JP7574805B2 - Polymer, composition for organic electroluminescent element, composition for forming hole transport layer or hole injection layer, organic electroluminescent element, organic EL display device, and organic EL lighting - Google Patents

Description

The present invention relates to a polymer. More specifically, the present invention relates to a polymer useful as a charge transport material for organic electroluminescent elements. The present invention also relates to a composition for organic electroluminescent elements containing the polymer, a composition for forming a hole transport layer or a hole injection layer, an organic electroluminescent element including a layer formed using the composition and a method for producing the same, and an organic EL display device and organic EL lighting having the organic electroluminescent element.

Methods for forming an organic layer in an organic electroluminescent device include a vacuum deposition method and a wet film formation method.
The vacuum deposition method has the advantages that since lamination is easy, charge injection from the anode and/or cathode can be improved and excitons can be easily confined in the light-emitting layer.
On the other hand, the wet film formation method has the advantages that it does not require a vacuum process, it is easy to achieve a large area, and by using a coating liquid in which a plurality of materials with various functions are mixed, a layer containing a plurality of materials with various functions can be easily formed.
However, since it is difficult to form layers using wet film formation methods, the driving stability is inferior to that of elements formed by vacuum deposition methods, and, with the exception of a few, these methods have not yet reached a level of practical use.

In order to perform lamination by a wet film-forming method, charge-transporting polymers having crosslinkable groups are desired, and their development is underway. For example, Patent Documents 1 to 3 disclose organic electroluminescent elements that contain polymers having specific repeating units and are laminated by a wet film-forming method.

Patent documents 4 and 5 disclose hole injection and transport materials having a structure in which a fluorene ring or a carbazole ring and an unsubstituted phenylene ring are bonded to the main chain of a polymer.

Patent Document 6 describes that it is preferable for a polymer having a repeating unit of a quaternary carbon C4 of ^sp3 hybridization and a phenylene to contain a non-conjugated unit in the main chain. Patent Document 6 discloses a side chain structure in which a triazine ring is connected to the main chain via an alkylene group.

Patent Document 7 discloses a compound in which a polymer has a repeating unit containing a silicon atom and a carbazole ring in the main chain, and a triazine group having a substituent is linked to the 9-position of the carbazole ring via an aryl group.

Patent document 8 discloses a polymer having a pyridine structure in the side chain of a polymer having an arylamine structure.

International Publication No. 2009/123269 JP 2013-045986 A International Publication No. 2013/191088 JP 2016-084370 A JP 2017-002287 A Special table number 2014-506003 Chinese Patent Publication No. 108383980 International Publication No. 2003/057762

Patent Document 6 discloses a structure in which a triazine ring in a side chain is connected to a main chain via an alkylene group. However, this polymer has a structure in which intermolecular charge transfer is prevented by connecting the main chain and the triazine ring in the side chain via an alkylene group.

The compound disclosed in Patent Document 7 contains a silicon atom, which causes the polymer main chain to become non-conjugated, resulting in poor charge transport properties.

Patent document 8 discloses an arylamine polymer having a fluorenyl group in the main chain, which has excellent charge transport properties. However, this polymer is prone to excimer formation due to direct bonding between the pyridine ring and the N atom in the main chain, and the durability of the device is insufficient.

The present invention aims to provide a polymer having high hole injection and transport capability and high durability, and a composition for organic electroluminescent elements containing the polymer. Another objective of the present invention is to provide an organic electroluminescent element having high brightness and a long operating life.

The present inventors have found that the above problems can be solved by using a polymer having a specific structure, which includes a specific 6-membered heteroaromatic ring having a nitrogen atom, in a side chain.
The gist of the present invention is as follows [1] to [16].

[1] A polymer containing a repeating unit represented by the following formula (1):

In formula (1), G represents an aromatic hydrocarbon group which may have a substituent, or a nitrogen atom.
^Ar2 represents a divalent aromatic hydrocarbon group which may have a substituent, a divalent aromatic heterocyclic group which may have a substituent, or a divalent group in which two or more groups selected from a divalent aromatic hydrocarbon group which may have a substituent and a divalent aromatic heterocyclic group which may have a substituent are linked together directly or via a linking group.
A is a structure containing a specific 6-membered heteroaromatic ring having a nitrogen atom and is represented by formula (1)-2.
In formula (1)-2, Ar ¹ represents a divalent aromatic hydrocarbon group which may have a substituent.
^Ar3 and ^Ar4 each independently represent an aromatic hydrocarbon group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or a monovalent group in which two or more groups selected from an aromatic hydrocarbon group which may have a substituent and an aromatic heterocyclic group which may have a substituent are linked together directly or via a linking group.
X and Y each independently represent a C atom or a N atom. When X or Y is a C atom, it may have a substituent.
"-*" is the site that bonds to G in formula (1).

[2] The polymer described in [1], wherein G is an N atom.

[3] A polymer described in [2], in which the repeating unit represented by formula (1) is a repeating unit represented by any of the following formulas (2)-1 to (2)-3.

In the formulas (2)-1 to (2)-3, A is the same as A in the above formula (1).
Q represents -C(R ⁵ )(R ⁶ )-, -N(R ⁷ )- or -C(R ¹¹ )(R ¹² )-C(R ¹³ )(R ¹⁴ )-.
R ¹ to R ⁴ each independently represent an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or an aralkyl group which may have a substituent.
R ⁵ to R ⁷ and R ¹¹ to R ¹⁴ each independently represent an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aralkyl group which may have a substituent, or an aromatic hydrocarbon group which may have a substituent.
a and b each independently represents an integer of 0 to 4.
c1 to c5 each independently represents an integer of 0 to 3.
However, at least one of c3 and c5 is 1 or more.
d1 to d4 each independently represents an integer of 1 to 4.
When a plurality of R ¹ , R ² , R ³ and R ⁴ are present in the repeating unit, R ¹ , R ² , R ³ and R ⁴ may be the same or different.

[4] A polymer described in any of [1] to [3], further containing a repeating unit represented by any of the following (3)-1 to (3)-3.

In formulas (3)-1 to (3)-3, ^Ar7 represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent, excluding the group containing a specific 6-membered heteroaromatic ring having a nitrogen atom, which is the structure A represented by formula (1)-2.
Q represents -C(R ⁵ )(R ⁶ )-, -N(R ⁷ )- or -C(R ¹¹ )(R ¹² )-C(R ¹³ )(R ¹⁴ )-.
R ¹ to R ⁴ each independently represent an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or an aralkyl group which may have a substituent.
R ⁵ to R ⁷ and R ¹¹ to R ¹⁴ each independently represent an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aralkyl group which may have a substituent, or an aromatic hydrocarbon group which may have a substituent.
a and b each independently represents an integer of 0 to 4.
c1 to c5 each independently represents an integer of 0 to 3.
However, at least one of c3 and c5 is an integer of 1 or more.
d1 to d4 each independently represents an integer of 1 to 4.
When a plurality of R ¹ , R ² , R ³ and R ⁴ are present in the repeating unit, R ¹ , R ² , R ³ and R ⁴ may be the same or different.

[5] A polymer described in any one of [1] to [4], wherein the polymer has a crosslinkable group as a substituent.

[6] A polymer described in any of [1] to [5], wherein the weight average molecular weight (Mw) of the polymer is 10,000 or more and the dispersity (Mw/Mn) is 3.5 or less.

[7] The polymer according to any one of [1] to [6], wherein Ar ¹ in the formula (1)-2 is a group in which two or more optionally substituted divalent aromatic hydrocarbon groups are linked together.

[8] The polymer according to any one of [1] to [7], wherein Ar ¹ in the formula (1)-2 contains at least one benzene ring linked at the 1- and 3-positions.

[9] A composition for organic electroluminescent devices containing a polymer described in any one of [1] to [8].

[10] A composition for forming a hole transport layer or a hole injection layer, comprising a polymer described in any one of [1] to [8].

[11] A method for manufacturing an organic electroluminescent device having an anode, a cathode, and an organic layer between the anode and the cathode on a substrate, the method including a film-forming step of forming at least one of the organic layers by a wet film-forming method using the composition for organic electroluminescent devices described in [9].

[12] A method for manufacturing an organic electroluminescent element described in [11], wherein the organic layer formed in the film formation step is at least one of a hole injection layer and a hole transport layer.

[13] A method for manufacturing an organic electroluminescent element described in [11] or [12], which includes a hole injection layer, a hole transport layer, and an emission layer between the anode and the cathode, and the organic layer formed in the film formation step is the hole injection layer, the hole transport layer, and the emission layer.

[14] An organic electroluminescent device comprising a layer containing a polymer according to any one of [1] to [8], or a polymer crosslinked from the polymer.

[15] An organic EL display device comprising the organic electroluminescent element described in [14].

[16] Organic EL lighting comprising the organic electroluminescent element described in [14].

According to the present invention, it is possible to provide a polymer having high hole injection and transport ability and high durability, and a composition for an organic electroluminescent element containing the polymer. According to the present invention, it is also possible to provide an organic electroluminescent element having high brightness and a long operating life.

The reason why the polymer according to one embodiment of the present invention exhibits the above-mentioned effects is not clear, but the following is thought to be the reason.
In a hole transport polymer having a specific structure including a specific 6-membered heteroaromatic ring having a nitrogen atom, which may have a substituent, in a side chain via an aromatic hydrocarbon group, which may have a substituent, the main chain and the specific 6-membered heteroaromatic ring having a nitrogen atom form a conjugated structure. For example, in a polymer structure using a main chain having an amine structure, the HOMO is distributed in the vicinity of the amine of the main chain, and the LUMO is distributed around the specific 6-membered heteroaromatic ring having a nitrogen atom.
The longer the conjugation between the amine of the main chain and the specific 6-membered heteroaromatic ring having a nitrogen atom, the more likely the LUMO is distributed in the specific 6-membered heteroaromatic ring having a nitrogen atom.

In the polymer of the present embodiment, the divalent aromatic hydrocarbon group Ar ¹ is present between the main chain and a specific 6-membered heteroaromatic ring having a nitrogen atom, so that the HOMO and LUMO in the molecule are separated and localized. Therefore, the highly electron-durable portion where the LUMO is distributed receives electrons, so that the durability against electrons is improved, and the hole transport property of the main chain is not inhibited, resulting in excellent hole transport property.
In the present invention, the 6-membered heteroaromatic ring having a nitrogen atom refers to a 6-membered heteroaromatic ring containing X and Y and contained in structure A of formula (1), and specifically may have a pyridine, pyrimidine, or triazine structure.

The main chain of the polymer of this embodiment preferably contains a fluorene ring or a carbazole ring. In this case, it is preferable that a phenylene group is bonded to the 2,7-position of the fluorene ring or the carbazole ring. By bonding a phenylene group to the 2,7-position of the fluorene ring or the carbazole ring, the fluorene ring or the carbazole ring becomes electrically more stable. In particular, it is considered that the electronic durability is improved and the device operation life is extended. At this time, when the phenylene ring has a substituent at the ortho position, the plane of the phenylene group having the substituent is more twisted relative to the plane of the adjacent fluorene ring or the carbazole ring due to the steric hindrance of the substituent. In this case, since the main chain structure has a π-conjugated system that is inhibited from spreading due to the steric hindrance of the substituent, the singlet excited energy level (S ₁ ) and the triplet excited energy level (T ₁ ) are high, and quenching due to energy transfer from the light-emitting exciton is suppressed, resulting in excellent luminous efficiency.

The main chain of the polymer of this embodiment preferably contains a phenylene group having a substituent. When the phenylene group of the main chain has a substituent, the plane of the phenylene group having the substituent is more twisted relative to the plane of the adjacent phenylene group, divalent fluorene group, or divalent carbazole group due to the steric hindrance of the substituent, and crystallization is less likely to occur due to the steric hindrance of the substituent, and the excited singlet energy level (S ₁ ) and excited triplet energy level (T ₁ ) are high, which is preferable.

The polymer of the present embodiment has a main chain structure in which the phenylene group and the oxygen atom are alternately bonded to each other, and thus the main chain structure has a structure in which the spread of the π-conjugated system is inhibited. Therefore, the polymer has a high excited singlet energy level (S ₁ ) and excited triplet energy level (T ₁ ), and is preferable because it has excellent luminous efficiency since quenching due to energy transfer from the luminescent exciton is suppressed.

In an organic electroluminescence device, if the energy level difference between the organic layers is not appropriate, it becomes difficult to inject carriers into the light-emitting layer, leading to an increase in the driving voltage, or carrier leakage from the light-emitting layer to an adjacent layer is likely to occur, leading to a decrease in device efficiency.
In contrast, a charge transport material having an energy level higher than the energy level of excitons of the light emitting material in the light emitting layer, such as the polymer of this embodiment, is preferable because it has a high effect of trapping excitons of the light emitting material.

The layer obtained by wet film formation using the composition for organic electroluminescent elements containing the polymer of this embodiment is flat and free of cracks. As a result, the organic electroluminescent element having this layer, which is another embodiment of the present invention, has high brightness and a long operating life.

The polymer of this embodiment has excellent electrochemical stability. Therefore, an element including a layer formed using the polymer can be applied to flat panel displays (for example, for office computers and wall-mounted televisions), in-vehicle display elements, cell phone displays, light sources that utilize the characteristics of surface light emitters (for example, light sources for copiers, backlight sources for liquid crystal displays and instruments), display boards, and marker lights, and has great technical value.

FIG. 1 is a schematic cross-sectional view showing an example of the structure of an organic electroluminescent device of the present invention.

Hereinafter, a polymer according to one embodiment of the present invention, a composition for organic electroluminescent elements and a composition for forming a hole transport layer or a hole injection layer, each of which contains the polymer, an organic electroluminescent element including a layer formed using the composition and a method for producing the same, and an organic EL display device and an organic EL lighting device having the organic electroluminescent element will be described in detail.
The following description is an example (typical example) of an embodiment of the present invention, and the present invention is not limited to these contents as long as it does not deviate from the gist of the present invention.

[Polymer]
The polymer according to one embodiment of the present invention is a polymer containing a repeating unit represented by the following formula (1).

In formula (1), G represents an aromatic hydrocarbon group which may have a substituent, or a nitrogen atom.
^Ar2 represents a divalent aromatic hydrocarbon group which may have a substituent, a divalent aromatic heterocyclic group which may have a substituent, or a divalent group in which two or more groups selected from a divalent aromatic hydrocarbon group which may have a substituent and a divalent aromatic heterocyclic group which may have a substituent are linked together directly or via a linking group.
A is a structure containing a specific 6-membered heteroaromatic ring having a nitrogen atom and is represented by formula (1)-2.
In formula (1)-2, Ar ¹ represents a divalent aromatic hydrocarbon group which may have a substituent.
^Ar3 and ^Ar4 each independently represent an aromatic hydrocarbon group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or a monovalent group in which two or more groups selected from an aromatic hydrocarbon group which may have a substituent and an aromatic heterocyclic group which may have a substituent are linked together directly or via a linking group.
X and Y each independently represent a C atom or a N atom. When X or Y is a C atom, it may have a substituent.
"-*" is the site that bonds to G in formula (1).

<G>
In the repeating unit represented by formula (1), G represents an aromatic hydrocarbon group which may have a substituent, or an N atom. From the viewpoint of excellent charge transportability and of the LUMO distributed around a specific 6-membered heteroaromatic ring having a nitrogen atom and the HOMO distributed in the main chain being separated and localized, G is preferably a benzene ring which may have a substituent, a fluorene ring which may have a substituent, or a spirofluorene ring which may have a substituent, and more preferably a structure shown in the following scheme 1. The following structure may have a substituent. "-*" represents a bonding site with Ar ¹ .

When G is an aromatic hydrocarbon group which may have a substituent, the optional substituent is preferably any one of the substituent group Z described below, an aralkyl group having 7 to 40 carbon atoms, or an aralkyl group of a heterocycle having 4 to 37 carbon atoms, or a combination thereof. Among them, from the viewpoint of durability, each occurrence of each of them may be the same or different, and is preferably an alkyl group having 1 to 24 carbon atoms, an aralkyl group having 7 to 40 carbon atoms, an aralkyl group of a heterocycle having 3 to 37 carbon atoms, an arylamino group having 10 to 24 carbon atoms, an aromatic hydrocarbon group having 6 to 36 carbon atoms, or an aromatic heterocyclic group having 3 to 36 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms, an aralkyl group having 7 to 30 carbon atoms, an aralkyl group of a heterocycle having 3 to 27 carbon atoms, an aromatic hydrocarbon group having 6 to 24 carbon atoms, or an aromatic heterocyclic group having 3 to 24 carbon atoms, and even more preferably an aromatic hydrocarbon group having 6 to 24 carbon atoms.
From the viewpoint of charge transport properties, each occurrence of each of these groups may be the same or different and is preferably an aromatic hydrocarbon group having 6 to 24 carbon atoms or an aromatic heterocyclic group having 3 to 24 carbon atoms, and more preferably a phenyl group, a naphthyl group, a fluorenyl group, a carbazolyl group, an indolocarbazolyl group, an indenocarbazolyl group, or an indenofluorenyl group.
In particular, when G is bonded to the 9-position of spirobifluorene or fluorene, it breaks conjugation, and therefore from the viewpoint of further localizing the LUMO distributed in the specific 6-membered heteroaromatic ring having a nitrogen atom and the HOMO distributed in the main chain, it is preferable that G is a fluorenyl group or an indenofluorenyl group.

It is preferable that G is an N atom (nitrogen atom) because it has excellent charge transport properties, particularly excellent hole transport properties.

<Ar ¹ and Ar ² >
In the repeating unit represented by formula (1), Ar ¹ represents a divalent aromatic hydrocarbon group which may have a substituent, and Ar ² represents a divalent aromatic hydrocarbon group which may have a substituent, a divalent aromatic heterocyclic group which may have a substituent, or a divalent group in which two or more groups selected from a divalent aromatic hydrocarbon group which may have a substituent and a divalent aromatic heterocyclic group which may have a substituent are linked together directly or via a linking group.

The aromatic hydrocarbon group preferably has 6 or more and 60 or less carbon atoms, and specific examples thereof include divalent groups of a 6-membered monocyclic ring or 2 to 5 condensed rings such as a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring, or a divalent group formed by linking multiple of these.

The aromatic heterocyclic group preferably has 3 or more and 60 or less carbon atoms, and specifically includes a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, a carbazole ring, a pyrroloimidazole ring, a pyrrolopyrazole ring, a pyrrolopyrrole ring, a thienopyrrole ring, a thienothiophene ring, a furopyrrole ring, a furofuran ring, a thienofuran ring, a benzoiso Examples of such divalent groups include a 5- or 6-membered monocyclic or 2- to 4-condensed ring divalent groups, such as an oxazole ring, a benzisothiazole ring, a benzimidazole ring, a pyridine ring, a pyrazine ring, a pyridazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a cinnoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, or an azulene ring, or a divalent group formed by linking a plurality of these rings.

The divalent group in which two or more groups selected from an aromatic hydrocarbon group which may have a substituent and an aromatic heterocyclic group which may have a substituent are linked together directly or via a linking group may be a group in which multiple identical groups are linked together, or a group in which multiple different groups are linked together.

From the viewpoint of localizing the LUMO distributed in the specific 6-membered heteroaromatic ring having a nitrogen atom in formula (1)-2 and the HOMO distributed in the main chain, Ar ¹ is preferably one divalent aromatic hydrocarbon group which may have a substituent or a group in which 2 to 10 divalent aromatic hydrocarbon groups which may have a substituent are linked, more preferably one divalent aromatic hydrocarbon group which may have a substituent or a group in which 2 to 8 divalent aromatic hydrocarbon groups which may have a substituent are linked, and among these, a group in which 2 or more divalent aromatic hydrocarbon groups which may have a substituent are linked is preferable.
Ar ¹ is preferably a group in which 2 to 6 benzene rings which may be substituted are linked, and most preferably a quaterphenylene group in which 4 benzene rings which may be substituted are linked.

From the viewpoint of further localizing the LUMO distributed in the specific 6-membered heteroaromatic ring having a nitrogen atom and the HOMO distributed in the main chain in formula (1)-2, Ar ¹ preferably contains at least one benzene ring linked at the 1,3-positions, which is a non-conjugated site, and more preferably contains two or more.
When Ar ¹ is a group in which a plurality of divalent aromatic hydrocarbon groups which may have a substituent are linked, it is preferred that all of them are linked by direct bonds from the viewpoint of charge transport properties or durability.

The present inventors performed structural optimization by DFT calculations using B3LYP as the functional and 6-31G as the basis function for the following units DUL-413, DUL-414, DUL-415, and DUL-416, in which the specific 6-membered heteroaromatic ring having a nitrogen atom in formula (1)-2 is a triazine ring, and then analyzed the distribution of the HOMO and LUMO of each unit by displaying the isoelectron density surface (0.02) of the HOMO and LUMO in Gauss View (HPC Systems). Furthermore, the overlap (square root of the inner product) between the distributions of the frontier orbitals (HOMO and LUMO) defined in the Mulliken distribution flow was calculated, and the value was determined as the "HOMO-LUMO overlap". The results are shown in Table 1.

From the results of the calculation, it was found that the LUMO of the molecule is distributed around the triazine ring in DUL-413, DUL-414, DUL-415 and DUL-416. In addition, the phenylene group between the nitrogen atom of the amine and the triazine ring is preferably linked at the meta position rather than at the para position, since the overlap value between the HOMO and the LUMO is smaller. Furthermore, the greater the number of phenylene groups linked at the meta position between the nitrogen atom of the amine and the triazine ring, the smaller the overlap value between the HOMO and the LUMO. The smaller the overlap between the LUMO around the triazine ring, which is the site that receives electrons, and the HOMO around the triphenylamine, which is the site that receives holes, the more chemically stable the molecule is.
The HOMO-LUMO overlap value is preferably 0.1 or less, more preferably 0.05 or less, and even more preferably less than 0.01.
Since the overlap between the HOMO and LUMO is smaller when the number of phenylene groups linked at the meta positions is 4 than when the number is 3, the HOMO-LUMO overlap value is particularly preferably less than 0.0024.
Therefore, preferred structures for ^Ar1 linking G and the specific 6-membered heteroaromatic ring shown in formula (1)-2 are as shown in the following schemes 2-1 and 2-2. "-*" represents the bonding site between G and the specific 6-membered heteroaromatic ring in formula (1)-2. Either of the two "-*"s may be bonded to G, and may be bonded to the specific 6-membered heteroaromatic ring.

From the viewpoints of excellent charge transport properties and excellent durability, ^Ar2 is preferably a divalent group to which one or more groups selected from a divalent aromatic hydrocarbon group which may have a substituent and a divalent aromatic heterocyclic group which may have a substituent are bonded directly or via a linking group.

When ^Ar2 has a linking group, the linking group is preferably an oxygen atom or a carbonyl group.
Since the triplet level can be increased by forming a non-conjugated structure with an aromatic ring, a structure in which the rings are linked by an oxygen atom or a carbonyl group is preferred.

From the viewpoint of improving the charge transport property and providing excellent stability by expanding the π-conjugated system, the ring contained in Ar ² is preferably a benzene ring or a fluorene ring.
A twisted structure in which a fluorene ring is bonded to a phenylene group having an alkyl group is particularly preferred from the viewpoint of forming a main chain structure in which the spread of the π-conjugated system is inhibited, the excited singlet energy level (S ₁ ) and the excited triplet energy level (T ₁ ), suppressing quenching due to energy transfer from the light-emitting exciton, and providing excellent luminous efficiency. Among these, a structure in which Ar ² contains a phenylene group having a methyl group is particularly preferred from the viewpoint of the difficulty of synthesizing and purifying the monomer intermediate.

When G is a nitrogen atom, hole transport properties are improved, and therefore, as the partial structure of ^Ar2 directly bonded to G, an aromatic hydrocarbon group which may have a substituent is preferable, a phenylene group which may have a substituent or a fluorenylene group which may have a substituent is more preferable, and a phenylene group which may have a substituent is particularly preferable.
A fluorene ring or a carbazole ring is preferably bonded to the benzene ring directly bonded to the nitrogen atom G. A structure in which one or more phenylene groups are further linked between the benzene ring directly bonded to the nitrogen atom of G and the fluorene ring or the carbazole ring is also preferred.

As the substituent that Ar ¹ may have, any one of the substituent group Z described below or a combination thereof can be used. The preferred range of the substituent that Ar ¹ may have is the same as the substituent that Ar 1 may have when G is an aromatic hydrocarbon group.

The substituent that ^Ar2 may have is the same as the substituent that Ar2 may have when G is an aromatic hydrocarbon group.

<X and Y>
X and Y each independently represent a C (carbon) atom or an N (nitrogen) atom. When X or Y is a C atom, it may have a substituent.
From the viewpoint of making it easier to localize LUMO around a specific 6-membered heteroaromatic ring having a nitrogen atom, it is preferable that both X and Y are N atoms.

When X or Y is a C atom, the substituent that may be present may be any one of the substituent group Z described below or a combination thereof. From the viewpoint of charge transport properties, it is more preferable that the compound has no substituent.

< ^Ar3 and ^Ar4 >
^Ar3 and ^Ar4 each independently represent an aromatic hydrocarbon group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or a monovalent group in which two or more groups selected from an aromatic hydrocarbon group which may have a substituent and an aromatic heterocyclic group which may have a substituent are linked together directly or via a linking group.

From the viewpoint of distributing the LUMO of the molecule, it is preferable that Ar ³ and Ar ⁴ each independently have a structure selected from a-1 to a-4, b-1 to b-9, c-1 to c-5, d-1 to d-17, and e-1 to e-4 shown in Scheme 3 below.
Furthermore, from the viewpoint of promoting the broadening of the LUMO of the molecule by having an electron-withdrawing group, a structure selected from a-1 to a-4, b-1 to b-9, c-1 to c-5, d-1 to d-13, and e-1 to e-4 is preferable.
Furthermore, from the viewpoint of the effect of trapping excitons formed in the light-emitting layer, which has a high triplet level, structures selected from a-1 to a-4, d-1 to d-13, and e-1 to e-4 are preferred.
In order to prevent molecular aggregation, structures selected from d-1 to d-13 and e-1 to e-4 are more preferred, and a benzene ring structure in which Ar ³ =Ar ⁴ =d-3 is particularly preferred from the viewpoints of ease of synthesis and excellent stability.
These structures may also have a substituent. "-*" represents a bonding site to a specific 6-membered heteroaromatic ring having a nitrogen atom. When there are multiple "-*", any one of them represents a bonding site to a specific 6-membered heteroaromatic ring having a nitrogen atom.

As the substituent that ^Ar3 and ^Ar4 may have, any one of the substituent group Z described below or a combination thereof can be used. From the viewpoint of durability and charge transportability, it is preferable that the substituent is the same as the above-mentioned substituent of ^Ar2 .

< ^R31 and ^R32 >
In Scheme 3, R ³¹ and R ³² are each preferably independently a linear, branched or cyclic alkyl group which may have a substituent. The number of carbon atoms of the alkyl group is not particularly limited, but in order to maintain the solubility of the polymer, the number of carbon atoms is preferably 1 to 6, more preferably 3 or less, and further preferably a methyl group or an ethyl group.

R ³¹ and R ³² may be the same or different, but it is preferable that all R ³¹ and R ³² are the same group, since this allows the charge to be uniformly distributed around the nitrogen atom and also facilitates synthesis.

[Preferable repeating unit structure]
The repeating unit represented by formula (1) is preferably a repeating unit represented by any one of the following formulas (2)-1 to (2)-3.

In the formulas (2)-1 to (2)-3, A is the same as A in the above formula (1).
Q represents -C(R ⁵ )(R ⁶ )-, -N(R ⁷ )- or -C(R ¹¹ )(R ¹² )-C(R ¹³ )(R ¹⁴ )-.
R ¹ to R ⁴ each independently represent an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or an aralkyl group which may have a substituent.
R ⁵ to R ⁷ and R ¹¹ to R ¹⁴ each independently represent an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aralkyl group which may have a substituent, or an aromatic hydrocarbon group which may have a substituent.
a and b each independently represents an integer of 0 to 4.
c1 to c5 each independently represents an integer of 0 to 3.
However, at least one of c3 and c5 is 1 or more.
d1 to d4 each independently represents an integer of 1 to 4.
When a plurality of R ¹ , R ² , R ³ and R ⁴ are present in the repeating unit, R ¹ , R ² , R ³ and R ⁴ may be the same or different.

< ^R1 and ^R2 >
In the repeating units represented by formulae (2)-1 to (2)-3, R ¹ and R ² are each independently an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or an aralkyl group which may have a substituent. It is preferable that R ¹ and R ² are each independently a linear, branched, or cyclic alkyl group which may have a substituent.
The number of carbon atoms in the alkyl group is not particularly limited, but in order to maintain the solubility of the polymer, the number of carbon atoms is preferably 1 to 6, more preferably 3 or less, and further preferably a methyl group or an ethyl group.

When there are a plurality of ^R1 and ^R2 in the repeating unit, ^R1 and ^R2 may be the same or different, but it is preferable that all ^R1 and ^R2 are the same group, since this allows the charge to be uniformly distributed around the nitrogen atom and also facilitates synthesis.

< ^R3 and ^R4 >
In the repeating units represented by formulae (2)-1 to (2)-3, ^R3 and ^R4 are each independently an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or an aralkyl group which may have a substituent. It is preferable that ^R3 and ^R4 are each independently a linear, branched, or cyclic alkyl group which may have a substituent.
The number of carbon atoms in the alkyl group is not particularly limited, but in order to maintain the solubility of the polymer, the number of carbon atoms is preferably 1 or more, more preferably 4 or more, and is preferably 12 or less, even more preferably 8 or less, and is particularly preferably a hexyl group.

<R ⁵ to R ⁷ and R ¹¹ to R ¹⁴ >
R ⁵ to R ⁷ and R ¹¹ to R ¹⁴ are each independently an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aralkyl group which may have a substituent, or an aromatic hydrocarbon group which may have a substituent. It is preferable that R ⁵ to R ⁷ and R ¹¹ to R ¹⁴ are each independently an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or an aromatic hydrocarbon group which may have a substituent.

The alkyl group is not particularly limited, but it is preferable that it is long in order to easily improve the solubility of the polymer, and it is preferable that it is short in order to improve the stability of the film and improve the charge transportability.The alkyl group preferably has 1 or more and 24 or less carbon atoms, more preferably 12 or less, even more preferably 8 or less, particularly preferably 6 or less, more preferably 2 or more, even more preferably 3 or more, and particularly preferably 4 or more.The alkyl group may be any of linear, branched, or cyclic structures.
Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a tert-butyl group, an n-hexyl group, an n-octyl group, a cyclohexyl group, and a dodecyl group.

The alkoxy group is not particularly limited, but in order to easily improve the solubility of the polymer, the alkoxy group preferably has 1 or more and 24 or less carbon atoms, more preferably 12 or less, even more preferably 8 or less, particularly preferably 6 or less, more preferably 2 or more, even more preferably 3 or more, and particularly preferably 4 or more.
Specific examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, an i-butoxy group, a tert-butoxy group, and a hexyloxy group.

The aralkyl group is not particularly limited, but since it is easy to improve the solubility of the polymer, it preferably has 7 to 60 carbon atoms, more preferably 40 or less, still more preferably 8 or more, even more preferably 10 or more, and particularly preferably 12 or more.
Specific examples of the aralkyl group include a 1,1-dimethyl-1-phenylmethyl group, a 1,1-di(n-butyl)-1-phenylmethyl group, a 1,1-di(n-hexyl)-1-phenylmethyl group, a 1,1-di(n-octyl)-1-phenylmethyl group, a phenylmethyl group, a phenylethyl group, a 3-phenyl-1-propyl group, a 4-phenyl-1-n-butyl group, a 1-methyl-1-phenylethyl group, a 5-phenyl-1-n-propyl group, a 6-phenyl-1-n-hexyl group, a 6-naphthyl-1-n-hexyl group, a 7-phenyl-1-n-heptyl group, an 8-phenyl-1-n-octyl group, and a 4-phenylcyclohexyl group.

The aromatic hydrocarbon group is not particularly limited, but in order to easily improve the solubility of the polymer, the aromatic hydrocarbon group preferably has 6 to 60 carbon atoms, more preferably 30 or less, even more preferably 24 or less, and particularly preferably 14 or less.
Specific examples of the aromatic hydrocarbon group include monovalent groups of 6-membered monocyclic rings or 2 to 5 condensed rings, such as a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring, or groups in which 2 to 8 ring structures selected from these are linked together. Preferred are monocyclic rings or groups in which 2 to 4 ring structures are linked together.

From the viewpoint of improving charge transport properties and durability, ^R5 to ^R7 are preferably alkyl groups or aromatic hydrocarbon groups. ^R5 and ^R6 are more preferably alkyl groups. ^R7 is more preferably an aromatic hydrocarbon group. The preferred carbon numbers of these groups are as described above.
In terms of improving solubility and at the same time providing excellent charge transport properties, R ⁵ and R ⁶ are preferably an alkyl group having 3 to 8 carbon atoms or an aralkyl group having 9 to 40 carbon atoms.

The alkyl group, alkoxy group, aralkyl group of R ¹ to R ^4, and the alkyl group, alkoxy group, aralkyl group, and aromatic hydrocarbon group of R ⁵ to R ⁷ and R ¹¹ to R ¹⁴ may further have a substituent. Examples of the substituent that may further have include the groups exemplified as preferred groups for the alkyl group, alkoxy group, aralkyl group, and aromatic hydrocarbon group of R ⁵ to R ⁷ and R ¹¹ to R ¹⁴ , or the crosslinkable groups described below.
From the viewpoint of reducing the voltage, it is ^most preferable that the alkyl groups, alkoxy groups and aralkyl groups of R ¹ to R ⁴ and the alkyl groups, alkoxy groups, aralkyl groups and aromatic hydrocarbon groups of R ⁵ to R ⁷ and R 11 to R ¹⁴ have no substituents.

The substituents that R ⁵ to R ⁷ and R ¹¹ to R ¹⁴ may further have are preferably the crosslinkable groups described below from the viewpoint of improving insolubility in a solvent when another layer is coated and laminated after the polymer of this embodiment is formed into a film. Among them, it is preferable that any of R ⁵ , R ⁶ , and R ¹¹ to R ¹⁴ has the crosslinkable group described below as a further substituent, and it is even more preferable that at least one of R ⁵ and R ⁶ has the crosslinkable group described below as a further substituent, since this is unlikely to impede the charge transport property.

<a, b, c1 to c5, d1 to d4>
In the repeating units represented by formulas (2)-1 to (2)-3, a and b are each independently an integer of 0 to 4. a and b are each 2 or less. It is preferred that a and b are both 0 or 1 at the same time.

In the repeating units represented by formulae (2)-1 to (2)-3, c1 to c5 each independently represent an integer of 0 to 3, provided that at least one of c3 and c5 is equal to or greater than 1. d1 to d4 each independently represent an integer of 1 to 4.
It is preferable that c1 to c5 and d1 to d4 each independently is 2 or less.
It is more preferable that both c1 and c2 are simultaneously 0 or 1. It is more preferable that both c1 and c2 are 1 or more.
At least one of c3 and c4, or both of c3 and c4, is preferably 1 or more. It is more preferable that both of c3 and c4 are 1.
It is preferable that c5 is 1 or more.
It is more preferable that c1 and c2, c3 and c4, and d1 to d4 are equal to each other. It is even more preferable that c1 to c5 and d1 to d4 are all 1 or 2. It is particularly preferable that c1 to c5 and d1 to d4 are all 1.

When both c1 and c2 in the repeating unit represented by formula (2)-1 are simultaneously 1 or 2, and both a and b are 2 or 1, ^R1 and ^R2 are most preferably bonded at positions symmetrical to each other.
When both c3 and c4 in the repeating unit represented by formula (2)-2 are simultaneously 1 or 2, and both a and b are 2 or 1, ^R1 and ^R2 are most preferably bonded at positions symmetrical to each other.

Here, the fact that ^R1 and ^R2 are bonded to positions symmetric to each other will be described with reference to the following formulas (1-1) and (1-2) taking as an example a case where Q=C, c1=c2=1, and a=b=2 in formula (2)-1.
^R1 and ^R2 being bonded at positions symmetrical to each other means that the bonding positions of ^R1 and ^R2 are symmetrical with respect to the fluorene ring of the main chain in the following formulae (1-1) and (1-2). In this case, a 180-degree rotation around the main chain is regarded as the same structure. For example, in the following formula (1-1), ^R1 ' and ^R2 ' are symmetrical, and ^R1 " and ^R2 " are symmetrical, and formula (1-1) and formula (1-2) are regarded as the same structure.

<Specific examples>
Specific examples of preferred repeating unit structures include the following structures.

[Substituent group Z]
The substituent group Z includes the following substituents.
For example, linear, branched, or cyclic alkyl groups having a carbon number of usually 1 or more, preferably 4 or more, and usually 24 or less, preferably 12 or less, such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a tert-butyl group, an n-hexyl group, a cyclohexyl group, or a dodecyl group;
For example, an alkenyl group having usually 2 or more carbon atoms and usually 24 or less, preferably 12 or less, such as a vinyl group;
For example, an alkynyl group having usually 2 or more carbon atoms and usually 24 or less, preferably 12 or less carbon atoms, such as an ethynyl group;
For example, an alkoxy group having usually 1 or more and usually 24 or less, preferably 12 or less, carbon atoms, such as a methoxy group or an ethoxy group;
For example, an aryloxy group or heteroaryloxy group having usually 4 or more, preferably 5 or more, and usually 36 or less, preferably 24, carbon atoms, such as a phenoxy group, a naphthoxy group, or a pyridyloxy group;
For example, an alkoxycarbonyl group having usually 2 or more and usually 24 or less, preferably 12 or less, carbon atoms, such as a methoxycarbonyl group or an ethoxycarbonyl group;
For example, dialkylamino groups having usually 2 or more and usually 24 or less, preferably 12 or less, carbon atoms, such as a dimethylamino group or a diethylamino group;
For example, diarylamino groups having usually 10 or more, preferably 12 or more, and usually 36 or less, preferably 24 or less, such as a diphenylamino group, a ditolylamino group, or an N-carbazolyl group;
For example, an arylalkylamino group, such as a phenylmethylamino group, which usually has 7 or more carbon atoms and usually has 36 or less, preferably 24 or less carbon atoms;
For example, acyl groups such as an acetyl group and a benzoyl group, each of which usually has 2 or more carbon atoms and usually has 24 or less, preferably 12 or less carbon atoms;
For example, halogen atoms such as fluorine atoms and chlorine atoms;
For example, haloalkyl groups having typically 1 or more and typically 12 or less, preferably 6 or less, carbon atoms, such as a trifluoromethyl group;
For example, an alkylthio group having usually 1 or more and usually 24 or less, preferably 12 or less, carbon atoms, such as a methylthio group or an ethylthio group;
For example, an arylthio group or heteroarylthio group having usually 4 or more, preferably 5 or more, and usually 36 or less, preferably 24 or less, such as a phenylthio group, a naphthylthio group, or a pyridylthio group;
For example, a silyl group having a carbon number of usually 2 or more, preferably 3 or more, and usually 36 or less, preferably 24 or less, such as a trimethylsilyl group or a triphenylsilyl group;
For example, a siloxy group having a carbon number of usually 2 or more, preferably 3 or more, and usually 36 or less, preferably 24 or less, such as a trimethylsiloxy group or a triphenylsiloxy group;
Cyano group;
For example, an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, or a monovalent group in which a plurality of identical or different monocyclic or condensed aromatic hydrocarbon rings are linked together, the carbon number of which is usually 6 or more and usually 36 or less, preferably 24 or less;
For example, a thienyl group or the like, or a monovalent group in which a plurality of identical or different monocyclic or condensed aromatic heterocyclic rings are linked together, the monovalent group having usually 3 or more, preferably 5 or more, and usually 36 or less, preferably 24 or less, carbon atoms:
A monovalent aromatic group in which an aromatic hydrocarbon ring and an aromatic heterocyclic group are linked, and when there are a plurality of aromatic hydrocarbon rings or aromatic heterocyclic groups, they may be the same or different, and the monovalent aromatic group has 8 to 36 carbon atoms, preferably 24 or less.

Among the above-mentioned substituent group Z, preferred are the alkyl groups, alkoxy groups, aromatic hydrocarbon groups, aromatic heterocyclic groups other than the groups containing a specific 6-membered heteroaromatic ring having a nitrogen atom, or monovalent aromatic groups to which an aromatic hydrocarbon ring and an aromatic heterocyclic group are linked. From the viewpoint of charge transportability, it is more preferred that the compound has no substituent or has a monovalent aromatic group to which an aromatic hydrocarbon group, an aromatic heterocyclic group, or an aromatic hydrocarbon ring and an aromatic heterocyclic group are linked.

Each of the substituents in the substituent group Z may further have a substituent. Examples of the substituents include the same ones as the above-mentioned substituents (substituent group Z) or the crosslinkable groups described below. Preferably, the compound has no further substituents, or has as a further substituent an alkyl group having 6 or less carbon atoms, an alkoxy group having 6 or less carbon atoms, a phenyl group, or a crosslinkable group described below. From the viewpoint of charge transportability, it is more preferable that the compound has no further substituents.

[End group]
In this embodiment, the term "terminal group" refers to the structure of the terminal part of the polymer formed by the endcapping agent used at the end of polymerization of the polymer. The terminal group of the polymer in this embodiment is usually a hydrocarbon group. From the viewpoint of charge transportability, the hydrocarbon group preferably has 1 to 60 carbon atoms, more preferably 1 to 40 carbon atoms, and even more preferably 1 to 30 carbon atoms.

The terminal group preferably includes the following:
For example, a linear, branched, or cyclic alkyl group having usually 1 or more, preferably 4 or more, and usually 24 or less, preferably 12 or less, such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a tert-butyl group, an n-hexyl group, a cyclohexyl group, or a dodecyl group.
For example, an alkenyl group, such as a vinyl group, which usually has 2 or more carbon atoms and usually has 24 or less, preferably 12 or less carbon atoms.
For example, an alkynyl group, such as an ethynyl group, which usually has 2 or more carbon atoms and usually has 24 or less, preferably 12 or less carbon atoms.
For example, aromatic hydrocarbon ring groups having usually 6 or more and usually 36 or less, preferably 24 or less, carbon atoms, such as a phenyl group or a naphthyl group.

These hydrocarbon groups may further have a substituent. The optional substituent is preferably an alkyl group or an aromatic hydrocarbon group, and when there are a plurality of these optional substituents, they may be bonded to each other to form a ring.
The substituent that the terminal hydrocarbon group may further have is preferably an alkyl group or an aromatic hydrocarbon group, more preferably an aromatic hydrocarbon group, from the viewpoints of charge transportability and durability.

[Soluble group]
The polymer of this embodiment preferably has a soluble group in order to exhibit solubility in a solvent. The soluble group in this embodiment is a group having a linear or branched alkyl or alkylene group having 3 to 24 carbon atoms, preferably 12 or less. Among these, preferred are alkyl, alkoxy, or aralkyl groups, such as n-propyl, 2-propyl, n-butyl, isobutyl, n-hexyl, and n-octyl groups. More preferred are n-hexyl and n-octyl groups. The soluble group may have a substituent.

<Number of Soluble Groups>
The polymer of the present embodiment preferably has a large number of soluble groups in that a polymer solution that can be used in a wet film-forming method can be easily obtained, whereas the polymer of the present embodiment preferably has a small number of soluble groups in that a film thickness reduction caused by dissolving the lower layer in a solvent is small when another layer is formed on the layer formed using the polymer of the present embodiment by a wet film-forming method.

The number of soluble groups contained in the polymer of the present embodiment can be expressed as the number of moles per gram of the polymer.
The number of soluble groups contained in the polymer of this embodiment, expressed as the number of moles per gram of polymer, is usually 4.0 mmol or less, preferably 3.0 mmol or less, and more preferably 2.0 mmol or less, and is usually 0.1 mmol or more, and preferably 0.5 mmol or more, per gram of polymer.
When the number of soluble groups is within the above range, the polymer is easily dissolved in a solvent, and a composition containing the polymer suitable for a wet film-forming method can be easily obtained. In addition, since the soluble group density is appropriate and the polymer has sufficient poor solubility in an organic solvent after drying with heating, a multilayer laminate structure can be formed by the wet film-forming method.

Here, the number of soluble groups per 1 g of the polymer can be calculated from the molar ratio of the monomers charged during synthesis and the structural formula, excluding the terminal groups from the polymer.
The following will explain the case of Polymer 1 synthesized in Example 1 described later.
In polymer 1, the molecular weight of the repeating units excluding the terminal groups is 748.4 on average. The number of hexyl groups, which are soluble groups, is 1.3 on average per repeating unit. When calculated based on a simple proportionality, the number of soluble groups per gram of molecular weight is calculated to be 1.74 millimoles.

[Crosslinkable group]
The polymer of this embodiment may have a crosslinkable group. The crosslinkable group in the polymer of this embodiment may be present in the repeating unit represented by the formula (1) or may be present in a repeating unit other than the repeating unit represented by the formula (1). In particular, it is preferable that the aromatic hydrocarbon group or aromatic heterocyclic group bonded as a side chain has a crosslinkable group, since the crosslinking reaction is likely to proceed.
The presence of a crosslinkable group can cause a large difference in solubility in an organic solvent before and after a reaction (insolubilization reaction) caused by irradiation with heat and/or active energy rays.

A crosslinkable group is a group that, upon exposure to heat and/or active energy rays, reacts with a group constituting another molecule located in the vicinity of the crosslinkable group to form a new chemical bond. In this case, the reactive group may be the same as or different from the crosslinkable group.

As the crosslinkable group, a group containing a cyclobutene ring condensed with an aromatic ring or an alkenyl group bonded to an aromatic ring is preferred, and a group selected from the crosslinkable group group K below is more preferred. The crosslinkable group is preferably contained in the polymer in the form of a further substitution on the substituent of each of the above structures.

<Crosslinking Group K>
The crosslinkable group group K has the structure shown below.

In the crosslinkable group group K, R ²¹ to R ²³ each independently represent a hydrogen atom or an alkyl group. R ²⁴ to R ²⁶ each independently represent an alkyl group or an alkoxy group. p represents an integer of 1 to 4, q represents an integer of 1 to 4, and r represents an integer of 1 to 4.
When p is 2 or more, multiple R ^{24 s} may be the same or different, and adjacent R ²⁴ s may be bonded to each other to form a ring.
When q is 2 or more, multiple R ²⁵ may be the same or different, and adjacent R ²⁵ may be bonded to each other to form a ring.
When r is 2 or more, multiple R ²⁶ may be the same or different, and adjacent R ²⁶ may be bonded to each other to form a ring.
Ar ²¹ and Ar ²² each independently represent an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent.
"-*" is the binding site.

Examples of the alkyl groups R ²¹ to R ²⁶ include linear or branched chain alkyl groups having 6 or less carbon atoms. Examples include methyl, ethyl, n-propyl, 2-propyl, n-butyl, and isobutyl groups. A methyl or ethyl group is more preferred. It is believed that when the alkyl groups R ²¹ to R ²⁶ have 6 or less carbon atoms, the crosslinking reaction is not sterically hindered, and the film formed by the polymer of this embodiment is more likely to be insolubilized.

Examples of the alkoxy group of ^R to ^R include linear or branched chain alkoxy groups having 6 or less carbon atoms. Examples include methoxy, ethoxy, n-propoxy, 2-propoxy, and n-butoxy groups. More preferably, they are methoxy or ethoxy groups. If ^R to R have ⁶ or less carbon atoms, the crosslinking reaction is not sterically hindered, and it is believed that the film formed by the polymer of this embodiment is more likely to be insolubilized.

The aromatic hydrocarbon group which may have a substituent of Ar ²¹ and Ar ²² includes, for example, a 6-membered monocyclic ring or a 2- to 5-condensed ring such as a benzene ring or a naphthalene ring, each having one free valence. A benzene ring having one free valence is particularly preferred.
Ar ²² may be a group in which two or more aromatic hydrocarbon groups, which may have a substituent, are bonded together. Examples of such groups include a biphenylene group and a terphenylene group, and a 4,4'-biphenylene group is preferred.

Examples of the aromatic heterocyclic group which may have a substituent of Ar ²¹ and Ar ²² include a 6-membered monocyclic ring or a 2- to 5-condensed ring such as a pyridine ring or a triazine ring having one free valence. A triazine ring having one free valence is particularly preferred.

The substituents which Ar ²¹ and Ar ²² may have are the same as those in the above-mentioned group Z of substituents.

As the crosslinkable group, groups that undergo a cycloaddition reaction, such as arylvinylcarbonyl groups such as cinnamoyl groups, benzocyclobutene rings having a single free valence, and 1,2-dihydrocyclobuta[a]naphthalene rings having a single free valence, are preferred in that they further improve the electrochemical stability of the element.

Among crosslinkable groups, groups containing a cyclobutene ring condensed with an aromatic ring having a single free valence and a 1,2-dihydrocyclobuta[a]naphthalene ring having a single free valence are preferred in that the structure after crosslinking is particularly stable, and among these, a benzocyclobutene ring or a 1,2-dihydrocyclobuta[a]naphthalene ring having a single free valence is even more preferred. A 1,2-dihydrocyclobuta[a]naphthalene ring having a single free valence is particularly preferred in that the crosslinking reaction temperature is low.

<Number of crosslinkable groups>
The crosslinkable groups of the polymer of the present embodiment are preferably large in number, since the polymer is sufficiently insolubilized by crosslinking and other layers can be easily formed thereon by a wet film-forming method, whereas the crosslinkable groups are preferably small in number, since the formed layer is less likely to crack, unreacted crosslinkable groups are less likely to remain, and the organic electroluminescent device is more likely to have a long life.

In the polymer of this embodiment, the number of crosslinkable groups present in one polymer chain is preferably 1 or more, more preferably 2 or more, and preferably 200 or less, more preferably 100 or less.

The number of crosslinkable groups contained in the polymer of this embodiment can be expressed as the number per 1,000 molecular weight of the polymer.
The number of crosslinkable groups possessed by the polymer of the present embodiment, expressed as the number per 1000 molecular weight of the polymer, is usually 3.0 or less, preferably 2.0 or less, and more preferably 1.0 or less, and usually 0.01 or more, and preferably 0.05 or more, per 1000 molecular weight.

When the number of crosslinkable groups is within the above range, cracks are unlikely to occur, and a flat film is easily obtained from the polymer of this embodiment. In addition, since the crosslink density is appropriate, there are few unreacted crosslinkable groups remaining in the layer after the crosslinking reaction, and the life of the obtained element is unlikely to be affected.
Furthermore, since the polymer has a sufficiently low solubility in organic solvents after the crosslinking reaction, a multi-layer laminate structure can be easily formed by a wet film-forming method.

Here, the number of crosslinkable groups per 1000 molecular weight of the polymer can be calculated from the molar ratio of the monomers charged during synthesis and the structural formula, excluding the terminal groups from the polymer.
The following will explain the case of Polymer 1 synthesized in the Examples described later.
In Polymer 1, the molecular weight of the repeating units excluding the terminal groups is 748.4 on average. The number of crosslinkable groups per repeating unit is 0.15. When calculated based on a simple proportionality, the number of crosslinkable groups per 1000 molecular weight is calculated to be 0.20.

[Repeating unit content]
In the polymer of the present embodiment, the content of the repeating unit represented by formula (1) is not particularly limited, but is usually contained in the polymer in an amount of 5 mol % or more, preferably 10 mol % or more, more preferably 15 mol % or more, and particularly preferably 20 mol % or more.

The repeating units of the polymer of this embodiment may be composed only of the repeating units represented by formula (1), but may also have a repeating unit other than formula (1) in order to balance the various performances when used as an organic electroluminescent device. In that case, the content of the repeating units represented by formula (1) in the polymer is usually 99 mol % or less, preferably 95 mol % or less.

[Preferable other repeating units that may be included]
The polymer of the present embodiment preferably further contains a repeating unit represented by any one of the following formula (3)-1, formula (3)-2, or formula (3)-3.

In formulas (3)-1 to (3)-3, ^Ar7 represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent, excluding the group containing a specific 6-membered heteroaromatic ring having a nitrogen atom, which is the structure A represented by formula (1)-2.
Q represents -C(R ⁵ )(R ⁶ )-, -N(R ⁷ )- or -C(R ¹¹ )(R ¹² )-C(R ¹³ )(R ¹⁴ )-.
R ¹ to R ⁴ each independently represent an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or an aralkyl group which may have a substituent.
R ⁵ to R ⁷ and R ¹¹ to R ¹⁴ each independently represent an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aralkyl group which may have a substituent, or an aromatic hydrocarbon group which may have a substituent.
a and b each independently represents an integer of 0 to 4.
c1 to c5 each independently represents an integer of 0 to 3.
However, at least one of c3 and c5 is an integer of 1 or more.
d1 to d4 each independently represents an integer of 1 to 4.
When a plurality of R ¹ , R ² , R ³ and R ⁴ are present in the repeating unit, R ¹ , R ² , R ³ and R ⁴ may be the same or different.

<Ar ⁷ >
In the repeating units represented by formulae (3)-1 to (3)-3, Ar ⁷ in each repeating unit independently represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent, excluding structure A represented by formula (1)-2 which contains a group containing a specific 6-membered heteroaromatic ring having a nitrogen atom in the present invention.

The aromatic hydrocarbon group preferably has 6 or more and 60 or less carbon atoms, and specific examples include a 6-membered monocyclic ring or a 2-5 condensed ring such as a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, or a fluorene ring, or a monovalent group in which multiple of these are linked together.

The aromatic heterocyclic group preferably has 3 or more and 60 or less carbon atoms. Specific examples of the aromatic heterocyclic group include a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, a carbazole ring, a pyrroloimidazole ring, a pyrrolopyrazole ring, a pyrrolopyrrole ring, a thienopyrrole ring, a thienothiophene ring, a furopyrrole ring, a furofuran ring, a thienofuran ring, a benzisoxazole ring, a benzisothiazole ring, a benzimidazole ring, a pyrazine ring, a pyridazine ring, a quinoline ring, an isoquinoline ring, a cinnoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, an azulene ring, and the like. These may be monocyclic or condensed rings having 5 to 6 members, or monovalent groups having multiple connected rings.

Ar ⁷ is preferably an aromatic hydrocarbon group which may have a substituent, from the viewpoints of excellent charge transportability and durability. Among them, a monovalent group of a benzene ring or fluorene ring which may have a substituent, i.e., a phenyl group or a fluorenyl group which may have a substituent, is more preferable, a fluorenyl group which may have a substituent, is further preferable, and a 2-fluorenyl group which may have a substituent is particularly preferable.

The substituent that the aromatic hydrocarbon group of ^Ar7 may have is not particularly limited as long as it does not significantly impair the properties of the polymer of this embodiment. Preferred examples include groups selected from the above-mentioned substituent group Z or the above-mentioned crosslinkable groups, and are preferably an alkyl group, an alkoxy group, an aromatic hydrocarbon group, an aromatic heterocyclic group other than a specific 6-membered heteroaromatic ring having a nitrogen atom, or the above-mentioned crosslinkable groups, and more preferably an alkyl group.

From the viewpoint of solubility in a coating solvent, Ar ⁷ is preferably a fluorenyl group substituted with an alkyl group having 1 to 24 carbon atoms, and more preferably a 2-fluorenyl group substituted with an alkyl group having 4 to 12 carbon atoms. Furthermore, a 9-alkyl-2-fluorenyl group in which an alkyl group is substituted at the 9-position of the 2-fluorenyl group is preferred, and more preferably a 9,9'-dialkyl-2-fluorenyl group in which two alkyl groups are substituted.
When Ar7 is a fluorenyl group substituted with an alkyl group at least at the 9-position and the 9'-position, the solubility in a solvent and the durability of the fluorene ring are easily improved. Furthermore, when ^Ar7 is a fluorenyl group substituted with an alkyl group at both the 9-position and the 9'-position, the solubility in a solvent and the durability of the fluorene ring are easily further improved.
It is preferable that Ar ⁷ contains the above-mentioned crosslinkable group, since this improves the insolubility in a solvent during lamination coating after film formation.

From the viewpoint of insolubilization, the polymer of the present embodiment preferably contains, as a further substituent, a repeating unit represented by formula (3)-1 to formula (3)-3 containing at least one of the above-mentioned crosslinkable groups, and it is preferable that the crosslinkable group is further substituted with a substituent that the aromatic hydrocarbon group represented by ^Ar7 may have.

<Specific examples>
Specific examples of the repeating unit structures represented by formula (3)-1 to formula (3)-3 include the following structures.

[Other repeating units]
The polymer of the present embodiment may further contain a repeating unit represented by the following formula (4) or (5) in terms of charge transport properties and durability.

In formula (4), ^R8 and ^R9 each independently represent a hydrogen atom, an alkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent.

In formula (5), Ar ¹⁰ represents a divalent aromatic hydrocarbon group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or a divalent group in which two or more groups selected from a divalent aromatic hydrocarbon group which may have a substituent and a divalent aromatic heterocyclic group which may have a substituent are linked together directly or via a linking group.

< ^R8 and ^R9 >
Examples of the alkyl group, aromatic hydrocarbon group, and aromatic heterocyclic group of ^R8 and ^R9 include the alkyl group, aromatic hydrocarbon group, and aromatic heterocyclic group exemplified as the substituent group Z. The substituents that these groups may have are preferably the same as those in the substituent group Z or the crosslinkable group.

<Ar ¹⁰ >
Specific examples of the structure of Ar ¹⁰ include divalent groups similar to those of Ar ² in the formula (1). The substituents which these groups may have are preferably the same as those in the substituent group Z or the crosslinkable group.

[Molecular weight of polymer]
The weight average molecular weight (Mw) of the polymer of the present embodiment is usually 3,000,000 or less, preferably 1,000,000 or less, more preferably 500,000 or less, even more preferably 200,000 or less, and particularly preferably 100,000 or less. The weight average molecular weight (Mw) of the polymer of the present embodiment is usually 10,000 or more, preferably 15,000 or more.

When the weight average molecular weight of the polymer is equal to or less than the above upper limit, the polymer tends to have good solubility in a solvent and excellent film-forming properties.
When the weight average molecular weight of the polymer is equal to or more than the lower limit, the decrease in the glass transition temperature, melting point, and vaporization temperature of the polymer is suppressed, and the heat resistance may be improved. In addition, the coating film after the crosslinking reaction may have sufficient insolubility in organic solvents.

The number average molecular weight (Mn) of the polymer of this embodiment is usually 2,500,000 or less, preferably 750,000 or less, more preferably 400,000 or less, and particularly preferably 100,000 or less. The number average molecular weight (Mn) of the polymer of this embodiment is usually 2,000 or more, preferably 4,000 or more, more preferably 8,000 or more, and even more preferably 20,000 or more.

The dispersity (Mw/Mn) of the polymer of this embodiment is preferably 3.5 or less, more preferably 2.5 or less, and particularly preferably 2.0 or less. Since the smaller the dispersity value, the better, the lower limit is ideally 1.
When the dispersity of the polymer is equal to or less than the above upper limit, purification is easy, and the solubility in a solvent and the charge transporting ability are good.

Usually, the weight average molecular weight and number average molecular weight of a polymer are determined by SEC (size exclusion chromatography) measurement. In SEC measurement, the higher the molecular weight component, the shorter the elution time, and the lower the molecular weight component, the longer the elution time. However, the weight average molecular weight and number average molecular weight are calculated by converting the elution time of the sample into molecular weight using a calibration curve calculated from the elution time of polystyrene (standard sample) with a known molecular weight.

[Preferred Polymers]
The polymer of the present embodiment is most preferably represented by any one of the following formulas (6a) to (6o).

In each of the polymers of formulas (6a) to (6o), A, Q, R ¹ , R ² , R ³ and R ⁴ are the same as those in formulas (2)-1 to (2)-3. Ar ⁷ is the same as those in formulas (3)-1 to (3)-3. It is preferable that at least one of A or Ar ⁷ in each polymer has the above-mentioned crosslinkable group. n and m represent the number of repetitions.

[Specific examples]
Specific examples of the polymer of this embodiment other than the polymers synthesized in the examples described later and the polymers used in the examples are shown below. The polymer of this embodiment is not limited to these. The numbers in the chemical formulas represent the molar ratio of the repeating units.
These polymers may be any of random copolymers, alternating copolymers, block copolymers, graft copolymers, etc., and the arrangement order of the repeating units is not limited.

[Method of producing polymer]
The method for producing the polymer of the present embodiment is not particularly limited. For example, the polymer can be produced by a polymerization method using the Suzuki reaction, a polymerization method using the Grignard reaction, a polymerization method using the Yamamoto reaction, a polymerization method using the Ullmann reaction, a polymerization method using the Buchwald-Hartwig reaction, or the like.

In the case of the polymerization method using the Ullmann reaction and the polymerization method using the Buchwald-Hartwig reaction, for example, an aryl dihalide represented by the following formula (1a) (E represents a halogen atom such as I, Br, Cl, F, etc.) is reacted with a primary aminoaryl represented by formula (1b), and then further reacted with an aryl dihalide represented by formula (2a), thereby synthesizing the polymer of this embodiment.

In the above formula, A, R ¹ to R ² , Q, a, b, c1 and d1 are defined as in the above formulas (2)-1 to (2)-3, and n and m represent the number of repetitions.

In the above polymerization method, the reaction to form the N-aryl bond is usually carried out in the presence of a base such as potassium carbonate, sodium tert-butoxide, or triethylamine. It can also be carried out in the presence of a transition metal catalyst such as a copper or palladium complex.

[Organic electroluminescence element material]
The polymer of the present embodiment can be particularly suitably used as a material for an organic electroluminescent device. That is, the polymer of the present embodiment is preferably a material for an organic electroluminescent device.

The polymer of this embodiment is usually suitable for use in forming a layer between an anode and a light-emitting layer in an organic electroluminescent device. That is, the polymer of this embodiment is preferably used as a material for forming at least one of a hole injection layer and a hole transport layer, that is, as a charge transport material. By using the polymer of this embodiment in the hole injection layer or the hole transport layer, a layer having high charge transportability to the light-emitting layer and high durability against electrons leaked from the light-emitting layer can be provided between the anode and the light-emitting layer.
When used as a charge transporting material, the polymer of this embodiment may be used alone or in any combination of two or more kinds in any ratio.

When the polymer of this embodiment is used to form at least one of the hole injection layer and the hole transport layer of an organic electroluminescent device, the content of the polymer of this embodiment in the hole injection layer or the hole transport layer is usually 1 to 100% by weight, preferably 5 to 100% by weight, and more preferably 10 to 100% by weight. The above range is preferable because it improves the charge transport property of the hole injection layer or the hole transport layer, reduces the driving voltage, and improves driving stability.

When the content of the polymer of this embodiment in the hole injection layer or hole transport layer is not 100% by weight, other components constituting the hole injection layer or hole transport layer include the hole transport compound described below.

Since organic electroluminescent devices can be easily manufactured, the polymer of this embodiment is preferably used in an organic layer formed by a wet film-forming method.

[Composition for organic electroluminescent device]
The composition for organic electroluminescent elements of the present embodiment contains the polymer of the present embodiment. The composition for organic electroluminescent elements of the present embodiment may contain one type of the above polymer, or may contain two or more types of the above polymers in any combination and in any ratio.

[Polymer content]
The content of the polymer in the composition for organic electroluminescent elements of this embodiment is usually 0.01 to 70% by weight, preferably 0.1 to 60% by weight, and more preferably 0.5 to 50% by weight.
Within the above range, defects are unlikely to occur in the formed organic layer, and unevenness in the film thickness is unlikely to occur, which is preferable.
The composition for organic electroluminescent elements of the present embodiment may contain a solvent and the like in addition to the polymer.

[solvent]
The composition for organic electroluminescent elements of the present embodiment usually contains a solvent. The solvent is preferably one that dissolves the above-mentioned polymer. Specifically, a solvent that dissolves the above-mentioned polymer at room temperature in an amount of usually 0.05% by weight or more, preferably 0.5% by weight or more, and more preferably 1% by weight or more is suitable.

Specific examples of the solvent include organic solvents such as aromatic solvents such as toluene, xylene, mesitylene, and cyclohexylbenzene; halogen-containing solvents such as 1,2-dichloroethane, chlorobenzene, and o-dichlorobenzene; ether solvents such as aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA), and aromatic ethers such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, and 2,4-dimethylanisole; aliphatic ester solvents such as ethyl acetate, n-butyl acetate, ethyl lactate, and n-butyl lactate; and ester solvents such as aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, isopropyl benzoate, propyl benzoate, and n-butyl benzoate; and other organic solvents used in the hole injection layer forming composition and hole transport layer forming composition described below.

One type of solvent may be used, or two or more types may be used in any combination and in any ratio.

In particular, the solvent contained in the composition for organic electroluminescent elements of this embodiment is preferably a solvent having a surface tension at 20°C of typically less than 40 dyn/cm, preferably 36 dyn/cm or less, and more preferably 33 dyn/cm or less.

When forming a coating film by a wet film-forming method using the composition for organic electroluminescent elements of this embodiment and crosslinking the polymer to form an organic layer, it is preferable that the affinity between the solvent and the base is high. This is because the uniformity of the film quality greatly affects the uniformity and stability of the light emission of the organic electroluminescent element. Therefore, the composition for organic electroluminescent elements used in the wet film-forming method is required to have a low surface tension so that a coating film with high leveling properties and uniformity can be formed. Therefore, by using a solvent having such a low surface tension, a uniform layer containing the above-mentioned polymer can be formed, and thus a uniform crosslinked layer can be formed, which is preferable.

Specific examples of low surface tension solvents include aromatic solvents such as toluene, xylene, mesitylene, cyclohexylbenzene, etc., ester solvents such as ethyl benzoate, ether solvents such as anisole, trifluoromethoxyanisole, pentafluoromethoxybenzene, 3-(trifluoromethyl)anisole, ethyl (pentafluorobenzoate), etc.

The solvent contained in the composition for organic electroluminescent elements of this embodiment has a vapor pressure of usually 10 mmHg or less, preferably 5 mmHg or less, and usually 0.1 mmHg or more at 25° C. By using such a solvent, it is possible to prepare a composition for organic electroluminescent elements that is suitable for the process of producing an organic electroluminescent element by a wet film-forming method and that is suited to the properties of the polymer of this embodiment.
Specific examples of such solvents include the above-mentioned aromatic solvents such as toluene, xylene, and mesitylene, ether solvents, and ester solvents.

Moisture can cause performance degradation of organic electroluminescent devices, particularly promoting a decrease in brightness during continuous operation. In order to reduce residual moisture during wet film formation as much as possible, among the above solvents, those with a water solubility of 1% by weight or less at 25°C are preferred, and those with a water solubility of 0.1% by weight or less are more preferred.

The content of the solvent contained in the composition for organic electroluminescent elements of this embodiment is usually 10% by weight or more, preferably 30% by weight or more, and particularly preferably 50% by weight or more. By having the content of the solvent be equal to or more than the above lower limit, the flatness and uniformity of the layer formed can be improved.

[Electron Acceptor Compound]
From the viewpoint of reducing resistance, the composition for organic electroluminescent elements of the present embodiment preferably further contains an electron-accepting compound. In particular, when the composition for organic electroluminescent elements of the present embodiment is used for forming a hole injection layer, it preferably contains an electron-accepting compound.

As the electron-accepting compound, a compound having an oxidizing power and the ability to accept one electron from the polymer is preferred. Specifically, a compound having an electron affinity of 4 eV or more is preferred, and a compound having an electron affinity of 5 eV or more is more preferred.

Examples of such electron-accepting compounds include one or more compounds selected from the group consisting of triarylboron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of arylamines and metal halides, and salts of arylamines and Lewis acids.

Specific examples include onium salts substituted with organic groups, such as 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate and triphenylsulfonium tetrafluoroborate (WO 2005/089024), (WO 2017/164268); high-valent inorganic compounds such as iron(III) chloride (JP 11-251067 A) and ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene; aromatic boron compounds such as tris(pentafluorophenyl)borane (JP 2003-31365 A); fullerene derivatives, and iodine.

The composition for organic electroluminescent devices of this embodiment may contain a single type of electron-accepting compound as described above, or may contain two or more types in any combination and ratio.

When the composition for organic electroluminescent elements of this embodiment contains an electron-accepting compound, the content of the electron-accepting compound is usually 0.0005% by weight or more, preferably 0.001% by weight or more, and usually 20% by weight or less, preferably 10% by weight or less. The ratio of the electron-accepting compound to the above polymer in the composition for organic electroluminescent elements is usually 0.5% by weight or more, preferably 1% by weight or more, more preferably 3% by weight or more, and usually 80% by weight or less, preferably 60% by weight or less, and even more preferably 40% by weight or less.

It is preferable that the content of the electron-accepting compound in the composition for organic electroluminescent elements is equal to or greater than the above lower limit, because the electron acceptor accepts electrons from the polymer, and the resistance of the formed organic layer is reduced. It is preferable that the content of the electron-accepting compound in the composition for organic electroluminescent elements is equal to or less than the above upper limit, because defects are less likely to occur in the formed organic layer, and film thickness unevenness is less likely to occur.

[Cation Radical Compound]
The composition for organic electroluminescent elements of the present embodiment may further contain a cation radical compound.

As the cation radical compound, an ionic compound consisting of a cation radical, which is a chemical species obtained by removing one electron from a hole-transporting compound, and a counter anion is preferred. When the cation radical is derived from a hole-transporting polymer compound, the cation radical has a structure in which one electron has been removed from the repeating unit of the polymer compound.

The cation radical is preferably a chemical species obtained by removing one electron from a hole transport compound described below. A chemical species obtained by removing one electron from a compound preferred as a hole transport compound is preferable in terms of amorphousness, visible light transmittance, heat resistance, solubility, etc.

Here, the cation radical compound can be generated by mixing the hole transport compound described below with the electron acceptor compound described above. That is, by mixing the hole transport compound with the electron acceptor compound, electrons are transferred from the hole transport compound to the electron acceptor compound, and a cation ion compound consisting of the cation radical of the hole transport compound and a counter anion is generated.

When the composition for organic electroluminescent elements of this embodiment contains a cation radical compound, the content of the cation radical compound in the composition for organic electroluminescent elements is usually 0.0005% by weight or more, preferably 0.001% by weight or more, and usually 40% by weight or less, preferably 20% by weight or less. If the content of the cation radical compound is equal to or more than the above lower limit, the resistance of the formed organic layer is reduced, which is preferable. If the content of the cation radical compound is equal to or less than the above upper limit, the formed organic layer is less likely to have defects and is less likely to have uneven thickness, which is preferable.

In addition to the above components, the composition for organic electroluminescent elements of this embodiment may contain components contained in the composition for forming a hole injection layer or the composition for forming a hole transport layer described below in the amounts described below.

[Light Emitting Layer Material]
In an organic electroluminescent device in which the polymer according to an embodiment of the present invention is used as a charge transporting material forming at least one of a hole injection layer and a hole transport layer, the light emitting layer contains a light emitting material and a host material.

The luminescent material may be a phosphorescent material or a fluorescent material.

[Phosphorescent layer]
In an organic electroluminescent device in which the polymer according to an embodiment of the present invention is used as a charge transport material forming at least one of a hole injection layer and a hole transport layer, when the light emitting layer is a phosphorescent light emitting layer, the following materials are preferable as the phosphorescent light emitting material.

<Phosphorescent Material>
The phosphorescent material is a material that emits light from an excited triplet state. Representative examples of the phosphorescent material include metal complex compounds containing Ir, Pt, Eu, etc., and the material preferably has a structure containing a metal complex.

Among metal complexes, examples of phosphorescent organometallic complexes that emit light via a triplet state include Werner-type complexes or organometallic complex compounds that contain a metal selected from Groups 7 to 11 of the long-form periodic table (hereinafter, unless otherwise noted, "periodic table" refers to the long-form periodic table) as a central metal. As such phosphorescent materials, compounds represented by the following formula (201) or compounds represented by formula (205) shown below are preferred, and compounds represented by the following formula (201) are more preferred.

[Compound represented by formula (201)]

In formula (201), ring A1 represents an aromatic hydrocarbon ring structure which may have a substituent or an aromatic heterocyclic structure which may have a substituent.
Ring A2 represents an aromatic heterocyclic structure which may have a substituent.
R ²⁰¹ and R ²⁰² each independently represent a structure represented by formula (202). "*" represents a bonding site with ring A1 or ring A2. R ²⁰¹ and R ²⁰² may be the same or different, and when a plurality of R ²⁰¹ and R ²⁰² are present, they may be the same or different.
Ar ²⁰¹ and Ar ²⁰³ each independently represent an aromatic hydrocarbon structure which may have a substituent, or an aromatic heterocyclic structure which may have a substituent.
Ar ²⁰² represents an aromatic hydrocarbon structure which may have a substituent, an aromatic heterocyclic structure which may have a substituent, or an aliphatic hydrocarbon structure which may have a substituent.
The substituents bonded to ring A1, the substituents bonded to ring A2, or the substituents bonded to ring A1 and the substituents bonded to ring A2 may be bonded to each other to form a ring.
B ²⁰¹ -L ²⁰⁰ -B ²⁰² represents an anionic bidentate ligand. B ²⁰¹ and B ²⁰² each independently represent a carbon atom, an oxygen atom, or a nitrogen atom, and these atoms may be atoms constituting a ring. L ²⁰⁰ represents a single bond, or an atomic group constituting a bidentate ligand together with B ²⁰¹ and B ^202. When a plurality of ^{B 201} -L ²⁰⁰ -B ²⁰² are present, they may be the same or different.
i1 and i2 each independently represent an integer of 0 to 12.
i3 is an integer of 0 or more, the upper limit of which is the number that can be substituted for Ar ²⁰² .
j1 is an integer of 0 or more, the upper limit of which is the number that can be substituted for Ar ²⁰¹ .
k1 and k2 each independently represent an integer of 0 or more, which is the upper limit of the number of substitutions that can be made on ring A1 and ring A2.
m1 is an integer from 1 to 3.

Unless otherwise specified, the above substituents are preferably groups selected from the following substituent group Z'.

<Substituent Group Z'>
Alkyl groups: preferably alkyl groups having 1 to 20 carbon atoms, more preferably alkyl groups having 1 to 12 carbon atoms, even more preferably alkyl groups having 1 to 8 carbon atoms, and particularly preferably alkyl groups having 1 to 6 carbon atoms; Alkoxy groups: preferably alkoxy groups having 1 to 20 carbon atoms, more preferably alkoxy groups having 1 to 12 carbon atoms, and even more preferably alkoxy groups having 1 to 6 carbon atoms; Aryloxy groups: preferably aryloxy groups having 6 to 20 carbon atoms, more preferably aryloxy groups having 6 to 14 carbon atoms, even more preferably aryloxy groups having 6 to 12 carbon atoms, and especially preferably aryloxy groups having 6 carbon atoms; Heteroaryloxy groups: preferably carbon heteroaryloxy groups having 3 to 20 carbon atoms, more preferably heteroaryloxy groups having 3 to 12 carbon atoms; alkylamino groups: preferably alkylamino groups having 1 to 20 carbon atoms, more preferably alkylamino groups having 1 to 12 carbon atoms; arylamino groups: preferably arylamino groups having 6 to 36 carbon atoms, more preferably arylamino groups having 6 to 24 carbon atoms; aralkyl groups: preferably aralkyl groups having 7 to 40 carbon atoms, more preferably aralkyl groups having 7 to 18 carbon atoms, even more preferably aralkyl groups having 7 to 12 carbon atoms; heteroaralkyl groups: preferably heteroaralkyl groups having 4 to 40 carbon atoms, more preferably heteroaralkyl groups having 4 to 18 carbon atoms. Aralkyl groups; Alkenyl groups: preferably an alkenyl group having 2 to 20 carbon atoms, more preferably an alkenyl group having 2 to 12 carbon atoms, even more preferably an alkenyl group having 2 to 8 carbon atoms, and particularly preferably an alkenyl group having 2 to 6 carbon atoms; Alkinyl groups: preferably an alkynyl group having 2 to 20 carbon atoms, more preferably an alkynyl group having 2 to 12 carbon atoms; Aryl groups: preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 24 carbon atoms, even more preferably an aryl group having 6 to 18 carbon atoms, and particularly preferably an aryl group having 6 to 14 carbon atoms; Heteroaryl groups: preferably a heteroaryl group having 3 to 30 carbon atoms, more preferably a a heteroaryl group having 3 to 24 carbon atoms, more preferably a heteroaryl group having 3 to 18 carbon atoms, and particularly preferably a heteroaryl group having 3 to 14 carbon atoms; an alkylsilyl group: preferably an alkylsilyl group having 1 to 20 carbon atoms in the alkyl group, and more preferably an alkylsilyl group having 1 to 12 carbon atoms in the alkyl group; an arylsilyl group: preferably an arylsilyl group having 6 to 20 carbon atoms in the aryl group, and more preferably an arylsilyl group having 6 to 14 carbon atoms in the aryl group; an alkylcarbonyl group: preferably an alkylcarbonyl group having 2 to 20 carbon atoms; an arylcarbonyl group: preferably an arylcarbonyl group having 7 to 20 carbon atoms. In the above substituents, one or more hydrogen atoms may be replaced by a fluorine atom, or one or more hydrogen atoms may be replaced by a deuterium atom.
Unless otherwise specified, an aryl group is an aromatic hydrocarbon group, and a heteroaryl group is an aromatic heterocyclic group.
- Hydrogen atom, deuterium atom, fluorine atom, cyano group, or _-SF5

Preferred groups in the substituent group Z' include the following.
Preferred are alkyl groups, alkoxy groups, aryloxy groups, arylamino groups, aralkyl groups, alkenyl groups, aryl groups, heteroaryl groups, alkylsilyl groups, arylsilyl groups, groups in which one or more hydrogen atoms of these groups are replaced with fluorine atoms, fluorine atoms, cyano groups, and _--SF.sub.5 .
More preferred are alkyl groups, alkoxy groups, aryloxy groups, arylamino groups, aralkyl groups, alkenyl groups, aryl groups, heteroaryl groups, groups in which one or more hydrogen atoms of these groups are replaced with fluorine atoms, fluorine atoms, cyano groups, and _--SF.sub.5 .
More preferred are an alkyl group, an alkoxy group, an aryloxy group, an arylamino group, an aralkyl group, an alkenyl group, an aryl group, and a heteroaryl group.
Particularly preferred are an alkyl group, an arylamino group, an aralkyl group, an alkenyl group, an aryl group, and a heteroaryl group.
Most preferred are an alkyl group, an arylamino group, an aralkyl group, an aryl group and a heteroaryl group.

These substituent groups Z' may further have a substituent selected from the substituent group Z' as a substituent. The preferred groups, more preferred groups, even more preferred groups, particularly preferred groups, and most preferred groups of the substituents that may be had are the same as the preferred groups in the substituent group Z'.

<Ring A1>
Ring A1 represents an aromatic hydrocarbon ring structure which may have a substituent or an aromatic heterocyclic structure which may have a substituent.

The aromatic hydrocarbon ring of ring A1 is preferably an aromatic hydrocarbon ring having a carbon number of 6 to 30. Specifically, a benzene ring, a naphthalene ring, an anthracene ring, a triphenylyl ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring are preferred.
The aromatic heterocycle of Ring A1 is preferably an aromatic heterocycle having 3 to 30 carbon atoms containing a nitrogen atom, an oxygen atom, or a sulfur atom as a heteroatom, and more preferably a furan ring, a benzofuran ring, a thiophene ring, or a benzothiophene ring.
Ring A1 is more preferably a benzene ring, a naphthalene ring, or a fluorene ring, particularly preferably a benzene ring or a fluorene ring, and most preferably a benzene ring.

<Ring A2>
Ring A2 represents an aromatic heterocyclic structure which may have a substituent.

The aromatic heterocycle of ring A2 is preferably an aromatic heterocycle having 3 to 30 carbon atoms and containing a nitrogen atom, an oxygen atom, or a sulfur atom as a heteroatom. Specific examples include a pyridine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, an imidazole ring, an oxazole ring, a thiazole ring, a benzothiazole ring, a benzoxazole ring, a benzimidazole ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, a quinazoline ring, a naphthyridine ring, and a phenanthridine ring. More preferred are a pyridine ring, a pyrazine ring, a pyrimidine ring, an imidazole ring, a benzothiazole ring, a benzoxazole ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, and a quinazoline ring. Even more preferred are a pyridine ring, an imidazole ring, a benzothiazole ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, and a quinazoline ring. Most preferred are a pyridine ring, an imidazole ring, a benzothiazole ring, a quinoline ring, a quinoxaline ring and a quinazoline ring.

<Combination of Ring A1 and Ring A2>
Preferred combinations of ring A1 and ring A2, expressed as (ring A1-ring A2), include (benzene ring-pyridine ring), (benzene ring-quinoline ring), (benzene ring-quinoxaline ring), (benzene ring-quinazoline ring), (benzene ring-imidazole ring) and (benzene ring-benzothiazole ring).

<Substituents of Ring A1 and Ring A2>
The substituents which the ring A1 and the ring A2 may have can be arbitrarily selected, but are preferably one or more kinds of substituents selected from the above-mentioned substituent group Z'.

<Ar ²⁰¹ , Ar ²⁰² , Ar ²⁰³ >
Ar ²⁰¹ and Ar ²⁰³ each independently represent an aromatic hydrocarbon ring structure which may have a substituent, or an aromatic heterocyclic structure which may have a substituent.

Ar ²⁰² represents an aromatic hydrocarbon ring structure which may have a substituent, an aromatic heterocyclic structure which may have a substituent, or an aliphatic hydrocarbon structure which may have a substituent.

<Aromatic Hydrocarbon Rings of Ar ²⁰¹ , Ar ²⁰² and Ar ²⁰³ >
When any of Ar ²⁰¹ , Ar ²⁰² , and Ar ²⁰³ is an aromatic hydrocarbon structure which may have a substituent, the aromatic hydrocarbon structure is preferably an aromatic hydrocarbon ring having a carbon number of 6 to 30. Specific examples include a benzene ring, a naphthalene ring, an anthracene ring, a triphenylyl ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring, more preferably a benzene ring, a naphthalene ring, or a fluorene ring, and most preferably a benzene ring.

<9,9' positions of fluorene>
When any of Ar ²⁰¹ , Ar ²⁰² and Ar ²⁰³ is a fluorene ring which may have a substituent, the 9- and 9'-positions of the fluorene ring preferably have a substituent or are bonded to an adjacent structure.

<o-, m-phenylene>
When either Ar ²⁰¹ or Ar ²⁰² is a benzene ring which may have a substituent, it is preferable that at least one benzene ring is bonded to an adjacent structure at an ortho position or a meta position, and it is more preferable that at least one benzene ring is bonded to an adjacent structure at a meta position.

<Aromatic heterocycles represented by Ar ²⁰¹ , Ar ²⁰² and Ar ²⁰³ >
When any one of Ar ²⁰¹ , Ar ²⁰² and Ar ²⁰³ is an aromatic heterocyclic structure which may have a substituent, the aromatic heterocyclic structure is preferably an aromatic heterocyclic ring having 3 to 30 carbon atoms and containing any one of a nitrogen atom, an oxygen atom or a sulfur atom as a heteroatom. Specific examples include a pyridine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, an imidazole ring, an oxazole ring, a thiazole ring, a benzothiazole ring, a benzoxazole ring, a benzimidazole ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, a quinazoline ring, a naphthyridine ring, a phenanthridine ring, a carbazole ring, a dibenzofuran ring and a dibenzothiophene ring, and more preferably a pyridine ring, a pyrimidine ring, a triazine ring, a carbazole ring, a dibenzofuran ring and a dibenzothiophene ring.

<N-position of carbazole>
When any of Ar ²⁰¹ , Ar ²⁰² and Ar ²⁰³ is a carbazole ring which may have a substituent, the N-position of the carbazole ring preferably has a substituent or is bonded to an adjacent structure.

<Aliphatic hydrocarbons of Ar ²⁰² >
When Ar ²⁰² is an aliphatic hydrocarbon structure which may have a substituent, it is an aliphatic hydrocarbon structure having a straight chain, branched chain, or cyclic structure, and the number of carbon atoms is preferably 1 or more and 24 or less, more preferably 1 or more and 12 or less, and even more preferably 1 or more and 8 or less.

<i1, i2, i3, j1, k1, k2>
<Preferable ranges of i1 and i2>
i1 represents an integer of 0 to 12, preferably an integer of 1 to 12, more preferably an integer of 1 to 8, and further preferably an integer of 1 to 6. By being in this range, the solubility and charge transportability can be improved. It is expected.

<Preferable range of i3>
i3 preferably represents an integer of 0 to 5, more preferably 0 to 2, and further preferably 0 or 1.

<Preferable range of j1>
j1 preferably represents an integer of 0 to 2, and more preferably 0 or 1.

<Preferable Ranges of k1 and k2>
k1 and k2 each represent an integer of preferably 0 to 3, more preferably 1 to 3, further preferably 1 or 2, and particularly preferably 1.

<Preferable Substituents for Ar ²⁰¹ , Ar ²⁰² and Ar ²⁰³ >
The substituents that Ar ²⁰¹ , Ar ²⁰² , and Ar ²⁰³ may have can be arbitrarily selected, but are preferably one or more substituents selected from the above-mentioned substituent group Z'. The preferred groups are also the same as those in the above-mentioned substituent group Z', but are more preferably a hydrogen atom, an alkyl group, or an aryl group, particularly preferably a hydrogen atom or an alkyl group, and most preferably unsubstituted (hydrogen atom).

<Preferred structure of formula (201)>
Among the compounds represented by formula (201), a compound having the following structure is preferred.

<Phenylene linkage>)
A structure having groups linked to benzene rings.
That is, Ar ²⁰¹ is a benzene ring structure, i1 is 1 to 6, and at least one of the benzene rings is bonded to an adjacent structure at the ortho-position or meta-position.
This structure is expected to improve the solubility and charge transport properties.

<(phenylene)-(aralkyl)-(alkyl)>
A structure having an aromatic hydrocarbon group or aromatic heterocyclic group to which an alkyl group or an aralkyl group is bonded in the ring A1 or the ring A2.
That is, Ar ²⁰¹ is an aromatic hydrocarbon structure or an aromatic heterocyclic structure; i1 is 1 to 6; Ar ²⁰² is an aliphatic hydrocarbon structure; i2 is 1 to 12, preferably 3 to 8; Ar ²⁰³ is a benzene ring structure; and i3 is 0 or 1.
Ar ²⁰¹ is preferably the aromatic hydrocarbon structure, more preferably a structure in which 1 to 5 benzene rings are linked, and even more preferably a structure in which there is one benzene ring.
This structure is expected to improve the solubility and charge transport properties.

<Dendron>
A structure in which a dendron is bonded to ring A1 or ring A2.
For example, Ar and Ar ²⁰² are benzene ring structures, Ar ²⁰³ is a biphenyl or terphenyl structure, i1 and i2 are 1 to 6, i3 is 2, and j is 2.
This structure is expected to improve the solubility and charge transport properties.

<B ²⁰¹ -L ²⁰⁰ -B ²⁰² >
B ²⁰¹ -L ²⁰⁰ -B ²⁰² represent an anionic bidentate ligand. B ²⁰¹ and B ²⁰² each independently represent a carbon atom, an oxygen atom or a nitrogen atom, and these atoms form a ring. L ²⁰⁰ represents a single bond or an atomic group constituting a bidentate ligand together with B ²⁰¹ and B ^202. When a plurality of B ²⁰¹ -L ²⁰⁰ -B ²⁰² are present, They may be the same or different.

The structure represented by B ²⁰¹ -L ²⁰⁰ -B ²⁰² is preferably a structure represented by the following formula (203) or (204).

In formula (203), R ²¹¹ , R ²¹² and R ²¹³ each represent a substituent.

In formula (204), ring B3 represents an aromatic heterocyclic structure containing a nitrogen atom, which may have a substituent. Ring B3 is preferably a pyridine ring.

<Preferred phosphorescent material represented by formula (201)>
The phosphorescent material represented by formula (201) is not particularly limited, but specific examples include the following structures: In the following, "Ph" represents a "phenyl group" and "Me" represents a "methyl group".

[Compound represented by formula (205)]

In formula (205), ^M2 represents a metal. T represents a carbon atom or a nitrogen atom. ^R92 to ^R95 each independently represent a substituent. When T is a nitrogen atom, ^R94 and ^R95 are absent.

In formula (205), ^M2 represents a metal. Specific examples include metals selected from Groups 7 to 11 of the periodic table. Among these, preferred are ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold, and particularly preferred are divalent metals such as platinum and palladium.

In formula (205), R ⁹² and R ⁹³ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, a cyano group, an amino group, an acyl group, an alkoxycarbonyl group, a carboxyl group, 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.

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 .
When T is a nitrogen atom, R ⁹⁴ or R ⁹⁵ directly bonded to said T does not exist.

R ⁹² to R ⁹⁵ may further have a substituent. The substituent may be the same as those mentioned above.
Any two or more groups among R ⁹² to R ⁹⁵ may be bonded to each other to form a ring.

<Molecular Weight of Phosphorescent Material>
The molecular weight of the phosphorescent material is preferably not more than 5000, more preferably not more than 4000, and particularly preferably not more than 3000. The molecular weight of the phosphorescent material is usually not less than 800, preferably not less than 1000, and more preferably not less than 1200. It is believed that by having the molecular weight within this range, the phosphorescent materials do not aggregate with each other and can be uniformly mixed with the charge transport material, thereby making it possible to obtain a light-emitting layer with high luminous efficiency.

It is preferable that the molecular weight of the phosphorescent material is large in that it has a high Tg, melting point, decomposition temperature, etc., and that the phosphorescent material and the formed light-emitting layer have excellent heat resistance, and that deterioration of film quality due to gas generation, recrystallization, molecular migration, etc., and an increase in impurity concentration due to thermal decomposition of the material, etc., are unlikely to occur. On the other hand, it is preferable that the molecular weight of the phosphorescent material is small in that it is easy to purify the organic compound.

[Host material for phosphorescent light-emitting layer]
In an organic electroluminescent device using the polymer according to one embodiment of the present invention as a charge transporting material forming at least one of a hole injection layer and a hole transport layer, when the light emitting layer is a phosphorescent material, it is preferable that the host material contains the following material.

The host material of the light-emitting layer is a material having a skeleton with excellent charge transport properties, and is preferably selected from electron transport materials, hole transport materials, and bipolar materials capable of transporting both electrons and holes.

<Structure with excellent charge transport properties>
Specific examples of skeletons having excellent charge transport properties include an aromatic structure, an aromatic amine structure, a triarylamine structure, a dibenzofuran structure, a naphthalene structure, a phenanthrene structure, a phthalocyanine structure, a porphyrin structure, a thiophene structure, a benzylphenyl structure, a fluorene structure, a quinacridone structure, a triphenylene structure, a carbazole structure, a pyrene structure, an anthracene structure, a phenanthroline structure, a quinoline structure, a pyridine structure, a pyrimidine structure, a triazine structure, an oxadiazole structure, and an imidazole structure.

<Electron Transporting Material>
As the electron transporting material, from the viewpoint of a material having excellent electron transporting properties and a relatively stable structure, a compound having a pyridine structure, a pyrimidine structure, or a triazine structure is more preferable, and a compound having a pyrimidine structure or a triazine structure is further preferable.

<Hole Transport Material>
The hole transport material is a compound having a structure excellent in hole transportability. Among the central skeletons excellent in charge transportability, a carbazole structure, a dibenzofuran structure, a triarylamine structure, a naphthalene structure, a phenanthrene structure, or a pyrene structure is preferable as a structure excellent in hole transportability, and a carbazole structure, a dibenzofuran structure, or a triarylamine structure is more preferable.

<Three or more condensed ring structures>
The host material of the light-emitting layer preferably has a condensed ring structure of three or more rings, and more preferably has two or more condensed ring structures of three or more rings or at least one condensed ring of five or more rings. By using these compounds, the rigidity of the molecule increases, and it becomes easier to obtain the effect of suppressing the degree of molecular motion in response to heat. Furthermore, it is preferable that the condensed rings of three or more rings and the condensed rings of five or more rings have an aromatic hydrocarbon ring or an aromatic heterocyclic ring in terms of charge transportability and durability of the material.

Specific examples of condensed ring structures having three or more rings include anthracene structure, phenanthrene structure, pyrene structure, chrysene structure, naphthacene structure, triphenylene structure, fluorene structure, benzofluorene structure, indenofluorene structure, indolofluorene structure, carbazole structure, indenocarbazole structure, indolocarbazole structure, dibenzofuran structure, dibenzothiophene structure, etc. From the viewpoint of charge transportability and solubility, at least one selected from the group consisting of phenanthrene structure, fluorene structure, indenofluorene structure, carbazole structure, indenocarbazole structure, indolocarbazole structure, dibenzofuran structure, and dibenzothiophene structure is preferred, and from the viewpoint of durability against charge, a carbazole structure or an indolocarbazole structure is more preferred.

From the viewpoint of durability of the organic electroluminescent device against electric charges, it is preferable that at least one of the host materials of the light-emitting layer is a material having a pyrimidine skeleton or a triazine skeleton.

<Molecular weight range>
The host material of the light-emitting layer is preferably a polymer material from the viewpoint of excellent flexibility. A light-emitting layer formed using a material with excellent flexibility is preferable as a light-emitting layer of an organic electroluminescent element formed on a flexible substrate.
When the host material contained in the light-emitting layer is a polymeric material, its molecular weight is preferably from 5,000 to 1,000,000, more preferably from 10,000 to 500,000, and even more preferably from 10,000 to 100,000.

The host material of the light-emitting layer is preferably a low molecular weight material from the viewpoints of ease of synthesis and purification, ease of designing the electron transporting performance and hole transporting performance, and ease of adjusting the viscosity when dissolved in a solvent.
When the host material contained in the light-emitting layer is a low molecular weight material, its molecular weight is preferably 5,000 or less, more preferably 4,000 or less, particularly preferably 3,000 or less, and most preferably 2,000 or less, and is usually 300 or more, preferably 350 or more, and more preferably 400 or more.

[Blue fluorescent layer]
In an organic electroluminescent device using the polymer according to an embodiment of the present invention as a charge transport material forming at least one of a hole injection layer and a hole transport layer, when the light emitting layer is made of a fluorescent material, it is preferably a blue fluorescent material as described below.

<Blue fluorescent material>
The light-emitting material for the blue fluorescent layer is not particularly limited, but a compound represented by the following formula (211) is preferable.

In the above formula (211), Ar ²⁴¹ represents an aromatic hydrocarbon condensed ring structure which may have a substituent. Ar ²⁴² and Ar ²⁴³ each independently represent an alkyl group which may have a substituent, an aromatic hydrocarbon group, or a group in which these are bonded. n41 is an integer of 1 to 4.

Ar ²⁴¹ preferably represents an aromatic hydrocarbon condensed ring structure having 10 to 30 carbon atoms. Specific examples of the structure include a naphthalene ring, an acenaphthene ring, a fluorene ring, an anthracene ring, a phenanthrene ring, a fluoranthene ring, a pyrene ring, a tetracene ring, a chrysene ring, and a perylene ring. More preferably, it is an aromatic hydrocarbon condensed ring structure having 12 to 20 carbon atoms. Specific examples of the structure include an acenaphthene ring, a fluorene ring, an anthracene ring, a phenanthrene ring, a fluoranthene ring, a pyrene ring, a tetracene ring, a chrysene ring, and a perylene ring. Still more preferably, it is an aromatic hydrocarbon condensed ring structure having 16 to 18 carbon atoms, and specific examples of the structure include a fluoranthene ring, a pyrene ring, and a chrysene ring.

n41 is an integer from 1 to 4, preferably 1 to 3, more preferably 1 to 2, and most preferably 2.

<Substituents of Ar ²⁴¹ , Ar ²⁴² and Ar ²⁴³ >
The substituents that Ar ²⁴¹ , Ar ²⁴² , and Ar ²⁴³ may have are preferably groups selected from the aforementioned substituent group Z′, more preferably hydrocarbon groups included in the aforementioned substituent group Z′, and even more preferably hydrocarbon groups among the groups preferred as the substituent group Z′.

[Host material for blue fluorescent layer]
In an organic electroluminescent device in which the polymer according to an embodiment of the present invention is used as a charge transporting material forming at least one of a hole injection layer and a hole transport layer, when the light emitting layer is a blue fluorescent material, the following materials are preferable as the host material.

Although there are no particular limitations on the host material for the blue fluorescent-emitting layer, a compound represented by the following formula (212) is preferred.

In the above formula (212), R ²⁴¹ and R ²⁴² each independently represent a structure represented by the following formula (213). R ²⁴³ represents a substituent. When there are a plurality of R ²⁴³ , they may be the same or different. n43 represents an integer of 0 to 8.

In the above formula (213), Ar ²⁴⁴ and Ar ²⁴⁵ each independently represent an aromatic hydrocarbon structure which may have a substituent, or a heteroaromatic ring structure which may have a substituent. When there are a plurality of Ar ²⁴⁴ and Ar ²⁴⁵ , they may be the same or different. n44 is an integer of 1 to 5, and n45 is an integer of 0 to 5.

Ar ²⁴⁴ is preferably an aromatic hydrocarbon structure which is a monocyclic or fused ring having 6 to 30 carbon atoms and which may have a substituent, and more preferably an aromatic hydrocarbon structure which is a monocyclic or fused ring having 6 to 12 carbon atoms and which may have a substituent.

Ar ²⁴⁵ is preferably an aromatic hydrocarbon structure which is a monocyclic or fused ring having 6 to 30 carbon atoms and which may have a substituent, or an aromatic heterocyclic structure which is a fused ring having 6 to 30 carbon atoms and which may have a substituent, and more preferably an aromatic hydrocarbon structure which is a monocyclic or fused ring having 6 to 12 carbon atoms and which may have a substituent, or an aromatic heterocyclic structure which is a fused ring having 12 carbon atoms and which may have a substituent.

n44 is preferably an integer of 1 to 3, and more preferably 1 or 2.
n45 is preferably 0 to 3, more preferably 0 to 2.

<Substituents of R ²⁴³ , Ar ²⁴⁴ and Ar ²⁴⁵ >
The substituents R ²⁴³ and the substituents that Ar ²⁴⁴ and Ar ²⁴⁵ may have are preferably groups selected from the substituent group Z', more preferably hydrocarbon groups included in the substituent group Z', and even more preferably hydrocarbon groups among the groups preferred as the substituent group Z'.

<Molecular weight>
The molecular weight of the emitting material for the blue fluorescent layer and its host material is preferably 5,000 or less, more preferably 4,000 or less, particularly preferably 3,000 or less, and most preferably 2,000 or less, and is usually 300 or more, preferably 350 or more, and more preferably 400 or more.

[Organic electroluminescent element]
The organic electroluminescent device of the present embodiment is characterized in that, in the organic electroluminescent device having an anode and a cathode on a substrate, and an organic layer between the anode and the cathode, the organic layer includes a layer formed by a wet film-forming method using a composition for organic electroluminescent devices containing the polymer.

In the organic electroluminescent device of this embodiment, the layer formed by the wet film-forming method using the composition for organic electroluminescent devices containing the polymer is preferably at least one of a hole injection layer and a hole transport layer. In particular, it is preferable that the organic layer of the organic electroluminescent device comprises a hole injection layer, a hole transport layer, and a light-emitting layer, and all of these hole injection layer, hole transport layer, and light-emitting layer are layers formed by the wet film-forming method using the composition for organic electroluminescent devices containing the polymer.

In this embodiment, the wet film formation method refers to a film formation method, i.e., a coating method, in which a wet film formation method such as spin coating, dip coating, die coating, bar coating, blade coating, roll coating, spray coating, capillary coating, inkjet printing, nozzle printing, screen printing, gravure printing, or flexographic printing is adopted, and the coating film is dried to form a film. Among these film formation methods, the spin coating, spray coating, inkjet method, and nozzle printing method are preferred.

As an example of the structure of the organic electroluminescent element of this embodiment, Fig. 1 shows a schematic diagram (cross section) of an example of the structure of an organic electroluminescent element 10. In Fig. 1, 1 represents a substrate, 2 represents an anode, 3 represents a hole injection layer, 4 represents a hole transport layer, 5 represents a light-emitting layer, 6 represents a hole blocking layer, 7 represents an electron transport layer, 8 represents an electron injection layer, and 9 represents a cathode.

Below, an example of an embodiment of the layer structure of an organic electroluminescent element and its general formation method is described with reference to Figure 1.

[substrate]
The substrate 1 is a support for the organic electroluminescent element. The substrate 1 is usually made of a quartz or glass plate, a metal plate or metal foil, a plastic film or sheet, or the like. Of these, a glass plate or a plate made of a transparent synthetic resin such as polyester, polymethacrylate, polycarbonate, or polysulfone is preferred. The substrate is preferably made of a material with high gas barrier properties, since the organic electroluminescent element is less likely to deteriorate due to the outside air. For this reason, when a material with low gas barrier properties such as a synthetic resin substrate is used, it is preferred to provide a dense silicon oxide film or the like on at least one side of the substrate to increase the gas barrier properties.

[anode]
The anode 2 has a function of injecting holes into the layers on the light-emitting layer 5 side.
The anode 2 is usually composed of a metal such as aluminum, gold, silver, nickel, palladium, or platinum; a metal oxide such as indium and/or tin oxide; a metal halide such as copper iodide; carbon black, and a conductive polymer such as poly(3-methylthiophene), polypyrrole, or polyaniline.

The anode 2 is usually formed by a dry method such as sputtering or vacuum deposition.
When forming an anode using fine metal particles such as silver particles, fine particles such as copper iodide particles, carbon black, fine conductive metal oxide particles, fine conductive polymer powder, or the like, the anode can be formed by dispersing the particles in an appropriate binder resin solution and applying the solution onto a substrate.
In the case of a conductive polymer, a thin film can be formed directly on a substrate by electrolytic polymerization, or a conductive polymer can be coated on a substrate to form an anode (Appl. Phys. Lett., Vol. 60, p. 2711, 1992).

The anode 2 usually has a single-layer structure, but may have a laminated structure as appropriate. If the anode 2 has a laminated structure, a different conductive material may be laminated on the first layer of the anode.

The thickness of the anode 2 may be determined depending on the required transparency, material, etc. When particularly high transparency is required, a thickness that provides a visible light transmittance of 60% or more is preferable, and a thickness that provides a visible light transmittance of 80% or more is more preferable. The thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less.
On the other hand, when transparency is not required, the thickness of the anode 2 may be arbitrarily determined depending on the required strength, etc. In this case, the anode 2 may have the same thickness as the substrate.

When forming another layer on the surface of the anode 2, it is preferable to remove impurities on the anode 2 and adjust its ionization potential to improve hole injection properties by performing a treatment such as ultraviolet light/ozone, oxygen plasma, argon plasma, etc. before the film formation.

[Hole injection layer]
A layer that transports holes from the anode 2 side to the light-emitting layer 5 side is usually called a hole injection transport layer or a hole transport layer. When there are two or more layers that transport holes from the anode 2 side to the light-emitting layer 5 side, the layer closer to the anode side may be called a hole injection layer 3. The hole injection layer 3 is preferably formed in order to enhance the function of transporting holes from the anode 2 to the light-emitting layer 5 side. When the hole injection layer 3 is formed, the hole injection layer 3 is usually formed on the anode 2.

The thickness of the hole injection layer 3 is typically 1 nm or more, preferably 5 nm or more, and typically 1000 nm or less, preferably 500 nm or less.

The hole injection layer may be formed by vacuum deposition or wet film formation. From the viewpoint of excellent film formation properties, it is preferable to form the layer by wet film formation.

The hole injection layer 3 preferably contains a hole transport compound, and more preferably contains a hole transport compound and an electron accepting compound. Furthermore, it is preferable that the hole injection layer contains a cation radical compound, and it is particularly preferable that the hole injection layer contains a cation radical compound and a hole transport compound.

A typical method for forming a hole injection layer is described below. In the organic electroluminescent device of this embodiment, the hole injection layer is preferably formed by a wet film formation method using the composition for organic electroluminescent devices.

<Hole Transport Compound>
The hole injection layer forming composition usually contains a hole transporting compound that will become the hole injection layer 3. In the case of a wet film forming method, it usually further contains a solvent. The hole injection layer forming composition preferably has high hole transporting properties and can efficiently transport injected holes. For this reason, it is preferable that the hole mobility is large and impurities that become traps are unlikely to occur during production or use. In addition, it is preferable that the composition has excellent stability, a small ionization potential, and high transparency to visible light. In particular, when the hole injection layer 3 is in contact with the light emitting layer 5, it is preferable that the composition does not quench the light emission from the light emitting layer 5 or does not form an exciplex with the light emitting layer 5 to reduce the light emitting efficiency.

From the viewpoint of the charge injection barrier from the anode 2 to the hole injection layer 3, a compound having an ionization potential of 4.5 eV to 6.0 eV is preferable as the hole transport compound. Examples of the hole transport compound include aromatic amine compounds, phthalocyanine compounds, porphyrin compounds, oligothiophene compounds, polythiophene compounds, benzylphenyl compounds, compounds in which a tertiary amine is linked via a fluorene group, hydrazone compounds, silazane compounds, and quinacridone compounds.

Among the above-mentioned exemplary compounds, aromatic amine compounds are preferred from the viewpoint of amorphousness and visible light transmittance, and aromatic tertiary amine compounds are particularly preferred. Here, aromatic tertiary amine compounds are compounds having an aromatic tertiary amine structure, and also include compounds having a group derived from an aromatic tertiary amine.

The type of aromatic tertiary amine compound is not particularly limited, but it is preferable to use a polymeric compound (a polymeric compound with a series of repeating units) with a weight-average molecular weight of 1,000 or more and 1,000,000 or less, since it is easier to obtain uniform light emission due to the surface smoothing effect.

It is preferable that the hole injection layer 3 contains the aforementioned electron accepting compound or the aforementioned cation radical compound, since the conductivity of the hole injection layer can be improved by oxidation of the hole transport compound.

Cation radical compounds derived from polymeric compounds such as PEDOT/PSS (Adv. Mater., 2000, Vol. 12, p. 481) and emeraldine hydrochloride (J. Phys. Chem., 1990, Vol. 94, p. 7716) can also be produced by oxidative polymerization (dehydrogenative polymerization).

The oxidative polymerization referred to here is a process in which monomers are oxidized chemically or electrochemically in an acidic solution using peroxodisulfate or the like. In the case of this oxidative polymerization (dehydrogenative polymerization), the monomers are oxidized to polymerize, and a cation radical is generated in which one electron has been removed from the repeating unit of the polymer, with the anion derived from the acidic solution serving as the counter anion.

<Formation of hole injection layer by wet film formation method>
When the hole injection layer 3 is formed by a wet film formation method, a material for the hole injection layer 3 is usually mixed with a soluble solvent (a solvent for the hole injection layer) to prepare a composition for film formation (a composition for forming a hole injection layer), and this composition for forming a hole injection layer is applied onto a layer corresponding to the lower layer of the hole injection layer 3 (usually, the anode 2) to form a film, and then dried to form the film.

The concentration of the hole transport compound in the composition for forming the hole injection layer can be any concentration as long as it does not significantly impair the effects of the present invention, but in terms of uniformity of the film thickness, a lower concentration is preferable, and in terms of preventing defects from occurring in the hole injection layer, a higher concentration is preferable. Specifically, the concentration is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, particularly preferably 0.5% by weight or more, preferably 70% by weight or less, more preferably 60% by weight or less, and particularly preferably 50% by weight or less.

Examples of solvents include ether-based solvents, ester-based solvents, aromatic hydrocarbon-based solvents, amide-based solvents, etc.

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

Examples of ester solvents include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate.

Examples of aromatic hydrocarbon solvents include toluene, xylene, cyclohexylbenzene, 3-isopropylbiphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, cyclohexylbenzene, methylnaphthalene, etc.

Examples of the amide solvent include N,N-dimethylformamide and N,N-dimethylacetamide.
In addition, dimethyl sulfoxide and the like can also be used.

The formation of the hole injection layer 3 by a wet film formation method is usually carried out by preparing a composition for forming the hole injection layer, applying the composition to a layer corresponding to the lower layer of the hole injection layer 3 (usually the anode 2) and drying the composition.
After the hole injection layer 3 is formed, the applied film is usually dried by heating, drying under reduced pressure, or the like.

<Formation of Hole Injection Layer by Vacuum Deposition Method>
When the hole injection layer 3 is formed by the vacuum deposition method, one or more of the constituent materials of the hole injection layer 3 (such as the above-mentioned hole transporting compound and electron accepting compound) are usually placed in a crucible installed in a vacuum container (when two or more materials are used, each is usually placed in a separate crucible), and the inside of the vacuum container is evacuated to about 10 ⁻⁴ Pa with a vacuum pump, and then the crucible is heated (when two or more materials are used, each crucible is usually heated) to evaporate the materials in the crucible while controlling the amount of evaporation (when two or more materials are used, each is usually evaporated while controlling the amount of evaporation independently), and the hole injection layer 3 is formed on the anode 2 on the substrate 1 placed opposite the crucible. When two or more materials are used, a mixture of them can be placed in a crucible, heated, and evaporated to form the hole injection layer.

The degree of vacuum during deposition is not limited as long as it does not significantly impair the effects of the present invention, but is usually 0.1×10 ⁻⁶ Torr (0.13×10 ⁻⁴ Pa) or more and 9.0×10 ⁻⁶ Torr (12.0×10 ⁻⁴ Pa) or less. The deposition rate is not limited as long as it does not significantly impair the effects of the present invention, but is usually 0.1 Å/sec or more and 5.0 Å/sec or less. The film formation temperature during deposition is not limited as long as it does not significantly impair the effects of the present invention, but is preferably 10° C. or more and 50° C. or less.
The hole injection layer 3 may be crosslinked in the same manner as the hole transport layer 4 described below.

[Hole transport layer]
The hole transport layer 4 is a layer that transports holes from the anode 2 side to the light emitting layer 5 side. Although the hole transport layer 4 is not an essential layer in the organic electroluminescent device of this embodiment, it is preferable to form this layer in terms of enhancing the function of transporting holes from the anode 2 to the light emitting layer 5. When the hole transport layer 4 is formed, it is usually formed between the anode 2 and the light emitting layer 5. When the above-mentioned hole injection layer 3 is present, the hole transport layer 4 is formed between the hole injection layer 3 and the light emitting layer 5.

The thickness of the hole transport layer 4 is typically 5 nm or more, preferably 10 nm or more, and typically 300 nm or less, preferably 100 nm or less.

The hole transport layer 4 may be formed by vacuum deposition or wet film formation. From the viewpoint of excellent film formation properties, it is preferable to form the hole transport layer 4 by wet film formation.

A typical method for forming a hole transport layer is described below. In the organic electroluminescent device of this embodiment, the hole transport layer is preferably formed by a wet film formation method using the composition for organic electroluminescent devices.

The hole transport layer 4 usually contains a hole transport compound. As the hole transport compound contained in the hole transport layer 4, the polymer of the present embodiment described above or, if the polymer has a crosslinkable group, a polymer obtained by crosslinking the polymer is preferable. In addition to the above-mentioned polymer, the hole transport compound, an aromatic diamine containing two or more tertiary amines and having two or more condensed aromatic rings substituted with nitrogen atoms, such as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (JP Patent Publication No. 5-234681), and an aromatic amine compound having a starburst structure, such as 4,4',4''-tris(1-naphthylphenylamino)triphenylamine (J. Lumin., 72-7 4, p. 985, 1997), aromatic amine compounds consisting of a tetramer of triphenylamine (Chem. Commun., p. 2175, 1996), spiro compounds such as 2,2',7,7'-tetrakis-(diphenylamino)-9,9'-spirobifluorene (Synth. Metals, vol. 91, p. 209, 1997), carbazole derivatives such as 4,4'-N,N'-dicarbazolebiphenyl, etc., may also be included. For example, polyvinylcarbazole, polyvinyltriphenylamine (JP-A-7-53953), polyarylene ether sulfone containing tetraphenylbenzidine (Polym. Adv. Tech., vol. 7, p. 33, 1996), etc. may also be included.

<Formation of hole transport layer by wet film formation method>
When the hole transport layer 4 is formed by a wet film formation method, it is usually formed using a composition for forming a hole transport layer instead of the composition for forming a hole injection layer, in the same manner as when the above-mentioned hole injection layer 3 is formed by a wet film formation method.

When the hole transport layer 4 is formed by a wet film formation method, the composition for forming a hole transport layer usually further contains a solvent. The solvent used in the composition for forming a hole transport layer may be the same as the solvent used in the composition for forming a hole injection layer described above.
The concentration of the hole transporting compound in the composition for forming a hole transport layer can be in the same range as the concentration of the hole transporting compound in the composition for forming a hole injection layer.
The hole transport layer 4 can be formed by a wet film formation method similar to the film formation method for the hole injection layer 3 described above.

<Formation of hole transport layer by vacuum deposition method>
When the hole transport layer 4 is formed by the vacuum deposition method, it can be formed in the same manner as when the hole injection layer 3 is formed by the vacuum deposition method, by using the material of the hole transport layer 4 instead of the material of the hole injection layer 3. The film formation conditions such as the degree of vacuum, deposition rate, and temperature during deposition can be the same as those during the vacuum deposition of the hole injection layer 3.

[Light-emitting layer]
The light-emitting layer 5 is a layer that is excited by the recombination of holes injected from the anode 2 and electrons injected from the cathode 9 when an electric field is applied between the pair of electrodes, and thus has the function of emitting light. The light-emitting layer 5 is a layer formed between the anode 2 and the cathode 9. When the hole injection layer 3 is present on the anode 2, the light-emitting layer 5 is formed between the hole injection layer 3 and the cathode 9. When the hole transport layer 4 is present on the anode 2, the light-emitting layer 5 is formed between the hole transport layer 4 and the cathode 9.

The thickness of the light-emitting layer 5 is arbitrary as long as it does not significantly impair the effects of the present invention, but a thicker layer is preferable in that defects are less likely to occur in the film, and a thinner layer is preferable in that it is easier to achieve a low driving voltage. For this reason, the thickness of the light-emitting layer 5 is preferably 3 nm or more, more preferably 5 nm or more, and usually preferably 200 nm or less, more preferably 100 nm or less.

The light-emitting layer 5 contains at least a material having light-emitting properties (light-emitting material) and preferably contains a material having charge transport properties (charge transport material).

Below, we will explain common light-emitting materials and methods for forming the light-emitting layer. In the organic electroluminescent device of this embodiment, it is preferable that the light-emitting layer is formed by a wet film formation method using the composition for organic electroluminescent devices, particularly the light-emitting layer material and host material described above.

<Light-emitting material>
The light-emitting material is not particularly limited as long as it emits light at a desired emission wavelength and does not impair the effects of the present invention, and any known light-emitting material can be used. The light-emitting material may be a fluorescent material or a phosphorescent material, but a material with good luminous efficiency is preferred, and a phosphorescent material is preferred from the viewpoint of internal quantum efficiency.

Examples of fluorescent materials include the following:

Examples of fluorescent materials that emit blue light (blue fluorescent materials) include naphthalene, perylene, pyrene, anthracene, coumarin, chrysene, p-bis(2-phenylethenyl)benzene, and derivatives thereof.

Examples of fluorescent materials that emit green light (green fluorescent materials) include quinacridone derivatives, coumarin derivatives, and aluminum complexes such as Al(C ₉ H ₆ NO) ₃ .

Examples of fluorescent materials that emit yellow light (yellow fluorescent materials) include rubrene and perimidone derivatives.

Examples of fluorescent materials that emit red light (red fluorescent materials) include DCM (4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran) compounds, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, and azabenzothioxanthene.

Examples of phosphorescent materials include organometallic complexes containing a metal selected from Groups 7 to 11 of the periodic table. Metals selected from Groups 7 to 11 of the periodic table preferably include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold.

As the ligand of the organometallic complex, a ligand in which a (hetero)aryl group is linked to pyridine, pyrazole, phenanthroline, etc., such as a (hetero)arylpyridine ligand or a (hetero)arylpyrazole ligand, is preferred, and a phenylpyridine ligand or a phenylpyrazole ligand is particularly preferred. Here, (hetero)aryl represents an aryl group or a heteroaryl group.

Preferred phosphorescent materials include, for example, phenylpyridine complexes such as tris(2-phenylpyridine)iridium, tris(2-phenylpyridine)ruthenium, tris(2-phenylpyridine)palladium, bis(2-phenylpyridine)platinum, tris(2-phenylpyridine)osmium, and tris(2-phenylpyridine)rhenium; and porphyrin complexes such as octaethylplatinum porphyrin, octaphenylplatinum porphyrin, octaethylpalladium porphyrin, and octaphenylpalladium porphyrin.

Examples of polymer-based light-emitting materials include polyfluorene-based materials such as poly(9,9-dioctylfluorene-2,7-diyl), poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl))diphenylamine)] and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(1,4-benzo-2{2,1'-3}-triazole)], and polyphenylenevinylene-based materials such as poly[2-methoxy-5-(2-hexylhexyloxy)-1,4-phenylenevinylene].

<Charge Transporting Material>
The charge transporting material is a material that has a positive charge (hole) or negative charge (electron) transporting property, and is not particularly limited as long as it does not impair the effects of the present invention, and any known light emitting material can be used.

The charge transport material may be a compound that has been conventionally used in the light-emitting layer of an organic electroluminescent element, and in particular, a compound that is used as a host material in the light-emitting layer is preferred.

Specific examples of charge transport materials include aromatic amine compounds including the polymer of the present invention, phthalocyanine compounds, porphyrin compounds, oligothiophene compounds, polythiophene compounds, benzylphenyl compounds, compounds in which a tertiary amine is linked via a fluorene group, hydrazone compounds, silazane compounds, silanamine compounds, phosphamine compounds, and quinacridone compounds, which are listed as examples of hole transport compounds for the hole injection layer. Other examples include electron transport compounds such as anthracene compounds, pyrene compounds, carbazole compounds, pyridine compounds, phenanthroline compounds, oxadiazole compounds, and silole compounds.

For example, aromatic diamines containing two or more tertiary amines, such as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl, in which two or more condensed aromatic rings are substituted with nitrogen atoms (JP Patent Publication No. 5-234681), aromatic amine compounds having a starburst structure, such as 4,4',4''-tris(1-naphthylphenylamino)triphenylamine (J. Lumin., Vol. 72-74, p. 985, 1997), triphenylamine Compounds exemplified as hole-transporting compounds for the hole-transporting layer, such as aromatic amine compounds consisting of tetramers (Chem. Commun., p. 2175, 1996), fluorene compounds such as 2,2',7,7'-tetrakis-(diphenylamino)-9,9'-spirobifluorene (Synth. Metals, vol. 91, p. 209, 1997), and carbazole compounds such as 4,4'-N,N'-dicarbazolebiphenyl, can also be preferably used.

Other examples include oxadiazole compounds such as 2-(4-biphenylyl)-5-(p-tert-butylphenyl)-1,3,4-oxadiazole (tBu-PBD) and 2,5-bis(1-naphthyl)-1,3,4-oxadiazole (BND), silole compounds such as 2,5-bis(6'-(2',2''-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy), and phenanthroline compounds such as bathophenanthroline (BPhen) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP, bathocuproine).

<Formation of light-emitting layer by wet film formation method>
The method for forming the light-emitting layer 2 may be a vacuum deposition method or a wet film-forming method. From the viewpoint of excellent film-forming properties, the wet film-forming method is preferred, and the spin coating method and the ink-jet method are more preferred.

In particular, when the hole injection layer 3 or the hole transport layer 4, which is the layer below the light emitting layer 2, is formed using the composition for organic electroluminescent elements, lamination by the wet film formation method is easy, so that it is preferable to employ the wet film formation method. When the light emitting layer 5 is formed by the wet film formation method, it is usually formed using a light emitting layer forming composition prepared by mixing the material to be the light emitting layer 5 with a soluble solvent (light emitting layer solvent) instead of the hole injection layer forming composition, in the same manner as when the hole injection layer is formed by the wet film formation method described above.

Examples of the solvent include the ether solvents, ester solvents, aromatic hydrocarbon solvents, and amide solvents mentioned for forming the hole injection layer 3, as well as alkane solvents, halogenated aromatic hydrocarbon solvents, aliphatic alcohol solvents, alicyclic alcohol solvents, aliphatic ketone solvents, and alicyclic ketone solvents. Specific examples of the solvent are listed below, but are not limited to these as long as they do not impair the effects of the present invention.

For example, aliphatic ether solvents such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); aromatic ether solvents such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, and diphenyl ether; aromatic ester solvents such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate; toluene, xylene, mesitylene, cyclohexylbenzene, tetralin, 3-isopropylbiphenyl, 1, Examples of suitable solvents include aromatic hydrocarbon solvents such as 2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, cyclohexylbenzene, and methylnaphthalene; amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide; alkane solvents such as n-decane, cyclohexane, ethylcyclohexane, decalin, and bicyclohexane; halogenated aromatic hydrocarbon solvents such as chlorobenzene, dichlorobenzene, and trichlorobenzene; aliphatic alcohol solvents such as butanol and hexanol; alicyclic alcohol solvents such as cyclohexanol and cyclooctanol; aliphatic ketone solvents such as methyl ethyl ketone and dibutyl ketone; and alicyclic ketone solvents such as cyclohexanone, cyclooctanone, and fenchone. Of these, alkane solvents and aromatic hydrocarbon solvents are particularly preferred.

In order to obtain a more uniform film, it is preferable that the solvent evaporates at an appropriate rate from the liquid film immediately after film formation. For this reason, as described above, the boiling point of the solvent used is usually 80°C or higher, preferably 100°C or higher, more preferably 120°C or higher, and usually 270°C or lower, preferably 250°C or lower, more preferably 230°C or lower.

The amount of solvent used may be any amount as long as it does not significantly impair the effects of the present invention, but the content in the composition for forming the light-emitting layer is preferably 1% by mass or more, more preferably 10% by mass or more, and particularly preferably 50% by mass or more, and is preferably 99.99% by mass or less, more preferably 99.9% by mass or less, and particularly preferably 99% by mass or less.

Heating or reduced pressure can be used to remove the solvent after wet film formation. A clean oven or hot plate is preferred as the heating means used in the heating method, as they apply heat evenly to the entire film.

The heating temperature in the heating step is arbitrary as long as it does not significantly impair the effects of the present invention, but a higher temperature is preferable in terms of shortening the drying time, and a lower temperature is preferable in terms of less damage to the material. The upper limit of the heating temperature is usually 250°C or less, preferably 200°C or less, and more preferably 150°C or less. The lower limit of the heating temperature is usually 30°C or more, preferably 50°C or more, and more preferably 80°C or more. A heating temperature exceeding the above upper limit is higher than the heat resistance of the charge transport material or phosphorescent material normally used, and is not preferable because these may decompose or crystallize. A heating temperature below the above lower limit is not preferable because it takes a long time to remove the solvent. The heating time in the heating step is appropriately determined depending on the boiling point and vapor pressure of the solvent in the composition for forming the light-emitting layer, the heat resistance of the material, and the heating conditions.

<Formation of light-emitting layer by vacuum deposition method>
When the light-emitting layer 5 is formed by the vacuum deposition method, one or more of the constituent materials of the light-emitting layer 5 (such as the above-mentioned light-emitting material and charge-transporting compound) are usually placed in a crucible installed in a vacuum vessel (when two or more materials are used, each is usually placed in a separate crucible), the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with a vacuum pump, and then the crucible is heated (when two or more materials are used, each crucible is usually heated) to evaporate the materials in the crucible while controlling the amount of evaporation (when two or more materials are used, each is usually evaporated while controlling the amount of evaporation independently), and the light-emitting layer 5 is formed on the hole injection layer 3 or hole transport layer 4 placed opposite the crucible. When two or more materials are used, a mixture of those materials can also be placed in a crucible and heated and evaporated to form the light-emitting layer 5.

The degree of vacuum during deposition is not limited as long as it does not significantly impair the effects of the present invention, but is usually 0.1×10 ⁻⁶ Torr (0.13×10 ⁻⁴ Pa) or more and 9.0×10 ⁻⁶ Torr (12.0×10 ⁻⁴ Pa) or less. The deposition rate is not limited as long as it does not significantly impair the effects of the present invention, but is usually 0.1 Å/sec or more and 5.0 Å/sec or less. The film formation temperature during deposition is not limited as long as it does not significantly impair the effects of the present invention, but is preferably 10° C. or more and 50° C. or less.

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

Examples of materials for the hole blocking layer 6 that satisfy these conditions include mixed ligand complexes such as bis(2-methyl-8-quinolinolato)(phenolato)aluminum and bis(2-methyl-8-quinolinolato)(triphenylsilanolate)aluminum, metal complexes such as bis(2-methyl-8-quinolinolato)aluminum-μ-oxo-bis-(2-methyl-8-quinolinolato)aluminum binuclear metal complex, styryl compounds such as distyrylbiphenyl derivatives (JP Patent Publication No. 11-242996), triazole derivatives such as 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (JP Patent Publication No. 7-41759), and phenanthroline derivatives such as bathocuproine (JP Patent Publication No. 10-79297). Furthermore, compounds having at least one pyridine ring substituted at the 2-, 4- and 6-positions, as described in International Publication No. 2005/022962, are also preferred as materials for the hole blocking layer 6.

There is no limitation on the method for forming the hole blocking layer 6. 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 may be any thickness as long as it does not significantly impair the effects of the present invention, but is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.

[Electron Transport Layer]
The electron transport layer 7 is provided between the light emitting layer 5 and the electron injection layer 8 for the purpose of further improving the current efficiency of the device.

The electron transport layer 7 is formed from a compound that can efficiently transport electrons injected from the cathode 9 in the direction of the light-emitting layer 5 between electrodes to which an electric field is applied. The electron transport compound used in the electron transport layer 7 must have a high efficiency of electron injection from the cathode 9 or the electron injection layer 8, a high electron mobility, and be able to efficiently transport the injected electrons.

Examples of electron transport compounds used in the electron transport layer include metal complexes such as aluminum complexes of 8-hydroxyquinoline (JP Patent Publication 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 Patent Publication 5,645,948), quinoxaline compounds (JP Patent Publication 6-207169), phenanthroline derivatives (JP Patent Publication 5-331459), 2-t-butyl-9,10-N,N'-dicyanoanthraquinone diimine, n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, and n-type zinc selenide.

The thickness of the electron transport layer 7 is typically 1 nm or more, preferably 5 nm or more, and typically 300 nm or less, preferably 100 nm or less.

The electron transport layer 7 is formed by laminating it on the hole blocking layer 6 by a wet film forming method or a vacuum deposition method as described above. Usually, the vacuum deposition method is used.

[Electron injection layer]
The electron injection layer 8 plays a role of efficiently injecting electrons injected from the cathode 9 into the electron transport layer 7 or the light emitting layer 5 .

To efficiently inject electrons, the material forming the electron injection layer 8 is preferably a metal with a low work function. Examples include alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium. In this case, the thickness of the electron injection layer 8 is preferably 0.1 nm or more and 5 nm or less.

Further, as a material for forming the electron injection layer 8, an organic electron transporting material typified by a nitrogen-containing heterocyclic compound such as bathophenanthroline or a metal complex such as an aluminum complex of 8-hydroxyquinoline doped with an alkali metal such as sodium, potassium, cesium, lithium or rubidium (described in JP-A-10-270171, JP-A-2002-100478, JP-A-2002-100482, etc.) is also preferable because it improves the electron injection and transport properties and makes it possible to simultaneously achieve excellent film quality.
In this case, the film thickness of the electron injection layer 8 is usually 5 nm or more, preferably 10 nm or more, and usually 200 nm or less, preferably 100 nm or less.

The electron injection layer 8 is formed by laminating on the light emitting layer 5 or the hole blocking layer 6 or electron transport layer 7 thereon by a wet film formation method or a vacuum deposition method.
The details of the wet film formation method are the same as those of the light-emitting layer described above.

[cathode]
The cathode 9 plays a role of injecting electrons into the layer on the light-emitting layer 5 side (the electron injection layer 8 or the light-emitting layer 5, etc.).

The material of the cathode 9 can be the same as that used for the anode 2, but in order to efficiently inject electrons, it is preferable to use a metal with a low work function. Examples of the material of the cathode 9 include metals such as tin, magnesium, indium, calcium, aluminum, and silver, or alloys thereof. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.

From the viewpoint of element stability, it is preferable to protect the cathode made of a metal with a low work function by laminating a metal layer having a high work function and stability against the atmosphere on the cathode 9. Examples of metals to be laminated include aluminum, silver, copper, nickel, chromium, gold, platinum, etc.

The thickness of the cathode 9 is usually the same as that of the anode 2.

[Other layers]
The organic electroluminescent device of the present embodiment may further include other layers as long as the effects of the present invention are not significantly impaired. That is, any layer other than the layers described above may be included between the anode 2 and the cathode 9.

[Other element configurations]
The organic electroluminescent device of this embodiment may have a structure opposite to that described above, that is, 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 laminated in this order on a substrate 1. The organic electroluminescent device of the present invention may also be provided between two substrates, at least one of which is highly transparent.

When the organic electroluminescent element of this embodiment is applied to an organic electroluminescent device, it may be used as a single organic electroluminescent element, or it may be used in a configuration in which multiple organic electroluminescent elements are arranged in an array, or it may be used in a configuration in which anodes and cathodes are arranged in an X-Y matrix.

[Organic EL display device]
The organic EL display device (organic electroluminescence element display device) of this embodiment uses the above-mentioned organic electroluminescence element. There are no particular limitations on the type or structure of the organic EL display device of this embodiment. The organic electroluminescent device described above can be assembled in a conventional manner.
For example, the organic EL display device of the present invention can be manufactured by a method as described in "Organic EL Display" (Ohmsha, published on August 20, 2004, by Shizuo Tokito, Chihaya Adachi, and Hideyuki Murata). It can be formed.

[Organic EL lighting]
The organic EL lighting (organic electroluminescence element lighting) of this embodiment uses the above-mentioned organic electroluminescence element. There are no particular limitations on the type or structure of the organic EL lighting of this embodiment, and it can be assembled in accordance with a conventional method using the above-mentioned organic electroluminescence element.

The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples, and the present invention can be modified and carried out as desired without departing from the gist of the invention.

Polymer Production Examples
[Synthesis of Monomer]

Under a nitrogen stream, 3-bromo-3'-nitro-biphenyl (14.1 g, 50.5 mmol), bis(pinacolato)diboron (17.1 g, 60.6 mmol), and potassium acetate (24.8 g, 253.0 mmol) were placed in a 1000 ml flask and purged with nitrogen at room temperature. Then, 200 ml of 1,4-dioxane was placed in the flask, and 1,1'-bis(diphenylphosphino)ferrocene-palladium(II) dichloride-dichloromethane [PdCl ₂ (dppf)CH ₂ Cl ₂ ] (1.24 g, 1.52 mmol) was added, and the mixture was reacted at 100°C for 8.5 hours.
The reaction solution was filtered under reduced pressure, diluted with toluene, and crudely purified with activated clay. The crude product was purified by column chromatography (developing solution: hexane/ethyl acetate = 80/20) to obtain Compound 1 (16.3 g, yield 99.5%).

Compound 1 (8.7 g, 26.76 mmol), 1-bromo-3-iodobenzene (7.95 g, 28.1 mmol), an aqueous potassium phosphate solution (2 M, 40.1 ml), toluene (80 ml), and ethanol (40 ml) were charged into a flask, and the atmosphere in the system was thoroughly replaced with nitrogen and heated to 65° C.
Bis(triphenylphosphine)palladium(II) dichloride (0.094 g, 0.134 mmol) was added thereto and stirred at 65° C. for 3 hours. Water was added to the reaction solution, and extraction was performed with toluene. The organic layer was dried over anhydrous magnesium sulfate and crudely purified using activated clay. The crude product was purified by column chromatography (developing solution: hexane/methylene chloride=80/20) to obtain compound 2 (8.6 g, yield 90.5%).

Under a nitrogen stream, 100 ml of dimethylsulfoxide, compound 2 (8.55 g, 24.14 mmol), bis(pinacolato)diboron (7.36 g, 28.97 mmol), and potassium acetate (7.1 g, 72.42 mmol) were placed in a 300 ml flask and stirred for 30 minutes at 60° C. Then, 1,1′-bis(diphenylphosphino)ferrocene-palladium(II) dichloride-dichloromethane [PdCl ₂ (dppf)CH ₂ Cl ₂ ] (0.99 g, 1.21 mmol) was added, and the mixture was reacted at 85° C. for 4.0 hours.
The reaction solution was filtered under reduced pressure, and the filtrate was extracted with toluene. The organic layer was dried over anhydrous magnesium sulfate and crudely purified with activated clay. The crude product was purified by column chromatography (developing solution: hexane/ethyl acetate = 90/10) to obtain compound 3 (9.3 g, yield 96.0%).

Compound 3 (9.3 g, 23.18 mmol), 1-bromo-4-iodobenzene (6.88 g, 24.33 mmol), an aqueous potassium phosphate solution (2 M, 34.8 ml), toluene (80 ml), and ethanol (40 ml) were charged into a flask, and the inside of the system was thoroughly replaced with nitrogen and heated to 65° C.
Bis(triphenylphosphine)palladium(II) dichloride (0.081 g, 0.116 mmol) was added thereto, and the mixture was stirred at 65° C. for 3.5 hours. Water was added to the reaction solution, and extraction was performed with toluene. The organic layer was dried over anhydrous magnesium sulfate and crudely purified using activated clay. The crude product was purified by column chromatography (developing solution: hexane/methylene chloride=75/25) to obtain compound 4 (8.7 g, yield 87.2%).

Under a nitrogen stream, 100 ml of dimethylsulfoxide, compound 4 (8.7 g, 20.22 mmol), bis(pinacolato)diboron (6.2 g, 24.26 mmol), and potassium acetate (5.95 g, 60.66 mmol) were placed in a 300 ml flask and stirred for 30 minutes at 60° C. Then, 1,1′-bis(diphenylphosphino)ferrocene-palladium(II) dichloride-dichloromethane [PdCl ₂ (dppf)CH ₂ Cl ₂ ] (0.83 g, 1.01 mmol) was added, and the mixture was reacted at 85° C. for 3.0 hours.
The reaction solution was filtered under reduced pressure, and the filtrate was extracted with toluene. The organic layer was dried over anhydrous magnesium sulfate and crudely purified with activated clay. The crude product was purified by column chromatography (developing solution: hexane/methylene chloride=50/50) to obtain compound 5 (7.2 g, yield 75.0%).

Compound 5 (7.1 g, 14.87 mmol), commercially available 2-chloro-4,6-diphenyl-1,3,5-triazine (3.98 g, 14.87 mmol), an aqueous potassium phosphate solution (2 M, 23.0 ml), toluene (50 ml), and ethanol (25 ml) were charged into a flask, and the inside of the system was thoroughly replaced with nitrogen and heated to 65° C.
Tetrakis(triphenylphosphine)palladium(0) (0.52 g, 0.45 mmol) was added thereto, and the mixture was stirred at 85° C. for 4.0 hours. The precipitated insoluble matter was filtered under reduced pressure, and the filtered product was washed by suspending it in 50 ml of methylene chloride and added dropwise to 200 ml of ethanol. The precipitate was filtered under reduced pressure and dried to obtain compound 6 (5.3 g, yield 61.2%).

Under a nitrogen stream, 500 ml of tetrahydrofuran, 50 ml of ethanol, compound 6 (5.3 g, 9.10 mmol), and palladium/carbon (10%, about 55% wet with water, 0.72 g) were placed in a 1000 ml flask and stirred for 15 minutes at 50° C. Then, hydrazine monohydrate (3.1 g) was added dropwise and reacted at this temperature for 3 hours.
The reaction mixture was filtered through water-wet Celite under reduced pressure, and the filtrate was concentrated to obtain Compound 7 (4.8 g, yield 95.1%).

Compound 8 (8.0 g, 49 mmol), 1-bromo-1'-iodo-3,3'-biphenyl (17.7 g, 49 mmol), 120 ml of toluene, 60 ml of ethanol, and 2 M aqueous potassium phosphate solution (62 ml) were placed in a 500 ml flask, and nitrogen bubbling was performed for 30 minutes.
Tetrakis(triphenylphosphine)palladium(0) (1.43 g, 1.24 mmol) was added thereto, and the mixture was heated and stirred at 90° C. for 3 hours. The mixture was then cooled to room temperature, and water and toluene were added for separation and washing, after which the organic layer was dried over anhydrous magnesium sulfate. The solvent was then removed under reduced pressure. The resulting residue was purified by silica gel column chromatography (dichloromethane/hexane=1/9) to obtain 15.5 g of compound 9 as a colorless oil.

Compound 9 (15.5 g, 44 mmol), 3-aminophenylboronic acid monohydrate (6.4 g, 41 mmol), 100 ml of toluene, 50 ml of ethanol, and a 2 M aqueous potassium phosphate solution (55 ml) were placed in a 500 ml flask, and nitrogen bubbling was performed for 30 minutes.
Tetrakis(triphenylphosphine)palladium(0) (1.3 g, 1.15 mmol) was added thereto, and the mixture was heated and stirred at 90° C. for 3.5 hours. The mixture was then cooled to room temperature, and water and toluene were added for separation and washing, after which the organic layer was dried over anhydrous magnesium sulfate. The solvent was then removed under reduced pressure. The resulting residue was purified by silica gel column chromatography (ethyl acetate/hexane=2/8) to obtain 7.8 g of compound 10 as a pale yellow starch syrup.

A solution containing 270 ml of toluene, 135 ml of ethanol, 20.0 g (44.8 mmol) of compound 11, 50.72 g (179.3 mmol) of 1-bromo-4-iodotoluene, and 2 M aqueous potassium phosphate solution (191 ml) in a 1 L flask was degassed under vacuum and replaced with nitrogen. The solution was heated under a nitrogen stream and stirred for 30 minutes.
Then, 0.63 g (0.90 mmol) of bis(triphenylphosphine)palladium(II) dichloride was added and refluxed for 6 hours. Water was added to the reaction solution, which was extracted with toluene, and the organic layer was treated with anhydrous magnesium sulfate and activated clay. After heating and refluxing the toluene solution, insoluble matter was filtered and recrystallized to obtain colorless solid compound 12 (yield: 14.2 g, yield: 60.2%).

Compound 14 was synthesized in the same manner as compound 12, except that 1-bromo-4-iodobenzene was used instead of 5-bromo-2-iodotoluene.

[Example I-1: Synthesis of Polymer 1]

Compound 12 (2.5 g, 4.7 mmol), compound 13 (2.134 g, 6.1 mmol), compound 10 (0.51 g, 1.4 mmol), compound 7 (1.04 g, 1.9 mmol), sodium tert-butoxide (3.48 g, 36.2 mmol) and toluene (71 ml) were charged, the inside of the system was thoroughly replaced with nitrogen, and the system was heated to 60° C. (Solution A1).
Separately, to a solution of tris(dibenzylideneacetone)dipalladium complex (86.0 mg, 0.09 mmol) in 14 ml of toluene was added [4-(N,N-dimethylamino)phenyl]di-tert-butylphosphine (Amphos) (199.4 mg, 0.8 mmol), and the mixture was heated to 60° C. (Solution B1).

Solution B1 was added to solution A1 in a nitrogen stream, and the mixture was heated under reflux for 1.0 hour. After confirming that compounds 7, 10, and 13 had disappeared, compound 14 (1.78 g, 3.5 mmol) was added. After heating under reflux for 2 hours, bromobenzene (1.84 g, 11.7 mmol) was added, and the mixture was heated under reflux for 1 hour. The reaction solution was allowed to cool, and was added dropwise to an ethanol/water (370 ml/70 ml) solution to obtain an end-capped crude polymer.
The end-capped crude polymer was dissolved in toluene, reprecipitated in acetone, and the precipitated polymer was filtered off. The obtained polymer was dissolved in toluene, washed with dilute hydrochloric acid, and reprecipitated in ammonia-containing ethanol. The filtered polymer was purified by column chromatography to obtain the target polymer 1 (2.5 g). The molecular weight of the obtained polymer 1 was as follows.

Weight average molecular weight (Mw) = 20,600
Number average molecular weight (Mn) = 15,260
Dispersity (Mw/Mn)=1.35

[Example I-2: Synthesis of Polymer 2]

Compound 12 (2.5 g, 4.7 mmol), compound 13 (1.641 g, 4.70 mmol), 2-amino-9,9′-dimethylfluorene (0.59 g, 2.82 mmol), compound 7 (1.04 g, 1.9 mmol), sodium tert-butoxide (3.48 g, 36.2 mmol) and toluene (71 ml) were charged, the system was thoroughly purged with nitrogen, and the system was heated to 60° C. (Solution A2).
To a solution of tris(dibenzylideneacetone)dipalladium complex (86.0 mg, 0.09 mmol) in 14 ml of toluene, [4-(N,N-dimethylamino)phenyl]di-tert-butylphosphine (Amphos) (199.4 mg, 0.8 mmol) was added and the mixture was heated to 60° C. (Solution B2).

Solution B2 was added to solution A2 in a nitrogen stream, and the mixture was heated under reflux for 1.0 hour. After confirming that commercially available 2-amino-9,9'-dimethylfluorene, compound 7, and compound 13 had disappeared, compound 14 (2.08 g, 4.13 mmol) was added. After heating under reflux for 2 hours, bromobenzene (0.89 g, 5.67 mmol) was added, and the mixture was heated under reflux for 1 hour. The reaction solution was allowed to cool, and then added dropwise to an ethanol/water (370 ml/70 ml) solution to obtain an end-capped crude polymer.
The end-capped crude polymer was dissolved in toluene, reprecipitated in acetone, and the precipitated polymer was filtered off. The obtained polymer was dissolved in toluene, washed with dilute hydrochloric acid, and reprecipitated in ammonia-containing ethanol. The filtered polymer was purified by column chromatography to obtain the target polymer 2 (2.8 g). The molecular weight of the obtained polymer 2 was as follows.

Weight average molecular weight (Mw) = 47,380
Number average molecular weight (Mn) = 37,904
Dispersity (Mw/Mn)=1.25

[Element Examples and Comparative Examples]
[Example II-1]
An organic electroluminescent device was fabricated in the following manner.
A 50 nm thick indium tin oxide (ITO) transparent conductive film (Geomatec Co., Ltd., sputtered film) was deposited on a glass substrate and patterned into 2 mm wide stripes using normal photolithography and hydrochloric acid etching to form an anode. The substrate with the ITO pattern thus formed was ultrasonically cleaned with a surfactant aqueous solution, rinsed with ultrapure water, ultrasonically cleaned with ultrapure water, and rinsed with ultrapure water, in that order, then dried with compressed air, and finally cleaned with ultraviolet ozone.

A composition for forming a hole injection layer was prepared by dissolving 3.0% by weight of a hole-transporting polymer compound, which is a polymer of the present invention represented by the following formula (P-1) (Polymer 2 synthesized in Example I-2), and 0.6% by weight of an oxidizing agent (PD-1) shown in the structure below in ethyl benzoate.

This composition for forming a hole injection layer was spin-coated onto the above-mentioned substrate in the atmosphere and dried on a hot plate in the atmosphere at 240°C for 30 minutes to form a uniform thin film with a thickness of 60 nm, which served as the hole injection layer.

Next, a composition for forming a hole transport layer was prepared by dissolving 2.0% by weight of a charge transporting polymer compound represented by the following formula (HT-1) in cyclohexylbenzene.
This composition for forming a hole transport layer was spin-coated in a nitrogen glove box onto the substrate on which the hole injection layer had been coated, and dried on a hot plate in the nitrogen glove box at 230°C for 30 minutes to form a uniform thin film with a thickness of 25 nm, which was used as a hole transport layer.

Next, 3.0% by weight of the light-emitting layer material (H-1), 3.0% by weight of the light-emitting layer material (H-2), and 0.9% by weight of the light-emitting layer material (D-1) shown below were dissolved in cyclohexylbenzene to prepare a composition for forming the light-emitting layer.

This composition for forming the light-emitting layer was spin-coated in a nitrogen glove box onto the substrate on which the hole transport layer had been coated, and then dried for 20 minutes at 120°C on a hot plate in the nitrogen glove box to form a uniform thin film with a thickness of 80 nm, which was used as the light-emitting layer.

The substrate on which the light-emitting layer had been formed was placed in a vacuum deposition apparatus, and the inside of the apparatus was evacuated until the pressure became 2×10 ⁻⁴ Pa or less.

Next, a compound represented by the following structural formula (HB-1) and 8-hydroxyquinolinolatolithium were co-deposited on the light-emitting layer in a weight ratio of 2:3 using a vacuum deposition method to form a hole-blocking layer with a thickness of 30 nm.

Next, a 2 mm wide striped shadow mask was attached to the substrate as a mask for cathode deposition so that it was perpendicular to the ITO stripes of the anode, and aluminum was heated using a molybdenum boat to vacuum-deposit an 80 nm thick aluminum layer to form the cathode.

In this manner, an organic electroluminescent device having a light-emitting area measuring 2 mm x 2 mm was obtained.

[Comparative Example II-1]
A device was prepared in the same manner as in Example II-1, except that a polymer represented by the following formula (P-2) was used instead of the polymer represented by formula (P-1) as the polymer compound used in the hole injection layer.

[Element Evaluation]
The organic electroluminescent devices of Example II-1 and Comparative Example II-1 were each energized to measure the voltage (V) and current efficiency (cd/A) when emitting light at a luminance of 1000 cd/ ^m2 . In addition, the time LT90 (hr) until the luminance of the device decreased to 90% of the initial luminance when a current density of 40 mA/ ^cm2 was continuously applied to the device was measured.

Table 2 shows the voltage difference between Example II-1 and Comparative Example II-1 (voltage of Example II-1 - voltage of Comparative Example II-1) as the voltage difference, the relative value of the current efficiency of Example II-1 when the current efficiency of Comparative Example II-1 is set to 1 as the relative current efficiency, and the relative value of the LT90 of Example II-1 when the LT90 of Comparative Example II-1 is set to 1 as the relative lifespan.

The results in Table 2 show that the organic electroluminescent device of the present invention has improved performance.

[Example II-2]
A composition for forming a hole injection layer was prepared by dissolving 3.0% by weight of a hole-transporting polymer compound, which is a polymer of the present invention represented by the following formula (P-3) (Polymer 1 synthesized in Example I-1) and 0.6% by weight of an oxidizing agent (PD-1), in ethyl benzoate.

This composition for forming a hole injection layer was spin-coated onto the above-mentioned substrate in the atmosphere and dried on a hot plate in the atmosphere at 240°C for 30 minutes to form a uniform thin film with a thickness of 60 nm, which served as the hole injection layer.

Next, a hole transport layer was formed in the same manner as in Example 1, and then 3.6% by weight of (H-1), 2.4% by weight of (H-2), and 0.9% by weight of (D-1) were dissolved in cyclohexylbenzene as materials for the light-emitting layer to prepare a composition for forming the light-emitting layer.
This composition for forming an emissive layer was spin-coated in a nitrogen glove box onto the substrate on which the hole transport layer had been coated, and dried on a hot plate in the nitrogen glove box at 120°C for 20 minutes to form a uniform thin film with a thickness of 80 nm, which was used as the emissive layer.

After forming the light-emitting layer, the element was prepared in the same manner as in Example II-1.

[Comparative Example II-2]
A device was prepared in the same manner as in Example II-2, except that the polymer represented by formula (P-2) was used instead of the polymer represented by formula (P-3) as the polymer compound used in the hole injection layer.

[Element Evaluation]
The organic electroluminescent devices of Example II-2 and Comparative Example II-2 were energized, and the voltage (V) and current efficiency (cd/A) were measured when the devices were made to emit light at a luminance of 1000 cd/ ^m2 . In addition, the time (LT90) at which the luminance of the device decreased to 90% of the initial luminance when a current density of 40 mA/ ^cm2 was continuously applied to the devices was measured. Table 3 shows the voltage difference, relative current efficiency, and relative life obtained in the same manner as in Example II-1 and Comparative Example II-1.

The results in Table 3 show that the organic electroluminescent device of the present invention has improved performance.

[Example II-3]
After forming a hole injection layer and a hole transport layer in the same manner as in Example II-2, a composition for forming a light emitting layer was prepared by dissolving 4.0% by weight of the light emitting layer material (H-3) shown below and 0.2% by weight of (D-2) in cyclohexylbenzene as materials for the light emitting layer.

This composition for forming the light-emitting layer was spin-coated in a nitrogen glove box onto the substrate on which the hole transport layer had been coated, and then dried on a hot plate in the nitrogen glove box at 120°C for 20 minutes to form a uniform thin film with a thickness of 40 nm, which was used as the light-emitting layer.

After forming the light-emitting layer, the element was prepared in the same manner as in Example II-1.

[Comparative Example II-3]
A device was prepared in the same manner as in Example II-3, except that the polymer represented by formula (P-2) was used instead of the polymer represented by formula (P-3) as the polymer compound used in the hole injection layer.

[Element Evaluation]
A current was applied to each of the organic electroluminescent devices of Example II-3 and Comparative Example II-3, and the time LT90 (hr) until the luminance of the device decreased to 90% of the initial luminance when the current was continuously applied to the device at a current density of 20 mA/ ^cm2 was measured.
Table 4 shows the relative values of LT90 of Example II-3 when the LT90 of Comparative Example II-3 is taken as 1, as the relative life.

The results in Table 4 show that the organic electroluminescent device of the present invention has improved performance.

[Example II-4]
After the substrate was washed in the same manner as in Example II-1, a composition for forming a hole injection layer was prepared by dissolving 3.0% by weight of a hole transporting polymer compound represented by the following formula (P-4) and 0.6% by weight of an oxidizing agent (PD-1) in ethyl benzoate.

This composition for forming a hole injection layer was spin-coated onto the above-mentioned substrate in the atmosphere and dried on a hot plate in the atmosphere at 240°C for 30 minutes to form a uniform thin film with a thickness of 40 nm, which served as the hole injection layer.

Next, 3.0% by weight of the polymer of the present invention represented by the formula (P-1) was dissolved in cyclohexylbenzene to prepare a composition for forming a hole transport layer.
This composition for forming a hole transport layer was spin-coated in a nitrogen glove box onto the substrate on which the hole injection layer had been coated, and dried on a hot plate in the nitrogen glove box at 230°C for 30 minutes to form a uniform thin film with a thickness of 40 nm, which was used as a hole transport layer.

Next, 5.0% by weight of the light-emitting layer material (H-4) shown below and 0.75% by weight of the above-mentioned (D-1) were dissolved in cyclohexylbenzene to prepare a composition for forming the light-emitting layer.

This composition for forming the light-emitting layer was spin-coated in a nitrogen glove box onto the substrate on which the hole transport layer had been applied, and then dried for 20 minutes at 120°C on a hot plate in the nitrogen glove box to form a uniform thin film with a thickness of 60 nm, which was used as the light-emitting layer.

After forming the light-emitting layer, the element was fabricated in the same manner as in Example II-1.

[Comparative Example II-4]
A device was prepared in the same manner as in Example 3, except that the polymer represented by formula (P-2) was used instead of the polymer represented by formula (P-1) as the polymer compound used in the hole transport layer.

[Element Evaluation]
The organic electroluminescent devices of Example II-4 and Comparative Example II-4 were energized, and the time LT80 (hr) until the luminance of the device decreased to 80% of the initial luminance when the device was continuously energized at a current density of 60 mA/ ^cm2 was measured. Table 5 shows the relative value of LT80 of Example II-4 when LT80 of Comparative Example II-4 is set to 1 as the relative life.

The results in Table 5 show that the organic electroluminescent device of the present invention has improved performance.

Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2019-226582 filed on December 16, 2019, and Japanese Patent Application No. 2020-017140 filed on February 4, 2020, the entire contents of which are incorporated by reference.

REFERENCE SIGNS LIST 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light-emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Electron injection layer 9 Cathode 10 Organic electroluminescent device

Claims (16)

A polymer comprising a repeating unit represented by the following formula (1):

In formula (1), G represents a N atom.
^Ar2 represents a divalent aromatic hydrocarbon group which may have a substituent, a divalent aromatic heterocyclic group which may have a substituent, or a divalent group in which two or more groups selected from a divalent aromatic hydrocarbon group which may have a substituent and a divalent aromatic heterocyclic group which may have a substituent are linked together directly or via a linking group.
A is a structure containing a specific 6-membered heteroaromatic ring having a nitrogen atom and is represented by formula (1)-2.
In formula (1)-2, Ar ¹ represents a divalent aromatic hydrocarbon group which may have a substituent.
^Ar3 and ^Ar4 each independently represent an aromatic hydrocarbon group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or a monovalent group in which two or more groups selected from an aromatic hydrocarbon group which may have a substituent and an aromatic heterocyclic group which may have a substituent are linked together directly or via a linking group.
X and Y each independently represent a C atom or a N atom. When X or Y is a C atom, it may have a substituent.
"-*" is the site that bonds to G in formula (1). The polymer according to claim 1 , wherein the repeating unit represented by the formula (1) is a repeating unit represented by any one of the following formulas (2)-1 to (2)-3:

In the formulas (2)-1 to (2)-3, A is the same as A in the above formula (1).
Q represents -C(R ⁵ )(R ⁶ )-, -N(R ⁷ )- or -C(R ¹¹ )(R ¹² )-C(R ¹³ )(R ¹⁴ )-.
R ¹ to R ⁴ each independently represent an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or an aralkyl group which may have a substituent.
R ⁵ to R ⁷ and R ¹¹ to R ¹⁴ each independently represent an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aralkyl group which may have a substituent, or an aromatic hydrocarbon group which may have a substituent.
a and b each independently represents an integer of 0 to 4.
c1 to c5 each independently represents an integer of 0 to 3.
However, at least one of c3 and c5 is 1 or more.
d1 to d4 each independently represents an integer of 1 to 4.
When a plurality of R ¹ , R ² , R ³ and R ⁴ are present in the repeating unit, R ¹ , R ² , R ³ and R ⁴ may be the same or different. The polymer according to claim 1 or 2 , further comprising a repeating unit represented by any one of the following (3)-1 to (3)-3:

In formulas (3)-1 to (3)-3, ^Ar7 represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent, excluding the group containing a specific 6-membered heteroaromatic ring having a nitrogen atom, which is the structure A represented by formula (1)-2.
Q represents -C(R ⁵ )(R ⁶ )-, -N(R ⁷ )- or -C(R ¹¹ )(R ¹² )-C(R ¹³ )(R ¹⁴ )-.
R ¹ to R ⁴ each independently represent an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or an aralkyl group which may have a substituent.
R ⁵ to R ⁷ and R ¹¹ to R ¹⁴ each independently represent an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aralkyl group which may have a substituent, or an aromatic hydrocarbon group which may have a substituent.
a and b each independently represents an integer of 0 to 4.
c1 to c5 each independently represents an integer of 0 to 3.
However, at least one of c3 and c5 is an integer of 1 or more.
d1 to d4 each independently represents an integer of 1 to 4.
When a plurality of R ¹ , R ² , R ³ and R ⁴ are present in the repeating unit, R ¹ , R ² , R ³ and R ⁴ may be the same or different. the polymer has a crosslinkable group as a substituent,
The polymer according to any one of claims 1 to 3 , wherein the crosslinkable group is a cyclobutene ring condensed with an aromatic ring, or a group containing an alkenyl group bonded to an aromatic ring . The polymer according to any one of claims 1 to 4 , wherein the polymer has a weight average molecular weight (Mw) of 10,000 or more and a dispersity (Mw/Mn) of 3.5 or less. The polymer according to any one of claims 1 to 5 , wherein Ar ¹ in the formula (1)-2 is a group in which two or more divalent aromatic hydrocarbon groups which may have a substituent are linked together. The polymer according to any one of claims 1 to 6 , wherein Ar ¹ in the formula (1)-2 contains at least one benzene ring linked at the 1- and 3-positions. Ar in the formula (1-2) ¹ is selected from the following Schemes 2-1 and 2-2. The polymer according to any one of claims 1 to 5.

("-*" represents a bonding site between G and the specific 6-membered heteroaromatic ring of formula (1)-2. Either of the two "-*"s may be bonded to G, and may be bonded to the specific 6-membered heteroaromatic ring.) A composition for organic electroluminescent devices containing the polymer according to any one of claims 1 to 8. A composition for forming a hole transport layer or a hole injection layer, comprising the polymer according to any one of claims 1 to 8. A method for producing an organic electroluminescence device having an anode, a cathode, and an organic layer between the anode and the cathode on a substrate, the method including a film-forming step of forming at least one of the organic layers by a wet film-forming method using the composition for organic electroluminescence devices described in claim 9. The method for manufacturing an organic electroluminescent device according to claim 11, wherein the organic layer formed in the film forming step is at least one of a hole injection layer and a hole transport layer. The method for producing an organic electroluminescence device according to claim 11 or 12, comprising a hole injection layer, a hole transport layer, and a light emitting layer between the anode and the cathode, and the organic layers formed in the film formation step are the hole injection layer, the hole transport layer, and the light emitting layer. An organic electroluminescent device comprising a layer containing the polymer according to any one of claims 1 to 8, or a polymer obtained by crosslinking said polymer. An organic EL display device comprising the organic electroluminescent element according to claim 14. An organic EL lighting device comprising the organic electroluminescent element according to claim 14.

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