Ink Composition

Abstract

One embodiment has the objective of providing a technology that can achieve both process stability during the manufacture of a quantum dot electroluminescent device and the performance of the quantum dot electroluminescent device, such as luminescence characteristics and device lifespan. To solve the above problem, one embodiment provides an ink composition comprising a quantum dot, a reactive organic compound, and a solvent, wherein the quantum dot does not contain cadmium (Cd) and lead (Pb), and the reactive organic compound is a compound represented by the following formula (1): In the above formula (1), Ar1, L1, L2, and X are each as described in the specification.

Description

Technology Field

[0001] This concerns an ink composition. Background Technology

[0002] Recently, quantum dots have attracted attention as vivid RGB light sources covering a wide color gamut, and electroluminescent devices using quantum dots in the light-emitting layer (hereinafter also referred to as quantum dot electroluminescent devices) are being actively researched and developed as thin-film, lightweight, and low-power display and lighting devices.

[0003] When realizing a quantum dot electroluminescent device, it is important to laminate a quantum dot emitting layer between an anode and a cathode as a thin film with a thickness of several nanometers to several hundred nanometers, and it is also required to achieve precise interface formation with surrounding layers such as a hole transport layer and an electron transport layer. Typically, the quantum dot emitting layer is deposited by coating methods such as spin coating or inkjet methods. Development of ink compositions containing quantum dots used in the manufacture of such quantum dot electroluminescent devices is underway (see Patent Documents 1–8). Prior art literature

[0004] [Patent Document 1] Specification of Chinese Patent Application Publication No. 109306207 [Patent Document 2] International Publication No. 2019 / 225782 [Patent Document 3] Japanese Published Patent No. 2019-81868 [Patent Document 4] Japanese Published Patent No. 2020-41079 [Patent Document 5] Specification of U.S. Patent Application Publication No. 2018 / 0230321 [Patent Document 6] Japanese Published Patent No. 2017-043526 [Patent Document 7] Specification of Chinese Patent No. 107400414 [Patent Document 8] Specification of Chinese Patent No. 105907180 The problem to be solved

[0005] In a stacking process using the coating method, it is necessary to suppress the dissolution of the quantum dot light-emitting layer by the solvent when forming the upper layer of the quantum dot light-emitting layer. This is because if the quantum dot light-emitting layer dissolves, the interface between the upper layer and the quantum dot light-emitting layer becomes disrupted, which is one of the causes of reduced luminous efficiency and device lifespan.

[0006] In stacking processes using the coating method, there have been attempts to cross-link quantum dots to suppress the dissolution of the quantum dot light-emitting layer in solvents (process stability). However, this has not reached a fundamental solution because it can degrade the performance of quantum dot electroluminescent devices (e.g., light emission characteristics and device lifespan).

[0007] Accordingly, one embodiment aims to provide a technology that can achieve both process stability during the manufacturing of a quantum dot electroluminescent device and the performance of the quantum dot electroluminescent device (e.g., luminescence characteristics and device lifespan). means of solving the problem

[0008] One embodiment is an ink composition comprising quantum dots, a reactive organic compound, and a solvent, wherein the quantum dots do not contain cadmium (Cd) and lead (Pb), and the reactive organic compound is represented by the following formula (1):

[0009]

[0010] In the above equation (1),

[0011] Ar1 is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms, and

[0012] L1 is a single bond, or oxygen atom, and

[0013] L2 is a single bond, 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, and

[0014] X is a group selected from the groups represented by the following formulas (1-1) to (1-37):

[0015]

[0016]

[0017] Among the above formulas (1-1) to (1-37), * indicates a joining part,

[0018] Among the above equations (1-1) to (1-5), equation (1-7), equation (1-12), equation (1-19), equation (1-22), equation (1-23), equation (1-27), and equation (1-28), a1 each independently represents an integer between 2 and 4, and

[0019] Among the above equations (1-6), (1-8), (1-9), (1-13) to (1-15), (1-20), (1-25), and (1-30), a2 each independently represents an integer between 1 and 3 inclusive, a3 each independently represents 1 or 2, and the sum of a2 and a3 each independently is 2, 3, or 4.

[0020] Among the above equations (1-10), (1-16), (1-17), (1-21), (1-26), and (1-31), a4 represents 1 or 2, a5 represents 1, a6 represents 1 or 2, and the sum of a4, a5, and a6 is 3 or 4, respectively, and

[0021] In the above equations (1-24) and (1-29), a7 each independently represents an integer between 1 and 3, a8 each independently represents an integer between 1 and 3, and the sum of a7 and a8 each independently is 2, 3, or 4.

[0022] In the above equation (1-32), a9 is an integer between 2 and 18, and

[0023] Among the above formula (1-37), a 10 represents 1 or 2, and a 11 represents 1 or 2, and

[0024] In the above formulas (1-5) and (1-6), Ar2 is, respectively, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms, and

[0025] In the above formulas (1-27) to (1-31), Y is each independently -O-, -S-, -C(CH3)2- or diphenylmethylene group.

[0026] The above solvent comprises one or more of the compounds represented by the following formulas (2) to (5):

[0027]

[0028] Among the above formula (2),

[0029] R1 is a straight-chain or branched saturated hydrocarbon group having 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon group having 3 to 12 carbon atoms, and

[0030] b represents an integer between 1 and 3, and

[0031]

[0032] Among the above formula (3),

[0033] R2 is a straight-chain or branched saturated hydrocarbon group having 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon group having 3 to 12 carbon atoms, and

[0034]

[0035] In the above formula (4), c represents an integer between 6 and 18, and

[0036]

[0037] Among the above formula (5),

[0038] Z is -OH, -COOH, -NH2 or -SH, and

[0039] d represents an integer between 7 and 17.

[0040] The average particle size of the above quantum dots is 1 nm or more and 15 nm or less, and the content of the above quantum dots is 0.1 mass% or more and 10.0 mass% or less based on the total mass of the ink composition.

[0041] The content of the above reactive organic compound is 0.1 parts by mass or more and 10.0 parts by mass or less, when the mass of the above quantum dots in the ink composition is 100 parts by mass. Effects of the invention

[0042] According to one embodiment, process stability during the manufacture of a quantum dot electroluminescent device and the performance of the quantum dot electroluminescent device, such as light emission characteristics and device lifespan, can be achieved simultaneously. Brief explanation of the drawing

[0043] FIG. 1 is a schematic cross-sectional view showing a quantum dot electroluminescent device according to one embodiment. Specific details for implementing the invention

[0044] Hereinafter, examples of one embodiment are described. One embodiment is not limited to the following examples. Also, unless specifically stated otherwise, operations and measurements of physical properties are performed under conditions of room temperature (20°C or higher and 25°C or lower) and relative humidity of 40%RH or higher and 50%RH or lower.

[0045] [Ink Composition]

[0046] One embodiment is an ink composition comprising quantum dots, a reactive organic compound, and a solvent, wherein the quantum dots do not contain cadmium (Cd) and lead (Pb), and the reactive organic compound is represented by the following formula (1):

[0047]

[0048] Among the above formula (1),

[0049] Ar1 is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms, and

[0050] L1 is a single bond, or oxygen atom, and

[0051] L2 is a single bond, 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, and

[0052] X is a group selected from the groups consisting of the following formulas (1-1) to (1-37):

[0053]

[0054]

[0055] Among the above formulas (1-1) to (1-37), * indicates a joining part,

[0056] Among the above equations (1-1) to (1-5), equation (1-7), equation (1-12), equation (1-19), equation (1-22), equation (1-23), equation (1-27), and equation (1-28), a1 each independently represents an integer between 2 and 4, and

[0057] Among the above equations (1-6), (1-8), (1-9), (1-13) to (1-15), (1-20), (1-25), and (1-30), a2 each independently represents an integer between 1 and 3 inclusive, a3 each independently represents 1 or 2, and the sum of a2 and a3 each independently is 2, 3, or 4.

[0058] Among the above equations (1-10), (1-16), (1-17), (1-21), (1-26), and (1-31), a4 represents 1 or 2, a5 represents 1, a6 represents 1 or 2, and the sum of a4, a5, and a6 is 3 or 4, respectively, and

[0059] In the above equations (1-24) and (1-29), a7 each independently represents an integer between 1 and 3, a8 each independently represents an integer between 1 and 3, and the sum of a7 and a8 each independently is 2, 3, or 4.

[0060] In the above equation (1-32), a9 is an integer between 2 and 18, and

[0061] Among the above formula (1-37), a 10 represents 1 or 2, and a 11 represents 1 or 2, and

[0062] In the above formulas (1-5) and (1-6), Ar2 is, respectively, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms, and

[0063] In the above formulas (1-27) to (1-31), Y is each independently -O-, -S-, -C(CH3)2- or diphenylmethylene group.

[0064] The above solvent comprises one or more of the compounds represented by the following formulas (2) to (5):

[0065]

[0066] Among the above formula (2),

[0067] R1 is a straight-chain 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 from 1 to 3.

[0068]

[0069] Among the above formula (3),

[0070] R2 is a straight-chain or branched saturated hydrocarbon group having 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon group having 3 to 12 carbon atoms, and

[0071]

[0072] In the above formula (4), c represents an integer between 6 and 18, and

[0073]

[0074] Among the above formula (5),

[0075] Z is -OH, -COOH, -NH2 or -SH, and

[0076] d represents an integer between 7 and 17.

[0077] The average particle size of the above quantum dots is 1 nm or more and 15 nm or less, and the content of the above quantum dots is 0.1 mass% or more and 10.0 mass% or less based on the total mass of the ink composition.

[0078] The content of the above reactive organic compound is 0.1 parts by mass or more and 10.0 parts by mass or less, when the mass of the above quantum dots in the ink composition is 100 parts by mass.

[0079] By having the above-described configuration, the ink composition according to one embodiment can achieve both process stability during the manufacture of a quantum dot electroluminescent device and the performance of the quantum dot electroluminescent device, such as luminescence characteristics and device lifespan.

[0080] Although not intended to be bound by a specific theory, the mechanism by which the above problem is solved by an ink composition (quantum dot ink composition) according to one embodiment can be estimated as follows.

[0081] When fabricating quantum dot electroluminescent devices using a wet coating method, such as an inkjet method, the device is fabricated by repeating the process of applying and drying a liquid. When a liquid containing a solvent is applied to form a different layer on a dried film (quantum dot layer) containing quantum dots, the solvent penetrates the quantum dot layer, causing dissolution of the quantum dot layer and resulting in intermixing between the upper layer and the quantum dot layer. When intermixing occurs, the device characteristics deteriorate. Therefore, it is believed that intermixing can be suppressed by making the quantum dot layer robust. The inventors of the present invention believed that the quantum dot layer could be made robust and intermixing suppressed by using a compound capable of cross-linking quantum dots. However, when a compound having an azide group (-N3) (e.g., J. Yang, et al, Nat. Commun., 11(2020)2874.) is used to cross-link quantum dots to each other, the structure after cross-linking contains an amine, and active protons remain. The inventors of the present invention have discovered that device characteristics deteriorate due to the presence of active protons. On the other hand, when a reactive organic compound having a diazo group (=N2) is used, the structure after crosslinking does not contain amines, and active protons do not remain. As a result, the deterioration of the quantum dot electroluminescent device caused by the presence of active protons can be suppressed, so the ink composition according to one embodiment is thought to be able to achieve both process stability during the manufacture of the quantum dot electroluminescent device and the performance of the quantum dot electroluminescent device, such as luminescence characteristics and device lifespan.

[0082] The above mechanism is based on conjecture, and one embodiment is not bound by the above mechanism at all.

[0083] Hereinafter, the composition of an ink composition according to one embodiment is described in detail.

[0084] (Quantum Dot)

[0085] An ink composition according to one embodiment includes quantum dots. The quantum dots (semiconductor nanoparticles) are semiconductor nanoparticles of a predetermined size having a quantum confinement effect.

[0086] Quantum dots (semiconductor nanoparticles) can be synthesized by wet chemical processes, organometallic chemical vapor deposition processes, molecular beam epitaxy processes, or other similar processes. Among these, the wet chemical process is a method of growing particles by adding a precursor material to an organic solvent.

[0087] In wet chemical processes, as crystals grow, organic solvents naturally coordinate to the surface of quantum dot crystals and act as dispersants, thereby controlling the growth of the crystals. For this reason, wet chemical processes allow for the easy and low-cost control of semiconductor nanoparticle growth compared to vapor deposition methods such as Metal Organic Chemical Vapor Deposition (MOCVD) or Molecular Beam Epitaxy (MBE).

[0088] By controlling the size of quantum dots (semiconductor nanoparticles), the energy bandgap can be adjusted, allowing light of various wavelengths to be obtained from the light-emitting layer (quantum dot light-emitting layer). Therefore, by using multiple quantum dots of different sizes, a display capable of emitting (or emitting) light of multiple wavelengths is made possible. The sizes of the quantum dots can be selected to emit red, green, and blue light so as to enable the configuration of a color display. Additionally, the sizes of the quantum dots can be combined so that various colors of light emit white light.

[0089] Quantum dots do not contain cadmium (Cd) and lead (Pb). As quantum dots, semiconductor materials selected from group II-VI semiconductor compounds; group III-V semiconductor compounds; group IV-VI semiconductor compounds; group IV elements or compounds; or combinations thereof may be included.

[0090] Group II-VI semiconductor compounds may be selected from, for example, binary compounds selected from ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, or mixtures thereof, but are not particularly limited; ternary compounds selected from ZnSeS, ZnTeSe, ZnSTe, HgSeS, HgSeTe, HgSTe, HgZnS, HgZnSe, HgZnTe, or mixtures thereof; or quaternary compounds selected from HgZnSeS, HgZnSeTe, HgZnSTe, or mixtures thereof.

[0091] III-V semiconductor compounds may be selected from, but are not particularly limited, binary compounds selected from, for example, GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, or mixtures thereof; ternary compounds selected from GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, or mixtures thereof; or quaternary compounds selected from GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, or mixtures thereof.

[0092] Group IV-VI semiconductor compounds may be selected from, for example, binary compounds selected from SnS, SnSe, SnTe, or mixtures thereof, but are not particularly limited; or ternary compounds selected from SnSeS, SnSeTe, SnSTe, or mixtures thereof.

[0093] Group IV elements or compounds may be selected from, for example, mono-element compounds selected from Si, Ge, or mixtures thereof, but are not particularly limited; or binary compounds selected from SiC, SiGe, or mixtures thereof.

[0094] Quantum dots may be composed of one type of compound, or may contain two or more types of compounds. Additionally, they may have a core-shell type structure having, for example, a core containing a semiconductor compound and a shell containing a semiconductor compound different from the core. To ensure that excitons are confined to the core, the semiconductor compound constituting the shell may include a material with a higher bandgap than the semiconductor compound forming the core, thereby increasing the luminescence efficiency of the quantum dots. Examples of core-shell structures (core / shell) having such a relationship of bandgap size include InP / ZnS, CuInS / ZnS, ZnTeSe / ZnSe / ZnS, InP / ZnSe / ZnS, etc.

[0095] The average particle size (average diameter) of the quantum dots may be 1 nm or more and 15 nm or less. From the perspective of luminescence properties and dispersion stability of the quantum dots, the average particle size (average diameter) of the quantum dots may be 7 nm or more and 15 nm or less. The average particle size of the quantum dots in this specification is determined by using a transmission electron microscope (TEM) to measure the diameter of a circle having an area equal to the projected area of ​​100 particles, and using the arithmetic mean of these values. An example of a method for calculating the average particle size of the quantum dots is provided below:

[0096] (1) A quantum dot dispersion that does not contain reactive organic compounds is dropped onto a grid for a TEM measurement sample table, and a measurement sample is prepared;

[0097] (2) Using a TEM (e.g., HT7800 series manufactured by Hitachi Hitech), a measurement sample is photographed (magnification of 20,000x or more); and,

[0098] (3) Measure the diameter of a circle that has the same area as the projected area of ​​100 particles, and calculate the arithmetic mean of these values.

[0099] As quantum dots, an organic ligand having a coordinating group can be used on the surface. When synthesizing quantum dots, by adding an organic ligand to the raw material solution of the quantum dots, excessive crystal growth can be prevented, thereby obtaining quantum dots within the desired particle size range. In addition, quantum dots having a surface layer containing an organic ligand on the surface can prevent aggregation after synthesis.

[0100] The organic ligand may include an organic compound having a coordinating group that binds to a cation contained in the quantum dot. Examples of coordinating groups include a halogen atom, a carboxyl group, a carboxylic acid anhydride group, an amino group, an ammonium group, a thiol group (sulfanyl group), a sulfide group, a sulfoxide group, a phosphine group, a phosphine oxide group, a phosphate group, a phosphonic acid group, a phosphinic acid group, a sulfonic acid group, a boric acid group, a heterocyclic group, etc. Such organic ligands may be included as a single type or in combination of two or more types.

[0101] Examples of compounds containing halogen atoms include alkyl halides having straight-chain or branched alkyl groups with 1 to 30 carbon atoms. Specific examples of such alkyl halides include, for instance, 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, decyl chloride, etc.

[0102] Examples of carboxyl group-containing compounds include straight-chain or branched aliphatic carboxylic acid compounds with 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-hexenic acid, trans-2-hexenic acid, 2-hepteneic acid, 3-hepteneic acid, 2-hexadecenoic acid, linolenic acid, linoleic acid, γ-linolenic acid, 3-noneneic acid, 2-noneneic acid, trans-2-octenic acid, petroselinic acid, elaidic acid, oleic acid, 3-octenic acid, There are trans-2-pentene acid, trans-3-pentene acid, ricinoleic acid, sorbic acid, 2-tridecenoic acid, cis-15-tetracosenic acid, 10-undecenic acid, 2-undecenic acid, acetic acid, butyric acid, behenic acid, cerotic acid, decanoic acid, arachidic acid, heneicosanic acid, heptadecanic acid, heptanoic acid, hexanoic acid, heptacosanic acid, lauric acid, myristic acid, melisic acid, octacosanic acid, nonadecanic acid, nonacosanic acid, n-octosanic acid, palmitic acid, pentadecanic acid, propionic acid, pentacosanic acid, nonanoic acid, stearic acid, lignoceric acid, tricosanic acid, tridecanoic acid, undecanic acid, valeric acid, etc.

[0103] As amino group-containing compounds, for example, there are aliphatic amine compounds having straight-chain or branched alkyl groups 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, 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, There are n-octadecylamine, tri(n-hexyl)amine, tri(n-octyl)amine, tri(n-decyl)amine, etc.

[0104] Examples of thiol group-containing compounds include 1-hexanethiol, 1-octanthiol, 1-dodecanethiol, etc.

[0105] Examples of compounds containing sulfide groups include dialkyl sulfides such as dibutyl sulfide.

[0106] Examples of compounds containing sulfoxide groups include dialkyl sulfoxides such as dimethyl sulfoxide and dibutyl sulfoxide.

[0107] Examples of phosphine group-containing compounds include trialkylphosphines such as tripropylphosphine, tributylphosphine, trihexylphosphine, and trioctylphosphine.

[0108] Examples of compounds containing phosphine oxide groups include trialkylphosphines such as tripropylphosphine oxide, tributylphosphine oxide, trihexylphosphine oxide, trioctylphosphine oxide, and tridecylphosphine oxide.

[0109] Examples of complex compounds containing a heterocyclic group include nitrogen-containing heterocyclic compounds such as pyridine, ruthidin, coridine, and quinoline; sulfur-containing heterocyclic compounds such as thiophene.

[0110] Among these organic ligands, at least one selected from alkyl halide compounds, thiol group-containing compounds, aliphatic carboxylic acid compounds, or combinations thereof may be included in terms of dispersion stability and luminescence properties of the quantum dot. In one embodiment, the surface of the quantum dot may be coordinated with at least one organic ligand selected from alkyl halide compounds, thiol group-containing compounds, aliphatic carboxylic acid compounds, or combinations thereof. Additionally, for example, the organic ligand may be at least one selected from oleic acid, heptanoic acid, hexanoic acid, heptacosonic acid, lauric acid, 1-hexanethiol, 1-octanthiol, 1-dodecanethiol, or combinations thereof.

[0111] The content of organic ligands in the quantum dots is not particularly limited. From the perspective of controlling film thickness after ejection in an inkjet device, the content of organic ligands in the quantum dots may be, for example, 30 parts by mass or less, for example, 20 parts by mass or less, or 15 parts by mass or less, when the mass of the quantum dots is 100 parts by mass. The content of organic ligands in the quantum dots may be, for example, 1 part by mass or more when the mass of the quantum dots is 100 parts by mass. For example, when the mass of the quantum dots is 100 parts by mass, it may be 3 parts by mass or more, 5 parts by mass or more, 10 parts by mass or more, or 15 parts by mass or more. For example, the content of organic ligands in the quantum dots may be 1 part by mass or more and 30 parts by mass or less when the mass of the quantum dots is 100 parts by mass, for example, 1 part by mass or more and 25 parts by mass or less, 3 parts by mass or more and 25 parts by mass or less, 5 parts by mass or more and 30 parts by mass or less, 5 parts by mass or more and 25 parts by mass or less, 10 parts by mass or more and 30 parts by mass or less, 10 parts by mass or more and 25 parts by mass or less, 10 parts by mass or more and 20 parts by mass or less, 15 parts by mass or more and 30 parts by mass or less, or 15 parts by mass or more and 25 parts by mass or less, and is not limited to these ranges.

[0112] In one embodiment, the surface of the quantum dot is coordinated with at least one organic ligand selected from an alkyl halide compound, a thiol group-containing compound, an aliphatic carboxylic acid compound, or a combination thereof, and the content of the organic ligand in the quantum dot may be 30 parts by mass or less when the mass of the quantum dot is 100 parts by mass.

[0113] Quantum dots having organic ligands having coordinating groups on their surface can be synthesized by methods described, for example, in J. Am. Chem. Soc., 115, pp8706-8715 (1993), J. Phys. Chem., 101, pp9463-9475 (1997), Nature volume 575, pp634-638 (2019), etc. In addition, commercially available ones may also be used.

[0114] The content of quantum dots in the ink composition according to one embodiment may be 0.1 mass% or more and 10.0 mass% or less based on the total mass of the ink composition, for example, 0.5 mass% or more and 8.0 mass% or less, for example, 1.0 mass% or more and 6.0 mass% or less, for example, 1.0 mass% or more and 5.0 mass% or less, for example, 2.0 mass% or more and 5.0 mass% or less, and is not limited to these ranges.

[0115] (Reactive organic compounds)

[0116] An ink composition according to one embodiment includes a reactive organic compound. The reactive organic compound is a compound represented by the following formula (1). As described above, when quantum dots are crosslinked using the reactive organic compound according to one embodiment, no active protons remain in the structure after crosslinking. Additionally, although quantum dots are sensitive to heating, heat is required for the crosslinking reaction when crosslinking between quantum dots. As shown in the examples described below, the reactive organic compound according to one embodiment enables the crosslinking reaction at a lower temperature than a compound having an azide group, so the crosslinking reaction can be completed more quickly.

[0117]

[0118] Among the above formula (1),

[0119] Ar1 is a substituted or unsubstituted aromatic hydrocarbon group with 6 to 60 carbon atoms.

[0120] In Ar1, as an aromatic hydrocarbon group, it is not particularly limited as long as it is an aromatic hydrocarbon group with 6 or more and 60 or fewer carbon atoms (ring-forming carbon atoms). Specific examples of cases where Ar1 is unsubstituted include monovalent groups derived from aromatic hydrocarbons such as benzene, pentylene, indene, naphthalene, anthracene, azulene, heptylene, acenaphthene, phenalene, fluorene, phenanthrin, biphenyl, terphenyl, quaternphenyl, quinquephenyl, sexphenyl, pyrene, 9,9-diphenylfluorene, 9,9'-spirobi[fluorene], 9,9-dialkyl fluorene, and indeno[1,2-b]fluorene. Ar1 may be a monovalent group derived from a compound selected from benzene, fluorene, biphenyl, terphenyl, indeno[1,2-b]fluorene, or a combination thereof. For example, Ar1 may be a monovalent group derived from a compound selected from benzene, fluorene, biphenyl, indeno[1,2-b]fluorene, or a combination thereof. In one embodiment, Ar1 may be a monovalent group derived from benzene.

[0121] When any one hydrogen atom in Ar1 is substituted, the number of substituents introduced is not particularly limited, but, for example, it may be 1 or more and 3 or less, for example, 1 or more and 2 or less, for example, 1. In one embodiment, Ar1 is unsubstituted. In another embodiment, Ar1 may have 1 substituent. When Ar1 has a substituent, the bonding position of the substituent is not particularly limited.

[0122] When Ar1 has a substituent, the substituents that may be present are not particularly limited, and examples 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. Also, the substituents are not identical to the group being substituted. For example, an alkyl group is not substituted with an alkyl group.

[0123] As for the alkyl group, it can be either a straight chain or a branched one, but for example, a straight chain with 1 to 18 carbon atoms or a branched alkyl group with 3 to 18 carbon atoms can be given. For example, 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, 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, Examples include 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, n-octadecyl group, etc.

[0124] Examples of cycloalkyl groups include cyclopropyl groups, cyclobutyl groups, cyclopentyl groups, cyclohexyl groups, etc.

[0125] As for the hydroxyalkyl group, for example, the alkyl group may be substituted with 1 or more and 3 or less, for example, 1 or more and 2 or less, for example, a single hydroxyl group, for example, a hydroxymethyl group or a hydroxyethyl group may be exemplified.

[0126] As for the alkoxyalkyl group, for example, the alkyl group may be substituted with one or more than three, for example, one or more than two, for example, one alkoxy group.

[0127] Examples of alkoxy groups include, for instance, methoxy groups, ethoxy groups, propoxy groups, isopropoxy groups, butoxy groups, pentyloxy groups, hexyloxy groups, heptyloxy groups, octyloxy groups, nonyloxy groups, decyloxy groups, undecyloxy groups, dodecyloxy groups, tridecyloxy groups, tetradecyloxy groups, pentadecyloxy groups, hexadecyloxy groups, heptadecyloxy groups, octadecyloxy groups, 2-ethylhexyloxy groups, 3-ethylpentyloxy groups, etc.

[0128] Examples of cycloalkoxy groups include cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, and cyclohexyloxy groups.

[0129] Examples of alkenyl groups include vinyl groups, allyl groups, 1-propenyl groups, isopropenyl groups, 1-butenyl groups, 2-butenyl groups, 3-butenyl groups, 1-pentenyl groups, 2-pentenyl groups, 3-pentenyl groups, 1-hexenyl groups, 2-hexenyl groups, 3-hexenyl groups, 1-heptenyl groups, 2-heptenyl groups, 5-heptenyl groups, 1-octenyl groups, 3-octenyl groups, 5-octenyl groups, etc.

[0130] Examples of alkynyl groups include, for instance, 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-hexinyl group, 2-hexinyl group, 3-hexinyl group, 1-heptinyl group, 2-heptinyl group, 5-heptinyl group, 1-octinyl group, 3-octinyl group, 5-octinyl group, etc.

[0131] Examples of aryl groups include, for instance, phenyl group, naphthyl group, biphenyl group, fluorenyl group, anthryl group, pyrenyl group, azulenyl group, acenaphthylenyl group, terphenyl group, phenanthyl group, etc.

[0132] Examples of aryloxy groups include phenoxy groups and naphthyloxy groups.

[0133] Examples of alkyl thio groups include methyl thio, ethyl thio, propyl thio, pentyl thio, hexyl thio, octyl thio, dodecyl thio, etc.

[0134] Examples of cycloalkylthio groups include cyclopentylthio groups and cyclohexylthio groups.

[0135] Examples of arylthio groups include, for instance, phenylthio groups and naphthylthio groups.

[0136] Examples of alkoxycarbonyl groups include methyloxycarbonyl groups, ethyloxycarbonyl groups, butyloxycarbonyl groups, octyloxycarbonyl groups, dodecyloxycarbonyl groups, etc.

[0137] Examples of aryloxycarbonyl groups include phenyloxycarbonyl groups, naphthyloxycarbonyl groups, etc.

[0138] Examples of halogen groups include fluoro groups, chloro groups, bromo groups, iodine groups, etc.

[0139] The substituent that may exist when any one of the hydrogen atoms in Ar1 is substituted may be a straight-chain or branched alkyl group or a halogen group having 1 to 8 carbon atoms, for example, a straight-chain or branched alkyl group or a halogen group having 1 to 3 carbon atoms, for example, a methyl group or a fluoro group.

[0140] In the above formula (1), L1 may be a single bond or an oxygen atom. For example, L1 may be an oxygen atom.

[0141] In the above formula (1), L2 may be a single bond, 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.

[0142] In L2, saturated hydrocarbon groups with 1 to 60 carbon atoms are not particularly limited. Examples of L2 (unsubstituted) include methylene groups, ethylene groups, trimethylene groups, propylene groups, tetramethylene groups, pentamethylene groups, hexamethylene groups, heptamethylene groups, octamethylene groups, etc.

[0143] In L2, the aromatic hydrocarbon group is not particularly limited as long as it is an aromatic hydrocarbon group with 6 or more and 60 or fewer carbon atoms (ring-forming carbon atoms). Specific examples of cases where L2 is unsubstituted include divalent groups derived from aromatic hydrocarbons such as benzene, pentarene, indene, naphthalene, anthracene, azulene, heptalene, acenaphthene, phenalene, fluorene, phenanthrin, biphenyl, terphenyl, quaternphenyl, quinquephenyl, sexphenyl, pyrene, 9,9-diphenylfluorene, 9,9'-spirobi[fluorene], 9,9-dialkylfluorene, indeno[1,2-b]fluorene. L2 may be a divalent group derived from a compound selected from benzene, fluorene, biphenyl, terphenyl, indeno[1,2-b]fluorene, or a combination thereof. For example, L2 may be a divalent group derived from a compound selected from benzene, fluorene, biphenyl, indeno[1,2-b]fluorene, or a combination thereof. In one embodiment, Ar1 may be a divalent group derived from benzene.

[0144] The substituents that may exist when L2 has a substituent are the same as the definition in Ar1 above. The substituents that may exist when L2 has a substituent may be straight-chain or branched alkyl groups with 1 to 8 carbon atoms, and for example, straight-chain or branched alkyl groups with 1 to 3 carbon atoms.

[0145] L2 is, for example, a single bond or an unsubstituted saturated hydrocarbon group having 1 to 8 carbon atoms, and may be, for example, a single bond or a methylene group, an ethylene group, a trimethylene group, a propylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, or an octamethylene group. For example, L2 may be a single bond or a methylene group, an ethylene group, a trimethylene group, or a propylene group.

[0146] In the above formula (1), X may be selected from the group consisting of the following formulas (1-1) to (1-37).

[0147]

[0148]

[0149] Among the above formulas (1-1) to (1-37), * indicates a joining part.

[0150] Among the above equations (1-1) to (1-5), equation (1-7), equation (1-12), equation (1-19), equation (1-22), equation (1-23), equation (1-27), and equation (1-28), a1 each independently represents an integer between 2 and 4.

[0151] Among the above equations (1-6), (1-8), (1-9), (1-13) to (1-15), (1-20), (1-25), and (1-30), a2 is each independently an integer greater than or equal to 1 and less than or equal to 3, a3 is each independently 1 or 2, and each independently the sum of a2 and a3 is 2, 3, or 4.

[0152] Among the above equations (1-10), (1-16), (1-17), (1-21), (1-26), and (1-31), a4 represents 1 or 2 independently, a5 represents 1, a6 represents 1 or 2 independently, and the sum of a4, a5, and a6 is 3 or 4 independently.

[0153] In the above equations (1-24) and (1-29), a7 each independently represents an integer from 1 to 3, and a8 each independently represents an integer from 1 to 3, and each independently the sum of a7 and a8 is 2, 3, or 4.

[0154] In the above equation (1-32), a9 is an integer between 2 and 18.

[0155] Among the above formula (1-37), a 10 represents 1 or 2, and a 11 It represents 1 or 2.

[0156] In the above formulas (1-5) and (1-6), Ar2 is, respectively, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms.

[0157] In Ar2, the substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms is the same as the definition in Ar1 above. The two types of Ar2 present in the same molecule may be the same or different.

[0158] In the above formulas (1-27) to (1-31), Y is each independently -O-, -S-, -C(CH3)2- or diphenylmethylene group.

[0159] In the above formula (1), X may be selected from the group consisting of, for example, the following formulas (1-38) to (1-105).

[0160]

[0161]

[0162]

[0163] In the above formulas (1-53) and (1-54), Ar2 is, respectively, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms.

[0164] In the above formulas (1-100) to (1-102), Y is each independently -O-, -S-, -C(CH3)2- or diphenylmethylene group.

[0165] In another embodiment, X of the above formula (1) may be selected from the above formula (1-34) or formula (1-36).

[0166] The following shows compounds 1 to 24, which are examples of reactive organic compounds according to one embodiment. However, the present invention is not limited to these embodiments.

[0167]

[0168]

[0169] Among the above compounds, the reactive organic compound according to one embodiment may include one or more selected from the group consisting of compound 7, compound 14, compound 17, compound 20, or compound 23.

[0170] The content of a reactive organic compound in an ink composition according to one embodiment is 0.1 parts by mass or more and 10.0 parts by mass or less when the mass of quantum dots in the ink composition is 100 parts by mass, and for example, it may be 0.5 parts by mass or more and 5 parts by mass or less.

[0171] A reactive organic compound according to one embodiment can be synthesized by using a known organic synthesis method. For example, it can be synthesized by the method described in the example or by a method similar to the method described in the example. For example, in the method described in the example, it can be synthesized by changing the raw materials or reaction conditions, adding or excluding some steps, or appropriately combining known synthesis methods.

[0172] The method for confirming the structure of a reactive organic compound according to one embodiment is not particularly limited. The structure of a reactive organic compound according to one embodiment can be confirmed by, for example, known methods, such as NMR, LC-MS, etc.

[0173] (menstruum)

[0174] An ink composition according to one embodiment includes a solvent. The solvent includes at least one selected from compounds represented by the following formulas (2) to (5). The solvent may be used alone or in a mixture of two or more types. The solvent may be a commercially available product or a synthetic product.

[0175]

[0176] In the above formula (2), R1 is a straight-chain or branched saturated hydrocarbon group with 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon group with 3 to 12 carbon atoms, and b represents an integer from 1 to 3. When b is 2 or more, the types of multiple R1 may be the same or different from each other.

[0177] In formula (2), R1 may be, for example, a straight-chain or branched saturated hydrocarbon group with 1 to 10 carbon atoms, or a cyclic saturated hydrocarbon group with 3 to 6 carbon atoms.

[0178] In formula (2), the straight-chain or branched saturated hydrocarbon group having 1 to 18 carbon atoms is not particularly limited. Specific examples of the straight-chain or branched saturated hydrocarbon group having 1 to 18 carbon atoms include straight-chain 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; Examples of branched alkyl groups include isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, tert-pentyl group, neopentyl 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, 1-methyldecyl group, etc.

[0179] In formula (2), the cyclic saturated hydrocarbon group having 3 to 12 carbon atoms is not particularly limited. 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, Examples include 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[5.2.1.02, 6]decyl group, isobornyl group, adamantyl group, etc.

[0180] Specific examples of the compound represented by formula (2) include toluene, xylene, ethylbenzene, diethylbenzene, mesitylene, propylbenzene, cyclopropylbenzene, cyclopentylbenzene, cyclohexylbenzene, etc.

[0181]

[0182] In the above formula (3), R2 is a straight-chain or branched saturated hydrocarbon group with 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon group with 3 to 12 carbon atoms.

[0183] In formula (3), straight-chain or branched saturated hydrocarbon groups with 1 to 18 carbon atoms, and cyclic saturated hydrocarbon groups with 3 to 12 carbon atoms are the same as defined in R1.

[0184] In formula (3), R2 may be, for example, a straight-chain or branched saturated hydrocarbon group with 1 to 10 carbon atoms, or a cyclic saturated hydrocarbon group with 3 to 6 carbon atoms.

[0185] In formula (3), R2 may be, for example, a straight-chain or branched saturated hydrocarbon group with 6 to 10 carbon atoms, or a cyclic saturated hydrocarbon group with 3 to 6 carbon atoms.

[0186] Specific examples of the compound 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-pentylcyclohexane, neopentylcyclohexane. Examples include 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, 1-methyldecylcyclohexane, etc.

[0187]

[0188] In the above formula (4), c represents an integer between 6 and 18.

[0189] Specific examples of compounds represented by formula (4) include n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tritecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, n-eicosan, etc.

[0190]

[0191] In the above formula (5), Z is -OH, -COOH, -NH2 or -SH, and d is an integer between 7 and 17.

[0192] Specific examples of the compound represented by formula (5) include n-octanol, n-nonanol, n-decanol, n-undecanol, n-dodecanol, n-tridecanol, n-tetradecanol, n-tetradecanol, n-pentadecanol, n-hexadecanol, n-heptadecanol, n-octadecanol; nonanic acid, decanic acid, undecanic acid, dodecanic acid, tridecanic acid, tetradecanic acid, pentadecanic acid, hexadecanic acid, heptadecanic acid, octadecanic acid, nonadecanic acid; n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine; Examples include 1-octanthiol, 1-nonanthiol, 1-decanethiol, 1-undecanthiol, 1-dodecanethiol, 1-tridecanethiol, 1-tetradecanthiol, 1-pentadecanthiol, 1-hexadecanethiol, 1-heptadecanthiol, 1-octadecanethiol, etc.

[0193] The solvent content can be appropriately set to satisfy the content of the aforementioned quantum dots and reactive organic compounds.

[0194] (Additives)

[0195] The ink composition according to one embodiment may include various additives as needed. Examples of additives include, for instance, a host material used in the light-emitting layer, an antioxidant, a leveling agent, a plasticizer, a surfactant, an antifoaming agent, a silane coupling agent, a UV absorber, an adhesion promoter, etc.

[0196] Examples of host materials include, for example, compounds having a carbazole backbone, compounds having a diarylamine backbone, compounds having a pyridine backbone, compounds having a pyrazine backbone, compounds having a triazine backbone, compounds having an arylsilane backbone, etc.

[0197] The amount of the above additive can be appropriately determined according to the application within a range that does not impair the purpose of one embodiment.

[0198] As long as it does not impair the purpose of one embodiment, the ink composition according to one embodiment may further include other solvents other than the solvent. Examples of such other solvents include (+)-limonene, ethylene glycol monobutyl ether, α-terpineol, propylene carbonate, dimethyl sulfoxide, N,N-dimethylformamide, 1-bromooctane, 1-bromononan, 1-bromodecane, 1-bromododecane, etc. The content of these other solvents may be 10 volume parts or less, for example, 5 volume parts or less, relative to 100 volume parts of the solvent. In one embodiment, the content of the other solvent may be 0 volume parts, that is, no other solvent other than the solvent according to one embodiment may be included.

[0199] [Method for manufacturing ink composition]

[0200] The method for preparing the ink composition according to one embodiment is not particularly limited. For example, the quantum dots, the reactive organic compound, the solvent, and other components added as needed may be mixed all at once, or the components may be mixed sequentially. The temperature during mixing is not particularly limited, but is typically in the range of 20°C to 30°C. In addition, the mixing time is not particularly limited, but may typically be in the range of 0.1 hours to 1 hour.

[0201] [use]

[0202] The use of the ink composition according to one embodiment is not particularly limited and, for example, can be used to form a quantum dot-containing layer in various optical members used in display devices, etc. Additionally, the ink composition according to one embodiment may be a composition suitable for forming a quantum dot-containing layer by an inkjet method and, for example, can be used for inkjet applications. As for the optical member, there are, for example, semiconductor optical members such as light-converting members and light-emitting members.

[0203] For example, an ink composition according to one embodiment may be used to form a light-emitting layer having an electroluminescent element. That is, according to another embodiment, an electroluminescent element (quantum dot electroluminescent element) having a light-emitting layer formed using an ink composition according to one embodiment is provided. According to yet another embodiment, an image display device having the electroluminescent element (quantum dot electroluminescent element) is provided.

[0204] In the following, quantum dot electroluminescent devices will be described in detail.

[0205] [Quantum Dot Electroluminescent Device]

[0206] Referring to FIG. 1, a quantum dot electroluminescent device according to one embodiment will be described in detail. FIG. 1 is a schematic diagram showing a quantum dot electroluminescent device according to one embodiment. In this specification, "quantum dot electroluminescent device" may be abbreviated as "QD-LED".

[0207] As shown in FIG. 1, a QD-LED (100) according to one 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).

[0208] The method of 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, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, screen printing, flexographic printing, offset printing, inkjet printing, etc.

[0209] When forming a layer other than the light-emitting layer (150) by a solution coating method, examples of solvents used include toluene, xylene, ethylbenzene, diethylbenzene, methicylene, propylbenzene, cyclohexylbenzene, dimethoxybenzene, anisole, ethoxytoluene, phenoxytoluene, isopropylbiphenyl, dimethylanisole, phenyl acetate, phenyl propionic acid, methyl benzoate, ethyl benzoate, cyclohexane, etc. The amount of solvent used in the coating solution is not particularly limited.

[0210] The substrate (110) can be a substrate used in general EL devices. For example, the substrate (110) may be a semiconductor substrate such as a glass substrate or a silicon substrate, or a transparent plastic substrate.

[0211] A first electrode (120) is formed on the substrate (110). Specifically, the first electrode (120) is an anode and can be formed from a metal, an alloy, or a conductive compound having a large work function. For example, the first electrode (120) may be formed as a transparent 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. Additionally, 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 as needed.

[0212] 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, for example, 10 nm or more and 1000 nm or less, for example, 20 nm or more and 300 nm or less (dry film thickness; hereinafter the same).

[0213] The hole injection layer (130) can be formed from a known hole injection material.As known hole injection materials forming the hole injection layer (130), examples include poly(ether ketone)-containing triphenylamine (TPAPKEK), 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), copper phthalocyanine, and 4,4',4"-tris (3-methylphenylphenylamino)triphenylamine (4,4',4”-tris(3-methylphenylphenylamino)triphenylamine: m-MTDATA), N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine: NPB), 4,4',4”-tris(diphenylamino)triphenylamine (4,4',4”-tris(diphenylamino)triphenylamine: TDATA), 4,4',4”-tris(N,N-2-naphthylphenylamino)triphenylamine (4,4',4”-tris(N,N-2-naphthylphenylamino)triphenylamine: 2-TNATA), polyaniline / dodecylbenzenesulfonic acid, Examples include poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate): PEDOT / PSS, and polyaniline / 10-camphorsulfonic acid.

[0214] A hole transport layer (140) is formed on the hole injection layer (130). The hole transport layer (140) is a layer having the function of transporting holes, and can be formed with a thickness of, for example, 10 nm or more and 150 nm or less, for example, 20 nm or more and 50 nm or less.

[0215] The hole transport layer (140) can be formed from a known hole transport material. As known hole transport materials, for example, 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)triphenylamine (TCTA). Examples include N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (NPB), poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-N-(4-sec-butylphenyl)diphenylamine (TFB)). These hole transport materials may be single types or a mixture of two or more types.

[0216] A light-emitting layer (150) is formed on the hole transport layer (140). The light-emitting layer (150) includes quantum dots and, as described above, can be formed using, for example, an inkjet method. One embodiment is an electroluminescent device (quantum dot electroluminescent device) having a light-emitting layer formed by an inkjet device using an ink composition according to one embodiment. One embodiment is a quantum dot electroluminescent device having a light-emitting layer formed by an ink composition according to one embodiment, wherein the light-emitting layer can be formed by an inkjet device. The light-emitting layer (150) can be formed with a thickness of, for example, 10 nm or more and 60 nm or less, for example, 20 nm or more and 50 nm or less.

[0217] An electron transport layer (160) is formed on the light-emitting layer (150). The electron transport layer (160) is a layer having the function of transporting electrons and can be formed using vacuum deposition, spin coating, inkjet, etc. The electron transport layer (160) can be formed with a thickness of, for example, 15 nm or more and 50 nm or less.

[0218] The electron transport layer (160) can be formed using a known electron transport material. Additionally, the 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)aluminum (Alq3), and compounds having a nitrogen-containing aromatic ring. Specific examples of compounds having a nitrogen-containing aromatic ring include, for example, a compound containing a pyridine ring such as 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene, a compound containing a triazine ring such as 2,4,6-tris(3'-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine. There are compounds containing an imidazole ring, such as 2-(4-(N-phenylbenzoimidazolyl-1-yl-phenyl)-9,10-dinaphthylanthracene (2-(4-(N-phenylbenzoimidazolyl-1-yl-phenyl)-9,10-dinaphthylanthracene) and 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene (1,3,5-tris(N-phenyl-benzimidazol-2-yl)benzene: TPBI). In addition, known inorganic electron transport materials are not particularly limited, but examples include oxides such as TiO2, ZnO, ZnMgO, SiO2, SnO2, WO3, Ta2O3, BaTiO3, BaZrO3, ZrO2, HfO2, Al2O3, Y2O3, ZrSiO4, etc.

[0219] The above electron transport material may be a single type or a mixture of two or more types.

[0220] 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) can be formed using a vacuum deposition method or the like. The electron injection layer (170) can be formed with a thickness of, for example, 0.1 nm or more and 5 nm or less, or, for example, 0.3 nm or more and 2 nm or less. Any known material can be used as the material for forming the electron injection layer (170). For example, the electron injection layer (170) can 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).

[0221] A second electrode (180) is formed on the electron injection layer (170). The second electrode (180) can be formed using a vacuum deposition method or the like. The second electrode (180) is, for example, a negative electrode and can be formed from a metal, an alloy, or a conductive compound having a small work function. For example, the second electrode (180) may be formed as a reflective electrode using a metal such as lithium (Li), magnesium (Mg), aluminum (Al), or calcium (Ca), or an alloy such as aluminum-lithium (Al-Li), magnesium-indium (Mg-In), or magnesium-silver (Mg-Ag). The second electrode (180) can be formed with a thickness of, for example, 10 nm or more and 200 nm or less, for example, 50 nm or more and 150 nm or less. Alternatively, the second electrode (180) may be formed as a transparent electrode by a thin film of the metal material with a thickness of 20 nm or less, or by a transparent conductive film such as indium tin oxide (In2O3-SnO2) and indium zinc oxide (In2O3-ZnO).

[0222] Furthermore, the stacked structure of the QD-LED (100) according to the present embodiment is not limited to the above example. The QD-LED (100) according to the present embodiment may be formed with other known stacked structures. For example, in the QD-LED (100), one or more of the hole injection layer (130), hole transport layer (140), electron transport layer (160), and electron injection layer (170) may be omitted, and additionally, other layers may be provided. In addition, each layer of the QD-LED (100) may be formed as a single layer or may be formed as multiple layers.

[0223] 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 may be formed, for example, by an oxadiazole derivative, a triazole derivative, or a phenanthroline derivative.

[0224] Although embodiments of the present invention have been described in detail, they are illustrative and exemplary and are not limiting; it is clear that the scope of the present invention should be interpreted by the appended claims.

[0225] The present invention includes the following embodiments.

[0226] 1. An ink composition comprising quantum dots, a reactive organic compound, and a solvent,

[0227] The above quantum dots do not contain cadmium (Cd) and lead (Pb), and

[0228] The above reactive organic compound is an ink composition, wherein the reactive organic compound is a compound represented by the following formula (1):

[0229]

[0230] Among the above formula (1),

[0231] Ar1 is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms, and

[0232] L1 is a single bond, or oxygen atom, and

[0233] L2 is a single bond, 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, and

[0234] X is one of the groups represented by the following formulas (1-1) to (1-37):

[0235]

[0237]

[0238] Among the above formulas (1-1) to (1-37), * indicates a joining part,

[0239] Among the above equations (1-1) to (1-5), equation (1-7), equation (1-12), equation (1-19), equation (1-22), equation (1-23), equation (1-27), and equation (1-28), a1 each independently represents an integer between 2 and 4, and

[0240] Among the above equations (1-6), (1-8), (1-9), (1-13) to (1-15), (1-20), (1-25), and (1-30), a2 each independently represents an integer between 1 and 3, a3 each independently represents 1 or 2, and the sum of a2 and a3 each independently is 2, 3, or 4.

[0241] Among the above equations (1-10), (1-16), (1-17), (1-21), (1-26), and (1-31), a4 represents 1 or 2, a5 represents 1, a6 represents 1 or 2, and the sum of a4, a5, and a6 is 3 or 4, respectively, and

[0242] In the above equations (1-24) and (1-29), a7 each independently represents an integer between 1 and 3, a8 each independently represents an integer between 1 and 3, and the sum of a7 and a8 each independently is 2, 3, or 4.

[0243] In the above equation (1-32), a9 is an integer between 2 and 18, and

[0244] Among the above formula (1-37), a 10 represents 1 or 2, and a 11 represents 1 or 2, and

[0245] In the above formulas (1-5) and (1-6), Ar2 is, respectively, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms, and

[0246] In the above formulas (1-27) to (1-31), Y is independently -O-, -S-, -C(CH3)2- or diphenylmethylene group.

[0247] 2. The above-described ink composition of 1, wherein the solvent comprises at least one selected from compounds represented by the following formulas (2) to (5):

[0248]

[0249] In the above formula (2), R1 is a straight-chain or branched saturated hydrocarbon group with 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon group with 3 to 12 carbon atoms, and b represents an integer from 1 to 3.

[0250]

[0251] In the above formula (3), R2 is a straight-chain or branched saturated hydrocarbon group with 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon group with 3 to 12 carbon atoms, and

[0252]

[0253] In the above formula (4), c represents an integer between 6 and 18, and

[0254]

[0255] In the above formula (5), Z is -OH, -COOH, -NH2 or -SH, and d is an integer between 7 and 17.

[0256] 3. An ink composition described in 1 or 2, wherein the average particle size of the quantum dots is 1 nm or more and 15 nm or less.

[0257] 4. An ink composition described in any one of 1 to 3, wherein the content of the quantum dots is 0.1 mass% or more and 10.0 mass% or less based on the total mass of the ink composition.

[0258] 5. An ink composition described in any one of 1 to 4, wherein the content of the reactive organic compound is 0.1 parts by mass or more and 10.0 parts by mass or less, when the mass of the quantum dots in the ink composition is 100 parts by mass.

[0259] 6. X is an ink composition described in any one of 1 to 5, selected from the group consisting of the following formulas (1-38) to (1-105):

[0260]

[0262]

[0263]

[0264] In the above formulas (1-53) and (1-54), Ar2 is, respectively, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms, and

[0265] In the above formulas (1-100) to (1-102), Y is -O-, -S-, -C(CH3)2- or diphenylmethylene group.

[0266] 7. X in the above formula (1) is selected from the above formula (1-34) or formula (1-36), an ink composition described in any one of 1 to 5.

[0267] 8. The above-mentioned reactive organic compound is an ink composition described in any one of 1 to 7, represented by one or more of the following compounds 1 to 24:

[0268]

[0270]

[0271] 9. The ink composition described in 8, wherein the reactive organic compound is represented by one or more of the compounds 7, 14, 17, 20, or 23.

[0272] 10. An ink composition described in any one of 2 to 9, wherein R1 of the above formula (2) is a straight-chain or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms.

[0273] 11. An ink composition described in any one of 2 to 9, wherein R2 of the above formula (3) is a straight-chain or branched saturated hydrocarbon group having 6 to 10 carbon atoms, or a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms.

[0274] 12. An ink composition described in any one of 2 to 11, wherein the surface of the quantum dot is coordinated with at least one organic ligand selected from an alkyl halide compound, a thiol group-containing compound, an aliphatic carboxylic acid compound, or a combination thereof.

[0275] 13. An ink composition described in any one of 1 to 12, wherein the content of the organic ligand in the quantum dots is 1 to 30 parts by mass or less when the mass of the quantum dots is 100 parts by mass.

[0276] 14. A quantum dot electroluminescent device having a light-emitting layer formed using an ink composition described in any one of 1 to 13 above.

[0277] 15. A quantum dot electroluminescent device having a light-emitting layer formed by an inkjet device using an ink composition described in any one of 1 to 13 above.

[0278] 16. An image display device having a quantum dot electroluminescent element as described in 14 or 15 above.

[0279] 17. A method for manufacturing a quantum dot electroluminescent device having a light-emitting layer formed using an ink composition described in any one of 1 to 13 above, wherein the light-emitting layer is formed by an inkjet device.

[0280] Examples

[0281] 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.

[0282] Synthesis Example 1: Synthesis of Compound 7

[0283] Compound 7 was synthesized according to the following reaction scheme 1.

[0284] [Reaction Equation 1]

[0285]

[0286] A mixture of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (5.0 g), triethylamine (4.6 g), and dichloromethane (80 mL) was cooled in 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 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 intermediate 7-1, which is a viscous liquid (7.28 g, yield 94, 6%).

[0287] In a 300 mL three-necked flask, intermediate 7-1 (3.64 g), diazabicycloundecene (3.3 g), and acetonitrile (100 mL) were added, and p-acetoamidebenzenesulfonylazide (5.2 g) was slowly added in portions. The mixture was stirred for 24 hours at room temperature under a nitrogen atmosphere. After the reaction was complete, the resulting mixture was poured into water, 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%).

[0288] Synthesis Example 2: Synthesis of Compound 14

[0289] Compound 14 was synthesized according to the following reaction scheme 2.

[0290] [Reaction Equation 2]

[0291]

[0292] 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 to 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 a 1% aqueous sodium hydroxide solution. Subsequently, the organic layer was washed with an 8% aqueous sodium carbonate solution and pure water. The organic layer was dried with magnesium sulfate and then filtered. 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 14-1 (quantity 6.2 g, yield 63%).

[0293] In 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. Subsequently, p-acetamidebenzenesulfonic acid azide (7.82 mmol, 1.88 g) was slowly added, and the mixture was stirred at room temperature for 24 hours. The reaction was stopped by adding pure water to the reaction mixture, and then the mixture was separated into dichloromethane and pure water. The organic layer was dried with magnesium sulfate and filtered. The resulting solution was concentrated and recrystallized using methanol. The obtained solid was vacuum dried (50 °C, 16 hours) to obtain compound 14 (quantity 0.4 g, yield 35%).

[0294] Synthesis Example 3: Synthesis of Compound 20

[0295] Compound 20 was synthesized according to the following reaction scheme 3.

[0296] [Reaction Equation 3]

[0297]

[0298] 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 to a 200 mL three-necked flask and stirred under reflux under a nitrogen atmosphere. After the reaction was complete, the resulting solution was neutralized with a 1% aqueous sodium hydroxide solution. Subsequently, the organic layer was washed with an 8% aqueous sodium carbonate solution and pure water. The organic layer was dried with magnesium sulfate and then filtered. 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 20-1 (quantity 7.0 g, yield 57%).

[0299] In 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. Subsequently, p-acetamidebenzenesulfonic acid azide (11.46 mmol, 2.75 g) was slowly added, and the mixture was stirred at room temperature for 12 hours. The reaction was stopped by adding pure water to the reaction mixture, and then the mixture was separated into ethyl acetate and pure water. The organic layer was dried with magnesium sulfate and filtered. The resulting solution was concentrated and recrystallized using methanol. The obtained solid was vacuum dried (50 °C, 16 hours) to obtain compound 20 (quantity 0.5 g, yield 44%).

[0300] Synthesis Example 4: Synthesis of Compound 17

[0301] Compound 17 was synthesized according to the following reaction scheme 4.

[0302] [Reaction Equation 4]

[0303]

[0304] 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 added to 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 a 1% aqueous sodium hydroxide solution. Subsequently, the organic layer was washed with an 8% aqueous sodium carbonate solution and pure water. The organic layer was dried with magnesium sulfate and then filtered. 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 (quantity 10.9 g, yield 74%).

[0305] Intermediate 17-1 (1.47 mmol, 1.0 g), diazabicycloundecene (14.69 mmol, 2.24 g), and acetonitrile (73.5 mL) were added to a 200 mL four-necked flask and stirred. Subsequently, p-acetamidebenzenesulfonic acid azide (14.69 mmol, 3.53 g) was slowly added, and the mixture was stirred at room temperature for 12 hours. The reaction was stopped by adding pure water to the reaction mixture, and then the mixture was separated into dichloromethane and pure water. The organic layer was dried with magnesium sulfate and then filtered. The resulting solution was concentrated and recrystallized using methanol. The obtained solid was vacuum dried (50 °C, 16 hours) to obtain Compound 17 (quantity 0.88 g, yield 77%).

[0306] Synthesis Example 5: Synthesis of Compound 23

[0307] Compound 23 was synthesized according to the following reaction scheme 5.

[0308] [Reaction Equation 5]

[0309]

[0310] 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 to a 200 mL three-necked flask and stirred under reflux under a nitrogen atmosphere. After the reaction was complete, the resulting solution was neutralized with a 1% aqueous sodium hydroxide solution. Subsequently, the organic layer was washed with an 8% aqueous sodium carbonate solution and pure water. The organic layer was dried with magnesium sulfate and then filtered. 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 (quantity 2.2 g, yield 17%).

[0311] 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. Subsequently, p-acetamidebenzenesulfonic acid azide (14.01 mmol, 3.37 g) was slowly added, and the mixture was stirred at room temperature for 12 hours. The reaction was stopped by adding pure water to the reaction mixture, and then the mixture was separated into ethyl acetate and pure water. The organic layer was dried with magnesium sulfate and then filtered. The resulting solution was concentrated and recrystallized using methanol. The obtained solid was vacuum dried (50 °C, 16 hours) to obtain compound 20 (quantity 0.87 g, yield 75%).

[0312] [Evaluation of Cross-linking Reaction]

[0313] For compounds 7, 14, 17, 20, and 23 synthesized in Synthesis Examples 1 to 5 above, and the following comparative compounds, the reaction initiation temperature and reaction completion time were evaluated, and the results are shown in Table 1.

[0314] (Comparison compound)

[0315]

[0316] (Reaction initiation temperature)

[0317] Compounds 7, 14, 17, 20, 23, and each of the above comparative compounds were measured using a differential scanning calorimeter (DSC) (manufactured by Seiko Instruments, trade name: DSC6000) with a profile raised from room temperature to 320°C at a heating rate of 10°C / min. Among the generated exothermic peaks, the temperature at which the exothermic peak began was set as the reaction start temperature.

[0318] (Reaction completion time)

[0319] Compounds 7, 14, 17, 20, 23, and each of the above comparative compounds were measured using a differential scanning calorimeter (DSC) (manufactured by Seiko Instruments, trade name: DSC6000) with a profile in which the temperature was raised from room temperature to 140°C at a heating rate of 10°C / min and maintained at 140°C for 60 minutes. The time from when 140°C was reached to when the heat capacity reached zero was defined as the reaction completion time.

[0320]

[0321] As shown in Table 1 above, it can be seen that the reactive organic compound according to one embodiment has a lower reaction initiation temperature and a shorter reaction completion time compared to the comparative compound.

[0322] Example 1

[0323] A quantum dot dispersion represented as InP / ZnSe / ZnS was prepared by 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) (core type: InP, shell type: ZnSe / ZnS, quantum dot content in dispersion: 2 mass%, maximum emission wavelength of quantum dots: 627 nm, organic ligand of quantum dots: oleic acid (SP value when coordinated to the quantum dot surface: 8.1 (cal / cm²)). 3 ) 1 / 2 , average particle size of the quantum dots: 10 nm). The content of oleic acid in the quantum dots was 10 parts by mass when the mass of the quantum dots was 100 parts by mass. Ethanol was added to the obtained quantum dot dispersion, precipitation was formed and centrifugation was performed, and the supernatant was removed to obtain a precipitate.

[0324] 3 mL of cyclohexylbenzene was added to the precipitate obtained above as a solvent, stirred with a shaker (mixing temperature: 25°C, mixing time: 10 min), and the precipitate was dispersed in the solvent. The content of quantum dots (InP / ZnSe / ZnS) in the dispersion was 3 mass%. Compound 7 synthesized in Synthesis Example 1 was added to the quantum dot content (3 mass%) in an amount of 5 mass parts, thereby preparing ink composition 1.

[0325] Example 2

[0326] Ink composition 2 was prepared in the same manner as in Example 1, except that compound 14 synthesized in Synthesis Example 2 was used instead of compound 7, and compound 14 was added to make the content of quantum dots (3 mass%) 1 mass part.

[0327] Example 3

[0328] Ink composition 3 was prepared in the same manner as in Example 2, except that compound 20 synthesized in Synthesis Example 3 was used instead of compound 14.

[0329] Comparative Example 1

[0330] For the precipitate obtained in Example 1, 3 mL of cyclohexylbenzene was added as a solvent and stirred with a shaker (mixing temperature: 25°C, mixing time: 10 min) to disperse the precipitate in the solvent to prepare Comparative Ink Composition 1. The content of quantum dots (InP / ZnSe / ZnS) in Comparative Ink Composition 1 was 3.0 mass%.

[0331] [Evaluation of Stacking Stability (Process Stability)]

[0332] Ink composition 1, ink composition 2, ink composition 3, and comparative ink composition 1 were each applied by spin coating to achieve a dry film thickness of 30 nm, and then heat-treated at 140°C for 30 minutes to form each thin film. The UV absorption spectrum of each thin film was measured. Next, a solvent (cyclohexylbenzene) was added dropwise to each thin film and allowed to infiltrate for 10 minutes. After removing the solvent, the UV absorption spectrum of each thin film was measured. Stacking stability was evaluated by the value (percentage) obtained by dividing the intensity of the spectrum after solvent addition by the intensity of the spectrum before solvent addition. 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%).

[0333] Ink composition Reactive organic compounds Amount of reactive organic compound added Stacking stability Example 1 Compound 7 5 parts of mass 99% Example 2 Compound 14 1 part of mass 95% Example 3 Compound 20 1 part of mass 97% Comparative Example 1 No additives 0 mass part 90%

[0334] As shown in Table 2 above, thin films fabricated using ink compositions 1 to 3 exhibit high stacking stability compared to thin films fabricated using comparative ink composition 1. Accordingly, since quantum dot light-emitting layers fabricated using ink compositions 1 to 3 can suppress dissolution during stacking, it is believed that process stability can be secured by using ink compositions 1 to 3.

[0335] Preparation Example 1

[0336] As the first electrode (anode), an ITO-attached glass substrate was used, in which indium tin oxide (ITO) was patterned to a film thickness of 150 nm. This ITO-attached glass substrate was sequentially cleaned using a neutral detergent, deionized water, water, and isopropyl alcohol, and then UV-ozone treatment was performed. Next, poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate) (PEDOT / PSS) (manufactured by Sigma-Aldrich) was applied to the ITO-attached 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-attached glass substrate.

[0337] On this hole injection layer, a toluene solution of 1.0 mass% of the polymer compound P-1 (hole transport material) described below was applied 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.

[0338] 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.

[0339]

[0340] The terminal structure of polymer compound P-1 is presumed to be one of the following structures.

[0341]

[0342] Ink composition 1 was applied onto the hole transport layer by spin coating to a dry film thickness of 30 nm, and then dried. As a result, a quantum dot emitting layer with a thickness (dry film thickness) of 30 nm was formed on the hole transport layer. The light emitted by irradiating the quantum dot dispersion with ultraviolet light had a center wavelength of 462 nm and a full width at half maximum (FWHM) of 30 nm.

[0343] This quantum dot emitting layer was completely dried. A dispersion for forming an electron transport layer was prepared by dispersing ZnMgO in ethanol to a mass of 1.5%. This dispersion was applied onto the quantum dot 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 emitting layer.

[0344] Using a vacuum deposition apparatus, (8-quinolinonato)lithium (lithium quinolate) (Liq) was deposited on 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.

[0345] Aluminum (Al) was deposited on the electron injection layer using a vacuum deposition apparatus. As a result, a second electrode (cathode) with a thickness of 100 nm was formed on the electron injection layer. Thus, a quantum dot electroluminescent device 1 was obtained.

[0346] Comparative Manufacturing Example 1

[0347] In Preparation Example 1, a comparative quantum dot electroluminescent device 1 was prepared by performing the same operation as in Preparation Example 1, except that comparative ink composition 1 was used instead of ink composition 1.

[0348] [Evaluation of Device Performance]

[0349] (Luminous properties)

[0350] For each quantum dot electroluminescent device, when voltage is applied, current begins to flow at a constant voltage, and the quantum dot electroluminescent device emits light. When voltage is applied to each quantum dot electroluminescent device using a DC constant voltage power supply (manufactured by KEYENCE, source meter), current begins to flow at a constant voltage, and the quantum dot electroluminescent device emits light. While measuring the emission of each device using a luminance meter (manufactured by Topcon, SR-3), the current is gradually increased, and when the luminance reaches 650 nit (cd / m²). 2 When it reached ), the current was kept constant and left unattended. In Table 3, the difference between the initial voltage (V) at which the luminance became 650 nits and the voltage (V) after 100 hours is denoted as “ΔV@100hr”, and the change amount per hour from the initial voltage (V) is denoted as “ΔV / hr”.

[0351] (Luminous lifespan)

[0352] Using a DC constant voltage power supply (source meter manufactured by Keyence Co., Ltd.), a predetermined voltage was applied to each quantum dot electroluminescent device to cause each device to emit light. While measuring the emission of the quantum dot electroluminescent devices using a luminance measuring device (SR-3 manufactured by Topcon Co., Ltd.), the current was gradually increased until the luminance reached 650 nit (cd / m²). 2 When it reached ), the current was kept constant and left unattended. In Table 3, the time until the luminance value measured by the luminance meter gradually decreased to 90% of the initial luminance (650 nit) was defined as “Max.T90(hr)”.

[0353] Ink composition ΔV@100hr ΔV / hr Max.T90(hr) Preparation Example 1 Ink composition 1 1.0 0.010 53 Comparative Manufacturing Example 1 Comparative Ink Composition 1 1.8 0.017 40

[0354] From the results of Table 3, it can be seen that the quantum dot electroluminescent device of Preparation Example 1 has a reduced performance by having a light-emitting layer formed using an ink composition according to one embodiment. Specifically, it can be seen that the quantum dot electroluminescent device of Preparation Example 1 has a device lifespan improved by about 1.3 times and the increase in driving voltage is suppressed compared to the quantum dot electroluminescent device of Comparative Preparation Example 1. Explanation of the symbols

[0355] 100: Quantum Dot Electroluminescent Device (QD-LED) 110: Substrate 120: First electrode 130: Hole injection layer 140: Precision Transport Layer 150: Emissive layer 160: Electron transport layer 170: Electron injection layer 180: Second electrode

Claims

Claim 1 An ink composition comprising quantum dots, a reactive organic compound, and a solvent, wherein the quantum dots do not contain cadmium (Cd) and lead (Pb), and the reactive organic compound is a compound represented by the following formula (1): 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, 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, and X is a group selected from the group consisting of the following formulas (1-1) to (1-37): Among the above equations (1-1) to (1-37), * indicates a joining part, and among the above equations (1-1) to (1-5), equation (1-7), equation (1-12), equation (1-19), equation (1-22), equation (1-23), equation (1-27), and equation (1-28), a1 each independently represents an integer between 2 and 4, and among the above equations (1-6), equation (1-8), equation (1-9), equations (1-13) to (1-15), equation (1-20), equation (1-25), and equation (1-30), a2 each independently represents an integer between 1 and 3, a3 each independently represents 1 or 2, and the sum of a2 and a3 each independently is 2, 3, or 4, and the above equations (1-10), equation (1-16), equation (1-17), In equations (1-21), (1-26), and (1-31), a4 each independently represents 1 or 2, a5 represents 1, a6 each independently represents 1 or 2, and the sum of a4, a5, and a6 each independently represents 3 or 4; in equations (1-24) and (1-29), a7 each independently represents an integer between 1 and 3, and a8 each independently represents an integer between 1 and 3, and the sum of a7 and a8 each independently represents 2, 3, or 4; in equation (1-32), a9 is an integer between 2 and 18, and in equation (1-37), a 10 represents 1 or 2, and a 11 1 or 2 represents, in the above formulas (1-5) and (1-6), Ar2 is each independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms, and in the above formulas (1-27) to (1-31), Y is each independently -O-, -S-, -C(CH3)2- or diphenylmethylene group. Claim 2 In claim 1, the ink composition comprises at least one solvent selected from compounds represented by the following formulas (2) to (5): In the above formula (2), R1 is a straight-chain or branched saturated hydrocarbon group with 1 to 18 carbon atoms or a cyclic saturated hydrocarbon group with 3 to 12 carbon atoms, and b represents an integer from 1 to 3. In the above formula (3), R2 is a straight-chain or branched saturated hydrocarbon group with 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon group with 3 to 12 carbon atoms, and In the above formula (4), c represents an integer between 6 and 18, and In the above formula (5), Z is -OH, -COOH, -NH2 or -SH, and d is an integer between 7 and 17. Claim 3 An ink composition according to claim 1, wherein the average particle size of the quantum dots is 1 nm or more and 15 nm or less. Claim 4 An ink composition according to claim 1, wherein the content of the quantum dots is 0.1 mass% or more and 10.0 mass% or less based on the total mass of the ink composition. Claim 5 An ink composition according to claim 1, wherein the content of the reactive organic compound is 0.1 parts by mass or more and 10.0 parts by mass or less when the mass of the quantum dots in the ink composition is 100 parts by mass. Claim 6 In claim 1, X of the above formula (1) is selected from the group consisting of the following formulas (1-38) to (1-105), an ink composition: In the above formulas (1-53) and (1-54), Ar2 is, respectively, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms, and in the above formulas (1-100) to (1-102), Y is, respectively, an -O-, -S-, -C(CH3)2-, or diphenylmethylene group. Claim 7 In claim 1, X of the above formula (1) is an ink composition selected from the above formula (1-34) or formula (1-36). Claim 8 In claim 1, the ink composition wherein the reactive organic compound is represented by one or more of the following compounds 1 to 24: Claim 9 In claim 8, the ink composition wherein the reactive organic compound is represented by one or more of the compounds 7, 14, 17, 20, or 23. Claim 10 In paragraph 2, the ink composition wherein R1 of the above formula (2) is a straight-chain or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms. Claim 11 In paragraph 2, the ink composition, wherein R2 of the above formula (3) is a straight-chain or branched saturated hydrocarbon group having 6 to 10 carbon atoms, or a cyclic saturated hydrocarbon group having 3 to 6 carbon atoms. Claim 12 An ink composition according to claim 1, wherein the surface of the quantum dot is coordinated with at least one organic ligand selected from an alkyl halide compound, a thiol group-containing compound, an aliphatic carboxylic acid compound, or a combination thereof. Claim 13 An ink composition according to claim 12, wherein the content of the organic ligand in the quantum dots is 1 part by mass or more and 30 parts by mass or less when the mass of the quantum dots is 100 parts by mass. Claim 14 A quantum dot electroluminescent device having a light-emitting layer formed using the ink composition described in claim 1. Claim 15 A quantum dot electroluminescent device having a light-emitting layer formed by an inkjet device using the ink composition described in claim 1. Claim 16 An image display device having a quantum dot electroluminescent element as described in paragraph 14 or 15. Claim 17 A method for manufacturing a quantum dot electroluminescent device having a light-emitting layer formed using an ink composition described in claim 1, wherein the light-emitting layer is formed by an inkjet device.

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