JP6984674B2 - Compositions for organic electroluminescent devices, organic electroluminescent devices, display devices and lighting devices - Google Patents

Description

The present invention relates to a composition for an organic electroluminescent device, an organic electroluminescent device, a display device, and a lighting device.

In recent years, various electronic devices using an organic electroluminescent element (hereinafter, also referred to as "organic EL element") such as an organic electroluminescent lighting (organic EL lighting) and an organic electroluminescent display (organic EL display) have been put into practical use. It is becoming more and more popular. Since the organic EL panel has a low applied voltage, low power consumption, surface emission, and is capable of emitting three primary colors, its application to lighting and displays is being actively studied. Further, it is required to reduce the manufacturing cost and to put into practical use an electronic device using a large-area organic EL panel.

Conventionally, a method for manufacturing an organic EL panel is to insert a plurality of organic layers (light emitting layer, hole injection layer, hole transport film, electron transport layer, etc.) between an anode and a cathode, and an organic layer such as a low molecular weight dye. It was done by vacuum-depositing the material of. However, the vacuum vapor deposition method has a problem that the utilization efficiency of the material is low and the manufacturing cost is high.
Further, when a large area panel is formed by a vacuum vapor deposition method, it is difficult to obtain a uniform and defect-free large area thin film because the thermal expansion of the substrate and the vapor deposition mask due to the radiant heat from the vapor deposition source occurs non-uniformly. rice field.

By the way, in recent years, a technique for forming an organic layer by a wet film forming method has been reported. According to the wet film forming method, it is possible to apply a necessary material in a necessary amount to a necessary place, so that it is possible to improve the utilization efficiency of the material. Further, since there is no non-uniform heat radiation, it is possible to form a uniform film even in a large area.
The manufacturing process of an organic electroluminescent device by such a wet film forming method is expected to enable simplification, efficiency, and cost reduction in manufacturing a large-area organic EL device, and various studies have been conducted. .. Specifically, it is considered that a large-area organic EL device can be realized at low cost by using, for example, an inkjet method or a nozzle coating method.

In the process of manufacturing an organic electroluminescent element by a wet film forming method, an ink in which a material for forming a layer having various functions is dissolved or dispersed in a solvent is manufactured, and a coating film is manufactured using the ink. However, these inks have a problem that they deteriorate in the period until use and the element characteristics deteriorate. One of the factors is oxidation by air or the like. Therefore, it is being considered to add an antioxidant or the like. This is a diversion of the effect of suppressing oxidation by adding an antioxidant to a resin or the like, and is particularly added to a polymer-based organic electroluminescent material. In addition, there are some cases where the characteristics are improved by adding to the fluorescent light emitting layer (Patent Document 1).

On the other hand, no attempt has been made to add an antioxidant to the phosphorescent material. This is because the antioxidant inhibits the oxidation reaction between the oxygen in the basal singlet and the material, but at the same time, the antioxidant has a function of capturing radicals, so that it becomes a radical itself. This is to extinguish and deteriorate the light emitting material. For example, a ruthenium-based complex is known to be deteriorated by a phenol-based antioxidant, which is a typical antioxidant (Patent Document 2). Further, it has been shown that Tetrakis (μ-pyrophosphito) diplatinate (II), which is a phosphorescent material, is quenched by a wide range of materials such as olefins, phosphorus, and amines (Non-Patent Document 1).

Common antioxidants such as BHT (butylhydroxytoluene) and phosphoric acid-based antioxidants are of the antioxidant system based on the principle of radical capture using hydroxyl groups and isolated electron pairs of phosphorus. Therefore, it is presumed that the characteristics of the phosphorescent light emitting layer deteriorate due to the same kind of factors, and it is considered that this has not been investigated so far.

Japanese Unexamined Patent Publication No. 2007-59935 Japanese Unexamined Patent Publication No. 11-194094

J. Phys. Chem. 1988,29, 4088-4094

In the process of manufacturing an organic electroluminescent element by a wet film forming method, an ink in which a material for forming a layer having various functions is dissolved or dispersed in a solvent is manufactured, and a coating film is manufactured using the ink. However, these inks have a problem that they deteriorate in the period until use and the element characteristics deteriorate. In particular, in a composition for forming a light emitting layer, since the light emitting material is sensitive to oxygen and water, it is not easy to obtain long-term storage stability, and it is desired to further obtain storage stability of the composition. rice field. An object of the present invention is to provide a composition that solves the above problems.

As a result of diligent studies on the above problems, the present inventors add an antioxidant, which was conventionally considered not to be added because it deteriorates the light emitting performance, to the light emitting layer forming composition. As a result, it has been found that long-term storage stability of the composition for forming a light emitting layer can be realized without impairing the function of the light emitting material, and the present invention has been completed.
That is, the gist of the present invention is as follows.
[1] A composition containing at least one phosphorescent material, a solvent and an antioxidant.
[2] The composition according to [1], wherein the composition is a composition for forming a light emitting layer of an organic electroluminescent device.
[3] The composition according to [1] or [2], wherein the phosphorescent material is a metal complex.
[4] The composition according to [3], wherein the metal complex is a metal complex containing a transition metal.
[5] The composition according to any one of [1] to [4], wherein the antioxidant is a phenolic antioxidant.
[6] An organic electroluminescent device having a layer formed by wet-forming the composition according to any one of [1] to [5].
[7] An organic EL display made by using the organic electroluminescent device according to [6].
[8] Organic EL lighting made by using the organic electroluminescent device according to [6].

By using the composition of the present invention, it is possible to obtain a good device whose drive life does not decrease even if an organic electroluminescent device is manufactured using the composition stored for a long period of time. That is, a composition that can be stored for a long period of time can be obtained.
The mechanism of action of the present invention is presumed as follows.
Usually, the phosphorescent material used for the light emitting layer has a light emitting mechanism via a triplet state. The triplet state is stable as an electronic state, but it is easy to capture oxygen whose ground state is a triplet, water having an isolated electron pair, and the like, and is unstable as a compound. Therefore, in order to inhibit the oxidation by oxygen, water, etc., the action can be stopped by adding an antioxidant. On the other hand, although the antioxidant has an active site for radicals, it protects the reaction site by steric hindrance and the like, so it is presumed that the phosphorescent material is not destroyed and the emission is not inhibited.

Furthermore, complexes with transition metals tend to form singlet states, as represented by phosphorescent materials such as Ir and Pt complexes. In addition, since it has an electron cloud (orbit) farther from the nucleus, it undergoes coordination due to a ligand, and as can be seen from the formation of weaker bonds than usual, lone electron pairs, radicals, It is easily affected by materials with empty orbits and materials in triple-term state. Therefore, an antioxidant is effective in preventing the influence of oxygen in the basal triplet.

FIG. 1 shows a schematic view of a suitable element cross section relating to an organic electroluminescent element.

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof.
The present invention is a composition comprising at least one phosphorescent material, a solvent and an antioxidant.

<Phosphorescent material>
The phosphorescent material of the present invention refers to a material that emits light from an excited triplet state. For example, a metal complex compound having Ir, Pt, Eu, etc. is a typical example. Among them, those containing a metal complex are preferable as the structure of the material.
Among the metal complexes, as a phosphorescent organic metal complex that emits light via a triplet state, it is a long-periodic periodic table (hereinafter, unless otherwise specified, the term "periodic table" refers to a long-periodic table. A Werner-type complex or an organic metal complex compound containing a metal selected from Groups 7 to 11 as a central metal can be mentioned. Preferred are compounds represented by the following formula (I) or formula (II).

ML (q-j) L'j ... (I)
(In the formula (I), M represents a metal, q represents the valence of the metal, L and L'represent a bidentate ligand, and j represents a number of 0, 1 or 2. When there are a plurality of Ls or L's, the plurality of Ls or the plurality of L's may be the same or different.)

(In formula (II), M ² represents a metal and T represents a carbon atom or a nitrogen atom. R ^{92 to} R ^95.
Represents a substituent independently of each other. However, when T is a nitrogen atom, there are no ^{R 94} and R ^95. )
Hereinafter, first, the compound represented by the formula (I) will be described.
In the formula (I), M is a metal selected from Groups 7 to 11 of the periodic table, preferably ruthenium, rhodium, palladium, silver, renium, osmium, iridium, platinum, gold and the like, and more preferably. Is iridium or platinum, and is most preferably iridium because of its high stability and high emission efficiency.

Further, in the formula (I), the bidentate ligand L represents a ligand having a partial structure represented by the following formula (III).

In the partial structure of the above formula (III), the 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 ring group or an aromatic heterocyclic group.
Further, in the partial structure of the above formula (III), the ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

Further, in the formula (I), the bidentate ligand L'represents a ligand having the following partial structure.

Among them, as L', the ligands listed below are preferable from the viewpoint of the stability of the complex.

The compound represented by the formula (I) is more preferably a compound represented by the following formulas (Ia), (Ib) and (Ic).

(In the formula (Ia), M4 represents a metal similar to M, w represents the valence of the metal, ring A1 represents an aromatic ring group which may have a substituent, and ring A2. Represents a nitrogen-containing aromatic heterocyclic group which may have a substituent. When w is 2 or more and there are a plurality of rings A1 and A2, the plurality of rings A1 or A2 may be the same. It may be different.)

(In the formula (Ib), M5 represents a metal similar to M, w-1 represents the valence of the metal, and ring A1 represents an aromatic ring group which may have a substituent. Ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent. When w is 3 or more and there are a plurality of rings A1 and A2, the plurality of rings A1 or A2 are the same. May be different.)

(In the formula (Ic), M6 represents a metal similar to M, w represents the valence of the metal, j represents 0, 1 or 2, and rings A1 and A1'are independent of each other. Represents an aromatic ring group which may have a substituent, and ring A2 and ring A2'independently represent a nitrogen-containing aromatic heterocyclic group which may have a substituent. When j is 2 or more or j is 2 or more and there are a plurality of rings A1, ring A1', ring A2 or ring A2', even if the plurality of rings A1, ring A1', ring A2 or ring A2' are the same, respectively. It may be different.)

In the above formulas (Ia) to (Ic) and (III), the aromatic rings of rings A1 and A1'are aromatic hydrocarbon groups or aromatic heterocyclic groups, and preferably have two free atomic valences. It has a benzene ring, a naphthalene ring, an anthracene ring, a triphenylyl ring, an asenaften ring, a fluorantene ring, a fluorene ring, a furan ring, a benzofuran ring, a thiophene ring, and a benzothiophene ring, more preferably a benzene ring and a naphthalene ring, and most preferably. Is a benzene ring. Here, in the present invention, the free valence can form a bond with another free valence as described in Organic Chemistry / Biochemical Nomenclature (above) (Revised 2nd Edition, Nanedo, published in 1992). Say something. That is, for example, "a benzene ring having one free valence" refers to a phenyl group, and "a benzene ring having two free valences" refers to a phenylene group.

In the above formulas (Ia) to (Ic), (III), the nitrogen-containing aromatic heterocyclic group of the ring A2 and the ring A2'is preferably a pyridyl group, a pyrimidyl group, a pyridyl group, a triazil group, a pyridyl group, an imidazolyl group, and the like. Oxazolyl group, thiazolyl group, benzothiazolyl group, benzoxazolyl group, benzoimidazolyl group, quinolyl group, isoquinolyl group, quinoxalyl group, quinazolyl group, phenanthridyl group, more preferably pyridine ring, pyrazine ring, pyrimidine ring, imidazolyl. Groups, quinolyl groups, isoquinolyl groups, quinoxalyl groups and quinazolyl groups are preferable, particularly preferably pyridyl group, imidazolyl group, quinolyl group, isoquinolyl group, quinoxalyl group and quinazolyl group, and most preferably pyridyl group, imidazolyl group and quinolyl group. , Kinoxalyl group, quinazolyl group.

In the above formulas (Ia) to (Ic) and (III), phenyl which may have a substituent is most preferable as a combined structure of ring A1 and ring A2 or a combined structure of ring A1'and ring A2'. -Phenyl structure, phenyl-quinoline structure which may have a substituent, phenyl-quinoxalin structure which may have a substituent, phenyl-imidazole structure which may have a substituent, and a substituent. It is a phenyl-quinazoline structure that may be used.

The substituents that the rings A1, ring A1', ring A2 and ring A2' in the above formulas (Ia) to (Ic) and (III) may have are a halogen atom and an alkyl group having 1 to 12 carbon atoms. , An alkenyl group having 1 to 12 carbon atoms, an alkoxycarbonyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aralkyl group having 1 to 24 carbon atoms, an aryloxy group having 1 to 12 carbon atoms, and a carbon number of carbon atoms. 1 to 24 dialkylamino groups, 8 to 24 carbon diarylamino groups, 5 or 6-membered monocyclic or 2 to 4 fused ring aromatic hydrocarbon ring groups, 6 to 24 carbon aromatic carbides Examples thereof include a hydrogen group, a carbazolyl group, an acyl group, a haloalkyl group and a cyano group. Preferably, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aralkyl group having 1 to 24 carbon atoms, a diarylamino group having 8 to 24 carbon atoms, a single ring having 5 or 6 membered rings or 2 It is an aromatic hydrocarbon ring group which is a ~ 4 fused ring, an aromatic ring group having 4 to 24 carbon atoms, and a carbazolyl group. A diarylamino group having 8 to 24 carbon atoms, an aromatic hydrocarbon ring group which is a single ring or a 2-4 condensed ring having 5 or 6 members, a monovalent aromatic hydrocarbon group having 6 to 24 carbon atoms, and a carbazolyl group. May further have a substituent on the aryl moiety constituting the group, and the substituents include an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, and 1 to 24 carbon atoms. Examples thereof include a monovalent aromatic hydrocarbon group having 6 to 24 carbon atoms which may be substituted with an alkyl group having 1 to 12 carbon atoms. The monovalent aromatic hydrocarbon group having 6 to 24 carbon atoms is preferably a monovalent group in which 1 to 4 benzene rings are linked.

In addition, these substituents may be linked to each other to form a ring. As a specific example, one of the substituents of the ring A1 and the substituent of the ring A2 is bonded to each other, or the substituent of the ring A1'and the substituent of the ring A2' are bonded to each other. A fused ring may be formed. Examples of such a fused ring include a 7,8-benzoquinoline group. The ring formed by linking these substituents to each other may further have the above-mentioned substituent. Further, the substituent may have one, or may have two or more substituents that are the same or different from each other.
Further, a preferable example of M in the formulas (Ia) to (Ic) is the same as M in the formula (I).

Next, the compound represented by the formula (II) will be described.
In formula (II), M ² represents a metal. As a specific example, the above-mentioned metal can be mentioned as a metal selected from the 7th to 11th groups of the periodic table. Of these, ruthenium, rhodium, palladium, silver, renium, osmium, iridium, platinum or gold are preferred, and divalent metals such as platinum and palladium are particularly preferred.

Further, in the formula (II), R ⁹² and R ⁹³ are independently hydrogen atom, halogen atom, alkyl group, aralkyl group, alkenyl group, cyano group, amino group, acyl group, alkoxycarbonyl group and carboxyl group, respectively. Represents an alkoxy group, an alkylamino group, an aralkylamino group, a haloalkyl group, a hydroxyl group, an aryloxy group, an aromatic hydrocarbon group or an aromatic heterocyclic group.

Further, when T is a carbon atom, R ⁹⁴ and R ⁹⁵ independently represent substituents represented by the same examples as ^{R 92} and R ^{93, respectively.} Further, when T is a nitrogen atom, there is no ^{R 94} or R ^{95 directly bonded to the T.}
Further, R ^{92 to} R ⁹⁵ may further have a substituent. As the substituent, the above-mentioned substituent can be used.
Further, ^{any two or more groups of R 92 to} R ⁹⁵ may be connected to each other to form a ring. The phosphorescent organometallic complex is preferably a compound represented by the formula (I).

<Antioxidant>
As for the types of antioxidants, as phenolic agents, BHT (butylhydroxytoluene), BHA (butylhydroxyanisole), Irganox series (BASF), ADEKA STAB AO series (ADEKA), Yoshinox series (AP Eye Corporation) A hindered phenolic system represented by the company) is preferable. Further, since antioxidants for foods such as tocopherol and ascorbic acid function by the same mechanism as BHT and the like, the same kind of effect can be expected. In addition, phosphite esters, like phenolic esters, are expected to have the effect of trapping radicals and protecting functional materials by their own oxidation, so it is thought that the same type of function works. In particular, BHT, BHA, an alkyl chain having 20 or less carbon atoms, or a phosphite ester having an allyl group having 30 or less carbon atoms is preferable.

<Composition>
The composition of the present invention contains at least the phosphorescent material, the antioxidant, and a solvent. The composition of the present invention is usually used for forming a layer or a film by a wet film forming method, and is particularly preferably used for forming an organic layer of an organic electroluminescent device. The organic layer is particularly preferably a light emitting layer.

That is, the composition of the present invention is preferably a composition for an organic electroluminescent device, and more preferably used as a composition for forming a light emitting layer of an organic electroluminescent device.
The content of the phosphorescent material in the composition of the present invention is usually 0.001% by weight or more, preferably 0.01% by weight or more, more preferably 0.05% by weight or more, usually 15% by weight or less, preferably 10%. It is less than% by weight. By setting the content of the phosphorescent material in the composition within this range, for example, when a light emitting layer is formed using this composition, from adjacent layers (for example, a hole transport layer or a hole blocking layer). Holes and electrons are efficiently injected into the light emitting layer, and the driving voltage can be reduced. It should be noted that the phosphorescent material may be contained in the composition of only one kind, or may be contained in combination of two or more kinds.

The content of the antioxidant with respect to the solvent in the composition of the present invention is usually 0.0001% by weight or more, usually 10% by weight or less, more preferably 0.1% by weight or less, still more preferably 0.01% by weight. % Or less, more preferably 0.001% by weight or less. By setting the content of the antioxidant in this range, deterioration of the phosphorescent light emitting material in the composition can be satisfactorily suppressed, and the luminous efficiency in the light emitting layer is not lowered, which is preferable.

<Other ingredients>
When the composition of the present invention is used, for example, for an organic electroluminescent element, the composition includes the above-mentioned phosphorescent material, antioxidant and solvent, as well as a charge-transporting compound used for an organic electroluminescent element, particularly a light emitting layer. Can be contained.
When the light emitting layer of the organic electroluminescent element is formed by using the composition of the present invention, it is preferable to use the phosphorescent light emitting material of the present invention as a dopant material and other charge transporting compounds as a host material.

As the charge transporting compound that can be contained in the composition of the present invention, those conventionally used as materials for an organic electroluminescent device can be used. For example, pyridine, carbazole, naphthalene, perylene, pyrene, anthracene, chrysene, naphthalene, phenanthrene, coronen, fluoranthene, benzophenanthrene, fluorene, acetonaftofluoranthene, coumarin, p-bis (2-phenylethenyl) benzene and theirs. Derivatives, quinacridone derivatives, DCM (4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostylyl) -4H-pyran) compounds, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, azabenzothioxanthene, aryl Examples thereof include a fused aromatic ring compound in which an amino group is substituted, a styryl derivative in which an arylamino group is substituted, and the like.

One of these may be used alone, or two or more of them may be used in any combination and ratio.
The content of the charge-transporting compound in the composition of the present invention is usually 0.01% by weight or more, preferably 0.1% by weight or more, and usually 50% by weight or less, preferably 30% by weight or less, still more preferably. It is 10% by weight or less.

The content of the charge-transporting compound in the composition of the present invention is usually 100% by weight or more, preferably 200% by weight or more, more preferably 300% by weight or more, and usually 100,000% by weight, based on the metal complex compound. % Or less, preferably 10,000% by weight or less, more preferably 2000% by weight or less.
The solvent contained in the composition of the present invention is a volatile liquid component used for forming a layer containing a metal complex compound by wet film formation.

The solvent is not particularly limited as long as it is a solvent in which the metal complex compound as a solute, the charge transporting compound described later, and the antioxidant are sufficiently dissolved. Preferred solvents include, for example, alkanes such as n-decane, cyclohexane, ethylcyclohexane, decalin, bicyclohexane; aromatic hydrocarbons such as toluene, xylene, methicylene, phenylcyclohexane, tetralin; chlorobenzene, dichlorobenzene, trichlorobenzene and the like. Halogenized aromatic hydrocarbons such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetol, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, etc. Aromatic ethers such as 2,4-dimethylanisole and diphenyl ether; aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, ethyl benzoate, propyl benzoate, n-butyl benzoate, etc. Alicyclic ketones such as cyclohexanone, cyclooctanone and fencon; alicyclic alcohols such as cyclohexanol and cyclooctanol; aliphatic ketones such as methylethylketone and dibutylketone; aliphatic alcohols such as butanol and hexanol; ethylene Hydrocarbon ethers such as glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA); and the like. Of these, alkanes and aromatic hydrocarbons are preferable, and phenylcyclohexane in particular has a preferable viscosity and boiling point in the wet film forming process.

One of these solvents may be used alone, or two or more of these solvents may be used in any combination and ratio.
The boiling point of the solvent is usually 80 ° C. or higher, preferably 90 ° C. or higher, more preferably 100 ° C. or higher, and particularly preferably 110 ° C. or higher. The boiling point of the solvent is usually 300 ° C. or lower, preferably 280 ° C. or lower, and more preferably 250 ° C. or lower. If the boiling point of the solvent is lower than the above lower limit, the film formation stability may decrease due to the evaporation of the solvent from the composition during the wet film formation.

The content of the solvent in the composition of the present invention is preferably 20% by weight or more, more preferably 50% by weight or more, still more preferably 80% by weight or more, and preferably 99.95% by weight or less, more preferably 99. It is 9.9% by weight or less, more preferably 99.8% by weight or less. For example, the light emitting layer is usually formed to have a thickness of about 3 to 200 nm, but when a light emitting layer having such a thickness is formed by using the composition of the present invention, if the content of the solvent is less than this lower limit, the composition is formed. The viscosity of the object may become too high, and the film forming workability may decrease. On the other hand, if it exceeds this upper limit, it tends to be difficult to form a film because the thickness of the film obtained by removing the solvent after the film formation cannot be increased.

The metal complex compound-containing composition of the present invention may further contain other compounds and the like in addition to the above-mentioned compounds and the like, if necessary. For example, another solvent may be contained in addition to the above solvent. Examples of such a solvent include amides such as N, N-dimethylformamide and N, N-dimethylacetamide, dimethyl sulfoxide and the like. One of these may be used alone, or two or more of them may be used in any combination and ratio.

<Wet film formation method>
The wet film forming method is a method in which a composition containing a solvent is applied onto a substrate and the solvent is dried and removed to form a film. The coating method is not limited, but is, for example, spin coating method, dip coating method, die coating method, bar coating method, blade coating method, roll coating method, spray coating method, capillary coating method, inkjet method, screen printing method, gravure. Examples include a printing method and a flexographic printing method.

As a method for drying and removing the solvent, heat drying is usually performed. Examples of heating means used in the heating step include clean ovens, hot plates, and infrared heating. As the infrared heating, a halogen heater, a ceramic-coated halogen heater, a ceramic heater, or the like can be used. Since heating with infrared rays directly gives heat energy to the substrate or membrane, it can be dried in a shorter time than heating using an oven or hot plate, and it is affected by the gas (moisture and oxygen) in the heating atmosphere and minute dust. It is preferable because the influence of the above can be minimized and the productivity is improved.

The heating temperature is usually 70 ° C. or higher, preferably 75 ° C. or higher, more preferably 80 ° C. or higher, and usually 150 ° C. or lower, preferably 140 ° C. or lower, more preferably 130 ° C. or lower.
The heating time is usually 10 seconds or more, preferably 60 seconds or more, more preferably 90 seconds or more, and usually 120 minutes or less, preferably 60 minutes or less, more preferably 30 minutes or less.
It is also preferable to perform vacuum drying before heat drying.
The film thickness of the organic layer obtained by forming the composition of the present invention into a film by a wet film forming method is usually 5 nm or more, preferably 10 nm or more, more preferably 20 nm or more, usually 500 nm or less, preferably 300 nm or less, still more preferable. Is 200 nm or less.

[Organic electroluminescent device]
The organic electroluminescent device according to the present invention is an organic electroluminescent device having an anode, a cathode, and at least one organic layer between them, and at least one of the organic layers is the composition of the present invention. It is characterized by being a layer formed by wet film formation using. This layer is preferably a light emitting layer.
FIG. 1 is a schematic cross-sectional view showing a structural example suitable for the organic electroluminescent device according to the present invention. In FIG. 1, reference numeral 1 is a substrate, reference numeral 2 is an anode, reference numeral 3 is a hole injection layer, and reference numeral 4 is a hole injection layer. The hole transport layer, reference numeral 5 is a light emitting layer, reference numeral 6 is a hole blocking layer, reference numeral 7 is an electron transport layer, reference numeral 8 is an electron injection layer, and reference numeral 9 is a cathode.

[1] Substrate The substrate 1 serves as a support for an organic electric field light emitting element, and a quartz or glass plate, a metal plate, a metal foil, a plastic film, a sheet, or the like is used. In particular, a glass plate or a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, or polysulfone is preferable. When using a synthetic resin substrate, it is necessary to pay attention to the gas barrier property. If the gas barrier property of the substrate is too small, the organic electroluminescent device may be deteriorated by the outside air passing through the substrate, which is not preferable. Therefore, one of the preferable methods is to provide a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate to secure the gas barrier property.

[2] Anode 2 The anode 2 is provided on the substrate 1. The anode 2 plays a role of injecting holes into a layer on the light emitting layer side (hole injection layer 3, hole transport layer 4, light emitting layer 5, etc.).
The anode 2 is usually a metal such as aluminum, gold, silver, nickel, palladium, platinum, a metal oxide such as an oxide of indium and / or tin, a metal halide such as copper iodide, carbon black, or carbon black. It is composed of conductive polymers such as poly (3-methylthiophene), polypyrrole, and polyaniline.

The anode 2 is usually formed by a sputtering method, a vacuum vapor deposition method, or the like. In addition, when forming an anode using metal fine particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, conductive polymer fine powder, etc., use an appropriate binder resin solution. The anode 2 can also be formed by dispersing and applying the particles on the substrate 1. Further, in the case of a conductive polymer, a thin film can be formed directly on the substrate 1 by electrolytic polymerization, or an anode 2 can be formed by applying the conductive polymer on the substrate 1 (Appl. Phys. Lett). ., Volume 60, p. 2711, 1992).

The anode 2 usually has a single-layer structure, but it is also possible to have a laminated structure made of a plurality of materials if desired.
The thickness of the anode 2 depends on the required transparency. When transparency is required, it is desirable that the transmittance of visible light is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably about 500 nm or less. When it may be opaque, the thickness of the anode 2 is arbitrary, and the anode 2 may be the same as the substrate 1. Further, it is also possible to laminate different conductive materials on the above-mentioned anode 2.
For the purpose of removing impurities adhering to the anode and adjusting the ionization potential to improve hole injection, the surface of the anode is treated with ultraviolet rays (UV) / ozone, oxygen plasma treatment, and argon plasma treatment. It is preferable to do so.

[3] Hole Injection Layer The hole injection layer 3 is a layer for transporting holes from the anode 2 to the light emitting layer 5, and is usually formed on the anode 2.
The method for forming the hole injection layer 3 according to the present invention may be a vacuum vapor deposition method or a wet film formation method, and is not particularly limited. However, the hole injection layer 3 is formed by the wet film formation method from the viewpoint of reducing dark spots. Is preferable.
The film thickness of the hole injection layer 3 is usually in the range of 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less.

<Formation of hole injection layer by wet film formation method>
When the hole injection layer 3 is formed by wet film formation, usually, the material constituting the hole injection layer 3 is mixed with an appropriate solvent (solvent for the hole injection layer) to form a composition for coating (holes). A composition for forming an injection layer) is prepared, and this composition for forming a hole injection layer is applied onto a layer (usually an anode) corresponding to the lower layer of the hole injection layer 3 by an appropriate method and dried. As a result, the hole injection layer 3 is formed.

(Hole-transporting compound)
The composition for forming a hole injection layer usually contains a hole transporting compound and a solvent as a constituent material of the hole injection layer. The hole-transporting compound is a polymer compound such as a polymer as long as it is a compound having a hole-transporting property, which is usually used for the hole injection layer of an organic electric field light emitting element. Although it may be a low molecular weight compound, it is preferably a high molecular weight compound.

As the hole transporting compound, a compound having an ionization potential of 4.5 eV to 6.0 eV is preferable 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 derivatives, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, benzylphenyl derivatives, compounds in which a tertiary amine is linked with a fluorene group, hydrazone derivatives, silazane derivatives, and silanamin. Examples thereof include derivatives, phosphamine derivatives, quinacridone derivatives, polyaniline derivatives, polypyrrole derivatives, polyphenylene vinylene derivatives, polythienylene vinylene derivatives, polyquinoline derivatives, polyquinoxalin derivatives, carbon and the like.

In the present invention, the derivative includes, for example, an aromatic amine derivative itself and a compound having an aromatic amine as a main skeleton, even if it is a polymer. It may be a metric.
Among the above-exemplified examples, aromatic amine compounds are preferable, and aromatic tertiary amine compounds are 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 also includes a compound having a group derived from the aromatic tertiary amine.

The type of the aromatic tertiary amine compound is not particularly limited, but from the viewpoint of uniform light emission due to the surface smoothing effect, polymer compounds having a weight average molecular weight of 1000 or more and 1,000,000 or less (polymerized compounds having a series of repeating units) are further used. preferable.
Further, as the hole transporting compound, a conductive polymer (PEDOT / PSS) obtained by polymerizing 3,4-ethylenedioxythiophene (3,4-ethylenedioxythiophene), which is a derivative of polythiophene, in high-molecular-weight polystyrene sulfonic acid. Is also preferable. Further, the end of this polymer may be capped with methacrylate or the like.

The concentration of the hole transporting compound in the composition for forming a hole injection layer is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.01% by weight or more, preferably 0.01% by weight or more in terms of film thickness uniformity. Is 0.1% by weight or more, more preferably 0.5% by weight or more, and usually 70% by weight or less, preferably 60% by weight or less, still more preferably 50% by weight or less. If this concentration is too high, the film thickness may be uneven, and if it is too low, the formed hole injection layer may be defective.

(Electron accepting compound)
The composition for forming a hole injection layer preferably contains an electron-accepting compound as a constituent material of the hole injection layer.
The electron-accepting compound is preferably a compound having an oxidizing power and having an ability to accept one electron from the hole-transporting compound described above, and specifically, a compound having an electron affinity of 4 eV or more is preferable and 5 eV or more. The compound is more preferred.

Examples of such an electron-accepting compound include a triarylboron compound, a metal halide, a Lewis acid, an organic acid, an onium salt, a salt of an arylamine and a metal halide, and a salt of an arylamine and a Lewis acid. One or more compounds selected from the group may be mentioned. More specifically, iron (III) chloride (Japanese Patent Laid-Open No. 11-251067), high atomic value inorganic compounds such as ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene, tris (pentafluorophenyl) borane Aromatic boron compounds such as (Japanese Unexamined Patent Publication No. 2003-31365); onium salt substituted with an organic group (International Publication No. 2005/089024); fullerene derivative; iodine; polystyrene sulfonic acid ion, alkylbenzene sulfonic acid ion, Examples thereof include sulfonate ions such as Drosophila sulfonate ions.

These electron-accepting compounds can improve the conductivity of the hole-injected layer by oxidizing the hole-transporting compound.
The content of the electron-accepting compound in the hole-injecting layer or the composition for forming the hole-injecting layer with respect to the hole-transporting compound is usually 0.1 mol% or more, preferably 1 mol% or more. However, it is usually 100 mol% or less, preferably 40 mol% or less.

(solvent)
It is preferable that at least one of the solvents of the composition for forming the hole injection layer used in the wet film forming method is a compound capable of dissolving the constituent material of the hole injection layer described above. The boiling point of this solvent is usually 80 ° C. or higher, preferably 100 ° C. or higher, more preferably 110 ° C. or higher, usually 300 ° C. or lower, preferably 280 ° C. or lower. If the boiling point of the solvent is too low, the drying rate may be too fast and the film quality may deteriorate. Further, if the boiling point of the solvent is too high, it is necessary to raise the temperature of the drying step, which may adversely affect other layers and substrates.

Examples of the solvent include ether solvents, ester solvents, aromatic hydrocarbon solvents, amide solvents and the like.
Examples of the ether solvent include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, and anisole. , Fenetol, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, aromatic ethers such as 2,4-dimethylanisole, and the like.

Examples of the ester-based 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-iropropylbiphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, cyclohexylbenzene, methylnaphthalene and the like. Can be mentioned.

Examples of the amide-based solvent include N, N-dimethylformamide, N, N-dimethylacetamide, and the like.
In addition, dimethyl sulfoxide and the like can also be used.
Only one of these solvents may be used, or two or more of these solvents may be used in any combination and ratio.

(Film formation method)
After preparing the composition for forming the hole injection layer, this composition is applied to the layer corresponding to the lower layer of the hole injection layer 3 (usually, the anode 2) by wet film formation, and dried to form holes. The injection layer 3 is formed.
The temperature in the coating step is preferably 10 ° C. or higher, preferably 50 ° C. or lower, in order to prevent film damage due to the formation of crystals in the composition.

The relative humidity in the coating step is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.01 ppm or more and usually 80% or less.
After coating, if necessary, the solvent is roughly removed by vacuum drying or the like, and then the film of the composition for forming a hole injection layer is dried by heating. Examples of the heating means used in the heating step include a clean oven, a hot plate, an infrared heater (halogen heater), and the like.

The heating temperature in the heating step is preferably a temperature equal to or higher than the boiling point of the solvent used in the composition for forming the hole injection layer, as long as the effect of the present invention is not significantly impaired. Further, in the case of a mixed solvent containing two or more kinds of solvents used for the hole injection layer, it is preferable that at least one kind is heated at a temperature equal to or higher than the boiling point of the solvent. Considering the boiling point elevation of the solvent, it is preferable to heat at 120 ° C. or higher, preferably 300 ° C. or lower in the heating step.

In the heating step, if the heating temperature is equal to or higher than the boiling point of the solvent for forming the hole injection layer and sufficient insolubilization of the film does not occur, the heating time is not limited, but is preferably 10 seconds or longer, usually 180. Less than a minute. If the heating time is too long, the components of other layers tend to diffuse, and if it is too short, the hole injection layer tends to become inhomogeneous. The heating may be performed in two steps.

<Formation of hole injection layer by vacuum vapor deposition method>
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-mentioned hole transporting compound, electron accepting compound, etc.) are placed in a vacuum vessel. Put it in the installed crucible (when using two or more kinds of materials, put it in each crucible), ^{exhaust the inside of the vacuum container to about 10-4} Pa with an appropriate vacuum pump, and then heat the crucible (two kinds). When the above materials are used, each crucible is heated), and the amount of evaporation is controlled to evaporate the constituent materials of the hole injection layer 3 (when two or more kinds of materials are used, the amount of evaporation is controlled independently. And evaporate) to form the hole injection layer 3 on the anode 2 of the substrate placed facing the crucible. When two or more kinds of materials are used, a mixture thereof can be placed in a crucible and heated and evaporated to form the hole injection layer 3.

The degree of vacuum during vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 × 10 ^-7 Torr (1.3 × 10 ^-6 Pa) or more, and usually 9.0 × 10 ^-6 Torr. It is (12.0 × 10 ^-4 Pa) or less.
The vapor deposition rate is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 Å / sec or more and usually 5.0 Å / sec or less.

[4] Hole transport layer The hole transport layer 4 is formed on the hole injection layer 3 when there is a hole injection layer, and on the anode 2 when there is no hole injection layer 3. Can be done. Further, the organic electroluminescent device of the present invention may have a configuration in which the hole transport layer is omitted.
The method for forming the hole transport layer 4 may be a vacuum vapor deposition method or a wet film formation method, and is not particularly limited, but it is preferable to form the hole transport layer 4 by a wet film formation method from the viewpoint of reducing dark spots.

As the material for forming the hole transport layer 4, it is preferable that the material has a high hole transport property and can efficiently transport the injected holes. Therefore, it is preferable that the ionization potential is small, the transparency is high with respect to visible light, the hole mobility is large, the stability is excellent, and impurities that become traps are less likely to be generated during production or use. Further, in many cases, since it is in contact with the light emitting layer 5, it is preferable not to quench the light emitted from the light emitting layer 5 or form an exciplex with the light emitting layer 5 to reduce the efficiency.

The material of such a hole transport layer 4 may be any material conventionally used as a constituent material of the hole transport layer, and for example, the hole transport property used in the hole injection layer 3 described above. Examples thereof include those exemplified. In addition, arylamine derivatives, fluorene derivatives, spiro derivatives, carbazole derivatives, pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, phthalocyanine derivatives, porphyrin derivatives, silol derivatives, oligothiophene derivatives, condensed polycyclic fragrances. Examples include group derivatives and metal complexes.

Further, for example, a polyvinylcarbazole derivative, a polyarylamine derivative, a polyvinyltriphenylamine derivative, a polyfluorene derivative, a polyarylene derivative, a polyarylene ether sulfone derivative containing tetraphenylbenzidine, a polyarylene vinylene derivative, a polysiloxane derivative, and polythiophene. Derivatives, poly (p-phenylene vinylene) derivatives and the like can be mentioned. These may be any of alternating copolymers, random polymers, block polymers or graft copolymers. Further, it may be a polymer having a branch in the main chain and having three or more terminal portions, or a so-called dendrimer.

Of these, polyarylamine derivatives and polyarylene derivatives are preferable.
The polyarylamine derivative is preferably a polymer containing a repeating unit represented by the following formula (V). In particular, it is preferably a polymer composed of repeating units represented by the following formula (V), and in this case, Ar ^a or Ar ^b may be different in each repeating unit.

(In the formula (V), Ar ^a and Ar ^b each independently represent an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent.)
Examples of the aromatic hydrocarbon group which may have a substituent include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, and a pyrene having one or two free valences. A 6-membered monocyclic or 2-5 fused ring or a ring thereof having one or two free valences such as a ring, a benzpyrene ring, a chrysen ring, a triphenylene ring, an acenaphthene ring, a fluorentene ring, a fluorene ring, etc. Examples thereof include groups in which two or more rings are directly bonded to each other.

Examples of the aromatic heterocyclic group which may have a substituent include a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrazole ring, a pyrazole ring, and an imidazole having one or two free atomic valences. Ring, oxadiazole ring, indole ring, carbazole ring, pyrrolobymidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrazole ring, thienothiophene ring, flopyrol ring, flofran ring, thienoflan ring, benzoisoxazole ring, benzoisothiazole ring , Benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxalin ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazolin ring, quinazolinone ring, Examples thereof include a 5- or 6-membered monocyclic ring or a 2-4 condensed ring having one or two free valences such as an azulene ring, or a group formed by directly bonding two or more rings thereof. ..

From the viewpoint of solubility in organic solvents and heat resistance, Ar ^a and Ar ^b independently have one or two free valences, such as a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, and a triphenylene ring. A group consisting of two or more rings selected from the group consisting of a pyrene ring, a thiophene ring, a pyridine ring, and a fluorene ring or a benzene ring (for example, a biphenyl group (biphenylene group) or a terphenyl group (terphenylene group)) is formed. Among them, a benzene ring, a biphenyl ring and a fluorene ring having one or two free valences are preferable.

The ^{substituents that the aromatic hydrocarbon group and the aromatic heterocyclic group in Ar a} and Ar ^b may have include an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group and a dialkyl group. Examples thereof include an amino group, a diarylamino group, an acyl group, a halogen atom, a haloalkyl group, an alkylthio group, an arylthio group, a silyl group, a syroxy group, a cyano group, an aromatic hydrocarbon ring group and an aromatic heterocyclic group.

As the polyarylene derivative, an arylene group such as an aromatic hydrocarbon group or an aromatic heterocyclic group, which may have a substituent exemplified as ^{Ar a} or Ar ^b in the above formula (V), is used as a repeating unit thereof. Examples thereof include polymers having.
As the polyarylene derivative, a polymer having at least one of the repeating units consisting of the following formula (VI) and the following formula (VII) is preferable.

(In the formula (VI), R ^a , R ^b , R ^c and R ^d are each independently an alkyl group, an alkoxy group, a phenylalkyl group, a phenylalkoxy group, a phenyl group, a phenoxy group, an alkylphenyl group and an alkoxyphenyl. A group, an alkylcarbonyl group, an alkoxycarbonyl group, or a carboxy group. V and w each independently represent an integer of 0 to 3. When v or w is 2 or more, a plurality of groups contained in one molecule. R ^a or R ^b may be the same or different, and adjacent R ^a or R ^b may form a ring.)

(In formula (VII), R ^e and R ^{f are independently synonymous with R a} , R _b , R ^c or R ^d in the above formula (VI). X and y are independently 0. Represents an integer of ~ 3. When x or y is 2 or more, a plurality of Res and Rfs contained in one molecule may be the same or different, and adjacent Res or Rfs form a ring. Q represents an atom or a group of atoms constituting a 5-membered ring or a 6-membered ring.)
Specific examples of Q include -O-, -BR-, -NR-, -SiR _2- , -PR-, -SR-, -CR _2-, or a group formed by binding these. In addition, R here represents a hydrogen atom or an arbitrary organic group. The arbitrary organic group in the present invention may be a group containing at least one carbon atom.

Further, the polyarylene derivative preferably has a repeating unit represented by the following formula (VIII) in addition to at least one of the repeating units consisting of the formula (VI) and the formula (VII).

(In the formula (VIII), Ar ^c ~Ar ^h and Ar ^j are each independently may have a substituent group, .Ganma and δ represents an aromatic hydrocarbon group or an aromatic heterocyclic group, Represents 0 or 1 independently.)
Specific examples of Ar ^{c to} Ar ^h and Ar ^j are the same as those of ^{Ar a} and Ar ^b in the above equation (V).

Specific examples of the above formulas (VI) to (VIII) and specific examples of polyarylene derivatives include those described in Japanese Patent Application Laid-Open No. 2008-98619.
When the hole transport layer 4 is formed by the wet film formation method, the hole injection layer 3 is formed in the same manner as described above.
After preparing the composition for forming a hole transport layer, it is applied and dried by heating.
The composition for forming a hole transport layer contains a solvent in addition to the above-mentioned hole transport compound. The solvent used is the same as that used in the composition for forming the hole injection layer. Further, the coating conditions, the heating and drying conditions, and the like are the same as in the case of forming the hole injection layer 3.

Also when the hole transport layer is formed by the vacuum vapor deposition method, the film forming conditions and the like are the same as in the case of forming the hole injection layer 3.
In addition to the hole transporting compound, the hole transporting layer 4 contains various light emitting materials, an electron transporting compound, an electron accepting compound, a binder resin, a leveling agent, a coating property improving agent such as an antifoaming agent, and the like. May be.

The hole transport layer 4 is also preferably a layer formed by insolubilizing a compound having an insolubilizing group (hereinafter, referred to as "insolubilizing compound") from the viewpoint of heat resistance or film forming property. The insolubilizing compound is a compound having an insolubilizing group, and forms an insolubilizing polymer by insolubilizing.
The insolubilizing group is a group that reacts by irradiation with heat and / or active energy rays, and is a group having an effect of lowering the solubility in an organic solvent or water after the reaction as compared with before the reaction. In the present invention, the insolubilizing group is preferably a leaving group or a crosslinkable group.

The leaving group is a group that dissociates from the bound aromatic hydrocarbon ring at 70 ° C. or higher and is further soluble in a solvent. Here, "soluble in a solvent" means that the compound is dissolved in toluene at room temperature in an amount of 0.1% by weight or more at room temperature before the compound reacts by irradiation with heat and / or active energy rays. The solubility in toluene is preferably 0.5% by weight or more, more preferably 1% by weight or more.

The leaving group is preferably a group that thermally dissociates without forming a polar group on the ring side of the aromatic hydrocarbon, and more preferably a group that thermally dissociates by a reverse Diels-Alder reaction. Further, it is preferably a group that thermally dissociates at 100 ° C. or higher, and preferably a group that thermally dissociates at 300 ° C. or lower.
Examples of crosslinkable groups include groups derived from cyclic ethers such as oxetane and epoxy; groups derived from unsaturated double bonds such as vinyl group, trifluorovinyl group, styryl group, acrylic group, methacryloyl and cinnamoyl; Examples include groups derived from benzocyclobutane.

The insolubilizing compound may be a monomer, an oligomer, or a polymer. The insolubilizing compound may have only one kind, or may have two or more kinds in any combination and ratio.
As the insolubilizing compound, it is preferable to use a hole transporting compound having a crosslinkable group. Examples of hole-transporting compounds include nitrogen-containing aromatic compound derivatives such as pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, carbazole derivatives, phthalocyanine derivatives, and porphyrin derivatives; triphenylamine derivatives. ; Sirol derivative; Oligothiophene derivative, condensed polycyclic aromatic derivative, metal complex and the like can be mentioned. Among them, nitrogen-containing aromatic derivatives such as pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, and carbazole derivatives; triphenylamine derivatives, silol derivatives, condensed polycyclic aromatic derivatives, metal complexes, etc. Preferred, especially triphenylamine derivatives are more preferred.

In order to insolubilize an insoluble compound to form a hole transport layer 4, usually, a composition for forming a hole transport layer in which an insoluble compound is dissolved or dispersed in a solvent is prepared, and a film is formed by a wet film forming method. To insolubilize.
The composition for forming a hole transport layer contains an insolubilizing compound in an amount of usually 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, usually 50% by weight or less, preferably 20% by weight. It is contained in an amount of 10% by weight or less, more preferably 10% by weight or less.

A composition for forming a hole transport layer containing an insoluble compound at such a concentration is formed on a lower layer (usually a hole injection layer 3), and then heated and / or irradiated with active energy such as light to insolubilize the compound. Insolubilize.
Conditions such as temperature and humidity at the time of coating are the same as those at the time of wet film formation of the hole injection layer 3. The method of heating after coating is not particularly limited. The heating temperature condition is usually 120 ° C. or higher, preferably 400 ° C. or lower. The heating time is usually 1 minute or more, preferably 24 hours or less. The heating means is not particularly limited, but means such as placing a laminate having a film-formed layer on a hot plate or heating in an oven are used. For example, conditions such as heating on a hot plate at 120 ° C. or higher for 1 minute or longer can be used.

In the case of irradiation with electromagnetic energy such as light, a method of irradiating with an ultra-high pressure mercury lamp, a high pressure mercury lamp, etc., or a method of irradiating with a mask aligner incorporating the above-mentioned light source, a conveyor type light irradiation device, etc. Can be mentioned.
The film thickness of the hole transport layer 4 thus formed is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less.

[5] Light emitting layer A light emitting layer 5 is usually provided on the hole transport layer 4. The light emitting layer 5 was excited by the recombination of the holes injected from the anode 2 through the hole injection layer 3 and the electrons injected from the cathode 9 through the electron transport layer 7 between the electrodes to which the electric field was applied. , The layer that is the main source of light emission. The light emitting layer 5 preferably contains a light emitting material (dopant) and one or more kinds of host materials. The light emitting material is preferably the metal complex compound according to the present invention, and the host material is preferably the charge transporting compound according to the present invention. The light emitting layer 5 is preferably a layer formed by wet-forming the composition of the present invention. The light emitting layer 5 may further have a layer formed by a vacuum vapor deposition method.

The light emitting layer 5 may contain other materials and components other than the light emitting material (dopant) and the host material as long as the performance of the present invention is not impaired.
The organic electroluminescent device may have two or more light emitting layers. When two or more light emitting layers are provided, any light emitting layer may satisfy the provisions of the present invention. In the case of two or more layers, each light emitting layer may be in direct contact with each other, or may be interposed between other layers. Examples of other layers interposed therein include a charge transport layer, a block layer, a charge generation layer, and the like.

It is preferable to have a light emitting layer formed by a vapor deposition method on a layer formed by wet-depositing the composition of the present invention, and more preferably, the composition of the present invention is wet-deposited. It is configured to have a fluorescent light emitting layer formed by a vapor deposition method on the formed layer. By forming a light emitting layer by a vapor deposition method on a layer formed by wet-forming the composition of the present invention, the light emitting layer can be uniformly laminated, which is preferable. Further, if the light emitting layer formed by the vapor deposition method on the layer formed by wet-forming the composition of the present invention is a fluorescent light emitting layer, the fluorescent light emitting layer material usually does not contain heavy atoms and has a relatively low temperature. Therefore, the energy when the composition of the present invention, which is the lower layer of the fluorescent light-emitting material, is adhered to the layer formed by wet film formation is low, and there is no damage to the lower layer, which is preferable.

[6] Hole blocking layer The hole blocking layer 6 is laminated on the light emitting layer 5 so as to be in contact with the interface on the cathode side of the light emitting layer 5. In particular, when a phosphorescent light emitting material or a blue light emitting material is used as the light emitting material of the light emitting layer 5, it is effective to provide the hole blocking layer 6. The hole blocking layer 6 has a function of confining holes and electrons in the light emitting layer 5 to improve the luminous efficiency. That is, the hole blocking layer 6 is generated by increasing the recombination probability with electrons in the light emitting layer 5 by blocking the holes moving from the light emitting layer 5 from reaching the electron transport layer 7. It has a role of confining excitons in the light emitting layer 5 and a role of efficiently transporting electrons injected from the electron transport layer 7 toward the light emitting layer 5.
The physical properties required for the material constituting the hole blocking layer 6 are high electron mobility and low hole mobility, a large energy gap (difference between HOMO and LUMO), and an excited triplet level (T1). Is high.

Examples of the hole blocking layer material satisfying such conditions include a mixed compound of bis (2-methyl-8-quinolinolato) (phenolato) aluminum, bis (2-methyl-8-quinolinolato) (triphenylsilanorat) aluminum, and the like. Position complex, metal complex such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolilato) aluminum dinuclear metal complex, styryl compound such as distyrylbiphenyl derivative ( Japanese Patent Application Laid-Open No. 11-242996), 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4-triazole and other triazole derivatives (Japanese Patent Laid-Open No. 11-242996) 7-41759A), phenylanthroline derivatives such as bathocuproine (Japanese Patent Laid-Open No. 10-79297). Further, a compound having at least one pyridine ring substituted at the 2, 4, 6 position described in International Publication No. 2005/022962 is also preferable as a hole blocking material.

As the material of the hole blocking layer 6, only one kind may be used, or two or more kinds may be used in any combination and ratio.
The film thickness of the hole blocking layer 6 is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.
The hole blocking layer 6 can also be formed by the same method as the hole injection layer 3, but a vacuum vapor deposition method is usually used.

[7] Electron transport layer The electron transport layer 7 is provided between the hole injection layer 6 and the electron injection layer 8 described later for the purpose of further improving the luminous efficiency of the device. The electron transport layer 7 is formed of a compound capable of efficiently transporting electrons injected from the cathode 9 between electrodes to which an electric field is applied in the direction of the light emitting layer 5. As the electron-transporting compound used for the electron-transporting layer 7, the electron-injecting efficiency from the cathode 9 or the electron-injecting layer 8 is high, and the injected electrons can be efficiently transported with high electron mobility. It needs to be a compound.

Examples of the material satisfying such conditions include a metal complex such as an aluminum complex of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), a metal complex of 10-hydroxybenzo [h] quinoline, and an oxadiazole derivative. , Distyrylbiphenyl derivative, silol derivative, 3- or 5-hydroxyflavon metal complex, benzoxazole metal complex, benzothiazole metal complex, trisbenzimidazolylbenzene (US Patent No. 5,645,948), quinoxalin compound (Japan) Japanese Patent Application Laid-Open No. 6-207169), phenanthroline derivative (Japanese Patent Laid-Open No. 5-331459), 2-t-butyl-9,10-N, N'-dicyanoanthraquinonediimine, n-type hydrogenated amorphous Quality Silicon carbide, n-type zinc sulfide, n-type zinc selenium and the like can be mentioned.

The lower limit of the film thickness of the electron transport layer 7 is usually about 1 nm, preferably about 5 nm, and the upper limit is usually about 300 nm, preferably about 100 nm.
The electron transport layer 7 is formed by a wet film forming method or a vacuum vapor deposition method in the same manner as the hole injection layer 3, but a vacuum vapor deposition method is usually used.
[8] Electron injection layer The electron injection layer 8 plays a role of efficiently injecting electrons injected from the cathode 9 into the light emitting layer 5. In order to efficiently perform electron injection, the material forming the electron injection layer 8 is preferably a metal having a low work function, and an alkali metal such as sodium or cesium, or an alkaline earth metal such as barium or calcium is used.
The film thickness of the electron injection layer 8 is preferably 0.1 to 5 nm.

Further, an ultrathin insulating film (thickness of about 0.1 to 5 nm) such _{as LiF, MgF 2} , Li ₂ O, Cs ₂ CO ₃ is inserted as an electron injection layer 8 at the interface between the cathode 9 and the electron transport layer 7. This is also an effective method for improving the efficiency of the device (Appl. Phys. Lett., Vol. 70, p. 152, 1997; Japanese Patent Application Laid-Open No. 10-74586; IEETrans. Electron. Devices, Vol. 44). , 1245, 1997; SID 04 Digist, p. 154).

Furthermore, alkali metals such as sodium, potassium, cesium, lithium, and rubidium are doped into organic electron transport materials represented by metal complexes such as nitrogen-containing heterocyclic compounds such as vasophenantroline and aluminum complexes of 8-hydroxyquinoline (). (Described in Japanese Patent Laid-Open No. 10-270171, Japanese Patent Laid-Open No. 2002-100478, Japanese Patent Application Laid-Open No. 2002-14482, etc.), electron injection and transportability are improved, and excellent film quality is achieved at the same time. It is preferable because it enables this. In this case, the film thickness is usually 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 a wet film forming method or a vacuum vapor deposition method in the same manner as the light emitting layer 5. In the case of the vacuum vapor deposition method, put the vapor deposition source in a crucible or metal boat installed in the vacuum vessel, ^{exhaust the inside of the vacuum vessel to about 10-4} Pa with an appropriate vacuum pump, and then remove the crucible or metal boat. It is heated and evaporated to form an electron injection layer on a substrate placed facing a crucible or metal boat.

The vapor deposition of the alkali metal is performed using an alkali metal dispenser filled with alkali metal chromate and a reducing agent in dichrome. By heating this dispenser in a vacuum vessel, the alkali metal chromate is reduced and the alkali metal is evaporated. When co-depositing an organic electron transport material and an alkali metal, put the organic electron transport material in a crucible installed in a vacuum vessel and exhaust the ^{inside of the vacuum vessel to about 10 -4 Pa with an appropriate vacuum pump.} , Each crucible and dispenser is simultaneously heated and evaporated to form an electron injection layer on a substrate placed facing the crucible and dispenser.
At this time, co-deposited uniformly in the film thickness direction of the electron injection layer 8, but there may be a concentration distribution in the film thickness direction.

[9] Cathode The cathode 9 plays a role of injecting electrons into a layer on the light emitting layer 5 side (electron injection layer 8 or light emitting layer 5 or the like).
As the material used for the cathode 9, the material used for the anode 2 can be used, but in order to efficiently inject electrons, a metal having a low work function is preferable, and tin, magnesium, indium, calcium, etc. Suitable metals such as aluminum and silver or alloys thereof are used. Specific examples include low work function alloy electrodes such as magnesium-silver alloys, magnesium-indium alloys, and aluminum-lithium alloys.

The film thickness of the cathode 9 is usually the same as that of the anode 2. For the purpose of protecting the cathode made of low work function metal, further laminating a metal layer having a high work function and being stable to the atmosphere increases the stability of the device. Metals such as aluminum, silver, copper, nickel, chromium, gold and platinum are used for this purpose.

[10] Other Constituent Layers Although the above description has focused on the element having the layer configuration shown in FIG. 1, the performance between the anode 2 and the cathode 9 and the light emitting layer 5 in the organic electroluminescent element of the present invention has been described. In addition to the layers described above, any layer may be provided, and any layer other than the light emitting layer 5 may be omitted as long as the above description is not impaired.

For example, it is also effective to provide an electron blocking layer between the hole transporting layer 4 and the light emitting layer 5 for the same purpose as the hole blocking layer 8. The electron blocking layer prevents electrons moving from the light emitting layer 5 from reaching the hole transport layer 4, thereby increasing the recombination probability with holes in the light emitting layer 5 and producing excitons. It has a role of confining it in the light emitting layer 5 and a role of efficiently transporting holes injected from the hole transport layer 4 toward the light emitting layer 5.

The characteristics required for the electron blocking layer include high hole transportability, a large energy gap (difference between HOMO and LUMO), and a high excited triplet level (T1). Further, when the light emitting layer 5 is formed by the wet film forming method, it is preferable to form the electron blocking layer by the wet film forming method because the device can be easily manufactured.
Therefore, it is preferable that the electron blocking layer also has wet film formation compatibility, and the material used for such an electron blocking layer is a copolymer of dioctylfluorene and triphenylamine represented by F8-TFB (international). Publication No. 2004/084260) and the like can be mentioned.

The structure opposite to that of FIG. 1, that is, the cathode 9, the electron injection layer 8, the electron transport layer 7, the hole blocking layer 6, the light emitting layer 5, the hole transport layer 4, and the hole injection layer 3 on the substrate 1. It is also possible to stack the anodes 2 in this order, and it is also possible to provide the organic electroluminescent device of the present invention between two substrates having at least one highly transparent substrate.
Further, it is also possible to have a structure in which a plurality of layers shown in FIG. 1 are stacked (a structure in which a plurality of light emitting units are stacked). _{In that case, if, for example, V 2} O ₅ or the like is used as the charge generation layer instead of the interface layer between the stages (between the light emitting units) (two layers when the anode is ITO and the cathode is Al), the barrier between the stages is used. Is less, which is more preferable from the viewpoint of luminous efficiency and drive voltage.

The present invention can be applied to any of a single element, an element having an array-arranged structure, and a structure in which an anode and a cathode are arranged in an XY matrix.

[Display equipment and lighting equipment]
The display device and the lighting device of the present invention use the organic electroluminescent element of the present invention as described above. The form and structure of the display device and the lighting device of the present invention are not particularly limited, and can be assembled according to a conventional method using the organic electroluminescent element of the present invention.
For example, the display device and the lighting device of the present invention by the method described in "Organic EL Display" (Ohmsha, published on August 20, 2004, by Shizushi Tokito, Chihaya Adachi, Hideyuki Murata). Can be formed.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

[Example 1]
The organic electroluminescent device shown in FIG. 1 was manufactured.
First, an ITO transparent conductive film was deposited on a glass substrate 1 to a thickness of 150 nm and patterned into stripes having a width of 2 mm to form an ITO anode 2 (manufactured by Sanyo Vacuum Co., Ltd., sputter-deposited product). Was washed in the order of ultrasonic cleaning with an aqueous solution of a surfactant, water washing with ultrapure water, ultrasonic cleaning with ultrapure water, and water washing with ultrapure water, then dried with compressed air and subjected to ultraviolet ozone cleaning.

Next, 2.0% by weight of the hole-transporting polymer compound having a repeating structure represented by the following (P1) and 4-isopropyl-4'-methyldiphenyliodonium tetrakis represented by the following (A1) (A1) An ethyl benzoate solution (composition for forming a hole injection layer) containing 0.8% by weight of pentafluorophenyl) borate was prepared.

The hole injection layer 3 having a film thickness of 40 nm is formed by applying this composition for forming a hole injection layer onto the ITO substrate by a spin coating method under the conditions shown below and further baking under the baking conditions shown below. Got
<Film formation conditions>
Spin coating atmosphere Bake conditions under atmospheric atmosphere At 230 ° C for 1 hour, then a 1 wt% cyclohexylbenzene solution (composition for forming a hole transport layer) of a hole transporting polymer compound represented by the following (H1). ) Was prepared, applied by spin coating on the hole injection layer 3 under the conditions shown below, and subjected to cross-linking treatment by baking to form a hole transport layer 4 having a film thickness of 10 nm.

<Film formation conditions>
Spin-coat atmosphere Baking conditions under a nitrogen atmosphere At 230 ° C. for 1 hour under a nitrogen atmosphere Next, when forming the light emitting layer 5, the light emitting material (D-1) and the charge transport material (h-1 to h-) shown below are used. 3) and dibutylhydroxytoluene (BHT) were used to prepare a composition for forming a light emitting layer having the composition shown below.

<Composition composition for forming a light emitting layer>
Solvent cyclohexylbenzene component concentration (D-1): 0.6% by weight
(H-1): 2.25% by weight
(H-2): 0.375% by weight
(H-3): 0.375% by weight
BHT: 0.01% by weight
On the day when this light emitting layer forming composition is prepared, this solution is applied onto the hole transport layer 4 by the spin coating method under the conditions shown below, and the bake treatment is performed under the bake conditions shown below. A light emitting layer 5 having a film thickness of 50 nm was formed.

<Film formation conditions>
Spin coating atmosphere Nitrogen atmosphere baking conditions Nitrogen atmosphere, 230 ° C, 10 minutes
Next, the substrate on which the hole injection layer 3, the hole transport layer 4 and the light emitting layer 5 are wet-deposited is carried into the vacuum vapor deposition apparatus, rough exhaust is performed, and then the degree of vacuum in the apparatus is used using a cryopump. Exhausted until the value was 3.0 × 10 ^{-4 Pa or less.} BAlq (CAS: 146162-54-1) was deposited on the light emitting layer 5 as a hole blocking material at a vapor deposition rate of 0.6 to 1.2 Å while the ^{degree of vacuum was maintained at 2.2 × 10 -4 Pa or less.} The hole blocking layer 6 was formed by laminating at a film thickness of 10 nm at / sec.

Next, while keeping the degree of vacuum at 2.2 × 10 ^-4 Pa or less, tris (8-hydroxyquinolinate) aluminum (Alq ₃ ) is heated on the hole blocking layer 6 to achieve a vapor deposition rate. The electron transport layer 7 was formed by laminating with a film thickness of 20 nm at 0.7 to 1.3 Å / sec.
Here, the element that had been vapor-deposited up to the electron transport layer 7 was conveyed from the organic layer vapor deposition chamber to the metal vapor deposition chamber. As a mask for cathode vapor deposition, a striped shadow mask having a width of 2 mm was installed in close contact with the element so as to be orthogonal to the ITO stripe of the anode 2. In the same manner as when the organic layer was vapor-deposited, the inside of the device was exhausted until the ^{degree of vacuum became 1.1 × 10 -4 Pa or less.}

Then, while the degree of vacuum ^{was maintained at 1.0 × 10 -4} Pa or less, lithium fluoride (LiF) was heated on the electron transport layer 7 using a molybdenum boat to achieve a vapor deposition rate of 0.07. The electron injection layer 8 was formed by laminating at a thickness of 0.5 nm at ~ 0.15 Å / sec. Next, in the same manner ^{, the aluminum is heated using a molybdenum boat while the degree of vacuum is maintained at 2.0 × 10 -4} Pa, so that the film is formed at a vapor deposition rate of 0.6 to 10.0 Å / sec. The cathode 9 was formed by thin-film deposition with a thickness of 80 nm. The substrate temperature at the time of vapor deposition of the electron injection layer 8 and the cathode 9 was maintained at room temperature.

Subsequently, in order to prevent the device from being deteriorated by moisture in the atmosphere during storage, the sealing process was carried out by the method described below.
In the nitrogen glove box, apply photocurable resin 30Y-437 (manufactured by ThreeBond) to the outer periphery of a glass plate with a size of 23 mm x 23 mm with a width of 1 mm, and apply a moisture getter sheet (manufactured by DYNIC) to the center. installed. A substrate on which the cathode had been formed was carried in, and the vapor-deposited surface was bonded so as to face the desiccant sheet. Then, only the region coated with the photocurable resin was irradiated with ultraviolet light to cure the resin.
As described above, an organic electroluminescent device having a light emitting area portion having a size of 2 mm × 2 mm was obtained.

[Example 2]
Examples except that the composition for forming a light emitting layer was stored and used for 2 weeks in a small environmental tester "SU-221" manufactured by ESPEC, which was heated to 60 ° C. before applying the composition for forming a light emitting layer. An organic electroluminescent element was obtained by using the same method as in 1.

[Comparative Example 1]
The same method as in Example 1 is used except that the composition for forming a light emitting layer is prepared using only the electroluminescent material (D-1), the charge transport material (h-1 to h-3), and cyclohexylbenzene. Obtained an organic electroluminescent device.

[Comparative Example 2]
The same method as in Example 2 is used except that the composition for forming a light emitting layer is prepared using only the electroluminescent material (D-1), the charge transport material (h-1 to h-3), and cyclohexylbenzene. Obtained an organic electroluminescent device.
For Examples 1 and 2 and Comparative Examples 1 and 2, constant current drive was performed using the current values at ^{the initial luminance of 5000 cd / m 2.} Regarding the relative ratio (L / L0,%) of the luminance to the initial luminance after 50 hours at that time, the difference (ΔL / L0) with respect to Comparative Example 1 is summarized in Table 1. Since there was almost no change in the drive life between Example 1 and Comparative Example 1, it was suggested that BHT did not affect the device characteristics. Further, by comparing Example 2 and Comparative Example 2, it was found that the storage stability of the composition for forming a light emitting layer at 60 ° C. was extremely good by adding BHT.

[Example 3]
In Example 1, the same operation was performed up to the formation of the hole transport layer 4. Next, when the light emitting layer 5 was formed, the same composition for forming a light emitting layer was used, and the film thickness was changed to 30 nm. Next, the substrate on which the hole injection layer 3, the hole transport layer 4 and the light emitting layer 5 are wet-deposited is carried into the vacuum vapor deposition apparatus, rough exhaust is performed, and then the degree of vacuum in the apparatus is used using a cryopump. Exhausted until the value was 3.0 × 10 ^{-4 Pa or less.} The fluorescent material D-2 and the charge transport material h-5 shown below are deposited on the light emitting layer 5 with a vacuum degree of 2.2 × 10 ^{-4 Pa or less, and the vapor deposition rate of h-5 is 0.} The light emitting layer 5-2 was formed by laminating the light emitting layer 5-2 with a film thickness of 10 nm while keeping the volume ratio at 0.8 to 1.2 Å / sec and adjusting the volume ratio of D-2 to h-5: D-2 = 100: 10. Formed. Then, the hole blocking layer, the electron transport layer, the electron injection layer, and the cathode were formed by the same method as in Example 1, and the sealing treatment was performed to obtain an organic electroluminescent device.

[Example 4]
Examples except that the composition for forming a light emitting layer was stored and used for 2 weeks in a small environmental tester "SU-221" manufactured by ESPEC, which was heated to 60 ° C. before applying the composition for forming a light emitting layer. An organic electroluminescent element was obtained by using the same method as in 3.

[Comparative Example 3]
The same method as in Example 3 is used except that the composition for forming a light emitting layer is prepared using only the electroluminescent material (D-1), the charge transport material (h-1 to h-3), and cyclohexylbenzene. Obtained an organic electroluminescent device.

[Comparative Example 4]
The same method as in Example 4 is used except that the composition for forming a light emitting layer is prepared using only the electroluminescent material (D-1), the charge transport material (h-1 to h-3), and cyclohexylbenzene. Obtained an organic electroluminescent device.
For Examples 3 and 4 and Comparative Examples 3 and 4, constant current driving with ^{a current density of 50 mA / cm 2 was performed.} Regarding the relative ratio (L / L0,%) of the luminance to the initial luminance after 50 hours at that time, the difference (ΔL / L0) when the comparative example 3 is used as a reference is summarized in Table 2. Since there is almost no change in the drive life between Example 3 and Comparative Example 3, it is suggested that BHT does not affect the device characteristics and also affects the light emission behavior of the adjacent layer. It was suggested that there was no such thing. Further, by comparing Example 4 and Comparative Example 4, by adding BHT, 60
It was found that the storage stability of the composition for forming a light emitting layer at ° C was extremely good.

[Example 5]
An organic electroluminescent device was obtained by using the same method as in Example 1 except that the light emitting material (D-3) shown below was used instead of the light emitting material (D-1).

[Example 6]
Examples except that the composition for forming a light emitting layer was stored and used for 2 weeks in a small environmental tester "SU-221" manufactured by ESPEC, which was heated to 60 ° C. before applying the composition for forming a light emitting layer. An organic electroluminescent element was obtained by using the same method as in 5.

[Comparative Example 5]
The same method as in Example 5 is used except that the composition for forming a light emitting layer is prepared using only the electroluminescent material (D-3), the charge transport material (h-1 to h-3), and cyclohexylbenzene. Obtained an organic electroluminescent device.

[Comparative Example 6]
The same method as in Example 6 is used except that the composition for forming a light emitting layer is prepared using only the electroluminescent material (D-3), the charge transport material (h-1 to h-3), and cyclohexylbenzene. Obtained an organic electroluminescent device.

[Comparative Example 7]
First, in the stage of storage in the small environmental tester "SU-221" manufactured by ESPEC Co., Ltd. heated to 60 ° C., the charge transport material (h-1 to h-3), BHT and cyclohexylbenzene are used only. Stored in the form of a liquid composition. After storage for 2 weeks, a light emitting material (D-3) was added to the composition so as to have the same concentration as the light emitting layer forming composition of Example 6, and the light emitting layer forming composition was prepared. An organic electroluminescent device was obtained by using the same method as in Example 6 except that the light emitting layer was formed by using the light emitting layer forming composition.

[Comparative Example 8]
First, at the stage of storage in the small environmental tester "SU-221" manufactured by ESPEC, which was heated to 60 ° C., the liquid was prepared using only the charge transport material (h-1 to h-3) and cyclohexylbenzene. It was stored in the state of the composition. After storage for 2 weeks, a light emitting material (D-3) was added to the composition so as to have the same concentration as the light emitting layer forming composition of Example 6, and the light emitting layer forming composition was prepared. An organic electroluminescent device was obtained by using the same method as in Example 6 except that the light emitting layer was formed by using the light emitting layer forming composition.

For Examples 5 and 6 and Comparative Examples 5 and 6, constant current drive was performed using the current values at ^{the initial luminance of 5000 cd / m 2.} Regarding the relative ratio (L / L0,%) of the brightness to the initial brightness after 50 hours at that time, the difference (ΔL / L0) when the comparative example 5 is used as a reference is summarized in Table 3. Since there was almost no change in the drive life between Example 5 and Comparative Example 5, it was suggested that BHT did not affect the element characteristics or had an effect of slightly extending the life. Further, by comparing Example 6 and Comparative Example 6, it was suggested that the storage stability of the composition for forming a light emitting layer at 60 ° C. was extremely good by adding BHT. Further, by comparing the results of Examples 1 and 2 and Comparative Examples 1 and 2 with the results of Table 3, it was suggested that the function could be changed even if the type of dopant was changed. Further, from Comparative Examples 7 and 8, when the material emitting phosphorescence is not present, the storage stability is not impaired regardless of the presence or absence of BHT. From this, it was found that it is particularly effective when it contains a phosphorescent material.

Code 1 Board code 2 Anode code 3 Hole injection layer code 4 Hole transport layer code 5 Light emitting layer code 6 Hole blocking layer code 7 Electron transport layer code 8 Electron injection layer code 9 Cathode

Claims (5)

The organic electroluminescent device hole injection layer, the light emitting layer has a hole transporting layer and the emitting layer in this order, at least one phosphorescent material, a composition containing a solvent and a phenolic antioxidant (except , The following liquid compositions 1, 2, 5, 6 and 7) are formed by wet film formation.
The hole injection layer is a wet composition containing a aromatic tertiary amine compound which is a polymer compound having a weight average molecular weight of 1000 or more and 1000000 or less, an electron accepting compound, and a solvent having a boiling point of 110 ° C. or more and 300 ° C. or less. It der shall be formed by deposition,
The phenolic antioxidant is butylhydroxytoluene (BHT) .
A method for forming an organic electroluminescent device.
[Liquid composition 1:
70 parts by weight of the following polymer compound 2, 30 parts by weight of the following phosphorescent material 1, 1 part by weight of 2,6-di-tert-butyl-4-methylphenol (BHT) as a phenolic antioxidant, and a solvent. A liquid composition prepared by adding 9899 parts by weight of cyclohexylbenzene and dissolving it at room temperature.
The liquid compositions 2, 5, 6 and 7 are the same as the liquid composition 1 except that the phenolic antioxidant and the solvent of the liquid composition 1 are changed to the table below.

Phosphorescent material 1:

Polymer compound 2: Polymer compound synthesized by the following method In a 1 L separable flask equipped with a stirring blade, baffle, cooling tube, and thermometer, 2,2'-(2,5-dihexyl-1,4) -Phenylene) -bis (4,4,5,5-tetramethyl- [1.3.2] -dioxaborolane) 16.44 g, 9,9'-bis (4-hexylphenyl) -2,7-dibromo 17.01 g of -9H-fluorene, 4.19 g of 2,4-bis (4-bromophenyl) -6- (4-n-dodecylphenyl) -1,3,5-triazine, and 446 g of toluene were charged. The air in the flask was replaced with nitrogen. The flask was immersed in an oil bath, heated to an internal temperature of 90 ° C., charged with 0.007 g of palladium acetate and 0.05 g of tri (o-methoxyphenyl) phosphine, and then 20% by weight of hydroxylation. 117 g of tetraethylammonium water was added dropwise over 1 hour. After stirring at an oil bath temperature of 100 ° C. for 5 hours, 0.40 g of phenylboric acid, 0.023 g of dichlorobistriphenylphosphine, and 117 g of 20% by weight tetraethylammonium hydroxide water were added, and the temperature of the oil bath was further increased. Was 100 ° C. and stirred for 15 hours. The reaction was cooled to room temperature and then diluted with toluene. Then, it was washed with 15% by weight of N, N-diethyldithiocarbamate sodium aqueous solution, and then washed with ion-exchanged water. After removing the water in the solution by azeotropic dehydration, the precipitated crystals were removed by filtration. The filtrate was washed with 10 wt% hydrochloric acid, 3 wt% aqueous ammonia, and ion-exchanged water, and then the filtrate was passed through a silica gel / alumina mixed column (the ratio of the weight of silica gel to the weight of alumina was 1). The liquid passed through the column was added dropwise to methanol, and the resulting polymer was filtered. The obtained polymer was washed with methanol and then dried to obtain 20 g of the polymer compound 2. ] The method for forming an organic electroluminescent device according to claim 1, wherein the phosphorescent material is a metal complex. The method for forming an organic electroluminescent device according to claim 2, wherein the metal complex is a metal complex containing a transition metal. A method for forming an organic EL display using the method for forming an organic electroluminescent device according to any one of claims 1 to 3. A method for forming organic EL lighting using the method for forming an organic electroluminescent device according to any one of claims 1 to 3.

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