Quantum dot-containing composition, wavelength conversion member, and method for producing quantum dot-containing composition

Abstract

The present invention is a quantum dot-containing composition which contains quantum dots that emit fluorescence by excitation light, and which is characterized in that: the quantum dot-containing composition contains a silicone oligomer and quantum dots that have a ligand containing a siloxane bond on the surface of the quantum dots, wherein the ligand containing a siloxane bond contains at least one substituent that is polymerizable with a reactive substituent contained in the silicone oligomer. Thus, there are provided a quantum dot-containing composition that improves inkjet discharge stability and can also be cured while maintaining quantum dot characteristics, a wavelength conversion member, and a method for producing the quantum dot-containing composition.

Description

Quantum dot-containing composition, wavelength conversion member, and method for manufacturing the quantum dot-containing composition

[0001] The present invention relates to a quantum dot-containing composition, a wavelength conversion member, and a method for producing a quantum dot-containing composition.

[0002] In semiconductor nanoparticle single crystals, a strong quantum confinement effect occurs when the crystal size is less than or equal to the Bohr radius of the exciton, resulting in discrete energy levels. Since the energy levels depend on the crystal size, the light absorption and emission wavelengths can be adjusted by controlling the crystal size. Furthermore, the emission from exciton recombination in semiconductor nanoparticle single crystals becomes highly efficient due to the quantum confinement effect, and because this emission is fundamentally in the form of emission lines, achieving a uniform particle size distribution allows for high-brightness, narrow-band emission, which is attracting considerable attention. This phenomenon, resulting from the strong quantum confinement effect in nanoparticles, is called the quantum size effect, and semiconductor nanocrystals utilizing this property are being investigated for broad applications as quantum dots.

[0003] One application of quantum dots is being explored: their use in phosphor materials for displays. If narrow-band, highly efficient light emission can be achieved, it will be possible to reproduce colors that were previously unattainable with existing technologies, making them a promising next-generation display material.

[0004] Currently, quantum dots are being increasingly used in displays, particularly in the form of quantum dot liquid crystal displays (LCDs), which are already being commercialized. Attempts are being made to convert light emitted from white or blue LED backlights to green and red by passing it through a quantum dot-containing wavelength conversion material. Furthermore, applications to color conversion filters for MiniLEDs and μLEDs, as well as self-emissive QDEL devices, are also being investigated, and forming a quantum dot surface state suitable for the patterning method is crucial.

[0005] Currently, the photolithography method is used to produce color filters. This method involves coating a photosensitive resin composition containing pigments onto a glass substrate, drying the solvent, then exposing it to UV light as a mask, and removing the uncured portion by alkaline development to form a color pattern. By repeating this process, blue, red, and green patterns are created. However, the photolithography method has many problems, including significant raw material loss due to the waste of uncured material, a complicated process, and the use of expensive equipment.

[0006] Therefore, inkjet technology has also been considered in recent years. With inkjet technology, there is no waste of raw materials, and it is possible to manufacture large-scale and large-area products without introducing expensive equipment, making it competitive in terms of cost. However, the technology to create fine nozzles is difficult, and as the nozzles become smaller, problems such as clogging and unstable ejection occur. For this reason, both photolithography, which has a proven track record in miniaturization, and inkjet, which is cost-competitive, are being considered.

[0007] On the other hand, creating ink compositions containing quantum dots at high concentration and high dispersion is a problem in both photolithography and inkjet printing. With some exceptions, ink compositions are dispersed in solvents such as PGMEA and PGME. In particular, in the case of inkjet printing, if the viscosity of the curable material in the ink composition is high, ejection is difficult and stable pattern formation is not possible. Therefore, quantum dots dispersed in solvents have been investigated and are directly patterned using inkjet printing (Patent Documents 1 and 2). However, the ink lacks thixotropy after ejection, and ink leakage and seepage become a problem before drying.

[0008] Therefore, a curable material is added to the ink composition, and if the viscosity is high, additives such as solvents and dispersants are added to adjust the viscosity of the ink composition (Patent Document 3). However, if the solvent evaporates, the nozzle discharge becomes unstable, and if a lot of solvent remains in the discharged droplet, there is a problem of the so-called coffee stain phenomenon where quantum dots move to the edge of the droplet when the solvent evaporates.

[0009] Therefore, studies are being conducted to use monomers, which are curable materials with low viscosity, instead of polymer resins, which are curable materials with high viscosity. However, controlling the crosslinking density and reactivity is difficult. Thus, attempts are being made to create ink compositions with low viscosity and controllable crosslinking density by mixing multiple monomers and crosslinking agents (Patent Document 4). However, because it is necessary to mix multiple monomers and crosslinking agents, the quantum dot content is relatively reduced, and the compatibility between quantum dots and multiple materials becomes an issue.

[0010] Chinese Patent Application Publication No. 105820663, U.S. Patent No. 8765014, Japanese Patent Publication No. 2019-081868, Japanese Patent Publication No. 2019-532473

[0011] This invention has been made in view of the above-mentioned problems, and aims to provide a quantum dot-containing composition, a wavelength conversion member, and a method for producing a quantum dot-containing composition that improve inkjet ejection stability and can be cured while maintaining the properties of quantum dots.

[0012] To solve the above problems, the present invention provides a quantum dot-containing composition containing quantum dots that emit fluorescence upon excitation light, wherein the quantum dot-containing composition comprises quantum dots having ligands containing siloxane bonds on the quantum dot surface, and a silicone oligomer, and the ligands containing siloxane bonds contain at least one substituent that can be polymerized with a reactive substituent contained in the silicone oligomer.

[0013] Such a quantum dot-containing composition would maintain the properties of the quantum dots while improving inkjet ejection stability and enabling curing.

[0014] Furthermore, in the present invention, it is preferable that the quantum dot-containing composition further comprises one or more selected from a curing agent, a polymerization initiator, a solvent, and a light scattering agent.

[0015] The quantum dot-containing composition of the present invention may contain the above-mentioned components.

[0016] Furthermore, in the present invention, it is preferable that the quantum dots contain quantum dot cores selected from the group consisting of Group II-VI, Group III-V, Group IV, Group IV-VI, Group I-III-VI, Group II-IV-V, and mixed crystals, alloys, or compounds having a perovskite structure thereof.

[0017] Such quantum dots can emit fluorescence when excited by light.

[0018] In this case, it is preferable that the quantum dots include core-shell type quantum dots in which the quantum dot core is coated with a shell having a larger band gap than the quantum dot core.

[0019] With such quantum dots, the light emission becomes stable, making them relatively easy to handle.

[0020] Furthermore, in the present invention, it is preferable that the ligand has one or more of the following: an amino group, a thiol group, a carboxyl group, a phosphin group, a phosphine oxide group, and an ammonium ion.

[0021] Such ligands are preferable because they are easily coordinated to the quantum dot surface.

[0022] Furthermore, in the present invention, it is preferable that the reactive substituent contained in the silicone oligomer has one or more of the following: vinyl group, acrylic group, methacrylic group, hydroxyl group, phenolic hydroxyl group, epoxy group, and alkoxysilyl group.

[0023] In the present invention, the following are preferred as reactive substituents included in the silicone oligomer.

[0024] Furthermore, the present invention provides a wavelength conversion member which is a cured product of the quantum dot-containing composition described above.

[0025] Such wavelength conversion components suppress the degradation of fluorescence emission efficiency under high temperature and high humidity conditions, resulting in high reliability.

[0026] Further, the present invention provides the method for producing the quantum dot-containing composition described above containing quantum dots that emit fluorescence upon excitation light, the method comprising: a ligand exchange step of mixing a solution in which the quantum dots are dispersed with a ligand containing a siloxane bond to coordinate the ligand to the outermost surface of the quantum dots; and after the ligand exchange step, a silicone oligomer mixing step of mixing the ligand-coordinated quantum dots with the silicone oligomer.

[0027] With such a method for producing a quantum dot-containing composition, it is possible to produce a quantum dot-containing composition that maintains the properties of quantum dots, improves the ejection stability of inkjet, and is also curable.

[0028] As described above, the quantum dot-containing composition of the present invention contains a silicone oligomer and thus has a large number of reactive sites, can form a favorable cured film, has a viscosity of several cP to 100 cP that enables inkjet ejection, and contains almost no silanol component, and therefore can be stably handled in the atmosphere.

[0029] As described above, there has been a demand for the development of a quantum dot-containing composition that maintains the properties of quantum dots, improves the ejection stability of inkjet, and is also curable, and a method for producing the same.

[0030] As a result of extensive and intensive studies on the above problem, the present inventors have found that the use of a silicone oligomer in a quantum dot-containing composition is effective. They have also found that coordinating a ligand containing a siloxane bond to the surface of the quantum dots is effective for obtaining dispersion stability. Furthermore, the inventors have found that by introducing a substituent capable of polymerizing with the reactive substituent of the silicone oligomer into the ligand, a quantum dot-containing composition that can be cured even when added at a high concentration can be produced, and the present invention has been completed.

[0031] In other words, the present invention relates to a quantum dot-containing composition containing quantum dots that emit fluorescence upon excitation light, wherein the quantum dot-containing composition comprises quantum dots having ligands containing siloxane bonds on the quantum dot surface, and a silicone oligomer, wherein the ligands containing siloxane bonds contain at least one substituent that can be polymerized with a reactive substituent contained in the silicone oligomer.

[0032] The present invention will be described in detail below, but the present invention is not limited to these descriptions.

[0033] (Quantum dot-containing composition) The quantum dot-containing composition of the present invention comprises quantum dots in which a ligand containing a siloxane bond is coordinated to the surface of the quantum dot and substituents that can be polymerized with a silicone oligomer are introduced, and a silicone oligomer having a reactive substituent.

[0034] (Quantum Dots) The quantum dots in this invention are not particularly limited as long as they emit fluorescence when excited by light, and can be used in any form. The quantum dots are mainly nanoparticles with a particle size of 10 nm or less, but they can also be nanowires, nanorods, nanotubes, nanocubes, etc., and can be applied in any shape.

[0035] The quantum dots used in the present invention can be any suitable material, for example, a semiconductor material that contains a quantum dot core selected from the group consisting of Group II-VI, Group III-V, Group IV, Group IV-VI, Group I-III-VI, Group II-IV-V, and compounds having mixed crystals, alloys, or perovskite structures thereof.

[0036] Specifically, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, G aSb, InN, InP, InAs, InSb, Si, Ge, Sn, Pb, PbS, PbSe, PbTe, SnS, SnSe, SnTe, AgGaS ２ AgInS ２ AgGaSe ２ AgInSe ２, CuGaS ２ , CuGaSe ２ , CuInS ２ , CuInSe ２ , ZnSiP ２ , ZnGeP ２ , CdSiP ２ , CdGeP ２ , CsPbCl ３ , CsPbBr ３ , CsPbI ３ , CsSnCl ３ , CsSnBr ３ , CsSnI ３ Examples include, but are not limited to, compounds containing the above.

[0037] Further, the quantum dots used in the present invention may have a core-shell structure. The shell material capable of forming the core-shell structure is not particularly limited, but those having a large band gap relative to the core material and low lattice mismatch are preferred, and any combination can be selected according to the core material.

[0038] Specific shell materials include ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, Si, Ge, Sn, Pb, PbS, PbSe, PbTe, SnS, SnSe, SnTe, AgGaS ２ , AgInS ２ , AgGaSe ２ , AgInSe ２ , CuGaS ２ , CuGaSe ２ , CuInS ２ , CuInSe ２ , ZnSiP ２ , ZnGeP ２ , CdSiP ２ , CdGeP ２ , CsPbCl ３ , CsPbBr ３ , CsPbI ３ , CsSnCl ３ , CsSnBr ３ , CsSnI ３Examples include BeS, BeSe, BeTe, MgS, MgSe, MgTe, CuF, CuCl, CuBr, and CuI, and these materials may be selected as a single or multiple mixed crystal, but are not limited thereto.

[0039] Preferably, the quantum dots include core-shell type quantum dots in which the quantum dot core is coated with a shell having a larger band gap than the quantum dot core.

[0040] While there are various methods for manufacturing quantum dots, such as liquid-phase and gas-phase methods, the present invention is not particularly limited. However, from the viewpoint of exhibiting high fluorescence emission efficiency, it is preferable to use semiconductor nanoparticles obtained by the hot soap method or hot injection method, which involves reacting precursor species at high temperatures in a high-boiling-point nonpolar solvent. It is desirable that organic ligands are coordinated to the surface in order to impart dispersibility in the nonpolar solvent and reduce surface defects.

[0041] The organic ligand preferably contains an aliphatic hydrocarbon from the viewpoint of dispersibility. Examples of such organic ligands include oleic acid, stearic acid, palmitic acid, myristic acid, lauric acid, decanoic acid, octanoic acid, oleylamine, stearyl(octadecyl)amine, dodecyl(lauryl)amine, decylamine, octylamine, octadecanethiol, hexadecanethiol, tetradecanethiol, dodecanethiol, decanethiol, octanthiol, trioctylphosphine, trioctylphosphine oxide, triphenylphosphine, triphenylphosphine oxide, tributylphosphine, tributylphosphine oxide, etc., and these may be used individually or in combination.

[0042] (Ligands coordinating to quantum dots) Furthermore, the quantum dots in the present invention have ligands containing siloxane bonds as ligands coordinating to their surface. Preferably, the ligands contain one or more of the following: an amino group, a thiol group, a carboxyl group, a phosphin group, a phosphine oxide group, and an ammonium ion. In addition to the ligands containing siloxane bonds, it is desirable that the quantum dots in the present invention also have the above-mentioned organic ligands coordinating to them. It is desirable that the ligands containing siloxane bonds have substituents that interact with or adsorb to the quantum dot surface. Examples of substituents that interact with or adsorb to the quantum dot surface include amino groups, thiol groups, carboxyl groups, mercapto groups, phosphin groups, phosphine groups, phosphine oxide groups, sulfonyl groups, ammonium ions, quaternary ammonium salts, etc., and among these, amino groups, carboxyl groups, mercapto groups, phosphine groups, and quaternary ammonium salts are preferred from the viewpoint of strong coordinating ability.

[0043] Furthermore, the ligand containing a siloxane bond in the present invention contains at least one substituent that can polymerize with the reactive substituent contained in the silicone oligomer described later. It is desirable that the substituents of the silicone oligomer and substituents that can polymerize with the reactive substituent are contained in the ligand containing the siloxane bond by forming a covalent bond with it. With such a ligand, even if it forms aggregates with the quantum dot to which the ligand is coordinated, it will not easily detach during subsequent purification operations and will exhibit desirable properties.

[0044] Furthermore, examples of substituents that can polymerize with silicone oligomers include vinyl groups, acrylic groups, methacrylic groups, hydroxyl groups, phenolic hydroxyl groups, epoxy groups, sulfonyl groups, carboxyl groups, thiol groups, and alkoxysilyl groups. However, since introducing highly acidic substituents or those that easily coordinate with quantum dots tends to cause aggregation, vinyl groups, acrylic groups, methacrylic groups, hydroxyl groups, phenolic hydroxyl groups, epoxy groups, and alkoxysilyl groups are preferred.

[0045] (Silicone Oligomer) The silicone oligomer included in the quantum dot-containing composition of the present invention is not particularly limited as long as it has a reactive substituent. Silicone oligomers are mainly dimers and trimers, and are low molecular weight materials with a molecular weight of 1000 or less, so they have relatively low viscosity, high compatibility with organic solvents, and low volatility. Furthermore, the silicone oligomer used in the present invention has polymerizable reactive substituents introduced, and curing is possible when used in combination with polymerization initiators, etc. The reactive substituent included in the silicone oligomer preferably has one or more of the following: vinyl group, acrylic group, methacrylic group, hydroxyl group, phenolic hydroxyl group, epoxy group, and alkoxysilyl group. Examples of radical polymerizable reactive substituents include vinyl group, acrylic group, methacrylic group, thiol group, etc., and all can be suitably used. Examples of cationic polymerizable reactive substituents include hydroxyl group, phenolic hydroxyl group, epoxy group, glycidyl group, oxetanyl group, isocyanate group, etc., and all can be suitably used.

[0046] Furthermore, in the present invention, it is preferable that the quantum dot-containing composition further comprises one or more selected from a curing agent, a polymerization initiator, a solvent, and a light scattering agent. Each component will be described in detail below.

[0047] (Curing agent) The quantum dot-containing composition of the present invention may contain a curing agent. As the curing agent, titanium-based, aluminum-based alkoxide oligomers or monomers, or phosphoric acid-based curing catalysts can be used. Specifically, D-20, D-25, D-26, DX-9740, X-40-2309A (Shin-Etsu Chemical Co., Ltd.) can be suitably used.

[0048] The curing agent content is preferably 0.1 to 10 parts by mass, and more preferably 0.2 to 5 parts by mass, per 100 parts by mass of the added silicone oligomer.

[0049] (Polymerization Initiator) The quantum dot-containing composition of the present invention may also preferably contain a polymerization initiator. The polymerization initiator may be a thermal or photopolymerization initiator, and either can be suitably used in conjunction with the silicone oligomer. Examples of photoradical polymerization initiators include Irgacure® series, which are commercially available from BASF, such as Irgacure 290, Irgacure 651, Irgacure 754, Irgacure 184, Irgacure 2959, Irgacure 907, Irgacure 369, Irgacure 379, Irgacure 819, and Irgacure 1173. Examples of Darocure® series include TPO and Darocure 1173. In addition, known thermal radical polymerization initiators, photocationic polymerization initiators, titania (a curing catalyst for alkoxysilanes), and alumina oligomers may also be included.

[0050] The polymerization initiator content is preferably 0.1 to 10 parts by mass, and more preferably 0.2 to 5 parts by mass, per 100 parts by mass of the added silicone oligomer.

[0051] (Solvent) The quantum dot-containing composition of the present invention may contain a solvent to improve its applicability. From the viewpoint of dispersibility with quantum dots, organic solvents are preferred as solvents, such as ketones, alkylene glycol ethers, alcohols, and aromatic compounds. From the ketone group, examples include acetone, methyl ethyl ketone, cyclohexanone, etc. From the alkylene glycol ether group, examples include methyl cellosolve (ethylene glycol monomethyl ether), butyl cellosolve (ethylene glycol monobutyl ether), methyl acetate cellosolve, ethyl acetate cellosolve, butyl acetate cellosolve, ethylene glycol monopropyl ether, ethylene glycol monohexyl ether, ethylene glycol dimethyl ether, diethylene glycol ethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol acetate monomethyl ether, diethylene glycol acetate Suitablely usable compounds include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, 3-methyl-3-methoxybutanol, etc. from the group of alcohols, and benzene, toluene, xylene, etc. from the group of aromatic compounds.

[0052] The solvent content may be adjusted as appropriate according to the viscosity of each silicone oligomer, preferably 5 to 30 parts by mass, and more preferably 1 to 10 parts by mass, per 100 parts by mass of silicone oligomer.

[0053] (Light scattering agent) The quantum dot-containing composition of the present invention may contain a light scattering agent to improve the light extraction efficiency. Examples of light scattering agents include titania, zirconia, silica, and alumina.

[0054] The amount of light scattering agent is preferably 1 to 20 parts by mass, and more preferably 1 to 10 parts by mass, per 100 parts by mass of the added silicone oligomer.

[0055] Furthermore, the quantum dot-containing composition of the present invention may also contain polymerizable crosslinking agents, photoacid generators, antioxidants, etc., and can be appropriately adjusted according to polymerizability and coatability.

[0056] (Wavelength Conversion Member) The wavelength conversion member of the present invention is a cured product obtained by curing a quantum dot-containing composition. The form of the wavelength conversion member in the present invention is not particularly limited, but examples include a wavelength conversion color filter patterned as an inkjet material. The method for manufacturing the wavelength conversion member is not particularly limited, but for example, the wavelength conversion member can be obtained by coating a quantum dot-containing composition onto a transparent film or substrate such as PET or polyimide, curing it, and then laminating it.

[0057] The method for curing the above-mentioned quantum dot-containing composition is not particularly limited, but for example, a film coated with the quantum dot-containing composition can be cured overnight at room temperature with humidity. Alternatively, it can be done by heating at 60°C for 2 hours, followed by heating at 150°C for 4 hours. Furthermore, the quantum dot-containing composition may be cured using a photopolymerization reaction, and the method can be appropriately modified according to the application.

[0058] By introducing substituents that can polymerize with reactive substituents in the silicone oligomer into the ligand containing the siloxane bond on the quantum dot surface in the above quantum dot-containing composition, it becomes possible to manufacture a wavelength conversion component that is highly reliable after curing and does not exhibit aggregation or curing inhibition.

[0059] (Method for producing a quantum dot-containing composition) The present invention provides a method for producing the quantum dot-containing composition described above, which contains quantum dots that emit fluorescence upon excitation light, comprising: a ligand exchange step of mixing a solution in which the quantum dots are dispersed with a ligand having a siloxane bond to coordinate the ligand to the outermost surface of the quantum dots; and a silicone oligomer mixing step of mixing the quantum dots to which the ligand has been coordinated with the silicone oligomer after the ligand exchange step.

[0060] The quantum dot-containing composition of the present invention can be produced, for example, by the following method. First, quantum dots coordinated with ligands containing long-chain hydrocarbons are dispersed in a hydrophobic solvent, and a ligand exchange reaction is carried out by mixing ligands containing siloxane bonds with the quantum dots. The conditions of the ligand exchange reaction, such as the amount added, heating temperature, time, and light irradiation, are appropriately changed depending on the type of ligand.

[0061] Next, a quantum dot-containing composition can be produced by mixing the quantum dots, to which the ligand containing the siloxane bond is coordinated, with the silicone oligomer.

[0062] Ligands containing siloxane bonds can be synthesized by the reaction of trialkylsilanes, dialkylsilanes, and monoalkylsilanes in the presence of an acid or base, or by the reaction of dihydroxysilane with monoalkoxysilane, dialkoxysilane, trialkoxysilane, or a silicone polymer or oligomer containing an alkoxysilyl group. Furthermore, the ligands containing siloxane bonds in the present invention have at least one substituent that can be polymerized with the reactive substituent contained in the aforementioned silicone oligomer, and are capable of coordinating to quantum dots. It is desirable that the reactive substituent contained in the silicone oligomer and the polymerizable substituent are contained in the ligand containing the siloxane bond by forming a covalent bond. There are no particular restrictions on the method of forming the covalent bond, but for example, a method of introducing monoalkoxysilanes, dialkoxysilanes, trialkoxysilanes, or silicone oligomers having substituents that can be polymerized with the reactive substituent contained in the silicone oligomer or substituents that can coordinate to the quantum dot surface by forming a siloxane bond using the method described above is suitably used. After forming a ligand containing a siloxane bond, unreacted materials and by-products are removed by purification, and the ligand containing the siloxane bond can be coordinated to the quantum dot surface by mixing with quantum dots and performing treatments such as heating. Subsequently, a quantum dot-containing composition can be produced by mixing with a silicone oligomer. By coordinating the ligand containing the siloxane bond, the compatibility with the silicone oligomer is improved, and a quantum dot-containing composition can be produced in which the quantum dots are uniformly dispersed without aggregation.

[0063] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited thereto. In this example, an InP / ZnSe / ZnS core-shell type quantum dot was used as the quantum dot material.

[0064] [Example 1] (Quantum dot core synthesis process) 0.23 g (0.9 mmol) of palmitic acid, 0.088 g (0.3 mmol) of indium acetate, and 10 mL of 1-octadecene were added to a flask. The mixture was heated and stirred under reduced pressure at 100°C for 1 hour while dissolving the raw materials. Then, nitrogen was purged into the flask, and 0.75 mL (0.15 mmol) of a 0.2 M solution prepared by mixing tritrimethylsilylphosphine with trioctylphosphine was added. The temperature was raised to 300°C, and it was confirmed that the solution changed color from yellow to red, indicating the formation of core particles.

[0065] (Quantum dot shell layer synthesis process) Next, 2.85 g (4.5 mmol) of zinc stearate and 15 mL of 1-octadecene were added to another flask, and under reduced pressure, the mixture was heated and stirred at 100°C for 1 hour while dissolving to prepare a 0.3 M zinc stearate octadecene solution. 3.0 mL (0.9 mmol) of this solution was added to the reaction solution after core synthesis and cooled to 200°C. Next, 0.474 g (6.0 mmol) of selenium and 4.0 mL of trioctylphosphine were added to another flask and heated to 150°C to dissolve to prepare a 1.5 M selentrioctylphosphine solution. The reaction solution after the core synthesis process, which had been cooled to 200°C, was heated to 320°C over 30 minutes, and the selentrioctylphosphine solution was added in 0.1 mL increments for a total of 0.6 mL (0.9 mmol). The mixture was held at 320°C for 10 minutes and then cooled to room temperature. 0.44 g (2.2 mmol) of zinc acetate was added and dissolved by heating and stirring under reduced pressure at 100°C. The flask was again purged with nitrogen and the temperature was raised to 230°C. 0.98 mL (4.0 mmol) of 1-dodecanethiol was added and the mixture was held for 1 hour. The resulting solution was cooled to room temperature, ethanol was added to precipitate it, the supernatant was removed by centrifugation, and the solution was redispersed with 2 mL of toluene to prepare a core-shell type quantum dot-containing solution.

[0066] (Ligand synthesis process) As ligands having substituents capable of forming siloxane bonds and substituents that coordinate to the quantum dot surface, 1.43 g (6 mmol) of (3-mercaptopropyl)triethoxysilane (Tokyo Chemical Industries, Ltd.), 3 g of X-61-717 (Shin-Etsu Chemical Co., Ltd.), and 5 mL of ethanol were added, 1 mL of 0.1 M aqueous hydrochloric acid was added, and the mixture was heated at 60°C for 1 day. The solvent was removed by evaporation using an evaporator, and the mixture was separated by silica gel column to prepare a ligand containing 2.4 g of siloxane bonds.

[0067] (Ligand exchange step) 2 mL of the siloxane bond-containing ligand prepared in the ligand synthesis step was added to 2 mL of the quantum dot-containing solution obtained in the quantum dot shell layer synthesis step, and the mixture was stirred at room temperature for 24 hours. After the reaction was complete, ethanol was added to precipitate the reaction solution, and the supernatant was removed by centrifugation. The same purification was performed again, and the solution was dispersed in toluene to prepare a quantum dot solution to which the siloxane bond-containing ligand was coordinated.

[0068] (Silicone Oligomer Mixing Process) The solution after the ligand exchange process, dispersed in toluene, and X-61-717 (Shin-Etsu Chemical Co., Ltd.), a silicone oligomer, were weighed and mixed so that the quantum dots were present at 20% by mass in terms of non-volatile content. After mixing, 1 part by mass of the thermal radical generator AIBN (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to 100 parts by mass of X-61-717 to obtain a quantum dot-containing composition.

[0069] (Method for manufacturing wavelength conversion member) A wavelength conversion member was manufactured using the obtained quantum dot-containing composition. The quantum dot-containing composition was degassed under vacuum, and the quantum dot-containing composition with a solid content of 20% was poured into a 20 cm x 10 cm square, 500 μm thick mold coated with fluororesin. The quantum dot-containing composition was heat-cured by heating it on a hot plate at 120°C for 1 hour while evaporating the solvent, and then removed from the mold to manufacture a wavelength conversion member with a thickness of 100 μm.

[0070] (Measurement of emission wavelength, emission width at half maximum, and luminescence efficiency) In the examples and comparative examples, the fluorescence emission characteristics of the quantum dot-containing compositions were evaluated using the quantum efficiency measurement system (QE-2100) manufactured by Otsuka Electronics Co., Ltd., to measure the emission wavelength, fluorescence emission width at half maximum, and fluorescence emission efficiency (internal quantum efficiency) of the quantum dots at an excitation wavelength of 450 nm.

[0071] (Ejection Stability Test) An inkjet ejection test was performed using the obtained quantum dot-containing composition. An inkjet ejection test was conducted using a labojet-600 inkjet device (manufactured by Microjet Corporation) and an IJHB-10 inkjet head (manufactured by Microjet Corporation) to evaluate whether stable ejection was possible and whether a dot-shaped pattern could be formed.

[0072] [Comparative Example 1] The procedure up to the synthesis of the quantum dot shell layer was carried out in the same manner as in Example 1.

[0073] (Silicone Oligomer Mixing Process) Two mL of the solution obtained after synthesizing the quantum dot shell layer dispersed in toluene was mixed with X-61-717 (Shin-Etsu Chemical Co., Ltd.), a silicone oligomer, weighed so that the quantum dots were present at 20% by mass in terms of non-volatile content. After mixing, the solvent was removed, and 1 part by mass of the thermal radical generator AIBN (manufactured by Tokyo Chemical Co., Ltd.) was added to 100 parts by mass of the added silicone oligomer to obtain a quantum dot-containing composition. The wavelength conversion member was manufactured in the same manner as in Example 1, and the emission wavelength, emission width at half maximum, and luminous efficiency were measured.

[0074] (Discharge Stability Test) A discharge stability test was performed in the same manner as in Example 1, but clogging occurred during discharge. Therefore, 0.5 mL of toluene was added to 1 mL of the quantum dot-containing composition to redisperse it, and the discharge stability test was performed again to evaluate whether a dot-shaped pattern could be formed. After discharge, the solvent gradually evaporated as the mixture was allowed to stand, and a coffee stain phenomenon was observed in which the shape of the dots changed.

[0075] [Example 2] The procedure was the same as in Example 1 up to the ligand exchange step.

[0076] (Silicone Oligomer Mixing Process) 2 mL of the solution obtained after the synthesis of the quantum dot shell layer dispersed in toluene and KR-500 (Shin-Etsu Chemical Co., Ltd.), a silicone oligomer, were weighed and mixed so that the quantum dots were present at 20% by mass in terms of non-volatile content. After mixing, the solvent was removed, and 2 parts by mass of curing agent D-20 (Shin-Etsu Chemical Co., Ltd.) were added to 100 parts by mass of the added KR-500 to obtain a quantum dot-containing composition.

[0077] (Method for manufacturing wavelength conversion member) A wavelength conversion member was manufactured using the obtained quantum dot-containing composition. The quantum dot-containing composition was degassed under vacuum, and the quantum dot-containing composition with a solid content of 20% was poured into a 20 cm x 10 cm square, 500 μm thick mold coated with fluororesin. The composition was cured by humidity in ambient air at room temperature, and then removed from the mold to manufacture a wavelength conversion member with a thickness of 100 μm. The emission wavelength, emission width at half maximum, luminous efficiency, and discharge stability tests were performed in the same manner as in Example 1.

[0078] [Comparative Example 2] The quantum dot shell layer was fabricated using the same method as in Example 1 up to the quantum dot shell layer synthesis step. The silicon oligomer mixing step was then performed using the same method as in Example 2, excluding the ligand synthesis step and ligand exchange step, to produce a wavelength conversion member. The emission wavelength, emission width at half maximum, and luminous efficiency were measured using the same method as in Example 1.

[0079] (Discharge Stability Test) A discharge stability test was performed in the same manner as in Example 1, but there was a lot of aggregation and it was not possible to discharge from the nozzle. Therefore, 2 mL of toluene was added to 1 mL of the quantum dot-containing composition to redisperse it, and the discharge stability test was performed again to evaluate whether a dot-shaped pattern could be formed. After discharge, the solvent was allowed to stand and gradually evaporated, and aggregation of quantum dots and a coffee stain phenomenon in which the dot shape changed were observed.

[0080] [Example 3] The process up to the quantum dot shell layer synthesis step was the same as in Example 1.

[0081] (Ligand synthesis process) 1.0 mmol of (3-mercaptopropyl)triethoxysilane, 4.0 mmol of triethoxysilylpropyl methacrylate, 6.0 mmol of diphenylsilanediol, and 0.15 mmol of barium hydroxide monohydrate were added to a flask purged with nitrogen, and the mixture was heated and stirred at 65°C for 24 hours. After the reaction was complete, the mixture was cooled to room temperature, separated by silica gel column chromatography, and the solvent was removed by evaporator to prepare a ligand containing 2.7 g of siloxane bonds.

[0082] (Ligand exchange step) 2 mL of the siloxane bond-containing ligand prepared in the ligand synthesis step was added to 2 mL of the quantum dot-containing solution obtained in the quantum dot shell layer synthesis step, and the mixture was stirred at room temperature for 24 hours. After the reaction was complete, ethanol was added to precipitate the reaction solution, and the supernatant was removed by centrifugation. The same purification was performed again, and the solution was dispersed in toluene to prepare a quantum dot solution to which the siloxane bond-containing ligand was coordinated. Subsequently, the silicone oligomer mixing step, the production of the wavelength conversion member, the measurement of emission wavelength, emission width at half maximum, luminous efficiency, and discharge stability test were carried out in the same manner as in Example 1.

[0083] [Comparative Example 3] The quantum dot shell layer was fabricated in the same manner as in Example 1 up to the quantum dot shell layer synthesis step, and the wavelength conversion member was manufactured in the same manner as in Example 3, excluding the ligand synthesis step and ligand exchange step. Subsequently, the emission wavelength, emission full width at half maximum, and luminous efficiency were measured in the same manner as in Example 1.

[0084] (Discharge Stability Test) A discharge stability test was performed in the same manner as in Example 1, but there was a lot of aggregation and it was not possible to discharge from the nozzle. Therefore, 2 mL of toluene was added to 1 mL of the quantum dot-containing composition to redisperse it, and the discharge stability test was performed again to evaluate whether a dot-shaped pattern could be formed. After discharge, the solvent was allowed to stand and gradually evaporated, and aggregation of quantum dots and a coffee stain phenomenon in which the dot shape changed were observed.

[0085] [Example 4] The procedure was the same as in Example 3 up to the ligand exchange step.

[0086] (Silicone Oligomer Mixing Process) 2 mL of the solution obtained after the synthesis of the quantum dot shell layer dispersed in toluene and X-40-9282K (Shin-Etsu Chemical Co., Ltd.), a silicone oligomer, were weighed and mixed so that the quantum dots were present at 20% by mass in terms of non-volatile content. After mixing, the solvent was removed, and 4 parts by mass of the curing agent D-20 (Shin-Etsu Chemical Co., Ltd.) was added to 100 parts by mass of the added X-40-9282K to obtain a quantum dot-containing composition.

[0087] (Method for manufacturing wavelength conversion member) A wavelength conversion member was manufactured using the obtained quantum dot-containing composition. The quantum dot-containing composition was degassed under vacuum, and the quantum dot-containing composition with a solid content of 20% was poured into a 20 cm x 10 cm square, 500 μm thick mold coated with fluororesin. The composition was cured by humidity in ambient air at room temperature, and then removed from the mold to manufacture a wavelength conversion member with a thickness of 100 μm. The emission wavelength, emission width at half maximum, luminous efficiency, and discharge stability tests were performed in the same manner as in Example 1.

[0088] [Comparative Example 4] The quantum dot shell layer was fabricated in the same manner as in Example 1 up to the quantum dot shell layer synthesis step, and the wavelength conversion member was manufactured in the same manner as in Example 4, excluding the ligand synthesis step and ligand exchange step. The emission wavelength, emission width at half maximum, and luminous efficiency were measured in the same manner as in Example 1.

[0089] (Discharge Stability Test) A discharge stability test was performed in the same manner as in Example 1, but clogging occurred during discharge. Therefore, 0.5 mL of toluene was added to 1 mL of the quantum dot-containing composition to redisperse it, and the discharge stability test was performed again to evaluate whether a dot-shaped pattern could be formed. After discharge, the solvent gradually evaporated as the mixture was allowed to stand, and a coffee stain phenomenon was observed in which the shape of the dots changed.

[0090] Table 1 shows the results of comparing Examples 1-4 with Comparative Examples 1-4.

[0091] The results of fluorescence emission efficiency and discharge stability tests of wavelength conversion members using quantum dot-containing compositions are shown. Table 1 shows that, compared to the examples, the comparative examples, which did not undergo ligand synthesis and ligand exchange processes and did not have ligands containing siloxane bonds on the quantum dot surface, exhibited lower quantum efficiency and a larger long-wavelength shift in emission wavelength. Microscopic observation revealed numerous aggregates of approximately 1-50 μm in size in comparative examples 1-4, resulting in reduced quantum efficiency. On the other hand, the examples exhibited smaller and fewer aggregates, thus suppressing the decrease in quantum efficiency. The examples demonstrate that significant steric hindrance can be introduced through silicone or resin coating, effectively suppressing aggregation. Comparing the discharge stability test results, all examples showed improved discharge stability compared to the comparative examples, and the dot shape was also good. From this, it can be seen that in Examples 2 and 4, discharge stability can be ensured even without the presence of a solvent, and even in Examples 1 and 3, which contain a solvent, discharge stability can be ensured with a small amount of solvent, resulting in less solvent evaporation after discharge and suppression of quantum dot aggregation and coffee stain phenomena.

[0092] As described above, the quantum dot-containing composition of the present invention has high suitability for inkjet patterning, and it has been confirmed that the wavelength conversion member using it exhibits less aggregation of quantum dots, good patterns after curing, and suppressed degradation of fluorescence emission efficiency.

[0093] This specification encompasses the following embodiments: [1] A quantum dot-containing composition comprising quantum dots that emit fluorescence upon excitation light, wherein the quantum dot-containing composition comprises quantum dots having ligands containing siloxane bonds on the quantum dot surface, and a silicone oligomer, characterized in that the ligands containing siloxane bonds contain at least one substituent that can be polymerized with a reactive substituent contained in the silicone oligomer. [2] The quantum dot-containing composition according to [1], further comprising one or more selected from a curing agent, a polymerization initiator, a solvent, and a light scattering agent. [3] The quantum dot-containing composition according to [1] or [2], characterized in that the quantum dots comprise quantum dot cores selected from the group consisting of Group II-VI, Group III-V, Group IV, Group IV-VI, Group I-III-VI, Group II-IV-V, and compounds having mixed crystals, alloys, or perovskite structures thereof. [4]: The quantum dot-containing composition according to [3], characterized in that the quantum dot contains a core-shell type quantum dot in which the quantum dot core is coated with a shell having a larger band gap than the quantum dot core. [5]: The quantum dot-containing composition according to any one of [1] to [4], characterized in that the ligand has one or more of the following: an amino group, a thiol group, a carboxyl group, a phosphin group, a phosphine oxide group, and an ammonium ion. [6]: The quantum dot-containing composition according to any one of [1] to [5], characterized in that the reactive substituent contained in the silicone oligomer has one or more of the following: a vinyl group, an acrylic group, a methacrylic group, a hydroxyl group, a phenolic hydroxyl group, an epoxy group, and an alkoxysilyl group. [7]: A wavelength conversion member characterized in that it is a cured product of any one of the quantum dot-containing compositions according to [1] to [6].[8] A method for producing any one of the quantum dot-containing compositions described in [1] to [6] above, which contains quantum dots that emit fluorescence upon excitation light, comprising: a ligand exchange step of mixing a solution in which the quantum dots are dispersed with a ligand containing a siloxane bond to coordinate the ligand to the outermost surface of the quantum dots; and a silicone oligomer mixing step of mixing the quantum dots to which the ligand has been coordinated with the silicone oligomer after the ligand exchange step.

[0094] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention.

Claims

A quantum dot-containing composition comprising quantum dots that emit fluorescence upon excitation light, wherein the quantum dot-containing composition comprises quantum dots having ligands containing siloxane bonds on the quantum dot surface, and a silicone oligomer, characterized in that the ligands containing siloxane bonds contain at least one substituent that can polymerize with a reactive substituent contained in the silicone oligomer. 　 The quantum dot-containing composition according to claim 1, characterized in that the quantum dot-containing composition further comprises one or more selected from a curing agent, a polymerization initiator, a solvent, and a light scattering agent. 　 The quantum dot-containing composition according to claim 1, characterized in that the quantum dot contains a quantum dot core selected from the group consisting of Group II-VI, Group III-V, Group IV, Group IV-VI, Group I-III-VI, Group II-IV-V, and compounds having a mixed crystal, alloy, or perovskite structure thereof. 　 The quantum dot-containing composition according to claim 3, characterized in that the quantum dots include core-shell type quantum dots in which the quantum dot core is coated with a shell having a larger band gap than the quantum dot core. 　 The quantum dot-containing composition according to claim 1, characterized in that the ligand has one or more of the following: an amino group, a thiol group, a carboxyl group, a phosphin group, a phosphine oxide group, and an ammonium ion. 　 The quantum dot-containing composition according to claim 1, characterized in that the reactive substituent contained in the silicone oligomer has one or more of the following: a vinyl group, an acrylic group, a methacrylic group, a hydroxyl group, a phenolic hydroxyl group, an epoxy group, and an alkoxysilyl group. 　 A wavelength conversion member characterized by being a cured product of a quantum dot-containing composition according to any one of claims 1 to 6. 　 A method for producing a quantum dot-containing composition according to any one of claims 1 to 6, which contains quantum dots that emit fluorescence upon excitation light, A ligand exchange step involves mixing a solution in which the quantum dots are dispersed with a ligand containing a siloxane bond, thereby coordinating the ligand to the outermost surface of the quantum dots. A method for producing a quantum dot-containing composition, characterized by comprising the ligand exchange step followed by a silicone oligomer mixing step of mixing the quantum dots to which the ligands are coordinated with the silicone oligomer.

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