Ink composition

Abstract

This technology provides a way to achieve both process stability in the manufacturing of quantum dot electroluminescent devices and the performance of the quantum dot electroluminescent devices (particularly luminescence characteristics and device lifetime). [Solution] An ink composition comprising quantum dots, a reactive organic compound, and a solvent, The quantum dots do not contain cadmium (Cd) or lead (Pb), the average particle size of the quantum dots is between 1 nm and 15 nm, and the content of the quantum dots is between 0.1% and 10.0% by mass, based on 100% by mass of the total mass of the ink composition. The reactive organic compound is a compound represented by formula (1) as described in the specification, and the content of the reactive organic compound is 0.1% by mass or more and 10.0% by mass or less, with the mass of the quantum dots in the ink composition being 100% by mass. The solvent is an ink composition comprising at least one compound selected from the compounds represented by formulas (2) to (5) described in the specification.

Description

[Technical Field]

[0001] This invention relates to an ink composition. [Background technology]

[0002] In recent years, quantum dots have attracted attention as sharp RGB light sources that cover a wide color gamut, and electroluminescent devices (hereinafter also referred to as quantum dot electroluminescent elements) that use quantum dots as the light-emitting layer are being actively researched and developed as thin-film, lightweight, and low-power display and lighting elements.

[0003] In realizing quantum dot electroluminescent devices, it is crucial to laminate a quantum dot light-emitting layer between the anode and cathode as a thin film with a thickness of several nanometers to several hundred nanometers, and to achieve precise interface formation with surrounding layers such as hole transport layers and electron transport layers. Typically, the quantum dot light-emitting layer is formed by coating methods such as spin coating and inkjet. Development of ink compositions containing quantum dots used in the manufacture of such quantum dot electroluminescent devices is progressing (see Patent Documents 1-8). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Chinese Patent Application Publication No. 109306207 Specification [Patent Document 2] International Publication No. 2019 / 225782 [Patent Document 3] Japanese Patent Publication No. 2019-81868 [Patent Document 4] Japanese Patent Publication No. 2020-41079 [Patent Document 5] U.S. Patent Application Publication No. 2018 / 0230321 [Patent Document 6] Japanese Patent Publication No. 2017-043526 [Patent Document 7] Chinese Patent No. 107400414 Specification [Patent Document 8] Chinese Patent Application Publication No. 105907180 Specification [Overview of the project] [Problems that the invention aims to solve]

[0005] In the lamination process using coating methods, it is necessary to suppress the dissolution of the quantum dot emissive layer by the solvent when forming the upper layer of the quantum dot emissive layer. This is because dissolution of the quantum dot emissive layer disrupts the interface between the upper layer and the quantum dot emissive layer, which is one of the causes of decreased luminous efficiency and device lifespan.

[0006] In lamination processes using coating methods, attempts have been made to bridge quantum dots to suppress the dissolution of the quantum dot luminescence layer in the solvent (process stability). However, this has not led to a fundamental solution because it can sacrifice the performance of the quantum dot electroluminescent device (e.g., luminescence characteristics and device lifetime).

[0007] Therefore, the present invention has been made in view of the above circumstances, and aims to provide a technology that can achieve both process stability in the manufacturing of quantum dot electroluminescent elements and performance of quantum dot electroluminescent elements (particularly light emission characteristics and element lifetime). [Means for solving the problem]

[0008] The above-mentioned problems of the present invention can be solved by the following means.

[0009] In other words, the present invention relates to an ink composition comprising quantum dots, a reactive organic compound, and a solvent. The quantum dots do not contain cadmium (Cd) or lead (Pb), the average particle size of the quantum dots is between 1 nm and 15 nm, and the content of the quantum dots is between 0.1% and 10.0% by mass, based on 100% by mass of the total mass of the ink composition. The reactive organic compound is a compound represented by the following formula (1),

[0010] [Chemical formula]

[0011] In the above formula (1), Ar1 is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms, L1 is a single bond or an oxygen atom, L2 is a single bond, or a substituted or unsubstituted saturated hydrocarbon group having 1 to 60 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms, X is a group selected from the group consisting of the following formulas (1-1) to (1-37),

[0012] [Chemical formula]

[0013] [Chemical formula]

[0014] In the above formulas (1-1) to (1-37), * represents a bonding site, In the above formulas (1-1) to (1-5), (1-7), (1-12), (1-19), (1-22), (1-23), (1-27), and (1-28), a1 each independently represents an integer of 2 or more and 4 or less, In the above formulas (1-6), (1-8), (1-9), (1-13) to (1-15), (1-20), (1-25), and (1-30), a2 each independently represents an integer of 1 or more and 3 or less, a3 each independently represents 1 or 2, and the sum of a2 and a3 each independently is 2, 3, or 4, In the above equations (1-10), (1-16), (1-17), (1-21), (1-26), and (1-31), a4 independently represents either 1 or 2, a5 independently represents 1, a6 independently represents either 1 or 2, and the sum of a4, a5, and a6 independently represents either 3 or 4. In equations (1-24) and (1-29) above, a7 independently represents an integer between 1 and 3, a8 independently represents an integer between 1 and 3, and the sum of a7 and a8 is independently 2, 3, or 4. In the above equation (1-32), a9 is an integer between 2 and 18, In the above formula (1-37), a 10 is 1 or 2, and a 11 It represents 1 or 2, In the above formulas (1-5) and (1-6), Ar2 is independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms. In the above formulas (1-27) to (1-31), Y is independently -O-, -S-, -C(CH3)2-, or a diphenylmethylene group. The content of the reactive organic compound is 0.1% by mass or more and 10.0% by mass or less, with the mass of the quantum dots in the ink composition being 100% by mass. The solvent comprises at least one compound selected from those represented by the following formulas (2) to (5):

[0015] [ka]

[0016] In formula (2) above, R1 is a linear or branched saturated hydrocarbon group having 1 to 18 carbon atoms or a cyclic saturated hydrocarbon group having 3 to 12 carbon atoms, and b represents an integer between 1 and 3.

[0017] [ka]

[0018] In the above formula (3), R2 is a linear or branched saturated hydrocarbon group having 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon group having 3 to 12 carbon atoms.

[0019] [ka]

[0020] In the above equation (4), c represents an integer between 6 and 18,

[0021] [ka]

[0022] In formula (5) above, Z is -OH, -COOH, -NH2, or -SH, and d is an integer between 7 and 17, representing the ink composition. [Effects of the Invention]

[0023] According to the present invention, it is possible to achieve both process stability in the manufacturing of quantum dot electroluminescent elements and performance of the quantum dot electroluminescent elements (particularly light emission characteristics and element lifetime). [Brief explanation of the drawing]

[0024] [Figure 1] This is a schematic cross-sectional view showing a quantum dot electroluminescent device according to one embodiment of the present invention. [Modes for carrying out the invention]

[0025] Embodiments of the present invention will be described below. However, the present invention is not limited to the embodiments described below. Unless otherwise specified, operations and measurements of physical properties will be performed under conditions of room temperature (20°C to 25°C) and relative humidity of 40%RH to 50%RH.

[0026] [Ink composition] One embodiment of the present invention is an ink composition comprising quantum dots, a reactive organic compound, and a solvent. The quantum dots do not contain cadmium (Cd) or lead (Pb), the average particle size of the quantum dots is between 1 nm and 15 nm, and the content of the quantum dots is between 0.1% and 10.0% by mass, based on 100% by mass of the total mass of the ink composition. The reactive organic compound is a compound represented by the following formula (1):

[0027] [ka]

[0028] In the above formula (1), Ar1 is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms. L1 is a single bond or an oxygen atom. L2 is a single bond, or a saturated hydrocarbon group having 1 to 60 carbon atoms, either substituted or unsubstituted, or an aromatic hydrocarbon group having 6 to 60 carbon atoms, X is a group selected from the group consisting of the following equations (1-1) to (1-37),

[0029] [ka]

[0030] [ka]

[0031] In the above formulas (1-1) to (1-37), * represents a bonding site. In the above equations (1-1) to (1-5), (1-7), (1-12), (1-19), (1-22), (1-23), (1-27), and (1-28), a1 independently represents an integer between 2 and 4, In the above equations (1-6), (1-8), (1-9), (1-13)~(1-15), (1-20), (1-25), and (1-30), a2 independently represents an integer between 1 and 3 (inclusive), a3 independently represents either 1 or 2, and the sum of a2 and a3 is independently 2, 3, or 4. In the above equations (1-10), (1-16), (1-17), (1-21), (1-26), and (1-31), a4 independently represents either 1 or 2, a5 independently represents 1, a6 independently represents either 1 or 2, and the sum of a4, a5, and a6 independently represents either 3 or 4. In equations (1-24) and (1-29) above, a7 independently represents an integer between 1 and 3, a8 independently represents an integer between 1 and 3, and the sum of a7 and a8 is independently 2, 3, or 4. In the above equation (1-32), a9 is an integer between 2 and 18, In the above formula (1-37), a 10 is 1 or 2, and a 11 It represents 1 or 2, In the above formulas (1-5) and (1-6), Ar2 is independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms. In the above formulas (1-27) to (1-31), Y is independently -O-, -S-, -C(CH3)2-, or a diphenylmethylene group. The content of the reactive organic compound is 0.1% by mass or more and 10.0% by mass or less, with the mass of the quantum dots in the ink composition being 100% by mass. The solvent comprises at least one compound selected from those represented by the following formulas (2) to (5):

[0032] [ka]

[0033] In formula (2) above, R1 is a linear or branched saturated hydrocarbon group having 1 to 18 carbon atoms or a cyclic saturated hydrocarbon group having 3 to 12 carbon atoms, and b represents an integer between 1 and 3.

[0034] [ka]

[0035] In the above formula (3), R2 is a linear or branched saturated hydrocarbon group having 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon group having 3 to 12 carbon atoms.

[0036] [ka]

[0037] In the above equation (4), c represents an integer between 6 and 18,

[0038] [ka]

[0039] In formula (5) above, Z is -OH, -COOH, -NH2, or -SH, and d is an integer between 7 and 17, representing the ink composition.

[0040] Having the above-described configuration, the ink composition according to the present invention can achieve both process stability in the manufacturing of quantum dot electroluminescent elements and performance of the quantum dot electroluminescent elements (particularly luminescence characteristics and element lifetime).

[0041] The inventors hypothesize the following mechanism by which the ink composition (quantum dot ink composition) according to the present invention solves the above problems.

[0042] When fabricating quantum dot electroluminescent devices using a wet coating method, particularly an inkjet method, the device is fabricated by repeatedly applying a liquid and drying it. Since a different layer is formed on top of a dry film containing quantum dots (quantum dot layer), when a liquid containing a solvent is applied, the solvent penetrates the quantum dot layer, causing dissolution of the quantum dot layer and potentially resulting in a phenomenon called intermixing, where the upper layer and the quantum dot layer mix. Intermixing leads to a deterioration of the device's characteristics. Therefore, it is thought that intermixing can be suppressed by strengthening the quantum dot layer. The inventors of this invention hypothesized that by using a compound that can crosslink quantum dots, the quantum dot layer could be strengthened and intermixing could be suppressed. However, when a compound having an azide group (-N3) (for example, J. Yang, et al, Nat. Commun., 11 (2020) 2874.) is used to crosslink quantum dots, an amine is included in the structure after crosslinking, resulting in the retention of active protons. The inventors have found that the residual active protons degrade the characteristics of the device. On the other hand, by using a reactive organic compound having a diazo group (=N2), the structure after crosslinking does not contain amines, and no active protons remain. As a result, the degradation of the quantum dot electroluminescent device due to the presence of active protons can be suppressed, and therefore, the ink composition according to the present invention is considered to be able to achieve both process stability in the manufacture of quantum dot electroluminescent devices and performance of the quantum dot electroluminescent device (particularly luminescence characteristics and device lifetime).

[0043] The above mechanism is speculative, and the present invention is not bound in any way by the above mechanism.

[0044] The composition of the ink composition according to the present invention will be described in detail below.

[0045] (Quantum dots) The ink composition according to the present invention contains quantum dots. The quantum dots (semiconductor nanoparticles) are semiconductor nanoparticles of a predetermined size that exhibit quantum constraint effects.

[0046] Quantum dots (semiconductor nanoparticles) can be synthesized by wet chemical processes, organometallic vapor deposition processes, molecular beam epitaxy processes, or other similar processes. Among these, wet chemical processes involve growing particles by adding precursor substances to an organic solvent.

[0047] In wet chemical processes, as crystals grow, organic solvents naturally coordinate to the surface of quantum dot crystals, acting as dispersants and regulating crystal growth. Therefore, wet chemical processes allow for easier and lower-cost control of semiconductor nanoparticle growth compared to vapor deposition methods such as metal-organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE).

[0048] Quantum dots (semiconductor nanoparticles) can have their energy bandgap adjusted by controlling their size, allowing them to produce light in a variety of wavelengths in their light-emitting layer (quantum dot light-emitting layer). Therefore, using multiple quantum dots of different sizes enables displays that emit (or emit) light of multiple wavelengths. The size of the quantum dots can be selected to emit red, green, and blue light, allowing for the construction of color displays. Alternatively, the sizes of the quantum dots can be combined to emit white light from a variety of colors.

[0049] Quantum dots do not contain cadmium (Cd) or lead (Pb). Quantum dots can be made from semiconductor materials selected from the group consisting of group II-VI semiconductor compounds, group III-V semiconductor compounds, group IV-VI semiconductor compounds, group IV elements or compounds, and combinations thereof.

[0050] The group II-VI semiconductor compounds are not particularly limited, but include, for example, two-element compounds selected from the group consisting of ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, and mixtures thereof; three-element compounds selected from the group consisting of ZnSeS, ZnTeSe, ZnSTe, HgSeS, HgSeTe, HgSTe, HgZnS, HgZnSe, HgZnTe, and mixtures thereof; and four-element compounds selected from the group consisting of HgZnSeS, HgZnSeTe, HgZnSTe, and mixtures thereof.

[0051] III-V semiconductor compounds are not particularly limited, but include, for example, two-element compounds selected from the group consisting of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, and mixtures thereof; three-element compounds selected from the group consisting of GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, and mixtures thereof; and four-element compounds selected from the group consisting of GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, and mixtures thereof.

[0052] The IV-VI semiconductor compounds are not particularly limited, but can be selected from, for example, the group consisting of SnS, SnSe, SnTe, and mixtures thereof; or from the group consisting of three elements selected from the group consisting of SnSeS, SnSeTe, SnSTe, and mixtures thereof.

[0053] The Group IV elements or compounds are not particularly limited, but include, for example, mono-element compounds selected from the group consisting of Si, Ge, and mixtures thereof; and di-element compounds selected from the group consisting of SiC, SiGe, and mixtures thereof.

[0054] A quantum dot may consist of one compound or two or more compounds. It may also have a core-shell structure, for example, comprising a core made of a semiconductor compound and a shell made of a different semiconductor compound. The luminescence efficiency of the quantum dot can be increased by using a semiconductor compound with a higher band gap than the core-forming semiconductor compound as the semiconductor compound constituting the shell, so that excitons are confined to the core. Examples of core-shell structures (core / shell) with such band gap relationships include InP / ZnS, CuInS / ZnS, ZnTeSe / ZnSe / ZnS, and InP / ZnSe / ZnS.

[0055] The average particle size (average diameter) of quantum dots is between 1 nm and 15 nm. Preferably, the average particle size (average diameter) of quantum dots is between 7 nm and 15 nm from the viewpoint of luminescence characteristics and dispersion stability of quantum dots. In this specification, the average particle size of quantum dots is calculated by measuring the diameter of a circle having the same area as the projected area of ​​100 particles using a transmission electron microscope (TEM), and adopting the value as the arithmetic mean of these measurements. An example of a method for calculating the average particle size of quantum dots is shown below: (1) Prepare a measurement sample by dropping a quantum dot dispersion that does not contain reactive organic compounds onto a grid for the TEM measurement sample stage; (2) Take an image of the sample to be measured using a TEM (e.g., Hitachi High-Tech HT7800 series) (magnification of 20,000x or more); and (3) Measure the diameter of a circle having the same area as the projected area of ​​100 particles, and calculate their arithmetic mean.

[0056] It is preferable to use quantum dots in which organic ligands having coordinating groups are coordinated to the surface. By adding organic ligands to the raw material solution of the quantum dots during synthesis, excessive crystal growth can be prevented, and quantum dots within the desired particle size range can be obtained. In addition, quantum dots having a surface layer composed of organic ligands on their surface can be prevented from agglomerating after synthesis.

[0057] The organic ligand is preferably an organic compound having a coordinating group that bonds to the cation contained in the quantum dot. Examples of coordinating groups include halogen atoms, carboxyl groups, carboxylic acid anhydride groups, amino groups, ammonium groups, thiol groups (sulfanyl groups), sulfide groups, sulfoxide groups, phosphine groups, phosphine oxide groups, phosphoric acid groups, phosphonic acid groups, phosphinic acid groups, sulfonic acid groups, boronic acid groups, heterocyclic groups, etc. Such organic ligands may be used individually or in combination of two or more.

[0058] Examples of halogen atom-containing compounds include alkyl halides having linear or branched alkyl groups with 1 to 30 carbon atoms. Specific examples of such alkyl halides include methyl chloride, methyl bromide, methyl iodide, ethyl chloride, ethyl bromide, ethyl iodide, propyl chloride, propyl bromide, propyl iodide, butyl chloride, butyl bromide, butyl iodide, hexyl chloride, hexyl bromide, octyl chloride, octyl bromide, and decyl chloride.

[0059] Examples of carboxyl group-containing compounds include linear or branched aliphatic carboxylic acid compounds having 1 to 30 carbon atoms. Specific examples of such aliphatic carboxylic acid compounds include, for example, arachidonic acid, crotonic acid, trans-2-decenoic acid, erucic acid, 3-decenoic acid, cis-4,7,10,13,16,19-docosahexaenoic acid, 4-decenoic acid, allcis-5,8,11,14,17-eicosapentaenoic acid, allcis-8,11,14-eicosatrienoic acid, cis-9-hexadecenoic acid, trans-3-hexenoic acid, trans-2-hexenoic acid, 2-heptenoic acid, 3-heptenoic acid, 2-hexadecenoic acid, linolenic acid, linoleic acid, γ-linolenic acid, 3-nonenic acid, 2-nonenic acid, trans-2-octenoic acid, petroseric acid, elaidic acid, and oleic acid. Examples include octanoic acid, 3-octenoic acid, trans-2-pentenoic acid, trans-3-pentenoic acid, ricinoleic acid, sorbic acid, 2-tridecenoic acid, cis-15-tetracosenoic acid, 10-undecenoic acid, 2-undecenoic acid, acetic acid, butyric acid, behenic acid, cerotic acid, decanoic acid, arachidic acid, heneicosanoic acid, heptadecanoic acid, heptanoic acid, hexanoic acid, heptacosanoic acid, lauric acid, myristic acid, melissic acid, octacosanoic acid, nonadecanoic acid, nonacosanoic acid, n-octanoic acid, palmitic acid, pentadecanoic acid, propionic acid, pentacosanoic acid, nonanoic acid, stearic acid, lignoceric acid, tricosanoic acid, tridecanoic acid, undecanoic acid, valeric acid, etc.

[0060] Examples of amino group-containing compounds include aliphatic amine compounds having a linear or branched alkyl group with 1 to 30 carbon atoms. Specific examples of such aliphatic amine compounds include, for example, 1-aminoheptadecane, 1-aminononadecane, heptadecane-9-amine, stearylamine, oleylamine, 2-n-octyl-1-dodecylamine, allylamine, amylamine, 2-ethoxyethylamine, 3-ethoxypropylamine, isobutylamine, isoamylamine, 3-methoxypropylamine, 2-methoxyethylamine, 2-methylbutylamine, neopentylamine, n-propylamine Examples include methylamine, ethylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-octadecylamine, tri(n-hexyl)amine, tri(n-octyl)amine, and tri(n-decyl)amine.

[0061] Examples of thiol group-containing compounds include 1-hexanethiol, 1-octanthiol, and 1-dodecanethiol.

[0062] Examples of sulfide group-containing compounds include dialkyl sulfides such as dibutyl sulfide.

[0063] Examples of sulfoxide group-containing compounds include dialkyl sulfoxides such as dimethyl sulfoxide and dibutyl sulfoxide.

[0064] Examples of phosphine group-containing compounds include trialkylphosphines such as tripropylphosphine, tributylphosphine, trihexylphosphine, and trioctylphosphine.

[0065] Examples of phosphine oxide group-containing compounds include trialkylphosphine oxides such as tripropylphosphine oxide, tributylphosphine oxide, trihexylphosphine oxide, trioctylphosphine oxide, and tridecylphosphine oxide.

[0066] Examples of heterocyclic compounds include nitrogen-containing heterocyclic compounds such as pyridine, lutidine, colidine, and quinolines; and sulfur-containing heterocyclic compounds such as thiophene.

[0067] Among these organic ligands, at least one selected from the group consisting of alkyl halides, thiol group-containing compounds, and aliphatic carboxylic acid compounds is preferred from the viewpoint of dispersion stability and luminescence properties of quantum dots. In one embodiment of the present invention, it is preferable that the surface of the quantum dot is coordinated with at least one organic ligand selected from the group consisting of alkyl halides, thiol group-containing compounds, and aliphatic carboxylic acid compounds. Furthermore, it is more preferable that the organic ligand is at least one selected from the group consisting of oleic acid, heptanoic acid, hexanoic acid, heptacosanic acid, lauric acid, 1-hexanethiol, 1-octanthiol, and 1-dodecanethiol.

[0068] The content of organic ligands in quantum dots is not particularly limited. From the viewpoint of controlling the film thickness after ejection in an inkjet device, the content of organic ligands in quantum dots is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, with the mass of the quantum dot being 100% by mass. For example, the content of organic ligands in quantum dots is 5% by mass or more.

[0069] In one embodiment of the present invention, the surface of a quantum dot is coordinated with at least one organic ligand selected from the group consisting of alkyl halides, thiol group-containing compounds, and aliphatic carboxylic acid compounds, and the content of the organic ligand in the quantum dot is preferably 30% by mass or less, with the mass of the quantum dot being 100% by mass.

[0070] Quantum dots with organic ligands having coordinating groups coordinated to their surface can be synthesized by methods described, for example, J.Am.Chem.Soc.,115,pp8706-8715(1993), J.Phys.Chem.,101,pp9463-9475(1997), Nature volume 575,pp634-638(2019), etc. Commercially available quantum dots can also be suitably used.

[0071] The quantum dot content in the ink composition according to the present invention is 0.1% by mass or more and 10.0% by mass or less, preferably 0.5% by mass or more and 8.0% by mass or less, and more preferably 1.0% by mass or more and 6.0% by mass or less, based on 100% by mass of the total mass of the ink composition.

[0072] (Reactive organic compounds) The ink composition according to the present invention contains a reactive organic compound. The reactive organic compound is a compound represented by the following formula (1). As described above, by using the reactive organic compound according to the present invention, even if quantum dots are crosslinked, no active protons remain in the crosslinked structure. Furthermore, while quantum dots are sensitive to heat, crosslinking between quantum dots requires heating for the crosslinking reaction. As shown in the examples described later, the reactive organic compound according to the present invention allows for crosslinking reactions at lower temperatures than compounds having azide groups, and the completion time of the crosslinking reaction can also be shortened.

[0073] [ka]

[0074] In formula (1) above, Ar1 is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms.

[0075] In Ar1, the aromatic hydrocarbon group is not particularly limited as long as it is an aromatic hydrocarbon group with 6 to 60 carbon atoms (number of ring-forming carbon atoms). Specific examples of unsubstituted Ar1 include monovalent groups derived from aromatic hydrocarbons such as benzene, pentalene, indene, naphthalene, anthracene, azulene, heptalene, acenaphthene, phenalene, fluorene, phenanthrine, biphenyl, terphenyl, quaterphenyl, quinkiphenyl, sexiphenyl, pyrene, 9,9-diphenylfluorene, 9,9'-spirobi[fluorene], 9,9-dialkylfluorene, and indeno[1,2-b]fluorene. Preferably, Ar1 is a monovalent group derived from compounds selected from benzene, fluorene, biphenyl, terphenyl, and indeno[1,2-b]fluorene, as well as combinations thereof. More preferably, Ar1 is a monovalent group derived from a compound selected from benzene, fluorene, biphenyl, and indeno[1,2-b]fluorene, or combinations thereof. Even more preferably, Ar1 is a monovalent group derived from benzene.

[0076] When any hydrogen atom of Ar1 is substituted, the number of substituents introduced is not particularly limited, but is preferably 1 to 3, more preferably 1 to 2, and most preferably 1. In one embodiment of the present invention, Ar1 is unsubstituted. In one embodiment of the present invention, Ar1 has one substituent. When Ar1 has a substituent, the bonding position of the substituent is not particularly limited.

[0077] The substituents that may exist when Ar1 has substituents are not particularly limited and include alkyl groups, cycloalkyl groups, hydroxyalkyl groups, alkoxyalkyl groups, alkoxy groups, cycloalkoxy groups, alkenyl groups, alkynyl groups, amino groups, aryl groups, aryloxy groups, alkylthio groups, cycloalkylthio groups, arylthio groups, alkoxycarbonyl groups, aryloxycarbonyl groups, hydroxyl groups (-OH), carboxyl groups (-COOH), thiol groups (-SH), cyano groups (-CN), halogen groups, etc. When two or more hydrogen atoms are substituted, the types of substituents may be the same or different. Note that the substituents will not be the same as the group being substituted. For example, an alkyl group will not be substituted with another alkyl group.

[0078] The alkyl group may be linear or branched, but preferably linear alkyl groups having 1 to 18 carbon atoms or branched alkyl groups having 3 to 18 carbon atoms. Specifically, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, neopentyl group, 1,2-dimethylpropyl group, n-hexyl group, isohexyl group, 1,3-dimethylbutyl group, 1-isopropylpropyl group, 1,2-dimethylbutyl group, n-heptyl group, 1,4-dimethylpentyl group, 3-ethylpentyl group, 2-methyl-1-isopropylpropyl group, Examples include 1-ethyl-3-methylbutyl group, n-octyl group, 2-ethylhexyl group, 3-methyl-1-isopropylbutyl group, 2-methyl-1-isopropyl group, 1-tert-butyl-2-methylpropyl group, n-nonyl group, 3,5,5-trimethylhexyl group, n-decyl group, isodecyl group, n-undecyl group, 1-methyldecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, and n-octadecyl group.

[0079] Examples of cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl groups.

[0080] Examples of hydroxyalkyl groups include those in which the alkyl group is substituted with 1 to 3 (preferably 1 to 2, particularly preferably 1) hydroxyl groups (e.g., hydroxymethyl group, hydroxyethyl group).

[0081] Examples of alkoxyalkyl groups include those in which the alkyl group is substituted with 1 to 3 (preferably 1 to 2, particularly preferably 1) of the above alkoxy groups.

[0082] Examples of alkoxy groups include methoxy, ethoxy, propoxy, isopropoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy, tetradecyloxy, pentadecyloxy, hexadecyloxy, heptadecyloxy, octadecyloxy, 2-ethylhexyloxy, and 3-ethylpentyloxy.

[0083] Examples of cycloalkoxy groups include cyclopropyloxy group, cyclobutyloxy group, cyclopentyloxy group, and cyclohexyloxy group.

[0084] Examples of alkenyl groups include vinyl group, allyl group, 1-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 1-heptenyl group, 2-heptenyl group, 5-heptenyl group, 1-octenyl group, 3-octenyl group, and 5-octenyl group.

[0085] Examples of alkynyl groups include acetylenyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group, 2-butynyl group, 3-butynyl group, 1-pentetyl group, 2-pentetyl group, 3-pentetyl group, 1-hexynyl group, 2-hexynyl group, 3-hexynyl group, 1-heptynyl group, 2-heptynyl group, 5-heptynyl group, 1-octinyl group, 3-octinyl group, and 5-octinyl group.

[0086] Examples of aryl groups include phenyl, naphthyl, biphenyl, fluorenyl, anthuryl, pyrenyl, azlenyl, acenaphthirenyl, terphenyl, and phenanthuryl groups.

[0087] Examples of aryloxy groups include phenoxy groups and naphthyloxy groups.

[0088] Examples of alkylthio groups include methylthio, ethylthio, propylthio, pentylthio, hexylthio, octylthio, and dodecylthio groups.

[0089] Examples of cycloalkylthio groups include cyclopentylthio groups and cyclohexylthio groups.

[0090] Examples of arylthio groups include phenylthio groups and naphthylthio groups.

[0091] Examples of alkoxycarbonyl groups include methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, and dodecyloxycarbonyl group.

[0092] Examples of aryloxycarbonyl groups include phenyloxycarbonyl groups and naphthyloxycarbonyl groups.

[0093] Examples of halogen groups include fluoro groups, chloro groups, bromo groups, and iodine groups.

[0094] When any hydrogen atom of Ar1 is substituted, the substituents that may be present are preferably linear or branched alkyl groups or halogen groups having 1 to 8 carbon atoms, more preferably linear or branched alkyl groups or halogen groups having 1 to 3 carbon atoms, and particularly preferably methyl groups or fluoro groups.

[0095] In formula (1) above, L1 is a single bond or an oxygen atom. L1 is preferably an oxygen atom.

[0096] In formula (1) above, L2 is a single bond, or a substituted or unsubstituted saturated hydrocarbon group having 1 to 60 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms.

[0097] In L2, saturated hydrocarbon groups having 1 to 60 carbon atoms are not particularly limited. Specific examples of L2 (unsubstituted) groups include methylene, ethylene, trimethylene, propylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, and octamethylene groups.

[0098] In L2, the aromatic hydrocarbon group is not particularly limited as long as it is an aromatic hydrocarbon group with 6 to 60 carbon atoms (number of ring-forming carbon atoms). Specific examples of unsubstituted L2 include divalent groups derived from aromatic hydrocarbons such as benzene, pentalene, indene, naphthalene, anthracene, azulene, heptalene, acenaphthene, phenalene, fluorene, phenanthrine, biphenyl, terphenyl, quaterphenyl, quinkiphenyl, sexiphenyl, pyrene, 9,9-diphenylfluorene, 9,9'-spirobi[fluorene], 9,9-dialkylfluorene, and indeno[1,2-b]fluorene. It is preferable that L2 is a divalent group derived from compounds selected from benzene, fluorene, biphenyl, terphenyl, and indeno[1,2-b]fluorene, as well as combinations thereof. More preferably, L2 is a divalent group derived from a compound selected from benzene, fluorene, biphenyl, and indeno[1,2-b]fluorene, or combinations thereof. Even more preferably, Ar1 is a divalent group derived from benzene.

[0099] The substituents that may be present when L2 has substituents are the same as defined for Ar1 above. The substituents that may be present when L2 has substituents are preferably linear or branched alkyl groups having 1 to 8 carbon atoms, and more preferably linear or branched alkyl groups having 1 to 3 carbon atoms.

[0100] L2 is preferably a single bond or an unsubstituted saturated hydrocarbon group having 1 to 8 carbon atoms, more preferably a single bond or a methylene group, ethylene group, trimethylene group, propylene group, tetramethylene group, pentamethylene group, hexamethylene group, heptamethylene group, or octamethylene group, and even more preferably a single bond or a methylene group, ethylene group, trimethylene group, or propylene group.

[0101] In equation (1) above, X is a group selected from the group consisting of the following equations (1-1) to (1-37).

[0102] [ka]

[0103] [ka]

[0104] In the above formulas (1-1) to (1-37), * represents a bonding site.

[0105] In the above formulas (1-1) to (1-5), (1-7), (1-12), (1-19), (1-22), (1-23), (1-27), and (1-28), a1 independently represents an integer between 2 and 4, inclusive.

[0106] In the above equations (1-6), (1-8), (1-9), (1-13) to (1-15), (1-20), (1-25), and (1-30), a2 independently represents an integer between 1 and 3, a3 independently represents either 1 or 2, and the sum of a2 and a3 is independently 2, 3, or 4.

[0107] In the above equations (1-10), (1-16), (1-17), (1-21), (1-26), and (1-31), a4 independently represents either 1 or 2, a5 independently represents 1, a6 independently represents either 1 or 2, and the sum of a4, a5, and a6 is independently either 3 or 4.

[0108] In equations (1-24) and (1-29) above, a7 independently represents an integer between 1 and 3, and a8 independently represents an integer between 1 and 3, and the sum of a7 and a8 is independently 2, 3, or 4.

[0109] In the above equation (1-32), a9 is an integer between 2 and 18, inclusive.

[0110] In the above formula (1-37), a 10 is 1 or 2, and a 11It represents either 1 or 2.

[0111] In the above formulas (1-5) and (1-6), Ar2 is independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms.

[0112] In Ar2, substituted or unsubstituted aromatic hydrocarbon groups having 6 to 60 carbon atoms are defined in the same way as in Ar1 above. Two types of Ar2 present in the same molecule may be the same or different.

[0113] In the above formulas (1-27) to (1-31), Y is independently -O-, -S-, -C(CH3)2-, or a diphenylmethylene group.

[0114] In formula (1) above, X is preferably a group selected from the group consisting of the following formulas (1-38) to (1-105).

[0115] [ka]

[0116] [ka]

[0117] [ka]

[0118] In the above formulas (1-53) and (1-54), Ar2 is independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms.

[0119] In the above formulas (1-100) to (1-102), Y is independently -O-, -S-, -C(CH3)2-, or a diphenylmethylene group.

[0120] The following are specific examples of reactive organic compounds 1 to 24 according to one embodiment of the present invention. However, the present invention is not limited to these specific examples.

[0121] [ka]

[0122] [ka]

[0123] Among these, at least one selected from the group consisting of compound 7, compound 14, compound 17, compound 20, and compound 23 is more preferred.

[0124] The content of the reactive organic compound in the ink composition according to the present invention is 0.1% by mass or more and 10.0% by mass or less, preferably 0.5% by mass or more and 5% by mass or less, with the mass of quantum dots in the ink composition being 100% by mass.

[0125] The reactive organic compounds according to the present invention can be synthesized using known organic synthesis methods. More specifically, they can be synthesized by the methods described in the Examples or by methods similar to those described in the Examples. For example, they can be synthesized by changing the raw materials or reaction conditions, adding or excluding some steps, or appropriately combining known synthesis methods in the methods described in the Examples.

[0126] The method for confirming the structure of the reactive organic compound according to the present invention is not particularly limited. The structure of the reactive organic compound according to the present invention can be confirmed, for example, by known methods (e.g., NMR, LC-MS, etc.).

[0127] (solvent) The ink composition according to the present invention contains a solvent. The solvent contains at least one compound selected from the compounds represented by the following formulas (2) to (5). The solvent may be used alone or as a mixture of two or more. The solvent may be a commercially available product or a synthetic product.

[0128] [ka]

[0129] In formula (2) above, R1 is a linear or branched saturated hydrocarbon group having 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon group having 3 to 12 carbon atoms, and b represents an integer between 1 and 3. When b is 2 or greater, the types of R1 may be the same or different from one another.

[0130] In formula (2), R1 is preferably a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms.

[0131] In formula (2), the linear or branched saturated hydrocarbon group having 1 to 18 carbon atoms is not particularly limited. Specific examples of linear or branched saturated hydrocarbon groups having 1 to 18 carbon atoms include linear alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, and n-octadecyl; isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, tert-pentyl, and neo Examples of branched alkyl groups include pentyl group, 1,2-dimethylpropyl group, isohexyl group, 1,3-dimethylbutyl group, 1-isopropylpropyl group, 1,2-dimethylbutyl group, 1,4-dimethylpentyl group, 3-ethylpentyl group, 2-methyl-1-isopropylpropyl group, 1-ethyl-3-methylbutyl group, 2-ethylhexyl group, 3-methyl-1-isopropylbutyl group, 2-methyl-1-isopropyl group, 1-tert-butyl-2-methylpropyl group, 3,5,5-trimethylhexyl group, isodecyl group, and 1-methyldecyl group.

[0132] In formula (2), the cyclic saturated hydrocarbon group having 3 to 12 carbon atoms is not particularly limited. Specific examples of cyclic saturated hydrocarbon groups having 3 to 12 carbon atoms include: cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, cyclodecyl group, bicyclo[1.1.0]butyl group, bicyclo[1.1.1]pentyl group, bicyclo[2.1.0]pentyl group, bicyclo[3.1.0]hexyl group, bicyclo[2.1.1]hexyl group, bicyclo[2.2.0]hexyl group, bicyclo[2.2.1]heptyl group (norbornyl group), bicyclo[3.1.1]heptyl group, bicyclo[3.2.0]heptyl group, Bicyclo[4.1.0]heptyl group, bicyclo[2.2.2]octyl group, bicyclo[3.2.1]octyl group, bicyclo[3.3.0]octyl group, bicyclo[4.1.1]octyl group, bicyclo[4.2.0]octyl group, bicyclo[5.1.0]octyl group, bicyclo[3.2.2]nonyl group, bicyclo[3.3.1]nonyl group, bicyclo[4.2.1]nonyl group, bicyclo[4.3.0]nonyl group, bicyclo[5.1.1]nonyl group, bicyclo[5.2.0]nonyl group, bicyclo[6.1.0]nonyl group, bicyclo[4.3.1]decyl group, tricyclo[5.2.1.0 2,6 Examples include decyl groups, isobornyl groups, and adamantyl groups.

[0133] Specific examples of compounds represented by formula (2) include toluene, xylene, ethylbenzene, diethylbenzene, mesitylene, propylbenzene, cyclopropylbenzene, cyclopentylbenzene, and cyclohexylbenzene.

[0134] [ka]

[0135] In formula (3) above, R2 is a linear or branched saturated hydrocarbon group having 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon group having 3 to 12 carbon atoms.

[0136] In formula (3), the definitions of a linear or branched saturated hydrocarbon group having 1 to 18 carbon atoms, and a cyclic saturated hydrocarbon group having 3 to 12 carbon atoms, are the same as those in R1.

[0137] In formula (3), R2 is preferably a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms or a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms.

[0138] In formula (3), R2 is more preferably a linear or branched saturated hydrocarbon group having 6 to 10 carbon atoms or a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms.

[0139] Specific examples of compounds represented by formula (3) include methylcyclohexane, ethylcyclohexane, n-butylcyclohexane, n-pentylcyclohexane, n-hexylcyclohexane, n-heptylcyclohexane, n-octylcyclohexane, n-nonylcyclohexane, n-decylcyclohexane, n-undecylcyclohexane, n-dodecylcyclohexane, n-tridecylcyclohexane, n-tetradecylcyclohexane, n-pentadecylcyclohexane, n-hexadecylcyclohexane, n-heptadecylcyclohexane, n-octadecylcyclohexane, isopropylcyclohexane, isobutylcyclohexane, sec-butylcyclohexane, tert-butylcyclohexane, isopentylcyclohexane, tert-pentylcyclo Examples include hexane, neopentylcyclohexane, 1,2-dimethylpropylcyclohexane, isohexylcyclohexane, 1,3-dimethylbutylcyclohexane, 1-isopropylpropylcyclohexane, 1,2-dimethylbutylcyclohexane, 1,4-dimethylpentylcyclohexane, 3-ethylpentylcyclohexane, 2-methyl-1-isopropylpropylcyclohexane, 1-ethyl-3-methylbutylcyclohexane, 2-ethylhexylcyclohexane, 3-methyl-1-isopropylbutylcyclohexane, 2-methyl-1-isopropylcyclohexane, 1-tert-butyl-2-methylpropylcyclohexane, 3,5,5-trimethylhexylcyclohexane, isodecylcyclohexane, and 1-methyldecylcyclohexane.

[0140] [ka]

[0141] In equation (4) above, c represents an integer between 6 and 18, inclusive.

[0142] Specific examples of compounds represented by formula (4) include n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, and n-eicosane.

[0143] [ka]

[0144] In formula (5) above, Z is -OH, -COOH, -NH2, or -SH, and d is an integer between 7 and 17, representing the ink composition.

[0145] Specific examples of compounds represented by formula (5) include n-octanol, n-nonanol, n-decanol, n-undecanol, n-dodecanol, n-tridecanol, n-tetradecanol, n-pentadecanol, n-hexadecanol, n-heptadecanol, n-octadecanol; nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid; n-octylamine, n-nonylamine, n-decylamine Examples include mine, n-undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine; 1-octanthiol, 1-nonanthiol, 1-decanethiol, 1-undecanethiol, 1-dodecanethiol, 1-tridecanethiol, 1-tetradecanethiol, 1-pentadecanthiol, 1-hexadecanthiol, 1-heptadecanthiol, 1-octadecanethiol, etc.

[0146] The solvent content can be appropriately set to satisfy the above-mentioned content of quantum dots and reactive organic compounds.

[0147] (Additives) The ink composition according to the present invention may optionally contain various additives. Examples of additives include, for example, host materials used in the light-emitting layer, antioxidants, leveling agents, plasticizers, surfactants, defoamers, silane coupling agents, ultraviolet absorbers, adhesion promoters, and the like.

[0148] Examples of host materials include compounds having a carbazole skeleton, a diarylamine skeleton, a pyridine skeleton, a pyrazine skeleton, a triazine skeleton, and an arylsilane skeleton.

[0149] The amount of the above-mentioned additive can be appropriately determined according to the application, as long as it does not impair the objective of the present invention.

[0150] The ink composition according to the present invention may further contain other solvents other than the solvent described above, as long as it does not impair the objective of the present invention. Examples of such other solvents include (+)-limonene, ethylene glycol monobutyl ether, α-terpineol, propylene carbonate, dimethyl sulfoxide, N,N-dimethylformamide, 1-bromooctane, 1-bromononane, 1-bromodecane, and 1-bromododecane. The content of these other solvents is preferably 10 parts by volume or less, and more preferably 5 parts by volume or less, per 100 parts by volume of the solvent described above. In particular, it is preferable that the content of other solvents is 0 parts by volume, that is, that no other solvents other than the solvent described above are included.

[0151] [Method for manufacturing ink composition] The method for producing the ink composition according to the present invention is not particularly limited. For example, the quantum dots, reactive organic compound, solvent, and other components added as needed may be mixed all at once, or each component may be mixed sequentially. The temperature during mixing is not particularly limited, but is usually in the range of 20°C to 30°C. Similarly, the mixing time is not particularly limited, but is usually in the range of 0.1 hours to 1 hour.

[0152] [Application] The applications of the ink composition according to the present invention are not particularly limited, and it can be used, for example, to form quantum dot-containing layers in various optical components used in display devices and the like. Furthermore, the ink composition according to the present invention is suitable for forming quantum dot-containing layers by an inkjet method and can be preferably used for inkjet applications. Examples of optical components include semiconductor optical components such as light conversion members and light-emitting members.

[0153] In particular, the ink composition according to the present invention is suitably used to form the light-emitting layer of an electroluminescent element. That is, according to another embodiment of the present invention, an electroluminescent element (quantum dot electroluminescent element) is provided which comprises a light-emitting layer formed using the ink composition according to the present invention. According to another embodiment of the present invention, an image display device is provided which comprises the above-mentioned electroluminescent element (quantum dot electroluminescent element).

[0154] The following provides a detailed explanation of quantum dot electroluminescent devices.

[0155] [Quantum dot electroluminescent element] The quantum dot electroluminescent element according to this embodiment will be described in detail with reference to Figure 1. Figure 1 is a schematic diagram showing the quantum dot electroluminescent element according to this embodiment. In this specification, "quantum dot electroluminescent element" may be abbreviated as "QD-LED".

[0156] As shown in Figure 1, the QD-LED 100 according to this embodiment comprises a substrate 110, a first electrode 120 disposed on the substrate 110, a hole injection layer 130 disposed on the first electrode 120, a hole transport layer 140 disposed on the hole injection layer 130, a light-emitting layer 150 disposed on the hole transport layer 140, an electron transport layer 160 disposed on the light-emitting layer 150, an electron injection layer 170 disposed on the electron transport layer 160, and a second electrode 180 disposed on the electron injection layer 170.

[0157] The method for forming layers other than the light-emitting layer 150 is not particularly limited. Layers other than the light-emitting layer 150 may be formed by, for example, vacuum deposition or by solution coating. Examples of solution coating methods include spin coating, casting, microgravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, screen printing, flexographic printing, offset printing, and inkjet printing.

[0158] When forming layers other than the luminescent layer 150 by a solution coating method, examples of solvents that can be used include toluene, xylene, ethylbenzene, diethylbenzene, methylene, propylbenzene, cyclohexylbenzene, dimethoxybenzene, anisole, ethoxytoluene, phenoxytoluene, isopropyl biphenyl, dimethylanisole, phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, cyclohexane, etc. The amount of solvent used in the coating solution is not particularly limited.

[0159] The substrate 110 can be a substrate commonly used in EL elements. For example, the substrate 110 may be a glass substrate, a semiconductor substrate such as a silicon substrate, or a transparent plastic substrate.

[0160] A first electrode 120 is formed on the substrate 110. Specifically, the first electrode 120 is an anode and is formed from a metal, alloy, or conductive compound with a high work function. For example, the first electrode 120 may be formed as a transmissive electrode using indium tin oxide (In2O3-SnO2:ITO), indium zinc oxide (In2O3-ZnO), tin oxide (SnO2), zinc oxide (ZnO), etc., which have excellent transparency and conductivity. Alternatively, the first electrode 120 may be formed as a reflective electrode by laminating magnesium (Mg), aluminum (Al), etc., onto the transparent conductive film. Furthermore, after forming the first electrode 120 on the substrate 110, cleaning and UV-ozone treatment may be performed if necessary.

[0161] A hole injection layer 130 is formed on the first electrode 120. The hole injection layer 130 is a layer that facilitates the injection of holes from the first electrode 120, and may be formed with a thickness of 10 nm to 1000 nm, more specifically, 20 nm to 300 nm (dry film thickness; the same applies hereinafter).

[0162] The hole injection layer 130 can be formed using known hole injection materials. Examples of known hole injection materials for forming the hole injection layer 130 include: poly(ether ketone)-containing triphenylamine (TPAPEK), 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate (PPBI), N,N'-diphenyl-N,N'-bis-[4-(phenyl-m-tolyl-amino)-phenyl]-biphenyl-4,4'-diamine (DNTPD), and copper phthalocyanine. phthalocyanine), 4,4',4”-tris(3-methylphenylphenylamino)triphenylamine (m-MTDATA), N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (NPB), 4,4',4”-tris(diphenylamino)triphenylamine (TDATA), 4,4',4”-tris(N,N-2-naphthylphenylamino)triphenylamine (2-TNATA), polyaniline / dodecylbenzenesulfonic acid acid), poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate)(poly(3,Examples include 4-ethylenedioxythiophene / poly(4-styrenesulfonate):PEDOT / PSS, and polyaniline / 10-camphorsulfonic acid.

[0163] A hole transport layer 140 is formed on the hole injection layer 130. The hole transport layer 140 is a layer that has the function of transporting holes, and may be formed with a thickness of, for example, 10 nm to 150 nm, more specifically 20 nm to 50 nm.

[0164] The hole transport layer 140 may be formed of a known hole transport material. Examples of known hole transport materials include carbazole derivatives such as 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), N-phenylcarbazole, and polyvinylcarbazole, N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1-biphenyl]-4,4'-diamine (TPD), and 4,4',4”-tris(N-carbazolyl) Examples include 4,4',4”-tris(N-carbazolyl)triphenylamine (TCTA), N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (NPB), and poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine):TFB). These hole transport materials may be used individually or as a mixture of two or more.

[0165] A light-emitting layer 150 is formed on the hole transport layer 140. The light-emitting layer 150 contains quantum dots and, as described above, is preferably formed using an inkjet method. One embodiment of the present invention is a field-emitting element (quantum dot electroluminescent element) comprising a light-emitting layer formed by an inkjet device using the ink composition according to the present invention. Another embodiment of the present invention is a quantum dot electroluminescent element comprising a light-emitting layer formed by an inkjet device, wherein the light-emitting layer is formed by an inkjet device. The light-emitting layer 150 may be formed with a thickness of, for example, 10 nm to 60 nm, more specifically 20 nm to 50 nm.

[0166] An electron transport layer 160 is formed on the light-emitting layer 150. The electron transport layer 160 is a layer that has the function of transporting electrons and is formed using methods such as vacuum deposition, spin coating, or inkjet. The electron transport layer 160 may be formed with a thickness of, for example, 15 nm to 50 nm.

[0167] The electron transport layer 160 may be formed using a known electron transport material. This electron transport material may be an organic material or an inorganic material. Examples of known organic electron transport materials include (8-quinolinato)lithium (lithium quinolate) (Liq), tris(8-quinolinato)aluminium (tris(8-quinolinato)aluminium:Alq3), and compounds having a nitrogen-containing aromatic ring. Specific examples of compounds containing nitrogen-containing aromatic rings include, for example, compounds containing a pyridine ring such as 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene, compounds containing a triazine ring such as 2,4,6-tris(3'-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine, and 2-(4-(N-phenylbenzoinidazolyl-1-ylphenyl)-9,10-dinaphthylanthracene Examples of compounds containing an imidazole ring include N-phenylbenzoimidazolyl-1-yl-phenyl)-9,10-dinaphthylanthracene and 1,3,5-tris(N-phenyl-benzimidazol-2-yl)benzene (TPBI). Furthermore, known inorganic electron transport materials are not particularly limited, but examples include oxides of TiO2, ZnO, ZnMgO, SiO2, SnO2, WO3, Ta2O3, BaTiO3, BaZrO3, ZrO2, HfO2, Al2O3, Y2O3, and ZrSiO4.

[0168] The above-mentioned electron transport material may be a single material or a mixture of two or more materials.

[0169] An electron injection layer 170 is formed on the electron transport layer 160. The electron injection layer 170 is a layer that facilitates the injection of electrons from the second electrode 180. The electron injection layer 170 is formed using a method such as vacuum deposition. The electron injection layer 170 may be formed with a thickness of 0.1 nm to 5 nm, more specifically 0.3 nm to 2 nm. Any known material can be used to form the electron injection layer 170. For example, the electron injection layer 170 may be formed using lithium compounds such as (8-quinolinato)lithium (lithium quinolate) ((8-quinolinato)lithium:Liq) and lithium fluoride (LiF), sodium chloride (NaCl), cesium fluoride (CsF), lithium oxide (Li2O), or barium oxide (BaO).

[0170] A second electrode 180 is formed on the electron injection layer 170. The second electrode 180 is formed using a method such as vacuum deposition. Specifically, the second electrode 180 is a cathode and is formed from a metal, alloy, or conductive compound with a small work function. For example, the second electrode 180 may be formed as a reflective electrode from a metal such as lithium (Li), magnesium (Mg), aluminum (Al), or calcium (Ca), or from an alloy such as aluminum-lithium (Al-Li), magnesium-indium (Mg-In), or magnesium-silver (Mg-Ag). The second electrode 180 may be formed with a thickness of 10 nm to 200 nm, more specifically 50 nm to 150 nm. Alternatively, the second electrode 180 may be formed as a transmissive electrode from a thin film of the above-mentioned metal material with a thickness of 20 nm or less, or from a transparent conductive film such as indium tin oxide (In2O3-SnO2) or indium zinc oxide (In2O3-ZnO).

[0171] The laminated structure of the QD-LED 100 according to this embodiment is not limited to the examples given above. The QD-LED 100 according to this embodiment may be formed using other known laminated structures. For example, the QD-LED 100 may omit one or more of the hole injection layer 130, hole transport layer 140, electron transport layer 160, and electron injection layer 170, or it may have additional layers. Furthermore, each layer of the QD-LED 100 may be formed as a single layer or as multiple layers.

[0172] For example, the QD-LED 100 may further include a hole blocking layer between the hole transport layer 140 and the light-emitting layer 150 to prevent excitons or holes from diffusing into the electron transport layer 160. The hole blocking layer can be formed from, for example, an oxadiazole derivative, a triazole derivative, or a phenanthroline derivative.

[0173] While embodiments of the present invention have been described in detail, these are descriptive and illustrative, and not limiting, and it is clear that the scope of the present invention should be interpreted by the appended claims.

[0174] The present invention encompasses the following embodiments and forms.

[0175] 1. An ink composition comprising quantum dots, a reactive organic compound, and a solvent. The quantum dots do not contain cadmium (Cd) or lead (Pb), the average particle size of the quantum dots is between 1 nm and 15 nm, and the content of the quantum dots is between 0.1% and 10.0% by mass, based on 100% by mass of the total mass of the ink composition. The reactive organic compound is a compound represented by the following formula (1):

[0176] [ka]

[0177] In the above formula (1), Ar1 is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms. L1 is a single bond or an oxygen atom. L2 is a single bond, or a saturated hydrocarbon group having 1 to 60 carbon atoms, either substituted or unsubstituted, or an aromatic hydrocarbon group having 6 to 60 carbon atoms, X is a group selected from the group consisting of the following equations (1-1) to (1-37),

[0178] [ka]

[0179] [ka]

[0180] In the above formulas (1-1) to (1-37), * represents a bonding site. In the above equations (1-1) to (1-5), (1-7), (1-12), (1-19), (1-22), (1-23), (1-27), and (1-28), a1 independently represents an integer between 2 and 4, In the above equations (1-6), (1-8), (1-9), (1-13)~(1-15), (1-20), (1-25), and (1-30), a2 independently represents an integer between 1 and 3 (inclusive), a3 independently represents either 1 or 2, and the sum of a2 and a3 is independently 2, 3, or 4. In the above equations (1-10), (1-16), (1-17), (1-21), (1-26), and (1-31), a4 independently represents either 1 or 2, a5 independently represents 1, a6 independently represents either 1 or 2, and the sum of a4, a5, and a6 independently represents either 3 or 4. In the above formulas (1-24) and (1-29), a7 independently represents an integer of 1 or more and 3 or less, a8 independently represents an integer of 1 or more and 3 or less, and the sum of a7 and a8 independently is 2, 3, or 4. In the above formula (1-32), a9 is an integer of 2 or more and 18 or less. In the above formula (1-37), a 10 represents 1 or 2, and a 11 represents 1 or 2. In the above formulas (1-5) and (1-6), Ar2 independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms. In the above formulas (1-27) to (1-31), Y independently represents -O-, -S-, -C(CH3)2- or a diphenylmethylene group. The content of the reactive organic compound is 0.1% by mass or more and 10.0% by mass or less based on 100% by mass of the mass of the quantum dots in the ink composition. The solvent contains at least one selected from the compounds represented by the following formulas (2) to (5).

[0181]

Chemical formula

[0182] In the above formula (2), R1 is a linear or branched saturated hydrocarbon group having 1 to 18 carbon atoms or a cyclic saturated hydrocarbon group having 3 to 12 carbon atoms, and b represents an integer of 1 or more and 3 or less.

[0183]

Chemical formula

[0184] In the above formula (3), R2 is a linear or branched saturated hydrocarbon group having 1 to 18 carbon atoms or a cyclic saturated hydrocarbon group having 3 to 12 carbon atoms.

[0185]

Chemical formula

[0186] In the above equation (4), c represents an integer between 6 and 18,

[0187] [ka]

[0188] In the above formula (5), Z is -OH, -COOH, -NH2, or -SH, and d is an integer between 7 and 17, representing an ink composition.

[0189] 2.X is a group selected from the group consisting of the following equations (1-38) to (1-105),

[0190] [ka]

[0191] [ka]

[0192] [ka]

[0193] In the above formulas (1-53) and (1-54), Ar2 is independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms. In the above formulas (1-100) to (1-102), Y is -O-, -S-, -C(CH3)2-, or a diphenylmethylene group. The aforementioned R1 is a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms. The ink composition according to 1. above, wherein R2 is a linear or branched saturated hydrocarbon group having 6 to 10 carbon atoms or a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms.

[0194] 3. The surface of the quantum dot is coordinated with at least one organic ligand selected from the group consisting of alkyl halides, thiol group-containing compounds, and aliphatic carboxylic acid compounds. The ink composition according to 1. or 2. above, wherein the content of the organic ligand in the quantum dot is 30% by mass or less, with the mass of the quantum dot being 100% by mass.

[0195] 4. A quantum dot electroluminescent element comprising a light-emitting layer formed using the ink composition described in 1. or 2. above.

[0196] 5. A quantum dot electroluminescent element comprising a light-emitting layer formed by an inkjet device using the ink composition described in 1. or 2. above.

[0197] An image display device comprising the quantum dot electroluminescent element described in item 4 or 5 above.

[0198] 6. A method for manufacturing a quantum dot electroluminescent element, comprising a light-emitting layer formed using the ink composition described in 1. or 2. above, The light-emitting layer is formed using an inkjet device, in a manufacturing method. [Examples]

[0199] The present invention will be described in more detail using the following examples and comparative examples, but the technical scope of the present invention is not limited to the following examples.

[0200] <Synthesis of Compound 7> Compound 7 was synthesized according to the following reaction equation.

[0201] [ka]

[0202] A mixture of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (5.0 g), triethylamine (4.6 g), and dichloromethane (80 mL) was cooled on ice, and phenylacetyl chloride (5.3 g) was added dropwise over 30 minutes. The reaction was then stirred at room temperature for 24 hours to complete the reaction. The reaction mixture was extracted three times with dichloromethane, and the organic solvent was removed by distillation. The crude product was purified by silica gel chromatography (eluent: ethyl acetate / hexane) to obtain the viscous liquid intermediate 7-1 (7.28 g, yield 94.6%).

[0203] In a 300 mL three-necked flask, intermediate 7-1 (3.64 g), diazabicycloundecene (3.3 g), and acetonitrile (100 mL) were placed, and p-acetamidobenzenesulfonyl azide (5.2 g) was slowly added in portions. The mixture was stirred at room temperature under a nitrogen atmosphere for 24 hours. After the reaction was complete, the resulting mixture was poured into water and extracted with dichloromethane, and the organic solvent was removed by distillation. The crude product was purified by silica gel chromatography (eluent: dichloromethane) to obtain compound 7 (2.32 g, yield 59.2%).

[0204] <Synthesis of Compound 14> Compound 14 was synthesized according to the following reaction equation.

[0205] [ka]

[0206] Into a 300 mL three-necked flask, pentaerythritol (14.69 mmol, 2 g), p-tolylacetic acid (61.70 mmol, 9.27 g), p-toluenesulfonic acid (12.34 mmol, 2.35 g), and toluene (73 mL) were added, and the mixture was refluxed and stirred under a nitrogen atmosphere. After completion of the reaction, the resulting solution was neutralized with a 1% aqueous sodium hydroxide solution. Then, the organic layer was washed with an 8% aqueous sodium carbonate solution and pure water. The organic layer was dried over magnesium sulfate and then filtered off. The resulting solution was concentrated and then diluted with dichloromethane (10 mL), and methanol (75 mL) was added to precipitate a solid. The obtained solid was dried in vacuo (50 °C, 16 h) to obtain Intermediate 14-1 (yield 6.2 g, yield 63%).

[0207] Into a 200 mL four-necked flask, Intermediate 14-1 (1.50 mmol, 1.0 g), diazabicycloundecene (7.82 mmol, 1.88 g), and acetonitrile (75.2 mL) were added and stirred. Then, p-acetamidobenzenesulfonyl azide (7.82 mmol, 1.88 g) was slowly added, and the mixture was stirred at room temperature for 24 h. After adding pure water to the reaction solution to stop the reaction, liquid separation was performed with dichloromethane and pure water. The organic layer was dried over magnesium sulfate and then filtered off. The resulting solution was concentrated and then recrystallized with methanol. The obtained solid was dried in vacuo (50 °C, 16 h) to obtain Compound 14 (yield 0.4 g, yield 35%).

[0208] <Synthesis of Compound 20> Compound 20 was synthesized according to the following reaction formula.

[0209]

Chemical formula

[0210] Into a 200 mL three-necked flask, dipentaerythritol (11.80 mmol, 3.0 g), p-tolylacetic acid (74.33 mmol, 11.16 g), p-toluenesulfonic acid (7.43 mmol, 1.41 g), and toluene (59 mL) were added, and the mixture was refluxed and stirred under a nitrogen atmosphere. After completion of the reaction, the resulting solution was neutralized with a 1% aqueous sodium hydroxide solution. Then, the organic layer was washed with an 8% aqueous sodium carbonate solution and pure water. The organic layer was dried over magnesium sulfate and then filtered off. The resulting solution was concentrated, diluted with dichloromethane (10 mL), and methanol (75 mL) was added to precipitate a solid. The resulting solid was dried in vacuo (50 °C, 16 h) to obtain Intermediate 20-1 (yield 7.0 g, yield 57%).

[0211] Into a 200 mL four-necked flask, Intermediate 20-1 (0.95 mmol, 1.0 g), diazabicycloundecene (12.60 mmol, 1.92 g), and acetonitrile (48 mL) were added and stirred. Then, p-acetamidobenzenesulfonyl azide (11.46 mmol, 2.75 g) was slowly added, and the mixture was stirred at room temperature for 12 h. After adding pure water to the reaction solution to stop the reaction, a liquid separation operation was performed with ethyl acetate and pure water. The organic layer was dried over magnesium sulfate and then filtered off. The resulting solution was concentrated and then recrystallized using methanol. The resulting solid was dried in vacuo (50 °C, 16 h) to obtain Compound 20 (yield 0.5 g, yield 44%).

[0212] <Synthesis of Compound 17> Compound 17 was synthesized according to the following reaction formula.

[0213]

Chemical formula

[0214] Pentaerythritol (22.03 mmol, 3.0 g), 4-fluorophenylacetic acid (92.54 mmol, 14.27 g), p-toluenesulfonic acid (18.51 mmol, 3.52 g), and toluene (110 mL) were placed in a 300 mL three-necked flask and stirred under reflux under a nitrogen atmosphere. After the reaction was complete, the resulting solution was neutralized with 1% aqueous sodium hydroxide solution. The organic layer was then washed with 8% aqueous sodium carbonate solution and pure water. The organic layer was dried over magnesium sulfate and filtered off. The resulting solution was concentrated, diluted with dichloromethane (10 mL), and methanol (75 mL) was added to precipitate a solid. The obtained solid was vacuum dried (50°C, 16 hours) to obtain intermediate 17-1 (yield 10.9 g, yield 74%).

[0215] In a 200 mL four-necked flask, intermediate 17-1 (1.47 mmol, 1.0 g), diazabicycloundecene (14.69 mmol, 2.24 g), and acetonitrile (73.5 mL) were added and stirred. Then, p-acetamidobenzenesulfonic acid azide (14.69 mmol, 3.53 g) was slowly added, and the mixture was stirred at room temperature for 12 hours. After stopping the reaction by adding pure water to the reaction mixture, the reaction was separated by liquid-liquid extraction with dichloromethane and pure water. The organic layer was dried over magnesium sulfate and filtered off. The resulting solution was concentrated and recrystallized using methanol. The resulting solid was vacuum-dried (50°C, 16 hours) to obtain compound 17 (yield 0.88 g, yield 77%).

[0216] <Synthesis of Compound 23> Compound 23 was synthesized according to the following reaction equation.

[0217] [ka]

[0218] In a 200 mL three-necked flask, dipentaerythritol (11.80 mmol, 3.0 g), 4-fluorophenylacetic acid (74.33 mmol, 11.5 g), p-toluenesulfonic acid (7.43 mmol, 1.41 g), and toluene (59 mL) were added and stirred under reflux under a nitrogen atmosphere. After the reaction was complete, the resulting solution was neutralized with 1% aqueous sodium hydroxide solution. The organic layer was then washed with 8% aqueous sodium carbonate solution and pure water. The organic layer was dried over magnesium sulfate and filtered off. The resulting solution was concentrated, diluted with dichloromethane (10 mL), and methanol (75 mL) was added to precipitate a solid. The obtained solid was vacuum dried (50°C, 16 hours) to obtain intermediate 23-1 (yield 2.2 g, yield 17%).

[0219] In a 200 mL four-necked flask, intermediate 23-1 (0.93 mmol, 1.0 g), diazabicycloundecene (15.41 mmol, 2.34 g), and acetonitrile (48 ml) were added and stirred. Then, p-acetamidobenzenesulfonic acid azide (14.01 mmol, 3.37 g) was slowly added, and the mixture was stirred at room temperature for 12 hours. After stopping the reaction by adding pure water to the reaction mixture, the mixture was separated using ethyl acetate and pure water. The organic layer was dried over magnesium sulfate and filtered off. The resulting solution was concentrated and recrystallized using methanol. The resulting solid was vacuum-dried (50°C, 16 hours) to obtain compound 20 (yield 0.87 g, yield 75%).

[0220] [Evaluation of crosslinking reaction] The reaction initiation temperature and reaction completion time were evaluated for compounds 7, 14, 17, 20, and 23 synthesized above, as well as the comparative compounds listed below. The results are shown in Table 1.

[0221] [ka]

[0222] (Reaction initiation temperature) Compound 7, 14, 17, 20 or 23, or a comparative compound, was measured using a differential scanning calorimeter (DSC) (manufactured by Seiko Instruments Inc., trade name: DSC6000) with a temperature increase rate of 10 °C / min from room temperature to 320 °C in a profile. At the generated exothermic peak, the temperature at which the exothermic peak started was taken as the reaction start temperature.

[0223] (Reaction completion time) Compound 7, 14, 17, 20 or 23, or a comparative compound, was measured using a differential scanning calorimeter (DSC) (manufactured by Seiko Instruments Inc., trade name: DSC6000) with a temperature increase rate of 10 °C / min from room temperature to 140 °C and then held at 140 °C for 60 minutes in a profile. The time from when the temperature reached 140 °C to when the heat capacity reached 0 was taken as the reaction completion time.

[0224] [Table 1]

[0225] As shown in Table 1 above, it can be seen that the reactive organic compound according to the present invention has a lower reaction start temperature and a shorter reaction completion time compared to the comparative compound.

[0226] <Example 1> Referring to the sections "Synthesis of InP cores" and "Synthesis of InP / ZnSe / ZnS QDs" in the "Methods" section of Nature volume 575, pp634 - 638 (2019), a quantum dot dispersion was prepared (core species: InP, shell species: ZnSe / ZnS, quantum dot content in the dispersion: 2% by mass, maximum emission wavelength of the quantum dots: 627 nm, organic ligand of the quantum dots: oleic acid (SP value when coordinated to the quantum dot surface: 8.1 (cal / cm 3 ) 1 / 2(Average particle size of quantum dots: 10 nm; see below for a schematic of the structure). The oleic acid content in the quantum dots was 10% by mass, with the total mass of the quantum dots being 100% by mass. Ethanol was added to the obtained quantum dot dispersion to generate a precipitate and perform centrifugation. The supernatant was removed to obtain the precipitate.

[0227] [ka]

[0228] To the precipitate obtained above, 3 mL of cyclohexylbenzene was added as a solvent and the mixture was stirred with a shaker (mixing temperature: 25°C, mixing time: 10 minutes) to disperse the precipitate in the solvent. The quantum dot content (InP / ZnSe / ZnS) in the dispersion was 3% by mass. Compound 7 was added to the quantum dot content (3% by mass) to a total of 5% by mass to prepare ink composition 1.

[0229] <Example 2> Ink composition 2 was prepared in the same manner as in Example 1, except that compound 14 was used instead of compound 7, and compound 14 was added to a concentration of 1% by mass relative to the quantum dot content (3% by mass).

[0230] <Example 3> Ink composition 3 was prepared in the same manner as in Example 2, except that compound 20 was used instead of compound 14.

[0231] <Comparative Example 1> To the precipitate obtained in Example 1, 3 mL of cyclohexylbenzene was added as a solvent, and the mixture was stirred with a shaker (mixing temperature: 25°C, mixing time: 10 minutes) to disperse the precipitate in the solvent and prepare comparative ink composition 1. The quantum dot (InP / ZnSe / ZnS) content in comparative ink composition 1 was 3.0% by mass.

[0232] [Evaluation of Lamination Stability (Process Stability)] Ink composition 1, ink composition 2, or comparative ink composition 1 was applied by spin coating to a dry film thickness of 30 nm, and then heat-treated at 140°C for 30 minutes to form a thin film. The UV absorption spectrum of the thin film was measured. Next, a solvent (cyclohexylbenzene) was added dropwise to the thin film and allowed to permeate for 10 minutes. After removing the solvent, the UV absorption spectrum of the thin film was measured. The lamination stability was evaluated by dividing the spectral intensity after solvent addition by the spectral intensity before solvent addition (percentage). The results are shown in Table 2. In Table 2, the amount of reactive organic compound added is the amount relative to the quantum dot content (3 mass%).

[0233] [Table 2]

[0234] As shown in Table 2, thin films prepared using ink compositions 1 and 2 exhibit higher lamination stability compared to thin films prepared using comparative ink composition 1. Therefore, since dissolution during lamination can be suppressed in quantum dot light-emitting layers prepared using ink compositions 1 and 2, it is considered that process stability can be ensured by using ink compositions 1 and 2.

[0235] <Example 3> As the first electrode (anode), an ITO-coated glass substrate patterned with indium tin oxide (ITO) to a thickness of 150 nm was used. This ITO-coated glass substrate was sequentially washed with a neutral detergent, deionized water, water, and isopropyl alcohol, and then subjected to UV-ozone treatment. Next, poly(3,4-ethylenedioxythiophene) / poly(4-styrene sulfonate) (PEDOT / PSS) (manufactured by Sigma-Aldrich) was applied to this ITO-coated glass substrate by spin coating to a dry film thickness of 30 nm, and then dried. As a result, a hole injection layer with a thickness (dry film thickness) of 30 nm was formed on the ITO-coated glass substrate.

[0236] A 1.0 mass% toluene solution of polymer compound P-1 (hole transport material) was applied to this hole injection layer by spin coating to a dry film thickness of 30 nm, and then heat-treated at 230°C for 60 minutes to form a hole transport layer. As a result, a hole transport layer with a thickness (dry film thickness) of 30 nm was formed on the hole injection layer.

[0237] Polymer compound P-1 was synthesized in accordance with the manufacturing method described in Japanese Patent Publication No. 2024-82022. Polymer compound P-1 is presumed to have the following structure.

[0238] [ka]

[0239] The terminal structure of polymer compound P-1 is presumed to be one of the following structures.

[0240] [ka]

[0241] Ink composition 1 was applied to the hole transport layer by spin coating to a dry film thickness of 30 nm, and then dried. As a result, a quantum dot light-emitting layer with a thickness (dry film thickness) of 30 nm was formed on the hole transport layer. The light emitted when ultraviolet light was irradiated onto the quantum dot dispersion had a central wavelength of 462 nm and a full width at half maximum of 30 nm.

[0242] The quantum dot light-emitting layer was completely dried. A dispersion for forming an electron transport layer was prepared by dispersing ZnMgO in ethanol at a concentration of 1.5% by mass. This dispersion was applied to the quantum dot light-emitting layer by spin coating to a dry film thickness of 60 nm, and then dried. As a result, an electron transport layer with a dry film thickness of 60 nm was formed on the quantum dot light-emitting layer.

[0243] Using a vacuum deposition apparatus, (8-quinolinolate)lithium (lithium quinolate) (Liq) was deposited onto this electron transport layer. As a result, an electron injection layer with a thickness of 0.5 nm was formed on the electron transport layer.

[0244] Using a vacuum deposition apparatus, aluminum (Al) was deposited onto this electron injection layer. As a result, a second electrode (cathode) with a thickness of 100 nm was formed on the electron injection layer. This yielded a quantum dot electroluminescent device 1.

[0245] <Comparative Example 2> In Example 3, the same procedure as in Example 3 was followed, except that comparative ink composition 1 was used instead of ink composition 1, to fabricate a comparative quantum dot electroluminescent element 1.

[0246] [Evaluation of device performance] (Luminous properties) When a voltage is applied to each quantum dot electroluminescent element, a current begins to flow at a constant voltage, causing the quantum dot electroluminescent element to emit light. When a voltage is applied to each quantum dot electroluminescent element using a DC constant voltage power supply (KEYENCE, source meter), a current begins to flow at a constant voltage, causing the quantum dot electroluminescent element to emit light. While measuring the light emission of each element using a luminance meter (Topcon, SR-3), the current is gradually increased until the luminance reaches 650 nits (cd / m²). 2 The current was kept constant when the voltage reached 650 nits, and the device was left unattended. In Table 3, the difference between the initial voltage (V) at which the brightness reached 650 nits and the voltage (V) after 100 hours is defined as "ΔV@100hr", and the change per hour from the initial voltage (V) is defined as "ΔV / hr".

[0247] (Luminous lifespan) Using a DC constant voltage power supply (Source Meter, manufactured by Keyence Corporation), a predetermined voltage was applied to each quantum dot electroluminescent element, causing each element to emit light. While measuring the light emitted by the quantum dot electroluminescent elements with a luminance measuring device (SR-3, manufactured by Topcon Corporation), the current was gradually increased until the luminance reached 650 nits (cd / m²). 2 The current was kept constant once the luminance reached 650 nits, and the device was left undisturbed. In Table 3, the time it took for the luminance value measured by the luminance measuring device to gradually decrease to 90% of the initial luminance (650 nits) was defined as "Max. T90 (hr)".

[0248] [Table 3]

[0249] The results in Table 3 show that the quantum dot electroluminescent element of Example 3, by incorporating a light-emitting layer formed using the ink composition according to the present invention, exhibited suppressed performance degradation. Specifically, the quantum dot electroluminescent element of Example 3 showed approximately 1.3 times improvement in element life and suppressed increase in drive voltage compared to the quantum dot electroluminescent element of Comparative Example 2. [Explanation of Symbols]

[0250] 100 quantum dot electroluminescent elements (QD-LEDs), 110 boards, 120 first electrode, 130 hole injection layer, 140 Hole transport layer, 150 luminescent layers, 160 electron transport layer, 170 electron injection layer, 180 Second electrode.

Claims

1. An ink composition comprising quantum dots, a reactive organic compound, and a solvent. The quantum dots do not contain cadmium (Cd) or lead (Pb), the average particle size of the quantum dots is 1 nm or more and 15 nm or less, and the content of the quantum dots is 0.1% by mass or more and 10.0% by mass or less, based on 100% by mass of the total mass of the ink composition. The reactive organic compound is a compound represented by the following formula (1): 【Chemistry 1】 In the above formula (1), Ar １ This is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms. L １ It is a single bond, or an oxygen atom, L ２ This is a single bond, or a saturated hydrocarbon group having 1 to 60 carbon atoms, or a saturated hydrocarbon group having 6 to 60 carbon atoms, either substituted or unsubstituted. X is a group selected from the group consisting of the following formulas (1-1) to (1-37), 【Chemistry 2】 【Transformation 3】 In the above formulas (1-1) to (1-37), * represents a bonding site. In the above formulas (1-1) to (1-5), (1-7), (1-12), (1-19), (1-22), (1-23), (1-27), and (1-28), a １ Each of these independently represents an integer between 2 and 4, In the above formulas (1-6), (1-8), (1-9), (1-13) to (1-15), (1-20), (1-25), and (1-30), a ２ Each of these independently represents an integer between 1 and 3, and a ３ Each independently represents either 1 or 2, and a ２ and a ３ The sums of these two values ​​are, independently, 2, 3, or 4. In the above formulas (1-10), (1-16), (1-17), (1-21), (1-26), and (1-31), a ４ each independently represents 1 or 2, a ５ represents 1, a ６ each independently represents 1 or 2, a ４ and a ５ and a ６ and the sum of are each independently 3 or 4, In the above formulas (1-24) and (1-29), a ７ Each of these independently represents an integer between 1 and 3, and a ８ Each of these independently represents an integer between 1 and 3, and a ７ and a ８ The sums of these two values ​​are, independently, 2, 3, or 4. In the above formula (1-32), a ９ is an integer between 2 and 18, In the above formula (1-37), a １０ is 1 or 2, a １１ This represents 1 or 2, In the above formulas (1-5) and (1-6), Ar ２ Each of these is independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms. In the above equations (1-27) to (1-31), Y is independently -O-, -S-, and -C(CH) ３ ) ２ - or a diphenylmethylene group, The content of the reactive organic compound is 0.1% by mass or more and 10.0% by mass or less, with the mass of the quantum dots in the ink composition being 100% by mass. The solvent comprises at least one compound selected from those represented by the following formulas (2) to (5): 【Chemistry 4】 In the above formula (2), R １ b is a linear or branched saturated hydrocarbon group having 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon group having 3 to 12 carbon atoms, and b represents an integer between 1 and 3. 【Transformation 5】 In the above formula (3), R ２ This is a linear or branched saturated hydrocarbon group having 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon group having 3 to 12 carbon atoms. 【Transformation 6】 In the above formula (4), c represents an integer between 6 and 18, 【Transformation 7】 In the above formula (5), Z is -OH, -COOH, -NH ２ An ink composition that is either -SH or -SH, where d represents an integer between 7 and 17.

2. X is a group selected from the group consisting of the following formulas (1-38) to (1-105), 【Transformation 8】 【Chemistry 9】 【Chemistry 10】 In the above formulas (1-53) and (1-54), Ar ２ Each of these is independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms. In the above equations (1-100) to (1-102), Y is independently -O-, -S-, and -C(CH) ３ ) ２ - or a diphenylmethylene group, The aforementioned R １ This is a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms. The aforementioned R ２ The ink composition according to claim 1, wherein is a linear or branched saturated hydrocarbon group having 6 to 10 carbon atoms or a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms.

3. The surface of the quantum dot is coordinated with at least one organic ligand selected from the group consisting of alkyl halides, thiol group-containing compounds, and aliphatic carboxylic acid compounds. The ink composition according to claim 1, wherein the content of the organic ligand in the quantum dot is 30% by mass or less, with the mass of the quantum dot being 100% by mass.

4. A quantum dot electroluminescent element comprising a light-emitting layer formed using the ink composition described in claim 1.

5. A quantum dot electroluminescent element comprising a light-emitting layer formed by an inkjet device using the ink composition described in claim 1.

6. An image display device comprising the quantum dot electroluminescent element according to claim 4 or 5.

7. A method for manufacturing a quantum dot electroluminescent element, comprising a light-emitting layer formed using the ink composition described in claim 1, The light-emitting layer is formed using an inkjet device, in a manufacturing method.

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