JP6441698B2 - Charge transport material - Google Patents

Description

  The present invention relates to a charge transport material having a triphenylamine-based unit as a charge transport unit in a side chain.

  Organic electroluminescent devices such as organic light emitting diodes (OLEDs) are self-emitting devices that emit light from organic materials in the light emitting layer by recombining holes and electrons injected from the anode and cathode in the light emitting layer. is there.

  For organic electroluminescent elements, materials for organic electroluminescent elements including charge transport materials such as hole transport materials are used. The charge transport material not only has the ability to transport charges to the light-emitting layer, but also functions to prevent excitons formed by recombination of holes and electrons in the light-emitting layer from entering the charge transport layer. In addition, it is considered that the efficiency of the green and blue OLED elements can be improved particularly when the hole transport material has high charge mobility and high triplet energy.

  For example, Patent Document 1 discloses a polymerizable compound having a triphenylamine unit in the side chain as a hole transporting material.

JP 2008-91894 A

  However, since the hole transport material disclosed in Patent Document 1 is inferior in charge resistance, an organic electroluminescent device having a hole transport layer or a hole injection layer containing such a material has a short device life (durability). Inferior). On the other hand, it may be proposed to use a hole transport material in which a unit for imparting charge resistance is provided in addition to the unit disclosed in Patent Document 1 for the hole transport layer and the hole injection layer. However, in such a case, there is a problem that the ratio of the charge transport unit per unit density is lowered and the charge transport performance is lowered.

  Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to provide a hole transport material for an organic electroluminescent element with improved durability.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a charge transport material having a structural unit of a predetermined structure as a material for an organic electroluminescent element. The headline, the present invention has been completed.

  According to the charge transport material according to the present invention, the durability of the organic electroluminescent element can be improved.

1 is a diagram illustrating a structure of an organic electroluminescence device according to an embodiment of the present invention.

  The present invention provides a charge transport material having a structural unit (A) represented by the following formula (1).

However, ^one of R ¹ , R ² and R ⁵ is a substituent (a) represented by the following formula (3):

In the above formula (3), X represents a linking group constituting the main chain, and A represents a single bond, or a halogen atom, cyano group, alkyl group, aryl group, amino group, alkoxy group, carbazole group, fluorene group. Represents a divalent aromatic group or heterocyclic group substituted or unsubstituted with at least one substituent selected from the group consisting of a heterocyclic group and a silyl group,
And the remaining R ¹ , R ² and R ⁵ are a hydrogen atom or a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group and a silyl group. Represents a monovalent aromatic group or heterocyclic group substituted or unsubstituted with at least one substituent selected from;
R ³ , R ⁴ , R ^{6 to} R ⁸ , R ^{10 to} R ¹² , R ¹⁴ and R ¹⁵ are each independently a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group or an alkoxy group. And R ⁹ and R ¹³ each independently represents a hydrogen atom, an aryl group, a tertiary butyl group, a carbazole group, a fluorene group, a heterocyclic group, or a formula (9): —N (R ²⁰ ) (R ²¹ ) — represents an amino group, and at least one of R ⁹ and R ¹³ is an aryl group, a tertiary butyl group, a carbazole group, a fluorene group, a heterocyclic group, or a formula (9) ^{: -N (R 20) (R} 21) - an amino group of this case, in the above formula ^{(9), R 20} is an aryl group, and ^{R 21} is an arylene group, this , ^{R 21} to form a ring with ^{R 8} or ^{R 10.}

The charge transport material includes a main chain type charge transport material having a charge transport unit in the main chain and a side chain type charge transport material having a charge transport unit in the side chain. Side chain charge transport materials generally tend to have lower charge mobility than main chain materials. As a result of intensive studies on the reason why the side chain type charge transporting material has low charge mobility, the main chain skeleton of the side chain type material is not involved in charge transport, It was estimated that the charge transport performance was low. For this reason, as a result of intensive studies on the structure of a charge transport material having a high density (ratio) of charge transport units, a charge transport material having a triphenylamine unit into which a specific substituent is introduced solves the above problem. I found it. That is, the charge transport material of the present invention is characterized in that in the structural unit (A), the substituents “R ⁹ ” and / or “R ¹³ ” are specific groups such as a phenyl group. The charge transport material [constituent unit (A)] of the present invention has a substituent “R ⁹ ” and / or “R ¹³ ” for imparting or improving charge resistance to a triphenylamine-based unit having excellent charge transportability. It has a structure to be introduced. For this reason, the organic electroluminescent device having the charge transport material of the present invention has excellent charge resistance, and particularly when used as a hole transport material, it can reduce the deterioration effect on electrons and improve the device life. . In addition, the organic electroluminescence device having the charge transport material of the present invention has a sufficient ratio of charge transport units per unit density, and therefore has excellent charge transport performance (prevents deterioration of charge transport performance). It is possible.

  In addition, the charge transport material of the present invention preferably further has a structural unit (B) represented by the following formula (2) or a structural unit (B ′) represented by the following formula (8).

  According to this embodiment, by further introducing the structural unit (B) or the structural unit (B ′) of the above formula (2), crosslinking or film formation can be performed while suppressing a decrease in charge transport ability to some extent. Conventionally, when a layer (for example, a hole injection layer or a hole transport layer) is formed using a charge transport material, it is necessary to perform crosslinking or curing after film formation. It is necessary to have. However, in charge transport materials in which a unit having a crosslinking group is separately introduced, the ratio of charge transport capacity per volume is further reduced in the side chain type charge transport material compared to the main chain type, and driving of the organic electroluminescent device is reduced. There was a problem of causing an increase in voltage. In particular, the charge transport material preferably further includes the structural unit (B) of the above formula (2) or the structural unit (B ′) of the formula (8). The charge transport material according to the embodiment serves as both a unit having a crosslinking group and a charge transport unit (amine unit). For this reason, since the charge transport material according to the embodiment has a high density (ratio) of the charge transport unit, it is possible to impart crosslinkability while maintaining high charge transport performance. Moreover, the charge transport material of the said form can be synthesize | combined easily and is preferable also from a viewpoint of mass production.

  Therefore, since the charge transport material of the present invention is excellent in charge transport property, in the organic electroluminescent device having the charge transport material of the present invention, it is possible to effectively suppress / prevent a decrease in driving voltage and improve the efficiency of the device.

  Embodiments of the present invention will be described below. In addition, this invention is not limited only to the following embodiment. Further, in this specification, the structural unit (A) of the formula (1) is simply referred to as “structural unit (A)”, and the structural unit (B) of the formula (2) is simply referred to as “structural unit (B)”. The structural unit (B ′) in (8) is also simply referred to as “structural unit (B ′)”. In this specification, “x to y” indicating a range means “x or more and y or less”. Unless otherwise specified, measurement of operation and physical properties is performed under conditions of room temperature (20 to 25 ° C.) / Relative humidity 40 to 50%.

[Charge transport material]
The charge transport material according to the present invention has a structural unit (A) represented by the following formula (1). In the structural unit (A), a substituent “R ⁹ ” and / or “R ¹³ ” for imparting charge resistance is introduced into a triphenylamine-based unit having excellent charge transportability. For this reason, the organic electroluminescent device having the charge transport material of the present invention has excellent charge resistance, and particularly when used as a hole transport material, it can reduce the deterioration effect on electrons and improve the device life. . Moreover, since the organic electroluminescent element which has the charge transport material of this invention suppresses the fall of the ratio of the charge transport unit per unit density, it can exhibit high charge transport performance.

In the above formula (1), one of R ¹ , R ² and R ⁵ is a substituent (a) represented by the following formula (3).

  In the present specification, the substituent (a) in the formula (3) is also simply referred to as “substituent (a)”.

  In formula (3) representing the substituent (a), X represents a linking group constituting the main chain. Here, the linking group constituting the main chain is not particularly limited as long as it is a structure capable of constituting the main chain of the structural unit (A). Specifically, the following structures are mentioned.

  Among the above linking groups, X is preferably a linking group having the following structure.

In the above formula (3), A represents a single bond or a halogen atom, a cyano group (—CN), an alkyl group, an aryl group, an amino group (—NH ₂ ), an alkoxy group, a carbazole group, a fluorene group, a complex It represents a divalent aromatic group or heterocyclic group that is substituted or unsubstituted with at least one substituent selected from the group consisting of a cyclic group and a silyl group.

  Here, the divalent aromatic group is not particularly limited as long as it is a ring-derived group composed of a carbon atom and a hydrogen atom. Specifically, it is derived from a benzene ring (phenylene group), a biphenyl ring (biphenylene group), a naphthalene ring (naphthalenyl group), an anthracene ring (anthracenyl group) and a fluorene ring (fluorenyl group). Of these, the aromatic group is preferably a group derived from a benzene ring (phenylene group) or a group derived from a fluorene ring (fluorenyl group).

  The divalent heterocyclic group is not particularly limited as long as it is a group derived from a ring composed of one or more heteroatoms selected from a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, and a sulfur atom. Specifically, thiophene ring, dithienothiophene ring, cyclopentadithiophene ring, phenylthiophene ring, diphenylthiophene ring, imidazole ring, oxazole ring, isoxazole ring, thiazole ring, pyrrole ring, furan ring, benzofuran ring, iso Benzofuran ring, coumarin ring (for example, 3,4-dihydrocoumarin), benzimidazole ring, benzoxazole ring, rhodanine ring, pyrazolone ring, imidazolone ring, pyran ring, pyridine ring, pyrazine ring, pyrazole ring, pyrimidine ring, pyridazine ring , Triazine ring, fluorene ring, benzothiophene ring, benzo (c) thiophene ring, benzimidazole ring, benzoxazole ring, benzisoxazole ring, benzothiazole ring, indole ring, phthalazine ring, sinanoline ring, quina Phosphorus ring, carbazole ring, carboline ring, diazacarboline ring (in which one of carbon atoms of carboline is replaced by nitrogen atom), 1,10-phenanthroline ring, quinone ring, rhodanine ring, dirhodanine ring, thiohydantoin ring , Pyrazolone ring and pyrazoline ring. A plurality of these heterocycles may be used in combination, for example, phenylpyridine (eg, 4-phenylpyridine), styrylthiophene (eg, 2-styrylthiophene), 2- (9H-fluoren-2-yl) thiophene, 2-phenylbenzo [b] thiophene, phenylbithiophene ring, (1,1-diphenyl-4-phenyl) -1,3-butadiene, 1,4-diphenyl-1,3-dibutadiene, 4- (phenylmethylene) ) -2,5-cyclohexadiene, and those derived from a phenyldithienothiophene ring. Of these, a carbazole ring is preferred.

  Examples of the halogen atom that may be introduced into the divalent aromatic group or heterocyclic group include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

  The alkyl group that may be introduced into the divalent aromatic group or heterocyclic group is not particularly limited, but may be a linear or branched alkyl group having 1 to 24 carbon atoms. Specifically, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, Neopentyl group, 1,2-dimethylpropyl group, n-hexyl group, isohexyl group, 1,3-dimethylbutyl group, 1-isopropylpropyl group, 1,2-dimethylbutyl group, n-heptyl group, 1,4- Dimethylpentyl group, 3-ethylpentyl group, 2-methyl-1-isopropylpropyl group, 1-ethyl-3-methylbutyl group, n-octyl group, 2-ethylhexyl group, 3-methyl-1-isopropylbutyl group, 2 -Methyl-1-isopropyl group, 1-t-butyl-2-methylpropyl group, n-nonyl group, 3,5,5-trimethylhexyl Group, n-decyl group, isodecyl group, n-undecyl group, 1-methyldecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, Examples include n-octadecyl group, n-nonadecyl group, n-eicosyl group, n-heneicosyl group, n-docosyl group, n-tricosyl group, n-tetracosyl group and the like. Of these, a linear or branched alkyl group having 1 to 8 carbon atoms is preferable.

  The aryl group that may be introduced into the divalent aromatic group or heterocyclic group is not particularly limited, but may be an aryl group having 6 to 20 carbon atoms. Specifically, phenyl group, benzyl group, phenethyl group, o-, m- or p-tolyl group, 2,3- or 2,4-xylyl group, mesityl group, naphthyl group, anthryl group, phenanthryl group, biphenylyl Group, benzhydryl group, trityl group, pyrenyl group and the like. Of these, a phenyl group is preferred.

  The alkoxy group that may be introduced into the divalent aromatic group or heterocyclic group is not particularly limited, but may be a linear or branched alkoxy group having 1 to 24 carbon atoms. Specifically, methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group, nonyloxy group, decyloxy group, undecyloxy group, dodecyloxy group Group, tridecyloxy group, tetradecyloxy group, pentadecyloxy group, hexadecyloxy group, heptadecyloxy group, octadecyloxy group, 2-ethylhexyloxy group, 3-ethylpentyloxy group and the like. Of these, a linear or branched alkoxy group having 1 to 8 carbon atoms is preferable.

  The carbazole group that may be introduced into the divalent aromatic group or heterocyclic group represents any of the following. In the following, Z represents a hydrogen atom, an aryl group, an alkyl group or an alkoxy group. Here, the alkyl group is not particularly limited, and is the same as the definition in the alkyl group and alkoxy group that may be introduced into the divalent aromatic group or heterocyclic group, and thus the description thereof is omitted here.

  The fluorene group that may be introduced into the divalent aromatic group or heterocyclic group represents any of the following. In the following, Z and Z ′ each independently represent a hydrogen atom, an alkyl group, or an alkoxy group. Here, the alkyl group is not particularly limited, and is the same as the definition in the alkyl group and alkoxy group that may be introduced into the divalent aromatic group or heterocyclic group, and thus the description thereof is omitted here.

  The heterocyclic group that may be introduced into the divalent aromatic group or heterocyclic group is not particularly limited, and specifically, the heterocyclic ring except that the valence of the divalent aromatic group is changed. Since the heterocyclic group similar to what was described by group is illustrated, description is abbreviate | omitted here.

The silyl group that may be introduced into the divalent aromatic group or heterocyclic group is represented by the formula: —Si (Z ₁ ) (Z ₂ ) (Z ₃ ). Here, Z < ₁ > -Z < ₃ > represents an alkyl group, an alkoxy group, and an aryl group. Here, Z _{1 to} Z ₃ may be the same or different. Here, the alkyl group and the alkoxy group are not particularly limited, and are the same as the definitions in the alkyl group and the alkoxy group that may be introduced into the divalent aromatic group or heterocyclic group. Is omitted.

  Among these, A is preferably a single bond, a divalent aromatic group substituted with a divalent aromatic group or a heterocyclic group, and preferably a single bond or a divalent aromatic group. .

The substituent (a) bonded to the linking group (X) constituting the main chain may be any of R ¹ , R ² or R ⁵ , but R ¹ is preferably the substituent (a). When such a structure is adopted, the quinoid structure and the accompanying side reaction that occur in the charge transport of the amine unit are reduced by introduction of substituents, so that the charge resistance of the device can be further improved.

Further, as described above, in the above formula (1), ^one of R ¹ , R ² and R ⁵ is the substituent (a), but the remaining R ¹ , R ² and R ⁵ which are not the substituent (a). Is substituted with a hydrogen atom or at least one substituent selected from the group consisting of a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group and a silyl group. Or an unsubstituted monovalent aromatic group or heterocyclic group. In this case, the remaining R ¹ , R ² and R ⁵ may be the same or different from each other. Further, the definitions of the remaining R ¹ , R ² and R ⁵ that are not the substituent (a) are the same as the definitions in the substituent (a), and thus the description thereof is omitted here. However, the monovalent aromatic group is to be read by changing the valence of the divalent aromatic group in the substituent (a). Similarly, the monovalent heterocyclic group shall be read by changing the valence of the divalent heterocyclic group in the substituent (a).

Of these, the remaining R ¹ , R ² and R ⁵ are preferably a hydrogen atom, an alkyl group or an aryl group, and more preferably a hydrogen atom or an aryl group.

In the above formula (1), R ³ , R ⁴ , R ^{6 to} R ⁸ , R ^{10 to} R ¹² , R ¹⁴ and R ¹⁵ are each independently a hydrogen atom, a halogen atom, a cyano group (—CN), An alkyl group, an aryl group, an amino group (—NH ₂ ), an alkoxy group, a carbazole group, or a silyl group is represented. At this time, R ³ , R ⁴ , R ^{6 to} R ⁸ , R ^{10 to} R ¹² , R ¹⁴ and R ¹⁵ may be the same or different. Here, the halogen atom, the alkyl group, the aryl group, the alkoxy group, the carbazole group, and the silyl group are not particularly limited, and are defined as the substituents that may be introduced into the divalent aromatic group or heterocyclic group. Since it is the same, description is abbreviate | omitted here.

Among these, R ³ , R ⁴ , R ^{6 to} R ⁸ , R ^{10 to} R ¹² , R ¹⁴ and R ¹⁵ are each independently a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. Preferably, they are a hydrogen atom and an aryl group.

In the above formula (1), R ⁹ and R ¹³ are each independently a hydrogen atom, an aryl group, a tertiary butyl group, a carbazole group, a fluorene group, a heterocyclic group, or a formula (9): —N (R ²⁰ ) ^{(R 21)} - represents an amino group. In this case, at least one of R ⁹ and R ¹³ is an aryl group, a tertiary butyl group, a carbazole group, a fluorene group, a heterocyclic group, or an amino group of the formula (9): —N (R ²⁰ ) (R ²¹ ) — Represents. Here, at least one of R ⁹ and R ¹³ is an aryl group, a tertiary butyl group, a carbazole group, a fluorene group, a heterocyclic group, or an amino group of the formula (9): —N (R ²⁰ ) (R ²¹ ) — Each may be the same or different as long as it represents a group. Here, the aryl group, carbazole group, and fluorene group are not particularly limited, and are the same as the definitions in the substituents that may be introduced into the divalent aromatic group or heterocyclic group, and thus the description thereof is omitted here. To do. Similarly, since the heterocyclic group has the same definition as in the substituent (a), the description thereof is omitted here. However, the heterocyclic group (monovalent heterocyclic group) is to be read by changing the valence of the divalent heterocyclic group in the substituent (a).

In the above formula (9), R ²⁰ is an aryl group. Here, the aryl group is not particularly limited and is the same as the definition in the substituent that may be introduced into the divalent aromatic group or heterocyclic group, and thus the description thereof is omitted here. Preferably, R ²⁰ is a phenyl group or a biphenylyl group. R ²¹ is an arylene group, which is linked to R ⁸ or R ¹⁰ to form a ring. Here, one bond type of R ²¹ is connected to the nitrogen atom of formula (9), and the other bond type is connected to R ⁸ or R ¹⁰ of formula (1) to form a ring. The arylene group as the substituent “R ²¹ ” is not particularly limited, and has the same definition except that the aryl group that may be introduced into the divalent aromatic group or heterocyclic group is changed to divalent. The description is omitted here. Preferably, R ²¹ is a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group.

Among these, considering the effect of improving the charge resistance (durability), solubility, etc., as a preferable combination of R ⁹ and R ¹³ , one is a hydrogen atom and the other is an aryl group; One is a hydrogen atom and the other is a carbazole group; one is a hydrogen atom and the other is a fluorene group; one is a hydrogen atom and the other is a formula (9): —N (R ²⁰ ) (R ²¹ ) -amino group. A more preferred combination of R ⁹ and R ¹³ includes one being a hydrogen atom and the other being an aryl group; both being an aryl group.

  Specifically, the structural unit (A) preferably has one of the following structures. The structural unit (A) is more preferably the following structures A1, A8, and A9.

  The charge transport material according to the present invention essentially has the structural unit (A) of the following formula (1), but may have other structural units in addition to the structural unit (A). Preferably, the charge transport material according to the present invention preferably has a triphenylamine unit or a fluorene unit having a crosslinking group in addition to the structural unit (A) of the following formula (1). According to the embodiment, since the structural unit (B) or (B ′) serves as both a unit having a crosslinking group and a charge transport unit, the charge transport material has a high ratio of charge transport units as a whole (high). Cross-linkability can be further imparted while ensuring charge transport performance). By the presence of a crosslinking group in the structural unit (B) or (B ′), a crosslinking reaction occurs by heating, so that it can be insolubilized in a solvent and a stronger film can be formed. For this reason, durability of an organic electroluminescent element can be improved more by using the charge transport material which concerns on this invention which has a structural unit (A) and a structural unit (B) or (B '). For example, even when another layer is formed on the layer containing the charge transport material, the layer containing the charge transport material is not or hardly dissolved in the solvent at the time of application. In addition, the charge transport material in this form can be easily synthesized and is preferable from the viewpoint of mass production. That is, according to a preferred embodiment of the present invention, the charge transport material preferably further has a structural unit (B) represented by the following formula (2) or a structural unit (B ′) represented by the following formula (8). .

  “The charge transport material according to the present invention has the structural unit (A) and the structural unit (B) or (B ′)” means that the charge transport material includes the structural unit (A) and the structural unit (B). The charge transport material includes the structural unit (A) and the structural unit (B ′), and the charge transport material includes the structural unit (A), the structural unit (B), and the structural unit (B ′). .

  The structural unit (B) of the above formula (2) serves as both a unit having a crosslinking group and a charge transport unit (amine unit). For this reason, since the charge transport material having the structural unit (B) of the above formula (2) has a high density (ratio) of the charge transport unit, it can impart crosslinkability while maintaining high charge transport performance. . Moreover, the charge transport material of the said form can be synthesize | combined easily and is preferable also from a viewpoint of mass production.

  In the present specification, the “crosslinking group” means a group that reacts (crosslinks) with the same or different group of structural units located nearby by heating or irradiation with active energy rays to form a new bond.

  In the above formula (2), Y represents a linking group constituting the main chain. Here, the linking group constituting the main chain is not particularly limited as long as it is a structure capable of constituting the main chain of the structural unit (B). Specifically, the example given by the structural unit (A) is mentioned similarly.

  Among the above linking groups, Y is preferably a linking group having the following structure.

In the above formula (2), B represents (i) a single bond, or (ii) a halogen atom, a cyano group (—CN), an alkyl group, an aryl group, an amino group (—NH ₂ ), an alkoxy group, or a carbazole. A substituted or unsubstituted divalent aromatic group or heterocyclic group substituted with at least one substituent selected from the group consisting of a group, a fluorene group, a heterocyclic group and a silyl group, or (iii) Formula (4) : Represents an amino group of —N (R ¹⁸ ) —R ¹⁹ —. Here, a halogen atom, an alkyl group, an aryl group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group and a silyl group are not particularly limited, and are introduced into the divalent aromatic group or heterocyclic group. Since the definitions are the same as those in the preferred substituents, the description thereof is omitted here. Similarly, the divalent aromatic group or heterocyclic group is not particularly limited, and is the same as defined for the substituent “A”, and thus the description thereof is omitted here.

Among these, B is substituted with at least one substituent selected from the group consisting of halogen atoms, cyano groups, alkyl groups, aryl groups, amino groups, alkoxy groups, carbazole groups, fluorene groups, heterocyclic groups, and silyl groups. It is preferably a substituted or unsubstituted divalent aromatic group or heterocyclic group. That is, in the above formula (1), R ¹ is selected from the group consisting of A, a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group, and a silyl group. A substituent (a) of the formula (3) which is a substituted or unsubstituted divalent aromatic group or heterocyclic group substituted with at least one substituent, and in the above formula (2), B is a halogen atom 2 which is substituted or unsubstituted with at least one substituent selected from the group consisting of an atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group and a silyl group A valent aromatic group or a heterocyclic group is preferred. When such a structure is adopted, the quinoid structure and the accompanying side reaction that occur in the charge transport of the amine unit are reduced by introduction of substituents, so that the charge resistance of the device can be further improved. In addition, as described above, the substituent A in the structural unit (A) and / or the substituent B in the structural unit (B), or the substituent D in the structural unit (B ′) is a divalent aromatic group or By using a heterocyclic group (in the case of the substituent D, a divalent carbazole group, a fluorene group, an aromatic group, or a heterocyclic group), it is configured as compared with the case where such a substituent is not introduced. Since the electrochemical stability of the unit can be improved, the lifetime of the element can be extended. Further, since the self-reactivity of the monomer before polymerization can be suppressed, handling (handling) in synthesis and production becomes easy.

In the above formula (4), R ¹⁸ is at least one selected from the group consisting of a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group, and a silyl group. An aromatic group or heterocyclic group substituted or unsubstituted with a substituent. Here, a halogen atom, an alkyl group, an aryl group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group and a silyl group are not particularly limited, and are introduced into the divalent aromatic group or heterocyclic group. Since the definitions are the same as those in the preferred substituents, the description thereof is omitted here. Similarly, the aromatic group or heterocyclic group is not particularly limited, and is the same as defined in the substituent “A”. Therefore, the description thereof is omitted here. However, the monovalent aromatic group is to be read by changing the valence of the divalent aromatic group in the substituent (a). Similarly, the monovalent heterocyclic group shall be read by changing the valence of the divalent heterocyclic group in the substituent (a). Preferably, R ¹⁸ is an aryl group or heterocyclic group substituted with an alkyl group. R ¹⁹ is substituted with at least one substituent selected from the group consisting of halogen atoms, cyano groups, alkyl groups, aryl groups, amino groups, alkoxy groups, carbazole groups, fluorene groups, heterocyclic groups, and silyl groups. Or an unsubstituted or divalent aromatic group or heterocyclic group. Here, a halogen atom, an alkyl group, an aryl group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group and a silyl group are not particularly limited, and are introduced into the divalent aromatic group or heterocyclic group. Since the definitions are the same as those in the preferred substituents, the description thereof is omitted here. Similarly, the divalent aromatic group or heterocyclic group is not particularly limited, and is the same as defined for the substituent “A”, and thus the description thereof is omitted here. Preferably, R ¹⁹ is a divalent aromatic group or heterocyclic group.

Among these, B is a single bond, a divalent aromatic group, a divalent aromatic group substituted with a heterocyclic group, or an amino group of the formula (4): —N (R ¹⁸ ) —R ¹⁹ —. Preferably, it is preferably a divalent aromatic group or an amino group of the formula (4): —N (R ¹⁸ ) —R ¹⁹ — In the above formula (2), K _a and K _b are A bridging group, a hydrogen atom, a halogen atom, a cyano group (—CN), an alkyl group, an aryl group, an amino group (—NH ₂ ), an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group or a silyl group is represented. In this case, K _a and K _b may be the same or different, but at least one of K _a and K _b represents a cross-linking group. Here, the halogen atom, the alkyl group, the aryl group, the alkoxy group, the carbazole group, the fluorene group, the heterocyclic group and the silyl group are not particularly limited, and may be introduced into the divalent aromatic group or heterocyclic group. Since the definitions for the substituents are the same as each other, the description thereof is omitted here. The cross-linking group is not particularly limited as long as it can induce a cross-linking reaction by heat or active energy rays, but the following structures are preferable. In addition, below, it illustrates as a phenylene group which has a crosslinking group of a structural unit (B). Thus, for example, in the first structure described above, —C (—R) ═CH ₂ is a bridging group.

In the above structure, the bonding position of the bridging group (for example, in the second structure, the bridging group: —C (—F) ═CF ₂ ) to the phenylene group is not particularly limited. Any of the 4-positions may be used, but the 4-position is preferred.

  In the above structure, R and R ′ each independently represents a hydrogen atom or an alkyl group. Here, the alkyl group is not particularly limited and is the same as the definition of the substituent that may be introduced into the divalent aromatic group or heterocyclic group, and thus the description thereof is omitted here. In the above structure, Ar is at least one substituent selected from the group consisting of a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group, and a silyl group. An aromatic group or a heterocyclic group substituted or unsubstituted by Here, a halogen atom, an alkyl group, an aryl group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group and a silyl group are not particularly limited, and are introduced into the divalent aromatic group or heterocyclic group. Since the definitions are the same as those in the preferred substituents, the description thereof is omitted here. Similarly, the aromatic group or heterocyclic group is not particularly limited, and is the same as defined in the substituent “A”. Therefore, the description thereof is omitted here. However, the monovalent aromatic group is to be read by changing the valence of the divalent aromatic group in the substituent (a). Similarly, the monovalent heterocyclic group shall be read by changing the valence of the divalent heterocyclic group in the substituent (a).

  Among these, in consideration of crosslinking reactivity, stability of the crosslinked structure, electrochemical stability, etc., a group derived from a benzocyclobutene ring having the following structure (bicyclo [4.2.0] octa-1,3,5 -Trienyl group) is preferred. From the viewpoint of reactivity (easiness of crosslinking), cyclic ether groups such as epoxy groups and oxetane groups, and vinyl ether groups are preferred.

In the above formula (2), the bridging groups (K _a , K _b ) may be directly bonded to the phenyl group of the triphenylamine-based unit, but may be bonded via a divalent linking group. Here, the divalent linking group is not particularly limited, but includes an oxygen atom (—O—), a carbonyl group (—C (═O) — group), a methylene group (—CH ₂ —), an ethylene group, and the like. Examples thereof include an alkylene group having 2 to 10 carbon atoms and an arylene group (for example, a phenylene group). Preferably, the bridging group (K _a , K _b ) is directly bonded to the phenyl group of the triphenylamine-based unit or bonded to the phenyl group of the triphenylamine-based unit via a phenylene group.

In the above formula (2), one of K _a and K _b is a hydrogen atom or a phenyl group, and the other is a crosslinking group; both are preferably a crosslinking group.

  According to the preferable form of this invention, it is preferable that a structural unit (B) is shown by a following formula.

In the above formulas, B, and _{K a} is the same as defined in the above formula (2).

  In the above formula (8), Y ′ represents a linking group constituting the main chain. Here, the linking group constituting the main chain is not particularly limited as long as it is a structure capable of constituting the main chain of the structural unit (B ′). Specifically, the example given by the structural unit (A) is mentioned similarly.

  Among the above linking groups, Y ′ is preferably a linking group having the following structure.

In the above formula (8), D represents (i) a single bond, or (ii) a halogen atom, a cyano group (—CN), an alkyl group, an aryl group, an amino group (—NH ₂ ), an alkoxy group, or a carbazole. And a divalent carbazole group, a fluorene group, an aromatic group or a heterocyclic group which is substituted or unsubstituted with at least one substituent selected from the group consisting of a group, a fluorene group, a heterocyclic group and a silyl group. Among these, D is selected from the group consisting of halogen atoms, cyano groups (—CN), alkyl groups, aryl groups, amino groups (—NH ₂ ), alkoxy groups, carbazole groups, fluorene groups, heterocyclic groups, and silyl groups. It is preferably a divalent carbazole group, fluorene group, aromatic group or heterocyclic group which is substituted or unsubstituted with at least one selected substituent.

  Here, a halogen atom, an alkyl group, an aryl group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group and a silyl group are not particularly limited, and are introduced into the divalent aromatic group or heterocyclic group. Since the definitions are the same as those in the preferred substituents, the description thereof is omitted here. Similarly, the divalent aromatic group or heterocyclic group is not particularly limited, and is the same as defined for the substituent “A”, and thus the description thereof is omitted here. The substituent D is not substituted with the same substituent. That is, for example, a fluorene group is not substituted with a fluorene group.

  In the present specification, the divalent carbazole group represents one of the following. In the following, Z represents a hydrogen atom, an alkyl group or an alkoxy group. Here, the alkyl group is not particularly limited, and is the same as the definition in the alkyl group and alkoxy group that may be introduced into the divalent aromatic group or heterocyclic group, and thus the description thereof is omitted here.

  In this specification, a bivalent fluorene group represents either of the following. In the following, Z and Z ′ each independently represent a hydrogen atom, an alkyl group, or an alkoxy group. Here, the alkyl group is not particularly limited, and is the same as the definition in the alkyl group and alkoxy group that may be introduced into the divalent aromatic group or heterocyclic group, and thus the description thereof is omitted here.

  Among these, considering the point that can impart higher electron resistance, D is preferably an alkyl group, an alkoxy group, a fluorene group substituted with an alkyl group, more preferably a fluorene group substituted with an alkyl group, A fluorene group substituted with a linear or branched alkyl group having 1 to 12 carbon atoms is particularly preferred.

  In the above formula (8), D ′ is at least one selected from the group consisting of halogen atoms, cyano groups, alkyl groups, aryl groups, amino groups, alkoxy groups, carbazole groups, fluorene groups, heterocyclic groups, and silyl groups. A carbazole group, a fluorene group, an aromatic group or a heterocyclic group, which is substituted or unsubstituted with a substituent. At this time, the carbazole group, fluorene group, aromatic group or heterocyclic group as the substituent “D ′” is substituted with one or two phenylene groups containing a bridging group represented by the following formula (9).

  Preferably, the carbazole group, fluorene group, aromatic group or heterocyclic group as the substituent “D ′” is substituted with two bridging group-containing phenylene groups represented by the above formula (9). Here, a halogen atom, an alkyl group, an aryl group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group and a silyl group are not particularly limited, and are introduced into the divalent aromatic group or heterocyclic group. Since the definitions are the same as those in the preferred substituents, the description thereof is omitted here. Similarly, the divalent aromatic group or heterocyclic group is not particularly limited, and is the same as defined for the substituent “A”, and thus the description thereof is omitted here. The substituent D ′ is not substituted with the same substituent. That is, for example, a fluorene group is not substituted with a fluorene group. The crosslinking group-containing phenylene group is not particularly limited, and examples similar to and preferred examples of the phenylene group having a crosslinking group of the structural unit (B) can be applied.

Specifically, the structural unit (B) and the structural unit (B ′) preferably have one of the following structures. The structural unit (B) is more preferably the following structure B2 or B6. In the structure below, R ″ represents an alkyl group (the definition of the alkyl group is the same as the definition in the structural unit (A)). When two R ″ are present, each R ″ ”May be the same or different. In the structure below, the main chain is“ —CH ₂ —CH═ ”, but the main chain is“ —CH ₂ —C (CH ₃ ) = ”is also preferable.

  As described above, the charge transport material of the present invention may be composed of only the structural unit (A), but is composed of the structural unit (A) and the structural units (B) and / or (B ′). Is preferred. Here, the structure of the charge transport material is not particularly limited when the charge transport material is composed of the structural unit (A) and the structural units (B) and / or (B ′) (is a copolymer), Any of a random copolymer, an alternating copolymer, a periodic copolymer, and a block copolymer may be sufficient. Further, the composition of the charge transport material in the case of a copolymer is not particularly limited, but the structural unit (A) and the structural units (B) and / or (B ′) (structural unit (A): structural unit (B) And / or (B ′) molar ratio; when it has both structural units (B) and (B ′), the structural unit (A): total molar ratio of structural units (B) and (B ′) is In the charge transport material, it is preferably contained in a ratio (molar ratio) of 99: 1 to 80:20, more preferably 95: 5 to 85:15. In the above, the total of the composition (contents) of the structural unit (A) and the structural units (B) and / or (B ′) is 100. With such a composition, sufficient resistance (insolubilization) to a solvent at the time of crosslinking can be obtained. For this reason, for example, even if another layer is formed on the layer containing the charge transport material, the layer containing the charge transport material is hardly or hardly dissolved in the solvent at the time of application.

  In addition, the weight average molecular weight (Mw) of the charge transport material according to the present invention is not particularly limited as long as the object and effects of the present invention can be obtained, but may be, for example, 5,000 to 500,000. Preferably, it is 10,000-200,000. With such a weight average molecular weight, the thickness of the coating solution for forming a layer (for example, a hole injection layer, a hole transport layer) using a charge transport material is appropriately adjusted to obtain a uniform film thickness. It is possible to form a layer. In addition, the measuring method in particular of a weight average molecular weight (Mw) is not restrict | limited, A well-known method is applied similarly or suitably modified. In this specification, the value measured in the following Example shall be employ | adopted for a weight average molecular weight (Mw).

  The charge transport material according to the present invention is excellent in charge resistance. For this reason, especially when the charge transport material according to the present invention is used as a hole transport material, it is possible to reduce the deterioration effect on the electrons and improve the device life. Therefore, the organic electroluminescent element using the charge transport material according to the present invention is excellent in durability. In addition, when the charge transport material according to the present invention is used for an organic electroluminescence device, high charge mobility is achieved.

  The terminal of the main chain of the charge transport material of the present invention is not particularly limited and is appropriately defined depending on the type of raw material used, but is usually a hydrogen atom.

The method for producing the charge transport material according to the present invention is not particularly limited, and a known polymerization method can be applied in the same manner or appropriately modified. Specifically, the charge transport material according to the present invention includes at least one monomer (A) represented by the following formula (5) and, if necessary, one or more kinds represented by the following formula (6). It can be produced by a (co) polymerization reaction using the monomer (B) or one or more monomers (B ′) represented by the formula: H ₂ —Y′-DD ′.

However, ^one of R ¹ , R ² and R ⁵ is represented by the following formula (7):

In the above formula (7), X represents a linking group constituting the main chain, and A represents a single bond, or a halogen atom, cyano group, alkyl group, aryl group, amino group, alkoxy group, carbazole group, fluorene group. Represents a divalent aromatic group or heterocyclic group substituted or unsubstituted with at least one substituent selected from the group consisting of a heterocyclic group and a silyl group,
And the remaining R ¹ , R ² and R ⁵ are a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, or a fluorene. Represents a monovalent aromatic group or heterocyclic group substituted or unsubstituted with at least one substituent selected from the group consisting of a group, a heterocyclic group and a silyl group;
R ³ , R ⁴ , R ^{6 to} R ⁸ , R ^{10 to} R ¹² , R ¹⁴ and R ¹⁵ are each independently a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group or an alkoxy group. And R ⁹ and R ¹³ each independently represents a hydrogen atom, an aryl group, a tertiary butyl group, a carbazole group, a fluorene group, or a heterocyclic group, and in this case, R ⁹ And at least one of R ¹³ represents an aryl group, a tertiary butyl group, a carbazole group, a fluorene group or a heterocyclic group,

However, Y represents the coupling group which comprises a principal chain, B is a single bond or a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group, and A divalent aromatic group or heterocyclic group substituted or unsubstituted with at least one substituent selected from the group consisting of silyl groups, or of formula (4): —N (R ¹⁸ ) —R ¹⁹ — Represents an amino group, and in the formula (4), R ¹⁸ is selected from the group consisting of a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group, and a silyl group. at least one of the is or an unsubstituted substituted with a substituent selected, an aromatic group or a heterocyclic group; R ¹⁹ is a halogen atom, a cyano group, an alkyl group, an aryl group, an amino A divalent aromatic group or a heterocyclic group substituted or unsubstituted with at least one substituent selected from the group consisting of an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group and a silyl group; K _a and K _{b each} represent a bridging group, a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group, or a silyl group. at least one of _a and K _b represents a bridging group;
In the above formula (5) to (7), the substituents ^{R 1 ~R 15, X, A} , Y, B, K a and _{K b} are each substituents in the above formula (1) to (3) Since it is the same as the definition, the description is omitted here. Further, in the formula: H ₂ —Y′-DD ′, the substituents Y ′, D, and D ′ are the same as the definitions of the substituents in the formula (8), and thus the description thereof is omitted here. .

  The monomer used for the polymerization of the charge transport material according to the present invention can be synthesized by appropriately combining known synthetic reactions, and the structure thereof can also be confirmed using known methods such as NMR and LC-MS. .

  The method for polymerizing the charge transport material according to the present invention is not particularly limited. For example, known polymerization methods such as radical polymerization, anionic polymerization, and cationic polymerization can be employed, and radical polymerization that is easy to produce is preferably used.

  Examples of the solvent used for polymerization include toluene, xylene, diethyl ether, chloroform, ethyl acetate, methylene chloride, tetrahydrofuran, acetone, acetonitrile, N, N-dimethylformamide, dimethyl sulfoxide, anisole, hexamethylphosphoric triamide, and the like. Toluene and tetrahydrofuran are preferred. These may be used alone or in combination of two or more. The monomer used for the polymerization of the charge transport material according to the present invention has high solubility in these organic solvents.

  The monomer concentration in the solvent (when using a plurality of monomers, the total amount thereof) is usually 5 to 90% by weight, preferably 10 to 80% by weight, based on the whole reaction solution.

  The polymerization temperature is preferably 40 to 100 ° C. from the viewpoint of controlling the molecular weight. The polymerization reaction is usually performed for 30 minutes to 24 hours.

  The solvent to which the monomer has been added may be subjected to a degassing treatment before the addition of the polymerization initiator. As the deaeration process, for example, freeze deaeration or bubbling with an inert gas such as nitrogen gas may be performed.

  As the polymerization initiator, conventionally known ones can be used, and examples thereof include benzophenone, benzoyl peroxide, acetyl peroxide, lauroyl peroxide, and azobisisobutyronitrile. The blending amount of the polymerization initiator is, for example, 0.0001 to 1 mol with respect to all monomers (1 mol) used for the production of the charge transport material.

<Material for organic electroluminescence device>
The charge transport material according to the present invention is suitably used as a material for an organic electroluminescence device. The charge transport material according to the present invention provides a material for an organic electroluminescence device having high durability and further high charge mobility. Accordingly, the present invention provides the use of the charge transport material of the present invention as a material for an organic electroluminescence device. Here, the description of the charge transport material is applied as appropriate.

  Since the material for an organic electroluminescent element according to the present invention is excellent in solubility in an organic solvent, it is particularly suitably used for producing an element by a wet process.

  Since the organic electroluminescent element material according to the present invention is excellent in charge mobility, it is suitable for forming any organic film such as a hole injection material, a hole transport material, and / or a light emitting layer material (host). Although it can be utilized, it is particularly suitably used as a hole injection material and / or a hole transport material from the viewpoint of hole transportability.

<Organic electroluminescent device>
The charge transport material according to the present invention is used for an organic electroluminescence device as a material for an organic electroluminescence device. In one aspect of the present invention, an organic electroluminescent device comprising a first electrode, a second electrode, and an organic film disposed between the first electrode and the second electrode, wherein the organic film An organic electroluminescent device is provided in which at least one layer of comprises the above-described charge transport material. From the viewpoint of hole transportability, according to a preferred embodiment of the present invention, the organic film containing the charge transport material according to the present invention is a hole injection layer or a hole transport layer.

  FIG. 1 is a cross-sectional view of an organic electroluminescent device 100 according to an embodiment of the present invention. FIG. 1 shows the first electrode 120 / the hole injection layer 130 / the hole transport layer 140 / the light emitting layer 150 / the electron transport layer 160 / the electron injection layer 170 / the second electrode 180. It is not limited to a simple structure. The organic electroluminescent device has a first electrode / single film having a hole injection function and a hole transport function / a light emitting layer / electron transport layer / second electrode or a first electrode / a hole injection function and a hole transport function. It may have a structure such as a single film / light emitting layer / electron transport layer / electron injection layer / second electrode.

  The organic electroluminescent element according to the present invention may be either a front light emitting type or a back light emitting type.

  With reference to FIG. 1, an organic light emitting device according to an embodiment of the present invention will be described. FIG. 1 is a schematic diagram illustrating an example of the structure of an organic light emitting device according to an embodiment of the present invention.

  As shown in FIG. 1, the organic light emitting device 100 according to an embodiment of the present invention includes a substrate 110, a first electrode 120 disposed on the substrate 110, and a hole injection disposed on the first electrode 120. A layer 130, a hole transport layer 140 disposed on the hole injection layer 130, a light emitting layer 150 disposed on the hole transport layer 140, an electron transport layer 160 disposed on the light emitting layer 150, The electron injection layer 170 arrange | positioned on the electron carrying layer 160 and the 2nd electrode 180 arrange | positioned on the electron injection layer 170 are provided.

  As the substrate 110, a substrate used in a general organic light emitting device can be used. For example, the substrate 110 may be a glass substrate, a semiconductor substrate, or a transparent plastic substrate.

The first electrode 120 is, for example, an anode, and is formed on the substrate 110 using an evaporation method, a sputtering method, or the like. Specifically, the first electrode 120 is formed as a transmission electrode using a metal, an alloy, a conductive compound, or the like having a high work function. The first electrode 120 is, for example, transparent and may be formed of indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO ₂ ), zinc oxide (ZnO) or the like having excellent conductivity. . The first electrode 120 may be formed as a reflective electrode using magnesium (Mg), aluminum (Al), or the like.

  The hole injection layer 130 is a layer having a function of facilitating the injection of holes from the first electrode 120, and uses a vacuum deposition method, a spin coating method, an ink jet method, or the like. Formed on the first electrode 120. Since the charge transport material according to the present invention is excellent in solubility in an organic solvent, it is particularly preferably used for forming a hole injection layer by a wet process such as a spin coating method, a casting method, a printing method, or an LB method. In the case of the above method, the hole injection layer forming material is dissolved in a solvent, but the solvent that can be used is not particularly limited, but the same solvent as the solvent used for the polymerization can be used. Further, the hole injection layer 130 may be specifically formed with a thickness (dry film thickness) of about 10 nm to about 500 nm, more specifically about 10 nm to about 100 nm. The hole injection layer 130 can be formed using a known material in addition to the charge transport material according to the present invention. For example, N, N′-diphenyl-N, N′-bis- [4- (Phenyl-m-tolyl-amino) -phenyl] -biphenyl-4,4′-diamine (DNTPD), phthalocyanine compounds such as copper phthalocyanine, 4,4 ′, 4 ″ -tris (3-methylphenylphenylamino) tri Phenylamine (m-MTDATA), N, N′-di (1-naphthyl) -N, N′-diphenylbenzidine (NPB), 4,4 ′, 4 ″ -tris {N, N diphenylamino} triphenylamine (TDATA), 4,4 ′, 4 ″ -tris (N, N-2-naphthylphenylamino) triphenylamine (2-TNATA), polyaniline / dodecylbenzenes Phosphonic acid (PANI / DBSA), poly (3,4-ethylenedioxythiophene) / poly (4-styrenesulfonate) (PEDOT / PSS), polyaniline / camphorsulfonic acid (PANI / CSA), or polyaniline / poly (4 -Styrene sulfonate) (PANI / PSS) or the like.

  When the charge transport material according to the present invention is used in a wet process, the content of the charge transport material according to the present invention with respect to the entire coating solution is, for example, 0.1 to 20% by weight, preferably 0.1 to 10% by weight. %.

  When the charge transport material according to the present invention is used for the hole injection layer, the content of the whole layer is 50 to 100% by weight (dry weight), preferably 80 to 100% by weight (dry weight).

  The hole transport layer 140 is a layer containing a hole transport material having a function of transporting holes, and is formed on the hole injection layer 130 using a vacuum deposition method, a spin coating method, an ink jet method, or the like. Since the charge transport material according to the present invention is excellent in solubility in an organic solvent, it is particularly suitably used for forming a hole transport layer by a wet process such as a spin coating method, a casting method, a printing method, or an LB method. In the case of the above method, the hole transport layer forming material is dissolved in a solvent, but the solvent that can be used is not particularly limited, but the same solvent as the solvent used for the polymerization can be used. Further, the hole transport layer 140 may be specifically formed with a thickness (dry film thickness) of about 5 nm to about 500 nm, more specifically about 10 nm to about 100 nm. The hole transport layer 140 may be formed using a known hole transport material in addition to the charge transport material according to the present invention. For example, N-phenylcarbazole (PhCz), polyvinylcarbazole (PVK) Carbazole derivatives such as N, N′-bis (3-methylphenyl) -N, N′-diphenyl- [1,1-biphenyl] -4,4′-diamine (TPD), 4,4 ′, 4 ″ -Tris (N-carbazolyl) triphenylamine (TCTA), N, N'-di (1-naphthyl) -N, N'-diphenylbenzidine (NPB) can be used.

  When the charge transport material according to the present invention is used for the hole transport layer, the content of the whole layer is 50 to 100% by weight (dry weight), preferably 80 to 100% by weight (dry weight).

  The light emitting layer 150 is a layer that emits light by phosphorescence, fluorescence, or the like, and is formed on the hole transport layer 140 using a vacuum deposition method, a spin coating method, an ink jet method, or the like. The light emitting layer 150 includes a host material and a dopant material, and may include a charge transport material according to the present invention. Since the charge transport material according to the present invention is excellent in solubility in an organic solvent, it is particularly suitably used for forming a light emitting layer by a wet process such as a spin coating method, a casting method, a printing method, or an LB method. In the case of the above method, the light emitting layer forming material is dissolved in a solvent, but the solvent that can be used is not particularly limited, but the same solvent as the solvent used for the polymerization can be used. In addition, the light emitting layer 150 may be specifically formed with a thickness (dry film thickness) of about 10 nm to about 100 nm, more specifically about 20 nm to about 60 nm.

  The light emitting layer 150 may contain other host materials, such as 1,3-bis (carbazole) benzene (mCP), tris (8-quinolinolato) aluminum (Alq3), 4,4′-bis (carbazole). -9-yl) biphenyl (CBP), poly (n-vinylcarbazole) (PVK), 9,10-di (naphthalen-2-yl) anthracene (ADN), 4,4 ', 4 "-tris (N- Carbazolyl) triphenylamine (TCTA), 1,3,5-tris (N-phenylbenzimidazol-2-yl) benzene (TPBI), 3-tert-butyl-9,10-di (naphth-2-yl) Anthracene (TBADN), distyrylarylene (DSA), 4,4′-bis (9-carbazole) -2,2′-dimethyl-biphenyl (d CBP) may also include.

  The light emitting layer 150 may be formed as a light emitting layer that emits light of a specific color. For example, the light emitting layer 150 may be formed as a red light emitting layer, a green light emitting layer, and a blue light emitting layer.

  When the light emitting layer 150 is a blue light emitting layer, a known material can be used as the blue dopant. For example, perylene and its derivatives, bis [2- (4,6-difluorophenyl) pyridinate] picoline, for example. An iridium (Ir) complex such as iridium (III) (FIrpic) can be used.

When the light emitting layer 150 is a red light emitting layer, a known material can be used as the red dopant. For example, rubrene and its derivatives, 4-dicyanomethylene-2- (p-dimethylaminostyryl) ) -6-methyl-4H-pyran (DCM) and its derivatives, iridium complexes such as bis (1-phenylisoquinoline) (acetylacetonate) iridium (III) (Ir (piq) ₂ (acac)), osmium (Os ) Complexes, platinum complexes and the like can be used.

When the light emitting layer 150 is a green light emitting layer, a known material can be used as the green dopant. For example, coumarin and its derivatives, tris (2-phenylpyridine) iridium (III) (Ir (Ppy) ₃ ), tris (2- (3-p-xyyl) phenyl) pyridine iridium (III) (TEG), iridium complexes such as tris (acetylacetonato) iridium (III) (Ir (acac) ₃ ), etc. Can be used.

  When the charge transport material according to the present invention is used in the light emitting layer, the content of the light emitting layer with respect to the entire host is 10 to 100% by weight (dry weight), preferably 50 to 100% by weight (dry weight). .

  The electron transport layer 160 is a layer containing an electron transport material having a function of transporting electrons, and is formed on the light emitting layer 150 by using a vacuum deposition method, a spin coating method, an ink jet method, or the like. In addition, the electron transport layer 160 may be specifically formed with a thickness of about 10 nm to about 100 nm, more specifically about 15 nm to about 70 nm. Note that the electron transport layer 160 includes, for example, a Li complex such as lithium quinolate (Liq), a quinoline derivative such as tris (8-quinolinolato) aluminum (Alq3), or a 1,2,4-triazole derivative (TAZ). , Bis (2-methyl-8-quinolinolato)-(p-phenylphenolate) -aluminum (BAlq), beryllium bis (benzoquinoline-10-olate) (BeBq2), and the like. These electron transport layer forming materials may be commercially available products or synthetic products. As an example of a commercial item, KLET-01, KLET-02, KLET-03, KLET-10, KLET-M1 (above, Chemipro Kasei Co., Ltd. product) etc. are mentioned. These electron transport layer forming materials may be used singly or in combination of two or more.

The electron injection layer 170 is a layer having a function of facilitating injection of electrons from the second electrode 180, and is formed on the electron transport layer 160 using a vacuum deposition method or the like. Further, the electron injection layer 170 may be specifically formed with a thickness of about 0.1 nm to about 10 nm, more specifically about 0.3 nm to about 9 nm. Note that the electron injection layer 170 can be formed using a known material. For example, lithium fluoride (LiF), sodium chloride (NaCl), cesium fluoride (CsF), and lithium oxide (Li ₂ O) can be used. , Barium oxide (BaO) or the like can be used.

  The second electrode 180 is, for example, a cathode, and is formed on the electron injection layer 170 by vapor deposition or sputtering. Specifically, the second electrode 180 is formed as a reflective electrode using a metal, an alloy, a conductive compound, or the like having a low work function. The second electrode 180 is made of, for example, lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver ( (Mg—Ag) or the like. The second electrode 180 may be formed as a transmissive electrode using indium tin oxide (ITO), indium zinc oxide (IZO), or the like.

  The example of the structure of the organic light emitting device 100 according to one embodiment of the present invention has been described above, but the structure of the organic light emitting device 100 according to one embodiment of the present invention is not limited to the above example. The organic light emitting device 100 according to an embodiment of the present invention may be formed using other known structures of various organic light emitting devices. For example, the organic light emitting device 100 may not include one or more of the hole injection layer 130, the hole transport layer 140, the electron transport layer 160, and the electron injection layer 170. In addition, each layer of the organic light emitting device 100 may be formed of a single layer or a plurality of layers.

  Further, the organic light emitting device 100 includes a hole blocking layer between the hole transport layer 140 and the light emitting layer 150 in order to prevent the phenomenon of triplet excitons or holes diffusing into the electron transport layer 160. May be. Note that the hole blocking layer can be formed using, for example, an oxadiazole derivative, a triazole derivative, or a phenanthroline derivative.

  The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

  In the following synthesis examples, various analyzes were performed by the methods shown below.

(Measurement of weight average molecular weight)
The weight average molecular weight (Mw) of the (co) polymer is measured by GPC (gel permeation chromatography) using polystyrene as a standard substance under the following conditions.

Synthesis example 1
A monomer (A9) having the following structure was synthesized by the following reaction.

  To a four-necked flask substituted with argon, 9- (4-biphenylyl) 3-bromocarbazole (10.0 g), aniline (2.46 g), tris (dibenzylideneacetone) dipalladium (0.690 g), 1, 1′-bis (diphenylphosphino) ferrocene (1.66 g), sodium tert-butoxide (4.82 g), and toluene (100 mL) were added and heated at 110 ° C. for 3 hours. The mixture was allowed to cool to room temperature (25 ° C.), and the insoluble material was filtered off through celite. The solvent was removed from the filtrate under reduced pressure, and the residue was purified by column chromatography to give 9- (4-biphenylyl) -N-phenyl-9H-carbazol-3-amine (5.84 g).

  In a four-necked flask replaced with argon, 9- (4-biphenylyl) -N-phenyl-9H-carbazol-3-amine (5.80 g), 4-bromo-4′-vinylbiphenyl (3.61 g), Tris (dibenzylideneacetone) dipalladium (0.648 g), tri-tert-butylphosnium tetrafluoroborate (0.430 g), sodium tert-butoxide (2.96 g), xylene (80 mL) were added, and 140 ° C. For 3 hours. The mixture was allowed to cool to room temperature (25 ° C.), and the insoluble material was filtered off through celite. The solvent was distilled off under reduced pressure from the filtrate, and column chromatography and recrystallization were performed to obtain a monomer (A9) (0.855 g).

Synthesis example 2
A monomer (B7) having the following structure was synthesized by the following method.

  To a four-necked flask purged with argon, 9- (bicyclo [4.2.0] octa-1 (6), 2,4-trien-3-yl) -9- (bicyclo [4.2.0] Octa-1,3,5-trien-3-yl) -2-bromo-9H-fluorene (1.00 g), 2- (9,9-dioctyl-7vinyl-9H-fluoren-2-yl) -4 , 4,5,5-tetramethyl-1,3,2-dioxaborolane (1.21 g), tri-tert-butylphosnium tetrafluoroborate (0.129 g), tris (dibenzylideneacetone) dipalladium (0 .10 g), potassium carbonate (0.63 g), 1,2-dimethoxyethane (DME) (9 mL) and water (4 mL) were added and heated at 85 ° C. for 5 hours. The mixture was allowed to cool to room temperature (25 ° C.), and the insoluble material was filtered off through celite. The solvent was distilled off from the filtrate under reduced pressure, and column chromatography and recrystallization were performed to obtain monomer B2 (1.20 g).

Synthesis example 3
A comparative monomer (C1) having the following structure was synthesized by the following method.

  To a four-necked flask substituted with argon, N-4-bromophenyl-N, N-bisphenylamine (5.01 g), 4-methoxyaniline (2.16 g), tris (dibenzylideneacetone) dipalladium (0 .572 g), 1,1′-bis (diphenylphosphino) ferrocene (1.384 g), sodium tert-butoxide (2.97 g) and toluene (78 mL) were added and heated at 110 ° C. for 6 hours. The mixture was allowed to cool to room temperature (25 ° C.), and the insoluble material was filtered off through celite. The solvent was removed from the filtrate under reduced pressure, and the residue was purified by column chromatography to obtain N- (4-methoxyphenyl) -N ′, N′-diphenyl-benzene 1,4-diamine (4.57 g).

  In a four-necked flask substituted with argon, N- (4-methoxyphenyl) -N ′, N′-diphenyl-benzene-1-diamine (1.11 g), 4-bromostyrene (0.663 g), tris (Dibenzylideneacetone) dipalladium (0.138 g), tetrabutylphosphine ferrocene (0.176 g), sodium tert-butoxide (0.588 g) and toluene (15 mL) were added and heated at 110 ° C. for 6 hours. The mixture was allowed to cool to room temperature (25 ° C.), and the insoluble material was filtered off through celite. The solvent was distilled off from the filtrate under reduced pressure, and the residue was purified by column chromatography to obtain monomer C1 (0.604 g).

Synthesis example 4
A comparative monomer (B2) having the following structure was synthesized by the following method.

  To a four-necked flask substituted with argon, aniline (2.79 g), 3-bromobicyclo [4,2,0] octa-1 (6), 2,4-triene (11.5 g), tris (dibenzylidene) Acetone) dipalladium (0.549 g), tri-tert-butylphosnium tetrafluoroborate (0.696 g), sodium tert-butoxide (8.55 g), toluene (150 mL) were added and heated at 110 ° C. for 2 hours. did. The mixture was allowed to cool to room temperature (25 ° C.), and the insoluble material was filtered off through celite. The solvent was distilled off from the filtrate under reduced pressure, the residue was purified by column chromatography, and N- (bicyclo [4.2.0] octa-1,3,5-trien-3-yl) -N-phenylbicyclo [4. 2.0] Octa-1 (6), 2,4-trien-3-amine (9.16 g) was obtained.

  In a four-necked flask substituted with argon, N- (bicyclo [4.2.0] octa-1,3,5-trien-3-yl) -N-phenylbicyclo [4.2.0] octa-1 was added. (6) 2,2,4-Trien-3-amine (6.12 g) and dimethylformamide (DMF) (41.2 mL) were added and cooled with ice water. N-bromosuccinimide (3.67 g) dissolved in DMF (20.6 mL) was added dropwise and stirred for 2 hours. Toluene (150 mL) was added, washed with water, and dried over magnesium sulfate. The solvent was distilled off under reduced pressure, the residue was purified by column chromatography, and N- (bicyclo [4.2.0] octa-1,3,5-trien-3-yl) -N- (4-bromophenyl) bicyclo [ 4.2.0] Octa-1 (6), 2,4-trien-3-amine (7.08 g) was obtained.

  In a four-necked flask substituted with argon, N- (bicyclo [4.2.0] octa-1,3,5-trien-3-yl) -N- (4-bromophenyl) bicyclo [4.2. 0] octa-1 (6), 2,4-trien-3-amine (6.45 g), 4-vinylphenylboronic acid (3.03 g), tetrakis (triphenylformine) palladium (0.40 g) , Potassium carbonate (7.73 g), 1,2-dimethoxyethane (DME) (68 mL) and water (17 mL) were added, and the mixture was heated at 85 ° C. for 5 hours. The mixture was allowed to cool to room temperature (25 ° C.), and the insoluble material was filtered off through celite. The solvent was distilled off under reduced pressure from the filtrate, and column chromatography and recrystallization were performed to obtain a monomer (B2) (3.67 g).

Example 1
A hole transport material (1) having the following structure was synthesized using the monomer (A9) synthesized in Synthesis Example 1 and the monomer (B7) synthesized in Synthesis Example 2 by the following method.

  Specifically, in the Schlenk tube, the monomer (A9) synthesized in Synthesis Example 1 (795 mg), the monomer synthesized in Synthesis Example 2 (B7) (118 mg), azobisisobutyronitrile (4.5 mg) ), Toluene (9 ml) was added, and after bubbling and freeze degassing, the mixture was heated and stirred at 60 ° C. for 6 hours. After cooling to room temperature, the good solvent is THF, the poor solvent is an excess amount of methanol, reprecipitation is performed 5 times, the precipitate is vacuum-dried, and a copolymer of monomer (A9) and monomer (B7) ( Monomer (A9) -derived structural unit (A): Monomer (B7) -derived structural unit (B) = 90: 10 (molar ratio)) (500 mg) was obtained. The copolymer thus obtained is referred to as a comparative hole transport material (1).

  The weight average molecular weight (Mw) of the hole transport material (1) thus obtained was measured and found to be 29,000.

Comparative Example 1
By the following method, the monomer (C1) synthesized in Synthesis Example 3 and the monomer (B2) synthesized in Synthesis Example 4 were synthesized as a comparative hole transport material (2) having the following structure.

  Specifically, in the Schlenk tube, the monomer (C1) synthesized in Synthesis Example 3 (160 mg), the monomer (B2) synthesized in Synthesis Example 4 (1.69 g), azobisisobutyronitrile (8 0.0 mg) and toluene (8 ml) were added, and after bubbling and freeze degassing, the mixture was heated and stirred at 60 ° C. for 6 hours. Allow to cool to room temperature, reprecipitate 5 times with THF as the good solvent and excess methanol as the poor solvent, and vacuum dry the precipitate to obtain a copolymer of monomer (C1) and monomer (B2) (Structural unit (C) derived from monomer (C1): Structural unit (D) derived from monomer (B2) = 90: 10 (molar ratio)) (1.80 g) was obtained. The copolymer thus obtained is referred to as a comparative hole transport material (2).

  The weight average molecular weight (Mw) of the hole transport material (2) thus obtained was measured and found to be 25,000.

Example 2
A PEDOT-PSS (manufactured by Sigma-Aldrich) was applied by spin coating so that the thickness (dry film thickness) was 30 nm on a glass substrate with ITO on which stripe-shaped ITO was arranged. Film thickness) A 30 nm hole injection layer was formed.

  Next, the hole transport material (1) synthesized in Example 1 was dissolved in xylene (solvent) at a concentration of 1 wt% to prepare a hole transport layer forming coating solution (1). On the hole injection layer formed as described above, this hole transport layer forming coating solution (1) is applied by spin coating so that the thickness (dry film thickness) is 30 nm, and then at 230 ° C. for 1 hour. A hole transport layer having a thickness (dry film thickness) of 30 nm was formed by heating.

  Further, on the hole transport layer formed as described above, 3,6-bis (triphenylsilyl) carbazole (hereinafter referred to as mCP) and 4,4′-bis (carbazol-9-yl) are used as two types of host materials. Biphenyl (hereinafter referred to as CBP) is in a ratio of mCP: CBP = 7: 3 (weight ratio), and tris (2- (3-p-xyyl) phenyl) pyridine iridium (III) (TEG) is 10% as a dopant material. In order to be doped, it was co-evaporated with a vacuum deposition apparatus, and a light emitting layer having a thickness of 30 nm was formed on the hole injection layer.

  Lithium quinolate (hereinafter referred to as Liq) and KLET-03 (manufactured by Chemipro Kasei Co., Ltd.) are co-evaporated on the light-emitting layer formed above with a vacuum vapor deposition device to emit an electron transport layer having a thickness of 50 nm. Formed on the layer.

  On the electron transport layer formed above, lithium fluoride (hereinafter referred to as LiF) was vapor-deposited with a vacuum deposition apparatus, and an electron injection layer having a thickness of 1 nm was formed on the electron transport layer.

  On the electron injection layer formed above, aluminum (hereinafter referred to as Al) was vapor-deposited with a vacuum deposition apparatus, and an electrode (cathode) having a thickness of 100 nm was formed on the electron injection layer. This obtained the organic electroluminescent element (1).

Comparative Example 2
In Example 1, the hole transport layer is formed using the comparative hole transport material (2) synthesized in Comparative Example 1 instead of the hole transport material (1). Similarly, a comparative organic electroluminescent element (2) was obtained.

  Durability was evaluated by the following method for the organic electroluminescent device (1) obtained in Example 1 and the comparative organic electroluminescent device (2) obtained in Comparative Example 1. The results are shown in Table 1 below. In Table 1 below, the device life of Example 1 is expressed as an extension when the device life of the comparative organic electroluminescent device (2) of Comparative Example 1 is taken as 100.

[Evaluation of durability]
The device lifetime is measured according to the following method.

That is, when a voltage is applied to each element using a DC constant voltage power supply (for example, source meter KEYENCE), current starts to flow at a certain voltage, and the element starts to emit light. Luminescence is captured by a luminance measuring device (for example, SR-3: manufactured by Topcom), the current is gradually increased, and when the luminance reaches 1000 cd / m ² , the current is constant and left. The time until the luminance value measured by the luminance measuring apparatus fluctuates (slowly decreases) and reaches 80% of the initial luminance value is defined as “element life (time)”.

  From the results of Table 1 above, it can be seen that the organic electroluminescent device (1) of Example 1 can significantly improve the device lifetime as compared with the comparative organic electroluminescent device (2) of Comparative Example 1. This is presumed that the device lifetime could be improved because the hole transport material (1) used in the hole transport layer has higher charge resistance than the comparative hole transport material (2).

100 organic electroluminescent device,
110 substrates,
120 first electrode;
130 hole injection layer,
140 hole transport layer,
150 light emitting layer,
160 electron transport layer,
170 electron injection layer,
180 Second electrode.

Claims (7)

Charge transport material having a structural unit (A) represented by the following formula (1) and a structural unit (B) represented by the following formula (2) or a structural unit (B ′) represented by the following formula (8) :
However, ^one of R ¹ , R ² and R ⁵ is a substituent (a) represented by the following formula (3):
In the above formula (3), X represents a linking group constituting the main chain, and A represents a single bond, or a halogen atom, cyano group, alkyl group, aryl group, amino group, alkoxy group, carbazole group, fluorene group. Represents a divalent aromatic group or heterocyclic group substituted or unsubstituted with at least one substituent selected from the group consisting of a heterocyclic group and a silyl group,
And the remaining R ¹ , R ² and R ⁵ are a hydrogen atom or a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group and a silyl group. Represents a monovalent aromatic group or heterocyclic group substituted or unsubstituted with at least one substituent selected from;
R ³ , R ⁴ , R ^{6 to} R ⁸ , R ^{10 to} R ¹² , R ¹⁴ and R ¹⁵ are each independently a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group or an alkoxy group. And R ⁹ and R ¹³ each independently represents a hydrogen atom, an aryl group, a tertiary butyl group, a carbazole group, a fluorene group, a heterocyclic group, or a formula (9): —N (R ²⁰ ) (R ²¹ ) — represents an amino group, and at least one of R ⁹ and R ¹³ is an aryl group, a tertiary butyl group, a carbazole group, a fluorene group, a heterocyclic group, or a formula (9) ^{: -N (R 20) (R} 21) - an amino group of this case, in the above formula ^{(9), R 20} is an aryl group, and ^{R 21} is an arylene group, this , ^{R 21} to form a ring with ^{R 8} or ^{R 10,}
However, Y represents the coupling group which comprises a principal chain, B is a single bond or a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group, and A divalent aromatic group or heterocyclic group substituted or unsubstituted with at least one substituent selected from the group consisting of silyl groups, or of formula (4): —N (R ¹⁸ ) —R ¹⁹ — Represents an amino group, and in the formula (4), R ¹⁸ is selected from the group consisting of a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group, and a silyl group. at least one of the is or an unsubstituted substituted with a substituent selected, an aromatic group or a heterocyclic group; R ¹⁹ is a halogen atom, a cyano group, an alkyl group, an aryl group, an amino , An alkoxy group, a carbazole group, a fluorene group, at least one selected from the group consisting of heterocyclic group and a silyl group are the or unsubstituted substituted with a substituent, is a divalent aromatic group or a heterocyclic group; and
K _a and K _{b each} represent a bridging group, a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group, or a silyl group. at least one of _a and K _b represents a bridging group;
However, Y 'represents the coupling group which comprises a principal chain, D is a single bond or a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group And a divalent carbazole group, a fluorene group, an aromatic group or a heterocyclic group, which is substituted or unsubstituted with at least one substituent selected from the group consisting of silyl group, and D ′ is a halogen atom, cyano group Group, alkyl group, aryl group, amino group, alkoxy group, carbazole group, fluorene group, heterocyclic group, and substituted or unsubstituted carbazole group, fluorene with at least one substituent selected from the group consisting of silyl group Group, aromatic group or heterocyclic group, and the carbazole group, fluorene group, aromatic group or heterocyclic group is one or two of the following (9):
K _a represents a bridging group,
It is substituted with a crosslinking group-containing phenylene group represented by The structural unit (B) is represented by the following formula:
In the above formula, B is a single bond or at least one selected from the group consisting of a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group, and a silyl group. A substituted or unsubstituted divalent aromatic group or heterocyclic group, or an amino group of the formula (4): —N (R ¹⁸ ) —R ¹⁹ —, in the above formula (4) R ¹⁸ is substituted with at least one substituent selected from the group consisting of a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group, and a silyl group. or unsubstituted, an aromatic group or a heterocyclic group; R ¹⁹ is a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group Fluorene groups, of the the or unsubstituted substituted with at least one substituent selected from the group consisting of heterocyclic group and a silyl group, a divalent aromatic group or a heterocyclic group, and K _a is the bridging group, Represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group or a silyl group,
The charge transport material according to claim 1 , wherein the structural unit (B ') is represented by the following formula:
In the above formula, D is a single bond or at least one selected from the group consisting of a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group, and a silyl group. A divalent carbazole group, a fluorene group, an aromatic group or a heterocyclic group substituted or unsubstituted with a substituent is represented, and Ka represents _a bridging group. The charge transport material according to claim 1 or 2 , wherein the structural unit (A) and the structural units (B) and / or (B ') are included in a ratio (molar ratio) of 99: 1 to 80:20. In Formula (1), R ¹ is at least A selected from the group consisting of a halogen atom, a cyano group, an alkyl group, an aryl group, an amino group, an alkoxy group, a carbazole group, a fluorene group, a heterocyclic group, and a silyl group. A substituent (a) of the formula (3) which is a substituted or unsubstituted divalent aromatic group or heterocyclic group, and in the formula (2), B is a halogen atom, A substituted or unsubstituted divalent divalent substituted with at least one substituent selected from the group consisting of cyano group, alkyl group, aryl group, amino group, alkoxy group, carbazole group, fluorene group, heterocyclic group and silyl group An aromatic group or a heterocyclic group, or, in the above formula (8), D is a halogen atom, cyano group, alkyl group, aryl group, amino group, alkoxy group, carbazole group, fluorene Groups, of the the or unsubstituted substituted with at least one substituent selected from the group consisting of heterocyclic group and a silyl group, a divalent carbazole group, a fluorene group, an aromatic group or a heterocyclic group, claim 1 The charge transport material according to any one of to 3 . Weight average molecular weight of 5,000 to 500,000, a charge transport material according to any one of claims 1-4. A first electrode;
A second electrode;
An organic film disposed between the first electrode and the second electrode;
An organic electroluminescent device comprising:
At least 1 layer of the said organic film is an organic electroluminescent element containing the charge transport material of any one of Claims 1-5 . The organic electroluminescent element according to claim 6 , wherein the organic film containing the charge transport material is a hole injection layer or a hole transport layer.