JP2013159561A - Charge transport material, composition for charge transport film, organic electroluminescent element, organic el display and organic el illumination - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charge transport material which is thermally and electrochemically stable and soluble into a solvent, a composition for a charge transport film containing the same, an organic electroluminescent element having high luminous efficiency and high driving stability, an organic EL display including the same, and an organic EL illumination.SOLUTION: A monoamine compound represented by general formula (1) is provided. (In the general formula (1), ArG-ArGeach represent a 3-30C aromatic ring group or the like which may have a substituent, and Z represents a divalent substituent comprising two or more 3-60C aromatic ring assembly atomic groups which may have a substituent).

Description

  The present invention relates to a monoamine compound that is thermally and electrochemically stable and soluble in various solvents, a charge transport material comprising the monoamine compound, a composition for a charge transport film comprising the charge transport material, and the charge transport material. The present invention relates to an organic electroluminescent element having a layer to be contained and having high luminous efficiency and high driving stability, and an organic EL display and organic EL illumination including the element.

In recent years, an electroluminescent element (organic electroluminescent element) using an organic thin film has been developed. Examples of the method for forming the organic thin film include a vacuum deposition method and a wet film forming method. Among these, the wet film-forming method does not require a vacuum process, is easy to increase in area, and can easily mix a plurality of materials having various functions into one layer (coating liquid). There are advantages.
Polymer materials such as poly (p-phenylene vinylene) derivatives and polyfluorene derivatives are mainly used as the material of the light emitting layer formed by the wet film forming 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 problems, the organic electroluminescence device by the wet film forming method is inferior in driving stability to the organic electroluminescence device by the 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 transport materials, light-emitting materials) instead of a polymer compound. The organic electroluminescent elements described above are described, and the following compounds H-1 and H-2 are used as the hole transporting charge transporting material.

  Moreover, in the organic electroluminescent element using the organic thin film which consists of the several low molecular material formed by the wet film forming method, non-patent literature 1 and patent documents 2-4 raise the luminous efficiency of the organic electroluminescent element. Therefore, a device utilizing phosphorescence is described, and the following compounds H-3, H-4, H-5, H-6, and H-7 are used as charge transport materials.

Japanese Patent Laid-Open No. 11-238359 JP 2007-110093 A WO2011 / 055933 WO2007 / 063754

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

  However, the above compounds H-1, H-2, H-3, H-4 and H-5 do not necessarily have sufficient solubility in solvents, and H-6 is based on the rigidity of the spiro ring. It is considered that the solubility is low due to the high symmetry. For this reason, it is necessary to use a halogen-based solvent such as chloroform as a coating solvent, but the halogen-based solvent has a large environmental load. Furthermore, there is a possibility that the material is deteriorated by impurities contained in the halogen-based solvent, and it is considered that the driving stability of the organic electroluminescence device by the wet film forming method using the halogen-based solvent is not sufficient.

In addition, since the compounds H-1, H-2, H-3 and H-4 have low glass transition temperatures, the organic electroluminescent devices disclosed in Patent Document 1 and Non-Patent Document 1 have improved heat resistance. There seems to be room. Furthermore, the compounds H-1, H-2, H-3, H-4 and H-5 are very easy to crystallize, and it is not easy to obtain a uniform amorphous film by a wet film forming method.
In addition, since the compound H-7 has only one benzene ring each substituted with a positively charged amine nitrogen atom, the contribution of stabilization to the positive charge is small, and the compound exemplified in Patent Document 4 Is considered to have low electrical stability.

  Accordingly, the present invention has been made in view of the above-described conventional situation, and the problem is that it is thermally and electrochemically stable, a solvent-soluble charge transport material, and a composition for a charge transport film containing the same. To provide things. Another object of the present invention is to provide an organic electroluminescent device having high luminous efficiency and high driving stability, and an organic EL display and organic EL illumination having the organic electroluminescent device.

  As a result of intensive studies, the present inventors have found that the monoamine compound represented by the following general formula (1) is excellent in solubility in a solvent and has a high amorphous property, so that a thin film can be formed by a wet film formation method. In addition, since it has excellent charge transportability and electrical redox durability, it has been found that when it is used in an organic electroluminescent device, it can exhibit high luminous efficiency and high driving stability, and the present invention has been completed.

That is, the gist of the present invention resides in the monoamine compound shown below.
A monoamine compound represented by the following general formula (1).

(In General Formula (1), ArG ^{1 to} ArG ³ each have an aromatic ring group having 3 to 30 carbon atoms which may have a substituent, or 3 to 60 carbon atoms which may have a substituent. Represents two or more aromatic ring assembly group groups, and Z represents a divalent substitution consisting of two or more aromatic ring assembly groups having 3 to 60 carbon atoms which may have a substituent. Represents a group)

  According to the monoamine compound of the present invention, the charge transport material comprising the monoamine compound, and the charge transport film composition comprising the charge transport material, an organic thin film comprising a thermally and electrochemically stable material is prepared by a wet process. It can be easily formed by a film method, and the area of the organic electroluminescent element can be easily increased. In addition, according to the organic electroluminescence device using the charge transport material of the present invention and the charge transport film composition containing the charge transport material, it is possible to emit light with high luminance and high efficiency, and stability of the device. In particular, driving stability is improved.

The charge transport material of the present invention can be applied to film formation by a wet film formation method because of excellent film formability, charge transportability, light emission characteristics, and heat resistance.
In addition, the charge transport material of the present invention and the charge transport film composition containing the charge transport material have excellent film-forming properties, charge transport properties, light emitting properties, and heat resistance, so that holes are formed according to the layer structure of the device. The present invention can also be applied to formation of organic layers such as an injection layer, a hole transport layer, a light emitting layer, an electron injection layer, and an electron transport layer.

Therefore, the organic electroluminescent device using the charge transport material of the present invention and the charge transport film composition containing the charge transport material is a flat panel display (for example, for OA computers or wall-mounted televisions), an in-vehicle display device, a mobile phone. It can be applied to light sources (for example, light sources for copiers, backlights for liquid crystal displays and instruments), display panels, and beacon lamps that take advantage of the characteristics of telephone displays and surface light emitters, and their technical value is great. Is.

  In addition, the charge transport material of the present invention and the charge transport film composition containing the charge transport material have essentially excellent redox stability, and thus are not limited to organic electroluminescent devices, but also electrophotographic photosensitive materials. It can also be used effectively for the body.

It is sectional drawing which shows typically an example of the structure of the organic electroluminescent element of this invention.

Embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention does not exceed the gist thereof. It is not limited to the contents.
[Explanation of words]
The hydrocarbon aromatic ring represents an aromatic ring composed of only carbon and hydrogen atoms such as benzene, naphthalene, anthracene, phenanthrene and fluorene.

A heteroaromatic ring represents an aromatic ring containing an oxygen atom, a sulfur atom, a nitrogen atom, a silicon atom, etc. in addition to carbon and hydrogen atoms, such as a pyridine ring, a carbazole ring, a dibenzofuran ring and the like. The aromatic ring represents all hydrocarbon aromatic rings and heteroaromatic rings.
The aromatic ring assembly atomic group is an atomic group formed by linking aromatic rings such as biphenyl and terphenyl.

[Monoamine compound]
The monoamine compound of the present invention (hereinafter also referred to as “compound (1)”) is represented by the following general formula (1).

(In General Formula (1), ArG ^{1 to} ArG ³ each have an aromatic ring group having 3 to 30 carbon atoms which may have a substituent, or 3 to 60 carbon atoms which may have a substituent. Represents two or more aromatic ring assembly group groups, and Z represents a divalent substitution consisting of two or more aromatic ring assembly groups having 3 to 60 carbon atoms which may have a substituent. Represents a group)

[1. Structural features]
Compound (1) has both an indolocarbazole and an amine moiety having two or more aromatic rings around the nitrogen atom, and the positive charge is stabilized by conjugation with the amine moiety and the negative charge is stabilized by conjugation with the indolocarbazole ring. And has an excellent charge (hole) transporting ability and a long lifetime.
Compound (1) has an indolocarbazole structure portion twisted with the conjugate plane of the amine, so that it has extremely high amorphousness, excellent solubility in various organic solvents, and is easily crystallized. It is possible to form an amorphous organic thin film that does not.
Incidentally, ArG ³ is preferably from the viewpoint of further improvement of the solubility be two or more aromatic ring assembly atomic group, any one of ArG ¹ ～ArG ³ represented by the following general formula 3 It is preferable to have a partial structure in order to further improve the amorphous property.

[2. Molecular weight range]
The molecular weight of the compound (1) is usually 5000 or less, preferably 4000 or less, more preferably 3000 or less, and usually 700 or more, preferably 800 or more.
Within the above range, purification is easy and the glass transition temperature, melting point, vaporization temperature and the like are high, and thus heat resistance is good.

[3. Physical properties]
(1) Glass transition temperature Although compound (1) has a glass transition temperature of 80 degreeC or more normally, it is preferable that a glass transition temperature is 90 degreeC or more from a heat resistant viewpoint, and it is 100 degreeC or more. Further preferred.

(2) Vaporization temperature Compound (1) usually has a vaporization temperature of 300 ° C or higher and 800 ° C or lower. The charge transport material of the present invention preferably has no crystallization temperature between the glass transition temperature and the vaporization temperature.
(3) Solubility The compound (1) has a solvent solubility of 1% by mass or more in a hydrocarbon solvent having a high boiling point of 100 ° C. or higher at 25 ° C. and atmospheric pressure. It is preferable for securing and obtaining film formability by a wet film forming method. This solubility is preferably 3% by mass or more, more preferably 5% by mass or more. The upper limit of the solubility is not particularly defined but is usually 50% by mass or less.

(4) IP, EA
The compound of the present invention is characterized by having an excellent charge (hole) injecting and transporting ability. The indicators include IP (ionization potential) and EA (electron affinity).
There are various measurement methods and estimation methods, and it is also possible to calculate them by, for example, the Stochastic Monte Carlo method.

The range of IP and EA is, in the Stochastic Monte Carlo method, IP is usually 6.5 or less, preferably 6.0 or less, more preferably 5.7 or less, and EA is usually 1.0 or more, preferably 1. It is 5 or more, more preferably 1.8 or more.
[5. ArG ^{1 to} ArG ³ ]
In (1), ArG ^{1 to} ArG ³ are each independently an aromatic ring group having 3 to 30 carbon atoms which may have a substituent, or 3 carbon atoms which may have a substituent. 2 to 60 aromatic ring assembly group groups.

  Examples of aromatic ring groups having 3 to 30 carbon atoms include a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring having one free valence , Triphenylene ring, fluoranthene ring, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole 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, quinoxaline ring, benzimidazole ring, quinazoline ring, etc. Ring or 2-5 contraction It includes groups of rings.

Here, in the present invention, the free valence can form a bond with another free valence as described in Organic Chemistry / Biochemical Nomenclature (above) (Revised 2nd edition, Nankodo, 1992). Say things. That is, for example, “a benzene ring having one free valence” refers to a phenyl group, and “a benzene ring having two free valences” refers to a phenylene group.
Examples of two or more aromatic ring assembly group having 3 to 60 carbon atoms are as follows.

[5.2 Divalent Substituent Z]
Z represents a divalent substituent composed of two or more aromatic ring assembly groups having 3 to 60 carbon atoms which may have a substituent, and examples thereof include the above-mentioned aromatic groups ArG1 to ArG3. It is a group having two free valences composed of an atomic group equivalent to the ring assembly atomic group. From the viewpoint of chemical stability, an aromatic ring assembly atomic group that is a benzene ring having two free valences and a dibenzofuran ring is preferred, and an aromatic ring assembly atomic group that is a benzene ring having two free valences Is particularly preferred.

Examples of the substituent that the ArG ^{1 to} ArG ³ and the divalent substituent Z may have are as follows:
-8 linear or branched alkyl group (for example, methyl group, ethyl group, n-propyl group, 2-propyl group, n-butyl group, isobutyl group, tert-butyl group, etc.), alkenyl having 2 to 9 carbon atoms Group (for example, vinyl group, allyl group, 1-butenyl group, etc.), alkynyl group having 2-9 carbon atoms (for example, ethynyl group, propargyl group, etc.), aralkyl group having 7-17 carbon atoms (for example, benzyl group, etc.) 1-20 alkoxy groups (for example, methoxy group, ethoxy group, butoxy group), C6-C12 aryloxy groups (for example, phenyloxy group, 1-naphthyloxy group, 2-naphthyloxy group, etc.), carbon number A heteroaryloxy group having 3 to 20 5- or 6-membered aromatic heterocyclic group (for example, pyridyloxy group, thienyloxy group, etc.), having 1 to 10 carbon atoms Sil group (for example, formyl group, acetyl group, benzoyl group, etc.), C2-C10 alkoxycarbonyl group (for example, methoxycarbonyl group, ethoxycarbonyl group, etc.), C7-C13 aryloxycarbonyl group (for example, phenoxycarbonyl) Group), an alkylcarbonyloxy group having 2 to 10 carbon atoms (such as an acetoxy group), an alkylthio group having 1 to 8 carbon atoms (such as a methylthio group and an ethylthio group), and an arylthio group having 6 to 12 carbon atoms (for example, Phenylthio group, 1-naphthylthio group, etc.), C3-C30 silyl group (eg trimethylsilyl group, triphenylsilyl group etc.), aromatic hydrocarbon having one free valence (eg benzene ring, naphthalene ring, anthracene) Ring, phenanthrene ring, perylene ring, tetracene , A pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, a fluoranthene ring, etc., a 5- or 6-membered monocyclic ring or a 2-5 condensed ring.) Aromatic heterocyclic ring having one free valence (For example, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, 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, quinoline ring Quinoxaline ring , A benzimidazole ring, a perimidine ring, a quinazoline ring, and the like, a 5- or 6-membered monocyclic ring or a 2-4 condensed ring).

From the viewpoint of improving electrochemical durability and improving heat resistance, the substituent of ArG1 to ArG3 is preferably an aromatic hydrocarbon group or an aromatic heterocyclic group, more preferably an aromatic carbonization. A hydrogen group or an aromatic heterocyclic group, more preferably a phenyl group, a naphthyl group, or a carbazole ring or benzofuran ring having one free valence, etc., particularly preferably a phenyl group or a naphthyl group.
From the viewpoint of further improving the solubility and amorphousness, the substituent of ArG1 to ArG3 is preferably an alkyl group, more preferably a methyl group, an ethyl group, an n-propyl group, a 2-propyl group, n -Butyl group, isobutyl group, tert-butyl group and the like, more preferably methyl group, ethyl group and the like.

[6] Particularly preferred partial structure When the monoamine compound of the present invention is used as a charge transport material to be described later, any one of ArG ^{1 to} ArG ³ is represented by the following general formula 3 from the viewpoint of further improving the solubility in a solvent. It is preferable to have a partial structure represented by
[8. Example]
Although the preferable specific example as a monoamine compound of this invention is shown below, this invention is not limited to these.

[9. Synthesis method]
The amine compound of the present invention can be synthesized, for example, by sequentially introducing a ring using an arylamine compound as a starting material.

(CN coupling reaction)
An amino group is introduced into an aromatic hydrocarbon group by reacting a reaction substrate with a halide having an aromatic hydrocarbon group or a trifluoromethanesulfonate ester reagent in the presence of a base using a transition metal element catalyst. be able to. Isolation and purification can be performed, for example, by combining distillation, filtration, extraction, recrystallization, reprecipitation, suspension washing, and chromatography operations.

Examples of the transition metal element catalyst include a palladium catalyst and a copper catalyst, and a palladium catalyst is desirable from the viewpoint of simplicity of reaction and high reaction yield.
The base is not particularly limited, and for example, potassium carbonate, cesium carbonate, tert-butoxy sodium, triethylamine and the like can be used.
As the solvent, when a palladium catalyst is used, toluene is preferable, and when a copper catalyst is used, pyridine, N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and the like are preferable.

  In addition, in the compound (1) according to the present invention, when Z = -Ph-Ar- (Ar is an aromatic ring), the coupling reaction is sequentially carried out using a triarylamine trihalide as a starting material. Can also be synthesized.

(C—C coupling reaction)
An aromatic hydrocarbon group is introduced into a substrate by reacting a reaction substrate with an organometallic reagent having an aromatic hydrocarbon group in a nonpolar or polar solvent in the presence of a base using a transition metal element catalyst. be able to. Isolation and purification can be performed, for example, by combining distillation, filtration, extraction, recrystallization, reprecipitation, suspension washing, and chromatography operations.

Examples of organometallic reagents include organoboron reagents, organomagnesium reagents, organozinc reagents and the like. Of these, organoboron reagents are desirable because of their ease of handling.
Examples of transition metal element catalysts include organic palladium catalysts, organic nickel catalysts, organic copper catalysts, organic platinum catalysts, organic rhodium catalysts, organic ruthenium catalysts, and organic iridium catalysts. Among these, an organopalladium catalyst is desirable because of the simplicity of the reaction and the high reaction yield.

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 aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; dimethoxyethane , Tetrahydrofuran, dioxane and other ethers; ethanol, propanol and other alcohols; water and the like alone or in admixture.

Moreover, 1-100 mol% of surfactant can also be added if necessary.
[Charge transport material]
The charge transport material of the present invention comprises a monoamine compound represented by the general formula (1). Since the monoamine compound is excellent in solubility in a solvent and has a high amorphous property, a thin film can be formed by a wet film formation method.

In addition, the monoamine compound used as the charge transport material of the present invention is excellent in charge transportability and electrical redox resistance, and has a high triplet excitation level. High luminous efficiency and high driving stability can be realized.
[Composition for charge transport film]
The composition for a charge transport film of the present invention contains the above-described charge transport material of the present invention, and is preferably used for an organic electroluminescence device.

[1] Solvent The charge transport film composition of the present invention, particularly the charge transport film composition used as the composition for an organic electroluminescence device, preferably contains a solvent.
The solvent contained in the composition for a charge transport film of the present invention is not particularly limited as long as it is a solvent that can satisfactorily dissolve the charge transport material of the present invention as a solute.

  Since the charge transport material of the present invention has very high solubility in a solvent, 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; cycloaliphatic ketones such as cyclohexanone and cyclooctanone; aliphatic ketones such as methyl ethyl ketone and dibutyl ketone; cyclohexanol, cyclooctanol and the like Aliphatic alcohols; aliphatic alcohols such as butanol and hexanol; aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA); ethyl acetate, n-butyl acetate, lactic acid Aliphatic esters such as ethyl 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. There is a possibility. Therefore, it is preferable to reduce the amount of water in the composition.

  Examples of the method for reducing the amount of water in the composition include a nitrogen gas seal, use of a desiccant, a method of dehydrating a solvent in advance, a method of using a solvent having low water solubility, and the like. Among these, the use of a solvent having low solubility in water is preferable because the solution film can prevent whitening by absorbing moisture in the atmosphere during the wet film-forming process. From such a viewpoint, as the composition for a charge transport film of the present invention, for example, a solvent having a water solubility at 25 ° C. of 1% by mass or less, preferably 0.1% by mass or less is contained in the composition. It is preferable to contain 10 mass% or more.

Further, in order to reduce the decrease in film formation stability due to solvent evaporation from the composition during wet film formation, the solvent has a boiling point of 100 ° C. or higher, preferably 150 ° C. or higher, as the solvent for the charge transport film composition. More preferably, it is effective to use a solvent of 200 ° C. or higher. Further, in order to obtain a more uniform film, it is necessary for the solvent to evaporate from the liquid film immediately after film formation at an appropriate rate. For this purpose, the lower limit of the boiling point is usually 80 ° C., preferably 100 ° C. It is effective to use a solvent having a temperature of preferably 120 ° C. and usually an upper limit of less than 270 ° C., preferably less than 250 ° C., more preferably less than 230 ° C.
A solvent that satisfies the above-mentioned conditions, ie, solute solubility, evaporation rate, and water solubility conditions, may be used alone. However, if a solvent that satisfies all the conditions cannot be selected, two or more solvents may be mixed. It can also be used.

[2] Luminescent Material The charge transport film composition of the present invention, particularly the charge transport film composition used as the composition for an organic electroluminescence device, preferably contains a luminescent material.
The light emitting material refers to a component that mainly emits light in the composition for a charge transport film of the present invention, and corresponds to a dopant component in an organic electroluminescent device. That is, the amount of light (unit: cd / m ² ) emitted from the charge transport film composition is usually 10 to 100%, preferably 20 to 10%.
If 0%, more preferably 50-100%, most preferably 80-100% is identified as luminescence from a component material, it is defined as a luminescent material.

Any known material can be used as the light-emitting material. For example, a fluorescent light-emitting material and a phosphorescent light-emitting material can be used singly or as a mixture of a plurality of materials. From the viewpoint of internal quantum efficiency, phosphorescent light emission is preferable. Material.
The maximum emission peak wavelength of this luminescent material is preferably in the range of 390 to 700 nm, more preferably 500 to 700 nm.
For the purpose of improving the solubility in a solvent, it is possible to reduce the symmetry and rigidity of the light emitting material molecule, or to 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.
Preferable 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).

ML _(qj) L ' _j (V)
(In the general formula (V), M represents a metal, q represents a valence of the metal, and L and L ′.
Represents a bidentate ligand. j represents an integer of 0-2. )

(In the general formula (VI), M ^d represents a metal, T represents a carbon atom or a nitrogen atom. R ^{92 to} R ⁹⁵ each independently represents a substituent. However, when T is nitrogen, R ⁹⁴ and R ⁹⁵ is not.
)
Hereinafter, the compound represented by the general formula (V) will be described first.
In the general formula (V), M represents an arbitrary metal. 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 L and L ′ in the general formula (V) each represent a ligand having the following partial structure.

  As L ′, the followings are particularly preferable from the viewpoint of the stability of the complex.

In the partial structures of L and L ′, ring A1 represents an aromatic hydrocarbon group or aromatic heterocyclic group, ring A2 represents a nitrogen-containing aromatic heterocyclic group, and these may have a substituent. Good.
When the rings A1 and A2 have a substituent, preferred substituents include a halogen atom such as a fluorine atom; an alkyl group such as a methyl group and an ethyl group; an alkenyl group such as a vinyl group; a methoxycarbonyl group and an ethoxycarbonyl group 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 formulas (Va), (Vb), and (Vc).

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

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

(In the general formula (Vc), M ^c represents a metal, w represents a valence of the metal, and j represents 0-2.
Indicates an integer. Furthermore, each of ring A1 and ring A1 ′ independently represents an aromatic hydrocarbon group that may have a substituent or an aromatic heterocyclic group that may have a substituent. Ring A2 and ring A2 ′ each independently represent a nitrogen-containing aromatic heterocyclic group which may have a substituent. )
In the general formulas (Va), (Vb), and (Vc), the group constituting the ring A1 and the ring A1 ′ is preferably, for example, a phenyl group, a biphenyl group, a naphthyl group, an anthryl group, a thienyl group, or a furyl group. Benzothienyl group, benzofuryl group, pyridyl group, quinolyl group, isoquinolyl group, carbazolyl group and the like.

Further, the group constituting the 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, for example. Group, phenanthridyl group and the like.
Furthermore, examples of the substituent that the ring A1, ring A1 ′ ring A2 and ring A2 ′ may have include a halogen atom such as a fluorine atom; an alkyl group such as a methyl group and an ethyl group; an alkenyl group such as a vinyl group; Alkoxycarbonyl groups such as methoxycarbonyl group and ethoxycarbonyl group; alkoxy groups such as methoxy group and ethoxy group; aryloxy groups such as phenoxy group and benzyloxy group; dialkylamino groups such as dimethylamino group and diethylamino group; diphenylamino group A diarylamino group such as carbazolyl group; an acyl group such as acetyl group; a haloalkyl group such as trifluoromethyl group; a cyano group and the like.

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

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

Further, examples of M ^a , M ^b , and M ^c include the same metals as M described above, and among these, ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, or gold is preferable.
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 Represents a phenyl group).

Among the organometallic complexes represented by the general formulas (V), (Va), (Vb), and (Vc), in particular, as the ligand L and / or L ′, a 2-arylpyridine-based ligand, , A complex having 2-arylpyridine, a complex in which a substituent is bonded to the complex, and a complex in which a substituent is bonded to each other to form a condensed ring.
Moreover, the compound as described in an international publication 2005/019373 pamphlet can also be used.

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 can be mentioned, and divalent metals such as platinum and palladium are particularly preferable.

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

Further, when T is a carbon atom, R ⁹⁴ and R ⁹⁵ each independently represent a substituent represented by the same examples as R ⁹² and R ⁹³ . Further, as described above, when T is a nitrogen atom, R ⁹⁴ and R ⁹⁵ are absent.
R ^{92 to} R ⁹⁵ may further have a substituent. There is no restriction | limiting in particular as a substituent in this case, Arbitrary groups can be made into a substituent.
Further, 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 a charge transport film of the present invention, in particular, the composition for a charge transport film used as a composition for an organic electroluminescence device, in addition to the solvent and the light emitting material described above, In addition, various other solvents may be included. Examples of such other solvents include amide solvents 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.
In addition, 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 Compounding Ratio in Charge Transport Film Composition Charge transport film composition, in particular, charge transport material, light emitting material, and components that can be added as required in leveling composition for organic electroluminescence device (leveling) The lower limit of the solid content concentration such as an agent is usually 0.01% by mass, preferably 0.05% by mass, more preferably 0.1% by mass, still more preferably 0.5% by mass, and most preferably 1% by mass. The upper limit is usually 80% by mass, preferably 50% by mass, more preferably 40% by mass, still more preferably 30% by mass, and most preferably 20% by mass. When this concentration is below the lower limit, it is difficult to form a thick film when forming a thin film, and when it exceeds the upper limit, it is difficult to form a thin film.

  In the composition for a charge transport film of the present invention, particularly the composition for an organic electroluminescence device, the lower limit of the mass ratio of the light emitting material / charge transport material is usually 0.1 / 99.9, more preferably 0.8. 5 / 99.5, more preferably 1/99, most preferably 2/98 or more, while the upper limit is usually 50/50, more preferably 40/60, still more preferably 30/70, most preferably 20 / 80. If this mass ratio falls below the lower limit or exceeds the upper limit, the luminous efficiency may be significantly reduced.

[5] Method for Preparing Charge Transport Film Composition The charge transport film composition of the present invention, particularly the organic electroluminescent device composition, comprises a charge transport material, a light emitting material, and a leveling agent that can be added as necessary. It is prepared by dissolving a solute composed of various additives such as an antifoaming agent 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 solution. The dissolution step may be performed at room temperature, but when the dissolution rate is slow, it can be heated and dissolved. After the dissolution step, a filtration step such as filtering may be applied as necessary.

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

Specifically, the amount of water contained in the composition for a charge transport film of the present invention, particularly the composition for an organic electroluminescence device, is usually 1% by mass or less, preferably 0.1% by mass or less, more preferably 0. 0.01% by mass or less.
As a method for measuring the moisture concentration in the composition for a charge transport film, a method described in Japanese Industrial Standard “Method for Measuring Moisture of Chemical Products” (JIS K0068: 2001) is preferable. For example, Karl Fischer reagent method (JIS K0211- 1348) and the like.

(Uniformity)
The composition for a charge transport film of the present invention, particularly the composition for an organic electroluminescence device, is used at room temperature in order to improve stability in a wet film forming process, for example, ejection stability from a nozzle in an ink jet film forming method. It is preferably a uniform liquid. 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 charge transport film of the present invention, particularly the composition for organic electroluminescence device, in the case of extremely low viscosity, for example, coating surface nonuniformity due to excessive liquid film flow in the film forming process, inkjet film formation In the case of extremely high viscosity, nozzle clogging or the like in ink jet film formation tends to occur. For this reason, the lower limit of the viscosity of the composition of the present invention at 25 ° C. is usually 2 mPa · s, preferably 3 mPa · s, more preferably 5 mPa · s, and the upper limit is usually 1000 mPa · s, preferably 100 mPa · s. More preferably, it is 50 mPa · s.

In addition, when the surface tension of the composition for charge transport film of the present invention, particularly the composition for organic electroluminescence device is high, the wettability of the film-forming liquid to the substrate is lowered, that is, the leveling property of the liquid film is deteriorated, Since problems such as disturbance of the film-forming surface during drying are likely to occur, the surface tension at 20 ° C. of the composition of the present invention is usually less than 50 mN / m, preferably less than 40 mN / m.
Furthermore, when the vapor pressure of the composition for a charge transport film of the present invention, particularly the composition for an organic electroluminescence device, is high, problems such as a change in solute concentration due to evaporation of the solvent are likely to 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.

<Configuration of organic electroluminescent element>
The organic electroluminescent device of the present invention is particularly suitable if it includes one or more organic layers on a pair of electrodes formed on a substrate, and at least one of the organic layers contains the charge transport material of the present invention. It is not limited. Here, the organic layer is not uniform depending on the layer structure of the organic electroluminescent element, but for example, a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer are included. Can be mentioned.

When the organic electroluminescent element of the present invention has one organic layer, the organic layer means a light emitting layer, the light emitting layer has a charge transporting ability, and contains the charge transport material of the present invention.
On the other hand, in the case of an organic electroluminescent device having a plurality of organic layers, at least one of a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer and an electron injection layer is the charge of the present invention. What is necessary is just to contain a transport material. In addition, as a layer structure of the organic layer of the organic electroluminescent element which has a some organic layer, if it can light-emit, it will not specifically limit, For example, the following are mentioned.
1) at least composed of a light emitting layer and an electron transport layer 2) at least composed of a hole transport layer and a light emitting layer 3) at least composed of a hole transport layer, a light emitting layer and an electron transport layer With reference to FIG. 1, the layer structure of the organic electroluminescent element of the present invention, the general formation method thereof, and the like will be described. For convenience of illustration, the dimensional ratios in the drawings do not necessarily match those described.

FIG. 1 is a schematic cross-sectional view showing an example of an organic electroluminescent element according to the present invention. The organic electroluminescent device shown in FIG. 1 has an anode 2, a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, a hole blocking layer 6, an electron transport layer 7, an electron injection layer 8 and a substrate 1. The cathode 9 has a structure in which the cathodes 9 are sequentially laminated.
In the present invention, the wet film forming method refers to, 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 for the organic electroluminescent element is matched.

(substrate)
The substrate 1 serves as a support for the organic electroluminescent element, and a quartz or glass plate, a metal plate or a metal foil, a plastic film, 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.

(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, or 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.

(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) is prepared. Next, this hole injection layer forming composition is applied onto a layer corresponding to the lower layer of the hole injection layer 3 (usually an anode) by an appropriate technique, formed into a film, and dried to inject holes. Layer 3 is formed.

(Hole transporting compound)
The composition for forming a hole injection layer usually contains a hole transporting compound and a solvent as a constituent material of the hole injection layer.
The hole transporting compound is a 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 weight compound, it is preferably a high molecular weight compound.

As the hole transporting compound, from the viewpoint of a charge injection barrier from the anode 2 to the hole injection layer 3, 4
. Compounds having an ionization potential of 5 eV to 6.0 eV are preferred. 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 body.
The hole transporting compound used for forming the hole injection layer 3 may contain any one of these compounds alone, or may contain two or more. In the case of containing two or more kinds of hole transporting compounds, the combination is arbitrary, but one or more kinds of aromatic tertiary amine polymer compounds and one or two kinds of other hole transporting compounds. 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 (VII).

(In the general formula (VII), Ar ¹ and Ar ² are each independently 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. 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 the above general formulas, Ar ^{6 to} Ar ¹⁶ each independently represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. R ¹⁰¹ and R ¹⁰² each independently represents a hydrogen atom or an arbitrary substituent.
The aromatic hydrocarbon group and aromatic heterocyclic group of Ar ^{1 to} Ar ¹⁶ include a benzene ring, a naphthalene ring, a phenanthrene ring, and a thiophene from the viewpoint of the solubility, heat resistance, hole injection / transport properties 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 ¹⁰¹ and R ¹⁰² 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 (VII) 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 (3,4-ethylenedioxythiophene), a polythiophene derivative, in high molecular weight polystyrene sulfonic acid. The end of this polymer may be capped with methacrylate or the like.

Further, the hole transporting compound may be a crosslinkable polymer described in the following [Hole transporting layer]. The same applies to the film formation method when the crosslinkable polymer is used.
The concentration of the hole transporting compound in the composition for forming a hole injection layer is arbitrary as long as the effects of the present invention are not significantly impaired, but the lower limit is usually 0.01% by mass in terms of film thickness uniformity. The upper limit is usually 70% by mass, preferably 60% by mass, and more preferably 50% by mass. 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.
As the electron-accepting compound, a compound having an oxidizing power and an ability to accept one electron from the above-described hole-transporting compound is preferable. Specifically, a compound having an electron affinity of 4 eV or more is preferable, and a compound having an electron affinity 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, iron (III) chloride (Japanese Patent Application Laid-Open No. 11-251067)
, Inorganic compounds with high valence such as ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene; aromatic boron compounds such as tris (pentafluorophenyl) borane (Japanese Unexamined Patent Publication No. 2003-31365); substitution of organic groups Onium salts (International Publication No. 2005/089024); 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 injection layer or the composition for forming a hole injection layer is usually 0.1 mol% or more, preferably 1 mol% or more with respect to the hole-transporting compound, And it is 100 mol% or less normally, Preferably it is 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 ratios.

(solvent)
It is preferable that at least one of the solvents contained in the composition for forming a hole injection layer used in the wet film forming method can dissolve the constituent material of the hole injection layer described above. The boiling point of this solvent is usually 110 ° C. or higher, preferably 140 ° C. or higher. Among them, a solvent having a boiling point of 200 ° C. or higher and 400 ° C. or lower, particularly 300 ° C. or lower is preferable. If the boiling point of the solvent is too low, the drying speed is too high and the film quality may be deteriorated. On the other hand, if the boiling point of the solvent is too high, it is necessary to increase the temperature of the drying process, and it may adversely affect other layers and the substrate.

Examples of the solvent include ethers, esters, aromatic hydrocarbons, amides, and the like, and dimethyl sulfoxide can also be used. Specific examples of each solvent are as described above.
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 a hole injection layer, the composition is applied onto a layer (usually the anode 2) located on the outer surface of the substrate by wet film formation, and then hole injection is performed by drying. Layer 3 is formed.
The temperature in the coating 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 an application | coating process is not limited unless the effect of this invention is impaired remarkably, it is 0.01 ppm or more normally, and usually 80% or less.
After coating, the film of the composition for forming a hole injection layer is usually dried by heating or the like. If the example of the heating means used in this heating process is given, a clean oven and a hot plate are preferable.
The heating temperature in the heating step is preferably 120 ° C. or higher and 410 ° C. or lower.
In the heating step, the heating time is not limited, but is preferably 10 seconds or more and 180 minutes or less.

<Formation of hole injection layer by vacuum deposition>
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 vessel. Place in the crucibles installed (or put in each crucible when two or more materials are used), evacuate the inside of the vacuum vessel to about 10 ^-4 Pa with an appropriate vacuum pump, and then heat the crucible (2 When using more than one kind of material, heat each crucible) and evaporate by controlling the amount of evaporation (when using more than two kinds of materials, evaporate by controlling the amount of evaporation independently) A hole injection layer 3 is formed on the anode 2 of the substrate placed face to face. 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.

[Hole transport layer]
The method for forming the hole transport layer 4 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 transport layer 4 is formed by a wet film formation method from the viewpoint of reducing dark spots. It is preferable.
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. For this purpose, it is preferable that the ionization potential is small, the transparency to visible light is high, the hole mobility is large, the stability is excellent, and impurities that become traps are less likely to be generated during manufacture 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 general formula (VIII). In particular, a polymer composed of a repeating unit represented by the following general formula (VIII) is preferable. In this case, Ar ^a or Ar ^b may be different in each repeating unit.

(In general formula (VIII), Ar ^a and Ar ^b each independently represents 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, and pyrene having one or two free valences. A ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, a fluorene ring, or the like, a 6-membered monocyclic ring or a 2-5 condensed ring, or a group in which these rings are connected by a direct bond Is mentioned.

  Examples of the aromatic heterocyclic group which may have a substituent include, for example, a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, having one or two free valences. Imidazole ring, oxadiazole ring, indole ring, 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 Such as azulene ring, it includes groups monocyclic or 2-4 fused ring and these five- or six-membered ring is formed by connecting a direct bond or two or more rings.

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

Examples of the substituent that the aromatic hydrocarbon group and 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.

Examples of the polyarylene derivative include a polymer having in its repeating unit an arylene group such as an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent exemplified as the aforementioned Ar ^a or Ar ^b. .
As the polyarylene derivative, a polymer having a repeating unit of the following general formula (IX-1) and / or the following formula (IX-2) is preferable.

(In the general formula (IX-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 or 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, they are contained in one molecule. And a plurality of R ^a or R ^b may be the same or different, and adjacent R ^a or R ^b may form a ring.)

(In the general formula (IX-2), R ^e and R ^f are independently the same as R ^a , R ^b , R ^c or R ^{d in the} general formula (IX-1). Each independently 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 —O—, —BR ¹⁰³ —, —NR ¹⁰³ —, —SiR ¹⁰³ ₂ —, —PR ¹⁰³ —, —SR ¹⁰³ —, —CR ¹⁰³ ₂ — or a group formed by bonding thereof. It is. R ¹⁰³ is
Represents a hydrogen atom or any organic group. The organic group in the present invention is a group containing at least one carbon atom.

  The polyarylene derivative includes, in addition to the repeating unit consisting of the general formula (IX-1) and / or the general formula (IX-2), further a repeating unit represented by the following general formula (IX-3) It is preferable to have.

(In the general formula (IX-3), Ar ^{c to} Ar ^j each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent. V and w are Each independently represents 0 or 1.)
Specific examples of Ar ^{c to} Ar ^j are the same as Ar ^a and Ar ^b in the general formula (VIII).
Specific examples of the general formulas (IX-1) to (IX-3) and 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 also 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 group, trifluorovinyl group, styryl group, acrylic group, methacryloyl group and cinnamoyl group. A group derived from benzocyclobutene and the like.
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 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 An oligothiophene derivative, a condensed polycyclic aromatic derivative, a metal complex and the like. Of these, 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. are preferable. In particular, a triphenylamine derivative is preferable.

Examples of the crosslinkable compound include those in which a crosslinkable group is bonded to a main chain or a 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 is crosslinked to the general formula (VIII) or the general formulas (IX-1) to (IX-3). A polymer having a repeating unit in which a functional group is bonded directly or via a linking group is preferred.

In order to form a hole transport layer 4 by crosslinking a crosslinkable compound, a composition for forming a hole transport layer in which a 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 further contain a coating property improving agent such as a leveling agent or an antifoaming agent; an electron accepting compound; a binder resin;

The composition for forming a hole transport layer usually contains a crosslinkable compound in an amount of 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 weight or less. Preferably it is 20 weight% or less, More preferably, it contains 10 weight% 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 active 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 400 ° C. or lower.
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 higher for 1 minute or longer can be used.

In the case of irradiation with active energy such as light, irradiation is performed by directly using an ultraviolet light source such as an ultra-high pressure mercury lamp or a high pressure mercury lamp, or by using a mask aligner or a conveyor type light irradiation device incorporating the above-mentioned light source. The method of doing is mentioned. 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.
The film thickness of the hole transport layer 4 thus formed is usually 5 nm or more, preferably 10 nm or more, and usually 300 nm or less, preferably 100 nm or less.

[Light emitting layer]
A light emitting layer 4 is usually provided on the hole injection layer 3. The light emitting layer 4 is, for example, a layer containing the above-described light emitting material. Between the electrodes to which an electric field is applied, the holes injected from the anode 2 through the hole injection layer 3 and the cathode 6 through the electron transport layer 5 are injected. It is a layer which is excited by recombination with the emitted electrons and becomes a main light emitting source. The light emitting layer 4 preferably contains a light emitting material (dopant) and one or more host materials. The light emitting layer 4 further preferably contains the charge transport material of the present invention as a host material. The light emitting layer 4 may be formed by a vacuum deposition method, but is particularly preferably a layer produced by a wet film forming method using the composition for organic electroluminescent elements of the present invention. Here, as described above, the wet film forming method is a method in which a composition containing a solvent is formed by spin coating, spray coating, dip coating, die coating, flexographic printing, screen printing, an ink jet method, or the like.

In addition, the light emitting layer 4 may contain other materials and components as long as the performance of the present invention is not impaired.
In general, in the organic electroluminescent element, when the same material is used, the effective electric field increases as the film thickness between the electrodes decreases. As a result, the injected current increases and the drive voltage decreases. For this reason, the driving voltage of the organic electroluminescence device decreases when the total film thickness between the electrodes is thin, but if it is too thin, a short circuit occurs due to the protrusion caused by the electrode such as ITO. Necessary.

In the present invention, in addition to the light emitting layer 4, when the organic layer such as the hole injection layer 3 and the electron transport layer 5 described later is provided, the light emitting layer 4 and other organic materials such as the hole injection layer 3 and the electron transport layer 5 are used. The total film thickness combined with the layers is usually 30 nm or more, preferably 50 nm or more, and more preferably 100 nm or more. The upper limit of the total film thickness is usually 1000 nm, preferably 500 nm, more preferably 300 nm. Further, when the hole injection layer 3 other than the light emitting layer 4 and the electron injection layer 5 described later have high conductivity, the amount of charge injected into the light emitting layer 4 increases. Therefore, for example, the thickness of the hole injection layer 3 can be increased to reduce the thickness of the light emitting layer 4, and the drive voltage can be lowered while maintaining the total thickness to some extent.
Therefore, the thickness of the light emitting layer 4 is usually 10 nm or more, preferably 20 nm or more, and usually 300 nm or less, preferably 200 nm or less. When the element of the present invention has only the light emitting layer 4 between the anode and the cathode, the thickness of the light emitting layer 4 is usually 30 nm or more, preferably 50 nm or more, usually 500 nm or less, preferably 300 nm or less. is there.

[Hole blocking layer]
A hole blocking layer 6 may be provided between the light emitting layer 5 and an electron injection layer 8 described later. The hole blocking layer 6 is a layer 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. Further, a compound having at least one pyridine ring substituted at the 2,4,6-position described in International Publication No. 2005-022962 is also preferable as the material for the hole blocking layer 6.

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 a ratio.
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 forming method, a vapor 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, usually 100 nm or less, preferably 50 nm or less.

[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 transporting 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 having high electron mobility are efficiently transported. The compound which can be used is used. Examples of the compound satisfying such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline, oxadiazole derivatives , Distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline compounds ( JP-A-6-207169), phenanthroline derivative (JP-A-5-331459), 2-t-butyl-9,10-N, N'-dicyanoanthraquinonediimine, n-type hydrogenated amorphous silicon carbide , N-type zinc sulfide, n-type Sele Zinc oxide and the like.

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.

[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. Specific examples thereof include alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium. The film thickness is usually 0.1 nm or more, preferably 5 nm or less.

  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 ( (As described in JP-A-10-270171, JP-A-2002-1000047, JP-A-2002-1000048, etc.), it is possible to improve the electron injection / transport properties and achieve excellent film quality. preferable. The film thickness in this case is usually 5 nm or more, preferably 10 nm or more, 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.

[cathode]
The cathode 9 plays a role of injecting electrons into a layer on the light emitting layer 5 side (such as the electron injection layer 8 or the light emitting layer 5).
As the material of the cathode 9, the material used for the anode 2 can be used. However, in order to perform electron injection efficiently, a metal having a low work function is preferable. For example, tin, magnesium, indium, calcium, A suitable metal such as aluminum or 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.

[Other layers]
The organic electroluminescent element according to the present invention may have another configuration without departing from the gist thereof. For example, as long as the performance is not impaired, an arbitrary layer other than the above layers may be provided between the anode 2 and the cathode 9, and an arbitrary layer may be omitted.
Further, at the interface between the cathode 9 and the light emitting layer 5 or the electron transport layer 7, for example, lithium fluoride (LiF), magnesium fluoride (MgF ₂ ), lithium oxide (Li ₂ O), cesium carbonate (II) (CsCO ₃ Inserting an ultra-thin insulating film (0.1 to 5 nm) formed by the above method is also an effective method for improving the efficiency of the device (Applied Physics Letters, 1997, Vol. 70, pp. 152; JP-A-10-74586; IE
EE Transactions on Electron Devices, 1 997, Vol. 44, pp. 1245; SID 04 Digest, pp. 154 etc.).

Moreover, the structure of the organic electroluminescent element of the present invention is not limited to the above, and the stacking order can be changed. Specifically, a cathode 9, an electron injection layer 8, an electron transport layer 7, a hole blocking layer 6, a light emitting layer 5, a hole transport layer 4, a hole injection layer 3, and an anode 2 are sequentially stacked on the substrate 1. It is good also as the structure made.
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 above as long as the effects of the present invention are not significantly impaired.

<Organic EL display and organic EL lighting>
The organic EL display and organic EL illumination of the present invention comprise the above-described organic electroluminescent element of the present invention. There is no restriction | limiting in particular about the type and structure of the organic electroluminescent display of this invention, and organic electroluminescent illumination, It can assemble in accordance with a conventional method using the organic electroluminescent element of this invention.

  For example, the organic EL display and the organic EL display of the present invention can be obtained by the method described in “Organic EL display” (Ohm, August 20, 2004, published by Shizushi Tokito, Chiba Adachi, Hideyuki Murata). EL illumination can be formed.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples, and the present invention can be arbitrarily modified and implemented without departing from the gist thereof.
[Synthesis of Compound I]
(Synthesis of Compound 1)

Under a nitrogen atmosphere, [1,1 ′: 3 ′, 1 ″] terphenyl-3-ylboronic acid 3.00 g (10.9 mmol), tris (4-bromophenyl) amine 2.64 g (0.5 times mol), toluene 56 ml, Tetrakis (triphenylphosphine) palladium (0) 0.316 g (0.025 times mol) was added to a mixed solution of ethanol 27 ml and 2M aqueous sodium carbonate solution 13.5 ml (2.5 times mol), and the reaction was carried out at reflux temperature for 2 hours. After completion of the reaction, the reaction mixture was cooled to room temperature, and the liquid separation and organic layer were washed and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure to obtain 5.1 g of Intermediate 1.

  11,12-Dihydroindolo [2,3-a] carbazole 5.0 g (19.5 mmol) to 3-Bromobiphenyl (1.0 times mol), Sodium tert-Butoxide (3.0 times mol), Tri (tert-butyl) phosphine (0.1 times mol) ), A toluene suspension of Pd2 (dba) 3 (0.05-fold mol) was reacted at an internal temperature of 65 ° C. to obtain 12.1 g of a crude intermediate 2 (LC purity 83.5%).

  Intermediate 2 40 g (0.49 mmol), 3-Bromoiodobenzene 83.1 g (3 times mol), potassium carbonate 40.6 g (3.0 times mol), copper powder 6.22 g (1 times mol), tetraglyme 200 ml mixed solution 200 The reaction was carried out at 7 ° C for 7 hours. The reaction solution was filtered through celite and purified by column chromatography to obtain 34.9 g of Intermediate 3.

  Intermediate 3 33.0 g (58.6 mmol) of a THF solution was cooled to −78 ° C., and 1.6 M butyllithium (1.2 times mol) was added dropwise. The progress of the reaction was monitored by LC, and it was confirmed that bromine in all raw materials was replaced with lithium, and trimethyl borate (3.2 times mol) was reacted. After completion of the reaction, the mixture was treated with 1N hydrochloric acid, the liquid separation and the organic layer were washed, and the solvent was concentrated. The residue was purified by column chromatography to obtain 21.2 g of Intermediate 4.

To 2550 g (33.9 mmol) of Intermediate 1 and 19.7 g (1.1 times mol) of Intermediate 4 in 550 ml of toluene: ethanol = 2: 1 mixture, 34 ml (2 times mol) of 2M sodium carbonate aqueous solution was added and degassed with nitrogen gas. Then, 1.18 g (0.03 times mol) of tetrakis (triphenylphosphine) palladium (0) was added, and the mixture was reacted at a solvent reflux temperature (internal temperature 71 ° C.) for 17 hours and 15 minutes. After completion of the reaction, extraction, the organic layer was washed, dried over magnesium sulfate, and the solvent was distilled off under reduced pressure. The residue was purified by silica gel column chromatography to obtain 21.2 g of compound 1.
About the physical-property value of the compound 1, it is as follows.

[Physical property values]
Analytical method MALDI-MS method m / z 1183.5 (M ⁺ )
¹ H-NMR (400 MHz): 7.12-7.67 (53H, m), 7.85-7.86 (4H, m), 8.15 (s, 2H),
8.18-8.21 (m, 2H)
[IP calculation method]
(STEP 1: Generation of a sufficient number of sampling initial molecular structures satisfying statistical physics to eliminate arbitraryness) A three-dimensional molecular structure was created by molecular modeling for a compound to be calculated that was considered suitable.
The initial molecular structure was sampled for the stereomolecular structure using the Stochastic Monte Carlo method.

In the method of sampling the structure using the Stochastic Monte Carlo method, first, a temporary three-dimensional molecular structure created by modeling was randomly changed to generate a new structure. And the transition probability between the structures was calculated using the energy values of the old and new structures. In addition, when a random number is generated in the range [0,1] and the random number is less than or equal to the transition probability, the new structure is adopted as a more stable structure. In addition, when the random number is larger than the transition probability, the new structure is not energetically stable, so the old structure is adopted as the stable structure. This procedure was repeated to obtain a plurality of local structures that are stable in terms of energy potential (local minimum structures). At that time, the number of local minimum structures was generated so that the structure average of Boltzman distribution could be reproduced sufficiently. Finally, a total of 10 local minimum structures were generated.

  In the calculation of the Stochastic Monte Carlo method, the maximum random offset was set to 0.05 nm when calculating the molecular energy, and the force field used was MMFF94 (Halgren, T.A. J. Comput. Chem. 1996, 17, 490). The actual calculation was performed using ChemBio3D Ultra 12.0 (Molecular Modeling Software by CambridgeSoft Corporation).

(STEP 2: Optimization of stereomolecular structure by quantum chemical calculation)
The structure optimization in the quantum chemical calculation was performed on the 10 local minimum molecular structures obtained in the above (STEP 1).
In the structural optimization by the semi-empirical quantum chemical calculation in STEP2, the optimization of the ground state was performed using the PM6 method (Stewart, JJPJ Mol. Model. 2007, 13, 1173). On top of that, the density functional method was used as non-empirical molecular orbital calculation with higher calculation accuracy. At that time, the hybrid B3LYP (Becke, ADJ Chem. Phys. 1993, 98, 5648) is used as the functional, and the basis function is 6-31G **. The structure was calculated. The 10 optimized local minimum optimized structures thus obtained were used as molecular structures for estimating IP.

  All molecular optimization calculations were performed using the Gaussian 09 program (Gaussian 09, Revision A.1, MJ Frisch, GW Trucks, HB Schlegel, GE Scuseria, MA Robb, JR Cheeseman, G. Scalmani, V. Barone, B. Mennucci, GA Petersson, H. Nakatsuji, M. Caricato, X. Li, HP Hratchian, AF Izmaylov, J. Bloino, G. Zheng, JL Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, JA Montgomery, Jr., JE Peralta, F. Ogliaro, M. Bearpark, JJ Heyd, E. Brothers, KN Kudin, VN Staroverov, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, JC Burant, SS Iyengar, J. Tomasi, M. Cossi, N. Rega, JM Millam, M. Klene, JE Knox, JB Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, RE Stratmann, O. Yazyev, AJ Austin, R. Cammi, C. Pomelli, JW Ochterski, RL Martin, K. Morokuma, VG Zakrzewski, GA Voth, P. Salvador, JJ Dannenberg, S. Dapprich, AD Daniels, O. Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, and D. J. Fox, Gaussian, Inc., Wallingford CT, 2009.).

(STEP3: IP calculation)
Using the values of the orbital energy of HOMO in the 10 local minimum structures finally obtained by non-empirical quantum chemistry calculations in the above (STEP 2: Optimization of stereomolecular structure by quantum chemistry calculations) In the local minimum, the IP value was calculated by the equation IP = − (HOMO orbital energy value) based on Yanak's theorem (also calculated by EA = − (LUMO orbital energy)). Furthermore, an average value (IP average value) was determined from the IP values for 10 local minimums.

[Calculation method of EA]
This was carried out in the same manner as in (STEP 1: generation of molecular structure) to (STEP 2: optimization of structure).
Further, in the above (STEP3: IP calculation), similarly, using the 10 optimized structure LUMO energy values finally obtained in (STEP2: structure optimization), the EA value is determined by Yanak's theorem. From the orbital energy, EA = − (LUMO orbital energy. The average value of these EAs was taken as the EA value of the unit of the target compound.

  From the above calculation results, the compound of the present invention has preferable IP and EA, and can be adjusted by selecting a substituent, and is preferably a charge (injection) transport material of an organic electroluminescent device. As a component of any layer (see Table 1).

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Electron injection layer 9 Cathode

Claims (10)

A monoamine compound represented by the following general formula (1).

(In General Formula (1), ArG ^{1 to} ArG ³ each have an aromatic ring group having 3 to 30 carbon atoms which may have a substituent, or 3 to 60 carbon atoms which may have a substituent. Represents two or more aromatic ring assembly group groups, and Z represents a divalent substitution consisting of two or more aromatic ring assembly groups having 3 to 60 carbon atoms which may have a substituent. Represents a group) In the said General formula (1), Z is a monoamine compound of Claim 1 represented by following General formula (2).

(However, in Structural Formula (2), n = 2 to 8, and the substituent R ¹ of the benzene ring in the parenthesis independently represents a hydrogen atom or an alkyl group.) ^3. The monoamine according to claim 1, wherein in the general formula (1), ArG ³ is an optionally substituted two or more aromatic ring assembly group having 3 to 60 carbon atoms. Compound The monoamine compound according to claim 1 or 2, wherein, in the general formula (1), any one of ArG ^{1 to} ArG ³ has a partial structure represented by the following general formula (3).

  The monoamine compound according to any one of claims 1 to 4, wherein the solubility in a solvent in which an organic solvent having a high boiling point of 100 ° C or more has a component of 20% or more is 1% by mass or more.   The charge transport material which consists of a monoamine compound of any one of Claims 1-5.   A charge transport film composition comprising the charge transport material according to claim 6 and a solvent. 7. An organic electroluminescence device comprising an anode, a cathode, and a light emitting layer provided between both electrodes on a substrate, the organic electroluminescence device comprising the light emitting layer containing the charge transport material according to claim 6. element.   An organic EL display device comprising the organic electroluminescent element according to claim 8.   An organic EL illumination comprising the organic electroluminescent element according to claim 8.

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