JP2023012818A - Composition for forming light emitting layer of quantum dot light emitting element, quantum dot light emitting element, quantum dot display device, and quantum dot lighting - Google Patents

Abstract

To provide a quantum dot light emitting element having a light emitting layer containing quantum dots, exhibiting excellent element characteristics, low voltage drive, high luminous efficiency, and long drive life.SOLUTION: A composition for forming the light-emitting layer of a quantum dot light-emitting element, comprising quantum dots, a compound represented by the following formula (1), and an organic solvent. (Ar21 and Ar22 are aromatic hydrocarbon groups having 6 to 30 carbons which may have substituents, aromatic heterocyclic groups having 3 to 30 carbons which may have substituents, or monovalent groups having 2 to 7 of these linked together.)SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a composition for forming a light emitting layer of a quantum dot light emitting device, and a quantum dot light emitting device, a quantum dot display device and a quantum dot illumination using the same.

As a thin-film type electroluminescence element, an organic electroluminescence element using an organic thin film has been developed. An organic electroluminescent device (OLED) usually has a hole-injection layer, a hole-transport layer, an organic light-emitting layer, an electron-transport layer, etc. between an anode and a cathode, and materials suitable for these layers are being developed. There are red, green, and blue luminescent colors, and development is progressing accordingly.

In recent years, attempts have been made to cover a wider color gamut by using "quantum dots", which are inorganic light-emitting substances, in the light-emitting layer to make the red, green, and blue light sources sharp emission spectra. . An electroluminescent device using quantum dots is also called a quantum dot light emitting device (QD-LED, QLED).

A quantum dot light-emitting device is usually formed by a wet film-forming method (coating method). The wet film-forming method has advantages such as easiness in increasing the area, and research and development of quantum dot light-emitting devices by film-forming by a coating method have been advanced. For example, Patent Literatures 1 to 3 and Non-Patent Literature 1 discuss quantum dot light-emitting devices, but it has been desired to reduce the voltage of the device, improve the luminous efficiency, and improve the driving life.

JP 2020-107867 A JP 2020-161476 A JP 2020-173937 A

Nature, 2014, vol.515, pp.96-99

An object of the present invention is to provide a quantum dot light-emitting device that has a light-emitting layer containing quantum dots, exhibits excellent device characteristics, can be driven at a low voltage, has high luminous efficiency, and has a long drive life.

The gist of the present invention is as follows [1] to [9].

[1] A composition for forming a light emitting layer of a quantum dot light emitting device, comprising quantum dots, a compound represented by the following formula (1), and an organic solvent.

(In formula (1),
Ar ²¹ and Ar ²² are each independently an optionally substituted C 6-30 aromatic hydrocarbon group, an optionally substituted C 3-30 aromatic heterocyclic ring or a structure selected from an optionally substituted C 6-30 aromatic hydrocarbon group and an optionally substituted C 3-30 aromatic heterocyclic group represents a monovalent group in which 2 to 7 are linked,
Each of R ²¹ to R ²⁴ is independently an optionally substituted alkyl group, an optionally substituted C 6 to 30 aromatic hydrocarbon group, and a substituted group. an aromatic heterocyclic group having 3 to 30 carbon atoms which may be substituted, or an aromatic hydrocarbon group having 6 to 30 carbon atoms which may have substituents and 3 to 3 carbon atoms which may have substituents represents a monovalent group in which 2 to 7 structures selected from 30 aromatic heterocyclic groups are linked,
e and g are each independently an integer of 0 to 4,
f and h are each independently an integer of 0 to 3; )

[2] A composition for forming a light emitting layer of a quantum dot light emitting device, comprising quantum dots, a compound represented by the following formula (1A), and an organic solvent.

(In formula (1A), Ar ²¹ , Ar ²² , R ²¹ to R ²⁴ , e, f, g, and h are Ar ²¹ , Ar ²² , R ²¹ to R ²⁴ , e, f, Synonymous with g and h.)

[3] A method for producing a quantum dot light-emitting device, comprising applying the composition for forming a light-emitting layer of the quantum dot light-emitting device according to [1] or [2] and drying it to form a light-emitting layer.

[4] A method for manufacturing a quantum dot display device, including the method for manufacturing the quantum dot light-emitting element of [3].

[5] A method for manufacturing quantum dot lighting, including the method for manufacturing the quantum dot light-emitting device of [3].

[6] having an anode, a cathode, and a light-emitting layer provided between the anode and the cathode;
A quantum dot light-emitting device, wherein the light-emitting layer contains quantum dots and a compound represented by the following formula (1).

(In formula (1),
Ar ²¹ and Ar ²² are each independently an optionally substituted C 6-30 aromatic hydrocarbon group, an optionally substituted C 3-30 aromatic heterocyclic ring or a structure selected from an optionally substituted C 6-30 aromatic hydrocarbon group and an optionally substituted C 3-30 aromatic heterocyclic group represents a monovalent group in which 2 to 7 are linked,
Each of R ²¹ to R ²⁴ is independently an optionally substituted alkyl group, an optionally substituted C 6 to 30 aromatic hydrocarbon group, and a substituted group. an aromatic heterocyclic group having 3 to 30 carbon atoms which may be substituted, or an aromatic hydrocarbon group having 6 to 30 carbon atoms which may have substituents and 3 to 3 carbon atoms which may have substituents represents a monovalent group in which 2 to 7 structures selected from 30 aromatic heterocyclic groups are linked,
e and g are each independently an integer of 0 to 4,
f and h are each independently an integer of 0 to 3; )

[7] having an anode, a cathode, and a light-emitting layer provided between the anode and the cathode;
A quantum dot light-emitting device, wherein the light-emitting layer contains a quantum dot and a compound represented by the following formula (1A).

(In formula (1A), Ar ²¹ , Ar ²² , R ²¹ to R ²⁴ , e, f, g, and h are Ar ²¹ , Ar ²² , R ²¹ to R ²⁴ , e, f, Synonymous with g and h.)

[8] A quantum dot display device comprising the quantum dot light emitting device according to [6] or [7].

[9] A quantum dot illumination comprising the quantum dot light-emitting device according to [6] or [7].

The composition for forming a light-emitting layer and the quantum dot light-emitting device of the present invention can provide a quantum dot light-emitting device that exhibits excellent device characteristics, can be driven at a low voltage, has high luminous efficiency, and has a long drive life.

FIG. 1 is a schematic cross-sectional view showing a structural example of the quantum dot light-emitting device of the present invention.

In the following, embodiments of the composition for forming the light-emitting layer of the quantum dot light-emitting device of the present invention, the quantum dot light-emitting device, the quantum dot display device comprising the quantum dot light-emitting device, and the quantum dot illumination comprising the quantum dot light-emitting device are described in detail. to explain. The following description is an example (representative example) of embodiments of the present invention, and the present invention is not limited to these contents unless it exceeds the gist thereof.

[Composition for forming light-emitting layer of quantum dot light-emitting device]
The composition for forming a light-emitting layer of the quantum dot light-emitting device of the present invention (hereinafter referred to as the "composition for forming a light-emitting layer of the present invention") comprises quantum dots, a compound represented by the following formula (1), and an organic solvent.

(In formula (1),
Ar ²¹ and Ar ²² are each independently an optionally substituted C 6-30 aromatic hydrocarbon group, an optionally substituted C 3-30 aromatic heterocyclic ring or a structure selected from an optionally substituted C 6-30 aromatic hydrocarbon group and an optionally substituted C 3-30 aromatic heterocyclic group represents a monovalent group in which 2 to 7 are linked,
Each of R ²¹ to R ²⁴ is independently an optionally substituted alkyl group, an optionally substituted C 6 to 30 aromatic hydrocarbon group, and a substituted group. an aromatic heterocyclic group having 3 to 30 carbon atoms which may be substituted, or an aromatic hydrocarbon group having 6 to 30 carbon atoms which may have substituents and 3 to 3 carbon atoms which may have substituents represents a monovalent group in which 2 to 7 structures selected from 30 aromatic heterocyclic groups are linked,
e and g are each independently an integer of 0 to 4,
f and h are each independently an integer of 0 to 3; )

The compound represented by formula (1) contained in the light-emitting layer-forming composition of the present invention may be one kind or two or more kinds.

In the light-emitting layer formed using the light-emitting layer-forming composition of the present invention, the quantum dots function as a light-emitting material, and the compound represented by Formula (1) functions as a charge-transporting material.

[Reasons why the present invention is effective]
The compound represented by the formula (1) contained in the light-emitting layer of the light-emitting layer-forming composition of the present invention and the quantum dot light-emitting device formed from this light-emitting layer-forming composition has appropriate charge transport properties and HOMO Since it has a level, it becomes possible to effectively generate an excited state of the quantum dot.
The compound represented by the formula (1) has a wide HOMO by connecting two carbazolyl groups at the benzene ring portion, and has an appropriate charge transport property and HOMO level. Since an aromatic hydrocarbon group or an aromatic heterocyclic group is bonded to the 9-positions of the two carbazolyl groups, the durability is excellent.

[Quantum dots]
The composition for forming a light-emitting layer of the present invention contains quantum dots. Quantum dots are luminescent semiconductor nanoparticles that typically range in diameter from 1 to 20 nm.

Preferably, the quantum dots comprise Group II-VI compounds, Group III-V compounds, Group IV-VI compounds, Group IV elements, Group IV compounds, and combinations thereof.

II-VI group compounds include CdSe, CdTe, CdS, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, AgInS, CuInS, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, ＨｇＳｅＴｅ、ＨｅＳＴｅ、ＣｄＺｎＳ、ＣｄＺｎＳｅ、ＣｄＺｎＴｅ、ＣｄＨｇＳ、ＣｄＨｇＳｅ、ＣｄＨｇＴｅ、ＨｇＺｎＳ、ＨｅＺｎＳｅ、ＨｅＺｎＴｅ、ＭｇＺｎＳｅ、ＭｇＺｎＳ、ＨｇＺｎＴｅＳ、ＣｄＺｎＳｅＳ、ＣｄＺｎＳｅＴｅ、ＣｄＺｎＳＴｅ、ＣｄＨｇＳｅＳ、ＣｄＨｇＳｅＴｅ、ＣｄＨｇＳＴｅ、ＨｇＺｎＳｅＳ、ＨｇＺｎＳｅＴｅ、ＨｇＺｎＳＴｅが挙げられる。

III-V compounds include GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InGaP, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb.

Group IV-VI compounds include SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe.

Examples of Group IV elements and Group IV compounds include Si, Ge, SiC, and SiGe.
be.

Quantum dots may be homogenous single structures or core/shell dual structures. It may also have a triple or quadruple or more structure such as core/shell/shell. The materials that make up the core and shell consist of different compounds. In this case, the energy bandgap of the shell compound is preferably larger than the energy bandgap of the core compound. Specifically, structures such as ZnTeSe/ZnSe/ZnS, CdSe/ZnS, and InP/ZnS are preferred.
Also, the number of quantum dots may be one or two or more.

[Compound represented by formula (1)]
A composition for forming a light-emitting layer of a quantum dot light-emitting device of the present invention contains a compound represented by the following formula (1).

(In formula (1),
Ar ²¹ and Ar ²² are each independently an optionally substituted C 6-30 aromatic hydrocarbon group, an optionally substituted C 3-30 aromatic heterocyclic ring or a structure selected from an optionally substituted C 6-30 aromatic hydrocarbon group and an optionally substituted C 3-30 aromatic heterocyclic group represents a monovalent group in which 2 to 7 are linked,
Each of R ²¹ to R ²⁴ is independently an optionally substituted alkyl group, an optionally substituted C 6 to 30 aromatic hydrocarbon group, and a substituted group. an aromatic heterocyclic group having 3 to 30 carbon atoms which may be substituted, or an aromatic hydrocarbon group having 6 to 30 carbon atoms which may have substituents and 3 to 3 carbon atoms which may have substituents represents a monovalent group in which 2 to 7 structures selected from 30 aromatic heterocyclic groups are linked,
e and g are each independently an integer of 0 to 4,
f and h are each independently an integer of 0 to 3; )

< ^Ar21 , ^Ar22 >
The aromatic hydrocarbon group having 6 to 30 carbon atoms that can be applied to Ar ²¹ and Ar ²² in the formula (1) is preferably a 6-membered monocyclic group or a monovalent group having 2 to 5 condensed rings. Specifically, monovalent ring such as benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, fluorene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, fluoranthene ring, and indenofluorene ring. groups. More preferably, a monovalent group of a benzene ring, a naphthalene ring, a phenanthrene ring, a fluorene ring, or an indenofluorene ring, more preferably a monovalent group of a benzene ring, a naphthalene ring, or a fluorene ring, and most A monovalent group of a benzene ring or a naphthalene ring is preferred.

The aromatic heterocyclic group having 3 to 30 carbon atoms applicable to Ar ²¹ and Ar ²² in the formula (1) includes a 5- or 6-membered monocyclic ring or a 2- to 5-condensed monovalent group. preferable. Specifically, furan ring, benzofuran ring, dibenzofuran ring, thiophene ring, benzothiophene ring, dibenzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, indolocarbazole ring, indenocarbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, Examples include monovalent groups such as pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, shinoline ring, quinoxaline ring, perimidine ring, quinazoline ring, and quinazolinone ring. Among these, thiophene ring, pyrrole ring, imidazole ring, pyridine ring, pyrimidine ring, triazine ring, quinoline ring, quinazoline ring, carbazole ring, dibenzofuran ring, dibenzothiophene ring, indolocarbazole ring, phenanthroline ring, or indo locarbazole ring, more preferably a monovalent group of pyridine ring, pyrimidine ring, triazine ring, quinoline ring, quinazoline ring, carbazole ring, dibenzofuran ring, dibenzothiophene ring, indolocarbazole ring, or indenocarbazole ring; and more preferably a monovalent group of a carbazole ring, dibenzofuran ring, dibenzothiophene ring, indolocarbazole ring, or indenocarbazole ring.

Ar ²¹ and Ar ²² are selected from an optionally substituted C 6-30 aromatic hydrocarbon group and an optionally substituted C 3-30 aromatic heterocyclic group When the structure to be formed is a monovalent group in which 2 to 7 units are linked, the aromatic hydrocarbon group and the aromatic heterocyclic group can be selected from these monovalent groups and combined. The number of linkages is preferably 2-5, more preferably 3.

Examples of the substituent which the aromatic hydrocarbon group and the aromatic heterocyclic group of Ar ²¹ and Ar ²² may have include those listed in the substituent group Z described below.

< ^R21 to ^R24 >
In formula (1), the alkyl group applicable to R ²¹ to R ²⁴ has usually 1 or more carbon atoms, preferably 4 or more carbon atoms, usually 24 or less carbon atoms, preferably 12 or less carbon atoms, and more preferably 12 or less carbon atoms. is 8 or less, more preferably 6 or less, and is a linear, branched or cyclic alkyl group. Specifically, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, n-hexyl group, cyclohexyl group, dodecyl groups.
An aromatic hydrocarbon group having a prime number of 6 to 30, an aromatic heterocyclic group having a carbon number of 3 to 30 which may have a substituent, or, applicable to R ²¹ to R ²⁴ in the formula (1) 2 to 7 structures selected from optionally substituted aromatic hydrocarbon groups having 6 to 30 carbon atoms and aromatic heterocyclic groups having 3 to 30 carbon atoms and optionally having substituents Specific examples of the monovalent groups linked together are the same as the specific examples described as application to Ar ²¹ and Ar ²² .

Examples of the substituent which the alkyl group, aromatic hydrocarbon group, and aromatic heterocyclic group of R ²¹ to R ²⁴ may have include those listed in the group of substituents Z described below.

<e, f, g, h>
In formula (1), e and g are each independently integers of 0 to 4, and f and h are each independently integers of 0 to 3. e, f, g, and h are preferably 0 or 1 from the viewpoint of proper charge transportability and HOMO level. 0 is more preferable in terms of ease of manufacture. 1 is more preferable from the viewpoint of high heat resistance.
When e, f, g and h are 2 or more and there are a plurality of R ²¹ to R ²⁴ , the plurality of R ²¹ to R ²⁴ may be the same or different groups.

<Substituent Group Z>
Substituent group Z includes an alkyl group, an alkoxy group, an aryloxy group, a heteroaryloxy group, an alkoxycarbonyl group, a dialkylamino group, a diarylamino group, an arylalkylamino group, an acyl group, a halogen atom, a haloalkyl group, an alkylthio group, A group consisting of an arylthio group, a silyl group, a siloxy group, a cyano group, an aromatic hydrocarbon group, and an aromatic heterocyclic group. These substituents may contain any structure of linear, branched and cyclic.

More specific examples of the substituent group Z include the following structures.
For example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, n-hexyl group, cyclohexyl group, dodecyl group, etc. , the number of carbon atoms is usually 1 or more, preferably 4 or more, usually 24 or less, preferably 12 or less, more preferably 8 or less, and still more preferably 6 or less, linear, branched , or a cyclic alkyl group;
An alkoxy group having usually 1 or more carbon atoms, 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 carbon atoms, preferably 5 or more carbon atoms, usually 36 or less, preferably 24 or less carbon atoms such as phenoxy group, naphthoxy group, pyridyloxy group, etc. group;
For example, an alkoxycarbonyl group having usually 2 or more carbon atoms, usually 24 or less, preferably 12 or less, such as a methoxycarbonyl group or an ethoxycarbonyl group;
For example, a dialkylamino group having usually 2 or more carbon atoms, usually 24 or less, preferably 12 or less, such as a dimethylamino group or a diethylamino group;
For example, a diarylamino group having usually 10 or more carbon atoms, preferably 12 or more carbon atoms, usually 36 or less, preferably 24 or less carbon atoms, such as a diphenylamino group or a ditolylamino group;
For example, an arylalkylamino group having usually 7 carbon atoms, usually 36 or less, preferably 24 or less, such as a phenylmethylamino group;
For example, an acyl group having usually 2 carbon atoms, usually 24 or less, preferably 12 carbon atoms, such as an acetyl group or a benzoyl group;
Halogen atoms such as, for example, fluorine atoms and chlorine atoms;
For example, a haloalkyl group having usually 1 or more carbon atoms, usually 12 or less, preferably 6 or less, such as a trifluoromethyl group;
For example, an alkylthio group having usually 1 or more carbon atoms, usually 24 or less, preferably 12 or less, such as a methylthio group or an ethylthio group;
arylthio groups having usually 4 or more, preferably 5 or more, usually 36 or less, preferably 24 or less carbon atoms, such as phenylthio, naphthylthio, and pyridylthio groups;
For example, a silyl group having usually 2 or more carbon atoms, preferably 3 or more carbon atoms, usually 36 or less, preferably 24 or less carbon atoms, such as a trimethylsilyl group or a triphenylsilyl group;
a siloxy group having usually 2 or more carbon atoms, preferably 3 or more carbon atoms, usually 36 or less, preferably 24 or less carbon atoms, such as a trimethylsiloxy group or a triphenylsiloxy group;
cyano group;
aromatic hydrocarbon groups having usually 6 or more carbon atoms, usually 36 or less, preferably 24 or less, such as phenyl group and naphthyl group;
For example, an aromatic heterocyclic group having usually 3 or more, preferably 4 or more, and usually 36 or less, preferably 24 or less carbon atoms such as thienyl group or pyridyl group.

Among the substituent group Z described above, an alkyl group, an alkoxy group, a diarylamino group, an aromatic hydrocarbon group, or an aromatic heterocyclic group is preferred. From the viewpoint of charge transport properties, the substituent is preferably an aromatic hydrocarbon group or an aromatic heterocyclic group, more preferably an aromatic hydrocarbon group, and further preferably has no substituent. From the viewpoint of improving solubility, the substituent is preferably an alkyl group or an alkoxy group.

Further, each substituent in the substituent group Z may further have a substituent. Examples of these substituents include the same substituents as those described above (substituent group Z). Each substituent that the substituent group Z may have is preferably an alkyl group having 8 or less carbon atoms, an alkoxy group having 8 or less carbon atoms, or a phenyl group, more preferably an alkyl group having 6 or less carbon atoms, It is an alkoxy group having 6 or less carbon atoms or a phenyl group, and each substituent in the substituent group Z more preferably does not have a further substituent from the viewpoint of charge transport properties.

<Molecular weight>
The compound represented by the formula (1) is a low-molecular-weight material, and has a molecular weight of preferably 5,000 or less, more preferably 3,000 or less, particularly preferably 2,000 or less, and most preferably 1 , 500 or less, and the lower limit of the molecular weight is usually 300 or more, preferably 350 or more, more preferably 400 or more.

<Compound Represented by Formula (1A)>
The compound represented by the formula (1) has hole-transporting property and A compound represented by the following formula (1A) is preferable because the electron-transporting property is enhanced and the excited state of the quantum dot can be effectively generated.

(In formula (1A), Ar ²¹ , Ar ²² , R ²¹ to R ²⁴ , e, f, g, and h are Ar ²¹ , Ar ²² , R ²¹ to R ²⁴ , e, f, Synonymous with g and h.)

<Specific examples of compounds represented by formula (1)>
Although the compound represented by Formula (1) is not particularly limited, the following compounds may, for example, be mentioned.

The composition for forming a light-emitting layer of the present invention may contain only one compound represented by the formula (1), or may contain two or more compounds.

[Organic solvent]
The organic solvent contained in the composition for forming a light-emitting layer of the present invention is a compound represented by the above formula (1), preferably the compound represented by the above formula (1A), by wet film formation. It is a volatile liquid component used to form the containing layer.

The organic solvent is the compound represented by the formula (1), which is a solute, preferably the compound represented by the formula (1A), and when other charge-transporting materials described later are used, the other charge-transporting There is no particular limitation as long as it is an organic solvent in which the organic material can be dissolved satisfactorily.

Preferred organic solvents include, for example, alkanes such as n-decane, cyclohexane, ethylcyclohexane, decalin and bicyclohexane; aromatic hydrocarbons such as toluene, xylene, mesitylene, phenylcyclohexane, tetralin and methylnaphthalene; Halogenated aromatic hydrocarbons such as chlorobenzene and trichlorobenzene; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3 - aromatic ethers such as dimethylanisole, 2,4-dimethylanisole and diphenyl ether; aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate and n-butyl benzoate; Alicyclic ketones such as cyclohexanone, cyclooctanone and fenchone; Alicyclic alcohols such as cyclohexanol and cyclooctanol; Aliphatic ketones such as methyl ethyl ketone and dibutyl ketone; Aliphatic alcohols such as butanol and hexanol; aliphatic ethers such as glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA);

Among these, alkanes, aromatic hydrocarbons, and aromatic esters are preferred, and aromatic hydrocarbons and aromatic esters are particularly preferred, from the viewpoint of viscosity and boiling point.

One type of these organic solvents may be used alone, or two or more types may be used in any combination and ratio.

The boiling point of the organic solvent used is usually 80° C. or higher, preferably 100° C. or higher, more preferably 120° C. or higher, and usually 350° C. or lower, preferably 330° C. or lower, more preferably 300° C. or lower. If the boiling point of the organic solvent is below this range, the film formation stability may decrease due to evaporation of the solvent from the composition for forming the light-emitting layer during wet film formation. If the boiling point of the organic solvent exceeds this range, there is a possibility that the film formation stability will decrease due to the residual solvent after wet film formation.

In particular, among the above organic solvents, a combination of two or more organic solvents having a boiling point of 150° C. or higher is considered to facilitate the formation of a more uniform coating film, and thus is preferable.

[Other charge transport materials]
The composition for forming a light-emitting layer of the present invention may further contain a charge-transporting material other than the compound represented by the formula (1).

As other charge-transporting materials, those used as charge-transporting materials for organic electroluminescence devices can be used. For example, pyridine, carbazole, naphthalene, perylene, pyrene, anthracene, chrysene, naphthacene, phenanthrene, coronene, fluoranthene, benzophenanthrene, fluorene, acetonaphthofluoranthene, coumarin, p-bis(2-phenylethenyl)benzene and these derivatives, quinacridone derivatives, DCM (4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran) compounds, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, azabenzothioxanthenes, aryl Examples include condensed aromatic ring compounds with substituted amino groups, styryl derivatives with substituted arylamino groups, and the like.

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

Among these, naphthalene, perylene, pyrene, anthracene, chrysene, naphthacene, phenanthrene, coronene, fluoranthene, benzophenanthrene, fluorene, acetonaphthofluoranthene and derivatives thereof are preferred, and anthracene derivatives are more preferred. .

[Content]
The content of quantum dots contained in the light-emitting layer-forming composition of the present invention is usually 0.001% by mass or more, preferably 0.01% by mass or more, and is usually 30.0% by mass or less, preferably 20.0% by mass. % by mass or less.
The content of the compound represented by the formula (1), preferably the compound represented by the formula (1A), contained in the composition for forming a light-emitting layer of the present invention is usually 0.01% by mass or more, preferably is 0.1% by mass or more, usually 30.0% by mass or less, preferably 20.0% by mass or less.
By setting the content of the quantum dots and the compound represented by the formula (1), preferably the compound represented by the formula (1A), in this range, adjacent layers (for example, a hole transport layer and a hole Injection of holes and electrons from the blocking layer) into the light-emitting layer is performed efficiently, and the driving voltage can be reduced.
In addition, the quantum dot, the compound represented by the formula (1), preferably the compound represented by the formula (1A) may be contained in the composition for forming the light-emitting layer only one kind. More than one species may be included in combination.

When the light-emitting layer-forming composition of the present invention contains other charge-transporting materials, the content thereof is usually 0.01% by mass or more, preferably 0.1% by mass or more, and usually 30.0% by mass or less. Preferably, it is 20.0% by mass or less. By setting the content of the other charge-transporting material in the composition for forming the light-emitting layer within the above range, the transportability of electrons in the light-emitting layer is improved, the voltage is lowered, and electrons in the light-emitting layer It is considered that the luminous efficiency is improved because the hole balance is improved.

Further, from the viewpoint of improving luminous efficiency, the compound represented by the formula (1), preferably the compound represented by the formula (1A), contained in the composition for forming a light-emitting layer of the present invention, and other charge-transporting compounds The total content of the materials is usually 10 parts by mass or less, preferably 1 part by mass or less, more preferably 0.5 parts by mass or less, usually 0.001 parts by mass or more, with respect to 1 part by mass of the quantum dots, It is preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more.

The content of the organic solvent contained in the light-emitting layer-forming composition of the present invention is usually 10% by mass or more, preferably 50% by mass or more, particularly preferably 80% by mass or more, and usually 99.95% by mass or less, preferably is 99.9% by mass or less, particularly preferably 99.8% by mass or less. If the content of the organic solvent is at least the above lower limit, the composition will have an appropriate viscosity and the coatability will be improved.

[Other ingredients]
The composition for forming a light-emitting layer of the present invention may contain other compounds in addition to the quantum dots and the above compounds, if necessary. Other compounds preferably include dibutylhydroxytoluene, which is known as an antioxidant, and phenols such as dibutylphenol.

[Deposition method]
A method for forming a light-emitting layer using the composition for forming a light-emitting layer of the present invention is a wet film-forming method. The wet film-forming method is a method of applying a composition to form a liquid film, drying it to remove the organic solvent, and forming a light-emitting layer film. Examples of coating methods include spin coating, dip coating, die coating, bar coating, blade coating, roll coating, spray coating, capillary coating, inkjet, nozzle printing, screen printing, and gravure. It refers to a method of forming a film by employing a wet film-forming method such as a printing method or a flexographic printing method, and drying the coating film. Among these film forming methods, the spin coating method, the spray coating method, the inkjet method, the nozzle printing method, and the like are preferable. When manufacturing a quantum dot display device having a quantum dot light-emitting element using the composition for forming a light-emitting layer of the present invention, an inkjet method or a nozzle printing method is preferable, and an inkjet method is particularly preferable.

Although the drying method is not particularly limited, natural drying, drying under reduced pressure, drying by heating, or drying under reduced pressure while heating can be used as appropriate. Heat drying may be carried out in order to further remove residual organic solvent after natural drying or vacuum drying.
Drying under reduced pressure is preferably carried out at a pressure equal to or lower than the vapor pressure of the organic solvent contained in the composition for forming a light-emitting layer.
When heating, the heating method is not particularly limited, but heating with a hot plate, heating in an oven, infrared heating, or the like can be used. The heating time is usually 80° C. or higher, preferably 100° C. or higher, more preferably 110° C. or higher, and preferably 200° C. or lower, more preferably 150° C. or lower.
The heating time is generally 1 minute or longer, preferably 2 minutes or longer, generally 60 minutes or shorter, preferably 30 minutes or shorter, and more preferably 20 minutes or shorter.

[Quantum dot light emitting device]
A quantum dot light-emitting device according to one aspect of the present invention includes an anode, a cathode, and a light-emitting layer formed between the anode and the cathode using the composition for forming a light-emitting layer of the present invention ( light-emitting layer).
Further, a quantum dot light-emitting device according to another aspect of the present invention has an anode, a cathode, and a light-emitting layer provided between the anode and the cathode, and the light-emitting layer includes quantum dots and the above formula (1) Including the compound represented by.

The quantum dot light-emitting device of the present invention preferably further includes an organic layer other than the light-emitting layer as a second organic layer between the anode and the light-emitting layer. The second organic layer is more preferably a hole injection layer or a hole transport layer, and even more preferably a hole transport layer. In addition, as described later, the second organic layer is a polymer having a triarylamine structure as a repeating unit (hereinafter, when the polymer contained in the second organic layer is referred to as the "second polymer" ), more preferably the polymer does not contain a cross-linking group. As the second polymer, a polymer containing a repeating unit represented by formula (5) is preferable as follows, more preferably a repeating unit represented by formula (2) described later, or formula (3) or a polymer containing a repeating unit represented by formula (4).

The second organic layer is preferably formed by a wet film-forming method using the second composition described below. The second composition is insolubilized by heating after application. Therefore, the second organic layer can be suitably used for lamination of quantum dot light-emitting devices.

The second organic layer included in the quantum dot light-emitting device of the present invention is described below.
The structure of the quantum dot light emitting device of the present invention will be described later.

[Second organic layer]
The second organic layer preferably contains, as a hole-transporting material, a second polymer having a triarylamine structure as a repeating unit.

[Second Polymer Used for Second Organic Layer]
As the second polymer having the triarylamine structure having no cross-linking group contained in the second organic layer as a repeating unit, it is preferable that the main chain of the polymer contains the triarylamine structure.
A repeating unit of the triarylamine structure is represented by the following formula (5).

(In formula (5),
Ar ⁴ is an aromatic hydrocarbon group optionally having a substituent other than a bridging group, an aromatic heterocyclic group optionally having a substituent other than a bridging group, or a substituent other than a bridging group represents a group in which a plurality of groups selected from an aromatic hydrocarbon group which may have and an aromatic heterocyclic group which may have a substituent other than a bridging group are linked,
Ar ⁵ is a divalent aromatic hydrocarbon group optionally having a substituent other than a bridging group, a divalent aromatic heterocyclic group optionally having a substituent other than a bridging group, or represents a divalent group in which at least one group selected from the group consisting of a divalent aromatic hydrocarbon group and the aforementioned divalent aromatic heterocyclic group is linked directly or via a linking group.
Ar ⁴ and Ar ⁵ may form a ring via a single bond or a linking group. )

( ^Ar4 )
In the repeating unit represented by the above formula (5), Ar ⁴ is an aromatic hydrocarbon group which may have a substituent other than a bridging group, and may have a substituent other than a bridging group. A plurality of aromatic heterocyclic groups selected from an aromatic heterocyclic group, an aromatic hydrocarbon group optionally having a substituent other than a bridging group, and an aromatic heterocyclic group optionally having a substituent other than a bridging group It represents a group in which groups are linked.

The aromatic hydrocarbon group preferably has 6 or more and 60 or less carbon atoms, and specifically includes a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, and chrysene ring. , a triphenylene ring, an acenaphthene ring, a fluoranthene ring, a fluorene ring and the like, a monovalent 6-membered ring or a 2 to 5 condensed ring monovalent group, or a group in which a plurality of these are linked. For example, "a monovalent group of a benzene ring" means "a benzene ring having a monovalent free atom valence", that is, a phenyl group.

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, and an oxadiazole ring. , indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, cinnoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring, etc. Examples include monocyclic to 6-membered ring, monovalent group of 2 to 4 condensed rings, and groups in which a plurality of these are linked.

Ar ⁴ is preferably an aromatic hydrocarbon group which may have a substituent other than a cross-linking group from the viewpoint of excellent charge transportability and durability, and among these, it has a substituent other than a cross-linking group. A monovalent group of a benzene ring or a fluorene ring which may be optionally used, i.e., a phenyl group or a fluorenyl group which may have a substituent other than a bridging group is more preferable, and may have a substituent other than a bridging group. A fluorenyl group that has a good fluorenyl group is more preferred, and a 2-fluorenyl group that may have a substituent other than a cross-linking group is particularly preferred.

Substituents other than the cross-linking group that the aromatic hydrocarbon group and aromatic heterocyclic group of Ar ⁴ may have are not particularly limited as long as they do not significantly reduce the properties of the present polymer. The substituent is preferably a group selected from the substituent group Z, more preferably an alkyl group, an alkoxy group, an aromatic hydrocarbon group, or an aromatic heterocyclic group, and still more preferably an alkyl group.

Ar ⁴ is preferably a fluorenyl group substituted with an alkyl group having 1 to 24 carbon atoms, particularly a 2-fluorenyl group substituted with an alkyl group having 4 to 12 carbon atoms, from the viewpoint of solubility in a coating solvent. preferable. Furthermore, a 9-alkyl-2-fluorenyl group in which the 9-position of the 2-fluorenyl group is substituted with an alkyl group is preferred, and a 9,9′-dialkyl-2-fluorenyl group in which the 9-position is substituted with an alkyl group is particularly preferred.

At least one of the 9-position and 9'-position is a fluorenyl group substituted with an alkyl group, so that the solubility in solvents and the durability of the fluorene ring tend to be improved. Furthermore, since both the 9- and 9'-positions are alkyl-substituted fluorenyl groups, the solubility in solvents and the durability of the fluorene ring tend to be further improved.

Ar ⁴ is also preferably a spirobifluorenyl group from the viewpoint of solubility in a coating solvent.

(other preferred Ar ⁴ )
At least one Ar ⁴ in the repeating unit represented by formula (5) above is also preferably a group represented by formula (10) below. The reason for this is that in the two carbazole structures in the following formula (10), LUMO is distributed in the aromatic hydrocarbon group or aromatic heterocyclic group between the nitrogen atoms of each other, and the main chain amine in formula (5) This is thought to be due to the fact that the influence on the amine is suppressed and the durability of the main chain amine to electrons and excitons is improved.

(In formula (10),
Ar ¹¹ and Ar ¹² are each independently an optionally substituted divalent aromatic hydrocarbon group or an optionally substituted divalent aromatic heterocyclic group,
Ar ¹³ to Ar ¹⁵ are each independently a hydrogen atom or a substituent.
* represents the bonding position to the nitrogen atom in formula (2). )

(Ar ¹³ to Ar ¹⁵ )
Ar ¹³ to Ar ¹⁵ each independently represent a hydrogen atom or a substituent. When Ar ¹³ to Ar ¹⁵ are substituents, the substituents are not particularly limited, but are preferably an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group. It is a cyclic group. Preferred structures are the same as the groups mentioned for Ar ⁴ above.

When Ar ¹³ to Ar ¹⁵ are substituents, it is preferred that Ar ¹³ to Ar ¹⁵ are bonded to the 3- or 6-position of each carbazole structure from the viewpoint of improving durability.

Ar ¹³ to Ar ¹⁵ are preferably hydrogen atoms from the viewpoint of ease of synthesis and charge transport properties.

Ar ¹³ to Ar ¹⁵ are an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group from the viewpoint of durability improvement and charge transport property. is preferred, and an optionally substituted aromatic hydrocarbon group is more preferred.

When Ar ¹³ to Ar ¹⁵ are an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group, the substituent group Z includes The substituents mentioned are the same, the preferred substituents are the same, and the substituents that these substituents may further have are also the same.

( ^Ar12 )
Ar ¹² is an optionally substituted divalent aromatic hydrocarbon group or an optionally substituted divalent aromatic heterocyclic group.

The aromatic hydrocarbon group preferably has 6 to 60 carbon atoms, more preferably 10 to 50 carbon atoms, and particularly preferably 12 to 40 carbon atoms. Specific examples of the aromatic hydrocarbon group include benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluoranthene ring, Examples include a 6-membered monocyclic ring or a divalent group of 2 to 5 condensed rings such as a fluorene ring, or a group in which a plurality of these are linked. When a plurality of these are linked, it is preferably a group in which a plurality of linked divalent aromatic hydrocarbon groups are conjugated.

The aromatic heterocyclic group preferably has 3 to 60 carbon atoms, and specific examples include furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring 5 or Examples include a 6-membered monocyclic ring, a divalent group of 2 to 4 condensed rings, and a group in which a plurality of these are linked.

Examples of the substituents that these aromatic hydrocarbon groups or aromatic heterocyclic groups may have include the alkyl groups, aralkyl groups and aromatic hydrocarbon groups of the substituent group Z described above. When the structure of Ar ¹² is twisted due to the steric effect of the substituent, it is preferable to have no substituent. When the structure of Ar ¹² is not twisted due to the steric effect of the substituent, it is preferable to have a substituent. .

A specific preferred group for Ar ¹² is a divalent group of a benzene ring, a naphthalene ring, anthracene ring, or a fluorene ring, or a group in which a plurality of these are linked, more preferably a divalent group of a benzene ring or a plurality of these It is a linked group, particularly preferably a 1,4-phenylene group in which a benzene ring is linked at the 1,4-position divalently, a 2,7-fluorenylene group in which a fluorene ring is linked at the 2,7-divalent position, Or a group in which a plurality of these are linked, most preferably a group containing "1,4-phenylene group-2,7-fluorenylene group-1,4-phenylene group-".

In these preferred structures, it is preferable that the phenylene group does not have a substituent other than at the linking position so that Ar ¹² is not twisted due to the steric effect of the substituent. Further, the fluorenylene group preferably has substituents at the 9 and 9′ positions from the viewpoint of improving solubility and durability of the fluorene structure.

(Ar ¹¹ )
Ar ¹¹ is a divalent group linked to the nitrogen atom of the main chain amine in formula (10). Ar ¹¹ is an optionally substituted divalent aromatic hydrocarbon group or an optionally substituted divalent aromatic heterocyclic group.

The aromatic hydrocarbon group for Ar ¹¹ preferably has 6 or more and 60 or less carbon atoms, more preferably 10 or more and 50 or less carbon atoms, and particularly preferably 12 or more and 40 or less carbon atoms. Specific examples of the aromatic hydrocarbon group include benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluoranthene ring, Examples include a 6-membered monocyclic ring or a divalent group of 2 to 5 condensed rings such as a fluorene ring, or a group in which a plurality of these are linked.

The aromatic heterocyclic group for Ar ¹¹ preferably has 3 or more and 60 or less carbon atoms. Specifically, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzoisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring or A group in which a plurality of these are linked is exemplified.

Examples of the substituents that these aromatic hydrocarbon groups or aromatic heterocyclic groups may have include the alkyl groups, aralkyl groups and aromatic hydrocarbon groups of the substituent group Z described above.

When a plurality of these divalent aromatic hydrocarbon groups or divalent aromatic heterocyclic groups are linked together, it is preferably a group in which the multiple linked divalent aromatic hydrocarbon groups are bonded so as not to be conjugated. Specifically, it preferably contains a 1,3-phenylene group or a group having a substituent and having a twisted structure due to the steric effect of the substituent.

( ^Ar5 )
The aromatic hydrocarbon group and aromatic hydrocarbon group for Ar ⁵ include the same groups as for Ar ⁴ in formula (5) and are divalent. Further, the aromatic hydrocarbon group in Ar ⁵ and the substituent which the aromatic hydrocarbon group may have are preferably the same groups as in the substituent group Z above.

(crosslinking group)
The second polymer used for the second organic layer does not have a cross-linking group.
Here, the cross-linking group means a group that reacts with other cross-linking groups located in the vicinity of the cross-linking group by irradiation with heat and/or active energy rays to form a new chemical bond. In this case, the reactive group may be the same group as the bridging group or a different group.

Examples of the cross-linking group include groups containing an alkenyl group, groups containing a conjugated diene structure, groups containing an alkynyl group, groups containing an oxirane structure, groups containing an oxetane structure, groups containing an aziridine structure, azide groups, and maleic anhydride structures. a group containing an alkenyl group bonded to an aromatic ring, a cyclobutene ring condensed to an aromatic ring, and the like. Specific examples of the cross-linking group include groups selected from the following cross-linking group T.

(Crosslinking Group T)

In the above bridging group T, R ^XL represents a methylene group, an oxygen atom or a sulfur atom, and n ^XL represents an integer of 0-5. When multiple R ^XL are present, they may be the same or different, and when multiple n ^XL are present, they may be the same or different. *1 represents the binding position. These cross-linking groups may have substituents.

Hereinafter, more preferable repeating units represented by the above formula (5) are “repeating units represented by formula (2)”, “repeating units represented by formula (3)”, and “repeating units represented by formula (4) Represented repeating unit” will be described in detail.

<Repeating Unit Represented by Formula (2)>

(In formula (2),
Ar ¹ is an aromatic hydrocarbon group optionally having a substituent other than a bridging group, an aromatic heterocyclic group optionally having a substituent other than a bridging group, or a substituent other than a bridging group. A group in which a plurality of groups selected from an aromatic hydrocarbon group which may have and an aromatic heterocyclic group which may have a substituent other than a bridging group are linked,
X is -C(R ⁷ )(R ⁸ )-, -N(R ⁹ )- or -C(R ¹¹ )(R ¹² )-C(R ¹³ )(R ¹⁴ )-;
R ¹ and R ² are each independently an alkyl group optionally having a substituent other than a bridging group,
R ⁷ to R ⁹ and R ¹¹ to R ¹⁴ are each independently a hydrogen atom, an alkyl group optionally having a substituent other than a bridging group, and optionally having a substituent other than a bridging group. an aromatic hydrocarbon group optionally having a substituent other than an aralkyl group or a bridging group,
a and b are each independently an integer of 0 to 4;
c is an integer from 1 to 3,
d is an integer from 0 to 4,
When there are multiple R ^1s , the multiple R ^1s may be the same or different,
When there are multiple R ² s, the multiple R ^2s may be the same or different. )

(R ¹ , R ² )
R ¹ and R ² in the repeating unit represented by formula (2) are each independently an alkyl group optionally having a substituent other than a bridging group.

The alkyl group is a linear, branched or cyclic alkyl group. Although the number of carbon atoms in the alkyl group is not particularly limited, it is preferably 1 or more, preferably 8 or less, more preferably 6 or less, and even more preferably 3 or less in order to maintain the solubility of the second polymer. More preferably, the alkyl group is a methyl group or an ethyl group.

When there is a plurality of R ¹ , the plurality of R ¹ may be the same or different, and when there is a plurality of R ^{2 , the plurality of R 2 may} be the same or different. All R ¹ and R ² are preferably the same group because the charge can be uniformly distributed around the nitrogen atom and the synthesis is easy.

(R ⁷ to R ⁹ and R ¹¹ to R ¹⁴ )
R ⁷ to R ⁹ and R ¹¹ to R ¹⁴ are each independently a hydrogen atom, an alkyl group optionally having a substituent other than a bridging group, and optionally having a substituent other than a bridging group. It is an aromatic hydrocarbon group which may have a substituent other than an aralkyl group or a bridging group.

The alkyl group is not particularly limited, but since it tends to improve the solubility of the second polymer, the number of carbon atoms is preferably 1 or more, preferably 24 or less, more preferably 8 or less, and further preferably 6 or less. preferable. Also, the alkyl group may have a linear, branched or cyclic structure.

Specific examples of the alkyl group include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group and n-hexyl group. , n-octyl group, cyclohexyl group, dodecyl group and the like.

The aralkyl group is not particularly limited, but preferably has 5 or more carbon atoms, preferably 60 or less, and more preferably 40 or less, because it tends to improve the solubility of the second polymer.

Specific examples of the aralkyl group include 1,1-dimethyl-1-phenylmethyl group, 1,1-di(n-butyl)-1-phenylmethyl group, 1,1-di(n-hexyl)- 1-phenylmethyl group, 1,1-di(n-octyl)-1-phenylmethyl group, phenylmethyl group, phenylethyl group, 3-phenyl-1-propyl group, 4-phenyl-1-n-butyl group , 1-methyl-1-phenylethyl group, 5-phenyl-1-n-propyl group, 6-phenyl-1-n-hexyl group, 6-naphthyl-1-n-hexyl group, 7-phenyl-1- n-heptyl group, 8-phenyl-1-n-octyl group, 4-phenylcyclohexyl group and the like.

The aromatic hydrocarbon group is not particularly limited, but preferably has 6 or more carbon atoms, preferably 60 or less, and more preferably 30 or less, because it tends to improve the solubility of the second polymer.

Specific examples of the aromatic hydrocarbon group include benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluoranthene ring, and fluorene. A 6-membered monocyclic or 2-5 condensed monovalent group such as a ring, or a group in which a plurality of these are linked, and the like can be mentioned.

From the viewpoint of improving charge transport properties and durability, R ⁷ and R ⁸ are preferably methyl groups or aromatic hydrocarbon groups, R ⁷ and R ⁸ are more preferably methyl groups, and R ⁹ is a phenyl group. is more preferable.

The alkyl groups for R ¹ and R ² , the alkyl groups for R ⁷ to R ⁹ and R ¹¹ to R ¹⁴ , the aralkyl groups and the aromatic hydrocarbon groups may have a substituent other than a bridging group. Substituents other than the bridging group include the groups exemplified as preferable alkyl groups, aralkyl groups and aromatic hydrocarbon groups for R ⁷ to R ⁹ and R ¹¹ to R ¹⁴ .

The alkyl groups of R ¹ and R ² , the alkyl groups of R ⁷ to R ⁹ and R ¹¹ to R ¹⁴ , the aralkyl groups and the aromatic hydrocarbon groups may not have substituents from the viewpoint of lowering the voltage. Most preferred.

(a, b, c and d)
In the repeating unit represented by formula (2) above, a and b are each independently an integer of 0-4. It is preferable that a+b is 1 or more, more preferably each of a and b is 2 or less, and more preferably both a and b are 1.

When a + b is 1 or more, the aromatic ring of the main chain is twisted due to steric hindrance, and the solubility of the second polymer in the solvent is excellent, and the coating film formed by the wet film formation method and heat-treated is solvent It tends to be excellent in insolubility in Therefore, when a + b is 1 or more, when forming another organic layer (for example, a light-emitting layer) on this coating film by a wet film-forming method, the composition for forming a light-emitting layer of the present invention containing an organic solvent elution of the second polymer is suppressed. As a result, it is considered that the formed light-emitting layer is less affected and the driving life of the quantum dot light-emitting device is further extended.

In the repeating unit represented by formula (2) above, c is an integer of 1-3 and d is an integer of 0-4. Each of c and d is preferably 2 or less, more preferably c and d are equal, and it is particularly preferable that both c and d are 1 or both c and d are 2.

When both c and d in the repeating unit represented by the above formula (2) are 1 or both c and d are 2 and both a and b are 2 or 1, R ¹ and R ² are most preferably bonded at symmetrical positions.

Here, the binding of R ¹ and R ² at positions symmetrical to each other means the binding position of R ¹ and R ² with respect to the fluorene ring, carbazole ring or 9,10-dihydrophenanthrene derivative structure in formula (2). is symmetrical. At this time, 180° rotation around the main chain is regarded as the same structure.

(Ar ¹ )
In the repeating unit represented by the above formula (2), Ar ¹ may have a substituent other than an aromatic hydrocarbon group which may have a substituent other than a bridging group and a bridging group. A plurality of aromatic heterocyclic groups selected from an aromatic heterocyclic group, an aromatic hydrocarbon group optionally having a substituent other than a bridging group, and an aromatic heterocyclic group optionally having a substituent other than a bridging group It is a group in which groups are linked.

Having an aromatic hydrocarbon group which may have a substituent other than a bridging group, an aromatic heterocyclic group which may have a substituent other than a bridging group, or a substituent other than a bridging group The group in which a plurality of groups selected from aromatic hydrocarbon groups and aromatic heterocyclic groups which may have substituents other than a bridging group are linked is the same as in the case of Ar ⁴ . and the substituents other than the bridging group and the preferred structure are also the same as in the case of Ar ⁴ above.

(other preferred Ar ¹ )
At least one Ar ¹ in the repeating unit represented by formula (2) above is more preferably a group represented by formula (10) above.

(X)
X in the above formula (2) is preferably -C(R ⁷ )(R ⁸ )- or -N(R ⁹ )- because of its high stability during charge transport, and -C(R ⁷ )(R ⁸ )— is more preferred.

Moreover, in the polymer containing the repeating unit represented by the above formula (2), when there are a plurality of Ar ¹ , R ¹ , R ² and X, they may be the same or different. Preferably, the polymer contains a plurality of repeating units in which the repeating units represented by formula (2) have the same structure. In this case, since the polymer contains a plurality of repeating units with the same structure, the HOMO and LUMO of the repeating units are the same, so that the charge is not concentrated at a specific shallow level and becomes a trap, and the charge transport property It is considered to be superior to

(preferred repeating unit)
The repeating unit represented by formula (2) above is particularly preferably a repeating unit represented by any one of the following formulas (2-1) to (2-4).

In the formula above, R ¹ and R ² are the same, and R ¹ and R ² are bonded at symmetrical positions.

<Specific example of main chain of repeating unit represented by formula (2)>
Although the main chain structure excluding the nitrogen atom in the above formula (2) is not particularly limited, examples thereof include the following structures.

<Content of Repeating Unit Represented by Formula (2)>
In the second polymer contained in the second organic layer, the content of the repeating unit represented by formula (2) is not particularly limited, but the repeating unit represented by formula (2) is the second polymer It is usually contained in an amount of 10 mol% or more, preferably 30 mol% or more, more preferably 40 mol% or more, further preferably 50 mol% or more.

In the second polymer contained in the second organic layer, the repeating unit may be composed only of repeating units represented by formula (2), but the performance when used as a quantum dot light-emitting device is For balancing purposes, it may have repeating units other than formula (2). In that case, the content of the repeating unit represented by formula (2) in the second polymer is usually 99 mol % or less, preferably 95 mol % or less.

<Terminal group>
As used herein, a terminal group refers to the terminal structure of the second polymer formed by the endcapping agent used to terminate the polymerization of the second polymer. In the second organic layer, the terminal group of the second polymer containing repeating units represented by formula (2) is preferably a hydrocarbon group. From the viewpoint of charge transportability, the hydrocarbon group is preferably a hydrocarbon group having 1 to 60 carbon atoms, more preferably a hydrocarbon group having 1 to 40 carbon atoms, and even more preferably a hydrocarbon group having 1 to 30 carbon atoms.

Examples of hydrocarbon groups include
carbon, such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, n-hexyl group, cyclohexyl group, dodecyl group A linear, branched or cyclic alkyl group whose number is usually 1 or more, preferably 4 or more, usually 24 or less, preferably 12 or less;
A linear, branched, or cyclic alkenyl group having usually 2 or more and 24 or less, preferably 12 or less carbon atoms, such as a vinyl group;
A linear or branched alkynyl group having usually 2 or more and 24 or less, preferably 12 or less carbon atoms, such as an ethynyl group;
aromatic hydrocarbon groups having usually 6 or more and 36 or less, preferably 24 or less carbon atoms, such as phenyl group and naphthyl group;

These hydrocarbon groups may further have a substituent, and the substituent which may further have is preferably an alkyl group or an aromatic hydrocarbon group. When there are a plurality of these substituents which may be additionally contained, they may be combined with each other to form a ring.

The terminal group is preferably an alkyl group or an aromatic hydrocarbon group, more preferably an aromatic hydrocarbon group, from the viewpoint of charge transportability and durability.

<Repeating Unit Represented by Formula (3)>

(In formula (3),
Ar ² is an aromatic hydrocarbon group optionally having a substituent other than a bridging group, an aromatic heterocyclic group optionally having a substituent other than a bridging group, or a substituent other than a bridging group. A group in which a plurality of groups selected from an aromatic hydrocarbon group which may have and an aromatic heterocyclic group which may have a substituent other than a bridging group are linked,
R ³ and R ⁶ are each independently an alkyl group optionally having a substituent other than a bridging group,
R ⁴ and R ⁵ are each independently an alkyl group optionally having a substituent other than a bridging group, an alkoxy group optionally having a substituent other than a bridging group, or a substituent other than a bridging group is an aralkyl group optionally having
l is 0 or 1,
m is 1 or 2,
k is 0 or 1,
p is 0 or 1,
q is 0 or 1; )

(R ³ , R ⁶ )
R ³ and R ⁶ in the repeating unit represented by formula (3) are each independently an alkyl group optionally having a substituent other than a bridging group.
Examples of the alkyl group include the same as those for R ¹ and R ² in the formula (2), and the same substituents and preferred structures as those for R ¹ and R ² may be included.

^{( R4} , R5)
R ⁴ and R ⁵ in the repeating unit represented by the formula (3) are each independently an alkyl group optionally having a substituent other than a bridging group, and a substituent other than a bridging group. is an alkoxy group which may be substituted or an aralkyl group which may have a substituent other than a bridging group.

The alkyl group is a linear, branched or cyclic alkyl group. Although the number of carbon atoms in the alkyl group is not particularly limited, it is preferably 1 or more, preferably 24 or less, more preferably 8 or less, and even more preferably 6 or less, because it tends to improve the solubility of the polymer.

Specific examples of the alkyl group include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group and n-hexyl. group, n-octyl group, cyclohexyl group, dodecyl group and the like.

The alkoxy group is not particularly limited, and the alkyl group represented by R ¹⁰ of the alkoxy group (-OR ¹⁰ ) may have any structure of linear, branched or cyclic, and improves the solubility of the polymer. Therefore, the number of carbon atoms is preferably 1 or more, preferably 24 or less, and more preferably 12 or less.

Specific examples of the alkoxy group include methoxy, ethoxy, n-propoxy, n-butoxy, hexyloxy, 1-methylpentyloxy, cyclohexyloxy and the like.

The aralkyl group is not particularly limited, but preferably has 5 or more carbon atoms, preferably 60 or less, and more preferably 40 or less, because it tends to improve the solubility of the polymer.

Specific examples of the aralkyl group include 1,1-dimethyl-1-phenylmethyl group, 1,1-di(n-butyl)-1-phenylmethyl group, 1,1-di(n-hexyl) -1-phenylmethyl group, 1,1-di(n-octyl)-1-phenylmethyl group, phenylmethyl group, phenylethyl group, 3-phenyl-1-propyl group, 4-phenyl-1-n-butyl group, 1-methyl-1-phenylethyl group, 5-phenyl-1-n-propyl group, 6-phenyl-1-n-hexyl group, 6-naphthyl-1-n-hexyl group, 7-phenyl-1 -n-heptyl group, 8-phenyl-1-n-octyl group, 4-phenylcyclohexyl group and the like.

(l, m and k)
l represents 0 or 1, k represents 0 or 1;

l and k are each independent, and l+k is preferably 1 or more, more preferably 1 or 2, and still more preferably 2. When l+k is within the above range, the solubility of the second polymer contained in the second organic layer is increased, and precipitation from the second composition containing the polymer tends to be suppressed.

m represents 1 or 2, and is preferably 1 because the quantum dot light-emitting device of the present invention can be driven at a low voltage and the hole injection ability, transport ability, and durability tend to be improved.

(p and q)
p represents 0 or 1; q represents 0 or 1; If l=k=1, p and q cannot be 0 at the same time. Since p and q are not 0 at the same time, the solubility of the second polymer contained in the second organic layer is increased, and precipitation from the second composition containing the polymer tends to be suppressed. be. For the same reason as a and b above, when p+q is 1 or more, the driving life of the quantum dot light-emitting device is considered to be longer, which is preferable.

⁽ Ar2)
In the repeating unit represented by the above formula (3), Ar ² is an aromatic hydrocarbon group which may have a substituent other than a bridging group, and may have a substituent other than a bridging group. A plurality of aromatic heterocyclic groups selected from an aromatic heterocyclic group, an aromatic hydrocarbon group optionally having a substituent other than a bridging group, and an aromatic heterocyclic group optionally having a substituent other than a bridging group It is a group in which groups are linked.

An aromatic hydrocarbon group which may have a substituent other than the bridging group, an aromatic heterocyclic group which may have a substituent other than the bridging group, or a substituent other than the bridging group The group in which a plurality of groups selected from aromatic hydrocarbon groups and aromatic heterocyclic groups which may have substituents other than a bridging group are linked is Ar ¹ in the above formula (2). Examples are the same as in the case of Ar 1, and the substituents other than the cross-linking group and the preferred structure are also the same as in the case of Ar ¹ above.

Ar ² is also preferably a spirobifluorenyl group from the viewpoint of solubility in a coating solvent.

In particular, Ar ² is preferably a group represented by the following formula (15) or a group represented by the following formula (16).

(In formulas (15) and (16), * represents the bonding position with the nitrogen atom in formula (3).)

(other preferred Ar ² )
As with Ar ¹ , at least one Ar ² is preferably a group represented by formula (10). In the case where at least one of Ar ² is a group represented by the formula (10), the preferred structure of the formula (10) and the substituents that may be present are such that at least one of the Ar ¹ is the formula ( It is the same as the group represented by 10).

<Specific example of main chain of repeating unit represented by formula (3)>
Although the main chain structure excluding the nitrogen atom in formula (3) is not particularly limited, examples thereof include the following structures.

<Content of Repeating Unit Represented by Formula (3)>
In the second polymer contained in the second organic layer, the content of the repeating unit represented by formula (3) is not particularly limited, but the repeating unit represented by formula (3) is usually the second polymer. It is contained in the coalescence at 10 mol% or more, preferably 30 mol% or more, more preferably 40 mol% or more, and particularly preferably 50 mol% or more.

In the second polymer contained in the second organic layer, the repeating unit may be composed only of repeating units represented by formula (3), but the performance when used as a quantum dot light-emitting device is For balancing purposes, it may have repeating units other than formula (3). In that case, the content of the repeating unit represented by formula (3) in the second polymer is usually 99 mol % or less, preferably 95 mol % or less.

<Terminal group>
In the second polymer contained in the second organic layer, the terminal group of the second polymer containing the repeating unit represented by the formula (3) contains the repeating unit represented by the above formula (2) Like the terminal groups of the second polymer, they are preferably hydrocarbon groups. Preferred hydrocarbon groups and substituents that may be present are also the same as the terminal groups of the polymer containing the repeating unit represented by formula (2) above.

[Repeating unit represented by formula (4)]

(In formula (4),
Ar ³ is an aromatic hydrocarbon group optionally having a substituent other than a bridging group, an aromatic heterocyclic group optionally having a substituent other than a bridging group, or a substituent other than a bridging group. A group in which a plurality of groups selected from an aromatic hydrocarbon group which may have and an aromatic heterocyclic group which may have a substituent other than a bridging group are linked,
Ar ⁴¹ is a divalent aromatic hydrocarbon group optionally having a substituent other than a bridging group, a divalent aromatic heterocyclic group optionally having a substituent other than a bridging group, or at least one group selected from the group consisting of a divalent aromatic hydrocarbon group and the divalent aromatic heterocyclic group is a divalent group in which a plurality of groups are linked directly or via a linking group,
R ⁴¹ and R ⁴² are each independently an alkyl group optionally having a substituent other than a bridging group,
t is 1 or 2;
u is 0 or 1,
r and s are each independently an integer of 0-4. )

( ^R41 , ^R42 )
R ⁴¹ and R ⁴² in the repeating unit represented by formula (4) are each independently an alkyl group optionally having a substituent other than a bridging group.

The alkyl group is a linear, branched or cyclic alkyl group. 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, preferably 10 or less, more preferably 8 or less, and more preferably 6 or less. More preferably, the alkyl group is a methyl group or a hexyl group.

When a plurality of R ⁴¹ and R ⁴² are present in the repeating unit represented by formula (4) above, the plurality of R ⁴¹ and R ⁴² may be the same or different.

(r, s, t and u)
In the repeating unit represented by formula (4), r and s are each independently an integer of 0-4. r+s is preferably 1 or more, and r and s are each preferably 2 or less. When r+s is 1 or more, the drive life of the quantum dot light-emitting device is considered to be longer for the same reason as a and b in the formula (2).

In the repeating unit represented by formula (4) above, t is 1 or 2, and u is 0 or 1. t is preferably 1 and u is preferably 1.

( ^Ar3 )
In the repeating unit represented by the above formula (4), Ar ³ is an aromatic hydrocarbon group which may have a substituent other than a bridging group, and may have a substituent other than a bridging group. A plurality of aromatic heterocyclic groups selected from an aromatic heterocyclic group, an aromatic hydrocarbon group optionally having a substituent other than a bridging group, and an aromatic heterocyclic group optionally having a substituent other than a bridging group It is a group in which groups are linked.

Having an aromatic hydrocarbon group which may have a substituent other than a bridging group, an aromatic heterocyclic group which may have a substituent other than a bridging group, or a substituent other than a bridging group As a group in which a plurality of groups selected from an aromatic heterocyclic group which may have a substituent other than an aromatic hydrocarbon group and a bridging group are linked, Ar ⁴ in the formula (5) and the substituents other than the bridging group and the preferred structure are also the same as in the case of Ar ⁴ .

( ^Ar41 )
Ar ⁴¹ is a divalent aromatic hydrocarbon group optionally having a substituent other than a bridging group, a divalent aromatic heterocyclic group optionally having a substituent other than a bridging group, or A divalent group in which a plurality of at least one group selected from the group consisting of a divalent aromatic hydrocarbon group and the aforementioned divalent aromatic heterocyclic group are linked directly or via a linking group.

The aromatic hydrocarbon group and aromatic hydrocarbon group for Ar ⁴¹ include the same groups as for Ar ⁵ in the formula (5). In addition, the aromatic hydrocarbon group and the substituent that the aromatic hydrocarbon group may have are preferably the same groups as in the substituent group Z, and the substituent that may further be included in the substituent group Z is preferably the same as

<Specific examples of repeating units represented by formula (4)>
Although the repeating unit represented by formula (4) is not particularly limited, examples thereof include the following structures.

<Content of Repeating Unit Represented by Formula (4)>
In the second polymer contained in the second organic layer, the content of the repeating unit represented by formula (4) is not particularly limited, but the repeating unit represented by formula (4) is usually the second polymer. It is contained in the coalescence at 10 mol% or more, preferably 30 mol% or more, more preferably 40 mol% or more, and particularly preferably 50 mol% or more.

In the second polymer contained in the second organic layer, the repeating unit may be composed only of repeating units represented by formula (4), but the performance when used as a quantum dot light-emitting device is For balancing purposes, it may have repeating units other than formula (4). In that case, the content of the repeating unit represented by formula (4) in the second polymer is usually 99 mol % or less, preferably 95 mol % or less.

<Terminal group>
In the second polymer contained in the second organic layer, the terminal group of the polymer containing the repeating unit represented by the formula (4) is the second polymer containing the repeating unit represented by the above formula (2). Like the terminal groups of the polymer, they are preferably hydrocarbon groups. Preferred hydrocarbon groups and substituents that may be present are also the same as the terminal groups of the polymer containing the repeating unit represented by formula (2) above.

[Molecular Weight of Second Polymer]
The molecular weight of the second polymer contained in the second organic layer is described below.

The weight average molecular weight (Mw) of the second polymer containing the repeating unit represented by formula (2) is usually 3,000,000 or less, preferably 1,000,000 or less, more preferably 500,000 or less. , more preferably 200,000 or less, and particularly preferably 100,000 or less. The weight average molecular weight is usually 2,500 or more, preferably 5,000 or more, more preferably 10,000 or more, still more preferably 15,000 or more, and particularly preferably 17,000 or more.

When the weight-average molecular weight of the second polymer containing the repeating unit represented by formula (2) is equal to or less than the above upper limit value, solubility in a solvent is obtained, and film-forming properties tend to be excellent. Further, when the weight average molecular weight of the polymer is at least the above lower limit, the decrease in the glass transition temperature, melting point and vaporization temperature of the polymer may be suppressed, and the heat resistance may be improved.

In addition, the number average molecular weight (Mn) of the second polymer containing the repeating unit represented by formula (2) is usually 2,500,000 or less, preferably 750,000 or less, more preferably 400,000 or less. , particularly preferably 100,000 or less. Moreover, the number average molecular weight is usually 2,000 or more, preferably 4,000 or more, more preferably 6,000 or more, and still more preferably 8,000 or more.

Furthermore, the dispersion degree (Mw/Mn) of the second polymer containing the repeating unit represented by formula (2) is preferably 3.5 or less, more preferably 2.5 or less, and particularly preferably 2.0. It is below. Note that the lower limit value is ideally 1 because the smaller the value of the degree of dispersion, the better. When the degree of dispersion of the polymer is equal to or less than the above upper limit, purification is easy, and solubility in a solvent and charge transportability are good.

The weight average molecular weight (Mw) of the second polymer containing the repeating unit represented by formula (3) or formula (4) is preferably 10,000 or more, more preferably 15,000 or more, More preferably, it is 17,000 or more. Also, the weight average molecular weight is preferably 2,000,000 or less, more preferably 1,000,000 or less, and particularly preferably 100,000 or less.

When the weight-average molecular weight of the second polymer containing the repeating unit represented by formula (3) or formula (4) is equal to or less than the above upper limit, impurities can be suppressed from increasing in molecular weight and purification can be easily performed. There is a tendency. Further, when the weight-average molecular weight of the polymer is at least the above lower limit, the decrease in glass transition temperature, melting point, vaporization temperature, etc. is suppressed, and heat resistance tends to be improved.

Further, the number average molecular weight (Mn) of the second polymer containing repeating units represented by formula (3) or formula (4) is preferably 1,000,000 or less, more preferably 800,000. or less, more preferably 500,000 or less. Also, the number average molecular weight is preferably 4,000 or more, more preferably 8,000 or more, and still more preferably 10,000 or more.

Furthermore, the dispersity (Mw/Mn) of the second polymer containing the repeating unit represented by formula (3) or formula (4) is preferably 3.5 or less, more preferably 3.0 or less. is more preferably 2.4 or less, particularly preferably 2.1 or less, and most preferably 2 or less. Further, the dispersion degree of the polymer is preferably 1 or more, more preferably 1.1 or more, and still more preferably 1.2 or more. When the degree of dispersion of the polymer is equal to or less than the above upper limit, purification is facilitated, and there is a tendency to suppress a decrease in solubility in a solvent and a decrease in charge-transporting ability.

The weight average molecular weight and number average molecular weight of a polymer are usually determined by SEC (size exclusion chromatography) measurements. In SEC measurement, the higher the molecular weight, the shorter the elution time, and the lower the molecular weight, the longer the elution time. By conversion, the weight average molecular weight and number average molecular weight are calculated.

[Concrete example]
Specific examples of the second polymer containing the repeating unit represented by formula (2) are shown below, but the second polymer used in the present invention is not limited to these. The numbers in the chemical formulas represent the molar ratio of repeating units. n represents the number of repetitions.

These second polymers may be random copolymers, alternating copolymers, block copolymers, graft copolymers, or the like, and the sequence of the monomers is not limited.

A second polymer containing a repeating unit represented by formula (3) and a second polymer having a structure in which Ar ² of the repeating unit represented by formula (3) is represented by formula (10) Specific examples are shown below, but the second polymer used in the present invention is not limited to these. The numbers in the chemical formulas represent the molar ratio of repeating units. n represents the number of repetitions.

These second polymers may be random copolymers, alternating copolymers, block copolymers, graft copolymers, or the like, and the sequence of the monomers is not limited.

Specific examples of the second polymer containing the repeating unit represented by formula (4) are shown below, but the second polymer used in the present invention is not limited to these. The numbers in the chemical formulas represent the molar ratio of repeating units. n represents the number of repetitions.

These second polymers may be random copolymers, alternating copolymers, block copolymers, graft copolymers, or the like, and the sequence of the monomers is not limited.

<Method for producing the second polymer>
The method for producing the second polymer contained in the second organic layer is not particularly limited and is arbitrary. Examples thereof include a polymerization method by Suzuki reaction, a polymerization method by Grignard reaction, a polymerization method by Yamamoto reaction, a polymerization method by Ullmann reaction, a polymerization method by Buchwald-Hartwig reaction, and the like.

In the case of the polymerization method by the Ullmann reaction and the polymerization method by the Buchwald-Hartwig reaction, for example, an aryl dihalide represented by the following formula (2a) (Z represents a halogen atom such as I, Br, Cl, F) and the following A second polymer containing the repeating unit represented by the formula (2) is synthesized by reacting it with a primary aminoaryl represented by the formula (2b).

(In the above reaction formula, Ar ¹ , R ¹ , R ² , X, and a to d have the same meanings as in formula (2) above.)

Further, in the case of the polymerization method by the Ullmann reaction and the polymerization method by the Buchwald-Hartwig reaction, for example, an aryl dihalide represented by the formula (3a) (Z represents a halogen atom such as I, Br, Cl, F) and A polymer containing a repeating unit represented by formula (3) is synthesized by reacting it with a primary aminoaryl represented by formula (3b).

(In the above reaction formula, Ar ² , R ³ to R ⁶ , km to m, p, and q have the same meanings as in formula (3) above.)

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

[Second composition]
The second composition forming the second organic layer will be described below.
The second composition contains a second polymer and a solvent (organic solvent). This second composition is generally used to form the organic layers of the quantum dot light-emitting device of the present invention by a wet film-forming method. The organic layer is preferably a hole-transporting layer adjacent to a light-emitting layer formed from the composition for forming a light-emitting layer of the present invention. The second composition may contain one type of the second polymer, or may contain two or more types in any combination and in any ratio.

(Content of second polymer)
The content of the second polymer in the second composition is usually 0.01% by mass or more and 70% by mass or less, preferably 0.1% by mass or more and 60% by mass, more preferably 0.5% by mass. % or more and 50 mass % or less. When the content of the second polymer is within the above range, defects are less likely to occur in the formed organic layer, and film thickness unevenness is less likely to occur, which is preferable.

(solvent)
The second composition usually contains a solvent. This solvent preferably dissolves the second polymer. Specifically, a solvent capable of dissolving the second polymer in the second composition at room temperature in an amount of usually 0.05% by mass or more, preferably 0.5% by mass or more, and more preferably 1% by mass or more is suitable. is.

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

In addition, one solvent may be used, or two or more solvents may be used in any combination and in any ratio.

The surface tension of the solvent at 20° C. is generally less than 40 dyn/cm, preferably 36 dyn/cm or less, more preferably 33 dyn/cm or less.

On the other hand, the vapor pressure of the solvent at 25° C. is usually 10 mmHg or less, preferably 5 mmHg or less, and usually 0.1 mmHg or more. By using such a solvent, it is possible to prepare a second composition suitable for the process of manufacturing a quantum dot light-emitting device by a wet film-forming method and suitable for the properties of the second polymer.

Specific examples of such solvents include aromatic solvents such as toluene, xylene, mesitylene and cyclohexylbenzene, ether solvents and ester solvents.

By the way, moisture may cause performance deterioration of the quantum dot light-emitting device, and in particular, it may promote a decrease in luminance during continuous driving. Therefore, in order to reduce water remaining during wet film formation as much as possible, the solubility of the solvent in water at 25° C. is preferably 1% by mass or less, more preferably 0.1% by mass or less.

The content of the solvent in the second composition is usually 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, and particularly preferably 80% by mass or more. When the content of the solvent is at least the above lower limit, the flatness and uniformity of the formed layer can be improved.

[Electron-accepting compound]
The second composition preferably further contains an electron-accepting compound in order to reduce the resistance. Especially when the second composition is used to form a hole injection layer, the second composition preferably contains an electron-accepting compound.

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

The second composition may contain one of the above electron-accepting compounds alone, or may contain two or more in any combination and ratio.

When the second composition contains an electron-accepting compound, the content of the electron-accepting compound in the second composition is usually 0.0005% by mass or more, preferably 0.001% by mass or more, and usually It is 20% by mass or less, preferably 10% by mass or less.

The ratio of the electron-accepting compound to the second polymer in the second composition is usually 0.5% by mass or more, preferably 1% by mass or more, more preferably 3% by mass or more, and is usually 80% by mass or more. % by mass or less, preferably 60% by mass or less, more preferably 40% by mass or less.

It is preferable that the content of the electron-accepting compound in the second composition is at least the above lower limit, because the electron acceptor accepts electrons from the second polymer and the resistance of the formed organic layer is lowered. When the content of the electron-accepting compound in the second composition is equal to or less than the above upper limit, defects are less likely to occur in the formed organic layer, and film thickness unevenness is less likely to occur, which is preferable.

[Cation Radical Compound]
The second composition may further contain a cation radical compound.
The cation radical compound is preferably an ionic compound composed of a cation radical, which is a chemical species obtained by removing one electron from a hole-transporting compound, and a counter anion. However, when the cation radical is derived from a hole-transporting polymer compound, the cation radical has a structure in which one electron is removed from the repeating unit of the polymer compound.

Moreover, the cation radical is preferably a chemical species obtained by removing one electron from the hole-transporting compound described later. From the viewpoints of amorphousness, visible light transmittance, heat resistance, solubility, and the like, chemical species obtained by removing one electron from a compound that is preferable as a hole-transporting compound is preferable.

Here, the cation radical compound can be produced by mixing the hole-transporting compound described later and the electron-accepting compound described above. That is, by mixing the hole-transporting compound and the electron-accepting compound, electron transfer occurs from the hole-transporting compound to the electron-accepting compound, and the cation radical of the hole-transporting compound and the counter anion A cationic compound is produced.

When the second composition contains a cation radical compound, the content of the cation radical compound in the second composition is usually 0.0005% by mass or more, preferably 0.001% by mass or more, and usually 40% by mass. Below, preferably 20% by mass or less. When the content of the cation radical compound is at least the above lower limit, the resistance of the formed organic layer is preferably reduced. .

In addition to the above components, the second composition contains components contained in the hole injection layer-forming composition and the hole transport layer-forming composition, which will be described later, in the amounts described later. good too.

[Structure of quantum dot light-emitting device]
As an example of the structure of the quantum dot light emitting device of the present invention, FIG. 1 shows a schematic diagram (cross section) of a structural example of a quantum dot light emitting device 8. As shown in FIG. In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transport layer, 5 is a light emitting layer, 6 is an electron transport layer, and 7 is a cathode.

<Substrate>
The substrate 1 serves as a support for the quantum dot light-emitting device, and is usually made of quartz or glass plate, metal plate or metal foil, plastic film or sheet, or the like. Among these, glass plates and transparent synthetic resin plates such as polyester, polymethacrylate, polycarbonate and polysulfone are preferred. The substrate is preferably made of a material having a high gas barrier property because deterioration of the quantum dot light-emitting element due to outside air is unlikely to occur. Therefore, especially when using a material having low gas barrier properties such as a synthetic resin substrate, it is preferable to provide a dense silicon oxide film or the like on at least one side of the substrate to improve the gas barrier properties.

<Anode>
The anode 2 has the function of injecting holes into the layer on the light-emitting layer 5 side.

Anode 2 is typically made of metals such as aluminum, gold, silver, nickel, palladium, platinum; metal oxides such as indium and/or tin oxide; metal halides such as copper iodide; carbon black and poly(3 -methylthiophene), polypyrrole, and polyaniline.

The anode 2 is usually formed by a dry method such as a sputtering method or a vacuum deposition method. In addition, when the anode is formed using metal fine particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, conductive polymer fine powder, etc., it may be added to an appropriate binder resin solution. It can also be formed by dispersing and coating on a substrate. In the case of a conductive polymer, a thin film can be formed directly on a substrate by electrolytic polymerization, or an anode can be formed by coating a conductive polymer on a substrate (Appl. Phys. Lett., 60 2711, 1992).

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

The thickness of the anode 2 may be determined according to the required transparency and material. When particularly high transparency is required, the thickness is preferably such that the visible light transmittance is 60% or more, and more preferably the thickness is such that the visible light transmittance is 80% or more. 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 set according to the required strength, etc. In this case, the thickness of the anode 2 may be the same as that of the substrate.

When another layer is formed on the surface of the anode 2, the impurity on the anode 2 is removed and its ionization potential is changed by treating with ultraviolet rays/ozone, oxygen plasma, argon plasma, etc. before the film formation. is preferably adjusted to improve the hole injection property.

<Hole injection layer>
A layer that functions to transport 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 function to transport holes from the anode 2 side to the light emitting layer 5 side, the layer closer to the anode side may be called the 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 forming the hole injection layer 3 , the hole injection layer 3 is usually formed on the anode 2 .

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

A method for forming the hole injection layer may be a vacuum deposition method or a wet film formation method. From the viewpoint of excellent film-forming properties, it is preferable to form the film by a wet film-forming method.

A general method for forming a hole injection layer will be described below. In the quantum dot light emitting device of the present invention, the hole injection layer is formed by a wet film formation method using a composition for forming a hole injection layer. preferably.

(Hole-transporting compound)
The hole injection layer-forming composition usually contains a hole-transporting compound that forms the hole injection layer 3 . Moreover, the composition for forming a hole injection layer usually further contains a solvent in the case of the wet film-forming method. It is preferable that the composition for forming a hole injection layer has a high hole-transporting property and can efficiently transport the injected holes. For this reason, it is preferable that the hole mobility is large and that impurities that become traps are less likely to occur during manufacture or use. Moreover, it is preferable that it has excellent stability, a small ionization potential, and a high transparency to visible light. In particular, when the hole injection layer is in contact with the light-emitting layer, it is preferable to use a material that does not quench light emitted from the light-emitting layer or that forms an exciplex with the light-emitting layer so as not to lower the light emission efficiency.

The hole-transporting compound is preferably a compound having an ionization potential of 4.5 eV to 6.0 eV from the viewpoint of a charge injection barrier from the anode to the hole injection layer. Examples of hole-transporting compounds include aromatic amine-based compounds, phthalocyanine-based compounds, porphyrin-based compounds, oligothiophene-based compounds, polythiophene-based compounds, benzylphenyl-based compounds, compounds in which tertiary amines are linked with fluorene groups, and hydrazones. compounds, silazane compounds, quinacridone compounds, and the like.

Among the exemplified compounds described above, aromatic amine compounds are preferred, and aromatic tertiary amine compounds are particularly preferred, from the viewpoints of amorphousness and visible light transmittance. Here, the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and includes a compound having a group derived from an aromatic tertiary amine.

The type of the aromatic tertiary amine compound is not particularly limited, but from the point that uniform light emission is easily obtained due to the surface smoothing effect, a polymer compound having a weight average molecular weight of 1,000 or more and 1,000,000 or less (repeated It is preferable to use a polymerizable compound in which units are linked.

(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 is usually mixed with a soluble solvent (solvent for the hole injection layer) to form a film formation composition (hole Injection layer forming composition) is prepared. Then, the hole injection layer 3 is formed by coating the hole injection layer forming composition on the layer (usually the anode) corresponding to the lower layer of the hole injection layer to form a film and drying it.

The concentration of the hole-transporting compound in the hole-injection layer-forming composition is arbitrary as long as it does not significantly impair the effects of the present invention. , a higher value is preferable from the viewpoint that defects are less likely to occur in the hole injection layer. Specifically, it is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and particularly preferably 0.5% by mass or more. It is preferably 60% by mass or less, and particularly preferably 50% by mass or less.

Examples of the solvent include ether solvents, ester solvents, aromatic hydrocarbon solvents, amide solvents and the like.

Examples of ether-based solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA), 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, and 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, and methylnaphthalene. be done.

Examples of amide solvents include N,N-dimethylformamide and N,N-dimethylacetamide.

In addition to these, dimethyl sulfoxide and the like can also be used.

Formation of the hole injection layer 3 by a wet film-forming method is usually carried out by preparing a composition for forming a hole injection layer and then applying it on a layer corresponding to the lower layer of the hole injection layer 3 (usually the anode 2). It is carried out by coating and forming a film on the surface and drying it.
After forming the hole injection layer 3, the coating film is usually dried by heating, drying under reduced pressure, or the like.

(Formation of hole injection layer by vacuum evaporation method)
When the hole injection layer 3 is formed by a vacuum deposition method, one or more of the constituent materials of the hole injection layer 3 are usually placed in a crucible placed in a vacuum vessel (two or more materials are placed in separate crucibles), and the inside of the vacuum chamber is evacuated to about 10 ⁻⁴ Pa by a vacuum pump. After that, the crucible is heated (usually each crucible is heated when two or more materials are used) to evaporate while controlling the amount of evaporation of the material in the crucible (when two or more materials are used, (usually independently controlling the amount of evaporation) to form a hole-injecting layer on the anode on the substrate placed facing the crucible. When two or more materials are used, a mixture thereof can be placed in a crucible, heated and evaporated to form the hole injection layer.

The degree of vacuum during vapor deposition is not limited as long as it does not ^{significantly impair} the ^effects of the present invention. 12.0×10 ⁻⁴ Pa) or less. The vapor 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/second or more and 5.0 Å/second or less. The film formation temperature during vapor deposition is not particularly limited as long as the effects of the present invention are not significantly impaired, but is preferably 10° C. or higher and 50° C. or lower.

Note that the hole injection layer 3 may be crosslinked.

<Hole transport layer>
The hole transport layer 4 is a layer that functions to transport holes from the anode 2 side to the light emitting layer 5 side. In the quantum dot light-emitting device of the present invention, the hole transport layer 4 is preferably formed from the viewpoint of enhancing the function of transporting holes from the anode 2 to the light-emitting layer 5 . When forming the hole transport layer 4 , the hole transport layer 4 is usually formed between the anode 2 and the light emitting layer 5 . Further, when the hole injection layer 3 described above is present, it is formed between the hole injection layer 3 and the light emitting layer 5 .

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

A method for forming the hole transport layer 4 may be a vacuum deposition method or a wet film formation method. From the viewpoint of excellent film-forming properties, it is preferable to form the film by a wet film-forming method.

A general method for forming a hole transport layer will be described below. It is preferably formed by a wet film formation method.

The hole transport layer 4 usually contains a hole transport compound. The hole-transporting compound contained in the hole-transporting layer 4 is preferably the second polymer contained in the second organic layer.

In the hole-transporting layer 4, in addition to the second polymer, the hole-transporting compound, represented by 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl, Aromatic diamine containing two or more tertiary amines and having two or more condensed aromatic rings substituted on the nitrogen atom (JP-A-5-234681), 4,4′,4″-tris(1-naphthylphenyl Aromatic amine compounds having a starburst structure such as amino)triphenylamine (J. Lumin., Vol. 72-74, pp. 985, 1997), aromatic amine compounds composed of a tetramer of triphenylamine (Chem. Commun., 2175, 1996), spiro compounds such as 2,2′,7,7′-tetrakis-(diphenylamino)-9,9′-spirobifluorene (Synth. Metals, 91, 209, 1997), 4,4'-N,N'-dicarbazole biphenyl, etc. Also, for example, polyvinylcarbazole, polyvinyltriphenylamine (JP-A-7-53953), tetra Polyarylene ether sulfone containing phenylbenzidine (Polym. Adv. Tech., Vol. 7, p. 33, 1996) and the like may also be included.

(Formation of hole transport layer by wet film formation method)
When the hole transport layer is formed by a wet film formation method, holes are usually added instead of the composition for forming a hole injection layer in the same manner as in the case of forming the hole injection layer by the wet film formation method. It is formed using a composition for forming a transport layer.

When forming a hole transport layer by a wet film-forming method, the composition for forming a hole transport layer usually further contains a solvent. As the solvent used in the composition for forming a hole transport layer, the same solvent as the solvent used in the composition for forming a hole injection layer can be used.

The concentration of the hole-transporting compound in the hole-transporting layer-forming composition can be in the same range as the concentration of the hole-transporting compound in the hole-injection layer-forming composition.

The formation of the hole transport layer by the wet film formation method can be performed in the same manner as the hole injection layer formation method described above.

(Formation of hole transport layer by vacuum deposition method)
When the hole-transporting layer is formed by a vacuum vapor deposition method, a hole-transporting layer is generally used instead of the composition for forming a hole-injecting layer in the same manner as in the case of forming the hole-injecting layer by a vacuum vapor deposition method. It can be formed using a layer-forming composition. Film formation conditions such as degree of vacuum, vapor deposition rate and temperature during vapor deposition can be the same as those for the vacuum vapor deposition of the hole injection layer.

<Light emitting layer>
The light-emitting layer 5 is a layer that functions to emit light by being excited by recombination of holes injected from the anode 2 and electrons injected from the cathode 7 when an electric field is applied between a pair of electrodes. .
The light-emitting layer 5 is a layer formed between the anode 2 and the cathode 7, and the light-emitting layer is formed between the hole-injection layer and the cathode, if there is a hole-injection layer on the anode, and the anode If there is a hole-transport layer on top, it is formed between the hole-transport layer and the cathode.
The quantum dot light-emitting device in the present invention preferably has the light-emitting layer in the first embodiment or the light-emitting layer in the second embodiment as the light-emitting layer.

The film thickness of the light-emitting layer 5 is arbitrary as long as it does not significantly impair the effects of the present invention. However, a thicker film is preferable because defects are less likely to occur in the film. . For this reason, the thickness of the light-emitting layer 5 is preferably 2 nm or more, more preferably 5 nm or more, and is usually 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 one or more host materials. The host material is usually a charge-transporting material, but a material with low charge-transporting properties may be added to adjust the charge-transporting properties.

(Formation of light-emitting layer by wet film-forming method)
A method for forming the light-emitting layer may be either a vacuum deposition method or a wet film formation method, but the wet film formation method is preferred because of its excellent film formability, and the spin coating method and the ink jet method are more preferred. In particular, when the composition for forming a light-emitting layer of the present invention is used to form a hole-injection layer or a hole-transport layer, which is the lower layer of the light-emitting layer, lamination by a wet film-forming method is easy. It is preferable to adopt the law. When the light-emitting layer is formed by a wet film-forming method, a light-emitting layer and A light-emitting layer-forming composition prepared by mixing these materials with a soluble solvent (light-emitting layer solvent) is used.

Examples of the solvent include ether-based solvents, ester-based solvents, aromatic hydrocarbon-based solvents, amide-based solvents, alkane-based solvents, halogenated aromatic hydrocarbon-based solvents, aliphatic group alcohol solvents, alicyclic alcohol solvents, aliphatic ketone solvents, alicyclic ketone solvents and the like. Specific examples of the solvent are listed below, but are not limited to these as long as the effects of the present invention are not impaired.

For example, aliphatic ether solvents such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2 -Aromatic ether solvents such as methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, diphenyl ether; phenyl acetate, phenyl propionate, methyl benzoate, benzoic acid Aromatic ester solvents such as ethyl, propyl benzoate, n-butyl benzoate; toluene, xylene, mesitylene, cyclohexylbenzene, tetralin, 3-isopropylbiphenyl, 1,2,3,4-tetramethylbenzene, 1,4 - aromatic hydrocarbon solvents such as diisopropylbenzene, cyclohexylbenzene and methylnaphthalene; amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide; n-decane, cyclohexane, ethylcyclohexane, decalin, 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; , dibutyl ketone and other aliphatic ketone solvents; cyclohexanone, cyclooctanone, fencon and other alicyclic ketone solvents; Among these, alkane solvents and aromatic hydrocarbon solvents are particularly preferred.

<Hole blocking layer>
A hole-blocking layer may be provided between the light-emitting layer 5 and the electron-transporting layer 6, which will be described later. The hole-blocking layer 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 7 side.

This hole-blocking layer has the role of blocking holes moving from the anode 2 from reaching the cathode 7 and the role of efficiently transporting electrons injected from the cathode 7 toward the light-emitting layer 5. have. The physical properties required for the material constituting the hole blocking layer include high electron mobility and low hole mobility, a large energy gap (difference between HOMO and LUMO), and an excited triplet level (T ₁ ). is high.

Examples of materials for the hole blocking layer that satisfy these conditions include bis(2-methyl-8-quinolinolato)(phenolato)aluminum, bis(2-methyl-8-quinolinolato)(triphenylsilanolate)aluminum, and the like. mixed ligand complexes, bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolato) aluminum binuclear metal complexes such as metal complexes, distyrylbiphenyl derivatives and the like Styryl compounds (JP-A-11-242996), triazole derivatives such as 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (JP-A-11-242996) 7-41759), phenanthroline derivatives such as bathocuproine (JP-A-10-79297), and the like. Furthermore, the compound having at least one pyridine ring substituted at the 2,4,6 positions described in WO 2005/022962 is also preferable as a material for the hole blocking layer.

There are no restrictions on the method of forming the hole blocking layer. 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 is arbitrary as long as it does not significantly impair the effects of the present invention, but it 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 6 is provided between the light emitting layer 5 and the cathode 7 for the purpose of further improving the current efficiency of the device.

The electron transport layer 6 is formed of a compound capable of efficiently transporting electrons injected from the cathode 7 toward the light-emitting layer 5 between electrodes to which an electric field is applied. The electron-transporting compound used in the electron-transporting layer 6 is a compound that has high electron injection efficiency from the cathode 7, high electron mobility, and can efficiently transport the injected electrons. is required.

Specific examples of the electron-transporting compound used in the electron-transporting layer include metal complexes such as an aluminum complex of 8-hydroxyquinoline (JP-A-59-194393), and 10-hydroxybenzo[h]quinoline. metal complexes, oxadiazole derivatives, distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948 specification), quinoxaline compound (JP-A-6-207169), phenanthroline derivative (JP-A-5-331459), 2-tert-butyl-9,10-N,N'-dicyanoanthraquinonediimine, n-type Examples include hydrogenated amorphous silicon carbide, n-type zinc sulfide, n-type zinc selenide, and the like.

The film thickness of the electron transport layer 6 is usually 1 nm or more, preferably 5 nm or more, and is usually 300 nm or less, preferably 100 nm or less.

The electron-transporting layer 6 is formed by laminating the light-emitting layer or the hole-blocking layer by a wet film-forming method or a vacuum vapor deposition method in the same manner as described above. A vacuum deposition method is usually used.

<Electron injection layer>
An electron injection layer may be provided between the electron transport layer 6 and the cathode 7 in order to efficiently inject electrons injected from the cathode 7 into the electron transport layer 6 or the light emitting layer 5 .

In order to efficiently inject electrons, the material forming the electron injection layer is preferably a metal with a low work function. Examples thereof include alkali metals such as sodium and cesium, alkaline earth metals such as barium and calcium, and the like. The film thickness is preferably 0.1 nm or more and 5 nm or less.

Furthermore, 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 is doped with an alkali metal such as sodium, potassium, cesium, lithium or rubidium ( JP-A-10-270171, JP-A-2002-100478, JP-A-2002-100482, etc.) also improves the electron injection and transport properties and makes it possible to achieve both excellent film quality. preferable.

The film thickness of the electron injection layer 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 is formed by laminating the light emitting layer 5 or the hole blocking layer or the electron transport layer 6 thereon by a wet film forming 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.

In some cases, the hole-blocking layer, the electron-transporting layer, and the electron-injecting layer are formed into a single layer by the operation of co-doping the electron-transporting material and the lithium complex.

<Cathode>
The cathode 7 plays a role of injecting electrons into a layer (an electron injection layer, a light-emitting layer, or the like) on the light-emitting layer 5 side.

As the material of the cathode 7, it is possible to use the material used for the anode 2, but in terms of efficient electron injection, it is preferable to use a metal with a low work function, such as tin or magnesium. , indium, calcium, aluminum, and silver, or alloys thereof. Specific examples include low work function alloy electrodes such as magnesium-silver alloys, magnesium-indium alloys, and aluminum-lithium alloys.

From the viewpoint of the stability of the quantum dot light-emitting device, it is preferable to protect the cathode made of a metal with a low work function by stacking a metal layer that has a high work function and is stable against the atmosphere on the cathode. Metals to be laminated include, for example, metals such as aluminum, silver, copper, nickel, chromium, gold, and platinum.

The film thickness of the cathode is generally similar to that of the anode.

<Other layers>
The quantum dot light-emitting device of the present invention may further have other layers as long as they do not significantly impair the effects of the present invention. That is, it may have any of the other layers described above between the anode and cathode.

<Other device configurations>
The quantum dot light-emitting device of the present invention has a structure opposite to that described above. It is also possible to laminate the injection layer and the anode in this order.

When applying the quantum dot light-emitting device of the present invention to an organic electroluminescent device, even if it is used as a single quantum dot light-emitting device, even if it is used in a configuration in which a plurality of quantum dot light-emitting devices are arranged in an array, A configuration in which anodes and cathodes are arranged in an XY matrix may be used.

[Quantum dot display device]
The quantum dot display device (quantum dot light emitting device display device) of the present invention comprises the quantum dot light emitting device of the present invention. The type and structure of the quantum dot display device of the present invention are not particularly limited, and the quantum dot light emitting device of the present invention can be assembled according to a conventional method.

For example, referring to the method described in "Organic EL Display" (Ohmsha, August 20, 2004, by Shizuo Tokito, Chihaya Adachi, and Hideyuki Murata), the organic light-emitting layer is formed by quantum dots. The quantum dot display device of the present invention can be formed by replacing with a light-emitting layer containing

[Quantum dot lighting]
The quantum dot illumination (quantum dot light emitting device illumination) of the present invention comprises the quantum dot light emitting device of the present invention. The type and structure of the quantum dot illumination of the present invention are not particularly limited, and the quantum dot light emitting device of the present invention can be assembled according to a conventional method.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples. However, the present invention is not limited to the following examples, and the present invention can be arbitrarily modified without departing from the scope of the invention.

[Example 1]
A quantum dot light-emitting device was produced by the following method.
An indium tin oxide (ITO) transparent conductive film deposited on a glass substrate to a thickness of 50 nm (manufactured by Geomatec, a sputter-deposited product) was subjected to a 2 mm-wide stripe using ordinary photolithography and etching with hydrochloric acid. was patterned to form an anode. The substrate on which the ITO pattern is formed in this manner is washed with ultrasonic waves using an aqueous solution of surfactant, washed with ultrapure water, ultrasonically washed with ultrapure water, and washed with ultrapure water in this order, and then dried with compressed air. , and finally performed ultraviolet ozone cleaning.

As a composition for forming a hole injection layer, 3.0% by mass of a hole-transporting polymer compound having a repeating structure of the following formula (P-1) and 0.6% by mass of an electron-accepting compound (HI-1) was dissolved in ethyl benzoate to prepare a composition.

This composition for forming a hole injection layer was spin-coated on the 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, forming a hole injection layer. and

Next, a charge-transporting polymer compound having the following structural formula (HT-1) is dissolved in 1,3,5-trimethylbenzene at a concentration of 2.0% by mass to form a hole-transporting layer-forming composition. was prepared.

This composition for forming a hole transport layer is spin-coated in a nitrogen glove box onto the substrate on which the hole injection layer has been applied and formed, and dried on a hot plate in a nitrogen glove box at 230° C. for 30 minutes to form a film. A uniform thin film with a thickness of 40 nm was formed as a hole transport layer.

Subsequently, a toluene solution containing 1.35% by mass of CdZnSeS nanoparticles and 0.15% by mass of a compound having a structure represented by the following formula (H-1) was prepared as a composition for forming a light-emitting layer. is spin-coated on the substrate on which the film up to the hole transport layer is coated for 30 seconds at 3000 rpm in a nitrogen glove box, and dried on a hot plate in a nitrogen glove box at 100 ° C. for 10 minutes to form a light-emitting layer. and

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

Next, structural formula (ET-1) shown below and 8-hydroxyquinolinolatritium were co-deposited on the light-emitting layer at a film thickness ratio of 2:3 by a vacuum vapor deposition method to form an electron-transporting layer having a film thickness of 45 nm. formed.

Subsequently, a striped shadow mask with a width of 2 mm was adhered to the substrate so as to be orthogonal to the ITO stripes of the anode as a mask for cathode evaporation, and aluminum was heated with a molybdenum boat to form an aluminum layer with a thickness of 80 nm. formed to form the cathode.
As described above, a quantum dot light-emitting device having a light-emitting area portion with a size of 2 mm×2 mm was obtained.

[Comparative Example 1]
The procedure of Example 1 was repeated, except that the light-emitting layer was formed using a toluene solution having a composition containing 1.5% by mass of CdZnSeS nanoparticles and not containing the compound having the structure represented by the formula (H-1). A quantum dot light-emitting device was fabricated by

[Evaluation of element]
When the quantum dot light-emitting devices obtained in Example 1 and Comparative Example 1 were caused to emit light, red light emission with a peak wavelength of 628 nm and a half width of 27 nm was obtained. The luminance half-life (LT50) was measured when the device was continuously energized at a current density of 10 mA/cm ² .
Table 1 shows the relative luminance half life of the quantum dot light emitting device of Example 1 when the luminance half life (LT50) of the quantum dot light emitting device of Comparative Example 1 is set to 1.
In Table 1, the CdZnSeS nanoparticles are described as "QD", and the compound having the structure represented by formula (H-1) is described as "H-1".

From the results in Table 1, it was found that the performance of the quantum dot light-emitting device of the present invention was improved.

The present invention is applicable to various fields in which quantum dot light-emitting devices are used, such as flat panel displays (for example, OA computers and wall-mounted TVs), and light sources that take advantage of the characteristics of surface light emitters (for example, light sources for copiers). , backlight sources for liquid crystal displays and instruments), display boards, indicator lamps, and the like.

REFERENCE SIGNS LIST 1 substrate 2 anode 3 hole injection layer 4 hole transport layer 5 light emitting layer 6 electron transport layer 7 cathode 8 quantum dot light emitting device

Claims (9)

A composition for forming a light emitting layer of a quantum dot light emitting device, comprising quantum dots, a compound represented by the following formula (1), and an organic solvent.

(In formula (1),
Ar ²¹ and Ar ²² are each independently an optionally substituted C 6-30 aromatic hydrocarbon group, an optionally substituted C 3-30 aromatic heterocyclic ring or a structure selected from an optionally substituted C 6-30 aromatic hydrocarbon group and an optionally substituted C 3-30 aromatic heterocyclic group represents a monovalent group in which 2 to 7 are linked,
Each of R ²¹ to R ²⁴ is independently an optionally substituted alkyl group, an optionally substituted C 6 to 30 aromatic hydrocarbon group, and a substituted group. an aromatic heterocyclic group having 3 to 30 carbon atoms which may be substituted, or an aromatic hydrocarbon group having 6 to 30 carbon atoms which may have substituents and 3 to 3 carbon atoms which may have substituents represents a monovalent group in which 2 to 7 structures selected from 30 aromatic heterocyclic groups are linked,
e and g are each independently an integer of 0 to 4,
f and h are each independently an integer of 0 to 3; ) A composition for forming a light emitting layer of a quantum dot light emitting device, comprising quantum dots, a compound represented by the following formula (1A), and an organic solvent.

(In formula (1A), Ar ²¹ , Ar ²² , R ²¹ to R ²⁴ , e, f, g, and h are Ar ²¹ , Ar ²² , R ²¹ to R ²⁴ , e, f, Synonymous with g and h.) A method for producing a quantum dot light-emitting device, comprising the steps of applying and drying the composition for forming a light-emitting layer of a quantum dot light-emitting device according to claim 1 or 2 to form a light-emitting layer. A method for manufacturing a quantum dot display device, comprising the method for manufacturing the quantum dot light emitting device according to claim 3. A method for manufacturing a quantum dot illumination, comprising the method for manufacturing a quantum dot light emitting device according to claim 3. having an anode, a cathode, and a light-emitting layer provided between the anode and the cathode;
A quantum dot light-emitting device, wherein the light-emitting layer contains quantum dots and a compound represented by the following formula (1).

(In formula (1),
Ar ²¹ and Ar ²² are each independently an optionally substituted C 6-30 aromatic hydrocarbon group, an optionally substituted C 3-30 aromatic heterocyclic ring or a structure selected from an optionally substituted C 6-30 aromatic hydrocarbon group and an optionally substituted C 3-30 aromatic heterocyclic group represents a monovalent group in which 2 to 7 are linked,
Each of R ²¹ to R ²⁴ is independently an optionally substituted alkyl group, an optionally substituted C 6 to 30 aromatic hydrocarbon group, and a substituted group. an aromatic heterocyclic group having 3 to 30 carbon atoms which may be substituted, or an aromatic hydrocarbon group having 6 to 30 carbon atoms which may have substituents and 3 to 3 carbon atoms which may have substituents represents a monovalent group in which 2 to 7 structures selected from 30 aromatic heterocyclic groups are linked,
e and g are each independently an integer of 0 to 4,
f and h are each independently an integer of 0 to 3; ) having an anode, a cathode, and a light-emitting layer provided between the anode and the cathode;
A quantum dot light-emitting device, wherein the light-emitting layer contains a quantum dot and a compound represented by the following formula (1A).

(In formula (1A), Ar ²¹ , Ar ²² , R ²¹ to R ²⁴ , e, f, g, and h are Ar ²¹ , Ar ²² , R ²¹ to R ²⁴ , e, f, Synonymous with g and h.) A quantum dot display device comprising the quantum dot light emitting device according to claim 6 or 7. A quantum dot illumination comprising the quantum dot light emitting device according to claim 6 or 7.

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