Composition for forming a light-emitting layer of a quantum dot light-emitting device, quantum dot light-emitting device, quantum dot display device, and quantum dot lighting

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: The composition for forming the light-emitting layer of a quantum dot light-emitting element includes quantum dots, a compound represented by the following formula (1), and an organic solvent. The quantum dot light emitting element has an anode 2, a cathode 7, and a light emitting layer 5, and the light emitting layer includes quantum dots and a compound represented by the following formula (1).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a composition for forming a light-emitting layer of a quantum dot light-emitting device, and to a quantum dot light-emitting device, a quantum dot display device, and a quantum dot lighting device using the composition. [Background technology]

[0002] As a thin-film electroluminescent device, organic electroluminescent devices using organic thin films are being developed. Organic electroluminescent devices (OLEDs) usually have 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 each of these layers are being developed, and development is also underway for red, green, and blue light-emitting colors.

[0003] In recent years, attempts have been made to cover a wider color gamut by using "quantum dots," an inorganic light-emitting material, in the light-emitting layer to give red, green, and blue light sources a sharp emission spectrum. Electroluminescent devices using quantum dots are also called quantum dot light-emitting devices (QD-LEDs, QLEDs).

[0004] Furthermore, quantum dot light-emitting devices are usually formed by a wet film-forming method (coating method). The wet film-forming method has advantages such as the ease of achieving large-area applications, and research and development of quantum dot light-emitting devices formed by coating methods has been progressing. For example, Patent Documents 1 to 3 and Non-Patent Document 1 discuss quantum dot light-emitting devices, but there has been a demand for lower voltage devices, improved luminous efficiency, and improved operating life. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2020-107867 [Patent Document 2] Japanese Patent Publication No. 2020-161476 [Patent Document 3] Japanese Patent Publication No. 2020-173937 [Non-patent literature]

[0006] [Non-Patent Document 1] Nature, 2014, vol. 515, pp. 96-99 Summary of the Invention [Problem to be solved by the invention]

[0007] 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, operates at a low voltage, has high luminous efficiency, and has a long operating life. [Means for solving the problem]

[0008] The gist of the present invention is as follows [1] to

[11] .

[0009] [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:

[0010] [ka]

[0011] (In formula (1), Ar 21 ~Ar 35 each independently represents a hydrogen atom, a benzene ring structure which may have a substituent, or a structure in which 2 to 10 benzene ring structures which may have a substituent are linked in an unbranched or branched manner.

[0012] [2] In the formula (1), Ar 22 , Ar 23 , Ar 24 , Ar 27 , Ar 28 , Ar 29 , Ar 32 , Ar 33 and Ar 34The composition for forming a light-emitting layer of a quantum dot light-emitting device according to [1], wherein at least one of the above is a structure represented by the following formula (1-1) or the following formula (1-2):

[0013] [ka]

[0014] (In formula (1-1) and formula (1-2), Ar 36 ~Ar 39 each independently represents a hydrogen atom, a benzene ring structure which may have a substituent, or a structure in which 2 to 8 benzene ring structures which may have a substituent are linked in an unbranched or branched manner.

[0015] [3] In the formula (1), Ar 22 , Ar 23 and Ar 24 One of the following and Ar 27 , Ar 28 and Ar 29 One of the following and Ar 32 , Ar 33 and Ar 34 The composition for forming a light-emitting layer of a quantum dot light-emitting device according to [2], wherein any one of the above is a structure represented by the formula (1-1) or the formula (1-2).

[0016] [4] A method for producing a quantum dot light-emitting element, comprising the step of applying and drying the composition for forming a light-emitting layer of a quantum dot light-emitting element according to any one of [1] to [3] to form a light-emitting layer.

[0017] [5] A method for manufacturing a quantum dot display device, including the method for manufacturing the quantum dot light-emitting element according to [4].

[0018] [6] A method for manufacturing quantum dot lighting, including the method for manufacturing the quantum dot light-emitting element of [4].

[0019] [7] A quantum dot light-emitting device having an anode, a cathode, and a light-emitting layer provided between the anode and the cathode, the light-emitting layer containing quantum dots and a compound represented by the following formula (1):

[0020] [ka]

[0021] (In formula (1), Ar 21 ~Ar 35 each independently represents a hydrogen atom, a benzene ring structure which may have a substituent, or a structure in which 2 to 10 benzene ring structures which may have a substituent are linked in an unbranched or branched manner.

[0022] [8] In the formula (1), Ar 22 , Ar 23 , Ar 24 , Ar 27 , Ar 28 , Ar 29 , Ar 32 , Ar 33 and Ar 34 The quantum dot light-emitting device according to [7], wherein at least one of the above has a structure represented by the following formula (1-1) or the following formula (1-2):

[0023] [ka]

[0024] (In formula (1-1) and formula (1-2), Ar 36 ~Ar 39 each independently represents a hydrogen atom, a benzene ring structure which may have a substituent, or a structure in which 2 to 8 benzene ring structures which may have a substituent are linked in an unbranched or branched manner.

[0025] [9] In the formula (1), Ar 22 , Ar 23 and Ar 24 One of the following and Ar 27 , Ar 28 and Ar 29 One of the following and Ar 32 , Ar 33 and Ar 34The quantum dot light-emitting device according to [8], wherein any one of the above has a structure represented by the formula (1-1) or the formula (1-2).

[0026]

[10] A quantum dot display device comprising the quantum dot light-emitting element according to any one of [7] to [9].

[0027]

[11] A quantum dot lighting device comprising the quantum dot light-emitting device according to any one of [7] to [9]. [Effects of the Invention]

[0028] 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, operates at a low voltage, has high luminous efficiency, and has a long operating life. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of the structure of a quantum dot light-emitting device according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] The following describes in detail embodiments of the composition for forming a light-emitting layer of a quantum dot light-emitting element of the present invention, the quantum dot light-emitting element, a quantum dot display device including the quantum dot light-emitting element, and a quantum dot lighting device including the quantum dot light-emitting element. The following description is one example (typical example) of the embodiment of the present invention, and the present invention is not limited to these contents as long as it does not deviate from the gist of the invention.

[0031] [Composition for forming a light-emitting layer of a 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") contains quantum dots, a compound represented by the following formula (1), and an organic solvent.

[0032] [ka]

[0033] (In formula (1), Ar 21 ~Ar 35 each independently represents a hydrogen atom, a benzene ring structure which may have a substituent, or a structure in which 2 to 10 benzene ring structures which may have a substituent are linked in an unbranched or branched manner.

[0034] The compound represented by formula (1) contained in the composition for forming a light-emitting layer of the present invention may be one type or two or more types.

[0035] In the light-emitting layer formed using the composition for forming a light-emitting layer 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.

[0036] [Reasons why the present invention is effective] The composition for forming an emission layer of the present invention and the compound represented by formula (1) contained in the emission layer of a quantum dot light-emitting device formed from the composition for forming an emission layer have appropriate charge transport properties, and can effectively generate an excited state of quantum dots having a deep HOMO. The compound represented by formula (1) has broadened HOMO and LUMO due to the benzene rings connected, and has moderate hole and electron transport properties. Because it has a 1,3,5-triphenylbenzene structure that does not contain a central heteroatom, the energy gap between HOMO and LUMO is large, and it is thought to be suitable for effectively generating excited states of quantum dots with deep HOMO.

[0037] [Quantum dots] The composition for forming a light-emitting layer of the present invention contains quantum dots, which are light-emitting semiconductor nanoparticles and typically have a diameter in the range of 1 to 20 nm.

[0038] The quantum dots are preferably made of a II-VI compound, a III-V compound, a IV-VI compound, a group IV element, a group IV compound, or a combination thereof.

[0039] Examples of II-VI 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, and HgZnSTe.

[0040] Group 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, and InAlPSb.

[0041] Examples of Group IV-VI compounds include SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe.

[0042] Examples of Group IV elements and Group IV compounds include Si, Ge, SiC, and SiGe. do.

[0043] Quantum dots may have a homogeneous single structure or a core / shell double structure. They may also have a triple or quadruple structure, such as core / shell / shell. The materials constituting the core and shell are different compounds. In this case, it is preferable that the energy band gap of the shell compound is larger than that of the core compound. Specific examples of structures that are preferable include ZnTeSe / ZnSe / ZnS, CdSe / ZnS, and InP / ZnS. The quantum dots may be of one type or of two or more types.

[0044] [Compound represented by formula (1)] The composition for forming the light-emitting layer of the quantum dot light-emitting device of the present invention contains a compound represented by the following formula (1).

[0045] [ka]

[0046] (In formula (1), Ar 21 ~Ar 35 each independently represents a hydrogen atom, a benzene ring structure which may have a substituent, or a structure in which 2 to 10 benzene ring structures which may have a substituent are linked in an unbranched or branched manner.

[0047] In formula (1), Ar 21 ~Ar 35 In the case where the benzene ring structure is an optionally substituted benzene ring structure or a structure in which 2 to 10 optionally substituted benzene ring structures are linked in an unbranched or branched manner, the substituent that the benzene ring may have is preferably an alkyl group.

[0048] <Alkyl group as a substituent> The alkyl group as a substituent is a linear, branched, or cyclic alkyl group having usually 1 or more and 12 or less carbon atoms, preferably 8 or less, further preferably 6 or less, and even more preferably 4 or less carbon atoms, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a tert-butyl group, an n-hexyl group, a cyclohexyl group, and a 2-ethylhexyl group.

[0049] <Equation (1-1), Equation (1-2)> In the formula (1), Ar 22 , Ar 23 , Ar 24 , Ar 27 , Ar 28 , Ar 29 , Ar 32 , Ar 33 and Ar 34 At least one of the above preferably has a structure represented by the following formula (1-1) or (1-2) in terms of excellent solubility in a solvent, resistance to crystallization, and ease of obtaining a uniform film. 22 , Ar 23 , Ar 24 , Ar 27 , Ar 28 , Ar 29 , Ar 32 , Ar 33 and Ar 34 A compound in which at least one of the above has a structure represented by the following formula (1-1) or (1-2) may be referred to as "compound (1-1) or (1-2)".

[0050] [ka]

[0051] (In formulas (1-1) and (1-2), Ar 36 ~Ar 39 each independently represents a hydrogen atom, a benzene ring structure which may have a substituent, or a structure in which 2 to 8 benzene ring structures which may have a substituent are linked in an unbranched or branched manner.

[0052] In formula (1-1) and formula (1-2), Ar 36 ~Ar 39 In the case where the benzene ring has a structure in which 2 to 10 benzene ring structures which may have a substituent or 2 to 10 benzene ring structures which may have a substituent are linked in an unbranched or branched manner, the substituent which the benzene ring may have is preferably an alkyl group as the substituent.

[0053] In the formula (1), Ar 22 , Ar 23 and Ar 24 One of the following and Ar 27 , Ar 28 and Ar 29 and Ar 32 , Ar 33 and Ar 34 Preferably, any one of Ar is a structure represented by the formula (1-1) or the formula (1-2), 22 , Ar 27 and Ar 32 is more preferably a structure represented by the formula (1-1) or the formula (1-2).

[0054] Furthermore, it is preferable that the structure represented by the formula (1-1) is a structure represented by the following formula (1-1A), (1-1B), (1-1C), (1-1D) or (1-1E), and the structure represented by the formula (1-2) is a structure represented by the following formula (1-2A), (1-2B), (1-2C) or (1-2D). These structures may be substituted with an alkyl group as the substituent. From the viewpoint of improving solubility, substitution with an alkyl group is preferred. From the viewpoint of charge transport properties and durability during device operation, it is preferred that the structure has no substituent.

[0055] [ka]

[0056] Among these, the structure represented by the formula (1-1) is preferably a structure represented by the formula (1-1A), (1-1C), (1-1D), or (1-1E), and the structure represented by the formula (1-2) is more preferably a structure represented by the formula (1-2A). It is particularly preferable that at least one of the structures represented by the formula (1-1) or the formula (1-2) includes a structure represented by the formula (1-1A) or a structure represented by the formula (1-2A).

[0057] It is believed that the inclusion of such a structure in the compound represented by formula (1) allows the charge transport property in the light-emitting layer to be appropriately adjusted, thereby increasing the light-emitting efficiency, and also that the inclusion of such a structure results in excellent solubility and durability during device operation.

[0058] <Molecular weight> The compound represented by formula (1) is a low molecular weight material, and the molecular weight is preferably 5,000 or less, more preferably 3,000 or less, particularly preferably 2,000 or less, and most preferably 1,500 or less. The lower limit of the molecular weight is usually 300 or more, preferably 400 or more, and more preferably 600 or more.

[0059] <Specific examples of compounds represented by formula (1)> The compound represented by formula (1) is not particularly limited, but examples thereof include the following compounds.

[0060] [ka]

[0061] [ka]

[0062] The composition for forming a light-emitting layer of the present invention may contain only one type of compound represented by the formula (1), or may contain two or more types.

[0063] [Organic solvents] The organic solvent contained in the composition for forming an emitting layer of the present invention is a volatile liquid component used for forming a layer containing quantum dots and the compound represented by formula (1), preferably compounds (1-1) and (1-2), by wet film formation.

[0064] The organic solvent is not particularly limited as long as it is an organic solvent in which the compound represented by formula (1), preferably the compounds (1-1) and (1-2), and other charge-transporting materials described later, which are solutes, can be well dissolved.

[0065] 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, dichlorobenzene, and trichlorobenzene; and aromatic hydrocarbons such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, and diphenyl ether. aromatic ethers; 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; and aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA).

[0066] Among these, from the viewpoint of viscosity and boiling point, alkanes, aromatic hydrocarbons, and aromatic esters are preferred, and aromatic hydrocarbons and aromatic esters are particularly preferred.

[0067] These organic solvents may be used singly or in any combination of two or more in any ratio.

[0068] 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, evaporation of the solvent from the composition for forming an emitting layer during wet film formation may reduce film formation stability. If the boiling point of the organic solvent is above this range, residual solvent may remain after wet film formation, reducing film formation stability.

[0069] In particular, it is considered that a more uniform coating film can be easily formed by combining two or more organic solvents having a boiling point of 150° C. or higher, which is preferable.

[0070] [Other charge transport materials] The composition for forming a light-emitting layer of the present invention may further contain a charge transport material other than the compound represented by formula (1).

[0071] Other charge transport materials that can be used include those used as charge transport materials in organic electroluminescent devices, such as pyridine, carbazole, naphthalene, perylene, pyrene, anthracene, chrysene, naphthacene, phenanthrene, coronene, fluoranthene, benzophenanthrene, fluorene, acetonaphthofluoranthene, coumarin, p-bis(2-phenylethenyl)benzene and derivatives thereof, quinacridone derivatives, DCM (4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran) compounds, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, azabenzothioxanthene, fused aromatic ring compounds substituted with an arylamino group, and styryl derivatives substituted with an arylamino group.

[0072] These may be used alone or in any combination of two or more in any ratio.

[0073] Of these, naphthalene, perylene, pyrene, anthracene, chrysene, naphthacene, phenanthrene, coronene, fluoranthene, benzophenanthrene, fluorene, acetonaphthofluoranthene, and derivatives thereof are preferred, and anthracene derivatives are more preferred.

[0074] [Content] The content of quantum dots in the composition for forming a light-emitting layer of the present invention is usually 0.001% by mass or more, preferably 0.01% by mass or more, and usually 30.0% by mass or less, preferably 20.0% by mass or less. The content of the compound represented by formula (1), preferably compounds (1-1) and (1-2), contained in the composition for forming an emitting layer of the present invention is usually 0.01% by mass or more, preferably 0.1% by mass or more, and 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 formula (1), preferably the compounds (1-1) and (1-2), within this range, holes and electrons can be efficiently injected from an adjacent layer (e.g., a hole transport layer or a hole blocking layer) into the light-emitting layer, thereby reducing the driving voltage. The quantum dots, the compounds represented by the formula (1), preferably the compounds (1-1) and (1-2), may be contained in the composition for forming the light-emitting layer alone or in combination of two or more kinds.

[0075] When the composition for forming a light-emitting layer of the present invention contains another charge transport material, 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 20.0% by mass or less. By setting the content of the other charge transport material in the composition for forming a light-emitting layer within the above range, it is thought that the electron transportability in the light-emitting layer is improved, resulting in a lower voltage, and the balance between electrons and holes in the light-emitting layer is improved, thereby improving the luminous efficiency.

[0076] Furthermore, from the viewpoint of improving the luminous efficiency, the total content of the compound represented by formula (1), preferably the compound (1-1) or (1-2), and other charge transport materials contained in the composition for forming an emitting layer of the present invention is usually 10 parts by mass or less, preferably 1 part by mass or less, and more preferably 0.5 parts by mass or less, relative to 1 part by mass of the quantum dots, and is usually 0.001 parts by mass or more, preferably 0.005 parts by mass or more, and more preferably 0.01 parts by mass or more.

[0077] The content of the organic solvent contained in the composition for forming an emitting layer 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 99.9% by mass or less, particularly preferably 99.8% by mass or less. If the content of the organic solvent is equal to or more than the lower limit, the composition has an appropriate viscosity and improves coatability, while if it is equal to or less than the upper limit, a uniform film is easily obtained and film-formability is good.

[0078] [Other ingredients] The composition for forming a light-emitting layer of the present invention may further contain other compounds in addition to the quantum dots and the above-mentioned compounds, as necessary. Preferred examples of the other compounds include phenols such as dibutylhydroxytoluene and dibutylphenol, which are known as antioxidants.

[0079] [Film forming method] The 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 involves applying a composition to form a liquid film, drying the film to remove the organic solvent, and forming a film of the light-emitting layer. Examples of the application method include wet film-forming methods such as spin coating, dip coating, die coating, bar coating, blade coating, roll coating, spray coating, capillary coating, inkjet printing, nozzle printing, screen printing, gravure printing, and flexographic printing, and the applied film is then dried to form a film. Among these film-forming methods, spin coating, spray coating, inkjet printing, and nozzle printing are preferred. When manufacturing a quantum dot display device equipped with a quantum dot light-emitting element using the composition for forming a light-emitting layer of the present invention, the inkjet method or nozzle printing method is preferred, with the inkjet method being particularly preferred.

[0080] The drying method is not particularly limited, and natural drying, drying under reduced pressure, drying by heating, or drying under reduced pressure while heating can be appropriately used. Heat drying may be performed after natural drying or drying under reduced pressure in order to further remove residual organic solvents. The 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 on a hot plate, heating in an oven, infrared heating, etc. 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 usually 1 minute or more, preferably 2 minutes or more, and usually 60 minutes or less, preferably 30 minutes or less, more preferably 20 minutes or less.

[0081] [Quantum dot light-emitting element] A quantum dot light-emitting device according to one aspect of the present invention includes an anode, a cathode, and an emitting layer (the emitting layer in the first embodiment) formed between the anode and the cathode using the composition for forming an emitting layer of the present invention. Furthermore, a quantum dot light-emitting device according to another embodiment 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 contains quantum dots and a compound represented by formula (1).

[0082] The quantum dot light-emitting device of the present invention preferably further comprises 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. As described below, the second organic layer preferably comprises a polymer having a triarylamine structure as a repeating unit (hereinafter, the polymer contained in the second organic layer may be referred to as a "second polymer"), and even more preferably, the polymer does not comprise a crosslinking group. As the second polymer, a polymer containing a repeating unit represented by formula (5) is preferred, as shown below, and more preferably a polymer containing a repeating unit represented by formula (2), formula (3), or formula (4) is preferred.

[0083] The second organic layer is preferably formed by a wet film-forming method using the second composition described below. After application, the second composition is insolubilized by heating. Therefore, the second organic layer can be suitably used for stacking quantum dot light-emitting elements.

[0084] The second organic layer included in the quantum dot light-emitting device of the present invention will be described below. The structure of the quantum dot light-emitting device of the present invention will be described later.

[0085] [Second organic layer] The second organic layer preferably contains, as a hole transport material, a second polymer having a triarylamine structure as a repeating unit.

[0086] [Second polymer used in the second organic layer] The second polymer having a triarylamine structure having no crosslinking group as a repeating unit contained in the second organic layer preferably contains the triarylamine structure in the main chain of the polymer. The repeating unit of the triarylamine structure is represented by the following formula (5).

[0087] [ka]

[0088] (In formula (5), Ar 4 represents 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 group in which a plurality of groups selected from an aromatic hydrocarbon group which may have a substituent other than a bridging group and an aromatic heterocyclic group which may have a substituent other than a bridging group are linked together, Ar 5 represents a divalent aromatic hydrocarbon group which may have a substituent other than a bridging group, a divalent aromatic heterocyclic group which may have 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 the divalent aromatic hydrocarbon groups and the divalent aromatic heterocyclic groups are linked together directly or via a linking group. Ar 4 and Ar 5 may form a ring via a single bond or a linking group.

[0089] (Ar 4 ) In the repeating unit represented by the above formula (5), Ar 4 represents 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 group in which multiple groups selected from an aromatic hydrocarbon group which may have a substituent other than a bridging group and an aromatic heterocyclic group which may have a substituent other than a bridging group are linked together.

[0090] The aromatic hydrocarbon group preferably has 6 to 60 carbon atoms, and specific examples thereof include monovalent groups of 6-membered monocyclic rings or 2 to 5 condensed rings, such as a 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 ring, or groups in which multiple of these are linked together. Note that, for example, a "monovalent group of a benzene ring" means a "benzene ring having a single free valence," i.e., a phenyl group.

[0091] The aromatic heterocyclic group preferably has 3 or more and 60 or less carbon atoms, and specific examples thereof include a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, a carbazole ring, a pyrroloimidazole ring, a pyrrolopyrazole ring, a pyrrolopyrrole ring, a thienopyrrole ring, a thienothiophene ring, a furopyrrole ring, a furofuran ring, a thienofuran ring, a benzoyl ... Examples of the 5- or 6-membered ring include a monovalent group of a 5- or 6-membered monocyclic ring or a monovalent group of 2- to 4-fused rings, such as an isoxazole ring, a benzisothiazole ring, a benzimidazole ring, a pyridine ring, a pyrazine ring, a pyridazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a cinnoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, and an azulene ring, or a group in which a plurality of these rings are linked together.

[0092] Ar 4 is preferably an aromatic hydrocarbon group which may have a substituent other than a crosslinking group, from the viewpoints of excellent charge transport properties and excellent durability, and among these, a monovalent group of a benzene ring or a fluorene ring which may have a substituent other than a crosslinking group, i.e., a phenyl group or a fluorenyl group which may have a substituent other than a crosslinking group, is more preferred, a fluorenyl group which may have a substituent other than a crosslinking group is still more preferred, and a 2-fluorenyl group which may have a substituent other than a crosslinking group is particularly preferred.

[0093] Ar 4The substituents other than the crosslinking group that the aromatic hydrocarbon group and aromatic heterocyclic group may have are not particularly limited as long as they do not significantly impair the properties of the present polymer. Preferred examples of the substituents include groups selected from the following substituent group Z, with alkyl groups, alkoxy groups, aromatic hydrocarbon groups, and aromatic heterocyclic groups being more preferred, and alkyl groups being even more preferred.

[0094] Ar 4 In terms of solubility in a coating solvent, a fluorenyl group substituted with an alkyl group having 1 to 24 carbon atoms is preferred, and a 2-fluorenyl group substituted with an alkyl group having 4 to 12 carbon atoms is particularly preferred. 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 substituted with two alkyl groups is particularly preferred.

[0095] The fluorenyl group substituted with an alkyl group at at least one of the 9- and 9'-positions tends to improve the solubility in solvents and the durability of the fluorene ring. Furthermore, the fluorenyl group substituted with an alkyl group at both the 9- and 9'-positions tends to further improve the solubility in solvents and the durability of the fluorene ring.

[0096] Also, Ar 4 is also preferably a spirobifluorenyl group from the viewpoint of solubility in a coating solvent.

[0097] <Substituent group Z> The substituent group Z is a group consisting of alkyl groups, alkoxy groups, aryloxy groups, heteroaryloxy groups, alkoxycarbonyl groups, dialkylamino groups, diarylamino groups, arylalkylamino groups, acyl groups, halogen atoms, haloalkyl groups, alkylthio groups, arylthio groups, silyl groups, siloxy groups, cyano groups, aromatic hydrocarbon groups, and aromatic heterocyclic groups. These substituents may have any of a linear, branched, and cyclic structure.

[0098] More specifically, the substituent group Z includes the following structures. For example, a linear, branched, or cyclic alkyl group having usually 1 or more, preferably 4 or more, and usually 24 or less, preferably 12 or less, more preferably 8 or less, and even more preferably 6 or less, such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a tert-butyl group, an n-hexyl group, a cyclohexyl group, or a dodecyl group; For example, alkoxy groups having usually 1 or more and usually 24 or less, preferably 12 or less carbon atoms, such as a methoxy group or an ethoxy group; For example, an aryloxy group or heteroaryloxy group having usually 4 or more, preferably 5 or more, and usually 36 or less, preferably 24 or less, carbon atoms, such as a phenoxy group, naphthoxy group, or pyridyloxy group; For example, alkoxycarbonyl groups having usually 2 or more and usually 24 or less, preferably 12 or less carbon atoms, such as a methoxycarbonyl group or an ethoxycarbonyl group; For example, dialkylamino groups having usually 2 or more and usually 24 or less, preferably 12 or less carbon atoms, such as a dimethylamino group or a diethylamino group; For example, diarylamino groups such as diphenylamino groups and ditolylamino groups, each of which has usually 10 or more, preferably 12 or more, and usually 36 or less, preferably 24 or less carbon atoms; For example, an arylalkylamino group having typically 7 carbon atoms, typically 36 or less, and preferably 24 or less, such as a phenylmethylamino group; For example, acyl groups such as an acetyl group and a benzoyl group, each of which usually has 2 carbon atoms, usually 24 or less, and preferably 12 carbon atoms; For example, halogen atoms such as fluorine atoms and chlorine atoms; For example, haloalkyl groups having typically 1 or more carbon atoms and typically 12 or less, preferably 6 or less, such as a trifluoromethyl group; For example, alkylthio groups having usually 1 or more and usually 24 or less, preferably 12 or less carbon atoms, such as a methylthio group or an ethylthio group; For example, an arylthio group having usually 4 or more, preferably 5 or more, and usually 36 or less, preferably 24 or less, carbon atoms, such as a phenylthio group, a naphthylthio group, or a pyridylthio group; For example, a silyl group having usually 2 or more, preferably 3 or more, carbon atoms and usually 36 or less, preferably 24 or less, such as a trimethylsilyl group or a triphenylsilyl group; For example, a siloxy group having a carbon number of usually 2 or more, preferably 3 or more, and usually 36 or less, preferably 24 or less, such as a trimethylsiloxy group or a triphenylsiloxy group; cyano group; For example, aromatic hydrocarbon groups such as phenyl and naphthyl groups, each having a carbon number of usually 6 or more and usually 36 or less, and preferably 24 or less; For example, aromatic heterocyclic groups having usually 3 or more, preferably 4 or more, carbon atoms and usually 36 or less, preferably 24 or less, such as a thienyl group or a pyridyl group.

[0099] Among the above-mentioned substituent group Z, alkyl groups, alkoxy groups, diarylamino groups, aromatic hydrocarbon groups, and aromatic heterocyclic groups are preferred. From the viewpoint of charge transportability, the substituent is preferably an aromatic hydrocarbon group or an aromatic heterocyclic group, more preferably an aromatic hydrocarbon group, and even more preferably no substituent. From the viewpoint of improving solubility, the substituent is preferably an alkyl group or an alkoxy group.

[0100] Each of the substituents in the above-mentioned substituent group Z may further have a substituent. Examples of such a substituent include the same as those in the above-mentioned substituents (substituent group Z). Each of the substituents that may be contained in the above-mentioned substituent group Z 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, an alkoxy group having 6 or less carbon atoms, or a phenyl group, and from the viewpoint of charge transportability, it is more preferable that each of the substituents in the above-mentioned substituent group Z does not have any further substituent.

[0101] (Other preferred Ar 4 ) Ar in the repeating unit represented by the above formula (5) 4 It is also preferable that at least one of the groups is a group represented by the following formula (10): The reason for this is thought to be that in the two carbazole structures in the following formula (10), the LUMOs are distributed in the aromatic hydrocarbon group or aromatic heterocyclic group between the nitrogen atoms of each other, thereby suppressing the influence on the main chain amine in formula (5) and improving the durability of the main chain amine against electrons and excitons.

[0102] [ka]

[0103] (In formula (10), Ar 11 and Ar 12 each independently represents a divalent aromatic hydrocarbon group which may have a substituent or a divalent aromatic heterocyclic group which may have a substituent, Ar 13 ~Ar 15 are each independently a hydrogen atom or a substituent. * indicates the bonding position to the nitrogen atom in formula (2).

[0104] (Ar 13 ~Ar 15 ) Ar 13 ~Ar 15 Each of Ar independently represents a hydrogen atom or a substituent. 13 ~Ar 15 When Ar is a substituent, the substituent is not particularly limited, but is preferably an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. 4 The groups are the same as those listed above.

[0105] Ar 13 ~Ar 15 is a substituent, Ar 13 ~Ar 15 is preferably bonded to the 3- or 6-position of each carbazole structure from the viewpoint of improving durability.

[0106] Ar 13 ~Ar 15 is preferably a hydrogen atom from the viewpoint of ease of synthesis and charge transport properties.

[0107] Ar 13 ~Ar 15 From the viewpoint of improving durability and charge transport properties, is preferably an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent, and more preferably an aromatic hydrocarbon group which may have a substituent.

[0108] Ar 13 ~Ar 15 When is an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group, the substituents are the same as those exemplified in the above-mentioned substituent group Z, the preferred substituents are also the same, and the substituents that these substituents may further have are also the same.

[0109] (Ar 12 ) Ar 12 is a divalent aromatic hydrocarbon group which may have a substituent or a divalent aromatic heterocyclic group which may have a substituent.

[0110] 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 divalent groups of 6-membered monocyclic or 2- to 5-condensed rings such as a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring, or groups in which multiple such groups are linked together. When multiple such groups are linked together, the multiple linked divalent aromatic hydrocarbon groups are preferably conjugated.

[0111] The aromatic heterocyclic group preferably has 3 to 60 carbon atoms, and specific examples thereof include a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, a carbazole ring, a pyrroloimidazole ring, a pyrrolopyrazole ring, a pyrrolopyrrole ring, a thienopyrrole ring, a thienothiophene ring, a furopyrrole ring, a furofuran ring, a thienofuran ring, and a benzoiso Examples thereof include a divalent group of a 5- or 6-membered monocyclic ring or a 2- to 4-condensed ring such as an oxazole ring, a benzisothiazole ring, a benzimidazole ring, a pyridine ring, a pyrazine ring, a pyridazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a cinnoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, or an azulene ring, or a group in which a plurality of these rings are linked together.

[0112] 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 above-mentioned substituent group Z. 12 In the case where the structure of Ar is twisted, it is preferable to have no substituents. 12 In the case where the structure does not become distorted, it is preferable that the group has a substituent.

[0113] Ar 12 Specific preferred groups are divalent groups of a benzene ring, a naphthalene ring, an anthracene ring, or a fluorene ring, or a group in which multiple such groups are linked together, more preferably a divalent group of a benzene ring or a group in which multiple such groups are linked together, particularly preferably a 1,4-phenylene group in which benzene rings are linked together at the 1- and 4-positions, a 2,7-fluorenylene group in which fluorene rings are linked together at the 2- and 7-positions, or a group in which multiple such groups are linked together, and most preferably a group containing "1,4-phenylene group-2,7-fluorenylene group-1,4-phenylene group-".

[0114] In these preferred structures, the phenylene group does not have a substituent other than the linking position, which is due to the steric effect of the substituent. 12In addition, it is preferable that the fluorenylene group has substituents at the 9,9' positions from the viewpoint of improving the solubility and durability of the fluorene structure.

[0115] (Ar 11 ) Ar 11 is a divalent group that connects to the nitrogen atom of the main chain amine in formula (10). 11 is a divalent aromatic hydrocarbon group which may have a substituent or a divalent aromatic heterocyclic group which may have a substituent.

[0116] Ar 11 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 divalent groups of a 6-membered monocyclic ring or 2 to 5 condensed rings such as a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring, or groups in which a plurality of these rings are linked together.

[0117] Ar 11 The aromatic heterocyclic group preferably has 3 to 60 carbon atoms. Specific examples thereof include a 5- or 6-membered monocyclic or 2- to 4-fused ring divalent group, such as a 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, 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, and azulene ring, or a group in which a plurality of these are linked together.

[0118] The substituents which these aromatic hydrocarbon groups or aromatic heterocyclic groups may have include the alkyl groups, aralkyl groups and aromatic hydrocarbon groups of the above-mentioned substituent group Z.

[0119] When a plurality of such divalent aromatic hydrocarbon groups or divalent aromatic heterocyclic groups are linked, the plurality of linked divalent aromatic hydrocarbon groups are preferably linked so as not to be conjugated. Specifically, it is preferable that the group contains a 1,3-phenylene group or a group having a substituent and forming a twisted structure due to the steric effect of the substituent.

[0120] (Ar 5 ) Ar 5 The aromatic hydrocarbon group in the formula (5) is Ar 4 In addition, Ar 5 The aromatic hydrocarbon group and the substituents which the aromatic hydrocarbon group may have in the above formula are preferably the same groups as those in the group Z of substituents.

[0121] (crosslinking group) The second polymer used in the second organic layer does not have a crosslinking group. Here, the crosslinking group refers to a group that reacts with another crosslinking group located in the vicinity of the crosslinking group upon exposure to heat and / or active energy rays to form a new chemical bond. In this case, the reactive group may be the same as or different from the crosslinking group.

[0122] Examples of the crosslinking group include a group containing an alkenyl group, a group containing a conjugated diene structure, a group containing an alkynyl group, a group containing an oxirane structure, a group containing an oxetane structure, a group containing an aziridine structure, an azide group, a group containing a maleic anhydride structure, a group containing an alkenyl group bonded to an aromatic ring, a cyclobutene ring fused to an aromatic ring, etc. Specific examples of the crosslinking group include groups selected from the following group T of crosslinking groups.

[0123] (Bridging group T) [ka]

[0124] In the above-mentioned bridging group T, R XL represents a methylene group, an oxygen atom, or a sulfur atom; n XL represents an integer from 0 to 5. XL When there are multiple, they may be the same or different, and n XL When there are multiple groups, they may be the same or different. *1 indicates the bonding position. These bridging groups may have a substituent.

[0125] Hereinafter, the repeating unit represented by formula (2), the repeating unit represented by formula (3), and the repeating unit represented by formula (4) will be described in detail as more preferred repeating units of formula (5).

[0126] <Repeating unit represented by formula (2)> [ka]

[0127] (In formula (2), Ar 1 is 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 group in which a plurality of groups selected from an aromatic hydrocarbon group which may have a substituent other than a bridging group and an aromatic heterocyclic group which may have a substituent other than a bridging group are linked together, X is -C(R 7 )(R 8 )-, -N(R 9 )- or -C(R 11 )(R 12 )-C(R 13 )(R 14 )- and R 1 and R 2 each independently represents an alkyl group which may have a substituent other than a crosslinking group, R 7 ~R 9 and R 11~R 14 each independently represents a hydrogen atom, an alkyl group which may have a substituent other than a bridging group, an aralkyl group which may have a substituent other than a bridging group, or an aromatic hydrocarbon group which may have a substituent other than a bridging group, a and b each independently represent an integer of 0 to 4, c is an integer from 1 to 3, d is an integer from 0 to 4, R 1 If there are multiple R 1 may be the same or different, R 2 If there are multiple R 2 may be the same or different.)

[0128] (R 1 , R 2 ) R in the repeating unit represented by the above formula (2) 1 and R 2 are each independently an alkyl group which may have a substituent other than a crosslinking group.

[0129] 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 second polymer, it is preferably 1 or more, and is preferably 8 or less, more preferably 6 or less, and even more preferably 3 or less. The alkyl group is more preferably a methyl group or an ethyl group.

[0130] R 1 If there are multiple R 1 may be the same or different, and R 2 If there are multiple R 2 may be the same or different. Since the charge can be uniformly distributed around the nitrogen atom and synthesis is easy, all R 1 and R 2 are preferably the same group.

[0131] (R 7 ~R9 and R 11 ~R 14 ) R 7 ~R 9 and R 11 ~R 14 are each independently a hydrogen atom, an alkyl group which may have a substituent other than a bridging group, an aralkyl group which may have a substituent other than a bridging group, or an aromatic hydrocarbon group which may have a substituent other than a bridging group.

[0132] The alkyl group is not particularly limited, but since this tends to improve the solubility of the second polymer, the number of carbon atoms is preferably 1 or more and is preferably 24 or less, more preferably 8 or less, and even more preferably 6 or less. The alkyl group may have a linear, branched, or cyclic structure.

[0133] Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a tert-butyl group, an n-hexyl group, an n-octyl group, a cyclohexyl group, and a dodecyl group.

[0134] The aralkyl group is not particularly limited, but preferably has 5 or more carbon atoms, and preferably 60 or less, more preferably 40 or less, since this tends to improve the solubility of the second polymer.

[0135] Specific examples of the aralkyl group include a 1,1-dimethyl-1-phenylmethyl group, a 1,1-di(n-butyl)-1-phenylmethyl group, a 1,1-di(n-hexyl)-1-phenylmethyl group, a 1,1-di(n-octyl)-1-phenylmethyl group, a phenylmethyl group, a phenylethyl group, a 3-phenyl-1-propyl group, a 4-phenyl-1-n-butyl group, a 1-methyl-1-phenylethyl group, a 5-phenyl-1-n-propyl group, a 6-phenyl-1-n-hexyl group, a 6-naphthyl-1-n-hexyl group, a 7-phenyl-1-n-heptyl group, an 8-phenyl-1-n-octyl group, and a 4-phenylcyclohexyl group.

[0136] The aromatic hydrocarbon group is not particularly limited, but preferably has 6 or more carbon atoms, and preferably 60 or less, more preferably 30 or less, since this tends to improve the solubility of the second polymer.

[0137] Specific examples of the aromatic hydrocarbon group include monovalent groups of 6-membered monocyclic rings or 2 to 5 condensed rings, such as a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring, or groups in which multiple of these are linked together.

[0138] From the viewpoint of improving charge transport properties and durability, R 7 and R 8 is preferably a methyl group or an aromatic hydrocarbon group, and R 7 and R 8 is more preferably a methyl group, and R 9 is more preferably a phenyl group.

[0139] R 1 , R 2 alkyl group, R 7 ~R 9 and R 11 ~R 14 The alkyl group, aralkyl group and aromatic hydrocarbon group may have a substituent other than a bridging group. The substituent other than a bridging group may be any of the substituents described above in R 7 ~R 9 and R 11 ~R 14 Examples of the alkyl group, aralkyl group and aromatic hydrocarbon group include those mentioned above as preferred groups.

[0140] R 1 , R 2 alkyl group, R 7 ~R 9 and R 11 ~R 14 From the viewpoint of reducing the voltage, it is most preferable that the alkyl group, aralkyl group and aromatic hydrocarbon group have no substituent.

[0141] (a, b, c and d) In the repeating unit represented by the above formula (2), a and b each independently represent an integer of 0 to 4. It is preferable that a+b is 1 or greater, and it is further preferable that a and b are each 2 or less, and it is more preferable that both a and b are 1.

[0142] When a+b is 1 or more, the aromatic rings in the main chain are twisted due to steric hindrance, resulting in excellent solubility of the second polymer in solvents, and the coating film formed by the wet film-forming method and heat-treated tends to be excellent insolubility in solvents. Therefore, when a+b is 1 or more, when another organic layer (e.g., a light-emitting layer) is formed on this coating film by the wet film-forming method, elution of the second polymer into the composition for forming a light-emitting layer of the present invention, which contains an organic solvent, is suppressed. As a result, it is thought that the formed light-emitting layer is less affected, and the operating life of the quantum dot light-emitting device is further extended.

[0143] In the repeating unit represented by the above formula (2), c is an integer of 1 to 3, and d is an integer of 0 to 4. It is preferable that c and d are each 2 or less, more preferably c and d are equal, and particularly preferably that both c and d are 1 or both c and d are 2.

[0144] In the repeating unit represented by the above formula (2), when both c and d 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 positions symmetrical to each other.

[0145] where R 1 and R 2 and are bonded at positions symmetrical to each other means that R 1 and R 2 In this case, a 180-degree rotation around the main chain is considered to be the same structure.

[0146] (Ar1 ) In the repeating unit represented by the above formula (2), Ar 1 is 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 group in which multiple groups selected from an aromatic hydrocarbon group which may have a substituent other than a bridging group and an aromatic heterocyclic group which may have a substituent other than a bridging group are linked together.

[0147] Examples of the group formed by linking a plurality of groups selected from the aromatic hydrocarbon group which may have a substituent other than a bridging group, the aromatic heterocyclic group which may have a substituent other than a bridging group, and the aromatic hydrocarbon group which may have a substituent other than a bridging group and the aromatic heterocyclic group which may have a substituent other than a bridging group include the above-mentioned Ar 4 The same substituents as those in the case of Ar are listed, and the preferred structures and substituents other than the bridging group are also listed. 4 The same as in the case of

[0148] (Other preferred Ar 1 ) Ar in the repeating unit represented by the above formula (2) 1 At least one of the above is more preferably a group represented by the formula (10).

[0149] (X) X in the above formula (2) is -C(R 7 )(R 8 )- or -N(R 9 )-, and -C(R 7 )(R 8 )- is more preferred.

[0150] In addition, in the polymer containing the repeating unit represented by the above formula (2), Ar 1 , R 1 , R 2When there are a plurality of X's, they may be the same or different. Preferably, the polymer contains a plurality of repeating units represented by formula (2) having the same structure. In this case, when the polymer contains a plurality of repeating units having the same structure, the HOMO and LUMO of the repeating units are the same, so that charges are not concentrated at a specific shallow level to form traps, and it is thought that this results in excellent charge transport properties.

[0151] (Preferred repeating unit) The repeating unit represented by the above formula (2) is particularly preferably a repeating unit represented by any one of the following formulae (2-1) to (2-4).

[0152] [ka]

[0153] In the above formula, R 1 and R 2 are identical and R 1 and R 2 are bonded at symmetric positions to each other.

[0154] <Specific examples of the main chain of the repeating unit represented by formula (2)> The main chain structure excluding the nitrogen atom in the above formula (2) is not particularly limited, but examples include the following structures.

[0155] [ka]

[0156] [ka]

[0157] [ka]

[0158] [ka]

[0159] [ka]

[0160] [ka]

[0161] [ka]

[0162] <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 usually contained in the second polymer in an amount of 10 mol % or more, preferably 30 mol % or more, more preferably 40 mol % or more, and even more preferably 50 mol % or more.

[0163] The second polymer contained in the second organic layer may be composed solely of repeating units represented by formula (2), but may also contain repeating units other than formula (2) in order to balance the various performances when formed into a quantum dot light-emitting device. In this case, the content of repeating units represented by formula (2) in the second polymer is usually 99 mol % or less, preferably 95 mol % or less.

[0164] <Terminal group> In this specification, the term "terminal group" refers to the structure of the terminal portion of the second polymer formed by an endcapping agent used at the end of polymerization of the second polymer. In the second organic layer, the terminal group of the second polymer containing the repeating unit 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.

[0165] Examples of the hydrocarbon group include: a linear, branched, or cyclic alkyl group having usually 1 or more, preferably 4 or more, and usually 24 or less, preferably 12 or less, carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a tert-butyl group, an n-hexyl group, a cyclohexyl group, or a dodecyl group; a linear, branched, or cyclic alkenyl group, such as a vinyl group, which generally has 2 or more and 24 or less carbon atoms, and preferably 12 or less carbon atoms; a linear or branched alkynyl group, such as an ethynyl group, having typically 2 to 24 carbon atoms, preferably 12 or less; Examples include aromatic hydrocarbon groups having usually 6 to 36 carbon atoms, preferably 24 or less, such as phenyl and naphthyl groups.

[0166] These hydrocarbon groups may further have a substituent, and the optional substituent is preferably an alkyl group or an aromatic hydrocarbon group. When there are a plurality of these optional additional substituents, they may be bonded to each other to form a ring.

[0167] From the viewpoint of charge transportability and durability, the terminal group is preferably an alkyl group or an aromatic hydrocarbon group, and more preferably an aromatic hydrocarbon group.

[0168] <Repeating unit represented by formula (3)> [ka]

[0169] (In formula (3), Ar 2 is 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 group in which a plurality of groups selected from an aromatic hydrocarbon group which may have a substituent other than a bridging group and an aromatic heterocyclic group which may have a substituent other than a bridging group are linked together, R 3 and R 6 each independently represents an alkyl group which may have a substituent other than a crosslinking group, R 4 and R 5 each independently represents an alkyl group which may have a substituent other than a crosslinking group, an alkoxy group which may have a substituent other than a crosslinking group, or an aralkyl group which may have a substituent other than a crosslinking group, 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.

[0170] (R 3 , R 6 ) R in the repeating unit represented by the above formula (3) 3 and R 6 are each independently an alkyl group which may have a substituent other than a crosslinking group. The alkyl group is R 1 and R 2 The substituents that may be present and preferred structures are the same as those of R 1 and R 2 The same can be mentioned.

[0171] (R 4 , R 5 ) R in the repeating unit represented by the above formula (3) 4 and R 5are each independently an alkyl group which may have a substituent other than a crosslinking group, an alkoxy group which may have a substituent other than a crosslinking group, or an aralkyl group which may have a substituent other than a crosslinking group.

[0172] 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 is preferably 1 or more, and is preferably 24 or less, more preferably 8 or less, and even more preferably 6 or less, since this tends to improve the solubility of the polymer.

[0173] Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a tert-butyl group, an n-hexyl group, an n-octyl group, a cyclohexyl group, and a dodecyl group.

[0174] The alkoxy group is not particularly limited, and may be an alkoxy group (—OR 10 )R 10 The alkyl group represented by the formula (I) may have any of a linear, branched, or cyclic structure, and preferably has 1 or more carbon atoms, and preferably 24 or less, and more preferably 12 or less, since this tends to improve the solubility of the polymer.

[0175] Specific examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, a hexyloxy group, a 1-methylpentyloxy group, and a cyclohexyloxy group.

[0176] The aralkyl group is not particularly limited, but preferably has 5 or more carbon atoms, and preferably 60 or less, more preferably 40 or less, since this tends to improve the solubility of the polymer.

[0177] Specific examples of the aralkyl group include a 1,1-dimethyl-1-phenylmethyl group, a 1,1-di(n-butyl)-1-phenylmethyl group, a 1,1-di(n-hexyl)-1-phenylmethyl group, a 1,1-di(n-octyl)-1-phenylmethyl group, a phenylmethyl group, a phenylethyl group, a 3-phenyl-1-propyl group, a 4-phenyl-1-n-butyl group, a 1-methyl-1-phenylethyl group, a 5-phenyl-1-n-propyl group, a 6-phenyl-1-n-hexyl group, a 6-naphthyl-1-n-hexyl group, a 7-phenyl-1-n-heptyl group, an 8-phenyl-1-n-octyl group, and a 4-phenylcyclohexyl group.

[0178] (l, m and k) l represents 0 or 1; k represents 0 or 1;

[0179] l and k are each independent, and l+k is preferably 1 or greater, more preferably 1 or 2, and even more preferably 2. When l+k is within the above range, the solubility of the second polymer contained in the second organic layer tends to be increased, and precipitation from the second composition containing the polymer also tends to be suppressed.

[0180] m represents 1 or 2, and is preferably 1, since the quantum dot light-emitting device of the present invention can be driven at a low voltage and tends to have improved hole injection ability, transport ability, and durability.

[0181] (p and q) p represents 0 or 1, and q represents 0 or 1. When l=k=1, p and q cannot be 0 at the same time. When 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. Furthermore, for the same reasons as in a and b above, when p+q is 1 or more, the operating life of the quantum dot light-emitting device is considered to be further extended, which is preferable.

[0182] (Ar 2 ) In the repeating unit represented by the above formula (3), Ar 2is 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 group in which multiple groups selected from an aromatic hydrocarbon group which may have a substituent other than a bridging group and an aromatic heterocyclic group which may have a substituent other than a bridging group are linked together.

[0183] The aromatic hydrocarbon group which may have a substituent other than a bridging group, the aromatic heterocyclic group which may have a substituent other than a bridging group, or the group in which a plurality of groups selected from the aromatic hydrocarbon group which may have a substituent other than a bridging group and the aromatic heterocyclic group which may have a substituent other than a bridging group are linked together includes Ar 1 The same substituents as those in the case of Ar are listed, and the preferred structures and substituents other than the bridging group are also listed. 1 The same as in the case of

[0184] Also, Ar 2 is also preferably a spirobifluorenyl group from the viewpoint of solubility in a coating solvent.

[0185] In particular, Ar 2 is preferably a group represented by the following formula (15) or a group represented by the following formula (16).

[0186] [ka]

[0187] (In formulas (15) and (16), * represents the bonding position with the nitrogen atom in formula (3).)

[0188] (Other preferred Ar 2 ) The Ar 1 Similarly, Ar 2 At least one of the Ar 2 When at least one of the groups is a group represented by the formula (10), the preferred structure of the formula (10) and the substituents that may be possessed are as follows: 1The same applies as when at least one of the groups is a group represented by the formula (10).

[0189] <Specific examples of the main chain of the repeating unit represented by formula (3)> The main chain structure excluding the nitrogen atom in formula (3) is not particularly limited, but examples include the following structures.

[0190] [ka]

[0191] [ka]

[0192] [ka]

[0193] [ka]

[0194] [ka]

[0195] [ka]

[0196] [ka]

[0197] [ka]

[0198] <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 contained in the second polymer at 10 mol % or more, preferably 30 mol % or more, more preferably 40 mol % or more, and particularly preferably 50 mol % or more.

[0199] The second polymer contained in the second organic layer may be composed solely of repeating units represented by formula (3), but may also contain repeating units other than formula (3) in order to balance the various performances when formed into a quantum dot light-emitting device. In this case, the content of repeating units represented by formula (3) in the second polymer is usually 99 mol % or less, preferably 95 mol % or less.

[0200] <Terminal group> In the second polymer contained in the second organic layer, the end group of the second polymer containing the repeating unit represented by formula (3) is preferably a hydrocarbon group, similar to the end group of the second polymer containing the repeating unit represented by formula (2). Preferred hydrocarbon groups and the substituents that may be present are also similar to those of the end group of the polymer containing the repeating unit represented by formula (2).

[0201] [Repeating unit represented by formula (4)] [ka]

[0202] (In formula (4), Ar 3 is 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 group in which a plurality of groups selected from an aromatic hydrocarbon group which may have a substituent other than a bridging group and an aromatic heterocyclic group which may have a substituent other than a bridging group are linked together, Ar 41represents a divalent aromatic hydrocarbon group which may have a substituent other than a bridging group, a divalent aromatic heterocyclic group which may have 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 the divalent aromatic hydrocarbon groups and the divalent aromatic heterocyclic groups are linked together directly or via a linking group, R 41 and R 42 each independently represents an alkyl group which may have a substituent other than a crosslinking group, t is 1 or 2; u is 0 or 1; r and s are each independently an integer of 0 to 4.

[0203] (R 41 , R 42 ) R in the repeating unit represented by the above formula (4) 41 , R 42 are each independently an alkyl group which may have a substituent other than a crosslinking group.

[0204] 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, and is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. The alkyl group is more preferably a methyl group or a hexyl group.

[0205] R 41 and R 42 When there are a plurality of R 41 and R 42 may be the same or different.

[0206] (r, s, t and u) In the repeating unit represented by formula (4), r and s are each independently an integer of 0 to 4. r+s is preferably 1 or greater, and each of r and s is preferably 2 or less. When r+s is 1 or greater, the operating life of the quantum dot light-emitting device is thought to be further extended for the same reasons as for a and b in formula (2).

[0207] In the repeating unit represented by the above formula (4), t is 1 or 2, and u is 0 or 1. t is preferably 1, and u is preferably 1.

[0208] (Ar 3 ) 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, an aromatic heterocyclic group which may have a substituent other than a bridging group, or a group in which multiple groups selected from an aromatic hydrocarbon group which may have a substituent other than a bridging group and an aromatic heterocyclic group which may have a substituent other than a bridging group are linked together.

[0209] Examples of the group in which a plurality of groups selected from 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, and an aromatic hydrocarbon group which may have a substituent other than a bridging group and an aromatic heterocyclic group which may have a substituent other than a bridging group are linked include Ar 4 The same substituents as those in the case of Ar are listed, and the preferred structures and substituents other than the bridging group are also listed. 4 The same as in the case of

[0210] (Ar 41 ) Ar 41 is a divalent aromatic hydrocarbon group which may have a substituent other than a bridging group, a divalent aromatic heterocyclic group which may have 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 the divalent aromatic hydrocarbon groups and the divalent aromatic heterocyclic groups are linked together directly or via a linking group.

[0211] Ar 41 The aromatic hydrocarbon group in the formula (5) is preferably Ar 5 The aromatic hydrocarbon group and the substituents that the aromatic hydrocarbon group may have are preferably the same as those in the substituent group Z, and the substituents that the aromatic hydrocarbon group may further have are also preferably the same as those in the substituent group Z.

[0212] <Specific examples of repeating units represented by formula (4)> The repeating unit represented by formula (4) is not particularly limited, but examples thereof include the following structures.

[0213] [ka]

[0214] <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 contained in the second polymer at 10 mol % or more, preferably 30 mol % or more, more preferably 40 mol % or more, and particularly preferably 50 mol % or more.

[0215] The second polymer contained in the second organic layer may be composed solely of repeating units represented by formula (4), but may also contain repeating units other than formula (4) in order to balance the various performances when formed into a quantum dot light-emitting device. In this case, the content of repeating units represented by formula (4) in the second polymer is usually 99 mol % or less, preferably 95 mol % or less.

[0216] <Terminal group> In the second polymer contained in the second organic layer, the end group of the polymer containing the repeating unit represented by formula (4) is preferably a hydrocarbon group, similar to the end group of the second polymer containing the repeating unit represented by formula (2). Preferred hydrocarbon groups and the substituents that may be present are also similar to those of the end group of the polymer containing the repeating unit represented by formula (2).

[0217] [Molecular weight of second polymer] The molecular weight of the second polymer contained in the second organic layer will be described below.

[0218] 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, even 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, even more preferably 15,000 or more, and particularly preferably 17,000 or more.

[0219] 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 upper limit, solubility in a solvent is obtained and film-forming properties tend to be excellent. On the other hand, when the weight-average molecular weight of the polymer is equal to or greater than the lower limit, decreases in the glass transition temperature, melting point, and vaporization temperature of the polymer are suppressed, and heat resistance may be improved.

[0220] 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, and particularly preferably 100,000 or less, and is usually 2,000 or more, preferably 4,000 or more, more preferably 6,000 or more, and even more preferably 8,000 or more.

[0221] Furthermore, the dispersity (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 or less. Since the smaller the dispersity, the better, the lower limit is ideally 1. When the dispersity of the polymer is equal to or less than the above upper limit, purification is easy, and the solubility in solvents and charge transport ability are good.

[0222] 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, and even more preferably 17,000 or more, and is preferably 2,000,000 or less, more preferably 1,000,000 or less, and particularly preferably 100,000 or less.

[0223] When the weight-average molecular weight of the second polymer containing the repeating unit represented by formula (3) or (4) is not more than the upper limit, the increase in molecular weight of impurities is suppressed, and purification tends to be easy. On the other hand, when the weight-average molecular weight of the polymer is not less than the lower limit, the decrease in the glass transition temperature, melting point, vaporization temperature, etc. is suppressed, and heat resistance tends to be improved.

[0224] The number average molecular weight (Mn) of the second polymer containing the repeating unit represented by formula (3) or formula (4) is preferably 1,000,000 or less, more preferably 800,000 or less, and even more preferably 500,000 or less, and is preferably 4,000 or more, more preferably 8,000 or more, and even more preferably 10,000 or more.

[0225] 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, even more preferably 2.4 or less, particularly preferably 2.1 or less, and most preferably 2 or less. The dispersity of the polymer is preferably 1 or more, more preferably 1.1 or more, and even more preferably 1.2 or more. When the dispersity of the polymer is the above upper limit or less, purification becomes easy, and a decrease in solubility in solvents and a decrease in charge transport ability tend to be suppressed.

[0226] The weight-average molecular weight and number-average molecular weight of a polymer are usually determined by SEC (size exclusion chromatography) measurement. In SEC measurement, the higher the molecular weight component, the shorter the elution time, and the lower the molecular weight component, the longer the elution time. The weight-average molecular weight and number-average molecular weight are calculated by converting the elution time of the sample into molecular weight using a calibration curve calculated from the elution time of polystyrene (standard sample) with known molecular weight.

[0227] [Specific 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 formula represent the molar ratio of the repeating unit. n represents the number of repeats.

[0228] These second polymers may be any of random copolymers, alternating copolymers, block copolymers, graft copolymers, etc., and there are no limitations on the sequence of the monomers.

[0229] [ka]

[0230] A second polymer containing a repeating unit represented by formula (3) and an Ar repeating unit represented by formula (3) 2Specific examples of the second polymer having a structure represented by formula (10) are shown below, but the second polymer used in the present invention is not limited to these. The numbers in the chemical formula represent the molar ratio of repeating units, and n represents the number of repeats.

[0231] These second polymers may be any of random copolymers, alternating copolymers, block copolymers, graft copolymers, etc., and the sequence of the monomers is not limited.

[0232] [ka]

[0233] [ka]

[0234] [ka]

[0235] 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 formula represent the molar ratio of the repeating unit. n represents the number of repeats.

[0236] These second polymers may be any of random copolymers, alternating copolymers, block copolymers, graft copolymers, etc., and there are no limitations on the sequence of the monomers.

[0237] [ka]

[0238] [ka]

[0239] <Method for producing the second polymer> The method for producing the second polymer contained in the second organic layer is not particularly limited and may be any method, such as a polymerization method based on the Suzuki reaction, a polymerization method based on the Grignard reaction, a polymerization method based on the Yamamoto reaction, a polymerization method based on the Ullmann reaction, or a polymerization method based on the Buchwald-Hartwig reaction.

[0240] In the polymerization method using the Ullmann reaction and the polymerization method using the Buchwald-Hartwig reaction, for example, a dihalogenated aryl represented by the following formula (2a) (Z represents a halogen atom such as I, Br, Cl, or F) is reacted with a primary aminoaryl represented by the following formula (2b) to synthesize a second polymer containing a repeating unit represented by the formula (2).

[0241] [ka]

[0242] (In the above reaction scheme, Ar 1 , R 1 , R 2 , X, and a to d have the same meanings as in the formula (2).

[0243] In the case of the polymerization method using the Ullmann reaction and the polymerization method using the Buchwald-Hartwig reaction, for example, a polymer containing a repeating unit represented by formula (3) is synthesized by reacting an aryl dihalide represented by formula (3a) (Z represents a halogen atom such as I, Br, Cl, or F) with a primary aminoaryl represented by formula (3b).

[0244] [ka]

[0245] (In the above reaction scheme, Ar 2 , R 3 ~R 6 , k to m, p, and q have the same meanings as in the formula (3).

[0246] In the above polymerization method, the reaction for forming the N-aryl bond is usually carried out in the presence of a base such as potassium carbonate, sodium tert-butoxide, triethylamine, etc. Alternatively, it can be carried out in the presence of a transition metal catalyst such as a copper or palladium complex.

[0247] [Second Composition] The second composition that forms the second organic layer will now be described. The second composition contains a second polymer and a solvent (organic solvent). This second composition is usually used to form an organic layer of the quantum dot light-emitting device of the present invention by a wet film-forming method. The organic layer is preferably a hole transport layer adjacent to the light-emitting layer formed from the light-emitting layer-forming composition of the present invention. The second composition may contain one type of second polymer, or two or more types in any combination and in any ratio.

[0248] (Content of second polymer) The content of the second polymer in the second composition is usually 0.01% by mass to 70% by mass, preferably 0.1% by mass to 60% by mass, and more preferably 0.5% by mass to 50% by mass. When the content of the second polymer is within the above range, defects are unlikely to occur in the formed organic layer, and thickness unevenness is unlikely to occur, which is preferable.

[0249] (solvent) The second composition usually contains a solvent. This solvent is preferably one that dissolves the second polymer. Specifically, a solvent that dissolves the second polymer in the second composition at room temperature is suitable, typically 0.05% by mass or more, preferably 0.5% by mass or more, and more preferably 1% by mass or more.

[0250] Specific examples of the solvent include aromatic solvents such as toluene, xylene, mesitylene, cyclohexylbenzene, and methylnaphthalene; halogen-containing solvents such as 1,2-dichloroethane, chlorobenzene, and o-dichlorobenzene; aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, and 3-methoxytoluene. Examples of organic solvents include ether-based solvents such as aromatic ethers such as benzene, 4-methoxytoluene, 2,3-dimethylanisole, and 2,4-dimethylanisole; aliphatic ester-based solvents such as ethyl acetate, n-butyl acetate, ethyl lactate, and n-butyl lactate; and 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; as well as organic solvents used in the composition for forming a hole injection layer and the composition for forming a hole transport layer, which will be described later.

[0251] The solvent may be used alone or in any combination of two or more in any ratio.

[0252] The surface tension of the solvent at 20° C. is usually less than 40 dyn / cm, preferably 36 dyn / cm or less, more preferably 33 dyn / cm or less.

[0253] 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 that is suitable for the process of producing a quantum dot light-emitting device by a wet film-forming method and that is suited to the properties of the second polymer.

[0254] Specific examples of such solvents include the above-mentioned aromatic solvents such as toluene, xylene, mesitylene, and cyclohexylbenzene, ether solvents, and ester solvents.

[0255] However, moisture can cause performance degradation of quantum dot light-emitting devices, particularly accelerating a decrease in brightness during continuous operation. Therefore, in order to minimize the amount of moisture remaining during wet film formation, the water solubility of the solvent at 25°C is preferably 1% by mass or less, and more preferably 0.1% by mass or less.

[0256] 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. By ensuring that the solvent content is equal to or greater than the lower limit, the flatness and uniformity of the formed layer can be improved.

[0257] [Electron-accepting compounds] In order to reduce the resistance, the second composition preferably further contains an electron-accepting compound. In particular, when the second composition is used to form a hole injection layer, the second composition preferably contains an electron-accepting compound.

[0258] The electron-accepting compound is preferably a compound having oxidizing power and the ability to accept one electron from the second polymer contained in the second organic layer. Specifically, a compound having an electron affinity of 4 eV or more is preferred, and a compound having an electron affinity of 5 eV or more is more preferred.

[0259] The second composition may contain one type of electron-accepting compound as described above, or may contain two or more types in any combination and ratio.

[0260] 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 20% by mass or less, preferably 10% by mass or less.

[0261] Furthermore, 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 usually 80% by mass or less, preferably 60% by mass or less, and even more preferably 40% by mass or less.

[0262] When the content of the electron-accepting compound in the second composition is equal to or greater than the lower limit, the electron acceptor accepts electrons from the second polymer, thereby reducing the resistance of the formed organic layer. When the content of the electron-accepting compound in the second composition is equal to or less than the upper limit, the formed organic layer is less likely to have defects and less likely to have uneven thickness.

[0263] [Cation radical compounds] The second composition may further contain a cation radical compound. The cation radical compound is preferably an ionic compound consisting of a cation radical, which is a chemical species obtained by removing one electron from a hole-transporting compound, and a counter anion. 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.

[0264] The cation radical is preferably a chemical species obtained by removing one electron from a hole transport compound described below, which is preferable in terms of amorphousness, visible light transmittance, heat resistance, solubility, etc.

[0265] The cation radical compound can be produced by mixing a hole transport compound (described later) with the electron acceptor compound described above. That is, by mixing the hole transport compound with the electron acceptor compound, electrons are transferred from the hole transport compound to the electron acceptor compound, and a cation ion compound consisting of a cation radical of the hole transport compound and a counter anion is produced.

[0266] 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 or less, preferably 20% by mass or less. A content of the cation radical compound equal to or greater than the lower limit is preferred because the resistance of the formed organic layer is low, while a content of the cation radical compound equal to or less than the upper limit is preferred because defects are less likely to occur in the formed organic layer and film thickness unevenness is less likely to occur.

[0267] In addition to the above components, the second composition may contain components contained in the composition for forming a hole injection layer or the composition for forming a hole transport layer, which will be described later, in the amounts described later.

[0268] [Structure of quantum dot light-emitting device] As an example of the structure of the quantum dot light-emitting device of the present invention, a schematic diagram (cross section) of an example of the structure of a quantum dot light-emitting device 8 is shown in Fig. 1. In Fig. 1, 1 represents a substrate, 2 represents an anode, 3 represents a hole injection layer, 4 represents a hole transport layer, 5 represents a light-emitting layer, 6 represents an electron transport layer, and 7 represents a cathode.

[0269] <Substrate> The substrate 1 serves as a support for the quantum dot light-emitting element, and is typically made of a quartz or glass plate, a metal plate or metal foil, a plastic film or sheet, or the like. Of these, a glass plate or a plate made of a transparent synthetic resin such as polyester, polymethacrylate, polycarbonate, or polysulfone is preferred. The substrate is preferably made of a material with high gas barrier properties, as this makes it less likely for the quantum dot light-emitting element to deteriorate due to exposure to the outside air. Therefore, when using a material with 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.

[0270] <Anode> The anode 2 has the function of injecting holes into the layer on the light-emitting layer 5 side.

[0271] The anode 2 is usually made of a metal such as aluminum, gold, silver, nickel, palladium, or platinum; a metal oxide such as indium and / or tin oxide; a metal halide such as copper iodide; carbon black, or a conductive polymer such as poly(3-methylthiophene), polypyrrole, or polyaniline.

[0272] The anode 2 is usually formed by a dry method such as sputtering or vacuum deposition. When forming the anode using metal particles such as silver, copper iodide, carbon black, conductive metal oxide particles, or conductive polymer fine powder, the anode can be formed by dispersing the particles in an appropriate binder resin solution and applying it to the substrate. In the case of a conductive polymer, a thin film can be formed directly on the substrate by electrolytic polymerization, or the anode can be formed by applying the conductive polymer to the substrate (Appl. Phys. Lett., Vol. 60, p. 2711, 1992).

[0273] 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, a different conductive material may be laminated on the first layer of the anode.

[0274] The thickness of the anode 2 may be determined depending on the required transparency, material, etc. When particularly high transparency is required, a thickness that provides a visible light transmittance of 60% or more is preferred, and a thickness that provides a visible light transmittance of 80% or more is even more preferred. The thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less. On the other hand, when transparency is not required, the thickness of the anode 2 may be arbitrarily determined depending on the required strength, etc. In this case, the anode 2 may have the same thickness as the substrate.

[0275] When another layer is formed on the surface of the anode 2, it is preferable to perform a treatment with ultraviolet light / ozone, oxygen plasma, argon plasma, or the like before the film formation to remove impurities on the anode 2 and adjust its ionization potential to improve hole injection properties.

[0276] <Hole injection layer> A layer that transports holes from the anode 2 side to the light-emitting layer 5 side is usually called a hole injection transport layer or a hole transport layer. When there are two or more layers that transport holes from the anode 2 side to the light-emitting layer 5 side, the layer closer to the anode side is sometimes 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 the hole injection layer 3 is formed, the hole injection layer 3 is usually formed on the anode 2.

[0277] The 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.

[0278] The hole injection layer may be formed by vacuum deposition or wet film formation, but is preferably formed by wet film formation in terms of excellent film formability.

[0279] 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 preferably formed by a wet film-forming method using a composition for forming a hole injection layer.

[0280] (Hole transporting compound) The hole injection layer-forming composition typically contains a hole transport compound that will become the hole injection layer 3. Furthermore, in the case of a wet film formation method, the hole injection layer-forming composition typically further contains a solvent. It is preferable that the hole injection layer-forming composition have high hole transport properties and can efficiently transport injected holes. Therefore, it is preferable that the hole injection layer-forming composition have high hole mobility and are less likely to generate impurities that become traps during production or use. It is also preferable that the composition have excellent stability, a small ionization potential, and high transparency to visible light. In particular, when the hole injection layer is in contact with the light-emitting layer, it is preferable that the composition do not quench the light emission from the light-emitting layer or form exciplexes with the light-emitting layer to prevent a decrease in light-emitting efficiency.

[0281] From the viewpoint of the charge injection barrier from the anode to the hole injection layer, the hole transport compound is preferably a compound having an ionization potential of 4.5 eV to 6.0 eV. Examples of the hole transport compound include aromatic amine compounds, phthalocyanine compounds, porphyrin compounds, oligothiophene compounds, polythiophene compounds, benzylphenyl compounds, compounds in which a tertiary amine is linked via a fluorene group, hydrazone compounds, silazane compounds, and quinacridone compounds.

[0282] Among the above-mentioned exemplary compounds, 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 compounds are compounds having an aromatic tertiary amine structure and also include compounds having a group derived from an aromatic tertiary amine.

[0283] The type of aromatic tertiary amine compound is not particularly limited, but it is preferable to use a polymer compound (polymerizable compound having a series of repeating units) having a weight-average molecular weight of 1,000 or more and 1,000,000 or less, since uniform light emission is easily obtained due to the surface smoothing effect.

[0284] (Formation of hole injection layer by wet film formation method) When forming the hole injection layer 3 by a wet film formation method, a composition for film formation (hole injection layer composition) is usually prepared by mixing the material for the hole injection layer with a soluble solvent (hole injection layer solvent). Then, the hole injection layer 3 is formed by applying the hole injection layer composition onto a layer (usually an anode) corresponding to the layer below the hole injection layer to form a film and drying it.

[0285] The concentration of the hole transport compound in the composition for forming a hole injection layer may be any concentration as long as it does not significantly impair the effects of the present invention, but a lower concentration is preferable in terms of uniformity of the film thickness, and a higher concentration is preferable in terms of preventing defects from occurring in the hole injection layer. Specifically, the concentration 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, while it is preferably 70% by mass or less, more preferably 60% by mass or less, and particularly preferably 50% by mass or less.

[0286] Examples of the solvent include ether solvents, ester solvents, aromatic hydrocarbon solvents, and amide solvents.

[0287] Examples of ether solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA), and aromatic ethers such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, and 2,4-dimethylanisole.

[0288] Examples of ester solvents include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate.

[0289] Examples of aromatic hydrocarbon solvents include toluene, xylene, cyclohexylbenzene, 3-isopropylbiphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, cyclohexylbenzene, and methylnaphthalene.

[0290] Examples of amide solvents include N,N-dimethylformamide and N,N-dimethylacetamide.

[0291] In addition to these, dimethyl sulfoxide and the like can also be used.

[0292] The hole injection layer 3 is usually formed by a wet film formation method by preparing a composition for forming the hole injection layer, applying the composition to a layer corresponding to the lower layer of the hole injection layer 3 (usually the anode 2), and then drying the composition. After the hole injection layer 3 is formed, the coated film is usually dried by heating, drying under reduced pressure, or the like.

[0293] (Formation of hole injection layer by vacuum deposition method) When forming the hole injection layer 3 by vacuum deposition, one or more types of materials constituting the hole injection layer 3 are usually placed in a crucible installed in a vacuum chamber (when two or more types of materials are used, each is usually placed in a separate crucible), and the inside of the vacuum chamber is vacuumed by a vacuum pump for 10 -4 The chamber is evacuated to approximately 100 Pa. The crucible is then heated (when two or more materials are used, each crucible is usually heated) and the materials in the crucible are evaporated while controlling their evaporation rates (when two or more materials are used, each material is usually evaporated while controlling its evaporation rate independently), forming a hole injection layer on the anode on the substrate placed opposite the crucible. When two or more materials are used, a mixture of the materials can also be placed in the crucible and heated to evaporate to form the hole injection layer.

[0294] The degree of vacuum during deposition is not limited as long as it does not significantly impair the effects of the present invention. -6 Torr (0.13 × 10 -4 Pa) or above, 9.0×10 -6 Torr (12.0 × 10 -4 The deposition rate is not limited as long as it does not significantly impair the effects of the present invention, but is usually 0.1 Å / sec or more and 5.0 Å / sec or less. The film formation temperature during deposition is not limited as long as it does not significantly impair the effects of the present invention, but is preferably 10°C or more and 50°C or less.

[0295] The hole injection layer 3 may be crosslinked.

[0296] <Hole transport layer> The hole transport layer 4 is a layer that transports holes from the anode 2 side to the light-emitting layer 5 side. In the quantum dot light-emitting device of the present invention, it is preferable to form the hole transport layer 4 in order to enhance the function of transporting holes from the anode 2 to the light-emitting layer 5. When the hole transport layer 4 is formed, it is usually formed between the anode 2 and the light-emitting layer 5. Furthermore, when the above-mentioned hole injection layer 3 is present, it is formed between the hole injection layer 3 and the light-emitting layer 5.

[0297] The 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.

[0298] The hole transport layer 4 may be formed by vacuum deposition or wet film formation, but is preferably formed by wet film formation in terms of excellent film formability.

[0299] A general method for forming a hole transport layer will be described below. In the quantum dot light-emitting device of the present invention, the hole transport layer is preferably formed by a wet film-forming method using the second composition described above as the composition for forming the hole transport layer.

[0300] The hole transport layer 4 usually contains a hole transport compound. The hole transport compound contained in the hole transport layer 4 is preferably the second polymer contained in the second organic layer.

[0301] The hole transport layer 4 may contain, in addition to the second polymer, the hole transport compound, an aromatic diamine containing two or more tertiary amines and having two or more condensed aromatic rings substituted with nitrogen atoms, such as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (JP-A-5-234681), an aromatic amine compound having a starburst structure such as 4,4',4"-tris(1-naphthylphenylamino)triphenylamine (J. Lumin., vol. 72-74, p. 985, 1997), an aromatic amine compound consisting of a tetramer of triphenylamine (Chem. Commun., 21 Preferred examples include spiro compounds such as 2,2',7,7'-tetrakis-(diphenylamino)-9,9'-spirobifluorene (Synth. Metals, Vol. 91, p. 209, 1997), and carbazole derivatives such as 4,4'-N,N'-dicarbazolebiphenyl. Other examples include polyvinylcarbazole, polyvinyltriphenylamine (JP-A-7-53953), and polyarylene ether sulfone containing tetraphenylbenzidine (Polym. Adv. Tech., Vol. 7, p. 33, 1996).

[0302] (Formation of hole transport layer by wet film formation method) When the hole transport layer is formed by a wet film formation method, it is usually formed using a composition for forming a hole transport layer instead of the composition for forming a hole injection layer, in the same manner as when the hole injection layer described above is formed by a wet film formation method.

[0303] When the hole transport layer is formed by a wet film formation method, the composition for forming the hole transport layer usually further contains a solvent. The solvent used in the composition for forming the hole transport layer can be the same as the solvent used in the composition for forming the hole injection layer described above.

[0304] The concentration of the hole transporting compound in the composition for forming a hole transport layer can be set to the same range as the concentration of the hole transporting compound in the composition for forming a hole injection layer.

[0305] The hole transport layer can be formed by a wet film formation method in the same manner as the above-mentioned hole injection layer formation method.

[0306] (Formation of hole transport layer by vacuum deposition method) When forming the hole transport layer by vacuum deposition, it can be formed in the same manner as when forming the hole injection layer by vacuum deposition, except that the hole transport layer-forming composition is used instead of the hole injection layer-forming composition. The film formation conditions, such as the degree of vacuum, deposition rate, and temperature during deposition, can be the same as those for the vacuum deposition of the hole injection layer.

[0307] <Light-emitting layer> The light-emitting layer 5 is a layer that is excited by the recombination of holes injected from the anode 2 and electrons injected from the cathode 7 when an electric field is applied between the pair of electrodes, and thus emits light. The light-emitting layer 5 is a layer formed between the anode 2 and the cathode 7. When a hole injection layer is present on the anode, the light-emitting layer is formed between the hole injection layer and the cathode. When a hole transport layer is present on the anode, the light-emitting layer is formed between the hole transport layer and the cathode. The quantum dot light-emitting device of the present invention preferably has the light-emitting layer of the first embodiment or the light-emitting layer of the second embodiment as the light-emitting layer.

[0308] The thickness of the light-emitting layer 5 is arbitrary as long as it does not significantly impair the effects of the present invention, but a thicker layer is preferable in terms of preventing defects from occurring in the film, and a thinner layer is preferable in terms of facilitating a low driving voltage. Therefore, the thickness of the light-emitting layer 5 is preferably 2 nm or more, more preferably 5 nm or more, and usually preferably 200 nm or less, more preferably 100 nm or less.

[0309] 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 blended to adjust the charge-transporting properties.

[0310] (Formation of light-emitting layer by wet film formation method) The method for forming the light-emitting layer may be a vacuum deposition method or a wet film-forming method, but wet film-forming methods are preferred due to their excellent film-forming properties, and spin coating and ink-jet methods are more preferred. In particular, when a hole injection layer or hole transport layer, which is the layer below the light-emitting layer, is formed using the light-emitting layer-forming composition of the present invention, lamination by the wet film-forming method is easy, so wet film-forming methods are preferably used. When the light-emitting layer is formed by the wet film-forming method, it is usually formed using a light-emitting layer-forming composition prepared by mixing the material to be the light-emitting layer with a soluble solvent (light-emitting layer solvent) instead of the hole injection layer-forming composition, in the same manner as when the hole injection layer is formed by the wet film-forming method described above.

[0311] Examples of the solvent include the ether solvents, ester solvents, aromatic hydrocarbon solvents, and amide solvents mentioned for forming the hole injection layer, as well as alkane solvents, halogenated aromatic hydrocarbon solvents, aliphatic alcohol solvents, alicyclic alcohol solvents, aliphatic ketone solvents, and alicyclic ketone solvents. Specific examples of the solvent are listed below, but are not limited to these as long as the effects of the present invention are not impaired.

[0312] For example, aliphatic ether solvents such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); aromatic ether solvents such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, and diphenyl ether; aromatic ester solvents such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate; toluene, xylene, mesitylene, cyclohexylbenzene, tetralin, 3-isopropylbiphenyl, 1, Examples of suitable solvents include aromatic hydrocarbon solvents such as 2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, cyclohexylbenzene, and methylnaphthalene; amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide; alkane solvents such as n-decane, cyclohexane, ethylcyclohexane, decalin, and bicyclohexane; halogenated aromatic hydrocarbon solvents such as chlorobenzene, dichlorobenzene, and trichlorobenzene; aliphatic alcohol solvents such as butanol and hexanol; alicyclic alcohol solvents such as cyclohexanol and cyclooctanol; aliphatic ketone solvents such as methyl ethyl ketone and dibutyl ketone; and alicyclic ketone solvents such as cyclohexanone, cyclooctanone, and fenchone. Among these, alkane solvents and aromatic hydrocarbon solvents are particularly preferred.

[0313] <Hole-blocking layer> A hole-blocking layer may be provided between the light-emitting layer 5 and the electron-transporting layer 6 described below. 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.

[0314] This hole-blocking layer has the roles of preventing holes migrating from the anode 2 from reaching the cathode 7 and efficiently transporting electrons injected from the cathode 7 toward the light-emitting layer 5. Required physical properties of 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 a high excited triplet level (T1).

[0315] Examples of materials for hole-blocking layers that satisfy these conditions include mixed ligand complexes such as bis(2-methyl-8-quinolinolato)(phenolato)aluminum and bis(2-methyl-8-quinolinolato)(triphenylsilanolato)aluminum; metal complexes such as bis(2-methyl-8-quinolinolato)aluminum-μ-oxo-bis-(2-methyl-8-quinolinolato)aluminum binuclear metal complex; styryl compounds such as distyrylbiphenyl derivatives (JP 11-242996 A); triazole derivatives such as 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (JP 7-41759 A); and phenanthroline derivatives such as bathocuproine (JP 10-79297 A). Furthermore, compounds having at least one pyridine ring substituted at the 2-, 4-, and 6-positions, as described in WO 2005 / 022962, are also preferred as materials for the hole-blocking layer.

[0316] There is no limitation on the method for forming the hole blocking layer, and it can be formed by a wet film forming method, a vapor deposition method, or other methods.

[0317] The thickness of the hole blocking layer is arbitrary as long as it does not significantly impair the effects of the present invention, but is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.

[0318] <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.

[0319] The electron transport layer 6 is formed from a compound capable of efficiently transporting electrons injected from the cathode 7 between electrodes to which an electric field is applied, toward the light-emitting layer 5. The electron transporting compound used in the electron transport layer 6 is required to have a high efficiency of electron injection from the cathode 7, a high electron mobility, and the ability to efficiently transport the injected electrons.

[0320] Specific examples of the electron transporting compound used in the electron transport layer include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo[h]quinoline, oxadiazole derivatives, distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (U.S. Pat. No. 5,645,948), quinoxaline compounds (Japanese Patent Laid-Open No. 6-207169), phenanthroline derivatives (Japanese Patent Laid-Open No. 5-331459), 2-tert-butyl-9,10-N,N'-dicyanoanthraquinone diimine, n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, and n-type zinc selenide.

[0321] The thickness of the electron transport layer 6 is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less.

[0322] The electron transport layer 6 is formed by laminating it on the light-emitting layer or the hole-blocking layer by a wet film-forming method or a vacuum deposition method in the same manner as described above. Usually, the vacuum deposition method is used.

[0323] <Electron injection layer> In order to efficiently inject electrons injected from the cathode 7 into the electron transport layer 6 or the light emitting layer 5, an electron injection layer may be provided between the electron transport layer 6 and the cathode 7.

[0324] To efficiently inject electrons, the material forming the electron injection layer is preferably a metal with a low work function. Examples include alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium. The thickness of the electron injection layer is usually preferably 0.1 nm or more and 5 nm or less.

[0325] Furthermore, doping an organic electron transport material, typically a nitrogen-containing heterocyclic compound such as bathophenanthroline or a metal complex such as an aluminum complex of 8-hydroxyquinoline, with an alkali metal such as sodium, potassium, cesium, lithium, or rubidium (as described in JP-A Nos. 10-270171, 2002-100478, and 2002-100482, for example) is also preferred, as it improves both the electron injection and transport properties and enables excellent film quality to be achieved.

[0326] The 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.

[0327] The electron injection layer is formed by laminating it on the light-emitting layer 5 or the hole blocking layer or 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.

[0328] In some cases, the hole blocking layer, electron transporting layer, and electron injecting layer are formed into one layer by co-doping the electron transporting material with a lithium complex.

[0329] <Cathode> The cathode 7 serves to inject electrons into the layer on the light-emitting layer 5 side (such as the electron injection layer or the light-emitting layer).

[0330] The cathode 7 can be made of any of the materials used for the anode 2, but for efficient electron injection, it is preferable to use a metal with a low work function, such as tin, magnesium, indium, calcium, aluminum, silver, or an alloy thereof. Specific examples include low-work-function alloy electrodes such as a magnesium-silver alloy, a magnesium-indium alloy, or an aluminum-lithium alloy.

[0331] In terms of the stability of quantum dot light-emitting devices, it is preferable to protect the cathode made of a low-work-function metal by depositing a metal layer on the cathode that has a high work function and is stable against the atmosphere, such as aluminum, silver, copper, nickel, chromium, gold, or platinum.

[0332] The thickness of the cathode is usually the same as that of the anode.

[0333] <Other layers> The quantum dot light-emitting device of the present invention may further include other layers as long as the effects of the present invention are not significantly impaired. That is, any of the above-mentioned layers may be included between the anode and the cathode.

[0334] <Other element configurations> The quantum dot light-emitting device of the present invention may have a structure opposite to that described above, i.e., for example, a cathode, an electron injection layer, an electron transport layer, a hole blocking layer, a light-emitting layer, a hole transport layer, a hole injection layer, and an anode stacked in this order on a substrate.

[0335] When the quantum dot light-emitting element of the present invention is applied to an organic electroluminescent device, it may be used as a single quantum dot light-emitting element, or may be used in a configuration in which multiple quantum dot light-emitting elements are arranged in an array, or may be used in a configuration in which anodes and cathodes are arranged in an XY matrix.

[0336] [Quantum dot display device] The quantum dot display device (quantum dot light-emitting element display device) of the present invention comprises the quantum dot light-emitting element of the present invention. The type and structure of the quantum dot display device of the present invention are not particularly limited, and it can be assembled using the quantum dot light-emitting element of the present invention according to a conventional method.

[0337] For example, the quantum dot display device of the present invention can be formed by replacing the organic light-emitting layer with a light-emitting layer containing quantum dots, with reference to the method described in "Organic EL Display" (Ohmsha, published August 20, 2004, by Tokito Shizuo, Adachi Chinaya, and Murata Hideyuki).

[0338] [Quantum dot lighting] The quantum dot lighting (quantum dot light-emitting element lighting) of the present invention comprises the quantum dot light-emitting element of the present invention. There are no particular limitations on the type or structure of the quantum dot lighting of the present invention, and it can be assembled using the quantum dot light-emitting element of the present invention in accordance with a conventional method. [Example]

[0339] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples, and the present invention can be practiced with any modifications without departing from the gist of the present invention.

[0340] [Example 1] A quantum dot light-emitting device was fabricated in the following manner. A 50-nm-thick indium tin oxide (ITO) transparent conductive film (Geomatec, sputter-deposited) was deposited on a glass substrate and patterned into 2-mm-wide stripes using standard photolithography and hydrochloric acid etching to form the anode. The substrate with the ITO pattern formed was then ultrasonically cleaned with a surfactant solution, rinsed with ultrapure water, ultrasonically cleaned with ultrapure water, and rinsed with ultrapure water again, followed by drying with compressed air and finally cleaning with ultraviolet ozone.

[0341] A composition for forming a hole injection layer was prepared by dissolving 3.0 mass% of a hole transporting polymer compound having a repeating structure of the following formula (P-1) and 0.6 mass% of an electron accepting compound (HI-1) in ethyl benzoate.

[0342] [ka]

[0343] This composition for forming a hole injection layer was spin-coated onto 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, which was used as a hole injection layer.

[0344] Next, a charge transporting polymer compound having the following structural formula (HT-1) was dissolved in 1,3,5-trimethylbenzene to a concentration of 2.0% by mass to prepare a composition for forming a hole transporting layer.

[0345] [ka]

[0346] This composition for forming a hole transport layer was spin-coated in a nitrogen glove box onto the substrate on which the hole injection layer had been coated, and dried on a hot plate in the nitrogen glove box at 230°C for 30 minutes to form a uniform thin film with a thickness of 40 nm, which served as the hole transport layer.

[0347] Next, a toluene solution containing 1.35 mass % of CdZnSeS nanoparticles and 0.15 mass % of a compound having a structure represented by the following formula (H-1) was prepared as a composition for forming an emitting layer. This was spin-coated at 3,000 rpm for 30 seconds in a nitrogen glove box onto the substrate on which the above-mentioned hole transport layer had been coated, and then dried on a hot plate in the nitrogen glove box at 100°C for 10 minutes to form an emitting layer.

[0348] [ka]

[0349] The substrate on which the light-emitting layer had been formed was placed in a vacuum deposition device, and the inside of the device was heated to 2 × 10 -4 The pressure was evacuated until it reached a pressure of 0.1 Pa or less.

[0350] Next, the following structural formula (ET-1) and 8-hydroxyquinolinolatolithium were co-deposited on the light-emitting layer in a thickness ratio of 2:3 by vacuum deposition to form an electron transport layer with a thickness of 45 nm.

[0351] [ka]

[0352] Next, a 2 mm wide striped shadow mask was attached to the substrate as a mask for cathode deposition so that it was perpendicular to the ITO stripes of the anode, and aluminum was heated using a molybdenum boat to form an 80 nm thick aluminum layer, forming the cathode. In this manner, a quantum dot light-emitting device having a light-emitting area measuring 2 mm x 2 mm was obtained.

[0353] [Comparative Example 1] A quantum dot light-emitting device was fabricated in the same manner as in Example 1, except that the light-emitting layer was formed using a toluene solution containing 1.5 mass % CdZnSeS nanoparticles and not containing a compound having a structure represented by formula (H-1).

[0354] [Element evaluation] When the quantum dot light-emitting devices obtained in Example 1 and Comparative Example 1 were driven to emit light, red light was emitted with a peak wavelength of 628 nm and a half-value width of 27 nm. 2 The half-life (LT50) of the luminance was measured when a current was continuously applied at a current density of 1000 kJ / s. Table 1 shows the relative brightness half life of the quantum dot light-emitting device of Example 1 when the brightness half life (LT50) of the quantum dot light-emitting device of Comparative Example 1 is taken as 1. In Table 1, CdZnSeS nanoparticles are referred to as "QDs," and the compound having the structure represented by formula (H-1) is referred to as "H-1."

[0355] [Table 1]

[0356] The results in Table 1 show that the quantum dot light-emitting device of the present invention has improved performance. [Industrial Applicability]

[0357] The present invention can be suitably used in various fields in which quantum dot light-emitting elements are used, such as flat panel displays (for example, for office automation computers and wall-mounted televisions), 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), sign boards, marker lights, etc. [Explanation of symbols]

[0358] 1 board 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 devices

Claims

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: 【Chemistry 1】 (In formula (1), Ar ２１ , Ar 25 , Ar 26 , Ar 30 , Ar 31 and Ar 35 are hydrogen atoms. Any one of Ar 22 , Ar 23 , and Ar 24 , any one of Ar 27 , Ar 28 , and Ar 29 , and any one of Ar 32 , Ar 33 , and Ar 34 are represented by the following formula (1-1A), (1-1B), (1-1C), (1-2A), (1-2B), or (1-2C), and these structures may be substituted with an alkyl group. Any one other than any one of Ar 22 , Ar 23 , and Ar 24 , any one other than any one of Ar 27 , Ar 28 , and Ar 29 , and any one other than any one of Ar 32 , Ar 33 , and Ar 34 are hydrogen atoms. 【Chemistry 2】

2. A method for producing a quantum dot light-emitting device, comprising the step of applying the composition for forming a light-emitting layer of a quantum dot light-emitting device according to claim 1 and drying the composition to form a light-emitting layer.

3. A method for manufacturing a quantum dot display device, comprising the method for manufacturing the quantum dot light-emitting element according to claim 2.

4. A method for manufacturing a quantum dot illumination, comprising the method for manufacturing the quantum dot light-emitting device according to claim 2.

5. an anode, a cathode, and a light-emitting layer provided between the anode and the cathode; The light-emitting layer contains quantum dots and a compound represented by the following formula (1): 【Transformation 3】 (In formula (1), Ar ２１ , Ar 25 , Ar 26 , Ar 30 , Ar 31 and Ar 35 are hydrogen atoms. Any one of Ar 22 , Ar 23 , and Ar 24 , any one of Ar 27 , Ar 28 , and Ar 29 , and any one of Ar 32 , Ar 33 , and Ar 34 are represented by the following formula (1-1A), (1-1B), (1-1C), (1-2A), (1-2B), or (1-2C), and these structures may be substituted with an alkyl group. Any one other than any one of Ar 22 , Ar 23 , and Ar 24 , any one other than any one of Ar 27 , Ar 28 , and Ar 29 , and any one other than any one of Ar 32 , Ar 33 , and Ar 34 are hydrogen atoms. 【Chemistry 4】

6. A quantum dot display device comprising the quantum dot light-emitting device according to claim 5 .

7. Quantum dot lighting, comprising the quantum dot light-emitting device according to claim 5 .

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