Quantum dots, quantum dot dispersions, photo-conversion curable compositions, color filters, photo-conversion laminated substrates, and image display devices

Abstract

To provide a quantum dot superior in oxidation stability and reliability.SOLUTION: There is provided a quantum dot having a ligand layer on the surface in which the ligand layer includes compounds of a particular chemical formula structure, and a quantum dot dispersion including the quantum dot, and a light conversion curable composition are also provided. The disclosed quantum dot is superior in oxidation stability and reliability and is effectively applicable to various applications such as color filters and light conversion laminated base materials.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to quantum dots, quantum dot dispersions, photo-convertible curable compositions, color filters, photo-convertible laminated substrates, and image display devices.

Background Art

[0002] Quantum dots have high luminescence and a narrow emission spectrum, and the emission wavelength can be adjusted at a single excitation wavelength. Since they have the unique properties of quantum dots that are stable to light, many studies have been conducted recently for use in important application fields such as bioimaging, energy conversion, and lighting (LED).

[0003] Such quantum dots are substances with extremely sensitive surface states. Oxidation occurs from the surface due to the dispersed solvent or the surrounding environment, and ultimately, the emission efficiency decreases rapidly. For various applications of quantum dots, they must be dispersed in various solvents in addition to the initially dispersed organic solvent, or specific functional groups must be formed on the surface. However, such processes damage the surface of the quantum dots, ultimately leading to a problem of a decrease in emission efficiency.

[0004] Many attempts have been made to overcome such problems, and various methods are currently proposed. One of them is the ligand exchange method of substituting the organic substances present on the surface of quantum dots with molecules having desired functional groups. This method is a method of substituting the organic molecules present on the surface of quantum dots with organic molecules suitable for application, but since it directly affects the surface of quantum dots, it has a demerit of causing a fatal problem in emission efficiency.

[0005] Korean Patent Publication No. 10-2018-0002716 and Korean Registered Patent No. 10-1628065 disclose quantum dots containing ligands disposed on the surface, but there are problems such as low compatibility, poor dispersibility, not only a decrease in stability and reliability, but also poor heat resistance.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] One object of the present invention is to provide quantum dots having excellent oxidation stability and reliability.

[0008] Another object of the present invention is to provide a quantum dot dispersion containing the quantum dots and a photo-conversion curable composition containing the quantum dot dispersion.

[0009] Furthermore, an object of the present invention is to provide a color filter, a photo-conversion laminated substrate, and an image display device including a cured film formed using the photo-conversion curable composition.

Means for Solving the Problems

[0010] The present invention provides quantum dots having a ligand layer on the surface, wherein the ligand layer contains a compound represented by the following Chemical Formula 1.

Chemical Formula

[0011] Further, the present invention provides a quantum dot dispersion containing the quantum dots. Further, the present invention provides a light-converting curable composition containing the quantum dot dispersion. Furthermore, the present invention provides a color filter or a light-converting laminated substrate including a cured film formed using the light-converting curable composition. Further, the present invention provides an image display device including the color filter or the light-converting laminated substrate.

Advantages of the Invention

[0012] The quantum dots according to the present invention include a compound represented by a specific chemical formula structure as a ligand layer, whereby the surface of the quantum dots is protected and excellent in oxidation stability, so that improved optical properties can be exhibited, and relatively little viscosity change can be provided during long-term storage, providing excellent reliability.

[0013] In addition, when the photocurable composition containing the quantum dots of the present invention is used, it is possible to form a cured film that is excellent in photocatalytic conversion efficiency and heat resistance and can reduce the amount of outgas generated during production, and it can be effectively applied to various applications such as color filters and photocatalytic conversion laminated substrates.

Embodiments for Carrying Out the Invention

[0014] The present invention provides quantum dots having a ligand layer on the surface, wherein the ligand layer contains a compound having a specific chemical formula structure, a quantum dot dispersion containing the quantum dots, and a photocurable composition. Further, the quantum dots according to the present invention are excellent in oxidation stability and reliability and can be effectively applied to various applications such as color filters and photocatalytic conversion laminated substrates.

[0015] Furthermore, the present invention provides an image display device including the color filter or the photocatalytic conversion laminated substrate.

[0016] As used herein, the alkyl group can mean a monovalent aliphatic saturated hydrocarbon, including linear alkyl groups such as methyl group, ethyl group, propyl group, and butyl group; branched alkyl groups such as isopropyl group, sec-butyl group, tert-butyl group, and neopentyl group.

[0017] As used herein, the alkylene group means a linear or branched divalent hydrocarbon having 1 to 30 carbon atoms, and includes, for example, methylene group, ethylene group, n-propylene group, i-propylene group, etc., but is not limited thereto.

[0018] As used herein, the cycloalkyl group can include all cyclic saturated hydrocarbons or cyclic unsaturated hydrocarbons containing one or more unsaturated bonds.

[0019] As used herein, an alkenyl group can mean an alkyl group containing one or more double bonds.

[0020] As used herein, an alkynyl group can mean an alkyl group containing one or more triple bonds.

[0021] <Quantum dot> In the present invention, the quantum dot may be one that emits spontaneous light by a light source and is used to generate light in the visible light and infrared regions. The quantum dot is a substance having a crystal structure of several nanosizes and may be composed of several hundreds to several thousands of atoms. Atoms form molecules, and the molecules form an aggregate of small molecules called clusters to form nanoparticles. Usually, when such nanoparticles particularly have semiconductor characteristics, they are called quantum dots. The quantum dots of the present invention are not particularly limited as long as they conform to such a concept. When an object becomes smaller than the nanosize, a quantum confinement effect, which is a phenomenon in which the energy band gap of the object increases, appears. When the quantum dot receives energy from the outside and reaches an excited state, it emits energy corresponding to the energy band gap by itself and can emit spontaneous light.

[0022] The quantum dot according to the present invention is characterized by having a ligand layer on the surface, and the ligand layer contains a compound represented by the following Chemical Formula 1. Thereby, the surface of the quantum dot is protected, excellent oxidation stability is achieved, a decrease in quantum efficiency is prevented, excellent light characteristics are shown, and reliability can be improved. [Chemical formula]

[0023] In the Chemical Formula 1, A may be a carboxyl group (-COOH), a thiol group (-SH), or an amino group (-NH2), or may be a monovalent substituent containing these groups.

[0024] R1 and R2 may each independently be a direct bond, a linear or branched alkylene group having 1 to 20 carbon atoms.

[0025] L may be a cycloalkylene group having 3 to 20 carbon atoms, a heterocycloalkylene group having 2 to 20 carbon atoms, or a heteroarylene group having 3 to 20 carbon atoms. In the present invention, "hetero" means an integral structure containing elements other than carbon and hydrogen in the structure, and preferably may be a structure containing nitrogen, sulfur, or oxygen.

[0026] X may be a direct bond, an ester group, or an amide group (however, when A is a carboxyl group, X is not an ester group). The ester group or amide group may each be a divalent substituent containing an ester structure and an amide structure, or derived therefrom. In the present invention, "derived from" means a structure in which one or more hydrogen atoms have been removed from the structural formula.

[0027] Y may be a linear or branched alkylene group having 1 to 20 carbon atoms, a polyethylene glycol group having 2 to 30 carbon atoms, or a linear or branched polypropylene glycol group. The polyethylene glycol group and polypropylene glycol group in the present invention each mean a structure in which ethylene glycol groups and propylene glycol groups are repeated two or more times.

[0028] Z is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, or a photopolymerizable reactive group having 2 to 30 carbon atoms. The photopolymerizable reactive group is not particularly limited as long as it is a photopolymerizable substituent, and may be a structure containing a double bond or a triple bond, and preferably may be an alkenyl group, an alkynyl group, a phenyl group, or an acrylate group.

[0029] In one embodiment of the present invention, the compound represented by Chemical Formula 1 may be a compound represented by any one of the following Chemical Formulas 1-1 to 1-7.

Chemical Formula

[0030] In the present invention, the compound represented by Chemical Formula 1 can serve to coordinate and bond to the surface of quantum dots as an organic ligand to stabilize the quantum dots.

[0031] Normally produced quantum dots generally have a ligand layer on their surface. The ligand layer immediately after production may consist of oleic acid, lauric acid, 2-(2-methoxyethoxy)acetic acid, 2-[2-(2-methoxyethoxy)ethoxy]acetic acid, and succinic acid mono-[2-(2-methoxy-ethoxy)-ethyl]ester. In this case, compared with the quantum dots of the present invention containing the compound represented by Chemical Formula 1 as the ligand layer, the surface protection effect may be reduced due to unbonded defects on the surface of the quantum dots caused by a weaker binding force between the ligand layer and the quantum dots. Also, in the case of oleic acid, it is easily dispersed in saturated hydrocarbon solvents such as n-hexane, which is a highly volatile compound (VOC; volatile organic compound), and aromatic solvents such as chloroform and benzene, but has poor dispersibility in solvents and monomers (photopolymerizable compounds) such as PGMEA.

[0032] The quantum dots according to the present invention contain the compound represented by Chemical Formula 1 in the ligand layer, so that the surface of the quantum dots is protected. Therefore, they can not only exhibit excellent oxidation stability compared with conventional quantum dots, but also have extremely excellent dispersibility in solvents and monomers such as PGMEA, and the effect of improving the optical properties appears.

[0033] In some embodiments, the quantum dots according to the present invention include the compound represented by the chemical formula 1 in the ligand layer and may further include oleic acid, lauric acid, 2-(2-methoxyethoxy)acetic acid, 2-[2-(2-methoxyethoxy)ethoxy]acetic acid, and succinic acid mono-[2-(2-methoxy-ethoxy)-ethyl]ester, etc.

[0034] The quantum dots are not particularly limited as long as they are quantum dot particles that can emit light upon stimulation by light or electricity. For example, they may be selected from the group consisting of II-VI group semiconductor compounds; III-V group semiconductor compounds; IV-VI group semiconductor compounds; group IV elements or compounds containing the same; and combinations thereof, and these can be used alone or in combination of two or more.

[0035] For example, the II-VI group semiconductor compound may be selected from the group consisting of binary compounds selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, and mixtures thereof; ternary compounds selected from the group consisting of CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, and mixtures thereof; and quaternary compounds selected from the group consisting of CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, and mixtures thereof, but is not limited thereto.

[0036] The III-V semiconductor compound may be selected from the group consisting of binary compounds selected from the group consisting of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, and mixtures thereof; ternary compounds selected from the group consisting of GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, and mixtures thereof; and quaternary compounds selected from the group consisting of GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, and mixtures thereof, but is not limited thereto.

[0037] The IV-VI semiconductor compound may be one or more selected from the group consisting of binary compounds selected from the group consisting of SnS, SnSe, SnTe, PbS, PbSe, PbTe, and mixtures thereof; ternary compounds selected from the group consisting of SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, and mixtures thereof; and quaternary compounds selected from the group consisting of SnPbSSe, SnPbSeTe, SnPbSTe, and mixtures thereof, but is likewise not limited thereto.

[0038] The Group-IV element or the compound containing the same may be selected from the group consisting of elements selected from the group consisting of Si, Ge, and mixtures thereof; and binary compounds selected from the group consisting of SiC, SiGe, and mixtures thereof, but is not limited thereto.

[0039] Quantum dots may have a homogeneous single structure, a double structure such as a core-shell structure and a gradient structure, or a mixed structure thereof. In the present invention, the type of quantum dots is not particularly limited as long as they can emit light upon optical stimulation.

[0040] According to one embodiment, the quantum dots have a core-shell structure. The core includes one or more selected from the group consisting of InP, InZnP, InGaP, CdSe, CdS, CdTe, ZnS, ZnSe, ZnTe, CdSeTe, CdZnS, CdSeS, PbSe, PbS, PbTe, AgInZnS, HgS, HgSe, HgTe, GaN, GaP, GaAs, InGaN, InAs, and ZnO. The shell can include one or more selected from the group consisting of ZnS, ZnSe, ZnTe, ZnO, CdS, CdSe, CdTe, CdO, InP, InS, GaP, GaN, GaO, InZnP, InGaP, InGaN, InZnSCdSe, PbS, TiO, SrSe, and HgSe. Preferably, it can include one or more selected from the group consisting of InP / ZnS, InP / ZnSe, InP / GaP / ZnS, InP / ZnSe / ZnS, InP / ZnSeTe / ZnS, and InP / MnSe / ZnS, but is not limited thereto.

[0041] Generally, quantum dots can be manufactured by a wet chemical process, a metal organic chemical vapor deposition (MOCVD) process, or a molecular beam epitaxy (MBE) process.

[0042] The quantum dots according to the present invention can be synthesized by a wet chemical process.

[0043] The wet chemical process is a method of growing particles by placing a precursor substance in an organic solvent. When crystals grow, the organic solvent is naturally coordinated to the surface of the quantum dot crystal to act as a dispersant and regulate crystal growth. Therefore, the size growth of quantum dot particles can be controlled by a process that is easier and less expensive than vapor deposition methods such as metalorganic chemical vapor deposition and molecular beam epitaxy.

[0044] When manufacturing quantum dots by the wet chemical process, an organic ligand is used to prevent aggregation of the quantum dots and control the particle size of the quantum dots at the nanolevel. As such an organic ligand, oleic acid can generally be used.

[0045] In one embodiment of the present invention, the oleic acid used in the process of manufacturing the quantum dots is replaced with the compound represented by Chemical Formula 1 by a ligand exchange method.

[0046] The ligand exchange is performed by adding the organic ligand to be exchanged, that is, the compound represented by Chemical Formula 1, to a dispersion containing quantum dots having the original organic ligand, that is, oleic acid, and stirring this at room temperature to 200 °C for 30 minutes to 3 hours to obtain quantum dots to which the compound represented by Chemical Formula 1 is bound.

[0047] If necessary, a process of separating and purifying the quantum dots to which the compound represented by Chemical Formula 1 is bound may be additionally performed.

[0048] Quantum dots according to one embodiment of the present invention can be manufactured by an organic ligand exchange method under simple stirring treatment at room temperature as described above, and have the merit of being mass-producible.

[0049] Also, quantum dots according to one embodiment of the present invention can maintain quantum efficiency even under high-temperature conditions and can ensure stable optical properties during the display manufacturing process.

[0050] <Quantum dot dispersion> One embodiment of the present invention relates to a quantum dot dispersion. The quantum dot dispersion according to the present invention contains the above-described quantum dots and monomers.

[0051] Quantum dot In the present invention, the quantum dots are contained in an amount of 10 to 95% by weight, preferably 20 to 90% by weight, more preferably 20 to 80% by weight, based on the total solid content of the quantum dot dispersion. When the quantum dots are contained within the above range, it is possible to provide a photo-curable composition having excellent light-emitting properties. When the quantum dots are contained in an amount less than the above content range, the light characteristics may deteriorate, making it difficult to realize a high-quality display device. Further, when the content exceeds the above range, the components for realizing curing may be insufficient, resulting in insufficient curing degree of the coating film and reducing the productivity in the subsequent processes of display manufacturing and the reliability of the product.

[0052] Monomer The monomer contained in the quantum dot dispersion of the present invention is a photopolymerizable compound that serves to disperse the quantum dots.

[0053] Examples of the monomers used in the present invention include monofunctional monomers, difunctional monomers, and other polyfunctional monomers. Preferably, monomers having two or more functional groups can be used.

[0054] The monomer can be the same substance as the photopolymerizable compound used in the photo-curable composition described below.

[0055] In the present invention, the monomer may be used alone or in combination of two or more monomers.

[0056] The type of the monofunctional monomer is not particularly limited, and examples thereof include nonylphenyl carbitol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-ethylhexyl carbitol acrylate, 2-hydroxyethyl acrylate, and the like.

[0057] The type of the bifunctional monomer is not particularly limited. For example, it may include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol (meth)acrylate, triethylene glycol (meth)acrylate, neopentyl glycol di(meth)acrylate, dineopentyl glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, bis(acryloyloxyethyl) ether of bisphenol A, 3-methylpentanediol di(meth)acrylate, and the like.

[0058] The type of the polyfunctional monomer is not particularly limited. For example, it may include trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, ethoxylated dipentaerythritol hexa(meth)acrylate, propoxylated dipentaerythritol hexa(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and the like.

[0059] The monomer contained in the quantum dot dispersion of the present invention is contained in an amount of 10 to 90% by weight, preferably 20 to 80% by weight, more preferably 30 to 70% by weight, based on the total solid content of the quantum dot dispersion.

[0060] If it is less than the above-mentioned content range, coating or jetting characteristics may deteriorate due to a decrease in dispersion characteristics or an increase in the viscosity of the dispersion. Conversely, if it exceeds the above range, the light source absorption rate of the quantum dots may be insufficient, resulting in a decrease in color reproducibility and a decrease in optical characteristics due to a decrease in luminous efficiency performance.

[0061] Solvent The quantum dots according to the present invention can be dispersed using a solvent.

[0062] Examples of the solvent include alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, and ethylene glycol monobutyl ether; diethylene glycol dialkyl ethers such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, and diethylene glycol dibutyl ether; methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, methoxybutyl acetate, pentyl acetate (n-Pentyl acetate), and the like. In the present invention, the solvent may be used alone or in combination with the above-mentioned monomer.

[0063] The solvent is contained in an amount of 10 to 90% by weight, preferably 20 to 80% by weight, based on the total quantum dot dispersion. If the solvent is contained in an amount less than the above range, the dispersion characteristics may deteriorate, resulting in a decrease in film-forming characteristics due to foreign substances and a deterioration of the light-emitting characteristics. If the solvent is contained in an amount greater than the above range, a decrease in the color region of the display may occur due to insufficient luminous intensity and light leakage of the light source. Therefore, it is preferable to satisfy the above range.

[0064] In the quantum dot (QD) dispersion, the quantum dots can be dispersed with either the monomer or the solvent alone, or a quantum dot (QD) dispersion can be produced by mixing the monomer and the solvent and thereby dispersing the quantum dots.

[0065] <Photoconvertible curable composition> The photoconvertible curable composition of the present invention contains the above-described quantum dot dispersion.

[0066] Furthermore, it can further contain one or more selected from scattering particles, a photopolymerizable compound, a resin, and a photoinitiator, and if necessary, it can also further contain constituent components such as additives known in the art.

[0067] Hereinafter, each component contained in the photoconvertible curable composition of the present invention will be described in detail.

[0068] Quantum dot dispersion The quantum dot dispersion contained in the photoconvertible curable composition of the present invention is applied as the above-described quantum dot dispersion as it is.

[0069] When the photoconvertible curable composition of the present invention contains 10 to 80% by weight of the quantum dot dispersion with respect to the whole photoconvertible curable composition, the produced photoconvertible curable composition can exhibit desired viscosity characteristics and excellent photoluminescence characteristics. From this aspect, it is preferable that the photoconvertible curable composition of the present invention contains 20 to 70% by weight of the quantum dot dispersion.

[0070] Scattering particle The photoconvertible curable composition according to the present invention can contain scattering particles.

[0071] As the scattering particles, ordinary inorganic materials can be used, and preferably, it can contain metal oxides having an average particle diameter of 30 to 1000 nm.

[0072] The metal oxide may be, but is not limited to, an oxide containing one metal selected from the group consisting of Li, Be, B, Na, Mg, Al, Si, K, Ca, Sc, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, Rb, Sr, Y, Mo, Cs, Ba, La, Hf, W, Tl, Pb, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Ti, Sb, Sn, Zr, Nb, Ce, Ta, In, and combinations thereof.

[0073] Specifically, one selected from the group consisting of Al2O3, SiO2, ZnO, ZrO2, BaTiO3, TiO2, Ta2O5, Ti3O5, ITO, IZO, ATO, ZnO-Al, Nb2O3, SnO, MgO, and combinations thereof is possible. If necessary, a material surface-treated with a compound having an unsaturated bond such as acrylate can also be used.

[0074] When the photo-conversion curable composition according to the present invention contains scattering particles, it is preferable because it can increase the path of the light spontaneously emitted from the quantum dots through the scattering particles and enhance the overall light efficiency in the color filter or the photo-conversion laminated substrate.

[0075] Preferably, the scattering particles can have an average particle size of 30 to 1000 nm, and preferably those in the range of 100 to 500 nm are used. At this time, if the particle size is too small, a sufficient scattering effect of the light emitted from the quantum dots cannot be expected. On the contrary, if it is too large, the particles will sink in the composition or a surface of the self-luminous layer with uniform quality cannot be obtained. Therefore, it is appropriately adjusted and used within the above range.

[0076] The scattering particles can be used in an amount of 0.1 to 50% by weight, preferably 0.5 to 30% by weight, based on the total amount of the photo-convertible curable composition. When the scattering particles are contained within the above range, it is preferable because the effect of increasing the emission intensity can be maximized. When the scattering particles are contained in an amount less than the above range, it becomes somewhat difficult to ensure the desired emission intensity. When the amount exceeds the above range, not only is the effect of increasing the emission intensity insufficient, but problems such as a decrease in the stability of the composition may occur. Therefore, it is preferably used appropriately within the above range.

[0077] Photopolymerizable compound The photopolymerizable compound in the present invention is a compound that can be polymerized by the action of light and a photoinitiator described later, and examples thereof include monofunctional monomers, bifunctional monomers, and other polyfunctional monomers. Preferably, monomers having two or more functional groups are used.

[0078] The photopolymerizable compound contained in the photo-convertible curable composition of the present invention can contain a compound of the same or different type as the monomer contained in the quantum dot dispersion.

[0079] The type of the monofunctional monomer is not particularly limited, and examples thereof include nonylphenyl carbitol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-ethylhexyl carbitol acrylate, 2-hydroxyethyl acrylate, N-vinylpyrrolidone, and the like.

[0080] The type of the bifunctional monomer is not particularly limited, and examples thereof include 1,6-hexanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, bis(acryloyloxyethyl) ether of bisphenol A, 3-methylpentanediol di(meth)acrylate, and the like.

[0081] The type of the polyfunctional monomer is not particularly limited. For example, it includes trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, ethoxylated dipentaerythritol hexa(meth)acrylate, propoxylated dipentaerythritol hexa(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and the like.

[0082] The total weight of the "monomer" contained during the production of the quantum dot dispersion and the "photopolymerizable compound" contained in the photo-conversion curable composition accounts for 40% by weight or more, preferably 40 - 90% by weight, and more preferably 40 - 80% by weight based on the total photo-conversion curable composition.

[0083] If the content of the photopolymerizable compound is less than the above range, the heat resistance is poor, the amount of outgas generation increases, and the possibility of quantum dots being oxidized during the process progress is high.

[0084] Conversely, if it exceeds the above range, the amount (content) of quantum dots that can be introduced decreases, and thus the optical properties may deteriorate.

[0085] Resin The photo-conversion curable composition according to the present invention can contain a resin.

[0086] The resin can include a cardo resin, an acrylic resin, an epoxy resin, or a combination thereof.

[0087] The cardo resin, acrylic alkali-soluble resin, or epoxy resin has reactivity by the action of light or heat and functions to improve the dispersibility of quantum dots.

[0088] The resin contained in the photoconversion curable composition of the present invention acts as a binder resin for quantum dots and is not particularly limited as long as it is a resin that can be used as a support for the photoconversion coating layer.

[0089] The resin can be used in an amount of 0.01 to 30% by weight, preferably 0.1 to 20% by weight, based on the total amount of the photoconversion curable composition. When the resin is contained within the above range, the formation of the photoconversion curable composition is easy, and the protective properties of the quantum dots are good, resulting in excellent light emission properties and reliability.

[0090] Photopolymerization initiator The photopolymerization initiator in the present invention is a compound for initiating the polymerization of the photopolymerizable compound described above, and is not particularly limited in the present invention. However, acylphosphine-based, acetophenone-based, benzophenone-based, triazine-based, thioxanthone-based, oxime-based, benzoin-based, anthracene-based, anthraquinone-based, and biimidazole-based compounds can be used, and these can be used alone or in combination of two or more.

[0091] As an example, examples of the benzophenone-based compound include benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, and the like.

[0092] As other photopolymerization initiators, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 10-butyl-2-chloroacridone, 9,10-phenanthrenequinone, camphorquinone, methyl phenylglyoxylate, titanocene compounds, and the like can be used.

[0093] The content of such a photopolymerization initiator is 0.1 to 20% by weight, preferably 0.5 to 15% by weight, based on the total amount of the photoconversion curable composition.

[0094] When the content of the photopolymerization initiator is within the above range, the photo-conversion curable composition is highly sensitive, and the strength of the pixel portion and the smoothness on the surface of the pixel portion tend to be good, so it is preferable. Further, when the content of the photopolymerization initiation auxiliary agent is within the above range, the sensitivity efficiency of the photo-conversion curable composition becomes even higher, and the productivity of the color filter formed using this composition tends to improve, so it is preferable.

[0095] Additive The photo-conversion curable composition according to the present invention can further contain known additives for various purposes. As such additives, for example, it is also possible to use additives such as fillers, other polymer compounds, curing agents, adhesion promoters, antioxidants, ultraviolet absorbers, and anti-aggregation agents in combination. One or more of these additives are possible, and in consideration of light efficiency and the like, it is preferable to use them at 1% by weight or less in the whole composition.

[0096] The photo-conversion curable composition according to the present invention is excellent in light characteristics, heat resistance, and viscosity characteristics, and can minimize the emission of outgas, so it can be effectively applied when forming a cured film contained in a color filter or a photo-conversion laminated substrate.

[0097] <Cured film> The present invention provides a cured film formed using the photo-conversion curable composition, and the cured film is contained in a color filter or a photo-conversion laminated substrate.

[0098] <Color filter> As a pattern formation method for forming the color filter of the present invention, a method known in the art can be used.

[0099] Taking one embodiment as an example, the pattern formation method is a) a step of applying a photo-conversion ink composition to a substrate; b) a pre-bake step of drying the solvent; c) applying a photomask onto the obtained film and irradiating with actinic rays to cure the exposed areas; d) developing the unexposed areas by dissolving them using an aqueous alkali solution; e) performing drying and post-baking steps, which may be included. The substrate may be a glass substrate or a polymer substrate, but is not limited thereto. As the glass substrate, in particular, soda lime glass, barium- or strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, or quartz can be preferably used. Examples of the polymer substrate include polycarbonate, acrylic, polyethylene terephthalate, polyethersulfide, or polysulfone substrate.

[0100] At this time, the coating is performed by a known wet coating method using a coating apparatus such as a roll coater, spin coater, slit and spin coater, slit coater (sometimes also referred to as a die coater), or inkjet so as to obtain a desired thickness.

[0101] The pre-baking is performed by heating with an oven, hot plate, or the like. At this time, the heating temperature and heating time in the pre-baking are appropriately selected depending on the solvent used, and for example, it is performed at a temperature of 80 to 150°C for 1 to 30 minutes.

[0102] Also, the exposure performed after the pre-baking is to expose to light emitted from an exposure device. At this time, as the light to be irradiated, for example, visible light, ultraviolet rays, X-rays, and electron beams can be used.

[0103] The development process of dissolving the unexposed portion using an alkaline aqueous solution after exposure is carried out for the purpose of removing the photosensitive resin composition of the portion where the unexposed portion is not removed, and a desired pattern is formed by this development. As a developer suitable for development using this alkaline aqueous solution, for example, an aqueous solution of a carbonate of an alkali metal or an alkaline earth metal can be used. In particular, an alkaline aqueous solution containing less than 1 to 3% by weight of a carbonate such as sodium carbonate, potassium carbonate, or lithium carbonate is used, and development can be carried out using a developing device or an ultrasonic cleaner at a temperature of 10 to 50 °C, preferably 20 to 40 °C.

[0104] Post-baking is carried out to enhance the adhesion between the patterned film and the substrate. For example, it is carried out by heat treatment under the conditions of 80 to 250 °C for 10 to 120 minutes. Post-baking can be carried out using an oven, a hot plate, etc., similar to pre-baking.

[0105] Light conversion laminated substrate The light conversion laminated substrate according to the present invention includes a cured product of a light conversion curable composition that can be coated on a glass substrate. By including a light conversion resin composition that can be coated on a glass substrate, a solvent that does not correspond to harmful substances to the human body can be used, and the safety of workers and the productivity of products can be improved.

[0106] The light conversion laminated substrate can include silicon (Si), silicon oxide (SiOx), or a polymer substrate, and the polymer substrate may be polyethersulfone (PES) or polycarbonate (PC), etc.

[0107] The light conversion laminated substrate is formed by applying the light conversion curable composition and thermally curing it.

[0108] <Image display device> The image display device according to the present invention includes the color filter or the light conversion laminated substrate described above. Specifically, the image display device includes a liquid crystal display (liquid crystal display device; LCD), an organic EL display (organic EL display device), a liquid crystal projector, a display device for a game machine, a display device for a mobile terminal such as a mobile phone, a display device for a digital camera, a display device for a car navigation, etc. Among them, a color display device is particularly preferable.

[0109] Except for including the color filter or the light conversion laminated substrate, the image display device may further include a configuration known to those skilled in the technical field of the present invention. That is, the present invention includes an image display device to which a color filter or a light conversion laminated substrate can be applied.

[0110] The image display device including the color filter according to the present invention can have excellent characteristics in color reproducibility, luminance, heat resistance, reliability, etc.

Examples

[0111] Hereinafter, the present invention will be described in more detail through examples. However, the following examples are for more specifically explaining the present invention, and the scope of the present invention is not limited by the following examples.

[0112] Synthesis Example 1: Synthesis of InP / ZnSe / ZnS Core-Shell Quantum Dots 0.4 mmol (0.058 g) of indium acetate, 0.6 mmol (0.15 g) of palmitic acid, and 20 mL of 1-octadecene were placed in a reactor and heated to 120 °C under vacuum. After 1 hour, the atmosphere in the reactor was switched to nitrogen. After heating to 280 °C, a mixed solution of 0.2 mmol (58 μl) of tris(trimethylsilyl)phosphine (TMS3P) and 1.0 mL of trioctylphosphine was quickly injected and reacted for 0.5 minutes.

[0113] Next, 2.4 mmol (0.448 g) of zinc acetate, 4.8 mmol of oleic acid, and 20 mL of trioctylamine were placed in a reactor and heated to 120 °C under vacuum. After 1 hour, the atmosphere in the reactor was switched to nitrogen, and the reactor was heated to 280 °C. 2 mL of the previously synthesized InP core solution was added, and then 4.8 mmol of selenium in trioctylphosphine (Se / TOP) was added. The final mixture was then reacted for 2 hours. Ethanol was added to the reaction solution rapidly cooled to room temperature, and the precipitate obtained by centrifugation was filtered under reduced pressure and then dried under reduced pressure to form InP / ZnSe core-shell.

[0114] Next, 2.4 mmol (0.448 g) of zinc acetate, 4.8 mmol of oleic acid, and 20 mL of trioctylamine were placed in a reactor and heated to 120 °C under vacuum. After 1 hour, the atmosphere in the reactor was switched to nitrogen, and the reactor was heated to 280 °C. 2 mL of the previously synthesized InP core solution was added, and then 4.8 mmol of sulfur in trioctylphosphine (S / TOP) was added. The final mixture was then reacted for 2 hours. Ethanol was added to the reaction solution rapidly cooled to room temperature, and the precipitate obtained by centrifugation was filtered under reduced pressure and then dried under reduced pressure to obtain quantum dots with an InP / ZnSe / ZnS core-shell structure, which were then dispersed in chloroform. The solid content was adjusted to 10%. The maximum emission wavelength was 520 nm.

[0115] Examples 1 to 7 and Comparative Examples 1 to 4: Production of quantum dot dispersion Example 1: Quantum Dot Dispersion A-1 1) Ligand Substitution Reaction 5 mL of the quantum dot solution obtained in Synthesis Example 1 was placed in a centrifuge tube, and 20 mL of ethanol was added to precipitate. The supernatant was discarded by centrifugation, 3 mL of chloroform was added to the precipitate to disperse the quantum dots, and then 1.0 g of the compound represented by Chemical Formula 1-1 was added. The reaction was carried out for 1 hour while heating to 60 °C under a nitrogen atmosphere. 25 mL of n-hexane was added to the reaction product to precipitate the quantum dots, and then centrifugation was performed to separate the precipitate, which was then dried in a vacuum oven at 60 °C for 3 hours.

[0116] 2) Preparation of Quantum Dot Dispersion After adding 1,6-Hexanediol diacrylate to the obtained quantum dot powder to a solid content of 50%, it was stirred to produce a quantum dot dispersion. The maximum emission wavelength was 520 nm.

Chemical formula

[0117] Example 2: Quantum dot dispersion A-2 The procedure was the same as in Example 1, except that the compound represented by the following Chemical formula 1-2 was used instead of the ligand used in Example 1. The maximum emission wavelength was 522 nm.

Chemical formula

[0118] Example 3: Quantum dot dispersion A-3 The procedure was the same as in Example 1, except that the compound represented by the following Chemical formula 1-3 was used instead of the ligand used in Example 1. The maximum emission wavelength was 522 nm.

Chemical formula

[0119] Example 4: Quantum dot dispersion A-4 The procedure was the same as in Example 1, except that the compound represented by the following Chemical formula 1-4 was used instead of the ligand used in Example 1. The maximum emission wavelength was 522 nm.

Chemical formula

[0120] Example 5: Quantum dot dispersion A-5 The procedure was the same as in Example 1, except that the compound represented by the following Chemical formula 1-5 was used instead of the ligand used in Example 1. The maximum emission wavelength was 522 nm.

Chemical formula

[0121] Example 6: Quantum Dot Dispersion A-6 The procedure was the same as in Example 1, except that the compound represented by the following Chemical Formula 1-6 was used instead of the ligand used in Example 1. The maximum emission wavelength was 522 nm. [Chemical Formula]

[0122] Example 7. Quantum Dot Dispersion A-7 The procedure was the same as in Example 1, except that the compound represented by the following Chemical Formula 1-7 was used instead of the ligand used in Example 1. The maximum emission wavelength was 522 nm. [Chemical Formula]

[0123] Comparative Example 1: Quantum Dot Dispersion A-8 (No Ligand Exchange Reaction Performed) 5 mL of the quantum dot solution obtained in Synthesis Example 1 was placed in a centrifuge tube, and 20 mL of ethanol was added to precipitate the quantum dots. After discarding the supernatant and separating the precipitate, it was dried in a vacuum oven at 60 °C for 3 hours. After adding 1,6-Hexanediol diacrylate to the obtained quantum dot powder to a solid content of 50%, it was stirred to produce a quantum dot dispersion. The maximum emission wavelength was 520 nm.

[0124] Comparative Example 2: Quantum Dot Dispersion A-9 The procedure was the same as in Example 1, except that Octylamine was used instead of the ligand used in Example 1. The maximum emission wavelength was 522 nm.

[0125] Comparative Example 3: Quantum Dot Dispersion A-10 The procedure was the same as in Example 1, except that 5-Oxohexanoic Acid was used instead of the ligand used in Example 1. The maximum emission wavelength was 522 nm.

[0126] Comparative Example 4: Quantum Dot Dispersion A-11 The procedure of Example 1 was repeated, except that the compound represented by the following Chemical Formula 2 was used instead of the ligand used in Example 1. The maximum emission wavelength was 522 nm. [Chemical Formula]

[0127] Experimental Example (1) Quantum Efficiency The quantum efficiency (QY%) at the initial stage of production and the absolute quantum efficiency (QY%) after standing at room temperature for 15 days of the quantum dot dispersions of Examples 1 to 7 and Comparative Examples 1 to 4 were measured using QE-2100 (manufactured by Otsuka Corporation).

[0128] Since the quantum efficiency decreases due to the oxidation of the quantum dot surface, the decrease amount of the quantum efficiency can be measured to confirm the oxidation stability. That is, the oxidation stability can be confirmed by measuring ΔQY%. The measurement results are shown in Table 1 below.

[0129] (2) Viscosity Change Rate For the produced quantum dot dispersion, using an R-type viscometer (VISCOMETER MODELRE120L SYSTEM, product of Toki Sangyo Co., Ltd.), the initial viscosity and the change over time of the accelerated viscosity after storage at 40°C for 2 weeks were measured under the conditions of a rotation speed of 20 rpm and a temperature of 25°C. The viscosity change rate after storage at 40°C compared to the initial viscosity value is shown in Table 1 below.

[0130] [Table 1]

[0131] Examples 8 to 17 and Comparative Examples 5 to 8: Production of light conversion curable composition Using the quantum dot dispersions of A-1 to A-11 of the above Examples and Comparative Examples, a photo-curable composition was produced according to the components and contents shown in Table 2 below.

[0132]

Table 2

[0133] Experimental example (1) Manufacture of the light conversion coating layer Each of the light conversion curable compositions produced in Examples 8 to 17 and Comparative Examples 5 to 8 was applied onto a 5 cm × 5 cm glass substrate by an inkjet method, and then irradiated with a 1 kW high-pressure mercury lamp containing all of g, h, and i lines as an ultraviolet light source at 1000 mJ / cm 2 . (First step). Thereafter, it was heated in a heating oven at 180°C for 30 minutes to manufacture a light conversion coating layer (second step). The film thickness of the manufactured light conversion coating layer was measured using a film thickness measuring instrument (Dektak 6M, Vecco), and evaluation was carried out on a 10-μm coating film.

[0134] (2) Light conversion efficiency evaluation After the manufactured light conversion coating layer was positioned above a blue (blue) light source (XLamp XR-E LED, Royal blue450, Cree), the light conversion efficiency was measured and calculated using a luminance measuring instrument (CAS140CT Spectrometer, Instrument systems) and the following formula 1, and the results are shown in Table 3 below. The higher the light conversion efficiency (%), the better the luminance can be obtained.

Equation

[0135] (3) Heat resistance The manufactured light conversion coating layer was irradiated with a blue light source (XLamp XR-E LED, Royal blue450, illuminance 3 mW / cm 2, after placing it on top of (Cree), the luminance was measured using a luminance meter (CAS140CT Spectrometer, Instrument systems). After heating the same light conversion sheet in a heating oven at 230 °C for 30 minutes, the luminance was measured in the same manner as above, and the luminance retention rate after heating was calculated by the following formula 2 to evaluate the heat resistance. [Equation 2] Luminance retention rate = (luminance after treatment at 230 °C for 30 minutes) / (luminance before treatment at 230 °C for 30 minutes) X 100

[0136] (4) Measurement of outgas While heating the manufactured light conversion coating layer at 180 °C for 15 minutes, the gas components containing sublimable substances generated were collected, and the gas components were analyzed using GC / MS. Specifically, based on 100% of the volume of the compound components (outgas) detected from the gas components generated in the coating film formed of the composition of Comparative Example 1, the outgas amounts in the Examples and Comparative Examples were measured.

[0137]

Table 3

[0138] Referring to Table 3 above, it can be confirmed that the light conversion curable compositions of Examples 8 to 17 of the present application all have a light conversion efficiency of 30% or more, show relatively excellent light characteristics compared to Comparative Examples 5 to 8, and also show excellent characteristics in terms of heat resistance and the effect of reducing outgas.

Claims

1. A quantum dot having a ligand layer on its surface, The quantum dot in which the ligand layer contains one or more selected from the compounds represented by the following Chemical Formulas 1-1 to 1-7. 【Chemical Formula 1】

2. The quantum dot has a core-shell structure including a core and a shell covering the core, The core contains one or more of InP, InZnP, InGaP, CdSe, CdS, CdTe, ZnS, ZnSe, ZnTe, CdSeTe, CdZnS, CdSeS, PbSe, PbS, PbTe, AgInZnS, HgS, HgSe, HgTe, GaN, GaP, GaAs, InGaN, InAs, and ZnO, The shell contains one or more of ZnS, ZnSe, ZnTe, ZnO, CdS, CdSe, CdTe, CdO, InP, InS, GaP, GaN, GaO, GaS, InZnP, InGaP, InGaN, InZnSCdSe, PbS, TiO, SrSe, and HgSe. The quantum dot according to Claim 1.

3. A quantum dot dispersion containing the quantum dot according to Claim 1 or 2 and a monomer.

4. A photo-conversion curable composition containing the quantum dot dispersion according to Claim 3 and further containing any one or more selected from scattering particles, a photopolymerizable compound, a resin, and a photoinitiator.

5. The photo-conversion curable composition according to Claim 4, wherein the quantum dot dispersion is contained in an amount of 30% by weight to 80% by weight based on the total weight of the photo-conversion curable composition.

6. The photo-conversion curable composition according to Claim 4, wherein the resin contains a cardo resin, an acrylic resin, an epoxy resin, or a combination thereof.

7. A color filter including a cured film formed using the photo-conversion curable composition according to Claim 4.

8. An optical conversion laminated substrate including a cured film formed using the optical conversion curable composition according to claim 4.

9. An image display device including the color filter according to claim 7 or the optical conversion laminated substrate according to claim 8.

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