WO2018186101A1 - Organic electroluminescence element and method for manufacturing organic electroluminescence element - Google Patents

Organic electroluminescence element and method for manufacturing organic electroluminescence element Download PDF

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WO2018186101A1
WO2018186101A1 PCT/JP2018/008977 JP2018008977W WO2018186101A1 WO 2018186101 A1 WO2018186101 A1 WO 2018186101A1 JP 2018008977 W JP2018008977 W JP 2018008977W WO 2018186101 A1 WO2018186101 A1 WO 2018186101A1
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light emitting
compound
layer
emitting layer
organic
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PCT/JP2018/008977
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French (fr)
Japanese (ja)
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威人 並川
顕一 田畑
井上　暁
康生 宮田
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コニカミノルタ株式会社
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Priority to JP2019511108A priority Critical patent/JP6941160B2/en
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • H10K50/12—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising dopants
    • H10K50/121—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising dopants for assisting energy transfer, e.g. sensitization
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/10—Apparatus or processes specially adapted to the manufacture of electroluminescent light sources
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2101/00—Properties of the organic materials covered by group H10K85/00
    • H10K2101/10—Triplet emission
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers

Definitions

  • the present invention relates to an organic electroluminescence element and a method for manufacturing the organic electroluminescence element. More specifically, the present invention relates to an organic electroluminescent device having good luminous efficiency and luminance half life even when driven at high luminance (high current density) and a method for manufacturing the organic electroluminescent device.
  • EL organic electroluminescence
  • An organic EL element has a structure in which a light-emitting layer containing a compound that emits light (hereinafter also referred to as “light-emitting material”) is sandwiched between a cathode and an anode, and recombines by injecting electrons and holes into the light-emitting layer.
  • This is an element that generates excitons (excitons) by light emission, and emits light by utilizing light emission (fluorescence / phosphorescence) when the excitons are deactivated.
  • Such an organic EL element can emit light at a low voltage of several to several tens of volts, and further has a wide viewing angle and high visibility because it is a self-luminous type.
  • the organic EL element is a thin-film type complete solid-state element, it has attracted attention from the viewpoints of space saving and portability.
  • an organic EL element capable of emitting light with better luminous efficiency, luminance and chromaticity is desired.
  • organic EL devices have two types of emission methods: “phosphorescence emission” that emits light when returning from the triplet excited state to the ground state, and “fluorescence emission” that emits light when returning from the singlet excited state to the ground state. Two ways are known.
  • thermoally activated delayed fluorescence where a reverse intersystem crossing from a triplet exciton to a singlet exciton, hereinafter, also referred to as “RISC” occurs.
  • thermally excited delayed fluorescence Thermally Activated Delayed Fluorescence (hereinafter abbreviated as “TADF” where appropriate) and the possibility of use in organic EL devices has been reported (for example, (See Patent Document 1, Non-Patent Document 1, and Non-Patent Document 2.)
  • TADF Thermally Activated Delayed Fluorescence
  • the phosphorescence and TADF methods are excellent.
  • the phosphorescence method and the TADF method still have room for improvement in terms of lifetime and color purity, especially for blue light emission, particularly pure blue or deep blue, which requires a short emission wavelength. No practically satisfactory level of color purity has been found.
  • the blue phosphorescent compound has a higher energy level (hereinafter also simply referred to as “level”) than that of red or green, and has a low level of quenching generated during electric field driving. This is because energy transfer to a substance is easy.
  • the blue phosphorescent compound has an emission decay lifetime ⁇ of about several ⁇ s to several tens of ⁇ s, which is 2 to 4 orders longer than the fluorescence lifetime of the fluorescent material.
  • the blue phosphorescent compound since the blue phosphorescent compound has a high triplet excited state level, the emission spectrum from the blue phosphorescent compound and the absorption spectrum of the quencher are likely to overlap, and the energy transfer rate is large. It has become.
  • phosphorescent compounds and TADF compounds having a long emission decay lifetime (on the order of microseconds) and TADF compounds are easily quenched by a quencher (quenching substance), and the luminance half-life of the organic EL element (hereinafter, referred to as the “luminescence half-life”). Simply referred to as “half-life”).
  • one of the factors that cause a reduction in the half-life of the organic EL element is heat generation during driving.
  • the excitation energy generated by recombination of holes and electrons in the light-emitting layer is not necessarily consumed as light emission, but part of it is deactivated as heat.
  • the released heat is accumulated in the element.
  • decomposition and aggregation of the compound contained in the organic EL element occur, quencher generation accompanying it, fluctuations in film physical properties, and the like.
  • carrier balance due to exciton quenching and film physical property fluctuations due to the quencher occurs.
  • the collapse of the brightness causes a reduction in luminance and half-life.
  • the emission efficiency of the organic EL element has been proposed to improve luminous efficiency by a method in which a phosphorescent compound and a fluorescent compound are contained in one light emitting layer.
  • a method in which a phosphorescent compound and a fluorescent compound are contained in one light emitting layer For example, refer to Patent Document 2.
  • the value of the external extraction quantum efficiency is as low as 3.3%, which does not exceed the theoretical limit value of the fluorescent light emitting device, and is not at a practical level. Also, the roll-off was great.
  • JP 2013-116975 A Japanese translation of PCT publication No. 2003-520391
  • the present invention has been made in view of the above-described problems and circumstances, and the problem to be solved is that the luminance half-life can be improved even when driven at high luminance (high current density), and the luminous efficiency is also excellent.
  • An organic electroluminescence device is provided.
  • the present inventor includes a specific phosphorescent compound and a fluorescent compound in the light emitting layer in the process of examining the cause of the above problem, and the like. Brightness is enhanced by promoting Ferster-type energy transfer to the fluorescent compound and maintaining the emission decay lifetime ⁇ of the single light emitting layer and the absolute quantum yield PLQE ( ⁇ ) of the single light emitting layer at the specified values. It has been found that even when driven at (high current density), the luminance half-life can be improved and the light emission efficiency can be improved, leading to the present invention. That is, the said subject which concerns on this invention is solved by the following means.
  • An organic electroluminescence device having a light emitting layer,
  • the light emitting layer contains a phosphorescent compound and a fluorescent compound,
  • the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound have an overlap,
  • the light emission decay lifetime ⁇ of the light emitting layer satisfies the following formula (1):
  • the absolute quantum yield PLQE ⁇ of the light emitting layer single layer satisfies the following formula (2):
  • the organic electroluminescent element whose Stokes shift of the said fluorescent compound is 0.1 eV or less.
  • the excitation energy generated on the phosphorescent compound can be rapidly transferred to the fluorescent compound by Forster-type energy transfer or Dexter-type energy transfer. It can be transferred to a fluorescent compound and consumed.
  • the emission decay lifetime of the phosphorescent compound is shortened to the order of sub-microseconds to nanoseconds. Therefore, from the formula (A), quenching with respect to the quencher is difficult, and the half-life is improved.
  • TTA triplet-triplet annihilation
  • triplet-polaron exciton annihilation is less likely to occur, and roll-off is improved.
  • TPA triplet-polaron exciton annihilation
  • the present inventor has examined that, in the above-described continuous driving at a high current, the process of excitation and light emission is repeated in a state where the exciton density is high, so that the heat accumulated in the organic EL element is continuously low in current. It has been found that the conventional method of adding a fluorescent compound to a light emitting layer containing a phosphorescent compound that is larger than driving (for example, see Patent Document 2) cannot sufficiently suppress the above-described fluctuations in film properties. It was. Furthermore, when the present inventors diligently studied, by adding a compound having a small Stokes shift as a fluorescent light emitting compound, heat generation is further suppressed even at high current density driving, fluctuation of film physical properties is suppressed, and half life is reduced. I found out that I could do better. The detailed reason is described below. As a result, since the deterioration rate can be further reduced, the following half-life acceleration coefficient n can be reduced.
  • the acceleration coefficient is n in the following formula (B).
  • t 1 / t 2 (L 1 / L 2 ) ⁇ n (B) [L 1: current density 2.5 mA / cm 2 upon application of the initial luminance L 2: current density 16.25mA / cm 2 applied during the initial luminance t 1: the luminance L 1 (low current 2.5 mA / cm 2) T 2 : Half life at luminance L 2 (high current 16.25 mA / cm 2 )]
  • a small Stokes shift means a small change in molecular structure between the excited state and the ground state. This can be said that the difference between the excitation energy and the emission energy is small, that is, the energy released as heat without contributing to the emission is small (see FIG. 1A).
  • a large Stokes shift means that the energy released as heat is large because the molecular structure varies greatly between the excited state and the ground state, and the difference between the excited energy and the emitted energy is also large. (See FIG. 1B.) Therefore, by using a fluorescent compound having a small Stokes shift, generation of heat can be suppressed even in high current driving with a high exciton density, and fluctuations in film properties over time can be suppressed.
  • the excitation energy generated in the light emitting layer emits light mainly from a fluorescent compound.
  • the amount of the fluorescent light-emitting compound added is small, the excitation energy generated in the light-emitting layer is collected in the fluorescent light-emitting compound, so even if the amount added is small, it cannot be ignored as a film quality variation factor.
  • the Stokes shift of the fluorescent compound is preferably small, specifically 0.1 eV or less.
  • the inventor of the present invention has disclosed that the emission decay lifetime ⁇ of the light emitting layer single layer is shorter than the phosphorescence emission decay lifetime ⁇ 0 (Equation (1)), and the absolute quantum yield ⁇ of the light emitting layer single layer is phosphorescent. It has been found that the acceleration coefficient of the luminance half-life with respect to the applied current can be further reduced within a specific range (equation (2)) with respect to the absolute quantum yield ( ⁇ 0 ) of the single film of the active compound.
  • the phosphorescent compound emits fluorescence by transferring the excitation energy in the triplet excited state of the phosphorescent compound to the singlet excited state of the fluorescent compound.
  • Dexter energy transfer can occur from the triplet excited state of the phosphorescent compound to the triplet excited state of the fluorescent compound (FIG. 2). reference.).
  • the fluorescence emission compound is deactivated by non-luminescence from the triplet excited state, and thus the absolute quantum yield (that is, the absolute quantum yield ⁇ of the single light emitting layer) is lowered.
  • the absolute quantum yield ⁇ of the light emitting layer is higher.
  • a practical phosphorescent compound has a high absolute quantum yield close to 100% (that is, the absolute quantum yield ⁇ 0 of a single film of the phosphorescent compound), and contains a fluorescent compound.
  • the main factor for efficiently developing Forster energy transfer is to increase the overlap between the emission spectrum of the energy donor (phosphorescent compound) and the absorption spectrum of the energy acceptor (fluorescent compound). is there. Therefore, in the present invention, it is essential that the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound have an overlap.
  • the Forster energy transfer is inversely proportional to the sixth power of the intermolecular distance R as shown in the following equation (F).
  • Dexter type energy transfer shows exponential decay with respect to the intermolecular distance R as shown in the following equation (D) (Reference: Basic Chemistry Course, Photochemistry I Haruo Inoue, Katsuhiko Takagi, Masako Sasaki, Park Bell) Co-authored with Earthquake)
  • k ET represents the energy transfer speed.
  • the organic electroluminescent device of the present invention is an organic electroluminescent device having a light emitting layer, wherein the light emitting layer contains a phosphorescent compound and a fluorescent compound, and an emission spectrum of the phosphorescent compound and The absorption spectrum of the fluorescent compound has an overlap, the emission decay lifetime ⁇ of the single light emitting layer satisfies the above formula (1), and the absolute quantum yield PLQE ⁇ of the single light emitting layer is The above formula (2) is satisfied, and the Stokes shift of the fluorescent compound is 0.1 eV or less.
  • This feature is a technical feature common to or corresponding to the following embodiments.
  • the present invention can provide an organic electroluminescence device that can have a good luminance half-life and good luminous efficiency even when driven at high luminance (high current density).
  • the phosphorescent compound and the fluorescent compound satisfy the above formula (3) or the above formula (4), thereby keeping the external extraction efficiency (EQE) high. It is preferable because it is possible.
  • the content (% by mass) of the fluorescent compound is more than the content (% by mass) of the phosphorescent compound. Less is preferable because the external extraction quantum efficiency and the half life can be improved.
  • the content of the fluorescent light emitting compound is 5% by mass or less to improve the external extraction quantum efficiency and the half life. This is preferable because it is possible.
  • the light emitting layer can be produced by a dry process or a wet process.
  • a wet process not only can the restrictions imposed on the shape and size of the element be reduced, but also an organic electroluminescent element can be manufactured by a cheaper manufacturing process.
  • ⁇ is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.
  • the organic electroluminescence device of the present invention is an organic electroluminescence device having a light emitting layer,
  • the light emitting layer contains a phosphorescent compound and a fluorescent compound,
  • the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound have an overlap
  • the emission decay lifetime ⁇ of the light emitting layer single layer satisfies the following formula (1):
  • the absolute quantum yield PLQE ( ⁇ ) of the single light emitting layer satisfies the following formula (2):
  • the Stokes shift of the said fluorescent compound is 0.1 eV or less,
  • the organic electroluminescent element characterized by the above-mentioned.
  • the emission spectrum of the phosphorescent compound according to the present invention and the absorption spectrum of the fluorescent compound have an overlap.
  • the fact that the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound have an overlap means that the emission spectrum of the phosphorescent compound and the absorption located on the longest wavelength side of the fluorescent compound. It means that the belt overlaps.
  • the magnitude of the overlap of each spectrum is called an overlap integral value and is calculated by the following equation (OI).
  • f D is a normalized donor (energy donor, phosphorescent compound) emission spectrum
  • ⁇ A is a molar extinction coefficient of the acceptor (energy acceptor, fluorescent compound).
  • ⁇ indicates a wavelength.
  • J represents an overlap integral value.
  • the Stokes shift of the fluorescent compound is 0.1 eV or less, and the minimum value is 0 eV.
  • the Stokes shift refers to the energy difference (or wavelength difference) between the absorption maximum and the emission fluorescence maximum.
  • the maximum absorption wavelength ⁇ abs (nm) of the absorption band on the longest wave side of the solution absorption spectrum and the maximum emission wavelength ⁇ em (nm) of the shortest wave side of the solution emission spectrum are represented by energy ( eV) and obtained from the difference.
  • the maximum absorption wavelength ⁇ abs and the maximum emission wavelength ⁇ em of the fluorescent compound can be measured using an ultraviolet-visible-infrared spectrophotometer (for example, U-570 manufactured by JASCO Corporation).
  • the temperature of each solution in the measurement of the maximum absorption wavelength ⁇ abs and the maximum emission wavelength ⁇ em is 23 ° C.
  • a practical phosphorescent compound has a high absolute quantum yield close to 100% (that is, an absolute quantum yield ⁇ 0 of a single film of the phosphorescent compound), and a fluorescent compound is added. Even It is desired to suppress a decrease in absolute quantum yield due to the above Dexter type energy transfer and maintain a high absolute quantum yield. From the above viewpoint, practical light-emitting element performance can be maintained if ⁇ / ⁇ 0 is in the range of 0.6 to 1.0. It should be noted that the maximum value of ⁇ / ⁇ 0 is 1.0 in the sense that ⁇ 0 of phosphorescence alone is maintained (does not decrease).
  • the probability that the charge injected into the light emitting layer is recombined on the phosphorescent compound is higher, and recombination is performed on the fluorescent compound. Can be suppressed. As a result, a decrease in external extraction efficiency (EQE) can be further suppressed.
  • the light emission decay lifetime of the single light emission layer may be measured by manufacturing a single film having the same structure as the light emission layer, such as a light emitting film for evaluation described later, and measuring the light emission decay lifetime of the single film.
  • the emission decay lifetime ⁇ can be measured by using a streak camera C4334 (manufactured by Hamamatsu Photonics).
  • the emission decay lifetime ⁇ 0 of the phosphorescent compound single film is the same as that of the evaluation light emitting film obtained by measuring the emission decay lifetime ⁇ except that the fluorescent emission compound is not contained. What is necessary is just to measure similarly to the light emission decay lifetime ⁇ of the light emitting layer.
  • the absolute quantum yield PLQE ( ⁇ ) of the light emitting layer is a single film having the same structure as that of the light emitting layer, such as a light-emitting film for evaluation. Can be measured. Note that PLQE can be measured by using an absolute quantum yield measuring apparatus C9920-02 (manufactured by Hamamatsu Photonics).
  • the absolute quantum yield PLQE ( ⁇ 0 ) of the phosphorescent compound single film is the absolute quantum yield P
  • a single film manufactured in the same manner except that no fluorescent light emitting compound is contained may be measured in the same manner as the light emission decay lifetime ⁇ of the light emitting layer single layer.
  • LUMO is the lowest unoccupied molecular orbital of a compound.
  • the LUMO energy level is energy in which electrons in the vacuum level fall to the LUMO of the compound and stabilize, and are defined as energy when the vacuum level is zero.
  • HOMO is the highest occupied molecular orbital of a compound.
  • the HOMO energy level is defined as a value obtained by multiplying the energy required to move electrons in the HOMO to the vacuum level by -1.
  • the light emitting layer contains a phosphorescent compound and a fluorescent compound.
  • the emission decay lifetime ⁇ of the single light emitting layer satisfies the above formula (1), and the absolute quantum yield PLQE ( ⁇ ) of the single light emitting layer satisfies the above formula (2).
  • the light emitting layer according to the present invention provides a field in which electrons and holes injected from an electrode or an adjacent layer (hereinafter also referred to as “adjacent layer”) are recombined to emit light via excitons.
  • the layer that emits light may be within the light emitting layer or at the interface between the light emitting layer and the adjacent layer.
  • the light emitting layer single layer concerning this invention means the light emitting film for evaluation produced as a spectrum measurement sample containing a host compound, a phosphorescent light emitting compound, and a fluorescent light emitting compound.
  • the specific manufacturing method of this light emitting film for evaluation will be described in detail in Examples.
  • the phosphorescent compound single film is a host compound, a phosphorescent compound, and a fluorescent compound, and includes the host compound, the phosphorescent compound, and the evaluation light emitting film.
  • the phosphorescent compound single film is a luminescent single film for evaluation for obtaining ⁇ / ⁇ 0 and ⁇ / ⁇ 0 according to the present invention, which does not contain a fluorescent compound. .
  • the light emitting layer can be a thin layer having a thickness of 30 nm or less. This is because the light emitting layer according to the present invention can achieve the effects of high efficiency and long life even when the thin layer and exciton density are high. In addition, it is preferable that the thickness of a light emitting layer is 2 nm or more.
  • phosphorescent compound can be used. Specific examples of known phosphorescent compounds that can be used in the present invention include, but are not limited to, compounds described in the following literature. Below, a blue phosphorescent compound is demonstrated as a specific example of the phosphorescent compound which can be used conveniently by this invention.
  • a blue phosphorescent compound as a specific example of the phosphorescent compound according to the present invention is a compound containing a heavy atom and capable of emitting light from a triplet excited state. As long as luminescence is observed, there is no particular limitation.
  • a blue phosphorescent compound represented by the following general formula (1) is preferable. Thereby, a blue phosphorescent compound having more exciton stability can be produced.
  • M represents Ir or Pt.
  • a 1 , A 2 , B 1 and B 2 each independently represent a carbon atom or a nitrogen atom.
  • Ring Z 1 is a 6-membered aromatic hydrocarbon ring or 5-membered or 6-membered aromatic heterocycle formed together with A 1 and A 2 , or an aromatic condensed ring containing at least one of these rings Represents.
  • Ring Z 2 represents a 5-membered or 6-membered aromatic heterocycle formed together with B 1 and B 2 , or an aromatic condensed ring containing at least one of these rings.
  • the carbon atom contained in the ring Z 1 and the ring Z 2 may be a carbene carbon atom.
  • Ring Z 1 and ring Z 2 may each independently have a substituent. By substituents of the ring Z 1 and the ring Z 2 are attached, may form a condensed ring structure, ligands each other represented by the ring Z 1 and the ring Z 2 may be linked .
  • L represents a monoanionic bidentate ligand coordinated to M and may have a substituent.
  • m represents an integer of 0-2.
  • n represents an integer of 1 to 3.
  • M + n is 3 when M is Ir, and m + n is 2 when M is Pt.
  • the ligands or Ls represented by ring Z 1 and ring Z 2 may be the same or different, and the coordination represented by ring Z 1 and ring Z 2 The child and L may be connected.
  • Ring Z 2 is preferably a 5-membered aromatic heterocycle, and at least one of B 1 and B 2 is preferably a nitrogen atom.
  • the general formula (1) is preferably represented by the following general formula (DP-1).
  • M, A 1 , A 2 , B 1 , B 2 , rings Z 1 , L, m and n are M, A 1 , A 2 , B in the general formula (1). 1 , B 2 , synonymous with rings Z 1 , L, m and n.
  • B 3 to B 5 are an atomic group forming an aromatic heterocyclic ring, and each independently represents a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom which may have a substituent.
  • substituents that B 3 to B 5 have include the same groups as the substituents that the ring Z 1 and the ring Z 2 have in General Formula (1).
  • the aromatic heterocycle formed by B 1 to B 5 in the general formula (DP-1) is represented by any of the following general formulas (DP-1a), (DP-1b) and (DP-1c) It is preferable.
  • * 1 represents a binding site with A 2 in the general formula (DP-1), and * 2 represents a binding site with M.
  • Rb 3 to Rb 5 represent a hydrogen atom or a substituent, and the substituent represented by Rb 3 to Rb 5 has the same meaning as the substituents of the ring Z 1 and the ring Z 2 in the general formula (1).
  • Groups. B 4 and B 5 in the general formula (DP-1a) are a carbon atom or a nitrogen atom, and more preferably at least one is a carbon atom.
  • B 3 to B 5 in the general formula (DP-1b) are carbon atoms or nitrogen atoms, and more preferably at least one is a carbon atom.
  • B 3 and B 4 in the general formula (DP-1c) are a carbon atom or a nitrogen atom, more preferably at least one is a carbon atom, and the substituents represented by Rb 3 and Rb 4 are further bonded to each other. It is more preferable that a condensed ring structure is formed, and the newly formed condensed ring structure is preferably an aromatic ring, and includes a benzimidazole ring, an imidazopyridine ring, an imidazopyrazine ring, or a purine ring. Either is preferable.
  • Rb 5 is preferably an alkyl group or an aryl group, and more preferably a phenyl group.
  • the carbon atoms of the ring Z 1 and the ring Z 2 are carbene carbon atoms (specifically, when they are carbene complexes), for example, WO 2005 / No. 0193373, International Publication No. 2006/056418, International Publication No. 2005/113704, International Publication No. 2007/115970, International Publication No. 2007/1155981, and International Publication No. 2008/000727.
  • the carbene complex is preferably used.
  • blue phosphorescent compounds and other color phosphorescent compounds that can be used in the present invention can be appropriately selected from known compounds used in the light emitting layer of an organic EL device.
  • Specific examples of known blue phosphorescent compounds and other color phosphorescent compounds that can be used in the present invention include compounds described in the following documents, but are not limited thereto. Absent. Nature 395, 151 (1998), Appl. Phys. Lett. 78, 1622 (2001), Adv. Mater. 19, 739 (2007), Chem. Mater. 17, 3532 (2005), Adv. Mater. 17, 1059 (2005), International Publication No. 2009/100991, International Publication No. 2008/101842, International Publication No. 2003/040257, US Patent Publication No.
  • Patent Publication No. 2003/0152802 U.S. Patent No. 7090928, Angew. Chem. lnt. Ed. 47, 1 (2008), Chem. Mater. 18, 5119 (2006), Inorg. Chem. 46, 4308 (2007), Organometallics 23, 3745 (2004), Appl. Phys. Lett. 74, 1361 (1999), International Publication No. 2002/002714, International Publication No. 2006/009024, International Publication No. 2006/056418, International Publication No. 2005/019373, International Publication No. 2005/123873, International Publication No. 2005/123873, International Publication No. 2007/004380, International Publication No. 2006/082742, US Patent Publication No.
  • the fluorescent compound according to the present invention is a compound that can emit light from a singlet excited state, satisfies the formulas (1) and (2) as long as light emission from the singlet excited state is observed, and There is no particular limitation as long as the Stokes shift is 0.1 eV or less.
  • Examples of the fluorescent compound include anthracene derivatives, pyrene derivatives, chrysene derivatives, fluoranthene derivatives, perylene derivatives, fluorene derivatives, arylacetylene derivatives, styrylarylene derivatives, styrylamine derivatives, arylamine derivatives, boron complexes, coumarin derivatives, pyran. Derivatives, cyanine derivatives, croconium derivatives, squalium derivatives, oxobenzanthracene derivatives, fluorescein derivatives, rhodamine derivatives, pyrylium derivatives, perylene derivatives, polythiophene derivatives, rare earth complex compounds, and the like.
  • luminescent compound using delayed fluorescence include, for example, the compounds described in International Publication No. 2011/156793, Japanese Patent Application Laid-Open No. 2011-213643, Japanese Patent Application Laid-Open No. 2010-93181, and the like. Is not limited to these.
  • the content of the fluorescent compound When the content of the fluorescent compound is large, the light emission decay lifetime of the light emitting layer single layer becomes small, but the decrease in absolute quantum yield becomes remarkable. Therefore, it is preferable that the content is small. This is considered as follows. When the content of the fluorescent compound increases, the intermolecular distance between the phosphorescent compound and the fluorescent compound decreases, and the triplet of the fluorescent compound is lower than the triplet excited state of the phosphorescent compound. Since the Dexter-type energy transfer to the excited state increases, the absolute quantum yield decreases significantly (see FIG. 2). For this reason, the addition amount of the fluorescent compound is preferably small.
  • the content (% by mass) of the fluorescent compound is the phosphorous. Less than the content (% by mass) of the photoluminescent compound is preferable because the external extraction quantum efficiency and the half-life can be improved.
  • the content of the fluorescent compound is 5% by mass. The following is preferable.
  • the content is preferably 5% by mass or less, more preferably 0.9% by mass or less, and the lower limit is the absolute quantum yield of the single light emitting layer. From the viewpoint of maintaining a high rate, the smaller the content, the better. Thereby, an absolute quantum yield can be made favorable and by extension, external extraction quantum efficiency and a half life can be made more favorable.
  • the light emitting layer according to the present invention preferably contains a host compound in addition to the fluorescent compound and the phosphorescent compound.
  • the host compound according to the present invention is a compound mainly responsible for charge injection and transport in the light-emitting layer, and light emission itself is not substantially observed in the organic EL element.
  • the host compound is preferably a compound having a phosphorescence quantum yield of phosphorescence of less than 0.1 at room temperature (25 ° C.), and more preferably a compound having a phosphorescence quantum yield of less than 0.01.
  • the excited state energy of the host compound is preferably higher than the excited state energy of the phosphorescent compound contained in the same layer.
  • known host compounds may be used alone or in combination. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient.
  • the compound conventionally used with an organic EL element can be used. It may be a low molecular compound or a high molecular compound having a repeating unit, or a compound having a reactive group such as a vinyl group or an epoxy group.
  • known host compounds while having a hole transporting ability or an electron transporting ability, the emission of light is prevented from being increased in wavelength, and further, the organic EL element is stable against heat generation during high temperature driving or driving of the element.
  • Tg glass transition temperature
  • Tg is preferably 90 ° C. or higher, more preferably 120 ° C. or higher.
  • the glass transition point (Tg) is a value determined by a method based on JIS-K-7121 using DSC (Differential Scanning Calorimetry).
  • the host compound according to the present invention is preferably a compound having a structure represented by the following general formula (HA) or (HB).
  • Xa represents O or S.
  • Xb, Xc, Xd and Xe each independently represent a hydrogen atom, a substituent or a group having a structure represented by the following general formula (HC), and at least one of Xb, Xc, Xd and Xe is A group having a structure represented by the following general formula (HC) is represented, and at least one of the groups having a structure represented by the following general formula (HC) is a carbazolyl group.
  • L ′ represents a divalent linking group derived from an aromatic hydrocarbon ring or an aromatic heterocyclic ring.
  • n represents an integer of 0 to 3, and when n is 2 or more, a plurality of L ′ may be the same or different.
  • * Represents a binding site with the general formula (HA) or (HB).
  • Ar represents a group having a structure represented by the following general formula (HD).
  • Xf represents N (R ′), O or S.
  • E 1 to E 8 each represent C (R ′′) or N, and R ′ and R ′′ each represent a hydrogen atom, a substituent, or a bonding site with L ′ in the general formula (HC).
  • * Represents a binding site with L ′ in the general formula (HC).
  • Xb, Xc, Xd and Xe are represented by the general formula (HC), and more preferably Xc is represented by the general formula (HC).
  • Ar in the general formula (HC) represents a carbazolyl group which may have a substituent.
  • Examples of the substituents represented by Xb, Xc, Xd and Xe in the general formulas (HA) and (HB) and the substituents represented by R ′ and R ′′ in the general formula (HD) include the above general formula (DP ) And the same substituents that the ring Z1 and ring Z2 may have.
  • Examples of the aromatic hydrocarbon ring represented by L ′ in the general formula (HC) include a benzene ring, a p-chlorobenzene ring, a mesitylene ring, a toluene ring, a xylene ring, a naphthalene ring, an anthracene ring, an azulene ring, and an acenaphthene ring.
  • Examples of the aromatic heterocycle represented by L ′ in the general formula (HC) include a furan ring, a thiophene ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazole ring, an imidazole ring, a pyrazole ring, and a thiazole ring.
  • host compound according to the present invention include compounds applicable to the present invention in addition to the compound having the structure represented by the general formula (HA) or (HB). It is not specifically limited to.
  • JP-A-2015-38941 can also be suitably used.
  • the host compound used in the present invention may be used in an adjacent layer adjacent to the light emitting layer.
  • the light emitting layer according to the present invention is composed of a single layer or a plurality of layers, and when there are a plurality of light emitting layers, a non-light emitting intermediate layer may be provided between the light emitting layers.
  • a hole blocking layer also referred to as a hole blocking layer
  • an electron injection layer also referred to as a cathode buffer layer
  • An electron blocking layer also referred to as an electron barrier layer
  • a hole injection layer also referred to as an anode buffer layer
  • the electron transport layer according to the present invention is a layer having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. Moreover, you may be comprised by multiple layers.
  • the hole transport layer according to the present invention is a layer having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. Moreover, you may be comprised by multiple layers.
  • the layer excluding the anode and the cathode is also referred to as “organic layer”.
  • the organic EL element according to the present invention may be an element having a so-called tandem structure in which a plurality of light emitting units including at least one light emitting layer are stacked.
  • first light emitting unit / second light emitting unit / third light emitting unit / cathode Anode / first light emitting unit / intermediate layer / second light emitting unit / intermediate layer / third light emitting unit / cathode
  • first light emitting unit The second light emitting unit and the third light emitting unit may all be the same or different. Two light emitting units may be the same, and the remaining one may be different.
  • the third light emitting unit may not be provided, and on the other hand, a light emitting unit or an intermediate layer may be further provided between the third light emitting unit and the electrode.
  • a plurality of light emitting units may be laminated directly or via an intermediate layer, and the intermediate layer is generally an intermediate electrode, an intermediate conductive layer, a charge generation layer, an electron extraction layer, a connection layer, an intermediate layer.
  • a known material structure can be used as long as it is also called an insulating layer and has a function of supplying electrons to the anode-side adjacent layer and holes to the cathode-side adjacent layer.
  • Examples of the material used for the intermediate layer include ITO (indium tin oxide), IZO (indium zinc oxide), ZnO 2 , TiN, ZrN, HfN, TiO x , VO x , Conductive inorganic compound layers such as CuI, InN, GaN, CuAlO 2 , CuGaO 2 , SrCu 2 O 2 , LaB 6 , RuO 2 and Al, two-layer films such as Au / Bi 2 O 3 , SnO 2 / Ag / Sn O 2 , ZnO / Ag / ZnO, Bi 2 O 3 / Au / Bi 2 O 3 , TiO 2 / TiN / TiO 2 , TiO 2 / ZrN / TiO 2 and other multilayer films, C 60 and other fullerenes, conductive organic layers such as oligothiophene, metal phthalocyanines, metal-free phthalocyanines, metal porphyrins, metal-free porphyrins
  • Preferred examples of the configuration within the light emitting unit include, for example, those obtained by removing the anode and the cathode from the configurations (1) to (7) mentioned in the above representative device configurations, but the present invention is not limited to these. Not.
  • tandem organic EL element examples include, for example, US Pat. No. 6,337,492, US Pat. No. 7,420,203, US Pat. No. 7,473,923, US Pat. No. 6,872,472, US Pat. No. 6,107,734. Specification, U.S. Pat. No. 6,337,492, International Publication No.
  • JP-A-2006-228712 JP-A-2006-24791, JP-A-2006-49393, JP-A-2006-49394 JP-A-2006-49396, JP-A-2011-96679, JP-A-2005-340187, JP-A-4711424, JP-A-34968681, JP-A-3884564, JP-A-42131169, JP-A-2010-192719.
  • Examples include constituent materials, but the present invention is not limited to these.
  • the electron transport layer is made of a material having a function of transporting electrons, and may have a function of transmitting electrons injected from the cathode to the light emitting layer.
  • the total thickness of the electron transport layer according to the present invention is not particularly limited, but is usually in the range of 2 nm to 5 ⁇ m, more preferably 2 to 500 nm, and further preferably 5 to 200 nm.
  • the organic EL element when the light generated in the light emitting layer is extracted from the electrode, the light extracted directly from the light emitting layer interferes with the light extracted after being reflected by the electrode from which the light is extracted and the electrode located at the counter electrode. It is known to wake up. When light is reflected by the cathode, this interference effect can be efficiently utilized by appropriately adjusting the total thickness of the electron transport layer between 5 nm and 1 ⁇ m.
  • the electron mobility of the electron transport layer is preferably 10 ⁇ 5 cm 2 / Vs or more.
  • the material used for the electron transport layer may be any of electron injecting or transporting properties and hole blocking properties, and can be selected from conventionally known compounds. Can be selected and used.
  • nitrogen-containing aromatic heterocyclic derivatives (carbazole derivatives, azacarbazole derivatives (one or more carbon atoms constituting the carbazole ring are substituted with nitrogen atoms), pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, pyridazine derivatives, Triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, azatriphenylene derivatives, oxazole derivatives, thiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, benzimidazole derivatives, benzoxazole derivatives, benzthiazole derivatives, etc.), dibenzofuran derivatives, And dibenzothiophene derivatives, silole derivatives, aromatic hydrocarbon ring derivatives (naphthalene derivatives, anthracene derivatives, triphenylene, etc.)
  • a metal complex having a quinolinol skeleton or a dibenzoquinolinol skeleton as a ligand such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7- Dibromo-8-quinolinol) aluminum, tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc.
  • a metal complex in which the central metal is replaced with In, Mg, Cu, Ca, Sn, Ga, or Pb can also be used as the electron transport material.
  • metal-free or metal phthalocyanine or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material.
  • known distyrylpyrazine derivatives used for the light emitting layer can also be used as an electron transporting material, and inorganic materials such as n-type-Si and n-type-SiC can be used as well as the hole injection layer and the hole transport layer.
  • a semiconductor can also be used as an electron transport material.
  • a polymer material in which these materials are introduced into a polymer chain or these materials as a polymer main chain can be used.
  • the electron transport layer may be doped with a doping material as a guest material to form an electron transport layer having a high n property (electron rich).
  • the doping material include n-type dopants such as metal complexes and metal compounds such as metal halides.
  • Specific examples of the electron transport layer having such a structure include, for example, JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J. Pat. Appl. Phys. , 95, 5773 (2004) and the like.
  • More preferable electron transport materials in the present invention include pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, triazine derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, carbazole derivatives, azacarbazole derivatives, and benzimidazole derivatives.
  • the electron transport material may be used alone or in combination of two or more.
  • the hole blocking layer is a layer having a function of an electron transport layer in a broad sense, and is preferably made of a material having a function of transporting electrons and a small ability to transport holes, and transporting electrons while transporting holes. The probability of recombination of electrons and holes can be improved by blocking.
  • the structure of the electron transport layer described above can be used as a hole blocking layer according to the present invention, if necessary.
  • the hole blocking layer provided in the organic EL device of the present invention is preferably provided adjacent to the cathode side of the light emitting layer.
  • the thickness of the hole blocking layer according to the present invention is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.
  • the material used for the hole blocking layer As the material used for the hole blocking layer, the material used for the above-described electron transport layer is preferably used, and the above-described host compound according to the present invention and other materials used as the host compound are also used for the hole blocking layer. Preferably used.
  • the electron injection layer (also referred to as “cathode buffer layer”) according to the present invention is a layer provided between the cathode and the light emitting layer in order to lower the driving voltage and improve the light emission luminance. It is described in detail in Chapter 2 “Electrode Materials” (pages 123 to 166) of the second edition of “The Forefront of Industrialization (issued by NTT Corporation on November 30, 1998)”.
  • the electron injection layer may be provided as necessary, and may be present between the cathode and the light emitting layer or between the cathode and the electron transport layer as described above.
  • the electron injection layer is preferably a very thin film, and the thickness is preferably in the range of 0.1 to 5 nm, depending on the material. Moreover, the nonuniform film
  • JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like Specific examples of materials preferably used for the electron injection layer are as follows. , Metals typified by strontium and aluminum, alkali metal compounds typified by lithium fluoride, sodium fluoride, potassium fluoride, etc., alkaline earth metal compounds typified by magnesium fluoride, calcium fluoride, etc., oxidation Examples thereof include metal oxides typified by aluminum, metal complexes typified by lithium 8-hydroxyquinolate (Liq), and the like. Further, the above-described electron transport material can also be used.
  • the materials used for the electron injection layer may be used alone or in combination of two or more.
  • the hole transport layer is made of a material having a function of transporting holes and may have a function of transmitting holes injected from the anode to the light emitting layer.
  • the total thickness of the hole transport layer according to the present invention is not particularly limited, but is usually in the range of 5 nm to 5 ⁇ m, more preferably 2 to 500 nm, and further preferably 5 nm to 200 nm.
  • a material used for the hole transport layer (hereinafter referred to as a hole transport material), any material that has either a hole injection property or a transport property or an electron barrier property may be used. Any one can be selected and used.
  • porphyrin derivatives for example, porphyrin derivatives, phthalocyanine derivatives, oxazole derivatives, oxadiazole derivatives, triazole derivatives, imidazole derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, hydrazone derivatives, stilbene derivatives, polyarylalkane derivatives, triarylamine derivatives, carbazole derivatives , Indolocarbazole derivatives, isoindole derivatives, acene derivatives such as anthracene and naphthalene, fluorene derivatives, fluorenone derivatives, and polyvinyl carbazole, polymer materials or oligomers with aromatic amines introduced into the main chain or side chain, polysilane, conductive And polymer (for example, PEDOT: PSS, aniline copolymer, polyaniline, polythiophene, etc.).
  • PEDOT PSS, aniline copolymer, polyaniline
  • triarylamine derivatives examples include benzidine type typified by ⁇ -NPD (4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl), starburst type typified by MTDATA, Examples include compounds having fluorene or anthracene in the triarylamine-linked core.
  • hexaazatriphenylene derivatives such as those described in JP-T-2003-519432 and JP-A-2006-135145 can also be used as a hole transport material.
  • a hole transport layer having a high p property doped with impurities can also be used.
  • examples thereof include JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J. Pat. Appl. Phys. 95, 5773 (2004), and the like.
  • the above-mentioned materials can be used as the hole transport material, but a triarylamine derivative, a carbazole derivative, an indolocarbazole derivative, an azatriphenylene derivative, an organometallic complex, or an aromatic amine is introduced into the main chain or side chain.
  • the polymer materials or oligomers used are preferably used.
  • preferable hole transport materials used in the organic EL device of the present invention include, but are not limited to, the compounds described in the following documents in addition to the documents listed above.
  • the hole transport material may be used alone or in combination of two or more.
  • the electron blocking layer is a layer having a function of a hole transport layer in a broad sense, and is preferably made of a material having a function of transporting holes and a small ability to transport electrons, and transporting electrons while transporting holes. The probability of recombination of electrons and holes can be improved by blocking.
  • the above-described configuration of the hole transport layer can be used as an electron blocking layer according to the present invention, if necessary.
  • the electron blocking layer provided in the organic EL device of the present invention is preferably provided adjacent to the anode side of the light emitting layer.
  • the thickness of the electron blocking layer according to the present invention is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.
  • the material used for the electron blocking layer As the material used for the electron blocking layer, the material used for the above-described hole transport layer is preferably used, and the above-described host compound according to the present invention and other materials used as the host compound are also preferable for the electron blocking layer. Used.
  • the hole injection layer (also referred to as “anode buffer layer”) according to the present invention is a layer provided between the anode and the light emitting layer for the purpose of lowering the driving voltage and improving the light emission luminance. It is described in detail in Volume 2, Chapter 2, “Electrode Materials” (pages 123 to 166) of “The Forefront of Industrialization (issued by NTT Corporation on November 30, 1998)”.
  • the hole injection layer may be provided as necessary, and may be present between the anode and the light emitting layer or between the anode and the hole transport layer as described above.
  • the details of the hole injection layer are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069, etc.
  • Examples of materials used for the hole injection layer include: Examples thereof include materials used for the above-described hole transport layer.
  • phthalocyanine derivatives typified by copper phthalocyanine, hexaazatriphenylene derivatives, metal oxides typified by vanadium oxide, amorphous carbon as described in JP-T-2003-519432, JP-A-2006-135145, etc.
  • the materials used for the hole injection layer described above may be used alone or in combination of two or more.
  • the organic layer in the present invention described above may further contain other additives.
  • halogen elements and halogenated compounds such as bromine, iodine and chlorine, alkali metals and alkaline earth metals such as Pd, Ca and Na, transition metal compounds, complexes and salts.
  • the content of other additives can be arbitrarily determined, but is preferably 1000 ppm or less, more preferably 500 ppm or less, and still more preferably 50 ppm or less, based on the total mass% of the contained layer. It is.
  • ⁇ Method of forming organic layer ⁇ As a method for producing the organic electroluminescence device according to the present invention, a known method can be suitably employed.
  • the light-emitting layer may be formed using a wet process or a dry process. preferable.
  • a method for forming an organic layer (hole injection layer, hole transport layer, electron blocking layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) will be described below.
  • the method for forming the organic layer is not particularly limited, and conventionally known methods such as a vacuum deposition method such as a dry process, a wet process, and the like can be used.
  • the organic layer may be formed by using a wet process or a dry process.
  • the organic layer is preferably a layer formed by a wet process. That is, it is preferable to produce an organic EL element by a wet process.
  • a uniform film (coating film) can be easily obtained, and effects such as the difficulty of generating pinholes can be achieved.
  • membrane (coating film) here is a thing of the state dried after application
  • Examples of the wet process include spin coating, casting, ink jet, printing, die coating, blade coating, roll coating, spray coating, curtain coating, and LB (Langmuir-Blodgett). From the viewpoint of obtaining a homogeneous thin film easily and high productivity, a method with high roll-to-roll method suitability such as a die coating method, a roll coating method, an ink jet method, and a spray coating method is preferable.
  • dry process examples include vapor deposition methods (resistance heating, EB method, etc.), sputtering methods, CVD methods, and the like.
  • liquid medium for dissolving or dispersing the material of the organic EL device examples include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene and xylene.
  • Aromatic hydrocarbons such as mesitylene and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin and dodecane, and organic solvents such as DMF and DMSO can be used.
  • a dispersion method it can be dispersed by a dispersion method such as ultrasonic wave, high shearing force dispersion or media dispersion.
  • vapor deposition conditions vary depending on the type of compound used, but generally a boat heating temperature of 50 to 450 ° C., a degree of vacuum of 10 ⁇ 6 to 10 ⁇ 2 Pa, and a vapor deposition rate of 0.01 to It is desirable to select appropriately within a range of 50 nm / second, a substrate temperature of ⁇ 50 to 300 ° C., and a thickness of 0.1 nm to 5 ⁇ m, preferably 5 to 200 nm.
  • the organic layer according to the present invention it is preferable to consistently produce from the hole injection layer to the cathode by a single evacuation, but it may be taken out halfway and subjected to different film forming methods. In that case, it is preferable to perform the work in a dry inert gas atmosphere.
  • anode in the organic EL element those having a work function (4 eV or more, preferably 4.5 V or more) of a metal, an alloy, an electrically conductive compound and a mixture thereof as an electrode material are preferably used.
  • electrode substances include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO 2 , and ZnO.
  • conductive transparent materials such as CuI, indium tin oxide (ITO), SnO 2 , and ZnO.
  • an amorphous material such as IDIXO (In 2 O 3 —ZnO) that can form a transparent conductive film may be used.
  • these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern of a desired shape may be formed by a photolithography method, or when pattern accuracy is not so required (about 100 ⁇ m or more) A pattern may be formed through a mask having a desired shape during the vapor deposition or sputtering of the electrode material.
  • a wet film forming method such as a printing method or a coating method can also be used.
  • the transmittance be greater than 10%, and the sheet resistance as the anode is several hundred ⁇ / sq. The following is preferred.
  • the thickness of the anode depends on the material, but is usually selected in the range of 10 nm to 1 ⁇ m, preferably 10 to 200 nm.
  • Electrode a material having a work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used.
  • electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al 2 O 3 ) Mixtures, indium, lithium / aluminum mixtures, aluminum, rare earth metals and the like.
  • a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this for example, a magnesium / silver mixture
  • a magnesium / aluminum mixture a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al 2 O 3 ) mixture, a lithium / aluminum mixture, aluminum and the like.
  • the cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering.
  • the sheet resistance as a cathode is several hundred ⁇ / sq. The following is preferable, and the thickness is usually selected in the range of 10 nm to 5 ⁇ m, preferably 50 to 200 nm.
  • the emission luminance is improved, which is convenient.
  • a transparent or semi-transparent cathode can be produced by producing the conductive transparent material mentioned in the description of the anode on the cathode after producing the metal with a thickness of 1 to 20 nm.
  • the support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention is not particularly limited in the type of glass, plastic, etc., and is transparent. May be opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film capable of giving flexibility to the organic EL element.
  • polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate ( CAP), cellulose esters such as cellulose acetate phthalate, cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic, or polyarylate, Arton (trade name, manufactured by JSR) or Appel (
  • the surface of the resin film may be formed with an inorganic film, an organic film, or a hybrid film of both, and the water vapor permeability (25 ⁇ 0.5 ° C.) measured by a method according to JIS K 7129-1992. And a relative humidity (90 ⁇ 2)% RH) of 0.01 g / (m 2 ⁇ 24 h) or less is preferable, and oxygen measured by a method in accordance with JIS K 7126-1987
  • a high barrier film having a permeability of 10 ⁇ 3 mL / (m 2 ⁇ 24 h ⁇ atm) or less and a water vapor permeability of 10 ⁇ 5 g / (m 2 ⁇ 24 h) or less is preferable.
  • the material for forming the barrier film may be any material that has a function of suppressing entry of elements that cause deterioration of elements such as moisture and oxygen.
  • silicon oxide, silicon dioxide, silicon nitride, or the like can be used.
  • the method for forming the barrier film is not particularly limited.
  • vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma polymerization A plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.
  • the opaque support substrate examples include metal plates such as aluminum and stainless steel, films, opaque resin substrates, ceramic substrates, and the like.
  • the external extraction quantum efficiency at room temperature of light emission of the organic EL device of the present invention is preferably 1% or more, and more preferably 5% or more.
  • the external extraction quantum efficiency (%) the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element ⁇ 100.
  • a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor may be used in combination.
  • sealing means used for sealing the organic EL element of the present invention include a method of bonding a sealing member, an electrode, and a support substrate with an adhesive.
  • a sealing member it should just be arrange
  • transparency and electrical insulation are not particularly limited.
  • Specific examples include a glass plate, a polymer plate / film, and a metal plate / film.
  • the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz.
  • the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone.
  • the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.
  • a polymer film and a metal film can be preferably used because the organic EL element can be thinned.
  • the polymer film has an oxygen permeability measured by a method according to JIS K 7126-1987 of 1 ⁇ 10 ⁇ 3 mL / (m 2 ⁇ 24 h ⁇ atm) or less, and a method according to JIS K 7129-1992.
  • the measured water vapor permeability (25 ⁇ 0.5 ° C., relative humidity (90 ⁇ 2)%) is preferably 1 ⁇ 10 ⁇ 3 g / (m 2 ⁇ 24 h) or less.
  • sealing member For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.
  • the adhesive include photocuring and thermosetting adhesives having reactive vinyl groups of acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. be able to.
  • hot-melt type polyamide, polyester, and polyolefin can be mentioned.
  • a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.
  • an organic EL element may deteriorate by heat processing, what can be adhesively cured from room temperature to 80 ° C. is preferable.
  • a desiccant may be dispersed in the adhesive.
  • coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.
  • the electrode and the organic layer are coated on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film.
  • the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen.
  • silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can.
  • a laminated structure of these inorganic layers and layers made of organic materials it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials.
  • the method of forming these films There are no particular limitations on the method of forming these films. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.
  • an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and liquid phase.
  • a vacuum can also be used.
  • a hygroscopic compound can also be enclosed inside.
  • hygroscopic compound examples include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate).
  • metal oxides for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide
  • sulfates for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate.
  • metal halides eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.
  • perchloric acids eg perchloric acid Barium, magnesium perchlorate, and the like
  • anhydrous salts are preferably used in sulfates, metal halides, and perchloric acids.
  • a protective film or a protective plate may be provided outside the sealing film or the sealing film on the side facing the support substrate with the organic layer interposed therebetween.
  • the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate.
  • the same glass plate, polymer plate / film, metal plate / film, etc. used for the sealing can be used, but the polymer film is light and thin. Is preferably used.
  • An organic electroluminescent element emits light inside a layer having a refractive index higher than that of air (with a refractive index of about 1.6 to 2.1), and about 15% to 20% of light generated in the light emitting layer. It is generally said that only light can be extracted. This is because light incident on the interface (interface between the transparent substrate and air) at an angle ⁇ greater than the critical angle causes total reflection and cannot be taken out of the device, or between the transparent electrode or light emitting layer and the transparent substrate. This is because light is totally reflected between the light and the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the direction of the side surface of the device.
  • a technique for improving the light extraction efficiency for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the transparent substrate and the air interface (for example, US Pat. No. 4,774,435), A method for improving efficiency by providing light condensing property (for example, Japanese Patent Laid-Open No. 63-134795), a method for forming a reflective surface on the side surface of an element (for example, Japanese Patent Laid-Open No. 1-220394), a substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the substrate and the light emitter (for example, Japanese Patent Laid-Open No.
  • the light extracted from the transparent electrode has a higher extraction efficiency to the outside as the refractive index of the medium is lower.
  • the low refractive index layer examples include aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally in the range of about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Further, it is preferably 1.35 or less.
  • the thickness of the low refractive index medium is preferably at least twice the wavelength in the medium. This is because the effect of the low-refractive index layer is reduced when the thickness of the low-refractive index medium is about the wavelength of light and the electromagnetic wave exuded by evanescent enters the substrate.
  • the method of introducing a diffraction grating into an interface that causes total reflection or in any medium has a feature that the effect of improving the light extraction efficiency is high.
  • This method uses the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction, such as first-order diffraction or second-order diffraction.
  • the light that cannot be emitted due to total internal reflection between layers is diffracted by introducing a diffraction grating into any layer or medium (in the transparent substrate or transparent electrode). , Trying to extract light out.
  • the diffraction grating to be introduced has a two-dimensional periodic refractive index. This is because light emitted from the light-emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. The light extraction efficiency does not increase so much.
  • the refractive index distribution a two-dimensional distribution
  • the light traveling in all directions is diffracted, and the light extraction efficiency is increased.
  • the position where the diffraction grating is introduced may be in any layer or in the medium (in the transparent substrate or the transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated.
  • the period of the diffraction grating is preferably in the range of about 1/2 to 3 times the wavelength of light in the medium.
  • the arrangement of the diffraction grating is preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.
  • the organic EL element of the present invention is processed to provide a structure on a microlens array, for example, on the light extraction side of the support substrate (substrate), or combined with a so-called condensing sheet, so that a specific direction, For example, the luminance in a specific direction can be increased by condensing light in the front direction with respect to the element light emitting surface.
  • a quadrangular pyramid having a side of 30 ⁇ m and an apex angle of 90 degrees is arranged two-dimensionally on the light extraction side of the substrate.
  • One side is preferably within a range of 10 to 100 ⁇ m. If it is smaller than this, the effect of diffraction is generated and colored, and if it is too large, the thickness becomes thick, which is not preferable.
  • the condensing sheet it is possible to use, for example, an LED backlight of a liquid crystal display device that has been put into practical use.
  • a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used.
  • BEF brightness enhancement film
  • a substrate may be formed with a ⁇ -shaped stripe having an apex angle of 90 degrees and a pitch of 50 ⁇ m, or the apex angle is rounded and the pitch is changed randomly. Other shapes may also be used.
  • a light diffusion plate / film may be used in combination with the light collecting sheet.
  • a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.
  • the organic EL element of the present invention can be used as a display device, a display, and various light emission sources.
  • lighting devices home lighting, interior lighting
  • clock and liquid crystal backlights billboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light
  • the light source of a sensor etc. are mentioned, It is not limited to this, Especially, it can use effectively for the use as a backlight of a liquid crystal display device, and a light source for illumination.
  • patterning may be performed by a metal mask, an ink jet printing method, or the like when forming a film, if necessary.
  • patterning only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned.
  • a conventionally known method is used. Can do.
  • FIG. 3 is a schematic perspective view showing an example of a configuration of a display device including the organic EL element of the present invention, and displays image information by light emission of the organic EL element, for example, a display such as a mobile phone FIG.
  • the display 1 includes a display unit A having a plurality of pixels, a control unit B that performs image scanning of the display unit A based on image information, and the like.
  • Control unit B is electrically connected to display unit A.
  • the control unit B sends a scanning signal and an image data signal to each of the plurality of pixels based on image information from the outside.
  • each pixel sequentially emits light according to the image data signal for each scanning line by the scanning signal, and the image information is displayed on the display unit A.
  • FIG. 4 is a schematic diagram of the display unit A shown in FIG.
  • the display unit A has a wiring unit including a plurality of scanning lines 5 and data lines 6, a plurality of pixels 3 and the like on a substrate.
  • the main components of the display unit A will be described below.
  • FIG. 4 shows a case where the light emitted from the pixel 3 is extracted in the direction of the white arrow (downward).
  • Each of the scanning lines 5 and the plurality of data lines 6 in the wiring portion is made of a conductive material.
  • the scanning lines 5 and the data lines 6 are orthogonal to each other in a grid pattern and are connected to the pixels 3 at the orthogonal positions (details are not shown).
  • the pixel 3 When the scanning signal is transmitted from the scanning line 5, the pixel 3 receives the image data signal from the data line 6 and emits light according to the received image data.
  • a full-color display is possible by arranging pixels in the red region, the green region, and the blue region as appropriate in parallel on the same substrate.
  • the non-light emitting surface of the organic EL device of the present invention is covered with a glass case, a 300 ⁇ m thick glass substrate is used as a sealing substrate, and an epoxy photocurable adhesive (LUX The track LC0629B) is applied, and this is overlaid on the cathode and brought into close contact with the transparent support substrate, irradiated with UV light from the glass substrate side, cured, sealed, and illuminated as shown in FIGS.
  • a device can be formed.
  • FIG. 5 shows a schematic diagram of a lighting device, and the organic EL element 101 of the present invention is covered with a glass cover 102 (in addition, the sealing operation with the glass cover is to bring the organic EL element 101 into contact with the atmosphere.
  • a glove box under a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas with a purity of 99.999% or higher).
  • FIG. 6 shows a cross-sectional view of the lighting device.
  • 105 denotes a cathode
  • 106 denotes an organic EL layer (light emitting unit)
  • 107 denotes a glass substrate with a transparent electrode.
  • the glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.
  • Example 1 [Production of Organic EL Elements 1-1 to 1-12] (Preparation of base material) A transparent substrate with an ITO (Indium Tin Oxide) film having a thickness of 150 nm formed on a glass substrate of 50 mm ⁇ 50 mm and a thickness of 0.7 mm, patterned, and this ITO transparent electrode was attached was subjected to ultrasonic cleaning with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.
  • ITO Indium Tin Oxide
  • This transparent substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus.
  • Each of the vapor deposition crucibles in the vacuum vapor deposition apparatus was filled with the constituent material of each layer in an amount optimal for device fabrication.
  • As the evaporation crucible a crucible made of a resistance heating material made of molybdenum or tungsten was used.
  • the compound of the light emitting layer was changed to 84.5% by volume, 15% by volume, and 0.5% by volume of the host compound H-1, the phosphorescent compound PD-1, and the fluorescent compound described in Table I, respectively.
  • it was co-deposited on the hole transport layer at a deposition rate of 0.06 nm / second to form a light emitting layer having a thickness of 30 nm.
  • the compound ALq3 was deposited thereon at a deposition rate of 0.1 nm / second to form an electron transport layer having a thickness of 30 nm.
  • the non-light-emitting surface side of the element on which the cathode is formed is covered with a can-shaped glass case in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more, and an electrode lead-out wiring is installed. 1 to 1-12 were produced.
  • a quartz substrate having a size of 50 mm ⁇ 50 mm and a thickness of 0.7 mm is ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.
  • the transparent substrate is then used as a substrate holder for a commercially available vacuum deposition apparatus. Fixed to.
  • the host compound H-1, the phosphorescent compound PD-1, and the respective fluorescent compounds used in the organic EL elements 1-1 to 1-12 were prepared. It filled so that it might become the amount similar to the case of this time.
  • the evaporation crucible used was made of a resistance heating material made of molybdenum. After depressurizing the inside of the vacuum evaporation system to a vacuum degree of 1 ⁇ 10 ⁇ 4 Pa, the host compound, phosphorescent compound, and fluorescent compound were 84.5% by volume, 15% by volume, and 0.5% by volume, respectively. In this way, vapor deposition was performed at a vapor deposition rate of 0.06 nm / second to prepare evaluation light-emitting films 1-1 to 1-12 having a film thickness of 30 nm.
  • the types of “host compounds”, “phosphorescent compounds” and “fluorescent compounds” contained in the evaluation light-emitting films 1-1 to 1-12, and the concentrations of the respective compounds are as follows. This corresponds to the elements 1-1 to 1-12.
  • a single film composed of the phosphorescent compound PD-1 and the host compound H-1 in the same manner except that no fluorescent compound is contained (
  • the phosphorescent compound single film PD-1 was produced by changing the content of the phosphorescent compound and increasing the host compound by the amount not containing the fluorescent compound.
  • the measurement of the solution absorption spectrum (maximum absorption wavelength ⁇ abs ) of the fluorescent compound was performed as follows. First, the fluorescent compound was dissolved in 2-methyltetrahydrofuran (2m-THF) (without stabilizer) to obtain a solution having a concentration of 1.0 ⁇ 10 ⁇ 5 mol / L. The obtained solution was put into a quartz cell (10 mm long square cell), and the absorbance in the wavelength region of 250 to 700 nm of the solution was measured using a spectrophotometer (HITACHI U-3300 spectrophotometer) (liquid). The temperature was 23 ° C.).
  • 2m-THF 2-methyltetrahydrofuran
  • the emission decay lifetime ⁇ and the emission decay lifetime ⁇ 0 were measured as follows, and ⁇ / ⁇ 0 was obtained.
  • the light emission decay lifetime ⁇ of the evaluation light emitting films 1-1 to 1-12 was measured. Specifically, the emission decay lifetimes ⁇ of the evaluation light-emitting films 1-1 to 1-12 were obtained by measuring transient PL characteristics.
  • a small fluorescent lifetime measuring device C11367-03 manufactured by Hamamatsu Photonics was used for measurement of transient PL characteristics. The attenuation component was measured in TCC900 mode using an 280 nm LED as an excitation light source.
  • Luminescence decay lifetime ⁇ 0 A light emission decay lifetime ⁇ 0 is obtained in the same manner as the measurement of the light emission decay lifetime ⁇ , except that the phosphorescent compound single film PD-1 is used instead of the evaluation light emission membrane 1-1 to 1-12. It was measured.
  • the absolute quantum yield PLQE ( ⁇ ) of the light-emitting films for evaluation 1-1 to 1-12 corresponding to the organic EL elements 1-1 to 1-12 was measured using an absolute quantum yield measuring device C9920-02 (manufactured by Hamamatsu Photonics). ).
  • the measurement of the maximum emission wavelength ⁇ em of the fluorescent compound was performed as follows. First, the fluorescent compound was dissolved in 2-methyltetrahydrofuran (2m-THF) to prepare 1 ⁇ 10 ⁇ 5 mol / L 2m-THF solution. The obtained solution was bubbled with nitrogen gas (N 2 ) for 10 minutes and then measured using a fluorometer (HITACHI F-7000) (liquid temperature was 23 ° C.). In the measurement, an emission spectrum was measured using the maximum absorption wavelength as excitation light, and the maximum maximum emission wavelength in the emission spectrum was defined as the maximum emission wavelength ⁇ em . When there are a plurality of emission peaks in the above wavelength range, the peak at the shortest wavelength side is defined as the emission peak.
  • the criteria for determining the half-life acceleration factor are as follows. ⁇ : Less than 1.4 (pass) ⁇ : 1.4 or more and less than 1.6 (failed) X: 1.6 or more (failed)
  • Example 2 [Production of Organic EL Elements 2-1 to 2-11] (Preparation of base material) A transparent substrate with an ITO (Indium Tin Oxide) film having a thickness of 150 nm formed on a glass substrate of 50 mm ⁇ 50 mm and a thickness of 0.7 mm, patterned, and this ITO transparent electrode was attached was subjected to ultrasonic cleaning with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.
  • ITO Indium Tin Oxide
  • this transparent substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus.
  • Each of the vapor deposition crucibles in the vacuum vapor deposition apparatus was filled with the constituent material of each layer in an amount optimal for device fabrication.
  • the crucible for vapor deposition used what was produced with the resistance heating material made from molybdenum.
  • the pressure was reduced to 1 ⁇ 10 ⁇ 4 Pa, heated by energizing a deposition crucible containing ⁇ -NPD, and deposited on the hole injection layer at a deposition rate of 0.1 nm / sec.
  • the hole transport layer was formed.
  • HB-1 was deposited on the light emitting layer at a deposition rate of 0.1 nm / second to form a 10 nm thick hole blocking layer.
  • Compound ET-1 was deposited on the hole blocking layer at a deposition rate of 0.1 nm / second to form an electron transport layer having a thickness of 30 nm.
  • the organic EL elements 2-2 and 2-6 had a Stokes shift of the fluorescent compound having a value larger than 0.1 eV.
  • the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound overlap, and the Stokes shift of the fluorescent compound is 0.1 eV. It was the following.
  • Example 3 [Production of Organic EL Elements 3-1 to 3-16] (Preparation of base material) First, an atmospheric pressure plasma discharge treatment having a configuration described in Japanese Patent Application Laid-Open No. 2004-68143 is formed on the entire surface of a polyethylene naphthalate film (hereinafter abbreviated as PEN) (manufactured by Teijin DuPont Films Ltd.) on the anode forming side. Using an apparatus, an inorganic gas barrier layer made of SiOx was formed to a thickness of 500 nm.
  • PEN polyethylene naphthalate film
  • a flexible base material having a gas barrier property with an oxygen permeability of 0.001 mL / (m 2 ⁇ 24 h) or less and a water vapor permeability of 0.001 g / (m 2 ⁇ 24 h) or less was produced.
  • ITO indium tin oxide
  • the base material on which the hole injection layer was formed was transferred to a nitrogen atmosphere using nitrogen gas (grade G1), and a coating liquid for forming a hole transport layer having the following composition was used to form a 5 m / After being applied for min and air-dried, it was kept at 130 ° C. for 30 minutes to form a 30 nm-thick hole transport layer.
  • nitrogen gas grade G1
  • the base material on which the hole transport layer was formed was applied at a coating speed of 5 m / min by a die coating method using a coating solution for forming a light emitting layer having the following composition, and naturally dried, and then 30 ° C. at 30 ° C. Holding for 5 minutes, a light emitting layer having a thickness of 50 nm was formed.
  • x is the concentration of the fluorescent compound shown in Table IV.
  • Host compound H-2 8.5-part by mass Phosphorescent compound PD-1 1.5 parts by mass Fluorescent compound shown in Table IV x parts by mass Isopropyl acetate 2000 parts by mass
  • the base material on which the light-emitting layer is formed is applied at a coating speed of 5 m / min by a die coating method using a coating solution for forming a hole blocking layer having the following composition, and is naturally dried, and then at 80 ° C. for 30 minutes.
  • the hole blocking layer having a thickness of 10 nm was formed.
  • the base material on which the hole blocking layer was formed was applied at a coating speed of 5 m / min by a die coating method using a coating liquid for forming an electron transport layer having the following composition, naturally dried, and then 30 ° C. at 30 ° C. Holding for 30 minutes, an electron transport layer having a thickness of 30 nm was formed.
  • ⁇ Coating liquid for electron transport layer formation > ET-1 6 parts by mass 1H, 1H, 3H-tetrafluoropropanol (TFPO) 2000 parts by mass
  • the substrate was attached to a vacuum deposition apparatus without being exposed to the atmosphere. Further, a molybdenum resistance heating boat containing sodium fluoride and potassium fluoride was attached to a vacuum vapor deposition apparatus, and the vacuum chamber was depressurized to 4 ⁇ 10 ⁇ 5 Pa. Thereafter, the boat was energized and heated, and sodium fluoride was deposited on the electron transport layer at 0.02 nm / second to form a thin film having a thickness of 1 nm. Similarly, potassium fluoride was deposited on the sodium fluoride thin film at 0.02 nm / second to form an electron injection layer having a thickness of 1.5 nm.
  • An agent layer was provided, and a laminate of a polyethylene terephthalate (PET) film having a thickness of 12 ⁇ m was prepared.
  • PET polyethylene terephthalate
  • thermosetting adhesive as a sealing adhesive was uniformly applied at a thickness of 20 ⁇ m along the adhesive surface (shiny surface) of the aluminum foil of the sealing substrate using a dispenser. This was dried under a vacuum of 100 Pa or less for 12 hours. Further, the sealing substrate is moved to a nitrogen atmosphere having a dew point temperature of ⁇ 80 ° C. or less and an oxygen concentration of 0.8 ppm, and is dried for 12 hours or more so that the moisture content of the sealing adhesive is 100 ppm or less. It was adjusted.
  • thermosetting adhesive an epoxy adhesive mixed with the following (A) to (C) was used.
  • the sealing substrate was closely attached to the laminate, and was tightly sealed using a pressure-bonding roll under pressure-bonding conditions of a pressure-rolling roll temperature of 100 ° C., a pressure of 0.5 MPa, and an apparatus speed of 0.3 m / min. .
  • the emission decay lifetimes ⁇ and ⁇ 0 , the absolute quantum yield PLQE ( ⁇ ), and the absolute quantum yield PLQE ( ⁇ 0 ) were measured.
  • the organic EL elements 3-2 to 3-16 satisfied the expressions (1) and (2) and also satisfied the expression (3) or (4).
  • the light emitting film for evaluation used for the measurement is the type of “host compound”, “phosphorescent light emitting compound” and “fluorescent light emitting compound” in Example 1, and the content (volume%) of each compound.
  • the phosphorescent compound single film is formed from the phosphorescent compound PD-1 and the host compound H-2 in the same manner except that the fluorescent compound is not included in the production of the evaluation light emitting film.
  • a single membrane was produced. In the production of a single film of the phosphorescent compound, the content of the phosphorescent compound was not changed, and the host compound was increased by the amount not containing the fluorescent compound.
  • Example 1 the presence or absence of overlap between the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound and the Stokes shift of the fluorescent compound were examined. As for 3-16, it is confirmed that the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound overlap each other, and the Stokes shift of the fluorescent compound is 0.1 eV or less. It was done.
  • the present invention can be used for an organic electroluminescence element and a method for producing an organic electroluminescence element.

Abstract

The purpose of the present invention is to provide an organic electroluminescence element in which an appropriate luminance half-life can be achieved even when operating at high luminance (high current density), and favorable luminous efficiency is exhibited. The organic electroluminescence element according to the present invention is an organic electroluminescence element having a light-emitting layer, wherein: the light-emitting layer contains a phosphorescent luminous compound and a fluorescent luminous compound; the emission spectrum of the phosphorescent luminous compound and the absorption spectrum of the fluorescent luminous compound have an overlapping region; the luminescence decay lifetime τ of a single layer of the light-emitting layer and the absolute quantum yield PLQE Φ of a single layer of the light-emitting layer satisfy specific conditions; and the Stokes shift of the fluorescent luminous compound is 0.1 eV or less.

Description

有機エレクトロルミネッセンス素子及び有機エレクトロルミネッセンス素子の製造方法ORGANIC ELECTROLUMINESCENT ELEMENT AND METHOD FOR PRODUCING ORGANIC ELECTROLUMINESCENT ELEMENT
　本発明は、有機エレクトロルミネッセンス素子及び有機エレクトロルミネッセンス素子の製造方法に関する。より詳しくは、本発明は、高輝度（高電流密度）で駆動した際においても発光効率、輝度半減寿命が良好な有機エレクトロルミネッセンス素子及び有機エレクトロルミネッセンス素子の製造方法に関する。 The present invention relates to an organic electroluminescence element and a method for manufacturing the organic electroluminescence element. More specifically, the present invention relates to an organic electroluminescent device having good luminous efficiency and luminance half life even when driven at high luminance (high current density) and a method for manufacturing the organic electroluminescent device.
　発光型の電子ディスプレイデバイスとして、有機エレクトロルミネッセンス（以下、「ＥＬ」ともいう。）素子がある。 There is an organic electroluminescence (hereinafter, also referred to as “EL”) element as a light-emitting electronic display device.
　有機ＥＬ素子は、発光する化合物（以下、「発光材料」ともいう。）を含有する発光層を陰極と陽極で挟んだ構成を有し、発光層に電子及び正孔を注入して、再結合させることにより励起子（エキシトン）を生成させ、このエキシトンが失活する際の光の放出（蛍光・リン光）を利用して発光する素子である。このような有機ＥＬ素子は、数～数十Ｖの低電圧で発光が可能であり、さらに自己発光型であるために視野角に富み、視認性が高い。また、有機ＥＬ素子は、薄膜型の完全固体素子であるために省スペース、携帯性等の観点から注目されている。 An organic EL element has a structure in which a light-emitting layer containing a compound that emits light (hereinafter also referred to as “light-emitting material”) is sandwiched between a cathode and an anode, and recombines by injecting electrons and holes into the light-emitting layer. This is an element that generates excitons (excitons) by light emission, and emits light by utilizing light emission (fluorescence / phosphorescence) when the excitons are deactivated. Such an organic EL element can emit light at a low voltage of several to several tens of volts, and further has a wide viewing angle and high visibility because it is a self-luminous type. In addition, since the organic EL element is a thin-film type complete solid-state element, it has attracted attention from the viewpoints of space saving and portability.
　今後の有機ＥＬの素子開発として、さらに発光効率、輝度及び色度の良好な発光が可能な有機ＥＬ素子が望まれている。 As an organic EL element development in the future, an organic EL element capable of emitting light with better luminous efficiency, luminance and chromaticity is desired.
　従来、有機ＥＬ素子の発光方式としては、三重項励起状態から基底状態に戻る際に光を発する「リン光発光」と、一重項励起状態から基底状態に戻る際に光を発する「蛍光発光」の二通りが知られている。 Conventionally, organic EL devices have two types of emission methods: “phosphorescence emission” that emits light when returning from the triplet excited state to the ground state, and “fluorescence emission” that emits light when returning from the singlet excited state to the ground state. Two ways are known.
　有機ＥＬ素子に電界をかけると、陽極と陰極からそれぞれ正孔と電子が注入され、発光層において再結合し励起子を生じる。このとき一重項励起子と三重項励起子とが２５％：７５％の割合で生成するため、三重項励起子を利用するリン光発光の方が、蛍光発光に比べ、理論的に高い内部量子効率が得られることが知られている。また、Ｉｒ、Ｒｕ、Ｐｔといった重原子を含む青色リン光発光性金属錯体は、重原子効果によって一重項励起状態から三重項励起状態への本来禁制であるスピン反転が可能であり、理論的には最大１００％の内部量子収率を実現し得ることが知られている。高輝度の観点から、発光材料として、青色蛍光発光性化合物よりも、上記重原子を含む青色リン光発光性金属錯体が用いられることが多い。 When an electric field is applied to the organic EL element, holes and electrons are injected from the anode and the cathode, respectively, and recombine in the light emitting layer to generate excitons. At this time, since singlet excitons and triplet excitons are generated at a ratio of 25%: 75%, phosphorescence using triplet excitons is theoretically higher in internal quantum than fluorescence. It is known that efficiency can be obtained. In addition, blue phosphorescent metal complexes containing heavy atoms such as Ir, Ru, and Pt are capable of spin inversion, which is inherently forbidden from a singlet excited state to a triplet excited state, due to the heavy atom effect. Is known to be able to achieve internal quantum yields of up to 100%. From the viewpoint of high brightness, a blue phosphorescent metal complex containing the above heavy atoms is often used as a light emitting material rather than a blue fluorescent compound.
　また、近年では、三重項励起子から一重項励起子への逆項間交差（Ｒｅｖｅｒｓｅ　Ｉｎｔｅｒｓｙｓｔｅｍ　Ｃｒｏｓｓｉｎｇ：以下、適宜「ＲＩＳＣ」ともいう。）が生じる現象を利用した現象（熱活性型遅延蛍光（「熱励起型遅延蛍光」ともいう：Ｔｈｅｒｍａｌｌｙ　Ａｃｔｉｖａｔｅｄ　Ｄｅｌａｙｅｄ　Ｆｌｕｏｒｅｓｃｅｎｃｅ：以下、適宜「ＴＡＤＦ」と略記する。）を利用した蛍光発光材料と、有機ＥＬ素子への利用の可能性が報告されている（例えば、特許文献１、非特許文献１、非特許文献２参照。）。このＴＡＤＦ機構による遅延蛍光を利用すると、電界励起による蛍光発光においても、理論的にはリン光発光と同等の１００％の内部量子効率が可能となる。 Further, in recent years, a phenomenon (thermally activated delayed fluorescence (“RIS”) where a reverse intersystem crossing from a triplet exciton to a singlet exciton, hereinafter, also referred to as “RISC”) occurs. Also referred to as “thermally excited delayed fluorescence”: Thermally Activated Delayed Fluorescence (hereinafter abbreviated as “TADF” where appropriate) and the possibility of use in organic EL devices has been reported (for example, (See Patent Document 1, Non-Patent Document 1, and Non-Patent Document 2.) By using delayed fluorescence by this TADF mechanism, 100% internal quantum is theoretically equivalent to phosphorescence emission even in fluorescence emission by electric field excitation. Efficiency becomes possible.
　発光効率の観点では、リン光方式、ＴＡＤＦ方式が優れており、低消費電力を要求される照明用途やモバイルディスプレイ用途などでは、やはり全ての光にリン光発光又はＴＡＤＦ発光を利用することが望まれている。
　しかしながら、リン光方式やＴＡＤＦ方式では、寿命及び色純度の点にまだ改善の余地があり、特に、青色発光、中でも短波長な発光波長が求められる純青又は深い青（ディープブルー）に関して、寿命及び色純度の点で実用的に満足できるレベルのものは見出されていない。その理由は、青色リン光発光性化合物のエネルギー準位（以下、単に「準位」ともいう）が、赤色や緑色のものと比較して高く、電界駆動中に生成された準位の低い消光物質にエネルギー移動がしやすいためである。
　青色リン光発光性化合物は発光減衰寿命τが数μｓ～数十μｓ程度であり、蛍光発光材料の蛍光寿命と比較して２～４オーダー長くなっている。また、青色リン光発光性化合物は、三重項励起状態の準位が高いために、青色リン光発光性化合物からの発光スペクトルと消光物質の吸収スペクトルとに重なりが生じやすく、エネルギー移動速度が大きくなっている。 From the viewpoint of luminous efficiency, the phosphorescence and TADF methods are excellent. For lighting and mobile display applications that require low power consumption, it is desirable to use phosphorescence or TADF for all light. It is rare.
However, the phosphorescence method and the TADF method still have room for improvement in terms of lifetime and color purity, especially for blue light emission, particularly pure blue or deep blue, which requires a short emission wavelength. No practically satisfactory level of color purity has been found. The reason is that the blue phosphorescent compound has a higher energy level (hereinafter also simply referred to as “level”) than that of red or green, and has a low level of quenching generated during electric field driving. This is because energy transfer to a substance is easy.
The blue phosphorescent compound has an emission decay lifetime τ of about several μs to several tens of μs, which is 2 to 4 orders longer than the fluorescence lifetime of the fluorescent material. In addition, since the blue phosphorescent compound has a high triplet excited state level, the emission spectrum from the blue phosphorescent compound and the absorption spectrum of the quencher are likely to overlap, and the energy transfer rate is large. It has become.
　ここで、消光物質が生成した際の発光材料からの消光現象は、下記に示すＳＴＥＲＮ－ＶＯＬＭＥＲの式（下記式（Ａ））によって説明することができる。 Here, the quenching phenomenon from the light emitting material when the quenching substance is generated can be explained by the STern-VOLMER formula (the following formula (A)) shown below.
Figure JPOXMLDOC01-appb-M000001
 　Ｋq：発光材料から消光物質へのエネルギー移動速度、［Ｑ］：消光物質濃度、τ0：発光材料の発光減衰寿命
Figure JPOXMLDOC01-appb-M000001
 K q : Energy transfer rate from the light emitting material to the quenching substance, [Q]: Quenching substance concentration, τ 0 : Luminescence decay lifetime of the light emitting material
　すなわち、ＳＴＥＲＮ－ＶＯＬＭＥＲの式より、発光減衰寿命が長い（マイクロ秒オーダー）リン光発光性化合物及びＴＡＤＦ化合物は、クエンチャー（消光物質）によって消光されやすく、有機ＥＬ素子の輝度半減寿命（以下、単に「半減寿命」ともいう。）が低下する。 That is, from the STern-VOLMER equation, phosphorescent compounds and TADF compounds having a long emission decay lifetime (on the order of microseconds) and TADF compounds are easily quenched by a quencher (quenching substance), and the luminance half-life of the organic EL element (hereinafter, referred to as the “luminescence half-life”). Simply referred to as “half-life”).
　また、有機ＥＬ素子の半減寿命の低下を引き起こす要因の一つとして、駆動中の発熱が挙げられる。
　発光層中で正孔と電子とが再結合することで生成した励起エネルギーは、すべてが発光として消費される訳ではなく、その一部は熱として失活する。有機ＥＬ素子を連続駆動させることで、放出される熱が素子内に蓄積される。この結果、有機ＥＬ素子が含有する化合物の分解や凝集の発生、それに伴うクエンチャーの生成、膜物性の変動等が生じ、ひいては、クエンチャーによる励起子消光や膜物性の変動に起因するキャリアバランスの崩れにより輝度及び半減寿命の低下を生じる。 Further, one of the factors that cause a reduction in the half-life of the organic EL element is heat generation during driving.
The excitation energy generated by recombination of holes and electrons in the light-emitting layer is not necessarily consumed as light emission, but part of it is deactivated as heat. By continuously driving the organic EL element, the released heat is accumulated in the element. As a result, decomposition and aggregation of the compound contained in the organic EL element occur, quencher generation accompanying it, fluctuations in film physical properties, and the like. As a result, carrier balance due to exciton quenching and film physical property fluctuations due to the quencher occurs. The collapse of the brightness causes a reduction in luminance and half-life.
　リン光方式やＴＡＤＦ方式での発光の場合、駆動初期では高効率で発光する。しかし、リン光発光性化合物やＴＡＤＦ化合物の発光減衰寿命が長いこと、即ちエネルギー的に活性な状態である三重項励起状態の滞在時間が長いことで、駆動に伴い発生する熱の影響をより受けやすくなる。この結果、クエンチャーの生成や膜物性の変動が促進され、輝度及び半減寿命の低下を生じるという問題があった。特にクエンチャーが生成した場合、上記ＳＴＥＲＮ－ＶＯＬＭＥＲ式より、有機ＥＬ素子の輝度及び半減寿命の低下が顕著となる。 In the case of light emission by phosphorescence method or TADF method, light is emitted with high efficiency at the initial driving stage. However, phosphorescent compounds and TADF compounds have a long emission decay lifetime, that is, a long residence time in the triplet excited state, which is an energetically active state, and thus is more affected by the heat generated by driving. It becomes easy. As a result, there is a problem that the generation of quencher and the change in film properties are promoted, and the luminance and half-life are reduced. In particular, when a quencher is generated, the brightness and half-life of the organic EL element are significantly reduced from the STern-VOLMER formula.
　また、有機ＥＬ素子の発光態様としては、上記リン光方式やＴＡＤＦ方式のほか、一つの発光層にリン光発光性化合物及び蛍光発光性化合物を含有させる方式による、発光効率向上が提案されている（例えば、特許文献２参照。）。しかし、外部取り出し量子効率の値が３．３％と低効率で、蛍光発光素子の理論限界値を超えるものではなく、実用的なレベルではなかった。また、ロールオフも大きかった。 In addition to the phosphorescence method and the TADF method, the emission efficiency of the organic EL element has been proposed to improve luminous efficiency by a method in which a phosphorescent compound and a fluorescent compound are contained in one light emitting layer. (For example, refer to Patent Document 2). However, the value of the external extraction quantum efficiency is as low as 3.3%, which does not exceed the theoretical limit value of the fluorescent light emitting device, and is not at a practical level. Also, the roll-off was great.
特開２０１３－１１６９７５号公報JP 2013-116975 A 特表２００３－５２０３９１号公報Japanese translation of PCT publication No. 2003-520391
　本発明は、上記問題・状況に鑑みてなされたものであり、その解決課題は、高輝度（高電流密度）で駆動した際においても輝度半減寿命を良好にでき、かつ、発光効率も良好な有機エレクトロルミネッセンス素子を提供することである。 The present invention has been made in view of the above-described problems and circumstances, and the problem to be solved is that the luminance half-life can be improved even when driven at high luminance (high current density), and the luminous efficiency is also excellent. An organic electroluminescence device is provided.
　本発明者は、上記課題を解決すべく、上記問題の原因等について検討する過程において、発光層中に特定のリン光発光性化合物及び蛍光発光性化合物物を含有させ、リン光発光性化合物から蛍光発光性化合物へフェルスター型のエネルギー移動を促進させて、発光層単層の発光減衰寿命τ、発光層単層の絶対量子収率ＰＬＱＥ（φ）を規定の値に保つことで、高輝度（高電流密度）で駆動した際においても、輝度半減寿命を良好にでき、かつ、発光効率も良好にできることを見いだし本発明に至った。
　すなわち、本発明に係る上記課題は、以下の手段により解決される。 In order to solve the above problems, the present inventor includes a specific phosphorescent compound and a fluorescent compound in the light emitting layer in the process of examining the cause of the above problem, and the like. Brightness is enhanced by promoting Ferster-type energy transfer to the fluorescent compound and maintaining the emission decay lifetime τ of the single light emitting layer and the absolute quantum yield PLQE (φ) of the single light emitting layer at the specified values. It has been found that even when driven at (high current density), the luminance half-life can be improved and the light emission efficiency can be improved, leading to the present invention.
That is, the said subject which concerns on this invention is solved by the following means.
　１．発光層を有する有機エレクトロルミネッセンス素子であって、
　前記発光層が、リン光発光性化合物及び蛍光発光性化合物を含有し、
　前記リン光発光性化合物の発光スペクトルと前記蛍光発光性化合物の吸収スペクトルとが重なりを有しており、
　前記発光層単層の発光減衰寿命τが、下記（１）式を満たし、
　前記発光層単層の絶対量子収率ＰＬＱＥφが、下記（２）式を満たし、
　前記蛍光発光性化合物のストークスシフトが、０．１ｅＶ以下である有機エレクトロルミネッセンス素子。
　　０＜τ／τ0≦０．７・・・（１）
　　０．６≦φ／φ0≦１．０・・・（２）
［τ：前記発光層単層の発光減衰寿命
　τ0：前記リン光発光性化合物の単膜の発光減衰寿命
　φ：前記発光層単層の絶対量子収率ＰＬＱＥ
　φ0：前記リン光発光性化合物の単膜の絶対量子収率ＰＬＱＥ］ 1. An organic electroluminescence device having a light emitting layer,
The light emitting layer contains a phosphorescent compound and a fluorescent compound,
The emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound have an overlap,
The light emission decay lifetime τ of the light emitting layer satisfies the following formula (1):
The absolute quantum yield PLQEφ of the light emitting layer single layer satisfies the following formula (2):
The organic electroluminescent element whose Stokes shift of the said fluorescent compound is 0.1 eV or less.
0 <τ / τ 0 ≦ 0.7 (1)
0.6 ≦ φ / φ 0 ≦ 1.0 (2)
[Τ: emission decay lifetime of the single layer of the light emitting layer τ 0 : emission decay lifetime of the single layer of the phosphorescent compound φ: absolute quantum yield PLQE of the single layer of the light emitting layer
φ 0 : absolute quantum yield PLQE of the phosphorescent compound single film]
　２．前記リン光発光性化合物と前記蛍光発光性化合物とが、下記（３）式又は下記（４）式を満たす第１項に記載の有機エレクトロルミネッセンス素子。
　ＨＯＭＯ（Ｆ）≦ＨＯＭＯ（Ｐ）・・・（３）
　ＬＵＭＯ（Ｐ）≦ＬＵＭＯ（Ｆ）・・・（４）
［ＨＯＭＯ（Ｐ）、ＬＵＭＯ（Ｐ）：それぞれ、前記リン光発光性化合物の最高被占分子軌道（ＨＯＭＯ）と最低空分子軌道（ＬＵＭＯ）のエネルギー準位
　ＨＯＭＯ（Ｆ）、ＬＵＭＯ（Ｆ）：それぞれ、前記蛍光発光性化合物の最高被占分子軌道（ＨＯＭＯ）と前記蛍光発光性化合物の最低空分子軌道（ＬＵＭＯ）のエネルギー準位］ 2. The organic electroluminescence device according to item 1, wherein the phosphorescent compound and the fluorescent compound satisfy the following formula (3) or the following formula (4).
HOMO (F) ≦ HOMO (P) (3)
LUMO (P) ≦ LUMO (F) (4)
[HOMO (P), LUMO (P): energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the phosphorescent compound HOMO (F) and LUMO (F), respectively: The energy levels of the highest occupied molecular orbital (HOMO) of the fluorescent compound and the lowest unoccupied molecular orbital (LUMO) of the fluorescent compound, respectively.
　３．前記発光層に含まれる化合物の総量を１００質量％としたとき、前記蛍光発光性化合物の含有量（質量％）が、前記リン光発光性化合物の含有量（質量％）より少ない第１項又は第２項に記載の有機エレクトロルミネッセンス素子。 3. The first item or the content (% by mass) of the fluorescent compound, which is less than the content (% by mass) of the phosphorescent compound, when the total amount of the compounds contained in the light emitting layer is 100% by mass. 3. The organic electroluminescence device according to item 2.
　４．前記発光層に含まれる化合物の総量を１００質量％としたとき、前記蛍光発光性化合物の含有量が、５質量％以下である第１項から第３項までのいずれか一項に記載の有機エレクトロルミネッセンス素子。 4. The organic according to any one of Items 1 to 3, wherein the content of the fluorescent compound is 5% by mass or less when the total amount of the compounds contained in the light emitting layer is 100% by mass. Electroluminescence element.
　５．第１項から第４項までのいずれか一項に記載の有機エレクトロルミネッセンス素子を製造する有機エレクトロルミネッセンス素子の製造方法であって、
　前記発光層を、ドライプロセスで製造する有機エレクトロルミネッセンス素子の製造方法。 5). It is a manufacturing method of the organic electroluminescent element which manufactures the organic electroluminescent element as described in any one of Claim 1 to 4,
The manufacturing method of the organic electroluminescent element which manufactures the said light emitting layer with a dry process.
　６．第１項から第４項までのいずれか一項に記載の有機エレクトロルミネッセンス素子を製造する有機エレクトロルミネッセンス素子の製造方法であって、
　前記発光層を、ウェットプロセスで製造する有機エレクトロルミネッセンス素子の製造方法。 6). It is a manufacturing method of the organic electroluminescent element which manufactures the organic electroluminescent element as described in any one of Claim 1 to 4,
The manufacturing method of the organic electroluminescent element which manufactures the said light emitting layer with a wet process.
　本発明の上記手段により、高輝度（高電流密度）で駆動した際においても輝度半減寿命を良好にでき、かつ、発光効率も良好な有機エレクトロルミネッセンス素子を提供することができる。
　本発明の効果の発現機構ないし作用機構については、明確にはなっていないが、以下のように考えている。 By the above means of the present invention, it is possible to provide an organic electroluminescence device that can have a satisfactory luminance half-life even when driven at a high luminance (high current density) and has a good luminous efficiency.
The expression mechanism or action mechanism of the effect of the present invention is not clear, but is considered as follows.
　リン光発光性化合物の発光層に蛍光発光性化合物を添加することで、リン光発光性化合物上に生成した励起エネルギーを蛍光発光性化合物にフェルスター型エネルギー移動又はデクスター型エネルギー移動により、速やかに蛍光発光性化合物へ移動させ消費することができる。その結果、リン光発光性化合物の発光減衰寿命がサブマイクロ秒～ナノ秒オーダーに短縮されるので、式（Ａ）より、クエンチャーに対し消光されにくくなり、半減寿命が向上する。
　また、リン光発光性化合物が励起状態で存在する時間が短くなるので、励起子密度が大きい状態である高電流駆動において、３重項－３重項励起子消滅（ＴＴＡ；Ｔｒｉｐｌｅｔ－Ｔｒｉｐｌｅｔ　Ａｎｎｉｈｉｌａｔｉｏｎ）や、３重項－ポーラロン励起子消滅（ＴＰＡ；Ｔｒｉｐｌｅｔ－Ｐｏｌａｒｏｎ　Ａｎｎｉｈｉｌａｔｉｏｎ）が発生しにくくなり、ロールオフが改善する。
　しかし、これまで知られている手法では、半減寿命に関しては、低電流での連続駆動では向上が見られたものの、高電流の連続駆動では半減寿命向上効果は不十分であった。 By adding a fluorescent compound to the phosphorescent compound emitting layer, the excitation energy generated on the phosphorescent compound can be rapidly transferred to the fluorescent compound by Forster-type energy transfer or Dexter-type energy transfer. It can be transferred to a fluorescent compound and consumed. As a result, the emission decay lifetime of the phosphorescent compound is shortened to the order of sub-microseconds to nanoseconds. Therefore, from the formula (A), quenching with respect to the quencher is difficult, and the half-life is improved.
In addition, since the time during which the phosphorescent compound exists in an excited state is shortened, triplet-triplet annihilation (TTA) is performed in high current driving where the exciton density is high. And triplet-polaron exciton annihilation (TPA) is less likely to occur, and roll-off is improved.
However, in the methods known so far, the half-life is improved in continuous driving at a low current, but the half-life improving effect is insufficient in continuous driving at a high current.
　そこで、本発明者が検討したところ、上述の高電流の連続駆動では、励起子密度が高い状態で励起及び発光の過程が繰り返されるので、有機ＥＬ素子内に蓄積される熱が低電流の連続駆動より大きく、リン光発光性化合物を含有する発光層に蛍光発光性化合物を添加するという従来手法（例えば、特許文献２参照。）では、上述の膜物性の変動を十分に抑制できないことをつきとめた。
　更に本発明者が鋭意検討したところ、蛍光発光性化合物としてストークスシフトが小さい化合物を添加することで、高電流密度駆動であっても発熱をより抑制し、膜物性の変動を抑え、半減寿命をより良好にできることをつきとめた。詳細な理由は以下に記載する。この結果、劣化速度をより遅くすることができるため、下記半減寿命の加速係数ｎを小さくできる。 Therefore, the present inventor has examined that, in the above-described continuous driving at a high current, the process of excitation and light emission is repeated in a state where the exciton density is high, so that the heat accumulated in the organic EL element is continuously low in current. It has been found that the conventional method of adding a fluorescent compound to a light emitting layer containing a phosphorescent compound that is larger than driving (for example, see Patent Document 2) cannot sufficiently suppress the above-described fluctuations in film properties. It was.
Furthermore, when the present inventors diligently studied, by adding a compound having a small Stokes shift as a fluorescent light emitting compound, heat generation is further suppressed even at high current density driving, fluctuation of film physical properties is suppressed, and half life is reduced. I found out that I could do better. The detailed reason is described below. As a result, since the deterioration rate can be further reduced, the following half-life acceleration coefficient n can be reduced.
　なお、加速係数とは、下記（Ｂ）式中のｎである。
　ｔ1／ｔ2＝（Ｌ1／Ｌ2）－ｎ・・・（Ｂ）
［Ｌ1：電流密度２．５ｍＡ／ｃｍ２印加時の初期輝度
　Ｌ2：電流密度１６．２５ｍＡ／ｃｍ２印加時の初期輝度
　ｔ1：輝度Ｌ1（低電流２．５ｍＡ／ｃｍ２）での半減寿命
　ｔ2：輝度Ｌ2（高電流１６．２５ｍＡ／ｃｍ２）での半減寿命］ The acceleration coefficient is n in the following formula (B).
t 1 / t 2 = (L 1 / L 2 ) −n (B)
[L 1: current density 2.5 mA / cm 2 upon application of the initial luminance L 2: current density 16.25mA / cm 2 applied during the initial luminance t 1: the luminance L 1 (low current 2.5 mA / cm 2) T 2 : Half life at luminance L 2 (high current 16.25 mA / cm 2 )]
　ストークスシフトが小さいことは、励起状態と基底状態との間で分子構造の変動が小さいことを意味する。このことは、励起エネルギーと発光エネルギーとの差が小さい、つまり、発光に寄与せず熱として放出するエネルギーが小さいといえる（図１Ａ参照。）。一方、ストークスシフトが大きいことは、励起状態と基底状態との間で分子構造の変動が大きく、励起エネルギーと発光エネルギーの差も大きいので、熱として放出するエネルギーが大きいといえる。（図１Ｂ参照。）
　よって、ストークスシフトが小さい蛍光発光性化合物を用いることで、励起子密度が高い高電流駆動においても、熱の発生を抑制し、経時での膜物性の変動を抑制することができる。
　本発明の技術では、発光層で生成した励起エネルギーは主に蛍光発光性化合物から発光する。蛍光発光性化合物の添加量は少量であるが、発光層内で生成した励起エネルギーは蛍光発光性化合物に集まるので、添加量が少量ではあっても、膜質変動要因として無視できない。
　このような発熱抑制の観点から、本発明においては、蛍光発光性化合物のストークスシフトは小さい方がよく、具体的には、０．１ｅＶ以下である。 A small Stokes shift means a small change in molecular structure between the excited state and the ground state. This can be said that the difference between the excitation energy and the emission energy is small, that is, the energy released as heat without contributing to the emission is small (see FIG. 1A). On the other hand, a large Stokes shift means that the energy released as heat is large because the molecular structure varies greatly between the excited state and the ground state, and the difference between the excited energy and the emitted energy is also large. (See FIG. 1B.)
Therefore, by using a fluorescent compound having a small Stokes shift, generation of heat can be suppressed even in high current driving with a high exciton density, and fluctuations in film properties over time can be suppressed.
In the technique of the present invention, the excitation energy generated in the light emitting layer emits light mainly from a fluorescent compound. Although the amount of the fluorescent light-emitting compound added is small, the excitation energy generated in the light-emitting layer is collected in the fluorescent light-emitting compound, so even if the amount added is small, it cannot be ignored as a film quality variation factor.
From the viewpoint of suppressing such heat generation, in the present invention, the Stokes shift of the fluorescent compound is preferably small, specifically 0.1 eV or less.
　さらに、本発明者は、発光層単層の発光減衰寿命τがリン光の発光減衰寿命τ0より短
く（（１）式）、且つ、発光層単層の絶対量子収率φをリン光発光性化合物の単膜の絶対量子収率（φ0）に対して特定の範囲（（２）式）であれば、印加電流に対する輝度半減
寿命の加速係数をさらに小さくすることができることを見い出した。 Further, the inventor of the present invention has disclosed that the emission decay lifetime τ of the light emitting layer single layer is shorter than the phosphorescence emission decay lifetime τ 0 (Equation (1)), and the absolute quantum yield φ of the light emitting layer single layer is phosphorescent. It has been found that the acceleration coefficient of the luminance half-life with respect to the applied current can be further reduced within a specific range (equation (2)) with respect to the absolute quantum yield (φ 0 ) of the single film of the active compound.
　また、本発明の有機ＥＬ素子では、リン光発光性化合物の三重項励起状態の励起エネルギーを蛍光発光性化合物の一重項励起状態へフェルスター型エネルギー移動させ、蛍光発光させる。
　これに対し、従来の技術では、フェルスター型エネルギー移動と共に、リン光発光性化合物の三重項励起状態から、蛍光発光性化合物の三重項励起状態へ、デクスター型エネルギー移動が発生し得る（図２参照。）。デクスター型エネルギー移動が発生した場合、蛍光発光性化合物の三重項励起状態からは非発光で失活するので、絶対量子収率（すなわち、発光層単層の絶対量子収率φ）は低下する。
　しかしながら、有機ＥＬ素子の性能において、発光層単層の絶対量子収率φは高い方が望ましい。
　実用的なリン光発光性化合物は１００％に近い高い絶対量子収率（すなわち、リン光発光性化合物の単膜の絶対量子収率φ0）を有しており、蛍光発光性化合物を含有させても
、上記のデクスター型エネルギー移動による絶対量子収率の低下を抑制し、高い絶対量子収率を維持することが望まれる。
　そのためには、リン光発光性化合物の三重項励起状態から蛍光発光性化合物の一重項励起状態のフェルスター型エネルギー移動を促進させることが有効である。フェルスター型エネルギー移動を効率的に発現させる主な因子は、エネルギー供与体（リン光発光性化合物）の発光スペクトルと、エネルギー受容体（蛍光発光性化合物）の吸収スペクトルの重なりを大きくすることである。
　このため、本発明においては、リン光発光性化合物の発光スペクトルと蛍光発光性化合物の吸収スペクトルとが、重なりを有することが必須である。 Moreover, in the organic EL device of the present invention, the phosphorescent compound emits fluorescence by transferring the excitation energy in the triplet excited state of the phosphorescent compound to the singlet excited state of the fluorescent compound.
On the other hand, in the conventional technique, along with the Forster energy transfer, Dexter energy transfer can occur from the triplet excited state of the phosphorescent compound to the triplet excited state of the fluorescent compound (FIG. 2). reference.). When Dexter type energy transfer occurs, the fluorescence emission compound is deactivated by non-luminescence from the triplet excited state, and thus the absolute quantum yield (that is, the absolute quantum yield φ of the single light emitting layer) is lowered.
However, in terms of the performance of the organic EL element, it is desirable that the absolute quantum yield φ of the light emitting layer is higher.
A practical phosphorescent compound has a high absolute quantum yield close to 100% (that is, the absolute quantum yield φ 0 of a single film of the phosphorescent compound), and contains a fluorescent compound. However, it is desired to suppress a decrease in absolute quantum yield due to the above-described Dexter type energy transfer and maintain a high absolute quantum yield.
For this purpose, it is effective to promote the Forster energy transfer from the triplet excited state of the phosphorescent compound to the singlet excited state of the fluorescent compound. The main factor for efficiently developing Forster energy transfer is to increase the overlap between the emission spectrum of the energy donor (phosphorescent compound) and the absorption spectrum of the energy acceptor (fluorescent compound). is there.
Therefore, in the present invention, it is essential that the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound have an overlap.
　また、フェルスター型エネルギー移動は、下記（Ｆ）式に示されるように、分子間距離Ｒの６乗に反比例する。一方、デクスター型エネルギー移動は、下記（Ｄ）式に示されるように、分子間距離Ｒに対し指数関数減衰を示す（参考文献：基礎化学コース　光化学I　井上晴夫・高木克彦・佐々木政子・朴鐘震　共著）。なお、下記（Ｆ）式及び（Ｄ）式において、ｋETはエネルギーの移動速度を表す。 Further, the Forster energy transfer is inversely proportional to the sixth power of the intermolecular distance R as shown in the following equation (F). On the other hand, Dexter type energy transfer shows exponential decay with respect to the intermolecular distance R as shown in the following equation (D) (Reference: Basic Chemistry Course, Photochemistry I Haruo Inoue, Katsuhiko Takagi, Masako Sasaki, Park Bell) Co-authored with Earthquake) In the following formulas (F) and (D), k ET represents the energy transfer speed.
　ｋET∝Ｒ－６・・・（Ｆ）
　ｋET∝ｅｘｐ（－Ｒ）・・・（Ｄ） k ET ∝R -6 ... (F)
k ET ∝exp (-R) (D)
　上式より、分子間距離が大きくなると、相対的にフェルスター型エネルギー移動に対してデクスター型エネルギー移動が発生しにくくなるといえる。よって、デクスター型エネルギー移動を抑制し、フェルスター型エネルギー移動を促進させる手法として、蛍光発光性化合物の含有量を減らし、リン光発光性化合物と蛍光発光性化合物の分子間距離を適度に離し、フェルスター型エネルギー移動が優勢となる距離に保つことも有効である。 From the above formula, it can be said that when the intermolecular distance is increased, Dexter-type energy transfer is less likely to occur relative to Forster-type energy transfer. Therefore, as a method of suppressing Dexter type energy transfer and promoting Forster type energy transfer, the content of the fluorescent compound is reduced, and the intermolecular distance between the phosphorescent compound and the fluorescent compound is appropriately separated, It is also effective to keep the distance at which Förster energy transfer predominates.
ストークスシフトが小さい場合のエネルギー放出を説明する概念図Conceptual diagram explaining energy release when Stokes shift is small ストークスシフトが大きい場合のエネルギー放出を説明する概念図Conceptual diagram explaining energy release when Stokes shift is large 従来技術におけるエネルギー移動を示す模式図Schematic diagram showing energy transfer in the prior art 本発明の有機ＥＬ素子を有する表示装置の構成の一例を示した概略斜視図The schematic perspective view which showed an example of the structure of the display apparatus which has the organic EL element of this invention 図３に示す表示部Ａの模式図Schematic diagram of display section A shown in FIG. 本発明の有機ＥＬ素子を有する照明装置の一例を示した概略図Schematic which showed an example of the illuminating device which has the organic EL element of this invention 本発明の有機ＥＬ素子を有する照明装置の一例を示した断面図Sectional drawing which showed an example of the illuminating device which has the organic EL element of this invention
　本発明の有機エレクトロルミネッセンス素子は、発光層を有する有機エレクトロルミネッセンス素子であって、前記発光層が、リン光発光性化合物及び蛍光発光性化合物を含有し、前記リン光発光性化合物の発光スペクトルと前記蛍光発光性化合物の吸収スペクトルとが重なりを有しており、前記発光層単層の発光減衰寿命τが、上記（１）式を満たし、前記発光層単層の絶対量子収率ＰＬＱＥφが、上記（２）式を満たし、前記蛍光発光性化合物のストークスシフトが、０．１ｅＶ以下であることを特徴とする。この特徴は下記実施態様に共通又は対応する技術的特徴である。これにより、本発明は、高輝度（高電流密度）で駆動した際においても輝度半減寿命を良好にでき、かつ、発光効率も良好な有機エレクトロルミネッセンス素子を提供できる。 The organic electroluminescent device of the present invention is an organic electroluminescent device having a light emitting layer, wherein the light emitting layer contains a phosphorescent compound and a fluorescent compound, and an emission spectrum of the phosphorescent compound and The absorption spectrum of the fluorescent compound has an overlap, the emission decay lifetime τ of the single light emitting layer satisfies the above formula (1), and the absolute quantum yield PLQEφ of the single light emitting layer is The above formula (2) is satisfied, and the Stokes shift of the fluorescent compound is 0.1 eV or less. This feature is a technical feature common to or corresponding to the following embodiments. As a result, the present invention can provide an organic electroluminescence device that can have a good luminance half-life and good luminous efficiency even when driven at high luminance (high current density).
　本発明の実施態様としては、前記リン光発光性化合物と前記蛍光発光性化合物とが、上記（３）式又は上記（４）式を満たすことで、外部取り出し効率（ＥＱＥ）を高く保つことができるので好ましい。 As an embodiment of the present invention, the phosphorescent compound and the fluorescent compound satisfy the above formula (3) or the above formula (4), thereby keeping the external extraction efficiency (EQE) high. It is preferable because it is possible.
　本発明においては、前記発光層に含まれる化合物の総量を１００質量％としたとき、前記蛍光発光性化合物の含有量（質量％）が、前記リン光発光性化合物の含有量（質量％）より少ないことが、外部取り出し量子効率及び半減寿命をより良好にできるため好ましい。 In the present invention, when the total amount of compounds contained in the light emitting layer is 100% by mass, the content (% by mass) of the fluorescent compound is more than the content (% by mass) of the phosphorescent compound. Less is preferable because the external extraction quantum efficiency and the half life can be improved.
　本発明においては、前記発光層に含まれる化合物の総量を１００質量％としたとき、蛍光発光性化合物の含有量が、５質量％以下であることが外部取り出し量子効率及び半減寿命をより良好にできるため好ましい。 In the present invention, when the total amount of the compounds contained in the light emitting layer is 100% by mass, the content of the fluorescent light emitting compound is 5% by mass or less to improve the external extraction quantum efficiency and the half life. This is preferable because it is possible.
　本発明の有機エレクトロルミネッセンス素子を製造する有機エレクトロルミネッセンス素子の製造方法としては、前記発光層を、ドライプロセス又はウェットプロセスで製造することができる。特にウェットプロセスを用いて製造することにより、素子の形状や大きさに課せられる制約を低減できるだけでなく、より安価な作製プロセスで有機エレクトロルミネッセンス素子を製造することができる。 As a method for producing an organic electroluminescence element for producing the organic electroluminescence element of the present invention, the light emitting layer can be produced by a dry process or a wet process. In particular, by manufacturing using a wet process, not only can the restrictions imposed on the shape and size of the element be reduced, but also an organic electroluminescent element can be manufactured by a cheaper manufacturing process.
　以下、本発明とその構成要素、及び本発明を実施するための形態・態様について詳細な説明をする。なお、本願において、「～」は、その前後に記載される数値を下限値及び上限値として含む意味で使用する。 Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In the present application, “˜” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.
　≪有機エレクトロルミネッセンス素子の概要≫
　本発明の有機エレクトロルミネッセンス素子は、発光層を有する有機エレクトロルミネッセンス素子であって、
　前記発光層が、リン光発光性化合物及び蛍光発光性化合物を含有し、
　前記リン光発光性化合物の発光スペクトルと前記蛍光発光性化合物の吸収スペクトルとが重なりを有しており、
　前記発光層単層の発光減衰寿命τが下記（１）式を満たし、
　前記発光層単層の絶対量子収率ＰＬＱＥ（φ）が下記（２）式を満たし、
　前記蛍光発光性化合物のストークスシフトが、０．１ｅＶ以下であることを特徴とする有機エレクトロルミネッセンス素子。
　　０＜τ／τ0≦０．７・・・（１）
　　０．６≦φ／φ0≦１．０・・・（２）
［τ：前記発光層単層の発光減衰寿命
　τ0：前記リン光発光性化合物の単膜の発光減衰寿命
　φ：前記発光層単層の絶対量子収率ＰＬＱＥ
　φ0：前記リン光発光性化合物の単膜の絶対量子収率ＰＬＱＥ］ ≪Outline of organic electroluminescence element≫
The organic electroluminescence device of the present invention is an organic electroluminescence device having a light emitting layer,
The light emitting layer contains a phosphorescent compound and a fluorescent compound,
The emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound have an overlap,
The emission decay lifetime τ of the light emitting layer single layer satisfies the following formula (1):
The absolute quantum yield PLQE (φ) of the single light emitting layer satisfies the following formula (2):
The Stokes shift of the said fluorescent compound is 0.1 eV or less, The organic electroluminescent element characterized by the above-mentioned.
0 <τ / τ 0 ≦ 0.7 (1)
0.6 ≦ φ / φ 0 ≦ 1.0 (2)
[Τ: emission decay lifetime of the single layer of the light emitting layer τ 0 : emission decay lifetime of the single layer of the phosphorescent compound φ: absolute quantum yield PLQE of the single layer of the light emitting layer
φ 0 : absolute quantum yield PLQE of the phosphorescent compound single film]
　［スペクトルの重なり］
　本発明に係るリン光発光性化合物の発光スペクトルと蛍光発光性化合物の吸収スペクトルとは、重なりを有する。
　上述のように、フェルスター型エネルギー移動を効率的に発現させる主な因子として、リン光発光性化合物の発光スペクトルと蛍光発光性化合物の吸収スペクトルの重なりがある。
　ここで、リン光発光性化合物の発光スペクトルと蛍光発光性化合物の吸収スペクトルとが重なりを有するとは、リン光発光性化合物の発光スペクトルと、蛍光発光性化合物の最も長波長側に位置する吸収帯とが重なることをいう。
　前記各スペクトルの重なりの大きさは重なり積分値と呼ばれ、下記式（ＯＩ）で算出されることが知られている。 [Spectral overlap]
The emission spectrum of the phosphorescent compound according to the present invention and the absorption spectrum of the fluorescent compound have an overlap.
As described above, there is an overlap between the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound as a main factor for efficiently expressing the Forster energy transfer.
Here, the fact that the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound have an overlap means that the emission spectrum of the phosphorescent compound and the absorption located on the longest wavelength side of the fluorescent compound. It means that the belt overlaps.
It is known that the magnitude of the overlap of each spectrum is called an overlap integral value and is calculated by the following equation (OI).
Figure JPOXMLDOC01-appb-M000002
Figure JPOXMLDOC01-appb-M000002
　上式（ＯＩ）中のｆDは規格化されたドナー（エネルギー供与体、リン光発光性化合物
）発光スペクトル、εAはアクセプター（エネルギー受容体、蛍光発光性化合物）のモル
吸光係数を示す。λは波長を示す。なお、Ｊは、重なり積分値を表す。 In the above formula (OI), f D is a normalized donor (energy donor, phosphorescent compound) emission spectrum, and ε A is a molar extinction coefficient of the acceptor (energy acceptor, fluorescent compound). λ indicates a wavelength. J represents an overlap integral value.
　［蛍光発光性化合物のストークスシフト］
　本発明は、蛍光発光性化合物のストークスシフトが、０．１ｅＶ以下であり、最小値は０ｅＶである。
　なお、ストークスシフトとは、吸収極大と発光蛍光極大とのエネルギー差（又は波長の差。）をいう。本発明においては、後述のように、溶液吸収スペクトルの最長波側の吸収帯の極大吸収波長λabs（ｎｍ）と、溶液発光スペクトルの最も短波側の極大発光波長λem（ｎｍ）をエネルギー（ｅＶ）に換算し、その差分より求める。 [Stokes shift of fluorescent compounds]
In the present invention, the Stokes shift of the fluorescent compound is 0.1 eV or less, and the minimum value is 0 eV.
The Stokes shift refers to the energy difference (or wavelength difference) between the absorption maximum and the emission fluorescence maximum. In the present invention, as will be described later, the maximum absorption wavelength λ abs (nm) of the absorption band on the longest wave side of the solution absorption spectrum and the maximum emission wavelength λ em (nm) of the shortest wave side of the solution emission spectrum are represented by energy ( eV) and obtained from the difference.
　（蛍光発光性化合物のストークスシフトの測定手法）
　溶液吸収スペクトルの最長波側の吸収帯の極大吸収波長λabs（ｎｍ）と、溶液発光スペクトルの最も短波側の極大発光波長λem（ｎｍ）をエネルギー（ｅＶ）に換算し、その差分より求めた。具体的には、下記式でストークスシフトを算出した。
　ストークスシフト（ｅＶ）＝｜１２４０／λabs－１２４０／λem｜ (Measurement method of Stokes shift of fluorescent compounds)
The maximum absorption wavelength λ abs (nm) of the absorption band on the longest wave side of the solution absorption spectrum and the maximum emission wavelength λ em (nm) of the shortest wave side of the solution emission spectrum are converted into energy (eV) and obtained from the difference. It was. Specifically, the Stokes shift was calculated by the following formula.
Stokes shift (eV) = | 1240 / λ abs −1240 / λ em |
　（極大吸収波長λabs及び極大発光波長λemの測定）
　上記蛍光発光性化合物の極大吸収波長λabs及び極大発光波長λemについては、紫外線可視赤外分光光度計（例えば、日本分光社製Ｕ－５７０）を用いて測定することができる。
　なお、本発明において、極大吸収波長λabs及び極大発光波長λemの測定における各溶
液の温度は２３℃とする。 (Measurement of maximum absorption wavelength λabs and maximum emission wavelength λem )
The maximum absorption wavelength λ abs and the maximum emission wavelength λ em of the fluorescent compound can be measured using an ultraviolet-visible-infrared spectrophotometer (for example, U-570 manufactured by JASCO Corporation).
In the present invention, the temperature of each solution in the measurement of the maximum absorption wavelength λ abs and the maximum emission wavelength λ em is 23 ° C.
　［（１）～（４）式の説明］
　＜（１）式＞
　リン光発光性化合物の発光層に蛍光発光性化合物を添加することで、リン光発光性化合物上に生成した励起エネルギーを蛍光発光性化合物にフェルスター型エネルギー移動又はデクスター型エネルギー移動により、速やかに蛍光発光性化合物へ移動させ消費することができる。その結果、リン光発光性化合物の発光減衰寿命がサブマイクロ秒～ナノ秒オーダーに短縮される。
　発明者は、リン光発光性化合物の発光減衰寿命の短縮（τ／τ0）が０．７以下であれ
ば、有機ＥＬ素子の半減寿命の加速係数を下げる効果が大きいことを見出した。
　なお、本発明において、０より大きければ、τ／τ0は小さいほどよい。 [Explanation of equations (1) to (4)]
<(1) Formula>
By adding a fluorescent compound to the phosphorescent compound emitting layer, the excitation energy generated on the phosphorescent compound can be rapidly transferred to the fluorescent compound by Forster-type energy transfer or Dexter-type energy transfer. It can be transferred to a fluorescent compound and consumed. As a result, the emission decay lifetime of the phosphorescent compound is shortened to the order of submicroseconds to nanoseconds.
The inventor has found that if the shortening of the emission decay lifetime of the phosphorescent compound (τ / τ 0 ) is 0.7 or less, the effect of lowering the acceleration factor of the half-life of the organic EL element is great.
In the present invention, the larger τ / τ 0 is, the better it is.
　＜（２）式＞
　実用的なリン光発光性化合物は１００％に近い高い絶対量子収率（すなわち、リン光発光性化合物の単膜の絶対量子収率φ0）を有しており、蛍光発光性化合物を添加しても、
上記のデクスター型エネルギー移動による絶対量子収率の低下を抑制し、高い絶対量子収率を維持することが望まれる。
　以上の観点から、φ／φ0が０．６～１．０の範囲内であれば、実用的な発光素子性能
を維持することができる。なお、リン光単独のφ0を維持する（低下しない）という意味
で、φ／φ0の最大値は１．０である。 <(2) Formula>
A practical phosphorescent compound has a high absolute quantum yield close to 100% (that is, an absolute quantum yield φ 0 of a single film of the phosphorescent compound), and a fluorescent compound is added. Even
It is desired to suppress a decrease in absolute quantum yield due to the above Dexter type energy transfer and maintain a high absolute quantum yield.
From the above viewpoint, practical light-emitting element performance can be maintained if φ / φ 0 is in the range of 0.6 to 1.0. It should be noted that the maximum value of φ / φ 0 is 1.0 in the sense that φ 0 of phosphorescence alone is maintained (does not decrease).
　＜（３）又は（４）式＞
　本発明の技術では、リン光発光性化合物の三重項励起状態の励起エネルギーを蛍光発光性化合物の一重項励起状態へフェルスター型エネルギー移動させて、蛍光発光させることが必要なので、発光層に注入された電荷はリン光発光性化合物上で再結合することが好ましい。（３）式を満たすことで、正孔は、リン光発光性化合物へ注入され、トラップされやすくなる。また、（４）式を満たすことで発光層に注入された電子は、リン光発光性化合物へ注入され、トラップされやすくなる。リン光発光性化合物上で電荷を再結合させるには、正孔及び電子の両方をリン光発光性化合物上にトラップさせる必要はなく、どちらか一方のみで構わない。よって、（３）又は（４）式を満たすことで、発光層に注入された電荷がリン光発光性化合物上で再結合する確率がより高くなり、蛍光発光性化合物上で再結合することを抑制できる。その結果、外部取り出し効率（ＥＱＥ）の低下をより抑制できる。 <Formula (3) or (4)>
In the technology of the present invention, it is necessary to transfer the excitation energy in the triplet excited state of the phosphorescent compound to the singlet excited state of the fluorescent compound to cause fluorescence emission. It is preferred that the generated charges recombine on the phosphorescent compound. By satisfying the formula (3), holes are injected into the phosphorescent compound and easily trapped. Further, when the formula (4) is satisfied, the electrons injected into the light emitting layer are injected into the phosphorescent compound and easily trapped. In order to recombine charges on the phosphorescent compound, it is not necessary to trap both holes and electrons on the phosphorescent compound, and only one of them may be used. Therefore, by satisfying the formula (3) or (4), the probability that the charge injected into the light emitting layer is recombined on the phosphorescent compound is higher, and recombination is performed on the fluorescent compound. Can be suppressed. As a result, a decrease in external extraction efficiency (EQE) can be further suppressed.
　（発光層単層の発光減衰寿命τ等の求め方）
　発光層単層の発光減衰寿命は、後述の評価用発光性膜のような、発光層と同様の構成の単膜を製造し、当該単膜について、発光減衰寿命を計測すればよい。なお、発光減衰寿命τは、ストリークカメラＣ４３３４（浜松ホトニクス社製）を用いることで計測可能である。
　また、リン光発光性化合物の単膜の発光減衰寿命τ0は、発光減衰寿命τを計測した評
価用発光性膜において、蛍光発光性化合物を含有させないほかは同様にして製造した単膜について、発光層単層の発光減衰寿命τと同様に計測すればよい。 (How to find the emission decay lifetime τ, etc. of a single light emitting layer)
The light emission decay lifetime of the single light emission layer may be measured by manufacturing a single film having the same structure as the light emission layer, such as a light emitting film for evaluation described later, and measuring the light emission decay lifetime of the single film. The emission decay lifetime τ can be measured by using a streak camera C4334 (manufactured by Hamamatsu Photonics).
Further, the emission decay lifetime τ 0 of the phosphorescent compound single film is the same as that of the evaluation light emitting film obtained by measuring the emission decay lifetime τ except that the fluorescent emission compound is not contained. What is necessary is just to measure similarly to the light emission decay lifetime τ of the light emitting layer.
　（発光層単層の絶対量子収率ＰＬＱＥ（φ）等の求め方）
　発光層単層の絶対量子収率ＰＬＱＥ（φ）は、評価用発光性膜のような、発光層と同様の構成の単膜を製造し、当該単膜について、絶対量子収率ＰＬＱＥ（φ）を測定すればよい。なお、ＰＬＱＥの測定は、絶対量子収率測定装置Ｃ９９２０－０２（浜松ホトニクス社製）を用いることで可能である。
　また、リン光発光性化合物の単膜の絶対量子収率ＰＬＱＥ（φ0）は、絶対量子収率Ｐ
ＬＱＥ（φ）を計測した評価用発光性膜において、蛍光発光性化合物を含有させないほかは同様にして製造した単膜について、発光層単層の発光減衰寿命τと同様に計測すればよい。 (How to obtain absolute quantum yield PLQE (φ), etc. of light emitting layer)
The absolute quantum yield PLQE (φ) of the light emitting layer is a single film having the same structure as that of the light emitting layer, such as a light-emitting film for evaluation. Can be measured. Note that PLQE can be measured by using an absolute quantum yield measuring apparatus C9920-02 (manufactured by Hamamatsu Photonics).
The absolute quantum yield PLQE (φ 0 ) of the phosphorescent compound single film is the absolute quantum yield P
In the evaluation light emitting film in which LQE (φ) is measured, a single film manufactured in the same manner except that no fluorescent light emitting compound is contained may be measured in the same manner as the light emission decay lifetime τ of the light emitting layer single layer.
　（ＨＯＭＯ、ＬＵＭＯ）
　ＬＵＭＯとは化合物の最低空分子軌道である。そして、ＬＵＭＯエネルギー準位とは、真空準位にある電子が化合物のＬＵＭＯに落ちて安定化するエネルギーであり、真空準位を０としたときのエネルギーで定義される。 (HOMO, LUMO)
LUMO is the lowest unoccupied molecular orbital of a compound. The LUMO energy level is energy in which electrons in the vacuum level fall to the LUMO of the compound and stabilize, and are defined as energy when the vacuum level is zero.
　ＨＯＭＯとは化合物の最高被占分子軌道である。そして、ＨＯＭＯエネルギー準位とは、ＨＯＭＯにある電子を、真空準位に移動させるのに要するエネルギーに－１を掛けて得られた値で定義される。 HOMO is the highest occupied molecular orbital of a compound. The HOMO energy level is defined as a value obtained by multiplying the energy required to move electrons in the HOMO to the vacuum level by -1.
　（ＨＯＭＯエネルギー準位及びＬＵＭＯエネルギー準位の計算方法）
　本発明における蛍光発光性化合物又はリン光発光性化合物の分子軌道計算による構造最適化及び電子密度分布の算出（ＨＯＭＯ（Ｐ）、ＬＵＭＯ（Ｐ）、ＨＯＭＯ（Ｆ）、ＬＵＭＯ（Ｆ）の算出）は、計算方法として、ホスト化合物、蛍光発光性化合物は汎関数としてＢ３ＬＹＰ、基底関数として６－３１Ｇ（ｄ）を用い、リン光発光性化合物には汎関数としてＢ３ＬＹＰを、基底関数としてＬａｎＬ２ＤＺを用いた分子軌道計算用ソフトウェアを用いて算出することができ、ソフトウェアに特に限定はなく、いずれを用いても同様に求めることができる。
　具体的には、例えば、分子軌道計算用ソフトウェアとして、米国Ｇａｕｓｓｉａｎ社製のＧａｕｓｓｉａｎ０９（Ｒｅｖｉｓｉｏｎ　Ｃ．０１，Ｍ．Ｊ．Ｆｒｉｓｃｈ，ｅｔ　ａｌ，Ｇａｕｓｓｉａｎ，Ｉｎｃ．，２０１０．）を用いることができる。 (Calculation method of HOMO energy level and LUMO energy level)
Structure optimization and calculation of electron density distribution by molecular orbital calculation of fluorescent compound or phosphorescent compound in the present invention (calculation of HOMO (P), LUMO (P), HOMO (F), LUMO (F)) As a calculation method, B3LYP is used as the functional for the host compound and fluorescent compound, and 6-31G (d) is used as the basis function, B3LYP is used as the functional for the phosphorescent compound, and LanL2DZ is used as the basis function. The molecular orbital calculation software can be used for calculation, and there is no particular limitation on the software, and any of them can be similarly used.
Specifically, for example, Gaussian 09 (Revision C.01, MJ Frisch, et al, Gaussian, Inc., 2010.) manufactured by Gaussian, USA can be used as software for molecular orbital calculation.
　［発光層］
　発光層は、リン光発光性化合物及び蛍光発光性化合物を含有する。
　また、発光層単層の発光減衰寿命τは、上記（１）式を満たし、前記発光層単層の絶対量子収率ＰＬＱＥ（φ）は上記（２）式を満たす。
　本発明に係る発光層は、電極又は隣接する層（以下、「隣接層」ともいう。）から注入されてくる電子及び正孔が再結合し、励起子を経由して発光する場を提供する層であり、発光する部分は発光層の層内であっても、発光層と隣接層との界面であってもよい。 [Light emitting layer]
The light emitting layer contains a phosphorescent compound and a fluorescent compound.
The emission decay lifetime τ of the single light emitting layer satisfies the above formula (1), and the absolute quantum yield PLQE (φ) of the single light emitting layer satisfies the above formula (2).
The light emitting layer according to the present invention provides a field in which electrons and holes injected from an electrode or an adjacent layer (hereinafter also referred to as “adjacent layer”) are recombined to emit light via excitons. The layer that emits light may be within the light emitting layer or at the interface between the light emitting layer and the adjacent layer.
　なお、本発明に係る発光層単層とは、ホスト化合物と、リン光発光性化合物と、蛍光発光性化合物とを含有する、スペクトル測定試料として作製される評価用発光性膜をいう。なお、この評価用発光性膜の具体的な製造方法については、実施例にて詳述する。
　また、リン光発光性化合物の単膜とは、ホスト化合物と、リン光発光性化合物と、蛍光発光性化合物とを含有する上記評価用発光性膜において、ホスト化合物と、リン光発光性化合物とを含有する発光性膜のことをいう。このように、リン光発光性化合物の単膜とは、蛍光発光性化合物を含有せず、本発明に係るτ／τ0、φ／φ0を求めるための評価用の発光性単膜である。 In addition, the light emitting layer single layer concerning this invention means the light emitting film for evaluation produced as a spectrum measurement sample containing a host compound, a phosphorescent light emitting compound, and a fluorescent light emitting compound. In addition, the specific manufacturing method of this light emitting film for evaluation will be described in detail in Examples.
In addition, the phosphorescent compound single film is a host compound, a phosphorescent compound, and a fluorescent compound, and includes the host compound, the phosphorescent compound, and the evaluation light emitting film. A luminescent film containing Thus, the phosphorescent compound single film is a luminescent single film for evaluation for obtaining τ / τ 0 and φ / φ 0 according to the present invention, which does not contain a fluorescent compound. .
　（発光層の厚さ）
　発光層は、厚さ３０ｎｍ以下の薄層とすることができる。本発明に係る発光層であれば、薄層及び励起子密度が高くても高効率及び長寿命の効果を奏することができるためである。
　なお、発光層の厚さは、２ｎｍ以上であることが好ましい。 (Light emitting layer thickness)
The light emitting layer can be a thin layer having a thickness of 30 nm or less. This is because the light emitting layer according to the present invention can achieve the effects of high efficiency and long life even when the thin layer and exciton density are high.
In addition, it is preferable that the thickness of a light emitting layer is 2 nm or more.
　＜リン光発光性化合物＞
　リン光発光性化合物としては、公知のものを使用できる。本発明に使用できる公知のリン光発光性化合物の具体例としては、後述の文献に記載されている化合物等が挙げられるがこれに限るものではない。
　以下に、本発明で好適に使用できるリン光発光性化合物の具体的な例として、青色リン光発光性化合物について説明する。 <Phosphorescent compound>
Known phosphorescent compounds can be used. Specific examples of known phosphorescent compounds that can be used in the present invention include, but are not limited to, compounds described in the following literature.
Below, a blue phosphorescent compound is demonstrated as a specific example of the phosphorescent compound which can be used conveniently by this invention.
　本発明に係るリン光発光性化合物の具体的な例としての青色リン光発光性化合物は、重原子を含有し、三重項励起状態からの発光が可能な化合物であり、三重項励起状態からの発光が観測される限り特に限定されない。好ましくは、下記一般式（１）で表される青色リン光発光性化合物である。これにより、より励起子の安定性な青色リン光発光性化合物を作製できる。 A blue phosphorescent compound as a specific example of the phosphorescent compound according to the present invention is a compound containing a heavy atom and capable of emitting light from a triplet excited state. As long as luminescence is observed, there is no particular limitation. A blue phosphorescent compound represented by the following general formula (1) is preferable. Thereby, a blue phosphorescent compound having more exciton stability can be produced.
Figure JPOXMLDOC01-appb-C000003
Figure JPOXMLDOC01-appb-C000003
　前記一般式（１）において、Ｍは、Ｉｒ又はＰｔを表す。Ａ1、Ａ2、Ｂ1及びＢ2は、それぞれ独立に炭素原子又は窒素原子を表す。環Ｚ1は、Ａ1及びＡ2とともに形成される６員の芳香族炭化水素環又は５員若しくは６員の芳香族複素環、又はこれらの環のうちの少なくとも１つを含む芳香族縮合環を表す。環Ｚ2は、Ｂ1及びＢ2とともに形成される５員若しくは６員の芳香族複素環、又はこれらの環のうちの少なくとも１つを含む芳香族縮合環を表す。前記環Ｚ1及び環Ｚ2が有する炭素原子は、カルベン炭素原子であってもよい。Ａ1とＭとの結合及びＢ1とＭとの結合は、一方が配位結合であり、他方は共有結合を表す。環Ｚ1及び環Ｚ2は、それぞれ独立に置換基を有していてもよい。環Ｚ1及び環Ｚ2の置換基が結合することによって、縮環構造を形成していてもよく、環Ｚ1と環Ｚ2とで表される配位子同士が連結していてもよい。Ｌは、Ｍに配位したモノアニオン性の二座配位子を表し、置換基を有していてもよい。ｍは、０～２の整数を表す。ｎは、１～３の整数を表す。ＭがＩｒの場合のｍ＋ｎは３であり、ＭがＰｔの場合のｍ＋ｎは２である。ｍ又はｎが２以上のとき、環Ｚ1と環Ｚ2とで表される配位子又はＬはそれぞれ同じでも異なっていてもよく、環Ｚ1と環Ｚ2とで表される配位子とＬとは連結していてもよい。 In the general formula (1), M represents Ir or Pt. A 1 , A 2 , B 1 and B 2 each independently represent a carbon atom or a nitrogen atom. Ring Z 1 is a 6-membered aromatic hydrocarbon ring or 5-membered or 6-membered aromatic heterocycle formed together with A 1 and A 2 , or an aromatic condensed ring containing at least one of these rings Represents. Ring Z 2 represents a 5-membered or 6-membered aromatic heterocycle formed together with B 1 and B 2 , or an aromatic condensed ring containing at least one of these rings. The carbon atom contained in the ring Z 1 and the ring Z 2 may be a carbene carbon atom. One of the bond between A 1 and M and the bond between B 1 and M is a coordination bond, and the other represents a covalent bond. Ring Z 1 and ring Z 2 may each independently have a substituent. By substituents of the ring Z 1 and the ring Z 2 are attached, may form a condensed ring structure, ligands each other represented by the ring Z 1 and the ring Z 2 may be linked . L represents a monoanionic bidentate ligand coordinated to M and may have a substituent. m represents an integer of 0-2. n represents an integer of 1 to 3. M + n is 3 when M is Ir, and m + n is 2 when M is Pt. When m or n is 2 or more, the ligands or Ls represented by ring Z 1 and ring Z 2 may be the same or different, and the coordination represented by ring Z 1 and ring Z 2 The child and L may be connected.
　なお、環Ｚ2は好ましくは５員の芳香族複素環であり、Ｂ1及びＢ2は少なくとも一方が窒素原子であることが好ましい。一般式（１）は、好ましくは下記一般式（ＤＰ－１で表される。 Ring Z 2 is preferably a 5-membered aromatic heterocycle, and at least one of B 1 and B 2 is preferably a nitrogen atom. The general formula (1) is preferably represented by the following general formula (DP-1).
Figure JPOXMLDOC01-appb-C000004
Figure JPOXMLDOC01-appb-C000004
　上記一般式（ＤＰ－１）において、Ｍ、Ａ1、Ａ2、Ｂ1、Ｂ2、環Ｚ1、Ｌ、ｍ及びｎは、一般式（１）におけるＭ、Ａ1、Ａ2、Ｂ1、Ｂ2、環Ｚ1、Ｌ、ｍ及びｎと同義である。 In the general formula (DP-1), M, A 1 , A 2 , B 1 , B 2 , rings Z 1 , L, m and n are M, A 1 , A 2 , B in the general formula (1). 1 , B 2 , synonymous with rings Z 1 , L, m and n.
　Ｂ3～Ｂ5は芳香族複素環を形成する原子群であり、それぞれ独立して、置換基を有していてもよい炭素原子、窒素原子、酸素原子又は硫黄原子を表す。Ｂ3～Ｂ5が有する置換基としては、前述の一般式（１）における環Ｚ1及び環Ｚ2が有する置換基と同義の基が挙げられる。 B 3 to B 5 are an atomic group forming an aromatic heterocyclic ring, and each independently represents a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom which may have a substituent. Examples of the substituent that B 3 to B 5 have include the same groups as the substituents that the ring Z 1 and the ring Z 2 have in General Formula (1).
　一般式（ＤＰ－１）においてＢ1～Ｂ5で形成される芳香族複素環は、下記一般式（ＤＰ－１ａ）、（ＤＰ－１ｂ）及び（ＤＰ－１ｃ）のいずれかで表されることが好ましい。 The aromatic heterocycle formed by B 1 to B 5 in the general formula (DP-1) is represented by any of the following general formulas (DP-1a), (DP-1b) and (DP-1c) It is preferable.
Figure JPOXMLDOC01-appb-C000005
Figure JPOXMLDOC01-appb-C000005
　一般式（ＤＰ－１ａ）、（ＤＰ－１ｂ）及び（ＤＰ－１ｃ）において、＊１は一般式（ＤＰ－１）のＡ2との結合部位を表し、＊２はＭとの結合部位を表す。
　Ｒｂ3～Ｒｂ5は水素原子又は置換基を表し、Ｒｂ3～Ｒｂ5で表される置換基としては、前述の一般式（１）における環Ｚ1及び環Ｚ2が有する置換基と同義の基が挙げられる。
　一般式（ＤＰ－１ａ）におけるＢ4及びＢ5は、炭素原子又は窒素原子であり、より好ましくは少なくとも一つが炭素原子である。
　一般式（ＤＰ－１ｂ）におけるＢ3～Ｂ5は、炭素原子又は窒素原子であり、より好ましくは少なくとも一つは炭素原子である。
　一般式（ＤＰ－１ｃ）におけるＢ3及びＢ4は、炭素原子又は窒素原子であり、より好ましくは少なくとも一つは炭素原子であり、Ｒｂ3とＲｂ4で表される置換基がさらに互いに結合して縮環構造を形成していることがより好ましく、このとき新たに形成される縮環構造は芳香族環であることが好ましく、ベンゾイミダゾール環、イミダゾピリジン環、イミダゾピラジン環又はプリン環のいずれかであることが好ましい。Ｒｂ5はアルキル基、ア
リール基であることが好ましく、フェニル基であることがより好ましい。 In the general formulas (DP-1a), (DP-1b) and (DP-1c), * 1 represents a binding site with A 2 in the general formula (DP-1), and * 2 represents a binding site with M. To express.
Rb 3 to Rb 5 represent a hydrogen atom or a substituent, and the substituent represented by Rb 3 to Rb 5 has the same meaning as the substituents of the ring Z 1 and the ring Z 2 in the general formula (1). Groups.
B 4 and B 5 in the general formula (DP-1a) are a carbon atom or a nitrogen atom, and more preferably at least one is a carbon atom.
B 3 to B 5 in the general formula (DP-1b) are carbon atoms or nitrogen atoms, and more preferably at least one is a carbon atom.
B 3 and B 4 in the general formula (DP-1c) are a carbon atom or a nitrogen atom, more preferably at least one is a carbon atom, and the substituents represented by Rb 3 and Rb 4 are further bonded to each other. It is more preferable that a condensed ring structure is formed, and the newly formed condensed ring structure is preferably an aromatic ring, and includes a benzimidazole ring, an imidazopyridine ring, an imidazopyrazine ring, or a purine ring. Either is preferable. Rb 5 is preferably an alkyl group or an aryl group, and more preferably a phenyl group.
　以下に一般式（１）の具体的な化合物例を示すが、本願で使用可能なものは、これらに限定されない。 Specific examples of the compound represented by the general formula (1) are shown below, but those usable in the present application are not limited to these.
Figure JPOXMLDOC01-appb-C000006
Figure JPOXMLDOC01-appb-C000006
Figure JPOXMLDOC01-appb-C000007
Figure JPOXMLDOC01-appb-C000007
Figure JPOXMLDOC01-appb-C000008
Figure JPOXMLDOC01-appb-C000008
Figure JPOXMLDOC01-appb-C000009
Figure JPOXMLDOC01-appb-C000009
Figure JPOXMLDOC01-appb-C000010
Figure JPOXMLDOC01-appb-C000010
Figure JPOXMLDOC01-appb-C000011
Figure JPOXMLDOC01-appb-C000011
Figure JPOXMLDOC01-appb-C000012
Figure JPOXMLDOC01-appb-C000012
　また、上記青色リン光発光性化合物において、環Ｚ1及び環Ｚ2が有する炭素原子がカルベン炭素原子である場合（具体的には、カルベン錯体である場合。）、例えば、国際公開第２００５／０１９３７３号公報、国際公開第２００６／０５６４１８号公報、国際公開第２００５／１１３７０４号公報、国際公開第２００７／１１５９７０号公報、国際公開第２００７／１１５９８１号公報及び国際公開第２００８／０００７２７号公報に記載されるカルベン錯体を好適に使用できる。 In the blue phosphorescent compound, when the carbon atoms of the ring Z 1 and the ring Z 2 are carbene carbon atoms (specifically, when they are carbene complexes), for example, WO 2005 / No. 0193373, International Publication No. 2006/056418, International Publication No. 2005/113704, International Publication No. 2007/115970, International Publication No. 2007/1155981, and International Publication No. 2008/000727. The carbene complex is preferably used.
　また、その他本発明において使用できる青色リン光発光性化合物及びその他の色のリン光発光性化合物としては、有機ＥＬ素子の発光層に使用される公知のものの中から適宜選択して用いることができる。
　なお、本発明に使用できる公知の青色リン光発光性化合物及びその他の色のリン光発光性化合物の具体例としては、以下の文献に記載されている化合物等が挙げられるがこれに限るものではない。
　Ｎａｔｕｒｅ　３９５，１５１（１９９８）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．７８，１６２２（２００１）、Ａｄｖ．Ｍａｔｅｒ．１９，７３９（２００７）、Ｃｈｅｍ．Ｍａｔｅｒ．　１７，３５３２（２００５）、Ａｄｖ．Ｍａｔｅｒ．１７，１０５９（２００５）、国際公開第２００９／１００９９１号、国際公開第２００８／１０１８４２号、国際公開第２００３／０４０２５７号、米国特許公開第２００６／８３５４６９号明細書、米国特許公開第２００６／０２０２１９４号明細書、米国特許公開第２００７／００８７３２１号明細書、米国特許公開第２００５／０２４４６７３号明細書、Ｉｎｏｒｇ．Ｃｈｅｍ．４０，１７０４（２００１）、Ｃｈｅｍ．Ｍａｔｅｒ．１６，２４８０（２００４）、Ａｄｖ．Ｍａｔｅｒ．１６，２００３（２００４）、Ａｎｇｅｗ．Ｃｈｅｍ．ｌｎｔ．Ｅｄ．２００６，４５，７８００、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．８６，１５３５０５（２００５）、Ｃｈｅｍ．Ｌｅｔｔ．３４，５９２（２００５）、Ｃｈｅｍ．Ｃｏｍｍｕｎ．２９０６（２００５）、Ｉｎｏｒｇ．Ｃｈｅｍ．４２，１２４８（２００３）、国際公開第２００９／０５０２９０号、国際公開第２００２／０１５６４５号、国際公開第２００９／０００６７３号、米国特許公開第２００２／００３４６５６号明細書、米国特許第７３３２２３２号明細書、米国特許公開第２００９／０１０８７３７号明細書、米国特許公開第２００９／００３９７７６号、米国特許第６９２１９１５号明細書、米国特許第６６８７２６６号明細書、米国特許公開第２００７／０１９０３５９号明細書、米国特許公開第２００６／０００８６７０号明細書、米国特許公開第２００９／０１６５８４６号明細書、米国特許公開第２００８／００１５３５５号明細書、米国特許第７２５０２２６号明細書、米国特許第７３９６５９８号明細書、米国特許公開第２００６／０２６３６３５号明細書、米国特許公開第２００３／０１３８６５７号明細書、米国特許公開第２００３／０１５２８０２号明細書、米国特許第７０９０９２８号明細書、Ａｎｇｅｗ．Ｃｈｅｍ．ｌｎｔ．Ｅｄ．４７，１（２００８）、Ｃｈｅｍ．Ｍａｔｅｒ．１８，５１１９（２００６）、Ｉｎｏｒｇ．Ｃｈｅｍ．４６，４３０８（２００７）、Ｏｒｇａｎｏｍｅｔａｌｌｉｃｓ　２３，３７４５（２００４）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．７４，１３６１（１９９９）、国際公開第２００２／００２７１４号、国際公開第２００６／００９０２４号、国際公開第２００６／０５６４１８号、国際公開第２００５／０１９３７３号、国際公開第２００５／１２３８７３号、国際公開第２００５／１２３８７３号、国際公開第２００７／００４３８０号、国際公開第２００６／０８２７４２号、米国特許公開第２００６／０２５１９２３号明細書、米国特許公開第２００５／０２６０４４１号明細書、米国特許第７３９３５９９号明細書、米国特許第７５３４５０５号明細書、米国特許第７４４５８５５号明細書、米国特許公開第２００７／０１９０３５９号明細書、米国特許公開第２００８／０２９７０３３号明細書、米国特許第７３３８７２２号明細書、米国特許公開第２００２／０１３４９８４号明細書、米国特許第７２７９７０４号明細書、米国特許公開第２００６／０９８１２０号明細書、米国特許公開第２００６／１０３８７４号明細書、国際公開第２００５／０７６３８０号、国際公開第２０１０／０３２６６３号、国際公開第２００８／１４０１１５号、国際公開第２００７／０５２４３１号、国際公開第２０１１／１３４０１３号、国際公開第２０１１／１５７３３９号、国際公開第２０１０／０８６０８９号、国際公開第２００９／１１３６４６号、国際公開第２０１２／０２０３２７号、国際公開第２０１１／０５１４０４号、国際公開第２０１１／００４６３９号、国際公開第２０１１／０７３１４９号、米国特許公開第２０１２／２２８５８３号明細書、米国特許公開第２０１２／２１２１２６号明細書、特開２０１２－０６９７３７号公報、特開２０１２－１９５５５４号公報、特開２００９－１１４０８６号公報、特開２００３－８１９８８号公報、特開２００２－３０２６７１号公報、特開２００２－３６３５５２号公報等である。 Further, other blue phosphorescent compounds and other color phosphorescent compounds that can be used in the present invention can be appropriately selected from known compounds used in the light emitting layer of an organic EL device. .
Specific examples of known blue phosphorescent compounds and other color phosphorescent compounds that can be used in the present invention include compounds described in the following documents, but are not limited thereto. Absent.
Nature 395, 151 (1998), Appl. Phys. Lett. 78, 1622 (2001), Adv. Mater. 19, 739 (2007), Chem. Mater. 17, 3532 (2005), Adv. Mater. 17, 1059 (2005), International Publication No. 2009/100991, International Publication No. 2008/101842, International Publication No. 2003/040257, US Patent Publication No. 2006/835469, US Patent Publication No. 2006/020202194. U.S. Patent Publication No. 2007/0087321, U.S. Patent Publication No. 2005/0244673, Inorg. Chem. 40, 1704 (2001), Chem. Mater. 16, 2480 (2004), Adv. Mater. 16, 2003 (2004), Angew. Chem. lnt. Ed. 2006, 45, 7800, Appl. Phys. Lett. 86, 153505 (2005), Chem. Lett. 34, 592 (2005), Chem. Commun. 2906 (2005), Inorg. Chem. 42, 1248 (2003), International Publication No. 2009/050290, International Publication No. 2002/015645, International Publication No. 2009/000673, US Patent Publication No. 2002/0034656, US Pat. No. 7,332,232, United States Patent Publication No. 2009/0108737, United States Patent Publication No. 2009/0039776, United States Patent No. 6921915, United States Patent No. 6,687,266, United States Patent Publication No. 2007/0190359, United States Patent Publication 2006/0008670, U.S. Patent Publication No. 2009/0165846, U.S. Patent Publication No. 2008/0015355, U.S. Pat. No. 7,250,226, U.S. Pat. No. 7,396,598, U.S. Pat. 2006/026 635 Pat, U.S. Patent Publication No. 2003/0138657, U.S. Patent Publication No. 2003/0152802, U.S. Patent No. 7090928, Angew. Chem. lnt. Ed. 47, 1 (2008), Chem. Mater. 18, 5119 (2006), Inorg. Chem. 46, 4308 (2007), Organometallics 23, 3745 (2004), Appl. Phys. Lett. 74, 1361 (1999), International Publication No. 2002/002714, International Publication No. 2006/009024, International Publication No. 2006/056418, International Publication No. 2005/019373, International Publication No. 2005/123873, International Publication No. 2005/123873, International Publication No. 2007/004380, International Publication No. 2006/082742, US Patent Publication No. 2006/0251923, US Publication No. 2005/0260441, US Pat. No. 7,393,599. U.S. Pat. No. 7,534,505, U.S. Pat. No. 7,445,855, U.S. Patent Publication No. 2007/0190359, U.S. Patent Publication No. 2008/0297033, U.S. Pat. No. 7,338,722, U.S. Pat. No. 2002 No. 034984, U.S. Pat. No. 7,279,704, U.S. Patent Publication No. 2006/098120, U.S. Publication No. 2006/103874, WO 2005/076380, WO 2010/032663 International Publication No. 2008/140115, International Publication No. 2007/052431, International Publication No. 2011/134013, International Publication No. 2011/157339, International Publication No. 2010/086089, International Publication No. 2009/113646, International Publication No. Publication No. 2012/020327, International Publication No. 2011/051404, International Publication No. 2011/004639, International Publication No. 2011/073149, US Patent Publication No. 2012/2285853, US Patent Publication No. 2012/212126 Description, JP 2012-069737 A, JP 2012-195554 A, JP 2009-114086 A, JP 2003-81988 A, JP 2002-302671 A, JP 2002-363552 A Etc.
　＜蛍光発光性化合物＞
　本発明に係る蛍光発光性化合物は、一重項励起状態からの発光が可能な化合物であり、一重項励起状態からの発光が観測される限り、（１）及び（２）式を満たし、かつ、ストークスシフトが、０．１ｅＶ以下であるものあれば特に限定されない。 <Fluorescent compound>
The fluorescent compound according to the present invention is a compound that can emit light from a singlet excited state, satisfies the formulas (1) and (2) as long as light emission from the singlet excited state is observed, and There is no particular limitation as long as the Stokes shift is 0.1 eV or less.
　蛍光発光性化合物としては、例えば、アントラセン誘導体、ピレン誘導体、クリセン誘導体、フルオランテン誘導体、ペリレン誘導体、フルオレン誘導体、アリールアセチレン誘導体、スチリルアリーレン誘導体、スチリルアミン誘導体、アリールアミン誘導体、ホウ素錯体、クマリン誘導体、ピラン誘導体、シアニン誘導体、クロコニウム誘導体、スクアリウム誘導体、オキソベンツアントラセン誘導体、フルオレセイン誘導体、ローダミン誘導体、ピリリウム誘導体、ペリレン誘導体、ポリチオフェン誘導体、又は希土類錯体系化合物等が挙げられる。 Examples of the fluorescent compound include anthracene derivatives, pyrene derivatives, chrysene derivatives, fluoranthene derivatives, perylene derivatives, fluorene derivatives, arylacetylene derivatives, styrylarylene derivatives, styrylamine derivatives, arylamine derivatives, boron complexes, coumarin derivatives, pyran. Derivatives, cyanine derivatives, croconium derivatives, squalium derivatives, oxobenzanthracene derivatives, fluorescein derivatives, rhodamine derivatives, pyrylium derivatives, perylene derivatives, polythiophene derivatives, rare earth complex compounds, and the like.
　また、近年では遅延蛍光を利用する発光化合物も開発されており、これらを用いてもよい。 In recent years, light emitting compounds utilizing delayed fluorescence have been developed, and these may be used.
　遅延蛍光を利用する発光化合物の具体例としては、例えば、国際公開第２０１１／１５６７９３号、特開２０１１－２１３６４３号公報、特開２０１０－９３１８１号公報等に記載の化合物が挙げられるが、本発明はこれらに限定されない。 Specific examples of the luminescent compound using delayed fluorescence include, for example, the compounds described in International Publication No. 2011/156793, Japanese Patent Application Laid-Open No. 2011-213643, Japanese Patent Application Laid-Open No. 2010-93181, and the like. Is not limited to these.
　以下に、本発明に係る蛍光発光性化合物として使用できる化合物の具体例を記載するが、本発明に係る蛍光発光性化合物は、これに限定されない。 Hereinafter, specific examples of compounds that can be used as the fluorescent compound according to the present invention will be described, but the fluorescent compound according to the present invention is not limited thereto.
Figure JPOXMLDOC01-appb-C000013
Figure JPOXMLDOC01-appb-C000013
Figure JPOXMLDOC01-appb-C000014
Figure JPOXMLDOC01-appb-C000014
Figure JPOXMLDOC01-appb-C000015
Figure JPOXMLDOC01-appb-C000015
Figure JPOXMLDOC01-appb-C000016
Figure JPOXMLDOC01-appb-C000016
Figure JPOXMLDOC01-appb-C000017
Figure JPOXMLDOC01-appb-C000017
Figure JPOXMLDOC01-appb-C000018
Figure JPOXMLDOC01-appb-C000018
Figure JPOXMLDOC01-appb-C000019
Figure JPOXMLDOC01-appb-C000019
Figure JPOXMLDOC01-appb-C000020
Figure JPOXMLDOC01-appb-C000020
Figure JPOXMLDOC01-appb-C000021
Figure JPOXMLDOC01-appb-C000021
Figure JPOXMLDOC01-appb-C000022
Figure JPOXMLDOC01-appb-C000022
Figure JPOXMLDOC01-appb-C000023
Figure JPOXMLDOC01-appb-C000023
Figure JPOXMLDOC01-appb-C000024
Figure JPOXMLDOC01-appb-C000024
Figure JPOXMLDOC01-appb-C000025
Figure JPOXMLDOC01-appb-C000025
Figure JPOXMLDOC01-appb-C000026
Figure JPOXMLDOC01-appb-C000026
Figure JPOXMLDOC01-appb-C000027
Figure JPOXMLDOC01-appb-C000027
Figure JPOXMLDOC01-appb-C000028
Figure JPOXMLDOC01-appb-C000028
Figure JPOXMLDOC01-appb-C000029
Figure JPOXMLDOC01-appb-C000029
　（蛍光発光性化合物の含有量）
　蛍光発光性化合物の含有量が大きいと、発光層単層の発光減衰寿命は小さくなるが、絶対量子収率の低下が顕著となるので、その含有量は少ない方が好ましい。これは、下記のように考えている。
　蛍光発光性化合物の含有量が多くなると、リン光発光性化合物と蛍光発光性化合物の分子間距離が小さくなり、リン光発光性化合物の三重項励起状態よりも低い、蛍光発光性化合物の三重項励起状態へのデクスター型エネルギー移動が増大するので、絶対量子収率の低下が顕著となる（図２参照）。
　このため、蛍光発光性化合物の添加量は少量であることが好ましく、発光層に含まれる化合物の総量を１００質量％としたとき、前記蛍光発光性化合物の含有量（質量％）が、前記リン光発光性化合物の含有量（質量％）より少ないことが、外部取り出し量子効率及び半減寿命をより良好にできるため好ましい。
　具体的には、発光層に含まれる化合物（すなわち、ホスト化合物、リン光発光性化合物及び蛍光発光性化合物）の総量を１００質量％としたとき、蛍光発光性化合物の含有量は、５質量％以下であることが好ましい。このように、実用的な有機ＥＬ素子の発光性能を達成するには、５質量％以下が好ましく、更に好ましくは０．９質量％以下であり、その下限値は発光層単層の絶対量子収率を高く維持する観点から０質量％より大きければ、小さいほどよい。これにより、絶対量子収率を良好にでき、ひいては、外部取り出し量子効率及び半減寿命をより良好にできる。 (Content of fluorescent compound)
When the content of the fluorescent compound is large, the light emission decay lifetime of the light emitting layer single layer becomes small, but the decrease in absolute quantum yield becomes remarkable. Therefore, it is preferable that the content is small. This is considered as follows.
When the content of the fluorescent compound increases, the intermolecular distance between the phosphorescent compound and the fluorescent compound decreases, and the triplet of the fluorescent compound is lower than the triplet excited state of the phosphorescent compound. Since the Dexter-type energy transfer to the excited state increases, the absolute quantum yield decreases significantly (see FIG. 2).
For this reason, the addition amount of the fluorescent compound is preferably small. When the total amount of the compounds contained in the light emitting layer is 100% by mass, the content (% by mass) of the fluorescent compound is the phosphorous. Less than the content (% by mass) of the photoluminescent compound is preferable because the external extraction quantum efficiency and the half-life can be improved.
Specifically, when the total amount of compounds (that is, the host compound, the phosphorescent compound and the fluorescent compound) contained in the light emitting layer is 100% by mass, the content of the fluorescent compound is 5% by mass. The following is preferable. Thus, in order to achieve the light emitting performance of a practical organic EL device, the content is preferably 5% by mass or less, more preferably 0.9% by mass or less, and the lower limit is the absolute quantum yield of the single light emitting layer. From the viewpoint of maintaining a high rate, the smaller the content, the better. Thereby, an absolute quantum yield can be made favorable and by extension, external extraction quantum efficiency and a half life can be made more favorable.
　＜ホスト化合物＞
　本発明に係る発光層は、蛍光発光性化合物、リン光発光性化合物以外にホスト化合物も含むことが好ましい。
　本発明に係るホスト化合物は、発光層において主に電荷の注入及び輸送を担う化合物であり、有機ＥＬ素子においてそれ自体の発光は実質的に観測されない。 <Host compound>
The light emitting layer according to the present invention preferably contains a host compound in addition to the fluorescent compound and the phosphorescent compound.
The host compound according to the present invention is a compound mainly responsible for charge injection and transport in the light-emitting layer, and light emission itself is not substantially observed in the organic EL element.
　ホスト化合物は、好ましくは室温（２５℃）においてリン光発光のリン光量子収率が、０．１未満の化合物であり、更に好ましくはリン光量子収率が０．０１未満の化合物である。また、ホスト化合物の励起状態エネルギーは、同一層内に含有されるリン光発光性化合物の励起状態エネルギーよりも高いことが好ましい。 The host compound is preferably a compound having a phosphorescence quantum yield of phosphorescence of less than 0.1 at room temperature (25 ° C.), and more preferably a compound having a phosphorescence quantum yield of less than 0.01. The excited state energy of the host compound is preferably higher than the excited state energy of the phosphorescent compound contained in the same layer.
　ホスト化合物としては、公知のホスト化合物を単独で用いてもよく、又は複数併用してもよい。ホスト化合物を複数種用いることで、電荷の移動を調整することが可能であり、有機ＥＬ素子を高効率化することができる。
　本発明に係るホスト化合物としては、特に制限はなく、従来有機ＥＬ素子で用いられる化合物を用いることができる。低分子化合物でも繰り返し単位を有する高分子化合物でもよく、また、ビニル基やエポキシ基のような反応性基を有する化合物でもよい。
　公知のホスト化合物としては、正孔輸送能又は電子輸送能を有しつつ、且つ、発光の長波長化を防ぎ、さらに、有機ＥＬ素子を高温駆動時や素子駆動中の発熱に対して安定して動作させる観点から、高いガラス転移温度（Ｔｇ）を有することが好ましい。好ましくはＴｇが９０℃以上であり、より好ましくは１２０℃以上である。
　ここで、ガラス転移点（Ｔｇ）とは、ＤＳＣ（Ｄｉｆｆｅｒｅｎｔｉａｌ　Ｓｃａｎｎｉｎｇ　Ｃａｌｏｒｉｍｅｔｒｙ：示差走査熱量法）を用いて、ＪＩＳ－Ｋ－７１２１に準拠した方法により求められる値である。 As the host compound, known host compounds may be used alone or in combination. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient.
There is no restriction | limiting in particular as a host compound based on this invention, The compound conventionally used with an organic EL element can be used. It may be a low molecular compound or a high molecular compound having a repeating unit, or a compound having a reactive group such as a vinyl group or an epoxy group.
As known host compounds, while having a hole transporting ability or an electron transporting ability, the emission of light is prevented from being increased in wavelength, and further, the organic EL element is stable against heat generation during high temperature driving or driving of the element. From the viewpoint of operating, it is preferable to have a high glass transition temperature (Tg). Tg is preferably 90 ° C. or higher, more preferably 120 ° C. or higher.
Here, the glass transition point (Tg) is a value determined by a method based on JIS-K-7121 using DSC (Differential Scanning Calorimetry).
　本発明に係るホスト化合物は、好ましくは下記一般式（ＨＡ）又は（ＨＢ）で表される構造を有する化合物である。 The host compound according to the present invention is preferably a compound having a structure represented by the following general formula (HA) or (HB).
Figure JPOXMLDOC01-appb-C000030
Figure JPOXMLDOC01-appb-C000030
Figure JPOXMLDOC01-appb-C000031
Figure JPOXMLDOC01-appb-C000031
　一般式（ＨＡ）及び（ＨＢ）中、Ｘａは、Ｏ又はＳを表す。Ｘｂ、Ｘｃ、Ｘｄ及びＸｅは、それぞれ独立に、水素原子、置換基又は下記一般式（ＨＣ）で表される構造を有する基を表すが、Ｘｂ、Ｘｃ、Ｘｄ及びＸｅのうち少なくとも一つは下記一般式（ＨＣ）で表される構造を有する基を表し、下記一般式（ＨＣ）で表される構造を有する基のうち少なくとも一つはＡｒがカルバゾリル基を表す。 In the general formulas (HA) and (HB), Xa represents O or S. Xb, Xc, Xd and Xe each independently represent a hydrogen atom, a substituent or a group having a structure represented by the following general formula (HC), and at least one of Xb, Xc, Xd and Xe is A group having a structure represented by the following general formula (HC) is represented, and at least one of the groups having a structure represented by the following general formula (HC) is a carbazolyl group.
　一般式（ＨＣ）
　　Ａｒ－（Ｌ′）ｎ－＊ General formula (HC)
Ar- (L ′) n- *
　一般式（ＨＣ）中、Ｌ′は、芳香族炭化水素環又は芳香族複素環から導出される２価の連結基を表す。ｎは０～３の整数を表し、ｎが２以上の場合、複数のＬ′は同じでもあっても異なっていてもよい。＊は、一般式（ＨＡ）又は（ＨＢ）との結合部位を表す。Ａｒは、下記一般式（ＨＤ）で表される構造を有する基を表す。 In general formula (HC), L ′ represents a divalent linking group derived from an aromatic hydrocarbon ring or an aromatic heterocyclic ring. n represents an integer of 0 to 3, and when n is 2 or more, a plurality of L ′ may be the same or different. * Represents a binding site with the general formula (HA) or (HB). Ar represents a group having a structure represented by the following general formula (HD).
Figure JPOXMLDOC01-appb-C000032
Figure JPOXMLDOC01-appb-C000032
　一般式（ＨＤ）中、Ｘｆは、Ｎ（Ｒ′）、Ｏ又はＳを表す。Ｅ１～Ｅ８はＣ（Ｒ″）又はＮを表し、Ｒ′及びＲ″は水素原子、置換基又は一般式（ＨＣ）におけるＬ′との結合部位を表す。＊は、一般式（ＨＣ）におけるＬ′との結合部位を表す。 In the general formula (HD), Xf represents N (R ′), O or S. E 1 to E 8 each represent C (R ″) or N, and R ′ and R ″ each represent a hydrogen atom, a substituent, or a bonding site with L ′ in the general formula (HC). * Represents a binding site with L ′ in the general formula (HC).
　上記一般式（ＨＡ）で表される構造を有する化合物においては、好ましくは、Ｘｂ、Ｘｃ、Ｘｄ及びＸｅのうち少なくとも二つが一般式（ＨＣ）で表され、より好ましくはＸｃが一般式（ＨＣ）で表され、かつ、当該一般式（ＨＣ）におけるＡｒが置換基を有していてもよいカルバゾリル基を表す。 In the compound having the structure represented by the general formula (HA), preferably at least two of Xb, Xc, Xd and Xe are represented by the general formula (HC), and more preferably Xc is represented by the general formula (HC). And Ar in the general formula (HC) represents a carbazolyl group which may have a substituent.
　一般式（ＨＡ）及び（ＨＢ）におけるＸｂ、Ｘｃ、Ｘｄ及びＸｅで表される置換基、並びに一般式（ＨＤ）におけるＲ′及びＲ″で表される置換基としては、上記一般式（ＤＰ）における環Ｚ１及び環Ｚ２が有していてもよい置換基と同様のものが挙げられる。 Examples of the substituents represented by Xb, Xc, Xd and Xe in the general formulas (HA) and (HB) and the substituents represented by R ′ and R ″ in the general formula (HD) include the above general formula (DP ) And the same substituents that the ring Z1 and ring Z2 may have.
　一般式（ＨＣ）におけるＬ′で表される芳香族炭化水素環としては、例えば、ベンゼン環、ｐ－クロロベンゼン環、メシチレン環、トルエン環、キシレン環、ナフタレン環、アントラセン環、アズレン環、アセナフテン環、フルオレン環、フェナントレン環、インデン環、ピレン環、ビフェニル環等が挙げられる。
　一般式（ＨＣ）におけるＬ′で表される芳香族複素環としては、例えば、フラン環、チオフェン環、ピリジン環、ピリダジン環、ピリミジン環、ピラジン環、トリアゾール環、イミダゾール環、ピラゾール環、チアゾール環、キナゾリン環、カルバゾール環、カルボリン環、ジアザカルバゾール環（カルボリン環を構成する任意の炭素原子の一つが窒素原子で置き換わったものを示す。）、フタラジン環等が挙げられる。 Examples of the aromatic hydrocarbon ring represented by L ′ in the general formula (HC) include a benzene ring, a p-chlorobenzene ring, a mesitylene ring, a toluene ring, a xylene ring, a naphthalene ring, an anthracene ring, an azulene ring, and an acenaphthene ring. Fluorene ring, phenanthrene ring, indene ring, pyrene ring, biphenyl ring and the like.
Examples of the aromatic heterocycle represented by L ′ in the general formula (HC) include a furan ring, a thiophene ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazole ring, an imidazole ring, a pyrazole ring, and a thiazole ring. Quinazoline ring, carbazole ring, carboline ring, diazacarbazole ring (in which one of carbon atoms constituting the carboline ring is replaced by a nitrogen atom), a phthalazine ring, and the like.
　以下に、本発明に係るホスト化合物の具体例として、上記一般式（ＨＡ）又は（ＨＢ）で表される構造を有する化合物の他、本発明に適用可能な化合物を挙げるが、本発明はこれらに特に限定されない。 Specific examples of the host compound according to the present invention include compounds applicable to the present invention in addition to the compound having the structure represented by the general formula (HA) or (HB). It is not specifically limited to.
Figure JPOXMLDOC01-appb-C000033
Figure JPOXMLDOC01-appb-C000033
Figure JPOXMLDOC01-appb-C000034
Figure JPOXMLDOC01-appb-C000034
Figure JPOXMLDOC01-appb-C000035
Figure JPOXMLDOC01-appb-C000035
Figure JPOXMLDOC01-appb-C000036
Figure JPOXMLDOC01-appb-C000036
Figure JPOXMLDOC01-appb-C000037
Figure JPOXMLDOC01-appb-C000037
Figure JPOXMLDOC01-appb-C000038
Figure JPOXMLDOC01-appb-C000038
Figure JPOXMLDOC01-appb-C000039
Figure JPOXMLDOC01-appb-C000039
Figure JPOXMLDOC01-appb-C000040
Figure JPOXMLDOC01-appb-C000040
Figure JPOXMLDOC01-appb-C000041
Figure JPOXMLDOC01-appb-C000041
Figure JPOXMLDOC01-appb-C000042
Figure JPOXMLDOC01-appb-C000042
Figure JPOXMLDOC01-appb-C000043
Figure JPOXMLDOC01-appb-C000043
Figure JPOXMLDOC01-appb-C000044
Figure JPOXMLDOC01-appb-C000044
Figure JPOXMLDOC01-appb-C000045
Figure JPOXMLDOC01-appb-C000045
　また、上記化合物のほか、本発明に係るホスト化合物の具体例としては、以下の文献に記載の化合物等を挙げることができるが、本発明はこれらに限定されない。 In addition to the above compounds, specific examples of the host compound according to the present invention include compounds described in the following documents, but the present invention is not limited thereto.
　特開２００１－２５７０７６号公報、同２００２－３０８８５５号公報、同２００１－３１３１７９号公報、同２００２－３１９４９１号公報、同２００１－３５７９７７号公報、同２００２－３３４７８６号公報、同２００２－８８６０号公報、同２００２－３３４７８７号公報、同２００２－１５８７１号公報、同２００２－３３４７８８号公報、同２００２－４３０５６号公報、同２００２－３３４７８９号公報、同２００２－７５６４５号公報、同２００２－３３８５７９号公報、同２００２－１０５４４５号公報、同２００２－３４３５６８号公報、同２００２－１４１１７３号公報、同２００２－３５２９５７号公報、同２００２－２０３６８３号公報、同２００２－３６３２２７号公報、同２００２－２３１４５３号公報、同２００３－３１６５号公報、同２００２－２３４８８８号公報、同２００３－２７０４８号公報、同２００２－２５５９３４号公報、同２００２－２６０８６１号公報、同２００２－２８０１８３号公報、同２００２－２９９０６０号公報、同２００２－３０２５１６号公報、同２００２－３０５０８３号公報、同２００２－３０５０８４号公報、同２００２－３０８８３７号公報、米国特許出願公開第２００３／０１７５５５３号明細書、米国特許出願公開第２００６／０２８０９６５号明細書、米国特許出願公開第２００５／０１１２４０７号明細書、米国特許出願公開第２００９／００１７３３０号明細書、米国特許出願公開第２００９／００３０２０２号明細書、米国特許出願公開第２００５／０２３８９１９号明細書、国際公開第２００１／０３９２３４号、国際公開第２００９／０２１１２６号、国際公開第２００８／０５６７４６号、国際公開第２００４／０９３２０７号、国際公開第２００５／０８９０２５号、国際公開第２００７／０６３７９６号、国際公開第２００７／０６３７５４号、国際公開第２００４／１０７８２２号、国際公開第２００５／０３０９００号、国際公開第２００６／１１４９６６号、国際公開第２００９／０８６０２８号、国際公開第２００９／００３８９８号、国際公開第２０１２／０２３９４７号、特開２００８－０７４９３９号公報、特開２００７－２５４２９７号公報、欧州特許第２０３４５３８号明細書等である。さらには、特開２０１５－３８９４１号公報の段落［０２５５］～［０２９３］に記載の化合物Ｈ－１～Ｈ－２３０も好適に使用できる。 JP-A-2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579, 2002-105445, 2002-343568, 2002-141173, 2002-352957, 2002-203683, 2002-363227, 2002-231453, 2003-3165, 2002-234888, 2003-27048, 2002-255934, 2002-260861, 2002-280183, 2002-299060, 2002 -302516, 2002-305083, 2002-305084, 2002-308837, U.S. Patent Application Publication No. 2003/0175553, U.S. Patent Application Publication No. 2006/0280965, US Patent Application Publication No. 2005/0112407, US Patent Application Publication No. 2009/0017330, US Patent Application Publication No. 2009/0030202, US Patent Application Publication No. 2005/0238919, International Publication 2001/039234, International Publication No. 2009/021126, International Publication No. 2008/056746, International Publication No. 2004/093207, International Publication No. 2005/089025, International Publication No. 2007/063796, International Publication No. 2007/2007 / No. 063754, International Publication No. 2004/107822, International Publication No. 2005/030900, International Publication No. 2006/114966, International Publication No. 2009/086028, International Publication No. 2009/003898, International Publication No. 2012/023947 JP-A-2008-074939, JP-A-2007-254297, European Patent No. 2034538, and the like. Furthermore, compounds H-1 to H-230 described in paragraphs [0255] to [0293] of JP-A-2015-38941 can also be suitably used.
　また、本発明に用いられるホスト化合物は、発光層に隣接する隣接層に用いてもよい。 The host compound used in the present invention may be used in an adjacent layer adjacent to the light emitting layer.
　以下、本発明の有機ＥＬ素子の構成層について概略を説明したうえで、発光層以外の各層についても詳述する。 Hereinafter, after explaining the outline of the constituent layers of the organic EL device of the present invention, each layer other than the light emitting layer will be described in detail.
　［有機エレクトロルミネッセンス素子の構成層］
　本発明の有機ＥＬ素子における代表的な素子構成としては、以下の構成を挙げることができるが、これらに限定されるものではない。
　（１）陽極／発光層／陰極
　（２）陽極／発光層／電子輸送層／陰極
　（３）陽極／正孔輸送層／発光層／陰極
　（４）陽極／正孔輸送層／発光層／電子輸送層／陰極
　（５）陽極／正孔輸送層／発光層／電子輸送層／電子注入層／陰極
　（６）陽極／正孔注入層／正孔輸送層／発光層／電子輸送層／陰極
　（７）陽極／正孔注入層／正孔輸送層／（電子阻止層／）発光層／（正孔阻止層／）電子輸送層／電子注入層／陰極
　前記の中で（７）の構成が好ましく用いられるが、これに限定されるものではない。 [Constitutional layer of organic electroluminescence element]
As typical element structures in the organic EL element of the present invention, the following structures can be exemplified, but the invention is not limited thereto.
(1) Anode / light emitting layer / cathode (2) Anode / light emitting layer / electron transport layer / cathode (3) Anode / hole transport layer / light emitting layer / cathode (4) Anode / hole transport layer / light emitting layer / electron Transport layer / cathode (5) Anode / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode (6) Anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / cathode ( 7) Anode / hole injection layer / hole transport layer / (electron blocking layer /) light emitting layer / (hole blocking layer /) electron transport layer / electron injection layer / cathode Among the above, the configuration of (7) is preferable. Although used, it is not limited to this.
　本発明に係る発光層は、単層又は複数層で構成されており、発光層が複数の場合は各発光層の間に非発光性の中間層を設けてもよい。 The light emitting layer according to the present invention is composed of a single layer or a plurality of layers, and when there are a plurality of light emitting layers, a non-light emitting intermediate layer may be provided between the light emitting layers.
　必要に応じて、発光層と陰極との間に正孔阻止層（正孔障壁層ともいう）や電子注入層（陰極バッファー層ともいう）を設けてもよく、また、発光層と陽極との間に電子阻止層（電子障壁層ともいう）や正孔注入層（陽極バッファー層ともいう）を設けてもよい。 If necessary, a hole blocking layer (also referred to as a hole blocking layer) or an electron injection layer (also referred to as a cathode buffer layer) may be provided between the light emitting layer and the cathode. An electron blocking layer (also referred to as an electron barrier layer) or a hole injection layer (also referred to as an anode buffer layer) may be provided therebetween.
　本発明に係る電子輸送層とは、電子を輸送する機能を有する層であり、広い意味で電子注入層、正孔阻止層も電子輸送層に含まれる。また、複数層で構成されていてもよい。 The electron transport layer according to the present invention is a layer having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. Moreover, you may be comprised by multiple layers.
　本発明に係る正孔輸送層とは、正孔を輸送する機能を有する層であり、広い意味で正孔注入層、電子阻止層も正孔輸送層に含まれる。また、複数層で構成されていてもよい。 The hole transport layer according to the present invention is a layer having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. Moreover, you may be comprised by multiple layers.
　前記の代表的な素子構成において、陽極と陰極を除いた層を「有機層」ともいう。 In the above-described typical element configuration, the layer excluding the anode and the cathode is also referred to as “organic layer”.
　（タンデム構造）
　また、本発明に係る有機ＥＬ素子は、少なくとも１層の発光層を含む発光ユニットを複数積層した、いわゆるタンデム構造の素子であってもよい。 (Tandem structure)
Further, the organic EL element according to the present invention may be an element having a so-called tandem structure in which a plurality of light emitting units including at least one light emitting layer are stacked.
　タンデム構造の代表的な素子構成としては、例えば以下の構成を挙げることができる。 As typical element configurations of the tandem structure, for example, the following configurations can be given.
　陽極／第１発光ユニット／第２発光ユニット／第３発光ユニット／陰極
　陽極／第１発光ユニット／中間層／第２発光ユニット／中間層／第３発光ユニット／陰極
　ここで、前記第１発光ユニット、第２発光ユニット及び第３発光ユニットは全て同じであっても、異なっていてもよい。また二つの発光ユニットが同じであり、残る一つが異なっていてもよい。 Anode / first light emitting unit / second light emitting unit / third light emitting unit / cathode Anode / first light emitting unit / intermediate layer / second light emitting unit / intermediate layer / third light emitting unit / cathode Here, the first light emitting unit The second light emitting unit and the third light emitting unit may all be the same or different. Two light emitting units may be the same, and the remaining one may be different.
　また、第３発光ユニットはなくてもよく、一方で第３発光ユニットと電極の間に更に発光ユニットや中間層を設けてもよい。 The third light emitting unit may not be provided, and on the other hand, a light emitting unit or an intermediate layer may be further provided between the third light emitting unit and the electrode.
　複数の発光ユニットは直接積層されていても、中間層を介して積層されていてもよく、中間層は、一般的に中間電極、中間導電層、電荷発生層、電子引抜層、接続層、中間絶縁層とも呼ばれ、陽極側の隣接層に電子を、陰極側の隣接層に正孔を供給する機能を持った層であれば、公知の材料構成を用いることができる。 A plurality of light emitting units may be laminated directly or via an intermediate layer, and the intermediate layer is generally an intermediate electrode, an intermediate conductive layer, a charge generation layer, an electron extraction layer, a connection layer, an intermediate layer. A known material structure can be used as long as it is also called an insulating layer and has a function of supplying electrons to the anode-side adjacent layer and holes to the cathode-side adjacent layer.
　中間層に用いられる材料としては、例えば、ＩＴＯ（インジウム・スズ酸化物）、ＩＺＯ（インジウム・亜鉛酸化物）、ＺｎＯ2、ＴｉＮ、ＺｒＮ、ＨｆＮ、ＴｉＯx、ＶＯx、
ＣｕＩ、ＩｎＮ、ＧａＮ、ＣｕＡｌＯ2、ＣｕＧａＯ2、ＳｒＣｕ2Ｏ2、ＬａＢ6、ＲｕＯ2、Ａｌ等の導電性無機化合物層や、Ａｕ／Ｂｉ2Ｏ3等の２層膜や、ＳｎＯ2／Ａｇ／Ｓｎ
Ｏ2、ＺｎＯ／Ａｇ／ＺｎＯ、Ｂｉ2Ｏ3／Ａｕ／Ｂｉ2Ｏ3、ＴｉＯ2／ＴｉＮ／ＴｉＯ2、
ＴｉＯ2／ＺｒＮ／ＴｉＯ2等の多層膜、またＣ60等のフラーレン類、オリゴチオフェン等の導電性有機物層、金属フタロシアニン類、無金属フタロシアニン類、金属ポルフィリン類、無金属ポルフィリン類等の導電性有機化合物層等が挙げられるが、本発明はこれらに限定されない。 Examples of the material used for the intermediate layer include ITO (indium tin oxide), IZO (indium zinc oxide), ZnO 2 , TiN, ZrN, HfN, TiO x , VO x ,
Conductive inorganic compound layers such as CuI, InN, GaN, CuAlO 2 , CuGaO 2 , SrCu 2 O 2 , LaB 6 , RuO 2 and Al, two-layer films such as Au / Bi 2 O 3 , SnO 2 / Ag / Sn
O 2 , ZnO / Ag / ZnO, Bi 2 O 3 / Au / Bi 2 O 3 , TiO 2 / TiN / TiO 2 ,
TiO 2 / ZrN / TiO 2 and other multilayer films, C 60 and other fullerenes, conductive organic layers such as oligothiophene, metal phthalocyanines, metal-free phthalocyanines, metal porphyrins, metal-free porphyrins, etc. Examples include organic compound layers, but the present invention is not limited thereto.
　発光ユニット内の好ましい構成としては、例えば前記の代表的な素子構成で挙げた（１）～（７）の構成から、陽極と陰極を除いたもの等が挙げられるが、本発明はこれらに限定されない。 Preferred examples of the configuration within the light emitting unit include, for example, those obtained by removing the anode and the cathode from the configurations (1) to (7) mentioned in the above representative device configurations, but the present invention is not limited to these. Not.
　タンデム型有機ＥＬ素子の具体例としては、例えば、米国特許第６３３７４９２号明細書、米国特許第７４２０２０３号明細書、米国特許第７４７３９２３号明細書、米国特許第６８７２４７２号明細書、米国特許第６１０７７３４号明細書、米国特許第６３３７４９２号明細書、国際公開第２００５／００９０８７号、特開２００６－２２８７１２号公報、特開２００６－２４７９１号公報、特開２００６－４９３９３号公報、特開２００６－４９３９４号公報、特開２００６－４９３９６号公報、特開２０１１－９６６７９号公報、特開２００５－３４０１８７号公報、特許第４７１１４２４号、特許第３４９６６８１号、特許第３８８４５６４号、特許第４２１３１６９号、特開２０１０－１９２７１９号公報、特開２００９－０７６９２９号公報、特開２００８－０７８４１４号公報、特開２００７－０５９８４８号公報、特開２００３－２７２８６０号公報、特開２００３－０４５６７６号公報、国際公開第２００５／０９４１３０号等に記載の素子構成や構成材料等が挙げられるが、本発明はこれらに限定されない。 Specific examples of the tandem organic EL element include, for example, US Pat. No. 6,337,492, US Pat. No. 7,420,203, US Pat. No. 7,473,923, US Pat. No. 6,872,472, US Pat. No. 6,107,734. Specification, U.S. Pat. No. 6,337,492, International Publication No. 2005/009087, JP-A-2006-228712, JP-A-2006-24791, JP-A-2006-49393, JP-A-2006-49394 JP-A-2006-49396, JP-A-2011-96679, JP-A-2005-340187, JP-A-4711424, JP-A-34968681, JP-A-3884564, JP-A-42131169, JP-A-2010-192719. No., JP2009-07 929, JP 2008-078414, JP 2007-059848, JP 2003-272860, JP 2003-045676, WO 2005/094130, etc. Examples include constituent materials, but the present invention is not limited to these.
　≪電子輸送層≫
　本発明において電子輸送層とは、電子を輸送する機能を有する材料からなり、陰極より注入された電子を発光層に伝達する機能を有していればよい。 ≪Electron transport layer≫
In the present invention, the electron transport layer is made of a material having a function of transporting electrons, and may have a function of transmitting electrons injected from the cathode to the light emitting layer.
　本発明に係る電子輸送層の総厚については特に制限はないが、通常は２ｎｍ～５μｍの範囲であり、より好ましくは２～５００ｎｍであり、更に好ましくは５～２００ｎｍである。 The total thickness of the electron transport layer according to the present invention is not particularly limited, but is usually in the range of 2 nm to 5 μm, more preferably 2 to 500 nm, and further preferably 5 to 200 nm.
　また、有機ＥＬ素子においては発光層で生じた光を電極から取り出す際、発光層から直接取り出される光と、光を取り出す電極と対極に位置する電極によって反射されてから取り出される光とが干渉を起こすことが知られている。光が陰極で反射される場合は、電子輸送層の総厚を５ｎｍ～１μｍの間で適宜調整することにより、この干渉効果を効率的に利用することが可能である。 Further, in the organic EL element, when the light generated in the light emitting layer is extracted from the electrode, the light extracted directly from the light emitting layer interferes with the light extracted after being reflected by the electrode from which the light is extracted and the electrode located at the counter electrode. It is known to wake up. When light is reflected by the cathode, this interference effect can be efficiently utilized by appropriately adjusting the total thickness of the electron transport layer between 5 nm and 1 μm.
　一方で、電子輸送層の厚さを厚くすると電圧が上昇しやすくなるため、特に層厚が厚い場合においては、電子輸送層の電子移動度は１０－５ｃｍ２／Ｖｓ以上であることが好ましい。 On the other hand, when the thickness of the electron transport layer is increased, the voltage is likely to increase. Therefore, particularly when the layer thickness is thick, the electron mobility of the electron transport layer is preferably 10 −5 cm 2 / Vs or more. .
　電子輸送層に用いられる材料（以下、電子輸送材料という）としては、電子の注入性又は輸送性、正孔の障壁性のいずれかを有していればよく、従来公知の化合物の中から任意のものを選択して用いることができる。 The material used for the electron transport layer (hereinafter referred to as an electron transport material) may be any of electron injecting or transporting properties and hole blocking properties, and can be selected from conventionally known compounds. Can be selected and used.
　例えば、含窒素芳香族複素環誘導体（カルバゾール誘導体、アザカルバゾール誘導体（カルバゾール環を構成する炭素原子の一つ以上が窒素原子に置換されたもの）、ピリジン誘導体、ピリミジン誘導体、ピラジン誘導体、ピリダジン誘導体、トリアジン誘導体、キノリン誘導体、キノキサリン誘導体、フェナントロリン誘導体、アザトリフェニレン誘導体、オキサゾール誘導体、チアゾール誘導体、オキサジアゾール誘導体、チアジアゾール誘導体、トリアゾール誘導体、ベンズイミダゾール誘導体、ベンズオキサゾール誘導体、ベンズチアゾール誘導体等）、ジベンゾフラン誘導体、ジベンゾチオフェン誘導体、シロール誘導体、芳香族炭化水素環誘導体（ナフタレン誘導体、アントラセン誘導体、トリフェニレン等）等が挙げられる。 For example, nitrogen-containing aromatic heterocyclic derivatives (carbazole derivatives, azacarbazole derivatives (one or more carbon atoms constituting the carbazole ring are substituted with nitrogen atoms), pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, pyridazine derivatives, Triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, azatriphenylene derivatives, oxazole derivatives, thiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, benzimidazole derivatives, benzoxazole derivatives, benzthiazole derivatives, etc.), dibenzofuran derivatives, And dibenzothiophene derivatives, silole derivatives, aromatic hydrocarbon ring derivatives (naphthalene derivatives, anthracene derivatives, triphenylene, etc.)
　また、配位子にキノリノール骨格やジベンゾキノリノール骨格を有する金属錯体、例えば、トリス（８－キノリノール）アルミニウム（Ａｌｑ）、トリス（５，７－ジクロロ－８－キノリノール）アルミニウム、トリス（５，７－ジブロモ－８－キノリノール）アルミニウム、トリス（２－メチル－８－キノリノール）アルミニウム、トリス（５－メチル－８－キノリノール）アルミニウム、ビス（８－キノリノール）亜鉛（Ｚｎｑ）等、及びこれらの金属錯体の中心金属がＩｎ、Ｍｇ、Ｃｕ、Ｃａ、Ｓｎ、Ｇａ又はＰｂに置き替わった金属錯体も、電子輸送材料として用いることができる。 In addition, a metal complex having a quinolinol skeleton or a dibenzoquinolinol skeleton as a ligand, such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7- Dibromo-8-quinolinol) aluminum, tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and their metal complexes A metal complex in which the central metal is replaced with In, Mg, Cu, Ca, Sn, Ga, or Pb can also be used as the electron transport material.
　その他、メタルフリー若しくはメタルフタロシアニン、又はそれらの末端がアルキル基やスルホン酸基等で置換されているものも、電子輸送材料として好ましく用いることができる。また、発光層に使用される公知のジスチリルピラジン誘導体も、電子輸送材料として用いることができるし、正孔注入層、正孔輸送層と同様にｎ型－Ｓｉ、ｎ型－ＳｉＣ等の無機半導体も電子輸送材料として用いることができる。 In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material. In addition, known distyrylpyrazine derivatives used for the light emitting layer can also be used as an electron transporting material, and inorganic materials such as n-type-Si and n-type-SiC can be used as well as the hole injection layer and the hole transport layer. A semiconductor can also be used as an electron transport material.
　また、これらの材料を高分子鎖に導入した、又はこれらの材料を高分子の主鎖とした高分子材料を用いることもできる。 Also, a polymer material in which these materials are introduced into a polymer chain or these materials as a polymer main chain can be used.
　本発明に係る電子輸送層においては、電子輸送層にドープ材をゲスト材料としてドープして、ｎ性の高い（電子リッチ）電子輸送層を形成してもよい。ドープ材としては、金属錯体やハロゲン化金属など金属化合物等のｎ型ドーパントが挙げられる。このような構成の電子輸送層の具体例としては、例えば、特開平４－２９７０７６号公報、同１０－２７０１７２号公報、特開２０００－１９６１４０号公報、同２００１－１０２１７５号公報、Ｊ．Ａｐｐｌ．Ｐｈｙｓ．，９５，５７７３（２００４）等の文献に記載されたものが挙げられる。 In the electron transport layer according to the present invention, the electron transport layer may be doped with a doping material as a guest material to form an electron transport layer having a high n property (electron rich). Examples of the doping material include n-type dopants such as metal complexes and metal compounds such as metal halides. Specific examples of the electron transport layer having such a structure include, for example, JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J. Pat. Appl. Phys. , 95, 5773 (2004) and the like.
　本発明の有機ＥＬ素子に用いられる、公知の好ましい電子輸送材料の具体例としては、以下の文献に記載の化合物等が挙げられるが、これらに限定されない。 Specific examples of known preferable electron transport materials used in the organic EL device of the present invention include, but are not limited to, compounds described in the following documents.
　米国特許第６５２８１８７号明細書、米国特許第７２３０１０７号明細書、米国特許公開第２００５／００２５９９３号明細書、米国特許公開第２００４／００３６０７７号明細書、米国特許公開第２００９／０１１５３１６号明細書、米国特許公開第２００９／０１０１８７０号明細書、米国特許公開第２００９／０１７９５５４号明細書、国際公開第２００３／０６０９５６号、国際公開第２００８／１３２０８５号、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．７５，４（１９９９）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．７９，４４９（２００１）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．８１，１６２（２００２）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．８１，１６２（２００２）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．７９，１５６（２００１）、米国特許第７９６４２９３号明細書、米国特許公開第２００９／０３０２０２号明細書、国際公開第２００４／０８０９７５号、国際公開第２００４／０６３１５９号、国際公開第２００５／０８５３８７号、国際公開第２００６／０６７９３１号、国際公開第２００７／０８６５５２号、国際公開第２００８／１１４６９０号、国際公開第２００９／０６９４４２号、国際公開第２００９／０６６７７９号、国際公開第２００９／０５４２５３号、国際公開第２０１１／０８６９３５号、国際公開第２０１０／１５０５９３号、国際公開第２０１０／０４７７０７号、欧州特許第２３１１８２６号明細書、特開２０１０－２５１６７５号公報、特開２００９－２０９１３３号公報、特開２００９－１２４１１４号公報、特開２００８－２７７８１０号公報、特開２００６－１５６４４５号公報、特開２００５－３４０１２２号公報、特開２００３－４５６６２号公報、特開２００３－３１３６７号公報、特開２００３－２８２２７０号公報、国際公開第２０１２／１１５０３４号等である。 US Pat. No. 6,528,187, US Pat. No. 7,230,107, US Patent Publication No. 2005/0025993, US Patent Publication No. 2004/0036077, US Patent Publication No. 2009/0115316, US Patent Publication No. 2009/0101870, United States Patent Publication No. 2009/0179554, International Publication No. 2003/060956, International Publication No. 2008/132805, Appl. Phys. Lett. 75, 4 (1999), Appl. Phys. Lett. 79, 449 (2001), Appl. Phys. Lett. 81, 162 (2002), Appl. Phys. Lett. 81, 162 (2002), Appl. Phys. Lett. 79,156 (2001), U.S. Patent No. 7964293, U.S. Patent Publication No. 2009/030202, International Publication No. 2004/080975, International Publication No. 2004/063159, International Publication No. 2005/085387, International Publication No. 2006/067931, International Publication No. 2007/085652, International Publication No. 2008/114690, International Publication No. 2009/066942, International Publication No. 2009/066779, International Publication No. 2009/054253, International Publication No. 2011/086935, International Publication No. 2010/150593, International Publication No. 2010/047707, European Patent No. 2311826, Japanese Unexamined Patent Publication No. 2010-251675, Japanese Unexamined Patent Publication No. 2009-209133, Japanese Unexamined Patent Publication No. 2009-. 124114 JP, 2008-277810, JP 2006-156445, JP 2005-340122, JP 2003-45662, JP 2003-31367, JP 2003-282270, International Publication No. 2012/115034.
　本発明における、より好ましい電子輸送材料としては、ピリジン誘導体、ピリミジン誘導体、ピラジン誘導体、トリアジン誘導体、ジベンゾフラン誘導体、ジベンゾチオフェン誘導体、カルバゾール誘導体、アザカルバゾール誘導体、ベンズイミダゾール誘導体が挙げられる。 More preferable electron transport materials in the present invention include pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, triazine derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, carbazole derivatives, azacarbazole derivatives, and benzimidazole derivatives.
　電子輸送材料は単独で用いてもよく、また複数種を併用して用いてもよい。 The electron transport material may be used alone or in combination of two or more.
　≪正孔阻止層≫
　正孔阻止層とは広い意味では電子輸送層の機能を有する層であり、好ましくは電子を輸送する機能を有しつつ正孔を輸送する能力が小さい材料からなり、電子を輸送しつつ正孔を阻止することで電子と正孔の再結合確率を向上させることができる。 ≪Hole blocking layer≫
The hole blocking layer is a layer having a function of an electron transport layer in a broad sense, and is preferably made of a material having a function of transporting electrons and a small ability to transport holes, and transporting electrons while transporting holes. The probability of recombination of electrons and holes can be improved by blocking.
　また、前述する電子輸送層の構成を必要に応じて、本発明に係る正孔阻止層として用いることができる。 Moreover, the structure of the electron transport layer described above can be used as a hole blocking layer according to the present invention, if necessary.
　本発明の有機ＥＬ素子に設ける正孔阻止層は、発光層の陰極側に隣接して設けられることが好ましい。 The hole blocking layer provided in the organic EL device of the present invention is preferably provided adjacent to the cathode side of the light emitting layer.
　本発明に係る正孔阻止層の厚さとしては、好ましくは３～１００ｎｍの範囲であり、更に好ましくは５～３０ｎｍの範囲である。 The thickness of the hole blocking layer according to the present invention is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.
　正孔阻止層に用いられる材料としては、前述の電子輸送層に用いられる材料が好ましく用いられ、また、前述の本発明に係るホスト化合物及びその他のホスト化合物として用いられる材料も正孔阻止層に好ましく用いられる。 As the material used for the hole blocking layer, the material used for the above-described electron transport layer is preferably used, and the above-described host compound according to the present invention and other materials used as the host compound are also used for the hole blocking layer. Preferably used.
　≪電子注入層≫
　本発明に係る電子注入層（「陰極バッファー層」ともいう）とは、駆動電圧低下や発光輝度向上のために陰極と発光層との間に設けられる層のことで、「有機ＥＬ素子とその工業化最前線（１９９８年１１月３０日エヌ・ティー・エス社発行）」の第２編第２章「電極材料」（１２３～１６６頁）に詳細に記載されている。 ≪Electron injection layer≫
The electron injection layer (also referred to as “cathode buffer layer”) according to the present invention is a layer provided between the cathode and the light emitting layer in order to lower the driving voltage and improve the light emission luminance. It is described in detail in Chapter 2 “Electrode Materials” (pages 123 to 166) of the second edition of “The Forefront of Industrialization (issued by NTT Corporation on November 30, 1998)”.
　本発明において電子注入層は必要に応じて設け、前記のように陰極と発光層との間、又は陰極と電子輸送層との間に存在させてもよい。 In the present invention, the electron injection layer may be provided as necessary, and may be present between the cathode and the light emitting layer or between the cathode and the electron transport layer as described above.
　電子注入層はごく薄い膜であることが好ましく、素材にもよるがその厚さは０．１～５ｎｍの範囲が好ましい。また構成材料が断続的に存在する不均一な膜であってもよい。 The electron injection layer is preferably a very thin film, and the thickness is preferably in the range of 0.1 to 5 nm, depending on the material. Moreover, the nonuniform film | membrane in which a constituent material exists intermittently may be sufficient.
　電子注入層は、特開平６－３２５８７１号公報、同９－１７５７４号公報、同１０－７４５８６号公報等にもその詳細が記載されており、電子注入層に好ましく用いられる材料の具体例としては、ストロンチウムやアルミニウム等に代表される金属、フッ化リチウム、フッ化ナトリウム、フッ化カリウム等に代表されるアルカリ金属化合物、フッ化マグネシウム、フッ化カルシウム等に代表されるアルカリ土類金属化合物、酸化アルミニウムに代表される金属酸化物、リチウム８－ヒドロキシキノレート（Ｌｉｑ）等に代表される金属錯体等が挙げられる。また、前述の電子輸送材料を用いることも可能である。 Details of the electron injection layer are also described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specific examples of materials preferably used for the electron injection layer are as follows. , Metals typified by strontium and aluminum, alkali metal compounds typified by lithium fluoride, sodium fluoride, potassium fluoride, etc., alkaline earth metal compounds typified by magnesium fluoride, calcium fluoride, etc., oxidation Examples thereof include metal oxides typified by aluminum, metal complexes typified by lithium 8-hydroxyquinolate (Liq), and the like. Further, the above-described electron transport material can also be used.
　また、前記の電子注入層に用いられる材料は単独で用いてもよく、複数種を併用して用いてもよい。 Also, the materials used for the electron injection layer may be used alone or in combination of two or more.
　≪正孔輸送層≫
　本発明において正孔輸送層とは、正孔を輸送する機能を有する材料からなり、陽極より注入された正孔を発光層に伝達する機能を有していればよい。 ≪Hole transport layer≫
In the present invention, the hole transport layer is made of a material having a function of transporting holes and may have a function of transmitting holes injected from the anode to the light emitting layer.
　本発明に係る正孔輸送層の総厚については特に制限はないが、通常は５ｎｍ～５μｍの範囲であり、より好ましくは２～５００ｎｍであり、更に好ましくは５ｎｍ～２００ｎｍである。 The total thickness of the hole transport layer according to the present invention is not particularly limited, but is usually in the range of 5 nm to 5 μm, more preferably 2 to 500 nm, and further preferably 5 nm to 200 nm.
　正孔輸送層に用いられる材料（以下、正孔輸送材料という）としては、正孔の注入性又は輸送性、電子の障壁性のいずれかを有していればよく、従来公知の化合物の中から任意のものを選択して用いることができる。 As a material used for the hole transport layer (hereinafter referred to as a hole transport material), any material that has either a hole injection property or a transport property or an electron barrier property may be used. Any one can be selected and used.
　例えば、ポルフィリン誘導体、フタロシアニン誘導体、オキサゾール誘導体、オキサジアゾール誘導体、トリアゾール誘導体、イミダゾール誘導体、ピラゾリン誘導体、ピラゾロン誘導体、フェニレンジアミン誘導体、ヒドラゾン誘導体、スチルベン誘導体、ポリアリールアルカン誘導体、トリアリールアミン誘導体、カルバゾール誘導体、インドロカルバゾール誘導体、イソインドール誘導体、アントラセンやナフタレン等のアセン系誘導体、フルオレン誘導体、フルオレノン誘導体、及びポリビニルカルバゾール、芳香族アミンを主鎖又は側鎖に導入した高分子材料又はオリゴマー、ポリシラン、導電性ポリマー又はオリゴマー（例えばＰＥＤＯＴ：ＰＳＳ、アニリン系共重合体、ポリアニリン、ポリチオフェン等）等が挙げられる。 For example, porphyrin derivatives, phthalocyanine derivatives, oxazole derivatives, oxadiazole derivatives, triazole derivatives, imidazole derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, hydrazone derivatives, stilbene derivatives, polyarylalkane derivatives, triarylamine derivatives, carbazole derivatives , Indolocarbazole derivatives, isoindole derivatives, acene derivatives such as anthracene and naphthalene, fluorene derivatives, fluorenone derivatives, and polyvinyl carbazole, polymer materials or oligomers with aromatic amines introduced into the main chain or side chain, polysilane, conductive And polymer (for example, PEDOT: PSS, aniline copolymer, polyaniline, polythiophene, etc.).
　トリアリールアミン誘導体としては、α－ＮＰＤ（４，４′－ビス〔Ｎ－（１－ナフチル）－Ｎ－フェニルアミノ〕ビフェニル）に代表されるベンジジン型や、ＭＴＤＡＴＡに代表されるスターバースト型、トリアリールアミン連結コア部にフルオレンやアントラセンを有する化合物等が挙げられる。 Examples of triarylamine derivatives include benzidine type typified by α-NPD (4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl), starburst type typified by MTDATA, Examples include compounds having fluorene or anthracene in the triarylamine-linked core.
　また、特表２００３－５１９４３２号公報や特開２００６－１３５１４５号公報等に記載されているようなヘキサアザトリフェニレン誘導体も同様に正孔輸送材料として用いることができる。 In addition, hexaazatriphenylene derivatives such as those described in JP-T-2003-519432 and JP-A-2006-135145 can also be used as a hole transport material.
　更に不純物をドープしたｐ性の高い正孔輸送層を用いることもできる。その例としては、特開平４－２９７０７６号公報、特開２０００－１９６１４０号公報、同２００１－１０２１７５号公報の各公報、Ｊ．Ａｐｐｌ．Ｐｈｙｓ．，９５，５７７３（２００４）等に記載されたものが挙げられる。 Furthermore, a hole transport layer having a high p property doped with impurities can also be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J. Pat. Appl. Phys. 95, 5773 (2004), and the like.
　また、特開平１１－２５１０６７号公報、Ｊ．Ｈｕａｎｇ　ｅｔ．ａｌ．著文献（Ａｐｐｌｉｅｄ　Ｐｈｙｓｉｃｓ　Ｌｅｔｔｅｒｓ　８０（２００２），ｐ．１３９）に記載されているような、いわゆるｐ型正孔輸送材料やｐ型－Ｓｉ、ｐ型－ＳｉＣ等の無機化合物を用いることもできる。更にＩｒ（ｐｐｙ）3に代表されるような中心金属にＩｒやＰ
ｔを有するオルトメタル化有機金属錯体も好ましく用いられる。 JP-A-11-251067, J. Org. Huang et. al. It is also possible to use so-called p-type hole transport materials and inorganic compounds such as p-type-Si and p-type-SiC, as described in the literature (Applied Physics Letters 80 (2002), p. 139). Furthermore, Ir and P are used as the central metal represented by Ir (ppy) 3.
Orthometalated organometallic complexes having t are also preferably used.
　正孔輸送材料としては、前記のものを使用することができるが、トリアリールアミン誘導体、カルバゾール誘導体、インドロカルバゾール誘導体、アザトリフェニレン誘導体、有機金属錯体、芳香族アミンを主鎖又は側鎖に導入した高分子材料又はオリゴマー等が好ましく用いられる。 The above-mentioned materials can be used as the hole transport material, but a triarylamine derivative, a carbazole derivative, an indolocarbazole derivative, an azatriphenylene derivative, an organometallic complex, or an aromatic amine is introduced into the main chain or side chain. The polymer materials or oligomers used are preferably used.
　本発明の有機ＥＬ素子に用いられる、公知の好ましい正孔輸送材料の具体例としては、前記で挙げた文献の他、以下の文献に記載の化合物等が挙げられるが、これらに限定されない。 Specific examples of known preferable hole transport materials used in the organic EL device of the present invention include, but are not limited to, the compounds described in the following documents in addition to the documents listed above.
　例えば、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．６９，２１６０（１９９６）、Ｊ．Ｌｕｍｉｎ．７２－７４，９８５（１９９７）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．７８，６７３（２００１）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．９０，１８３５０３（２００７）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．９０，１８３５０３（２００７）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．５１，９１３（１９８７）、Ｓｙｎｔｈ．Ｍｅｔ．８７，１７１（１９９７）、Ｓｙｎｔｈ．Ｍｅｔ．９１，２０９（１９９７）、Ｓｙｎｔｈ．Ｍｅｔ．１１１，４２１（２０００）、ＳＩＤ　Ｓｙｍｐｏｓｉｕｍ　Ｄｉｇｅｓｔ，３７，９２３（２００６）、Ｊ．Ｍａｔｅｒ．Ｃｈｅｍ．３，３１９（１９９３）、Ａｄｖ．Ｍａｔｅｒ．６，６７７（１９９４）、Ｃｈｅｍ．Ｍａｔｅｒ．１５，３１４８（２００３）、米国特許公開第２００３／０１６２０５３号明細書、米国特許公開第２００２／０１５８２４２号明細書、米国特許公開第２００６／０２４０２７９号明細書、米国特許公開第２００８／０２２０２６５号明細書、米国特許第５０６１５６９号明細書、国際公開第２００７／００２６８３号、国際公開第２００９／０１８００９号、欧州特許第６５０９５５号明細書、米国特許公開第２００８／０１２４５７２号、米国特許公開第２００７／０２７８９３８号明細書、米国特許公開第２００８／０１０６１９０号明細書、米国特許公開第２００８／００１８２２１号明細書、国際公開第２０１２／１１５０３４号、特表２００３－５１９４３２号公報、特開２００６－１３５１４５号公報、米国特許出願番号１３／５８５９８１号等である。 For example, Appl. Phys. Lett. 69, 2160 (1996), J. MoI. Lumin. 72-74,985 (1997), Appl. Phys. Lett. 78, 673 (2001), Appl. Phys. Lett. 90, 183503 (2007), Appl. Phys. Lett. 90, 183503 (2007), Appl. Phys. Lett. 51, 913 (1987), Synth. Met. 87, 171 (1997), Synth. Met. 91, 209 (1997), Synth. Met. 111, 421 (2000), SID Symposium Digest, 37, 923 (2006), J. Am. Mater. Chem. 3,319 (1993), Adv. Mater. 6, 677 (1994), Chem. Mater. 15, 3148 (2003), US Patent Publication No. 2003/0162053, US Patent Publication No. 2002/0158242, US Patent Publication No. 2006/0240279, US Patent Publication No. 2008/0220265. US Patent No. 5061569, International Publication No. 2007/002683, International Publication No. 2009/018009, European Patent No. 650955, US Patent Publication No. 2008/0124572, US Patent Publication No. 2007/0278938. Specification, US Patent Publication No. 2008/0106190, US Patent Publication No. 2008/0018221, International Publication No. 2012/115034, Japanese Patent Publication No. 2003-519432, Japanese Patent Laid-Open No. 2006-135145, US Patent application number 1 / A 585 981 Patent and the like.
　正孔輸送材料は単独で用いてもよく、また複数種を併用して用いてもよい。 The hole transport material may be used alone or in combination of two or more.
　≪電子阻止層≫
　電子阻止層とは広い意味では正孔輸送層の機能を有する層であり、好ましくは正孔を輸送する機能を有しつつ電子を輸送する能力が小さい材料からなり、正孔を輸送しつつ電子を阻止することで電子と正孔の再結合確率を向上させることができる。 ≪Electron blocking layer≫
The electron blocking layer is a layer having a function of a hole transport layer in a broad sense, and is preferably made of a material having a function of transporting holes and a small ability to transport electrons, and transporting electrons while transporting holes. The probability of recombination of electrons and holes can be improved by blocking.
　また、前述する正孔輸送層の構成を必要に応じて、本発明に係る電子阻止層として用いることができる。 Moreover, the above-described configuration of the hole transport layer can be used as an electron blocking layer according to the present invention, if necessary.
　本発明の有機ＥＬ素子に設ける電子阻止層は、発光層の陽極側に隣接して設けられることが好ましい。 The electron blocking layer provided in the organic EL device of the present invention is preferably provided adjacent to the anode side of the light emitting layer.
　本発明に係る電子阻止層の厚さとしては、好ましくは３～１００ｎｍの範囲であり、更に好ましくは５～３０ｎｍの範囲である。 The thickness of the electron blocking layer according to the present invention is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.
　電子阻止層に用いられる材料としては、前述の正孔輸送層に用いられる材料が好ましく用いられ、また、前述の本発明に係るホスト化合物及びその他のホスト化合物として用いられる材料も電子阻止層に好ましく用いられる。 As the material used for the electron blocking layer, the material used for the above-described hole transport layer is preferably used, and the above-described host compound according to the present invention and other materials used as the host compound are also preferable for the electron blocking layer. Used.
　≪正孔注入層≫
　本発明に係る正孔注入層（「陽極バッファー層」ともいう）とは、駆動電圧低下や発光輝度向上のために陽極と発光層との間に設けられる層のことで、「有機ＥＬ素子とその工業化最前線（１９９８年１１月３０日エヌ・ティー・エス社発行）」の第２編第２章「電極材料」（１２３～１６６頁）に詳細に記載されている。 ≪Hole injection layer≫
The hole injection layer (also referred to as “anode buffer layer”) according to the present invention is a layer provided between the anode and the light emitting layer for the purpose of lowering the driving voltage and improving the light emission luminance. It is described in detail in Volume 2, Chapter 2, “Electrode Materials” (pages 123 to 166) of “The Forefront of Industrialization (issued by NTT Corporation on November 30, 1998)”.
　本発明において正孔注入層は必要に応じて設け、前記のように陽極と発光層又は陽極と正孔輸送層との間に存在させてもよい。 In the present invention, the hole injection layer may be provided as necessary, and may be present between the anode and the light emitting layer or between the anode and the hole transport layer as described above.
　正孔注入層は、特開平９－４５４７９号公報、同９－２６００６２号公報、同８－２８８０６９号公報等にもその詳細が記載されており、正孔注入層に用いられる材料としては、例えば前述の正孔輸送層に用いられる材料等が挙げられる。 The details of the hole injection layer are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069, etc. Examples of materials used for the hole injection layer include: Examples thereof include materials used for the above-described hole transport layer.
　中でも銅フタロシアニンに代表されるフタロシアニン誘導体、特表２００３－５１９４３２号公報や特開２００６－１３５１４５号公報等に記載されているようなヘキサアザトリフェニレン誘導体、酸化バナジウムに代表される金属酸化物、アモルファスカーボン、ポリアニリン（エメラルディン）やポリチオフェン等の導電性高分子、トリス（２－フェニルピリジン）イリジウム錯体等に代表されるオルトメタル化錯体、トリアリールアミン誘導体等が好ましい。 Among them, phthalocyanine derivatives typified by copper phthalocyanine, hexaazatriphenylene derivatives, metal oxides typified by vanadium oxide, amorphous carbon as described in JP-T-2003-519432, JP-A-2006-135145, etc. Preferred are conductive polymers such as polyaniline (emeraldine) and polythiophene, orthometalated complexes represented by tris (2-phenylpyridine) iridium complex, and triarylamine derivatives.
　前述の正孔注入層に用いられる材料は単独で用いてもよく、また複数種を併用して用いてもよい。 The materials used for the hole injection layer described above may be used alone or in combination of two or more.
　≪他の添加物≫
　前述した本発明における有機層は、更に他の添加物が含まれていてもよい。 ≪Other additives≫
The organic layer in the present invention described above may further contain other additives.
　他の添加物としては、例えば臭素、ヨウ素及び塩素等のハロゲン元素やハロゲン化化合物、Ｐｄ、Ｃａ、Ｎａ等のアルカリ金属やアルカリ土類金属、遷移金属の化合物や錯体、塩等が挙げられる。 Examples of other additives include halogen elements and halogenated compounds such as bromine, iodine and chlorine, alkali metals and alkaline earth metals such as Pd, Ca and Na, transition metal compounds, complexes and salts.
　他の添加物の含有量は、任意に決定することができるが、含有される層の全質量％に対して１０００ｐｐｍ以下であることが好ましく、より好ましくは５００ｐｐｍ以下であり、更に好ましくは５０ｐｐｍ以下である。 The content of other additives can be arbitrarily determined, but is preferably 1000 ppm or less, more preferably 500 ppm or less, and still more preferably 50 ppm or less, based on the total mass% of the contained layer. It is.
　ただし、電子や正孔の輸送性を向上させる目的や、励起子のエネルギー移動を有利にするための目的等によってはこの範囲内ではない。 However, it is not within this range depending on the purpose of improving the transportability of electrons and holes or the purpose of making the energy transfer of excitons advantageous.
　≪有機層の形成方法≫
　本発明に係る有機エレクトロルミネッセンス素子を製造する方法は、公知の方法を好適に採用することができるが、特に、発光層が、ウェットプロセス又はドライプロセスを用いて製膜される態様であることが好ましい。
　以下に、有機層（正孔注入層、正孔輸送層、電子阻止層、発光層、正孔阻止層、電子輸送層、電子注入層等）の形成方法について説明する。 ≪Method of forming organic layer≫
As a method for producing the organic electroluminescence device according to the present invention, a known method can be suitably employed. In particular, the light-emitting layer may be formed using a wet process or a dry process. preferable.
A method for forming an organic layer (hole injection layer, hole transport layer, electron blocking layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) will be described below.
　本発明の有機ＥＬ素子を製造する方法において、有機層の形成方法は、特に制限はなく、従来公知の例えば、ドライプロセスなどの真空蒸着法、ウェットプロセス等による形成方法を用いることができ、また、各層に使用される化合物等の材料に合わせて、ウェットプロセスやドライプロセスを使い分けて積層し、有機層を形成する方法であってもよい。ここで、有機層が、ウェットプロセスで形成された層であることが好ましい。すなわち、ウェットプロセスで有機ＥＬ素子を作製することが好ましい。有機ＥＬ素子をウェットプロセスで作製することで、均質な膜（塗膜）が得られやすく、且つピンホールが生成しにくい等の効果を奏することができる。なお、ここでの膜（塗膜）とは、ウェットプロセスによる塗布後に乾燥させた状態のものである。 In the method for producing the organic EL device of the present invention, the method for forming the organic layer is not particularly limited, and conventionally known methods such as a vacuum deposition method such as a dry process, a wet process, and the like can be used. Depending on the material used for each layer, such as a compound, the organic layer may be formed by using a wet process or a dry process. Here, the organic layer is preferably a layer formed by a wet process. That is, it is preferable to produce an organic EL element by a wet process. By producing the organic EL element by a wet process, a uniform film (coating film) can be easily obtained, and effects such as the difficulty of generating pinholes can be achieved. In addition, a film | membrane (coating film) here is a thing of the state dried after application | coating by a wet process.
　ウェットプロセスとしては、スピンコート法、キャスト法、インクジェット法、印刷法、ダイコート法、ブレードコート法、ロールコート法、スプレーコート法、カーテンコート法、ＬＢ法（ラングミュア－ブロジェット法）等があるが、均質な薄膜が得られやすく、且つ高生産性の点から、ダイコート法、ロールコート法、インクジェット法、スプレーコート法等のロール・ｔｏ・ロール方式適性の高い方法が好ましい。 Examples of the wet process include spin coating, casting, ink jet, printing, die coating, blade coating, roll coating, spray coating, curtain coating, and LB (Langmuir-Blodgett). From the viewpoint of obtaining a homogeneous thin film easily and high productivity, a method with high roll-to-roll method suitability such as a die coating method, a roll coating method, an ink jet method, and a spray coating method is preferable.
　なお、ドライプロセスとしては、蒸着法（抵抗加熱、ＥＢ法など）、スパッタリング法、ＣＶＤ法などが挙げられる。 Note that examples of the dry process include vapor deposition methods (resistance heating, EB method, etc.), sputtering methods, CVD methods, and the like.
　本発明に係る有機ＥＬ素子の材料を溶解又は分散する液媒体としては、例えば、メチルエチルケトン、シクロヘキサノン等のケトン類、酢酸エチル等の脂肪酸エステル類、ジクロロベンゼン等のハロゲン化炭化水素類、トルエン、キシレン、メシチレン、シクロヘキシルベンゼン等の芳香族炭化水素類、シクロヘキサン、デカリン、ドデカン等の脂肪族炭化水素類、ＤＭＦ、ＤＭＳＯ等の有機溶媒を用いることができる。 Examples of the liquid medium for dissolving or dispersing the material of the organic EL device according to the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene and xylene. Aromatic hydrocarbons such as mesitylene and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin and dodecane, and organic solvents such as DMF and DMSO can be used.
　また、分散方法としては、超音波、高剪断力分散やメディア分散等の分散方法により分散することができる。 Further, as a dispersion method, it can be dispersed by a dispersion method such as ultrasonic wave, high shearing force dispersion or media dispersion.
　更に層毎に異なる製膜法を適用してもよい。製膜に蒸着法を採用する場合、その蒸着条件は使用する化合物の種類等により異なるが、一般にボート加熱温度５０～４５０℃、真空度１０－６～１０－２Ｐａ、蒸着速度０．０１～５０ｎｍ／秒、基板温度－５０～３００℃、厚さ０．１ｎｍ～５μｍ、好ましくは５～２００ｎｍの範囲で適宜選ぶことが望ましい。 Further, different film forming methods may be applied for each layer. When a vapor deposition method is employed for film formation, the vapor deposition conditions vary depending on the type of compound used, but generally a boat heating temperature of 50 to 450 ° C., a degree of vacuum of 10 −6 to 10 −2 Pa, and a vapor deposition rate of 0.01 to It is desirable to select appropriately within a range of 50 nm / second, a substrate temperature of −50 to 300 ° C., and a thickness of 0.1 nm to 5 μm, preferably 5 to 200 nm.
　本発明に係る有機層の形成は、一回の真空引きで一貫して正孔注入層から陰極まで作製するのが好ましいが、途中で取り出して異なる製膜法を施しても構わない。その際は作業を乾燥不活性ガス雰囲気下で行うことが好ましい。 For the formation of the organic layer according to the present invention, it is preferable to consistently produce from the hole injection layer to the cathode by a single evacuation, but it may be taken out halfway and subjected to different film forming methods. In that case, it is preferable to perform the work in a dry inert gas atmosphere.
　≪陽極≫
　有機ＥＬ素子における陽極としては、仕事関数の大きい（４ｅＶ以上、好ましくは４．５Ｖ以上）金属、合金、電気伝導性化合物及びこれらの混合物を電極物質とするものが好ましく用いられる。このような電極物質の具体例としては、Ａｕ等の金属、ＣｕＩ、インジウムチンオキシド（ＩＴＯ）、ＳｎＯ2、ＺｎＯ等の導電性透明材料が挙げられる。ま
た、ＩＤＩＸＯ（Ｉｎ2Ｏ3－ＺｎＯ）等非晶質で透明導電膜を作製可能な材料を用いてもよい。 ≪Anode≫
As the anode in the organic EL element, those having a work function (4 eV or more, preferably 4.5 V or more) of a metal, an alloy, an electrically conductive compound and a mixture thereof as an electrode material are preferably used. Specific examples of such electrode substances include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO 2 , and ZnO. Alternatively, an amorphous material such as IDIXO (In 2 O 3 —ZnO) that can form a transparent conductive film may be used.
　陽極はこれらの電極物質を蒸着やスパッタリング等の方法により薄膜を形成させ、フォトリソグラフィー法で所望の形状のパターンを形成してもよく、又はパターン精度をあまり必要としない場合は（１００μｍ以上程度）、前記電極物質の蒸着やスパッタリング時に所望の形状のマスクを介してパターンを形成してもよい。 For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern of a desired shape may be formed by a photolithography method, or when pattern accuracy is not so required (about 100 μm or more) A pattern may be formed through a mask having a desired shape during the vapor deposition or sputtering of the electrode material.
　または、有機導電性化合物のように塗布可能な物質を用いる場合には、印刷方式、コーティング方式等湿式製膜法を用いることもできる。この陽極より発光を取り出す場合には、透過率を１０％より大きくすることが望ましく、また陽極としてのシート抵抗は数百Ω／ｓｑ．以下が好ましい。 Alternatively, when a material that can be applied, such as an organic conductive compound, is used, a wet film forming method such as a printing method or a coating method can also be used. When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is several hundred Ω / sq. The following is preferred.
　陽極の厚さは材料にもよるが、通常１０ｎｍ～１μｍ、好ましくは１０～２００ｎｍの範囲で選ばれる。 The thickness of the anode depends on the material, but is usually selected in the range of 10 nm to 1 μm, preferably 10 to 200 nm.
　≪陰極≫
　陰極としては、仕事関数の小さい（４ｅＶ以下）金属（電子注入性金属と称する）、合金、電気伝導性化合物及びこれらの混合物を電極物質とするものが用いられる。このような電極物質の具体例としては、ナトリウム、ナトリウム－カリウム合金、マグネシウム、リチウム、マグネシウム／銅混合物、マグネシウム／銀混合物、マグネシウム／アルミニウム混合物、マグネシウム／インジウム混合物、アルミニウム／酸化アルミニウム（Ａｌ2Ｏ3）混合物、インジウム、リチウム／アルミニウム混合物、アルミニウム、希土類金属等が挙げられる。これらの中で、電子注入性及び酸化等に対する耐久性の点から、電子注入性金属とこれより仕事関数の値が大きく安定な金属である第二金属との混合物、例えば、マグネシウム／銀混合物、マグネシウム／アルミニウム混合物、マグネシウム／インジウム混合物、アルミニウム／酸化アルミニウム（Ａｌ2Ｏ3）混合物、リチウム／アルミニウム混合物、アルミニウム等が好適である。 ≪Cathode≫
As the cathode, a material having a work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al 2 O 3 ) Mixtures, indium, lithium / aluminum mixtures, aluminum, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Suitable are a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al 2 O 3 ) mixture, a lithium / aluminum mixture, aluminum and the like.
　陰極はこれらの電極物質を蒸着やスパッタリング等の方法により薄膜を形成させることにより、作製することができる。また、陰極としてのシート抵抗は数百Ω／ｓｑ．以下が好ましく、厚さは通常１０ｎｍ～５μｍ、好ましくは５０～２００ｎｍの範囲で選ばれる。 The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as a cathode is several hundred Ω / sq. The following is preferable, and the thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm.
　なお、発光した光を透過させるため、有機ＥＬ素子の陽極又は陰極のいずれか一方が透明又は半透明であれば発光輝度が向上し好都合である。 In addition, in order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the emission luminance is improved, which is convenient.
　また、陰極に前記金属を１～２０ｎｍの厚さで作製した後に、陽極の説明で挙げる導電性透明材料をその上に作製することで、透明又は半透明の陰極を作製することができ、これを応用することで陽極と陰極の両方が透過性を有する素子を作製することができる。 In addition, a transparent or semi-transparent cathode can be produced by producing the conductive transparent material mentioned in the description of the anode on the cathode after producing the metal with a thickness of 1 to 20 nm. By applying the above, it is possible to manufacture a device in which both the anode and the cathode are transparent.
　≪支持基板≫
　本発明の有機ＥＬ素子に用いることのできる支持基板（以下、基体、基板、基材、支持体等ともいう）としては、ガラス、プラスチック等の種類には特に限定はなく、また透明であっても不透明であってもよい。支持基板側から光を取り出す場合には、支持基板は透明であることが好ましい。好ましく用いられる透明な支持基板としては、ガラス、石英、透明樹脂フィルムを挙げることができる。特に好ましい支持基板は、有機ＥＬ素子にフレキシブル性を与えることが可能な樹脂フィルムである。 ≪Support substrate≫
The support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention is not particularly limited in the type of glass, plastic, etc., and is transparent. May be opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film capable of giving flexibility to the organic EL element.
　樹脂フィルムとしては、例えば、ポリエチレンテレフタレート（ＰＥＴ）、ポリエチレンナフタレート（ＰＥＮ）等のポリエステル、ポリエチレン、ポリプロピレン、セロファン、セルロースジアセテート、セルローストリアセテート（ＴＡＣ）、セルロースアセテートブチレート、セルロースアセテートプロピオネート（ＣＡＰ）、セルロースアセテートフタレート、セルロースナイトレート等のセルロースエステル類又はそれらの誘導体、ポリ塩化ビニリデン、ポリビニルアルコール、ポリエチレンビニルアルコール、シンジオタクティックポリスチレン、ポリカーボネート、ノルボルネン樹脂、ポリメチルペンテン、ポリエーテルケトン、ポリイミド、ポリエーテルスルホン（ＰＥＳ）、ポリフェニレンスルフィド、ポリスルホン類、ポリエーテルイミド、ポリエーテルケトンイミド、ポリアミド、フッ素樹脂、ナイロン、ポリメチルメタクリレート、アクリル、又はポリアリレート類、アートン（商品名ＪＳＲ社製）若しくはアペル（商品名三井化学社製）といったシクロオレフィン系樹脂等を挙げられる。 Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate ( CAP), cellulose esters such as cellulose acetate phthalate, cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic, or polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Etc.
　樹脂フィルムの表面には、無機物、有機物の被膜又はその両者のハイブリッド被膜が形成されていてもよく、ＪＩＳ　Ｋ　７１２９－１９９２に準拠した方法で測定された、水蒸気透過度（２５±０．５℃、相対湿度（９０±２）％ＲＨ）が０．０１ｇ／（ｍ２・２４ｈ）以下のバリアー性フィルムであることが好ましく、更には、ＪＩＳ　Ｋ　７１２６－１９８７に準拠した方法で測定された酸素透過度が、１０－３ｍＬ／（ｍ２・２４ｈ・ａｔｍ）以下、水蒸気透過度が、１０－５ｇ／（ｍ２・２４ｈ）以下の高バリアー性フィルムであることが好ましい。 The surface of the resin film may be formed with an inorganic film, an organic film, or a hybrid film of both, and the water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. And a relative humidity (90 ± 2)% RH) of 0.01 g / (m 2 · 24 h) or less is preferable, and oxygen measured by a method in accordance with JIS K 7126-1987 A high barrier film having a permeability of 10 −3 mL / (m 2 · 24 h · atm) or less and a water vapor permeability of 10 −5 g / (m 2 · 24 h) or less is preferable.
　バリアー膜を形成する材料としては、水分や酸素等素子の劣化をもたらすものの浸入を抑制する機能を有する材料であればよく、例えば、酸化ケイ素、二酸化ケイ素、窒化ケイ素等を用いることができる。更に該膜の脆弱性を改良するために、これら無機層と有機材料からなる層の積層構造を持たせることがより好ましい。無機層と有機層の積層順については特に制限はないが、両者を交互に複数回積層させることが好ましい。 The material for forming the barrier film may be any material that has a function of suppressing entry of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used. Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and organic material layers. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.
　バリアー膜の形成方法については特に限定はなく、例えば、真空蒸着法、スパッタリング法、反応性スパッタリング法、分子線エピタキシー法、クラスターイオンビーム法、イオンプレーティング法、プラズマ重合法、大気圧プラズマ重合法、プラズマＣＶＤ法、レーザーＣＶＤ法、熱ＣＶＤ法、コーティング法等を用いることができるが、特開２００４－６８１４３号公報に記載されているような大気圧プラズマ重合法によるものが特に好ましい。 The method for forming the barrier film is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma polymerization A plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.
　不透明な支持基板としては、例えば、アルミニウム、ステンレス等の金属板、フィルムや不透明樹脂基板、セラミック製の基板等が挙げられる。 Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, ceramic substrates, and the like.
　本発明の有機ＥＬ素子の発光の室温における外部取り出し量子効率は、１％以上であることが好ましく、５％以上であるとより好ましい。 The external extraction quantum efficiency at room temperature of light emission of the organic EL device of the present invention is preferably 1% or more, and more preferably 5% or more.
　ここで、外部取り出し量子効率（％）＝有機ＥＬ素子外部に発光した光子数／有機ＥＬ素子に流した電子数×１００である。 Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100.
　また、カラーフィルター等の色相改良フィルター等を併用しても、有機ＥＬ素子からの発光色を、蛍光体を用いて多色へ変換する色変換フィルターを併用してもよい。 Also, a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor may be used in combination.
　≪封止≫
　本発明の有機ＥＬ素子の封止に用いられる封止手段としては、例えば、封止部材と、電極、支持基板とを接着剤で接着する方法を挙げることができる。封止部材としては、有機ＥＬ素子の表示領域を覆うように配置されていればよく、凹板状でも、平板状でもよい。また、透明性、電気絶縁性は特に限定されない。 ≪Sealing≫
Examples of the sealing means used for sealing the organic EL element of the present invention include a method of bonding a sealing member, an electrode, and a support substrate with an adhesive. As a sealing member, it should just be arrange | positioned so that the display area | region of an organic EL element may be covered, and it may be concave plate shape or flat plate shape. Moreover, transparency and electrical insulation are not particularly limited.
　具体的には、ガラス板、ポリマー板・フィルム、金属板・フィルム等が挙げられる。ガラス板としては、特にソーダ石灰ガラス、バリウム・ストロンチウム含有ガラス、鉛ガラス、アルミノケイ酸ガラス、ホウケイ酸ガラス、バリウムホウケイ酸ガラス、石英等を挙げることができる。また、ポリマー板としては、ポリカーボネート、アクリル、ポリエチレンテレフタレート、ポリエーテルサルファイド、ポリサルフォン等を挙げることができる。金属板としては、ステンレス、鉄、銅、アルミニウム、マグネシウム、ニッケル、亜鉛、クロム、チタン、モリブテン、シリコン、ゲルマニウム及びタンタルからなる群から選ばれる１種以上の金属又は合金からなるものが挙げられる。 Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.
　本発明においては、有機ＥＬ素子を薄膜化できるということからポリマーフィルム、金属フィルムを好ましく使用することができる。更には、ポリマーフィルムはＪＩＳ　Ｋ　７１２６－１９８７に準拠した方法で測定された酸素透過度が１×１０－３ｍＬ／（ｍ２・２４ｈ・ａｔｍ）以下、ＪＩＳ　Ｋ　７１２９－１９９２に準拠した方法で測定された、水蒸気透過度（２５±０．５℃、相対湿度（９０±２）％）が、１×１０－３ｇ／（ｍ２・２４ｈ）以下のものであることが好ましい。 In the present invention, a polymer film and a metal film can be preferably used because the organic EL element can be thinned. Further, the polymer film has an oxygen permeability measured by a method according to JIS K 7126-1987 of 1 × 10 −3 mL / (m 2 · 24 h · atm) or less, and a method according to JIS K 7129-1992. The measured water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)%) is preferably 1 × 10 −3 g / (m 2 · 24 h) or less.
　封止部材を凹状に加工するのは、サンドブラスト加工、化学エッチング加工等が使われる。 For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.
　接着剤として具体的には、アクリル酸系オリゴマー、メタクリル酸系オリゴマーの反応性ビニル基を有する光硬化及び熱硬化型接着剤、２－シアノアクリル酸エステル等の湿気硬化型等の接着剤を挙げることができる。また、エポキシ系等の熱及び化学硬化型（二液混合）を挙げることができる。また、ホットメルト型のポリアミド、ポリエステル、ポリオレフィンを挙げることができる。また、カチオン硬化タイプの紫外線硬化型エポキシ樹脂接着剤を挙げることができる。 Specific examples of the adhesive include photocuring and thermosetting adhesives having reactive vinyl groups of acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. be able to. Moreover, heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.
　なお、有機ＥＬ素子が熱処理により劣化する場合があるので、室温から８０℃までに接着硬化できるものが好ましい。また、前記接着剤中に乾燥剤を分散させておいてもよい。封止部分への接着剤の塗布は市販のディスペンサーを使ってもよいし、スクリーン印刷のように印刷してもよい。 In addition, since an organic EL element may deteriorate by heat processing, what can be adhesively cured from room temperature to 80 ° C. is preferable. A desiccant may be dispersed in the adhesive. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.
　また、有機層を挟み支持基板と対向する側の電極の外側に該電極と有機層を被覆し、支持基板と接する形で無機物、有機物の層を形成し封止膜とすることも好適にできる。この場合、該膜を形成する材料としては、水分や酸素等素子の劣化をもたらすものの浸入を抑制する機能を有する材料であればよく、例えば、酸化ケイ素、二酸化ケイ素、窒化ケイ素等を用いることができる。 In addition, it is also preferable that the electrode and the organic layer are coated on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film. . In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can.
　更に該膜の脆弱性を改良するために、これら無機層と有機材料からなる層の積層構造を持たせることが好ましい。これらの膜の形成方法については特に限定はなく、例えば、真空蒸着法、スパッタリング法、反応性スパッタリング法、分子線エピタキシー法、クラスターイオンビーム法、イオンプレーティング法、プラズマ重合法、大気圧プラズマ重合法、プラズマＣＶＤ法、レーザーＣＶＤ法、熱ＣＶＤ法、コーティング法等を用いることができる。 In order to further improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials. There are no particular limitations on the method of forming these films. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.
　封止部材と有機ＥＬ素子の表示領域との間隙には、気相及び液相では、窒素、アルゴン等の不活性気体やフッ化炭化水素、シリコンオイルのような不活性液体を注入することが好ましい。また、真空とすることも可能である。また、内部に吸湿性化合物を封入することもできる。 In the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and liquid phase. preferable. A vacuum can also be used. Moreover, a hygroscopic compound can also be enclosed inside.
　吸湿性化合物としては、例えば、金属酸化物（例えば、酸化ナトリウム、酸化カリウム、酸化カルシウム、酸化バリウム、酸化マグネシウム、酸化アルミニウム等）、硫酸塩（例えば、硫酸ナトリウム、硫酸カルシウム、硫酸マグネシウム、硫酸コバルト等）、金属ハロゲン化物（例えば、塩化カルシウム、塩化マグネシウム、フッ化セシウム、フッ化タンタル、臭化セリウム、臭化マグネシウム、ヨウ化バリウム、ヨウ化マグネシウム等）、過塩素酸類（例えば、過塩素酸バリウム、過塩素酸マグネシウム等）等が挙げられ、硫酸塩、金属ハロゲン化物及び過塩素酸類においては無水塩が好適に用いられる。 Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.), perchloric acids (eg perchloric acid) Barium, magnesium perchlorate, and the like), and anhydrous salts are preferably used in sulfates, metal halides, and perchloric acids.
　≪保護膜、保護板≫
　有機層を挟み支持基板と対向する側の前記封止膜又は前記封止用フィルムの外側に、素子の機械的強度を高めるために、保護膜若しくは保護板を設けてもよい。特に、封止が前記封止膜により行われている場合には、その機械的強度は必ずしも高くないため、このような保護膜、保護板を設けることが好ましい。これに使用することができる材料としては、前記封止に用いたのと同様なガラス板、ポリマー板・フィルム、金属板・フィルム等を用いることができるが、軽量かつ薄膜化ということからポリマーフィルムを用いることが好ましい。 ≪Protective film, protective plate≫
In order to increase the mechanical strength of the element, a protective film or a protective plate may be provided outside the sealing film or the sealing film on the side facing the support substrate with the organic layer interposed therebetween. In particular, when sealing is performed by the sealing film, the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate. As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, etc. used for the sealing can be used, but the polymer film is light and thin. Is preferably used.
　≪光取り出し向上技術≫
　有機エレクトロルミネッセンス素子は、空気よりも屈折率の高い（屈折率１．６～２．１程度の範囲内）層の内部で発光し、発光層で発生した光のうち１５％から２０％程度の光しか取り出せないと一般的に言われている。これは、臨界角以上の角度θで界面（透明基板と空気との界面）に入射する光は、全反射を起こし素子外部に取り出すことができないことや、透明電極ないし発光層と透明基板との間で光が全反射を起こし、光が透明電極ないし発光層を導波し、結果として、光が素子側面方向に逃げるためである。 ≪Light extraction improvement technology≫
An organic electroluminescent element emits light inside a layer having a refractive index higher than that of air (with a refractive index of about 1.6 to 2.1), and about 15% to 20% of light generated in the light emitting layer. It is generally said that only light can be extracted. This is because light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be taken out of the device, or between the transparent electrode or light emitting layer and the transparent substrate. This is because light is totally reflected between the light and the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the direction of the side surface of the device.
　この光の取り出しの効率を向上させる手法としては、例えば、透明基板表面に凹凸を形成し、透明基板と空気界面での全反射を防ぐ方法（例えば、米国特許第４７７４４３５号明細書）、基板に集光性を持たせることにより効率を向上させる方法（例えば、特開昭６３－３１４７９５号公報）、素子の側面等に反射面を形成する方法（例えば、特開平１－２２０３９４号公報）、基板と発光体の間に中間の屈折率を持つ平坦層を導入し、反射防止膜を形成する方法（例えば、特開昭６２－１７２６９１号公報）、基板と発光体の間に基板よりも低屈折率を持つ平坦層を導入する方法（例えば、特開２００１－２０２８２７号公報）、基板、透明電極層や発光層のいずれかの層間（含む、基板と外界間）に回折格子を形成する方法（特開平１１－２８３７５１号公報）等が挙げられる。 As a technique for improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the transparent substrate and the air interface (for example, US Pat. No. 4,774,435), A method for improving efficiency by providing light condensing property (for example, Japanese Patent Laid-Open No. 63-134795), a method for forming a reflective surface on the side surface of an element (for example, Japanese Patent Laid-Open No. 1-220394), a substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the substrate and the light emitter (for example, Japanese Patent Laid-Open No. 62-172691), lower refractive index than the substrate between the substrate and the light emitter A method of introducing a flat layer having a refractive index (for example, Japanese Patent Application Laid-Open No. 2001-202827), a method of forming a diffraction grating between any one of the substrate, the transparent electrode layer, and the light emitting layer (including between the substrate and the outside) ( JP 1 JP), etc. -283751 and the like.
　これらの方法を本発明の有機ＥＬ素子と組み合わせて用いることができるが、基板と発光体の間に基板よりも低屈折率を持つ平坦層を導入する方法、又は基板、透明電極層や発光層のいずれかの層間（含む、基板と外界間）に回折格子を形成する方法を好適に用いることができる。 These methods can be used in combination with the organic EL device of the present invention, but a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or a substrate, a transparent electrode layer or a light emitting layer A method of forming a diffraction grating between any of these layers (including between the substrate and the outside) can be suitably used.
　本発明は、これらの手段を組み合わせることにより、更に高輝度又は耐久性に優れた素子を得ることができる。 In the present invention, by combining these means, it is possible to obtain an element having higher luminance or durability.
　透明電極と透明基板の間に低屈折率の媒質を光の波長よりも長い厚さで形成すると、透明電極から出てきた光は、媒質の屈折率が低いほど、外部への取り出し効率が高くなる。 When a low refractive index medium is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the light extracted from the transparent electrode has a higher extraction efficiency to the outside as the refractive index of the medium is lower. Become.
　低屈折率層としては、例えば、エアロゲル、多孔質シリカ、フッ化マグネシウム、フッ素系ポリマー等が挙げられる。透明基板の屈折率は一般に１．５～１．７程度の範囲内であるので、低屈折率層は、屈折率がおよそ１．５以下であることが好ましい。また更に１．３５以下であることが好ましい。 Examples of the low refractive index layer include aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally in the range of about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Further, it is preferably 1.35 or less.
　また、低屈折率媒質の厚さは、媒質中の波長の２倍以上となるのが望ましい。これは、低屈折率媒質の厚さが、光の波長程度になってエバネッセントで染み出した電磁波が基板内に入り込む厚さになると、低屈折率層の効果が薄れるからである。 Also, the thickness of the low refractive index medium is preferably at least twice the wavelength in the medium. This is because the effect of the low-refractive index layer is reduced when the thickness of the low-refractive index medium is about the wavelength of light and the electromagnetic wave exuded by evanescent enters the substrate.
　全反射を起こす界面又は、いずれかの媒質中に回折格子を導入する方法は、光取り出し効率の向上効果が高いという特徴がある。この方法は、回折格子が１次の回折や、２次の回折といった、いわゆるブラッグ回折により、光の向きを屈折とは異なる特定の向きに変えることができる性質を利用して、発光層から発生した光のうち、層間での全反射等により外に出ることができない光を、いずれかの層間若しくは、媒質中（透明基板内や透明電極内）に回折格子を導入することで光を回折させ、光を外に取り出そうとするものである。 The method of introducing a diffraction grating into an interface that causes total reflection or in any medium has a feature that the effect of improving the light extraction efficiency is high. This method uses the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction, such as first-order diffraction or second-order diffraction. The light that cannot be emitted due to total internal reflection between layers is diffracted by introducing a diffraction grating into any layer or medium (in the transparent substrate or transparent electrode). , Trying to extract light out.
　導入する回折格子は、二次元的な周期屈折率を持っていることが望ましい。これは、発光層で発光する光はあらゆる方向にランダムに発生するので、ある方向にのみ周期的な屈折率分布を持っている一般的な一次元回折格子では、特定の方向に進む光しか回折されず、光の取り出し効率がさほど上がらない。 It is desirable that the diffraction grating to be introduced has a two-dimensional periodic refractive index. This is because light emitted from the light-emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. The light extraction efficiency does not increase so much.
　しかしながら、屈折率分布を二次元的な分布にすることにより、あらゆる方向に進む光が回折され、光の取り出し効率が上がる。 However, by making the refractive index distribution a two-dimensional distribution, the light traveling in all directions is diffracted, and the light extraction efficiency is increased.
　回折格子を導入する位置としては、いずれかの層間、若しくは媒質中（透明基板内や透明電極内）でも良いが、光が発生する場所である有機発光層の近傍が望ましい。このとき、回折格子の周期は、媒質中の光の波長の約１／２～３倍程度の範囲内が好ましい。回折格子の配列は、正方形のラチス状、三角形のラチス状、ハニカムラチス状等、二次元的に配列が繰り返されることが好ましい。 The position where the diffraction grating is introduced may be in any layer or in the medium (in the transparent substrate or the transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated. At this time, the period of the diffraction grating is preferably in the range of about 1/2 to 3 times the wavelength of light in the medium. The arrangement of the diffraction grating is preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.
　≪集光シート≫
　本発明の有機ＥＬ素子は、支持基板（基板）の光取り出し側に、例えばマイクロレンズアレイ上の構造を設けるように加工したり、又は、いわゆる集光シートと組み合わせたりすることにより、特定方向、例えば素子発光面に対し正面方向に集光することにより、特定方向上の輝度を高めることができる。 ≪Condenser sheet≫
The organic EL element of the present invention is processed to provide a structure on a microlens array, for example, on the light extraction side of the support substrate (substrate), or combined with a so-called condensing sheet, so that a specific direction, For example, the luminance in a specific direction can be increased by condensing light in the front direction with respect to the element light emitting surface.
　マイクロレンズアレイの例としては、基板の光取り出し側に一辺が３０μｍでその頂角が９０度となるような四角錐を二次元に配列する。一辺は１０～１００μｍの範囲内が好ましい。これより小さくなると回折の効果が発生して色付き、大きすぎると厚さが厚くなり好ましくない。 As an example of the microlens array, a quadrangular pyramid having a side of 30 μm and an apex angle of 90 degrees is arranged two-dimensionally on the light extraction side of the substrate. One side is preferably within a range of 10 to 100 μm. If it is smaller than this, the effect of diffraction is generated and colored, and if it is too large, the thickness becomes thick, which is not preferable.
　集光シートとしては、例えば液晶表示装置のＬＥＤバックライトで実用化されているものを用いることが可能である。このようなシートとして例えば、住友スリーエム社製輝度上昇フィルム（ＢＥＦ）等を用いることができる。プリズムシートの形状としては、例えば基材に頂角９０度、ピッチ５０μｍの△状のストライプが形成されたものであってもよいし、頂角が丸みを帯びた形状、ピッチをランダムに変化させた形状、その他の形状であっても良い。 As the condensing sheet, it is possible to use, for example, an LED backlight of a liquid crystal display device that has been put into practical use. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used. As the shape of the prism sheet, for example, a substrate may be formed with a Δ-shaped stripe having an apex angle of 90 degrees and a pitch of 50 μm, or the apex angle is rounded and the pitch is changed randomly. Other shapes may also be used.
　また、有機ＥＬ素子からの光放射角を制御するために光拡散板・フィルムを、集光シートと併用してもよい。例えば、（株）きもと製拡散フィルム（ライトアップ）等を用いることができる。 Further, in order to control the light emission angle from the organic EL element, a light diffusion plate / film may be used in combination with the light collecting sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.
　≪用途≫
　本発明の有機ＥＬ素子は、表示デバイス、ディスプレイ、各種発光光源として用いることができる。 ≪Usage≫
The organic EL element of the present invention can be used as a display device, a display, and various light emission sources.
　発光光源として、例えば、照明装置（家庭用照明、車内照明）、時計や液晶用バックライト、看板広告、信号機、光記憶媒体の光源、電子写真複写機の光源、光通信処理機の光源、光センサーの光源等が挙げられるがこれに限定するものではないが、特に液晶表示装置のバックライト、照明用光源としての用途に有効に用いることができる。 For example, lighting devices (home lighting, interior lighting), clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light Although the light source of a sensor etc. are mentioned, It is not limited to this, Especially, it can use effectively for the use as a backlight of a liquid crystal display device, and a light source for illumination.
　本発明の有機ＥＬ素子においては、必要に応じ製膜時にメタルマスクやインクジェットプリンティング法等でパターニングを施してもよい。パターニングする場合は、電極のみをパターニングしてもよいし、電極と発光層をパターニングしてもよいし、素子全層をパターニングしてもよく、素子の作製においては、従来公知の方法を用いることができる。 In the organic EL device of the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like when forming a film, if necessary. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned. In the fabrication of the element, a conventionally known method is used. Can do.
　≪表示装置≫
　以下、本発明の有機ＥＬ素子を有する表示装置の一例を図面に基づいて説明する。 ≪Display device≫
Hereinafter, an example of a display device having the organic EL element of the present invention will be described with reference to the drawings.
　図３は、本発明の有機ＥＬ素子から構成される表示装置の構成の一例を示した概略斜視図であって、有機ＥＬ素子の発光により画像情報の表示を行う、例えば、携帯電話等のディスプレイの模式図である。図３に示すとおり、ディスプレイ１は、複数の画素を有する表示部Ａ、画像情報に基づいて表示部Ａの画像走査を行う制御部Ｂ等からなる。 FIG. 3 is a schematic perspective view showing an example of a configuration of a display device including the organic EL element of the present invention, and displays image information by light emission of the organic EL element, for example, a display such as a mobile phone FIG. As shown in FIG. 3, the display 1 includes a display unit A having a plurality of pixels, a control unit B that performs image scanning of the display unit A based on image information, and the like.
　制御部Ｂは表示部Ａと電気的に接続されている。制御部Ｂは、複数の画素それぞれに対し、外部からの画像情報に基づいて走査信号と画像データ信号を送る。その結果、各画素が走査信号により走査線毎に画像データ信号に応じて順次発光し、画像情報が表示部Ａに表示される。 Control unit B is electrically connected to display unit A. The control unit B sends a scanning signal and an image data signal to each of the plurality of pixels based on image information from the outside. As a result, each pixel sequentially emits light according to the image data signal for each scanning line by the scanning signal, and the image information is displayed on the display unit A.
　図４は、図３に記載の表示部Ａの模式図である。 FIG. 4 is a schematic diagram of the display unit A shown in FIG.
　表示部Ａは基板上に、複数の走査線５及びデータ線６を含む配線部と、複数の画素３等とを有する。 The display unit A has a wiring unit including a plurality of scanning lines 5 and data lines 6, a plurality of pixels 3 and the like on a substrate.
　表示部Ａの主要な部材の説明を以下に行う。 The main components of the display unit A will be described below.
　図４においては、画素３の発光した光が白矢印方向（下方向）へ取り出される場合を示している。配線部の走査線５及び複数のデータ線６はそれぞれ導電材料から構成されている。走査線５とデータ線６は互いに格子状に直交して、その直交する位置で画素３に接続されている（詳細は図示していない）。 FIG. 4 shows a case where the light emitted from the pixel 3 is extracted in the direction of the white arrow (downward). Each of the scanning lines 5 and the plurality of data lines 6 in the wiring portion is made of a conductive material. The scanning lines 5 and the data lines 6 are orthogonal to each other in a grid pattern and are connected to the pixels 3 at the orthogonal positions (details are not shown).
　画素３は、走査線５から走査信号が送信されると、データ線６から画像データ信号を受け取り、受け取った画像データに応じて発光する。 When the scanning signal is transmitted from the scanning line 5, the pixel 3 receives the image data signal from the data line 6 and emits light according to the received image data.
　発光の色が赤領域の画素、緑領域の画素、青領域の画素を適宜同一基板上に並列配置することによって、フルカラー表示が可能となる。 A full-color display is possible by arranging pixels in the red region, the green region, and the blue region as appropriate in parallel on the same substrate.
　≪照明装置≫
　本発明の有機ＥＬ素子を具備した、本発明の照明装置の一態様について説明する。 ≪Lighting device≫
One aspect of the lighting device of the present invention that includes the organic EL element of the present invention will be described.
　本発明の有機ＥＬ素子の非発光面をガラスケースで覆い、厚さ３００μｍのガラス基板を封止用基板として用いて、周囲にシール材として、エポキシ系光硬化型接着剤（東亞合成社製ラックストラックＬＣ０６２９Ｂ）を適用し、これを陰極上に重ねて透明支持基板と密着させ、ガラス基板側からＵＶ光を照射して、硬化させて、封止し、図５、図６に示すような照明装置を形成することができる。 The non-light emitting surface of the organic EL device of the present invention is covered with a glass case, a 300 μm thick glass substrate is used as a sealing substrate, and an epoxy photocurable adhesive (LUX The track LC0629B) is applied, and this is overlaid on the cathode and brought into close contact with the transparent support substrate, irradiated with UV light from the glass substrate side, cured, sealed, and illuminated as shown in FIGS. A device can be formed.
　図５は、照明装置の概略図を示し、本発明の有機ＥＬ素子１０１はガラスカバー１０２で覆われている（なお、ガラスカバーでの封止作業は、有機ＥＬ素子１０１を大気に接触させることなく窒素雰囲気下のグローブボックス（純度９９．９９９％以上の高純度窒素ガスの雰囲気下）で行う。）。 FIG. 5 shows a schematic diagram of a lighting device, and the organic EL element 101 of the present invention is covered with a glass cover 102 (in addition, the sealing operation with the glass cover is to bring the organic EL element 101 into contact with the atmosphere. Without using a glove box under a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas with a purity of 99.999% or higher).
　図６は、照明装置の断面図を示し、図６において、１０５は陰極、１０６は有機ＥＬ層（発光ユニット）、１０７は透明電極付きガラス基板を示す。なお、ガラスカバー１０２内には窒素ガス１０８が充填され、捕水剤１０９が設けられている。 FIG. 6 shows a cross-sectional view of the lighting device. In FIG. 6, 105 denotes a cathode, 106 denotes an organic EL layer (light emitting unit), and 107 denotes a glass substrate with a transparent electrode. The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.
　なお、本発明を適用可能な実施形態は、上述した実施形態に限定されることなく、本発明の趣旨を逸脱しない範囲で適宜変更可能である。 Note that embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention.
　以下、実施例を挙げて本発明を具体的に説明するが、本発明はこれらに限定されるものではない。なお、実施例において「部」又は「％」の表示を用いるが、特に断りがない限り「質量部」又は「質量％」を表す。 Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.
　なお、以下の実施例１～３において使用する化合物の化学構造は下記のとおりである。 The chemical structures of the compounds used in Examples 1 to 3 below are as follows.
Figure JPOXMLDOC01-appb-C000046
Figure JPOXMLDOC01-appb-C000046
Figure JPOXMLDOC01-appb-C000047
Figure JPOXMLDOC01-appb-C000047
Figure JPOXMLDOC01-appb-C000048
Figure JPOXMLDOC01-appb-C000048
Figure JPOXMLDOC01-appb-C000049
Figure JPOXMLDOC01-appb-C000049
Figure JPOXMLDOC01-appb-C000050
Figure JPOXMLDOC01-appb-C000050
Figure JPOXMLDOC01-appb-C000051
Figure JPOXMLDOC01-appb-C000051
　≪実施例１≫
　［有機ＥＬ素子１－１～１－１２の作製］
　（基材の準備）
　５０ｍｍ×５０ｍｍ、厚さ０．７ｍｍのガラス基板上に、陽極としてＩＴＯ（インジウム・スズ酸化物）を１５０ｎｍの厚さで成膜し、パターニングを行った後、このＩＴＯ透明電極を付けた透明基板をイソプロピルアルコールで超音波洗浄し、乾燥窒素ガスで乾燥し、ＵＶオゾン洗浄を５分間行った。 Example 1
[Production of Organic EL Elements 1-1 to 1-12]
(Preparation of base material)
A transparent substrate with an ITO (Indium Tin Oxide) film having a thickness of 150 nm formed on a glass substrate of 50 mm × 50 mm and a thickness of 0.7 mm, patterned, and this ITO transparent electrode was attached Was subjected to ultrasonic cleaning with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.
　（正孔注入層の形成）
　この透明支持基板上に、ポリ（３，４－エチレンジオキシチオフェン）－ポリスチレン
　スルホネート（ＰＥＤＯＴ／ＰＳＳ、Ｂａｙｅｒ社製、Ｂａｙｔｒｏｎ　Ｐ　Ａｌ　４０　８３）を純水で７０％に希釈した溶液を用いて３０００ｒｐｍ、３０秒の条件下、スピンコート法により薄膜を形成した後、２００℃にて１時間乾燥し、膜厚２０ｎｍの正孔注入層を設けた。 (Formation of hole injection layer)
On this transparent support substrate, using a solution obtained by diluting poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, Bayer, Baytron P Al 40 83) to 70% with pure water, 3000 rpm After forming a thin film by spin coating under a condition of 30 seconds, the film was dried at 200 ° C. for 1 hour to provide a hole injection layer having a thickness of 20 nm.
　この透明基板を市販の真空蒸着装置の基板ホルダーに固定した。
　真空蒸着装置内の蒸着用るつぼの各々に、各層の構成材料を、各々素子作製に最適の量を充填した。蒸着用るつぼは、モリブデン製又はタングステン製の抵抗加熱用材料で作製されたものを用いた。 This transparent substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus.
Each of the vapor deposition crucibles in the vacuum vapor deposition apparatus was filled with the constituent material of each layer in an amount optimal for device fabrication. As the evaporation crucible, a crucible made of a resistance heating material made of molybdenum or tungsten was used.
　（正孔輸送層の形成）
　真空度１×１０－４Ｐａまで減圧した後、α－ＮＰＤの入った蒸着用るつぼに通電して加熱し、蒸着速度０．１ｎｍ／秒で正孔注入層上に蒸着し、厚さ３０ｎｍの正孔輸送層を形成した (Formation of hole transport layer)
After reducing the vacuum to 1 × 10 −4 Pa, the energization crucible containing α-NPD was energized and heated, and deposited on the hole injection layer at a deposition rate of 0.1 nm / second. Hole transport layer formed
　（発光層の形成）
　次いで、発光層の化合物を、ホスト化合物Ｈ－１、リン光発光性化合物ＰＤ－１、表Iに記した蛍光発光性化合物がそれぞれ８４．５体積％、１５体積％、０．５体積％になるように、蒸着速度０．０６ｎｍ／秒で正孔輸送層上に共蒸着し、厚さ３０ｎｍの発光層を形成した。 (Formation of light emitting layer)
Next, the compound of the light emitting layer was changed to 84.5% by volume, 15% by volume, and 0.5% by volume of the host compound H-1, the phosphorescent compound PD-1, and the fluorescent compound described in Table I, respectively. Thus, it was co-deposited on the hole transport layer at a deposition rate of 0.06 nm / second to form a light emitting layer having a thickness of 30 nm.
　（正孔阻止層の形成）
　その後、化合物Ｈ－１を蒸着速度０．１ｎｍ／秒で蒸着し、厚さ１０ｎｍの正孔阻止層を形成した。 (Formation of hole blocking layer)
Thereafter, Compound H-1 was deposited at a deposition rate of 0.1 nm / second to form a 10 nm thick hole blocking layer.
　（電子輸送層の形成）
　更にその上に化合物ＡＬｑ３を蒸着速度０．１ｎｍ／秒で蒸着し、厚さ３０ｎｍの電子輸送層を形成した。 (Formation of electron transport layer)
Further, the compound ALq3 was deposited thereon at a deposition rate of 0.1 nm / second to form an electron transport layer having a thickness of 30 nm.
　（陰極の形成）
　さらに、フッ化リチウムの層（電子注入層）を厚さ０．５ｎｍで形成した後に、アルミニウム１００ｎｍを蒸着して陰極を形成した。 (Formation of cathode)
Further, after forming a lithium fluoride layer (electron injection layer) with a thickness of 0.5 nm, 100 nm of aluminum was deposited to form a cathode.
　（封止）
　上記陰極が形成された素子の非発光面側を、純度９９．９９９％以上の高純度窒素ガスの雰囲気下で、缶状ガラスケースで覆い、電極取り出し配線を設置して、有機ＥＬ素子１－１～１－１２を作製した。 (Sealing)
The non-light-emitting surface side of the element on which the cathode is formed is covered with a can-shaped glass case in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more, and an electrode lead-out wiring is installed. 1 to 1-12 were produced.
　［評価］
　発光減衰寿命τ及び発光減衰寿命τ0並びに発光層単層の絶対量子収率ＰＬＱＥ（φ）及びリン光発光性化合物の単膜の絶対量子収率ＰＬＱＥ（φ0）については、下記評価用
発光性膜を作製し、当該評価用発光性膜とリン光発光性化合物の単膜を計測することで求めた。 [Evaluation]
Regarding the light emission decay lifetime τ and the light emission decay lifetime τ 0 , the absolute quantum yield PLQE (φ) of the light emitting layer single layer, and the absolute quantum yield PLQE (φ 0 ) of the single film of the phosphorescent compound, This was determined by measuring a single film of the evaluation light-emitting film and the phosphorescent compound.
　＜評価用発光性膜の作製＞
　５０ｍｍ×５０ｍｍ、厚さ０．７ｍｍの石英基板をイソプロピルアルコールで超音波洗浄し、乾燥窒素ガスで乾燥し、ＵＶオゾン洗浄を５分間行った後、この透明基板を市販の真空蒸着装置の基板ホルダーに固定した。真空蒸着装置の蒸着用るつぼの各々に、有機ＥＬ素子１－１～１－１２で使用されるホスト化合物Ｈ－１、リン光発光性化合物ＰＤ－１及び各蛍光発光性化合物を、各々素子作製の際と同様の量となるように充填した。蒸着用るつぼはモリブデン製の抵抗加熱用材料で作製されたものを用いた。
　真空蒸着装置内を真空度１×１０－４Ｐａまで減圧した後、ホスト化合物、リン光発光性化合物、蛍光発光性化合物が、それぞれ８４．５体積％、１５体積％、０．５体積％になるように、蒸着速度０．０６ｎｍ／秒の蒸着速度で蒸着させ、膜厚３０ｎｍの評価用発光性膜１－１～１－１２を作製した。なお、評価用発光性膜１－１～１－１２に含有される「ホスト化合物」、「リン光発光性化合物」及び「蛍光発光性化合物」の種類並びに各化合物の濃度は、それぞれ、有機ＥＬ素子１－１～１－１２に対応する。 <Preparation of evaluation light-emitting film>
A quartz substrate having a size of 50 mm × 50 mm and a thickness of 0.7 mm is ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. The transparent substrate is then used as a substrate holder for a commercially available vacuum deposition apparatus. Fixed to. In each of the vapor deposition crucibles of the vacuum vapor deposition apparatus, the host compound H-1, the phosphorescent compound PD-1, and the respective fluorescent compounds used in the organic EL elements 1-1 to 1-12 were prepared. It filled so that it might become the amount similar to the case of this time. The evaporation crucible used was made of a resistance heating material made of molybdenum.
After depressurizing the inside of the vacuum evaporation system to a vacuum degree of 1 × 10 −4 Pa, the host compound, phosphorescent compound, and fluorescent compound were 84.5% by volume, 15% by volume, and 0.5% by volume, respectively. In this way, vapor deposition was performed at a vapor deposition rate of 0.06 nm / second to prepare evaluation light-emitting films 1-1 to 1-12 having a film thickness of 30 nm. The types of “host compounds”, “phosphorescent compounds” and “fluorescent compounds” contained in the evaluation light-emitting films 1-1 to 1-12, and the concentrations of the respective compounds are as follows. This corresponds to the elements 1-1 to 1-12.
　次に、評価用発光性膜１－１～１－１２の製造において、蛍光発光性化合物を含有させないほかは同様にしてリン光発光性化合物ＰＤ－１とホスト化合物Ｈ－１からなる単膜（以下、「リン光発光性化合物の単膜ＰＤ－１」ともいう。）を製造した。なお、リン光発光性化合物の単膜ＰＤ－１においては、リン光発光性化合物の含有量は変えず、蛍光発光性化合物を含有させなかった分、ホスト化合物を増やして製造した。 Next, in the production of the light-emitting films for evaluation 1-1 to 1-12, a single film composed of the phosphorescent compound PD-1 and the host compound H-1 in the same manner except that no fluorescent compound is contained ( Hereinafter, “single film PD-1 of phosphorescent compound” was also produced. In addition, the phosphorescent compound single film PD-1 was produced by changing the content of the phosphorescent compound and increasing the host compound by the amount not containing the fluorescent compound.
　＜スペクトルの重なり＞
　リン光発光性化合物の単膜の発光スペクトルと、蛍光発光性化合物の溶液吸収スペクトルとを用いて、有機ＥＬ素子１－１～１－１２に対応する、リン光発光性化合物の発光スペクトルと蛍光発光性化合物の吸収スペクトルとの重なりの有無を調べたところ、いずれもリン光発光性化合物の発光スペクトルと蛍光発光性化合物の吸収スペクトルとが重なりを有していることが確認された。測定手法は以下に記す。 <Spectral overlap>
Using the emission spectrum of the phosphorescent compound single film and the solution absorption spectrum of the fluorescent compound, the emission spectrum and fluorescence of the phosphorescent compound corresponding to the organic EL elements 1-1 to 1-12 When the presence or absence of an overlap with the absorption spectrum of the luminescent compound was examined, it was confirmed that both the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound had an overlap. The measurement method is described below.
　（リン発光性化合物の発光スペクトルの測定）
　上記リン光発光性化合物の単膜ＰＤ－１について、発光スペクトルの測定を行い、これをリン発光性化合物ＰＤ－１の発光スペクトルとした。なお、発光スペクトルの測定は、日立製のＦ－７０００型分光蛍光光度計を用い、室温（３００Ｋ）にて行った。 (Measurement of emission spectrum of phosphorescent compound)
An emission spectrum of the phosphorescent compound single film PD-1 was measured and used as an emission spectrum of the phosphorescent compound PD-1. The emission spectrum was measured at room temperature (300 K) using a Hitachi F-7000 spectrofluorometer.
　（蛍光発光性化合物の溶液吸収スペクトルの測定）
　蛍光発光性化合物の溶液吸収スペクトル（極大吸収波長λabs）の測定については、下記のようにして行った。
　まず、蛍光発光性化合物を、２－メチルテトラヒドロフラン（２ｍ－ＴＨＦ）（安定剤なし）に溶解させて、濃度１．０×１０－５ｍｏｌ／Ｌの溶液を得た。得られた溶液を、石英セル（１０ｍｍ長四角セル）に入れて、分光光度計（ＨＩＴＡＣＨＩ　Ｕ－３３００分光光度計）を用いて、溶液の波長領域２５０～７００ｎｍの範囲の吸光度を測定した（液温は２３℃であった。）。 (Measurement of solution absorption spectrum of fluorescent compound)
The measurement of the solution absorption spectrum (maximum absorption wavelength λ abs ) of the fluorescent compound was performed as follows.
First, the fluorescent compound was dissolved in 2-methyltetrahydrofuran (2m-THF) (without stabilizer) to obtain a solution having a concentration of 1.0 × 10 −5 mol / L. The obtained solution was put into a quartz cell (10 mm long square cell), and the absorbance in the wavelength region of 250 to 700 nm of the solution was measured using a spectrophotometer (HITACHI U-3300 spectrophotometer) (liquid). The temperature was 23 ° C.).
　＜τ／τ0＞
　以下のようにして、発光減衰寿命τ及び発光減衰寿命τ0を測定し、τ／τ0を求めた。 <Τ / τ 0 >
The emission decay lifetime τ and the emission decay lifetime τ 0 were measured as follows, and τ / τ 0 was obtained.
　（発光減衰寿命τの測定）
　有機ＥＬ素子１－１～１－１２に係る発光層単層の発光減衰寿命τの測定として、評価用発光性膜１－１～１－１２の発光減衰寿命τを測定した。具体的には、評価用発光性膜１－１～１－１２の発光減衰寿命τは、過渡ＰＬ特性を測定することによって求めた。過渡ＰＬ特性の測定には、小型蛍光寿命測定装置Ｃ１１３６７－０３（浜松ホトニクス社製）を用いた。減衰成分は、２８０ｎｍのＬＥＤを励起光源としたＴＣＣ９００モードにて測定した。 (Measurement of emission decay lifetime τ)
As the measurement of the light emission decay lifetime τ of the single light emitting layer relating to the organic EL elements 1-1 to 1-12, the light emission decay lifetime τ of the evaluation light emitting films 1-1 to 1-12 was measured. Specifically, the emission decay lifetimes τ of the evaluation light-emitting films 1-1 to 1-12 were obtained by measuring transient PL characteristics. A small fluorescent lifetime measuring device C11367-03 (manufactured by Hamamatsu Photonics) was used for measurement of transient PL characteristics. The attenuation component was measured in TCC900 mode using an 280 nm LED as an excitation light source.
　（発光減衰寿命τ0）
　評価用発光性膜１－１～１－１２の代わりに、リン光発光性化合物の単膜ＰＤ－１を使用したほかは、発光減衰寿命τの測定と同様にして、発光減衰寿命τ0を測定した。 (Luminescence decay lifetime τ 0 )
A light emission decay lifetime τ 0 is obtained in the same manner as the measurement of the light emission decay lifetime τ, except that the phosphorescent compound single film PD-1 is used instead of the evaluation light emission membrane 1-1 to 1-12. It was measured.
　＜φ／φ0＞
　以下のようにして、有機ＥＬ素子１－１～１－１２に係る発光層単層の絶対量子収率ＰＬＱＥ（φ）及びリン光発光性化合物の単膜の絶対量子収率ＰＬＱＥ（φ0）を測定し、φ／φ0を求めた。結果は表Iに示すとおりである。 <Φ / φ 0 >
In the following manner, the absolute quantum yield PLQE (φ) of the single light emitting layer and the absolute quantum yield PLQE (φ 0 ) of the single layer of the phosphorescent compound according to the organic EL elements 1-1 to 1-12 Was measured to determine φ / φ 0 . The results are shown in Table I.
　（絶対量子収率ＰＬＱＥ（φ）の測定）
　有機ＥＬ素子１－１～１－１２に対応する評価用発光性膜１－１～１－１２の絶対量子収率ＰＬＱＥ（φ）を、絶対量子収率測定装置Ｃ９９２０－０２（浜松ホトニクス社製）を用いて測定した。 (Measurement of absolute quantum yield PLQE (φ))
The absolute quantum yield PLQE (φ) of the light-emitting films for evaluation 1-1 to 1-12 corresponding to the organic EL elements 1-1 to 1-12 was measured using an absolute quantum yield measuring device C9920-02 (manufactured by Hamamatsu Photonics). ).
　（絶対量子収率ＰＬＱＥ（φ0）の測定）
　評価用発光性膜１－１～１－１２の代わりに、リン光発光性化合物の単膜ＰＤ－１を使用したほかは、絶対量子収率ＰＬＱＥ（φ）の測定と同様にして、絶対量子収率ＰＬＱＥ（φ0）を測定した。 (Measurement of absolute quantum yield PLQE (φ 0 ))
The absolute quantum yield PLQE (φ) was measured in the same manner as the absolute quantum yield PLQE (φ) except that the phosphorescent compound single film PD-1 was used instead of the evaluation light-emitting films 1-1 to 1-12. The yield PLQE (φ 0 ) was measured.
　＜ストークスシフトの測定＞
　溶液吸収スペクトルの最長波側の吸収帯の極大吸収波長λabs（ｎｍ）と、溶液発光スペクトルの最も短波側の極大発光波長λem（ｎｍ）をエネルギー（ｅＶ）に換算し、その差分より求めた。具体的には、下記式でストークスシフトを算出した。
　ストークスシフト（ｅＶ）＝｜１２４０／λabs－１２４０／λem｜ <Measurement of Stokes shift>
The maximum absorption wavelength λ abs (nm) of the absorption band on the longest wave side of the solution absorption spectrum and the maximum emission wavelength λ em (nm) of the shortest wave side of the solution emission spectrum are converted into energy (eV) and obtained from the difference. It was. Specifically, the Stokes shift was calculated by the following formula.
Stokes shift (eV) = | 1240 / λ abs −1240 / λ em |
　（極大吸収波長λabsの測定）
　上記蛍光発光性化合物の溶液吸収スペクトル（極大吸収波長λabs）の測定については、上記「蛍光発光性化合物の溶液吸収スペクトルの測定」と同様にして行った。
　そして、得られた溶液吸収スペクトルにおける極大吸収ピークに対応する波長を極大吸収波長λabsとした。なお、上記波長範囲に吸収ピークが複数ある場合、最も長波長側にあるピークを吸収ピークとした。 (Measurement of maximum absorption wavelength λ abs )
The solution absorption spectrum (maximum absorption wavelength λ abs ) of the fluorescent compound was measured in the same manner as the above-mentioned “Measurement of solution absorption spectrum of fluorescent compound”.
The wavelength corresponding to the maximum absorption peak in the obtained solution absorption spectrum was defined as the maximum absorption wavelength λabs . When there are a plurality of absorption peaks in the above wavelength range, the peak on the longest wavelength side was taken as the absorption peak.
　（極大発光波長λemの測定）
　上記蛍光発光性化合物の極大発光波長λemの測定については、下記のようにして行った。
　まず、蛍光発光性化合物を、２－メチルテトラヒドロフラン（２ｍ－ＴＨＦ）に溶解させて１×１０－５ｍｏｌ／Ｌの２ｍ－ＴＨＦ溶液を調製した。
　得られた溶液につき、窒素ガス（Ｎ2）を１０分間吹き込みバブリングした後、蛍光光度計（ＨＩＴＡＣＨＩ　Ｆ－７０００）用いて測定した（液温は２３℃であった。）。
　なお、測定では、極大吸収波長を励起光として、発光スペクトルを測定し、当該発光スペクトルにおける最大の極大発光波長を、極大発光波長λemとした。なお、上記波長範囲に発光ピークが複数ある場合、最も短波長側にあるピークを発光ピークとした。 (Measurement of maximum emission wavelength λ em )
The measurement of the maximum emission wavelength λ em of the fluorescent compound was performed as follows.
First, the fluorescent compound was dissolved in 2-methyltetrahydrofuran (2m-THF) to prepare 1 × 10 −5 mol / L 2m-THF solution.
The obtained solution was bubbled with nitrogen gas (N 2 ) for 10 minutes and then measured using a fluorometer (HITACHI F-7000) (liquid temperature was 23 ° C.).
In the measurement, an emission spectrum was measured using the maximum absorption wavelength as excitation light, and the maximum maximum emission wavelength in the emission spectrum was defined as the maximum emission wavelength λ em . When there are a plurality of emission peaks in the above wavelength range, the peak at the shortest wavelength side is defined as the emission peak.
　＜半減寿命の加速係数＞
　下記（Ｂ）式から、半減寿命の加速係数ｎを求めた。結果は表Iに示すとおりである。
　ｔ1／ｔ2＝（Ｌ1／Ｌ2）－ｎ・・・（Ｂ）
［Ｌ1：電流密度２．５ｍＡ／ｃｍ２印加時の初期輝度
　Ｌ2：電流密度１６．２５ｍＡ／ｃｍ２印加時の初期輝度
　ｔ1：輝度Ｌ1（低電流２．５ｍＡ／ｃｍ２）での半減寿命
　ｔ2：輝度Ｌ2（高電流１６．２５ｍＡ／ｃｍ２）での半減寿命］
　なお、輝度の測定には、分光放射輝度計ＣＳ－２０００（コニカミノルタ（株）製）を用いた。 <Acceleration coefficient of half-life>
From the following formula (B), the half-life acceleration coefficient n was determined. The results are shown in Table I.
t 1 / t 2 = (L 1 / L 2 ) −n (B)
[L 1: current density 2.5 mA / cm 2 upon application of the initial luminance L 2: current density 16.25mA / cm 2 applied during the initial luminance t 1: the luminance L 1 (low current 2.5 mA / cm 2) T 2 : Half life at luminance L 2 (high current 16.25 mA / cm 2 )]
For measurement of luminance, a spectral radiance meter CS-2000 (manufactured by Konica Minolta Co., Ltd.) was used.
　半減寿命の加速係数の判断基準は下記のとおりである。
　○：１．４未満　（合格）
　△：１．４以上１．６未満　（不合格）
　×：１．６以上　（不合格） The criteria for determining the half-life acceleration factor are as follows.
○: Less than 1.4 (pass)
Δ: 1.4 or more and less than 1.6 (failed)
X: 1.6 or more (failed)
　なお、従来、有機ＥＬ素子の輝度半減寿命の加速係数は１．６前後であることが知られている（Ａｐｐｌ．　Ｐｈｙｓ．　Ｌｅｔｔ．　９１，　２５１１１１　（２００７），　Ｓｃｉ．　Ｔｅｃｈｎｏｌ．　Ａｄｖ．　Ｍａｔｅｒ．　１５　（２０１４）　０３４２０１）。 Conventionally, it is known that the acceleration coefficient of the luminance half-life of the organic EL element is around 1.6 (Appl. Phys. Lett. 91, 251111 (2007), Sci. Technol. Adv. Mater. 15). (2014) 034201).
Figure JPOXMLDOC01-appb-T000052
Figure JPOXMLDOC01-appb-T000052
　（まとめ）
　表Iより蛍光発光性化合物のストークスシフトが、０．１ｅＶ以下であることで、半減
寿命の加速係数を好適にできることが示された。
　これについては、下記のように考えている。
　ストークスシフトが小さい蛍光発光性化合物は励起状態と基底状態の構造変動が小さい。このことは、励起エネルギーと発光エネルギーの差が小さく、熱的ロスが小さいので、発熱抑制に繋がり、加えて、構造変動も小さいので、発熱や分子構造変動由来での経時の膜質変動を誘起させにくく、寿命が低下しにくいためであると考える。 (Summary)
From Table I, it was shown that when the Stokes shift of the fluorescent compound is 0.1 eV or less, the half-life acceleration coefficient can be suitably used.
This is considered as follows.
A fluorescent compound having a small Stokes shift has a small structural variation between an excited state and a ground state. This is because the difference between excitation energy and emission energy is small and the thermal loss is small, which leads to suppression of heat generation.In addition, the structural fluctuation is also small, which induces film quality fluctuation over time due to heat generation and molecular structure fluctuation. This is considered to be because it is difficult to reduce the service life.
　≪実施例２≫
　［有機ＥＬ素子２－１～２－１１の作製］
　（基材の準備）
　５０ｍｍ×５０ｍｍ、厚さ０．７ｍｍのガラス基板上に、陽極としてＩＴＯ（インジウム・スズ酸化物）を１５０ｎｍの厚さで成膜し、パターニングを行った後、このＩＴＯ透明電極を付けた透明基板をイソプロピルアルコールで超音波洗浄し、乾燥窒素ガスで乾燥し、ＵＶオゾン洗浄を５分間行った。 << Example 2 >>
[Production of Organic EL Elements 2-1 to 2-11]
(Preparation of base material)
A transparent substrate with an ITO (Indium Tin Oxide) film having a thickness of 150 nm formed on a glass substrate of 50 mm × 50 mm and a thickness of 0.7 mm, patterned, and this ITO transparent electrode was attached Was subjected to ultrasonic cleaning with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.
　（正孔注入層の形成）
　この透明支持基板上に、ポリ（３，４－エチレンジオキシチオフェン）－ポリスチレン　スルホネート（ＰＥＤＯＴ／ＰＳＳ、Ｂａｙｅｒ社製、Ｂａｙｔｒｏｎ　Ｐ　Ａｌ　４０　８３）を純水で７０％に希釈した溶液を用いて３０００ｒｐｍ、３０秒の条件下、スピンコート法により薄膜を形成した後、２００℃にて１時間乾燥し、厚さ２０ｎｍの正孔注入層を形成した。 (Formation of hole injection layer)
On this transparent support substrate, using a solution obtained by diluting poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, Bayer, Baytron P Al 40 83) to 70% with pure water, 3000 rpm After forming a thin film by spin coating under a condition of 30 seconds, the film was dried at 200 ° C. for 1 hour to form a hole injection layer having a thickness of 20 nm.
　次に、この透明基板を市販の真空蒸着装置の基板ホルダーに固定した。
　真空蒸着装置内の蒸着用るつぼの各々に、各層の構成材料を、各々素子作製に最適の量を充填した。蒸着用るつぼは、モリブデン製の抵抗加熱用材料で作製されたものを用いた。 Next, this transparent substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus.
Each of the vapor deposition crucibles in the vacuum vapor deposition apparatus was filled with the constituent material of each layer in an amount optimal for device fabrication. The crucible for vapor deposition used what was produced with the resistance heating material made from molybdenum.
　（正孔輸送層の形成）
　真空度１×１０－４Ｐａまで減圧した後、α－ＮＰＤの入った蒸着用るつぼに通電して加熱し、蒸着速度０．１ｎｍ／秒で前記正孔注入層上に蒸着し、層厚３０ｎｍの正孔輸送層を形成した。 (Formation of hole transport layer)
The pressure was reduced to 1 × 10 −4 Pa, heated by energizing a deposition crucible containing α-NPD, and deposited on the hole injection layer at a deposition rate of 0.1 nm / sec. The hole transport layer was formed.
　（発光層の形成）
　次いで、発光層の化合物として、「ホスト化合物」、「リン光発光性化合物」、「蛍光発光性化合物」を、表IIに記載の種類及び濃度となるように、蒸着速度０．０６ｎｍ／秒で正孔輸送層上に共蒸着し、厚さ３０ｎｍの発光層を形成した。 (Formation of light emitting layer)
Next, as a compound of the light emitting layer, “host compound”, “phosphorescent compound”, and “fluorescent compound” were deposited at a deposition rate of 0.06 nm / second so as to have the types and concentrations described in Table II. Co-evaporation was performed on the hole transport layer to form a light emitting layer having a thickness of 30 nm.
　（正孔阻止層の形成）
　その後、発光層の上にＨＢ－１を蒸着速度０．１ｎｍ／秒で蒸着し、厚さ１０ｎｍの正孔阻止層を形成した。 (Formation of hole blocking layer)
Thereafter, HB-1 was deposited on the light emitting layer at a deposition rate of 0.1 nm / second to form a 10 nm thick hole blocking layer.
　（電子輸送層の形成）
　更に正孔阻止層の上に化合物ＥＴ－１を蒸着速度０．１ｎｍ／秒で蒸着し、厚さ３０ｎｍの電子輸送層を形成した。 (Formation of electron transport layer)
Further, Compound ET-1 was deposited on the hole blocking layer at a deposition rate of 0.1 nm / second to form an electron transport layer having a thickness of 30 nm.
　（陰極の形成）
　さらに、フッ化リチウムの層（電子注入層）を厚さ０．５ｎｍで形成した後に、アルミニウム１００ｎｍを蒸着して陰極を形成した。 (Formation of cathode)
Further, after forming a lithium fluoride layer (electron injection layer) with a thickness of 0.5 nm, 100 nm of aluminum was deposited to form a cathode.
　（封止）
　上記陰極が形成された素子の非発光面側を、純度９９．９９９％以上の高純度窒素ガスの雰囲気下で、缶状ガラスケースで覆い、電極取り出し配線を設置して、有機ＥＬ素子２－１～２－１１を作製した。 (Sealing)
The non-light-emitting surface side of the element on which the cathode is formed is covered with a can-shaped glass case in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more, an electrode lead-out wiring is installed, and the organic EL element 2- 1 to 2-11 were produced.
　［評価］
　発光減衰寿命τ及び発光減衰寿命τ0並びに発光層単層の絶対量子収率ＰＬＱＥ（φ）及びリン光発光性化合物の単膜の絶対量子収率ＰＬＱＥ（φ0）については、実施例１と同様に評価用発光性膜及び有機ＥＬ素子２－１～２－１１に含有されるリン光発光性化合物とホスト化合物からなる単膜を作製し、これらをサンプルとして計測することで求めた。
　また、ＨＯＭＯエネルギー準位及びＬＵＭＯエネルギー準位は下記のようにして計算し、スペクトルの重なり、蛍光発光性化合物のストークスシフト及び半減寿命の加速係数ｎについては、実施例１と同様にして求めた。 [Evaluation]
Regarding the light emission decay lifetime τ and the light emission decay lifetime τ 0 , the absolute quantum yield PLQE (φ) of the single layer of the light emitting layer, and the absolute quantum yield PLQE (φ 0 ) of the single layer of the phosphorescent compound, Similarly, a single film composed of a phosphorescent compound and a host compound contained in the evaluation light-emitting film and the organic EL elements 2-1 to 2-11 was prepared, and these were measured as samples.
The HOMO energy level and the LUMO energy level were calculated as follows, and the spectrum overlap, the Stokes shift of the fluorescent compound and the half-life acceleration coefficient n were determined in the same manner as in Example 1. .
　なお、有機ＥＬ素子２－２及び２－６は蛍光発光性化合物のストークスシフトが０．１ｅＶよりも大きいものであった。
　また、有機ＥＬ素子２－７～２－１１は、リン光発光性化合物の発光スペクトルと蛍光発光性化合物の吸収スペクトルとが重なりを有しており、蛍光発光性化合物のストークスシフトが０．１ｅＶ以下であった。 The organic EL elements 2-2 and 2-6 had a Stokes shift of the fluorescent compound having a value larger than 0.1 eV.
In the organic EL devices 2-7 to 2-11, the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound overlap, and the Stokes shift of the fluorescent compound is 0.1 eV. It was the following.
　＜ＨＯＭＯエネルギー準位及びＬＵＭＯエネルギー準位の計算＞
　実施例で使用した蛍光発光性化合物又はリン光発光性化合物の分子軌道計算による構造最適化及び電子密度分布の算出は、計算手法として、ホスト化合物、蛍光発光性化合物は汎関数としてＢ３ＬＹＰ、基底関数として６－３１Ｇ（ｄ）を用い、リン光発光性化合物には汎関数としてＢ３ＬＹＰを、基底関数としてＬａｎＬ２ＤＺを用いた分子軌道計算用ソフトウェアを用いて算出した。
　具体的には、例えば、分子軌道計算用ソフトウェアとして、米国Ｇａｕｓｓｉａｎ社製のＧａｕｓｓｉａｎ０９（Ｒｅｖｉｓｉｏｎ　Ｃ．０１，Ｍ．Ｊ．Ｆｒｉｓｃｈ，ｅｔ　ａｌ，Ｇａｕｓｓｉａｎ，Ｉｎｃ．，２０１０．）を用いた。 <Calculation of HOMO energy level and LUMO energy level>
The structure optimization and the calculation of the electron density distribution of the fluorescent compound or phosphorescent compound used in the examples by molecular orbital calculation are as follows: host compound, fluorescent compound as functional B3LYP, basis function 6-31G (d) was used as a phosphorescent compound, and the molecular orbital calculation software using B3LYP as a functional and LanL2DZ as a basis function was calculated for the phosphorescent compound.
Specifically, for example, Gaussian 09 (Revision C.01, MJ Frisch, et al, Gaussian, Inc., 2010.) manufactured by Gaussian in the United States was used as molecular orbital calculation software.
　＜外部取り出し量子効率（ＥＱＥ）＞
　各有機ＥＬ素子を室温（約２３℃）、２．５ｍＡ／ｃｍ２の定電流条件下による通電を行い、発光開始直後の発光輝度（Ｌ1）［ｃｄ／ｍ２］を測定することにより、外部取り出し量子効率（ＥＱＥ）を算出した。 <External quantum efficiency (EQE)>
By energizing each organic EL element under constant current conditions of room temperature (about 23 ° C.) and 2.5 mA / cm 2 , and measuring the light emission luminance (L 1 ) [cd / m 2 ] immediately after the start of light emission, External extraction quantum efficiency (EQE) was calculated.
　ここで、発光輝度の測定はＣＳ－２０００（コニカミノルタ（株）製）を用いて行い、外部取り出し量子効率は、有機ＥＬ素子２－１を１とする相対比で表した。なお、値が大きいほうが発光効率に優れていることを示す。評価結果を表IIIに示す。 Here, the measurement of emission luminance was performed using CS-2000 (manufactured by Konica Minolta Co., Ltd.), and the external extraction quantum efficiency was expressed as a relative ratio where the organic EL element 2-1 was 1. In addition, the one where a value is large shows that it is excellent in luminous efficiency. The evaluation results are shown in Table III.
Figure JPOXMLDOC01-appb-T000053
Figure JPOXMLDOC01-appb-T000053
Figure JPOXMLDOC01-appb-T000054
Figure JPOXMLDOC01-appb-T000054
　（まとめ）
　表IIIより、比較例に対し、本発明に係る有機ＥＬ素子２－７～２－１１ではＥＱＥが実用的な値を維持しつつ、加速係数を下げることができることが示された。 (Summary)
From Table III, it was shown that, in the organic EL elements 2-7 to 2-11 according to the present invention, the acceleration coefficient can be lowered while maintaining a practical value for the organic EL elements 2-7 to 2-11 according to the present invention.
　≪実施例３≫
　［有機ＥＬ素子３－１～３－１６の作製］
　（基材の準備）
　まず、ポリエチレンナフタレートフィルム（以下、ＰＥＮと略記する。）（帝人デュポンフィルム株式会社製）の陽極を形成する側の全面に、特開２００４－６８１４３号公報に記載の構成の大気圧プラズマ放電処理装置を用いて、ＳｉＯｘからなる無機物のガスバリアー層を層厚５００ｎｍとなるように形成した。これにより、酸素透過度０．００１ｍＬ／（ｍ２・２４ｈ）以下、水蒸気透過度０．００１ｇ／（ｍ２・２４ｈ）以下のガスバリアー性を有する可撓性の基材を作製した。 Example 3
[Production of Organic EL Elements 3-1 to 3-16]
(Preparation of base material)
First, an atmospheric pressure plasma discharge treatment having a configuration described in Japanese Patent Application Laid-Open No. 2004-68143 is formed on the entire surface of a polyethylene naphthalate film (hereinafter abbreviated as PEN) (manufactured by Teijin DuPont Films Ltd.) on the anode forming side. Using an apparatus, an inorganic gas barrier layer made of SiOx was formed to a thickness of 500 nm. Thus, a flexible base material having a gas barrier property with an oxygen permeability of 0.001 mL / (m 2 · 24 h) or less and a water vapor permeability of 0.001 g / (m 2 · 24 h) or less was produced.
　（陽極の形成）
　上記基材上に厚さ１２０ｎｍのＩＴＯ（インジウム・スズ酸化物）をスパッタ法により製膜し、フォトリソグラフィー法によりパターニングを行い、陽極を形成した。なお、パターンは発光領域の面積が５ｃｍ×５ｃｍになるようなパターンとした。 (Formation of anode)
An ITO (indium tin oxide) film having a thickness of 120 nm was formed on the substrate by sputtering, and patterned by photolithography to form an anode. The pattern was such that the area of the light emitting region was 5 cm × 5 cm.
　（正孔注入層の形成）
　陽極を形成した基材をイソプロピルアルコールで超音波洗浄し、乾燥窒素ガスで乾燥し、ＵＶオゾン洗浄を５分間行った。そして、陽極を形成した基材上に、特許第４５０９７８７号公報の実施例１６と同様に調製したポリ（３，４－エチレンジオキシチオフェン）／ポリスチレンスルホネート（ＰＥＤＯＴ／ＰＳＳ）の分散液をイソプロピルアルコールで希釈した２質量％溶液をダイコート法にて塗布、自然乾燥し、層厚３０ｎｍの正孔注入層を形成した。 (Formation of hole injection layer)
The substrate on which the anode was formed was subjected to ultrasonic cleaning with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes. Then, a dispersion of poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT / PSS) prepared in the same manner as in Example 16 of Japanese Patent No. 4509787 was placed on the substrate on which the anode was formed. The 2% by weight solution diluted in (1) was applied by a die coating method and dried naturally to form a hole injection layer having a layer thickness of 30 nm.
　（正孔輸送層の形成）
　次に、正孔注入層を形成した基材を、窒素ガス（グレードＧ１）を用いた窒素雰囲気下に移し、下記組成の正孔輸送層形成用塗布液を用いて、ダイコート法にて５ｍ／ｍｉｎで塗布、自然乾燥した後に、１３０℃で３０分間保持し、厚さ３０ｎｍの正孔輸送層を形成した。 (Formation of hole transport layer)
Next, the base material on which the hole injection layer was formed was transferred to a nitrogen atmosphere using nitrogen gas (grade G1), and a coating liquid for forming a hole transport layer having the following composition was used to form a 5 m / After being applied for min and air-dried, it was kept at 130 ° C. for 30 minutes to form a 30 nm-thick hole transport layer.
　〈正孔輸送層形成用塗布液〉
　正孔輸送材料　ＨＴ－３（重量平均分子量Ｍｗ＝８００００）
　　　　　　　　　　　　　　　　　　　　　　　　　　　　１０質量部
　クロロベンゼン　　　　　　　　　　　　　　　　　　３０００質量部 <Coating liquid for hole transport layer formation>
Hole transport material HT-3 (weight average molecular weight Mw = 80000)
10 parts by mass Chlorobenzene 3000 parts by mass
　（発光層の形成）
　次に、正孔輸送層を形成した基材を、下記の組成の発光層形成用塗布液を用い、ダイコート法にて５ｍ／ｍｉｎの塗布速度で塗布し、自然乾燥した後に、１２０℃で３０分間保持し、厚さ５０ｎｍの発光層を形成した。
　なお、以下において、ｘは表IVに記した蛍光発光性化合物の濃度である。 (Formation of light emitting layer)
Next, the base material on which the hole transport layer was formed was applied at a coating speed of 5 m / min by a die coating method using a coating solution for forming a light emitting layer having the following composition, and naturally dried, and then 30 ° C. at 30 ° C. Holding for 5 minutes, a light emitting layer having a thickness of 50 nm was formed.
In the following, x is the concentration of the fluorescent compound shown in Table IV.
　〈発光層形成用塗布液〉
　ホスト化合物　Ｈ－２　　　　　　　　　　　　　　８．５－ｘ質量部
　リン光発光性化合物ＰＤ－１　　　　　　　　　　　　　１．５質量部
　表IVに示す蛍光発光性化合物　　　　　　　　　　　　　　　ｘ質量部
　酢酸イソプロピル　　　　　　　　　　　　　　　　　２０００質量部 <Light emitting layer forming coating solution>
Host compound H-2 8.5-part by mass Phosphorescent compound PD-1 1.5 parts by mass Fluorescent compound shown in Table IV x parts by mass Isopropyl acetate 2000 parts by mass
　（正孔阻止層の形成）
　次に、発光層を形成した基材を、下記組成の正孔阻止層形成用塗布液を用い、ダイコート法にて５ｍ／ｍｉｎの塗布速度で塗布し、自然乾燥した後に、８０℃で３０分間保持し、層厚１０ｎｍの正孔阻止層を形成した。 (Formation of hole blocking layer)
Next, the base material on which the light-emitting layer is formed is applied at a coating speed of 5 m / min by a die coating method using a coating solution for forming a hole blocking layer having the following composition, and is naturally dried, and then at 80 ° C. for 30 minutes. The hole blocking layer having a thickness of 10 nm was formed.
　〈正孔阻止層形成用塗布液〉
　ＨＢ－４　　　　　　　　　　　　　　　　　　　　　　　　２質量部
　イソプロピルアルコール（ＩＰＡ）　　　　　　　　　１５００質量部
　１Ｈ，１Ｈ，５Ｈ－オクタフルオロペンタノール（ＯＦＡＯ）
　　　　　　　　　　　　　　　　　　　　　　　　　　　５００質量部 <Hole blocking layer forming coating solution>
HB-4 2 parts by mass Isopropyl alcohol (IPA) 1500 parts by mass 1H, 1H, 5H-octafluoropentanol (OFAO)
500 parts by weight
　（電子輸送層の形成）
　次に、正孔阻止層を形成した基材を、下記組成の電子輸送層形成用塗布液を用い、ダイコート法にて５ｍ／ｍｉｎの塗布速度で塗布し、自然乾燥した後に、８０℃で３０分間保持し、厚さ３０ｎｍの電子輸送層を形成した。 (Formation of electron transport layer)
Next, the base material on which the hole blocking layer was formed was applied at a coating speed of 5 m / min by a die coating method using a coating liquid for forming an electron transport layer having the following composition, naturally dried, and then 30 ° C. at 30 ° C. Holding for 30 minutes, an electron transport layer having a thickness of 30 nm was formed.
　〈電子輸送層形成用塗布液〉
　ＥＴ－１　　　　　　　　　　　　　　　　　　　　　　　　６質量部
　１Ｈ，１Ｈ，３Ｈ－テトラフルオロプロパノール（ＴＦＰＯ）
　　　　　　　　　　　　　　　　　　　　　　　　　　２０００質量部 <Coating liquid for electron transport layer formation>
ET-1 6 parts by mass 1H, 1H, 3H-tetrafluoropropanol (TFPO)
2000 parts by mass
　（電子注入層、陰極の形成）
　次に、基板を大気に曝露することなく真空蒸着装置へ取り付けた。また、モリブデン製抵抗加熱ボートにフッ化ナトリウム及びフッ化カリウムを入れたものを真空蒸着装置に取り付け、真空槽を４×１０－５Ｐａまで減圧した。その後、ボートに通電して加熱し、フッ化ナトリウムを０．０２ｎｍ／秒で前記電子輸送層上に蒸着し、膜厚１ｎｍの薄膜を形成した。同様に、フッ化カリウムを０．０２ｎｍ／秒でフッ化ナトリウム薄膜上に蒸着し、厚さ１．５ｎｍの電子注入層を形成した。 (Formation of electron injection layer and cathode)
Next, the substrate was attached to a vacuum deposition apparatus without being exposed to the atmosphere. Further, a molybdenum resistance heating boat containing sodium fluoride and potassium fluoride was attached to a vacuum vapor deposition apparatus, and the vacuum chamber was depressurized to 4 × 10 −5 Pa. Thereafter, the boat was energized and heated, and sodium fluoride was deposited on the electron transport layer at 0.02 nm / second to form a thin film having a thickness of 1 nm. Similarly, potassium fluoride was deposited on the sodium fluoride thin film at 0.02 nm / second to form an electron injection layer having a thickness of 1.5 nm.
　（陰極の形成）
　引き続き、アルミニウムを蒸着して厚さ１００ｎｍの陰極を形成した。 (Formation of cathode)
Subsequently, aluminum was deposited to form a cathode having a thickness of 100 nm.
　（封止）
　以上の工程により形成した積層体に対し、市販のロールラミネート装置を用いて封止基材を接着した。 (Sealing)
The sealing base material was adhere | attached on the laminated body formed by the above process using the commercially available roll laminating apparatus.
　封止基材として、可撓性を有する厚さ３０μｍのアルミニウム箔（東洋アルミニウム（株）製）に、ドライラミネーション用の２液反応型のウレタン系接着剤を用いて層厚１．５μｍの接着剤層を設け、厚さ１２μｍのポリエチレンテレフタレート（ＰＥＴ）フィルムをラミネートしたものを作製した。 Adhesion as a sealing substrate with a thickness of 1.5 μm using a flexible aluminum foil (manufactured by Toyo Aluminum Co., Ltd.) with a thickness of 30 μm using a two-component reaction type urethane adhesive for dry lamination. An agent layer was provided, and a laminate of a polyethylene terephthalate (PET) film having a thickness of 12 μm was prepared.
　封止用接着剤として熱硬化性接着剤を、ディスペンサーを使用して封止基材のアルミニウム箔の接着面（つや面）に沿って厚さ２０μｍで均一に塗布した。これを１００Ｐａ以下の真空下で１２時間乾燥させた。更に、その封止基材を露点温度－８０℃以下、酸素濃度０．８ｐｐｍの窒素雰囲気下へ移動して、１２時間以上乾燥させ、封止用接着剤の含水率が１００ｐｐｍ以下となるように調整した。 A thermosetting adhesive as a sealing adhesive was uniformly applied at a thickness of 20 μm along the adhesive surface (shiny surface) of the aluminum foil of the sealing substrate using a dispenser. This was dried under a vacuum of 100 Pa or less for 12 hours. Further, the sealing substrate is moved to a nitrogen atmosphere having a dew point temperature of −80 ° C. or less and an oxygen concentration of 0.8 ppm, and is dried for 12 hours or more so that the moisture content of the sealing adhesive is 100 ppm or less. It was adjusted.
　熱硬化性接着剤としては下記の（Ａ）～（Ｃ）を混合したエポキシ系接着剤を用いた。 As the thermosetting adhesive, an epoxy adhesive mixed with the following (A) to (C) was used.
　（Ａ）ビスフェノールＡジグリシジルエーテル（ＤＧＥＢＡ）
　（Ｂ）ジシアンジアミド（ＤＩＣＹ）
　（Ｃ）エポキシアダクト系硬化促進剤 (A) Bisphenol A diglycidyl ether (DGEBA)
(B) Dicyandiamide (DICY)
(C) Epoxy adduct curing accelerator
　上記封止基材を上記積層体に対して密着・配置して、圧着ロールを用いて、圧着ロール温度１００℃、圧力０．５ＭＰａ、装置速度０．３ｍ／ｍｉｎの圧着条件で密着封止した。 The sealing substrate was closely attached to the laminate, and was tightly sealed using a pressure-bonding roll under pressure-bonding conditions of a pressure-rolling roll temperature of 100 ° C., a pressure of 0.5 MPa, and an apparatus speed of 0.3 m / min. .
　実施例１及び実施例２と同様にして、発光減衰寿命τ及びτ0並びに絶対量子収率ＰＬＱＥ（φ）及び絶対量子収率ＰＬＱＥ（φ0）を測定した。この結果、有機ＥＬ素子３－２～３－１６はいずれも（１）及び（２）式を満たし、かつ、（３）又は（４）式を満たすものであった。
　なお、測定に用いた評価用発光性膜は、実施例１における「ホスト化合物」、「リン光発光性化合物」及び「蛍光発光性化合物」の種類並びに各化合物の含有量（体積％）を、それぞれ、有機ＥＬ素子３－１～３－１６に対応する含有量（質量％）となるように変更したほかは、実施例１と同様にして製造した。また、リン光発光性化合物の単膜は、当該評価用発光性膜の製造において、蛍光発光性化合物を含有させないほかは同様にして、リン光発光性化合物ＰＤ－１とホスト化合物Ｈ－２からなる単膜を製造した。なお、当該リン光発光性化合物の単膜の製造においては、リン光発光性化合物の含有量は変えず、蛍光発光性化合物を含有させなかった分、ホスト化合物を増やして製造した。 In the same manner as in Example 1 and Example 2, the emission decay lifetimes τ and τ 0 , the absolute quantum yield PLQE (φ), and the absolute quantum yield PLQE (φ 0 ) were measured. As a result, all of the organic EL elements 3-2 to 3-16 satisfied the expressions (1) and (2) and also satisfied the expression (3) or (4).
In addition, the light emitting film for evaluation used for the measurement is the type of “host compound”, “phosphorescent light emitting compound” and “fluorescent light emitting compound” in Example 1, and the content (volume%) of each compound. Each was produced in the same manner as in Example 1 except that the content (mass%) was changed to correspond to each of the organic EL elements 3-1 to 3-16. In addition, the phosphorescent compound single film is formed from the phosphorescent compound PD-1 and the host compound H-2 in the same manner except that the fluorescent compound is not included in the production of the evaluation light emitting film. A single membrane was produced. In the production of a single film of the phosphorescent compound, the content of the phosphorescent compound was not changed, and the host compound was increased by the amount not containing the fluorescent compound.
　また、実施例１と同様に、リン光発光性化合物の発光スペクトルと蛍光発光性化合物の吸収スペクトルとの重なりの有無及び蛍光発光性化合物のストークスシフトを調べたところ、有機ＥＬ素子３－２～３－１６については、いずれもリン光発光性化合物の発光スペクトルと蛍光発光性化合物の吸収スペクトルとが重なりを有し、かつ、蛍光発光性化合物のストークスシフトが０．１ｅＶ以下であることが確認された。 Further, as in Example 1, the presence or absence of overlap between the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound and the Stokes shift of the fluorescent compound were examined. As for 3-16, it is confirmed that the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound overlap each other, and the Stokes shift of the fluorescent compound is 0.1 eV or less. It was done.
Figure JPOXMLDOC01-appb-T000055
Figure JPOXMLDOC01-appb-T000055
　（まとめ）
　表IVからわかるように、光発光性化合物の含有量が、発光層に含まれる化合物の総量を１００質量％としたとき、５質量％以下であれば、ＥＱＥ（相対値）を維持しつつ、加速係数を良好にできることが示された。さらには、０．９質量％以下であれば、ＥＱＥは、０．９以上となり、ＥＱＥ（相対値）をより高く維持できつつ、加速係数を良好にできることが示された。
　なお、ＥＱＥ及び加速係数ｎは、実施例１、２と同様にして求めた。 (Summary)
As can be seen from Table IV, when the content of the photoluminescent compound is 5% by mass or less when the total amount of the compounds contained in the light emitting layer is 100% by mass, while maintaining EQE (relative value), It was shown that the acceleration factor can be improved. Furthermore, if it is 0.9 mass% or less, EQE will be 0.9 or more, and it has been shown that the EQE (relative value) can be maintained higher and the acceleration coefficient can be improved.
The EQE and the acceleration coefficient n were obtained in the same manner as in Examples 1 and 2.
　本発明は、有機エレクトロルミネッセンス素子及び有機エレクトロルミネッセンス素子の製造方法に利用することができる。 The present invention can be used for an organic electroluminescence element and a method for producing an organic electroluminescence element.
　１　ディスプレイ
　３　画素
　５　走査線
　６　データ線
　１０１　有機ＥＬ素子
　１０２　ガラスカバー
　１０５　陰極
　１０６　有機ＥＬ層（発光ユニット）
　１０７　透明電極付きガラス基板
　１０８　窒素ガス
　１０９　捕水剤
　Ａ　表示部
　Ｂ　制御部 DESCRIPTION OF SYMBOLS 1 Display 3 Pixel 5 Scan line 6 Data line 101 Organic EL element 102 Glass cover 105 Cathode 106 Organic EL layer (light emitting unit)
107 Glass substrate with transparent electrode 108 Nitrogen gas 109 Water trapping agent A Display unit B Control unit

Claims (6)

  1. 　発光層を有する有機エレクトロルミネッセンス素子であって、
    　前記発光層が、リン光発光性化合物及び蛍光発光性化合物を含有し、
    　前記リン光発光性化合物の発光スペクトルと前記蛍光発光性化合物の吸収スペクトルとが重なりを有しており、
    　前記発光層単層の発光減衰寿命τが、下記（１）式を満たし、
    　前記発光層単層の絶対量子収率ＰＬＱＥφが、下記（２）式を満たし、
    　前記蛍光発光性化合物のストークスシフトが、０．１ｅＶ以下である有機エレクトロルミネッセンス素子。
    　　０＜τ／τ0≦０．７・・・（１）
    　　０．６≦φ／φ0≦１．０・・・（２）
    ［τ：前記発光層単層の発光減衰寿命
    　τ0：前記リン光発光性化合物の単膜の発光減衰寿命
    　φ：前記発光層単層の絶対量子収率ＰＬＱＥ
    　φ0：前記リン光発光性化合物の単膜の絶対量子収率ＰＬＱＥ］     An organic electroluminescence device having a light emitting layer,
    The light emitting layer contains a phosphorescent compound and a fluorescent compound,
    The emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound have an overlap,
    The light emission decay lifetime τ of the light emitting layer satisfies the following formula (1):
    The absolute quantum yield PLQEφ of the light emitting layer single layer satisfies the following formula (2):
    The organic electroluminescent element whose Stokes shift of the said fluorescent compound is 0.1 eV or less.
    0 <τ / τ 0 ≦ 0.7 (1)
    0.6 ≦ φ / φ 0 ≦ 1.0 (2)
    [Τ: emission decay lifetime of the single layer of the light emitting layer τ 0 : emission decay lifetime of the single layer of the phosphorescent compound φ: absolute quantum yield PLQE of the single layer of the light emitting layer
    φ 0 : absolute quantum yield PLQE of the phosphorescent compound single film]
  2. 　前記リン光発光性化合物と前記蛍光発光性化合物とが、下記（３）式又は下記（４）式を満たす請求項１に記載の有機エレクトロルミネッセンス素子。
    　ＨＯＭＯ（Ｆ）≦ＨＯＭＯ（Ｐ）・・・（３）
    　ＬＵＭＯ（Ｐ）≦ＬＵＭＯ（Ｆ）・・・（４）
    ［ＨＯＭＯ（Ｐ）、ＬＵＭＯ（Ｐ）：それぞれ、前記リン光発光性化合物の最高被占分子軌道（ＨＯＭＯ）と最低空分子軌道（ＬＵＭＯ）のエネルギー準位
    　ＨＯＭＯ（Ｆ）、ＬＵＭＯ（Ｆ）：それぞれ、前記蛍光発光性化合物の最高被占分子軌道（ＨＯＭＯ）と前記蛍光発光性化合物の最低空分子軌道（ＬＵＭＯ）のエネルギー準位］     The organic electroluminescent element according to claim 1, wherein the phosphorescent compound and the fluorescent compound satisfy the following formula (3) or the following formula (4).
    HOMO (F) ≦ HOMO (P) (3)
    LUMO (P) ≦ LUMO (F) (4)
    [HOMO (P), LUMO (P): energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the phosphorescent compound HOMO (F) and LUMO (F), respectively: The energy levels of the highest occupied molecular orbital (HOMO) of the fluorescent compound and the lowest unoccupied molecular orbital (LUMO) of the fluorescent compound, respectively.
  3. 　前記発光層に含まれる化合物の総量を１００質量％としたとき、前記蛍光発光性化合物の含有量（質量％）が、前記リン光発光性化合物の含有量（質量％）より少ない請求項１又は請求項２に記載の有機エレクトロルミネッセンス素子。 The content (% by mass) of the fluorescent compound is less than the content (% by mass) of the phosphorescent compound when the total amount of the compounds contained in the light emitting layer is 100% by mass. The organic electroluminescent element according to claim 2.
  4. 　前記発光層に含まれる化合物の総量を１００質量％としたとき、前記蛍光発光性化合物の含有量が、５質量％以下である請求項１から請求項３までのいずれか一項に記載の有機エレクトロルミネッセンス素子。 The organic according to any one of claims 1 to 3, wherein when the total amount of compounds contained in the light emitting layer is 100% by mass, the content of the fluorescent compound is 5% by mass or less. Electroluminescence element.
  5. 　請求項１から請求項４までのいずれか一項に記載の有機エレクトロルミネッセンス素子を製造する有機エレクトロルミネッセンス素子の製造方法であって、
    　前記発光層を、ドライプロセスで製造する有機エレクトロルミネッセンス素子の製造方法。     It is a manufacturing method of the organic electroluminescent element which manufactures the organic electroluminescent element as described in any one of Claim 1- Claim 4,
    The manufacturing method of the organic electroluminescent element which manufactures the said light emitting layer with a dry process.
  6. 　請求項１から請求項４までのいずれか一項に記載の有機エレクトロルミネッセンス素子を製造する有機エレクトロルミネッセンス素子の製造方法であって、
    　前記発光層を、ウェットプロセスで製造する有機エレクトロルミネッセンス素子の製造方法。     It is a manufacturing method of the organic electroluminescent element which manufactures the organic electroluminescent element as described in any one of Claim 1- Claim 4,
    The manufacturing method of the organic electroluminescent element which manufactures the said light emitting layer with a wet process.
PCT/JP2018/008977 2017-04-07 2018-03-08 Organic electroluminescence element and method for manufacturing organic electroluminescence element WO2018186101A1 (en)

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