WO2018135656A1 - Composition for forming light emitting layer and organic electroluminescent element containing said composition for forming light emitting layer - Google Patents

Composition for forming light emitting layer and organic electroluminescent element containing said composition for forming light emitting layer Download PDF

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WO2018135656A1
WO2018135656A1 PCT/JP2018/001764 JP2018001764W WO2018135656A1 WO 2018135656 A1 WO2018135656 A1 WO 2018135656A1 JP 2018001764 W JP2018001764 W JP 2018001764W WO 2018135656 A1 WO2018135656 A1 WO 2018135656A1
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compound
light emitting
emitting layer
composition
forming
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PCT/JP2018/001764
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French (fr)
Japanese (ja)
Inventor
逸美 西尾
石橋　孝一
良子 梶山
大輔 弘
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三菱ケミカル株式会社
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Priority to CN201880007700.XA priority Critical patent/CN110235265B/en
Priority to KR1020197019714A priority patent/KR102544020B1/en
Priority to JP2018562476A priority patent/JP6950710B2/en
Publication of WO2018135656A1 publication Critical patent/WO2018135656A1/en

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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/10—Organic polymers or oligomers
    • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/10—Apparatus or processes specially adapted to the manufacture of electroluminescent light sources
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/30—Coordination compounds
    • H10K85/341—Transition metal complexes, e.g. Ru(II)polypyridine complexes
    • H10K85/342—Transition metal complexes, e.g. Ru(II)polypyridine complexes comprising iridium
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/60—Organic compounds having low molecular weight
    • H10K85/631—Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/60—Organic compounds having low molecular weight
    • H10K85/649—Aromatic compounds comprising a hetero atom
    • H10K85/654—Aromatic compounds comprising a hetero atom comprising only nitrogen as heteroatom
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/60—Organic compounds having low molecular weight
    • H10K85/649—Aromatic compounds comprising a hetero atom
    • H10K85/657—Polycyclic condensed heteroaromatic hydrocarbons
    • H10K85/6572—Polycyclic condensed heteroaromatic hydrocarbons comprising only nitrogen in the heteroaromatic polycondensed ring system, e.g. phenanthroline or carbazole

Definitions

  • the present invention relates to a composition for forming a light emitting layer and an organic electroluminescent device containing the composition for forming a light emitting layer.
  • organic electroluminescent elements can emit light in various colors with a simple element configuration, in recent years, they have been actively developed as a technique for manufacturing light emitting devices such as displays and lighting.
  • the organic electroluminescence device obtains light emission by injecting holes and electrons from an anode and a cathode, allowing each charge to reach the light emitting layer, and recombining the charge in this light emitting layer. From this principle, it is possible to improve luminous efficiency by forming a light emitting layer using a composition for forming a light emitting layer containing not only a light emitting material but also a charge transport material, and retaining charges in the light emitting layer. It has been studied (see Patent Document 1).
  • retaining the charge in the light emitting layer deteriorates the current-voltage characteristics of the organic electroluminescent element.
  • it is generally performed by a method of retaining a charge by creating a charge trap level in the film. According to these methods, it is possible to increase the light emission efficiency by retaining the charge in the light emitting layer, but at the same time, the current-voltage characteristics are deteriorated, that is, the driving voltage of the organic electroluminescent element is increased. Since the power consumption increases as the driving voltage increases, for example, a technique for reducing the driving voltage by setting the total number of charge transport materials contained in the composition for forming a light emitting layer to three or more has been proposed. (See Patent Document 2). However, when the number of types of charge transport materials is increased, there are still insufficient studies on methods for improving the driving life, which is an important characteristic of organic electroluminescent devices, and methods for maintaining storage stability at high temperatures. it is conceivable that.
  • An object of the present invention is to provide an organic electroluminescence device having a long driving life and excellent storage stability, and an object thereof is to provide a composition for forming a light emitting layer suitable for the organic electroluminescence device.
  • a driving life is obtained by using a compound having a glass transition temperature higher than a predetermined temperature and a compound lower than the predetermined temperature for the composition for forming a light emitting layer. It has been found that an organic electroluminescent element is obtained that is long and has a drive life that does not easily decrease even after high-temperature storage.
  • the present invention has been achieved based on such findings, and the gist thereof is as follows.
  • a composition for forming a light-emitting layer of an organic electroluminescent device comprising a light-emitting material, a non-light-emitting material, and an organic solvent, the non-light-emitting material comprising a high Tg compound and glass having a glass transition temperature of 130 ° C. or higher
  • a low Tg compound having a transition temperature of 100 ° C. or lower the content of the low Tg compound in all the non-light emitting materials is 8 to 70% by mass, and at least one of the non-light emitting materials is a pyrimidine skeleton or
  • a composition for forming a light emitting layer which is a material having a triazine skeleton.
  • the molecular weight of all the non-light emitting materials whose content is 1.0% by mass or more with respect to the total amount of all the non-light emitting materials contained in the composition for forming a light emitting layer is 5000 or less.
  • R 1 to R 15 each independently represents a monovalent compound in which a hydrogen atom or a phenyl group or aromatic hydrocarbon monocyclic compound having 6 to 30 carbon atoms is bonded.
  • R 1 to R 15 each independently represents a monovalent compound in which a hydrogen atom or a phenyl group or aromatic hydrocarbon monocyclic compound having 6 to 30 carbon atoms is bonded.
  • An organic electroluminescence device having a light-emitting layer wet-formed using the composition for forming a light-emitting layer according to any one of [1] to [8].
  • an organic electroluminescent element having a long driving life and high luminous efficiency can be obtained after storage at high temperature.
  • FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of an organic electroluminescent element of the present invention.
  • FIG. 2 is a schematic cross-sectional view showing another example of the embodiment of the organic electroluminescent element of the present invention.
  • composition for forming a light emitting layer is used for forming a light-emitting layer of an organic electroluminescence device, and includes a light-emitting material, a non-light-emitting material, and an organic solvent.
  • Tg includes a high Tg compound having a temperature of 130 ° C. or higher and a low Tg compound having a Tg of 100 ° C. or lower.
  • Luminescent material As the light-emitting material, any known material that is usually used as a light-emitting material of an organic electroluminescent element can be applied, and there is no particular limitation. Light is emitted at a desired light emission wavelength, and the light emission efficiency is good. A substance may be used.
  • the light emitting material may be a fluorescent light emitting material or a phosphorescent light emitting material, but is preferably a phosphorescent light emitting material from the viewpoint of internal quantum efficiency and low heat generation.
  • a long-period type periodic table (hereinafter, unless otherwise specified, the term “periodic table” refers to a long-period type periodic table) selected from Group 7 to 11 Wellner type complexes or organometallic complexes containing the above metal as the central metal.
  • Preferred examples of the metal selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold.
  • the metal selected from Groups 7 to 11 of the periodic table iridium and platinum are more preferable.
  • an aryl group such as an arylpyridine ligand, a heteroarylpyridine ligand, an arylpyrazole ligand, a heteroarylpyrazole ligand, or a heteroaryl group such as pyridine, pyrazole, or phenanthroline And the like, and a phenylpyridine ligand and a phenylpyrazole ligand are particularly preferable.
  • phosphorescent materials include tris (2-phenylpyridine) iridium, tris (2-phenylpyridine) ruthenium, tris (2-phenylpyridine) palladium, bis (2-phenylpyridine) platinum, tris (2- Phenylpyridine) osmium, tris (2-phenylpyridine) rhenium, octaethylplatinum porphyrin, octaphenylplatinum porphyrin, octaethyl palladium porphyrin, octaphenyl palladium porphyrin, and the like.
  • the organometallic complex of the phosphorescent material is preferably a compound represented by the following formula (I).
  • ML (q ⁇ j) L ′ j (I) M represents a metal, q represents a valence of the metal, L and L ′ represent a bidentate ligand, and j represents a number of 0, 1 or 2.
  • M represents any metal. Specific examples of preferable M include the metals described above as the metal selected from Groups 7 to 11 of the periodic table.
  • bidentate ligand L represents a ligand having the following partial structure.
  • ring A1 represents an aromatic ring group which may have a substituent.
  • the aromatic ring group in the present invention may be an aromatic hydrocarbon group or an aromatic heterocyclic group.
  • ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.
  • examples of the bidentate ligand L ′ include the ligands shown below.
  • the organometallic complex of the phosphorescent material in the present invention from the viewpoint of easily interacting with the non-light emitting material coexisting in the light emitting layer, the above formula having a bidentate ligand having a relatively three-dimensional and bulky molecule ( The compounds represented by I) are preferred. Further, for example, a fluorescent material and a phosphorescent material may be used in combination such that a fluorescent material is used for blue and a phosphorescent material is used for green and red.
  • the symmetry and rigidity of the molecules of the light emitting material are reduced.
  • the molecular weight of the luminescent material in the present invention is preferably 5000 or less, more preferably 4000 or less, and particularly preferably 3000 or less. Further, the molecular weight of the light emitting material in the present invention is usually 400 or more, preferably 600 or more, more preferably 800 or more, and particularly preferably 1000 or more. With this molecular weight range, it is considered that the light-emitting materials can be uniformly mixed with the non-light-emitting material without aggregating the light-emitting materials, and a light-emitting layer with high light emission efficiency can be obtained.
  • the molecular weight of the luminescent material is high in Tg, melting point, decomposition temperature, etc., excellent in heat resistance of the luminescent material and the formed luminescent layer, and film quality deterioration due to gas generation, recrystallization, molecular migration, etc. In view of the fact that the increase in the impurity concentration accompanying the thermal decomposition of the material or the like hardly occurs, it is preferable.
  • the molecular weight of the light-emitting material is preferably small in that the organic compound can be easily purified and easily dissolved in a solvent.
  • the non-light emitting material in the present invention refers to all nonvolatile materials other than the light emitting material.
  • the non-volatile material is a material other than the organic solvent in the composition for forming a light emitting layer, and means a material included in the light emitting layer when the light emitting layer is formed.
  • the non-light emitting material includes at least a high Tg compound and a low Tg compound, which will be described later, but may include materials other than these.
  • At least one of the non-light emitting materials is a material having a pyrimidine skeleton or a triazine skeleton, and at least one of the high Tg compound and the low Tg compound described later.
  • One of the materials is preferably a material having a pyrimidine skeleton or a triazine skeleton.
  • any of the non-light-emitting materials is a material having a triazine skeleton, and it is particularly preferable that at least one of a high Tg compound or a low Tg compound described later is a material having a triazine skeleton.
  • the low Tg compound is a material having a triazine skeleton.
  • the molecular weight of all the non-light-emitting materials having a content ratio of 1.0% by mass or more with respect to the total amount of all the non-light-emitting materials contained in the composition for forming a light-emitting layer It is preferably 5000 or less, more preferably 4000 or less, particularly preferably 3000 or less, most preferably 2000 or less, usually 300 or more, preferably 350 or more, and more preferably 400 or more.
  • the high Tg compound of the present invention is a compound having a Tg of 130 ° C. or higher.
  • a compound having a Tg of 130 ° C. or higher may be appropriately selected from the compounds usually used for forming the light emitting layer of the organic electroluminescent device.
  • the high Tg compound is usually contained in the light emitting layer. It is preferable that the charge transport material be
  • the compound having a Tg of 130 ° C. or higher is preferably a compound that bonds a condensed ring structure of three or more rings to a central skeleton excellent in charge transportability.
  • a compound having two or more condensed ring structures having three or more rings and / or a compound having at least one condensed ring having five or more rings is preferable.
  • the rigidity of the molecule is increased, and the effect of suppressing the degree of molecular motion in response to heat is easily obtained.
  • central skeleton with excellent charge transportability examples include aromatic structures, aromatic amine structures, triarylamine structures, dibenzofuran structures, naphthalene structures, phenanthrene structures, phthalocyanine structures, porphyrin structures, thiophene structures, and benzylphenyl structures.
  • the high Tg compound in the present invention is preferably a material having a structure excellent in electron transporting property in that the light emitting material itself can suppress deterioration of the light emitting material due to transport of electrons and extend the driving life.
  • a compound having a structure excellent in hole transportability is also preferable, and among the central skeleton excellent in charge transportability, a carbazole structure, dibenzofuran structure, triarylamine structure, naphthalene structure, phenanthrene structure or pyrene structure is a hole.
  • a structure excellent in transportability is preferable, and a carbazole structure, a dibenzofuran structure, or a triarylamine structure is more preferable.
  • the high Tg compound in the present invention is a material having a structure excellent in hole transportability in that the light emitting material itself can suppress the deterioration of the light emitting material due to transporting holes and can extend the driving life.
  • the high Tg compound of the present invention preferably has a condensed ring structure of 3 or more rings, and / or at least one compound having 2 or more condensed ring structures of 3 or more rings and / or 5 or more condensed rings. More preferably, it is a compound which has.
  • condensed ring structure having three or more rings examples include anthracene structure, phenanthrene structure, pyrene structure, chrysene structure, naphthacene structure, triphenylene structure, fluorene structure, benzofluorene structure, indenofluorene structure, indolofluorene structure, Examples thereof include a carbazole structure, an indenocarbazole structure, an indolocarbazole structure, a dibenzofuran structure, and a dibenzothiophene structure.
  • a carbazole structure or an indolocarbazole structure is more preferable from the viewpoint of durability against electric charges.
  • the molecular weight of the high Tg compound in the present invention is usually 5000 or less, preferably 4000 or less, more preferably 3000 or less, and most preferably 2000 or less. Further, the molecular weight of the high Tg compound in the present invention is usually 300 or more, preferably 350 or more, and more preferably 400 or more.
  • the molecular weight of the high Tg compound is preferably large from the viewpoint that film quality deterioration due to gas generation, recrystallization, molecular migration or the like hardly occurs. On the other hand, the molecular weight of the high Tg compound is preferably small in view of easy purification of the organic compound and easy dissolution in a solvent.
  • the Tg of the high Tg compound in the present invention is arbitrary as long as the effect of the present invention is not significantly impaired as long as it is 130 ° C. or higher.
  • the Tg of the high Tg compound in the present invention is preferably 135 ° C. or higher, more preferably 140 ° C. or higher, since the film during high temperature storage is stable.
  • the Tg of the high Tg compound in the present invention is usually 250 ° C. or lower, preferably 200 ° C. or lower, more preferably 180 ° C. or lower, and still more preferably 160 ° C. or lower because of its high solubility in organic solvents.
  • the temperature inside the vehicle may exceed 80 ° C. when the vehicle is parked under the hot summer sun. Reliability is required. Therefore, a general high-temperature storage test of an organic electroluminescent element is usually performed at 100 ° C. or higher, and at most about 120 ° C.
  • changes in film properties and morphology near Tg actually occur gradually before and after Tg. From the above, the Tg of the high Tg compound in the present invention is 130 ° C. or higher, which is a sufficiently higher temperature than the storage test.
  • the composition for forming a light emitting layer of the present invention may contain at least one high Tg compound, but may contain a plurality of high Tg compounds.
  • the low Tg compound of the present invention is a compound having a Tg of 100 ° C. or lower.
  • the low Tg compound is preferably a compound in which monocyclic compounds are bonded via a direct bond and / or a linking group.
  • the compound may have a substituent, and the substituent is not particularly limited, but an alkyl group or an aralkyl group is preferable from the viewpoint of excellent solubility and ink storage stability.
  • the linking group is not particularly limited as long as it is an atom or a substituent that is usually used as a material for an organic electroluminescent device.
  • linking group means that the monocyclic compound is bonded to all bonds.
  • These linking groups may link monocyclic compounds to each other, or may link compounds in which monocyclic compounds are bonded via a direct bond. Further, the monocyclic compounds to be linked at this time, or the compounds in which the monocyclic compounds are bonded via a direct bond may have the same structure or different structures.
  • a nitrogen atom is a linking group and a compound in which monocyclic compounds are bonded via a direct bond is an aryl group, it means a triarylamine, and the three substituents of the triarylamine are the same. Or different.
  • the linking group is more preferably a nitrogen atom or an alkylene group from the viewpoint that the twist of the adjacent ring is larger, the planarity of the molecule is low, and crystallization due to molecular packing is difficult to cause. Further, from the viewpoint of durability against electric charges, a compound consisting of only a direct bond is more preferable.
  • a compound satisfying the above conditions may be appropriately selected from the compounds usually used for forming the light emitting layer of the organic electroluminescence device.
  • a monocyclic compound may be used as the low Tg material.
  • Aromatic hydrocarbon monocyclic compounds are bonded to each other through a direct bond and / or a linking group, and a compound having an aromatic structure, an aromatic amine structure or a benzylphenyl structure is more excellent in charge transporting properties. It is further preferable.
  • a compound in which monocyclic compounds are bonded via a direct bond and / or a linking group is preferable in that the planarity as a molecule is low and crystallization due to molecular packing is unlikely to occur.
  • a compound in which aromatic hydrocarbon monocyclic compounds are bonded via a direct bond and / or a linking group is advantageous in that the influence of hydrogen bond is small and the rotation of the bond is easy to be placed and the planarity of the molecule can be further lowered. More preferred.
  • the low Tg compound contained in the composition for forming a light emitting layer of the present invention comprises only a compound in which aromatic hydrocarbon monocyclic compounds are directly bonded to each other in terms of excellent durability against electric charges.
  • a compound represented by the following formula (A) is preferable as a low Tg compound in which aromatic hydrocarbon monocyclic compounds are directly bonded to each other.
  • R 1 to R 15 each independently represents a monovalent compound in which a hydrogen atom or a phenyl group or an aromatic hydrocarbon monocyclic compound having 6 to 30 carbon atoms is bonded.
  • the low Tg compound having the structure of the formula (A) has a high durability against electric charges, and is a structure that can easily achieve both molecular motion and stability due to heat and the like.
  • the structure of Formula (A) is a compound in which only a single ring of an aromatic hydrocarbon is bonded, it is preferable to easily fill a gap between high Tg compounds.
  • the structure of the formula (A) is preferable when the high Tg compound has a condensed ring structure having 3 or more rings or a condensed ring structure having 5 or more rings, because the gap between the high Tg compounds generated by the condensed ring is easily filled. Further, the structure of the formula (A) has a high affinity with the formula (A) which is an aromatic hydrocarbon compound when the condensed ring contains an aromatic hydrocarbon ring or an aromatic heterocycle, and a high Tg compound. The state in which the gaps between them are filled is considered to be more stable, which is preferable.
  • a preferable low Tg compound in the present invention is a compound in which monocyclic compounds are bonded through a direct bond and / or a linking group.
  • pyridine-based compounds, pyrimidine-based compounds, triazine-based compounds and the like which are materials having excellent electron transport properties and relatively stable structures, are preferable.
  • the light emitting material itself can suppress deterioration of the light emitting material due to transport of electrons, thereby extending the driving life.
  • the low Tg compound in the present invention is a material having an excellent electron transporting property and a relatively stable structure in that the light emitting material itself can suppress deterioration of the light emitting material due to transport of electrons and can extend the driving life.
  • the low Tg compound in the present invention is a material having a structure excellent in hole transportability in that the light emitting material itself can suppress the deterioration of the light emitting material due to transporting holes and can extend the driving life. It is preferable.
  • a dicycloalkylarylamine structure, a cycloalkyldiarylamine structure, and a triarylamine structure are preferable.
  • a triarylamine structure is more preferable from the viewpoint of durability.
  • the molecular weight of the low Tg compound in the present invention is usually 5000 or less, preferably 4000 or less, more preferably 3000 or less, and most preferably 2000 or less. Further, the molecular weight of the low Tg compound in the present invention is usually 300 or more, preferably 350 or more, more preferably 400 or more.
  • the molecular weight of the low Tg compound is preferably large in that it is difficult for the film quality to deteriorate due to gas generation, recrystallization, molecular migration, or the like.
  • the molecular weight of the low Tg compound is preferably small in that the organic compound can be easily purified and easily dissolved in a solvent.
  • the Tg of the low Tg compound in the present invention is arbitrary as long as the effect of the present invention is not significantly impaired as long as it is 100 ° C. or lower.
  • the Tg of the low Tg compound in the present invention is preferably 95 ° C. or lower, more preferably 90 ° C. or lower.
  • the Tg of the low Tg compound in the present invention is usually 60 ° C. or higher, preferably 70 ° C. or higher, more preferably 80 ° C. or higher, and still more preferably 85 ° C. or higher.
  • the Tg of the low Tg compound in the present invention is preferably low from the viewpoint of solubility in a solvent and device stability due to suppression of crystallization in the film.
  • the Tg of the low Tg compound is preferably high from the viewpoint of ensuring non-volatility, thermal stability in element fabrication process and element storage.
  • the composition for forming a light emitting layer of the present invention may contain at least one kind of low Tg compound, but may contain a plurality of low Tg compounds.
  • the composition for forming a light emitting layer of the present invention is preferably formed as a light emitting layer by using a wet film forming method such as an ink jet method.
  • the organic solvent used in the present invention is not particularly limited as long as the light emitting layer material such as the light emitting material and the non-light emitting material can be dissolved or dispersed well.
  • the solubility of the organic solvent is usually 0.01% by mass or more, preferably 0.05% by mass or more, and more preferably 0.1% by mass of the luminescent material and the non-luminescent material, respectively, at 25 ° C. and 1 atm. It is preferable to dissolve by mass% or more.
  • an organic solvent is not limited to these.
  • organic solvent examples include alkanes such as n-decane, cyclohexane, ethylcyclohexane, decalin, and bicyclohexane; aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene, tetramethylcyclohexanone, and tetralin; Halogenated aromatic hydrocarbons such as chlorobenzene and trichlorobenzene; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3 -Aromatic ethers such as dimethylanisole, 2,4-dimethylanisole, diphenyl ether; phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, ethy
  • the organic solvent preferably, it is at least one selected from the group consisting of alkanes and / or aromatic hydrocarbons, more preferably toluene, xylene and cyclohexylbenzene.
  • alkanes and / or aromatic hydrocarbons more preferably toluene, xylene and cyclohexylbenzene.
  • it is non-polar and hardly affected by moisture, and the material is easily dissolved, so that the ink can be stored stably.
  • One of these organic solvents may be used alone, or two or more thereof may be used in any combination and ratio.
  • the organic solvent evaporates from the liquid film immediately after the film formation at an appropriate rate.
  • the boiling point of the organic solvent is usually 80 ° C. or higher, preferably 100 ° C. or higher, more preferably 120 ° C. or higher.
  • the boiling point of the organic solvent is usually 270 ° C. or lower, preferably 250 ° C. or lower, more preferably 230 °
  • the composition for forming a light emitting layer of the present invention may contain other components as appropriate as long as it contains at least the high Tg compound and the low Tg compound as described above.
  • the content of the low Tg compound with respect to all the non-light emitting materials contained in the composition for forming a light emitting layer (hereinafter simply referred to as the content of the low Tg compound) is 8 to 70% by mass, More preferably, it is 10 to 70% by mass.
  • the content rate of a low Tg compound is 8 mass% or more, 10 mass% or more is preferable and 15 mass% or more is more preferable.
  • the content rate of a low Tg compound is 80 mass% or less, 70 mass% or less is preferable, 50 mass% or less is more preferable, 40 mass% or less is further more preferable, and 35 mass% or less is especially preferable.
  • the content of the low Tg compound is preferably high from the viewpoints of solubility in a solvent, ink storage stability after dissolution, and the light emitting surface is uniform and stable because crystallization of the light emitting layer is difficult to occur.
  • the content of the low Tg compound is preferably low in that the film morphology hardly changes when the device is stored at high temperature.
  • the content of the high Tg compound with respect to all the non-light emitting materials contained in the composition for forming the light emitting layer (hereinafter simply referred to as the content of the high Tg compound) is preferably 10% by mass or more, and more preferably 15% by mass or more. Moreover, 90 mass% or less is preferable, and 70 mass% or less is still more preferable. Contrary to the low Tg compound, the content of the high Tg compound is low in that it is soluble in a solvent, storage stability after dissolution, and the light emitting surface is uniform and stable because crystallization of the light emitting layer is difficult to occur. It is preferable that it is high in that the film morphology hardly changes when the device is stored at high temperature.
  • the content of the light emitting material in all the nonvolatile materials contained in the composition for forming a light emitting layer is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 40% by mass or less, and 30% by mass. The following is more preferable.
  • the heat resistance of the film is improved, and by including a low Tg compound, a uniform film can be formed during film formation.
  • High Tg compounds are easy to crystallize at the time of film formation and are rigid compounds. Therefore, high Tg compounds are difficult to come into close contact with each other at the molecular level, thereby reducing the charge transport property of the film.
  • a low Tg compound when a low Tg compound is present, it is presumed that the low Tg compound fills the gaps between the rigid high Tg compounds, suppresses crystallization of the high Tg compound, and forms a uniform film.
  • a composition containing a low Tg compound and a high Tg compound is formed into a wet film, it is dried in a state where the low Tg compound and the high Tg compound are uniformly mixed. That is, it is considered that a film in which the gap between the high Tg compounds rigid with the low Tg compound is filled can be easily formed, and a uniform film excellent in transportability can be easily formed.
  • the conventional vacuum heating vapor deposition method since the material is deposited in clusters, it is considered that the low Tg compound is difficult to fill the gap between the high Tg compounds.
  • a low Tg compound exists between the high Tg compounds, so that it is considered that the film has high heat resistance in which crystallization of the high Tg compound is suppressed.
  • heat resistance is usually insufficient, and thus it is believed that the organic electroluminescent device is accelerated by storage at a high temperature, or is accelerated by energization driving.
  • the present invention has found an unexpected effect that the heat resistance of the organic electroluminescence device is improved by the interaction of the low Tg compound and the high Tg compound by mixing the low Tg compound and the high Tg compound. It was. This is presumably because the thermal motion of the low Tg compound due to heat during high-temperature storage and heat generation during energization driving is suppressed by the high Tg compound present in the vicinity of the low Tg compound.
  • the solubility in an organic solvent can be improved and the storage stability of the composition can be ensured, and crystallization in the film of the organic electroluminescent device can be suppressed, and driving at room temperature is possible.
  • the lifetime can be extended.
  • a high Tg compound it is possible to suppress changes in film properties and morphology under high temperature storage near 100 ° C., which is a concern due to low Tg compounds, and stable and long driving life even after high temperature storage Can be obtained.
  • the reason why the Tg of the high Tg compound is 130 ° C. or higher is as described above. Further, when the Tg of the low Tg compound is 100 ° C. or lower, the interaction with the high Tg compound is suppressed, and the effect of suppressing the crystallization of the low Tg compound tends to be easily exhibited. When there is a difference of 30 ° C. or more as in the present invention, it is considered that the effects derived from each other's Tg are sufficiently developed.
  • the difference in Tg between the high Tg compound and the low Tg compound is not particularly limited, but is preferably 30 ° C or higher, more preferably 40 ° C or higher, and further preferably 50 ° C or higher.
  • 70 degrees C or less is preferable and 65 degrees C or less is more preferable.
  • the Tg difference is increased to some extent, and the high Tg compound is less susceptible to the molecular motion of the low Tg compound, so that the film morphology is less likely to change even at high temperatures.
  • the content of the low Tg compound is 8 to 70% by mass as described above. By being 8 mass% or more, there is an influence on the intermolecular interaction of the high Tg compound, and it is easy to suppress crystallization in the film and the organic solvent. Moreover, by being 70% by mass or less, the change in crystallinity during high-temperature storage caused by the low Tg compound can be absorbed by other materials less than 30% by mass, and the change in the morphology of the entire film is suppressed. It tends to be possible.
  • any of the high Tg compound and the low Tg compound has a high electron transporting property and a pyrimidine skeleton or a triazine skeleton excellent in structural stability, so that the probability that electrons are localized on the light emitting material is lowered and stable. Luminescence can be obtained. Therefore, the effect of extending the life can be sufficiently obtained. Furthermore, when the low Tg compound is a compound in which monocyclic compounds are bonded directly and / or via a linking group, the planarity as a molecule is lower and crystallization due to molecular packing is less likely to occur. Therefore, the effect of suppressing the crystallization can be further obtained.
  • the molecular weight of each non-light emitting material having a content of 1.0% by mass or more based on the total amount of all non-light emitting materials contained in the composition for forming a light emitting layer of the present invention is preferably 5000 or less.
  • the molecular weight is within this range, it is preferable that a film is formed in a state where most non-light emitting materials are uniformly mixed.
  • the high molecular weight compound is small in the film, the three-dimensional molecular entanglement is suppressed, and the high Tg compound and the low Tg compound are easily mixed uniformly. As a result, the generation of a minute region in which low Tg compounds are gathered is suppressed, and stability during high-temperature storage is easily obtained.
  • the molecular weight is not more than the upper limit of the molecular weight, the solubility of the compound in the solvent is improved, the entanglement of the molecular chain in the solvent is suppressed, and the impurities (that is, the deterioration-causing substance) can be easily removed.
  • the weighted average glass transition temperature of all non-light emitting materials contained in the composition for forming a light emitting layer is preferably 100 ° C. or higher, more preferably 115 ° C. or higher.
  • the weighted average glass transition temperature is preferably 150 ° C. or lower, more preferably 145 ° C. or lower.
  • the weighted average glass transition temperature is 100 ° C. or higher, the film morphology is less likely to change under the influence of heat during high-temperature storage and heat generated in the organic electroluminescence device when energized, that is, the driving life is more become longer.
  • the weighted average glass transition temperature is 150 ° C. or lower, the gaps between the molecules are easily filled, and the driving life is improved in terms of charge transportability in the film.
  • non-light emitting materials examples include additives such as a charge transport material and an antioxidant.
  • the composition for forming a light emitting layer of the present invention may contain a charge transport material that does not belong to either the high Tg compound or the low Tg compound. For convenience, this is referred to as a third charge transport material.
  • a third charge transport material As the third charge transport material, a material having a skeleton excellent in charge transportability is preferable.
  • skeleton having excellent charge transportability examples include aromatic structures, aromatic amine structures, triarylamine structures, dibenzofuran structures, naphthalene structures, phenanthrene structures, phthalocyanine structures, porphyrin structures, thiophene structures, benzylphenyl structures, Fluorene structure, quinacridone structure, triphenylene structure, carbazole structure, pyrene structure, anthracene structure, phenanthroline structure, quinoline structure, pyridine structure, pyrimidine structure, triazine structure, oxadiazole structure, imidazole structure and the like can be mentioned.
  • the third charge transporting material in the present invention is a material having a structure excellent in electron transporting property in that the light emitting material itself can suppress deterioration of the light emitting material due to transport of electrons and can extend the driving life. Is preferred.
  • a compound having a structure excellent in hole transportability is also preferable, and among the central skeleton excellent in charge transportability, a carbazole structure, dibenzofuran structure, triarylamine structure, naphthalene structure, phenanthrene structure or pyrene structure is a hole.
  • a structure excellent in transportability is preferable, and a carbazole structure, a dibenzofuran structure, or a triarylamine structure is more preferable.
  • the third charge transporting material in the present invention is a material having a structure excellent in hole transporting property in that the light emitting material itself can suppress the deterioration of the light emitting material due to transporting holes and can extend the driving life. Preferably there is.
  • the molecular weight of the third charge transport material in the present invention is arbitrary as long as the effects of the present invention are not significantly impaired.
  • the molecular weight of the third charge transport material in the present invention is usually 5000 or less, preferably 4000 or less, more preferably 3000 or less, and most preferably 2000 or less.
  • the molecular weight of the third charge transport material in the present invention is usually 300 or more, preferably 350 or more, more preferably 400 or more.
  • the molecular weight of the third charge transport material is large in that the film quality is hardly deteriorated due to gas generation, recrystallization, molecular migration, or the like.
  • the molecular weight of the third charge transport material is preferably small in that the organic compound can be easily purified and easily dissolved in a solvent.
  • the composition for forming a light emitting layer of the present invention preferably contains a third charge transport material that does not belong to either the high Tg compound or the low Tg compound. Two or more third charge transport materials may be used.
  • the light emitting layer according to the present invention is formed by a wet film forming method using the above-described composition for forming a light emitting layer of the present invention.
  • the wet film forming method refers to a film forming method, that is, a method in which a wet film forming method is employed as a coating method, and this coating film is dried to form a film.
  • coating methods include spin coating, dip coating, die coating, bar coating, blade coating, roll coating, spray coating, capillary coating, ink jet, nozzle printing, screen printing, and gravure. Examples thereof include a printing method and a flexographic printing method.
  • spin coating, spray coating, ink jet, nozzle printing, and the like are preferable.
  • the light emitting layer When the light emitting layer is formed by a wet film forming method, it is usually prepared by dissolving the above-described light emitting material, high Tg compound, low Tg compound, and other materials used as necessary in an appropriate organic solvent. A film is formed using the composition for forming a light emitting layer, and the organic solvent is removed by heating, decompression, or the like. As a method for removing the organic solvent, heating or reduced pressure can be used. As the heating means used in the heating method, a clean oven, a hot plate, or the like is preferable because heat is uniformly applied to the entire film.
  • the heating temperature in the heating step is arbitrary as long as the effects of the present invention are not significantly impaired. However, a higher temperature is preferable in terms of shortening the drying time, and a lower temperature is preferable in terms of less damage to the material.
  • the upper limit is usually 250 ° C. or lower, preferably 200 ° C. or lower, more preferably 150 ° C. or lower.
  • the lower limit is usually 30 ° C. or higher, preferably 50 ° C. or higher, more preferably 80 ° C. or higher.
  • the temperature is not more than the upper limit, decomposition or crystallization of a commonly used charge transport material or phosphorescent material can be suppressed.
  • the removal time of a solvent can be shortened because it is more than the said minimum.
  • the heating time in the heating step is appropriately determined depending on the boiling point and vapor pressure of the solvent in the composition for forming the light emitting layer, the heat resistance of the material, and the heating conditions.
  • Tg glass transition temperature
  • ⁇ Glass transition temperature measurement conditions Differential scanning calorimeter (DSC): Shimadzu DTA-50 Sample amount: about 4mg Sample container: Aluminum pan Atmosphere: Air Temperature range: Room temperature (25 ° C) to 300 ° C Temperature increase rate: 10 ° C / min The weighted average glass transition temperature is the sum of all non-luminescent materials multiplied by the weight ratio of each non-luminescent material to the Tg of each non-luminescent material determined by the above method.
  • DSC Differential scanning calorimeter
  • FIG. 1 is a schematic cross-sectional view showing a structural example of an organic electroluminescent device 10 according to the present invention.
  • 1 is a substrate
  • 2 is an anode
  • 3 is a hole injection layer
  • 4 is a hole transport layer
  • Reference numeral 5 denotes a light emitting layer
  • 6 denotes a hole blocking layer
  • 7 denotes an electron transport layer
  • 8 denotes an electron injection layer
  • 9 denotes a cathode.
  • the substrate 1 serves as a support for the organic electroluminescent element, and a quartz or glass plate, a metal plate or a metal foil, a plastic film or a sheet is usually used. Of these, glass plates and transparent synthetic resin plates such as polyester, polymethacrylate, polycarbonate, and polysulfone are preferable.
  • the substrate 1 is preferably made of a material having a high gas barrier property because the organic electroluminescence element is hardly deteriorated by the outside air. For this reason, when using a material having a low gas barrier property, such as a synthetic resin substrate, it is preferable to provide a dense silicon oxide film or the like on at least one surface of the substrate 1 to improve the gas barrier property.
  • the anode 2 has a function of injecting holes into the layer on the light emitting layer side.
  • the anode 2 is usually made of a metal such as aluminum, gold, silver, nickel, palladium, or platinum; a metal oxide such as an oxide of indium and / or tin; a metal halide such as copper iodide; a carbon black and a poly (3 -Methylthiophene), conductive polymers such as polypyrrole and polyaniline, and the like.
  • the anode 2 is often formed by a dry method such as a sputtering method or a vacuum deposition method.
  • an appropriate binder resin solution It can also be formed by being dispersed in and coated on a substrate.
  • a conductive polymer a thin film can be directly formed on the substrate by electrolytic polymerization, or the anode 2 can be formed by applying a conductive polymer on the substrate (Appl. Phys. Lett., 60, 2711, 1992).
  • the anode 2 usually has a single layer structure, but may have a laminated structure as appropriate. When the anode 2 has a laminated structure, different conductive materials may be laminated on the first anode.
  • the thickness of the anode 2 may be determined according to required transparency and material. In particular, when high transparency is required, a thickness at which visible light transmittance is 60% or more is preferable, and a thickness at which 80% or more is more preferable.
  • the thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably 500 nm or less. On the other hand, when transparency is not required, the thickness of the anode 2 may be arbitrarily set according to the required strength.
  • the anode 2 may have the same thickness as the substrate 1.
  • impurities on the anode are removed and the ionization potential thereof is adjusted by performing treatment such as ultraviolet ray + ozone, oxygen plasma, argon plasma before film formation. It is preferable to improve the hole injection property.
  • the layer responsible for transporting holes from the anode side to the light emitting layer side is usually called a hole injection transport layer or a hole transport layer.
  • the layer closer to the anode side may be referred to as the hole injection layer 3.
  • the hole injection layer 3 is preferably used from the viewpoint of enhancing the function of transporting holes from the anode to the light emitting layer side.
  • the hole injection layer 3 is usually formed on the anode.
  • the thickness of the hole injection layer 3 is usually 1 nm or more, preferably 5 nm or more, and usually 1000 nm or less, preferably 500 nm or less.
  • the formation method of the hole injection layer 3 may be a vacuum deposition method or a wet film formation method. In terms of excellent film forming properties, it is preferable to form the film by a wet film forming method.
  • the hole injection layer 3 preferably contains a hole transporting compound, and more preferably contains a hole transporting compound and an electron accepting compound. Further, the hole injection layer preferably contains a cation radical compound, and particularly preferably contains a cation radical compound and a hole transporting compound.
  • the composition for forming a hole injection layer usually contains a hole transporting compound that becomes the hole injection layer 3. In the case of a wet film forming method, a solvent is usually further contained. It is preferable that the composition for forming a hole injection layer has high hole transportability and can efficiently transport injected holes. For this reason, it is preferable that the hole mobility is high and impurities that become traps are less likely to be generated during production or use. Moreover, it is preferable that it is excellent in stability, has a small ionization potential, and has high transparency to visible light. In particular, when the hole injection layer 3 is in contact with the light emitting layer 5, it is preferable that the light emission from the light emitting layer 5 does not quench or that the light emitting layer 5 is exciplexed and the light emission efficiency is not lowered.
  • the hole transporting compound is preferably a compound having an ionization potential of 4.5 eV to 6.0 eV from the viewpoint of a charge injection barrier from the anode 2 to the hole injection layer 3.
  • hole transporting compounds include aromatic amine compounds, phthalocyanine compounds, porphyrin compounds, oligothiophene compounds, polythiophene compounds, benzylphenyl compounds, compounds in which tertiary amines are linked by a fluorene group, hydrazones Compound, silazane compound compound, quinacridone compound and the like.
  • an aromatic amine compound is preferable and an aromatic tertiary amine compound is particularly preferable from the viewpoint of amorphousness and visible light transmittance.
  • the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and includes a compound having a group derived from an aromatic tertiary amine.
  • the type of the aromatic tertiary amine compound is not particularly limited, but is a polymer compound having a weight average molecular weight of 1,000 to 1,000,000 (polymerization compound in which repeating units are linked) from the viewpoint of easily obtaining uniform light emission due to the surface smoothing effect. Is preferably used.
  • Preferable examples of the aromatic tertiary amine polymer compound include a polymer compound having a repeating unit represented by the following formula (II).
  • Ar 1 and Ar 2 each independently represent an aromatic group that may have a substituent or a heteroaromatic group that may have a substituent.
  • Ar 3 To Ar 5 each independently represents an optionally substituted aromatic group or an optionally substituted heteroaromatic group, wherein Y is selected from the following group of linking groups. Represents a selected linking group, and among Ar 1 to Ar 5 , two groups bonded to the same N atom may be bonded to each other to form a ring.
  • the linking group is shown below.
  • Ar 6 to Ar 16 each independently represents an aromatic group which may have a substituent or a heteroaromatic group which may have a substituent.
  • R 105 and R 106 each independently represents a hydrogen atom or an arbitrary substituent.
  • the aromatic group and heteroaromatic group of Ar 1 to Ar 16 include a benzene ring, a naphthalene ring, a phenanthrene ring, a thiophene ring, or pyridine from the viewpoint of the solubility, heat resistance, and hole injection / transport properties of the polymer compound.
  • a group derived from a ring is preferable, and a group derived from a benzene ring or a naphthalene ring is more preferable.
  • Specific examples of the aromatic tertiary amine polymer compound having a repeating unit represented by the formula (II) include those described in International Publication No. 2005/089024.
  • the hole injection layer 3 preferably contains an electron accepting compound because the conductivity of the hole injection layer 3 can be improved by oxidation of the hole transporting compound.
  • an electron accepting compound a compound having an oxidizing power and the ability to accept one electron from the above-described hole-transporting compound is preferable, and specifically, a compound having an electron affinity of 4 eV or more is preferable. More preferably, the compound is 5 eV or more.
  • electron-accepting compounds include triarylboron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of arylamines and metal halides, and salts of arylamines and Lewis acids.
  • examples thereof include one or more compounds selected from the group. Specifically, onium salts substituted with organic groups such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate and triphenylsulfonium tetrafluoroborate (WO 2005/089024 pamphlet); High-valent inorganic compounds such as iron (III) (Japanese Patent Laid-Open No.
  • ⁇ Cation radical compound an ionic compound composed of a cation radical which is a chemical species obtained by removing one electron from a hole transporting compound and a counter anion is preferable.
  • the cation radical is derived from a hole transporting polymer compound
  • the cation radical has a structure in which one electron is removed from the repeating unit of the polymer compound.
  • the cation radical is preferably a chemical species obtained by removing one electron from the compound described above as the hole transporting compound.
  • a chemical species obtained by removing one electron from a compound preferable as a hole transporting compound is preferable in terms of amorphousness, visible light transmittance, heat resistance, solubility, and the like.
  • the cation radical compound can be generated by mixing the hole transporting compound and the electron accepting compound. That is, by mixing the hole transporting compound and the electron accepting compound, electron transfer occurs from the hole transporting compound to the electron accepting compound, and the cation radical and the counter anion of the hole transporting compound A cation ion compound consisting of
  • Oxidative polymerization here refers to oxidation of a monomer chemically or electrochemically with peroxodisulfate in an acidic solution.
  • the monomer is polymerized by oxidation, and a cation radical that is removed from the polymer repeating unit by using an anion derived from an acidic solution as a counter anion is removed.
  • a material for forming the hole injection layer 3 is usually mixed with a soluble solvent (hole injection layer solvent) to form a film forming composition (positive Hole injecting layer forming composition) is prepared, and this hole injecting layer forming composition is applied onto a layer corresponding to the lower layer of the hole injecting layer 3 (usually the anode 2) to form a film and dried. To form.
  • a film forming composition positive Hole injecting layer forming composition
  • the concentration of the hole transporting compound in the composition for forming a hole injection layer is arbitrary as long as the effects of the present invention are not significantly impaired, but in terms of film thickness uniformity, the lower one is preferable. From the viewpoint that defects are unlikely to occur in the hole injection layer 3, a higher value is preferable. Specifically, it is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, and on the other hand, 70% by mass. The content is preferably less than 60% by mass, more preferably 60% by mass or less, and particularly preferably 50% by mass or less.
  • ether solvents examples include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA), 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, and anisole.
  • PGMEA propylene glycol-1-monomethyl ether acetate
  • Aromatic ethers such as phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole and 2,4-dimethylanisole.
  • ester solvent examples include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate.
  • aromatic hydrocarbon solvent examples include toluene, xylene, cyclohexylbenzene, 3-isopropylbiphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, methylnaphthalene and the like.
  • amide solvent examples include N, N-dimethylformamide and N, N-dimethylacetamide.
  • Formation of the hole injection layer 3 by a wet film formation method is usually performed after preparing a composition for forming a hole injection layer, and then forming the composition on a layer (usually the anode 2) corresponding to the lower layer of the hole injection layer 3
  • the film is formed by coating and drying.
  • the hole injection layer 3 is dried by heating or drying under reduced pressure after film formation.
  • the hole injection layer 3 is formed by vacuum vapor deposition
  • one or more of the constituent materials of the hole injection layer 3 are usually vacuumed.
  • a crucible installed in the container if two or more kinds of materials are used, usually put each in separate crucibles
  • evacuate the vacuum container to about 10 -4 Pa with a vacuum pump, then heat the crucible (When using two or more types of materials, each crucible is usually heated) and evaporated while controlling the amount of evaporation of the material in the crucible (when using two or more types of materials, each is usually independent.
  • the hole injection layer 3 is formed on the anode on the substrate placed facing the crucible.
  • the hole injection layer 3 can also be formed by putting a mixture thereof in a crucible, heating and evaporating the mixture.
  • the degree of vacuum at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 ⁇ 10 ⁇ 6 Torr (0.13 ⁇ 10 ⁇ 4 Pa) or more and 9.0 ⁇ 10 ⁇ 6 Torr ( 12.0 ⁇ 10 ⁇ 4 Pa) or less.
  • the deposition rate is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 to 5.0 liters / second or more.
  • the film forming temperature at the time of vapor deposition is not limited as long as the effects of the present invention are not significantly impaired, but it is preferably performed at 10 ° C. or higher and 50 ° C. or lower.
  • the hole transport layer 4 is a layer having a function of transporting holes from the anode side to the light emitting layer side.
  • the hole transport layer 4 is not an essential layer in the organic electroluminescence device of the present invention, but it is preferable to use this layer in terms of enhancing the function of transporting holes from the anode 2 to the light emitting layer 5.
  • the hole transport layer 4 is usually formed between the anode 2 and the light emitting layer 5. Further, when there is the hole injection layer 3 described above, it is formed between the hole injection layer 3 and the light emitting layer 5.
  • the film thickness of the hole transport layer 4 is usually 5 nm or more, preferably 10 nm or more, and is usually 300 nm or less, preferably 100 nm or less.
  • the formation method of the hole transport layer 4 may be a vacuum deposition method or a wet film formation method. In terms of excellent film forming properties, it is preferable to form the film by a wet film forming method.
  • the hole transport layer 4 usually contains a hole transport compound that becomes the hole transport layer 4.
  • the hole transporting compound contained in the hole transporting layer 4 in particular, two or more tertiary compounds represented by 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl are used.
  • Aromatic diamines containing two or more condensed aromatic rings, including amines, substituted with nitrogen atoms Japanese Patent Laid-Open No. 5-234811
  • An aromatic amine compound having a starburst structure J. Lumin., 72-74, 985, 1997), an aromatic amine compound comprising a tetramer of triphenylamine (Chem. Commun., 2175) 1996), 2,2 ′, 7,7′-tetrakis- (diphenylamino) -9,9′-spirobifluorene and other spiro compounds (Synth.
  • carbazole derivatives such as 4,4′-N, N′-dicarbazolebiphenyl.
  • polyvinyl carbazole polyvinyl triphenylamine (Japanese Patent Laid-Open No. 7-53953), polyarylene ether sulfone (Polym. Adv. Tech., 7, 33, 1996) containing tetraphenylbenzidine, etc. It can be preferably used.
  • the hole injection layer 3 is usually replaced with the hole injection layer forming composition in the same manner as in the case of forming the hole injection layer 3 by a wet film formation method. It forms using the composition for positive hole transport layer formation.
  • the composition for forming a hole transport layer usually further contains a solvent.
  • the solvent used in the composition for forming a hole transport layer the same solvent as the solvent used in the composition for forming a hole injection layer can be used.
  • the concentration of the hole transporting compound in the composition for forming a hole transport layer can be in the same range as the concentration of the hole transporting compound in the composition for forming a hole injection layer.
  • Formation of the hole transport layer 4 by a wet film formation method can be performed in the same manner as the film formation method of the hole injection layer 3 described above.
  • the positive hole injection layer 3 is usually formed in place of the composition for forming the hole injection layer in the same manner as in the case of forming the hole injection layer 3 by the vacuum deposition method. It can be formed using a composition for forming a hole transport layer. Film formation conditions such as the degree of vacuum at the time of vapor deposition, the vapor deposition rate, and the temperature can be formed under the same conditions as those for the vacuum vapor deposition of the hole injection layer 3.
  • the light emitting layer 5 is a layer having a function of emitting light when excited by recombination of holes injected from the anode 2 and electrons injected from the cathode 9 when an electric field is applied between a pair of electrodes. .
  • the light emitting layer 5 is a layer formed between the anode 2 and the cathode 9, and the light emitting layer 5 is provided between the hole injection layer 3 and the cathode 9 when the hole injection layer 3 is on the anode 2.
  • the hole transport layer 4 is formed on the anode 2, it is formed between the hole transport layer 4 and the cathode 9.
  • the thickness of the light-emitting layer 5 is arbitrary as long as the effects of the present invention are not significantly impaired. However, it is preferable that the thickness of the light-emitting layer 5 is small in that it is difficult to cause defects in the film. Is preferred. Specifically, the thickness is usually 3 nm or more, preferably 5 nm or more, and usually 200 nm or less, preferably 100 nm or less. In the organic electroluminescent element, two or more light emitting layers may be provided. The details of the light emitting layer 5 are as described above. When forming light emitting layers other than the light emitting layer based on this invention by a vacuum evaporation method, it forms as follows.
  • the constituent materials of the light emitting layer are usually placed in separate crucibles installed in the vacuum container, Is evacuated to about 10 ⁇ 4 Pa with a vacuum pump, and each crucible is heated to evaporate while independently controlling the evaporation amount of the material in each crucible, and on the substrate or the like placed facing each crucible.
  • the light-emitting layer can also be formed by placing a mixture of constituent materials in one crucible and heating and evaporating the mixture.
  • the degree of vacuum at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 ⁇ 10 ⁇ 6 Torr (0.13 ⁇ 10 ⁇ 4 Pa) or more and 9.0 ⁇ 10 ⁇ 6 Torr ( 12.0 ⁇ 10 ⁇ 4 Pa) or less.
  • the deposition rate is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 to 5.0 liters / second or more.
  • the film forming temperature at the time of vapor deposition is not limited as long as the effects of the present invention are not significantly impaired, but it is preferably performed at 10 ° C. or higher and 50 ° C. or lower.
  • a hole blocking layer 6 may be provided between the light emitting layer 5 and an electron injection layer 8 described later.
  • the hole blocking layer 6 is a layer stacked on the light emitting layer 5 so as to be in contact with the cathode side interface of the light emitting layer 5.
  • the hole blocking layer 6 has a role of blocking holes moving from the anode 2 from reaching the cathode 9 and a role of efficiently transporting electrons injected from the cathode 9 toward the light emitting layer 5.
  • Have The physical properties required for the material constituting the hole blocking layer 6 include high electron mobility, low hole mobility, a large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). Is high.
  • Examples of the material of the hole blocking layer 6 satisfying such conditions include bis (2-methyl-8-quinolinolato) (phenolato) aluminum, bis (2-methyl-8-quinolinolato) (triphenylsilanolato) aluminum.
  • Mixed ligand complexes such as bis (2-methyl-8-quinolato) aluminum- ⁇ -oxo-bis- (2-methyl-8-quinolinolato) aluminum binuclear metal complexes, distyrylbiphenyl derivatives, etc.
  • Styryl compounds Japanese Patent Laid-Open No.
  • the thickness of the hole blocking layer 6 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less. is there.
  • the electron transport layer 7 is provided between the light emitting layer 5 and the electron injection layer 8 for the purpose of further improving the current efficiency of the device.
  • the electron transport layer 7 is formed of a compound capable of efficiently injecting electrons from the cathode 9 or the electron injection layer 8 between the electrodes to which an electric field is applied, and efficiently transporting electrons in the direction of the light emitting layer 5.
  • the electron transporting compound used for the electron transporting layer 7 a compound that has high electron injection efficiency from the cathode 9 or the electron injection layer 8 and can efficiently transport the injected electrons is usually preferable.
  • Specific examples of the electron transporting compound include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No.
  • the thickness of the electron transport layer 7 is usually 1 nm or more, preferably 5 nm or more, and is usually 300 nm or less, preferably 100 nm or less.
  • the electron transport layer 7 is formed by laminating on the hole blocking layer 6 by a wet film formation method or a vacuum deposition method in the same manner as described above. Usually, a vacuum deposition method is used.
  • An electron injection layer 8 may be provided between the cathode 9 and the electron transport layer 7 or the light emitting layer 5.
  • the electron injection layer 8 plays a role of efficiently injecting electrons injected from the cathode 9 into the electron transport layer 7 or the light emitting layer 5.
  • the material for forming the electron injection layer 8 is preferably a metal having a low work function. Examples include alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium.
  • the film thickness is usually preferably from 0.1 nm to 5 nm.
  • an organic electron transport material represented by a metal complex such as a nitrogen-containing heterocyclic compound such as bathophenanthroline or an aluminum complex of 8-hydroxyquinoline is doped with an alkali metal such as sodium, potassium, cesium, lithium, rubidium ( (Described in JP-A-10-270171, JP-A-2002-1000047, JP-A-2002-1000048, etc.) also improves electron injection / transport and makes it possible to achieve both excellent film quality. preferable.
  • the film thickness is usually in the range of 5 nm or more, preferably 10 nm or more, and usually 200 nm or less, preferably 100 nm or less.
  • the electron injection layer 8 is formed by laminating on the light emitting layer 5 or the hole blocking layer thereon by a wet film formation method or a vacuum deposition method. The details of the wet film forming method are the same as those of the light emitting layer 5 described above.
  • the cathode 9 plays a role of injecting electrons into a layer on the light emitting layer side (such as the electron injection layer 8 or the light emitting layer 5).
  • the material used for the anode 2 can be used.
  • a metal having a low work function Metals such as indium, calcium, aluminum and silver, or alloys thereof. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.
  • the cathode 9 made of a metal having a low work function by laminating a metal layer having a high work function and stable to the atmosphere on the cathode 9.
  • the metal to be laminated include metals such as aluminum, silver, copper, nickel, chromium, gold, and platinum.
  • the thickness of the cathode is usually the same as that of the anode 2.
  • the organic electroluminescent element of the present invention may further have other layers as long as the effects of the present invention are not significantly impaired.
  • any other layer described above may be provided between the anode 2 and the cathode 9.
  • ⁇ Other element configuration> The structure opposite to that described above, that is, a cathode, an electron injection layer, a light emitting layer, a hole injection layer, and an anode can be stacked in this order on the substrate.
  • Example 1 An organic electroluminescent element having the configuration shown in FIG. 1 was produced.
  • the anode 2 was formed by patterning.
  • the substrate 1 (ITO substrate) on which the anode 2 was formed was cleaned in the order of ultrasonic cleaning with pure water and then with pure water, dried by nitrogen blowing, and finally subjected to ultraviolet ozone cleaning.
  • the hole injection layer 3 was formed by a wet film formation method as follows.
  • a hole-transporting compound 2.0% by mass of a polymer compound having a repeating structure represented by the following formula (P1) (weight average molecular weight 52000) and 4-isopropyl-4′-methyldiphenyl as an electron-accepting compound
  • P1 weight average molecular weight 52000
  • 4-isopropyl-4′-methyldiphenyl as an electron-accepting compound
  • a composition for forming a hole injection layer in which 0.4% by mass of iodonium tetrakis (pentafluorophenyl) borate and ethyl benzoate were dissolved was prepared, and this composition for forming a hole injection layer was formed on the ITO substrate.
  • a hole injection layer 3 having a film thickness of 32 nm was formed by film formation by spin coating and further heat drying. The film forming conditions were as follows.
  • ⁇ Film formation conditions Spin coating conditions: Spinner rotation speed 500 rpm / 2 seconds ⁇ 2100 rpm / 30 seconds Heating drying conditions: Leave in a clean oven at 230 ° C. for 1 hour
  • a hole transport layer 4 was formed on the formed hole injection layer 3 by a wet film forming method as follows.
  • a polymer compound (HT-1) having a repeating structure shown below was dissolved in cyclohexylbenzene as a solvent to prepare a composition for forming a hole transport layer.
  • the concentration of the polymer compound (HT-1) in the composition for forming a hole transport layer was 2.0% by mass.
  • the composition for forming a hole transport layer is formed on the hole injection layer 3 by a spin coat method, and further heated and dried to cause the polymer compound (HT-1) to undergo a crosslinking reaction to be cured, A hole transport layer 4 having a thickness of 21 nm was formed.
  • the film forming conditions were as follows. ⁇ Film formation conditions> Spin coating conditions: Spinner rotation speed 500 rpm / 2 seconds ⁇ 2900 rpm / 120 seconds Heat drying conditions: Leave on a hot plate at 230 ° C. for 1 hour
  • the light emitting layer 5 was formed on the formed hole transport layer 4 as follows.
  • the following compounds (HH-1), (HH-2), (H-1), (LH-1) and (D-1) were mixed at a mass ratio of 35: 20: 35: 10: 15.
  • a composition for forming a light emitting layer in which xylene was dissolved in xylene so that the mixture was 3.45% by mass was prepared, and the composition for forming a light emitting layer was spin-coated on the hole transport layer 4 in a nitrogen atmosphere.
  • the light emitting layer 5 having a film thickness of 59 nm was formed by forming a film by the method and further drying by heating.
  • the film forming conditions were as follows.
  • ⁇ Film formation conditions Spin coating conditions: Spinner rotation speed 500 rpm / 2 seconds ⁇ 1700 rpm / 120 seconds Heating drying conditions: Standing on a hot plate at 120 ° C. for 20 minutes
  • the compounds (HH-1), (HH-2), (H-1) and (LH-1) have Tg of 159 ° C., 142 ° C., 113 ° C. and 90 ° C., respectively, and non-light emitting materials Therefore, (HH-1) and (HH-2) correspond to the high Tg compound of the present invention, and (LH-1) corresponds to the low Tg compound of the present invention.
  • the low Tg compound (LH-1) has a pyrimidine skeleton, and monocyclic compounds are bonded to each other through a direct bond and / or a linking group.
  • the molecular weight of each compound is 968.4, 866.3, 636.3, 841 for (HH-1), (HH-2), (H-1), (LH-1) and (D-1), respectively. 4 and 1363.9, both of which had a molecular weight of 5000 or less.
  • the content rate of the low Tg compound with respect to the total amount of all the nonluminous materials contained in the composition for light emitting layer formation was 10 mass%, and the weighted average glass transition temperature of all the nonluminous materials was 133 degreeC.
  • a compound (HB-1) shown below was formed as a hole blocking layer 6 on the formed light emitting layer 5 by a vacuum deposition method so as to have a film thickness of 10 nm.
  • a compound (ET-1) shown below as an electron transport layer 7 was formed on the formed hole blocking layer 6 by a vacuum deposition method so as to have a film thickness of 20 nm.
  • the element that has been vapor-deposited up to the electron transport layer 7 is once taken out from the vacuum vapor deposition apparatus into the atmosphere, and used as a cathode vapor deposition mask with a 2 mm width in a shape orthogonal to the ITO stripe as the anode.
  • a stripe shadow mask is brought into close contact with the element, placed in another vacuum vapor deposition apparatus, and lithium fluoride (LiF) is formed to a thickness of 0.5 nm as the electron injection layer 8 by the same vacuum vapor deposition method as the electron transport layer 7.
  • LiF lithium fluoride
  • aluminum was laminated as the cathode 9 so as to have a film thickness of 80.0 nm.
  • sealing treatment was performed by the method described below.
  • a photocurable resin was applied to the outer periphery of a 23 mm ⁇ 23 mm size glass plate with a width of about 1 mm, and a moisture getter sheet was installed in the center.
  • finished cathode formation was bonded together so that the vapor-deposited surface might oppose a desiccant sheet.
  • coated was irradiated with ultraviolet light, and resin was hardened. Thereby, the organic electroluminescent element which has a light emission area part of 2 mm x 2 mm size was obtained.
  • Example 2 In Example 1, the compounds (HH-2), (LH-1), (LH-2), (H-1) and (D-) are used as the non-light emitting material and the light emitting material contained in the light emitting layer forming composition.
  • An organic electroluminescent element was produced in the same manner as in Example 1 except that 1) was changed to a mixture of 15: 15: 15: 55: 15 at a mass ratio.
  • Compound (LH-2) was a compound having the structure shown below, Tg was 87 ° C., and molecular weight was 762.3. Moreover, the content rate of the low Tg compound with respect to the total amount of all the nonluminous materials contained in the composition for light emitting layer formation was 30 mass%, and the weighted average glass transition temperature of all the nonluminous materials was 110 degreeC.
  • Example 3 In Example 1, compounds (HH-1), (H-2), (H-3), (LH-1) and (D-) are used as the non-light-emitting materials and the light-emitting materials contained in the composition for forming a light-emitting layer.
  • An organic electroluminescent element was produced in the same manner as in Example 1 except that 1) was changed to a mixture of 35: 15: 35: 15: 15 at a mass ratio.
  • Compounds (H-2) and (H-3) are compounds having the following structures, Tg was 129 ° C. and 109 ° C., respectively, and molecular weights were 791.3 and 1157.5, respectively. .
  • the content rate of the low Tg compound with respect to the total amount of all the non-light-emitting materials contained in the composition for forming a light-emitting layer was 15% by mass, and the weighted average glass transition temperature of all the non-light-emitting materials was 127 ° C.
  • Example 4 In Example 1, as a non-light-emitting material and a light-emitting material contained in the composition for forming a light-emitting layer, the compounds (HH-1), (LH-1) and (D-1) were mixed at a mass ratio of 70:30:15. An organic electroluminescent element was produced in the same manner as in Example 1 except that the mixture was changed to that mixed in the above.
  • the content rate of the low Tg compound with respect to the total amount of all non-light-emitting materials contained in the composition for forming a light-emitting layer was 30% by mass, and the weighted average glass transition temperature of all the non-light-emitting materials was 138 ° C.
  • Example 5 In Example 1, (HH-1), (H-2), (LH-1), and (D-1) were used as the non-light-emitting material and the light-emitting material included in the composition for forming a light-emitting layer.
  • An organic electroluminescent element was produced in the same manner as in Example 1 except that the mixture was changed to a mixture with a mass ratio of 15:15.
  • the content rate of the low Tg compound with respect to the total amount of all the non-light-emitting materials contained in the composition for forming a light-emitting layer was 15% by mass, and the weighted average glass transition temperature of all the non-light-emitting materials was 144 ° C. there were.
  • Example 6 In Example 1, (HH-1), (H-3), (LH-1), and (D-1) were used as the non-light-emitting material and the light-emitting material included in the light-emitting layer forming composition: An organic electroluminescent element was produced in the same manner as in Example 1 except that the mixture was changed to a mixture at a mass ratio of 35:30:15. The content of the low Tg compound with respect to the total amount of all the non-light-emitting materials contained in the composition for forming a light-emitting layer was 30% by mass, and the weighted average glass transition temperature of all the non-light-emitting materials was 121 ° C. there were.
  • Example 1 (LH-1), (LH-2), (H-3) and (D-1) were used as non-light emitting materials and light emitting materials contained in the composition for forming a light emitting layer at 30:35.
  • An organic electroluminescence device was produced in the same manner as in Example 1 except that the mixture was changed to a mixture at a mass ratio of 35:15.
  • the weighted average glass transition temperature of all non-luminescent materials was 96 ° C.
  • Example 2 (Comparative Example 2) In Example 1, (HH-1), (HH-2), and (D-1) as a non-light emitting material and a light emitting material contained in the composition for forming a light emitting layer were mixed at a mass ratio of 70:30:15. An organic electroluminescent element was produced in the same manner as in Example 1 except that the mixture was changed to that mixed in the above. The weighted average glass transition temperature of all non-luminescent materials was 154 ° C. And production
  • Example 7 An organic electroluminescent element having the configuration shown in FIG. 2 was produced.
  • the content rate of the low Tg compound with respect to the total amount of all non-light-emitting materials contained in the composition for forming a light-emitting layer was 30% by mass, and the weighted average glass transition temperature of all the non-light-emitting materials was 112 ° C.
  • Example 8 In Example 7, compounds (HH-1), (LH-3), and (D-1) as a non-light-emitting material and a light-emitting material contained in the light-emitting layer forming composition were mixed at a mass ratio of 70:30:15.
  • An organic electroluminescent element was produced in the same manner as in Example 7 except that the mixture was changed to a mixed one.
  • Compound (LH-3) was a compound having the structure shown below, Tg was 95 ° C., and molecular weight was 586.2. Moreover, the content rate of the low Tg compound with respect to the total amount of all the nonluminous materials contained in the composition for light emitting layer formation was 30 mass%, and the weighted average glass transition temperature of all the nonluminous materials was 140 degreeC.
  • Example 9 In Example 7, the compounds (HH-1), (LH-1), (LH-3), and (D-1) were used as the non-light emitting material and the light emitting material contained in the light emitting layer forming composition.
  • An organic electroluminescent element was produced in the same manner as in Example 7 except that the mixture was changed to a mixture of 15:15 by mass.
  • the content of the low Tg compound with respect to the total amount of all the non-light-emitting materials contained in the composition for forming a light-emitting layer was 30% by mass, and the weighted average glass transition temperature of all the non-light-emitting materials was 139 ° C.
  • Example 10 (Example 10) In Example 7, compounds (HH-1), (LH-1) and (D-1) as a non-light-emitting material and a light-emitting material included in the composition for forming a light-emitting layer were mixed at a mass ratio of 70:30:15. An organic electroluminescent element was produced in the same manner as in Example 7 except that the mixture was changed to a mixed one.
  • the content rate of the low Tg compound with respect to the total amount of all non-light-emitting materials contained in the composition for forming a light-emitting layer was 30% by mass, and the weighted average glass transition temperature of all the non-light-emitting materials was 138 ° C.
  • Example 7 (Comparative Example 3) In Example 7, compounds (HH-1), (LH-4) and (D-1) as a non-light emitting material and a light emitting material contained in the composition for forming a light emitting layer in a mass ratio of 70:30:15 An organic electroluminescent element was produced in the same manner as in Example 7 except that the mixture was changed to a mixed one.
  • Compound (LH-4) was a compound having the structure shown below, Tg was 95 ° C., and molecular weight was 930.2. Moreover, the weighted average glass transition temperature of all the non-light-emitting materials was 140 ° C.
  • Example 7 (Comparative Example 4) In Example 7, compounds (HH-1), (LH-5) and (D-1) as a non-light-emitting material and a light-emitting material contained in the composition for forming a light-emitting layer were mixed at a weight ratio of 70:30:15. An organic electroluminescent element was produced in the same manner as in Example 7 except that the mixture was changed to a mixed one.
  • Compound (LH-5) was a compound having the structure shown below, Tg was 86 ° C., and molecular weight was 612.8. Moreover, the weighted average glass transition temperature of all the non-light-emitting materials was 137 ° C.
  • Example 7 Comparative Example 5
  • compounds (HH-1), (LH-1) and (D-1) as a non-light-emitting material and a light-emitting material contained in the composition for forming a light-emitting layer were used at a mass ratio of 95: 5: 15.
  • An organic electroluminescent element was produced in the same manner as in Example 7 except that the mixture was changed to a mixed one.
  • the weighted average glass transition temperature of all non-light emitting materials was 156 ° C.
  • Comparative Examples 3 and 4 which do not include any of the material having a pyrimidine skeleton and the material having a triazine skeleton as the non-light emitting material have a small LT85 after heating. Moreover, although the material which has a pyrimidine frame
  • the present invention relates to various fields in which an organic electroluminescent element is used as a composition for forming a light emitting layer of an organic electroluminescent element, for example, as a flat panel display (for example, for OA computers and wall-mounted televisions) and a surface light emitter. It can be suitably used in the fields of light sources that make use of features (for example, light sources of copiers, backlight light sources of liquid crystal displays and instruments), display boards, marker lamps, and illumination devices.

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Abstract

The purpose of the present invention is to provide an organic electroluminescent element which has a long service life and excellent storage stability; and the present invention provides a composition for forming a light emitting layer, which is suitable for the organic electroluminescent element. The present invention specifically provides a composition for forming a light emitting layer of an organic electroluminescent element, which contains a light emitting material, a non-light-emitting material and an organic solvent, and which is characterized in that: the light emitting material may be composed of one or more materials; the non-light-emitting material contains a high Tg compound having a glass transition temperature of not less than 130°C and a low Tg compound having a glass transition temperature of not more than 100°C; the content ratio of the low Tg compound relative to all the non-light-emitting materials is 10-70% by weight; and at least one of the non-light-emitting materials has a pyrimidine skeleton or a triazine skeleton.

Description

発光層形成用組成物及び該発光層形成用組成物を含有する有機電界発光素子Light emitting layer forming composition and organic electroluminescent device containing the light emitting layer forming composition
　本発明は、発光層形成用組成物と、この発光層形成用組成物を含有する有機電界発光素子関するものである。 The present invention relates to a composition for forming a light emitting layer and an organic electroluminescent device containing the composition for forming a light emitting layer.
　有機電界発光素子は、簡単な素子構成で様々な色に発光することができることから、近年、ディスプレイや照明等の発光装置を製造するための技術として、盛んに開発が行われている。
　有機電界発光素子は、陽極及び陰極から正孔及び電子を注入し、発光層に各電荷を到達させ、この発光層で電荷再結合させることで、発光を得るものである。この原理から、通常、発光材料だけでなく、電荷輸送材料を含有する発光層形成用組成物を用いて発光層を形成し、電荷を発光層内に留めることにより、発光効率を向上させることが検討されている（特許文献１参照）。 Since organic electroluminescent elements can emit light in various colors with a simple element configuration, in recent years, they have been actively developed as a technique for manufacturing light emitting devices such as displays and lighting.
The organic electroluminescence device obtains light emission by injecting holes and electrons from an anode and a cathode, allowing each charge to reach the light emitting layer, and recombining the charge in this light emitting layer. From this principle, it is possible to improve luminous efficiency by forming a light emitting layer using a composition for forming a light emitting layer containing not only a light emitting material but also a charge transport material, and retaining charges in the light emitting layer. It has been studied (see Patent Document 1).
　一方で、電荷を発光層に留めることは、有機電界発光素子の電流－電圧特性を悪化させる。一つの層に電荷を留めるには、通常、膜内に電荷のトラップ準位をつくり電荷を留める方法等により行われる。これらの方法によれば、電荷を発光層に留めることにより、発光効率を上げることが可能であるが、同時に、電流－電圧特性を悪化させる、すなわち有機電界発光素子の駆動電圧の上昇につながる。駆動電圧が高くなると、消費電力が増えてしまうため、例えば、発光層形成用組成物に含有される電荷輸送材料の総数を３種類以上とすることにより駆動電圧化を低下させる技術が提案されている（特許文献２参照）。
　しかしながら、電荷輸送材料の種類を増やした場合に、有機電界発光素子の重要な特性である駆動寿命を向上させる手法や、高温における保存安定性を維持する手法については、未だ検討が不十分であると考えられる。 On the other hand, retaining the charge in the light emitting layer deteriorates the current-voltage characteristics of the organic electroluminescent element. In order to retain a charge in one layer, it is generally performed by a method of retaining a charge by creating a charge trap level in the film. According to these methods, it is possible to increase the light emission efficiency by retaining the charge in the light emitting layer, but at the same time, the current-voltage characteristics are deteriorated, that is, the driving voltage of the organic electroluminescent element is increased. Since the power consumption increases as the driving voltage increases, for example, a technique for reducing the driving voltage by setting the total number of charge transport materials contained in the composition for forming a light emitting layer to three or more has been proposed. (See Patent Document 2).
However, when the number of types of charge transport materials is increased, there are still insufficient studies on methods for improving the driving life, which is an important characteristic of organic electroluminescent devices, and methods for maintaining storage stability at high temperatures. it is conceivable that.
日本国特開２００５－２１９５１３号公報Japanese Unexamined Patent Publication No. 2005-219513 国際公開ＷＯ２０１３／０６９３３８号パンフレットInternational Publication WO2013 / 069338 Pamphlet
　本発明は、駆動寿命が長くかつ保存安定性に優れた有機電界発光素子を提供することを目的とし、それに適した発光層形成用組成物を提供することを課題とする。 An object of the present invention is to provide an organic electroluminescence device having a long driving life and excellent storage stability, and an object thereof is to provide a composition for forming a light emitting layer suitable for the organic electroluminescence device.
　この課題に対し、本発明者らが鋭意検討を行った結果、ガラス転移温度が、所定の温度より高い化合物と、所定の温度より低い化合物を発光層形成用組成物に用いることで、駆動寿命が長く、かつ高温保存後でも駆動寿命が低下しにくい有機電界発光素子が得られることを見出した。
　本発明はこのような知見に基づいて達成されたものであり、以下を要旨とする。
［１］発光材料、非発光材料、及び有機溶媒を含む、有機電界発光素子の発光層形成用組成物であって、該非発光材料は、ガラス転移温度が１３０℃以上である高Ｔｇ化合物及びガラス転移温度が１００℃以下である低Ｔｇ化合物とを含み、全ての該非発光材料に対する該低Ｔｇ化合物の含有率が８～７０質量％であり、該非発光材料の内、少なくとも一つはピリミジン骨格又はトリアジン骨格を有する材料である、発光層形成用組成物。
［２］前記発光層形成用組成物に含まれる全ての前記非発光材料の総量に対する含有率が１．０質量％以上である全ての各非発光材料の分子量が５０００以下である、［１］に記載の発光層形成用組成物。
［３］全ての前記発光材料の分子量が５０００以下である、［１］又は［２］に記載の発光層形成用組成物。
［４］前記発光層形成用組成物に含まれる、ピリミジン骨格又はトリアジン骨格を有する材料が、前記高Ｔｇ化合物及び／又は前記低Ｔｇ化合物である、［１］～［３］のいずれか１項に記載の発光層形成用組成物。
［５］前記発光層形成用組成物に含まれる全ての前記非発光材料の加重平均ガラス転移温度が１００℃以上である、［１］～［４］のいずれか１項に記載の発光層形成用組成物。
［６］前記低Ｔｇ化合物が、単環化合物同士が直接結合及び／又は連結基を介して結合した化合物である、［１］～［５］に記載の発光層形成用組成物。
［７］前記低Ｔｇ化合物が、芳香族炭化水素単環化合物同士が直接結合及び／又は連結基を介して結合した化合物のみからなる、［１］～［６］のいずれか１項に記載の発光層形成用組成物。
［８］前記低Ｔｇ化合物が、下記の構造式（Ａ）で表される化合物である、［１］～［７］のいずれか１項に記載の発光層形成用組成物。 As a result of intensive studies by the present inventors on this problem, a driving life is obtained by using a compound having a glass transition temperature higher than a predetermined temperature and a compound lower than the predetermined temperature for the composition for forming a light emitting layer. It has been found that an organic electroluminescent element is obtained that is long and has a drive life that does not easily decrease even after high-temperature storage.
The present invention has been achieved based on such findings, and the gist thereof is as follows.
[1] A composition for forming a light-emitting layer of an organic electroluminescent device, comprising a light-emitting material, a non-light-emitting material, and an organic solvent, the non-light-emitting material comprising a high Tg compound and glass having a glass transition temperature of 130 ° C. or higher A low Tg compound having a transition temperature of 100 ° C. or lower, the content of the low Tg compound in all the non-light emitting materials is 8 to 70% by mass, and at least one of the non-light emitting materials is a pyrimidine skeleton or A composition for forming a light emitting layer, which is a material having a triazine skeleton.
[2] The molecular weight of all the non-light emitting materials whose content is 1.0% by mass or more with respect to the total amount of all the non-light emitting materials contained in the composition for forming a light emitting layer is 5000 or less. [1] The composition for light emitting layer formation as described in any one of.
[3] The composition for forming a light-emitting layer according to [1] or [2], wherein all the light-emitting materials have a molecular weight of 5000 or less.
[4] Any one of [1] to [3], wherein the material having a pyrimidine skeleton or a triazine skeleton contained in the composition for forming a light emitting layer is the high Tg compound and / or the low Tg compound. The composition for light emitting layer formation as described in any one of.
[5] The light-emitting layer formation according to any one of [1] to [4], wherein all the non-light-emitting materials contained in the light-emitting layer forming composition have a weighted average glass transition temperature of 100 ° C. or higher. Composition.
[6] The composition for forming a light-emitting layer according to [1] to [5], wherein the low Tg compound is a compound in which monocyclic compounds are bonded directly and / or via a linking group.
[7] The low Tg compound according to any one of [1] to [6], wherein the low Tg compound is composed only of a compound in which aromatic hydrocarbon monocyclic compounds are bonded directly and / or via a linking group. A composition for forming a light emitting layer.
[8] The composition for forming a light-emitting layer according to any one of [1] to [7], wherein the low Tg compound is a compound represented by the following structural formula (A).
Figure JPOXMLDOC01-appb-C000002
Figure JPOXMLDOC01-appb-C000002
［式（Ａ）において、Ｒ１～Ｒ１５は、それぞれ独立に、水素原子又は炭素数６～３０の、フェニル基若しくは芳香族炭化水素単環化合物が結合した一価の化合物を表す。］
［９］［１］～［８］のいずれか１項に記載の発光層形成用組成物を用いて湿式成膜した発光層を有する有機電界発光素子。 [In Formula (A), R 1 to R 15 each independently represents a monovalent compound in which a hydrogen atom or a phenyl group or aromatic hydrocarbon monocyclic compound having 6 to 30 carbon atoms is bonded. ]
[9] An organic electroluminescence device having a light-emitting layer wet-formed using the composition for forming a light-emitting layer according to any one of [1] to [8].
　本発明によれば、高温保存後において、駆動寿命が長く、かつ発光効率の高い有機電界発光素子を得ることができる。 According to the present invention, an organic electroluminescent element having a long driving life and high luminous efficiency can be obtained after storage at high temperature.
図１は、本発明の有機電界発光素子の実施の形態の一例を示す模式的な断面図である。FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of an organic electroluminescent element of the present invention. 図２は、本発明の有機電界発光素子の実施の形態の別の一例を示す模式的な断面図である。FIG. 2 is a schematic cross-sectional view showing another example of the embodiment of the organic electroluminescent element of the present invention.
　以下に本発明の発光層形成用組成物、有機電界発光素子及びその製造方法の実施態様を詳細に説明するが、以下の説明は、本発明の実施態様の一例（代表例）であり、本発明は、その要旨を超えない限り、これらの内容に特定されない。
［発光層形成用組成物］
　本発明の発光層形成用組成物は、有機電界発光素子の発光層の形成に用いられるものであり、発光材料、非発光材料、及び有機溶媒を含み、非発光材料として、ガラス転移温度（以下、Ｔｇと記載）が１３０℃以上である高Ｔｇ化合物と、Ｔｇが１００℃以下である低Ｔｇ化合物とを含む。 Hereinafter, embodiments of the composition for forming a light emitting layer, an organic electroluminescent element and a method for producing the same according to the present invention will be described in detail. The following description is an example (representative example) of an embodiment of the present invention, and The invention is not specified in these contents unless it exceeds the gist.
[Composition for forming light emitting layer]
The composition for forming a light-emitting layer of the present invention is used for forming a light-emitting layer of an organic electroluminescence device, and includes a light-emitting material, a non-light-emitting material, and an organic solvent. , Tg) includes a high Tg compound having a temperature of 130 ° C. or higher and a low Tg compound having a Tg of 100 ° C. or lower.
（発光材料）
　発光材料としては、通常、有機電界発光素子の発光材料として使用されている任意の公知の材料を適用することができ、特に制限はなく、所望の発光波長で発光し、発光効率が良好である物質を用いればよい。発光材料としては、蛍光発光材料であってもよく、燐光発光材料であってもよいが、内部量子効率及び発熱の少なさの観点から、好ましくは燐光発光材料である。 (Luminescent material)
As the light-emitting material, any known material that is usually used as a light-emitting material of an organic electroluminescent element can be applied, and there is no particular limitation. Light is emitted at a desired light emission wavelength, and the light emission efficiency is good. A substance may be used. The light emitting material may be a fluorescent light emitting material or a phosphorescent light emitting material, but is preferably a phosphorescent light emitting material from the viewpoint of internal quantum efficiency and low heat generation.
　燐光発光材料としては、例えば、長周期型周期表（以下、特に断り書きの無い限り「周期表」という場合には、長周期型周期表を指すものとする。）第７～１１族から選ばれる金属を中心金属として含むウェルナー型錯体又は有機金属錯体等が挙げられる。
　周期表第７～１１族から選ばれる金属として、好ましくは、ルテニウム、ロジウム、パラジウム、銀、レニウム、オスミウム、イリジウム、白金、金等が挙げられる。周期表第７～１１族から選ばれる金属としては、イリジウム及び白金がより好ましい。 As the phosphorescent material, for example, a long-period type periodic table (hereinafter, unless otherwise specified, the term “periodic table” refers to a long-period type periodic table) selected from Group 7 to 11 Wellner type complexes or organometallic complexes containing the above metal as the central metal.
Preferred examples of the metal selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. As the metal selected from Groups 7 to 11 of the periodic table, iridium and platinum are more preferable.
　錯体の配位子としては、アリールピリジン配位子、ヘテロアリールピリジン配位子、アリールピラゾール配位子、ヘテロアリールピラゾール配位子等のアリール基、又はヘテロアリール基に、ピリジン、ピラゾール、又はフェナントロリン等が結合した配位子が好ましく、特にフェニルピリジン配位子、フェニルピラゾール配位子が好ましい。
　燐光発光材料として、具体的には、トリス（２－フェニルピリジン）イリジウム、トリス（２－フェニルピリジン）ルテニウム、トリス（２－フェニルピリジン）パラジウム、ビス（２－フェニルピリジン）白金、トリス（２－フェニルピリジン）オスミウム、トリス（２－フェニルピリジン）レニウム、オクタエチル白金ポルフィリン、オクタフェニル白金ポルフィリン、オクタエチルパラジウムポルフィリン、オクタフェニルパラジウムポルフィリン等が挙げられる。 As a ligand of the complex, an aryl group such as an arylpyridine ligand, a heteroarylpyridine ligand, an arylpyrazole ligand, a heteroarylpyrazole ligand, or a heteroaryl group such as pyridine, pyrazole, or phenanthroline And the like, and a phenylpyridine ligand and a phenylpyrazole ligand are particularly preferable.
Specific examples of phosphorescent materials include tris (2-phenylpyridine) iridium, tris (2-phenylpyridine) ruthenium, tris (2-phenylpyridine) palladium, bis (2-phenylpyridine) platinum, tris (2- Phenylpyridine) osmium, tris (2-phenylpyridine) rhenium, octaethylplatinum porphyrin, octaphenylplatinum porphyrin, octaethyl palladium porphyrin, octaphenyl palladium porphyrin, and the like.
　特に、燐光発光材料の有機金属錯体としては、好ましくは下記式（Ｉ）で表される化合物が挙げられる。
　　ＭＬ（ｑ－ｊ）Ｌ′ｊ　　　　（Ｉ）
（式（Ｉ）中、Ｍは金属を表し、ｑは上記金属の価数を表す。また、Ｌ及びＬ′は二座配位子を表す。ｊは０、１又は２の数を表す。Ｌ又はＬ’は、それぞれが複数存在する場合、複数のＬ又はＬ’はそれぞれ同一であっても異なっていてもよい。）
　式（Ｉ）中、Ｍは任意の金属を表す。好ましいＭの具体例としては、周期表第７～１１族から選ばれる金属として前述した金属等が挙げられる。
　また、式（Ｉ）中、二座配位子Ｌは、以下の部分構造を有する配位子を示す。 In particular, the organometallic complex of the phosphorescent material is preferably a compound represented by the following formula (I).
ML (q−j) L ′ j (I)
(In formula (I), M represents a metal, q represents a valence of the metal, L and L ′ represent a bidentate ligand, and j represents a number of 0, 1 or 2. When a plurality of L or L ′ are present, the plurality of L or L ′ may be the same or different.
In formula (I), M represents any metal. Specific examples of preferable M include the metals described above as the metal selected from Groups 7 to 11 of the periodic table.
In formula (I), bidentate ligand L represents a ligand having the following partial structure.
Figure JPOXMLDOC01-appb-C000003
Figure JPOXMLDOC01-appb-C000003
　上記Ｌの部分構造において、環Ａ１は、置換基を有していてもよい、芳香環基を表す。本発明における芳香環基は、芳香族炭化水素基でも良いし、芳香族複素環基でも良い。
　また、上記Ｌの部分構造において、環Ａ２は、置換基を有していてもよい、含窒素芳香族複素環基を表す。
　また、式（Ｉ）中、二座配位子Ｌ′としては、以下示す配位子を挙げることができる。 In the partial structure of L, ring A1 represents an aromatic ring group which may have a substituent. The aromatic ring group in the present invention may be an aromatic hydrocarbon group or an aromatic heterocyclic group.
In the partial structure of L, ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.
In the formula (I), examples of the bidentate ligand L ′ include the ligands shown below.
Figure JPOXMLDOC01-appb-C000004
Figure JPOXMLDOC01-appb-C000004
　本発明における燐光発光材料の有機金属錯体として、発光層中で共存する非発光材料と相互作用しやすいという観点から、分子が比較的立体的で嵩高い、二座配位子を有する上記式（Ｉ）で表される化合物が好ましい。
　また、例えば、青色は蛍光発光材料、緑色及び赤色は燐光発光材料を用いる等、蛍光発光材料と燐光発光材料を組み合わせて用いてもよい。 As the organometallic complex of the phosphorescent material in the present invention, from the viewpoint of easily interacting with the non-light emitting material coexisting in the light emitting layer, the above formula having a bidentate ligand having a relatively three-dimensional and bulky molecule ( The compounds represented by I) are preferred.
Further, for example, a fluorescent material and a phosphorescent material may be used in combination such that a fluorescent material is used for blue and a phosphorescent material is used for green and red.
　なお、湿式成膜法により発光層を形成する際に用いられる発光層形成用組成物の調製に用いる溶剤への溶解性を向上させる目的で、発光材料の分子の対称性や剛性を低下させたり、或いはアルキル基等の親油性置換基を導入したりすることが好ましい。
　発光材料は、いずれか１種のみを用いてもよく、２種以上を任意の組み合わせ及び比率で併用してもよい。 In addition, for the purpose of improving the solubility in a solvent used for preparing a composition for forming a light emitting layer used when forming a light emitting layer by a wet film formation method, the symmetry and rigidity of the molecules of the light emitting material are reduced. Alternatively, it is preferable to introduce a lipophilic substituent such as an alkyl group.
Only one of the luminescent materials may be used, or two or more of the luminescent materials may be used in any combination and ratio.
　本発明における発光材料の分子量は、好ましくは５０００以下、更に好ましくは４０００以下、特に好ましくは３０００以下である。また、本発明における発光材料の分子量は、通常４００以上、好ましくは６００以上、更に好ましくは８００以上、特に好ましくは１０００以上である。この分子量範囲であることによって、発光材料どうしが凝集せず非発光材料と均一に混合し、発光効率の高い発光層を得ることができると考えられる。 The molecular weight of the luminescent material in the present invention is preferably 5000 or less, more preferably 4000 or less, and particularly preferably 3000 or less. Further, the molecular weight of the light emitting material in the present invention is usually 400 or more, preferably 600 or more, more preferably 800 or more, and particularly preferably 1000 or more. With this molecular weight range, it is considered that the light-emitting materials can be uniformly mixed with the non-light-emitting material without aggregating the light-emitting materials, and a light-emitting layer with high light emission efficiency can be obtained.
　発光材料の分子量は、Ｔｇや融点、分解温度等が高く、発光材料及び形成された発光層の耐熱性に優れる点、及び、ガス発生、再結晶化及び分子のマイグレーション等に起因する膜質の低下や材料の熱分解に伴う不純物濃度の上昇等が起こり難い点では大きいことが好ましい。一方、発光材料の分子量は、有機化合物の精製が容易で、溶剤に溶解させやすい点では小さいことが好ましい。 The molecular weight of the luminescent material is high in Tg, melting point, decomposition temperature, etc., excellent in heat resistance of the luminescent material and the formed luminescent layer, and film quality deterioration due to gas generation, recrystallization, molecular migration, etc. In view of the fact that the increase in the impurity concentration accompanying the thermal decomposition of the material or the like hardly occurs, it is preferable. On the other hand, the molecular weight of the light-emitting material is preferably small in that the organic compound can be easily purified and easily dissolved in a solvent.
（非発光材料）
　本発明における非発光材料とは、発光材料以外のすべての不揮発性材料を指すものとする。不揮発性材料とは、発光層形成用組成物における有機溶媒以外の材料であって、発光層を形成した際に発光層に含まれる材料のことを言う。非発光材料としては、後述の高Ｔｇ化合物と低Ｔｇ化合物とを少なくとも含むが、これら以外の材料を含んでもよい。 (Non-luminescent material)
The non-light emitting material in the present invention refers to all nonvolatile materials other than the light emitting material. The non-volatile material is a material other than the organic solvent in the composition for forming a light emitting layer, and means a material included in the light emitting layer when the light emitting layer is formed. The non-light emitting material includes at least a high Tg compound and a low Tg compound, which will be described later, but may include materials other than these.
　本発明においては、有機電界発光素子の電荷に対する耐久性の観点から、非発光材料の内、少なくとも一つはピリミジン骨格又はトリアジン骨格を有する材料であり、後述の高Ｔｇ化合物あるいは低Ｔｇ化合物の少なくとも一方が、ピリミジン骨格又はトリアジン骨格を有する材料であるであることが好ましい。さらに、非発光材料のいずれかがトリアジン骨格を有する材料であることがさらに好ましく、後述の高Ｔｇ化合物あるいは低Ｔｇ化合物の少なくとも一方がトリアジン骨格を有する材料であるであることが特に好ましく、後述の低Ｔｇ化合物がトリアジン骨格を有する材料であることが最も好ましい。 In the present invention, from the viewpoint of durability against charges of the organic electroluminescent device, at least one of the non-light emitting materials is a material having a pyrimidine skeleton or a triazine skeleton, and at least one of the high Tg compound and the low Tg compound described later. One of the materials is preferably a material having a pyrimidine skeleton or a triazine skeleton. Furthermore, it is more preferable that any of the non-light-emitting materials is a material having a triazine skeleton, and it is particularly preferable that at least one of a high Tg compound or a low Tg compound described later is a material having a triazine skeleton. Most preferably, the low Tg compound is a material having a triazine skeleton.
　本発明の発光層形成用組成物においては、発光層形成用組成物に含まれる全ての非発光材料の総量に対する含有率が１．０質量％以上である全ての各非発光材料の分子量は、５０００以下が好ましく、さらに好ましくは４０００以下であり、特に好ましくは３０００以下であり、最も好ましくは２０００以下であり、通常３００以上、好ましくは３５０以上、より好ましくは４００以上である。 In the composition for forming a light-emitting layer of the present invention, the molecular weight of all the non-light-emitting materials having a content ratio of 1.0% by mass or more with respect to the total amount of all the non-light-emitting materials contained in the composition for forming a light-emitting layer, It is preferably 5000 or less, more preferably 4000 or less, particularly preferably 3000 or less, most preferably 2000 or less, usually 300 or more, preferably 350 or more, and more preferably 400 or more.
＜高Ｔｇ化合物＞
　本発明の高Ｔｇ化合物は、Ｔｇが１３０℃以上を示す化合物である。高Ｔｇ化合物としては、通常、有機電界発光素子の発光層の形成に用いられる化合物から、Ｔｇが１３０℃以上のものを適宜選択すればよいが、高Ｔｇ化合物としては、発光層に通常含有される電荷輸送材料であることが好ましい。 <High Tg compound>
The high Tg compound of the present invention is a compound having a Tg of 130 ° C. or higher. As the high Tg compound, a compound having a Tg of 130 ° C. or higher may be appropriately selected from the compounds usually used for forming the light emitting layer of the organic electroluminescent device. However, the high Tg compound is usually contained in the light emitting layer. It is preferable that the charge transport material be
　Ｔｇが１３０℃以上である化合物としては、電荷輸送性に優れる中心骨格に対して、３環以上の縮合環構造を結合する化合物であることが好ましい。特に、３環以上の縮合環構造を２以上有する化合物及び/又は５環以上の縮合環を少なくとも１つ有する化合物であることが好ましい。これらの化合物であることで、分子の剛直性が増し、熱に応答する分子運動の程度を抑制する効果が得られ易くなる。
また、高Ｔｇ化合物が有する３環以上の縮合環及び５環以上の縮合環は、芳香族炭化水素環又は芳香族複素環を有することが電荷輸送性及び材料の耐久性の点で好ましい。 The compound having a Tg of 130 ° C. or higher is preferably a compound that bonds a condensed ring structure of three or more rings to a central skeleton excellent in charge transportability. In particular, a compound having two or more condensed ring structures having three or more rings and / or a compound having at least one condensed ring having five or more rings is preferable. By being these compounds, the rigidity of the molecule is increased, and the effect of suppressing the degree of molecular motion in response to heat is easily obtained.
Moreover, it is preferable from the point of charge transport property and durability of a material that 3 or more condensed rings and 5 or more condensed rings which a high Tg compound has have an aromatic hydrocarbon ring or an aromatic heterocyclic ring.
　電荷輸送性に優れる中心骨格としては、具体的には、芳香族構造、芳香族アミン構造、トリアリールアミン構造、ジベンゾフラン構造、ナフタレン構造、フェナントレン構造、フタロシアニン構造、ポルフィリン構造、チオフェン構造、ベンジルフェニル構造、フルオレン構造、キナクリドン構造、トリフェニレン構造、カルバゾール構造、ピレン構造、アントラセン構造、フェナントロリン構造、キノリン構造、ピリジン構造、ピリミジン構造、トリアジン構造、オキサジアゾール構造又はイミダゾール構造等が挙げられる。 Specific examples of the central skeleton with excellent charge transportability include aromatic structures, aromatic amine structures, triarylamine structures, dibenzofuran structures, naphthalene structures, phenanthrene structures, phthalocyanine structures, porphyrin structures, thiophene structures, and benzylphenyl structures. Fluorene structure, quinacridone structure, triphenylene structure, carbazole structure, pyrene structure, anthracene structure, phenanthroline structure, quinoline structure, pyridine structure, pyrimidine structure, triazine structure, oxadiazole structure or imidazole structure.
　中でも、電子輸送性に優れ構造が比較的安定な材料である観点から、ピリジン構造、ピリミジン構造、トリアジン構造を有する化合物がより好ましく、ピリミジン構造、トリアジン構造を有する化合物であることがさらに好ましい。
　本発明における高Ｔｇ化合物は、発光材料自身が電子を輸送することによる発光材料の劣化を抑え駆動寿命をより長くできるという点で、電子輸送性に優れた構造を有する材料であることが好ましい。 Of these, compounds having a pyridine structure, a pyrimidine structure, and a triazine structure are more preferable, and compounds having a pyrimidine structure and a triazine structure are more preferable, from the viewpoint of being a material that has excellent electron transport properties and a relatively stable structure.
The high Tg compound in the present invention is preferably a material having a structure excellent in electron transporting property in that the light emitting material itself can suppress deterioration of the light emitting material due to transport of electrons and extend the driving life.
　また、正孔輸送性に優れた構造を有する化合物も好ましく、前記電荷輸送性に優れた中心骨格の中でも、カルバゾール構造、ジベンゾフラン構造、トリアリールアミン構造、ナフタレン構造、フェナントレン構造又はピレン構造が正孔輸送性に優れた構造として好ましく、カルバゾール構造、ジベンゾフラン構造又はトリアリールアミン構造がさらに好ましい。 Further, a compound having a structure excellent in hole transportability is also preferable, and among the central skeleton excellent in charge transportability, a carbazole structure, dibenzofuran structure, triarylamine structure, naphthalene structure, phenanthrene structure or pyrene structure is a hole. A structure excellent in transportability is preferable, and a carbazole structure, a dibenzofuran structure, or a triarylamine structure is more preferable.
　本発明における高Ｔｇ化合物は、発光材料自身が正孔を輸送することによる発光材料の劣化を抑え駆動寿命をより長くできるという点で、正孔輸送性に優れた構造を有する材料であることが好ましい。
　本発明の高Ｔｇ化合物は、前述の通り、３環以上の縮合環構造を有することが好ましく、３環以上の縮合環構造を２以上有する化合物及び/又は５環以上の縮合環を少なくとも１つ有する化合物であることがさらに好ましい。
３環以上の縮合環構造としては、具体的には、アントラセン構造、フェナントレン構造、ピレン構造、クリセン構造、ナフタセン構造、トリフェニレン構造、フルオレン構造、ベンゾフルオレン構造、インデノフルオレン構造、インドロフルオレン構造、カルバゾール構造、インデノカルバゾール構造、インドロカルバゾール構造、ジベンゾフラン構造、ジベンゾチオフェン構造等が挙げられる。電荷輸送性ならびに溶解性の観点から、フェナントレン構造、フルオレン構造、インデノフルオレン構造、カルバゾール構造、インデノカルバゾール構造、インドロカルバゾール構造、ジベンゾフラン構造及びジベンゾチオフェン構造からなる群より選択される少なくとも１つが好ましく、電荷に対する耐久性の観点からカルバゾール構造又はインドロカルバゾール構造がさらに好ましい。 The high Tg compound in the present invention is a material having a structure excellent in hole transportability in that the light emitting material itself can suppress the deterioration of the light emitting material due to transporting holes and can extend the driving life. preferable.
As described above, the high Tg compound of the present invention preferably has a condensed ring structure of 3 or more rings, and / or at least one compound having 2 or more condensed ring structures of 3 or more rings and / or 5 or more condensed rings. More preferably, it is a compound which has.
Specific examples of the condensed ring structure having three or more rings include anthracene structure, phenanthrene structure, pyrene structure, chrysene structure, naphthacene structure, triphenylene structure, fluorene structure, benzofluorene structure, indenofluorene structure, indolofluorene structure, Examples thereof include a carbazole structure, an indenocarbazole structure, an indolocarbazole structure, a dibenzofuran structure, and a dibenzothiophene structure. From the viewpoint of charge transportability and solubility, at least one selected from the group consisting of phenanthrene structure, fluorene structure, indenofluorene structure, carbazole structure, indenocarbazole structure, indolocarbazole structure, dibenzofuran structure and dibenzothiophene structure A carbazole structure or an indolocarbazole structure is more preferable from the viewpoint of durability against electric charges.
　本発明における高Ｔｇ化合物の分子量は、通常５０００以下、好ましくは４０００以下、更に好ましくは３０００以下、最も好ましくは２０００以下である。また、本発明における高Ｔｇ化合物の分子量は、通常３００以上、好ましくは３５０以上、更に好ましくは４００以上である。
　高Ｔｇ化合物の分子量は、ガス発生や再結晶化及び分子のマイグレーション等に起因する膜質の低下が起こり難い点では大きいことが好ましい。一方、高Ｔｇ化合物の分子量は、有機化合物の精製が容易で、溶剤に溶解させやすい点では小さいことが好ましい。 The molecular weight of the high Tg compound in the present invention is usually 5000 or less, preferably 4000 or less, more preferably 3000 or less, and most preferably 2000 or less. Further, the molecular weight of the high Tg compound in the present invention is usually 300 or more, preferably 350 or more, and more preferably 400 or more.
The molecular weight of the high Tg compound is preferably large from the viewpoint that film quality deterioration due to gas generation, recrystallization, molecular migration or the like hardly occurs. On the other hand, the molecular weight of the high Tg compound is preferably small in view of easy purification of the organic compound and easy dissolution in a solvent.
　本発明における高Ｔｇ化合物のＴｇは、１３０℃以上であれば本発明の効果を著しく損なわない限り任意である。本発明における高Ｔｇ化合物のＴｇは、高温保存時の膜が安定であることから、好ましくは１３５℃以上、更に好ましくは１４０℃以上である。また、本発明における高Ｔｇ化合物のＴｇは、有機溶剤に対する溶解性が高いことから、通常２５０℃以下、好ましくは２００℃以下、より好ましくは１８０℃以下、更に好ましくは１６０℃以下である。 The Tg of the high Tg compound in the present invention is arbitrary as long as the effect of the present invention is not significantly impaired as long as it is 130 ° C. or higher. The Tg of the high Tg compound in the present invention is preferably 135 ° C. or higher, more preferably 140 ° C. or higher, since the film during high temperature storage is stable. The Tg of the high Tg compound in the present invention is usually 250 ° C. or lower, preferably 200 ° C. or lower, more preferably 180 ° C. or lower, and still more preferably 160 ° C. or lower because of its high solubility in organic solvents.
　例えば、有機電界発光素子を車載用ディスプレイに用いる場合等においては、夏の炎天下で車を停めていると車内温度は８０℃を超えることがあるため、車載用ディスプレイは１００℃を超える高温保存試験での信頼性が要求される。そのため、有機電界発光素子の一般的な高温保存試験は通常１００℃以上で行われ、高くても１２０℃程度であるこ。また、Ｔｇ付近での膜物性やモルフォロジーの変化は、実際にはＴｇの前後で徐々に起こる。以上のことから、本発明における高Ｔｇ化合物のＴｇは、保存試験よりも十分高い温度である１３０℃以上である。また、長期間の高温保存試験における膜物性やモルフォロジーの変化をより抑えられるという観点からは、より高いＴｇが更に好ましい。一方で、高Ｔｇ化合物のＴｇは、溶剤への溶解性及び膜中での結晶化の抑制による素子安定性という観点からは、低いことが好ましい。
　本発明の発光層形成用組成物には、高Ｔｇ化合物が少なくとも１種類含まれていればよいが、複数含まれていてもよい。 For example, when an organic electroluminescent device is used for a vehicle-mounted display, the temperature inside the vehicle may exceed 80 ° C. when the vehicle is parked under the hot summer sun. Reliability is required. Therefore, a general high-temperature storage test of an organic electroluminescent element is usually performed at 100 ° C. or higher, and at most about 120 ° C. In addition, changes in film properties and morphology near Tg actually occur gradually before and after Tg. From the above, the Tg of the high Tg compound in the present invention is 130 ° C. or higher, which is a sufficiently higher temperature than the storage test. Moreover, higher Tg is still more preferable from a viewpoint that the change of the film | membrane physical property and morphology in a long-term high temperature storage test can be suppressed more. On the other hand, the Tg of the high Tg compound is preferably low from the viewpoint of solubility in a solvent and device stability due to suppression of crystallization in the film.
The composition for forming a light emitting layer of the present invention may contain at least one high Tg compound, but may contain a plurality of high Tg compounds.
＜低Ｔｇ化合物＞
　本発明の低Ｔｇ化合物は、Ｔｇが１００℃以下を示す化合物である。低Ｔｇ化合物としては、単環化合物同士が、直接結合及び／又は連結基を介して結合した化合物であることが好ましい。該化合物は、置換基を有していてもよく、該置換基は特に限定されないが、アルキル基又はアラルキル基が溶解性及びインクの保管安定性に優れる点で好ましい。
　連結基としては通常、有機電界発光素子用材料として用いられる原子、置換基であれば特に限定しないが、具体的には、二価の連結基として、酸素原子、硫黄原子、アルキレン基、スルホ基、カルボニル基；三価の連結基として窒素原子；四価の連結基としてケイ素原子が好ましい。ここで、連結基は、全ての結合手に単環化合物が結合することを意味する。また、これらの連結基は、単環化合物同士を連結してもよく、また、単環化合物同士が直接結合を介して結合した化合物を連結してもよい。さらに、このとき連結する単環化合物、若しくは単環化合物同士が直接結合を介して結合した化合物は、同じ構造であっても異なる構造であってもよい。例えば、窒素原子が連結基で、単環化合物同士が直接結合を介して結合した化合物がアリ―ル基の場合はトリアリールアミンの事を指し、トリアリールアミンの３つの置換基が同じであっても異なっていてもよい。連結基としては、隣接する環のねじれがより大きくなり、分子の平面性が低く分子パッキングによる結晶化を引き起こしにくいという点から、窒素原子又はアルキレン基がより好ましい。また、電荷に対する耐久性の観点から、直接結合のみからなる化合物がさらに好ましい。 <Low Tg compound>
The low Tg compound of the present invention is a compound having a Tg of 100 ° C. or lower. The low Tg compound is preferably a compound in which monocyclic compounds are bonded via a direct bond and / or a linking group. The compound may have a substituent, and the substituent is not particularly limited, but an alkyl group or an aralkyl group is preferable from the viewpoint of excellent solubility and ink storage stability.
The linking group is not particularly limited as long as it is an atom or a substituent that is usually used as a material for an organic electroluminescent device. Specifically, as a divalent linking group, an oxygen atom, a sulfur atom, an alkylene group, a sulfo group A carbonyl group; a nitrogen atom as a trivalent linking group; and a silicon atom as a tetravalent linking group. Here, the linking group means that the monocyclic compound is bonded to all bonds. These linking groups may link monocyclic compounds to each other, or may link compounds in which monocyclic compounds are bonded via a direct bond. Further, the monocyclic compounds to be linked at this time, or the compounds in which the monocyclic compounds are bonded via a direct bond may have the same structure or different structures. For example, when a nitrogen atom is a linking group and a compound in which monocyclic compounds are bonded via a direct bond is an aryl group, it means a triarylamine, and the three substituents of the triarylamine are the same. Or different. The linking group is more preferably a nitrogen atom or an alkylene group from the viewpoint that the twist of the adjacent ring is larger, the planarity of the molecule is low, and crystallization due to molecular packing is difficult to cause. Further, from the viewpoint of durability against electric charges, a compound consisting of only a direct bond is more preferable.
　低Ｔｇ化合物としては、通常、有機電界発光素子の発光層の形成に用いられる化合物から、上記条件を満たすものを適宜選択すればよいが、低Ｔｇ材料としては、具体的には、単環化合物同士が、直接結合及び／又は連結基を介して結合した化合物であって、芳香族構造、芳香族アミン構造、チオフェン構造、ベンジルフェニル構造、ピリジン構造、ピリミジン構造、トリアジン構造、オキサジアゾール構造及びイミダゾール構造からなる群から選択される少なくとも1つの構造を有する化合物が好ましい。芳香族炭化水素単環化合物同士が、直接結合及び／又は連結基を介して結合した化合物であって、芳香族構造、芳香族アミン構造又はベンジルフェニル構造を有する化合物が、より電荷輸送性に優れることからさらに好ましい。 As the low Tg compound, a compound satisfying the above conditions may be appropriately selected from the compounds usually used for forming the light emitting layer of the organic electroluminescence device. Specifically, as the low Tg material, a monocyclic compound may be used. A compound in which each other is bonded through a direct bond and / or a linking group, and includes an aromatic structure, an aromatic amine structure, a thiophene structure, a benzylphenyl structure, a pyridine structure, a pyrimidine structure, a triazine structure, an oxadiazole structure, and A compound having at least one structure selected from the group consisting of imidazole structures is preferred. Aromatic hydrocarbon monocyclic compounds are bonded to each other through a direct bond and / or a linking group, and a compound having an aromatic structure, an aromatic amine structure or a benzylphenyl structure is more excellent in charge transporting properties. It is further preferable.
　低Ｔｇ化合物としては、分子としての平面性が低く、分子パッキングによる結晶化を引き起こしにくいという点で、単環化合物同士が、直接結合及び／又は連結基を介して結合した化合物が好ましい。一方、水素結合の影響が少なく結合の回転が置きやすく、より分子の平面性を低くできるという点では、芳香族炭化水素単環化合物同士が直接結合及び／又は連結基を介して結合した化合物がより好ましい。さらには、本発明の発光層形成用組成物に含まれる低Ｔｇ化合物が、芳香族炭化水素単環化合物同士が直接結合した化合物のみからなることが、電荷に対する耐久性が優れる点で好ましい。
　特に、芳香族炭化水素単環化合物同士が直接結合した低Ｔｇ化合物として、下記式（Ａ）で表される化合物が好ましい。 As the low Tg compound, a compound in which monocyclic compounds are bonded via a direct bond and / or a linking group is preferable in that the planarity as a molecule is low and crystallization due to molecular packing is unlikely to occur. On the other hand, a compound in which aromatic hydrocarbon monocyclic compounds are bonded via a direct bond and / or a linking group is advantageous in that the influence of hydrogen bond is small and the rotation of the bond is easy to be placed and the planarity of the molecule can be further lowered. More preferred. Furthermore, it is preferable that the low Tg compound contained in the composition for forming a light emitting layer of the present invention comprises only a compound in which aromatic hydrocarbon monocyclic compounds are directly bonded to each other in terms of excellent durability against electric charges.
In particular, a compound represented by the following formula (A) is preferable as a low Tg compound in which aromatic hydrocarbon monocyclic compounds are directly bonded to each other.
Figure JPOXMLDOC01-appb-C000005
Figure JPOXMLDOC01-appb-C000005
　式（Ａ）において、Ｒ１～Ｒ１５は、それぞれ独立に、水素原子又は炭素数６～３０の、フェニル基若しくは芳香族炭化水素単環化合物が結合した一価の化合物を表す。
　式 (Ａ)の構造を有する低Ｔｇ化合物は、電荷に対する耐久性が高く、熱等による分子運動と安定性を両立しやすい構造である。また、式 (Ａ)の構造は、芳香族炭化水素の単環のみが結合した化合物であるため、高Ｔｇ化合物同士の隙間を埋めやすく好ましい。また、式 (Ａ)の構造は、高Ｔｇ化合物が３環以上の縮合環構造又は５環以上の縮合環構造を有する場合、該縮合環によって生じる高Ｔｇ化合物同士の隙間を埋めやすいため好ましい。
　また、式 (Ａ)の構造は、該縮合環が芳香族炭化水素環又は芳香族複素環を含む場合、芳香族炭化水素化合物である式（Ａ）との親和性が高くなり、高Ｔｇ化合物同士の隙間を埋めた状態がより安定すると考えられ、好ましい。 In the formula (A), R 1 to R 15 each independently represents a monovalent compound in which a hydrogen atom or a phenyl group or an aromatic hydrocarbon monocyclic compound having 6 to 30 carbon atoms is bonded.
The low Tg compound having the structure of the formula (A) has a high durability against electric charges, and is a structure that can easily achieve both molecular motion and stability due to heat and the like. Moreover, since the structure of Formula (A) is a compound in which only a single ring of an aromatic hydrocarbon is bonded, it is preferable to easily fill a gap between high Tg compounds. The structure of the formula (A) is preferable when the high Tg compound has a condensed ring structure having 3 or more rings or a condensed ring structure having 5 or more rings, because the gap between the high Tg compounds generated by the condensed ring is easily filled.
Further, the structure of the formula (A) has a high affinity with the formula (A) which is an aromatic hydrocarbon compound when the condensed ring contains an aromatic hydrocarbon ring or an aromatic heterocycle, and a high Tg compound. The state in which the gaps between them are filled is considered to be more stable, which is preferable.
　また、本発明における好ましい低Ｔｇ化合物は、単環化合物同士が、直接結合及び／又は連結基を介して結合した化合物である。これらの中でも電子輸送性に優れ構造が比較的安定な材料である、ピリジン系化合物、ピリミジン系化合物、トリアジン系化合物等であることが好ましい。これらの化合物であることで、発光材料自身が電子を輸送することによる発光材料の劣化を抑え駆動寿命をより長くすることが可能になる。 In addition, a preferable low Tg compound in the present invention is a compound in which monocyclic compounds are bonded through a direct bond and / or a linking group. Among these, pyridine-based compounds, pyrimidine-based compounds, triazine-based compounds and the like, which are materials having excellent electron transport properties and relatively stable structures, are preferable. By using these compounds, the light emitting material itself can suppress deterioration of the light emitting material due to transport of electrons, thereby extending the driving life.
　本発明における低Ｔｇ化合物は、発光材料自身が電子を輸送することによる発光材料の劣化を抑え駆動寿命をより長くできるという点で、電子輸送性に優れ構造が比較的安定な材料であることが好ましい。
　一方、本発明における低Ｔｇ化合物は、発光材料自身が正孔を輸送することによる発光材料の劣化を抑え駆動寿命をより長くできるという点で、正孔輸送性に優れた構造を有する材料であることが好ましい。 The low Tg compound in the present invention is a material having an excellent electron transporting property and a relatively stable structure in that the light emitting material itself can suppress deterioration of the light emitting material due to transport of electrons and can extend the driving life. preferable.
On the other hand, the low Tg compound in the present invention is a material having a structure excellent in hole transportability in that the light emitting material itself can suppress the deterioration of the light emitting material due to transporting holes and can extend the driving life. It is preferable.
　正孔輸送性に優れた構造としては、ジシクロアルキルアリールアミン構造、シクロアルキルジアリールアミン構造、トリアリールアミン構造が好ましい。これらの中でも、耐久性の観点から、トリアリールアミン構造がさらに好ましい。 As the structure excellent in hole transportability, a dicycloalkylarylamine structure, a cycloalkyldiarylamine structure, and a triarylamine structure are preferable. Among these, a triarylamine structure is more preferable from the viewpoint of durability.
　本発明における低Ｔｇ化合物の分子量は、通常５０００以下、好ましくは４０００以下、更に好ましくは３０００以下、最も好ましくは２０００以下である。また、本発明における低Ｔｇ化合物の分子量は、通常３００以上、好ましくは３５０以上、より好ましくは４００以上である。
　低Ｔｇ化合物の分子量は、ガス発生や再結晶化及び分子のマイグレーション等に起因する膜質の低下が起こり難い点では大きいことが好ましい。一方、低Ｔｇ化合物の分子量は、有機化合物の精製が容易で、溶剤に溶解させやすい点では小さいことが好ましい。 The molecular weight of the low Tg compound in the present invention is usually 5000 or less, preferably 4000 or less, more preferably 3000 or less, and most preferably 2000 or less. Further, the molecular weight of the low Tg compound in the present invention is usually 300 or more, preferably 350 or more, more preferably 400 or more.
The molecular weight of the low Tg compound is preferably large in that it is difficult for the film quality to deteriorate due to gas generation, recrystallization, molecular migration, or the like. On the other hand, the molecular weight of the low Tg compound is preferably small in that the organic compound can be easily purified and easily dissolved in a solvent.
　本発明における低Ｔｇ化合物のＴｇは、１００℃以下であれば本発明の効果を著しく損なわない限り任意である。本発明における低Ｔｇ化合物のＴｇは、好ましくは９５℃以下、より好ましくは９０℃以下である。また、本発明における低Ｔｇ化合物のＴｇは、通常６０℃以上、好ましくは７０℃以上、より好ましくは８０℃以上、更に好ましくは８５℃以上である。 The Tg of the low Tg compound in the present invention is arbitrary as long as the effect of the present invention is not significantly impaired as long as it is 100 ° C. or lower. The Tg of the low Tg compound in the present invention is preferably 95 ° C. or lower, more preferably 90 ° C. or lower. The Tg of the low Tg compound in the present invention is usually 60 ° C. or higher, preferably 70 ° C. or higher, more preferably 80 ° C. or higher, and still more preferably 85 ° C. or higher.
　本発明における低Ｔｇ化合物のＴｇは、溶剤への溶解性及び膜中での結晶化の抑制による素子安定性という観点からは、低いことが好ましい。一方で、低Ｔｇ化合物のＴｇは、不揮発性の確保や素子作製プロセス及び素子の保存における熱安定性の観点からは、高いことが好ましい。
　本発明の発光層形成用組成物には、低Ｔｇ化合物が少なくとも１種類含まれていればよいが、複数含まれていてもよい。 The Tg of the low Tg compound in the present invention is preferably low from the viewpoint of solubility in a solvent and device stability due to suppression of crystallization in the film. On the other hand, the Tg of the low Tg compound is preferably high from the viewpoint of ensuring non-volatility, thermal stability in element fabrication process and element storage.
The composition for forming a light emitting layer of the present invention may contain at least one kind of low Tg compound, but may contain a plurality of low Tg compounds.
　（有機溶媒）
　本発明の発光層形成用組成物は、インクジェット法等の湿式成膜法を用いて発光層として形成することが好ましい。本発明で用いられる有機溶媒としては、発光材料及び非発光材料等の発光層材料が良好に溶解又は分散するものであれば特に限定されない。
　有機溶媒の溶解性としては、２５℃、１気圧下で、発光材料及び非発光材料等を、各々、通常０．０１質量％以上、好ましくは０．０５質量％以上、さらに好ましくは０．１質量％以上溶解することが好ましい。以下に有機溶媒の具体例を挙げるが、本発明の効果を損なわない限り、有機溶媒はこれらに限定されるものではない。 (Organic solvent)
The composition for forming a light emitting layer of the present invention is preferably formed as a light emitting layer by using a wet film forming method such as an ink jet method. The organic solvent used in the present invention is not particularly limited as long as the light emitting layer material such as the light emitting material and the non-light emitting material can be dissolved or dispersed well.
The solubility of the organic solvent is usually 0.01% by mass or more, preferably 0.05% by mass or more, and more preferably 0.1% by mass of the luminescent material and the non-luminescent material, respectively, at 25 ° C. and 1 atm. It is preferable to dissolve by mass% or more. Although the specific example of an organic solvent is given to the following, unless the effect of this invention is impaired, an organic solvent is not limited to these.
　有機溶媒としては、例えば、ｎ－デカン、シクロヘキサン、エチルシクロヘキサン、デカリン、ビシクロヘキサン等のアルカン類；トルエン、キシレン、メチシレン、シクロヘキシルベンゼン、テトラメチルシクロヘキサノン、テトラリン等の芳香族炭化水素類；クロロベンゼン、ジクロロベンゼン、トリクロロベンゼン等のハロゲン化芳香族炭化水素類；１，２－ジメトキシベンゼン、１，３－ジメトキシベンゼン、アニソール、フェネトール、２－メトキシトルエン、３－メトキシトルエン、４－メトキシトルエン、２，３－ジメチルアニソール、２，４－ジメチルアニソール、ジフェニルエーテル等の芳香族エーテル類；酢酸フェニル、プロピオン酸フェニル、安息香酸メチル、安息香酸エチル、安息香酸エチル、安息香酸プロピル、安息香酸ｎ－ブチル等の芳香族エステル類；シクロヘキサノン、シクロオクタノン、フェンコン等の脂環族ケトン類；シクロヘキサノール、シクロオクタノール等の脂環族アルコール類；メチルエチルケトン、ジブチルケトン等の脂肪族ケトン類；ブタノール、ヘキサノール等の脂肪族アルコール類；エチレングリコールジメチルエーテル、エチレングリコールジエチルエーテル、プロピレングリコール－１－モノメチルエーテルアセタート（ＰＧＭＥＡ）等の脂肪族エーテル類；等が挙げられる。 Examples of the organic solvent include alkanes such as n-decane, cyclohexane, ethylcyclohexane, decalin, and bicyclohexane; aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene, tetramethylcyclohexanone, and tetralin; Halogenated aromatic hydrocarbons such as chlorobenzene and trichlorobenzene; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3 -Aromatic ethers such as dimethylanisole, 2,4-dimethylanisole, diphenyl ether; phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, ethyl benzoate, propyl benzoate Aromatic esters such as n-butyl benzoate; Alicyclic ketones such as cyclohexanone, cyclooctanone, and Fencon; Alicyclic alcohols such as cyclohexanol and cyclooctanol; Aliphatic ketones such as methyl ethyl ketone and dibutyl ketone Aliphatic alcohols such as butanol and hexanol; aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA);
　上記の中でも、好ましくは、アルカン類及び/又は芳香族炭化水素類、より好ましくはトルエン、キシレン及びシクロヘキシルベンゼンからなる群より選択される少なくとも１つである。これらであることで、非極性で水分の影響を受けにくく、また材料が溶解しやすくインクを安定に保存しやすい。
　これらの有機溶媒は、１種類を単独で用いてもよく、また、２種類以上を任意の組み合わせ及び比率で用いてもよい。
　また、より均一な膜を得るためには、成膜直後の液膜から有機溶媒が適当な速度で蒸発することが好ましい。このため、有機溶媒の沸点は、通常８０℃以上、好ましくは１００℃以上、より好ましくは１２０℃以上である。また、有機溶媒の沸点は、通常２７０℃以下、好ましくは２５０℃以下、より好ましくは沸点２３０℃以下である。 Among the above, preferably, it is at least one selected from the group consisting of alkanes and / or aromatic hydrocarbons, more preferably toluene, xylene and cyclohexylbenzene. By being these, it is non-polar and hardly affected by moisture, and the material is easily dissolved, so that the ink can be stored stably.
One of these organic solvents may be used alone, or two or more thereof may be used in any combination and ratio.
In order to obtain a more uniform film, it is preferable that the organic solvent evaporates from the liquid film immediately after the film formation at an appropriate rate. For this reason, the boiling point of the organic solvent is usually 80 ° C. or higher, preferably 100 ° C. or higher, more preferably 120 ° C. or higher. The boiling point of the organic solvent is usually 270 ° C. or lower, preferably 250 ° C. or lower, more preferably 230 ° C. or lower.
　（発光層形成用組成物の組成比について）
　本発明の発光層形成用組成物は、非発光材料として、前述の通り、少なくとも上記高Ｔｇ化合物と低Ｔｇ化合物を含有していれば、その他の成分を適宜含有していてもよい。ただし、発光層形成用組成物に含まれる全ての非発光材料に対する低Ｔｇ化合物の含有率（以下、単に低Ｔｇ化合物の含有率と記載）が８～７０質量％であることが必要であり、１０～７０質量％であることがより好ましい。低Ｔｇ化合物の含有率は、８質量％以上であり、１０質量％以上が好ましく、１５質量％以上がより好ましい。また、低Ｔｇ化合物の含有率は、８０質量％以下であり、７０質量％以下が好ましく、５０質量％以下がより好ましく、４０質量％以下が更に好ましく、３５質量％以下が特に好ましい。 (Composition ratio of light emitting layer forming composition)
As described above, the composition for forming a light emitting layer of the present invention may contain other components as appropriate as long as it contains at least the high Tg compound and the low Tg compound as described above. However, it is necessary that the content of the low Tg compound with respect to all the non-light emitting materials contained in the composition for forming a light emitting layer (hereinafter simply referred to as the content of the low Tg compound) is 8 to 70% by mass, More preferably, it is 10 to 70% by mass. The content rate of a low Tg compound is 8 mass% or more, 10 mass% or more is preferable and 15 mass% or more is more preferable. Moreover, the content rate of a low Tg compound is 80 mass% or less, 70 mass% or less is preferable, 50 mass% or less is more preferable, 40 mass% or less is further more preferable, and 35 mass% or less is especially preferable.
　低Ｔｇ化合物の含有率は、溶剤への溶解性や溶解した後のインク保存安定性、発光層の結晶化が起こりづらく発光面が均一かつ安定となる点では、高いことが好ましい。一方、低Ｔｇ化合物の含有率は、素子の高温保存における膜のモルフォロジーの変化が起こりにくい点では、低いことが好ましい。 The content of the low Tg compound is preferably high from the viewpoints of solubility in a solvent, ink storage stability after dissolution, and the light emitting surface is uniform and stable because crystallization of the light emitting layer is difficult to occur. On the other hand, the content of the low Tg compound is preferably low in that the film morphology hardly changes when the device is stored at high temperature.
　発光層形成用組成物に含まれる全ての非発光材料に対する高Ｔｇ化合物の含有率（以下、単に高Ｔｇ化合物の含有率と記載）は、１０質量％以上が好ましく、１５質量％以上がさらに好ましく、また、９０質量％以下が好ましく、７０質量％以下が更に好ましい。
高Ｔｇ化合物の含有率は、低Ｔｇ化合物とは逆に、溶剤への溶解性や溶解した後の保存安定性、発光層の結晶化が起こりづらく発光面が均一かつ安定となる点では、低いことが好ましく、素子の高温保存における膜のモルフォロジーの変化が起こりにくい点では、高いことが好ましい。
　また、発光層形成用組成物に含まれる全不揮発性材料における発光材料の含有率は、５質量％以上が好ましく、１０質量％以上がさらに好ましく、また、４０質量％以下が好ましく、３０質量％以下が更に好ましい。 The content of the high Tg compound with respect to all the non-light emitting materials contained in the composition for forming the light emitting layer (hereinafter simply referred to as the content of the high Tg compound) is preferably 10% by mass or more, and more preferably 15% by mass or more. Moreover, 90 mass% or less is preferable, and 70 mass% or less is still more preferable.
Contrary to the low Tg compound, the content of the high Tg compound is low in that it is soluble in a solvent, storage stability after dissolution, and the light emitting surface is uniform and stable because crystallization of the light emitting layer is difficult to occur. It is preferable that it is high in that the film morphology hardly changes when the device is stored at high temperature.
In addition, the content of the light emitting material in all the nonvolatile materials contained in the composition for forming a light emitting layer is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 40% by mass or less, and 30% by mass. The following is more preferable.
　（本発明の作用機構）
　高Ｔｇ化合物を含むことで、膜の耐熱性が向上し、低Ｔｇ化合物を含むことで、成膜時に均一な膜が形成できると推測される。
　高Ｔｇ化合物は、成膜時に結晶化しやすく、剛直な化合物であるため、高Ｔｇ化合物同士は分子レベルでは密接しにくいことから、膜の電荷輸送性を低下させる。しかし、低Ｔｇ化合物が存在すると、低Ｔｇ化合物が剛直な高Ｔｇ化合物同士の隙間を埋める形になり、高Ｔｇ化合物の結晶化を抑制し、かつ均一な膜が形成できると推測される。 (Action mechanism of the present invention)
By including a high Tg compound, the heat resistance of the film is improved, and by including a low Tg compound, a uniform film can be formed during film formation.
High Tg compounds are easy to crystallize at the time of film formation and are rigid compounds. Therefore, high Tg compounds are difficult to come into close contact with each other at the molecular level, thereby reducing the charge transport property of the film. However, when a low Tg compound is present, it is presumed that the low Tg compound fills the gaps between the rigid high Tg compounds, suppresses crystallization of the high Tg compound, and forms a uniform film.
　さらに、低Ｔｇ化合物と高Ｔｇ化合物を含む組成物を湿式成膜すると、低Ｔｇ化合物と高Ｔｇ化合物が均一に混合した状態で乾燥する。つまり、低Ｔｇ化合物が剛直な高Ｔｇ化合物同士の隙間を埋めた膜を容易に形成でき、輸送性に優れた均一な膜が形成されやすくなると考えられる。従来の真空加熱蒸着方法では、材料がクラスターとなって蒸着されるため、高Ｔｇ化合物同士の隙間を低Ｔｇ化合物が埋めにくいと考えられる。 Further, when a composition containing a low Tg compound and a high Tg compound is formed into a wet film, it is dried in a state where the low Tg compound and the high Tg compound are uniformly mixed. That is, it is considered that a film in which the gap between the high Tg compounds rigid with the low Tg compound is filled can be easily formed, and a uniform film excellent in transportability can be easily formed. In the conventional vacuum heating vapor deposition method, since the material is deposited in clusters, it is considered that the low Tg compound is difficult to fill the gap between the high Tg compounds.
　また、膜中では、低Ｔｇ化合物が高Ｔｇ化合物間に存在するため、高Ｔｇ化合物の結晶化が抑制された、耐熱性の高い膜となると考えられる。
　また、通常、低Ｔｇ化合物のみを有機電界発光素子に用いた場合は耐熱性が不足するため、高温保存によって有機電界発光素子の劣化が促進されたり、通電駆動で劣化が早まると考えられていた。驚くべきことに、本発明では、低Ｔｇ化合物と高Ｔｇ化合物を混合することで、低Ｔｇ化合物と高Ｔｇ化合物の相互作用により有機電界発光素子の耐熱性が向上するという予期せぬ効果を見出した。これは、高温保存時の熱や通電駆動での発熱による低Ｔｇ化合物の熱運動が、低Ｔｇ化合物の近傍に存在する高Ｔｇ化合物によって抑制されているためであると推測される。 Further, in the film, a low Tg compound exists between the high Tg compounds, so that it is considered that the film has high heat resistance in which crystallization of the high Tg compound is suppressed.
In addition, when only a low Tg compound is used for an organic electroluminescent device, heat resistance is usually insufficient, and thus it is believed that the organic electroluminescent device is accelerated by storage at a high temperature, or is accelerated by energization driving. . Surprisingly, the present invention has found an unexpected effect that the heat resistance of the organic electroluminescence device is improved by the interaction of the low Tg compound and the high Tg compound by mixing the low Tg compound and the high Tg compound. It was. This is presumably because the thermal motion of the low Tg compound due to heat during high-temperature storage and heat generation during energization driving is suppressed by the high Tg compound present in the vicinity of the low Tg compound.
　低Ｔｇ化合物を含むことで、有機溶媒への溶解性が向上して組成物の保存安定性を確保できるだけでなく、有機電界発光素子の膜中での結晶化を抑えることができ、室温における駆動寿命を長くすることができる。加えて、高Ｔｇ化合物を含むことで、低Ｔｇ化合物により懸念される１００℃付近での高温保存下における膜物性やモルフォロジーの変化を抑えることができ、高温保存後でも変わらず安定した長い駆動寿命を得ることができる。 By including a low Tg compound, the solubility in an organic solvent can be improved and the storage stability of the composition can be ensured, and crystallization in the film of the organic electroluminescent device can be suppressed, and driving at room temperature is possible. The lifetime can be extended. In addition, by including a high Tg compound, it is possible to suppress changes in film properties and morphology under high temperature storage near 100 ° C., which is a concern due to low Tg compounds, and stable and long driving life even after high temperature storage Can be obtained.
　高Ｔｇ化合物のＴｇが１３０℃以上である理由は前述の通りである。
　また、低Ｔｇ化合物のＴｇが１００℃以下であることで、高Ｔｇ化合物との相互作用が抑制され、低Ｔｇ化合物の結晶化抑制の効果が発現しやすい傾向にある。本発明のように３０℃以上の差がある場合には、互いのＴｇに由来する効果がそれぞれ十分に発現すると考えられる。
　高Ｔｇ化合物と低Ｔｇ化合物のＴｇの差は特に限定されないが、３０℃以上が好ましく、４０℃以上がより好ましく、５０℃以上がさらに好ましい。また、７０℃以下が好ましく、６５℃以下がより好ましい。上記下限値以上であることで、Ｔｇ差がある程度大きくなり、高Ｔｇ化合物が低Ｔｇ化合物の分子運動の影響を受けにくくなるため、高温においても膜のモルフォロジーが変化しにくくなる。また上記上限値以下であることで、高Ｔｇ化合物と低Ｔｇ化合物がより均一に膜中で混ざり易くなる。 The reason why the Tg of the high Tg compound is 130 ° C. or higher is as described above.
Further, when the Tg of the low Tg compound is 100 ° C. or lower, the interaction with the high Tg compound is suppressed, and the effect of suppressing the crystallization of the low Tg compound tends to be easily exhibited. When there is a difference of 30 ° C. or more as in the present invention, it is considered that the effects derived from each other's Tg are sufficiently developed.
The difference in Tg between the high Tg compound and the low Tg compound is not particularly limited, but is preferably 30 ° C or higher, more preferably 40 ° C or higher, and further preferably 50 ° C or higher. Moreover, 70 degrees C or less is preferable and 65 degrees C or less is more preferable. By being above the lower limit, the Tg difference is increased to some extent, and the high Tg compound is less susceptible to the molecular motion of the low Tg compound, so that the film morphology is less likely to change even at high temperatures. Moreover, it becomes easy to mix a high Tg compound and a low Tg compound more uniformly in a film | membrane because it is below the said upper limit.
　低Ｔｇ化合物の含有率は、前述の通り８～７０質量％である。８質量％以上であることで、高Ｔｇ化合物の分子間相互作用に与える影響があり、膜及び有機溶媒中での結晶化を抑制しやすい。また、７０質量％以下であることで、低Ｔｇ化合物に起因する高温保存時の結晶性の変化を、残り３０質量％未満の他の材料により吸収することができ、膜全体のモルフォロジー変化を抑制できる傾向にある。 The content of the low Tg compound is 8 to 70% by mass as described above. By being 8 mass% or more, there is an influence on the intermolecular interaction of the high Tg compound, and it is easy to suppress crystallization in the film and the organic solvent. Moreover, by being 70% by mass or less, the change in crystallinity during high-temperature storage caused by the low Tg compound can be absorbed by other materials less than 30% by mass, and the change in the morphology of the entire film is suppressed. It tends to be possible.
　高Ｔｇ化合物及び低Ｔｇ化合物のいずれかが、電子輸送性が高く、構造安定性に優れたピリミジン骨格又はトリアジン骨格であることで、発光材料上に電子が局在化する確率が下がり、安定した発光を得ることができる。従って、上記長寿命化の効果を十分に得ることができる。
　さらに低Ｔｇ化合物が、単環化合物同士が直接結合及び／又は連結基を介して結合した化合物であると、分子としての平面性がより低くなり、分子パッキングによる結晶化をより引き起こしにくくなる。従って、上記結晶化抑制の効果をより一層得ることができる。 Any of the high Tg compound and the low Tg compound has a high electron transporting property and a pyrimidine skeleton or a triazine skeleton excellent in structural stability, so that the probability that electrons are localized on the light emitting material is lowered and stable. Luminescence can be obtained. Therefore, the effect of extending the life can be sufficiently obtained.
Furthermore, when the low Tg compound is a compound in which monocyclic compounds are bonded directly and / or via a linking group, the planarity as a molecule is lower and crystallization due to molecular packing is less likely to occur. Therefore, the effect of suppressing the crystallization can be further obtained.
　本発明の発光層形成用組成物に含まれる全非発光材料の総量に対する含有率が１．０質量％以上である各非発光材料の分子量は５０００以下が好ましい。上記分子量がこの範囲であることで、ほとんどの非発光材料が均一に混合した状態で成膜されて好ましい。
　高分子量の化合物が膜中に少ないと、３次元的な分子の絡まりが抑制され、高Ｔｇ化合物と低Ｔｇ化合物とが均一に混合されやすくなる。その結果、低Ｔｇ化合物同士が集まった微小な領域の生成が抑制され、高温保存時の安定性が得られ易くなる。また、成膜時に高Ｔｇ化合物同士が集まった微小な領域が生成して成膜時に結晶化することを抑制し、均一な膜が得られ易くなり、有機電界発光素子の特性が向上する。
　また、上記分子量の上限以下であることで、化合物の溶媒への溶解性が改善したり、溶媒中での分子鎖の絡まりが抑制され、不純物(すなわち劣化原因物質)の除去が行いやすくなる。 The molecular weight of each non-light emitting material having a content of 1.0% by mass or more based on the total amount of all non-light emitting materials contained in the composition for forming a light emitting layer of the present invention is preferably 5000 or less. When the molecular weight is within this range, it is preferable that a film is formed in a state where most non-light emitting materials are uniformly mixed.
When the high molecular weight compound is small in the film, the three-dimensional molecular entanglement is suppressed, and the high Tg compound and the low Tg compound are easily mixed uniformly. As a result, the generation of a minute region in which low Tg compounds are gathered is suppressed, and stability during high-temperature storage is easily obtained. In addition, a minute region in which high Tg compounds are gathered at the time of film formation and crystallization at the time of film formation is suppressed, and a uniform film can be easily obtained, thereby improving the characteristics of the organic electroluminescent element.
Further, when the molecular weight is not more than the upper limit of the molecular weight, the solubility of the compound in the solvent is improved, the entanglement of the molecular chain in the solvent is suppressed, and the impurities (that is, the deterioration-causing substance) can be easily removed.
　本発明において、発光層形成用組成物に含まれる全ての非発光材料の加重平均ガラス転移温度は、１００℃以上であることが好ましく、１１５℃以上であることがより好ましい。また加重平均ガラス転移温度は、好ましくは１５０℃以下であり、より好ましくは１４５℃以下である。加重平均ガラス転移温度が１００℃以上であることで、高温保存時の熱や、通電時に有機電界発光素子内で発生する熱の影響を受けて膜のモルフォロジーが変化しにくく、すなわち駆動寿命がより長くなる。また、加重平均ガラス転移温度が１５０℃以下であることで、分子同士の隙間が埋まりやすくなり、膜中の電荷輸送性しいては駆動寿命が改善する。 In the present invention, the weighted average glass transition temperature of all non-light emitting materials contained in the composition for forming a light emitting layer is preferably 100 ° C. or higher, more preferably 115 ° C. or higher. The weighted average glass transition temperature is preferably 150 ° C. or lower, more preferably 145 ° C. or lower. When the weighted average glass transition temperature is 100 ° C. or higher, the film morphology is less likely to change under the influence of heat during high-temperature storage and heat generated in the organic electroluminescence device when energized, that is, the driving life is more become longer. Further, when the weighted average glass transition temperature is 150 ° C. or lower, the gaps between the molecules are easily filled, and the driving life is improved in terms of charge transportability in the film.
（その他の非発光材料）
　本発明の発光層形成用組成物が、上記高Ｔｇ化合物及び低Ｔｇ化合物以外に含んでいてもよい非発光材料としては、電荷輸送材料及び酸化防止剤等の添加剤が挙げられる。 (Other non-light emitting materials)
Examples of the non-light emitting material that the composition for forming a light emitting layer of the present invention may contain in addition to the high Tg compound and the low Tg compound include additives such as a charge transport material and an antioxidant.
＜第３の電荷輸送材料＞
　本発明の発光層形成用組成物には、前記高Ｔｇ化合物又は前記低Ｔｇ化合物のいずれにも属さない電荷輸送材料が含まれていてもよい。便宜上、これを第３の電荷輸送材料と呼ぶ。第３の電荷輸送材料としては、電荷輸送性に優れる骨格を有する材料が好ましい。
　電荷輸送性に優れる骨格としては、具体的には、芳香族構造、芳香族アミン構造、トリアリールアミン構造、ジベンゾフラン構造、ナフタレン構造、フェナントレン構造、フタロシアニン構造、ポルフィリン構造、チオフェン構造、ベンジルフェニル構造、フルオレン構造、キナクリドン構造、トリフェニレン構造、カルバゾール構造、ピレン構造、アントラセン構造、フェナントロリン構造、キノリン構造、ピリジン構造、ピリミジン構造、トリアジン構造、オキサジアゾール構造、イミダゾール構造等が挙げられる。 <Third charge transport material>
The composition for forming a light emitting layer of the present invention may contain a charge transport material that does not belong to either the high Tg compound or the low Tg compound. For convenience, this is referred to as a third charge transport material. As the third charge transport material, a material having a skeleton excellent in charge transportability is preferable.
Specific examples of the skeleton having excellent charge transportability include aromatic structures, aromatic amine structures, triarylamine structures, dibenzofuran structures, naphthalene structures, phenanthrene structures, phthalocyanine structures, porphyrin structures, thiophene structures, benzylphenyl structures, Fluorene structure, quinacridone structure, triphenylene structure, carbazole structure, pyrene structure, anthracene structure, phenanthroline structure, quinoline structure, pyridine structure, pyrimidine structure, triazine structure, oxadiazole structure, imidazole structure and the like can be mentioned.
　中でも、電子輸送特性に優れ構造が比較的安定な材料である観点から、ピリジン構造、ピリミジン構造及びトリアジン構造を有する化合物からなる群から選択される少なくとも１つがより好ましく、ピリミジン構造、及び/又はトリアジン構造を有する化合物であることがさらに好ましい。
　本発明における第３の電荷輸送材料は、発光材料自身が電子を輸送することによる発光材料の劣化を抑え駆動寿命をより長くできるという点で、電子輸送性に優れた構造を有する材料であることが好ましい。 Among these, from the viewpoint of being a material having an excellent electron transport property and a relatively stable structure, at least one selected from the group consisting of compounds having a pyridine structure, a pyrimidine structure and a triazine structure is more preferable, and a pyrimidine structure and / or a triazine. More preferably, it is a compound having a structure.
The third charge transporting material in the present invention is a material having a structure excellent in electron transporting property in that the light emitting material itself can suppress deterioration of the light emitting material due to transport of electrons and can extend the driving life. Is preferred.
　また、正孔輸送性に優れた構造を有する化合物も好ましく、前記電荷輸送性に優れた中心骨格の中でも、カルバゾール構造、ジベンゾフラン構造、トリアリールアミン構造、ナフタレン構造、フェナントレン構造又はピレン構造が正孔輸送性に優れた構造として好ましく、カルバゾール構造、ジベンゾフラン構造又はトリアリールアミン構造がさらに好ましい。 Further, a compound having a structure excellent in hole transportability is also preferable, and among the central skeleton excellent in charge transportability, a carbazole structure, dibenzofuran structure, triarylamine structure, naphthalene structure, phenanthrene structure or pyrene structure is a hole. A structure excellent in transportability is preferable, and a carbazole structure, a dibenzofuran structure, or a triarylamine structure is more preferable.
　本発明における第３の電荷輸送材料は、発光材料自身が正孔を輸送することによる発光材料の劣化を抑え駆動寿命をより長くできるという点で、正孔輸送性に優れた構造を有する材料であることが好ましい。
　本発明における第３の電荷輸送材料の分子量は、本発明の効果を著しく損なわない限り任意である。本発明における第３の電荷輸送材料の分子量は、通常５０００以下、好ましくは４０００以下、さらに好ましくは３０００以下、最も好ましくは２０００以下である。また、本発明における第３の電荷輸送材料の分子量は、通常３００以上、好ましくは３５０以上、更に好ましくは４００以上である。 The third charge transporting material in the present invention is a material having a structure excellent in hole transporting property in that the light emitting material itself can suppress the deterioration of the light emitting material due to transporting holes and can extend the driving life. Preferably there is.
The molecular weight of the third charge transport material in the present invention is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight of the third charge transport material in the present invention is usually 5000 or less, preferably 4000 or less, more preferably 3000 or less, and most preferably 2000 or less. The molecular weight of the third charge transport material in the present invention is usually 300 or more, preferably 350 or more, more preferably 400 or more.
　第３の電荷輸送材料の分子量は、ガス発生や再結晶化及び分子のマイグレーション等に起因する膜質の低下が起こり難い点では大きいことが好ましい。一方、第３の電荷輸送材料の分子量は、有機化合物の精製が容易で、溶剤に溶解させやすい点では小さいことが好ましい。
　本発明の発光層形成用組成物には、前記高Ｔｇ化合物又は前記低Ｔｇ化合物のいずれにも属さない第３の電荷輸送材料が含まれていることが好ましい。また、第３の電荷輸送材料は２種以上であってもかまわない。 It is preferable that the molecular weight of the third charge transport material is large in that the film quality is hardly deteriorated due to gas generation, recrystallization, molecular migration, or the like. On the other hand, the molecular weight of the third charge transport material is preferably small in that the organic compound can be easily purified and easily dissolved in a solvent.
The composition for forming a light emitting layer of the present invention preferably contains a third charge transport material that does not belong to either the high Tg compound or the low Tg compound. Two or more third charge transport materials may be used.
　［発光層の形成方法］
　本発明に係る発光層は、上述の本発明の発光層形成用組成物を用いて湿式成膜法で形成される。 [Method of forming light emitting layer]
The light emitting layer according to the present invention is formed by a wet film forming method using the above-described composition for forming a light emitting layer of the present invention.
　（湿式成膜による発光層の形成方法）
　本発明において湿式成膜法とは、成膜方法、即ち、塗布方法として湿式で成膜させる方法を採用し、この塗布膜を乾燥させて膜形成を行う方法をいう。塗布方法としては、例えば、スピンコート法、ディップコート法、ダイコート法、バーコート法、ブレードコート法、ロールコート法、スプレーコート法、キャピラリーコート法、インクジェット法、ノズルプリンティング法、スクリーン印刷法、グラビア印刷法、フレキソ印刷法等が挙げられる。これらの成膜方法の中でも、スピンコート法、スプレーコート法、インクジェット法、ノズルプリンティング法等が好ましい。 (Method of forming light emitting layer by wet film formation)
In the present invention, the wet film forming method refers to a film forming method, that is, a method in which a wet film forming method is employed as a coating method, and this coating film is dried to form a film. Examples of coating methods include spin coating, dip coating, die coating, bar coating, blade coating, roll coating, spray coating, capillary coating, ink jet, nozzle printing, screen printing, and gravure. Examples thereof include a printing method and a flexographic printing method. Among these film forming methods, spin coating, spray coating, ink jet, nozzle printing, and the like are preferable.
　湿式成膜法により発光層を形成する場合は、通常、上述の発光材料、高Ｔｇ化合物、低Ｔｇ化合物、及び必要に応じて用いられるその他の材料を適切な有機溶媒に溶解させることにより調製した発光層形成用組成物を用いて成膜し、加熱、減圧等により有機溶媒を除去することにより形成する。
　有機溶媒の除去方法としては、加熱又は減圧を用いることができる。加熱方法において使用する加熱手段としては、膜全体に均等に熱を与えることから、クリーンオーブン、ホットプレート等が好ましい。 When the light emitting layer is formed by a wet film forming method, it is usually prepared by dissolving the above-described light emitting material, high Tg compound, low Tg compound, and other materials used as necessary in an appropriate organic solvent. A film is formed using the composition for forming a light emitting layer, and the organic solvent is removed by heating, decompression, or the like.
As a method for removing the organic solvent, heating or reduced pressure can be used. As the heating means used in the heating method, a clean oven, a hot plate, or the like is preferable because heat is uniformly applied to the entire film.
　加熱工程における加熱温度は、本発明の効果を著しく損なわない限り任意であるが、乾燥時間を短くする点では温度が高いほうが好ましく、材料へのダメージが少ない点では低い方が好ましい。
　上限は通常２５０℃以下であり、好ましくは２００℃以下、さらに好ましくは１５０℃以下である。下限は通常３０℃以上であり、好ましくは５０℃以上であり、さらに好ましくは８０℃以上である。上限以下の温度であることで、通常用いられる電荷輸送材料又は燐光発光材料の分解や結晶化を抑制できる。また、上記下限以上であることで、溶媒の除去時間を短縮することができる。加熱工程における加熱時間は、発光層形成用組成物中の溶媒の沸点や蒸気圧、材料の耐熱性、及び加熱条件によって適切に決定される。 The heating temperature in the heating step is arbitrary as long as the effects of the present invention are not significantly impaired. However, a higher temperature is preferable in terms of shortening the drying time, and a lower temperature is preferable in terms of less damage to the material.
The upper limit is usually 250 ° C. or lower, preferably 200 ° C. or lower, more preferably 150 ° C. or lower. The lower limit is usually 30 ° C. or higher, preferably 50 ° C. or higher, more preferably 80 ° C. or higher. When the temperature is not more than the upper limit, decomposition or crystallization of a commonly used charge transport material or phosphorescent material can be suppressed. Moreover, the removal time of a solvent can be shortened because it is more than the said minimum. The heating time in the heating step is appropriately determined depending on the boiling point and vapor pressure of the solvent in the composition for forming the light emitting layer, the heat resistance of the material, and the heating conditions.
［ガラス転移温度（Ｔｇ）の測定方法］
　本発明におけるＴｇの測定方法は以下の通りである。
　示差走査熱量計を用いて、室温（２５℃）から３００℃まで１０℃／ｍｉｎの昇温速度で測定し、それによって得られたＤＳＣカーブにおけるガラス転移を示す変曲点の中心の温度をＴｇとした。測定条件を下記に示す。 [Measurement method of glass transition temperature (Tg)]
The measuring method of Tg in the present invention is as follows.
Using a differential scanning calorimeter, the temperature at room temperature (25 ° C.) to 300 ° C. was measured at a rate of temperature increase of 10 ° C./min, and the temperature at the center of the inflection point showing the glass transition in the DSC curve thus obtained was Tg. It was. The measurement conditions are shown below.
＜ガラス転移点温度測定条件＞
　示差走査熱量計（ＤＳＣ）：島津　ＤＴＡ－５０
　試料量：約４ｍｇ
　試料容器：アルミパン
　雰囲気：大気
　温度範囲：室温（２５℃）～３００℃
　昇温速度：１０℃／ｍｉｎ
　加重平均ガラス転移温度は、全非発光材料について、上記方法により求めた各非発光材料のＴｇに各非発光材料の重量比率を乗じたものの総和である。 <Glass transition temperature measurement conditions>
Differential scanning calorimeter (DSC): Shimadzu DTA-50
Sample amount: about 4mg
Sample container: Aluminum pan Atmosphere: Air Temperature range: Room temperature (25 ° C) to 300 ° C
Temperature increase rate: 10 ° C / min
The weighted average glass transition temperature is the sum of all non-luminescent materials multiplied by the weight ratio of each non-luminescent material to the Tg of each non-luminescent material determined by the above method.
［有機電界発光素子の層構成と製造方法］
　以下に、本発明に係る有機電界発光素子の一般的層構成及びその製造方法等の実施の形態の一例を、図１を参照して説明する。
　図１は本発明に係る有機電界発光素子１０の構造例を示す断面の模式図であり、図１において、１は基板、２は陽極、３は正孔注入層、４は正孔輸送層、５は発光層、６は正孔阻止層、７は電子輸送層、８は電子注入層、９は陰極を各々表す。 [Layer structure and manufacturing method of organic electroluminescent element]
Hereinafter, an example of an embodiment of a general layer configuration of an organic electroluminescent element according to the present invention and a manufacturing method thereof will be described with reference to FIG.
FIG. 1 is a schematic cross-sectional view showing a structural example of an organic electroluminescent device 10 according to the present invention. In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transport layer, Reference numeral 5 denotes a light emitting layer, 6 denotes a hole blocking layer, 7 denotes an electron transport layer, 8 denotes an electron injection layer, and 9 denotes a cathode.
　これらの構造に適用する材料は、公知の材料を適用することができ、特に制限はないが、各層に関しての代表的な材料や製法を一例として以下に記載する。また、公報や論文等を引用している場合、該当内容を当業者の常識の範囲で適宜、適用、応用することができるものとする。 The materials applied to these structures can be known materials and are not particularly limited, but typical materials and manufacturing methods for each layer are described below as an example. In addition, when citing publications and papers, the relevant contents can be applied and applied as appropriate within the scope of common knowledge of those skilled in the art.
（基板１）
　基板１は、有機電界発光素子の支持体となるものであり、通常、石英やガラスの板、金属板や金属箔、プラスチックフィルムやシート等が用いられる。これらのうち、ガラス板や、ポリエステル、ポリメタクリレート、ポリカーボネート、ポリスルホン等の透明な合成樹脂の板が好ましい。基板１は、外気による有機電界発光素子の劣化が起こり難いことからガスバリア性の高い材質とするのが好ましい。このため、特に合成樹脂製の基板等のようにガスバリア性の低い材質を用いる場合は、基板１の少なくとも片面に緻密なシリコン酸化膜等を設けてガスバリア性を上げるのが好ましい。 (Substrate 1)
The substrate 1 serves as a support for the organic electroluminescent element, and a quartz or glass plate, a metal plate or a metal foil, a plastic film or a sheet is usually used. Of these, glass plates and transparent synthetic resin plates such as polyester, polymethacrylate, polycarbonate, and polysulfone are preferable. The substrate 1 is preferably made of a material having a high gas barrier property because the organic electroluminescence element is hardly deteriorated by the outside air. For this reason, when using a material having a low gas barrier property, such as a synthetic resin substrate, it is preferable to provide a dense silicon oxide film or the like on at least one surface of the substrate 1 to improve the gas barrier property.
（陽極２）
　陽極２は、発光層側の層に正孔を注入する機能を担う。陽極２は、通常、アルミニウム、金、銀、ニッケル、パラジウム、白金等の金属；インジウム及び／又はスズの酸化物等の金属酸化物；ヨウ化銅等のハロゲン化金属；カーボンブラック及びポリ（３－メチルチオフェン）、ポリピロール、ポリアニリン等の導電性高分子等により構成される。陽極２の形成は、通常、スパッタリング法、真空蒸着法等の乾式法により行われることが多い。また、銀等の金属微粒子、ヨウ化銅等の微粒子、カーボンブラック、導電性の金属酸化物微粒子、導電性高分子微粉末等を用いて陽極２を形成する場合には、適当なバインダー樹脂溶液に分散させて、基板上に塗布することにより形成することもできる。また、導電性高分子の場合は、電解重合により直接基板上に薄膜を形成したり、基板上に導電性高分子を塗布して陽極２を形成することもできる（Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．，６０巻，２７１１頁，１９９２年）。 (Anode 2)
The anode 2 has a function of injecting holes into the layer on the light emitting layer side. The anode 2 is usually made of a metal such as aluminum, gold, silver, nickel, palladium, or platinum; a metal oxide such as an oxide of indium and / or tin; a metal halide such as copper iodide; a carbon black and a poly (3 -Methylthiophene), conductive polymers such as polypyrrole and polyaniline, and the like. In general, the anode 2 is often formed by a dry method such as a sputtering method or a vacuum deposition method. In addition, when forming the anode 2 using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, and conductive polymer fine powder, an appropriate binder resin solution It can also be formed by being dispersed in and coated on a substrate. In the case of a conductive polymer, a thin film can be directly formed on the substrate by electrolytic polymerization, or the anode 2 can be formed by applying a conductive polymer on the substrate (Appl. Phys. Lett., 60, 2711, 1992).
　陽極２は、通常、単層構造であるが、適宜、積層構造としてもよい。陽極２が積層構造である場合、１層目の陽極上に異なる導電材料を積層してもよい。　陽極２の厚みは、必要とされる透明性と材質等に応じて、決めればよい。特に高い透明性が必要とされる場合は、可視光の透過率が６０％以上となる厚みが好ましく、８０％以上となる厚みが更に好ましい。陽極２の厚みは、通常５ｎｍ以上、好ましくは１０ｎｍ以上であり、また、通常１０００ｎｍ以下、好ましくは５００ｎｍ以下とするのが好ましい。一方、透明性が不要な場合は、陽極２の厚みは必要な強度等に応じて任意に厚みとすればよく、この場合、陽極２は基板１と同一の厚みでもよい。
　陽極２の表面に成膜を行う場合は、成膜前に、紫外線＋オゾン、酸素プラズマ、アルゴンプラズマ等の処理を施すことにより、陽極上の不純物を除去すると共に、そのイオン化ポテンシャルを調整して正孔注入性を向上させておくのが好ましい。 The anode 2 usually has a single layer structure, but may have a laminated structure as appropriate. When the anode 2 has a laminated structure, different conductive materials may be laminated on the first anode. The thickness of the anode 2 may be determined according to required transparency and material. In particular, when high transparency is required, a thickness at which visible light transmittance is 60% or more is preferable, and a thickness at which 80% or more is more preferable. The thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably 500 nm or less. On the other hand, when transparency is not required, the thickness of the anode 2 may be arbitrarily set according to the required strength. In this case, the anode 2 may have the same thickness as the substrate 1.
When film formation is performed on the surface of the anode 2, impurities on the anode are removed and the ionization potential thereof is adjusted by performing treatment such as ultraviolet ray + ozone, oxygen plasma, argon plasma before film formation. It is preferable to improve the hole injection property.
（正孔注入層３）
　陽極側から発光層側に正孔を輸送する機能を担う層は、通常、正孔注入輸送層又は正孔輸送層と呼ばれる。そして、陽極側から発光層側に正孔を輸送する機能を担う層が２層以上ある場合に、より陽極側に近い方の層を正孔注入層３と呼ぶことがある。正孔注入層３は、陽極から発光層側に正孔を輸送する機能を強化する点で、用いることが好ましい。正孔注入層３を用いる場合、通常、正孔注入層３は、陽極上に形成される。 (Hole injection layer 3)
The layer responsible for transporting holes from the anode side to the light emitting layer side is usually called a hole injection transport layer or a hole transport layer. When there are two or more layers responsible for transporting holes from the anode side to the light emitting layer side, the layer closer to the anode side may be referred to as the hole injection layer 3. The hole injection layer 3 is preferably used from the viewpoint of enhancing the function of transporting holes from the anode to the light emitting layer side. When the hole injection layer 3 is used, the hole injection layer 3 is usually formed on the anode.
　正孔注入層３の膜厚は、通常１ｎｍ以上、好ましくは５ｎｍ以上、また、通常１０００ｎｍ以下、好ましくは５００ｎｍ以下である。
　正孔注入層３の形成方法は、真空蒸着法でも、湿式成膜法でもよい。成膜性が優れる点では、湿式成膜法により形成することが好ましい。
　正孔注入層３は、正孔輸送性化合物を含むことが好ましく、正孔輸送性化合物と電子受容性化合物とを含むことがより好ましい。更には、正孔注入層中にカチオンラジカル化合物を含むことが好ましく、カチオンラジカル化合物と正孔輸送性化合物とを含むことが特に好ましい。 The thickness of the hole injection layer 3 is usually 1 nm or more, preferably 5 nm or more, and usually 1000 nm or less, preferably 500 nm or less.
The formation method of the hole injection layer 3 may be a vacuum deposition method or a wet film formation method. In terms of excellent film forming properties, it is preferable to form the film by a wet film forming method.
The hole injection layer 3 preferably contains a hole transporting compound, and more preferably contains a hole transporting compound and an electron accepting compound. Further, the hole injection layer preferably contains a cation radical compound, and particularly preferably contains a cation radical compound and a hole transporting compound.
＜正孔輸送性化合物＞
　正孔注入層形成用組成物は、通常、正孔注入層３となる正孔輸送性化合物を含有する。また、湿式成膜法の場合は、通常、更に溶剤も含有する。正孔注入層形成用組成物は、正孔輸送性が高く、注入された正孔を効率よく輸送できるのが好ましい。このため、正孔移動度が大きく、トラップとなる不純物が製造時や使用時等に発生し難いのが好ましい。また、安定性に優れ、イオン化ポテンシャルが小さく、可視光に対する透明性が高いことが好ましい。特に、正孔注入層３が発光層５と接する場合は、発光層５からの発光を消光しないものや発光層５とエキサイプレックスを形成して、発光効率を低下させないものが好ましい。 <Hole transporting compound>
The composition for forming a hole injection layer usually contains a hole transporting compound that becomes the hole injection layer 3. In the case of a wet film forming method, a solvent is usually further contained. It is preferable that the composition for forming a hole injection layer has high hole transportability and can efficiently transport injected holes. For this reason, it is preferable that the hole mobility is high and impurities that become traps are less likely to be generated during production or use. Moreover, it is preferable that it is excellent in stability, has a small ionization potential, and has high transparency to visible light. In particular, when the hole injection layer 3 is in contact with the light emitting layer 5, it is preferable that the light emission from the light emitting layer 5 does not quench or that the light emitting layer 5 is exciplexed and the light emission efficiency is not lowered.
　正孔輸送性化合物としては、陽極２から正孔注入層３への電荷注入障壁の観点から、４．５ｅＶ～６．０ｅＶのイオン化ポテンシャルを有する化合物が好ましい。正孔輸送性化合物の例としては、芳香族アミン系化合物、フタロシアニン系化合物、ポルフィリン系化合物、オリゴチオフェン系化合物、ポリチオフェン系化合物、ベンジルフェニル系化合物、フルオレン基で３級アミンを連結した化合物、ヒドラゾン系化合物、シラザン系化合物系化合物、キナクリドン系化合物等が挙げられる。 The hole transporting compound is preferably a compound having an ionization potential of 4.5 eV to 6.0 eV from the viewpoint of a charge injection barrier from the anode 2 to the hole injection layer 3. Examples of hole transporting compounds include aromatic amine compounds, phthalocyanine compounds, porphyrin compounds, oligothiophene compounds, polythiophene compounds, benzylphenyl compounds, compounds in which tertiary amines are linked by a fluorene group, hydrazones Compound, silazane compound compound, quinacridone compound and the like.
　上述の例示化合物のうち、非晶質性及び可視光透過性の点から、芳香族アミン化合物が好ましく、芳香族三級アミン化合物が特に好ましい。ここで、芳香族三級アミン化合物とは、芳香族三級アミン構造を有する化合物であって、芳香族三級アミン由来の基を有する化合物も含む。
　芳香族三級アミン化合物の種類は、特に制限されないが、表面平滑化効果により均一な発光を得やすい点から、重量平均分子量が１０００以上１００００００以下の高分子化合物（繰り返し単位が連なる重合型化合物）を用いるのが好ましい。芳香族三級アミン高分子化合物の好ましい例としては、下記式（ＩＩ）で表される繰り返し単位を有する高分子化合物等が挙げられる。 Of the above-described exemplary compounds, an aromatic amine compound is preferable and an aromatic tertiary amine compound is particularly preferable from the viewpoint of amorphousness and visible light transmittance. Here, the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and includes a compound having a group derived from an aromatic tertiary amine.
The type of the aromatic tertiary amine compound is not particularly limited, but is a polymer compound having a weight average molecular weight of 1,000 to 1,000,000 (polymerization compound in which repeating units are linked) from the viewpoint of easily obtaining uniform light emission due to the surface smoothing effect. Is preferably used. Preferable examples of the aromatic tertiary amine polymer compound include a polymer compound having a repeating unit represented by the following formula (II).
Figure JPOXMLDOC01-appb-C000006
Figure JPOXMLDOC01-appb-C000006
（式（ＩＩ）中、Ａｒ１及びＡｒ２は、それぞれ独立して、置換基を有していてもよい芳香族基又は置換基を有していてもよい複素芳香族基を表す。Ａｒ３～Ａｒ５は、それぞれ独立して、置換基を有していてもよい芳香族基又は置換基を有していてもよい複素芳香族基を表す。Ｙは、下記の連結基群の中から選ばれる連結基を表す。また、Ａｒ１～Ａｒ５のうち、同一のＮ原子に結合する二つの基は互いに結合して環を形成してもよい。
　下記に連結基を示す。 (In Formula (II), Ar 1 and Ar 2 each independently represent an aromatic group that may have a substituent or a heteroaromatic group that may have a substituent. Ar 3 To Ar 5 each independently represents an optionally substituted aromatic group or an optionally substituted heteroaromatic group, wherein Y is selected from the following group of linking groups. Represents a selected linking group, and among Ar 1 to Ar 5 , two groups bonded to the same N atom may be bonded to each other to form a ring.
The linking group is shown below.
Figure JPOXMLDOC01-appb-C000007
  
Figure JPOXMLDOC01-appb-C000007
  
（上記各式中、Ａｒ６～Ａｒ１６は、それぞれ独立して、置換基を有していてもよい芳香族基又は置換基を有していてもよい複素芳香族基を表す。Ｒ105及びＲ106は、それぞれ独立して、水素原子又は任意の置換基を表す。） (In the above formulas, Ar 6 to Ar 16 each independently represents an aromatic group which may have a substituent or a heteroaromatic group which may have a substituent. R 105 and R 106 each independently represents a hydrogen atom or an arbitrary substituent.)
　Ａｒ１～Ａｒ１６の芳香族基及び複素芳香族基としては、高分子化合物の溶解性、耐熱性、正孔注入輸送性の点から、ベンゼン環、ナフタレン環、フェナントレン環、チオフェン環、又はピリジン環由来の基が好ましく、ベンゼン環又はナフタレン環由来の基がさらに好ましい。
　式（ＩＩ）で表される繰り返し単位を有する芳香族三級アミン高分子化合物の具体例としては、国際公開第２００５／０８９０２４号パンフレットに記載のもの等が挙げられる。 The aromatic group and heteroaromatic group of Ar 1 to Ar 16 include a benzene ring, a naphthalene ring, a phenanthrene ring, a thiophene ring, or pyridine from the viewpoint of the solubility, heat resistance, and hole injection / transport properties of the polymer compound. A group derived from a ring is preferable, and a group derived from a benzene ring or a naphthalene ring is more preferable.
Specific examples of the aromatic tertiary amine polymer compound having a repeating unit represented by the formula (II) include those described in International Publication No. 2005/089024.
＜電子受容性化合物＞
　正孔注入層３には、正孔輸送性化合物の酸化により、正孔注入層３の導電率を向上させることができるため、電子受容性化合物を含有していることが好ましい。
　電子受容性化合物としては、酸化力を有し、上述の正孔輸送性化合物から一電子受容する能力を有する化合物が好ましく、具体的には、電子親和力が４ｅＶ以上である化合物が好ましく、電子親和力が５ｅＶ以上である化合物が更に好ましい。 <Electron-accepting compound>
The hole injection layer 3 preferably contains an electron accepting compound because the conductivity of the hole injection layer 3 can be improved by oxidation of the hole transporting compound.
As the electron-accepting compound, a compound having an oxidizing power and the ability to accept one electron from the above-described hole-transporting compound is preferable, and specifically, a compound having an electron affinity of 4 eV or more is preferable. More preferably, the compound is 5 eV or more.
　このような電子受容性化合物としては、例えば、トリアリールホウ素化合物、ハロゲン化金属、ルイス酸、有機酸、オニウム塩、アリールアミンとハロゲン化金属との塩、アリールアミンとルイス酸との塩よりなる群から選ばれる１種又は２種以上の化合物等が挙げられる。具体的には、４－イソプロピル－４’－メチルジフェニルヨードニウムテトラキス（ペンタフルオロフェニル）ボラート、トリフェニルスルホニウムテトラフルオロボラート等の有機基の置換したオニウム塩（国際公開２００５／０８９０２４号パンフレット）；塩化鉄（ＩＩＩ）（特開平１１－２５１０６７号公報）、ペルオキソ二硫酸アンモニウム等の高原子価の無機化合物；テトラシアノエチレン等のシアノ化合物；トリス（ペンタフルオロフェニル）ボラン（特開２００３－３１３６５号公報）等の芳香族ホウ素化合物；フラーレン誘導体及びヨウ素等が挙げられる。 Examples of such electron-accepting compounds include triarylboron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of arylamines and metal halides, and salts of arylamines and Lewis acids. Examples thereof include one or more compounds selected from the group. Specifically, onium salts substituted with organic groups such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate and triphenylsulfonium tetrafluoroborate (WO 2005/089024 pamphlet); High-valent inorganic compounds such as iron (III) (Japanese Patent Laid-Open No. 11-251067) and ammonium peroxodisulfate; Cyano compounds such as tetracyanoethylene; Tris (pentafluorophenyl) borane (Japanese Patent Laid-Open No. 2003-31365) Aromatic boron compounds such as: fullerene derivatives and iodine.
＜カチオンラジカル化合物＞
　カチオンラジカル化合物としては、正孔輸送性化合物から一電子取り除いた化学種であるカチオンラジカルと、対アニオンとからなるイオン化合物が好ましい。但し、カチオンラジカルが正孔輸送性の高分子化合物由来である場合、カチオンラジカルは高分子化合物の繰り返し単位から一電子取り除いた構造となる。 <Cation radical compound>
As the cation radical compound, an ionic compound composed of a cation radical which is a chemical species obtained by removing one electron from a hole transporting compound and a counter anion is preferable. However, when the cation radical is derived from a hole transporting polymer compound, the cation radical has a structure in which one electron is removed from the repeating unit of the polymer compound.
　カチオンラジカルとしては、正孔輸送性化合物として前述した化合物から一電子取り除いた化学種であることが好ましい。正孔輸送性化合物として好ましい化合物から一電子取り除いた化学種であることが、非晶質性、可視光の透過率、耐熱性及び溶解性等の点から好適である。 
　ここで、カチオンラジカル化合物は、前述の正孔輸送性化合物と電子受容性化合物を混合することにより生成させることができる。即ち、前述の正孔輸送性化合物と電子受容性化合物とを混合することにより、正孔輸送性化合物から電子受容性化合物へと電子移動が起こり、正孔輸送性化合物のカチオンラジカルと対アニオンとからなるカチオンイオン化合物が生成する。  The cation radical is preferably a chemical species obtained by removing one electron from the compound described above as the hole transporting compound. A chemical species obtained by removing one electron from a compound preferable as a hole transporting compound is preferable in terms of amorphousness, visible light transmittance, heat resistance, solubility, and the like.
Here, the cation radical compound can be generated by mixing the hole transporting compound and the electron accepting compound. That is, by mixing the hole transporting compound and the electron accepting compound, electron transfer occurs from the hole transporting compound to the electron accepting compound, and the cation radical and the counter anion of the hole transporting compound A cation ion compound consisting of
　ＰＥＤＯＴ／ＰＳＳ（Ａｄｖ．Ｍａｔｅｒ．，２０００年，１２巻，４８１頁）やエメラルジン塩酸塩（Ｊ．Ｐｈｙｓ．Ｃｈｅｍ．，１９９０年，９４巻，７７１６頁）等の高分子化合物由来のカチオンラジカル化合物は、酸化重合（脱水素重合）することによっても生成する。
　ここでいう酸化重合は、モノマーを酸性溶液中で、ペルオキソ二硫酸塩等を用いて化学的に、又は、電気化学的に酸化するものである。この酸化重合（脱水素重合）の場合、モノマーが酸化されることにより高分子化されるとともに、酸性溶液由来のアニオンを対アニオンとする、高分子の繰り返し単位から一電子取り除かれたカチオンラジカルが生成する。 Cationic radical compounds derived from polymer compounds such as PEDOT / PSS (Adv. Mater., 2000, 12, 481) and emeraldine hydrochloride (J. Phys. Chem., 1990, 94, 7716) It is also produced by oxidative polymerization (dehydrogenation polymerization).
Oxidative polymerization here refers to oxidation of a monomer chemically or electrochemically with peroxodisulfate in an acidic solution. In the case of this oxidative polymerization (dehydrogenation polymerization), the monomer is polymerized by oxidation, and a cation radical that is removed from the polymer repeating unit by using an anion derived from an acidic solution as a counter anion is removed. Generate.
＜湿式成膜法による正孔注入層３の形成＞
　湿式成膜法により正孔注入層３を形成する場合、通常、正孔注入層３となる材料を可溶な溶剤（正孔注入層用溶剤）と混合して成膜用の組成物（正孔注入層形成用組成物）を調製し、この正孔注入層形成用組成物を正孔注入層３の下層に該当する層（通常は、陽極２）上に塗布して成膜し、乾燥させることにより形成させる。 <Formation of hole injection layer 3 by wet film formation method>
When the hole injection layer 3 is formed by a wet film formation method, a material for forming the hole injection layer 3 is usually mixed with a soluble solvent (hole injection layer solvent) to form a film forming composition (positive Hole injecting layer forming composition) is prepared, and this hole injecting layer forming composition is applied onto a layer corresponding to the lower layer of the hole injecting layer 3 (usually the anode 2) to form a film and dried. To form.
　正孔注入層形成用組成物中における正孔輸送性化合物の濃度は、本発明の効果を著しく損なわない限り任意であるが、膜厚の均一性の点では、低い方が好ましく、また、一方、正孔注入層３に欠陥が生じ難い点では、高い方が好ましい。具体的には、０．０１質量％以上であるのが好ましく、０．１質量％以上であるのが更に好ましく、０．５質量％以上であるのが特に好ましく、また、一方、７０質量％以下であるのが好ましく、６０質量％以下であるのが更に好ましく、５０質量％以下であるのが特に好ましい。 The concentration of the hole transporting compound in the composition for forming a hole injection layer is arbitrary as long as the effects of the present invention are not significantly impaired, but in terms of film thickness uniformity, the lower one is preferable. From the viewpoint that defects are unlikely to occur in the hole injection layer 3, a higher value is preferable. Specifically, it is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, and on the other hand, 70% by mass. The content is preferably less than 60% by mass, more preferably 60% by mass or less, and particularly preferably 50% by mass or less.
　溶剤としては、例えば、エーテル系溶剤、エステル系溶剤、芳香族炭化水素系溶剤、アミド系溶剤等が挙げられる。
　エーテル系溶剤としては、例えば、エチレングリコールジメチルエーテル、エチレングリコールジエチルエーテル、プロピレングリコール－１－モノメチルエーテルアセタート（ＰＧＭＥＡ）等の脂肪族エーテル及び１，２－ジメトキシベンゼン、１，３－ジメトキシベンゼン、アニソール、フェネトール、２－メトキシトルエン、３－メトキシトルエン、４－メトキシトルエン、２，３－ジメチルアニソール、２，４－ジメチルアニソール等の芳香族エーテル等が挙げられる。 Examples of the solvent include ether solvents, ester solvents, aromatic hydrocarbon solvents, amide solvents, and the like.
Examples of ether solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA), 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, and anisole. , Aromatic ethers such as phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole and 2,4-dimethylanisole.
　エステル系溶剤としては、例えば、酢酸フェニル、プロピオン酸フェニル、安息香酸メチル、安息香酸エチル、安息香酸プロピル、安息香酸ｎ－ブチル等の芳香族エステル等が挙げられる。
　芳香族炭化水素系溶剤としては、例えば、トルエン、キシレン、シクロヘキシルベンゼン、３－イソプロピルビフェニル、１，２，３，４－テトラメチルベンゼン、１，４－ジイソプロピルベンゼン、メチルナフタレン等が挙げられる。アミド系溶剤としては、例えば、Ｎ，Ｎ－ジメチルホルムアミド、Ｎ，Ｎ－ジメチルアセトアミド等が挙げられる。 Examples of the ester solvent include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate.
Examples of the aromatic hydrocarbon solvent include toluene, xylene, cyclohexylbenzene, 3-isopropylbiphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, methylnaphthalene and the like. Examples of the amide solvent include N, N-dimethylformamide and N, N-dimethylacetamide.
　これらの他、ジメチルスルホキシド等も用いることができる。
　正孔注入層３の湿式成膜法による形成は、通常、正孔注入層形成用組成物を調製後に、これを、正孔注入層３の下層に該当する層（通常は、陽極２）上に塗布成膜し、乾燥することにより行われる。正孔注入層３は、通常、成膜後に、加熱や減圧乾燥等により塗布膜を乾燥させる。 In addition to these, dimethyl sulfoxide and the like can also be used.
Formation of the hole injection layer 3 by a wet film formation method is usually performed after preparing a composition for forming a hole injection layer, and then forming the composition on a layer (usually the anode 2) corresponding to the lower layer of the hole injection layer 3 The film is formed by coating and drying. In general, the hole injection layer 3 is dried by heating or drying under reduced pressure after film formation.
＜真空蒸着法による正孔注入層３の形成＞
　真空蒸着法により正孔注入層３を形成する場合には、通常、正孔注入層３の構成材料（前述の正孔輸送性化合物、電子受容性化合物等）の１種類又は２種類以上を真空容器内に設置された坩堝に入れ（２種類以上の材料を用いる場合は、通常各々を別々の坩堝に入れ）、真空容器内を真空ポンプで１０－４Ｐａ程度まで排気した後、坩堝を加熱して（２種類以上の材料を用いる場合は、通常各々の坩堝を加熱して）、坩堝内の材料の蒸発量を制御しながら蒸発させ（２種類以上の材料を用いる場合は、通常各々独立に蒸発量を制御しながら蒸発させ）、坩堝に向き合って置かれた基板上の陽極上に正孔注入層３を形成させる。なお、２種類以上の材料を用いる場合は、それらの混合物を坩堝に入れ、加熱、蒸発させて正孔注入層３を形成することもできる。 <Formation of hole injection layer 3 by vacuum deposition>
When the hole injection layer 3 is formed by vacuum vapor deposition, one or more of the constituent materials of the hole injection layer 3 (the above-described hole transporting compound, electron accepting compound, etc.) are usually vacuumed. Put in a crucible installed in the container (if two or more kinds of materials are used, usually put each in separate crucibles), evacuate the vacuum container to about 10 -4 Pa with a vacuum pump, then heat the crucible (When using two or more types of materials, each crucible is usually heated) and evaporated while controlling the amount of evaporation of the material in the crucible (when using two or more types of materials, each is usually independent. The hole injection layer 3 is formed on the anode on the substrate placed facing the crucible. When two or more kinds of materials are used, the hole injection layer 3 can also be formed by putting a mixture thereof in a crucible, heating and evaporating the mixture.
　蒸着時の真空度は、本発明の効果を著しく損なわない限り限定されないが、通常０．１×１０－６Ｔｏｒｒ（０．１３×１０－４Ｐａ）以上、９．０×１０－６Ｔｏｒｒ（１２．０×１０－４Ｐａ）以下である。蒸着速度は、本発明の効果を著しく損なわない限り限定されないが、通常０．１Å／秒以上、５．０Å／秒以下である。蒸着時の成膜温度は、本発明の効果を著しく損なわない限り限定されないが、好ましくは１０℃以上、５０℃以下で行われる。 The degree of vacuum at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 × 10 −6 Torr (0.13 × 10 −4 Pa) or more and 9.0 × 10 −6 Torr ( 12.0 × 10 −4 Pa) or less. The deposition rate is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 to 5.0 liters / second or more. The film forming temperature at the time of vapor deposition is not limited as long as the effects of the present invention are not significantly impaired, but it is preferably performed at 10 ° C. or higher and 50 ° C. or lower.
（正孔輸送層４）
　正孔輸送層４は、陽極側から発光層側に正孔を輸送する機能を担う層である。正孔輸送層４は、本発明の有機電界発光素子では、必須の層では無いが、陽極２から発光層５に正孔を輸送する機能を強化する点では、この層を用いるのが好ましい。正孔輸送層４を用いる場合、通常、正孔輸送層４は、陽極２と発光層５の間に形成される。また、上述の正孔注入層３がある場合は、正孔注入層３と発光層５の間に形成される。 (Hole transport layer 4)
The hole transport layer 4 is a layer having a function of transporting holes from the anode side to the light emitting layer side. The hole transport layer 4 is not an essential layer in the organic electroluminescence device of the present invention, but it is preferable to use this layer in terms of enhancing the function of transporting holes from the anode 2 to the light emitting layer 5. When the hole transport layer 4 is used, the hole transport layer 4 is usually formed between the anode 2 and the light emitting layer 5. Further, when there is the hole injection layer 3 described above, it is formed between the hole injection layer 3 and the light emitting layer 5.
　正孔輸送層４の膜厚は、通常５ｎｍ以上、好ましくは１０ｎｍ以上であり、また、一方、通常３００ｎｍ以下、好ましくは１００ｎｍ以下である。
　正孔輸送層４の形成方法は、真空蒸着法でも、湿式成膜法でもよい。成膜性が優れる点では、湿式成膜法により形成することが好ましい。
　正孔輸送層４は、通常、正孔輸送層４となる正孔輸送性化合物を含有する。正孔輸送層４に含まれる正孔輸送性化合物としては、特に、４，４’－ビス［Ｎ－（１－ナフチル）－Ｎ－フェニルアミノ］ビフェニルで代表される、２個以上の３級アミンを含み２個以上の縮合芳香族環が窒素原子に置換した芳香族ジアミン（特開平５－２３４６８１号公報）、４，４’，４’’－トリス（１－ナフチルフェニルアミノ）トリフェニルアミン等のスターバースト構造を有する芳香族アミン化合物（Ｊ．Ｌｕｍｉｎ．，７２－７４巻、９８５頁、１９９７年）、トリフェニルアミンの四量体から成る芳香族アミン化合物（Ｃｈｅｍ．Ｃｏｍｍｕｎ．，２１７５頁、１９９６年）、２，２’，７，７’－テトラキス－（ジフェニルアミノ）－９，９’－スピロビフルオレン等のスピロ化合物（Ｓｙｎｔｈ．Ｍｅｔａｌｓ，９１巻、２０９頁、１９９７年）、４，４’－Ｎ，Ｎ’－ジカルバゾールビフェニル等のカルバゾール誘導体等が挙げられる。また、例えばポリビニルカルバゾール、ポリビニルトリフェニルアミン（特開平７－５３９５３号公報）、テトラフェニルベンジジンを含有するポリアリーレンエーテルサルホン（Ｐｏｌｙｍ．Ａｄｖ．Ｔｅｃｈ．，７巻、３３頁、１９９６年）等も好ましく使用できる。 The film thickness of the hole transport layer 4 is usually 5 nm or more, preferably 10 nm or more, and is usually 300 nm or less, preferably 100 nm or less.
The formation method of the hole transport layer 4 may be a vacuum deposition method or a wet film formation method. In terms of excellent film forming properties, it is preferable to form the film by a wet film forming method.
The hole transport layer 4 usually contains a hole transport compound that becomes the hole transport layer 4. As the hole transporting compound contained in the hole transporting layer 4, in particular, two or more tertiary compounds represented by 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl are used. Aromatic diamines containing two or more condensed aromatic rings, including amines, substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234811), 4,4 ′, 4 ″ -tris (1-naphthylphenylamino) triphenylamine An aromatic amine compound having a starburst structure (J. Lumin., 72-74, 985, 1997), an aromatic amine compound comprising a tetramer of triphenylamine (Chem. Commun., 2175) 1996), 2,2 ′, 7,7′-tetrakis- (diphenylamino) -9,9′-spirobifluorene and other spiro compounds (Synth. Metals, Vol. 91, 209). Page, 1997), and carbazole derivatives such as 4,4′-N, N′-dicarbazolebiphenyl. Also, for example, polyvinyl carbazole, polyvinyl triphenylamine (Japanese Patent Laid-Open No. 7-53953), polyarylene ether sulfone (Polym. Adv. Tech., 7, 33, 1996) containing tetraphenylbenzidine, etc. It can be preferably used.
＜湿式成膜法による正孔輸送層４の形成＞
　湿式成膜法で正孔輸送層４を形成する場合は、通常、上述の正孔注入層３を湿式成膜法で形成する場合と同様にして、正孔注入層形成用組成物の代わりに正孔輸送層形成用組成物を用いて形成させる。
　湿式成膜法で正孔輸送層４を形成する場合は、通常、正孔輸送層形成用組成物は、更に溶剤を含有する。正孔輸送層形成用組成物に用いる溶剤は、上述の正孔注入層形成用組成物で用いる溶剤と同様の溶剤を使用することができる。
　正孔輸送層形成用組成物中における正孔輸送性化合物の濃度は、正孔注入層形成用組成物中における正孔輸送性化合物の濃度と同様の範囲とすることができる。
　正孔輸送層４の湿式成膜法による形成は、前述の正孔注入層３の成膜法と同様に行うことができる。 <Formation of hole transport layer 4 by wet film formation method>
When the hole transport layer 4 is formed by a wet film formation method, the hole injection layer 3 is usually replaced with the hole injection layer forming composition in the same manner as in the case of forming the hole injection layer 3 by a wet film formation method. It forms using the composition for positive hole transport layer formation.
When the hole transport layer 4 is formed by a wet film formation method, the composition for forming a hole transport layer usually further contains a solvent. As the solvent used in the composition for forming a hole transport layer, the same solvent as the solvent used in the composition for forming a hole injection layer can be used.
The concentration of the hole transporting compound in the composition for forming a hole transport layer can be in the same range as the concentration of the hole transporting compound in the composition for forming a hole injection layer.
Formation of the hole transport layer 4 by a wet film formation method can be performed in the same manner as the film formation method of the hole injection layer 3 described above.
＜真空蒸着法による正孔輸送層４の形成＞
　真空蒸着法で正孔輸送層４を形成する場合についても、通常、上述の正孔注入層３を真空蒸着法で形成する場合と同様にして、正孔注入層形成用組成物の代わりに正孔輸送層形成用組成物を用いて形成させることができる。蒸着時の真空度、蒸着速度及び温度等の成膜条件等は、前記正孔注入層３の真空蒸着時と同様の条件で成膜することができる。 <Formation of hole transport layer 4 by vacuum deposition>
Also in the case of forming the hole transport layer 4 by the vacuum deposition method, the positive hole injection layer 3 is usually formed in place of the composition for forming the hole injection layer in the same manner as in the case of forming the hole injection layer 3 by the vacuum deposition method. It can be formed using a composition for forming a hole transport layer. Film formation conditions such as the degree of vacuum at the time of vapor deposition, the vapor deposition rate, and the temperature can be formed under the same conditions as those for the vacuum vapor deposition of the hole injection layer 3.
　（発光層５）
　発光層５は、一対の電極間に電界が与えられた時に、陽極２から注入される正孔と陰極９から注入される電子が再結合することにより励起され、発光する機能を担う層である。発光層５は、陽極２と陰極９の間に形成される層であり、発光層５は、陽極２の上に正孔注入層３がある場合は、正孔注入層３と陰極９の間に形成され、陽極２の上に正孔輸送層４がある場合は、正孔輸送層４と陰極９との間に形成される。 (Light emitting layer 5)
The light emitting layer 5 is a layer having a function of emitting light when excited by recombination of holes injected from the anode 2 and electrons injected from the cathode 9 when an electric field is applied between a pair of electrodes. . The light emitting layer 5 is a layer formed between the anode 2 and the cathode 9, and the light emitting layer 5 is provided between the hole injection layer 3 and the cathode 9 when the hole injection layer 3 is on the anode 2. In the case where the hole transport layer 4 is formed on the anode 2, it is formed between the hole transport layer 4 and the cathode 9.
　発光層５の膜厚は本発明の効果を著しく損なわない限り任意であるが、膜に欠陥が生じ難い点では厚いことが好ましいが、また、一方で、駆動電圧が低くなりやすい点では薄いことが好ましい。具体的には、通常３ｎｍ以上、好ましくは５ｎｍ以上、また、通常２００ｎｍ以下、好ましくは１００ｎｍ以下の範囲であるのがよい。
　なお、有機電界発光素子には、発光層は２層以上設けてもかまわない。
　発光層５の詳細については、前述の通りである。
　本発明に係る発光層以外の発光層を真空蒸着法で形成する場合は次のように形成する。 The thickness of the light-emitting layer 5 is arbitrary as long as the effects of the present invention are not significantly impaired. However, it is preferable that the thickness of the light-emitting layer 5 is small in that it is difficult to cause defects in the film. Is preferred. Specifically, the thickness is usually 3 nm or more, preferably 5 nm or more, and usually 200 nm or less, preferably 100 nm or less.
In the organic electroluminescent element, two or more light emitting layers may be provided.
The details of the light emitting layer 5 are as described above.
When forming light emitting layers other than the light emitting layer based on this invention by a vacuum evaporation method, it forms as follows.
＜真空蒸着法による発光層の形成方法＞
　真空蒸着法により発光層を形成する場合には、通常、発光層の構成材料（前述の発光材料、非発光材料等）を、各々真空容器内に設置された別々の坩堝に入れ、真空容器内を真空ポンプで１０－４Ｐａ程度まで排気した後、各坩堝を加熱して、各坩堝内の材料の蒸発量を独立に制御しながら蒸発させ、各坩堝に向き合って置かれた基板等の上に発光層を形成させる。なお、構成材料の混合物を１つの坩堝に入れ、加熱、蒸発させて発光層を形成することもできる。 <Method of forming light emitting layer by vacuum deposition>
When forming a light emitting layer by a vacuum deposition method, the constituent materials of the light emitting layer (the aforementioned light emitting material, non-light emitting material, etc.) are usually placed in separate crucibles installed in the vacuum container, Is evacuated to about 10 −4 Pa with a vacuum pump, and each crucible is heated to evaporate while independently controlling the evaporation amount of the material in each crucible, and on the substrate or the like placed facing each crucible. To form a light emitting layer. Note that the light-emitting layer can also be formed by placing a mixture of constituent materials in one crucible and heating and evaporating the mixture.
　蒸着時の真空度は、本発明の効果を著しく損なわない限り限定されないが、通常０．１×１０－６Ｔｏｒｒ（０．１３×１０－４Ｐａ）以上、９．０×１０－６Ｔｏｒｒ（１２．０×１０－４Ｐａ）以下である。蒸着速度は、本発明の効果を著しく損なわない限り限定されないが、通常０．１Å／秒以上、５．０Å／秒以下である。蒸着時の成膜温度は、本発明の効果を著しく損なわない限り限定されないが、好ましくは１０℃以上、５０℃以下で行われる。 The degree of vacuum at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 × 10 −6 Torr (0.13 × 10 −4 Pa) or more and 9.0 × 10 −6 Torr ( 12.0 × 10 −4 Pa) or less. The deposition rate is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 to 5.0 liters / second or more. The film forming temperature at the time of vapor deposition is not limited as long as the effects of the present invention are not significantly impaired, but it is preferably performed at 10 ° C. or higher and 50 ° C. or lower.
（正孔阻止層６）
　発光層５と後述の電子注入層８との間に、正孔阻止層６を設けてもよい。正孔阻止層６は、発光層５の上に、発光層５の陰極側の界面に接するように積層される層である。
　この正孔阻止層６は、陽極２から移動してくる正孔を陰極９に到達するのを阻止する役割と、陰極９から注入された電子を効率よく発光層５の方向に輸送する役割とを有する。正孔阻止層６を構成する材料に求められる物性としては、電子移動度が高く正孔移動度が低いこと、エネルギーギャップ（ＨＯＭＯ、ＬＵＭＯの差）が大きいこと、励起三重項準位（Ｔ１）が高いことが挙げられる。 (Hole blocking layer 6)
A hole blocking layer 6 may be provided between the light emitting layer 5 and an electron injection layer 8 described later. The hole blocking layer 6 is a layer stacked on the light emitting layer 5 so as to be in contact with the cathode side interface of the light emitting layer 5.
The hole blocking layer 6 has a role of blocking holes moving from the anode 2 from reaching the cathode 9 and a role of efficiently transporting electrons injected from the cathode 9 toward the light emitting layer 5. Have The physical properties required for the material constituting the hole blocking layer 6 include high electron mobility, low hole mobility, a large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). Is high.
　このような条件を満たす正孔阻止層６の材料としては、例えば、ビス（２－メチル－８－キノリノラト）（フェノラト）アルミニウム、ビス（２－メチル－８－キノリノラト）（トリフェニルシラノラト）アルミニウム等の混合配位子錯体、ビス（２－メチル－８－キノラト）アルミニウム－μ－オキソ－ビス－（２－メチル－８－キノリノラト）アルミニウム二核金属錯体等の金属錯体、ジスチリルビフェニル誘導体等のスチリル化合物（特開平１１－２４２９９６号公報）、３－（４－ビフェニルイル）－４－フェニル－５（４－ｔｅｒｔ－ブチルフェニル）－１，２，４－トリアゾール等のトリアゾール誘導体（特開平７－４１７５９号公報）、バソクプロイン等のフェナントロリン誘導体（特開平１０－７９２９７号公報）等が挙げられる。更に、国際公開第２００５／０２２９６２号パンフレットに記載の２，４，６位が置換されたピリジン環を少なくとも１個有する化合物も、正孔阻止層６の材料として好ましい。 Examples of the material of the hole blocking layer 6 satisfying such conditions include bis (2-methyl-8-quinolinolato) (phenolato) aluminum, bis (2-methyl-8-quinolinolato) (triphenylsilanolato) aluminum. Mixed ligand complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolinolato) aluminum binuclear metal complexes, distyrylbiphenyl derivatives, etc. Styryl compounds (Japanese Patent Laid-Open No. 11-242996), triazole derivatives such as 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4-triazole (Japanese Patent Laid-Open No. 7-41759), phenanthroline derivatives such as bathocuproine (Japanese Patent Laid-Open No. 10-79297), and the like. It is. Further, a compound having at least one pyridine ring substituted at the 2,4,6-positions described in International Publication No. 2005/022962 is also preferable as the material of the hole blocking layer 6.
　正孔阻止層６の形成方法に制限はなく、前述の発光層５の形成方法と同様にして形成することができる。
　正孔阻止層６の膜厚は、本発明の効果を著しく損なわない限り任意であるが、通常０．３ｎｍ以上、好ましくは０．５ｎｍ以上であり、また、通常１００ｎｍ以下、好ましくは５０ｎｍ以下である。 There is no restriction | limiting in the formation method of the hole-blocking layer 6, It can form similarly to the formation method of the above-mentioned light emitting layer 5. FIG.
The thickness of the hole blocking layer 6 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less. is there.
（電子輸送層７）
　電子輸送層７は素子の電流効率をさらに向上させることを目的として、発光層５と電子注入層８との間に設けられる。
　電子輸送層７は、電界を与えられた電極間において、陰極９又は電子注入層８から電子を効率よく注入し、発光層５の方向に電子を効率よく輸送することができる化合物より形成される。
　電子輸送層７に用いられる電子輸送性化合物としては、通常、陰極９又は電子注入層８からの電子注入効率が高く、注入された電子を効率よく輸送できる化合物が好ましい。電子輸送性化合物としては、具体的には、例えば、８－ヒドロキシキノリンのアルミニウム錯体等の金属錯体（特開昭５９－１９４３９３号公報）、１０－ヒドロキシベンゾ［ｈ］キノリンの金属錯体、オキサジアゾール誘導体、ジスチリルビフェニル誘導体、シロール誘導体、３－ヒドロキシフラボン金属錯体、５－ヒドロキシフラボン金属錯体、ベンズオキサゾール金属錯体、ベンゾチアゾール金属錯体、トリスベンズイミダゾリルベンゼン（米国特許第５６４５９４８号明細書）、キノキサリン化合物（特開平６－２０７１６９号公報）、フェナントロリン誘導体（特開平５－３３１４５９号公報）、２－ｔ－ブチル－９，１０－Ｎ，Ｎ’－ジシアノアントラキノンジイミン、ｎ型水素化非晶質炭化シリコン、ｎ型硫化亜鉛、ｎ型セレン化亜鉛等が挙げられる。
　電子輸送層７の膜厚は、通常１ｎｍ以上、好ましくは５ｎｍ以上であり、また、一方、通常３００ｎｍ以下、好ましくは１００ｎｍ以下である。
　電子輸送層７は、前記と同様にして湿式成膜法、或いは真空蒸着法により正孔阻止層６上に積層することにより形成される。通常は、真空蒸着法が用いられる。 (Electron transport layer 7)
The electron transport layer 7 is provided between the light emitting layer 5 and the electron injection layer 8 for the purpose of further improving the current efficiency of the device.
The electron transport layer 7 is formed of a compound capable of efficiently injecting electrons from the cathode 9 or the electron injection layer 8 between the electrodes to which an electric field is applied, and efficiently transporting electrons in the direction of the light emitting layer 5. .
As the electron transporting compound used for the electron transporting layer 7, a compound that has high electron injection efficiency from the cathode 9 or the electron injection layer 8 and can efficiently transport the injected electrons is usually preferable. Specific examples of the electron transporting compound include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline, oxadi Azole derivatives, distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline Compound (JP-A-6-207169), phenanthroline derivative (JP-A-5-331459), 2-t-butyl-9,10-N, N′-dicyanoanthraquinonediimine, n-type hydrogenated amorphous Silicon carbide, n-type zinc sulfide, n-type selenium Zinc halide etc. are mentioned.
The thickness of the electron transport layer 7 is usually 1 nm or more, preferably 5 nm or more, and is usually 300 nm or less, preferably 100 nm or less.
The electron transport layer 7 is formed by laminating on the hole blocking layer 6 by a wet film formation method or a vacuum deposition method in the same manner as described above. Usually, a vacuum deposition method is used.
（電子注入層８）
　陰極９と電子輸送層７又は発光層５の間に電子注入層８を設けてもよい。電子注入層８は、陰極９から注入された電子を効率よく、電子輸送層７又は発光層５へ注入する役割を果たす。
　電子注入を効率よく行うには、電子注入層８を形成する材料は、仕事関数の低い金属が好ましい。例としては、ナトリウムやセシウム等のアルカリ金属、バリウムやカルシウム等のアルカリ土類金属等が用いられる。その膜厚は通常０．１ｎｍ以上、５ｎｍ以下が好ましい。 (Electron injection layer 8)
An electron injection layer 8 may be provided between the cathode 9 and the electron transport layer 7 or the light emitting layer 5. The electron injection layer 8 plays a role of efficiently injecting electrons injected from the cathode 9 into the electron transport layer 7 or the light emitting layer 5.
In order to perform electron injection efficiently, the material for forming the electron injection layer 8 is preferably a metal having a low work function. Examples include alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium. The film thickness is usually preferably from 0.1 nm to 5 nm.
　更に、バソフェナントロリン等の含窒素複素環化合物や８－ヒドロキシキノリンのアルミニウム錯体等の金属錯体に代表される有機電子輸送材料に、ナトリウム、カリウム、セシウム、リチウム、ルビジウム等のアルカリ金属をドープする（特開平１０－２７０１７１号公報、特開２００２－１００４７８号公報、特開２００２－１００４８２号公報等に記載）ことも、電子注入・輸送性が向上し優れた膜質を両立させることが可能となるため好ましい。 Furthermore, an organic electron transport material represented by a metal complex such as a nitrogen-containing heterocyclic compound such as bathophenanthroline or an aluminum complex of 8-hydroxyquinoline is doped with an alkali metal such as sodium, potassium, cesium, lithium, rubidium ( (Described in JP-A-10-270171, JP-A-2002-1000047, JP-A-2002-1000048, etc.) also improves electron injection / transport and makes it possible to achieve both excellent film quality. preferable.
　膜厚は通常、５ｎｍ以上、好ましくは１０ｎｍ以上、また、通常２００ｎｍ以下、好ましくは１００ｎｍ以下の範囲である。
　電子注入層８は、湿式成膜法或いは真空蒸着法により、発光層５又はその上の正孔阻止層上に積層することにより形成される。
湿式成膜法の場合の詳細は、前述の発光層５の場合と同様である。 The film thickness is usually in the range of 5 nm or more, preferably 10 nm or more, and usually 200 nm or less, preferably 100 nm or less.
The electron injection layer 8 is formed by laminating on the light emitting layer 5 or the hole blocking layer thereon by a wet film formation method or a vacuum deposition method.
The details of the wet film forming method are the same as those of the light emitting layer 5 described above.
（陰極９）
　陰極９は、発光層側の層（電子注入層８又は発光層５等）に電子を注入する役割を果たす。陰極９の材料としては、前記の陽極２に使用される材料を用いることが可能であるが、効率良く電子注入を行なう上では、仕事関数の低い金属を用いることが好ましく、例えば、スズ、マグネシウム、インジウム、カルシウム、アルミニウム、銀等の金属又はそれらの合金等が用いられる。具体例としては、例えば、マグネシウム－銀合金、マグネシウム－インジウム合金、アルミニウム－リチウム合金等の低仕事関数の合金電極等が挙げられる。 (Cathode 9)
The cathode 9 plays a role of injecting electrons into a layer on the light emitting layer side (such as the electron injection layer 8 or the light emitting layer 5). As the material of the cathode 9, the material used for the anode 2 can be used. However, in order to perform electron injection efficiently, it is preferable to use a metal having a low work function. , Metals such as indium, calcium, aluminum and silver, or alloys thereof. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.
　素子の安定性の点では、陰極９の上に、仕事関数が高く、大気に対して安定な金属層を積層して、低仕事関数の金属からなる陰極９を保護するのが好ましい。積層する金属としては、例えば、アルミニウム、銀、銅、ニッケル、クロム、金、白金等の金属が挙げられる。
　陰極の膜厚は通常、陽極２と同様である。 In terms of device stability, it is preferable to protect the cathode 9 made of a metal having a low work function by laminating a metal layer having a high work function and stable to the atmosphere on the cathode 9. Examples of the metal to be laminated include metals such as aluminum, silver, copper, nickel, chromium, gold, and platinum.
The thickness of the cathode is usually the same as that of the anode 2.
（その他の層）
　本発明の有機電界発光素子は、本発明の効果を著しく損なわなければ、更に他の層を有していてもよい。すなわち、陽極２と陰極９との間に、上述の他の任意の層を有していてもよい。 (Other layers)
The organic electroluminescent element of the present invention may further have other layers as long as the effects of the present invention are not significantly impaired. In other words, any other layer described above may be provided between the anode 2 and the cathode 9.
＜その他の素子構成＞
　上述の説明とは逆の構造、即ち、基板上に陰極、電子注入層、発光層、正孔注入層、陽極の順に積層することも可能である。 <Other element configuration>
The structure opposite to that described above, that is, a cathode, an electron injection layer, a light emitting layer, a hole injection layer, and an anode can be stacked in this order on the substrate.
　次に、本発明を実施例によって更に具体的に説明するが、本発明はその要旨を超えない限り、以下の実施例の記載に限定されるものではない。 Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the description of the following examples unless it exceeds the gist.
（実施例１）
　図１に示す構成の有機電界発光素子を作製した。 Example 1
An organic electroluminescent element having the configuration shown in FIG. 1 was produced.
＜陽極＞
　ガラス製の基板１上に、インジウム・スズ酸化物（ＩＴＯ）透明導電膜を厚さ７０ｎｍに成膜したもの（スパッタ成膜品、シート抵抗１５Ω）を通常のフォトリソグラフィ技術により２ｍｍ幅のストライプにパターニングして陽極２を形成した。陽極２を形成した基板１（ＩＴＯ基板）を、純水による超音波洗浄、純水による水洗の順で洗浄後、窒素ブローで乾燥させ、最後に紫外線オゾン洗浄の処理を行った。 <Anode>
An indium tin oxide (ITO) transparent conductive film formed on a glass substrate 1 with a thickness of 70 nm (sputtered film, sheet resistance 15Ω) is formed into a 2 mm wide stripe by a normal photolithography technique. The anode 2 was formed by patterning. The substrate 1 (ITO substrate) on which the anode 2 was formed was cleaned in the order of ultrasonic cleaning with pure water and then with pure water, dried by nitrogen blowing, and finally subjected to ultraviolet ozone cleaning.
＜正孔注入層＞
　次いで、正孔注入層３を以下のように湿式成膜法によって形成した。
　正孔輸送性化合物として、下記式（Ｐ１）で表される繰り返し構造を有する高分子化合物（重量平均分子量　５２０００）を２．０質量％、電子受容性化合物として４－イソプロピル－４’－メチルジフェニルヨードニウムテトラキス（ペンタフルオロフェニル）ボラートを０．４質量％、安息香酸エチルに溶解させた正孔注入層形成用組成物を調製し、この正孔注入層形成用組成物を、前記ＩＴＯ基板上にスピンコート法により成膜し、さらに加熱乾燥することにより、膜厚３２ｎｍの正孔注入層３を形成した。成膜条件は以下の通りであった。 <Hole injection layer>
Next, the hole injection layer 3 was formed by a wet film formation method as follows.
As a hole-transporting compound, 2.0% by mass of a polymer compound having a repeating structure represented by the following formula (P1) (weight average molecular weight 52000) and 4-isopropyl-4′-methyldiphenyl as an electron-accepting compound A composition for forming a hole injection layer in which 0.4% by mass of iodonium tetrakis (pentafluorophenyl) borate and ethyl benzoate were dissolved was prepared, and this composition for forming a hole injection layer was formed on the ITO substrate. A hole injection layer 3 having a film thickness of 32 nm was formed by film formation by spin coating and further heat drying. The film forming conditions were as follows.
＜成膜条件＞
　スピンコート条件：スピナ回転数５００ｒｐｍ／２秒　→２１００ｒｐｍ／３０秒
　加熱乾燥条件：２３０℃のクリーンオーブン内に１時間放置　 <Film formation conditions>
Spin coating conditions: Spinner rotation speed 500 rpm / 2 seconds → 2100 rpm / 30 seconds Heating drying conditions: Leave in a clean oven at 230 ° C. for 1 hour
Figure JPOXMLDOC01-appb-C000008
Figure JPOXMLDOC01-appb-C000008
＜正孔輸送層＞
　次いで、形成された正孔注入層３上に、以下の通り、湿式成膜法によって正孔輸送層４を形成した。
　架橋性化合物として、以下に示す繰り返し構造の高分子化合物（ＨＴ－１）（重量平均分子量：５３０００）を溶剤としてシクロヘキシルベンゼンに溶解させて正孔輸送層形成用組成物を調製した。該正孔輸送層形成用組成物における、該高分子化合物（ＨＴ－１）の濃度は２．０質量％であった。 <Hole transport layer>
Next, a hole transport layer 4 was formed on the formed hole injection layer 3 by a wet film forming method as follows.
As the crosslinkable compound, a polymer compound (HT-1) having a repeating structure shown below (weight average molecular weight: 53000) was dissolved in cyclohexylbenzene as a solvent to prepare a composition for forming a hole transport layer. The concentration of the polymer compound (HT-1) in the composition for forming a hole transport layer was 2.0% by mass.
Figure JPOXMLDOC01-appb-C000009
Figure JPOXMLDOC01-appb-C000009
　該正孔輸送層形成用組成物を、正孔注入層３上にスピンコート法により成膜し、さらに加熱乾燥することにより、該高分子化合物（ＨＴ－１）を架橋反応させて硬化させ、膜厚２１ｎｍの正孔輸送層４を形成した。成膜条件は以下の通りであった。
＜成膜条件＞
　スピンコート条件：スピナ回転数５００ｒｐｍ／２秒　→２９００ｒｐｍ／１２０秒
　加熱乾燥条件：２３０℃のホットプレート上に１時間放置 The composition for forming a hole transport layer is formed on the hole injection layer 3 by a spin coat method, and further heated and dried to cause the polymer compound (HT-1) to undergo a crosslinking reaction to be cured, A hole transport layer 4 having a thickness of 21 nm was formed. The film forming conditions were as follows.
<Film formation conditions>
Spin coating conditions: Spinner rotation speed 500 rpm / 2 seconds → 2900 rpm / 120 seconds Heat drying conditions: Leave on a hot plate at 230 ° C. for 1 hour
＜発光層＞
　次いで、形成された正孔輸送層４上に、以下の通り、発光層５を形成した。　以下に示す化合物（ＨＨ－１）、（ＨＨ－２）、（Ｈ－１）、（ＬＨ－１）及び（Ｄ－１）を、３５：２０：３５：１０：１５の質量比で混合し、この混合物が３．４５質量％となるようキシレンに溶解させた発光層形成用組成物を調製し、この発光層形成用組成物を窒素雰囲気下で、前記正孔輸送層４上にスピンコート法により成膜し、さらに加熱乾燥することにより、膜厚５９ｎｍの発光層５を形成した。成膜条件は以下の通りであった。 <Light emitting layer>
Next, the light emitting layer 5 was formed on the formed hole transport layer 4 as follows. The following compounds (HH-1), (HH-2), (H-1), (LH-1) and (D-1) were mixed at a mass ratio of 35: 20: 35: 10: 15. A composition for forming a light emitting layer in which xylene was dissolved in xylene so that the mixture was 3.45% by mass was prepared, and the composition for forming a light emitting layer was spin-coated on the hole transport layer 4 in a nitrogen atmosphere. The light emitting layer 5 having a film thickness of 59 nm was formed by forming a film by the method and further drying by heating. The film forming conditions were as follows.
＜成膜条件＞
　スピンコート条件：スピナ回転数５００ｒｐｍ／２秒　→１７００ｒｐｍ／１２０秒
加熱乾燥条件：１２０℃のホットプレート上に２０分放置　 <Film formation conditions>
Spin coating conditions: Spinner rotation speed 500 rpm / 2 seconds → 1700 rpm / 120 seconds Heating drying conditions: Standing on a hot plate at 120 ° C. for 20 minutes
Figure JPOXMLDOC01-appb-C000010
Figure JPOXMLDOC01-appb-C000010
Figure JPOXMLDOC01-appb-C000011
  
Figure JPOXMLDOC01-appb-C000011
  
Figure JPOXMLDOC01-appb-C000012
Figure JPOXMLDOC01-appb-C000012
Figure JPOXMLDOC01-appb-C000013
Figure JPOXMLDOC01-appb-C000013
Figure JPOXMLDOC01-appb-C000014
Figure JPOXMLDOC01-appb-C000014
　なお、上記化合物（ＨＨ－１）、（ＨＨ－２）、（Ｈ－１）及び（ＬＨ－１）のＴｇは、それぞれ１５９℃、１４２℃、１１３℃及び９０℃であり、かつ非発光材料であることから、（ＨＨ－１）と（ＨＨ－２）が本発明の高Ｔｇ化合物に相当し、（ＬＨ－１）が本発明の低Ｔｇ化合物に相当する。低Ｔｇ化合物である（ＬＨ－１）がピリミジン骨格を有し、かつ単環化合物同士が直接結合及び／又は連結基を介して、結合した化合物となっている。
　各化合物の分子量は、（ＨＨ－１）、（ＨＨ－２）、（Ｈ－１）、（ＬＨ－１）及び（Ｄ－１）がそれぞれ９６８．４、８６６．３、６３６．３、８４１．４及び１３６３．９であり、いずれも分子量５０００以下であった。また、発光層形成用組成物に含まれる全非発光材料の総量に対する低Ｔｇ化合物の含有率は１０質量％で、全非発光材料の加重平均ガラス転移温度は１３３℃であった。 The compounds (HH-1), (HH-2), (H-1) and (LH-1) have Tg of 159 ° C., 142 ° C., 113 ° C. and 90 ° C., respectively, and non-light emitting materials Therefore, (HH-1) and (HH-2) correspond to the high Tg compound of the present invention, and (LH-1) corresponds to the low Tg compound of the present invention. The low Tg compound (LH-1) has a pyrimidine skeleton, and monocyclic compounds are bonded to each other through a direct bond and / or a linking group.
The molecular weight of each compound is 968.4, 866.3, 636.3, 841 for (HH-1), (HH-2), (H-1), (LH-1) and (D-1), respectively. 4 and 1363.9, both of which had a molecular weight of 5000 or less. Moreover, the content rate of the low Tg compound with respect to the total amount of all the nonluminous materials contained in the composition for light emitting layer formation was 10 mass%, and the weighted average glass transition temperature of all the nonluminous materials was 133 degreeC.
＜正孔阻止層＞
　次いで、形成された発光層５上に、真空蒸着法により正孔阻止層６として以下に示す化合物（ＨＢ－１）を膜厚１０ｎｍとなるように形成した。 <Hole blocking layer>
Next, a compound (HB-1) shown below was formed as a hole blocking layer 6 on the formed light emitting layer 5 by a vacuum deposition method so as to have a film thickness of 10 nm.
Figure JPOXMLDOC01-appb-C000015
Figure JPOXMLDOC01-appb-C000015
　＜電子輸送層＞
　次いで、形成された正孔阻止層６上に、真空蒸着法により電子輸送層７として以下に示す化合物（ＥＴ－１）を膜厚２０ｎｍとなるように形成した。 <Electron transport layer>
Next, a compound (ET-1) shown below as an electron transport layer 7 was formed on the formed hole blocking layer 6 by a vacuum deposition method so as to have a film thickness of 20 nm.
Figure JPOXMLDOC01-appb-C000016
Figure JPOXMLDOC01-appb-C000016
＜電子注入層・陰極＞
　ここで、電子輸送層７までの蒸着を行った素子を、一度、前記真空蒸着装置内より大気中に取り出して、陰極蒸着用のマスクとして、陽極であるＩＴＯストライプと直交する形状の２ｍｍ幅のストライプ状シャドーマスクを素子に密着させ、別の真空蒸着装置内に設置して、電子輸送層７と同様の真空蒸着法により、電子注入層８としてフッ化リチウム（ＬｉＦ）を膜厚０．５ｎｍ、次いで陰極９としてアルミニウムを膜厚８０．０ｎｍとなるようにそれぞれ積層した。 <Electron injection layer / cathode>
Here, the element that has been vapor-deposited up to the electron transport layer 7 is once taken out from the vacuum vapor deposition apparatus into the atmosphere, and used as a cathode vapor deposition mask with a 2 mm width in a shape orthogonal to the ITO stripe as the anode. A stripe shadow mask is brought into close contact with the element, placed in another vacuum vapor deposition apparatus, and lithium fluoride (LiF) is formed to a thickness of 0.5 nm as the electron injection layer 8 by the same vacuum vapor deposition method as the electron transport layer 7. Subsequently, aluminum was laminated as the cathode 9 so as to have a film thickness of 80.0 nm.
＜封止＞
　引き続き、素子が保存中に大気中の水分等で劣化することを防ぐため、以下に記載の方法で封止処理を行った。
　真空蒸着装置に連結された窒素グローブボックス中で、２３ｍｍ×２３ｍｍサイズのガラス板の外周部に、約１ｍｍの幅で光硬化性樹脂を塗布し、中央部に水分ゲッターシートを設置した。この上に、陰極形成を終了した基板を、蒸着された面が乾燥剤シートと対向するように貼り合わせた。その後、光硬化性樹脂が塗布された領域のみに紫外光を照射し、樹脂を硬化させた。これにより、２ｍｍ×２ｍｍサイズの発光面積部分を有する有機電界発光素子が得られた。 <Sealing>
Subsequently, in order to prevent the element from being deteriorated by moisture in the atmosphere during storage, sealing treatment was performed by the method described below.
In a nitrogen glove box connected to a vacuum deposition apparatus, a photocurable resin was applied to the outer periphery of a 23 mm × 23 mm size glass plate with a width of about 1 mm, and a moisture getter sheet was installed in the center. On this, the board | substrate which complete | finished cathode formation was bonded together so that the vapor-deposited surface might oppose a desiccant sheet. Then, only the area | region where the photocurable resin was apply | coated was irradiated with ultraviolet light, and resin was hardened. Thereby, the organic electroluminescent element which has a light emission area part of 2 mm x 2 mm size was obtained.
　（実施例２）
　実施例１において、発光層形成用組成物に含まれる非発光材料及び発光材料として、化合物（ＨＨ－２）、（ＬＨ－１）、（ＬＨ－２）、（Ｈ－１）及び（Ｄ－１）を、１５：１５：１５：５５：１５の質量比で混合したものに変更したこと以外は実施例１と同様に有機電界発光素子を作製した。なお、化合物（ＬＨ－２）は以下に示す構造を有する化合物であり、Ｔｇは８７℃であり、分子量は７６２．３であった。また、発光層形成用組成物に含まれる全非発光材料の総量に対する低Ｔｇ化合物の含有率は３０質量％であり、全非発光材料の加重平均ガラス転移温度は１１０℃であった。 (Example 2)
In Example 1, the compounds (HH-2), (LH-1), (LH-2), (H-1) and (D-) are used as the non-light emitting material and the light emitting material contained in the light emitting layer forming composition. An organic electroluminescent element was produced in the same manner as in Example 1 except that 1) was changed to a mixture of 15: 15: 15: 55: 15 at a mass ratio. Compound (LH-2) was a compound having the structure shown below, Tg was 87 ° C., and molecular weight was 762.3. Moreover, the content rate of the low Tg compound with respect to the total amount of all the nonluminous materials contained in the composition for light emitting layer formation was 30 mass%, and the weighted average glass transition temperature of all the nonluminous materials was 110 degreeC.
Figure JPOXMLDOC01-appb-C000017
Figure JPOXMLDOC01-appb-C000017
　（実施例３）
実施例１において、発光層形成用組成物に含まれる非発光材料及び発光材料として、化合物（ＨＨ－１）、（Ｈ－２）、（Ｈ－３）、（ＬＨ－１）及び（Ｄ－１）を、３５：１５：３５：１５：１５の質量比で混合したものに変更したこと以外は実施例１と同様に有機電界発光素子を作製した。なお、化合物（Ｈ－２）及び（Ｈ－３）は以下に示す構造を有する化合物であり、Ｔｇはそれぞれ１２９℃、１０９℃であり、分子量はそれぞれ７９１．３及び１１５７．５及びであった。発光層形成用組成物に含まれる全非発光材料の総量に対する低Ｔｇ化合物の含有率は１５質量％であり、全非発光材料の加重平均ガラス転移温度は１２７℃であった。 (Example 3)
In Example 1, compounds (HH-1), (H-2), (H-3), (LH-1) and (D-) are used as the non-light-emitting materials and the light-emitting materials contained in the composition for forming a light-emitting layer. An organic electroluminescent element was produced in the same manner as in Example 1 except that 1) was changed to a mixture of 35: 15: 35: 15: 15 at a mass ratio. Compounds (H-2) and (H-3) are compounds having the following structures, Tg was 129 ° C. and 109 ° C., respectively, and molecular weights were 791.3 and 1157.5, respectively. . The content rate of the low Tg compound with respect to the total amount of all the non-light-emitting materials contained in the composition for forming a light-emitting layer was 15% by mass, and the weighted average glass transition temperature of all the non-light-emitting materials was 127 ° C.
Figure JPOXMLDOC01-appb-C000018
Figure JPOXMLDOC01-appb-C000018
Figure JPOXMLDOC01-appb-C000019
Figure JPOXMLDOC01-appb-C000019
　（実施例４）
　実施例１において、発光層形成用組成物に含まれる非発光材料及び発光材料として、化合物（ＨＨ－１）、（ＬＨ－１）及び（Ｄ－１）を、７０：３０：１５の質量比で混合したものに変更したこと以外は実施例１と同様に有機電界発光素子を作製した。発光層形成用組成物に含まれる全非発光材料の総量に対する低Ｔｇ化合物の含有率は３０質量％であり、全非発光材料の加重平均ガラス転移温度は１３８℃であった。 Example 4
In Example 1, as a non-light-emitting material and a light-emitting material contained in the composition for forming a light-emitting layer, the compounds (HH-1), (LH-1) and (D-1) were mixed at a mass ratio of 70:30:15. An organic electroluminescent element was produced in the same manner as in Example 1 except that the mixture was changed to that mixed in the above. The content rate of the low Tg compound with respect to the total amount of all non-light-emitting materials contained in the composition for forming a light-emitting layer was 30% by mass, and the weighted average glass transition temperature of all the non-light-emitting materials was 138 ° C.
　（実施例５）
　実施例１において、発光層形成用組成物に含まれる非発光材料及び発光材料として、（ＨＨ－１）、（Ｈ－２）、（ＬＨ－１）及び（Ｄ－１）を、７０：１５：１５：１５の質量比で混合したものに変更したこと以外は実施例１と同様に有機電界発光素子を作製した。発光層形成用組成物に含まれる全非発光材料の総量に対する低Ｔｇ化合物の含有率は１５質量％であり、全非発光材料の加重平均ガラス転移温度は１４４℃であった。
あった。 (Example 5)
In Example 1, (HH-1), (H-2), (LH-1), and (D-1) were used as the non-light-emitting material and the light-emitting material included in the composition for forming a light-emitting layer. An organic electroluminescent element was produced in the same manner as in Example 1 except that the mixture was changed to a mixture with a mass ratio of 15:15. The content rate of the low Tg compound with respect to the total amount of all the non-light-emitting materials contained in the composition for forming a light-emitting layer was 15% by mass, and the weighted average glass transition temperature of all the non-light-emitting materials was 144 ° C.
there were.
　（実施例６）
　実施例１において、発光層形成用組成物に含まれる非発光材料及び発光材料として、（ＨＨ－１）、（Ｈ－３）、（ＬＨ－１）、及び（Ｄ－１）を、３５：３５：３０：１５の質量比で混合したものに変更したこと以外は実施例１と同様に有機電界発光素子を作製した。発光層形成用組成物に含まれる全非発光材料の総量に対する低Ｔｇ化合物の含有率は３０質量％で、全非発光材料の加重平均ガラス転移温度は１２１℃であった。
あった。 (Example 6)
In Example 1, (HH-1), (H-3), (LH-1), and (D-1) were used as the non-light-emitting material and the light-emitting material included in the light-emitting layer forming composition: An organic electroluminescent element was produced in the same manner as in Example 1 except that the mixture was changed to a mixture at a mass ratio of 35:30:15. The content of the low Tg compound with respect to the total amount of all the non-light-emitting materials contained in the composition for forming a light-emitting layer was 30% by mass, and the weighted average glass transition temperature of all the non-light-emitting materials was 121 ° C.
there were.
（比較例１）
　実施例１において、発光層形成用組成物に含まれる非発光材料及び発光材料として、（ＬＨ－１）、（ＬＨ－２）、（Ｈ－３）及び（Ｄ－１）を、３０：３５：３５：１５の質量比で混合したものに変更したこと以外は実施例１と同様に有機電界発光素子を作製した。全非発光材料の加重平均ガラス転移温度は９６℃であった。 (Comparative Example 1)
In Example 1, (LH-1), (LH-2), (H-3) and (D-1) were used as non-light emitting materials and light emitting materials contained in the composition for forming a light emitting layer at 30:35. : An organic electroluminescence device was produced in the same manner as in Example 1 except that the mixture was changed to a mixture at a mass ratio of 35:15. The weighted average glass transition temperature of all non-luminescent materials was 96 ° C.
（比較例２）
　実施例１において、発光層形成用組成物に含まれる非発光材料及び発光材料として、（ＨＨ－１）、（ＨＨ－２）、及び（Ｄ－１）を、７０：３０：１５の質量比で混合したものに変更したこと以外は実施例１と同様に有機電界発光素子を作製した。全非発光材料の加重平均ガラス転移温度は１５４℃であった。
及び及び作製 (Comparative Example 2)
In Example 1, (HH-1), (HH-2), and (D-1) as a non-light emitting material and a light emitting material contained in the composition for forming a light emitting layer were mixed at a mass ratio of 70:30:15. An organic electroluminescent element was produced in the same manner as in Example 1 except that the mixture was changed to that mixed in the above. The weighted average glass transition temperature of all non-luminescent materials was 154 ° C.
And production
＜有機電界発光素子の駆動寿命の評価＞
　実施例１～６並びに比較例１及び２において得られた各有機電界発光素子を１００℃の恒温槽内で７２時間保存した後に、１５ｍＡ／ｃｍ２で駆動させ、輝度７０００ｃｄ／ｍ２で換算したときの１５％減衰寿命（ＬＴ８５）を算出した。そして、比較例のうち、ＬＴ８５の長かった比較例２のＬＴ８５を１とした場合の相対値（以下「加熱後ＬＴ８５」と称す。）を求めた。各実施例及び比較例の発光層形成用組成物の組成比と、駆動寿命の評価結果を表１に示す。 <Evaluation of driving life of organic electroluminescence device>
Each organic electroluminescence device obtained in Example 1-6 and Comparative Examples 1 and 2 after storage in a thermostat at 100 ° C. 72 hours, driven at 15 mA / cm 2, was converted by the luminance 7000cd / m 2 The 15% decay lifetime (LT85) was calculated. And the relative value (henceforth "LT85 after a heating") when LT85 of the comparative example 2 with which LT85 was long was set to 1 among the comparative examples was calculated | required. Table 1 shows the composition ratio of the composition for forming a light emitting layer of each example and comparative example, and the evaluation results of the driving life.
Figure JPOXMLDOC01-appb-T000020
  
Figure JPOXMLDOC01-appb-T000020
  
　（実施例７）
　図２に示す構成の有機電界発光素子を作製した。 (Example 7)
An organic electroluminescent element having the configuration shown in FIG. 2 was produced.
＜発光層＞
　実施例１と同様に陽極から正孔輸送層４まで形成し、発光層形成用組成物に含まれる非発光材料及び発光材料として、（ＨＨ－３）、（Ｈ－１）、（ＬＨ－２）及び（Ｄ－１）を、３５：３５：３０：１５の質量比で混合したものに変更したこと以外は実施例１と同様に発光層を形成した。なお、化合物（ＨＨ－３）は以下に示す構造を有する化合物であり、Ｔｇは１３２℃であり、分子量は８６８．１であった。発光層形成用組成物に含まれる全非発光材料の総量に対する低Ｔｇ化合物の含有率は３０質量％であり、全非発光材料の加重平均ガラス転移温度は１１２℃であった。 <Light emitting layer>
In the same manner as in Example 1, the anode to the hole transport layer 4 were formed, and as the non-light emitting material and the light emitting material contained in the light emitting layer forming composition, (HH-3), (H-1), (LH-2 ) And (D-1) were formed in the same manner as in Example 1 except that the mixture was changed to a mixture at a mass ratio of 35: 35: 30: 15. Compound (HH-3) was a compound having the structure shown below, Tg was 132 ° C., and molecular weight was 868.1. The content rate of the low Tg compound with respect to the total amount of all non-light-emitting materials contained in the composition for forming a light-emitting layer was 30% by mass, and the weighted average glass transition temperature of all the non-light-emitting materials was 112 ° C.
Figure JPOXMLDOC01-appb-C000021
Figure JPOXMLDOC01-appb-C000021
＜電子輸送層＞
　次いで、形成された発光層５上に、真空蒸着法により電子輸送層７として以下に示す化合物ＥＴ－２と化合物１を、２：３の質量比で混合した混合物を膜厚２０ｎｍとなるように形成した。なお、実施例１とは異なり正孔阻止層６は形成しなかった。 <Electron transport layer>
Next, a mixture obtained by mixing the following compound ET-2 and compound 1 shown below as the electron transport layer 7 by a vacuum deposition method on the formed light emitting layer 5 at a mass ratio of 2: 3 so as to have a film thickness of 20 nm. Formed. Unlike Example 1, the hole blocking layer 6 was not formed.
Figure JPOXMLDOC01-appb-C000022
  
Figure JPOXMLDOC01-appb-C000022
  
Figure JPOXMLDOC01-appb-C000023
  
Figure JPOXMLDOC01-appb-C000023
  
＜陰極・封止＞
　次いで陰極９としてアルミニウムを膜厚８０．０ｎｍとなるように積層した後、。実施例１と同様に封止処理を行った。なお、実施例１とは異なり、電子注入層８は形成しなかった。　 <Cathode / Sealing>
Subsequently, after laminating | stacking aluminum so that it might become a film thickness of 80.0 nm as the cathode 9. The sealing process was performed in the same manner as in Example 1. Unlike Example 1, the electron injection layer 8 was not formed.
（実施例８）
　実施例７において、発光層形成用組成物に含まれる非発光材料及び発光材料として化合物（ＨＨ－１）、（ＬＨ－３）及び（Ｄ－１）を、７０：３０：１５の質量比で混合したものに変更したこと以外は実施例７と同様に有機電界発光素子を作製した。なお、化合物（ＬＨ－３）は以下に示す構造を有する化合物であり、Ｔｇは９５℃であり、分子量は５８６．２であった。また、発光層形成用組成物に含まれる全非発光材料の総量に対する低Ｔｇ化合物の含有率は３０質量％であり、全非発光材料の加重平均ガラス転移温度は１４０℃であった。 (Example 8)
In Example 7, compounds (HH-1), (LH-3), and (D-1) as a non-light-emitting material and a light-emitting material contained in the light-emitting layer forming composition were mixed at a mass ratio of 70:30:15. An organic electroluminescent element was produced in the same manner as in Example 7 except that the mixture was changed to a mixed one. Compound (LH-3) was a compound having the structure shown below, Tg was 95 ° C., and molecular weight was 586.2. Moreover, the content rate of the low Tg compound with respect to the total amount of all the nonluminous materials contained in the composition for light emitting layer formation was 30 mass%, and the weighted average glass transition temperature of all the nonluminous materials was 140 degreeC.
Figure JPOXMLDOC01-appb-C000024
Figure JPOXMLDOC01-appb-C000024
（実施例９）
　実施例７において、発光層形成用組成物に含まれる非発光材料及び発光材料として化合物（ＨＨ－１）、（ＬＨ－１）、（ＬＨ－３）及び（Ｄ－１）を、７０：１５：１５：１５の質量比で混合したものに変更したこと以外は実施例７と同様に有機電界発光素子を作製した。発光層形成用組成物に含まれる全非発光材料の総量に対する低Ｔｇ化合物の含有率は３０質量％であり、全非発光材料の加重平均ガラス転移温度は１３９℃であった。 Example 9
In Example 7, the compounds (HH-1), (LH-1), (LH-3), and (D-1) were used as the non-light emitting material and the light emitting material contained in the light emitting layer forming composition. An organic electroluminescent element was produced in the same manner as in Example 7 except that the mixture was changed to a mixture of 15:15 by mass. The content of the low Tg compound with respect to the total amount of all the non-light-emitting materials contained in the composition for forming a light-emitting layer was 30% by mass, and the weighted average glass transition temperature of all the non-light-emitting materials was 139 ° C.
（実施例１０）
　実施例７において、発光層形成用組成物に含まれる非発光材料及び発光材料として化合物（ＨＨ－１）、（ＬＨ－１）及び（Ｄ－１）を、７０：３０：１５の質量比で混合したものに変更したこと以外は実施例７と同様に有機電界発光素子を作製した。発光層形成用組成物に含まれる全非発光材料の総量に対する低Ｔｇ化合物の含有率は３０質量％であり、全非発光材料の加重平均ガラス転移温度は１３８℃であった。 (Example 10)
In Example 7, compounds (HH-1), (LH-1) and (D-1) as a non-light-emitting material and a light-emitting material included in the composition for forming a light-emitting layer were mixed at a mass ratio of 70:30:15. An organic electroluminescent element was produced in the same manner as in Example 7 except that the mixture was changed to a mixed one. The content rate of the low Tg compound with respect to the total amount of all non-light-emitting materials contained in the composition for forming a light-emitting layer was 30% by mass, and the weighted average glass transition temperature of all the non-light-emitting materials was 138 ° C.
　（比較例３）
　実施例７において、発光層形成用組成物に含まれる非発光材料及び発光材料として化合物（ＨＨ－１）、（ＬＨ－４）及び（Ｄ－１）を、７０：３０：１５の質量比で混合したものに変更したこと以外は実施例７と同様に有機電界発光素子を作製した。なお、化合物（ＬＨ－４）は以下に示す構造を有する化合物であり、Ｔｇは９５℃であり、分子量は９３０．２であった。また、全非発光材料の加重平均ガラス転移温度は１４０℃であった。 (Comparative Example 3)
In Example 7, compounds (HH-1), (LH-4) and (D-1) as a non-light emitting material and a light emitting material contained in the composition for forming a light emitting layer in a mass ratio of 70:30:15 An organic electroluminescent element was produced in the same manner as in Example 7 except that the mixture was changed to a mixed one. Compound (LH-4) was a compound having the structure shown below, Tg was 95 ° C., and molecular weight was 930.2. Moreover, the weighted average glass transition temperature of all the non-light-emitting materials was 140 ° C.
Figure JPOXMLDOC01-appb-C000025
  
Figure JPOXMLDOC01-appb-C000025
  
（比較例４）
　実施例７において、発光層形成用組成物に含まれる非発光材料及び発光材料として化合物（ＨＨ－１）、（ＬＨ－５）及び（Ｄ－１）を、７０：３０：１５の重量比で混合したものに変更したこと以外は実施例７と同様に有機電界発光素子を作製した。なお、化合物（ＬＨ－５）は以下に示す構造を有する化合物であり、Ｔｇは８６℃であり、分子量は６１２．８であった。また、全非発光材料の加重平均ガラス転移温度は１３７℃であった。 (Comparative Example 4)
In Example 7, compounds (HH-1), (LH-5) and (D-1) as a non-light-emitting material and a light-emitting material contained in the composition for forming a light-emitting layer were mixed at a weight ratio of 70:30:15. An organic electroluminescent element was produced in the same manner as in Example 7 except that the mixture was changed to a mixed one. Compound (LH-5) was a compound having the structure shown below, Tg was 86 ° C., and molecular weight was 612.8. Moreover, the weighted average glass transition temperature of all the non-light-emitting materials was 137 ° C.
Figure JPOXMLDOC01-appb-C000026
Figure JPOXMLDOC01-appb-C000026
（比較例５）
　実施例７において、発光層形成用組成物に含まれる非発光材料及び発光材料として化合物（ＨＨ－１）、（ＬＨ－１）及び（Ｄ－１）を、９５：５：１５の質量比で混合したものに変更したこと以外は実施例７と同様に有機電界発光素子を作製した。なお、全非発光材料の加重平均ガラス転移温度は１５６℃であった。 (Comparative Example 5)
In Example 7, compounds (HH-1), (LH-1) and (D-1) as a non-light-emitting material and a light-emitting material contained in the composition for forming a light-emitting layer were used at a mass ratio of 95: 5: 15. An organic electroluminescent element was produced in the same manner as in Example 7 except that the mixture was changed to a mixed one. The weighted average glass transition temperature of all non-light emitting materials was 156 ° C.
＜有機電界発光素子の駆動寿命の評価＞
　実施例７～１０及び比較例３～５において得られた各有機電界発光素子を１００℃の恒温槽内で７２時間保存した後に、１５ｍＡ／ｃｍ２で駆動させ、輝度７０００ｃｄ／ｍ２で換算したときの１５％減衰寿命（ＬＴ８５）を算出した。そして、比較例のうち、ＬＴ８５が最も長かった比較例５のＬＴ８５を１とした場合の相対値として「加熱後ＬＴ８５」を求めた。各実施例及び比較例の発光層形成用組成物の組成比と、駆動寿命の評価結果を表２に示す。 <Evaluation of driving life of organic electroluminescence device>
Each organic electroluminescent device obtained in Examples 7-10 and Comparative Examples 3-5 after storage in a thermostat at 100 ° C. 72 hours, driven at 15 mA / cm 2, was converted by the luminance 7000cd / m 2 The 15% decay lifetime (LT85) was calculated. And "LT85 after heating" was calculated | required as a relative value when LT85 of the comparative example 5 with which LT85 was the longest was set to 1 among the comparative examples. Table 2 shows the composition ratio of the composition for forming a light emitting layer of each example and comparative example, and the evaluation results of the driving life.
Figure JPOXMLDOC01-appb-T000027
  
Figure JPOXMLDOC01-appb-T000027
  
　表１において、非発光材料として高Ｔｇ化合物及び低Ｔｇ化合物を含む実施例１～６では、非発光材料として高Ｔｇ化合物又は低Ｔｇ化合物のいずれか一方のみを含む比較例１及び比較例２に対して、加熱後においてもＬＴ８５が大きく、電圧も低いことが示されている。
　表２において、非発光材料としてピリミジン骨格又はトリアジン骨格を有する材料を含み、かつ低Ｔｇ化合物の含有率が特定範囲である実施例７～１０は、ＬＴ８５が大きくなっている。一方、非発光材料としてピリミジン骨格を有する材料及びトリアジン骨格を有する材料のいずれもを含まない比較例３及び４は、加熱後のＬＴ８５が小さくなっている。また、非発光材料としてピリミジン骨格又はトリアジン骨格を有する材料を含むが、低Ｔｇ化合物の含有率が特定範囲から外れる比較例５は、加熱後の電圧が高くなっている。
　以上より、実施例１～１０は加熱後でも高い特性が得られており、加熱後であっても優れた有機電界発光素子であることがわかる。 In Table 1, in Examples 1 to 6 containing a high Tg compound and a low Tg compound as the non-light-emitting material, Comparative Examples 1 and 2 containing only either the high Tg compound or the low Tg compound as the non-light-emitting material On the other hand, LT85 is large and voltage is low even after heating.
In Table 2, in Examples 7 to 10, which include a material having a pyrimidine skeleton or a triazine skeleton as the non-light emitting material and the content of the low Tg compound is in a specific range, LT85 is large. On the other hand, Comparative Examples 3 and 4 which do not include any of the material having a pyrimidine skeleton and the material having a triazine skeleton as the non-light emitting material have a small LT85 after heating. Moreover, although the material which has a pyrimidine frame | skeleton or a triazine frame | skeleton as a non-light-emitting material is included, the voltage after a heating is high in the comparative example 5 from which the content rate of a low Tg compound remove | deviates from a specific range.
From the above, it can be seen that Examples 1 to 10 have high characteristics even after heating, and are excellent organic electroluminescent elements even after heating.
　本発明は、有機電界発光素子の発光層形成用組成物として、有機電界発光素子が使用される各種の分野、例えば、フラットパネル・ディスプレイ（例えばＯＡコンピュータ用や壁掛けテレビ）や面発光体としての特徴を生かした光源（例えば、複写機の光源、液晶ディスプレイや計器類のバックライト光源）、表示板、標識灯、照明装置等の分野において、好適に使用することが出来る。 The present invention relates to various fields in which an organic electroluminescent element is used as a composition for forming a light emitting layer of an organic electroluminescent element, for example, as a flat panel display (for example, for OA computers and wall-mounted televisions) and a surface light emitter. It can be suitably used in the fields of light sources that make use of features (for example, light sources of copiers, backlight light sources of liquid crystal displays and instruments), display boards, marker lamps, and illumination devices.
　１　基板
　２　陽極
　３　正孔注入層
　４　正孔輸送層
　５　発光層
　６　正孔阻止層
　７　電子輸送層
　８　電子注入層
　９　陰極
　１０　有機電界発光素子 DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Electron injection layer 9 Cathode 10 Organic electroluminescent device

Claims (9)

  1. 　発光材料、非発光材料、及び有機溶媒を含む、有機電界発光素子の発光層形成用組成物であって、
    　該非発光材料は、ガラス転移温度が１３０℃以上である高Ｔｇ化合物及びガラス転移温度が１００℃以下である低Ｔｇ化合物とを含み、
    　全ての該非発光材料に対する該低Ｔｇ化合物の含有率が８～７０質量％であり、
    　該非発光材料の内、少なくとも一つはピリミジン骨格又はトリアジン骨格を有する材料である、発光層形成用組成物。     A composition for forming a light emitting layer of an organic electroluminescent device, comprising a light emitting material, a non-light emitting material, and an organic solvent,
    The non-luminescent material includes a high Tg compound having a glass transition temperature of 130 ° C. or higher and a low Tg compound having a glass transition temperature of 100 ° C. or lower.
    The content of the low Tg compound with respect to all the non-light emitting materials is 8 to 70% by mass;
    A composition for forming a light emitting layer, wherein at least one of the non-light emitting materials is a material having a pyrimidine skeleton or a triazine skeleton.
  2. 　前記発光層形成用組成物に含まれる全ての前記非発光材料の総量に対する含有率が１．０質量％以上である全ての各非発光材料の分子量が５０００以下である、請求項１に記載の発光層形成用組成物。 2. The molecular weight of all the non-light-emitting materials having a content of 1.0% by mass or more with respect to the total amount of all the non-light-emitting materials contained in the composition for forming a light-emitting layer is 5000 or less. A composition for forming a light emitting layer.
  3. 　全ての前記発光材料の分子量が５０００以下である、請求項１又は２に記載の発光層形成用組成物。 The composition for forming a light emitting layer according to claim 1 or 2, wherein the molecular weight of all the light emitting materials is 5000 or less.
  4. 　前記発光層形成用組成物に含まれる、ピリミジン骨格又はトリアジン骨格を有する材料が、前記高Ｔｇ化合物及び／又は前記低Ｔｇ化合物である、請求項１～３のいずれか１項に記載の発光層形成用組成物。 The light emitting layer according to any one of claims 1 to 3, wherein the material having a pyrimidine skeleton or a triazine skeleton contained in the composition for forming a light emitting layer is the high Tg compound and / or the low Tg compound. Forming composition.
  5. 　前記発光層形成用組成物に含まれる全ての前記非発光材料の加重平均ガラス転移温度が１００℃以上である、請求項１～４のいずれか１項に記載の発光層形成用組成物。 The composition for forming a light emitting layer according to any one of claims 1 to 4, wherein a weighted average glass transition temperature of all the non-light emitting materials contained in the composition for forming a light emitting layer is 100 ° C or higher.
  6. 　前記低Ｔｇ化合物が、単環化合物同士が直接結合及び／又は連結基を介して結合した化合物である、請求項１～５のいずれか１項に記載の発光層形成用組成物。 The composition for forming a light emitting layer according to any one of claims 1 to 5, wherein the low Tg compound is a compound in which monocyclic compounds are bonded to each other through a direct bond and / or a linking group.
  7. 　前記低Ｔｇ化合物が、芳香族炭化水素単環化合物同士が直接結合及び／又は連結基を介して結合した化合物のみからなる、請求項１～６のいずれか１項に記載の発光層形成用組成物。 The composition for forming a light emitting layer according to any one of claims 1 to 6, wherein the low Tg compound is composed only of a compound in which aromatic hydrocarbon monocyclic compounds are bonded directly and / or via a linking group. object.
  8. 　前記低Ｔｇ化合物が、下記の構造式（Ａ）で表される化合物である、請求項１～７のいずれか１項に記載の発光層形成用組成物。
    Figure JPOXMLDOC01-appb-C000001
     ［式（Ａ）において、Ｒ１～Ｒ１５は、それぞれ独立に、水素原子又は炭素数６～３０の、フェニル基若しくは芳香族炭化水素単環化合物が結合した一価の化合物を表す。］     The composition for forming a light emitting layer according to any one of claims 1 to 7, wherein the low Tg compound is a compound represented by the following structural formula (A).
    Figure JPOXMLDOC01-appb-C000001
     [In Formula (A), R 1 to R 15 each independently represents a monovalent compound in which a hydrogen atom or a phenyl group or aromatic hydrocarbon monocyclic compound having 6 to 30 carbon atoms is bonded. ]
  9. 　請求項１～８のいずれか１項に記載の発光層形成用組成物を用いて湿式成膜した発光層を有する有機電界発光素子。 An organic electroluminescence device having a light emitting layer formed by wet film formation using the composition for forming a light emitting layer according to any one of claims 1 to 8.
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