Quantum dot body, quantum dot composition, and wavelength conversion material, and methods for their production

Abstract

The present invention is a quantum dot body comprising a quantum dot that emits fluorescence in response to excitation light, the quantum dot body being characterized in that the quantum dot comprises a core of a semiconductor nanoparticle and a shell of a semiconductor nanoparticle that covers the core of the semiconductor nanoparticle, wherein the surface of the quantum dot is modified by a compound represented by formula (I) and having a methacryloyloxyethyl group and a hydrophilic group. As a result, a quantum dot body is provided that can maintain a high light emission efficiency and that exhibits improved dispersibility in highly polar solvents. (R1 represents a hydrophilic group.)

Description

Quantum dot body, quantum dot composition, wavelength conversion material, and methods for producing the same

[0001] The present invention relates to a quantum dot body, a quantum dot composition, a wavelength converting material, and methods for producing the same.

[0002] Quantum dots, which are semiconductor particles with nanometer-sized particle diameters, have discrete energy levels due to the confinement of excitons generated by light absorption in nanometer-sized spaces, and their band gaps depend on the particle diameter. As a result, quantum dots have highly efficient fluorescence emission and sharp emission spectra. Furthermore, because the band gap changes depending on the particle diameter, quantum dots have the advantage of being able to control the emission wavelength, making them promising for use as wavelength conversion materials in solid-state lighting and displays (Patent Document 1).

[0003] JP 2012-022028 A, International Publication No. 2011 / 081037, JP 2010-523557 A

[0004] Quantum dots containing Cd or Pb are examples of quantum dots that exhibit excellent fluorescence emission properties. However, because Cd and Pb are highly toxic to the human body and the environment, restrictions on their use are being considered around the world, including the European Union's RoHS Directive. Therefore, quantum dots that do not contain these toxic elements are being investigated.

[0005] Furthermore, quantum dots are prone to instability due to their small nanometer-sized particle diameter, large specific surface area, high surface energy, and surface activity. This makes them susceptible to surface defects due to dangling bonds and oxidation reactions on the quantum dot surface, which can cause deterioration of their fluorescence emission properties. Currently available quantum dots have these stability issues, and are known to experience deterioration of their emission properties due to heat, humidity, photoexcitation, and other factors.

[0006] To prevent this degradation, organic or inorganic ligands called ligands are attached to the quantum dot surface after synthesis. The ligands passivate the defects, suppressing the degradation of fluorescence efficiency.

[0007] Furthermore, the application of quantum dots as wavelength conversion materials to color filters used in displays and the like has been proposed as a packaging method. When applying quantum dots to color filters, it is important to create a quantum dot surface state suitable for the patterning method. Currently, color filters are primarily produced using a photolithography method in which a pigment-containing photosensitive resin composition is applied to a glass substrate, the solvent is dried, and the composition is exposed to UV light through a mask, and uncured portions are removed by alkaline development to form color patterns. This process is repeated to form blue, red, and green patterns. This photolithography method has many problems, such as significant raw material waste due to the uncured portions being wasted, and the process is complicated and requires expensive equipment.

[0008] For this reason, inkjet methods have been investigated in recent years. Inkjet methods are cost-competitive, as they eliminate raw material waste and allow for larger sizes and larger areas to be produced without the need for expensive equipment. However, the technology to create fine nozzles is difficult, and as nozzles become smaller, problems arise such as clogging and unstable discharge. Therefore, both photolithography, which has a proven track record in miniaturization, and inkjet methods, which are cost-competitive, are being investigated.

[0009] The challenge in both photolithography and inkjet printing is to prepare a resin composition containing quantum dots at a high concentration and with high dispersion. With the exception of a few resin compositions, quantum dots are dispersed in polar solvents such as propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME). However, quantum dots are essentially hydrophobic and difficult to disperse in these solvents and resin materials, resulting in aggregation, making it difficult to prepare a photosensitive resin composition containing quantum dots at a high concentration and with high dispersion.

[0010] Various studies have been conducted to date to disperse quantum dots in polar solvents. For example, in Patent Document 2, a composite in which semiconductor nanoparticles are dispersed in silica glass is produced by reacting a metal alkoxide with the surface of semiconductor nanoparticles in a stepwise manner to deposit a silica glass layer, making it possible to disperse the composite in water. However, the composite obtained by this production method has a problem in that the luminescence efficiency of the quantum dots is significantly reduced.

[0011] In addition, in Patent Document 3, it is possible to impart water solubility by producing a composite in which quantum dots are encapsulated in an amphiphilic polymer. However, in this composite, the polymer accounts for a large proportion of the weight and volume of the entire composite, so when quantum dots are filled and dispersed in a resin with a limited volume, such as for use in a color filter, the total amount of quantum dots is reduced, making it difficult to obtain sufficient light-emitting properties.

[0012] Another method is to improve dispersibility in polar solvents by using ligands with high affinity for polar solvents and adsorbing the ligands onto the quantum dot surface. However, these ligands on the quantum dot surface are released as soon as the solvent is removed. Therefore, when quantum dots are used as wavelength conversion materials for displays, removing the solvent to mix the quantum dots with a resin material can lead to problems such as aggregation of the quantum dots in the resin, a deterioration in the initial luminescence efficiency, and a deterioration over time in the luminescence efficiency of the composition consisting of quantum dots and a resin material.

[0013] The present invention has been made to solve the above problems, and aims to provide a quantum dot body that can maintain high luminous efficiency and has improved dispersibility in highly polar solvents. It is also an object of the present invention to provide a quantum dot composition in which the quantum dot body is dispersed in a resin material, and a wavelength converting material containing a cured product of the quantum dot composition, in which the initial value of luminous efficiency and deterioration over time are suppressed, as well as methods for producing the same.

[0014] The present invention has been made to achieve the above-mentioned object, and provides a quantum dot body containing quantum dots that emit fluorescence when exposed to excitation light, wherein the quantum dots include a semiconductor nanoparticle core and a semiconductor nanoparticle shell that covers the semiconductor nanoparticle core, and the surface of the quantum dots is modified with a compound having a methacryloyloxyethyl group and a hydrophilic group, as shown in the following formula (I):

[0015] (R １ represents a hydrophilic group.)

[0016] Such quantum dot bodies can maintain high luminous efficiency and have improved dispersibility in highly polar solvents.

[0017] In this case, the hydrophilic group may be selected from quaternary ammonium salts, carboxylates, succinates, isocyanates, maleates, hydrogen phosphates, 1,2,4-benzenetricarboxylates, salts of trimellitic anhydride, phthalates, acetoacetates, and thiocates.

[0018] This improves the affinity to polar solvents, and improves the dispersibility of the quantum dot bodies in polar solvents.

[0019] In this case, the compound may be bis[2-(methacryloyloxy)ethyl]phosphate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, mono-2-(methacryloyloxy)ethyl succinate, mono[2-(methacryloyloxy)ethyl]maleate, 2-(methacryloyloxy)ethyl isocyanate, (2-methacryloyloxyethyl)trimethylammonium bis(trifluoromethanesulfonyl)imide, 4-MET (4-methacryloxyethyltrimellitic acid), 4-META (4-methacryloxyethyl trimellitic anhydride), mono-2-(methacryloyloxy)ethyl phthalate, bis[2-(methacryloyloxy)ethyl](methyl)ammonio]propane-1-sulfonic acid, 2-(methacryloyloxy)ethyl acetoacetate, 2-[[2-(methacryloyloxy)ethyl]dimethylammonio]acetic acid, 4-[[2-(methacryloyloxy)ethyl]dimethylammonio]butane-1-sulfonic acid, 3-[[2-(methacryloyloxy)ethyl]dimethylammonio]propionate, 2-methacryloyloxyethyl thioctic acid, and [2-(methacryloyloxy)ethyl]trimethylammonium methylsulfate.

[0020] This further improves the affinity to polar solvents, and the dispersibility of the quantum dot bodies in polar solvents is further improved.

[0021] In this case, the compound may be contained in a range of 0.1 to 50% by mass relative to the quantum dots.

[0022] This effectively prevents the quantum dots from aggregating together, allowing the effects of modifying the quantum dot surfaces to be fully and stably exerted.

[0023] In this case, the compound may be contained in an amount ranging from 0.5 to 30% by mass relative to the quantum dots.

[0024] This makes it possible to more effectively suppress the aggregation of quantum dots, and to more sufficiently and stably exert the effect of modifying the quantum dot surface.

[0025] In this case, the quantum dot composition can be prepared by dispersing the quantum dot bodies in a resin material.

[0026] Such a quantum dot composition has improved dispersibility of the quantum dot bodies in the resin material.

[0027] In this case, the wavelength converting material may contain a cured product of the quantum dot composition.

[0028] In such a wavelength conversion material, the quantum dots are dispersed in the resin material at a high concentration without agglomerates while maintaining high luminous efficiency, and reliability is improved.

[0029] In this case, the method for producing the quantum dot body can include a quantum dot production step of producing quantum dots each including a semiconductor nanoparticle core and a semiconductor nanoparticle shell covering the semiconductor nanoparticle core, and a quantum dot modification step of modifying the surface of the quantum dot with a compound having a methacryloyloxyethyl group and a hydrophilic group, as represented by formula (I).

[0030] This makes it possible to produce quantum dot bodies that can maintain high luminous efficiency and have improved dispersibility in highly polar solvents.

[0031] In this case, the quantum dot composition can be produced by dispersing the quantum dot bodies produced by the quantum dot body production method in a resin material.

[0032] This makes it possible to produce a quantum dot composition in which the dispersibility of the quantum dot bodies in the resin material is improved.

[0033] In this case, the method for producing a wavelength converting material can be a method for producing a wavelength converting material by curing the quantum dot composition produced by the method for producing a quantum dot composition.

[0034] As a result, even after curing the quantum dot composition, it is possible to disperse the quantum dots in the resin material without forming aggregates while maintaining high luminous efficiency, and it is possible to produce a wavelength converting material with improved reliability.

[0035] As described above, the quantum dot body of the present invention can maintain high luminous efficiency and improve dispersibility in highly polar solvents. Furthermore, by using the quantum dot body of the present invention to form a quantum dot composition and a wavelength converting material, the initial value of the luminous efficiency and deterioration over time can be suppressed. Furthermore, it is possible to provide methods for producing a quantum dot body, a quantum dot composition, and a wavelength converting material having the above effects.

[0036] 1 is a schematic cross-sectional view showing an example of a quantum dot body of the present invention.

[0037] The present invention will be described in detail below, but the present invention is not limited thereto.

[0038] As described above, there has been a demand for quantum dots that can maintain high luminous efficiency and have improved dispersibility in highly polar solvents.

[0039] As a result of extensive research into the above-mentioned problems, the present inventors have found that a quantum dot body containing quantum dots that emit fluorescence in response to excitation light, wherein the quantum dots include a semiconductor nanoparticle core and a semiconductor nanoparticle shell that covers the semiconductor nanoparticle core, and the surface of the quantum dots is modified with a compound having a methacryloyloxyethyl group and a hydrophilic group, as shown in the following formula (I), can maintain high luminous efficiency and has improved dispersibility in highly polar solvents, thereby completing the present invention.

[0040] (R １ represents a hydrophilic group.)

[0041] Furthermore, it was found that a quantum dot composition in which the quantum dot bodies are dispersed in a resin material, and a wavelength converting material obtained by curing the quantum dot composition, have a high initial value of luminous efficiency and are inhibited from deteriorating over time. As a result, it was found that a wavelength converting material containing a cured product of the quantum dot composition in which the quantum dot bodies are dispersed in a resin material can suppress the rate of decrease in internal quantum yield during 100 hours of treatment to within 10% in a reliability test at 85°C and 85% RH without a barrier film, thereby enabling improvement in stability.

[0042] That is, the present invention relates to a quantum dot body 1 including quantum dots 4 that emit fluorescence in response to excitation light, as shown in FIG. 1 , wherein the quantum dots 4 include a semiconductor nanoparticle core 2 and a semiconductor nanoparticle shell 3 that covers the semiconductor nanoparticle core 2, and the surface of the quantum dots 4 is modified with a compound 5 having a methacryloyloxyethyl group and a hydrophilic group, as shown in formula (I) above; a quantum dot composition in which the quantum dot bodies 1 are dispersed in a resin material; and a wavelength conversion material including a cured product of the quantum dot composition, as well as methods for producing the same.

[0043] (Quantum Dots) The structure of the quantum dots according to the present invention is not particularly limited as long as it comprises a semiconductor nanoparticle core and a semiconductor nanoparticle shell. Such quantum dots have excellent fluorescence emission properties and stability. For example, in semiconductor nanoparticles with a core / shell structure, in which a nano-sized semiconductor particle serves as the core and a semiconductor particle with a larger band gap and lower lattice mismatch than the core serves as the shell, excitons generated in the shell are confined inside the core particle, thereby improving fluorescence emission efficiency, and further improving stability because the core surface is covered by the shell.

[0044] The quantum dots may also include a semiconductor nanoparticle core and a plurality of semiconductor nanoparticle shells covering the semiconductor nanoparticle core. Such quantum dots further suppress the deterioration of fluorescence emission efficiency.

[0045] The material for the semiconductor nanoparticle core of the core / shell semiconductor nanoparticles is preferably one that does not contain the elements Cd or Pb from the viewpoint of toxicity, and for example, a material selected from the group consisting of II-VI compounds, III-V compounds, I-III-VI compounds, II-IV-V compounds, and alloys or mixed crystals thereof can be used.

[0046] Specifically, the materials for the semiconductor nanoparticle core include ZnS, ZnSe, ZnTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, and AgGaS. ２ , AgInS ２ , AgGaSe ２ , AgInSe ２ , CuGaS ２ , CuGaSe ２ , CuInS ２ , CuInSe ２ , ZnSiP ２ , and ZnGeP ２ Among these materials, ZnSe, ZnTe, and InP are particularly preferable in terms of fluorescent emission characteristics and stability.

[0047] Furthermore, the surface of the core particle of the core / shell semiconductor nanoparticles is preferably passivated with an inorganic compound, which inactivates defects on the surface of the core particle, improves the fluorescence emission efficiency, and further suppresses deterioration of the fluorescence emission efficiency over time.

[0048] The inorganic compound for passivation is not particularly limited, but examples thereof include metal halides. From the viewpoint of improving the fluorescent light emission efficiency, GaCl ３ , GaI ３ , GaBr ３ , ZnCl ２ , ZnBr ２ , ZnI ２ , InCl ３ , InBr ３ , InI ３ , AgCl, AgBr, AgI, KCl, KBr, KI, NaCl, NaBr, NaI, MgCl ２, MgBr ２ , MgI ２ , CaCl ２ , CaBr ２ , CaI ２ , MnCl ２ , MnBr ２ , MnI ２ , FeCl ２ , FeBr ２ , FeI ２ , CuCl ２ , CuBr ２ , CuI ２ , ZrCl ４ , ZrBr ４ , ZrI ４ , GeCl ４ , GeBr ４ , GeI ４ Particularly preferred is at least one compound selected from

[0049] The material for the semiconductor nanoparticle shell is preferably one that does not contain elements such as Cd or Pb from the viewpoint of toxicity, but is also preferably one that has a large band gap and low lattice mismatch with respect to the core material, and can be selected from the group consisting of alloys and mixed crystals of II-VI and III-V group compounds.

[0050] Specific shell materials include those selected from the group consisting of ZnS, ZnSe, ZnTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, and InSb, either singly or in combination, or as mixed crystals. Of these materials, ZnSe and ZnS are particularly preferred in terms of improved fluorescence efficiency and stability.

[0051] [Quantum dot body] In the present invention, the modifying agent necessary for dispersing quantum dots in a polar solvent is a compound having a methacryloyloxyethyl group and a hydrophilic group, and the quantum dot body in the present invention includes the quantum dot and a compound having a methacryloyloxyethyl group and a hydrophilic group that modifies the surface of the quantum dot.

[0052] In the present invention, "modification" refers to a state in which a compound having a methacryloyloxyethyl group and a hydrophilic group is "adhered" to at least the surface of the quantum dot. Adhesion to the surface by "modification" includes partial and full-surface adhesion, and refers to a state in which the compound is attached to at least a part of the surface.

[0053] The term "adhesion" in the above context may refer to physical adsorption or chemical bonding, and may broadly refer to, for example, covalent bonding, ionic bonding, or hydrogen bonding, or may be a combination of these. As an example, a quantum dot body containing a compound having a methacryloyloxyethyl group and a hydrophilic group that modifies quantum dots may be in a state in which at least some of the organic or inorganic ligands attached during quantum dot synthesis coexist, as long as it is dispersible in a polar solvent.

[0054] The structure of the compound having a methacryloyloxyethyl group and a hydrophilic group in the present invention is represented by the following formula (I).

[0055] (R １ represents a hydrophilic group.)

[0056] R in the formula (I) １ is not particularly limited as long as it is a hydrophilic group, and examples thereof include quaternary ammonium salts, carboxylates, succinates, isocyanates, maleates, hydrogen phosphates, 1,2,4-benzenetricarboxylates, salts of trimellitic anhydride, phthalates, acetoacetates, and thiocates.

[0057] The type of compound having a methacryloyloxyethyl group and a hydrophilic group represented by the formula (I) is not particularly limited, and examples thereof include bis[2-(methacryloyloxy)ethyl]phosphate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, mono-2-(methacryloyloxy)ethyl succinate, mono[2-(methacryloyloxy)ethyl]maleate, 2-(methacryloyloxy)ethyl isocyanate, (2-methacryloyloxyethyl)trimethylammonium bis(trifluoromethanesulfonyl)imide, 4-MET (4-methacryloxyethyltrimellitic acid), 4-META (4-methacryloxyethyl trimellitic acid), anhydride), mono-2-(methacryloyloxy)ethyl phthalate, bis[2-(methacryloyloxy)ethyl](methyl)ammonio]propane-1-sulfonic acid, 2-(methacryloyloxy)ethyl acetoacetate, 2-[[2-(methacryloyloxy)ethyl]dimethylammonio]acetic acid, 4-[[2-(methacryloyloxy)ethyl]dimethylammonio]butane-1-sulfonic acid, 3-[[2-(methacryloyloxy)ethyl]dimethylammonio]propionate, 2-methacryloyloxyethyl thioctic acid, and [2-(methacryloyloxy)ethyl]trimethylammonium methyl sulfate.

[0058] These compounds have the structure shown in formula (I) above and have hydrophilic groups. By modifying the quantum dot surface with these compounds, the affinity to polar solvents is improved, and the dispersibility of the quantum dot bodies in polar solvents is improved.

[0059] The amount of the compound added as the surface modifier is not particularly limited as long as it is within the range in which the compound having a methacryloyloxyethyl group and a hydrophilic group modifies the quantum dot surface; however, for example, an amount of 50% by mass (wt%) or less relative to the solid mass of the quantum dots is preferable because aggregation of the quantum dots can be effectively suppressed, and an amount of 0.1% by mass (wt%) or more allows the effect of modification on the quantum dot surface to be sufficiently and stably exerted. Therefore, the amount of the surface modifier added is preferably in the range of 0.1 to 50% by mass (wt%), and more preferably in the range of 0.5 to 30% by mass (wt%), relative to the solid mass of the quantum dots.

[0060] [Quantum Dot Composition] The quantum dot bodies can be used as a quantum dot composition in which they are dispersed in a resin material.

[0061] In the quantum dot composition of the present invention, the methacryloyl group moiety of the quantum dot body undergoes a crosslinking reaction with a polymer that is a base polymer of a resin material. The resin material may contain a polymerization initiator together with the polymer that is the base polymer, and may also contain other ingredients such as an organic solvent, a polymerizable crosslinking agent, a photoacid generator, an antioxidant, and a light scattering agent.

[0062] The polymer is selected from polymers derived from acrylic acid, methacrylic acid, acrylic esters, and methacrylic esters, copolymers combining multiple polymers, polymers having a skeletal structure with glycidyl (meth)acrylate repeating units, siloxane skeleton, urethane skeleton, silphenylene skeleton, norbornene skeleton, fluorene skeleton, and isocyanurate skeleton, depending on the application. Examples include acrylic resins, alkyd resins, melamine resins, epoxy resins, silicone resins, polyvinyl alcohol, polyvinylpyrrolidone, polyamides, polyamide-imides, polyimides, and other polyimide precursors and their esterification products, and reaction products of tetracarboxylic dianhydrides and diamines. Furthermore, these polymers incorporate polymerizable substituents, which can be cured by combining them with a polymerization initiator. Examples of radically polymerizable substituents include vinyl groups, acrylic groups, methacrylic groups, and thiol groups, all of which can be used effectively. Examples of cationically polymerizable substituents include hydroxyl groups, phenolic hydroxyl groups, epoxy groups, glycidyl groups, oxetanyl groups, and isocyanate groups, all of which can be used effectively. In addition, a carboxy group may be introduced to impart alkaline developability.

[0063] Furthermore, as described above, the quantum dot composition of the present invention preferably contains a polymerization initiator. The polymerization initiator may be a thermal or photopolymerization initiator, either of which may be suitably used depending on the base polymer. Examples of photoradical polymerization initiators include those in the Irgacure (registered trademark) series 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 the Darocure (registered trademark) series include TPO and Darocure 1173. Other known thermal radical polymerization initiators and photocationic polymerization initiators may also be included. The content of the polymerization initiator is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass, per 100 parts by mass of the polymer to be added.

[0064] The quantum dot composition of the present invention may contain an organic solvent to improve its applicability. From the viewpoint of compatibility with quantum dots, organic solvents are preferred, such as ketones, alkylene glycol ethers, alcohols, and aromatic compounds. Ketones include acetone, methyl ethyl ketone, and cyclohexanone; alkylene glycol ethers include methyl cellosolve (ethylene glycol monomethyl ether), butyl cellosolve (ethylene glycol monobutyl ether), methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, 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 monomethyl ether, and diethylene glycol methyl ether. Suitable solvents include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, 3-methyl-3-methoxybutanol, and aromatic solvents such as benzene, toluene, and xylene. The quantum dot composition of the present invention may also contain a polymerizable crosslinker, a photoacid generator, an antioxidant, a light scattering agent, and the like, without any particular limitation, as long as the polymerizable coating properties are not affected.

[0065] In such a quantum dot composition, the methacryloyl group moiety of the compound having a methacryloyloxyethyl group and a hydrophilic group modifying the surface of the quantum dot undergoes a crosslinking reaction with a polymer that is the base polymer of the resin material, thereby suppressing the precipitation of aggregates of quantum dots in the resin, and thus improving dispersibility in the resin material.

[0066] [Wavelength converting material] The present invention also provides a wavelength converting material containing a cured product of the quantum dot composition. The wavelength converting material may be used as is or may be processed. One form of the wavelength converting material is a wavelength conversion film in which the quantum dot composition is dispersed in a resin and processed into a sheet and then cured.

[0067] In such a wavelength conversion material, the quantum dots are dispersed in the resin material at a high concentration without agglomerates while maintaining high luminous efficiency, and reliability is improved.

[0068] [Manufacturing Method of Quantum Dot Body] Next, a manufacturing method of a quantum dot body of the present invention will be described. The manufacturing method of a quantum dot body of the present invention is a manufacturing method of the quantum dot body, comprising a quantum dot manufacturing step of manufacturing quantum dots each including a semiconductor nanoparticle core and a semiconductor nanoparticle shell covering the semiconductor nanoparticle core, and a quantum dot modification step of modifying the surface of the quantum dot with a compound having a methacryloyloxyethyl group and a hydrophilic group represented by the formula (I). This makes it possible to manufacture quantum dot bodies that can maintain high luminous efficiency and have improved dispersibility in highly polar solvents.

[0069] (Quantum dot manufacturing process) There are various methods for manufacturing the core and shell of semiconductor nanoparticles, such as a liquid phase method or a gas phase method, but the present invention is not particularly limited to these. From the viewpoint of obtaining high fluorescence emission efficiency, it is preferable to use semiconductor nanoparticles obtained by a hot soap method or a hot injection method, in which precursor species are reacted at high temperature in a high-boiling-point nonpolar solvent.

[0070] (Quantum dot modification process) The method for modifying the surface of quantum dots with a compound having a methacryloyloxyethyl group and a hydrophilic group is not particularly limited as long as the compound can be modified on the surface of the quantum dots. One example is a method in which a two-phase system consisting of a polar solvent and a nonpolar solvent is used, and the nonpolar solvent in which quantum dots are dispersed and the polar solvent in which a compound having a methacryloyloxyethyl group and a hydrophilic group is dispersed are mixed by strong stirring or the like, and the quantum dot bodies, which are quantum dots modified with the compound having a methacryloyloxyethyl group and a hydrophilic group, are extracted into the polar solvent.

[0071] The type of non-polar solvent is not particularly limited as long as the quantum dots are dispersed without settling. The polar solvent is also not particularly limited as long as the compound having a methacryloyloxyethyl group and a hydrophilic group is dissolved without precipitating. Furthermore, the type of solvent is not limited as long as the polar solvent and the non-polar solvent are mixed and the resulting quantum dots are dispersed in the polar solvent even if they are not separated into two phases.

[0072] The heating temperature when modifying the quantum dot surface with a compound having a methacryloyloxyethyl group and a hydrophilic group is not particularly limited, but for efficient modification, the heating temperature is preferably in the range of 30 to 100° C. Within this range, the quantum dot surface can be modified more efficiently.

[0073] [Method for producing quantum dot composition] Next, a method for producing a quantum dot composition by dispersing the quantum dot bodies produced by the above-mentioned method for producing quantum dot bodies in a resin material will be described. The resin material can be a polymer that is a base polymer and a polymerization initiator, and may also contain organic solvents, polymerizable crosslinking agents, photoacid generators, antioxidants, light scattering agents, etc.

[0074] Suitable examples of the polymer include polymers derived from acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters, copolymers combining multiple polymers, and polymers having a skeletal structure with glycidyl (meth)acrylate as a repeating unit, a siloxane skeleton, a urethane skeleton, a silphenylene skeleton, a norbornene skeleton, a fluorene skeleton, and an isocyanurate skeleton. The polymer to be used may be selected appropriately depending on the application.

[0075] Furthermore, these polymers have polymerizable substituents introduced therein, and can be cured by using them in combination with a polymerization initiator. The polymerization initiator can be a thermal or photopolymerization initiator, and either can be suitably used depending on the base polymer. In addition, known thermal radical polymerization initiators and photocationic polymerization initiators may also be used.

[0076] The content of the polymerization initiator is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass, per 100 parts by mass of the polymer to be added. An organic solvent may be used to improve the coatability of the quantum dot composition. Furthermore, other agents such as a polymerizable crosslinker, a photoacid generator, an antioxidant, and a light scattering agent may also be used, with no particular limitations provided that they do not affect the coatability of the polymerizable material.

[0077] According to such a method for producing a quantum dot composition, it is possible to produce a quantum dot composition with improved dispersibility of the quantum dot bodies in a resin material.

[0078] [Method for producing wavelength converting material] The present invention also provides a method for producing a wavelength converting material by curing the quantum dot composition produced by the above-mentioned method for producing a quantum dot composition.

[0079] The method for producing the wavelength converting material is not particularly limited. For example, a resin composition in which a quantum dot composition is dispersed in a resin can be applied to a transparent film such as PET or polyimide, cured, and laminated to obtain the wavelength converting material.

[0080] The resin layer can be formed by coating onto the transparent film using a spraying method such as spraying or inkjet, or by spin coating, bar coating, or doctor blade. The thickness of the resin layer and the transparent film is not particularly limited and can be selected appropriately depending on the application.

[0081] According to such a method for producing a wavelength converting material, even after curing the quantum dot composition, it is possible to disperse the quantum dots in the resin material without forming aggregates while maintaining high luminous efficiency, and it is possible to produce a wavelength converting material with improved reliability.

[0082] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0083] (Measurement of Emission Wavelength, Emission Half Width, and Emission Efficiency) In the examples and comparative examples, the fluorescence emission properties of the quantum dots were evaluated by measuring the emission wavelength, fluorescence emission half width, and fluorescence emission efficiency (internal quantum yield) of the quantum dots at an excitation wavelength of 450 nm using a quantum efficiency measurement system (QE-2100) manufactured by Otsuka Electronics Co., Ltd.

[0084] (Reliability Test) The obtained wavelength converting material was treated under conditions of 85° C. and 85% RH (relative humidity) for 100 hours, and the fluorescence emission efficiency (internal quantum yield) of the wavelength converting material before and after the treatment was compared to evaluate its reliability.

[0085] Example 1 (Quantum Dot Production Process) 0.070 g (0.24 mmol) of indium acetate, 0.256 g (0.72 mmol) of palmitic acid, and 4.0 mL of 1-octadecene were placed in a flask, and the mixture was heated and stirred at 100° C. under reduced pressure to dissolve and degas for 1 hour.

[0086] After cooling the flask to room temperature and purging with nitrogen, 0.50 mL (0.17 mmol) of a 10 vol% (tris)trimethylsilylphosphine / octadecene solution was added to the flask, and the flask was heated to 300°C and stirred for 20 minutes to synthesize InP semiconductor core particles.

[0087] Next, the flask was cooled to 200° C., and then 0.10 mL (0.02 mmol) of a gallium (III) chloride / octadecene solution was added, followed by heating for 20 minutes.

[0088] The flask was then heated to 240°C, and 4.0 mL (1.2 mmol) of a 0.30 M zinc stearate / octadecene solution was added, followed by stirring for 30 minutes. 0.60 mL (0.90 mmol) of a 1.5 M selenium / trioctylphosphine solution was then added to the flask, followed by stirring for 30 minutes.

[0089] Next, after the flask was cooled to room temperature, 0.22 g (1.1 mmol) of zinc acetate was added, and the mixture was heated and stirred under reduced pressure at 100°C for 1 hour while dissolving. After purging the flask with nitrogen, the mixture was heated to 230°C, and 0.48 mL (2.0 mmol) of 1-dodecanethiol was added, followed by stirring for 30 minutes.

[0090] The resulting solution was cooled to room temperature, ethanol was added, and the mixture was centrifuged to precipitate quantum dots consisting of an InP core, a ZnSe shell, and a ZnS shell, and the supernatant was removed.

[0091] Hexane was added to the resulting quantum dot precipitate. Separately, a polar solvent, propylene glycol monomethyl ether acetate (PGMEA), was added. As a result, the resulting precipitate dispersed in hexane, but did not disperse in PGMEA, resulting in the quantum dots settling. This confirmed that the quantum dots do not disperse in polar solvents and have a high affinity for nonpolar solvents. Fluorescence emission characteristics were evaluated for the InP / ZnSe / ZnS hexane dispersion. The resulting quantum dots exhibited the following fluorescence emission characteristics: an emission wavelength of 536 nm, a half-width of 41 nm, and a luminous efficiency of 81%.

[0092] (Quantum dot modification step) In a nitrogen atmosphere, 10 mg of bis[2-(methacryloyloxy)ethyl]phosphate was weighed into a 20 ml vial, and 10 ml of dimethylformamide (DMF) was added and stirred to prepare a bis[2-(methacryloyloxy)ethyl]phosphate solution.

[0093] Further, under a nitrogen atmosphere, 10 g of the obtained 1.0 wt % InP / ZnSe / ZnS hexane dispersion and 10 ml of bis[2-(methacryloyloxy)ethyl]phosphate solution were added to a 50 ml vial. The mass ratio of bis[2-(methacryloyloxy)ethyl]phosphate to InP / ZnSe / ZnS was 10%.

[0094] At this time, the hexane and DMF separated into two phases, with the quantum dots dispersed in the non-polar solvent, hexane. The solution was then heated to 50°C in a nitrogen atmosphere, stirred for 30 minutes, and then cooled to room temperature. The quantum dots then migrated from the non-polar solvent, hexane, to the DMF, confirming that the quantum dots, whose surfaces were modified with bis[2-(methacryloyloxy)ethyl]phosphate, were dispersed in the polar solvent.

[0095] Hexane was further added to the obtained quantum dots, and the mixture was centrifuged to precipitate the quantum dots. The supernatant was removed, and propylene glycol monomethyl ether acetate (PGMEA) was added to the resulting quantum dot precipitate. It was confirmed that the quantum dots were dispersed in the polar PGMEA solvent. The fluorescence characteristics of the obtained quantum dots were an emission wavelength of 537 nm, an emission half-width of 42 nm, and a luminous efficiency of 60%.

[0096] (Production of quantum dot composition) The obtained PGMEA dispersion of quantum dot bodies and methacrylic-modified silicone X-32-3817-3 (manufactured by Shin-Etsu Chemical Co., Ltd.) were weighed and mixed so that the quantum dot bodies were contained in a nonvolatile content ratio of 20 wt %. After mixing, the solvent was removed to obtain a quantum dot composition.

[0097] (Production of wavelength converting material) A wavelength converting material was produced using the obtained quantum dot composition. The quantum dot composition was vacuum degassed and applied to a polyethylene terephthalate (PET) film with a thickness of 50 μm, and a quantum dot-containing resin layer with a thickness of 100 μm was formed using a bar coater. A PET film was then attached to the resin layer for lamination. This film was then exposed to a UV LED irradiation device with a wavelength of 365 nm and an output of 4000 mW / cm. ２ The quantum dot-containing resin layer was cured by irradiating it with light of 1000 W for 20 seconds to prepare a wavelength converting material. The fluorescence emission properties of the obtained wavelength converting material were an emission wavelength of 537 nm, an emission half width of 42 nm, and a luminous efficiency of 53%.

[0098] Example 2 (Quantum Dot Manufacturing Process) The quantum dot manufacturing process was carried out in the same manner as in Example 1, and a hexane dispersion of InP / ZnSe / ZnS was manufactured.

[0099] (Quantum dot modification step) In a nitrogen atmosphere, an aqueous solution of 75 wt % [2-(methacryloyloxy)ethyl]trimethylammonium chloride was used, and 10 mg of [2-(methacryloyloxy)ethyl]trimethylammonium chloride was weighed into a 20 ml vial, and 10 ml of dimethylformamide (DMF) was added and stirred to prepare a DMF solution of [2-(methacryloyloxy)ethyl]trimethylammonium chloride.

[0100] Further, under a nitrogen atmosphere, 10 g of the obtained 1.0 wt % InP / ZnSe / ZnS hexane dispersion and 10 ml of a DMF solution of [2-(methacryloyloxy)ethyl]trimethylammonium chloride were added to a 50 ml vial. The mass ratio of [2-(methacryloyloxy)ethyl]trimethylammonium chloride to InP / ZnSe / ZnS was 10%.

[0101] At this time, the hexane and DMF separated into two phases, with the quantum dots dispersed in the non-polar solvent, hexane. The solution was then heated to 50°C in a nitrogen atmosphere, stirred for 30 minutes, and then cooled to room temperature. The quantum dots then migrated from the non-polar solvent, hexane, to the DMF, confirming that the quantum dots, in which the surfaces of the InP / ZnSe / ZnS quantum dots were modified with [2-(methacryloyloxy)ethyl]trimethylammonium chloride, were dispersed in the polar solvent.

[0102] Hexane was further added to the obtained quantum dots, and the mixture was centrifuged to precipitate the quantum dots. The supernatant was removed, and propylene glycol monomethyl ether acetate (PGMEA) was added to the resulting quantum dot precipitate. It was confirmed that the quantum dots were dispersed in the polar PGMEA solvent. The fluorescence emission characteristics of the obtained quantum dots were an emission wavelength of 538 nm, an emission half-width of 43 nm, and a luminous efficiency of 55%.

[0103] (Production of quantum dot composition) The obtained PGMEA dispersion of quantum dot bodies and methacrylic-modified silicone X-32-3817-3 (manufactured by Shin-Etsu Chemical Co., Ltd.) were weighed and mixed so that the quantum dot bodies were contained in a nonvolatile content ratio of 20 wt %. After mixing, the solvent was removed to obtain a quantum dot composition.

[0104] (Production of wavelength converting material) A wavelength converting material was produced using the obtained quantum dot composition. The quantum dot composition was vacuum degassed and applied to a polyethylene terephthalate (PET) film with a thickness of 50 μm, and a quantum dot-containing resin layer with a thickness of 100 μm was formed using a bar coater. A PET film was then attached to the resin layer for lamination. This film was then exposed to a UV LED irradiation device with a wavelength of 365 nm and an output of 4000 mW / cm. ２ The quantum dot-containing resin layer was cured by irradiating it with light of 1000 W for 20 seconds to prepare a wavelength converting material. The fluorescence emission properties of the obtained wavelength converting material were an emission wavelength of 538 nm, an emission half width of 43 nm, and a luminous efficiency of 49%.

[0105] Example 3 (Quantum Dot Manufacturing Process) The quantum dot manufacturing process was carried out in the same manner as in Example 1, and a hexane dispersion of InP / ZnSe / ZnS was manufactured.

[0106] (Quantum dot modification step) In a nitrogen atmosphere, 10 mg of mono[2-(methacryloyloxy)ethyl]maleate was weighed into a 20 ml vial, and 10 ml of dimethylformamide (DMF) was added and stirred to prepare a mono[2-(methacryloyloxy)ethyl]maleate acid solution.

[0107] Further, under a nitrogen atmosphere, 10 g of the obtained 1.0 wt % InP / ZnSe / ZnS hexane dispersion and 10 ml of the mono[2-(methacryloyloxy)ethyl]maleate acid solution were added to a 50 ml vial. The mass ratio of mono[2-(methacryloyloxy)ethyl]maleate to InP / ZnSe / ZnS was 10%.

[0108] At this time, hexane and dimethylformamide separated into two phases, and the quantum dots were dispersed in the non-polar solvent, hexane. Next, this solution was heated to 50°C in a nitrogen atmosphere, stirred for 30 minutes, and then cooled to room temperature. At this time, the quantum dots had transferred to the polar solvent, dimethylformamide, and it was confirmed that the quantum dots were dispersed. Thus, an InP / ZnSe / ZnS quantum dot structure modified with mono[2-(methacryloyloxy)ethyl]maleate was obtained.

[0109] Hexane was further added to the obtained quantum dots, and the mixture was centrifuged to precipitate the quantum dots. The supernatant was removed, and propylene glycol monomethyl ether acetate (PGMEA) was added to the resulting quantum dot precipitate. It was confirmed that the quantum dots were dispersed in the polar PGMEA solvent. The fluorescence characteristics of the obtained quantum dots were an emission wavelength of 538 nm, an emission half-width of 42 nm, and a luminous efficiency of 58%.

[0110] (Production of quantum dot composition) The obtained PGMEA dispersion of quantum dot bodies and methacrylic-modified silicone X-32-3817-3 (manufactured by Shin-Etsu Chemical Co., Ltd.) were weighed and mixed so that the quantum dot bodies were contained in a nonvolatile content ratio of 20 wt %. After mixing, the solvent was removed to obtain a quantum dot composition.

[0111] (Production of wavelength converting material) A wavelength converting material was produced using the obtained quantum dot composition. The quantum dot composition was vacuum degassed and applied to a polyethylene terephthalate (PET) film with a thickness of 50 μm, and a quantum dot-containing resin layer with a thickness of 100 μm was formed using a bar coater. A PET film was then attached to the resin layer for lamination. This film was then exposed to a UV LED irradiation device with a wavelength of 365 nm and an output of 4000 mW / cm. ２ The quantum dot-containing resin layer was cured by irradiating it with light of 1000 W for 20 seconds to prepare a wavelength converting material. The fluorescence emission properties of the obtained wavelength converting material were an emission wavelength of 537 nm, an emission half width of 42 nm, and a luminous efficiency of 51%.

[0112] Comparative Example: The quantum dot production process was carried out in the same manner as in Example 1, and the resin composition was mixed without surface modification using a compound having a methacryloyloxyethyl group and a hydrophilic group. After the quantum dot production process, methacrylic-modified silicone oil X-32-3817-3 (manufactured by Shin-Etsu Chemical Co., Ltd.) was weighed and mixed into the hexane dispersion so that the quantum dots contained 20 wt% of the nonvolatile content. After mixing, the solvent was removed to obtain a quantum dot composition.

[0113] Using the obtained quantum dot composition, a wavelength converting material was produced by the same production method as in Example 1. The fluorescent emission characteristics of the obtained wavelength converting material were a wavelength of 544 nm, an emission half width of 47 nm, and a luminous efficiency of 28%.

[0114] The results of Examples 1 to 3 and Comparative Example are shown in Table 1. Table 1 shows the dispersion solvent of the quantum dots or quantum dot bodies, the luminous efficiency (internal quantum yield), dispersibility in the PGMEA solvent, the initial value of the luminous efficiency (internal quantum yield) of the wavelength converting material, the luminous efficiency (internal quantum yield) after reliability evaluation, and the presence or absence of aggregates by microscopic observation.

[0115]

[0116] The results in Table 1 confirm that the quantum dot bodies of Examples 1 to 3 precipitated in hexane solvent but dispersed in PGMEA solvent. These results confirm that quantum dot bodies modified with a compound having a methacryloyloxyethyl group and a hydrophilic group have improved affinity for polar solvents such as PGMEA, improving dispersibility. On the other hand, it was confirmed that the quantum dots produced by the method of the comparative example dispersed in hexane solvent, but precipitated and did not disperse in PGMEA solvent, which is a polar solvent.

[0117] Furthermore, when the wavelength converting materials were observed using a microscope, it was found that the wavelength converting materials of Examples 1 to 3 had small aggregates and a small number of them, which is thought to have suppressed the decrease in quantum yield. This is thought to be because in the Examples, the methacryloyl groups of the quantum dot bodies crosslinked with the base polymer of the resin material, effectively suppressing the aggregation of the quantum dots, and the dispersibility of the quantum dot bodies was confirmed to be improved. On the other hand, in the wavelength converting material of the Comparative Example, many aggregates of about 1 to 100 μm were observed, which is thought to have resulted in the decrease in quantum yield.

[0118] Furthermore, when the results of the reliability test of the wavelength converting material (treated at 85°C and 85% RH for 100 hours) were compared, it was found that the decrease in quantum yield was suppressed in all of the Examples compared to the Comparative Examples, and stability was improved. This is thought to be because the compound having a methacryloyloxyethyl group and a hydrophilic group stably modified the surface of the quantum dots even in a resin such as the wavelength converting material.

[0119] As described above, according to the examples of the present invention, it was confirmed that the quantum dot body of the present invention has improved dispersibility in polar solvents. Furthermore, it was confirmed that the quantum dot composition using the quantum dot body of the present invention and the wavelength converting material using the same have high reliability, with the initial value of the fluorescence emission efficiency and deterioration over time under high-temperature and high-humidity conditions being suppressed.

[0120] This specification includes the following aspects: [1]: A quantum dot body including quantum dots that emit fluorescence when exposed to excitation light, the quantum dots including a semiconductor nanoparticle core and a semiconductor nanoparticle shell that covers the semiconductor nanoparticle core, and the surface of the quantum dots is modified with a compound having a methacryloyloxyethyl group and a hydrophilic group, as shown in the following formula (I): (R １represents a hydrophilic group.) [2]: The quantum dot body according to [1] above, wherein the hydrophilic group is selected from the group consisting of quaternary ammonium salts, carboxylates, succinates, isocyanates, maleates, hydrogen phosphates, 1,2,4-benzenetricarboxylates, salts of trimellitic anhydride, phthalates, acetoacetates, and thioctates. [3]: The compound is selected from the group consisting of bis[2-(methacryloyloxy)ethyl]phosphate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, mono-2-(methacryloyloxy)ethyl succinic acid, mono[2-(methacryloyloxy)ethyl]maleate, 2-(methacryloyloxy)ethyl isocyanate, (2-methacryloyloxyethyl)trimethylammonium bis(trifluoromethanesulfonyl)imide, 4-MET (4-methacryloxyethyltrimellitic acid), 4-META (4-methacryloxyethyl trimellitic anhydride), mono-2-(methacryloyloxy)ethyl phthalate, bis[2-(methacryloyloxy)ethyl](methyl)ammonio]propane-1-sulfonic acid, 2-(methacryloyloxy)ethyl acetoacetate, 2-[[2-(methacryloyloxy)ethyl]dimethylammonio]acetic acid, 4-[[2-(methacryloyloxy)ethyl]dimethylammonio]butane-1-sulfonic acid, 3-[[2-(methacryloyloxy)ethyl]dimethylammonio]propionate, 2-methacryloyloxyethyl thioctic acid, and [2-(methacryloyloxy)ethyl]trimethylammonium methyl sulfate. [4]: ​​The quantum dot body of [1], [2], or [3] above, wherein the compound is contained in a range of 0.1 to 50% by mass relative to the quantum dots. [5]: The quantum dot body according to [1], [2], [3] or [4], wherein the compound is contained in an amount of 0.5 to 30% by mass relative to the quantum dots.[6]: A quantum dot composition comprising the quantum dot body of [1], [2], [3], [4], or [5] dispersed in a resin material. [7]: A wavelength converting material comprising a cured product of the quantum dot composition of [6]. [8]: A method for producing a quantum dot body of [1], [2], [3], [4], or [5], comprising: a quantum dot production step of producing quantum dots comprising a semiconductor nanoparticle core and a semiconductor nanoparticle shell covering the semiconductor nanoparticle core; and a quantum dot modification step of modifying the surfaces of the quantum dots with a compound having a methacryloyloxyethyl group and a hydrophilic group, as represented by formula (I). [9]: A method for producing a quantum dot composition, comprising dispersing quantum dot bodies produced by the quantum dot body production method of [8] in a resin material to produce a quantum dot composition.

[10] : A method for producing a wavelength converting material, comprising curing the quantum dot composition produced by the quantum dot composition production method of [9].

[0121] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. A quantum dot body containing quantum dots that emit fluorescence when excited by excitation light, wherein the quantum dots comprise a semiconductor nanoparticle core and a semiconductor nanoparticle shell that covers the semiconductor nanoparticle core, and the surface of the quantum dots is modified with a compound having a methacryloyloxyethyl group and a hydrophilic group, as shown in the following formula (I): (R １ represents a hydrophilic group.) 2. The quantum dot body according to claim 1, wherein the hydrophilic group is selected from the group consisting of quaternary ammonium salts, carboxylates, succinates, isocyanates, maleates, hydrogen phosphates, 1,2,4-benzenetricarboxylates, salts of trimellitic anhydride, phthalates, acetoacetates, and thioctates.

3. The compound is bis[2-(methacryloyloxy)ethyl]phosphate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, mono-2-(methacryloyloxy)ethyl succinate, mono[2-(methacryloyloxy)ethyl]maleate, 2-(methacryloyloxy)ethyl isocyanate, (2-methacryloyloxyethyl)trimethylammonium bis(trifluoromethanesulfonyl)imide, 4-MET (4-methacryloxyethyl trimellitic acid), 4-META (4-methacryloxyethyl trimellitic anhydride), mono-2-(methacryloyloxy)ethyl phthalate, bis[2-(methacryloyloxy)ethyl](methyl)ammonio]propane-1-sulfonic acid, 2-(methacryloyloxy)ethyl acetoacetate, 2-[[2-(methacryloyloxy)ethyl]dimethylammonio]acetic acid, 4-[[2-(methacryloyloxy)ethyl]dimethylammonio]butane-1-sulfonic acid, 3-[[2-(methacryloyloxy)ethyl]dimethylammonio]propionate, 2-methacryloyloxyethyl thioctic acid, and [2-(methacryloyloxy)ethyl]trimethylammonium methylsulfate.

4. The quantum dot body according to claim 1, wherein the compound is contained in an amount ranging from 0.1 to 50% by mass relative to the quantum dots.

5. The quantum dot body according to claim 1, wherein the compound is contained in an amount ranging from 0.5 to 30% by mass relative to the quantum dots.

6. A quantum dot composition comprising the quantum dot bodies according to any one of claims 1 to 5 dispersed in a resin material.

7. A wavelength converting material comprising a cured product of the quantum dot composition according to claim 6.

8. A method for producing a quantum dot body according to any one of claims 1 to 5, comprising: a quantum dot production step for producing quantum dots each comprising a semiconductor nanoparticle core and a semiconductor nanoparticle shell covering the semiconductor nanoparticle core; and a quantum dot modification step for modifying the surface of the quantum dot with a compound having a methacryloyloxyethyl group and a hydrophilic group, as represented by formula (I).

9. A method for producing a quantum dot composition, comprising dispersing quantum dot bodies produced by the method for producing quantum dot bodies according to claim 8 in a resin material to produce a quantum dot composition.

10. A method for producing a wavelength converting material, comprising curing a quantum dot composition produced by the method for producing a quantum dot composition according to claim 9 to produce a wavelength converting material.

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