Quantum dot, electroluminescent element, and ink composition

Abstract

To provide quantum dots having excellent stability and enabling high luminous efficiency to be obtained when used as a light-emitting material for an electroluminescent element.SOLUTION: The present invention relates to a quantum dot including semiconductor particles surface-treated with a surface treatment agent having a specific 1,3,5-triazine derivative structure.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to quantum dots, and an electroluminescent device and an ink composition using the same. [Background technology]

[0002] Electroluminescence (EL) devices are attracting attention as surface-emitting devices that are lightweight, thin, consume little power, and offer excellent shape flexibility. These devices have many excellent features, such as high-brightness emission, fast response, a wide viewing angle, thinness, lightness, and high resolution, and their application to flat panel displays and lighting is being considered. Quantum dots are attracting attention as one type of electroluminescent device.

[0003] Quantum dots are small nanoscale semiconductor particles that exhibit behavior intermediate between that of atoms or molecules and that of macroscopic solids (bulk forms). Nanoscale materials (semiconductor particles) in which charge carriers and excitons are confined in all three dimensions are called quantum dots. As quantum dot size decreases, their effective band gap increases. As quantum dot size decreases, their absorption and emission shift toward shorter wavelengths, i.e., from red to blue. Furthermore, by controlling the quantum dot composition and size in combination, a wide spectrum from the infrared to ultraviolet range can be obtained. Furthermore, by controlling the size distribution, a spectrum with a narrow half-width and excellent color purity can be obtained. Therefore, taking advantage of these properties, quantum dot-based organic electroluminescent devices using quantum dots composed of semiconductor nanocrystals as the light-emitting material have been proposed in recent years.

[0004] Quantum dots are generally surface-treated with ligands. Many of these ligands have a structure in which an adsorption group is attached to the end of a long-chain alkyl group. While these ligands have the effect of improving the chemical stability of the quantum dot surface, thereby increasing durability, and enhancing dispersibility and dispersion stability in organic solvents and water, they are insulating and do not exhibit sufficient performance when used in electroluminescent devices. For this reason, in recent years, ligands have been designed with the aim of improving the electrical properties of quantum dots, such as charge injection (Patent Documents 1 and 2). However, when used as a light-emitting material in electroluminescent devices, the luminescence efficiency and stability are insufficient, and there are also issues with film-forming properties when used in ink compositions. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-315661 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-214363 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide quantum dots with excellent stability that can provide high luminous efficiency when used as a light-emitting material in an electroluminescent device. Another object of the present invention is to provide an electroluminescent device with high luminous efficiency and little decrease in luminance during long-term operation. Another object of the present invention is to provide an ink composition with high stability, little decrease in fluorescence quantum yield during long-term storage, and excellent film-forming properties. [Means for solving the problem]

[0007] As a result of intensive research conducted by the present inventors to solve the above-mentioned problems, they discovered that by using quantum dots containing semiconductor particles that have been surface-treated with a surface treatment agent having a specific structure, it is possible to improve the properties of electroluminescent elements and also the properties of ink compositions, and thus arrived at the present invention.

[0008] That is, the present invention provides quantum dots containing semiconductor particles that have been surface-treated with a surface treatment agent, wherein the surface treatment agent is represented by the following general formula (1):

[0009] [ka]

[0010] [In general formula (1), R 1 ~R 15 are each independently a hydrogen atom, an optionally substituted monovalent aliphatic hydrocarbon group, an optionally substituted alkoxy group, an optionally substituted aryl group, an optionally substituted aryloxy group, an optionally substituted heteroaryl group, an optionally substituted heteroaryloxy group, an optionally substituted acyl group, an optionally substituted (poly)organosiloxane group, an optionally substituted amino group, a nitro group, a carboxyl group or a sulfanyl group, and R 1 ~R 15 At least one of the groups is a carboxyl group, a sulfanyl group, a group having a carboxyl group, or a group having a sulfanyl group.]

[0011] The present invention also relates to the quantum dots described above, wherein the surface treatment agent further comprises a surface treatment agent represented by the following general formula (2):

[0012] [ka]

[0013] [In general formula (2), R 21 ~R 35are each independently a hydrogen atom, an optionally substituted monovalent aliphatic hydrocarbon group, an optionally substituted alkoxy group, an optionally substituted aryl group, an optionally substituted aryloxy group, an optionally substituted heteroaryl group, an optionally substituted heteroaryloxy group, an optionally substituted acyl group, an optionally substituted (poly)organosiloxane group, an optionally substituted amino group, a nitro group, a carboxyl group or a sulfanyl group, and R 21 ~R 35 At least one of the groups is a carboxyl group, a sulfanyl group, a group having a carboxyl group, or a group having a sulfanyl group.]

[0014] The present invention also provides an electroluminescent device having an anode, a light-emitting layer, and a cathode on a substrate, wherein the light-emitting layer contains the quantum dots.

[0015] The present invention also provides an ink composition containing the quantum dots and a dispersion medium. [Effects of the Invention]

[0016] The present invention makes it possible to provide quantum dots with excellent stability that provide high luminous efficiency when used as a light-emitting material in electroluminescent devices. It also makes it possible to provide electroluminescent devices with high luminous efficiency and little decrease in luminance during long-term operation. Furthermore, it makes it possible to provide an ink composition with high stability, little decrease in fluorescence quantum yield during long-term storage, and excellent film-forming properties. DETAILED DESCRIPTION OF THE INVENTION

[0017] <Quantum dots> The quantum dots of the present invention are characterized in that the semiconductor particles are surface-treated with a surface treatment agent represented by the following general formula (1): BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail.

[0018] <Semiconductor particles> The materials of the semiconductor particles include carbon (C) (amorphous carbon, graphite, graphene, carbon nanotubes, etc.), silicon (Si), germanium (Ge), tin (Sn), and other elements of group IV of the periodic table, phosphorus (P) (black phosphorus), and other elements of group V of the periodic table, selenium (Se), tellurium (Te), and other elements of group VI of the periodic table, tin oxide (IV), boron nitride (BN), boron phosphide (BP), boron arsenide (BAs), aluminum nitride (AlN), aluminum phosphide (AlP), aluminum arsenide (AlAs), and aluminum antimonide (AlSb). ), gallium nitride (GaN), gallium phosphide (GaP), gallium arsenide (GaAs), gallium antimonide (GaSb), indium nitride (InN), indium phosphide (InP), indium arsenide (InAs), indium antimonide (InSb), and other compounds of group III elements and group V elements of the periodic table. Aluminum sulfide (Al2S3), aluminum selenide (Al2Se3), gallium sulfide (Ga2S3), gallium selenide (GaSe, Ga2Se3), gallium telluride (GaTe, Ga2Te3), indium oxide (In2O 3)Compounds of Group III elements of the periodic table and Group VI elements of the periodic table, such as indium sulfide (In2S3, InS), indium selenide (In2Se3), and indium telluride (In2Te3), zinc oxide (ZnO), zinc sulfide (ZnS), zinc selenide (ZnSe), zinc telluride (ZnTe), cadmium oxide (CdO), cadmium sulfide (CdS), cadmium selenide (CdSe), cadmium telluride (CdTe), mercury sulfide (HgS), mercury selenide (HgSe), and mercury telluride (HgTe). Examples of suitable semiconductors include compounds of Group II elements and Group VI elements of the periodic table, such as copper(I) oxide (CuO), compounds of Group I elements and Group VI elements of the periodic table, such as copper(I) chloride (CuCl), copper(I) bromide (CuBr), copper(I) iodide (CuI), silver chloride (AgCl), and silver bromide (AgBr), and chalcopalite-type compound semiconductors of Group I-III-VI2 elements, such as AgInS and CuInS. Two or more of these may be used in combination, if necessary. These semiconductors may contain elements other than the constituent elements. For example, in the case of Group III-V elements, alloys such as InGaP and InGaN may be used. Semiconductor particles doped with rare earth elements or transition metal elements may also be used in the above materials. For example, ZnS:Mn, ZnS:Tb, ZnS:Ce, LaPO4:Ce, etc. can be mentioned.

[0019] Among these, alloys such as silicon (Si), germanium (Ge), gallium nitride (GaN), gallium phosphide (GaP), gallium arsenide (GaAs), indium nitride (InN), indium phosphide (InP), indium arsenide (InAs), gallium selenide (GaSe, Ga2Se3), indium sulfide (In2S3, InS), zinc oxide (ZnO), zinc sulfide (ZnS), zinc selenide (ZnSe), zinc telluride (ZnTe), cadmium oxide (CdO), cadmium sulfide (CdS), cadmium selenide (CdSe), cadmium telluride (CdTe), InGaP, and InGaN are preferably used, and indium phosphide (InP), cadmium selenide (CdSe), zinc sulfide (ZnS), and zinc selenide (ZnSe) are particularly preferably used. It is particularly preferable to use InP for the core and ZnS and / or ZnSe for the shell.

[0020] Furthermore, perovskite crystals can also be suitably used as the material for the semiconductor particles. Perovskite crystals have a composition represented by the following formula (I) and have a three-dimensional crystal structure. Formula (I): AQX3 [In formula (I), A is a monovalent cation of at least one amine compound selected from the group consisting of methylammonium (CH3NH2) and formamidinium (NH2CHNH), or a monovalent cation of at least one alkali metal element selected from the group consisting of rubidium (Rb), cesium (Cs), and franc (Fr); Q is a divalent cation of at least one metal element selected from the group consisting of lead (Pb) and tin (Sn); and X is a monovalent anion of at least one halogen element selected from the group consisting of iodine (I), bromine (Br), and chlorine (Cl)]

[0021] The semiconductor particles preferably have a core-shell structure. Core-shell semiconductor particles have a structure in which a core is covered with a shell made of a material different from the material forming the core. By selecting a semiconductor with a large band gap for the shell, excitons (electron-hole pairs) generated by photoexcitation are confined within the core. As a result, the probability of non-radiative transitions at the particle surface is reduced, improving the quantum yield of light emission and the stability of fluorescent properties. The shell may also have multiple layers. Furthermore, the boundary between the core and shell, or between one shell and another shell, may be clear or may have a gradient structure in which the core is gradually joined by providing a concentration gradient. Furthermore, the shell may cover only a portion of the core, or the entire core.

[0022] The average particle size of the semiconductor particles, including the core and shell, is usually 0.5 nm to 100 nm, preferably 1 to 50 nm, and more preferably 1 to 15 nm.

[0023] The term "average particle size" as used herein refers to the average value obtained by observing semiconductor particles with a transmission electron microscope and measuring their particle sizes. Since the semiconductor particles are accompanied by the ligands described below, a scanning transmission electron microscope equipped with energy dispersive X-ray analysis can be used to identify the semiconductor material portion, and then the particle size can be measured by utilizing the fact that the semiconductor particle portion appears dark in the transmission electron microscope image relative to the ligands described below due to differences in electron density. The shape of the semiconductor particles is not limited to spherical, but may also be rod-like, disc-like, or other shapes. In this specification, the minor axis diameter and major axis diameter of the semiconductor particles are measured, and the average of the minor axis diameter and major axis diameter is defined as the particle size of the semiconductor particles. Furthermore, the particle size of 30 randomly selected semiconductor particles is determined, and the average value obtained by arithmetic averaging is defined as the average particle size of the semiconductor particles.

[0024] <Surface treatment agent> The surface treatment agent (hereinafter sometimes abbreviated as "treatment agent") used in the present invention includes a surface treatment agent represented by general formula (1). 1 ~R 15 The group represented by the following formula will be described.

[0025] Examples of the monovalent aliphatic hydrocarbon group include an alkyl group, a cycloalkyl group, an alkenyl group, and an alkynyl group. The monovalent aliphatic hydrocarbon group is preferably a monovalent aliphatic hydrocarbon group having 1 to 30 carbon atoms. The monovalent aliphatic hydrocarbon group may be linear or branched. Examples of alkyl groups include methyl, ethyl, hexyl, dodecyl, eicosyl, and 2-ethylhexyl groups. Examples of cycloalkyl groups include cyclohexyl and 3-cyclohexylpropyl groups. Examples of alkenyl groups include ethenyl and dodecene groups. Examples of alkynyl groups include prop-2-yn-1- and propargyl groups.

[0026] An alkoxy group is a group in which an alkyl group is bonded to an oxygen atom. For convenience, in this specification, a group in which a cycloalkyl group is bonded to an oxygen atom (cycloalkyloxy group) is also considered to be included in the alkoxy group.

[0027] The aryl group is preferably an aryl group having 6 to 20 carbon atoms. Examples of the aryl group include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 1-anthryl group, a 2-anthryl group, a 5-anthryl group, a 1-phenanthryl group, a 9-phenanthryl group, a 1-acenaphthyl group, a 2-azulenyl group, a 1-pyrenyl group, a 2-triphenylyl group, an o-biphenylyl group, an m-biphenylyl group, and a p-biphenylyl group.

[0028] An aryloxy group is a group in which an aryl group is bonded to an oxygen atom.

[0029] The heteroaryl group is a residue obtained by formally removing one hydrogen atom from an aromatic heterocycle having 2 to 18 carbon atoms, and is preferably an aryl group. Examples of the heteroaryl group include a triazolyl group, a 3-oxadiazolyl group, a 2-furanyl group, a 3-furanyl group, a 2-furyl group, a 3-furyl group, a 2-thienyl group, a 3-thienyl group, a 1-pyrrolyl group, a 2-pyrrolyl group, a 3-pyrrolyl group, a 2-pyridyl group, a 3-pyridyl group, a 4-pyridyl group, a 2-pyridyl group, a 2-pyrimidyl group, a 4-pyrimidyl group, a 2-oxazolyl group, a 3-isoxazolyl group, a 2-thiazolyl group, a 3-isothiazolyl group, a 2-imidazolyl group, a 3-pyrazolyl ... Examples of the aryl group include a 4-pyrazolyl group, a 5-pyrazolyl group, a 2-quinolyl group, a 3-quinolyl group, a 4-quinolyl group, a 5-quinolyl group, a 6-quinolyl group, a 7-quinolyl group, an 8-quinolyl group, a 1-isoquinolyl group, a 2-quinoxalinyl group, a 2-benzofuryl group, a 2-benzothienyl group, a 2-benzimidazole group, an N-indolyl group, an N-carbazolyl group, a 3-carbazolyl group, an N-acridinyl group, a 2-thiophenyl group, a 3-thiophenyl group, a bipyridyl group, and a phenanthrolyl group.

[0030] A heteroaryloxy group is a group in which a heteroaryl group is bonded to an oxygen atom.

[0031] An acyl group is a group in which a monovalent aliphatic hydrocarbon group, an aryl group, or a heteroaryl group is bonded via a carbonyl group.

[0032] A (poly)organosiloxane group is a monovalent residue formed by formally removing one hydrogen atom from a (poly)organosiloxane compound. Here, a (poly)organosiloxane compound refers to a compound with a (poly)siloxane bond as the main chain and an organic residue as the side chain. The organic residue in the (poly)organosiloxane compound may be a monovalent aliphatic hydrocarbon group and / or an aryl group. Examples of organosiloxane compounds include pentamethyldisiloxane, heptaethyltrisiloxane, undecamethyltetrasiloxane, trimethylsiloxydimethylsilanol, 1,1,3,3,tetramethyl-1,3-dihydroxydisiloxane, and 1,1,3,3,5,5-hexamethyl-1,5-dihydroxytrisiloxane. The number of repeating siloxane bond units is preferably four or less.

[0033] The amino group which may have a substituent includes an amino group and a substituted amino group. The substituent in the substituted amino group includes a monovalent aliphatic hydrocarbon group, an aryl group, a heteroaryl group, and an acyl group. The monovalent aliphatic hydrocarbon group, an aryl group, a heteroaryl group, and an acyl group which are the substituents in these amino groups may be further substituted with the substituents shown below.

[0034] Furthermore, the monovalent aliphatic hydrocarbon group, alkoxy group, aryl group, aryloxy group, heteroaryl group, heteroaryloxy group, acyl group and substituted amino group in general formula (1) may have a substituent. Examples of the substituent that may be introduced include a halogeno group, a cyano group, a hydroxyl group, a nitro group, an alkoxy group, a monovalent aliphatic hydrocarbon group, an aralkyl group, an aryl group, an aryloxy group, a silyloxy group, a heteroaryloxy group, an acyloxy group, a carbamoyloxy group, an alkoxycarbonyloxy group, an aryloxycarbonyloxy group, an amino group (including an anilino group), an acylamino group, an aminocarbonylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfamoylamino group, an alkyl and arylsulfonylamino group, a sulfanyl group, an alkylthio group, an arylthio group, a heterocyclic thio group, an alkyl and arylsulfinyl group, an alkyl and arylsulfonyl group, an acyl group, an aryloxycarbonyl group, an alkoxycarbonyl group, a carbamoyl group, an imido group, a phosphino group, a phosphinyl group, a phosphinyloxy group, a phosphinylamino group, a silyl group, and a group containing a siloxane bond.

[0035] The optional substituent in the present invention may be a monovalent group formed by bonding the above-mentioned monovalent substituent to a divalent group selected from an alkylene group, an alkenylene group, an arylene group, a heteroarylene group, an ether group, an ester group, a sulfide bond, a carbonyl group, an imino group, etc. The above-mentioned divalent group may be a group in which different divalent groups are bonded to each other.

[0036] Furthermore, examples of the group having a carboxyl group or a sulfanyl group include a monovalent aliphatic hydrocarbon group, an alkoxy group, an aryl group, an aryloxy group, a heteroaryl group, a heteroaryloxy group, an acyl group, and a substituted amino group, each of which has a carboxyl group or a sulfanyl group as a substituent.

[0037] Examples of the monovalent aliphatic hydrocarbon group having a carboxyl group or the aryl group having a carboxyl group include a 2-carboxylethyl group, a 2,2-dicarboxylethyl group, a 2-carboxylethenyl group, a 2-cyano-2-carboxylethenyl group, a 2-trifluoromethyl-2-carboxylethenyl group, and a 2-fluoro-2-carboxylethenyl group.

[0038] Examples of the monovalent aliphatic hydrocarbon group having a sulfanyl group, the aryl group having a sulfanyl group, and the acyl group having a sulfanyl group include a [(3-sulfanylpropanoyl)oxy]ethyl group, a [(2-sulfanylacetyl)oxy]ethyl group, a 4-(sulfanylmethyl)phenyl group, a [(3-sulfanylpropanoyl)oxy]propyl group, a 3-sulfanyl[(3-sulfanylpropanoyl)oxy]ethyl group, and a {[(2-sulfanylethoxy)propanoyl]oxy}ethyl group.

[0039] From the viewpoint of preventing an increase in viscosity or deterioration in film-forming properties due to crosslinking between semiconductor particles, the surface treatment agent represented by general formula (1) preferably has one group having a carboxyl group or a sulfanyl group, which serves as an adsorption site. It is particularly preferred that the surface treatment agent has no group having a sulfanyl group and one group having a carboxyl group.

[0040] In general formula (1), R 3 , R 8 and R 13 It is preferable that at least one of the above is a carboxyl group. In particular, it is preferable that the carboxyl group is bonded to an aryl group or a carbon atom forming a multiple bond.

[0041] In addition, in the general formula (1), R 3 , R 8 and R 13 It is preferable that at least one of R is a group having a carboxyl group. 1 ~R 2 , R 4 ~R7 , R 9 ~R 12 and R 14 ~R 15 is preferably a hydrogen atom. 3 , R 8 and R 13 Among these, the group that does not have a carboxyl group is preferably a hydrogen atom, an optionally substituted monovalent aliphatic hydrocarbon group, an optionally substituted alkoxy group, an optionally substituted aryl group, or an optionally substituted heteroaryl group, and particularly preferably a hydrogen atom.

[0042] Next, the surface treatment agent represented by general formula (2) will be described. In general formula (2), R 21 ~R 35 In the group represented by the formula (I), the monovalent aliphatic hydrocarbon group which may have a substituent, the alkoxy group which may have a substituent, the aryl group which may have a substituent, the aryloxy group which may have a substituent, the heteroaryl group which may have a substituent, the heteroaryloxy group which may have a substituent, the acyl group which may have a substituent, the (poly)organosiloxane group which may have a substituent, the amino group which may have a substituent, the group having a carboxyl group, and the group having a sulfanyl group have the same meanings as the respective groups in general formula (1).

[0043] From the viewpoint of preventing an increase in viscosity or deterioration in film-forming properties due to crosslinking between semiconductor particles, the surface treatment agent of general formula (2) preferably has one group having a carboxyl group or a sulfanyl group, which serves as an adsorption site. It is particularly preferred that the surface treatment agent has no group having a sulfanyl group and one group having a carboxyl group.

[0044] In general formula (2), R 23 , R 28 and R 33 It is preferable that at least one of the above is a carboxyl group. In particular, it is preferable that the carboxyl group is bonded to an aryl group or a carbon atom forming a multiple bond.

[0045] In general formula (2), R 23 , R 28 and R 33 It is preferable that at least one of R is a group having a carboxyl group. 21 ~R 23 , R 24 ~R 27 , R 29 ~R 32 and R 34 ~R 35 is preferably a hydrogen atom. 23 , R 28 and R 33 Among these, the group that does not have a carboxyl group is preferably a hydrogen atom, a monovalent aliphatic hydrocarbon group which may have a substituent, or an alkoxy group which may have a substituent.

[0046] Specific examples of the treating agent are shown below, but are not limited to these. In the structural formulas below, when cis- and trans-geometric isomers exist, the agent may be either the cis- or trans-form, or a mixture of the cis- and trans-form isomers. The same applies to syn-anti geometric isomers.

[0047] [ka]

[0048] [ka]

[0049] [ka]

[0050] [ka]

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054] [ka]

[0055] [ka]

[0056] [ka]

[0057] [ka]

[0058] [ka]

[0059] [ka]

[0060] [ka]

[0061] <Ink composition> The ink composition of the present invention contains the above-mentioned quantum dots and a dispersion medium. The dispersion medium is used to disperse the quantum dots.

[0062] (Dispersed Media) The dispersion medium is not particularly limited, and examples thereof include 1,2,3-trichloropropane, 1,3-butylene glycol, 1,3-butylene glycol diacetate, 1,4-dioxane, 2-heptanone, 2-methyl-1,3-propanediol, 3,5,5-trimethyl-2-cyclohexen-1-one, 3,3,5-trimethylcyclohexanone, ethyl 3-ethoxypropionate, 3-methyl-1,3-butanediol, 3-methoxy-3-methyl-1-butanol, 3-methoxy-3-methylbutyl acetate, 3-methoxybutanol, and 3-methoxymethyl-1,3-propanediol. dibutyl acetate, 4-heptanone, m-xylene, m-diethylbenzene, m-dichlorobenzene, N,N-dimethylacetamide, N,N-dimethylformamide, n-butyl alcohol, n-butylbenzene, n-propyl acetate, N-methylpyrrolidone, toluene, octane, nonane, hexane, o-xylene, o-chlorotoluene, o-diethylbenzene, o-dichlorobenzene, p-chlorotoluene, p-diethylbenzene, sec-butylbenzene, tert-butylbenzene, γ-butyrolactone, water, methanol, ethanol ethanol, isopropyl alcohol, tert-tert-butanol, isobutyl alcohol, isophorone, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monotert-butyl ether, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol monopropyl ether, ethylene glycol monohexyl ether, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, diisobutyl ketone, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether, cyclohexanol, cyclohexanol acetate, cyclohexanone,Examples of the alkyl esters include dipropylene glycol dimethyl ether, dipropylene glycol methyl ether acetate, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monomethyl ether, diacetone alcohol, triacetin, tripropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, propylene glycol diacetate, propylene glycol phenyl ether, propylene glycol monoethyl ether, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether, propylene glycol monopropyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether propionate, benzyl alcohol, methyl isobutyl ketone, methylcyclohexanol, n-amyl acetate, n-butyl acetate, isoamyl acetate, isobutyl acetate, propyl acetate, and dibasic acid esters. These solvents can be used alone or in combination of two or more in any ratio as required.

[0063] The viscosity of the ink composition of the present invention may be adjusted using a dispersion medium, resin, polymerizable monomer, etc. When the ink composition of the present invention is used as an inkjet ink, it is preferable to adjust the viscosity at 25°C to 3 to 50 mPa·s. Furthermore, depending on the physical properties required for the printed matter, resins, crosslinking agents, polymerizable monomers, photosensitive substances, and thermosensitive substances can be added to the ink composition.

[0064] <Electroluminescent device> The quantum dot-containing layer of the present invention can be used as a light-emitting layer in an electroluminescent device. The electroluminescent device has a substrate, a cathode and an anode provided on the substrate, a light-emitting layer between the two electrodes, and a charge transport layer on at least one of the cathode and the anode. Furthermore, due to the nature of the light-emitting device, at least one of the anode and the cathode is transparent.

[0065] A preferred embodiment of the layered structure of the light-emitting element is one in which a hole transport layer, a light-emitting layer, and an electron transport layer are stacked in this order from the anode side. Furthermore, a charge blocking layer or the like may be present between the hole transport layer and the light-emitting layer, or between the light-emitting layer and the electron transport layer. A hole injection layer may be present between the anode and the hole transport layer, and an electron injection layer may be present between the cathode and the electron transport layer. The light-emitting layer may be a single layer, or may be divided into a first light-emitting layer, a second light-emitting layer, a third light-emitting layer, or the like. Furthermore, each layer may be divided into multiple sublayers. Representative element configurations of multilayer electroluminescent devices include: (1) anode / hole injection layer / light-emitting layer / cathode; (2) anode / hole injection layer / hole transport layer / light-emitting layer / cathode; (3) anode / hole injection layer / light-emitting layer / electron injection layer / cathode; (4) anode / hole injection layer / hole transport layer / light-emitting layer / electron injection layer / cathode; (5) anode / hole injection layer / light-emitting layer / hole blocking layer / electron injection layer / cathode; and (6) anode / hole injection layer / hole transport layer / light-emitting layer / hole blocking layer / electron injection layer. Possible device configurations include (6) anode / light-emitting layer / hole-blocking layer / electron injection layer / cathode, (7) anode / light-emitting layer / hole-blocking layer / electron injection layer / cathode, (8) anode / light-emitting layer / electron injection layer / cathode, (9) anode / hole injection layer / hole transport layer / interlayer layer / light-emitting layer / cathode, (10) anode / hole injection layer / interlayer layer / light-emitting layer / electron injection layer / cathode, and (11) anode / hole injection layer / hole transport layer / interlayer layer / light-emitting layer / electron injection layer / cathode.

[0066] The substrate for forming the electroluminescent element can be, for example, a substrate used in known organic EL elements. The substrate can be a resin film or a gas barrier film, and the gas barrier films described in JP-A Nos. 2004-136466, 2004-148566, 2005-246716, and 2005-262529 are also preferably used. The thickness of the substrate is not particularly limited, but is preferably 30 μm to 700 μm, more preferably 40 μm to 200 μm, and even more preferably 50 μm to 150 μm. In either case, the haze is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less, and the total light transmittance is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more.

[0067] <Anode> The anode generally functions as an electrode that supplies holes to an organic or inorganic compound layer. There are no particular limitations on its shape, structure, size, etc., and it can be appropriately selected from known electrode materials depending on the application and purpose of the light-emitting device. As mentioned above, the anode is usually provided as a transparent anode. Transparent anodes are described in detail in "New Developments in Transparent Electrode Films" edited by Yutaka Sawada, published by CMC (1999). When a plastic substrate with low heat resistance is used as the substrate, a transparent anode formed at a low temperature of 150°C or less using ITO, IZO, or IGZO is preferred.

[0068] <Cathode> The cathode is generally sufficient as long as it functions as an electrode that injects electrons into an organic compound or inorganic compound layer, and there are no particular restrictions on the shape, structure, size, etc. of the cathode, and it can be appropriately selected from known electrode materials depending on the use and purpose of the light-emitting device. Examples of materials constituting the cathode include metals, alloys, metal oxides, electrically conductive compounds, and mixtures thereof. Specific examples include Group 2 metals (e.g., Mg, Ca, etc.), gold, silver, lead, aluminum, lithium-aluminum alloys, magnesium-silver alloys, and rare earth metals such as indium and ytterbium. These materials may be used alone, but from the viewpoint of achieving both stability and electron injection properties, two or more of them can be suitably used in combination.

[0069] Among these, materials primarily composed of aluminum are preferred as materials for constituting the cathode. Materials primarily composed of aluminum include aluminum alone and alloys of aluminum with 0.01 to 100 mass% of an alkali metal or Group II metal (e.g., lithium-aluminum alloys, magnesium-aluminum alloys, etc.). Cathode materials are described in detail in JP-A-2-15595 and JP-A-5-121172. A dielectric layer of 0.1 to 5 nm thick, made of a fluoride or oxide of an alkali metal or Group II metal, may be inserted between the cathode and the organic or inorganic compound layer. This dielectric layer can also be considered as a type of electron injection layer.

[0070] The thickness of the cathode can be appropriately selected depending on the material constituting the cathode and cannot be generally specified, but is usually about 10 nm to 5 μm, and preferably 50 nm to 1 μm. The cathode may be transparent or opaque. A transparent cathode can be formed by depositing a thin film of the cathode material to a thickness of 1 to 10 nm and then laminating a transparent conductive material such as ITO, IZO, or IGZO on top.

[0071] <Light-emitting layer> The light-emitting layer is a layer that, upon application of an electric field, receives holes from the anode, hole injection layer, or hole transport layer, and receives electrons from the cathode, electron injection layer, or electron transport layer, providing a site for recombination of holes and electrons to emit light. The light-emitting layer may contain a host material in addition to the quantum dots of the present invention. The light-emitting layer may further contain one or more fluorescent materials, phosphorescent materials, and dopants. The host material is preferably a charge transport material. The host material may be one or more types. For example, a mixture of an electron-transporting host material and a hole-transporting host material may be used. Furthermore, the light-emitting layer may contain a material that does not have charge transport properties and does not emit light. The light-emitting layer may be one layer or two or more layers, and each layer may emit light of a different color.

[0072] Examples of fluorescent materials include benzoxazole derivatives, benzimidazole derivatives, benzothiazole derivatives, styrylbenzene derivatives, polyphenyl derivatives, diphenylbutadiene derivatives, tetraphenylbutadiene derivatives, naphthalimide derivatives, coumarin derivatives, condensed aromatic compounds, perinone derivatives, oxadiazole derivatives, oxazine derivatives, aldazine derivatives, pyridine derivatives, cyclopentadiene derivatives, bisstyrylanthracene derivatives, quinacridone derivatives, pyrrolopyridine derivatives, thiadiazolopyridine derivatives, cyclopentadiene derivatives, styrylamine derivatives, diketopyrrolopyrrole derivatives, aromatic dimethylidine compounds, various metal complexes typified by metal complexes of 8-quinolinol derivatives and metal complexes of pyrromethene derivatives, polymer compounds such as polythiophene, polyphenylene, and polyphenylenevinylene, and compounds such as organosilane derivatives.

[0073] Examples of phosphorescent materials include complexes containing transition metal atoms or lanthanoid atoms. Transition metal atoms are not particularly limited, but preferably include ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, and platinum, and more preferably include rhenium, iridium, and platinum. Lanthanoid atoms include lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Among these lanthanoid atoms, neodymium, europium, and gadolinium are preferred.

[0074] Examples of the ligand for the complex include those described in G. Wilkinson et al., Comprehensive Coordination Chemistry, published by Pergamon Press in 1987; H. Yersin, "Photochemistry and Photophysics of Coordination Compounds," published by Springer-Verlag in 1987; and Akio Yamamoto, "Organometallic Chemistry - Fundamentals and Applications," published by Shokabosha in 1982.

[0075] Examples of the host material contained in the light-emitting layer include those having a carbazole skeleton, a diarylamine skeleton, a pyridine skeleton, a pyrazine skeleton, a triazine skeleton, and an arylsilane skeleton, as well as materials exemplified in the sections on the hole injection layer, the hole transport layer, the electron injection layer, and the electron transport layer described later.

[0076] <Hole injection layer, hole transport layer> The hole injection layer and the hole transport layer are layers having the function of receiving holes from the anode or the anode side and transporting them to the cathode side. As long as they have the above-mentioned function, they may be made of an organic compound or an inorganic compound, a low-molecular-weight compound, a high-molecular-weight compound, or a metal oxide. Specifically, the hole injection layer and the hole transport layer are preferably layers containing low molecular weight compounds such as carbazole derivatives, triphenylamine derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidine compounds, porphyrin compounds, phthalocyanine compounds, and organic silane derivatives; carbon compounds such as carbon and fullerene; inorganic compounds made of metal oxides such as vanadium pentoxide and molybdenum trioxide; and polymer compounds such as polyvinylcarbazole, polypyrrole, and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT-PSS).

[0077] <Electron injection layer, electron transport layer> The electron injection layer and the electron transport layer are layers that receive electrons from the cathode or the cathode side and transport them to the anode side. Specifically, the electron injection layer and the electron transport layer are preferably layers containing triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, fluorenone derivatives, anthraquinodimethane derivatives, anthrone derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, aromatic ring tetracarboxylic acid anhydrides such as naphthalene and perylene, phthalocyanine derivatives, various metal complexes typified by metal complexes of 8-quinolinol derivatives, metal phthalocyanines, metal complexes with benzoxazole or benzothiazole as a ligand, low molecular weight compounds such as organosilane derivatives, metal oxides such as zinc oxide (ZnO) and titanium oxide (TiO), and alkali metal-doped organic or inorganic compounds, and particularly preferably zinc oxide doped with magnesium, ZnMgO.

[0078] <Hole-blocking layer> The hole-blocking layer has the function of preventing holes transported from the anode side to the light-emitting layer from passing through to the cathode side. In the present invention, a hole-blocking layer can be provided as an organic compound layer adjacent to the light-emitting layer on the cathode side. In addition, the electron-transporting layer and the electron-injecting layer may also function as the hole-blocking layer. Examples of organic compounds that can be used to form the hole-blocking layer include aluminum complexes such as BAlq, triazole derivatives, and phenanthroline derivatives such as BCP. A layer that prevents electrons transported from the cathode to the light-emitting layer from passing through to the anode can also be provided adjacent to the light-emitting layer on the anode side. The hole-transporting layer and hole-injecting layer may also perform this function. [Example]

[0079] The present invention will be described in more detail below with reference to examples, but the technical scope of the present invention is not limited by these examples. In the examples, "parts" and "%" represent "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0080] <Production of Quantum Dot-Containing Composition> [Synthesis Example 1] An additive solution was prepared by heating and dissolving 0.55 parts of anhydrous zinc acetate, 7.0 parts of dodecanethiol (treatment agent R1), and 5.0 parts of oleylamine. Separately, 0.22 parts of indium chloride and 8.25 parts of octylamine were placed in a reaction vessel and heated to 165°C while bubbling with nitrogen. After the indium chloride was dissolved, 0.86 parts of diethylaminophosphine was added to the reaction vessel and the mixture was maintained at 165°C for 20 minutes. Thereafter, the liquid temperature was cooled to 40°C. Next, the above additive solution was added to the reaction vessel, heated at 240°C for 2 hours, and then allowed to cool to 25°C. After cooling, the mixture was purified by reprecipitation using hexane and ethanol to obtain quantum dots EX1, which are core-shell semiconductor particles with an InP core and a ZnS shell that have been surface-treated with dodecanethiol. The solids concentration was further adjusted to 10% using mesitylene, yielding a quantum dot EX1-containing composition.

[0081] [Synthesis Example 2] 2.0 mL of oleic acid and 10 mL of 1-octadecene were added to the flask, and the mixture was heated and stirred at 100°C under reduced pressure for 1 hour. Nitrogen was then purged into the flask, and the mixture was heated to 270°C. Once the solution temperature stabilized, 0.2 mL of a 0.3 M tellurium / trioctylphosphine solution (tellurium dissolved in trioctylphosphine) and 0.8 mL of a 0.3 M selenium / trioctylphosphine solution (selenium dissolved in trioctylphosphine) were added to the flask. 0.3 mL of a 1 M diethylzinc n-hexane solution was then added, and the mixture was maintained at 270°C for 30 minutes to synthesize ZnTeSe core semiconductor particles. In a separate flask, 3.0 g of zinc stearate and 15 mL of octadecene were added, heated to 100°C, and dissolved. The mixture was then stirred under vacuum for 1 hour to degas the zinc precursor solution. 10 mL of the zinc stearate solution and 2.4 mL of a 1.25 M selenium / trioctylphosphine solution prepared in a separate flask were simultaneously added to the flask in which the core semiconductor particles had been synthesized, and the reaction solution was stirred for 30 minutes. Next, 4.0 mL of trioctylphosphine was added to 0.16 g of sulfur and heated to 150 °C to dissolve the sulfur / trioctylphosphine solution, preparing a 1.25 M sulfur / trioctylphosphine solution. 1.0 mL of this solution was added to the reaction solution and stirred for 1 hour. Next, 0.22 g of zinc acetate was added to the reaction solution and dissolved by heating to 100 °C under reduced pressure. The flask was again purged with nitrogen, and the temperature was raised to 230 °C. 0.48 mL of dodecanethiol was added and the mixture was maintained for 1 hour. The resulting reaction solution was cooled to 25 °C. After cooling, the solution was purified by reprecipitation using toluene and ethanol to obtain quantum dots EX2, which consisted of core-shell semiconductor particles with a ZnTeSe core and a ZnSe / ZnS bilayer shell surface-treated with dodecanethiol. The solids concentration was further adjusted to 10% using mesitylene to obtain a quantum dot EX2-containing composition.

[0082] [Synthesis Example 3] A flask was charged with 0.033 g of silver(I) acetate, 0.058 g (0.20 mmol) of indium acetate, 0.65 mL of 1-dodecanethiol, and 4.0 mL of oleylamine. The mixture was heated and stirred under reduced pressure at 100°C for 1 hour, followed by degassing. Nitrogen was then purged into the flask, and the mixture was heated to 200°C and held there for 20 minutes. The flask was then heated to 230°C, after which 1.0 mL of a 1.25 M sulfur / trioctylphosphine solution was prepared and added to the reaction solution. The mixture was then stirred for 1 hour. Finally, 0.066 g of zinc acetate, 0.24 mL of oleic acid, and 0.15 mL of oleylamine were added to the flask, and the mixture was heated and stirred at 230°C for 1 hour. The resulting solution was cooled to 25°C. After cooling, the mixture was purified by reprecipitation using toluene and ethanol to obtain core-shell semiconductor particles with AgInS2 cores and ZnS shells, surface-treated with dodecanethiol. Quantum dots EX3 were obtained. Further, mesitylene was used to adjust the solid concentration to 10%, thereby obtaining a composition containing quantum dots EX3.

[0083] [Example 1] (Quantum dots and ink compositions) The quantum dot EX1-containing composition obtained in Synthesis Example 1 was diluted with toluene to a solids concentration of 1%. The same amount of a 5% toluene solution of Treatment Agent 1 (Table 1) was added and stirred for 12 hours. Purification was performed by reprecipitation using toluene and ethanol. Mesitylene was used to adjust the solids concentration to 10% to obtain Ink Composition 1, which contained quantum dots in which core-shell semiconductor particles with an InP core and a ZnS shell were surface-treated with Treatment Agent 1. The average particle size of the quantum dots separated from Ink Composition 1 was measured. Using a scanning transmission electron microscope equipped with energy dispersive X-ray analysis, the semiconductor particle region was identified, and the particle size of the semiconductor particles was measured, taking advantage of the fact that the semiconductor particle region appears dark in transmission electron microscope images relative to the surface treatment agent due to differences in electron density. Specifically, the minor and major axis diameters of the semiconductor particles were measured, and the average of the minor and major axis diameters was used as the particle size of the semiconductor particles. The average value was calculated for 30 randomly selected semiconductor particles to determine the average particle size of the semiconductor particles. The average particle size of the semiconductor particles contained in the quantum dots EX1 was 13 nm.

[0084] [Examples 2 to 34, Comparative Examples 1 and 2] Ink compositions 2 to 34 and R1 to R2 containing quantum dots in which core-shell semiconductor particles having an InP core and a ZnS shell were surface-treated with a treating agent were obtained in the same manner as in Example 1, except that treating agent 1 was changed to treating agents 2 to 34 and R1 to R2 shown in Tables 1 to 10. Ink compositions 2 to 34 are ink compositions of the present invention, and ink compositions R1 to R2 are ink compositions not of the present invention.

[0085] [Example 35] The quantum dot EX1-containing composition obtained in Synthesis Example 1 was diluted with toluene to a solids concentration of 1%. An equal amount of a 2.5% toluene mixed solution of Treatment Agent 2 and Treatment Agent 35 (shown in Table 11) at a concentration of 2.5% was added, and the mixture was stirred for 12 hours. Purification was carried out by reprecipitation using toluene and ethanol. The solids concentration was adjusted to 10% using mesitylene, and ink composition 35 containing quantum dots was obtained, in which core-shell semiconductor particles with an InP core and a ZnS shell were surface-treated with Treatment Agent 2 and Treatment Agent 35.

[0086] [Examples 36 to 38] Ink compositions 36 to 38 were obtained in the same manner as in Example 35, except that treating agent 35 was changed to treating agents 36 to 38 shown in Table 11, respectively.

[0087] [Comparative Example 3] Ink composition R3 with a solids concentration of 10% was obtained in the same manner as in Example 35, except that treating agent 2 was changed to treating agent R2 shown in Table 10 and treating agent 35 was changed to treating agent R1 shown in Table 10. The ink composition R3 contained quantum dots in which core-shell semiconductor particles having an InP core and a ZnS shell were surface-treated with treating agent R2 and treating agent R1.

[0088] [Example 39] Ink composition 39 was obtained in the same manner as in Example 1, except that the quantum dot EX1-containing composition obtained in Synthesis Example 1 was replaced with the quantum dot EX2-containing composition obtained in Synthesis Example 2, and treatment agent 1 was replaced with treatment agent 2, thereby obtaining ink composition 39 containing quantum dots in which core-shell type semiconductor particles having a core of ZnTeSe and a two-layered ZnSe / ZnS shell were surface-treated with treatment agent 2.

[0089] [Example 40] Ink composition 40 containing quantum dots in which core-shell type semiconductor particles having a core of AgInS2 and a shell of ZnS were surface-treated with treating agent 2 was obtained in the same manner as in Example 1, except that the quantum dot EX1-containing composition obtained in Synthesis Example 1 was replaced with the quantum dot EX3-containing composition obtained in Synthesis Example 3 and treating agent 1 was replaced with treating agent 2.

[0090] [Example 41] Ink composition 41 with a solids concentration of 10% was obtained in the same manner as in Example 35, except that treating agent 35 was changed to treating agent R1 shown in Table 10, and contained quantum dots in which core-shell semiconductor particles having an InP core and a ZnS shell were surface-treated with treating agent 2 and treating agent R1.

[0091] [Table 1]

[0092] [Table 2]

[0093] [Table 3]

[0094] [Table 4]

[0095] [Table 5]

[0096] [Table 6]

[0097] [Table 7]

[0098] [Table 8]

[0099] [Table 9]

[0100] [Table 10]

[0101] [Table 11]

[0102] (Ink stability evaluation) The fluorescence quantum yield stability over time was evaluated for ink compositions 1 to 28 and R1 to R3 obtained in the examples and comparative examples. A quantum efficiency measurement system QE-2000 manufactured by Otsuka Electronics Co., Ltd. was used to measure the fluorescence quantum yield. The fluorescence quantum yield after completion of synthesis was set to 1, and the fluorescence quantum yield after storage in a sealed state in the atmosphere for 100 hours was used as an index of ink stability. The results are shown in Table 12. The criteria are as follows: A+: 1.0 or less, 0.80 or more A: Less than 0.80, 0.75 or more B+: Less than 0.75, 0.70 or more B: Less than 0.70, 0.65 or more C+: Less than 0.65, 0.60 or more C: Less than 0.60, 0.55 or more D+: Less than 0.55, 0.50 or more D: Less than 0.50

[0103] (Evaluation of ink film forming properties) Film-forming properties of ink compositions 1 to 28 and R1 to R3 obtained in the examples and comparative examples were evaluated. A film was formed by spin-coating the ink composition onto a glass substrate that had been cleaned with an electronics industry detergent and a solvent and then treated with UV ozone, followed by heat treatment on a hot plate at 80°C. The arithmetic mean roughness (Ra) (nm) of the formed film was determined according to the method specified in Japanese Industrial Standards (JIS) R1683:2014 and evaluated according to the following criteria. The results are shown in Table 12. The criteria are as follows: A: 0 or more, 3.0 or less B: More than 3.0, less than 5.0 C: over 5.0, under 10.0 D: Exceeding 10.0

[0104] (Evaluation of electroluminescent devices) The electroluminescent device performance of ink compositions 1 to 28 and R1 to R3 obtained in the examples and comparative examples was evaluated. -6 The experiment was carried out in a vacuum of Torr without temperature control such as heating or cooling of the substrate. The light-emitting characteristics of the device were measured using an electroluminescent device with a light-emitting device area of ​​2 mm x 2 mm.

[0105] A 20-nm thick hole-injection layer was formed on a cleaned glass plate with an ITO electrode by spin coating using an ethanol dispersion of molybdenum oxide nanoparticles (purchased from Sigma-Aldrich, concentration: 2.3-2.7% by mass). The substrate was then dried at 150°C for 20 minutes to form a hole-injection layer. Poly(N-vinylcarbazole) was then dissolved in monochlorobenzene at a concentration of 1.0% by mass, spin coated, and dried at 110°C for 20 minutes to form a 35-nm thick hole-transport layer. The ink compositions of the present invention obtained in the Examples and Comparative Examples were diluted 20-fold with mesitylene, spin coated, and dried for 5 minutes at 25°C in a nitrogen atmosphere to form a 25-nm thick light-emitting layer. An isopropanol dispersion of zinc oxide nanoparticles N-10 (available from Avantama) was then spin coated on the substrate and dried for 20 minutes on a hot plate at 80°C to form an 80-nm thick electron-transport layer. Finally, aluminum (Al) was deposited to a thickness of 200 nm to form electrodes, and an electroluminescent device was obtained. The resulting device was subjected to a current density test of 10 mA / cm 2 The luminous efficiency (cd / A) when driven at 6 V and the relative luminance (= (luminance after 100 hours) / (initial luminance)) after 100 hours of continuous driving were measured. The results are shown in Table 12. When the ink composition of Example 1 was used, the external quantum efficiency was 4.8% and the luminous luminance was 28,000 (cd / m) at 6 V. 2 The peak wavelength of the emission spectrum was 622 nm, and the full width at half maximum was 26 nm. The evaluation criteria for the luminous efficiency (cd / A) and the relative brightness after 100 hours of continuous operation are as follows:

[0106] Luminous efficacy (cd / A) A+: 5.5 or above A: Less than 5.5, 5.0 or more B+: Less than 5.0, 4.5 or more B: Less than 4.5, 4.0 or more C+: Less than 4.0, 3.5 or above C: Less than 3.5, 3.0 or more D+: Less than 3.0, 2.0 or more D: Less than 2.0

[0107] Relative luminance A+: 1.0 or less, 0.60 or more A: Less than 0.60, 0.65 or more B+: Less than 0.65, 0.60 or more B: Less than 0.60, 0.55 or more C+: Less than 0.55, 0.50 or more C: Less than 0.50, 0.45 or more D+: Less than 0.45, 0.30 or more D: Less than 0.30

[0108] [Table 12]

Claims

1. Quantum dots containing semiconductor particles surface-treated with a surface treatment agent, the surface treatment agent comprising a surface treatment agent represented by the following general formula (1): 【Chemistry 1】 [In general formula (1), R 1 ~R 15 are each independently a hydrogen atom, an optionally substituted monovalent aliphatic hydrocarbon group, an optionally substituted alkoxy group, an optionally substituted aryl group, an optionally substituted aryloxy group, an optionally substituted heteroaryl group, an optionally substituted heteroaryloxy group, an optionally substituted acyl group, an optionally substituted (poly)organosiloxane group, an optionally substituted amino group, a nitro group, a carboxyl group or a sulfanyl group, and R 1 ~R 15 At least one of these is a carboxyl group, a sulfanyl group, a group having a carboxyl group, or a group having a sulfanyl group.]

2. The quantum dot according to claim 1, wherein the surface treatment agent further comprises a surface treatment agent represented by the following general formula (2): 【Chemistry 2】 [In general formula (2), R 21 ~R 35 are each independently a hydrogen atom, an optionally substituted monovalent aliphatic hydrocarbon group, an optionally substituted alkoxy group, an optionally substituted aryl group, an optionally substituted aryloxy group, an optionally substituted heteroaryl group, an optionally substituted heteroaryloxy group, an optionally substituted acyl group, an optionally substituted (poly)organosiloxane group, an optionally substituted amino group, a nitro group, a carboxyl group or a sulfanyl group, and R 21 ~R 35 At least one of these is a carboxyl group, a sulfanyl group, a group having a carboxyl group, or a group having a sulfanyl group.]

3. 3. An electroluminescent device having an anode, a light-emitting layer, and a cathode on a substrate, wherein the light-emitting layer contains the quantum dots according to claim 1.

4. An ink composition comprising the quantum dots according to claim 1 or 2 and a dispersion medium.

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