JP5664128B2 - Pyrimidine compound, material for organic electroluminescence device, composition for organic electroluminescence device, organic electroluminescence device, lighting device and display device - Google Patents

Description

  The present invention relates to a pyrimidine compound, a material for an organic electroluminescent device comprising the compound, a composition for an organic electroluminescent device containing the compound and a solvent, an organic electroluminescent device having a high luminous efficiency and a low driving voltage, and the organic The present invention relates to a lighting device and a display device having an electroluminescent element.

  In recent years, electroluminescence devices using organic thin films (organic electroluminescence (EL) devices) have been developed. Examples of the method for forming the organic thin film in the organic electroluminescence device include a vacuum deposition method and a wet film formation method. Among these, the wet film-forming method does not require a vacuum process, is easy to increase in area, and a plurality of materials having various functions in a coating liquid (composition for an organic electroluminescent element) for forming one layer. There are advantages such as easy mixing and mixing.

Polymer materials such as poly (p-phenylene vinylene) derivatives and polyfluorene derivatives are mainly used as the material for the light emitting layer formed by the wet film formation method. There's a problem.
・ It is difficult to control the degree of polymerization and molecular weight distribution of polymer materials.
・ Deterioration due to terminal residues occurs during continuous driving.

・ High purity of the material itself is difficult and contains impurities.
Due to the above-described problems, an element using a wet film formation method is inferior in driving stability as compared with an element using a vacuum deposition method, and has not reached a practical level except for a part.
As an attempt to solve the above problems, Patent Document 1 uses an organic thin film formed by a wet film-forming method by mixing a plurality of low-molecular materials (charge transporting materials, light-emitting materials) instead of a polymer compound. Organic electroluminescent devices are described. However, since the organic electroluminescent element described in Patent Document 1 uses fluorescent light emission, the light emission efficiency and the maximum light emission luminance of the element are low, and the practical characteristics are not satisfied.

  In an organic electroluminescent device using an organic thin film made of a plurality of low-molecular materials formed by a wet film formation method, Non-Patent Document 1 describes a device using phosphorescence emission in order to increase the luminous efficiency of the device. ing. The charge transport material of the organic electroluminescence device described in Non-Patent Document 1 uses the following biphenyl derivative.

  However, the biphenyl derivative is very easy to crystallize, and it has been difficult to obtain a uniform amorphous film by the wet film formation method. Furthermore, the biphenyl derivative has low solubility in a solvent. For this reason, it is necessary to use a halogen-based solvent such as chloroform or 1,2-dichloroethane as a coating solvent, but the halogen-based solvent has a large environmental load and has a practical problem. In addition, since there is a high possibility that the material is deteriorated by impurities contained in the halogen-based solvent, it is conceivable that an element formed by a wet film formation method using a halogen-based solvent does not have sufficient driving stability.

  Patent Document 2 describes a charge transport material containing a quinoline ring and a carbazole ring in the molecule as described below. However, the organic electroluminescence device using the charge transport material has not been sufficiently driven.

Japanese Patent Laid-Open No. 11-238359 JP 2006-199677 A

Japanese Journal of Applied Physics Vol.44, No.1B, 2005, pp.626-629

  The present invention has been made in view of the above-described conventional situation, and provides an organic electroluminescent element material that is excellent in solubility in various organic solvents and excellent in electron transport properties, and further in driving stability. An object of the present invention is to provide an excellent composition for forming an organic electroluminescent element that can be driven at a low voltage, an organic electroluminescent element using the composition, an illuminating device having the organic electroluminescent element, and a display device. .

As a result of intensive studies by the present inventors, a pyrimidine compound having a specific structure is excellent in solubility in various solvents and has an amorphous property, so that a thin film can be formed by a wet film formation method and is excellent. It has been found that when it is used in an organic electroluminescence device, it has high charge stability and can be driven with a low drive voltage because of its charge transport property, and the present invention has been achieved.
That is, the gist of the present invention resides in the following (1) to ( 8 ). (1) A pyrimidine compound represented by the following general formula ( 3 ).

(In general formula ( 3 ), X and Z are each independently any one of 1-naphthyl group, 2-naphthyl group, and 9-phenanthryl group.
L ¹ and L ² are single bonds . )
(2) An organic battery comprising the pyrimidine compound described in (1) above and a solvent.
Composition for field light emitting device.
(3) An organic electroluminescence device having an anode, a cathode, and an organic layer between the anode and the cathode on a substrate, wherein the organic layer is a compound as described in (1) above as an organic electroluminescence device material An organic electroluminescent element comprising a layer containing
(4) In an organic electroluminescent device having an anode, a cathode, and an organic layer between the anode and the cathode on a substrate, the organic layer is an organic electric field according to (2) described above by a wet film formation method. An organic electroluminescent device comprising a layer formed using a composition for a light emitting device.
(5) The organic electroluminescent element according to (3), wherein the layer containing the material for an organic electroluminescent element is a light emitting layer.
(6) The organic electroluminescent device as described in (4) above, wherein the layer formed using the composition for organic electroluminescent device is a luminescent layer.
(7) A display device comprising the organic electroluminescent element according to any one of (3) to (6).
(8) An illuminating device comprising the organic electroluminescent element according to any one of (3) to (6).

Since the pyrimidine compound of the present invention is excellent in solubility in various solvents and has an amorphous property, it can be formed into a thin film by a wet film formation method and has excellent charge transport properties.
For this reason, using the pyrimidine compound of the present invention, it is possible to easily provide an organic electroluminescence device that is excellent in driving stability and can be driven with a low driving voltage.

It is typical sectional drawing which showed an example of the organic electroluminescent element of this invention.

Embodiments of the present invention will be described in detail below. However, the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the invention.
<Pyrimidine compound>
The pyrimidine compound of the present invention is represented by the following general formula (I).

(In General Formula (1), X and Z are each independently an aromatic ring group having 30 or less carbon atoms which may have a substituent.
L ¹ and L ² are each independently a single bond or an aromatic ring group having 30 or less carbon atoms which may have a substituent. )
[1] Structural features In the pyrimidine compound of the present invention represented by the general formula (1), it is essential that at least one of the 4-position and the 6-position of the pyrimidine ring is substituted with a p-biphenyl group. . It is considered that the electron transport property is excellent because at least one of the 4-position and the 6-position of the pyrimidine ring is substituted with a p-biphenyl group.
In addition, the 2-position and 6-position of the pyrimidine ring (when the 4-position of the pyrimidine ring is substituted with a p-biphenyl group) or the 4-position (when the 6-position of the pyrimidine ring is substituted with a p-biphenyl group) It is considered that the active site of the pyrimidine ring can be protected and the chemical and electrical stability can be enhanced by being substituted with a phenyl group having a substituent.

[2] Each component in General formula (1) Each component in the said General formula (1) is demonstrated in detail below.
<About X and Z>
X and Z in the general formula (1) are each independently an aromatic ring group having 30 or less carbon atoms which may have a substituent. In the present invention, the “aromatic ring group” means an aromatic hydrocarbon ring group and an aromatic heterocyclic group.

As the aromatic ring group for X and Z, those having 3 to 25 carbon atoms are preferred, and more specifically,
A phenyl group;
A naphthyl group such as a 1-naphthyl group and a 2-naphthyl group;
A phenanthryl group such as a 9-phenanthyl group and a 3-phenanthyl group;
Anthryl groups such as 1-anthryl group, 2-anthryl group, 9-anthryl group;
A naphthacenyl group such as a 1-naphthacenyl group and a 2-naphthacenyl group;
A chrycenyl group such as a 1-chrysenyl group, a 2-chrysenyl group, a 3-chrysenyl group, a 4-chrysenyl group, a 5-chrycenyl group, a 6-chrenyl group;
A pyrenyl group such as a 1-pyrenyl group;
A triphenylenyl group such as a 1-triphenylenyl group;
A coronenyl group such as a 1-coronenyl group;
Pyridyl groups such as 2-pyridyl group, 3-pyridyl group, 4-pyridyl group;
A thienyl group such as a 2-thienyl group;
A benzothienyl group such as a 3-benzothienyl group;
Benzofuranyl group such as 2-dibenzofuranyl group, 4-dibenzofuranyl group, quinolinyl group such as 2-quinolinyl group, etc.
Among them, aromatic hydrocarbon ring groups such as a phenyl group, a naphthyl group, a phenanthyl group, and an anthranyl group are more preferable.

  From the viewpoint of the stability of the compound, X and Z are more preferably a phenyl group, a 2-naphthyl group, a 1-naphthyl group, a 9-phenanthryl group, a 9-anthranyl group, and the like, and a phenyl group, a 1-naphthyl group, A 2-naphthyl group, a 9-phenanthryl group, and the like are particularly preferable from the viewpoint of easy purification of the compound, and a 1-naphthyl group, a 2-naphthyl group, and a 9-phenanthryl group are most preferable.

X and Z may have a substituent. Specific examples of the substituent include
An alkyl group having 1 to 20 carbon atoms;
An aromatic hydrocarbon ring group having 6 to 25 carbon atoms;
An aromatic heterocyclic group having 3 to 20 carbon atoms;
An alkyloxy group having 1 to 20 carbon atoms;
A (hetero) aryloxy group having 3 to 20 carbon atoms;
An alkylthio group having 1 to 20 carbon atoms;
A (hetero) arylthio group having 3 to 20 carbon atoms;
A cyano group etc. are mentioned.

These groups may further have a substituent, and specific examples thereof are the same as those exemplified as the substituents for X and Z.
As the substituent which X and Z have, an alkyl group having 1 to 20 carbon atoms and an aromatic hydrocarbon ring group having 6 to 25 carbon atoms are preferable in terms of stability of the compound, and aromatic carbonization having 6 to 25 carbon atoms. A hydrogen ring group is particularly preferred.

  Examples of the alkyl group having 1 to 20 carbon atoms as the substituent that X and Z may have include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an iso-butyl group, and a sec-butyl group. Group, tert-butyl group, hexyl group, octyl group, cyclohexyl group, decyl group, octadecyl group and the like are preferable, and methyl group, ethyl group, isopropyl group and the like are preferable. Among them, a methyl group, an ethyl group, and the like are preferable from the viewpoint of availability of raw materials and low cost, and an iso-butyl group, a sec-butyl group, a tert-butyl group, and the like have high solubility in nonpolar solvents. Therefore, it is preferable.

As an example of an aromatic hydrocarbon ring group having 6 to 25 carbon atoms as a substituent that X and Z may have,
A phenyl group;
A naphthyl group such as a 1-naphthyl group and a 2-naphthyl group;
A phenanthryl group such as a 9-phenanthyl group and a 3-phenanthyl group;
Anthryl groups such as 1-anthryl group, 2-anthryl group, 9-anthryl group;
A naphthacenyl group such as a 1-naphthacenyl group and a 2-naphthacenyl group;
A chrycenyl group such as a 1-chrysenyl group, a 2-chrysenyl group, a 3-chrysenyl group, a 4-chrysenyl group, a 5-chrycenyl group, a 6-chrenyl group;
A pyrenyl group such as a 1-pyrenyl group;
A triphenylenyl group such as a 1-triphenylenyl group;
A coronenyl group such as a 1-coronenyl group;
A biphenyl group such as a 4-biphenyl group or a 3-biphenyl group;
Examples thereof include terphenyl groups such as ortho-terphenyl group, meta-terphenyl group and para-terphenyl group. Among them, in terms of stability of the compound, phenyl group, 2-naphthyl group, 1-anthranyl group, 9-phenanthryl group, 9-anthranyl group, 4-biphenyl group,
A 3-biphenyl group and the like are preferable, and a phenyl group, a 2-naphthyl group, a 3-biphenyl group, and the like are particularly preferable from the viewpoint of easy purification of the compound.

As an example of an aromatic heterocyclic group having 3 to 20 carbon atoms as a substituent that X and Z may have,
A thienyl group such as a 2-thienyl group;
A furyl group such as a 2-furyl group;
An imidazolyl group such as a 2-imidazolyl group;
A pyridyl group such as a 2-pyridyl group;
Examples thereof include benzofuranyl groups such as 2-dibenzofuranyl group and 4-dibenzofuranyl group, and triazine-yl groups such as 1,3,5-triazin-2-yl group.

A dibenzofuranyl group is preferable from the viewpoint of the stability of the compound. Examples of the alkyloxy group having 1 to 20 carbon atoms as a substituent that X and Z may have include a methoxy group, an ethoxy group, and an isopropyloxy group. , A cyclohexyloxy group, an octadecyloxy group, and the like, and a methoxy group, an ethoxy group, and the like are preferable from the viewpoint of easy separation and purification of the compound.

Examples of the (hetero) aryloxy group having 3 to 20 carbon atoms as the substituent that X and Z may have include a phenoxy group, a 1-naphthyloxy group, a 9-anthranyloxy group, and 2-thienyloxy. A phenoxy group and the like are preferable from the viewpoint of solubility.
Examples of the alkylthio group having 1 to 20 carbon atoms as the substituent that X and Z may have include a methylthio group, an ethylthio group, an isopropylthio group, a cyclohexylthio group, etc. From the point of being easy to do, a methylthio group etc. are preferable.

Examples of the (hetero) arylthio group having 3 to 20 carbon atoms as a substituent that X and Z may have include a phenylthio group, a 1-naphthylthio group, a 9-anthranylthio group, and a 2-thienylthio group. From the viewpoint of solubility, a phenylthio group and the like are preferable.
In the present invention, from the viewpoint of stability of the compound, at least X is preferably an aromatic hydrocarbon ring group having 6 to 25 carbon atoms, and X and Z are aromatic hydrocarbon groups having 6 to 25 carbon atoms, respectively. It is more preferable that they are a cyclic group and a C3-C20 aromatic heterocyclic group.

<For ^{L 1} and ^{L 2>}
L ¹ in the general formula (1) is a substituent bonded to the phenyl group bonded to the 2-position of the pyrimidine ring, and L ² is substituted to the 4-position of the pyridine ring (the 6-position of the pyrimidine ring is substituted with a p-biphenyl group). Or a phenyl group that binds to the 6-position (when the 4-position of the pyrimidine ring is substituted with a p-biphenyl group). L ¹ and L ² are each a single bond or an aromatic ring group having 30 or less carbon atoms which may have a substituent.

The aromatic ring groups of L ¹ and L ² are preferably those having 3 to 25 carbon atoms, and more specifically, a phenylene group, naphthylene group, phenanthrylene group, anthrylene group, naphthacenylene group, chrysenylene group, pyrenylene group. , Triphenylenylene group, coronenylene group, pyridylene group, thienylene group, benzothienylene group, quinolinylene group, and the like. From the viewpoint of the stability of the compound, L ¹ and L ² are more preferably a phenylene group, a naphthylene group, a phenanthrylene group, an anthrylene group, or the like. Further, a phenylene group, a naphthylene group, and the like are particularly preferable from the viewpoint of ease of purification of the compound, and an m-phenylene group is most preferable from the viewpoints of solubility and narrow conjugation and transport of high triplet excitation energy.

L ¹ and L ² may have a substituent, and specific examples and preferred embodiments of the substituent are the same as the substituents of X and Z.
L ¹ and L ² of the present invention are preferably a single bond and a phenylene group, respectively, from the viewpoint of compound stability. In addition, L ¹ is more preferably a single bond from the standpoint of compound synthesis. As described above, L ¹ is a m-phenylene group from the viewpoint of solubility and transport of high triplet excitation energy by narrowing conjugation. It is also preferable.

The pyrimidine compound of the present invention is preferably a compound represented by the following general formula (3) from the viewpoint of solubility in an organic solvent.
Moreover, the compound represented by following General formula (4) is also preferable from the point which is excellent in electron transport property.

<About other substituents>
In the present invention, the partial structure represented by the following general formula (2) is referred to as the main skeleton of the pyrimidine compound of the present invention.

As long as the pyrimidine compound of the present invention does not impair the effects of the present invention, in the main skeleton,
In addition to the aforementioned -L ¹ -X and -L ² -Z, an optional substituent may be present, but from the viewpoint of compound stability, the substituent is a phenyl group or an alkyl group. Is preferred.
When the substituent that the main skeleton may further have is a phenyl group, the phenyl group may further have a substituent. In addition, about the specific example and preferable aspect of the substituent which the said phenyl group may have further, it is the same as that of what was mentioned as a substituent which said X and Z have.
When the substituent that the main skeleton may further have is an alkyl group, the alkyl group may further have a substituent. In addition, as a specific example of the substituent that the alkyl group may further have,
The C6-C25 aromatic hydrocarbon ring group;
The aromatic heterocyclic group having 3 to 20 carbon atoms;
The alkyloxy group having 1 to 20 carbon atoms;
The C3-20 (hetero) aryloxy group;
The alkylthio group having 1 to 20 carbon atoms;
The C3-20 (hetero) arylthio group;
Examples include the cyano group.

These groups may further have a substituent, and specific examples thereof are the same as those exemplified as the substituents for X and Z.
In view of ease of separation and purification, the pyrimidine compound of the present invention preferably has no substituent other than -L ¹ -X and -L ² -Z described above in the main skeleton. From the viewpoint of stability of the compound, those having a phenyl group, naphthyl group, phenanthryl group or the like as a substituent in addition to the aforementioned -L ¹ -X and -L ² -Z in the main skeleton are also preferred.

[3] Molecular Weight The upper limit of the molecular weight of the pyrimidine compound of the present invention is usually 5000 or less, preferably 3000 or less when considering the ease of purification of the compound, and particularly preferred when considering solubility in a solvent. Is 2000 or less, and most preferably 1000 or less when considering high purification by sublimation purification.

Further, the lower limit of the molecular weight of the pyrimidine compound of the present invention is usually 400 or more, and preferably 500 or more in consideration of the thermal stability of the compound.
[4] Glass Transition Temperature The pyrimidine compound of the present invention usually has a glass transition temperature of 90 ° C. or higher, but is preferably 100 ° C. or higher from the viewpoint of heat resistance.

[5] Illustrative compounds Specific examples of the pyrimidine compounds of the present invention are listed below, but the pyrimidine compounds of the present invention are not limited to the following exemplary compounds.

[6] Synthesis Method The pyrimidine compound of the present invention can be synthesized by performing a coupling reaction using a metal catalyst using 2,4,6-trichloropyrimidine as a starting material.
The pyrimidine compound of the present invention represented by the general formula (1) can be synthesized by, for example, the following method A.

Further, the pyrimidine compound of the present invention represented by the general formula (1) can also be synthesized by the following method B or C when L ¹ = L ² = single bond and X = Z.

(In said reaction formula, X is synonymous with X in General formula (1). Q represents a chlorine atom, a bromine atom, an iodine atom, or a trifluoromethanesulfonic acid ester group.)
The elementary reactions shown in the above scheme will be further described below.
<Pyrimidine ring formation reaction>
2 mol of a benzonitrile derivative and 1 mol of an acetylbiphenyl derivative are dissolved or suspended in an inert solvent in trifluoromethanesulfonic acid anhydride, and 1 to 5 mol of trifluoromethanesulfonic acid anhydride is slowly added dropwise, while stirring. By adding a temperature of ˜60 ° C., a mixture containing a pyrimidine ring is obtained. Purification of the substrate from this mixture can be performed by a combination of distillation, filtration, extraction, recrystallization, reprecipitation, suspension washing, and chromatographic operations.

The solvent is not particularly limited as long as it does not react with trifluoromethanesulfonic anhydride, but the reaction should be performed using a non-benzene nonpolar solvent such as hexane or cyclohexane, or a basic solvent such as dichloromethane or chloroform. Are preferred, and halogen solvents such as dichloromethane are particularly preferred.
<Coupling reaction>
1 mol of an aromatic boron reagent and 0.75 to 5 mol of a halide or trifluoromethanesulfonate ester reagent having a pyrimidine substrate are reacted in a nonpolar or polar solvent in the presence of a base using a transition metal element catalyst. Thus, a substrate-coupled mixture can be obtained. Purification of the target product from this mixture can be performed by a combination of operations of distillation, filtration, extraction, recrystallization, reprecipitation, suspension washing, and chromatography.

Examples of the transition metal element catalyst include an organic palladium catalyst, an organic nickel catalyst, an organic copper catalyst, an organic platinum catalyst, an organic rhodium catalyst, an organic ruthenium catalyst, and an organic iridium catalyst. Organic palladium catalysts are preferred.
The base is not particularly limited, but metal hydroxides, metal salts, organic alkali metal reagents and the like are preferable.

  The solvent to be used is not particularly limited as long as it is a solvent that is active with respect to the reaction substrate, but non-aromatic hydrocarbon solvents such as hexane, heptane, and cyclohexane, and aromatic carbonization such as benzene, toluene, and xylene. A hydrogen solvent, an ether solvent such as dimethoxyethane, tetrahydrofuran and dioxane, an alcohol solvent such as ethanol and propanol, water and the like can be used singly or in combination.

Further, if necessary, a surfactant can be added to the reaction system in an amount of 1 to 100 mol% based on the reaction substrate.
[7] Use of pyrimidine compound Since the pyrimidine compound of the present invention has high electron transport properties, it is suitable as an electron transport material for an electrophotographic photosensitive member, an organic electroluminescent device, a photoelectric conversion device, an organic solar cell, an organic rectifying device, and the like. Can be used for For example, the pyrimidine compound of the present invention is useful as a host material, particularly as a host material of a phosphorescent material, in a light emitting layer of an organic electroluminescent device. Moreover, since the pyrimidine compound of the present invention has a low ionization potential and a low electron affinity, it has a high electron transport property, and is very useful as a material used for, for example, a hole blocking layer described later.

In particular, the pyrimidine compound of the present invention can be used in the production of an organic electroluminescence device by vacuum deposition, and can be formed into a thin film by a wet film formation method. It is also suitable as a material for a light emitting element.
Therefore, if an organic electroluminescent element can be produced by a vacuum deposition method using the organic electroluminescent element material comprising the pyrimidine compound of the present invention, the organic electroluminescent element composition containing the pyrimidine compound of the present invention can be used. An organic electroluminescent element can also be produced by a wet film formation method.

The obtained organic electroluminescent element is excellent in driving stability and can be driven with a low driving voltage.
<Material for organic electroluminescence device>
The material for an organic electroluminescent element of the present invention is composed of the pyrimidine compound of the present invention, and is preferably dissolved in 2% by weight or more, more preferably 5% by weight or more in toluene.
As will be described later, an aromatic hydrocarbon is preferable as the solvent contained in the composition for organic electroluminescent elements. Toluene is listed as a representative example of aromatic hydrocarbons and is used as an indicator of solubility.

When the organic electroluminescent element material of the present invention has a solubility in toluene of 2% by weight or more, it is preferable that a layer constituting the organic electroluminescent element can be easily formed by a wet film forming method. The upper limit of the solubility is not particularly limited, but is usually about 50% by weight.
<Composition for organic electroluminescence device>
The composition for organic electroluminescent elements of the present invention contains the pyrimidine compound of the present invention, and usually contains the pyrimidine compound of the present invention and a solvent, and preferably further contains a light emitting material.

[1] Solvent The solvent contained in the composition for organic electroluminescent elements of the present invention is not particularly limited as long as the pyrimidine compound of the present invention which is a solute dissolves well.
Since the pyrimidine compound of the present invention has high solubility, various solvents can be applied. For example, aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene and tetralin; halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzene and trichlorobenzene; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene and anisole , Phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole and other aromatic ethers; phenyl acetate, phenyl propionate, methyl benzoate, benzoic acid Aromatic esters such as ethyl, propyl benzoate and n-butyl benzoate; ketones having an alicyclic ring such as cyclohexanone and cyclooctanone; aliphatic ketones such as methyl ethyl ketone and dibutyl ketone; methyl ethyl ketone and cyclohexano Alcohol having an alicyclic ring such as ruthenium or cyclooctanol; Aliphatic alcohol such as butanol or hexanol; Aliphatic ether such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether or propylene glycol-1-monomethyl ether acetate (PGMEA); Ethyl acetate In addition, aliphatic esters such as n-butyl acetate, ethyl lactate, and n-butyl lactate can be used. Of these, aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene, tetralin and the like are preferable in that they have low water solubility and are not easily altered.

Since organic electroluminescent devices use many materials such as cathodes that deteriorate significantly due to moisture, the presence of moisture in the composition causes moisture to remain in the dried film, degrading the device characteristics. The possibility is considered and it is not preferable.
Examples of the method for reducing the amount of water in the composition include nitrogen gas sealing, use of a desiccant, dehydration of the solvent in advance, use of a solvent having low water solubility, and the like. In particular, it is preferable to use a solvent having low water solubility because the solution film can prevent whitening by absorbing moisture in the atmosphere during the wet film forming process. From such a viewpoint, the composition for organic electroluminescent elements to which the present embodiment is applied includes, for example, a solvent having a water solubility at 25 ° C. of 1% by weight or less, preferably 0.1% by weight or less. It is preferable to contain 10% by weight or more in the composition.

  Further, in order to reduce a decrease in film formation stability due to solvent evaporation from the composition during wet film formation, the solvent of the composition for organic electroluminescent elements has a boiling point of 100 ° C. or higher, preferably 150 ° C. It is effective to use a solvent having a boiling point of 200 ° C. or higher, more preferably 200 ° C. or higher. In order to obtain a more uniform film, it is necessary for the solvent to evaporate from the liquid film immediately after the film formation at an appropriate rate. For this purpose, the boiling point is usually 80 ° C. or higher, preferably the boiling point is 100 ° C. or higher. It is more effective to use a solvent having a boiling point of 120 ° C. or higher, usually a boiling point of less than 270 ° C., preferably a boiling point of less than 250 ° C., more preferably a boiling point of less than 230 ° C.

A solvent that satisfies the above-described conditions, that is, the conditions of solute solubility, evaporation rate, and water solubility may be used alone, or two or more kinds of solvents may be mixed and used.
[2] Luminescent Material The composition for organic electroluminescent elements of the present invention preferably further contains a luminescent material. A luminescent material refers to the component which mainly light-emits in the composition for organic electroluminescent elements of this invention, and corresponds to the dopant component in an organic electroluminescent device. That is, the amount of light emitted from the composition for organic electroluminescent elements (unit: cd / m ² ) is usually 10 to 100%, preferably 20 to 100%, more preferably 50 to 100%, most preferably 80 to 80%. If 100% is identified as luminescence from a component material, it is defined as the luminescent material.

As the light-emitting material, known materials can be applied, and a fluorescent light-emitting material or a phosphorescent light-emitting material can be used alone or in combination, and a phosphorescent light-emitting material is preferable from the viewpoint of internal quantum efficiency.
When used in the composition for organic electroluminescent elements of the present invention, the maximum emission peak wavelength of the luminescent material is preferably in the range of 390 to 490 nm.

For the purpose of improving the solubility in a solvent, it is also important to reduce the symmetry and rigidity of the light emitting material molecule or introduce a lipophilic substituent such as an alkyl group.
Examples of fluorescent dyes that emit blue light include perylene, pyrene, anthracene, coumarin, p-bis (2-phenylethenyl) benzene, and derivatives thereof. Examples of the green fluorescent dye include quinacridone derivatives and coumarin derivatives. Examples of yellow fluorescent dyes include rubrene and perimidone derivatives. Examples of red fluorescent dyes include DCM compounds, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, azabenzothioxanthene and the like.

Examples of the phosphorescent material include organometallic complexes containing a metal selected from Groups 7 to 11 of the periodic table.
Preferred examples of the metal in the phosphorescent organometallic complex containing a metal selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. Preferred examples of these organometallic complexes include compounds represented by the following general formula (V) or formula (VI).

MQ _{(qj) Q'j} (V)
(In general formula (V), M represents a metal, q represents the valence of the metal, Q and Q ′ represent a bidentate ligand, and j represents 0, 1 or 2.)

(In the general formula (VI), ^{M d} represents a metal, ^.R 92 ^{to R 95} T is representative of the carbon or nitrogen independently represents a substituent. However, when T is ^{nitrogen, R 94} And there is no R ^95. )
Hereinafter, the compound represented by the general formula (V) will be described first.
In the general formula (V), M represents an arbitrary metal, and specific examples of preferable ones include the metals described above as the metal selected from Groups 7 to 11 of the periodic table.
Moreover, the bidentate ligands Q and Q ′ in the general formula (V) each represent a ligand having the following partial structure.

  As Q ', the following are particularly preferable from the viewpoint of the stability of the complex.

In the partial structures of Q and Q ′, the ring A1 represents an aromatic hydrocarbon group or an aromatic heterocyclic group, and these may have a substituent. Ring A2 represents a nitrogen-containing aromatic heterocyclic group, and these may have a substituent.
When the rings A1 and A2 have a substituent, preferred substituents include halogen atoms such as fluorine atoms; alkyl groups such as methyl groups and ethyl groups; alkenyl groups such as vinyl groups; methoxycarbonyl groups and ethoxycarbonyl groups. Alkoxycarbonyl groups; alkoxy groups such as methoxy groups and ethoxy groups; aryloxy groups such as phenoxy groups and benzyloxy groups; dialkylamino groups such as dimethylamino groups and diethylamino groups; diarylamino groups such as diphenylamino groups; carbazolyl groups; An acyl group such as an acetyl group; a haloalkyl group such as a trifluoromethyl group; a cyano group; an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, and a phenanthyl group.

  More preferable examples of the compound represented by the general formula (V) include compounds represented by the following general formulas (Va), (Vb), and (Vc).

(In the general formula (Va), M ^a represents the same metal as M, w represents the valence of the metal, and ring A1 represents an aromatic hydrocarbon group which may have a substituent. Ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

(In the general formula (Vb), M ^b represents the same metal as M, w represents the valence of the above metal, and ring A1 is an aromatic hydrocarbon group or substituted which may have a substituent. Represents an aromatic heterocyclic group which may have a group, and ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.)

(In general formula (Vc), M ^c represents the same metal as M, w represents the valence of the metal, and j represents 0, 1 or 2. Furthermore, ring A1 and ring A1 ′ are Each independently represents an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group, and ring A2 and ring A2 ′ are each independently Represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.
In the above general formulas (Va), (Vb), and (Vc), the group of ring A1 and ring A1 ′ is preferably, for example, phenyl group, biphenyl group, naphthyl group, anthryl group, thienyl group, furyl group, benzo Examples include thienyl group, benzofuryl group, pyridyl group, quinolyl group, isoquinolyl group, carbazolyl group and the like.

Further, the group of ring A2 and ring A2 ′ is preferably a pyridyl group, pyrimidyl group, pyrazyl group, triazyl group, benzothiazole group, benzoxazole group, benzimidazole group, quinolyl group, isoquinolyl group, quinoxalyl group, A phenanthridyl group and the like can be mentioned.
Furthermore, the substituents that the compounds represented by the general formulas (Va), (Vb), and (Vc) may have include halogen atoms such as fluorine atoms; alkyl groups such as methyl groups and ethyl groups; vinyls Alkenyl groups such as methoxy groups; alkoxycarbonyl groups such as methoxycarbonyl groups and ethoxycarbonyl groups; alkoxy groups such as methoxy groups and ethoxy groups; aryloxy groups such as phenoxy groups and benzyloxy groups; dialkyls such as dimethylamino groups and diethylamino groups An amino group; a diarylamino group such as a diphenylamino group; a carbazolyl group; an acyl group such as an acetyl group; a haloalkyl group such as a trifluoromethyl group; a cyano group;

  When the said substituent is an alkyl group, the carbon number is 1 or more and 6 or less normally. Furthermore, when the substituent is an alkenyl group, the carbon number is usually 2 or more and 6 or less. When the substituent is an alkoxycarbonyl group, the carbon number is usually 2 or more and 6 or less. Further, when the substituent is an alkoxy group, the carbon number is usually 1 or more and 6 or less. Moreover, when a substituent is an aryloxy group, the carbon number is 6 or more and 14 or less normally. Furthermore, when the substituent is a dialkylamino group, the carbon number is usually 2 or more and 24 or less. Further, when the substituent is a diarylamino group, the carbon number is usually 12 or more and 28 or less. Furthermore, when the substituent is an acyl group, the carbon number is usually 1 or more and 14 or less. Moreover, when a substituent is a haloalkyl group, the carbon number is 1 or more and 12 or less normally.

These substituents may be connected to each other to form a ring. As a specific example, a substituent of the ring A1 and a substituent of the ring A2 are bonded, or a substituent of the ring A1 ′ and a substituent of the ring A2 ′ are bonded. Two fused rings may be formed. Examples of such a condensed ring group include a 7,8-benzoquinoline group.
Among them, as a substituent of ring A1, ring A1 ′, ring A2 and ring A2 ′, more preferably an alkyl group, an alkoxy group, an aromatic hydrocarbon group, a cyano group, a halogen atom, a haloalkyl group, a diarylamino group, a carbazolyl group Is mentioned.

In general formula (Va), (Vb), preferably as ^{M a, M b, M c} in (Vc), ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold.
Specific examples of the organometallic complex represented by the general formula (V), (Va), (Vb) or (Vc) are shown below, but are not limited to the following compounds (in the following, Ph is phenyl Represents a group).

Among the organometallic complexes represented by the general formulas (V), (Va), (Vb), and (Vc), in particular, as the ligand Q and / or Q ′, a 2-arylpyridine-based ligand, , 2-arylpyridine, a compound having an arbitrary substituent bonded thereto, and a compound having an arbitrary group condensed thereto are preferable.
The compounds described in International Publication No. 2005/019373 pamphlet can also be used as the light emitting material.

Next, the compound represented by the general formula (VI) will be described. In the general formula (VI), M ^d represents a metal, and specific examples thereof include the metals described above as the metal selected from Groups 7 to 11 of the periodic table. Among these, ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold is preferable, and divalent metals such as platinum and palladium are particularly preferable.

In the general formula (VI), R ⁹² and R ⁹³ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, a cyano group, an amino group, an acyl group, an alkoxycarbonyl group, or a carboxyl group. Represents an alkoxy group, an alkylamino group, an aralkylamino group, a haloalkyl group, a hydroxyl group, an aryloxy group, an aromatic hydrocarbon ring group or an aromatic heterocyclic group.

Further, when T is carbon, R ⁹⁴ and R ⁹⁵ each independently represent a substituent represented by the same examples as R ⁹² and R ⁹³ . Further, as described above, when T is nitrogen, there are no R ⁹⁴ and R ⁹⁵ .
R ^{92 to} R ⁹⁵ may further have a substituent. In this case, the substituent which may further be present is not particularly limited, and any group can be used as the substituent.

Furthermore, R ^{92 to} R ⁹⁵ may be linked to each other to form a ring, and this ring may further have an arbitrary substituent.
Specific examples (T-1, T-10 to T-15) of the organometallic complex represented by the general formula (VI) are shown below, but are not limited to the following exemplified compounds. In the following, Me represents a methyl group, and Et represents an ethyl group.

[3] Other components In the composition for organic electroluminescent elements of the present invention, various other solvents may be contained as necessary in addition to the solvent and the light emitting material described above. Examples of such other solvents include amides such as N, N-dimethylformamide and N, N-dimethylacetamide, and dimethyl sulfoxide.

Moreover, various additives, such as a leveling agent and an antifoamer, may be included.
Further, when two or more layers are laminated by a wet film forming method, in order to prevent these layers from being compatible with each other, a photo-curing resin or a thermosetting resin is used for the purpose of curing and insolubilizing after film formation. Can also be contained.
[4] Material concentration and blending ratio in the composition for organic electroluminescent elements such as the pyrimidine compound of the present invention in the composition for organic electroluminescent elements, the luminescent material and components (leveling agents, etc.) that can be added as required The solid content concentration is usually 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, further preferably 0.5% by weight or more, and most preferably 1% by weight or more. It is usually 80% by weight or less, preferably 50% by weight or less, more preferably 40% by weight or less, further preferably 30% by weight or less, and most preferably 20% by weight or less. If this concentration is below the lower limit, it is difficult to form a thick film when forming a thin film, and if it exceeds the upper limit, it may be difficult to form a thin film.

  In the composition for organic electroluminescent elements of the present invention, the weight mixing ratio of the light emitting material / pyrimidine compound is usually 0.1 / 99.9 or more, more preferably 0.5 / 99.5 or more. More preferably 1/99 or more, most preferably 2/98 or more, usually 50/50 or less, more preferably 40/60 or less, still more preferably 30/70 or less, Most preferably, it is 20/80 or less. If this ratio falls below the lower limit or exceeds the upper limit, the luminous efficiency may be significantly reduced.

[5] Method for Preparing Composition for Organic Electroluminescent Device The composition for organic electroluminescent device of the present invention comprises the pyrimidine compound of the present invention, the light emitting material described above, and a leveling agent and antifoaming agent that can be added as necessary. It is prepared by dissolving a solute composed of various additives such as in an appropriate solvent. In order to shorten the time required for the dissolution step and to keep the solute concentration in the composition uniform, the solute is usually dissolved while stirring the liquid. The dissolution step may be performed at room temperature, but when the dissolution rate is slow, it can be heated and dissolved. After completion of the dissolution step, a filtration step such as filtering may be performed as necessary.

[6] Properties, physical properties, etc. of the composition for organic electroluminescent elements (moisture concentration)
When an organic electroluminescence device is produced by forming a layer by a wet film forming method using the composition for organic electroluminescence device of the present invention, a film formed when water is present in the composition for organic electroluminescence device to be used. Since moisture is mixed into the film and the uniformity of the film is impaired, the water content in the composition for organic electroluminescent elements of the present invention is preferably as low as possible. In general, since organic electroluminescent devices use many materials such as cathodes that deteriorate significantly due to moisture, when moisture is present in the composition for organic electroluminescent devices, moisture remains in the dried film. However, there is a possibility of deteriorating the characteristics of the element, which is not preferable.

Specifically, the amount of water contained in the composition for organic electroluminescent elements of the present invention is usually 1% by weight or less, preferably 0.1% by weight or less, more preferably 0.01% by weight or less.
As a method for measuring the moisture concentration in the composition for organic electroluminescent elements, the method described in Japanese Industrial Standard “Method for Measuring Moisture of Chemical Products” (JIS K0068: 2001) is preferable. For example, the Karl Fischer reagent method (JIS K0211). -1348) and the like.

(Uniformity)
The composition for organic electroluminescent elements of the present invention is preferably in a uniform liquid state at room temperature in order to enhance stability in a wet film forming process, for example, ejection stability from a nozzle in an ink jet film forming method. . The uniform liquid at normal temperature means that the composition is a liquid composed of a uniform phase and does not contain a particle component having a particle size of 0.1 μm or more in the composition.

(Physical properties)
Regarding the viscosity of the composition for organic electroluminescent elements of the present invention, when the viscosity is extremely low, for example, coating surface non-uniformity due to excessive liquid film flow in the film forming process, nozzle ejection failure in ink jet film formation, etc. are likely to occur. In the case of extremely high viscosity, nozzle clogging or the like in ink jet film formation is likely to occur. For this reason, the viscosity at 25 ° C. of the composition of the present invention is usually 2 mPa · s or more, preferably 3 mPa · s or more, more preferably 5 mPa · s or more, and usually 1000 mPa · s or less, preferably 100 mPa · s or less. More preferably, it is 50 mPa · s or less.

Further, when the surface tension of the composition for organic electroluminescence device of the present invention is high, the wettability of the film-forming liquid to the substrate is lowered, the leveling property of the liquid film is poor, and the film formation surface is disturbed during drying. Since problems such as being easy to occur may occur, the surface tension of the composition of the present invention at 20 ° C. is usually less than 50 mN / m, preferably less than 40 mN / m.
Furthermore, when the vapor pressure of the composition for organic electroluminescent elements of the present invention is high, problems such as changes in solute concentration due to evaporation of the solvent may easily occur. For this reason, the vapor pressure at 25 ° C. of the composition of the present invention is usually 50 mmHg or less, preferably 10 mmHg or less, more preferably 1 mmHg or less.

<Organic electroluminescent device>
The organic electroluminescent element of the present invention has an anode, a cathode, and an organic layer provided between both electrodes on a substrate, and the organic layer contains the pyrimidine compound of the present invention. . The layer containing the pyrimidine compound is preferably formed using the material for organic electroluminescent elements or the composition for organic electroluminescent elements of the present invention. The organic layer containing the pyrimidine compound of the present invention is preferably a light emitting layer. Furthermore, the layer containing the pyrimidine compound is preferably doped with an organometallic complex. As this organometallic complex, those exemplified as the light emitting material can be used.

Moreover, since the pyrimidine compound of the present invention has a low ionization potential and electron affinity and high electron transport, it is also preferable that the pyrimidine compound is contained in the hole blocking layer and the electron transport layer. Below, the layer structure of the organic electroluminescent element of this invention, its general formation method, etc. are demonstrated with reference to FIG.
FIG. 1 is a schematic cross-sectional view showing a structural example of an organic electroluminescent device according to the present invention. In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transport layer, 5 is a light emitting layer, 6 is a hole blocking layer, 7 is an electron transport layer, 8 is an electron injection layer, 9 represents each cathode.

  In the present invention, the wet film forming method includes, 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, ink jet method, screen printing. This method is a wet film formation method such as a method, a gravure printing method, or a flexographic printing method. Among these film forming methods, a spin coating method, a spray coating method, and an ink jet method are preferable. This is because the liquid property specific to the coating composition used in the organic electroluminescence device is matched.

[1] Substrate The substrate 1 serves as a support for the organic electroluminescence device, and a quartz or glass plate, a metal plate or 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, polysulfone or the like is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too small, the organic electroluminescent element may be deteriorated by the outside air that has passed through the substrate. For this reason, a method of providing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also a preferable method.

[2] Anode
The anode 2 serves to inject holes into the layer on the light emitting layer side.
This 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 It is composed of a conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline.

  In general, the anode 2 is often formed by a sputtering method, a vacuum deposition method, or the like. In addition, when forming the anode 2 using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, and conductive polymer fine powder, an appropriate binder resin solution It is also possible to form the anode 2 by dispersing it and applying it onto the substrate 1. Furthermore, in the case of a conductive polymer, a thin film can be directly formed on the substrate 1 by electrolytic polymerization, or the anode 2 can be formed by applying a conductive polymer on the substrate 1 (Appl. Phys. Lett. 60, 2711, 1992).

The anode 2 usually has a single-layer structure, but it can also have a laminated structure made of a plurality of materials if desired.
The thickness of the anode 2 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably 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. Furthermore, it is also possible to laminate different conductive materials on the anode 2 described above.

For the purpose of removing impurities adhering to the anode 2 and adjusting the ionization potential to improve the hole injection property, the surface of the anode 2 is treated with ultraviolet (UV) / ozone, or with oxygen plasma or argon plasma. It is preferable to do.
[3] Hole Injection Layer The hole injection layer 3 is a layer that transports 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 deposition method or a wet film formation method, and is not particularly limited, but the hole injection layer 3 is formed by a wet film formation method from the viewpoint of reducing dark spots. It is preferable.
The thickness of the hole injection layer 3 is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably 500 nm or less.

(Formation of hole injection layer by wet film formation method)
When forming the hole injection layer 3 by wet film formation, the material for forming the hole injection layer 3 is usually mixed with an appropriate solvent (hole injection layer solvent) to form a film-forming composition (positive A composition for forming a hole injection layer), and applying the composition for forming a hole injection layer on a layer (usually an anode) corresponding to the lower layer of the hole injection layer 3 by an appropriate technique. The hole injection layer 3 is formed by coating and drying.

(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 compound having a hole transporting property that is usually used in a hole injection layer of an organic electroluminescence device, and may be a polymer compound or the like, a monomer or the like. Although it may be a low molecular compound, it is preferably a high molecular compound.

  The hole transporting compound is preferably a compound having an ionization potential of 4.5 eV to 6.0 eV from the viewpoint of a charge injection barrier from the anode 2 to the hole injection layer 3. Examples of hole transporting compounds include aromatic amine derivatives, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, benzylphenyl derivatives, compounds in which tertiary amines are linked by a fluorene group, hydrazone derivatives, silazane derivatives, silanamines Derivatives, phosphamine derivatives, quinacridone derivatives, polyaniline derivatives, polypyrrole derivatives, polyphenylene vinylene derivatives, polythienylene vinylene derivatives, polyquinoline derivatives, polyquinoxaline derivatives, carbon and the like.

In the present invention, the derivative includes, for example, an aromatic amine derivative, and includes an aromatic amine itself and a compound having an aromatic amine as a main skeleton. It may be a mer.
The hole transporting compound used as the material for the hole injection layer 3 may contain any one of these compounds alone, or may contain two or more. When two or more hole transporting compounds are contained, the combination thereof is arbitrary, but one or more aromatic tertiary amine polymer compounds and one or two other hole transporting compounds are used. It is preferable to use the above in combination.

Among the above examples, an aromatic amine compound is preferable from the viewpoint of amorphousness and visible light transmittance, and an aromatic tertiary amine compound is particularly preferable. Here, the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and includes a compound having a group derived from an aromatic tertiary amine.
The type of the aromatic tertiary amine compound is not particularly limited, but from the viewpoint of uniform light emission due to the surface smoothing effect, a polymer compound having a weight average molecular weight of 1,000 or more and 1,000,000 or less (a polymerizable compound in which repeating units are linked) is further included. preferable. Preferable examples of the aromatic tertiary amine polymer compound include a polymer compound having a repeating unit represented by the following formula (I).

(In Formula (I), Ar ¹ and Ar ² each independently represent an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. Ar ^{3 to} Ar ⁵ each independently represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. Represents a linking group selected from the group of linking groups, and two groups bonded to the same N atom among Ar ^{1 to} Ar ⁵ may be bonded to each other to form a ring.

(In said each formula, Ar < ⁶ > -Ar < ¹⁶ > represents each independently the aromatic hydrocarbon group which may have a substituent, or the aromatic heterocyclic group which may have a substituent. R ³¹ and R ³² each independently represent a hydrogen atom or an arbitrary substituent.)
As the aromatic hydrocarbon group and the aromatic heterocyclic group of Ar ^{1 to} Ar ¹⁶ , a benzene ring, a naphthalene ring, a phenanthrene ring, a thiophene from the viewpoint of the solubility, heat resistance, hole injection / transport property of the polymer compound A group derived from a ring or a pyridine ring is preferred, and a group derived from a benzene ring or a naphthalene ring is more preferred.

The aromatic hydrocarbon group and aromatic heterocyclic group of Ar ^{1 to} Ar ¹⁶ may further have a substituent. The molecular weight of the substituent is usually 400 or less, preferably about 250 or less. As the substituent, an alkyl group, an alkenyl group, an alkoxy group, an aromatic hydrocarbon group, an aromatic heterocyclic group and the like are preferable.
When R ³¹ and R ³² are optional substituents, examples of the substituent include alkyl groups, alkenyl groups, alkoxy groups, silyl groups, siloxy groups, aromatic hydrocarbon groups, aromatic heterocyclic groups, and the like. .

Specific examples of the aromatic tertiary amine polymer compound having a repeating unit represented by the formula (I) include those described in International Publication No. 2005/089024.
In addition, as a hole transporting compound, a conductive polymer (PEDOT / PSS) obtained by polymerizing 3,4-ethylenedioxythiophene, which is a derivative of polythiophene, in high molecular weight polystyrene sulfonic acid. Is also preferred. Moreover, 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 mass or more, preferably in terms of film thickness uniformity. Is 0.1% by mass or more, more preferably 0.5% by mass or more, and is usually 70% by mass or less, preferably 60% by mass or less, more preferably 50% by mass or less. If this concentration is too high, film thickness unevenness may occur, and if it is too low, defects may occur in the formed hole injection layer.

(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. Here, the electron-accepting compound is preferably a compound having an oxidizing power and the ability to accept one electron from the above-described hole-transporting compound, and specifically, a compound having an electron affinity of 4 eV or more is preferable. A compound that is a compound of 5 eV or more is more preferable.

Examples of such electron-accepting compounds include triarylboron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of arylamines and metal halides, and salts of arylamines and Lewis acids. Examples thereof include one or more compounds selected from the group. More specifically, an onium salt substituted with an organic group such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate and triphenylsulfonium tetrafluoroborate (International Publication No. WO 2005/089024); High valent inorganic compounds such as iron (III) chloride (Japanese Patent Laid-Open No. 11-251067), ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene, tris (pendafluorophenyl) borane (Japanese Patent Laid-Open No. 2003-31365) Aromatic boron compounds such as); fullerene derivatives; iodine; sulfonate ions such as polystyrene sulfonate ions, alkylbenzene sulfonate ions, camphor sulfonate ions, and the like.

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

(Other components)
As a material for the hole injection layer, other components may be further contained in addition to the above-described hole transporting compound and electron accepting compound as long as the effects of the present invention are not significantly impaired. Examples of other components include various light emitting materials, electron transporting compounds, binder resins, and coating property improving agents. In addition, only 1 type may be used for another component and it may use 2 or more types together by arbitrary combinations and a ratio.

(solvent)
At least one of the solvents of the composition for forming a hole injection layer used in the wet film formation method is preferably a compound that can dissolve the constituent material of the hole injection layer. The boiling point of this solvent is usually 110 ° C. or higher, preferably 140 ° C. or higher, more preferably 200 ° C. or higher, and usually 400 ° C. or lower, preferably 300 ° C. or lower. If the boiling point of the solvent is too low, the drying speed is too high and the film quality may be deteriorated. Further, if the boiling point of the solvent is too high, it is necessary to increase the temperature of the drying process, and there is a possibility of adversely affecting other layers and the substrate.

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

Examples of the ester solvent include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate.
Examples of the aromatic hydrocarbon solvent include toluene, xylene, cyclohexylbenzene, 3-isopropylpropylphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, cyclohexylbenzene, and methylnaphthalene. Can be mentioned.

Examples of the amide solvent include N, N-dimethylformamide and N, N-dimethylacetamide.
In addition, dimethyl sulfoxide and the like can also be used.
These solvent may use only 1 type and may use 2 or more types by arbitrary combinations and a ratio.

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

Although the relative humidity in a film-forming process is not limited unless the effect of this invention is impaired remarkably, it is 0.01 ppm or more normally and 80% or less normally.
After the film formation, the film of the composition for forming a hole injection layer is usually dried by heating or the like. Examples of the heating means used in the heating step include a clean oven, a hot plate, infrared rays, a halogen heater, microwave irradiation and the like. Among them, a clean oven and a hot plate are preferable in order to uniformly apply heat to the entire film.

  The heating temperature in the heating step is preferably heated at a temperature equal to or higher than the boiling point of the solvent used in the composition for forming a hole injection layer as long as the effects of the present invention are not significantly impaired. In the case of a mixed solvent containing two or more types of solvents used in the hole injection layer, at least one type is preferably heated at a temperature equal to or higher than the boiling point of the solvent. In consideration of an increase in the boiling point of the solvent, the heating step is preferably performed at 120 ° C. or higher, preferably 410 ° C. or lower.

  In the heating step, the heating time is not limited as long as the heating temperature is not lower than the boiling point of the solvent of the composition for forming a hole injection layer and sufficient insolubilization of the coating film does not occur. Is less than a minute. If the heating time is too long, the components of the other layers tend to diffuse, and if it is too short, the hole injection layer tends to be inhomogeneous. Heating may be performed in two steps.

(Formation of hole injection layer by vacuum evaporation)
When the hole injection layer 3 is formed by vacuum deposition, one or more of the constituent materials of the hole injection layer 3 (the aforementioned hole transporting compound, electron accepting compound, etc.) are placed in a vacuum container. Put in crucibles installed (in case of using two or more materials, put them in each crucible), evacuate the inside of the vacuum vessel to about 10 ⁻⁴ Pa with a suitable vacuum pump, and then heat the crucible (two types When using the above materials, heat each crucible) and evaporate by controlling the amount of evaporation (when using two or more materials, evaporate by independently controlling the amount of evaporation) and face the crucible Then, the hole injection layer 3 is formed on the anode 2 of the substrate placed on the substrate. In addition, when using 2 or more types of materials, the hole injection layer 3 can also be formed by putting those mixtures into a crucible, heating and evaporating.

The degree of vacuum at the time of vapor deposition is not limited as long as the effects of the present invention are not significantly impaired, but usually 0.1 × 10 ⁻⁶ Torr (0.13 × 10 ⁻⁴ Pa) or more, usually 9.0 × 10 ⁻⁶ Torr. (12.0 × 10 ⁻⁴ Pa) or less. The deposition rate is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 Å / second or more and usually 5.0 Å / second or less. The film forming temperature at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 10 ° C. or higher, preferably 50 ° C. or lower.

[4] Hole transport layer The hole transport layer 4 according to the present invention may be formed by either a vacuum deposition method or a wet film formation method, and is not particularly limited. It is preferably formed by a wet film formation method.
The hole transport layer 4 can be 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. The organic electroluminescent device of the present invention may have a configuration in which the hole transport layer is omitted.

  The material for forming the hole transport layer 4 is preferably a material having high hole transportability and capable of efficiently transporting injected holes. Therefore, it is preferable that the ionization potential is small, the transparency to visible light is high, the hole mobility is large, the stability is high, and impurities that become traps are not easily generated during manufacturing or use. In many cases, it is preferable not to quench the light emitted from the light emitting layer 5 or to form an exciplex with the light emitting layer 5 to reduce the efficiency because it is in contact with the light emitting layer 5.

  Such a material for the hole transport layer 4 may be any material conventionally used as a constituent material for the hole transport layer. For example, the hole transport property used for the hole injection layer 3 described above. What was illustrated as a compound is mentioned. 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, silole derivatives, oligothiophene derivatives, condensed polycyclic aromatics Group derivatives, metal complexes and the like.

  In addition, for example, polyvinylcarbazole derivatives, polyarylamine derivatives, polyvinyltriphenylamine derivatives, polyfluorene derivatives, polyarylene derivatives, polyarylene ether sulfone derivatives containing tetraphenylbenzidine, polyarylene vinylene derivatives, polysiloxane derivatives, polythiophenes Derivatives, poly (p-phenylene vinylene) derivatives, and the like. These may be any of an alternating copolymer, a random polymer, a block polymer, or a graft copolymer. Further, it may be a polymer having a branched main chain and three or more terminal portions, or a so-called dendrimer.

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

(In formula (II), 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, for example, a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, and acenaphthene. Examples thereof include a group derived from a 6-membered monocyclic ring or a 2-5 condensed ring, such as a ring, a fluoranthene ring, and a fluorene ring, and a group in which two or more rings are connected by a direct bond.

  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 pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, and a carbazole ring. , Pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzoisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine Ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring, etc. Or a group and the rings of from 2-4 fused rings include groups formed by connecting a direct bond or two or more rings.

From the viewpoints of solubility and heat resistance, Ar ^a and Ar ^b are each independently selected from the group consisting of a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, triphenylene ring, pyrene ring, thiophene ring, pyridine ring, and fluorene ring. A group derived from a selected ring or a group formed by linking two or more benzene rings (for example, a biphenyl group or a terphenyl group) is preferable. Among these, a group derived from a benzene ring (phenyl group), a group formed by connecting two benzene rings (biphenyl group), and a group derived from a fluorene ring (fluorenyl group) are preferable.

Examples of the substituent 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. 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 siloxy 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 formula (II) is used as its repeating unit. The polymer which has is mentioned.
As the polyarylene derivative, a polymer having a repeating unit composed of the following formula (III-1) and / or the following formula (III-2) is preferable.

(In formula (III-1), 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, Represents an alkoxyphenyl group, an alkylcarbonyl group, an alkoxycarbonyl group, or a carboxy group, and t and s each independently represent an integer of 0 to 3. When t or s is 2 or more, a plurality of molecules included 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 the formula (III-2), R ^e and R ^f are independently the same as R ^a , R ^b , R ^c or R ^d in the formula (III-1). Independently, it represents an integer of 0 to 3. When r or u is 2 or more, a plurality of R ^e and R ^f contained in one molecule may be the same or different, and adjacent R ^e or R ^f may form a ring, and X represents an atom or a group of atoms constituting a 5-membered ring or a 6-membered ring.)
Specific examples of X include an oxygen atom, a boron atom which may have a substituent, a nitrogen atom which may have a substituent, a silicon atom which may have a substituent, and a substituent. A phosphorus atom which may be substituted, a sulfur atom which may have a substituent, a carbon atom which may have a substituent, or a group formed by bonding these.

Further, the polyarylene derivative has a repeating unit represented by the following formula (III-3) in addition to the repeating unit consisting of the above formula (III-1) and / or the above formula (III-2). Is preferred.

(In formula (III-3), Ar ^{c to} Ar ^j may each independently have a substituent,
Represents an aromatic hydrocarbon group or an aromatic heterocyclic group. v and w each independently represent 0 or 1. )
Specific examples of Ar ^{c to} Ar ^j are the same as Ar ^a and Ar ^b in the formula (II).

Specific examples of the above formulas (III-1) to (III-3) and specific examples of polyarylene derivatives include those described in JP-A-2008-98619.
In the case of forming the hole transport layer 4 by a wet film formation method, a composition for forming a hole transport layer is prepared in the same manner as the formation of the hole injection layer 3 and then heated and dried after the wet film formation. .
The composition for forming a hole transport layer contains a solvent in addition to the above hole transport compound. The solvent used is the same as that used for the composition for forming a hole injection layer. The film forming conditions, heat drying conditions, and the like are the same as in the case of forming the hole injection layer 3.

In the case where the hole transport layer is formed by the vacuum deposition method, the film forming conditions are the same as those in the case of forming the hole injection layer 3.
The hole transport layer 4 may contain various light emitting materials, electron transport compounds, binder resins, coating property improving agents, and the like in addition to the hole transport compound.
The hole transport layer 4 may be a layer formed by crosslinking a crosslinkable compound. The crosslinkable compound is a compound having a crosslinkable group, and forms a network polymer compound by crosslinking.

Examples of this crosslinkable group include groups derived from cyclic ethers such as oxetane and epoxy; groups derived from unsaturated double bonds such as vinyl, trifluorovinyl, styryl, acrylic, methacryloyl and cinnamoyl; benzo Examples include groups derived from cyclobutene.
The crosslinkable compound may be any of a monomer, an oligomer, and a polymer. The crosslinkable compound may have only 1 type, and may have 2 or more types by arbitrary combinations and ratios.

  As the crosslinkable compound, a hole transporting compound having a crosslinkable group is preferably used. Examples of the hole transporting compound include those exemplified above, and those having a crosslinkable group bonded to the main chain or side chain with respect to these hole transporting compounds. In particular, the crosslinkable group is preferably bonded to the main chain via a linking group such as an alkylene group. In particular, the hole transporting compound is preferably a polymer containing a repeating unit having a crosslinkable group, and the above formula (II) and formulas (III-1) to (III-3) can be used as a crosslinkable group. Is preferably a polymer having a repeating unit bonded directly or via a linking group.

  As the crosslinkable compound, a hole transporting compound having a crosslinkable group is preferably used. 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, porphyrin derivatives; triphenylamine derivatives Silole derivatives; oligothiophene derivatives, condensed polycyclic aromatic derivatives, metal complexes and the like. Among them, nitrogen-containing aromatic derivatives such as pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, carbazole derivatives; triphenylamine derivatives, silole derivatives, condensed polycyclic aromatic derivatives, metal complexes, etc. Particularly preferred are triphenylamine derivatives.

In order to form the hole transport layer 4 by crosslinking the crosslinkable compound, a composition for forming a hole transport layer in which the crosslinkable compound is dissolved or dispersed in a solvent is usually prepared and deposited by wet film formation. To crosslink.
The composition for forming a hole transport layer may contain an additive for promoting a crosslinking reaction in addition to the crosslinking compound. Examples of additives that accelerate the crosslinking reaction include polymerization initiators and polymerization accelerators such as alkylphenone compounds, acylphosphine oxide compounds, metallocene compounds, oxime ester compounds, azo compounds, onium salts; condensed polycyclic hydrocarbons, Examples thereof include photosensitizers such as porphyrin compounds and diaryl ketone compounds.

Further, it may contain a coating property improving agent such as a leveling agent and an antifoaming agent; an electron accepting compound; a binder resin and the like.
In the composition for forming a hole transport layer, the crosslinkable compound is usually 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and usually 50% by mass or less. , Preferably it is 20 mass% or less, More preferably, it contains 10 mass% or less.

After forming a composition for forming a hole transport layer containing a crosslinkable compound at such a concentration on the lower layer (usually the hole injection layer 3), the composition is crosslinked by heating and / or irradiation with electromagnetic energy such as light. Are crosslinked to form a network polymer compound.
Conditions such as temperature and humidity during film formation are the same as those during the wet film formation of the hole injection layer 3.
The heating method after film formation is not particularly limited. The heating temperature condition is usually 120 ° C. or higher,
Preferably it is 400 degrees C or less.

The heating time is usually 1 minute or longer, preferably 24 hours or shorter. The heating means is not particularly limited, and means such as placing a laminated body having a deposited layer on a hot plate or heating in an oven is used. For example, conditions such as heating on a hot plate at 120 ° C. or more for 1 minute or more can be used.
In the case of irradiation with electromagnetic energy such as light, a method of irradiating directly using an ultraviolet / visible / infrared light source such as an ultra-high pressure mercury lamp, a high-pressure mercury lamp, a halogen lamp, an infrared lamp, etc. Examples include a mask aligner and a method of irradiation using a conveyor type light irradiation device. In electromagnetic energy irradiation other than light, for example, there is a method of irradiation using a device that irradiates a microwave generated by a magnetron, a so-called microwave oven.

As the irradiation time, it is preferable to set conditions necessary for reducing the solubility of the film, but irradiation is usually performed for 0.1 seconds or longer, preferably 10 hours or shorter.
Heating and irradiation of electromagnetic energy such as light may be performed individually or in combination. When combined, the order of implementation is not particularly limited.
The film thickness of the hole transport layer 4 thus formed is usually 5 nm or more, preferably 10 nm or more, and is usually 300 nm or less, preferably 100 nm or less.

[5] Light emitting layer When the hole injection layer 3 or the hole transport layer 4 is provided, the light emitting layer 5 is provided on the hole transport layer 4. The light emitting layer 5 is a layer that is excited by recombination of holes injected from the anode 2 and electrons injected from the cathode 9 between electrodes to which an electric field is applied, and becomes a main light emitting source.

(Light emitting layer material)
The light emitting layer 5 contains at least a material having a light emitting property (light emitting material) as a constituent material, and preferably a compound having a hole transporting property (hole transporting compound) or an electron transport. A compound (electron transporting compound) having the following properties: A light emitting material may be used as a dopant material, and a hole transporting compound, an electron transporting compound, or the like may be used as a host material. There is no particular limitation on the light-emitting material, and a substance that emits light at a desired light emission wavelength and has high light emission efficiency may be used. In the present invention, the above-described light-emitting material is preferably used. On the other hand, it is preferable to use the pyrimidine compound of the present invention as a host material, particularly an electron transporting compound.

In particular, in the organic electroluminescent element of the present invention, the light emitting layer is preferably formed by a wet film forming method using the composition for organic electroluminescent element of the present invention.
Furthermore, the light emitting layer 5 may contain other components as long as the effects of the present invention are not significantly impaired. In addition, when forming the light emitting layer 5 with a wet film-forming method, it is preferable to use a low molecular weight material (molecular weight is usually 10,000 or less, preferably 5000 or less).

<Formation of light emitting layer>
When the light emitting layer 5 is formed by a wet film forming method, the material used for the light emitting layer is dissolved in an appropriate solvent to form a composition for forming a light emitting layer (in the case of containing the pyrimidine compound of the present invention, a composition for an organic electroluminescent element). ) Is prepared, and a film is formed using it.
As the light-emitting layer solvent to be contained in the light-emitting layer forming composition for forming the light-emitting layer 5 by a wet film forming method, the solvent described in the above-mentioned organic electroluminescent element composition of the present invention is used. It is the same.

Further, as the solid content concentration of the light emitting material, the charge transporting compound, etc. in the composition for forming the light emitting layer,
Usually 0.01% by mass or more and usually 70% by mass or less. If this concentration is too large, film thickness unevenness may occur, and if it is too small, defects may occur in the film.
After wet-deposition of the composition for forming a light emitting layer, the resulting coating film is dried and the solvent is removed to form a light emitting layer. Specifically, it is the same as the method described in the formation of the hole injection layer. The method of the wet film forming method is not limited as long as the effect of the present invention is not significantly impaired, and any of the methods described above can be used.

The thickness of the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 3 nm or more, preferably 5 nm or more, and usually 200 nm or less, preferably 100 nm or less. If the thickness of the light emitting layer 5 is too thin, defects may occur in the film, and if it is too thick, the driving voltage may increase.
[6] Hole blocking layer In the organic electroluminescent element of the present invention, it is preferable to provide a hole blocking layer 6 between the light emitting layer 5 and an electron injection layer 8 described later. The hole blocking layer 6 is a layer laminated on the light emitting layer 5 so as to be in contact with the interface of the light emitting layer 5 on the cathode 9 side.

The hole blocking layer 6 has a role of blocking holes moving from the anode 2 from reaching the cathode 9 and a role of efficiently transporting electrons injected from the cathode 9 toward the light emitting layer 5. Have
The physical properties required for the material constituting the hole blocking layer 6 include high electron mobility, low hole mobility, a large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). Is high.

  Examples of the material for the hole blocking layer satisfying such conditions include bis (2-methyl-8-quinolinolato) (phenolato) aluminum, bis (2-methyl-8-quinolinolato) (triphenylsilanolato) aluminum, and the like. Mixed metal complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolinato) aluminum binuclear metal complexes, distyrylbiphenyl derivatives, etc. Triazole derivatives such as styryl compounds (JP-A-11-242996), 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4-triazole (JP-A-7 -41759), phenanthroline derivatives such as bathocuproine (JP-A-10-79297), and the like. That. Furthermore, the pyrimidine compound of the present invention and the compound having at least one pyridine ring substituted at the 2,4,6-position described in WO 2005/022962 are also preferable as the material for the hole blocking layer 6. The pyrimidine compound of the present invention is more preferable because of its low ionization potential and electron affinity and high electron transport properties.

In addition, the material of the hole-blocking layer 6 may use only 1 type, and may use 2 or more types together by arbitrary combinations and ratios.
There is no restriction | limiting in the formation method of the hole-blocking layer 6. FIG. Therefore, it can be formed by a wet film formation method, a vacuum deposition method, or other methods.
The thickness of the hole blocking layer 6 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less. is there.

Further, a hole relaxation layer may be provided instead of the hole blocking layer.
[7] Electron Transport Layer An electron transport layer 7 may be provided between the light emitting layer 5 and an electron injection layer 8 described later.
The electron transport layer 7 is provided for the purpose of further improving the light emission efficiency of the device, and efficiently transports electrons injected from the cathode 9 between the electrodes to which an electric field is applied in the direction of the light emitting layer 5. Formed from a compound capable of

  As an electron transport compound used for the electron transport layer 7, usually, the electron injection efficiency from the cathode 9 or the electron injection layer 8 is high, and the injected electrons are transported efficiently with high electron mobility. The compound which can be used is used. Examples of the compound satisfying such conditions include metal complexes such as pyrimidine compounds of the present invention and aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), metals of 10-hydroxybenzo [h] quinoline. Complex, oxadiazole derivative, distyrylbiphenyl derivative, silole derivative, 3-hydroxyflavone metal complex, 5-hydroxyflavone metal complex, benzoxazole metal complex, benzothiazole metal complex, trisbenzimidazolylbenzene (US Pat. No. 5,645,948) ), Quinoxaline compounds (JP-A-6-207169), phenanthroline derivatives (JP-A-5-331459), 2-t-butyl-9,10-N, N'-dicyanoanthraquinonediimine, n-type hydrogen Amorphous carbonized silicon Down, n-type zinc sulfide, etc. n-type zinc selenide.

In addition, the material of the electron carrying layer 7 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
There is no restriction | limiting in the formation method of the electron carrying layer 7. FIG. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.
The film thickness of the electron transport layer 7 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less.

[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 perform electron injection efficiently, the material for forming the electron injection layer 8 is preferably a metal having a low work function. Examples include alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium. Examples include lithium fluoride (LiF), magnesium fluoride (MgF ₂ ), lithium oxide (Li ₂ O), cesium carbonate (II) (CsCO ₃ ), and the like (Applied Physics Letters, 1997, 70, 152). JP-A-10-74586; see IEEE Transactions on Electron Devices, 1997, 44, 1245; SID 04 Digest, page 154, etc.).

The film thickness is usually preferably from 0.1 nm to 5 nm.
Furthermore, an organic electron transport compound represented by a metal complex such as a nitrogen-containing heterocyclic compound such as bathophenanthroline or an aluminum complex of 8-hydroxyquinoline is doped with an alkali metal such as sodium, potassium, cesium, lithium, or rubidium ( JP-A-10-270171, JP-A-2002-1000047, JP-A-2002-1000048, etc.) are preferable because it is possible to improve electron injection / transport properties and achieve excellent film quality. . The film thickness in this case is usually 5 nm or more, preferably 10 nm or more, and is usually 200 nm or less, preferably 100 nm or less.

In addition, the material of the electron injection layer 8 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
There is no restriction | limiting in the formation method of the electron injection layer 8. FIG. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.
[9] Cathode The cathode 9 plays a role of injecting electrons into a layer (such as the electron injection layer 8 or the light emitting layer 5) on the light emitting layer 5 side.

  As the material of the cathode 9, the material used for the anode 2 can be used. However, in order to perform electron injection efficiently, a metal having a low work function is preferable. For example, tin, magnesium, indium, A suitable metal such as calcium, aluminum, silver, or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.

In addition, the material of the cathode 9 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The film thickness of the cathode 9 is usually the same as that of the anode 2.
Further, for the purpose of protecting the cathode 9 made of a low work function metal, it is preferable to further stack a metal layer having a high work function and stable to the atmosphere because the stability of the device is increased. For this purpose, for example, metals such as aluminum, silver, copper, nickel, chromium, gold and platinum are used. In addition, these materials may be used only by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

[10] Other Layers The organic electroluminescent element according to the present invention may have another configuration without departing from the spirit thereof. For example, as long as the performance is not impaired, an arbitrary layer may be provided between the anode 2 and the cathode 9 in addition to the layers described above, and an arbitrary layer may be omitted. .

[11] Electron blocking layer Examples of the optional layer include an electron blocking layer. The electron blocking layer is provided between the hole injection layer 3 or the hole transport layer 4 and the light emitting layer 5 and prevents electrons moving from the light emitting layer 5 from reaching the hole injection layer 3. Thus, the probability of recombination of holes and electrons in the light emitting layer 5 is increased, the excitons generated are confined in the light emitting layer 5, and the holes injected from the hole injection layer 3 are efficiently collected. There is a role to transport in the direction of. In particular, when a phosphorescent material or a blue light emitting material is used as the light emitting material, it is effective to provide an electron blocking layer.

  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). Furthermore, when the light emitting layer 5 is produced by a wet film formation method, the electron blocking layer is also required to be compatible with the wet film formation. Examples of the material used for such an electron blocking layer include a copolymer of dioctylfluorene and triphenylamine typified by F8-TFB (International Publication No. 2004/084260).

In addition, the material of an electron blocking layer may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
There is no restriction | limiting in the formation method of an electron blocking layer. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.
Moreover, in the layer structure demonstrated above, it is also possible to laminate | stack components other than a board | substrate in reverse order. For example, in the case of the layer configuration in FIG. The hole injection layer 3 and the anode 2 may be provided in this order.

Furthermore, it is also possible to constitute the organic electroluminescent element according to the present invention by laminating components other than the substrate between two substrates, at least one of which is transparent.
In addition, a structure in which a plurality of components (light emitting units) other than the substrate are stacked in a plurality of layers (a structure in which a plurality of light emitting units are stacked) may be employed. In that case, instead of the interface layer between the steps (between the light emitting units) (when the anode is ITO and the cathode is Al, these two layers), for example, a charge made of vanadium pentoxide (V ₂ O ₅ ) or the like. When a generation layer (Carrier Generation Layer: CGL) is provided, a barrier between steps is reduced, which is more preferable from the viewpoint of light emission efficiency and driving voltage.

Furthermore, the organic electroluminescent device according to the present invention may be configured as a single organic electroluminescent device, or may be applied to a configuration in which a plurality of organic electroluminescent devices are arranged in an array. You may apply to the structure by which the cathode is arrange | positioned at XY matrix form.
In addition, each layer described above may contain components other than those described as materials as long as the effects of the present invention are not significantly impaired.

  The organic electroluminescent element of the present invention is used for organic EL displays and organic EL lighting. The organic electroluminescent device obtained by the present invention is described in, for example, “Organic EL Display” (Ohm, August 20, 2004, written by Shizushi Tokito, Chiba Adachi, and Hideyuki Murata). An organic EL display and organic EL illumination can be formed by the method.

EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to description of a following example, unless the summary is exceeded.
<Synthesis Example 1>
(Synthesis of Intermediate 1)

3-Bromobenzonitrile (7.57 g, 41.63 mmol) was placed in a four-necked eggplant flask, and 15 mL of methylene chloride was added to the place purged with nitrogen and stirred. The mixture was cooled in a water bath, trifluoromethanesulfonic anhydride (6.43 g, 22.79 mmol) and 4-acetylbiphenyl (3.89 g, 19.82 mmol) dissolved in 15 mL of methylene chloride were added, and the mixture was stirred for 3.5 hours. The reaction mixture was neutralized with aqueous sodium hydrogen carbonate solution, extracted with methylene chloride, the organic layer was washed with water, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane / methylene chloride = 3/1) and suspended and washed with ethanol to obtain intermediate 1 (3.3 g).
Yield 31%).
(Synthesis of Compound 203)

Under a nitrogen atmosphere, tetrakis (trimethyl chloride) was added to a suspension of Intermediate 1 (3.8 g, 7.01 mmol), 4-dibenzofuranboronic acid (3.41 g, 16.12 mmol), toluene (70 ml), ethanol (35 ml) at room temperature. Phenylphosphine) palladium (0) (0.40 g, 0.35 mmol) and 2M aqueous sodium carbonate solution (17.5 ml) were added, and the mixture was refluxed for 8 hours. After allowing to cool to room temperature, the reaction mixture was filtered, and the filtered product was dissolved in methylene chloride, dried over magnesium sulfate, treated with clay, and filtered. The filtrate was concentrated and suspended and washed with methylene chloride to obtain Compound 203 (3.2 g, yield 65%).
<Synthesis Example 2>
(Synthesis of Compound 202)

Under nitrogen atmosphere, a suspension of intermediate 1 (3.3 g, 6.24 mmol), 9-phenanthreneboronic acid (3.18 g, 14.35 mmol), toluene (62.4 ml), ethanol (31.2 ml) at room temperature with tetrakis (tri Phenylphosphine) palladium (0) (0.35 g, 0.31 mmol) and 2M aqueous sodium carbonate solution (15.6 ml) were added, and the mixture was refluxed for 6 hours. After allowing to cool to room temperature, the reaction mixture was filtered, and the filtered product was dissolved in methylene chloride, dried over magnesium sulfate, treated with clay, and filtered. The filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane / methylene chloride = 1/1) and suspended and washed with methanol to obtain Compound 202 (3.41 g, yield 81%).
<Synthesis Example 3>
(Synthesis of Compound 201)

Under a nitrogen atmosphere, tetrakis (trimethyl chloride) was added to a suspension of Intermediate 1 (2.8 g, 5.16 mmol), 1-naphthaleneboronic acid (2.04 g, 11.87 mmol), toluene (52 ml), and ethanol (26 ml) at room temperature. Phenylphosphine) palladium (0) (0.30 g, 0.26 mmol) and 2M aqueous sodium carbonate solution (13 ml) were added, and the mixture was refluxed for 7 hours. After allowing to cool to room temperature, the reaction mixture was extracted with methylene chloride, the organic layer was washed with water, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane / methylene chloride = 2/1, hexane / ethyl acetate = 10/1) and recrystallized from ethyl acetate / hexane to give compound 201 (1.13 g,
Yield 35%).

1. Substrate 2. Anode 3. Hole injection layer 4. 4. hole transport layer Light emitting layer 6. 6. Hole blocking layer Electron transport layer8. Electron injection layer 9. cathode

Claims (8)

A pyrimidine compound represented by the following general formula ( 3 ).

(In the general formula ( 3 ), X and Z are each independently 1-naphthyl group, 2-naphthyl group and 9
-Any of the phenanthryl groups.
L ¹ and L ² are single bonds . ) The composition for organic electroluminescent elements containing the pyrimidine compound of Claim 1 , and a solvent. An organic electroluminescent device having an anode, a cathode, and an organic layer between the anode and the cathode on a substrate, wherein the organic layer comprises a layer containing the compound according to claim 1 as a material for an organic electroluminescent device. An organic electroluminescent device comprising: The composition for organic electroluminescent elements according to claim 2 , wherein the organic layer comprises an anode, a cathode, and an organic layer between the anode and the cathode on a substrate. An organic electroluminescent element comprising a layer formed using a material. The organic electroluminescent element according to claim 3 , wherein the layer containing the material for an organic electroluminescent element is a light emitting layer. The organic electroluminescent element according to claim 4 , wherein the layer formed using the composition for organic electroluminescent element is a light emitting layer. A display device comprising the organic electroluminescent element according to claim 3 . An illuminating device comprising the organic electroluminescent element according to claim 3 .

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