WO2016194865A1 - Organic electroluminescent element - Google Patents

Organic electroluminescent element Download PDF

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WO2016194865A1
WO2016194865A1 PCT/JP2016/065878 JP2016065878W WO2016194865A1 WO 2016194865 A1 WO2016194865 A1 WO 2016194865A1 JP 2016065878 W JP2016065878 W JP 2016065878W WO 2016194865 A1 WO2016194865 A1 WO 2016194865A1
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group
layer
organic
dopant
light
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PCT/JP2016/065878
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French (fr)
Japanese (ja)
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井上　暁
昇 関根
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コニカミノルタ株式会社
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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
    • 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

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  • the present invention relates to an organic electroluminescence element.
  • the present invention relates to an organic electroluminescence device having excellent stability in the excited state of a host compound and a dopant and having an improved device driving life.
  • an organic EL element using a light emitting material that realizes high luminous efficiency by utilizing all of singlet excitons and triplet excitons for electroluminescence (hereinafter also referred to as EL) has been proposed.
  • EL organic EL element
  • a material in a practical range is developed with both high luminous efficiency and luminous lifetime, and is used for display and illumination.
  • TADF compounds have HOMO and LUMO by introducing an electron-donating and electron-withdrawing skeleton into the molecule to cause reverse intersystem crossing from the triplet state to the singlet state by thermal activation. Since it is necessary to separate the positions where the light is emitted, the charge transfer type light emission which is broad light emission is shown.
  • the lowest excited singlet of TADF compound as close an emission color to deep blue (S 1 ) (Hereinafter also simply referred to as “singlet (S 1 )”) Energy and lowest excited triplet (T 1 ) (hereinafter also simply referred to as “triplet (T 1 )”) energy needs to be increased.
  • the triplet energy of the host compound needs to be higher than the triplet energy of the dopant. In that case, since the dopant and the host compound remain in an unstable state having high energy, it is easy to generate a quenching substance by decomposition or the like. It was a problem to get.
  • Non-Patent Document 1 the energy transfer rate Kq increases exponentially, and there is a principle problem that quenching easily occurs. Therefore, a practical device lifetime is not obtained.
  • PL with Quencher
  • PL without Quencher
  • Kq the energy transfer rate from the emitting material to the quenching substance
  • Kd the rate of generation of the quencher by decomposition
  • t the cumulative excitation time by light or current
  • ⁇ is the phosphorescence lifetime of the luminescent material in the absence of the quencher.
  • the present invention has been made in view of the above problems and situations, and its solution is to provide an organic electroluminescent device having excellent stability in the excited state of a host compound and a dopant and having an improved device driving life. It is.
  • the light-emitting layer of the organic electroluminescence element is composed of a thermally activated delayed fluorescent light-emitting host compound and a phosphorescent light-emitting metal complex dopant
  • the singlet energy transfer efficiency of the host compound to the phosphorescent metal complex dopant is in the range of 10 to 100%, so that the host compound and the dopant are excellent in the excited state.
  • a pair of electrodes, and an organic electroluminescence device comprising an organic layer between the pair of electrodes,
  • the light-emitting layer contains a thermally activated delayed fluorescence host compound and a phosphorescent metal complex dopant
  • An organic electroluminescence device wherein a singlet energy transfer efficiency of the host compound to the phosphorescent metal complex dopant is within a range of 10 to 100%.
  • M represents Ir, Pt, Rh, Ru, Ag, Cu, or Os.
  • a 1 and A 2 each represent a carbon atom or a nitrogen atom.
  • Ring Z 1 represents A 1.
  • B 1 to B 5 are an atomic group forming a 5-membered aromatic heterocycle Represents a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom which may have a substituent, and ring Z 1 may have a substituent, and the substituents are further bonded to each other to form a condensed ring structure.
  • L represents a monoanionic bidentate ligand coordinated to M.
  • Each ligand coordinated to M is coordinated by bonding of substituents thereof to each other.
  • the children may be linked to each other, m represents an integer of 0 to 2, n represents an integer of 1 to 3, and m + n is 2 or 3. And when n is each of two or more, the ring Z 1, B 1 aromatic heterocyclic group and L represented by ⁇ B 5 may be different even each identical.
  • the organic electroluminescent element which was excellent in stability in the excitation state of a host compound and a dopant, and whose element drive lifetime improved can be provided.
  • the expression mechanism or action mechanism of the effect of the present invention is presumed as follows. When an organic electroluminescent device is driven by current, excitons in which holes and electrons are directly recombined on the phosphorescent metal complex dopant and excitons recombined on the host compound are generated, and the breakdown is as follows: The triplet state excitons are 75% and the singlet state excitons are 25%. As shown in FIG.
  • a singlet exciton recombined on a conventionally used host compound that is not a TADF compound allows an S 1 ⁇ S 0 transition, so that the Forster mechanism can quickly Or rapidly deactivates in the host molecule.
  • triplet excitons recombined on the host compound have a slow energy transfer rate due to the Forster mechanism due to the forbidden transition of T 1 ⁇ S 0 , and a slow energy transfer due to the Dexter mechanism based on electron exchange between adjacent molecules.
  • the deactivation rate in the host compound is as slow as several ⁇ s to several ms, it remains in an unstable excited state (triplet excited state) for a long time.
  • the host compound stays in an excited state having high excitation energy for a long time.
  • the rate at which the quenching substance is generated increases due to decomposition of the host compound and the like.
  • the present inventor generated a host compound using a TADF compound that crosses back from the triplet excited state to the singlet excited state and efficiently transfers energy to the dopant as the host compound.
  • the residence time in the triplet excited state is shortened, and excitons crossing back to back from the triplet to the singlet effectively transfer energy to the dopant, thereby retaining the triplet and singlet excited states on the host compound.
  • the organic electroluminescence device of the present invention is characterized in that the light-emitting layer contains a thermally activated delayed fluorescence host compound and a phosphorescent metal complex dopant.
  • Schematic explaining energy transfer of conventional host compound and phosphorescent metal complex dopant Schematic explaining energy transfer of thermally activated delayed fluorescence host compound and phosphorescent metal complex dopant according to the present invention
  • Schematic diagram showing an example of a display device composed of organic EL elements Schematic diagram of display section A in FIG. Schematic showing the pixel circuit
  • Schematic diagram of passive matrix type full color display device Schematic of lighting device
  • Schematic diagram of lighting device Schematic diagram of lighting device
  • the organic electroluminescence device of the present invention is an organic electroluminescence device in which an organic layer is provided between a pair of electrodes and the pair of electrodes, and the light emitting layer is a thermally activated delayed fluorescence host compound And a phosphorescent metal complex dopant, wherein the singlet energy transfer efficiency of the host compound to the phosphorescent metal complex dopant is in the range of 10 to 100%.
  • This feature is a technical feature common to or corresponding to the claims of claims 1 to 3.
  • the singlet energy transfer efficiency is preferably in the range of 90 to 100%.
  • the said phosphorescence-emitting metal complex dopant has a structure represented by the said General formula (1).
  • it since it has a 5-membered aromatic heterocyclic ring with ⁇ -excess, it has a higher HOMO level than a dopant with a 6-membered ring ligand with ⁇ -electron deficiency, and it tends to trap holes. It becomes difficult to generate singlet and triplet excited states, and generation of a quenching substance due to decomposition of the host compound or the like can be suppressed.
  • the fluorescence emission spectrum of the thermally activated delayed fluorescence emission host compound is the same as the absorption spectrum of the phosphorescence emission metal complex dopant and 1 ⁇ 10 14 nm 4 (mol / L) ⁇ 1 cm ⁇ . It is preferable to have one or more overlaps.
  • the singlet state Forster radius of the thermally activated delayed fluorescence host compound (the energy transfer rate from the thermally activated delayed fluorescence host compound to the phosphorescent metal complex dopant is The distance that is equal to the deactivation rate of the activated delayed fluorescence host compound itself) is increased, and the excitons that cross the back-to-back singlet from the triplet to the singlet effectively transfer energy to the dopant. Residence of the S 1 excited state on the host compound can be suppressed.
  • the singlet excited state energy of the thermally activated delayed fluorescence host compound is preferably lower than the minimum bond cleavage energy of the host compound, more preferably the singlet of the host compound. It is preferable that the term excited state energy is 0.2 eV or more lower than the minimum bond cleavage energy of the host compound. Thereby, the production
  • ⁇ 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 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 used in 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 used in 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. In the above-described typical element configuration, a layer excluding the anode and the cathode is referred to as an “organic layer”.
  • the organic EL element of the present invention may be a so-called tandem element in which a plurality of light emitting units including at least one light emitting layer are stacked.
  • a tandem element in which a plurality of light emitting units including at least one light emitting layer are stacked.
  • the first light emitting unit The second light emitting unit and the third light emitting unit may all be the same or different. Further, the two light emitting units may be the same, and the remaining one may be different.
  • the third light emitting unit may not be provided.
  • 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.
  • Known materials and structures can be used as long as they are also called insulating layers and have a function of supplying electrons to the anode-side adjacent layer and holes to the cathode-side adjacent layer.
  • Examples of materials used for the intermediate layer include ITO (indium tin oxide), IZO (indium zinc oxide), ZnO 2 , TiN, ZrN, HfN, TiOx, VOx, CuI, InN, GaN, and CuAlO 2.
  • Preferred examples of the structure within the light emitting unit include those obtained by removing the anode and the cathode from the structures (1) to (7) mentioned in the above representative element structures, but the present invention is not limited to these.
  • 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.
  • the organic EL device of the present invention is an organic electroluminescence device in which an organic layer is provided between a pair of electrodes and the pair of electrodes, and the light emitting layer has a thermally activated delayed fluorescence emission property.
  • the organic layer according to the present invention has a light emitting layer.
  • the light emitting layer according to the present invention is a layer that provides a field in which electrons and holes injected from an electrode or an adjacent layer are recombined to emit light via excitons, and the light emitting portion is a layer of the light emitting layer. Even within, it may be the interface between the light emitting layer and the adjacent layer.
  • the structure of the light emitting layer according to the present invention is not particularly limited as long as it satisfies the requirements defined in the present invention.
  • the total thickness of the light emitting layer is not particularly limited, but it is possible to prevent the homogeneity of the layer to be formed, the application of unnecessary high voltage during light emission, and the improvement of the stability of the emission color against the driving current. Therefore, it is preferably adjusted to a range of 2 nm to 5 ⁇ m, more preferably adjusted to a range of 2 to 500 nm, and further preferably adjusted to a range of 5 to 200 nm.
  • the thickness of each light emitting layer is preferably adjusted to a range of 2 nm to 1 ⁇ m, more preferably adjusted to a range of 2 to 200 nm, and further preferably adjusted to a range of 3 to 150 nm.
  • the light-emitting layer according to the present invention contains a light-emitting dopant (a light-emitting dopant compound, a dopant compound, also simply referred to as a dopant) and a host compound (a matrix material, a light-emitting host compound, also simply referred to as a host). preferable.
  • a light-emitting dopant a light-emitting dopant compound, a dopant compound, also simply referred to as a dopant
  • a host compound a matrix material, a light-emitting host compound, also simply referred to as a host.
  • the host compound used in the light emitting layer is a compound mainly responsible for charge injection and transport in the light emitting layer, and the light emission itself is not substantially observed in the organic EL element.
  • it is a compound having a phosphorescence quantum yield of phosphorescence of less than 0.1 at room temperature (25 ° C.), more preferably a compound having a phosphorescence quantum yield of less than 0.01.
  • the mass ratio in the layer is 20% or more among the compounds contained in a light emitting layer.
  • the triplet excited state energy of the host compound is preferably higher than the triplet excited state energy of the light-emitting dopant contained in the same layer.
  • the host compounds may be used alone or in combination of two or more. 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.
  • TADF host compound a heat-activated delayed fluorescence host compound
  • thermally activated Delayed Fluorescent Host Compound As the thermally activated delayed fluorescent luminescent host compound contained in the light emitting layer according to the present invention, a thermally activated delayed fluorescent luminescent compound (TADF compounds) are used.
  • TADF compounds thermally activated delayed fluorescent luminescent compound
  • the difference ⁇ Est between the singlet excitation energy level and the triplet excitation energy level is small, a reverse intersystem crossing from the triplet excited state to the singlet excited state, which cannot normally occur, occurs.
  • the TADF host compound that can be used in the present invention is a compound that has a triplet energy higher than the triplet energy of the light-emitting dopant and does not quench the light emission of the light-emitting dopant, as is generally known. It can be used suitably.
  • the molecular design for reducing the ⁇ Est of the thermally activated delayed fluorescent compound will be described.
  • it is most effective to reduce the spatial overlap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) in the molecule. Is.
  • HOMO is distributed in electron donating sites and LUMO is distributed in electron withdrawing sites in the electron orbit of the molecule.
  • LUMO is distributed in electron withdrawing sites in the electron orbit of the molecule.
  • site of the electron donating moiety and the electron withdrawing moiety refers to a substituent or a group of atoms.
  • Examples of the electron donating moiety include rings such as arylamines, carbazole, phenoxazine, acridine, phenothiazine and pyrroles.
  • Examples of the electron-withdrawing moiety include a nitrogen-containing aromatic heterocycle, an aromatic ring substituted with an electron-withdrawing group such as a cyano group or a sulfonyl group.
  • the absolute value of ⁇ Est S 1 -T 1 is preferably 1.0 eV or less, more preferably 0.5 eV or less.
  • the value of ⁇ Est is directly related to the speed of the crossing between inverse terms from the triplet excited state to the singlet excited state.
  • Preferred examples of the TADF compound used as the TADF host compound according to the present invention are exemplified below, but the present invention is not limited thereto.
  • Bond Dissociation Energy in the ground state is described in J. Org. Am. Chem. C, 2014, 118, pp 7569-7578.
  • the bond cleavage energy in the present invention refers to the minimum energy obtained as a result of calculation by the method of the literature for each bond of a compound.
  • the S 1 energy of the TADF host compound is lower than the bond cleavage energy in the ground state, the cleavage reaction becomes endothermic in the singlet excited state, so that generation of a quenching substance can be suppressed.
  • the light emitting layer according to the present invention may further contain other host compounds in addition to the above TADF host compound.
  • the other host compound according to the present invention is a compound mainly responsible for charge injection and transport in the light emitting layer, and its own light emission is not substantially observed in the organic EL element. Moreover, it is preferable that the volume ratio in the layer is 50% or less among the compounds contained in the light emitting layer which concerns on this invention. Further, as other host compounds, those having triplet excitation energy larger than the lowest excitation triplet energy of the TADF host compound are preferable. When the volume ratio is 50% or less and is higher than the lowest excited triplet energy of the TADF host compound, electron-hole recombination occurs on other host compounds, even when triplet excited states are formed. This is because there is a high probability that the TADF host compound exists, and the energy is transferred to the TADF host compound by the Dexter mechanism and then converted into singlet excitons.
  • Other host compounds may be used in combination. By using a plurality of other host compounds, the movement of charges can be adjusted, and the efficiency of the organic EL element can be increased.
  • As other host compounds while having hole transporting ability or electron transporting ability, the emission of light is prevented from being increased in wavelength, and the organic EL element is stable against heat generation during driving at high temperature or during 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 Colorimetry).
  • Luminescent dopant As the luminescent dopant used in the present invention, a phosphorescent metal complex dopant (also referred to as a phosphorescent dopant or a phosphorescent dopant) is used. In the present invention, it is particularly preferable to use a phosphorescent metal complex dopant represented by the following general formula (1).
  • the concentration of the luminescent dopant in the luminescent layer can be arbitrarily determined based on the specific dopant used and the requirements of the device, and is contained at a uniform concentration in the thickness direction of the luminescent layer. It may also have an arbitrary concentration distribution.
  • the luminescent dopant used for this invention may be used in combination with multiple types of a phosphorescent metal complex dopant, and may be used in combination with a fluorescent luminescent dopant. Thereby, arbitrary luminescent colors can be obtained.
  • the light emission color of the organic EL device of the present invention and the compound used in the present invention is shown in FIG. 5.16 on page 108 of “New Color Science Handbook” (Edited by the Japan Color Society, University of Tokyo Press, 1985). It is determined by the color when the result measured with the luminance meter CS-1000 (manufactured by Konica Minolta Co., Ltd.) is applied to the CIE chromaticity coordinates.
  • the light emitting layer of one layer or a plurality of layers contains a plurality of light emitting dopants having different emission colors and emits white light.
  • the combination of the light-emitting dopants that exhibit white and examples include blue and orange, and a combination of blue, green, and red.
  • the white color in the organic EL device of the present invention is not particularly limited, and may be white near orange or white near blue.
  • the phosphorescent dopant according to the present invention is a compound in which light emission from an excited triplet is observed, specifically, a compound that emits phosphorescence at room temperature (25 ° C.).
  • the phosphorescence quantum yield is defined as a compound of 0.01 or more at 25 ° C., but the preferred phosphorescence quantum yield is 0.1 or more.
  • the phosphorescence quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence dopant according to the present invention achieves the phosphorescence quantum yield (0.01 or more) in any solvent. It ’s fine.
  • phosphorescent dopants There are two types of light emission of phosphorescent dopants in principle. One is the recombination of carriers on the host compound to which carriers are transported to generate an excited state of the host compound, and this energy is transferred to the phosphorescent dopant. It is an energy transfer type to obtain light emission from the phosphorescent dopant. The other is a carrier trap type in which a phosphorescent dopant serves as a carrier trap, and carrier recombination occurs on the phosphorescent dopant to emit light from the phosphorescent dopant. In any case, it is a condition that the excited state energy of the phosphorescent dopant is lower than the excited state energy of the host compound. As a phosphorescence dopant which can be used in this invention, it can select from the well-known thing used for the light emitting layer of an organic EL element suitably, and can use it.
  • phosphorescent dopants that can be used in the present invention include compounds described in the following documents. 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 Application Publication No. 2006/835469, US Patent Application Publication No. 2006. No. 0202194, U.S. Patent Application Publication No. 2007/0087321, U.S. Patent Application Publication No. 2005/0244673, Inorg. Chem.
  • a preferable phosphorescent dopant includes an organometallic complex having Ir as a central metal. More preferably, a complex containing at least one coordination mode among metal-carbon bond, metal-nitrogen bond, metal-oxygen bond and metal-sulfur bond is preferable.
  • the phosphorescent metal complex dopant contained in the light emitting layer according to the present invention is preferably a phosphorescent metal complex dopant represented by the following general formula (1). That is, compared to the structure in which the ring coordinated to the central metal is an electron-deficient nitrogen-containing aromatic heterocycle such as pyridine and pyrimidine, electron donation of imidazole, pyrazole, triazole, etc. as shown in general formula (1) It is considered that the structure which is a natural nitrogen-containing aromatic heterocycle has a higher HOMO level, so that it is more likely to be a carrier trap, an excited state of the host compound is not easily generated, and more effective.
  • general formula (1) That is, compared to the structure in which the ring coordinated to the central metal is an electron-deficient nitrogen-containing aromatic heterocycle such as pyridine and pyrimidine, electron donation of imidazole, pyrazole, triazole, etc.
  • M represents Ir, Pt, Rh, Ru, Ag, Cu, or Os.
  • a 1 and A 2 each represent a carbon atom or a nitrogen atom.
  • Ring Z 1 represents a 6-membered aromatic hydrocarbon ring or 5-membered or 6-membered aromatic heterocycle formed together with A 1 and A 2 .
  • B 1 to B 5 are a group of atoms that form a 5-membered aromatic heterocyclic ring, and represent a carbon atom, nitrogen atom, oxygen atom or sulfur atom which may have a substituent.
  • Ring Z 1 may have a substituent, and the substituents may be bonded to each other to form a condensed ring structure.
  • L represents a monoanionic bidentate ligand coordinated to M.
  • Each of the ligands coordinated to M may have their substituents bonded to each other and linked together.
  • m represents an integer of 0 to 2
  • n represents an integer of 1 to 3
  • m + n is 2 or 3.
  • the aromatic heterocyclic groups represented by the rings Z 1 and B 1 to B 5 and L may be the same or different.
  • examples of the 6-membered aromatic hydrocarbon ring or 5-membered or 6-membered aromatic heterocycle formed by the ring Z 1 include a benzene ring, a pyridine ring, a pyrimidine ring, a pyrrole ring, Examples include a thiophene ring, a pyrazole ring, an imidazole ring, an oxazole ring, and a thiazole ring. Of these, a benzene ring is preferred.
  • Ring Z 1 may have a substituent, and the substituents may be bonded to each other to form a condensed ring structure.
  • examples of the substituent that the ring Z 1 may have include, for example, an alkyl group (eg, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group).
  • an alkyl group eg, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group.
  • cycloalkyl group eg cyclopentyl group, cyclohexyl group etc.
  • alkenyl group eg vinyl group, allyl group etc.
  • alkynyl group eg Ethynyl group, propargyl group, etc.
  • aromatic hydrocarbon ring group also called aromatic carbocyclic group, aryl group, etc.
  • phenyl group, p-chlorophenyl group mesityl group, tolyl group, xylyl group, naphthyl group, Anthryl, azulenyl, acenaphthenyl, fluorenyl, phenanthryl, indenyl, pyreth Nyl group, biphenylyl group, etc.
  • aromatic heterocyclic group for example, pyr
  • B 1 to B 5 each represent a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom, and preferably at least one represents a nitrogen atom.
  • a monocyclic ring is preferable as the aromatic nitrogen-containing heterocycle formed by these five atoms. Examples include pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, oxadiazole ring, and thiadiazole ring.
  • a pyrazole ring and an imidazole ring are preferable, and an imidazole ring in which B 2 and B 5 are nitrogen atoms is particularly preferable. These rings may be further substituted with the substituent which ring Z 1 may have.
  • substituents that the aromatic heterocyclic ring represented by B 1 to B 5 may have are an alkyl group and an aryl group, and more preferably an aryl group.
  • specific examples of the monoanionic bidentate ligand represented by L include, for example, substituted or unsubstituted phenylpyridine, phenylpyrazole, phenylimidazole, phenyltriazole, phenyltetrazole, and pyrazabol. And picolinic acid and acetylacetone. These groups may be further substituted with the substituent which ring Z 1 may have.
  • n represents an integer of 1 to 3
  • m + n is 2 or 3, but m is preferably 0.
  • M represents Ir, Pt, Rh, Ru, Ag, Cu or Os. Among them, iridium and platinum are preferable, and iridium is more preferable.
  • the phosphorescent metal complex dopant contained in the light emitting layer according to the present invention has an emission maximum wavelength of 465 nm (2.67 eV) or less. Is preferred.
  • the phosphorescent metal complex dopants preferably used in the present invention are shown below, but are not limited thereto. .
  • the emission maximum wavelengths (nm) of these phosphorescent metal complex dopants are shown in Table 1.
  • the light emission maximum wavelength is the light emission maximum wavelength of a spectrum measured at 300 K by dissolving a phosphorescent metal complex dopant in 2-methyltetrahydrofuran.
  • a fluorescent dopant (also referred to as a fluorescent luminescent dopant) that can be used in combination with the above phosphorescent metal complex dopant is a compound that can emit light from an excited singlet and is excited. There is no particular limitation as long as light emission from a singlet is observed.
  • Examples of the fluorescent dopant used in the present invention include anthracene derivatives, pyrene derivatives, chrysene derivatives, fluoranthene derivatives, perylene derivatives, fluorene derivatives, arylacetylene derivatives, styrylarylene derivatives, styrylamine derivatives, arylamine derivatives, boron complexes, coumarins.
  • 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.
  • the singlet energy transfer efficiency from the TADF host compound to the phosphorescent metal complex dopant is set in the range of 10 to 100%. Note that as the emission of the TADF host compound has a shorter wavelength, the overlap between the fluorescence emission spectrum of the TADF host compound and the absorption spectrum of the phosphorescent metal complex dopant increases, and the singlet energy transfer efficiency increases.
  • the singlet energy transfer efficiency can be calculated by the following equation from the fluorescence lifetime ⁇ 0 of the immediate component of the TADF host compound alone film and the fluorescence lifetime ⁇ 1 of the TADF immediate component of the film doped with the dopant to the TADF host compound. .
  • the immediate component (also referred to as the Prompt component) means light emission that is immediately observed from the excited state after the TADF host compound is excited with the excitation light, and is not observed immediately after the excitation, and a certain time has elapsed. This refers to light emission that is distinguished from a delayed component (also referred to as a delay component) that is observed later.
  • the maximum emission peak intensity of the TADF host compound is 10% or less of the maximum emission peak intensity of the dopant.
  • the fluorescence emission spectrum of the TADF host compound is the absorption spectrum of the phosphorescent metal complex dopant and 1 It is preferable to have an overlap of ⁇ 10 14 nm 4 (mol / L) ⁇ 1 cm ⁇ 1 or more.
  • the overlap between the fluorescence emission spectrum of the TADF host compound and the absorption spectrum of the phosphorescent metal complex dopant is represented by ⁇ f ( ⁇ ) ⁇ ( ⁇ ) ⁇ (nm) 4 d ⁇ .
  • Table 2 shows the average distance r between the dopant molecules and the energy transfer efficiency E with respect to each molecular weight at a dopant doping concentration of 5 vol% and 10 vol%.
  • the average distance between dopant molecules is determined by (number density of dopant) ⁇ 1/3 , and is determined using the molecular weight of the dopant, the film density, and the dopant concentration.
  • 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 used in 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 thickness of the electron transport layer between several nanometers and several micrometers.
  • 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 have any of an electron injection property or a transport property, and a hole barrier property. Any one 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 transport material.
  • the distyrylpyrazine derivative exemplified as the material for the light emitting layer can also be used as an electron transport material, and an inorganic semiconductor such as n-type-Si, n-type-SiC, etc. as in the case of the hole injection layer and the hole transport layer. Can also be used as an electron transporting material.
  • a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.
  • an 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 materials may be used alone or in combination of two or more.
  • the hole blocking layer is a layer having the 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. By blocking the holes, the probability of recombination of electrons and holes can be improved. Moreover, the structure of the electron carrying layer mentioned above can be used as a hole-blocking layer used for this invention as needed.
  • 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 layer thickness of the hole blocking layer used in 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 a hole-blocking layer the material used for the above-mentioned electron transport layer is preferably used, and the material used as the other host compound is also preferably used for the hole-blocking layer.
  • the electron injection layer (also referred to as “cathode buffer layer”) used in 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. 2 and Chapter 2 “Electrode Materials” (pages 123 to 166) of the 2nd volume of “The Forefront of Industrialization” (published 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 layer thickness is preferably in the range of 0.1 to 5 nm depending on the material. Further, it may be a non-uniform film in which constituent materials are present intermittently.
  • 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. Moreover, the material used for said electron injection layer may be used independently, and may be used in combination of multiple types.
  • 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 used in 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 to 200 nm.
  • a material used for the hole transport layer (hereinafter also referred to as a hole transport material) may have any of a hole injection property or a transport property, and an electron barrier property. 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, poly
  • Examples of the triarylamine derivative include a benzidine type typified by ⁇ -NPD, a starburst type typified by MTDATA, and a compound having fluorene or anthracene in the triarylamine linking core part.
  • hexaazatriphenylene derivatives such as those described in JP-T-2003-519432 and JP-A-2006-135145 can also be used as hole transport materials.
  • a hole transport layer having a high p property doped with impurities may 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.
  • JP-A-11-251067 J. Org. Huang et. al.
  • a so-called p-type hole transport material or an inorganic compound such as p-type-Si or p-type-SiC, as described in the literature (Appl. Phys. Lett., 80 (2002), p. 139) is used. You can also.
  • ortho-metalated organometallic complexes having Ir or Pt as a central metal as typified by Ir (ppy) 3 are also preferably used.
  • the above-mentioned materials can be used as the hole transport material, 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.
  • Specific examples of known preferred hole transport materials used in the organic EL device of the present invention include the compounds described in the following documents in addition to the documents listed above, but the present invention is not limited thereto. Not. For example, Appl. Phys. Lett. 69, 2160 (1996); Lumin. , 72-74,985 (1997), Appl. Phys. Lett. 78, 673 (2001), Appl.
  • 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, while transporting holes. By blocking electrons, the probability of recombination of electrons and holes can be improved. Moreover, the structure of the positive hole transport layer mentioned above can be used as an electron blocking layer used for this invention as needed.
  • 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 used in 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 the material used for the above-described hole transport layer is preferably used, and the material used as the above-described host compound is also preferably used for the electron blocking layer.
  • the hole injection layer (also referred to as “anode buffer layer”) used in the present invention is a layer provided between the anode and the light emitting layer in order to lower the driving voltage or improve the light emission luminance. It is described in detail in the second chapter, Chapter 2, “Electrode Materials” (pages 123 to 166) of “Elements and the Forefront of Industrialization (issued by NTT Corporation on November 30, 1998)”.
  • the hole injection layer may be provided as necessary, and may exist 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 and 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.
  • the additive content include halogen elements such as bromine, iodine and chlorine, halogenated compounds, alkali metals such as Pd, Ca and Na, alkaline earth metals, transition metal compounds, complexes, and salts.
  • the content of the additive content can be arbitrarily determined, but is preferably 1000 ppm or less, more preferably 500 ppm or less, still more preferably 50 ppm or less, based on the total mass% of the contained layer. is there. However, it is not within this range depending on the purpose of improving the transportability of electrons and holes or the purpose of favoring the exciton energy transfer.
  • a method for forming an organic layer (hole injection layer, hole transport layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) according to the present invention will be described.
  • the method for forming the organic layer according to the present invention is not particularly limited, and a conventionally known method such as a vacuum deposition method or a wet method (also referred to as a wet process) can be used. Is more preferable.
  • the wet method include spin coating method, casting method, ink jet method, printing method, die coating method, blade coating method, roll coating method, spray coating method, curtain coating method, and LB method (Langmuir-Blodgett method).
  • a method having high suitability for a roll-to-roll method such as a die coating method, a roll coating method, an ink jet method, or a spray coating method is preferable.
  • liquid medium for dissolving or dispersing the organic EL material of the present invention examples include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, xylene, mesitylene, Aromatic hydrocarbons such as 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 disperse
  • 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 layer thickness of 0.1 nm to 5 ⁇ m, preferably 5 to 200 nm.
  • the organic layer according to the present invention is preferably formed from the hole injection layer to the cathode consistently by a single evacuation, but it may be taken out halfway and subjected to different film formation methods. In that case, it is preferable to perform the work in a dry inert gas atmosphere.
  • anode As the anode in the organic EL element, a material having a work function (4 eV or more, preferably 4.5 eV or more) of a metal, an alloy, an electrically conductive compound, or a mixture thereof is preferably used.
  • a conductive transparent material such as a metal such as Au, 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.
  • a thin film may be formed by vapor deposition or sputtering of these electrode materials, and a pattern with a desired shape may be formed by photolithography, or when pattern accuracy is not so high (about 100 ⁇ m or more) A pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material.
  • a wet film formation 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 preferably several hundred ⁇ / ⁇ or less.
  • the film thickness of the anode depends on the material, it is usually selected in the range of 10 nm to 1 ⁇ m, preferably 10 to 200 nm.
  • cathode As the cathode, a material having a low 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.
  • a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function value than this, from the point of durability against electron injection and oxidation, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al 2 O 3 ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred.
  • 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 the cathode is preferably several hundred ⁇ / ⁇ or less, and the film thickness is usually selected in the range of 10 nm to 5 ⁇ m, preferably 50 to 200 nm.
  • the emission luminance is advantageously improved.
  • a transparent or translucent cathode can be produced by producing a conductive transparent material mentioned in the description of the anode on the cathode after producing the above 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 element of the present invention is not particularly limited in the type of glass, plastic, etc., and is transparent. It may or may not be opaque. When light is extracted 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 polyarylates, 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)%) of 0.01 g / (m 2 ⁇ 24 h) or less is preferable as a gas barrier film. Further, oxygen measured by a method according to JIS K 7126-1987 A high gas 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 gas barrier film may be any material as long as it has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen.
  • silicon oxide, silicon dioxide, silicon nitride, and the like can be used.
  • the method for forming the gas barrier film is not particularly limited.
  • the vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma weight A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, and 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, and ceramic substrates.
  • 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.
  • external extraction quantum efficiency (%) number of photons emitted to the outside of the organic EL element / number of electrons flowed 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 the phosphor may be used in combination.
  • 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.
  • the sealing member may be disposed so as to cover the display area of the organic EL element, and may be concave or flat.
  • transparency and electrical insulation are not particularly limited. 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.
  • polymer plate examples include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone.
  • metal plate examples 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 transmission rate (25 ⁇ 0.5 ° C., relative humidity (90 ⁇ 2)%) is preferably that of 1 ⁇ 10 -3 g / (m 2 / 24h) or less.
  • 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 adhesive-hardened from room temperature to 80 degreeC is preferable.
  • a desiccant may be dispersed in the adhesive.
  • Application of the adhesive to the sealing portion may use a commercially available dispenser, or may be printed 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.
  • a material for forming the film any material may be used as long as it 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 element, or between the transparent electrode or light emitting layer and the transparent substrate. This is because the light undergoes total reflection between the light, the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the side surface direction of the element.
  • 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.
  • these methods can be used in combination with the organic EL device of the present invention.
  • 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, transparent A method of forming a diffraction grating between any layers of the electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used.
  • by combining these means it is possible to obtain an element having higher luminance or durability.
  • 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.
  • 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 diminished 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 in any layer or medium (inside a transparent substrate or transparent electrode). , Trying to extract light out.
  • the introduced diffraction grating desirably 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. However, by making the refractive index distribution a two-dimensional distribution, light traveling in all directions is diffracted, and light extraction efficiency is increased.
  • the position where the diffraction grating is introduced may be in any of the layers 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 gratings is preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.
  • the organic EL device of the present invention can be processed to provide, for example, a structure on a microlens array on the light extraction side of a support substrate (substrate), or combined with a so-called condensing sheet, for example, in a specific direction, such as device light emission. Condensing light in the front direction with respect to the surface can increase the luminance in a specific direction.
  • a microlens array quadrangular pyramids having a side of 30 ⁇ m and an apex angle of 90 degrees are 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 for example, a sheet that is put into practical use in an LED backlight of a liquid crystal display device can be used.
  • a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used.
  • BEF brightness enhancement film
  • the shape of the prism sheet for example, a substrate may be formed with a triangle 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 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 as needed during film formation. 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.
  • the organic EL element of the present invention can be used for a display device.
  • the display device may be single color or multicolor, but here, the multicolor display device will be described.
  • a shadow mask is provided only at the time of forming a light emitting layer, and a film can be formed on one surface by vapor deposition, casting, spin coating, ink jet, printing, or the like.
  • the method is not limited. However, the vapor deposition method, the ink jet method, the spin coating method, and the printing method are preferable.
  • the configuration of the organic EL element provided in the display device is selected from the above-described configuration examples of the organic EL element as necessary.
  • the manufacturing method of an organic EL element is as having shown to the one aspect
  • the multicolor display device can be used as a display device, a display, and various light emission sources.
  • a display device or display full-color display is possible by using three types of organic EL elements of blue, red, and green light emission.
  • the display device and display include a television, a personal computer, a mobile device, an AV device, a character broadcast display, and an information display in an automobile.
  • the driving method when used as a display device for reproducing moving images may be either a simple matrix (passive matrix) method or an active matrix method.
  • Light emitting sources include home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, etc.
  • the present invention is not limited to these.
  • FIG. 3 is a schematic view showing an example of a display device composed of organic EL elements. It is a schematic diagram of a display such as a mobile phone that displays image information by light emission of an organic EL element.
  • 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, a wiring unit C that electrically connects the display unit A and the control unit B, and the like. .
  • the control unit B is electrically connected to the display unit A via the wiring unit C, and sends a scanning signal and an image data signal to each of a plurality of pixels based on image information from the outside. Sequentially emit light according to the image data signal, scan the image, and display the image information on the display unit A.
  • FIG. 4 is a schematic diagram of a display device using an active matrix method.
  • the display unit A includes a wiring unit C including a plurality of scanning lines 5 and data lines 6, a plurality of pixels 3 and the like on a substrate.
  • the main members of the display unit A will be described below.
  • FIG. 3 shows a case where the light emitted from the pixel 3 (the emitted light L) is extracted in the direction of the white arrow (downward).
  • the scanning lines 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a lattice shape and are connected to the pixels 3 at the orthogonal positions (details are shown in FIG. Not shown).
  • the pixel 3 receives an image data signal from the data line 6 and emits light according to the received image data.
  • Full-color display is possible by appropriately arranging pixels in the red region, the green region, and the blue region on the same substrate.
  • FIG. 5 is a schematic diagram showing a pixel circuit.
  • the pixel includes an organic EL element 10, a switching transistor 11, a driving transistor 12, a capacitor 13, and the like.
  • a full color display can be performed by using red, green, and blue light emitting organic EL elements as the organic EL elements 10 in a plurality of pixels, and juxtaposing them on the same substrate.
  • an image data signal is applied from the control unit B to the drain of the switching transistor 11 through the data line 6.
  • a scanning signal is applied from the control unit B to the gate of the switching transistor 11 via the scanning line 5
  • the driving of the switching transistor 11 is turned on, and the image data signal applied to the drain is supplied to the capacitor 13 and the driving transistor 12. Is transmitted to the gate.
  • the capacitor 13 is charged according to the potential of the image data signal, and the drive transistor 12 is turned on.
  • the drive transistor 12 has a drain connected to the power supply line 7 and a source connected to the electrode of the organic EL element 10, and the power supply line 7 connects to the organic EL element 10 according to the potential of the image data signal applied to the gate. Current is supplied.
  • the driving of the switching transistor 11 is turned off.
  • the driving of the driving transistor 12 is kept on and the next scanning signal is applied. Until then, the light emission of the organic EL element 10 continues.
  • the driving transistor 12 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic EL element 10 emits light.
  • the organic EL element 10 emits light by the switching transistor 11 and the drive transistor 12 that are active elements for the organic EL element 10 of each of the plurality of pixels, and the light emission of the organic EL element 10 of each of the plurality of pixels 3. It is carried out.
  • Such a light emitting method is called an active matrix method.
  • the light emission of the organic EL element 10 may be light emission of a plurality of gradations by a multi-value image data signal having a plurality of gradation potentials, or by turning on / off a predetermined light emission amount by a binary image data signal. good.
  • the potential of the capacitor 13 may be held continuously until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.
  • a passive matrix light emission drive in which the organic EL element emits light according to the data signal only when the scanning signal is scanned.
  • FIG. 6 is a schematic diagram of a passive matrix display device.
  • a plurality of scanning lines 5 and a plurality of image data lines 6 are provided in a lattice shape so as to face each other with the pixel 3 interposed therebetween.
  • the scanning signal of the scanning line 5 is applied by sequential scanning, the pixels 3 connected to the applied scanning line 5 emit light according to the image data signal.
  • the pixel 3 has no active element, and the manufacturing cost can be reduced.
  • the organic EL element of the present invention By using the organic EL element of the present invention, a display device with improved luminous efficiency was obtained.
  • FIG. 1 One Embodiment of Lighting Device of the Present Invention.
  • 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 superimposed 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. 1 One Embodiment of Lighting Device of the present invention that includes the organic EL element of the present invention.
  • FIG. 7 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 the sealing operation with the glass cover, the organic EL element 101 is brought into contact with the atmosphere. And a glove box under a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more).
  • FIG. 8 shows a cross-sectional view of the lighting device.
  • 105 denotes a cathode
  • 106 denotes an organic EL layer
  • 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.
  • volume% of the compound in each example is obtained from the specific gravity by measuring the film thickness of the film to be formed by the quartz crystal microbalance method and calculating the mass.
  • Example 1 As a TADF host compound according to the present invention, a thin film of each of the TADF compounds exemplified above is prepared, measured for absolute photoluminescence (PL) quantum yield and emission lifetime at 300K, and has thermally activated delayed fluorescence. It was confirmed whether or not.
  • PL photoluminescence
  • a quartz substrate having a size of 50 mm ⁇ 50 mm and a thickness of 0.7 mm was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. Fixed to the substrate holder.
  • H-1 exemplified as the TADF host compound was filled in an optimum amount for device fabrication.
  • the crucible for vapor deposition was made of molybdenum-based resistance heating material. After reducing the pressure in the vacuum deposition apparatus to a vacuum degree of 1 ⁇ 10 ⁇ 4 Pa, H-1 was deposited at a deposition rate of 0.1 nm / second to produce a thin film with a thickness of 30 nm.
  • the light emission lifetime of the thin film 1-1 was measured by measuring the transient PL characteristics.
  • a small fluorescent lifetime measuring device C11367-03 manufactured by Hamamatsu Photonics
  • the slow decay component was measured in the M9003-01 mode by flash lamp excitation
  • the fast decay component was measured in the TCC900 mode using a 340 nm LED as the excitation light source.
  • the fluorescence component is observed in nanoseconds
  • the delayed fluorescence component derived from phosphorescence and triplet states is observed in micro or millisecond units.
  • compound H-1 When measurement was performed on the thin film 1-1, components of 10 ns and 300 ns were observed for the emission lifetime in the oxygen-free state, but only a component of 10 ns was observed for the emission lifetime in the oxygen atmosphere. This indicates that the triplet state is involved in the light emission of compound H-1, and that a light emission lifetime of microseconds is observed at room temperature, compound H-1 is thermally activated delayed fluorescence. It was shown to be a compound (TADF compound).
  • the thin films 1-2 to 1-4 were similarly evaluated, and it was shown that H-2, H-4, and H-6 exemplified as the TADF host compound are TADF compounds.
  • Table 3 shows the absolute PL quantum yield results of the thin films 1-1 to 1-4.
  • Example 2 A phosphorescent metal complex-doped film was prepared using a non-TADF compound and each of the above exemplified TADF compounds as host compounds, and the resistance in an excited state was evaluated.
  • a quartz substrate having a size of 50 mm ⁇ 50 mm and a thickness of 0.7 mm was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. Fixed to the substrate holder.
  • mCP 1,3-bis (9-carbazolyl) benzene
  • H-2 is used as an dopant
  • the crucible for vapor deposition was made of molybdenum-based resistance heating material. After reducing the pressure in the vacuum deposition apparatus to a vacuum degree of 1 ⁇ 10 ⁇ 4 Pa, deposition was performed at a deposition rate of 0.1 nm / second so that mCP and H-2 were 95% by volume and 5% by volume, respectively, and the film thickness was 30 nm. A thin film was prepared.
  • Thin films 2-2 to 2-10 were produced in the same manner as in the production of the thin film 2-1, except that the type of host compound, the type of dopant, and the concentration were changed as shown in Table 4.
  • ⁇ Preparation of Thin Film 2-11 In the production of the thin film 2-1, the host compound was changed to H-2 and mCP, and the dopant was changed to P-50, respectively, and H-2, mCP, and P-50 were 50% by volume, 35% by volume, and 15% by volume, respectively.
  • a thin film 2-11 was produced in the same manner except that a thin film having a film thickness of 30 nm was produced by vapor deposition at a vapor deposition rate of 0.1 nm / second so as to give a%.
  • Thin films 2-12 to 2-14 were prepared in the same manner as in the preparation of the thin film 2-1, except that the type of host compound, the type of dopant, and the concentration were changed as shown in Table 4.
  • the luminance residual ratio in the UV irradiation test using the HgXe light source was determined.
  • a UV irradiation test using a HgXe light source a mercury xenon lamp UV irradiation device LC8 manufactured by Hamamatsu Photonics was used, and an A9616-05 was attached to a UV cut filter.
  • the irradiation fiber light exit surface and the glass cover surface of the sample (blue light emitting layer single layer) were arranged so as to be horizontal, and irradiation was performed at a distance of 1 cm until the number of emitted photons was reduced to half.
  • the measurement was performed under conditions of room temperature (300K) and 330K. For each sample, the time (half time) required for the number of luminescent photons to be halved is shown as a relative value with the value of the thin film 2-1 at room temperature (300 K) being 1.
  • the results are shown in Table 4.
  • the luminance was measured with a spectral radiance meter CS-1000 (manufactured by Konica Minolta) from an angle inclined by 45 degrees from the axis of the irradiation fiber.
  • the reaction rate such as decomposition similarly increases, but since the crossing between the reverse terms of T 1 to S 1 is promoted at high temperature, Since the time in the triplet state is reduced and the reaction probability such as decomposition is reduced, it is considered that the device lifetime is improved or the reduction width is suppressed.
  • Example 3 ⁇ Preparation of organic EL element 3-1 >> First, an ITO (indium tin oxide) film having a thickness of 150 nm was formed as an anode on a glass substrate having a size of 50 mm ⁇ 50 mm and a thickness of 0.7 mm. After patterning, an ITO transparent electrode was attached. The transparent substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes, and then the transparent substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus.
  • ITO indium tin oxide
  • Each of the deposition crucibles in the vacuum deposition apparatus was filled with the constituent material of each layer in an amount optimal for device fabrication.
  • the evaporation crucible used was made of a resistance heating material made of molybdenum or tungsten.
  • a deposition crucible containing 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl ( ⁇ -NPD) was heated by applying current to the ITO transparent electrode at a deposition rate of 0.1 nm / second to form a hole injection transport layer having a layer thickness of 40 nm.
  • the deposition crucible containing mCP was energized and heated, and deposited on the hole transport layer at a deposition rate of 0.1 nm / second to form an intermediate layer having a layer thickness of 10 nm.
  • the deposition crucible containing mCP as the host compound and P-57 as the dopant was energized and heated, and deposited on the intermediate layer at a deposition rate of 0.1 nm / second so as to be 95% by volume and 5% by volume, respectively.
  • Co-evaporation was performed to form a light emitting layer having a layer thickness of 20 nm.
  • the deposition crucible containing E-1 was energized and heated, and deposited on the light emitting layer at a deposition rate of 0.1 nm / second to form an electron transport layer having a layer thickness of 40 nm.
  • the non-light emitting surface side of the above element was covered with a can-shaped glass case in an atmosphere of high-purity nitrogen gas with a purity of 99.999% or more, and an electrode lead-out wiring was installed to prepare an organic EL element 3-1.
  • Organic EL devices 3-2 to 3-7 were prepared in the same manner as in the production of the organic EL device 3-1, except that the type of host compound, the type of dopant, and the concentration were changed as shown in Table 5. .
  • the quenching rate of the phosphorescent metal complex can be suppressed by using the TADF compound as a host compound and combining with the phosphorescent metal complex dopant. It can be seen that the element driving life of the element can be improved.
  • the present invention is suitable for providing an organic electroluminescence device having excellent stability in the excited state of a host compound and a dopant and having an improved device driving lifetime.

Abstract

The objective of the present invention is to provide an organic electroluminescent element which has an improved element service life, and wherein a host compound and a dopant have excellent stability in excited states. This organic electroluminescent element is provided with a pair of electrodes and an organic layer arranged between the pair of electrodes, and is characterized in that: the light emitting layer contains a thermally activated delayed fluorescent host compound and a phosphorescent metal complex dopant; and the singlet energy transfer efficiency of the host compound to the phosphorescent metal complex dopant is within the range of 10-100%.

Description

有機エレクトロルミネッセンス素子Organic electroluminescence device
　本発明は、有機エレクトロルミネッセンス素子に関する。特に、ホスト化合物及びドーパントの励起状態での安定性に優れ、素子駆動寿命が向上した有機エレクトロルミネッセンス素子に関する。 The present invention relates to an organic electroluminescence element. In particular, the present invention relates to an organic electroluminescence device having excellent stability in the excited state of a host compound and a dopant and having an improved device driving life.
　従来、一重項励起子と三重項励起子のすべてをエレクトロルミネッセンス（electoroluminescence：以下ＥＬともいう。）に利用し、高発光効率を実現する発光材料を用いた有機ＥＬ素子が提案されている。
　リン光発光有機ＥＬ素子においては、高い発光効率と発光寿命の両方で実用域の材料が開発され、ディスプレイや照明に利用されている。 2. Description of the Related Art Conventionally, an organic EL element using a light emitting material that realizes high luminous efficiency by utilizing all of singlet excitons and triplet excitons for electroluminescence (hereinafter also referred to as EL) has been proposed.
In the phosphorescent organic EL element, a material in a practical range is developed with both high luminous efficiency and luminous lifetime, and is used for display and illumination.
　また、近年、熱活性化型遅延蛍光発光性化合物（ＴＡＤＦ化合物）をドーパントとして用いた有機ＥＬ素子が提案されている（例えば、特許文献１参照。）。 In recent years, an organic EL device using a heat-activated delayed fluorescent compound (TADF compound) as a dopant has been proposed (for example, see Patent Document 1).
　一般的にＴＡＤＦ化合物は、熱活性化による三重項状態から一重項状態への逆項間交差を引き起こすべく、分子内に電子供与性と電子吸引性の骨格を導入することでＨＯＭＯとＬＵＭＯが存在する位置を分離する必要があるため、ブロードな発光である電荷移動型の発光を示す。
　このようなＴＡＤＦ化合物において青色発光を得るためには、励起状態と基底状態のエネルギー準位間に大きなギャップが必要であり、発光色を深青色に近づけるにつれてＴＡＤＦ化合物の最低励起一重項（Ｓ１）（以下、単に「一重項（Ｓ１）」ともいう。）エネルギー及び最低励起三重項（Ｔ１）（以下、単に「三重項（Ｔ１）」ともいう。）エネルギーを高くする必要が生じる。更に、ドーパントとして用いられるＴＡＤＦ化合物上に励起状態を局在化させ高い量子効率を得るために、ホスト化合物の三重項エネルギーがドーパントの三重項エネルギーよりも高い必要がある。その場合、ドーパント及びホスト化合物が高いエネルギーを有する不安定な状態に留まるため、分解等により消光物質を生成しやすい、つまり、消光物質の生成速度Ｋｄが極めて速いことが、実用可能な素子寿命を得るための問題となっていた。 In general, TADF compounds have HOMO and LUMO by introducing an electron-donating and electron-withdrawing skeleton into the molecule to cause reverse intersystem crossing from the triplet state to the singlet state by thermal activation. Since it is necessary to separate the positions where the light is emitted, the charge transfer type light emission which is broad light emission is shown.
In order to obtain blue light emission in such TADF compounds, it requires a large gap between the energy levels of the excited state and the ground state, the lowest excited singlet of TADF compound as close an emission color to deep blue (S 1 ) (Hereinafter also simply referred to as “singlet (S 1 )”) Energy and lowest excited triplet (T 1 ) (hereinafter also simply referred to as “triplet (T 1 )”) energy needs to be increased. . Further, in order to localize the excited state on the TADF compound used as the dopant and obtain a high quantum efficiency, the triplet energy of the host compound needs to be higher than the triplet energy of the dopant. In that case, since the dopant and the host compound remain in an unstable state having high energy, it is easy to generate a quenching substance by decomposition or the like. It was a problem to get.
　ドーパントの一重項（Ｓ１）及び三重項（Ｔ１）エネルギーを低く保ったまま、深青色発光を得るためには発光がシャープであるリン光発光性金属錯体を用いることで解決できるが、実用可能な素子寿命を得るためには次の課題を有している。すなわち、下記Ｓｔｅｒｎ－Ｖｏｌｍｅｒ式で示されるように、素子駆動中に生成する消光物質濃度の増加に伴い、リン光発光性金属錯体の消光が生じる。高い三重項エネルギーを有するリン光発光材料においては、リン光の原理上リン光寿命τが数μｓ～数１００μｓと蛍光発光材料に比べて２～３オーダー長いこと、かつ、高い三重項エネルギーを有するためにドーパント発光と消光物質の吸収とに重なりが生じやすく、非特許文献１に示されているようにエネルギー移動速度Ｋｑが指数関数的に増大し、消光が起きやすいという原理的な問題を有しているため、実用可能な素子寿命が得られていない。例えば下記Ｓｔｅｒｎ－Ｖｏｌｍｅｒ式に基づき、非特許文献１に記載の値を用い消光物質としてのトリフルオレン（三重項エネルギー２．３ｅＶ）の濃度に対するリン光発光性金属錯体の発光減衰量を試算すると、２．７０ｅＶに近い高いエネルギーレベルの最低励起三重項（Ｔ１）（以下、単に「高Ｔ１」ともいう。）のドーパントでは顕著に発光が減衰してしまうことが分かる。 In order to obtain deep blue light emission while keeping the singlet (S 1 ) and triplet (T 1 ) energy of the dopant low, it can be solved by using a phosphorescent metal complex with sharp emission, but practical use In order to obtain a possible element lifetime, the following problems are encountered. That is, as shown by the following Stern-Volmer equation, quenching of the phosphorescent metal complex occurs with an increase in the concentration of the quenching substance generated during device driving. In the phosphorescent material having high triplet energy, the phosphorescence lifetime τ is several μs to several hundreds μs on the principle of phosphorescence, which is two to three orders longer than fluorescent materials, and has high triplet energy. For this reason, the dopant emission and the absorption of the quenching substance are likely to overlap with each other, and as shown in Non-Patent Document 1, the energy transfer rate Kq increases exponentially, and there is a principle problem that quenching easily occurs. Therefore, a practical device lifetime is not obtained. For example, based on the following Stern-Volmer equation, using the values described in Non-Patent Document 1, when calculating the emission attenuation amount of the phosphorescent metal complex with respect to the concentration of trifluorene (triplet energy 2.3 eV) as a quenching substance, It can be seen that the emission is significantly attenuated with the dopant of the lowest excited triplet (T 1 ) (hereinafter also simply referred to as “high T 1 ”) having a high energy level close to 2.70 eV.
Figure JPOXMLDOC01-appb-M000002
Figure JPOXMLDOC01-appb-M000002
　上記式中、ＰＬ（ｗｉｔｈ Ｑｕｅｎｃｈｅｒ）は消光物質存在下における発光強度、ＰＬ（ｗｉｔｈｏｕｔ Ｑｕｅｎｃｈｅｒ）は消光物質非存在下における発光強度、Ｋｑは発光材料から消光物質へのエネルギー移動速度、［Ｑ］（＝Ｋｄ＊ｔ）は消光物質濃度、Ｋｄは分解等による消光物質の生成速度、ｔは光又は電流による積算励起時間、τは消光物質が存在しない場合の発光材料のリン光寿命である。 In the above formula, PL (with Quencher) is the emission intensity in the presence of the quenching substance, PL (without Quencher) is the emission intensity in the absence of the quenching substance, Kq is the energy transfer rate from the emitting material to the quenching substance, [Q] ( = Kd * t) is the quencher concentration, Kd is the rate of generation of the quencher by decomposition, t is the cumulative excitation time by light or current, and τ is the phosphorescence lifetime of the luminescent material in the absence of the quencher.
　以上のように、緑色及び赤色リン光発光性ドーパントを有する発光素子としては実用的なものが報告されている一方、高三重項エネルギーを有する青色リン光発光性ドーパントを有する発光素子においては実用的な寿命レベルが達成されていない。これは、青色リン光発光性ドーパントが上記のように高Ｔ１かつリン光を用いた発光材料であることにより、分解等による消光物質の生成速度Ｋｄ、発光材料から消光物質へのエネルギー移動速度Ｋｑ、リン光寿命τが不利な状況にあり、駆動による消光が極めて生じやすい原理的な問題が存在するためと考えられる。 As described above, practical light-emitting elements having green and red phosphorescent dopants have been reported, whereas practical light-emitting elements having blue phosphorescent dopants having high triplet energy. Lifetime levels are not achieved. This energy transfer rate of by blue phosphorescent dopant is a luminescent material using a high T 1 and phosphorescence as described above, the production rate Kd quencher by decomposition, to the quencher from the luminescent material This is probably because Kq and phosphorescence lifetime τ are disadvantageous and there is a principle problem that quenching due to driving is very likely to occur.
特開２０１１－２１３６４３号公報JP 2011-213643 A
　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、ホスト化合物及びドーパントの励起状態での安定性に優れ、素子駆動寿命が向上した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 problems and situations, and its solution is to provide an organic electroluminescent device having excellent stability in the excited state of a host compound and a dopant and having an improved device driving life. It is.
　本発明に係る上記課題を解決すべく、上記問題の原因等について検討した結果、有機エレクトロルミネッセンス素子の発光層が、熱活性化型遅延蛍光発光性のホスト化合物と、リン光発光性金属錯体ドーパントとを含有し、前記ホスト化合物の前記リン光発光性金属錯体ドーパントへの一重項エネルギー移動効率が１０～１００％の範囲内であることで、ホスト化合物及びドーパントの励起状態での安定性に優れ、素子駆動寿命が向上した有機エレクトロルミネッセンス素子を提供できることを見いだした。
　すなわち、本発明に係る課題は、以下の手段により解決される。 As a result of investigating the cause of the above-mentioned problems in order to solve the above-mentioned problems according to the present invention, the light-emitting layer of the organic electroluminescence element is composed of a thermally activated delayed fluorescent light-emitting host compound and a phosphorescent light-emitting metal complex dopant And the singlet energy transfer efficiency of the host compound to the phosphorescent metal complex dopant is in the range of 10 to 100%, so that the host compound and the dopant are excellent in the excited state. The present inventors have found that an organic electroluminescence element having an improved element driving life can be provided.
That is, the subject concerning this invention is solved by the following means.
　１．一対の電極と、前記一対の電極間に有機層が具備された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、熱活性化型遅延蛍光発光性のホスト化合物と、リン光発光性金属錯体ドーパントとを含有し、
　前記ホスト化合物の前記リン光発光性金属錯体ドーパントへの一重項エネルギー移動効率が、１０～１００％の範囲内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。 1. A pair of electrodes, and an organic electroluminescence device comprising an organic layer between the pair of electrodes,
The light-emitting layer contains a thermally activated delayed fluorescence host compound and a phosphorescent metal complex dopant,
An organic electroluminescence device, wherein a singlet energy transfer efficiency of the host compound to the phosphorescent metal complex dopant is within a range of 10 to 100%.
　２．前記一重項エネルギー移動効率が、９０～１００％の範囲内であることを特徴とする第１項に記載の有機エレクトロルミネッセンス素子。 2. 2. The organic electroluminescence device according to item 1, wherein the singlet energy transfer efficiency is in the range of 90 to 100%.
　３．前記リン光発光性金属錯体ドーパントが、下記一般式（１）で表される構造を有することを特徴とする第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. 3. The organic electroluminescent device according to item 1 or 2, wherein the phosphorescent metal complex dopant has a structure represented by the following general formula (1).
Figure JPOXMLDOC01-appb-C000003
Figure JPOXMLDOC01-appb-C000003
　（一般式（１）中、Ｍは、Ｉｒ、Ｐｔ、Ｒｈ、Ｒｕ、Ａｇ、Ｃｕ又はＯｓを表す。Ａ１及びＡ２は、各々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員の芳香族複素環を表す。Ｂ１～Ｂ５は、５員の芳香族複素環を形成する原子群であり、置換基を有していても良い炭素原子、窒素原子、酸素原子又は硫黄原子を表す。環Ｚ１は、置換基を有していても良く、更に置換基同士が結合して縮環構造を形成していても良い。Ｌは、Ｍに配位したモノアニオン性の二座配位子を表す。Ｍに配位した各々の配位子は、その置換基が互いに結合して配位子同士が連結していても良い。ｍは、０～２の整数を表し、ｎは、１～３の整数を表し、ｍ＋ｎは、２又は３である。ｍ及びｎが各々２以上のとき、環Ｚ１、Ｂ１～Ｂ５で表される芳香族複素環基及びＬは各々同じであっても異なっていても良い。） (In General Formula (1), M represents Ir, Pt, Rh, Ru, Ag, Cu, or Os. A 1 and A 2 each represent a carbon atom or a nitrogen atom. Ring Z 1 represents A 1. And a 6-membered aromatic hydrocarbon ring or a 5-membered or 6-membered aromatic heterocycle formed together with A 2. B 1 to B 5 are an atomic group forming a 5-membered aromatic heterocycle Represents a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom which may have a substituent, and ring Z 1 may have a substituent, and the substituents are further bonded to each other to form a condensed ring structure. L represents a monoanionic bidentate ligand coordinated to M. Each ligand coordinated to M is coordinated by bonding of substituents thereof to each other. The children may be linked to each other, m represents an integer of 0 to 2, n represents an integer of 1 to 3, and m + n is 2 or 3. And when n is each of two or more, the ring Z 1, B 1 aromatic heterocyclic group and L represented by ~ B 5 may be different even each identical.)
　本発明によれば、ホスト化合物及びドーパントの励起状態での安定性に優れ、素子駆動寿命が向上した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、以下のように推察している。
　有機エレクトロルミネッセンス素子を電流駆動した場合、ホールと電子とがリン光発光性金属錯体ドーパント上で直接再結合した励起子と、ホスト化合物上で再結合した励起子とが生成し、その内訳は、三重項状態の励起子が７５％、一重項状態の励起子が２５％となる。図１に示すように、ＴＡＤＦ化合物でない（非ＴＡＤＦ）従来用いられるホスト化合物上で再結合した一重項励起子はＳ１→Ｓ０遷移が許容であるために、フェルスター機構によって速やかにドーパント上にエネルギー移動するか、ホスト分子内で速やかに失活する。一方、ホスト化合物上で再結合した三重項励起子はＴ１→Ｓ０の遷移が禁制のため、フェルスター機構によるエネルギー移動速度が遅く、隣接分子間の電子交換に基づくデクスター機構で遅いエネルギー移動が主であること、また、ホスト化合物内での失活速度も数μｓ～数ｍｓと遅いことから、不安定な励起状態（三重項励起状態）に長時間留まることになる。特に、青色を呈する金属錯体ドーパントに対して用いられるホスト化合物の場合、高い励起エネルギーを有する励起状態に長時間留まることになる。結果、ホスト化合物の分解等により消光物質を生成する速度が増大すると推定される。
　本発明者は、図２に示すように、三重項励起状態から一重項励起状態へ逆項間交差し、ドーパントへ効率的にエネルギー移動するＴＡＤＦ化合物をホスト化合物として用いてホスト化合物上に発生した三重項励起状態の滞在時間を短くし、三重項から一重項に逆項間交差した励起子を効果的にドーパントへエネルギー移動し、当該ホスト化合物上での三重項及び一重項励起状態の滞留を抑制することで、消光物質の生成速度Ｋｄを低減し、有機エレクトロルミネッセンス素子の寿命を大幅に向上できることを見いだした。したがって、本発明の有機エレクトロルミネッセンス素子は、熱活性化型遅延蛍光発光性のホスト化合物と、リン光発光性金属錯体ドーパントを発光層に含有することを特徴としている。 ADVANTAGE OF THE INVENTION According to this invention, the organic electroluminescent element which was excellent in stability in the excitation state of a host compound and a dopant, and whose element drive lifetime improved can be provided.
The expression mechanism or action mechanism of the effect of the present invention is presumed as follows.
When an organic electroluminescent device is driven by current, excitons in which holes and electrons are directly recombined on the phosphorescent metal complex dopant and excitons recombined on the host compound are generated, and the breakdown is as follows: The triplet state excitons are 75% and the singlet state excitons are 25%. As shown in FIG. 1, a singlet exciton recombined on a conventionally used host compound that is not a TADF compound (non-TADF) allows an S 1 → S 0 transition, so that the Forster mechanism can quickly Or rapidly deactivates in the host molecule. On the other hand, triplet excitons recombined on the host compound have a slow energy transfer rate due to the Forster mechanism due to the forbidden transition of T 1 → S 0 , and a slow energy transfer due to the Dexter mechanism based on electron exchange between adjacent molecules. In addition, since the deactivation rate in the host compound is as slow as several μs to several ms, it remains in an unstable excited state (triplet excited state) for a long time. In particular, in the case of a host compound used for a metal complex dopant exhibiting a blue color, the host compound stays in an excited state having high excitation energy for a long time. As a result, it is estimated that the rate at which the quenching substance is generated increases due to decomposition of the host compound and the like.
As shown in FIG. 2, the present inventor generated a host compound using a TADF compound that crosses back from the triplet excited state to the singlet excited state and efficiently transfers energy to the dopant as the host compound. The residence time in the triplet excited state is shortened, and excitons crossing back to back from the triplet to the singlet effectively transfer energy to the dopant, thereby retaining the triplet and singlet excited states on the host compound. It has been found that by suppressing it, the generation rate Kd of the quenching substance can be reduced, and the lifetime of the organic electroluminescence device can be significantly improved. Therefore, the organic electroluminescence device of the present invention is characterized in that the light-emitting layer contains a thermally activated delayed fluorescence host compound and a phosphorescent metal complex dopant.
従来のホスト化合物及びリン光発光性金属錯体ドーパントのエネルギー移動を説明する概略図Schematic explaining energy transfer of conventional host compound and phosphorescent metal complex dopant 本発明に係る熱活性化型遅延蛍光発光性のホスト化合物及びリン光発光性金属錯体ドーパントのエネルギー移動を説明する概略図Schematic explaining energy transfer of thermally activated delayed fluorescence host compound and phosphorescent metal complex dopant according to the present invention 有機ＥＬ素子から構成される表示装置の一例を示した模式図Schematic diagram showing an example of a display device composed of organic EL elements 図３における表示部Ａの模式図Schematic diagram of display section A in FIG. 画素の回路を示した概略図Schematic showing the pixel circuit パッシブマトリクス方式フルカラー表示装置の模式図Schematic diagram of passive matrix type full color display device 照明装置の概略図Schematic of lighting device 照明装置の模式図Schematic diagram of lighting device
　本発明の有機エレクトロルミネッセンス素子は、一対の電極と、前記一対の電極間に有機層が具備された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、熱活性化型遅延蛍光発光性のホスト化合物と、リン光発光性金属錯体ドーパントとを含有し、前記ホスト化合物の前記リン光発光性金属錯体ドーパントへの一重項エネルギー移動効率が、１０～１００％の範囲内であることを特徴とする。この特徴は、請求項１から請求項３までの請求項に共通する又は対応する技術的特徴である。
　本発明においては、前記一重項エネルギー移動効率が、９０～１００％の範囲内であることが好ましい。これにより、熱活性化型遅延蛍光発光性のホスト化合物の三重項励起状態から逆項間交差された一重項励起状態エネルギーが効果的にドーパントへ移動するため、当該ホスト化合物の劣化を抑制することができる。
　また、本発明においては、前記リン光発光性金属錯体ドーパントが、前記一般式（１）で表される構造を有することが好ましい。これにより、π電子過剰の５員の芳香族複素環を有するために、π電子欠乏の６員環配位子を有するドーパントに比較してＨＯＭＯ準位が高く、ホールのトラップとなりやすく、ホストの一重項及び三重項励起状態を生成しにくくなり、ホスト化合物の分解等による消光物質の生成を抑制することができる。 The organic electroluminescence device of the present invention is an organic electroluminescence device in which an organic layer is provided between a pair of electrodes and the pair of electrodes, and the light emitting layer is a thermally activated delayed fluorescence host compound And a phosphorescent metal complex dopant, wherein the singlet energy transfer efficiency of the host compound to the phosphorescent metal complex dopant is in the range of 10 to 100%. This feature is a technical feature common to or corresponding to the claims of claims 1 to 3.
In the present invention, the singlet energy transfer efficiency is preferably in the range of 90 to 100%. This effectively suppresses the degradation of the host compound because the singlet excited state energy crossed between the reverse terms from the triplet excited state of the thermally activated delayed fluorescent light emitting host compound is effectively transferred to the dopant. Can do.
Moreover, in this invention, it is preferable that the said phosphorescence-emitting metal complex dopant has a structure represented by the said General formula (1). Thus, since it has a 5-membered aromatic heterocyclic ring with π-excess, it has a higher HOMO level than a dopant with a 6-membered ring ligand with π-electron deficiency, and it tends to trap holes. It becomes difficult to generate singlet and triplet excited states, and generation of a quenching substance due to decomposition of the host compound or the like can be suppressed.
　また、本発明においては、熱活性化型遅延蛍光発光性のホスト化合物の蛍光発光スペクトルが、リン光発光性金属錯体ドーパントの吸収スペクトルと１×１０１４ｎｍ４（ｍｏｌ／Ｌ）－１ｃｍ－１以上の重なりを有することが好ましい。これにより、熱活性化型遅延蛍光発光性のホスト化合物の一重項状態のフェルスター半径（熱活性化型遅延蛍光発光性のホスト化合物からリン光発光性金属錯体ドーパントへのエネルギー移動速度が、熱活性化型遅延蛍光発光性のホスト化合物自身での失活速度と等しくなる距離）が大きくなり、三重項から一重項に逆項間交差した励起子を、効果的にドーパントへエネルギー移動し、当該ホスト化合物上でのＳ１励起状態の滞留を抑制することができる。 In the present invention, the fluorescence emission spectrum of the thermally activated delayed fluorescence emission host compound is the same as the absorption spectrum of the phosphorescence emission metal complex dopant and 1 × 10 14 nm 4 (mol / L) −1 cm −. It is preferable to have one or more overlaps. As a result, the singlet state Forster radius of the thermally activated delayed fluorescence host compound (the energy transfer rate from the thermally activated delayed fluorescence host compound to the phosphorescent metal complex dopant is The distance that is equal to the deactivation rate of the activated delayed fluorescence host compound itself) is increased, and the excitons that cross the back-to-back singlet from the triplet to the singlet effectively transfer energy to the dopant. Residence of the S 1 excited state on the host compound can be suppressed.
　また、本発明においては、熱活性化型遅延蛍光発光性のホスト化合物の一重項励起状態エネルギーが、当該ホスト化合物が有する最小の結合開裂エネルギーより低いことが好ましく、より好ましくは当該ホスト化合物の一重項励起状態エネルギーが、当該ホスト化合物が有する最小の結合開裂エネルギーよりも０．２ｅＶ以上低いことが好ましい。これにより、高いエネルギーを有する一重項励起状態で結合開裂による分解等からの消光物質の生成を抑制することができる。 In the present invention, the singlet excited state energy of the thermally activated delayed fluorescence host compound is preferably lower than the minimum bond cleavage energy of the host compound, more preferably the singlet of the host compound. It is preferable that the term excited state energy is 0.2 eV or more lower than the minimum bond cleavage energy of the host compound. Thereby, the production | generation of the quenching substance from the decomposition | disassembly by bond cleavage, etc. can be suppressed in the singlet excited state which has high energy.
　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
　上記の中で（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。 <Outline of organic electroluminescence device>
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 /) luminescent 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良い。
　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。）を設けても良く、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。）を設けても良い。 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.
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, and the light emitting layer and the anode may be provided. 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.
　本発明に用いられる電子輸送層とは、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良い。
　本発明に用いられる正孔輸送層とは、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良い。
　上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」とする。 The electron transport layer used in 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 used in 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.
In the above-described typical element configuration, a layer excluding the anode and the cathode is referred to as an “organic layer”.
　また、本発明の有機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良い。
　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。
　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、上記第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、異なっていても良い。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良い。 The organic EL element of the present invention may be a so-called tandem element in which a plurality of light emitting units including at least one light emitting layer are stacked.
As typical element configurations of the tandem structure, for example, the following configurations can be given.
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. Further, the 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良く、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良い。
　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良く、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、公知の材料及び構成を用いることができる。 Further, the third light emitting unit may not be provided. 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. Known materials and structures can be used as long as they are also called insulating layers and have 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／ＳｎＯ２、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 materials used for the intermediate layer include ITO (indium tin oxide), IZO (indium zinc oxide), ZnO 2 , TiN, ZrN, HfN, TiOx, VOx, CuI, InN, GaN, and CuAlO 2. , CuGaO 2 , SrCu 2 O 2 , LaB 6 , RuO 2 , Al, etc., conductive inorganic compound layers, Au / Bi 2 O 3, etc., two-layer films, SnO 2 / Ag / SnO 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 , Conductive organic compound layers such as metal phthalocyanines, metal-free phthalocyanines, metal porphyrins, metal-free porphyrins, etc. The present invention is not limited to these.
　発光ユニット内の好ましい構成としては、例えば上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。
　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号公報、特許第３４９６６８１号公報、特許第３８８４５６４号公報、特許第４２１３１６９号公報、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。 Preferred examples of the structure within the light emitting unit include those obtained by removing the anode and the cathode from the structures (1) to (7) mentioned in the above representative element structures, but the present invention is not limited to these. Not.
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-3496868, JP-A-3848564, JP-A-4421169, JP 2010-192719, JP 009-076929, JP 2008-078414, JP 2007-059848, JP 2003-272860, JP 2003-045676, WO 2005/094130, etc. Although a structure, a constituent material, etc. are mentioned, this invention is not limited to these.
　ここで、本発明の有機ＥＬ素子は、一対の電極と、前記一対の電極間に有機層が具備された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、熱活性化型遅延蛍光発光性のホスト化合物と、リン光発光性金属錯体ドーパントとを含有し、前記ホスト化合物の前記リン光発光性金属錯体ドーパントへの一重項エネルギー移動効率が、１０～１００％の範囲内であることを特徴とする。 Here, the organic EL device of the present invention is an organic electroluminescence device in which an organic layer is provided between a pair of electrodes and the pair of electrodes, and the light emitting layer has a thermally activated delayed fluorescence emission property. A host compound and a phosphorescent metal complex dopant, wherein the singlet energy transfer efficiency of the host compound to the phosphorescent metal complex dopant is in the range of 10 to 100%. To do.
《発光層》
　本発明に係る有機層は、発光層を有する。本発明に係る発光層は、電極又は隣接層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良い。本発明に係る発光層は、本発明で規定する要件を満たしていれば、その構成に特に制限はない。 <Light emitting layer>
The organic layer according to the present invention has a light emitting layer. The light emitting layer according to the present invention is a layer that provides a field in which electrons and holes injected from an electrode or an adjacent layer are recombined to emit light via excitons, and the light emitting portion is a layer of the light emitting layer. Even within, it may be the interface between the light emitting layer and the adjacent layer. The structure of the light emitting layer according to the present invention is not particularly limited as long as it satisfies the requirements defined in the present invention.
　発光層の層厚の総和は、特に制限はないが、形成する層の均質性や、発光時に不必要な高電圧を印加するのを防止し、かつ駆動電流に対する発光色の安定性向上の観点から、２ｎｍ～５μｍの範囲に調整することが好ましく、より好ましくは２～５００ｎｍの範囲に調整され、更に好ましくは５～２００ｎｍの範囲に調整される。
　また、本発明において個々の発光層の層厚としては、２ｎｍ～１μｍの範囲に調整することが好ましく、より好ましくは２～２００ｎｍの範囲に調整され、更に好ましくは３～１５０ｎｍの範囲に調整される。 The total thickness of the light emitting layer is not particularly limited, but it is possible to prevent the homogeneity of the layer to be formed, the application of unnecessary high voltage during light emission, and the improvement of the stability of the emission color against the driving current. Therefore, it is preferably adjusted to a range of 2 nm to 5 μm, more preferably adjusted to a range of 2 to 500 nm, and further preferably adjusted to a range of 5 to 200 nm.
In the present invention, the thickness of each light emitting layer is preferably adjusted to a range of 2 nm to 1 μm, more preferably adjusted to a range of 2 to 200 nm, and further preferably adjusted to a range of 3 to 150 nm. The
　本発明に係る発光層には、発光ドーパント（発光性ドーパント化合物、ドーパント化合物、単にドーパントともいう。）と、ホスト化合物（マトリックス材料、発光ホスト化合物、単にホストともいう。）とを含有することが好ましい。 The light-emitting layer according to the present invention contains a light-emitting dopant (a light-emitting dopant compound, a dopant compound, also simply referred to as a dopant) and a host compound (a matrix material, a light-emitting host compound, also simply referred to as a host). preferable.
［１］ホスト化合物
　発光層に用いられるホスト化合物は、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。
　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、発光層に含有される化合物の内で、その層中での質量比が２０％以上であることが好ましい。
　また、ホスト化合物の三重項励起状態エネルギーは、同一層内に含有される発光ドーパントの三重項励起状態エネルギーよりも高いことが好ましい。 [1] Host Compound The host compound used in the light emitting layer is a compound mainly responsible for charge injection and transport in the light emitting layer, and the light emission itself is not substantially observed in the organic EL element.
Preferably, it is a compound having a phosphorescence quantum yield of phosphorescence of less than 0.1 at room temperature (25 ° C.), more preferably a compound having a phosphorescence quantum yield of less than 0.01. Moreover, it is preferable that the mass ratio in the layer is 20% or more among the compounds contained in a light emitting layer.
The triplet excited state energy of the host compound is preferably higher than the triplet excited state energy of the light-emitting dopant contained in the same layer.
　ホスト化合物は、単独で用いても良く、又は複数種併用して用いても良い。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。 The host compounds may be used alone or in combination of two or more. 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.
　本発明においては、ホスト化合物として、熱活性化型遅延蛍光発光性のホスト化合物（ＴＡＤＦホスト化合物）が用いられる。 In the present invention, a heat-activated delayed fluorescence host compound (TADF host compound) is used as the host compound.
［１－１］熱活性化型遅延蛍光発光性のホスト化合物
　本発明に係る発光層に含有される熱活性化型遅延蛍光発光性のホスト化合物としては、熱活性化型遅延蛍光発光性化合物（ＴＡＤＦ化合物）が用いられる。
　ＴＡＤＦ化合物は、一重項励起エネルギー準位と三重項励起エネルギー準位の差ΔＥｓｔが小さいために、通常では起こり得ない三重項励起状態から一重項励起状態への逆項間交差が起こる。更に、一重項励起状態から基底状態への失活（＝蛍光発光）の速度定数が極めて大きいことから、三重項励起子はそれ自体が基底状態に熱的に失活（無輻射失活）するよりも、一重項励起状態経由で蛍光を発しながら基底状態に戻る方が速度論的に有利である。
　逆項間交差により三重項励起状態でいる時間を短くすることで、分解等により消光物質を生成する速度を抑制することができる。
　本発明に用いることができるＴＡＤＦホスト化合物としては、一般的に知られているように、発光ドーパントの三重項エネルギーよりも高い三重項エネルギーを有し、発光ドーパントの発光を消光しない化合物であれば好適に用いることができる。 [1-1] Thermally Activated Delayed Fluorescent Host Compound As the thermally activated delayed fluorescent luminescent host compound contained in the light emitting layer according to the present invention, a thermally activated delayed fluorescent luminescent compound ( TADF compounds) are used.
In the TADF compound, since the difference ΔEst between the singlet excitation energy level and the triplet excitation energy level is small, a reverse intersystem crossing from the triplet excited state to the singlet excited state, which cannot normally occur, occurs. Furthermore, since the rate constant of deactivation from the singlet excited state to the ground state (= fluorescence emission) is extremely large, triplet excitons themselves are thermally deactivated to the ground state (non-radiative deactivation). It is more kinetically advantageous to return to the ground state while emitting fluorescence via the singlet excited state.
By shortening the time in the triplet excited state due to reverse intersystem crossing, the rate at which a quenching substance is generated by decomposition or the like can be suppressed.
The TADF host compound that can be used in the present invention is a compound that has a triplet energy higher than the triplet energy of the light-emitting dopant and does not quench the light emission of the light-emitting dopant, as is generally known. It can be used suitably.
　熱活性化型遅延蛍光化合物の上記ΔＥｓｔを小さくするための分子設計について説明する。
　上記ΔＥｓｔを小さくするためには、原理上分子内の最高被占軌道（Ｈｉｇｈｅｓｔ　Ｏｃｃｕｐｉｅｄ　Ｍｏｌｅｃｕｌａｒ　Ｏｒｂｉｔａｌ：ＨＯＭＯ）と最低空軌道（Ｌｏｗｅｓｔ　Ｕｎｏｃｃｕｐｉｅｄ　Ｍｏｌｅｃｕｌａｒ　Ｏｒｂｉｔａｌ：ＬＵＭＯ）の空間的な重なりを小さくすることが最も効果的である。 The molecular design for reducing the ΔEst of the thermally activated delayed fluorescent compound will be described.
In order to reduce the above ΔEst, in principle, it is most effective to reduce the spatial overlap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) in the molecule. Is.
　一般に分子の電子軌道において、ＨＯＭＯは電子供与性部位に、ＬＵＭＯは電子吸引性部位に分布することが知られており、分子内に電子供与性と電子吸引性の骨格を導入することによって、ＨＯＭＯとＬＵＭＯが存在する位置を遠ざけることが可能である。
　ここで、電子供与性部位及び電子吸引性部位の「部位」とは、置換基又は原子群のことを指す。 In general, it is known that HOMO is distributed in electron donating sites and LUMO is distributed in electron withdrawing sites in the electron orbit of the molecule. By introducing an electron donating and electron withdrawing skeleton into the molecule, HOMO is distributed. It is possible to move away the position where LUMO exists.
Here, the “site” of the electron donating moiety and the electron withdrawing moiety refers to a substituent or a group of atoms.
　電子供与性部位の例としては、例えば、アリールアミン類、カルバゾール、フェノキサジン、アクリジン、フェノチアジン及びピロール類等の環が挙げられる。
　電子吸引性部位の例としては、例えば、含窒素芳香族複素環、シアノ基又はスルホニル基等の電子吸引性基によって置換された芳香族環等が挙げられる。 Examples of the electron donating moiety include rings such as arylamines, carbazole, phenoxazine, acridine, phenothiazine and pyrroles.
Examples of the electron-withdrawing moiety include a nitrogen-containing aromatic heterocycle, an aromatic ring substituted with an electron-withdrawing group such as a cyano group or a sulfonyl group.
　化合物が熱活性化型遅延蛍光発光性（ＴＡＤＦ性）を示すためには、ΔＥｓｔ＝Ｓ１－Ｔ１の絶対値が１．０ｅＶ以下であることが好ましく、より好ましくは０．５ｅＶ以下である。ΔＥｓｔの値は、三重項励起状態から一重項励起状態への逆項間交差の速度に直結する。 In order for the compound to exhibit thermally activated delayed fluorescence (TADF property), the absolute value of ΔEst = S 1 -T 1 is preferably 1.0 eV or less, more preferably 0.5 eV or less. . The value of ΔEst is directly related to the speed of the crossing between inverse terms from the triplet excited state to the singlet excited state.
　本発明に係るＴＡＤＦホスト化合物として用いられる好ましいＴＡＤＦ化合物を以下に例示するが、本発明はこれに限定されるものではない。 Preferred examples of the TADF compound used as the TADF host compound according to the present invention are exemplified below, but the present invention is not limited thereto.
Figure JPOXMLDOC01-appb-C000004
Figure JPOXMLDOC01-appb-C000004
［１－２］最低励起一重項エネルギー（Ｓ１）
　ＴＡＤＦホスト化合物の一重項励起状態のエネルギーは高エネルギーであるほど蛍光発光が短波長になり、リン光発光性金属錯体ドーパントの吸収スペクトルとの間に重なりを生じやすくなることで、一重項励起状態からリン光発光性金属錯体ドーパントに効率的にエネルギー移動しやすくなるため、一重項励起状態のエネルギーの上限はないといえる。しかし実際には、一重項励起状態のエネルギーが高くなると、ＴＡＤＦホスト化合物が有する最小の結合開裂エネルギーよりも一重項励起状態のエネルギーが大きくなるために、励起状態において開裂が生じ、反応によって低い準位を有する消光物質を生じやすくなる。基底状態での結合開裂エネルギー（Ｂｏｎｄ　Ｄｉｓｓｏｃｉａｔｉｏｎ　Ｅｎｅｒｇｙ）はＪ．Ａｍ．Ｃｈｅｍ．Ｃ，２０１４，１１８，ｐｐ７５６９－７５７８に記載の方法で計算することができる。本発明における結合開裂エネルギーとは、化合物の各々の結合に対して、当該文献の方法で計算を行った結果得られる最小のエネルギーのことをいう。 [1-2] Lowest excited singlet energy (S 1 )
The higher the energy of the singlet excited state of the TADF host compound, the shorter the fluorescence emission, and the easier it is to form an overlap with the absorption spectrum of the phosphorescent metal complex dopant. Therefore, it can be said that there is no upper limit of the energy of the singlet excited state because it is easy to efficiently transfer energy to the phosphorescent metal complex dopant. However, in reality, when the energy of the singlet excited state is increased, the energy of the singlet excited state is larger than the minimum bond cleavage energy of the TADF host compound, so that cleavage occurs in the excited state, and the reaction causes a lower quasi- It becomes easy to produce a quenching substance having a position. Bond Dissociation Energy in the ground state is described in J. Org. Am. Chem. C, 2014, 118, pp 7569-7578. The bond cleavage energy in the present invention refers to the minimum energy obtained as a result of calculation by the method of the literature for each bond of a compound.
　ＴＡＤＦホスト化合物のＳ１エネルギーが基底状態での結合開裂エネルギーより低いことで、一重項励起状態で開裂反応が吸熱的となるために、消光物質の生成を抑制することができる。 Since the S 1 energy of the TADF host compound is lower than the bond cleavage energy in the ground state, the cleavage reaction becomes endothermic in the singlet excited state, so that generation of a quenching substance can be suppressed.
［１－３］その他のホスト化合物
　本発明に係る発光層は、上記したＴＡＤＦホスト化合物に加えて、更にその他のホスト化合物を含有していても良い。 [1-3] Other Host Compounds The light emitting layer according to the present invention may further contain other host compounds in addition to the above TADF host compound.
　本発明に係るその他のホスト化合物は、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。また、本発明に係る発光層に含有される化合物の内で、その層中での体積比が５０％以下であることが好ましい。また、その他のホスト化合物としては、ＴＡＤＦホスト化合物の最低励起三重項エネルギーより大きな三重項励起エネルギーを持つものが好ましい。体積比が５０％以下であり、かつＴＡＤＦホスト化合物の最低励起三重項エネルギーよりも高いことで、その他のホスト化合物上で電子－ホールの再結合が生じ三重項励起状態が形成された場合でも隣接したＴＡＤＦホスト化合物が存在する確率が高いために、デクスター機構によりＴＡＤＦホスト化合物にエネルギー移動したのち、一重項励起子に変換されるためである。 The other host compound according to the present invention is a compound mainly responsible for charge injection and transport in the light emitting layer, and its own light emission is not substantially observed in the organic EL element. Moreover, it is preferable that the volume ratio in the layer is 50% or less among the compounds contained in the light emitting layer which concerns on this invention. Further, as other host compounds, those having triplet excitation energy larger than the lowest excitation triplet energy of the TADF host compound are preferable. When the volume ratio is 50% or less and is higher than the lowest excited triplet energy of the TADF host compound, electron-hole recombination occurs on other host compounds, even when triplet excited states are formed. This is because there is a high probability that the TADF host compound exists, and the energy is transferred to the TADF host compound by the Dexter mechanism and then converted into singlet excitons.
　その他のホスト化合物は、複数種併用して用いても良い。その他の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。
　本発明で用いることができるその他の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良く、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良い。
　その他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、かつ、発光の長波長化を防ぎ、更に、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 Ｃｏｌｏｒｉｍｅｔｒｙ：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。 Other host compounds may be used in combination. By using a plurality of other host compounds, the movement of charges can be adjusted, and the efficiency of the organic EL element can be increased.
There is no restriction | limiting in particular as another host compound which can be used by this invention, The compound conventionally used with an organic EL element can be used. A low molecular compound or a high molecular compound having a repeating unit may be used, and a compound having a reactive group such as a vinyl group or an epoxy group may be used.
As other host compounds, while having hole transporting ability or electron transporting ability, the emission of light is prevented from being increased in wavelength, and the organic EL element is stable against heat generation during driving at high temperature or during 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 Colorimetry).
　本発明の有機ＥＬ素子に用いられる、その他の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が挙げられるが、本発明はこれらに限定されない。
　例えば、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、欧州特許出願公開第２０３４５３８号明細書等が挙げられる。 Specific examples of other host compounds used in the organic EL device of the present invention include compounds described in the following documents, but the present invention is not limited thereto.
For example, Japanese Patent Laid-Open Nos. 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860 Gazette, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579 No. 2002-105445, No. 2002-343568, No. 2002-141173, No. 2002-352957, No. 2002-203683, No. 2002-363227, No. 2002-231453. No. 2003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060. No. 2002-302516, No. 2002-305083, No. 2002-305084, No. 2002-308837, No. 2003/0175553, 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 ,Country Public Publication No. 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. 2007/063754, 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. 2012/0038 / No. 023947, Japanese Patent Application Laid-Open No. 2008-074939, Japanese Patent Application Laid-Open No. 2007-254297, and European Patent Application No. 2034538.
［２］発光ドーパント
　本発明に用いられる発光ドーパントとしては、リン光発光性金属錯体ドーパント（リン光ドーパント、リン光発光性ドーパントともいう。）が用いられる。本発明においては、特に、後述する一般式（１）で表されるリン光発光性金属錯体ドーパントを用いることが好ましい。
　発光層中の発光ドーパントの濃度については、使用される特定のドーパント及びデバイスの必要条件に基づいて、任意に決定することができ、発光層の層厚方向に対し、均一な濃度で含有されていても良く、また任意の濃度分布を有していても良い。 [2] Luminescent dopant As the luminescent dopant used in the present invention, a phosphorescent metal complex dopant (also referred to as a phosphorescent dopant or a phosphorescent dopant) is used. In the present invention, it is particularly preferable to use a phosphorescent metal complex dopant represented by the following general formula (1).
The concentration of the luminescent dopant in the luminescent layer can be arbitrarily determined based on the specific dopant used and the requirements of the device, and is contained at a uniform concentration in the thickness direction of the luminescent layer. It may also have an arbitrary concentration distribution.
　また、本発明に用いられる発光ドーパントは、リン光発光性金属錯体ドーパントを複数種併用して用いても良いし、蛍光発光性ドーパントと組み合わせて用いても良い。これにより、任意の発光色を得ることができる。
　本発明の有機ＥＬ素子や本発明に用いられる化合物の発光する色は、「新編色彩科学ハンドブック」（日本色彩学会編、東京大学出版会、１９８５）の１０８頁の図５．１６において、分光放射輝度計ＣＳ－１０００（コニカミノルタ（株）製）で測定した結果をＣＩＥ色度座標に当てはめたときの色で決定される。
　本発明においては、１層又は複数層の発光層が、発光色の異なる複数の発光ドーパントを含有し、白色発光を示すことも好ましい。
　白色を示す発光ドーパントの組み合わせについては特に限定はないが、例えば青と橙や、青と緑と赤の組み合わせ等が挙げられる。
　本発明の有機ＥＬ素子における白色とは、特に限定はなく、橙色寄りの白色であっても青色寄りの白色であっても良いが、２度視野角正面輝度を前述の方法により測定した際に、１０００ｃｄ／ｍ２でのＣＩＥ１９３１表色系における色度がｘ＝０．３９±０．０９、ｙ＝０．３８±０．０８の領域内にあることが好ましい。 Moreover, the luminescent dopant used for this invention may be used in combination with multiple types of a phosphorescent metal complex dopant, and may be used in combination with a fluorescent luminescent dopant. Thereby, arbitrary luminescent colors can be obtained.
The light emission color of the organic EL device of the present invention and the compound used in the present invention is shown in FIG. 5.16 on page 108 of “New Color Science Handbook” (Edited by the Japan Color Society, University of Tokyo Press, 1985). It is determined by the color when the result measured with the luminance meter CS-1000 (manufactured by Konica Minolta Co., Ltd.) is applied to the CIE chromaticity coordinates.
In the present invention, it is also preferable that the light emitting layer of one layer or a plurality of layers contains a plurality of light emitting dopants having different emission colors and emits white light.
There are no particular limitations on the combination of the light-emitting dopants that exhibit white, and examples include blue and orange, and a combination of blue, green, and red.
The white color in the organic EL device of the present invention is not particularly limited, and may be white near orange or white near blue. However, when the 2 ° viewing angle front luminance is measured by the method described above, The chromaticity in the CIE 1931 color system at 1000 cd / m 2 is preferably in the region of x = 0.39 ± 0.09 and y = 0.38 ± 0.08.
［２－１］リン光ドーパント
　本発明に係るリン光ドーパントは、励起三重項からの発光が観測される化合物であり、具体的には、室温（２５℃）にてリン光発光する化合物であり、リン光量子収率が、２５℃において０．０１以上の化合物であると定義されるが、好ましいリン光量子収率は０．１以上である。
　上記リン光量子収率は、第４版実験化学講座７の分光IIの３９８頁（１９９２年版、丸善）に記載の方法により測定できる。溶液中でのリン光量子収率は種々の溶媒を用いて測定できるが、本発明に係るリン光ドーパントは、任意の溶媒のいずれかにおいて上記リン光量子収率（０．０１以上）が達成されれば良い。 [2-1] Phosphorescent dopant The phosphorescent dopant according to the present invention is a compound in which light emission from an excited triplet is observed, specifically, a compound that emits phosphorescence at room temperature (25 ° C.). The phosphorescence quantum yield is defined as a compound of 0.01 or more at 25 ° C., but the preferred phosphorescence quantum yield is 0.1 or more.
The phosphorescence quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence dopant according to the present invention achieves the phosphorescence quantum yield (0.01 or more) in any solvent. It ’s fine.
　リン光ドーパントの発光は原理としては２種挙げられ、一つはキャリアが輸送されるホスト化合物上でキャリアの再結合が起こってホスト化合物の励起状態が生成し、このエネルギーをリン光ドーパントに移動させることでリン光ドーパントからの発光を得るというエネルギー移動型である。もう一つはリン光ドーパントがキャリアトラップとなり、リン光ドーパント上でキャリアの再結合が起こりリン光ドーパントからの発光が得られるというキャリアトラップ型である。いずれの場合においても、リン光ドーパントの励起状態のエネルギーはホスト化合物の励起状態のエネルギーよりも低いことが条件である。
　本発明において使用できるリン光ドーパントとしては、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。 There are two types of light emission of phosphorescent dopants in principle. One is the recombination of carriers on the host compound to which carriers are transported to generate an excited state of the host compound, and this energy is transferred to the phosphorescent dopant. It is an energy transfer type to obtain light emission from the phosphorescent dopant. The other is a carrier trap type in which a phosphorescent dopant serves as a carrier trap, and carrier recombination occurs on the phosphorescent dopant to emit light from the phosphorescent dopant. In any case, it is a condition that the excited state energy of the phosphorescent dopant is lower than the excited state energy of the host compound.
As a phosphorescence dopant which can be used in this invention, it can select from the well-known thing used for the light emitting layer of an organic EL element suitably, and can use it.
　本発明に使用できる公知のリン光ドーパントの具体例としては、以下の文献に記載されている化合物等が挙げられる。
　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、米国特許出願公開第２００６／８３５４６９号明細書、米国特許出願公開第２００６／０２０２１９４号明細書、米国特許出願公開第２００７／００８７３２１号明細書、米国特許出願公開第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、米国特許出願公開第２００２／００３４６５６号明細書、米国特許第７３３２２３２号明細書、米国特許出願公開第２００９／０１０８７３７号明細書、米国特許出願公開第２００９／００３９７７６号明細書、米国特許第６９２１９１５号明細書、米国特許第６６８７２６６号明細書、米国特許出願公開第２００７／０１９０３５９号明細書、米国特許出願公開第２００６／０００８６７０号明細書、米国特許出願公開第２００９／０１６５８４６号明細書、米国特許出願公開第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、米国特許出願公開第２００６／０２６３６３５号明細書、米国特許出願公開第２００３／０１３８６５７号明細書、米国特許出願公開第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、米国特許出願公開第２００６／０２５１９２３号明細書、米国特許出願公開第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、米国特許出願公開第２００７／０１９０３５９号明細書、米国特許出願公開第２００８／０２９７０３３号明細書、米国特許第７３３８７２２号明細書、米国特許出願公開第２００２／０１３４９８４号明細書、米国特許第７２７９７０４号明細書、米国特許出願公開第２００６／０９８１２０号明細書、米国特許出願公開第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、米国特許出願公開第２０１２／２２８５８３号明細書、米国特許出願公開第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。
　中でも、好ましいリン光ドーパントとしてはＩｒを中心金属に有する有機金属錯体が挙げられる。更に好ましくは、金属－炭素結合、金属－窒素結合、金属－酸素結合及び金属－硫黄結合のうち、少なくとも一つの配位様式を含む錯体が好ましい。 Specific examples of known phosphorescent dopants that can be used in the present invention include compounds described in the following documents.
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 Application Publication No. 2006/835469, US Patent Application Publication No. 2006. No. 0202194, U.S. Patent Application Publication No. 2007/0087321, U.S. Patent Application 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 Application Publication No. 2002/0034656, and US Pat. No. 7,332,232. United States Patent Application Publication No. 2009/0108737, United States Patent Application Publication No. 2009/0039776, United States Patent No. 6921915, United States Patent No. 6,687,266, United States Patent Application Publication No. 2007/0190359. No., US Patent Application Publication No. 2006/0008670, US Patent Application Publication No. 2009/0165846, US Patent Application Publication No. 2008/0015355, US Pat. No. 7,250,226, US Patent No. 7396598 Writing, U.S. Patent Application Publication No. 2006/0263635, U.S. Patent Application Publication No. 2003/0138657, U.S. Patent Application 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 Application Publication No. 2006/0251923, US Patent Application Publication No. 2005/0260441, US Pat. No. 7,393,599. No. 7, U.S. Pat. No. 7,534,505, U.S. Pat. No. 7,445,855, U.S. Patent Application Publication No. 2007/0190359, U.S. Patent Application Publication No. 2008/0297033, U.S. Pat. No. 7,338,722. Letter, United States Published Patent Application No. 2002/0134984, U.S. Pat. No. 7,279,704, U.S. Patent Application Publication No. 2006/098120, U.S. Patent Application Publication No. 2006/103874, International Publication No. 2005/076380. International Publication No. 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. Publication No. 2009/113646, International Publication No. 2012/020327, International Publication No. 2011/051404, International Publication No. 2011/004639, International Publication No. 2011/073149, US Patent Application Publication No. 2012/228583 , Rice JP 2012/212126 A, JP 2012-069737 A, JP 2012-195554 A, JP 2009-114086 A, JP 2003-81988 A, JP 2002-302671 A. Japanese Patent Laid-Open No. 2002-363552.
Among these, a preferable phosphorescent dopant includes an organometallic complex having Ir as a central metal. More preferably, a complex containing at least one coordination mode among metal-carbon bond, metal-nitrogen bond, metal-oxygen bond and metal-sulfur bond is preferable.
［２－２］一般式（１）で表されるリン光発光性金属錯体ドーパント [2-2] Phosphorescent metal complex dopant represented by the general formula (1)
　本発明に係る発光層に含有されるリン光発光性金属錯体ドーパントとしては、下記一般式（１）で表されるリン光発光性金属錯体ドーパントが好ましい。
　すなわち、中心金属に配位結合する環が、ピリジン、ピリミジン等電子欠乏性の含窒素芳香族複素環である構造に比較し、一般式（１）のようにイミダゾール、ピラゾール、トリアゾール等の電子供与性の含窒素芳香族複素環である構造の方が、ＨＯＭＯ準位が高くなるために、キャリアトラップとなりやすく、ホスト化合物の励起状態を生成しにくく、より効果を奏しやすいと考えられる。 The phosphorescent metal complex dopant contained in the light emitting layer according to the present invention is preferably a phosphorescent metal complex dopant represented by the following general formula (1).
That is, compared to the structure in which the ring coordinated to the central metal is an electron-deficient nitrogen-containing aromatic heterocycle such as pyridine and pyrimidine, electron donation of imidazole, pyrazole, triazole, etc. as shown in general formula (1) It is considered that the structure which is a natural nitrogen-containing aromatic heterocycle has a higher HOMO level, so that it is more likely to be a carrier trap, an excited state of the host compound is not easily generated, and more effective.
Figure JPOXMLDOC01-appb-C000005
Figure JPOXMLDOC01-appb-C000005
　一般式（１）中、Ｍは、Ｉｒ、Ｐｔ、Ｒｈ、Ｒｕ、Ａｇ、Ｃｕ又はＯｓを表す。Ａ１及びＡ２は、各々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員の芳香族複素環を表す。Ｂ１～Ｂ５は、５員の芳香族複素環を形成する原子群であり、置換基を有していても良い炭素原子、窒素原子、酸素原子又は硫黄原子を表す。環Ｚ１は、置換基を有していても良く、更に置換基同士が結合して縮環構造を形成していても良い。Ｌは、Ｍに配位したモノアニオン性の二座配位子を表す。Ｍに配位した各々の配位子は、その置換基が互いに結合して配位子同士が連結していても良い。ｍは、０～２の整数を表し、ｎは、１～３の整数を表し、ｍ＋ｎは、２又は３である。ｍ及びｎが各々２以上のとき、環Ｚ１、Ｂ１～Ｂ５で表される芳香族複素環基及びＬは各々同じであっても異なっていても良い。 In general formula (1), M represents Ir, Pt, Rh, Ru, Ag, Cu, or Os. A 1 and A 2 each represent a carbon atom or a nitrogen atom. Ring Z 1 represents a 6-membered aromatic hydrocarbon ring or 5-membered or 6-membered aromatic heterocycle formed together with A 1 and A 2 . B 1 to B 5 are a group of atoms that form a 5-membered aromatic heterocyclic ring, and represent a carbon atom, nitrogen atom, oxygen atom or sulfur atom which may have a substituent. Ring Z 1 may have a substituent, and the substituents may be bonded to each other to form a condensed ring structure. L represents a monoanionic bidentate ligand coordinated to M. Each of the ligands coordinated to M may have their substituents bonded to each other and linked together. m represents an integer of 0 to 2, n represents an integer of 1 to 3, and m + n is 2 or 3. When m and n are each 2 or more, the aromatic heterocyclic groups represented by the rings Z 1 and B 1 to B 5 and L may be the same or different.
　一般式（１）において、環Ｚ１により形成される６員の芳香族炭化水素環又は５員若しくは６員の芳香族複素環としては、例えば、ベンゼン環、ピリジン環、ピリミジン環、ピロール環、チオフェン環、ピラゾール環、イミダゾール環、オキサゾール環及びチアゾール環等が挙げられる。これらのうちで好ましいものは、ベンゼン環である。
　環Ｚ１は置換基を有していても良く、更に置換基同士が結合して縮環構造を形成していても良い。 In the general formula (1), examples of the 6-membered aromatic hydrocarbon ring or 5-membered or 6-membered aromatic heterocycle formed by the ring Z 1 include a benzene ring, a pyridine ring, a pyrimidine ring, a pyrrole ring, Examples include a thiophene ring, a pyrazole ring, an imidazole ring, an oxazole ring, and a thiazole ring. Of these, a benzene ring is preferred.
Ring Z 1 may have a substituent, and the substituents may be bonded to each other to form a condensed ring structure.
　一般式（１）において、環Ｚ１が有していても良い置換基としては、例えば、アルキル基（例えば、メチル基、エチル基、プロピル基、イソプロピル基、ｔｅｒｔ－ブチル基、ペンチル基、ヘキシル基、オクチル基、ドデシル基、トリデシル基、テトラデシル基、ペンタデシル基等）、シクロアルキル基（例えば、シクロペンチル基、シクロヘキシル基等）、アルケニル基（例えば、ビニル基、アリル基等）、アルキニル基（例えば、エチニル基、プロパルギル基等）、芳香族炭化水素環基（芳香族炭素環基、アリール基等ともいい、例えば、フェニル基、ｐ－クロロフェニル基、メシチル基、トリル基、キシリル基、ナフチル基、アントリル基、アズレニル基、アセナフテニル基、フルオレニル基、フェナントリル基、インデニル基、ピレニル基、ビフェニリル基等）、芳香族複素環基（例えば、ピリジル基、ピリミジニル基、フリル基、ピロリル基、イミダゾリル基、ベンゾイミダゾリル基、ピラゾリル基、ピラジニル基、トリアゾリル基（例えば、１，２，４－トリアゾール－１－イル基、１，２，３－トリアゾール－１－イル基等）、オキサゾリル基、ベンゾオキサゾリル基、チアゾリル基、イソオキサゾリル基、イソチアゾリル基、フラザニル基、チエニル基、キノリル基、ベンゾフリル基、ジベンゾフリル基、ベンゾチエニル基、ジベンゾチエニル基、インドリル基、カルバゾリル基、カルボリニル基、ジアザカルバゾリル基（前記カルボリニル基のカルボリン環を構成する炭素原子の一つが窒素原子で置き換わったものを示す。）、キノキサリニル基、ピリダジニル基、トリアジニル基、キナゾリニル基、フタラジニル基等）、複素環基（例えば、ピロリジル基、イミダゾリジル基、モルホリル基、オキサゾリジル基等）、アルコキシ基（例えば、メトキシ基、エトキシ基、プロピルオキシ基、ペンチルオキシ基、ヘキシルオキシ基、オクチルオキシ基、ドデシルオキシ基等）、シクロアルコキシ基（例えば、シクロペンチルオキシ基、シクロヘキシルオキシ基等）、アリールオキシ基（例えば、フェノキシ基、ナフチルオキシ基等）、アルキルチオ基（例えば、メチルチオ基、エチルチオ基、プロピルチオ基、ペンチルチオ基、ヘキシルチオ基、オクチルチオ基、ドデシルチオ基等）、シクロアルキルチオ基（例えば、シクロペンチルチオ基、シクロヘキシルチオ基等）、アリールチオ基（例えば、フェニルチオ基、ナフチルチオ基等）、アルコキシカルボニル基（例えば、メチルオキシカルボニル基、エチルオキシカルボニル基、ブチルオキシカルボニル基、オクチルオキシカルボニル基、ドデシルオキシカルボニル基等）、アリールオキシカルボニル基（例えば、フェニルオキシカルボニル基、ナフチルオキシカルボニル基等）、スルファモイル基（例えば、アミノスルホニル基、メチルアミノスルホニル基、ジメチルアミノスルホニル基、ブチルアミノスルホニル基、ヘキシルアミノスルホニル基、シクロヘキシルアミノスルホニル基、オクチルアミノスルホニル基、ドデシルアミノスルホニル基、フェニルアミノスルホニル基、ナフチルアミノスルホニル基、２－ピリジルアミノスルホニル基等）、アシル基（例えば、アセチル基、エチルカルボニル基、プロピルカルボニル基、ペンチルカルボニル基、シクロヘキシルカルボニル基、オクチルカルボニル基、２－エチルヘキシルカルボニル基、ドデシルカルボニル基、フェニルカルボニル基、ナフチルカルボニル基、ピリジルカルボニル基等）、アシルオキシ基（例えば、アセチルオキシ基、エチルカルボニルオキシ基、ブチルカルボニルオキシ基、オクチルカルボニルオキシ基、ドデシルカルボニルオキシ基、フェニルカルボニルオキシ基等）、アミド基（例えば、メチルカルボニルアミノ基、エチルカルボニルアミノ基、ジメチルカルボニルアミノ基、プロピルカルボニルアミノ基、ペンチルカルボニルアミノ基、シクロヘキシルカルボニルアミノ基、２－エチルヘキシルカルボニルアミノ基、オクチルカルボニルアミノ基、ドデシルカルボニルアミノ基、フェニルカルボニルアミノ基、ナフチルカルボニルアミノ基等）、カルバモイル基（例えば、アミノカルボニル基、メチルアミノカルボニル基、ジメチルアミノカルボニル基、プロピルアミノカルボニル基、ペンチルアミノカルボニル基、シクロヘキシルアミノカルボニル基、オクチルアミノカルボニル基、２－エチルヘキシルアミノカルボニル基、ドデシルアミノカルボニル基、フェニルアミノカルボニル基、ナフチルアミノカルボニル基、２－ピリジルアミノカルボニル基等）、ウレイド基（例えば、メチルウレイド基、エチルウレイド基、ペンチルウレイド基、シクロヘキシルウレイド基、オクチルウレイド基、ドデシルウレイド基、フェニルウレイド基ナフチルウレイド基、２－ピリジルアミノウレイド基等）、スルフィニル基（例えば、メチルスルフィニル基、エチルスルフィニル基、ブチルスルフィニル基、シクロヘキシルスルフィニル基、２－エチルヘキシルスルフィニル基、ドデシルスルフィニル基、フェニルスルフィニル基、ナフチルスルフィニル基、２－ピリジルスルフィニル基等）、アルキルスルホニル基（例えば、メチルスルホニル基、エチルスルホニル基、ブチルスルホニル基、シクロヘキシルスルホニル基、２－エチルヘキシルスルホニル基、ドデシルスルホニル基等）、アリールスルホニル基又はヘテロアリールスルホニル基（例えば、フェニルスルホニル基、ナフチルスルホニル基、２－ピリジルスルホニル基等）、アミノ基（例えば、アミノ基、エチルアミノ基、ジメチルアミノ基、ブチルアミノ基、シクロペンチルアミノ基、２－エチルヘキシルアミノ基、ドデシルアミノ基、アニリノ基、ナフチルアミノ基、２－ピリジルアミノ基等）、シアノ基、ニトロ基、ヒドロキシ基、メルカプト基、シリル基（例えば、トリメチルシリル基、トリイソプロピルシリル基、トリフェニルシリル基、フェニルジエチルシリル基等）等が挙げられる。これらの置換基のうち、好ましいものはアルキル基又はアリール基である。 In the general formula (1), examples of the substituent that the ring Z 1 may have include, for example, an alkyl group (eg, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group). Group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group etc.), cycloalkyl group (eg cyclopentyl group, cyclohexyl group etc.), alkenyl group (eg vinyl group, allyl group etc.), alkynyl group (eg Ethynyl group, propargyl group, etc.), aromatic hydrocarbon ring group (also called aromatic carbocyclic group, aryl group, etc.), for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, naphthyl group, Anthryl, azulenyl, acenaphthenyl, fluorenyl, phenanthryl, indenyl, pyreth Nyl group, biphenylyl group, etc.), aromatic heterocyclic group (for example, pyridyl group, pyrimidinyl group, furyl group, pyrrolyl group, imidazolyl group, benzoimidazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group (for example, 1,2,4) -Triazol-1-yl group, 1,2,3-triazol-1-yl group, etc.), oxazolyl group, benzoxazolyl group, thiazolyl group, isoxazolyl group, isothiazolyl group, furazanyl group, thienyl group, quinolyl group, Benzofuryl group, dibenzofuryl group, benzothienyl group, dibenzothienyl group, indolyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (one of the carbon atoms constituting the carboline ring of the carbolinyl group is replaced by a nitrogen atom) ), Quinoxalinyl group, pyridazinyl , Triazinyl group, quinazolinyl group, phthalazinyl group, etc.), heterocyclic group (eg, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (eg, methoxy group, ethoxy group, propyloxy group, pentyloxy group) Hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (eg, , Methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (for example, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (for example, phenoxy group) Ruthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxy) Carbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecyl) Aminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (eg, acetyl group, ethyl Carbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyl) Oxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, Propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino , Dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl) Group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, Pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoure ), Sulfinyl groups (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.) ), Alkylsulfonyl groups (eg, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl groups or heteroarylsulfonyl groups (eg, phenylsulfonyl group) Naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclope Nylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc., cyano group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group) Group, triphenylsilyl group, phenyldiethylsilyl group, etc.). Of these substituents, preferred are an alkyl group and an aryl group.
　一般式（１）において、Ｂ１～Ｂ５は、炭素原子、窒素原子、酸素原子又は硫黄原子を表し、少なくとも一つが窒素原子を表すことが好ましい。
　また、これら五つの原子により形成される芳香族含窒素複素環としては単環が好ましい。例えば、ピロール環、ピラゾール環、イミダゾール環、トリアゾール環、テトラゾール環、オキサゾール環、イソオキサゾール環、チアゾール環、イソチアゾール環、オキサジアゾール環及びチアジアゾール環等が挙げられる。これらのうちで好ましいものは、ピラゾール環、イミダゾール環であり、特に好ましくはＢ２及びＢ５が窒素原子であるイミダゾール環である。これらの環は上記した環Ｚ１が有していても良い置換基によって更に置換されていても良い。Ｂ１～Ｂ５で表される芳香族複素環が有していても良い置換基として好ましいものはアルキル基及びアリール基であり、更に好ましくはアリール基である。 In the general formula (1), B 1 to B 5 each represent a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom, and preferably at least one represents a nitrogen atom.
A monocyclic ring is preferable as the aromatic nitrogen-containing heterocycle formed by these five atoms. Examples include pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, oxadiazole ring, and thiadiazole ring. Among these, a pyrazole ring and an imidazole ring are preferable, and an imidazole ring in which B 2 and B 5 are nitrogen atoms is particularly preferable. These rings may be further substituted with the substituent which ring Z 1 may have. Preferable substituents that the aromatic heterocyclic ring represented by B 1 to B 5 may have are an alkyl group and an aryl group, and more preferably an aryl group.
　一般式（１）において、Ｌで表されるモノアニオン性の二座配位子の具体例としては、例えば、置換又は無置換のフェニルピリジン、フェニルピラゾール、フェニルイミダゾール、フェニルトリアゾール、フェニルテトラゾール、ピラザボル、ピコリン酸及びアセチルアセトン等が挙げられる。これらの基は上記した環Ｚ１が有していても良い置換基によって更に置換されていても良い。 In the general formula (1), specific examples of the monoanionic bidentate ligand represented by L include, for example, substituted or unsubstituted phenylpyridine, phenylpyrazole, phenylimidazole, phenyltriazole, phenyltetrazole, and pyrazabol. And picolinic acid and acetylacetone. These groups may be further substituted with the substituent which ring Z 1 may have.
　一般式（１）において、ｍは、０～２の整数を表し、ｎは、１～３の整数を表し、ｍ＋ｎは、２又は３であるが、ｍが０である場合が好ましい。 In the general formula (1), m represents an integer of 0 to 2, n represents an integer of 1 to 3, and m + n is 2 or 3, but m is preferably 0.
　一般式（１）において、Ｍは、Ｉｒ、Ｐｔ、Ｒｈ、Ｒｕ、Ａｇ、Ｃｕ又はＯｓを表すが、中でもイリジウム、白金が好ましく、更に好ましくはイリジウムである。 In the general formula (1), M represents Ir, Pt, Rh, Ru, Ag, Cu or Os. Among them, iridium and platinum are preferable, and iridium is more preferable.
［２－３］好ましいリン光発光性金属錯体ドーパントの具体例
　本発明に係る発光層に含有されるリン光発光性金属錯体ドーパントとしては、発光極大波長が４６５ｎｍ（２．６７ｅＶ）以下であることが好ましい。
　以下に、本発明において好ましく用いられるリン光発光性金属錯体ドーパント（上記一般式（１）で表されるリン光発光性金属錯体ドーパントを含む。）を示すが、これらに限定されるものではない。 [2-3] Specific examples of preferred phosphorescent metal complex dopant The phosphorescent metal complex dopant contained in the light emitting layer according to the present invention has an emission maximum wavelength of 465 nm (2.67 eV) or less. Is preferred.
The phosphorescent metal complex dopants preferably used in the present invention (including the phosphorescent metal complex dopant represented by the general formula (1)) are shown below, but are not limited thereto. .
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
　これらのリン光発光性金属錯体ドーパントの発光極大波長（ｎｍ）を表１に示す。発光極大波長は、リン光発光性金属錯体ドーパントを２－ｍｅｔｈｙｌＴｅｔｒａｈｙｄｒｏｆｕｒａｎに溶解させ、３００Ｋにおいて測定したスペクトルの発光極大波長である。 The emission maximum wavelengths (nm) of these phosphorescent metal complex dopants are shown in Table 1. The light emission maximum wavelength is the light emission maximum wavelength of a spectrum measured at 300 K by dissolving a phosphorescent metal complex dopant in 2-methyltetrahydrofuran.
Figure JPOXMLDOC01-appb-T000012
Figure JPOXMLDOC01-appb-T000012
［２－４］蛍光ドーパント
　本発明において、上記リン光発光性金属錯体ドーパントと併用可能な蛍光ドーパント（蛍光発光性ドーパントともいう。）は、励起一重項からの発光が可能な化合物であり、励起一重項からの発光が観測される限り特に限定されない。
　本発明に用いられる蛍光ドーパントとしては、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。 [2-4] Fluorescent dopant In the present invention, a fluorescent dopant (also referred to as a fluorescent luminescent dopant) that can be used in combination with the above phosphorescent metal complex dopant is a compound that can emit light from an excited singlet and is excited. There is no particular limitation as long as light emission from a singlet is observed.
Examples of the fluorescent dopant used in the present invention include anthracene derivatives, pyrene derivatives, chrysene derivatives, fluoranthene derivatives, perylene derivatives, fluorene derivatives, arylacetylene derivatives, styrylarylene derivatives, styrylamine derivatives, arylamine derivatives, boron complexes, coumarins. 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.
［３］一重項エネルギー移動効率
　本発明においてＴＡＤＦホスト化合物からリン光発光性金属錯体ドーパントへの一重項エネルギー移動効率は、１０～１００％の範囲内に設定されている。なお、ＴＡＤＦホスト化合物の発光が短波長である程、ＴＡＤＦホスト化合物の蛍光発光スペクトルとリン光発光性金属錯体ドーパントの吸収スペクトルとの重なりが増加し、一重項エネルギー移動効率が増加する。
　本発明において、一重項エネルギー移動効率は、ＴＡＤＦホスト化合物単独膜の即時成分の蛍光寿命τ０、ＴＡＤＦホスト化合物にドーパントをドープした膜のＴＡＤＦ即時成分の蛍光寿命τ１から下式によって算出することができる。なお、即時成分（Ｐｒｏｍｐｔ成分ともいう。）とはＴＡＤＦホスト化合物が励起光で励起された後、その励起状態から即座に観測される発光を意味し、励起後即座には観測されず一定時間経過後に観察される遅延成分（Ｄｅｌａｙ成分ともいう。）と区別される発光のことをいう。 [3] Singlet energy transfer efficiency In the present invention, the singlet energy transfer efficiency from the TADF host compound to the phosphorescent metal complex dopant is set in the range of 10 to 100%. Note that as the emission of the TADF host compound has a shorter wavelength, the overlap between the fluorescence emission spectrum of the TADF host compound and the absorption spectrum of the phosphorescent metal complex dopant increases, and the singlet energy transfer efficiency increases.
In the present invention, the singlet energy transfer efficiency can be calculated by the following equation from the fluorescence lifetime τ0 of the immediate component of the TADF host compound alone film and the fluorescence lifetime τ1 of the TADF immediate component of the film doped with the dopant to the TADF host compound. . The immediate component (also referred to as the Prompt component) means light emission that is immediately observed from the excited state after the TADF host compound is excited with the excitation light, and is not observed immediately after the excitation, and a certain time has elapsed. This refers to light emission that is distinguished from a delayed component (also referred to as a delay component) that is observed later.
Figure JPOXMLDOC01-appb-M000013
Figure JPOXMLDOC01-appb-M000013
　ＴＡＤＦホスト化合物の一重項エネルギー移動効率が高いほど、三重項エネルギーが逆項間交差したときに一重項エネルギーが速やかにドーパントに移動するため、ＴＡＤＦホスト化合物が高いエネルギー状態に滞在する時間が短く、結合開裂による分解等からの消光物質の生成を抑制することができると考えられる。
　また、より好ましくは、ＴＡＤＦホスト化合物の最大の発光ピーク強度が、ドーパントの最大の発光ピーク強度の１０％以下である。 The higher the singlet energy transfer efficiency of the TADF host compound, the faster the singlet energy is transferred to the dopant when the triplet energy crosses the reverse intersystem, so the time for the TADF host compound to stay in a high energy state is short, It is thought that the production | generation of the quenching substance from the decomposition | disassembly etc. by bond cleavage can be suppressed.
More preferably, the maximum emission peak intensity of the TADF host compound is 10% or less of the maximum emission peak intensity of the dopant.
［４］ＴＡＤＦホスト化合物の蛍光発光スペクトルとリン光発光性金属錯体ドーパントの吸収スペクトルとの重なり
　本発明においては、ＴＡＤＦホスト化合物の蛍光発光スペクトルが、リン光発光性金属錯体ドーパントの吸収スペクトルと１×１０１４ｎｍ４（ｍｏｌ／Ｌ）－１ｃｍ－１以上の重なりを有することが好ましい。
　リン光発光性金属錯体ドーパントのモル吸光係数ε（λ）（ｍｏｌ－１ｃｍ－１Ｌ）、ＴＡＤＦホスト化合物の蛍光発光スペクトルｆ（λ）、配向因子κ、屈折率ｎ、ＴＡＤＦホスト化合物の量子収率Φ、ホスト－ドーパント間の距離ｒから、下記式に基づきフェルスター半径Ｒ０及びエネルギー移動効率Ｅを算出することができる。なお、ホストの蛍光発光スペクトルは∫ｆ（ν）ｄν＝１に規格化したものを用いて計算する。また、下記式中、ＴＡＤＦホスト化合物の蛍光発光スペクトルとリン光発光性金属錯体ドーパントの吸収スペクトルとの重なりは、∫ｆ（λ）ε（λ）λ（ｎｍ）４ｄλで表される。 [4] Overlap of the fluorescence emission spectrum of the TADF host compound and the absorption spectrum of the phosphorescent metal complex dopant In the present invention, the fluorescence emission spectrum of the TADF host compound is the absorption spectrum of the phosphorescent metal complex dopant and 1 It is preferable to have an overlap of × 10 14 nm 4 (mol / L) −1 cm −1 or more.
Phosphorescent metal complex dopant molar extinction coefficient ε (λ) (mol −1 cm −1 L), TADF host compound fluorescence emission spectrum f (λ), orientation factor κ, refractive index n, TADF host compound quantum From the yield Φ and the distance r between the host and the dopant, the Forster radius R 0 and the energy transfer efficiency E can be calculated based on the following equations. Note that the fluorescence emission spectrum of the host is calculated using the one normalized to ∫f (ν) dν = 1. In the following formula, the overlap between the fluorescence emission spectrum of the TADF host compound and the absorption spectrum of the phosphorescent metal complex dopant is represented by ∫f (λ) ε (λ) λ (nm) 4 dλ.
Figure JPOXMLDOC01-appb-M000014
Figure JPOXMLDOC01-appb-M000014
Figure JPOXMLDOC01-appb-M000015
Figure JPOXMLDOC01-appb-M000015
　ここで、ドーパントのドープ濃度５ｖｏｌ％、１０ｖｏｌ％における各分子量に対するドーパント分子間の平均距離ｒ及びエネルギー移動効率Ｅを表２に示す。
　上記式で算出された重なりが１×１０１４以上であると、フェルスター半径Ｒ０（熱活性化型遅延蛍光発光性のホスト化合物からリン光発光性金属錯体ドーパントへのエネルギー移動速度が、熱活性化型遅延蛍光発光性のホスト化合物自身での失活速度と等しくなる距離）が２９オングストローム（ランダム配向仮定時（κ＝２／３）、屈折率１．６を想定）となり、表２に示すドープ濃度１０ｖｏｌ％のドーパント分子間の平均距離の半分よりも大きくなる。このため、ＴＡＤＦホスト化合物上で再結合して生成した三重項励起子を逆項間交差した一重項励起子から、近傍のドーパントへ効果的にエネルギー移動し、ＴＡＤＦホスト化合物上でのＳ１励起状態の滞留を抑制することができる。なお、ドーパント分子間の平均距離は、（ドーパントの数密度）－１／３で求められ、ドーパントの分子量、膜密度、ドーパント濃度を用いて求められる。 Here, Table 2 shows the average distance r between the dopant molecules and the energy transfer efficiency E with respect to each molecular weight at a dopant doping concentration of 5 vol% and 10 vol%.
When the overlap calculated by the above formula is 1 × 10 14 or more, the Förster radius R 0 (the energy transfer rate from the thermally activated delayed fluorescence host compound to the phosphorescent metal complex dopant is The distance equal to the deactivation rate of the activated delayed fluorescent host compound itself is 29 angstroms (when assuming random orientation (κ = 2/3), assuming a refractive index of 1.6). It becomes larger than half of the average distance between dopant molecules having a doping concentration of 10 vol%. For this reason, the triplet excitons generated by recombination on the TADF host compound effectively transfer energy from the singlet exciton crossing the reverse term to the neighboring dopant, and S 1 excitation on the TADF host compound. The retention of the state can be suppressed. The average distance between dopant molecules is determined by (number density of dopant) −1/3 , and is determined using the molecular weight of the dopant, the film density, and the dopant concentration.
《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良い。
　本発明に用いられる電子輸送層の総層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。
　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、電子輸送層の層厚を数ｎｍ～数μｍ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。 《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.
The total thickness of the electron transport layer used in 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.
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 thickness of the electron transport layer between several nanometers and several micrometers.
　一方で、電子輸送層の層厚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。
　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良く、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。 On the other hand, when the layer thickness of the electron transport layer is increased, the voltage is likely to increase. Therefore, particularly when the layer thickness is large, 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 (hereinafter referred to as an electron transport material) may have any of an electron injection property or a transport property, and a hole barrier property. Any one 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、発光層の材料として例示した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。
　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。 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 transport material. In addition, the distyrylpyrazine derivative exemplified as the material for the light emitting layer can also be used as an electron transport material, and an inorganic semiconductor such as n-type-Si, n-type-SiC, etc. as in the case of the hole injection layer and the hole transport layer. Can also be used as an electron transporting material.
Further, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.
　本発明に用いられ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良い。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 used in the present invention, an 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、本発明はこれらに限定されない。
　米国特許第６５２８１８７号明細書、米国特許第７２３０１０７号明細書、米国特許出願公開第２００５／００２５９９３号明細書、米国特許出願公開第２００４／００３６０７７号明細書、米国特許出願公開第２００９／０１１５３１６号明細書、米国特許出願公開第２００９／０１０１８７０号明細書、米国特許出願公開第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、米国特許出願公開第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、ＥＰ２３１１８２６号、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。 Specific examples of known preferable electron transport materials used in the organic EL device of the present invention include compounds described in the following documents, but the present invention is not limited thereto.
US Pat. No. 6,528,187, US Pat. No. 7,230,107, US Patent Application Publication No. 2005/0025993, US Patent Application Publication No. 2004/0036077, US Patent Application Publication No. 2009/0115316 U.S. Patent Application Publication No. 2009/0101870, U.S. Patent Application Publication No. 2009/0179554, International Publication No. 2003/060956, International Publication No. 2008/120855, 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 Application Publication No. 2009/030202, International Publication No. 2004/080975, International Publication No. 2004/063159, International Publication No. 2005/085387. No., International Publication No. 2006/067931, International Publication No. 2007/086552, 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, EP23111826, JP2010-251675A, JP2009-209133A, JP2009-124114A. JP 2008-277810 A, JP 2006-156445 A, JP 2005-340122 A, JP 2003-45662 A, JP 2003-31367 A, JP 2003-282270 A, 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。
　電子輸送材料は単独で用いても良く、また複数種を併用して用いても良い。 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 materials 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。
　また、前述する電子輸送層の構成を必要に応じて、本発明に用いられる正孔阻止層として用いることができる。
　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。
　本発明に用いられる正孔阻止層の層厚としては、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。
　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。 《Hole blocking layer》
The hole blocking layer is a layer having the 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. By blocking the holes, the probability of recombination of electrons and holes can be improved.
Moreover, the structure of the electron carrying layer mentioned above can be used as a hole-blocking layer used for this invention as needed.
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 layer thickness of the hole blocking layer used in the present invention is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.
As a material used for a hole-blocking layer, the material used for the above-mentioned electron transport layer is preferably used, and the material used as the other host compound is also preferably used for the hole-blocking layer.
《電子注入層》
　本発明に用いられる電子注入層（「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。
　本発明において電子注入層は必要に応じて設け、上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良い。
　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層厚は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良い。 《Electron injection layer》
The electron injection layer (also referred to as “cathode buffer layer”) used in 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. 2 and Chapter 2 “Electrode Materials” (pages 123 to 166) of the 2nd volume of “The Forefront of Industrialization” (published by NTT Corporation on November 30, 1998).
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.
The electron injection layer is preferably a very thin film, and the layer thickness is preferably in the range of 0.1 to 5 nm depending on the material. Further, it may be a non-uniform film in which constituent materials are present intermittently.
　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。
　また、上記の電子注入層に用いられる材料は単独で用いても良く、複数種を併用して用いても良い。 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.
Moreover, the material used for said electron injection layer may be used independently, and may be used in combination of multiple types.
《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良い。
　本発明に用いられる正孔輸送層の総層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５～２００ｎｍである。
　正孔輸送層に用いられる材料（以下、正孔輸送材料ともいう。）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良く、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。 《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.
The total thickness of the hole transport layer used in 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 to 200 nm.
A material used for the hole transport layer (hereinafter also referred to as a hole transport material) may have any of a hole injection property or a transport property, and an electron barrier property. 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。
　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。
　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。 Examples of the triarylamine derivative include a benzidine type typified by α-NPD, a starburst type typified by MTDATA, and a compound having fluorene or anthracene in the triarylamine linking core part.
In addition, hexaazatriphenylene derivatives such as those described in JP-T-2003-519432 and JP-A-2006-135145 can also be used as hole transport materials.
Furthermore, a hole transport layer having a high p property doped with impurities may 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（Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．，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Ｐｔ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. A so-called p-type hole transport material or an inorganic compound such as p-type-Si or p-type-SiC, as described in the literature (Appl. Phys. Lett., 80 (2002), p. 139) is used. You can also. Further, ortho-metalated organometallic complexes having Ir or Pt as a central metal as typified by Ir (ppy) 3 are also preferably used.
　正孔輸送材料としては、上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。
　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、上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、本発明はこれらに限定されない。
　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）、米国特許出願公開第２００３／０１６２０５３号明細書、米国特許出願公開第２００２／０１５８２４２号明細書、米国特許出願公開第２００６／０２４０２７９号明細書、米国特許出願公開第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、欧州特許出願公開第０６５０９５５号明細書、米国特許出願公開第２００８／０１２４５７２号明細書、米国特許出願公開第２００７／０２７８９３８号明細書、米国特許出願公開第２００８／０１０６１９０号明細書、米国特許出願公開第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、米国特許出願番号第１３／５８５９８１号等である。
　正孔輸送材料は単独で用いても良く、また複数種を併用して用いても良い。 Although the above-mentioned materials can be used as the hole transport material, 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.
Specific examples of known preferred hole transport materials used in the organic EL device of the present invention include the compounds described in the following documents in addition to the documents listed above, but the present invention is not limited thereto. Not.
For example, Appl. Phys. Lett. 69, 2160 (1996); 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 Application Publication No. 2003/0162053, US Patent Application Publication No. 2002/0158242, US Patent Application Publication No. 2006/0240279, US Patent Application Publication No. 2008. No. 0220265, U.S. Pat. No. 5,061,569, WO 2007/002683, WO 2009/018009, EP 0 650 955, U.S. Patent Publication No. 2008/0124572. US Patent Application Publication No. 2007/0278938, US Patent Application Publication No. 2008/0106190, US Patent Application Publication No. 2008/0018221, International Publication No. 2012/115034, Special Table 2003 No. 519432, Special 2006-135145 discloses a U.S. Patent Application No. 13/585981 and the like.
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。
　また、前述する正孔輸送層の構成を必要に応じて、本発明に用いられる電子阻止層として用いることができる。
　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。
　本発明に用いられる電子阻止層の層厚としては、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。
　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。 《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, while transporting holes. By blocking electrons, the probability of recombination of electrons and holes can be improved.
Moreover, the structure of the positive hole transport layer mentioned above can be used as an electron blocking layer used for this invention as needed.
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 used in the present invention is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.
As the material used for the electron blocking layer, the material used for the above-described hole transport layer is preferably used, and the material used as the above-described host compound is also preferably used for the electron blocking layer.
《正孔注入層》
　本発明に用いられる正孔注入層（「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。
　本発明において正孔注入層は必要に応じて設け、上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良い。
　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。 《Hole injection layer》
The hole injection layer (also referred to as “anode buffer layer”) used in the present invention is a layer provided between the anode and the light emitting layer in order to lower the driving voltage or improve the light emission luminance. It is described in detail in the second chapter, Chapter 2, “Electrode Materials” (pages 123 to 166) of “Elements and the Forefront of Industrialization (issued by NTT Corporation on November 30, 1998)”.
In the present invention, the hole injection layer may be provided as necessary, and may exist 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.
　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。
　前述の正孔注入層に用いられる材料は単独で用いても良く、また複数種を併用して用いても良い。 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 and 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.
The materials used for the hole injection layer described above may be used alone or in combination of two or more.
《その他の添加化合物》
　前述した本発明における有機層は、更に他の添加含有物が含まれていても良い。
　添加含有物としては、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。
　添加含有物の含有量は、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。
　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などによってはこの範囲内ではない。 《Other additive compounds》
The organic layer in the present invention described above may further contain other additives.
Examples of the additive content include halogen elements such as bromine, iodine and chlorine, halogenated compounds, alkali metals such as Pd, Ca and Na, alkaline earth metals, transition metal compounds, complexes, and salts.
The content of the additive content can be arbitrarily determined, but is preferably 1000 ppm or less, more preferably 500 ppm or less, still more preferably 50 ppm or less, based on the total mass% of the contained layer. is there.
However, it is not within this range depending on the purpose of improving the transportability of electrons and holes or the purpose of favoring the exciton energy transfer.
《有機層の形成方法》
　本発明に係る有機層（正孔注入層、正孔輸送層、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。
　本発明に係る有機層の形成方法は、特に制限はなく、従来公知の例えば真空蒸着法、湿式法（ウェットプロセスともいう。）等による形成方法を用いることができるが、湿式法により形成することがより好ましい。
　湿式法としては、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、か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、スプレーコート法などのロールｔｏロール方式適性の高い方法が好ましい。 <Method for forming organic layer>
A method for forming an organic layer (hole injection layer, hole transport layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) according to the present invention will be described.
The method for forming the organic layer according to the present invention is not particularly limited, and a conventionally known method such as a vacuum deposition method or a wet method (also referred to as a wet process) can be used. Is more preferable.
Examples of the wet method include spin coating method, casting method, ink jet method, printing method, die coating method, blade coating method, roll coating method, spray coating method, curtain coating method, and LB method (Langmuir-Blodgett method). From the viewpoint of obtaining a homogeneous thin film easily and high productivity, a method having high suitability for a roll-to-roll method such as a die coating method, a roll coating method, an ink jet method, or a spray coating method is preferable.
　本発明の有機ＥＬ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。
　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。 Examples of the liquid medium for dissolving or dispersing the organic EL material of 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, xylene, mesitylene, Aromatic hydrocarbons such as cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as DMF and DMSO can be used.
Moreover, as a dispersion method, it can disperse | distribute by dispersion methods, such as an ultrasonic wave, high shear force dispersion | distribution, and media dispersion | distribution.
　更に層毎に異なる成膜法を適用しても良い。成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℃、層厚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。
　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成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。 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 layer thickness of 0.1 nm to 5 μm, preferably 5 to 200 nm.
The organic layer according to the present invention is preferably formed from the hole injection layer to the cathode consistently by a single evacuation, but it may be taken out halfway and subjected to different film formation 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４．５ｅＶ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・スズ酸化物（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良い。 "anode"
As the anode in the organic EL element, a material having a work function (4 eV or more, preferably 4.5 eV or more) of a metal, an alloy, an electrically conductive compound, or a mixture thereof is preferably used. Specific examples of such an electrode substance include a conductive transparent material such as a metal such as Au, 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良く、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）、上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良い。
　また、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成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／□以下が好ましい。
　陽極の膜厚は材料にもよるが、通常１０ｎｍ～１μｍ、好ましくは１０～２００ｎｍの範囲で選ばれる。 For the anode, a thin film may be formed by vapor deposition or sputtering of these electrode materials, and a pattern with a desired shape may be formed by photolithography, or when pattern accuracy is not so high (about 100 μm or more) A pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material.
In addition, when a material that can be applied, such as an organic conductive compound, is used, a wet film formation 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 preferably several hundred Ω / □ or less.
Although the film thickness of the anode depends on the material, it 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２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 low 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, a mixture of an electron injecting metal and a second metal, which is a stable metal having a larger work function value than this, from the point of durability against electron injection and oxidation, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al 2 O 3 ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred.
　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／□以下が好ましく、膜厚は通常１０ｎｍ～５μｍ、好ましくは５０～２００ｎｍの範囲で選ばれる。
　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。
　また、陰極に上記金属を１～２０ｎｍの膜厚で作製した後に、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。 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 the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm.
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 advantageously improved.
In addition, a transparent or translucent cathode can be produced by producing a conductive transparent material mentioned in the description of the anode on the cathode after producing the above 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良い。支持基板側から光を取り出す場合には、支持基板が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 element of the present invention is not particularly limited in the type of glass, plastic, etc., and is transparent. It may or may not be opaque. When light is extracted 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）又はアペル（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のフィルムが挙げられる。 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 polyarylates, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Film.
　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良く、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）％）が０．０１ｇ／（ｍ２・２４ｈ）以下のガス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）以下の高ガス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)%) of 0.01 g / (m 2 · 24 h) or less is preferable as a gas barrier film. Further, oxygen measured by a method according to JIS K 7126-1987 A high gas 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.
　ガス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良く、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 gas barrier film may be any material as long as it 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, and 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.
　ガス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 gas barrier film is not particularly limited. For example, the vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma weight A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, and 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、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。
　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。
　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。
　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として用いて多色へ変換する色変換フィルターを併用しても良い。 Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, and ceramic substrates.
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.
Here, external extraction quantum efficiency (%) = number of photons emitted to the outside of the organic EL element / number of electrons flowed to the organic EL element × 100.
In addition, 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 the 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良く、凹板状でも、平板状でも良い。また、透明性、電気絶縁性は特に限定されない。
　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。 <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. The sealing member may be disposed so as to cover the display area of the organic EL element, and may be concave or flat. Moreover, transparency and electrical insulation are not particularly limited.
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。
　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。 In the present invention, a polymer film and a metal film can be preferably used because the organic EL element can be thinned. Furthermore, 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 transmission rate (25 ± 0.5 ° C., relative humidity (90 ± 2)%) is preferably that of 1 × 10 -3 g / (m 2 / 24h) or less.
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。
　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良い。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良いし、スクリーン印刷のように印刷しても良い。 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.
In addition, since an organic EL element may deteriorate by heat processing, what can be adhesive-hardened from room temperature to 80 degreeC is preferable. A desiccant may be dispersed in the adhesive. Application of the adhesive to the sealing portion may use a commercially available dispenser, or may be printed 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良く、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, as a material for forming the film, any material may be used as long as it 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。
　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。 Further, in order to 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.
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、保護膜又は保護板を設けても良い。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ことが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、透明電極又は発光層と透明基板との間で光が全反射を起こし、光が透明電極又は発光層を導波し、結果として、光が素子側面方向に逃げるためである。 《Light extraction enhancement 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 element, or between the transparent electrode or light emitting layer and the transparent substrate. This is because the light undergoes total reflection between the light, the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the side surface direction of the element.
　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）などが挙げられる。 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 No. -283751 Publication), and the like.
　本発明においては、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。
　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, these methods can be used in combination with the organic EL device of the present invention. However, 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, transparent A method of forming a diffraction grating between any layers of the electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used.
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。
　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、フッ素系ポリマーなどが挙げられる。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。 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.
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層厚になると、低屈折率層の効果が薄れるからである。
　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、いずれかの層間又は、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 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 diminished 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 in any layer or medium (inside a 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。
　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。
　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、ハニカムラチス状など、二次元的に配列が繰り返されることが好ましい。 The introduced diffraction grating desirably 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.
However, by making the refractive index distribution a two-dimensional distribution, light traveling in all directions is diffracted, and light extraction efficiency is increased.
The position where the diffraction grating is introduced may be in any of the layers 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 gratings 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。
　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。 <Condenser sheet>
The organic EL device of the present invention can be processed to provide, for example, a structure on a microlens array on the light extraction side of a support substrate (substrate), or combined with a so-called condensing sheet, for example, in a specific direction, such as device light emission. Condensing light in the front direction with respect to the surface can increase the luminance in a specific direction.
As an example of the microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are 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）など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良いし、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。
　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良い。例えば、（株）きもと製拡散フィルム（ライトアップ）などを用いることができる。 As the condensing sheet, for example, a sheet that is put into practical use in an LED backlight of a liquid crystal display device can be used. 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 triangle 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.
Moreover, in order to control the light emission angle from an organic EL element, you may use a light-diffusion plate and a film together with a condensing 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。
　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。
　本発明の有機ＥＬ素子においては、必要に応じ成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良い。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良いし、電極と発光層をパターニングしても良いし、素子全層をパターニングしても良く、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。 <Application>
The organic EL element of the present invention can be used as a display device, a display, and various light emission sources.
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.
In the organic EL element of the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like as needed during film formation. 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》
　本発明の有機ＥＬ素子は、表示装置に用いることができる。表示装置は単色でも多色でも良いが、ここでは多色表示装置について説明する。
　多色表示装置の場合は発光層形成時のみシャドーマスクを設け、一面に蒸着法、キャスト法、スピンコート法、インクジェット法、印刷法等で膜を形成できる。
　発光層のみパターニングを行う場合、その方法に限定はないが、好ましくは蒸着法、インクジェット法、スピンコート法、印刷法である。 <Display device>
The organic EL element of the present invention can be used for a display device. The display device may be single color or multicolor, but here, the multicolor display device will be described.
In the case of a multicolor display device, a shadow mask is provided only at the time of forming a light emitting layer, and a film can be formed on one surface by vapor deposition, casting, spin coating, ink jet, printing, or the like.
In the case of patterning only the light emitting layer, the method is not limited. However, the vapor deposition method, the ink jet method, the spin coating method, and the printing method are preferable.
　表示装置に具備される有機ＥＬ素子の構成は、必要に応じて上記の有機ＥＬ素子の構成例の中から選択される。
　また、有機ＥＬ素子の製造方法は、上記の本発明の有機ＥＬ素子の製造の一態様に示したとおりである。
　このようにして得られた多色表示装置に直流電圧を印加する場合には、陽極を＋、陰極を－の極性として電圧２～４０Ｖ程度を印加すると発光が観測できる。また、逆の極性で電圧を印加しても電流は流れずに発光は全く生じない。更に交流電圧を印加する場合には、陽極が＋、陰極が－の状態になったときのみ発光する。なお、印加する交流の波形は任意で良い。 The configuration of the organic EL element provided in the display device is selected from the above-described configuration examples of the organic EL element as necessary.
Moreover, the manufacturing method of an organic EL element is as having shown to the one aspect | mode of manufacture of the organic EL element of said invention.
When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. Further, even when a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Further, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the-state. The alternating current waveform to be applied may be arbitrary.
　多色表示装置は、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。表示デバイス、ディスプレイにおいて、青、赤、緑発光の３種の有機ＥＬ素子を用いることによりフルカラーの表示が可能となる。
　表示デバイス、ディスプレイとしては、テレビ、パソコン、モバイル機器、ＡＶ機器、文字放送表示、自動車内の情報表示等が挙げられる。特に静止画像や動画像を再生する表示装置として使用しても良く、動画再生用の表示装置として使用する場合の駆動方式は単純マトリクス（パッシブマトリクス）方式でもアクティブマトリクス方式でもどちらでも良い。
　発光光源としては、家庭用照明、車内照明、時計や液晶用のバックライト、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、本発明はこれらに限定されない。 The multicolor display device can be used as a display device, a display, and various light emission sources. In a display device or display, full-color display is possible by using three types of organic EL elements of blue, red, and green light emission.
Examples of the display device and display include a television, a personal computer, a mobile device, an AV device, a character broadcast display, and an information display in an automobile. In particular, it may be used as a display device for reproducing still images and moving images, and the driving method when used as a display device for reproducing moving images may be either a simple matrix (passive matrix) method or an active matrix method.
Light emitting sources include home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, etc. However, the present invention is not limited to these.
　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。
　図３は有機ＥＬ素子から構成される表示装置の一例を示した模式図である。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。
　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、表示部Ａと制御部Ｂとを電気的に接続する配線部Ｃ等を有する。
　制御部Ｂは表示部Ａと配線部Ｃを介して電気的に接続され、複数の画素それぞれに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り、走査信号により走査線ごとの画素が画像データ信号に応じて順次発光して画像走査を行って画像情報を表示部Ａに表示する。 Hereinafter, an example of a display device having the organic EL element of the present invention will be described with reference to the drawings.
FIG. 3 is a schematic view showing an example of a display device composed of organic EL elements. It is a schematic diagram of a display such as a mobile phone that displays image information by light emission of an organic EL element.
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, a wiring unit C that electrically connects the display unit A and the control unit B, and the like. .
The control unit B is electrically connected to the display unit A via the wiring unit C, and sends a scanning signal and an image data signal to each of a plurality of pixels based on image information from the outside. Sequentially emit light according to the image data signal, scan the image, and display the image information on the display unit A.
　図４はアクティブマトリクス方式による表示装置の模式図である。
　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Ｃと複数の画素３等とを有する。表示部Ａの主要な部材の説明を以下に行う。
　図３においては、画素３の発光した光（発光光Ｌ）が白矢印方向（下方向）へ取り出される場合を示している。 FIG. 4 is a schematic diagram of a display device using an active matrix method.
The display unit A includes a wiring unit C including a plurality of scanning lines 5 and data lines 6, a plurality of pixels 3 and the like on a substrate. The main members of the display unit A will be described below.
FIG. 3 shows a case where the light emitted from the pixel 3 (the emitted light L) is extracted in the direction of the white arrow (downward).
　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なり、走査線５とデータ線６は格子状に直交して、直交する位置で画素３に接続している（詳細は図示していない。）。
　画素３は、走査線５から走査信号が印加されると、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。
　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置することによって、フルカラー表示が可能となる。 The scanning lines 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a lattice shape and are connected to the pixels 3 at the orthogonal positions (details are shown in FIG. Not shown).
When a scanning signal is applied from the scanning line 5, the pixel 3 receives an image data signal from the data line 6 and emits light according to the received image data.
Full-color display is possible by appropriately arranging pixels in the red region, the green region, and the blue region on the same substrate.
　次に、画素の発光プロセスを説明する。図５は画素の回路を示した概略図である。
　画素は、有機ＥＬ素子１０、スイッチングトランジスタ１１、駆動トランジスタ１２、コンデンサー１３等を備えている。複数の画素に有機ＥＬ素子１０として、赤色、緑色及び青色発光の有機ＥＬ素子を用い、これらを同一基板上に並置することでフルカラー表示を行うことができる。 Next, the light emission process of the pixel will be described. FIG. 5 is a schematic diagram showing a pixel circuit.
The pixel includes an organic EL element 10, a switching transistor 11, a driving transistor 12, a capacitor 13, and the like. A full color display can be performed by using red, green, and blue light emitting organic EL elements as the organic EL elements 10 in a plurality of pixels, and juxtaposing them on the same substrate.
　図５において、制御部Ｂからデータ線６を介してスイッチングトランジスタ１１のドレインに画像データ信号が印加される。そして、制御部Ｂから走査線５を介してスイッチングトランジスタ１１のゲートに走査信号が印加されると、スイッチングトランジスタ１１の駆動がオンし、ドレインに印加された画像データ信号がコンデンサー１３と駆動トランジスタ１２のゲートに伝達される。 In FIG. 5, an image data signal is applied from the control unit B to the drain of the switching transistor 11 through the data line 6. When a scanning signal is applied from the control unit B to the gate of the switching transistor 11 via the scanning line 5, the driving of the switching transistor 11 is turned on, and the image data signal applied to the drain is supplied to the capacitor 13 and the driving transistor 12. Is transmitted to the gate.
　画像データ信号の伝達により、コンデンサー１３が画像データ信号の電位に応じて充電されるとともに、駆動トランジスタ１２の駆動がオンする。駆動トランジスタ１２は、ドレインが電源ライン７に接続され、ソースが有機ＥＬ素子１０の電極に接続されており、ゲートに印加された画像データ信号の電位に応じて電源ライン７から有機ＥＬ素子１０に電流が供給される。 By transmitting the image data signal, the capacitor 13 is charged according to the potential of the image data signal, and the drive transistor 12 is turned on. The drive transistor 12 has a drain connected to the power supply line 7 and a source connected to the electrode of the organic EL element 10, and the power supply line 7 connects to the organic EL element 10 according to the potential of the image data signal applied to the gate. Current is supplied.
　制御部Ｂの順次走査により走査信号が次の走査線５に移ると、スイッチングトランジスタ１１の駆動がオフする。しかし、スイッチングトランジスタ１１の駆動がオフしてもコンデンサー１３は充電された画像データ信号の電位を保持するので、駆動トランジスタ１２の駆動はオン状態が保たれて、次の走査信号の印加が行われるまで有機ＥＬ素子１０の発光が継続する。順次走査により次に走査信号が印加されたとき、走査信号に同期した次の画像データ信号の電位に応じて駆動トランジスタ１２が駆動して有機ＥＬ素子１０が発光する。
　すなわち、有機ＥＬ素子１０の発光は、複数の画素それぞれの有機ＥＬ素子１０に対して、アクティブ素子であるスイッチングトランジスタ１１と駆動トランジスタ１２を設けて、複数の画素３それぞれの有機ＥＬ素子１０の発光を行っている。このような発光方法をアクティブマトリクス方式と呼んでいる。 When the scanning signal is moved to the next scanning line 5 by the sequential scanning of the control unit B, the driving of the switching transistor 11 is turned off. However, since the capacitor 13 holds the charged potential of the image data signal even if the driving of the switching transistor 11 is turned off, the driving of the driving transistor 12 is kept on and the next scanning signal is applied. Until then, the light emission of the organic EL element 10 continues. When the scanning signal is next applied by sequential scanning, the driving transistor 12 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic EL element 10 emits light.
That is, the organic EL element 10 emits light by the switching transistor 11 and the drive transistor 12 that are active elements for the organic EL element 10 of each of the plurality of pixels, and the light emission of the organic EL element 10 of each of the plurality of pixels 3. It is carried out. Such a light emitting method is called an active matrix method.
　ここで、有機ＥＬ素子１０の発光は複数の階調電位を持つ多値の画像データ信号による複数の階調の発光でも良いし、２値の画像データ信号による所定の発光量のオン、オフでも良い。また、コンデンサー１３の電位の保持は次の走査信号の印加まで継続して保持しても良いし、次の走査信号が印加される直前に放電させても良い。
　本発明においては、上述したアクティブマトリクス方式に限らず、走査信号が走査されたときのみデータ信号に応じて有機ＥＬ素子を発光させるパッシブマトリクス方式の発光駆動でも良い。 Here, the light emission of the organic EL element 10 may be light emission of a plurality of gradations by a multi-value image data signal having a plurality of gradation potentials, or by turning on / off a predetermined light emission amount by a binary image data signal. good. The potential of the capacitor 13 may be held continuously until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.
In the present invention, not only the active matrix method described above, but also a passive matrix light emission drive in which the organic EL element emits light according to the data signal only when the scanning signal is scanned.
　図６は、パッシブマトリクス方式による表示装置の模式図である。図６において、複数の走査線５と複数の画像データ線６が画素３を挟んで対向して格子状に設けられている。
　順次走査により走査線５の走査信号が印加されたとき、印加された走査線５に接続している画素３が画像データ信号に応じて発光する。
　パッシブマトリクス方式では画素３にアクティブ素子が無く、製造コストの低減が計れる。
　本発明の有機ＥＬ素子を用いることにより、発光効率が向上した表示装置が得られた。 FIG. 6 is a schematic diagram of a passive matrix display device. In FIG. 6, a plurality of scanning lines 5 and a plurality of image data lines 6 are provided in a lattice shape so as to face each other with the pixel 3 interposed therebetween.
When the scanning signal of the scanning line 5 is applied by sequential scanning, the pixels 3 connected to the applied scanning line 5 emit light according to the image data signal.
In the passive matrix system, the pixel 3 has no active element, and the manufacturing cost can be reduced.
By using the organic EL element of the present invention, a display device with improved luminous efficiency was obtained.
《本発明の照明装置の一態様》
　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。
　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７及び図８に示すような照明装置を形成することができる。
　図７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）で行った。）。
　図８は、照明装置の断面図を示し、図８において、１０５は陰極、１０６は有機ＥＬ層、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。 << One Embodiment of Lighting Device of the Present Invention >>
One aspect of the lighting device of the present invention that includes the organic EL element of the present invention will be described.
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 superimposed 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. 7 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 the sealing operation with the glass cover, the organic EL element 101 is brought into contact with the atmosphere. And a glove box under a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more).
FIG. 8 shows a cross-sectional view of the lighting device. In FIG. 8, 105 denotes a cathode, 106 denotes an organic EL layer, 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.
　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。
　なお、本実施例において用いられる各化合物を以下に示す。 EXAMPLES 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.
In addition, each compound used in a present Example is shown below.
Figure JPOXMLDOC01-appb-C000017
Figure JPOXMLDOC01-appb-C000017
　また、各実施例における化合物の体積％は、形成する膜の膜厚を水晶振動子マイクロバランス法により測定し、質量を算出することで、比重から求めている。 Further, the volume% of the compound in each example is obtained from the specific gravity by measuring the film thickness of the film to be formed by the quartz crystal microbalance method and calculating the mass.
［実施例１］
　本発明に係るＴＡＤＦホスト化合物として上記例示した各ＴＡＤＦ化合物の薄膜を作製し、３００Ｋにおける絶対フォトルミネッセンス（ＰＬ）量子収率及び発光寿命を測定し、熱活性化型遅延蛍光発光性を有しているか否かを確認した。 [Example 1]
As a TADF host compound according to the present invention, a thin film of each of the TADF compounds exemplified above is prepared, measured for absolute photoluminescence (PL) quantum yield and emission lifetime at 300K, and has thermally activated delayed fluorescence. It was confirmed whether or not.
《薄膜１－１の作製》
　まず、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。 << Production of Thin Film 1-1 >>
First, a quartz substrate having a size of 50 mm × 50 mm and a thickness of 0.7 mm was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. Fixed to the substrate holder.
　真空蒸着装置の蒸着用るつぼに、上記ＴＡＤＦホスト化合物として例示したＨ－１を、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性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、Ｈ－１を蒸着速度０．１ｎｍ／秒で蒸着し、膜厚３０ｎｍの薄膜を作製した。 In the crucible for vapor deposition of the vacuum vapor deposition apparatus, H-1 exemplified as the TADF host compound was filled in an optimum amount for device fabrication. The crucible for vapor deposition was made of molybdenum-based resistance heating material.
After reducing the pressure in the vacuum deposition apparatus to a vacuum degree of 1 × 10 −4 Pa, H-1 was deposited at a deposition rate of 0.1 nm / second to produce a thin film with a thickness of 30 nm.
《薄膜１－２～１－４の作製》
　上記薄膜１－１の作製において、Ｈ－１を表３に記載の化合物に変更した以外は同様にして、薄膜１－２～１－４を作製した。 << Preparation of thin films 1-2 to 1-4 >>
Thin films 1-2 to 1-4 were prepared in the same manner as in the production of thin film 1-1 except that H-1 was changed to the compounds shown in Table 3.
《薄膜１－１～１－４の評価》
　上記作製した薄膜１－１のＰＬスペクトル及び絶対ＰＬ量子収率を、絶対ＰＬ量子収率測定装置Ｃ９９２０－０２（浜松ホトニクス社製）を用い、室温にて２８０ｎｍの励起波長で測定した。無酸素状態における薄膜１－１の絶対ＰＬ量子収率は０．６であり、酸素雰囲気下での絶対ＰＬ量子収率は０．２であった。無酸素状態と酸素雰囲気下とで絶対ＰＬ量子収率の値に変化が生じていることから、化合物Ｈ－１は熱活性化型遅延蛍光化合物（ＴＡＤＦ化合物）であることが示された。 << Evaluation of thin films 1-1 to 1-4 >>
The PL spectrum and absolute PL quantum yield of the produced thin film 1-1 were measured at room temperature with an excitation wavelength of 280 nm using an absolute PL quantum yield measuring apparatus C9920-02 (manufactured by Hamamatsu Photonics). The absolute PL quantum yield of the thin film 1-1 in the oxygen-free state was 0.6, and the absolute PL quantum yield in an oxygen atmosphere was 0.2. Changes in absolute PL quantum yield values between anoxic and oxygen atmospheres indicated that Compound H-1 is a thermally activated delayed fluorescent compound (TADF compound).
　また、薄膜１－１の発光寿命を、過渡ＰＬ特性を測定することによって行った。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。具体的には、遅い減衰成分はフラッシュランプ励起によるＭ９００３－０１モードにて、早い減衰成分は、３４０ｎｍのＬＥＤを励起光源としたＴＣＣ９００モードにて測定した。ここで、典型的には、蛍光成分はナノ秒に観測され、リン光発光及び三重項状態に由来する遅延蛍光成分はマイクロ又はミリ秒単位で観測される。薄膜１－１に対して測定を行ったところ、無酸素状態における発光寿命は１０ｎｓ及び３００ｎｓの成分が観測されたが、酸素雰囲気下における発光寿命は１０ｎｓの成分のみ観測された。これは、化合物Ｈ－１の発光に三重項状態が関与していることを示しており、室温でマイクロ秒の発光寿命が観測されていることも併せ、化合物Ｈ－１は熱活性型遅延蛍光化合物（ＴＡＤＦ化合物）であることが示された。 Further, the light emission lifetime of the thin film 1-1 was measured by measuring the transient PL characteristics. A small fluorescent lifetime measuring device C11367-03 (manufactured by Hamamatsu Photonics) was used for measurement of transient PL characteristics. Specifically, the slow decay component was measured in the M9003-01 mode by flash lamp excitation, and the fast decay component was measured in the TCC900 mode using a 340 nm LED as the excitation light source. Here, typically, the fluorescence component is observed in nanoseconds, and the delayed fluorescence component derived from phosphorescence and triplet states is observed in micro or millisecond units. When measurement was performed on the thin film 1-1, components of 10 ns and 300 ns were observed for the emission lifetime in the oxygen-free state, but only a component of 10 ns was observed for the emission lifetime in the oxygen atmosphere. This indicates that the triplet state is involved in the light emission of compound H-1, and that a light emission lifetime of microseconds is observed at room temperature, compound H-1 is thermally activated delayed fluorescence. It was shown to be a compound (TADF compound).
　薄膜１－２～１－４についても同様に評価を行い、上記ＴＡＤＦホスト化合物として例示したＨ－２、Ｈ－４、Ｈ－６がそれぞれＴＡＤＦ化合物であることが示された。
　薄膜１－１～１－４の絶対ＰＬ量子収率の結果を表３に示す。 The thin films 1-2 to 1-4 were similarly evaluated, and it was shown that H-2, H-4, and H-6 exemplified as the TADF host compound are TADF compounds.
Table 3 shows the absolute PL quantum yield results of the thin films 1-1 to 1-4.
Figure JPOXMLDOC01-appb-T000018
Figure JPOXMLDOC01-appb-T000018
［実施例２］
　非ＴＡＤＦ化合物及び上記例示した各ＴＡＤＦ化合物をそれぞれホスト化合物としてリン光発光性金属錯体ドープ膜を作製し、励起状態での耐性を評価した。 [Example 2]
A phosphorescent metal complex-doped film was prepared using a non-TADF compound and each of the above exemplified TADF compounds as host compounds, and the resistance in an excited state was evaluated.
《薄膜２－１の作製》
　まず、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。 << Production of Thin Film 2-1 >>
First, a quartz substrate having a size of 50 mm × 50 mm and a thickness of 0.7 mm was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. Fixed to the substrate holder.
　真空蒸着装置の蒸着用るつぼの各々に、ホスト化合物として非ＴＡＤＦ化合物である１，３－ｂｉｓ（９－ｃａｒｂａｚｏｌｙｌ）ｂｅｎｚｅｎｅ（ｍＣＰ）を、ドーパントとしてＨ－２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性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、ｍＣＰ及びＨ－２がそれぞれ９５体積％、５体積％になるように蒸着速度０．１ｎｍ／秒で蒸着し、膜厚３０ｎｍの薄膜を作製した。 In each of the evaporation crucibles of the vacuum evaporation apparatus, 1,3-bis (9-carbazolyl) benzene (mCP), which is a non-TADF compound, is used as a host compound, H-2 is used as an dopant, and the optimum amount for device fabrication Filled. The crucible for vapor deposition was made of molybdenum-based resistance heating material.
After reducing the pressure in the vacuum deposition apparatus to a vacuum degree of 1 × 10 −4 Pa, deposition was performed at a deposition rate of 0.1 nm / second so that mCP and H-2 were 95% by volume and 5% by volume, respectively, and the film thickness was 30 nm. A thin film was prepared.
《薄膜２－２～２－１０の作製》
　上記薄膜２－１の作製において、ホスト化合物の種類、ドーパントの種類及び濃度を表４に記載のとおりにそれぞれ変更した以外は同様にして、薄膜２－２～２－１０を作製した。 << Preparation of thin films 2-2 to 2-10 >>
Thin films 2-2 to 2-10 were produced in the same manner as in the production of the thin film 2-1, except that the type of host compound, the type of dopant, and the concentration were changed as shown in Table 4.
《薄膜２－１１の作製》
　上記薄膜２－１の作製において、ホスト化合物をＨ－２及びｍＣＰ、ドーパントをＰ－５０にそれぞれ変更するとともに、Ｈ－２、ｍＣＰ、Ｐ－５０がそれぞれ５０体積％、３５体積％、１５体積％になるように蒸着速度０．１ｎｍ／秒で蒸着し、膜厚３０ｎｍの薄膜を作製した以外は同様にして、薄膜２－１１を作製した。 << Preparation of Thin Film 2-11 >>
In the production of the thin film 2-1, the host compound was changed to H-2 and mCP, and the dopant was changed to P-50, respectively, and H-2, mCP, and P-50 were 50% by volume, 35% by volume, and 15% by volume, respectively. A thin film 2-11 was produced in the same manner except that a thin film having a film thickness of 30 nm was produced by vapor deposition at a vapor deposition rate of 0.1 nm / second so as to give a%.
《薄膜２－１２～２－１４の作製》
　上記薄膜２－１の作製において、ホスト化合物の種類、ドーパントの種類及び濃度を表４に記載のとおりにそれぞれ変更した以外は同様にして、薄膜２－１２～２－１４を作製した。 << Production of thin films 2-12 to 2-14 >>
Thin films 2-12 to 2-14 were prepared in the same manner as in the preparation of the thin film 2-1, except that the type of host compound, the type of dopant, and the concentration were changed as shown in Table 4.
《薄膜２－１～２－１４の評価》
（スペクトルの重なりの測定）
　ドーパントを２－ｍｅｔｈｙｌＴｅｔｒａｈｙｄｒｏｆｕｒａｎ溶媒に溶解し、１．０×１０－５ｍｏｌ／Ｌに調整した溶液の吸収スペクトルを測定し、吸光度からモル吸光係数（ｍｏｌ－１ｃｍ－１Ｌ）を算出した。実施例１にて作製したホスト薄膜の蛍光発光スペクトルを∫ｆ（ν）ｄν＝１に規格化し、下記式を用いてスペクトルの重なりの程度を評価した結果を表１に示す。 << Evaluation of thin films 2-1 to 2-14 >>
(Measurement of spectral overlap)
The dopant was dissolved in 2-methyltetrahydrofuran solvent, the absorption spectrum of a solution adjusted to 1.0 × 10 −5 mol / L was measured, and the molar extinction coefficient (mol −1 cm −1 L) was calculated from the absorbance. Table 1 shows the results of normalizing the fluorescence emission spectrum of the host thin film prepared in Example 1 to ∫f (ν) dν = 1 and evaluating the degree of spectrum overlap using the following formula.
Figure JPOXMLDOC01-appb-M000019
Figure JPOXMLDOC01-appb-M000019
（発光層単層試料の評価：紫外耐光性試験）
　下記の方法に従って、ＨｇＸｅ光源を用いたＵＶ照射試験における輝度残存率を求めた。ＨｇＸｅ光源を用いたＵＶ照射試験としては、浜松ホトニクス製水銀キセノンランプＵＶ照射装置ＬＣ８を使用し、ＵＶカットフィルターにＡ９６１６－０５を取り付けて使用した。照射ファイバー出光面と試料（青色発光層単層）のガラスカバー表面が水平をなすように配置し、１ｃｍの距離にて、発光フォトン数が半減するまで照射した。測定は室温（３００Ｋ）及び３３０Ｋの条件下で行った。
　各サンプルについて、発光フォトン数が半減するまでに要した時間（半減時間）を、薄膜２－１の室温（３００Ｋ）における値を１とする相対値で示した。その結果を表４に示す。なお、輝度の測定は、照射ファイバーの軸から４５度傾いた角度から分光放射輝度計ＣＳ－１０００（コニカミノルタ社製）により測定した。 (Evaluation of single layer sample of light emitting layer: UV light resistance test)
According to the following method, the luminance residual ratio in the UV irradiation test using the HgXe light source was determined. As a UV irradiation test using a HgXe light source, a mercury xenon lamp UV irradiation device LC8 manufactured by Hamamatsu Photonics was used, and an A9616-05 was attached to a UV cut filter. The irradiation fiber light exit surface and the glass cover surface of the sample (blue light emitting layer single layer) were arranged so as to be horizontal, and irradiation was performed at a distance of 1 cm until the number of emitted photons was reduced to half. The measurement was performed under conditions of room temperature (300K) and 330K.
For each sample, the time (half time) required for the number of luminescent photons to be halved is shown as a relative value with the value of the thin film 2-1 at room temperature (300 K) being 1. The results are shown in Table 4. The luminance was measured with a spectral radiance meter CS-1000 (manufactured by Konica Minolta) from an angle inclined by 45 degrees from the axis of the irradiation fiber.
Figure JPOXMLDOC01-appb-T000020
Figure JPOXMLDOC01-appb-T000020
　表４の結果から、ＴＡＤＦ化合物をホスト化合物として用い、リン光発光性金属錯体ドーパントと組み合わせることにより、リン光発光性金属錯体の消光速度を抑制できることが分かる。
　また、非ＴＡＤＦ化合物をホスト化合物とした場合、分解等の反応速度がアレニウス式に従って温度上昇にともない増加するために、素子寿命が低下する。これに対し、本発明のようにＴＡＤＦ化合物をホスト化合物とした場合、分解等の反応速度は同様に増加するものの、高温下でＴ１のＳ１への逆項間交差が促進されるため、三重項状態に存在する時間が減少し、分解等の反応確率が減少するために、素子寿命の向上又は低下幅の抑制が見られると考えられる。 From the results in Table 4, it can be seen that the quenching rate of the phosphorescent metal complex can be suppressed by using the TADF compound as a host compound and combining it with the phosphorescent metal complex dopant.
Further, when a non-TADF compound is used as a host compound, the reaction rate of decomposition or the like increases as the temperature rises according to the Arrhenius equation, so that the device life is reduced. On the other hand, when the TADF compound is used as the host compound as in the present invention, the reaction rate such as decomposition similarly increases, but since the crossing between the reverse terms of T 1 to S 1 is promoted at high temperature, Since the time in the triplet state is reduced and the reaction probability such as decomposition is reduced, it is considered that the device lifetime is improved or the reduction width is suppressed.
［実施例３］
《有機ＥＬ素子３－１の作製》
　まず、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の厚さで製膜し、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。 [Example 3]
<< Preparation of organic EL element 3-1 >>
First, an ITO (indium tin oxide) film having a thickness of 150 nm was formed as an anode on a glass substrate having a size of 50 mm × 50 mm and a thickness of 0.7 mm. After patterning, an ITO transparent electrode was attached. The transparent substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes, and then the transparent substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus.
　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。 Each of the deposition crucibles in the vacuum deposition apparatus was filled with the constituent material of each layer in an amount optimal for device fabrication. The evaporation crucible used was made of a resistance heating material made of molybdenum or tungsten.
　真空蒸着装置内を真空度１×１０－４Ｐａまで減圧した後、４，４′－ビス〔Ｎ－（１－ナフチル）－Ｎ－フェニルアミノ〕ビフェニル（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ＩＴＯ透明電極上に蒸着し、層厚４０ｎｍの正孔注入輸送層を形成した。 After depressurizing the inside of the vacuum deposition apparatus to a vacuum of 1 × 10 −4 Pa, a deposition crucible containing 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD) Was heated by applying current to the ITO transparent electrode at a deposition rate of 0.1 nm / second to form a hole injection transport layer having a layer thickness of 40 nm.
　次いで、ｍＣＰの入った蒸着用るつぼに通電して加熱し、蒸着速度０．１ｎｍ／秒で正孔輸送層上に蒸着し、層厚１０ｎｍの中間層を形成した。 Next, the deposition crucible containing mCP was energized and heated, and deposited on the hole transport layer at a deposition rate of 0.1 nm / second to form an intermediate layer having a layer thickness of 10 nm.
　次いで、ホスト化合物としてｍＣＰ、ドーパントとしてＰ－５７のそれぞれ入った蒸着用るつぼに通電して加熱し、それぞれ９５体積％、５体積％になるように蒸着速度０．１ｎｍ／秒で中間層上に共蒸着し、層厚２０ｎｍの発光層を形成した。 Next, the deposition crucible containing mCP as the host compound and P-57 as the dopant was energized and heated, and deposited on the intermediate layer at a deposition rate of 0.1 nm / second so as to be 95% by volume and 5% by volume, respectively. Co-evaporation was performed to form a light emitting layer having a layer thickness of 20 nm.
　その後、Ｅ－１の入った蒸着用るつぼに通電して加熱し、蒸着速度０．１ｎｍ／秒で発光層上に蒸着し、層厚４０ｎｍの電子輸送層を形成した。 Thereafter, the deposition crucible containing E-1 was energized and heated, and deposited on the light emitting layer at a deposition rate of 0.1 nm / second to form an electron transport layer having a layer thickness of 40 nm.
　更に、電子輸送層上にフッ化リチウムを膜厚０．８ｎｍ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。 Furthermore, after forming lithium fluoride with a film thickness of 0.8 nm on the electron transport layer, 100 nm of aluminum was vapor-deposited to form a cathode.
　上記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３－１を作製した。 The non-light emitting surface side of the above element was covered with a can-shaped glass case in an atmosphere of high-purity nitrogen gas with a purity of 99.999% or more, and an electrode lead-out wiring was installed to prepare an organic EL element 3-1.
《有機ＥＬ素子３－２～３－７の作製》
　上記有機ＥＬ素子３－１の作製において、ホスト化合物の種類、ドーパントの種類及び濃度を表５に記載のとおりに変更した以外は同様にして、有機ＥＬ素子３－２～３－７を作製した。 << Production of organic EL elements 3-2 to 3-7 >>
Organic EL devices 3-2 to 3-7 were prepared in the same manner as in the production of the organic EL device 3-1, except that the type of host compound, the type of dopant, and the concentration were changed as shown in Table 5. .
《有機ＥＬ素子３－１～３－７の評価》
（連続駆動安定性（半減寿命）の評価）
　各サンプルを、分光放射輝度計ＣＳ－２０００を用いて輝度を測定し、測定した輝度が半減する時間（ＬＴ５０）を半減寿命として求めた。駆動条件は、１５ｍＡ／ｃｍ２となる電流値とした。
　有機ＥＬ素子３－１の半減寿命を１．０とした相対値を求め、これを連続駆動安定性の尺度とした。その評価結果を表５に示す。表５中、数値が大きいほど、連続駆動安定性に優れている（長寿命である）ことを表す。 << Evaluation of organic EL elements 3-1 to 3-7 >>
(Evaluation of continuous drive stability (half life))
The brightness of each sample was measured using a spectral radiance meter CS-2000, and the time for which the measured brightness was reduced by half (LT50) was determined as the half life. The driving condition was a current value of 15 mA / cm 2 .
A relative value with the half-life of the organic EL element 3-1 set to 1.0 was determined, and this was used as a measure of continuous drive stability. The evaluation results are shown in Table 5. In Table 5, it shows that it is excellent in continuous drive stability (long life), so that a numerical value is large.
Figure JPOXMLDOC01-appb-T000021
Figure JPOXMLDOC01-appb-T000021
　表５の結果から、上記実施例２の結果と同様、ＴＡＤＦ化合物をホスト化合物として用い、リン光発光性金属錯体ドーパントと組み合わせることにより、リン光発光性金属錯体の消光速度を抑制でき、有機ＥＬ素子の素子駆動寿命を向上できることが分かる。 From the results of Table 5, as with the results of Example 2 above, the quenching rate of the phosphorescent metal complex can be suppressed by using the TADF compound as a host compound and combining with the phosphorescent metal complex dopant. It can be seen that the element driving life of the element can be improved.
　以上のように、本発明は、ホスト化合物及びドーパントの励起状態での安定性に優れ、素子駆動寿命が向上した有機エレクトロルミネッセンス素子を提供することに適している。 As described above, the present invention is suitable for providing an organic electroluminescence device having excellent stability in the excited state of a host compound and a dopant and having an improved device driving lifetime.
　１　　　ディスプレイ
　３　　　画素
　５　　　走査線
　６　　　データ線
　７　　　電源ライン
　１０　　有機ＥＬ素子
　１１　　スイッチングトランジスタ
　１２　　駆動トランジスタ
　１３　　コンデンサー
　１０１　照明装置内の有機ＥＬ素子
　１０２　ガラスカバー
　１０５　陰極
　１０６　有機ＥＬ層
　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
　Ｃ　　　配線部
　Ｌ　　　発光光 DESCRIPTION OF SYMBOLS 1 Display 3 Pixel 5 Scan line 6 Data line 7 Power supply line 10 Organic EL element 11 Switching transistor 12 Drive transistor 13 Capacitor 101 Organic EL element in a lighting device 102 Glass cover 105 Cathode 106 Organic EL layer 107 Glass substrate with transparent electrode 108 Nitrogen Gas 109 Water capturing agent A Display unit B Control unit C Wiring unit L Light emission

Claims (3)

  1. 　一対の電極と、前記一対の電極間に発光層を含む有機層が具備された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、熱活性化型遅延蛍光発光性のホスト化合物と、リン光発光性金属錯体ドーパントとを含有し、
    　前記ホスト化合物の前記リン光発光性金属錯体ドーパントへの一重項エネルギー移動効率が、１０～１００％の範囲内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。     An organic electroluminescence device comprising a pair of electrodes and an organic layer including a light emitting layer between the pair of electrodes,
    The light-emitting layer contains a thermally activated delayed fluorescence host compound and a phosphorescent metal complex dopant,
    An organic electroluminescence device, wherein a singlet energy transfer efficiency of the host compound to the phosphorescent metal complex dopant is within a range of 10 to 100%.
  2. 　前記一重項エネルギー移動効率が、９０～１００％の範囲内であることを特徴とする請求項１に記載の有機エレクトロルミネッセンス素子。 2. The organic electroluminescence device according to claim 1, wherein the singlet energy transfer efficiency is in a range of 90 to 100%.
  3. 　前記リン光発光性金属錯体ドーパントが、下記一般式（１）で表される構造を有することを特徴とする請求項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。
    Figure JPOXMLDOC01-appb-C000001
     （一般式（１）中、Ｍは、Ｉｒ、Ｐｔ、Ｒｈ、Ｒｕ、Ａｇ、Ｃｕ又はＯｓを表す。Ａ１及びＡ２は、各々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員の芳香族複素環を表す。Ｂ１～Ｂ５は、５員の芳香族複素環を形成する原子群であり、置換基を有していても良い炭素原子、窒素原子、酸素原子又は硫黄原子を表す。環Ｚ１は、置換基を有していても良く、更に置換基同士が結合して縮環構造を形成していても良い。Ｌは、Ｍに配位したモノアニオン性の二座配位子を表す。Ｍに配位した各々の配位子は、その置換基が互いに結合して配位子同士が連結していても良い。ｍは、０～２の整数を表し、ｎは、１～３の整数を表し、ｍ＋ｎは、２又は３である。ｍ及びｎが各々２以上のとき、環Ｚ１、Ｂ１～Ｂ５で表される芳香族複素環基及びＬは各々同じであっても異なっていても良い。）     The organic electroluminescence device according to claim 1 or 2, wherein the phosphorescent metal complex dopant has a structure represented by the following general formula (1).
    Figure JPOXMLDOC01-appb-C000001
     (In General Formula (1), M represents Ir, Pt, Rh, Ru, Ag, Cu, or Os. A 1 and A 2 each represent a carbon atom or a nitrogen atom. Ring Z 1 represents A 1. And a 6-membered aromatic hydrocarbon ring or a 5-membered or 6-membered aromatic heterocycle formed together with A 2. B 1 to B 5 are an atomic group forming a 5-membered aromatic heterocycle Represents a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom which may have a substituent, and ring Z 1 may have a substituent, and the substituents are further bonded to each other to form a condensed ring structure. L represents a monoanionic bidentate ligand coordinated to M. Each ligand coordinated to M is coordinated by bonding of substituents thereof to each other. The children may be linked to each other, m represents an integer of 0 to 2, n represents an integer of 1 to 3, and m + n is 2 or 3. And when n is each of two or more, the ring Z 1, B 1 aromatic heterocyclic group and L represented by ~ B 5 may be different even each identical.)
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JP2019050369A (en) * 2017-09-06 2019-03-28 住友化学株式会社 Light-emitting element

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JP2015065225A (en) * 2013-09-24 2015-04-09 日本放送協会 Organic electroluminescent element, and display device and lighting device using the same

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JP2014075249A (en) * 2012-10-03 2014-04-24 Idemitsu Kosan Co Ltd Organic electroluminescent element
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JP2019050369A (en) * 2017-09-06 2019-03-28 住友化学株式会社 Light-emitting element

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