JP7764685B2 - Charge transport material, ink composition, organic layer, organic electronics element, organic electroluminescence element, lighting device, display element, and display device - Google Patents

Description

Embodiments of the present invention relate to charge transport materials, ink compositions, organic layers, organic electronic elements, organic electroluminescence elements (also referred to as "organic EL elements"), lighting devices, display elements, and display devices.

Organic EL elements are attracting attention as large-area solid-state light sources, replacing incandescent lamps, gas-filled lamps, etc. They are also attracting attention as a promising self-emissive display to replace liquid crystal displays (LCDs) in the flat panel display (FPD) field, and commercialization is progressing.

Organic EL elements can be broadly divided into two types based on the organic materials used: low-molecular-weight organic EL elements, which use low-molecular-weight compounds, and high-molecular-weight organic EL elements, which use high-molecular-weight compounds. Manufacturing methods for organic EL elements can be broadly divided into dry processes, in which films are formed primarily in a vacuum system, and coating processes, in which films are formed using plate printing such as relief printing and intaglio printing, or plateless printing such as inkjet printing. Because coating processes allow for simple film formation, they are expected to be an essential method for future large-screen organic EL displays. For example, Patent Document 1 discloses an organic electronics material containing a polymer or oligomer with a structure that branches in three directions.

Furthermore, in order to improve the efficiency and/or extend the life of organic EL elements, attempts have been made to create multiple organic layers and separate the functions of each layer. For example, Patent Document 2 discusses a method of using a compound having at least one polymerizable group to create multiple organic layers.

International Publication No. 2010/140553 Japanese Patent Application Laid-Open No. 2006-279007

However, in coating processes, where multiple layers are created using an ink composition, there is a problem that when the upper layer is applied, the solvent contained in the upper layer dissolves the lower layer.

In view of the above, an object of one embodiment of the present invention is to provide a charge transport material and an ink composition that are suitable for coating processes and can form an organic layer that has excellent solvent resistance (hereinafter also referred to as "solvent resistance"). Another embodiment of the present invention is to provide an organic layer that is suitable for improving the properties of organic electronic elements. Another embodiment of the present invention is to provide an organic electronic element, organic EL element, display element, lighting device, and display device that have excellent properties.

With the above objective in mind, the inventors conducted extensive research and discovered that an organic layer formed using a charge-transporting material containing two or more polymers with different polymerizable substituents exhibits excellent solvent resistance.

Examples of embodiments of the present invention are listed below. The present invention is not limited to the following embodiments.

(1) A charge transport material containing a first polymer having a first polymerizable substituent and a second polymer having a second polymerizable substituent different from the first polymerizable substituent.

(2) The charge transport material according to (1), wherein the first polymerizable substituent has the following structure:

*-Ar-(CH ₂ ) _n -CH=CH ₂

In the above structure, * represents a bonding site to another structure, Ar represents a substituted or unsubstituted arylene group or heteroarylene group, and n is an integer of 0 to 20.

(3) The charge transport material according to (2), wherein Ar is a substituted or unsubstituted phenylene group.

(4) The charge transport material described in any one of (1) to (3), wherein the second polymerizable substituent includes at least one selected from the group consisting of a cyclopropyl group, a cyclobutyl group, a benzocyclobutenyl group, an epoxy group, and an oxetanyl group.

(5) The charge transport material described in any one of (1) to (4), wherein the second polymerizable substituent includes a benzocyclobutenyl group.

(6) An ink composition comprising the charge transport material described in any one of (1) to (5) and a solvent.

(7) An organic layer formed using the charge transport material described in any one of (1) to (5) or the ink composition described in (6).

(8) An organic electronics device comprising at least one organic layer described in (7).

(9) An organic electroluminescence device comprising at least one organic layer according to (7).

(10) The organic electroluminescence element according to (9), further comprising a flexible substrate.

(11) The organic electroluminescence element according to (9), further comprising a resin film substrate.

(12) A display element comprising the organic electroluminescence element described in any one of (9) to (11).

(13) A lighting device equipped with the organic electroluminescence element described in any one of (9) to (11).

(14) A display device equipped with an organic electroluminescence element described in any one of (9) to (11).

(15) A display device comprising the display device described in (14) and a liquid crystal element as a display means.

Embodiments of the present invention provide charge transport materials and ink compositions that are suitable for coating processes and can form organic layers with excellent solvent resistance. Furthermore, other embodiments of the present invention provide organic layers that are suitable for improving the properties of organic electronic devices. Other embodiments of the present invention provide organic electronic devices, organic EL devices, display devices, lighting devices, and display devices with excellent properties.

1 is a cross-sectional view schematically illustrating an example of an organic EL element according to an embodiment of the present invention.

The following describes embodiments of the present invention, but the present invention is not limited to these embodiments.

<Charge transport material>
The charge transport material according to this embodiment contains two or more charge transport polymers having different polymerizable substituents. Specifically, the charge transport material contains at least a charge transport polymer having a first polymerizable substituent (hereinafter also referred to as a "first polymer") and a charge transport polymer containing a second polymerizable substituent different from the first polymerizable substituent (hereinafter also referred to as a "second polymer"). The charge transport material may contain two or more first polymers and two or more second polymers. The charge transport material may further contain a charge transport polymer other than the first polymer and the second polymer. In other words, the charge transport material may further contain a charge transport polymer that does not contain a polymerizable substituent.

[Charge-transporting polymer]
The first polymer and the second polymer (hereinafter collectively referred to as "charge transporting polymers") will be described below.
Charge-transporting polymers have the ability to transport charges. The term "polymer" includes so-called "oligomers," which have a small number of repeating structural units.

[Structure of charge transport polymer]
Examples of partial structures contained in the charge transporting polymer include the following. The charge transporting polymer is not limited to polymers having the following partial structures. In the partial structures, "L" represents a divalent structural unit L, "T" represents a monovalent structural unit T, and "B" represents a trivalent or higher structural unit B. In the partial structures contained in the charge transporting polymer shown below, "*" in the formula represents a bonding site with another structural unit. In the partial structures below, multiple Ls may be the same structural unit or different structural units. The same applies to T and B.

Linear charge-transporting polymer

Branched charge-transporting polymer

(Structural unit L)
The structural unit L is a divalent structural unit having charge transport properties. The structural unit L is not particularly limited as long as it contains an atomic group having the ability to transport charge. For example, the structural unit L is selected from substituted or unsubstituted aromatic amine structures, carbazole structures, thiophene structures, fluorene structures, benzene structures, biphenylene structures, terphenylene structures, naphthalene structures, anthracene structures, tetracene structures, phenanthrene structures, dihydrophenanthrene structures, pyridine structures, pyrazine structures, quinoline structures, isoquinoline structures, quinoxaline structures, acridine structures, diazaphenanthrene structures, furan structures, pyrrole structures, oxazole structures, oxadiazole structures, thiazole structures, thiadiazole structures, triazole structures, benzothiophene structures, benzoxazole structures, benzoxadiazole structures, benzothiazole structures, benzothiadiazole structures, benzotriazole structures, and structures containing one or more of these. The aromatic amine structure is preferably a triarylamine structure, and more preferably a triphenylamine structure.

In one embodiment, from the viewpoint of obtaining excellent hole transport properties, the structural unit L is preferably selected from a substituted or unsubstituted aromatic amine structure, carbazole structure, thiophene structure, fluorene structure, benzene structure, pyrrole structure, and structures containing one or more of these, and more preferably from a substituted or unsubstituted aromatic amine structure, carbazole structure, thiophene structure, and structures containing one or more of these. From the viewpoint of obtaining excellent electron transport properties, the structural unit L is preferably selected from a substituted or unsubstituted fluorene structure, benzene structure, phenanthrene structure, pyridine structure, quinoline structure, and structures containing one or more of these.

Specific examples of the structural unit L include the following. The structural unit L is not limited to the following.

Each R independently represents a hydrogen atom or a substituent. All R may be hydrogen atoms. Furthermore, when R is a substituent, the substituent is preferably selected from the group consisting of -R ¹ , -OR ² , -SR ³ , -OCOR ⁴ , -COOR ⁵ , -SiR ⁶ R ⁷ R ⁸ , a halogen atom, and a group containing a polymerizable substituent as described below. ^{R 1} to R ⁸ independently represent a hydrogen atom; a linear, cyclic, or branched alkyl group having 1 to 22 carbon atoms; and an aryl or heteroaryl group having 2 to 30 carbon atoms. The alkyl group may be further substituted with an aryl or heteroaryl group having 2 to 20 carbon atoms, and the aryl or heteroaryl group may be further substituted with a linear, cyclic, or branched alkyl group having 1 to 22 carbon atoms. R is preferably a hydrogen atom, an alkyl group, an aryl group, or an alkyl-substituted aryl group. Ar represents an arylene group or heteroarylene group having 2 to 30 carbon atoms.

Specific examples of aromatic hydrocarbons contained in arylene groups and aromatic heterocycles contained in heteroarylene groups are the same as those described for aryl groups and heteroaryl groups.

The structural unit L may be, for example, the following structural unit (1):

In the structural unit (1) above, * represents a bonding site to another structure, and each Ar independently represents a substituted or unsubstituted aryl group or arylene group. Two Ar groups may also form a ring.

An aryl group is an atomic group formed by removing one hydrogen atom from an aromatic hydrocarbon. An arylene group is an atomic group formed by removing two hydrogen atoms from an aromatic hydrocarbon. Examples of aromatic hydrocarbons contained in aryl and arylene groups include benzene, naphthalene, anthracene, tetracene, fluorene, and phenanthrene.

Each Ar is preferably independently a substituted or unsubstituted phenyl group or phenylene group, a substituted or unsubstituted naphthyl group or naphthylene group, or a substituted or unsubstituted anthracenyl group or anthrylene group, and more preferably a substituted or unsubstituted phenyl group or phenylene group, or a substituted or unsubstituted naphthyl group or naphthylene group.

The above structural unit (1) is preferably a structural unit such as that shown in the following structural formula:

In the structural unit (1a), * denotes a bonding site to other structures, and R represents a hydrogen atom or a substituent. In the structural unit (1a), at least one R has an electron-withdrawing group as a substituent. The substituents in the structural unit (1a) are preferably each independently selected from the group consisting of -R ¹ , -OR ² , -SR ³ , -OCOR ⁴ , -COOR ⁵ , -SiR ⁶ R ⁷ R ⁸ , and a halogen atom. R ¹ to R ⁸ are each independently a hydrogen atom or at least one selected from the group consisting of linear, cyclic, or branched alkyl, alkenyl, alkynyl, and alkoxy groups having 1 to 22 carbon atoms, and aryl and heteroaryl groups having 2 to 30 carbon atoms. Furthermore, a heteroaryl group refers to an atomic group obtained by removing one hydrogen atom from an aromatic heterocycle. The aryl and heteroaryl groups may further have a substituent. The substituent is preferably a linear, cyclic or branched alkyl group having 1 to 22 carbon atoms, or a heteroaryl group having 2 to 30 carbon atoms.

Examples of electron-withdrawing groups include cyano, nitro, alkylsulfonyl groups (e.g., methylsulfonyl), arylsulfonyl groups (e.g., phenylsulfonyl), halogen atoms, and halogenated alkyl groups. Specific examples of aromatic heterocycles include pyridine, pyrazine, quinoline, isoquinoline, acridine, phenanthroline, furan, pyrrole, thiophene, carbazole, oxazole, oxadiazole, thiadiazole, triazole, benzoxazole, benzoxadiazole, benzothiadiazole, benzotriazole, and benzothiophene.

In the structural unit (1a), a1 represents an integer of 0 to 5, and a2 and a3 each independently represent an integer of 0 to 4. From the viewpoint of ease of bonding with other structures, a2 and a3 are preferably 0.

Furthermore, in the structural unit (1a), a1 is preferably 1 or greater, and R in (R) _a1 is preferably an electron-withdrawing group, for example, preferably containing a fluoro group or a fluoroalkyl group, which is an electron-withdrawing group, and is preferably at least one structural unit selected from the group consisting of the following structural units (1b) to (1e) containing a fluoro group or a perfluoromethyl group:

(Structural unit T)
The structural unit T is a monovalent structural unit that constitutes the terminal portion of the charge transporting polymer. The structural unit T is not particularly limited and may be selected from, for example, a substituted or unsubstituted aromatic hydrocarbon structure, an aromatic heterocyclic structure, and a structure containing one or more of these. The structural unit T may have the same structure as the structural unit L. In one embodiment, from the viewpoint of imparting durability without reducing charge transportability, the structural unit T is preferably a substituted or unsubstituted aromatic hydrocarbon structure, and more preferably a substituted or unsubstituted benzene structure. The structural unit T may have the same structure as the structural unit L except for the valence, or may have a different structure.

Specific examples of structural unit T include the following. Structural unit T is not limited to the following.

In the structural unit (2-1) above, * represents a bonding site with other structures, and each R independently represents a halogen atom or a halogenated alkyl group. The halogenated alkyl group preferably has 1 to 4 carbon atoms, and more preferably 1 or 2. The halogenated alkyl group is preferably a perhalogenated alkyl group, and more preferably a fluoroalkyl group or perfluoroalkyl group in which the halogen atom is a fluorine atom.

The two R's may be the same or different, but are preferably the same. It is more preferable that each R is independently a fluoroalkyl group, and even more preferable that each R is a perfluoroalkyl group having 1 to 4 carbon atoms.

In the structural unit (2-2) above, * indicates a bonding site with other structures, and each R independently represents a hydrogen atom or a linear alkyl group, with at least one R being a linear alkyl group. The linear alkyl group preferably has 4 to 20 carbon atoms, more preferably 4 to 16, and even more preferably 4 to 12.

The above structural unit (2-1) is preferably, for example, the following structural unit (2a-1):

In the structural unit (2a-1), m and n each independently represent an integer from 1 to 4. m and n may be the same or different, and are preferably the same.

The structural unit (2a-1) is particularly preferably the following structural unit (2b-1):

The above structural unit (2-2) is preferably, for example, the following structural unit (2a-2):

In the structural unit (2a-2), n represents an integer of 4 to 20. From the viewpoint of improving life characteristics, n is preferably 4 to 7. From the viewpoint of improving solubility, n is preferably 9 to 20. Taking into consideration the balance between improving life characteristics and improving solubility, n may be 4 to 16 or 4 to 12.

The structural unit (2a-2) is particularly preferably the following structural unit (2b-2):

(Structural unit B)
The structural unit B is a trivalent or higher structural unit constituting a branched portion when the charge-transporting polymer has a branched structure. From the viewpoint of improving the durability of an organic electronic device, the structural unit B is preferably a hexavalent or lower structural unit, more preferably a trivalent or tetravalent structural unit. The structural unit B is preferably a unit having charge transport properties. For example, from the viewpoint of improving the durability of an organic electronic device, the structural unit B is selected from a substituted or unsubstituted aromatic amine structure, a carbazole structure, a fused polycyclic aromatic hydrocarbon structure, and a structure containing one or more of these. The structural unit B may have the same structure as the structural unit L or a different structure other than the valence, and may also have the same structure as the structural unit T or a different structure.

Specific examples of structural unit B include the following. Structural unit B is not limited to the following.

W represents a trivalent linking group, for example, an arenetriyl group or heteroarenetriyl group having 2 to 30 carbon atoms. An arenetriyl group is an atomic group formed by removing three hydrogen atoms from an aromatic hydrocarbon. A heteroarenetriyl group is an atomic group formed by removing three hydrogen atoms from an aromatic heterocycle. Each Ar independently represents a divalent linking group, for example, an arylene group or heteroarylene group having 2 to 30 carbon atoms. Ar is preferably an arylene group, more preferably a phenylene group. Y represents a divalent linking group, for example, a divalent group formed by removing one additional hydrogen atom from a group having one or more hydrogen atoms among the substituents listed as R in the structural unit L (excluding groups containing polymerizable substituents). Z represents a carbon atom, a silicon atom, or a phosphorus atom. In the structural unit, the fused ring, W, Y, and Ar may have a substituent, and examples of the substituent include the substituents exemplified for R in the structural unit L.

Structural unit B may be, for example, the following structural units (3-1) and (3-2) (hereinafter collectively referred to as structural unit (3)).

In the structural units (3-1) and (3-2), * represents a bonding site to another structure, Ar represents a substituted or unsubstituted arylene group, and R represents a hydrogen atom or a substituent. The substituents in R in the structural units (3-1) and (3-2) are preferably each independently selected from the group consisting of -R ¹ , -OR ² , -SR ³ , -OCOR ⁴ , -COOR ⁵ , -SiR ⁶ R ⁷ R ⁸ , and a halogen atom. R ¹ to R ⁸ are each independently a hydrogen atom or at least one selected from the group consisting of linear, cyclic, or branched alkyl, alkenyl, alkynyl, and alkoxy groups having 1 to 22 carbon atoms, and aryl and heteroaryl groups having 2 to 30 carbon atoms. The aryl and heteroaryl groups may further have a substituent. The substituent is preferably a linear, cyclic or branched alkyl group having 1 to 22 carbon atoms, or a heteroaryl group having 2 to 30 carbon atoms.

In the structural units (3-1) and (3-2), b2 and b3 each independently represent an integer from 0 to 4, and b5 and b6 each independently represent an integer from 0 to 3. From the standpoint of ease of bonding with other structures, it is preferable that b2, b3, b5, and b6 are 0.

The above structural units (3-1) and (3-2) are preferably structural units such as those shown in the following structural formulas.

In the structural units (3a-1) and (3a-2), * represents a bonding site to other structures, and R represents a hydrogen atom or a substituent, and the substituent is preferably each independently selected from the group consisting of the above-mentioned -R ¹ , -OR ² , -SR ³ , -OCOR ⁴ , -COOR ⁵ , -SiR ⁶ R ⁷ R ⁸ and a halogen atom.

In addition, in the structural units (3a-1) and (3a-2), b1 to b4 each independently represent an integer from 0 to 4, and b5 and b6 each independently represent an integer from 0 to 3. From the viewpoint of ease of bonding with other structures, it is preferable that b1 to b6 are 0.

The above structural unit (3a-1) is preferably, for example, the following structural unit (3b-1):

The structural unit (3a-2) is preferably, for example, the following structural unit (3b-2):

[Content of each structural unit]

From the viewpoint of adjusting the energy level, the content of structural unit (1) is preferably 50 mol% or more, more preferably 75 mol% or more, and even more preferably 90 mol% or more, based on the total amount of structural unit L. The upper limit of the content of structural unit (1) is 100 mol%.

From the viewpoint of obtaining sufficient charge transport properties, the content of structural unit L contained in the charge-transporting polymer is preferably 10 mol% or more, more preferably 15 mol% or more, and even more preferably 20 mol% or more, based on all structural units. Furthermore, taking into account structural unit T and structural unit B, the content of structural unit L is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less.

From the viewpoint of obtaining good charge transport properties, the content of structural unit (2) is preferably 50 mol % or more, more preferably 75 mol % or more, and even more preferably 90 mol % or more, based on the total amount of structural unit B. The upper limit of the content of structural unit (2) is 100 mol %.

The content of structural unit B contained in the charge-transporting polymer is preferably 1 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more, based on all structural units, from the viewpoint of obtaining an organic layer with excellent solvent resistance. Furthermore, the content of trivalent or higher structural units is preferably 50 mol% or less, more preferably 40 mol% or less, even more preferably 30 mol% or less, and particularly preferably 20 mol% or less, from the viewpoint of suppressing an increase in viscosity and smoothly synthesizing the charge-transporting polymer, or from the viewpoint of obtaining sufficient charge transport properties.

From the viewpoint of achieving good storage stability of the liquid composition, the content of structural unit (3) is preferably 85 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more, based on the total amount of monovalent structural units. The upper limit of the content of structural unit (3) is 100 mol%.

The content of structural units T contained in the charge-transporting polymer is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, based on all structural units, from the viewpoints of the curability and solubility of the charge-transporting polymer and improving the properties of organic electronic devices. Furthermore, the content of monovalent structural units is preferably 60 mol% or less, more preferably 55 mol% or less, and even more preferably 50 mol% or less, from the viewpoint of obtaining sufficient charge transport properties.

The molar ratio of the content of structural unit L, structural unit B, and structural unit T contained in the charge-transporting polymer takes into consideration the balance of the effects of each structural unit, and is preferably structural unit L:structural unit B:structural unit T = 100:5-70:50-150, more preferably 100:10-60:60-135, and even more preferably 100:15-50:80-120.

(number average molecular weight)
The number average molecular weight of the charge transporting polymer can be adjusted appropriately taking into consideration solubility in a solvent, film-forming properties, etc. From the viewpoint of excellent charge transport properties, the number average molecular weight is preferably 500 or more, more preferably 1,000 or more, and even more preferably 2,000 or more. Furthermore, from the viewpoint of maintaining good solubility in a solvent and facilitating preparation of an ink composition, the number average molecular weight is preferably 1,000,000 or less, more preferably 100,000 or less, and even more preferably 50,000 or less.

(Weight average molecular weight)
The weight-average molecular weight of the charge-transporting polymer can be adjusted appropriately in consideration of solubility in a solvent, film-forming properties, etc. From the viewpoint of excellent charge transport properties, the weight-average molecular weight is preferably 1,000 or more, more preferably 5,000 or more, and even more preferably 10,000 or more. Furthermore, from the viewpoint of maintaining good solubility in a solvent and facilitating preparation of an ink composition, the weight-average molecular weight is preferably 1,000,000 or less, more preferably 700,000 or less, and even more preferably 400,000 or less.

The number average molecular weight and weight average molecular weight can be measured by gel permeation chromatography (GPC) using a calibration curve of standard polystyrene.

(Method for producing charge transport polymer)
Charge-transporting polymers can be produced by various synthesis methods, and are not particularly limited. For example, known coupling reactions such as Suzuki coupling, Negishi coupling, Sonogashira coupling, Stille coupling, and Buchwald-Hartwig coupling can be used. Suzuki coupling is a cross-coupling reaction between an aromatic boronic acid derivative and an aromatic halide using a Pd catalyst. According to Suzuki coupling, charge-transporting polymers can be easily produced by bonding desired aromatic rings together.

In the coupling reaction, catalysts such as Pd(0) compounds, Pd(II) compounds, and Ni compounds are used. It is also possible to use catalyst species generated by mixing precursors such as tris(dibenzylideneacetone)dipalladium(0) and palladium(II) acetate with a phosphine ligand. Regarding methods for synthesizing charge-transporting polymers, the description in International Publication No. 2010/140553, for example, can be cited.

[First polymer]
(Structural unit (4))
The first polymer is the charge-transporting polymer described above, which includes a structural unit (4) having a first polymerizable substituent. The structural unit (4) may be a monovalent structural unit having one bonding site with another structure, a divalent structural unit having two bonding sites with another structure, or a trivalent or higher structural unit having three or more bonding sites with another structure. However, from the viewpoint of achieving both the curability and charge transportability of the charge-transporting polymer, it is preferable that the first polymerizable substituent be included in a monovalent structural unit.

[First polymerizable substituent]
The first polymerizable substituent has the ability to harden through a polymerization reaction and change the solubility in a solvent. The term "polymerizable substituent" refers to a functional group that can form intramolecular and/or intermolecular bonds with each other by applying heat and/or light.

Examples of the first polymerizable substituent include groups having a carbon-carbon unsaturated bond (e.g., vinyl, allyl, butenyl, ethynyl, acryloyl, acryloyloxy, acryloylamino, methacryloyl, methacryloyloxy, methacryloylamino, vinyloxy, and vinylamino groups), groups having a small ring (e.g., cycloalkyl groups such as cyclopropyl, cyclobutyl, and cyclopentyl; cycloalkenyl groups such as cyclopropenyl and cyclobutenyl; fused ring groups such as benzocyclobutenyl; cyclic ether groups such as epoxy (oxiranyl) and oxetanyl; diketene groups; episulfide groups; lactone groups; lactam groups), and groups having a heterocycle containing a heteroatom (e.g., furanyl, pyrrolyl, thiophenyl, and silolyl). As the polymerizable substituent, ethynyl, vinyl, acryloyl, methacryloyl, cyclobutenyl, epoxy, and oxetanyl groups are particularly preferred, with vinyl, cyclobutenyl, epoxy, and oxetanyl groups being more preferred from the viewpoints of transparency and organic electronic device properties, and epoxy and oxetanyl groups being even more preferred from the viewpoint of reactivity. Furthermore, the above-mentioned groups having a carbon-carbon unsaturated bond, groups having a small ring, and groups having a heterocycle with a heteroatom may have a substituent, and preferably have an alkyl group, for example.

From the viewpoint of increasing the degree of freedom of the first polymerizable substituent and facilitating the polymerization reaction, the main skeleton of the charge-transporting polymer and the polymerizable substituent may be linked by an alkylene chain. Furthermore, for example, when an organic layer (described below) is formed on an electrode, from the viewpoint of improving affinity with a hydrophilic electrode such as ITO (indium oxide-tin oxide), the main skeleton and the polymerizable substituent may be linked by a hydrophilic chain such as an ethylene glycol chain or a diethylene glycol chain. Furthermore, from the viewpoint of facilitating the preparation of the monomer used to introduce the polymerizable substituent, the charge-transporting polymer may have an ether bond or an ester bond at the terminal end of the alkylene chain and/or hydrophilic chain, i.e., at the connection between these chains and the polymerizable substituent, and/or at the connection between these chains and the skeleton of the charge-transporting polymer.

By introducing the first polymerizable substituent into the terminal portion of the charge-transporting polymer, it is possible to achieve both the curability and charge transport properties of the charge-transporting polymer, which is preferable.

In this specification, the chain with the highest degree of polymerization among the various chains in one molecule of the charge-transporting polymer is considered to be the main chain. A side chain is a chain different from the main chain of the charge-transporting polymer and has at least one structural unit. Anything other than the side chain is considered to be a substituent. A terminal substituent attached to the main chain and/or side chain that is a polymerizable substituent is referred to as a "polymerizable end group." As described above, it is preferable for a polymerizable end group to be introduced into the charge-transporting polymer. In one embodiment, for example, the charge-transporting material may be configured so that the first polymer contains a first polymerizable end group and the second polymer contains a second polymerizable end group different from the first polymerizable end group.

From the viewpoint of transparency and the properties of organic electronic devices, the first polymerizable substituent is a group having a carbon-carbon unsaturated bond (e.g., a vinyl group, an allyl group, a butenyl group, an ethynyl group, an acryloyl group, an acryloyloxy group, an acryloylamino group, a methacryloyl group, a methacryloyloxy group, a methacryloylamino group, a vinyloxy group, a vinylamino group, etc.).

Specific examples of structural unit (4) include, but are not limited to, the following structural unit (4a), which is a monovalent structural unit.

*-Ar-(CH ₂ ) _n -CH=CH ₂ (4a)

In the structural unit (4a) above, * denotes a bonding site with another structure, Ar represents a substituted or unsubstituted arylene group or heteroarylene group, and n is an integer from 0 to 20. A heteroarylene group refers to an atomic group formed by removing two hydrogen atoms from an aromatic heterocycle. Specific examples of aromatic hydrocarbons include benzene, naphthalene, anthracene, tetracene, fluorene, and phenanthrene. Preferred arylene groups are phenylene and naphthylene groups, with phenylene being more preferred. Specific examples of aromatic heterocycles include pyridine, pyrazine, quinoline, isoquinoline, acridine, phenanthroline, furan, pyrrole, thiophene, carbazole, oxazole, oxadiazole, thiadiazole, triazole, benzoxazole, benzoxadiazole, benzothiadiazole, benzotriazole, and benzothiophene. From the viewpoint of improving life characteristics, n is preferably 0 to 8, more preferably 0 to 6, even more preferably 0 to 3, and particularly preferably 0 or 1. From the viewpoint of improving solubility, n is preferably 4 to 20, more preferably 4 to 16, even more preferably 4 to 12, and particularly preferably 4 to 8.

The structural unit (4a) has excellent reactivity, allowing the curing reaction of the charge-transporting polymer to proceed efficiently. Furthermore, by including a polymerizable substituent in the charge-transporting polymer that contributes to the curing reaction, an ink composition with excellent storage stability, as described below, can be obtained. In terms of obtaining an organic electronics device with better life characteristics, it is preferable that the value of n in the structure (4a) is small. On the other hand, in terms of obtaining excellent solubility, it is preferable that the value of n in the structural unit (1a) is large.

Furthermore, the structural unit (4a) preferably has a structure such as that shown in the following structural formula:

Furthermore, the first polymer may contain only one type of such structural unit, or two or more types.

[Structural unit content]
As described above, the structural unit (4) is preferably introduced into the terminal portion of the charge-transporting polymer, and in this case, the content of the structural unit (4) is preferably 1 to 50 mol % based on the structural unit constituting the polymer terminal. From the viewpoint of improving the solvent resistance of the organic layer, the content of the structural unit is preferably 2 mol % or more, more preferably 3 mol % or more, even more preferably 5 mol % or more, and particularly preferably 10 mol % or more. From the viewpoint of the charge transport property of the charge-transporting polymer, the content of the structural unit is preferably 50 mol % or less, more preferably 45 mol % or less, and even more preferably 40 mol % or less. To obtain high charge transport property, the content may be 35 mol % or less, or may be 30 mol % or less.

From the viewpoint of efficiently curing the charge-transporting polymer, the proportion of the first polymerizable substituent contained in structural unit (4) is preferably 0.1 mol % or more, more preferably 1 mol % or more, and even more preferably 3 mol % or more, based on the structural units constituting the polymer terminals. Furthermore, from the viewpoint of obtaining good charge-transporting properties, the proportion of the first polymerizable substituent is preferably 70 mol % or less, more preferably 60 mol % or less, and even more preferably 50 mol % or less, based on all structural units. Here, "proportion of polymerizable substituent" refers to the proportion of structural units having a polymerizable substituent.

From the viewpoint of contributing to changes in solubility, it is preferable that the first polymerizable substituent be contained in a large amount in the charge-transporting polymer. On the other hand, from the viewpoint of not interfering with charge transportability, it is preferable that the first polymerizable substituent be contained in a small amount in the charge-transporting polymer. The content of the polymerizable substituent can be set appropriately taking these factors into consideration.

For example, the number of polymerizable substituents per molecule of the charge-transporting polymer is preferably 2 or more, more preferably 3 or more, from the viewpoint of achieving sufficient change in solubility. Furthermore, the number of polymerizable substituents is preferably 1,000 or less, more preferably 500 or less, from the viewpoint of maintaining charge-transporting properties.

The number of polymerizable substituents per molecule of the charge-transporting polymer can be determined as an average value using the amount of polymerizable substituents (for example, the amount of monomer having a polymerizable substituent) used to synthesize the charge-transporting polymer, the amount of monomer corresponding to each structural unit, the weight-average molecular weight of the charge-transporting polymer, etc. The number of polymerizable substituents can also be calculated as an average value using the ratio of the integral value of the signal derived from the polymerizable substituent to the integral value of the entire spectrum in the ¹ H NMR (nuclear magnetic resonance) spectrum of the charge-transporting polymer, the weight-average molecular weight of the charge-transporting polymer, etc. For simplicity, when the amount of charge is known, it is preferable to use the value determined using the amount of charge.

[Second Polymer]
(Structural unit (5))
The second polymer is the charge-transporting polymer described above, and includes a structural unit (5) having a second polymerizable substituent different from the first polymerizable substituent. The structural unit (5) having the second polymerizable substituent contained in the second polymer may be any of a monovalent structural unit having one bonding site with another structure, a divalent structural unit having two bonding sites with another structure, and a trivalent or higher structural unit having three or more bonding sites with another structure. However, from the viewpoint of achieving both the curability and charge transportability of the charge-transporting polymer, it is preferable that the second polymerizable substituent be contained in a monovalent structural unit.

[Second Polymerizable Substituent]
The second polymerizable substituent can be any of the polymerizable substituents exemplified as the first polymerizable substituent described above (provided that the first polymerizable substituent and the second polymerizable substituent are different from each other). For example, the second polymer can be a group having a small ring (e.g., a cyclic alkyl group such as a cyclopropyl group or a cyclobutyl group; a fused ring group such as a benzocyclobutenyl group; a cyclic ether group such as an epoxy group or an oxetanyl group; a diketene group; an episulfide group; a lactone group; a lactam group, etc.). From the viewpoint of curability by heating, a cyclopropyl group, a cyclobutyl group, a benzocyclobutenyl group, an epoxy group, or an oxetanyl group is more preferred, and a benzocyclobutenyl group, which is relatively stable and can be crosslinked by heating alone, is most preferred.

[Structural unit content]
The content of the structural unit (5) is preferably 1 to 50 mol% based on the structural unit constituting the polymer terminal. From the viewpoint of improving the solvent resistance of the organic layer, the content of the structural unit is preferably 2 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, and particularly preferably 10 mol% or more. From the viewpoint of the charge transport property of the charge transport polymer, the content of the structural unit is preferably 50 mol% or less, more preferably 45 mol% or less, and even more preferably 40 mol% or less. To obtain high charge transport property, the content may be 35 mol% or less, or may be 30 mol% or less.

From the viewpoint of efficiently curing the charge-transporting polymer, the proportion of the second polymerizable substituent contained in structural unit (5) is preferably 0.1 mol % or more, more preferably 1 mol % or more, and even more preferably 3 mol % or more, based on the structural units constituting the polymer terminals. Furthermore, from the viewpoint of obtaining good charge-transporting properties, the proportion of the polymerizable substituent is preferably 70 mol % or less, more preferably 60 mol % or less, and even more preferably 50 mol % or less, based on all structural units.

While the present embodiment has been described using examples of a first polymer and a second polymer, the present invention is not limited to these examples. The charge-transporting material may contain two or more charge-transporting polymers having different polymerizable substituents, such as the first polymer and the second polymer. The ratio of the two or more charge-transporting polymers contained in the charge-transporting material is not particularly limited. For example, the charge-transporting material may contain equal amounts of the first polymer and the second polymer. This configuration allows for an organic layer with superior solvent resistance compared to a charge-transporting material containing only one charge-transporting polymer with a polymerizable substituent, and allows for easy incorporation of multiple organic layers into organic electronic devices. Furthermore, compared to a charge-transporting material containing a single charge-transporting polymer having two polymerizable substituents, the charge-transporting material of the present embodiment allows for easy incorporation of multiple organic layers into organic electronic devices because it is not necessary to consider the compatibility and blending ratio of the two polymerizable substituents when synthesizing the charge-transporting polymer. This allows for easy incorporation of multiple organic layers into organic electronic devices.

[Optional ingredients]
Additives such as polymerization initiators, antioxidants, anti-yellowing agents, ultraviolet absorbers, visible light absorbers, colorants, plasticizers, stabilizers, and fillers may be added to the organic electronics device within a range that does not adversely affect the properties of the device. Furthermore, an ionic compound may be mixed with the charge transport material to improve the luminous efficiency and lifespan of the organic EL device. By mixing and using an ionic compound, the electrical conductivity, stability, and lifespan of the organic EL device can be improved.

(ionic compounds)
Here, in this specification and the like, the term "ionic compound" refers to a compound consisting of a cation and an anion. From the viewpoint of electrical conductivity and stability, an anion containing an electron-withdrawing organic substituent is preferred, and examples thereof include halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, alkylsulfonyl groups substituted with alkyls such as cyano groups, thiocyano groups, nitro groups, and mesyl groups, arylsulfonyl groups substituted with aryls such as tosyl groups and mesityl groups, acyl groups having a carbon number of typically 1 to 12, preferably 6 or less, such as formyl groups, acetyl groups, and benzoyl groups, alkoxycarbonyl groups having a carbon number of typically 2 to 10, preferably 7 or less, such as methoxycarbonyl groups and ethoxycarbonyl groups, and phenoxycarbonyl groups and pyridyloxycarbonyl groups. Examples of such groups include an aryloxycarbonyl group having an aromatic hydrocarbon group or an aromatic heterocyclic group of typically 3 or more, preferably 4 or more and 25 or less, and preferably 15 or less; an acyloxy group having typically 2 to 20 carbon atoms such as acetoxy; a haloalkyl, haloalkenyl, haloalkynyl group having typically 1 to 10 carbon atoms, preferably 6 or less, linear, branched, or cyclic alkyl, alkenyl, or alkynyl group substituted with a halogen atom such as a fluorine atom or a chlorine atom; and a haloaryl group having typically 6 to 20 carbon atoms such as a pentafluorophenyl group.

The cation in the ionic compound is not particularly limited, but monovalent cations are preferred from the viewpoints of reactivity and ease of handling. More preferred cations in ionic compounds include iodonium, sulfonium, phosphonium, carbenium (trityl), anilinium, bismuthonium, ammonium, selenium, pyridinium, imidazolium, oxonium, quinolinium, pyrrolidinium, aminium, immonium, tropylium, morpholinium, piperidinium, quinolium, isoquinolium, thiazonium, and acridium.

The above cations may also be contained in the polymer.

From the viewpoint of improving charge transport properties, the ionic compound is preferably an onium salt, which refers to a compound comprising a cation such as a sulfonium ion, an iodonium ion, a selenium ion, an ammonium ion, a phosphonium ion, an oxonium ion, or a bismuthonium ion and a counter anion. Examples of anions include halogen ions such as F ⁻ , Cl ⁻ , Br ⁻ , and I ⁻ ; OH ⁻ ; ClO ₄ ⁻ ; sulfonate ions such as FSO ₃ ⁻ , ClSO ₃ ⁻ , CH ₃ SO ₃ ⁻ , C ₆ H ₅ SO ₃ ⁻ , and CF ₃ SO ₃ ⁻ ; sulfate ions such as HSO ₄ ⁻ and SO ₄ ²⁻ ; carbonate ions such as HCO ₃ ⁻ and CO ₃ ²⁻ ; phosphate ions such as H ₂ PO ₄ ⁻ , HPO ₄ ²⁻ , and PO ₄ ³⁻ ; fluorophosphate ions such as PF ₆ ⁻ and PF ₅ OH ⁻ ; BF ₄ ⁻ , B(C ₆ F ₅ ) ₄ ⁻ , and B(C ₆ H ₄ CF ₃ ) ₄ ^- ; fluoroantimonate ions such as AlCl ₄ ^- ; BiF ₆ ^- ; SbF ₆ ^- and SbF ₅ OH ^- ; and fluoroarsenate ions such as AsF ₆ ^- and AsF ₅ OH ^- .

Ionic compounds may be used alone or in combination of two or more.

(Polymerization initiator)
The ionic compound can be used as a polymerization initiator to promote the curing of the charge transport polymer. The trigger for initiating polymerization is not particularly limited as long as it exhibits the ability to polymerize a polymerizable substituent by application of heat, light, microwaves, radiation, electron beams, etc., but is preferably one that initiates polymerization by light irradiation and/or heating, and most preferably one that initiates polymerization by heating.

In this embodiment, the polymerization initiator is used in an amount of 0.1 to 50% by mass, more preferably 0.1 to 25% by mass, and even more preferably 0.1 to 20% by mass, relative to the charge transport material. If the polymerization initiator is mixed in at a ratio lower than this, polymerization will not proceed efficiently and the solubility will not be sufficiently changed. If the polymerization initiator is mixed in at a ratio higher than this, a large amount of polymerization initiator and/or decomposition products will remain, reducing the effectiveness of cleaning. The composition may also contain a sensitizer to improve photosensitivity and/or heat sensitivity.

<Ink composition>
The ink composition of this embodiment is characterized by containing the above-described charge transport material and a solvent, and may contain other additives such as a polymerization inhibitor, a stabilizer, a thickener, a gelling agent, a flame retardant, an antioxidant, a reduction inhibitor, an oxidizing agent, a reducing agent, a surface modifier, an emulsifier, an antifoaming agent, a dispersant, a surfactant, etc. Examples of the solvent include water and alcohols such as methanol, ethanol, and isopropyl alcohol; alkanes such as pentane, hexane, and octane; cyclic alkanes such as cyclohexane; aromatic solvents such as benzene, toluene, xylene, mesitylene, tetralin, and diphenylmethane; aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethoxytoluene, 2,3-dimethoxytoluene, 2,4-dimethylphenyl ether, 2,5-dimethylphenyl ether, 1,2-dimethylphenyl ether, 1,3-dimethoxybenzene, 2,5-dimethylphenyl ether ... Examples of the solvent include aromatic ethers such as methylanisole and 2,4-dimethylanisole; aliphatic esters such as ethyl acetate, n-butyl acetate, ethyl lactate and n-butyl lactate; aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate and n-butyl benzoate; amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide; and others such as dimethyl sulfoxide, tetrahydrofuran, acetone, chloroform and methylene chloride. However, aromatic solvents, aliphatic esters, aromatic esters, aliphatic ethers and aromatic ethers are preferably used.

In the ink composition of this embodiment, the content of the charge transport polymer relative to the solvent is preferably 0.1 to 50% by mass, from the viewpoint of applicability to various coating processes. From the viewpoint of reducing residual solvent during film formation, the content of the charge transport polymer is more preferably 0.5% by mass or more, and even more preferably 1% by mass or more. Furthermore, from the viewpoint of uniformly dissolving the charge transport material, the content is more preferably 40% by mass or less, and even more preferably 30% by mass or less.

<Organic layer>
The organic layer of this embodiment is a layer formed using the charge transport material or ink composition. By using a charge transport material or ink composition containing a solvent, an organic layer can be successfully formed by a coating method. Examples of the coating method include known methods such as spin coating; casting; immersion; plate-based printing methods such as relief printing, intaglio printing, offset printing, lithographic printing, relief reverse offset printing, screen printing, and gravure printing; and plateless printing methods such as inkjet printing. When the organic layer is formed by a coating method, the organic layer (coated layer) obtained after coating may be dried using a hot plate or oven to remove the solvent.

When a charge-transporting polymer contains a polymerizable substituent, the polymerization reaction can be accelerated by light irradiation, heat treatment, or other methods, changing the solubility of the organic layer. In the charge-transporting material, an ionic compound can function as a polymerization initiator. By stacking organic layers with varying solubilities, it becomes possible to easily create multilayered organic electronic devices. For information on methods for forming organic layers, see, for example, International Publication No. 2010/140553.

For example, an organic layer can be formed by forming a thin film from an ink composition containing the above-mentioned charge-transporting polymer, polymerization initiator, and solvent, and then heating it in a vacuum, in air, or in an inert gas atmosphere such as nitrogen or argon. The heating temperature and time are not particularly limited as long as they allow the polymerization reaction to proceed sufficiently. However, since the temperature can be applied to a variety of substrates, it is preferably 300°C or less, more preferably 200°C or less, and even more preferably 150°C or less. From the perspective of increasing productivity, the heating time is preferably 8 hours or less, more preferably 2 hours or less, and even more preferably 1 hour or less.

From the viewpoint of improving charge transport efficiency, the thickness of the organic layer after drying or curing is preferably 0.1 nm or more, more preferably 1 nm or more, and even more preferably 3 nm or more. Furthermore, from the viewpoint of reducing electrical resistance, the thickness of the organic layer is preferably 300 nm or less, more preferably 200 nm or less, and even more preferably 100 nm or less.

The organic layer of this embodiment can be used in organic electronic devices and organic EL devices described below, and can form organic electronic devices and organic EL devices that require a lower driving voltage and have a longer light emission lifetime than conventional devices.
<Organic electronics elements>
The organic electronics element of this embodiment includes at least one of the organic layers. Examples of the organic electronics element include organic EL elements such as organic light-emitting diodes (OLEDs), organic photoelectric conversion elements, and organic transistors. The organic electronics element preferably has a structure in which an organic layer is disposed between at least a pair of electrodes. The organic electronics element of this embodiment is not particularly limited as long as it includes a light-emitting layer, an organic layer, an anode, a cathode, and a substrate. The organic layer can be used as a hole injection layer, an electron injection layer, a hole transport layer, or an electron transport layer.

<Organic EL element>
The organic EL device of this embodiment includes at least one organic layer. The organic EL device of this embodiment is not particularly limited as long as it includes an emitting layer, an organic layer, an anode, a cathode, and a substrate. The organic layer can be used as a hole injection layer, an electron injection layer, a hole transport layer, or an electron transport layer. It is also preferable to use the organic layer of this embodiment as the hole injection layer or the hole transport layer.

Figure 1 is a cross-sectional schematic diagram showing one embodiment of an organic EL element. The organic EL element shown in Figure 1 has a multilayer structure in which a substrate 8, an anode 2, a hole injection layer 3, a hole transport layer 6, an emitting layer 1, an electron transport layer 7, an electron injection layer 5, and a cathode 4 are stacked in this order. Each layer will be described in detail below.

(Light-emitting layer)
The material used for the light-emitting layer may be a low-molecular-weight compound or a polymer, and dendrimers and the like can also be used. Examples of low-molecular-weight compounds that utilize fluorescence include perylene, coumarin, rubrene, quinacridone, dyes for dye lasers (e.g., rhodamine, DCM1, etc.), aluminum complexes (e.g., Tris(8-hydroxyquinolinato)aluminum(III) (Alq3)), stilbene, and derivatives thereof. Examples of polymers that utilize fluorescence include polyfluorene, polyphenylene, polyphenylene vinylene (PPV), polyvinylcarbazole (PVK), fluorene-benzothiadiazole copolymers, fluorene-triphenylamine copolymers, and derivatives and mixtures thereof.

Meanwhile, in recent years, the development of phosphorescent organic EL elements has been actively pursued in order to improve the efficiency of organic EL elements. Phosphorescent organic EL elements can utilize not only singlet state energy but also triplet state energy, making it possible, in principle, to increase the internal quantum yield to 100%. In phosphorescent organic EL elements, phosphorescent light is extracted by doping a host material with a metal complex phosphorescent material containing heavy metals such as platinum and iridium as a phosphorescent dopant (see M.A. Baldo et al., Nature, Vol. 395, p. 151 (1998); M.A. Baldo et al., Applied Physics Letters, Vol. 75, p. 4 (1999); M.A. Baldo et al., Nature, Vol. 403, p. 750 (2000)).

In the organic EL device of this embodiment, from the viewpoint of high efficiency, it is preferable to use a phosphorescent material in the light-emitting layer. As the phosphorescent material, a metal complex containing a central metal such as Ir or Pt can be suitably used. Specifically, examples of Ir complexes include FIr(pic) [iridium(III) bis[(4,6-difluorophenyl)-pyridinate-N,C ² ]picolinate] which emits blue light, Ir(ppy) ₃ [factory tris(2-phenylpyridine)iridium] which emits green light (see M.A. Baldo et al., Nature, Vol. 403, p. 750 (2000)), and (btp) ₂ Ir(acac) {bis[2-(2'-benzo[4,5-α]thienyl)pyridinate-N,C ³ ]iridium(acetylacetonate)}, Ir(piq) ₃ [tris(1-phenylisoquinoline)iridium] which emits red light. et al., Appl. Phys. Lett., 78 no. 11, 2001, 1622).

Examples of Pt complexes include 2,3,7,8,12,13,17,18-octaethyl-21H,23H-phorphine platinum (PtOEP), which emits red light.
The phosphorescent material may be a small molecule or dendritic species, such as an iridium-cored dendrimer, and derivatives thereof may also be suitably used.

Furthermore, when the light-emitting layer contains a phosphorescent material, it preferably contains a host material in addition to the phosphorescent material. The host material may be a low-molecular-weight compound or a high-molecular-weight compound, and dendrimers and the like can also be used.

Examples of low molecular weight compounds that can be used include CBP (4,4'-Bis(Carbazol-9-yl)-biphenyl), mCP (1,3-bis(9-carbazolyl)benzene), and CDBP (4,4'-Bis(Carbazol-9-yl)-2,2'-dimethylbiphenyl), while examples of high molecular weight compounds that can be used include polyvinylcarbazole, polyphenylene, and polyfluorene, as well as derivatives of these.

The light-emitting layer may be formed by a vapor deposition method or a coating method. Formation by a coating method is more preferable because it allows for inexpensive production of organic EL devices. To form the light-emitting layer by a coating method, a solution containing a phosphorescent material and, if necessary, a host material can be applied to the desired substrate by a known method, such as an inkjet method, a casting method, a dipping method, a printing method such as letterpress printing, intaglio printing, offset printing, lithographic printing, letterpress reverse offset printing, screen printing, or gravure printing, or a spin coating method.

(cathode)
The cathode material is preferably a metal or a metal alloy such as Li, Ca, Mg, Al, In, Cs, Ba, Mg—Ag, LiF, or CsF.

(anode)
The anode may be made of a metal (e.g., Au) or other material with metallic conductivity, such as an oxide (e.g., ITO) or a conductive polymer (e.g., a polythiophene-polystyrene sulfonic acid mixture (PEDOT:PSS)).

(Hole transport layer, hole injection layer)
It is preferable to use the organic layer described above as at least one of a hole transport layer and a hole injection layer. As described above, these layers can be easily formed by using an organic layer containing an organic electronic material. Furthermore, for example, when an organic EL element has the organic layer described above as a hole transport layer and further has a hole injection layer, a known material may be used for the hole injection layer. Furthermore, when an organic EL element has the organic layer described above as a hole injection layer and further has a hole transport layer, a known material may be used for the hole transport layer. Furthermore, an organic EL element may have the organic layer described above as a hole transport layer and a hole injection layer.

When a material containing a triphenylamine structure is used for the hole injection layer, it is preferable to use the organic layer described above for the hole transport layer from the perspective of the energy level for hole migration. In this case, the polymerization initiator may be contained in the organic layer that is the hole transport layer, or in an organic layer below the hole transport layer.

(electron transport layer, electron injection layer)
Examples of materials suitable for the electron transport layer and electron injection layer include phenanthroline derivatives (e.g., 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)), bipyridine derivatives, nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, heterocyclic tetracarboxylic acid anhydrides such as naphthalene perylene, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives (e.g., 2-(4-biphenylyl)-5-(4-tert-butylphenyl-1,3,4-oxadiazole) (PBD)), and aluminum complexes (e.g., Tris(8-hydroxyquinolinato)aluminum(III) (Alq3)). Thiadiazole derivatives, in which the oxygen atom of the oxadiazole ring is replaced with a sulfur atom, and quinoxaline derivatives having a quinoxaline ring, which is known as an electron-withdrawing group, can also be used.

(substrate)
The substrate usable for the organic EL element of this embodiment is not particularly limited to the type of glass, plastic, etc., and is not particularly limited as long as it is transparent, but glass, quartz, a light-transmitting resin film, etc. When a resin film is used, it is particularly preferable because it can impart flexibility to the organic EL element and function as a flexible substrate.

Examples of resin films include films made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC), cellulose acetate propionate (CAP), etc.

When using a resin film, the resin film may be coated with an inorganic material such as silicon oxide or silicon nitride to prevent the permeation of water vapor, oxygen, etc.

(Emitting color)
The color of light emitted from the organic EL element of this embodiment is not particularly limited, but a white light-emitting element is preferred because it can be used in various lighting fixtures such as home lighting, car lighting, clocks, and LCD backlights.

Currently, it is difficult to produce white light from a single material, so white light is obtained by using multiple light-emitting materials to simultaneously emit multiple light colors and mixing them. Combinations of multiple light colors are not particularly limited, but include those containing three maximum emission wavelengths (blue, green, and red), and those containing two maximum emission wavelengths that utilize complementary color relationships, such as blue and yellow, or yellow-green and orange. Furthermore, the emitted color can be controlled by adjusting the type and amount of phosphorescent material.

<Display element, lighting device, display device>
The display element of this embodiment is characterized by including the organic EL element. For example, by using organic EL elements as elements corresponding to red, green, and blue (RGB) pixels, a color display element can be obtained.
There are two image formation methods: the simple matrix type, in which individual organic EL elements arranged on a panel are directly driven by electrodes arranged in a matrix, and the active matrix type, in which each element is driven by a thin-film transistor. The former has a simple structure but is used to display characters and other images because it has a limited number of vertical pixels. The latter requires a low driving voltage and small current, producing bright, high-definition images, and is therefore used for high-quality displays.

The lighting device of this embodiment is characterized by including the organic EL element. Furthermore, the display device of this embodiment is characterized by including a lighting device and a liquid crystal element as display means. A display device using the lighting device described above as a backlight (white light source) and a liquid crystal element as display means, i.e., a liquid crystal display device, may be used. This configuration is a known liquid crystal display device in which only the backlight is replaced with the lighting device described above, and the liquid crystal element portion can be made using known technology.

The present embodiment will be explained in more detail below using examples, but the present embodiment is not limited to the following examples.

Below is a synthesis example of the charge transport material used in this example.

<Preparation of Pd catalyst>
In a glove box under a nitrogen atmosphere, at room temperature, a fluororesin-coated ceramic stir bar was placed in a glass sample vial, and 73.2 mg (80 μmol) of tris(dibenzylideneacetone)dipalladium was weighed out. 15 mL of toluene was added and the mixture was stirred for 30 minutes. Similarly, a fluororesin-coated ceramic stir bar was placed in a glass sample vial, and 129.6 mg (640 μmol) of tris(t-butyl)phosphine was weighed out. 5 mL of toluene was added and the mixture was stirred for 5 minutes. These solutions were mixed and stirred at 80°C for 2 hours. The resulting solution was filtered through a 0.2 μm pore membrane filter to remove insoluble matter, and the resulting solution was used as a catalyst. All solvents were degassed by bubbling nitrogen for at least 30 minutes before use.

<Synthesis of Charge Transporting Material>
(Synthesis of Charge-Transporting Polymer 1)
A 100 mL three-necked round-bottom glass flask was charged with 2.34 g (4.6 mmol) of Monomer 1 (see below), 0.87 g (1.8 mmol) of Monomer 2 (see below), 0.91 g (3.1 mmol) of Monomer 3 (see below), 0.15 g (0.6 mmol) of Monomer 4 (see below), and 17.7 mL of toluene. 3.9 mL of a 1% by mass trioctylmethylammonium chloride toluene solution and 7.2 mL of a 3 M aqueous potassium hydroxide solution were then added. All solvents were degassed by nitrogen bubbling for at least 30 minutes before use. A reflux condenser and a nitrogen gas flow tube were attached to the flask containing the reaction solution, and the flask was immersed in an oil bath heated to 60°C and stirred for 30 minutes to dissolve the monomer. Subsequently, 1.0 mL of the Pd catalyst solution prepared above was added, and the temperature of the oil bath was raised to 120°C to carry out the reaction. The reaction solution was heated to reflux for 2 hours. All reactions were carried out under a nitrogen stream.

After the reaction was complete, the organic layer was washed with water and poured into a methanol-water (9:1) mixed solution. The resulting precipitate was filtered off and washed with methanol. The resulting precipitate was washed with ethyl acetate, and the eluted solid was vacuum dried. The dried solid was dissolved in toluene, and a metal adsorbent (Strem Chemicals' "Triphenylphosphine, polymer-bound on styrene-divinylbenzene copolymer," 200 mg per 100 mg of precipitate) was added, followed by stirring at 40°C for 2 hours. After stirring was complete, the solution was filtered through a 0.2 μm pore membrane filter to remove the metal adsorbent and solid impurities, and then poured into methanol. The precipitate was suction filtered, washed with methanol, and then vacuum dried to obtain charge-transporting polymer 1.

(Synthesis of Charge-Transporting Polymer 2)
The synthesis was carried out in the same manner as in the synthesis of the above charge transporting polymer 1, except that the reaction was carried out using the following monomer 5 instead of monomer 4.

(Synthesis of Charge-Transporting Polymer 3)
The synthesis was carried out in the same manner as in the synthesis of the above charge transporting polymer 1, except that the reaction was carried out using the following monomer 6 instead of monomer 4.

(Synthesis of charge transporting polymer 4)
The synthesis was carried out in the same manner as in the synthesis of the above charge transporting polymer 1, except that the reaction was carried out using the following monomer 7 instead of monomer 4.

(Evaluation of Solvent Resistance)
An organic layer was formed using a charge transport polymer, and solvent resistance was evaluated by measuring the film remaining rate as follows. That is, an organic layer was formed using the steps shown below, and the quartz plate with the formed organic layer was immersed in 10 mL of toluene under atmospheric pressure and at room temperature and allowed to stand for 10 minutes. The film remaining rate (%) of the organic layer was calculated using the following formula from the ratio of the absorbance (Abs) at the absorption maximum (λmax) in the visible ultraviolet spectroscopy (UV-vis) spectrum before and after immersion of the organic layer in toluene. The higher the film remaining rate, the better the solvent resistance.

Remaining film rate (%) = (absorbance of organic layer after toluene immersion / absorbance of organic layer before toluene immersion) x 100

Example 1
The charge-transporting polymer 1 (5.0 mg) and the charge-transporting polymer 3 (5.0 mg) were weighed into a glass sample tube and dissolved in 0.9 mL of toluene to prepare a charge-transporting polymer solution. The charge-transporting polymer solution was spin-coated onto a quartz plate at 3,000 rpm in air. The spin-coated quartz plate was then placed in a nitrogen-atmosphere glove box and heated on a nitrogen-atmosphere hot plate at 230°C for 30 minutes to undergo a curing reaction, forming an organic layer. The remaining film ratio (%) of the organic layer was then calculated.

Example 2
The same procedure as in Example 1 was carried out except that Charge Transporting Polymer 4 was used instead of Charge Transporting Polymer 3, and the remaining film ratio was measured.

Example 3
The same procedure as in Example 1 was carried out except that Charge Transporting Polymer 2 was used instead of Charge Transporting Polymer 1, and the remaining film ratio was measured.

Example 4
The same procedure as in Example 3 was carried out except that Charge Transporting Polymer 4 was used instead of Charge Transporting Polymer 3, and the remaining film ratio was measured.

(Comparative Example 1)
The same procedure as in Example 1 was carried out except that Charge Transporting Polymer 1 was used instead of Charge Transporting Polymer 3, and the remaining film ratio was measured (total amount of Charge Transporting Polymer 1: 10.0 mg).

(Comparative Example 2)
The same procedure as in Example 3 was carried out except that Charge Transporting Polymer 2 was used instead of Charge Transporting Polymer 3, and the remaining film rate was measured (total amount of Charge Transporting Polymer 2: 10.0 mg).

The results for Examples 1 to 4 and Comparative Examples 1 and 2 are shown in Table 1 below.

Examples 1 to 4 show that by using two types of charge-transporting polymers, the residual film rate is improved compared to Comparative Examples 1 and 2, which use only one type of charge-transporting polymer.

As a result, by containing two types of charge-transporting polymers in the charge-transporting material, it is possible to achieve good layering of organic layers.

REFERENCE SIGNS LIST 1 Light-emitting layer 2 Anode 3 Hole injection layer 4 Cathode 5 Electron injection layer 6 Hole transport layer 7 Electron transport layer 8 Substrate

Claims (11)

a first polymer having a first polymerizable substituent;
a second polymer having a second polymerizable substituent different from the first polymerizable substituent;
the first polymerizable substituent comprises a group having a polymerizable carbon-carbon unsaturated bond,
In the first polymer, a structural unit (4) having a first polymerizable substituent is introduced into a terminal portion of the polymer, and the content of the structural unit (4) based on the structural unit constituting the terminal portion of the polymer is 10 to 50 mol %,
The structural unit (4) is represented by the following structural formula:
(* indicates the binding site with other structures.)
the second polymerizable substituent comprises a benzocyclobutenyl group ;
In the second polymer, a structural unit (5) having a second polymerizable substituent is introduced into a terminal portion of the polymer, and the content of the structural unit (5) based on the structural unit constituting the terminal portion of the polymer is 10 to 50 mol %,
The structural unit (5) is represented by the following structural formula:
(* indicates the binding site with other structures.)
The charge transporting material, wherein the first polymer and the second polymer have the following structural unit (2-1):
In the structural unit (2-1), * represents a bonding site to other structures, and each R independently represents a halogen atom or a halogenated alkyl group having 1 to 4 carbon atoms. An ink composition comprising the charge transport material of claim 1 and a solvent. An organic layer formed using the charge transporting material according to claim 1 or the ink composition according to claim 2 . An organic electronic device comprising at least one organic layer according to claim 3 . An organic electroluminescence device comprising at least one organic layer according to claim 3 . The organic electroluminescent device according to claim 5 , further comprising a flexible substrate. The organic electroluminescence device according to claim 5 , further comprising a resin film substrate. A display device comprising the organic electroluminescence device according to any one of claims 5 to 7 . A lighting device comprising the organic electroluminescence element according to any one of claims 5 to 7 . A display device comprising the organic electroluminescence element according to any one of claims 5 to 7 . A display device comprising the lighting device according to claim 9 and a liquid crystal element as a display means.