Coated semiconductor nanoparticles and their manufacturing methods

Abstract

This invention provides a method for manufacturing coated semiconductor nanoparticles, which includes the step of coating the surface of the semiconductor nanoparticles with a metal oxide. The method is characterized by subjecting a metal oxide precursor to microwave irradiation treatment, and then coating the surface of the semiconductor nanoparticles with the aforementioned metal oxide. This provides a method for efficiently manufacturing coated semiconductor nanoparticles with suppressed fluorescence luminescence efficiency degradation.

Description

[Technical Field]

[0001] This invention relates to coated semiconductor nanoparticles and a method for manufacturing the same. [Previous Technology]

[0002] Semiconductor particles with a diameter of nanometers are formed by the excitons generated by light absorption being encapsulated within a nanometer-sized space, resulting in discrete energy levels for the semiconductor nanoparticles. Furthermore, their band gap depends on the particle size. Therefore, the fluorescence emission of semiconductor nanoparticles is highly efficient, and their emission spectrum is sharp.

[0003] Furthermore, due to the characteristic of band gap variation due to particle size, it has the feature of being able to control the emission wavelength, and is expected to be used as a wavelength conversion material for solid-state lighting or displays (Patent Document 1).

[0004] However, semiconductor nanoparticles are prone to defects such as dangling bonds on their surfaces. Oxidation reactions caused by oxygen or moisture occur in these surface defects, forming new defect locants, thus the fluorescence efficiency deteriorates over time.

[0005] Currently available semiconductor nanoparticle systems are adversely affected by heat or humidity, photoexcitation, and particle aggregation. Furthermore, in applications such as wavelength conversion materials for displays, semiconductor nanoparticle systems are dispersed in resins, and it is known that aggregation or decreased stability of semiconductor nanoparticle systems in resins leads to a decrease in fluorescence efficiency.

[0006] Based on the above points, as a method to suppress the deterioration of the fluorescence luminescence efficiency of semiconductor nanoparticles, there is a proposal to coat the surface of semiconductor nanoparticles with a protective layer such as a metal oxide to improve stability.

[0007] For example, Patent Document 2 discloses a method for manufacturing a composite in which semiconductor nanoparticles are dispersed in silica glass by reacting the surface of semiconductor nanoparticles with metal alkoxides in stages to deposit a silica glass layer. This manufacturing method discloses a composite containing semiconductor nanoparticles that provides high fluorescence luminescence efficiency and stability.

[0008] However, when using the composite disclosed in Patent Document 2 as a wavelength conversion material, further improvement in fluorescence efficiency is required. Furthermore, regarding stability, it is necessary to suppress the deterioration of fluorescence efficiency under ambient temperature and atmospheric conditions, as well as under high temperature and high humidity conditions.

[0009] Furthermore, in Patent Document 3, a glass composite in which nanoparticles are dispersed and fixed is manufactured by adding an aqueous dispersion solution of semiconductor nanoparticles to an organic solvent containing a surfactant to form a reverse microcell containing an aqueous solution of nanoparticles, and using the reverse microcell as a reaction field for a metal oxide precursor.

[0010] The method described in Patent Document 3 can provide a glass composite exhibiting high fluorescence luminescence efficiency. However, this manufacturing method involves a reaction time of several days and uses large amounts of solvents and surfactants, thus posing challenges to mass production or cost reduction. Previous Art Documents Patent Documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2012-022028; Patent Document 2: International Publication No. 2011 / 081037; Patent Document 3: Japanese Invention Patent No. 4403270 [Summary of the Invention]

[0012] The problem that the invention is intended to solve

[0013] This invention was made to solve the above-mentioned problems, and its object is to provide a method for efficiently manufacturing coated semiconductor nanoparticles with suppressed degradation of fluorescence luminescence efficiency. Furthermore, this invention provides coated semiconductor nanoparticles with suppressed degradation of fluorescence luminescence efficiency. Means for solving the problems

[0014] The present invention was made to achieve the above-mentioned objective and provides a method for manufacturing coated semiconductor nanoparticles, which includes the step of coating a metal oxide on the surface of semiconductor nanoparticles. The method is characterized in that: a metal oxide precursor is subjected to microwave irradiation treatment, and the aforementioned metal oxide is coated on the surface of the aforementioned semiconductor nanoparticles.

[0015] According to such a method for manufacturing coated semiconductor nanoparticles, coated semiconductor nanoparticles with suppressed fluorescence luminescence efficiency can be manufactured efficiently.

[0016] At this time, it is preferable to perform the aforementioned coating step, in the presence of the aforementioned semiconductor nanoparticles and the aforementioned metal oxide precursor, to perform the aforementioned microwave irradiation treatment on the aforementioned metal oxide precursor in the presence of the aforementioned semiconductor nanoparticles, and to coat the aforementioned metal oxide on the surface of the aforementioned semiconductor nanoparticles.

[0017] In this way, metal oxides can be reliably coated onto semiconductor nanoparticles, and coated semiconductor nanoparticles with suppressed fluorescence luminescence efficiency can be manufactured more efficiently.

[0018] At this time, it is preferable to set the semiconductor nanoparticles used in the aforementioned coating step as including a semiconductor nanoparticle core and a single or multiple semiconductor nanoparticle shells covering the semiconductor nanoparticle core.

[0019] This allows for the efficient manufacture of semiconductor nanoparticles with excellent fluorescence emission properties and stability.

[0020] At this time, the semiconductor nanoparticle core used in the aforementioned coating step can be set as a single, multiple, alloy, or mixed crystal selected from ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, AgGaS2, AgInS2, AgGaSe2, AgInSe2, CuGaS2, CuGaSe2, CuInS2, CuInS2, ZnSiP2, ZnGeP2, CdSiP2, and CdGeP2.

[0021] Due to their excellent fluorescence properties and stability, these compounds are suitable for semiconductor nanoparticle cores. Among these compounds, ZnSe, ZnTe, CdSe, CdS, and InP are particularly superior in terms of fluorescence properties and stability.

[0022] At this time, it is preferable to set the semiconductor nanoparticle shell used in the aforementioned coating step as a single, multiple, alloy or mixed crystal selected from ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb.

[0023] In this way, semiconductor nanoparticles with large band gaps and low lattice mismatch can be formed for the core material. Among these compounds, ZnSe, ZnS, CdSe, and CdS are particularly superior in terms of improved fluorescence efficiency and stability.

[0024] In this case, it is preferable to carry out the aforementioned coating step in one or more solvents, namely polar solvent, non-polar solvent, and ionic liquid.

[0025] These solvents are suitable as dispersion media for semiconductor nanoparticles and metal oxide precursors.

[0026] In this case, it is preferable to use a solvent that contains more than 90% of the aforementioned non-polar solvent by volume in the coating step.

[0027] In this way, the degradation of fluorescence efficiency during coating can be suppressed more effectively.

[0028] In this case, it is preferable to use the non-polar solvent used in the aforementioned coating step as one or more solvents such as toluene, hexane, cyclohexane, benzene, and diethyl ether.

[0029] Such non-polar solvents can further improve the dispersibility of semiconductor nanoparticles.

[0030] At this time, it is preferable to set the metal oxide precursor used in the aforementioned coating step as one or more selected from metal alkoxides, metal halides, and metal complexes.

[0031] These metal oxide precursors are highly reactive and can be used as metal oxide coatings on the surface of semiconductor nanoparticles.

[0032] In this case, it is preferable to carry out the aforementioned coating step in the presence of an alkaline aqueous solution.

[0033] In this way, the control of the film thickness of the coating becomes easier.

[0034] At this time, it is preferable to carry out the aforementioned coating step in the presence of a surfactant.

[0035] In this case, the metal oxide precursor has excellent dispersibility.

[0036] In this case, it is preferable to carry out the aforementioned coating step in the presence of alcohol.

[0037] In this case, the dispersibility of the metal oxide precursor is even better.

[0038] Furthermore, it is preferable to set the microwave irradiation treatment time in the aforementioned coating step to a range of 3 to 30 minutes, and more preferably a range of 5 to 15 minutes.

[0039] Such a processing time can more effectively prevent the reduction of fluorescence luminescence efficiency.

[0040] Furthermore, it is preferable to set the heating temperature of the microwave irradiation treatment in the aforementioned coating step to a range of 40~100°C, and more preferably to a range of 50~80°C.

[0041] Although the reaction temperature in microwave irradiation treatment varies with the solvent, such a temperature can more effectively prevent the deterioration of fluorescence luminescence efficiency.

[0042] In this case, it is preferable to include a step of modifying the surface of the aforementioned semiconductor nanoparticles with a surface modifier before the aforementioned coating step.

[0043] In this way, since the metal oxide precursor reacts on the surface of the semiconductor nanoparticles through the surface modifier, the metal oxide layer is coated on the surface of the semiconductor nanoparticles more efficiently, and the degradation of fluorescence luminescence efficiency is suppressed during microwave irradiation treatment.

[0044] In this case, it is preferable to set the aforementioned surface modifier as one or more selected from (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, (3-mercaptopropyl)trimethoxysilane, (3-mercaptopropyl)triethoxysilane, 6-mercapto-1-hexanol, mercaptoacetic acid, 3-mercaptopropionic acid, and 4-mercaptobenzoic acid.

[0045] These compounds are suitable as surface modifiers.

[0046] Furthermore, the present invention provides a coated semiconductor nanoparticle, which is a coated semiconductor nanoparticle with a metal oxide coated on the surface of the semiconductor nanoparticle, wherein: the aforementioned metal oxide is coated on the surface of the aforementioned semiconductor nanoparticle by microwave irradiation treatment.

[0047] Such coated semiconductor nanoparticle systems suppress the degradation of fluorescence luminescence efficiency.

[0048] At this time, the resin composition is preferably such that the coated semiconductor nanoparticles are dispersed in the resin.

[0049] Such a resin composition is a resin composition in which the degradation of fluorescence luminescence efficiency is suppressed.

[0050] At this point, it is preferable to use a wavelength conversion material that is a hardened material with a resin composition.

[0051] If such a wavelength conversion material is used, the reliability will be improved.

[0052] At this time, it is preferable to use a light-emitting element that uses a wavelength conversion material.

[0053] Such a light-emitting element becomes the most reliable. Effects of the invention

[0054] As described above, according to the method for manufacturing coated semiconductor nanoparticles of the present invention, coated semiconductor nanoparticles with suppressed degradation of fluorescence luminescence efficiency can be efficiently manufactured. Furthermore, the coated semiconductor nanoparticles of the present invention are coated semiconductor nanoparticles with suppressed degradation of fluorescence luminescence efficiency. In addition, the coated semiconductor nanoparticles of the present invention are applicable to resin compositions, wavelength conversion materials using cured resin compositions, and light-emitting elements using wavelength conversion materials.

Implementation Method

[0055] Hereinafter, embodiments of the present invention will be described. However, in the present invention, the composition or manufacturing method of the semiconductor nanoparticles and metal oxides is not limited to the following forms only.

[0056] As described above, the problem is to efficiently manufacture semiconductor nanoparticles with suppressed fluorescence luminescence efficiency. The inventors have repeatedly and diligently examined this problem. As a result, they discovered that by a method for manufacturing coated semiconductor nanoparticles that includes a step of coating the surface of semiconductor nanoparticles with a metal oxide, and wherein the aforementioned coating step is performed by microwave irradiation, coated semiconductor nanoparticles with suppressed fluorescence luminescence efficiency can be efficiently manufactured, thus completing the present invention.

[0057] That is, the present invention is a method for manufacturing coated semiconductor nanoparticles, which includes the step of coating a metal oxide on the surface of semiconductor nanoparticles, wherein the metal oxide precursor is subjected to microwave irradiation treatment, and the aforementioned metal oxide is coated on the surface of the aforementioned semiconductor nanoparticles.

[0058] The inventors have proposed a mechanism to solve the above-mentioned problems as follows. In the coating method of metal oxide on the surface of semiconductor nanoparticles using the Stober method or the reverse microcell method, since the semiconductor nanoparticles coexist with water or oxygen for a long time, the particles aggregate due to oxidation reaction on the particle surface or ligand detachment, and the fluorescence efficiency gradually deteriorates.

[0059] On the other hand, in the method of microwave irradiation treatment, metal oxide precursors are selectively added directly from the inside to carry out the reaction in a short time. Therefore, the coating of metal oxides is carried out efficiently under mild conditions, the desorption of ligands adsorbed on the surface of semiconductor nanoparticles (quantum dots) or the surface oxidation reaction is mitigated, and the degradation of fluorescence luminescence efficiency is suppressed.

[0060] Therefore, by subjecting the metal oxide precursor to microwave irradiation, the metal oxide is coated on the surface of the semiconductor nanoparticles, thereby mitigating the detachment of ligands or the surface oxidation reaction and suppressing the deterioration of fluorescence luminescence efficiency.

[0061] The above mechanism is based on speculation, and its correctness or incorrectness does not affect the technical scope of the present invention.

[0062] (Semiconductor Nanoparticles) The structure of the semiconductor nanoparticles in this invention is not particularly limited, but from the viewpoint of fluorescence emission characteristics and stability, a core / shell structure of semiconductor nanoparticles is preferred. That is, it is preferred to include a semiconductor nanoparticle core and one or more semiconductor nanoparticle shells covering the semiconductor nanoparticle core. In the core / shell structure of semiconductor nanoparticles, which uses nano-sized semiconductor particles as the core and semiconductors with a band gap larger than the core and low lattice mismatch as the shell, the fluorescence emission efficiency is improved because the exciton system generated in the shell is sealed inside the core particle, and the stability is improved because the core surface is covered by the shell.

[0063] The material of the semiconductor nanoparticle core, which is the core / shell semiconductor nanoparticle, is not particularly limited, but it is preferred, for example, to use single, multiple, alloy or mixed crystals selected from group II-VI compounds, group III-V compounds, group I-III-VI compounds, group II-IV-V compounds.

[0064] Specific core materials include compounds containing ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, AgGaS2, AgInS2, AgGaSe2, AgInSe2, CuGaS2, CuGaSe2, CuInS2, CuInS2, CuInS2, ZnSiP2, ZnGeP2, CdSiP2, and CdGeP2. These compounds are suitable for semiconductor nanoparticle cores due to their excellent fluorescence properties and stability. Among these compounds, ZnSe, ZnTe, CdSe, CdS, and InP are particularly superior in terms of fluorescence properties and stability.

[0065] There are no particular limitations on the material used as the shell of semiconductor nanoparticles. It is preferable to use materials with large band gaps and low lattice mismatch, preferably single, multiple, alloy or mixed crystals selected from group II-VI compounds and group III-V compounds.

[0066] Specific shell compounds include those containing ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, and InSb. These compounds have large band gaps and low lattice mismatches for the core material. Among these compounds, ZnSe, ZnS, CdSe, and CdS are particularly superior in terms of improved fluorescence efficiency and stability.

[0067] There are various methods for manufacturing semiconductor nanoparticles, such as liquid-phase methods or gas-phase methods, but there are no particular limitations in this invention. From the viewpoint of exhibiting high fluorescence luminescence efficiency, semiconductor nanoparticles obtained by hot soaping or hot injection methods, which use high-boiling-point nonpolar solvents to react precursor species at high temperatures, are preferred.

[0068] Furthermore, in order to reduce surface defects, semiconductor nanoparticles preferably contain organic ligands called ligands that are coordinated on the surface. From the viewpoint of suppressing the aggregation of semiconductor nanoparticles, ligands preferably contain aliphatic hydrocarbons. Examples of such ligands include oleic acid, stearic acid, palmitic acid, myristic acid, lauric acid, decanoic acid, octanoic acid, oleylamine, stearylamine, dodecylamine, decylamine, octylamine, octadecyl mercaptan, hexadecyl mercaptan, tetradecyl mercaptan, dodecyl mercaptan, decane mercaptan, octane mercaptan, trioctylphosphine, trioctylphosphine oxide, triphenylphosphine, triphenylphosphine oxide, tributylphosphine, tributylphosphine oxide, etc., which can be used alone or in combination.

[0069] (Coated Semiconductor Nanoparticles) The method for manufacturing coated semiconductor nanoparticles of the present invention involves microwave irradiation of a metal oxide precursor to coat the surface of the semiconductor nanoparticles with metal oxide. By using microwaves to directly heat the metal oxide precursor from the inside, coating can be selectively performed in a shorter time.

[0070] The term "microwave" as used here generally refers to electromagnetic waves with a vibration frequency of 300 MHz to 3 THz. Furthermore, as a method of microwave irradiation, for example, the use of the flexi WAVE manufactured by Milestone can be cited, but there are no particular limitations.

[0071] Furthermore, in this invention, silicon oxide systems are considered to be contained within metal oxides.

[0072] The "coating" of the metal oxide on the surface of the semiconductor particles in the method for manufacturing coated semiconductor nanoparticles of the present invention can be partial or complete. Furthermore, it can be a uniform coating layer, such as a core-shell structure, or a non-uniform coating layer, or a structure where multiple semiconductor nanoparticles are coated with metal oxide. The film thickness of the metal oxide is not particularly limited, but from the viewpoint of light transmittance, it is preferably 100 nm or less.

[0073] Preferably, in the coating step, the metal oxide precursor is subjected to microwave irradiation treatment in the presence of semiconductor nanoparticles and metal oxide precursor, thereby coating the surface of the semiconductor nanoparticles with metal oxide. This ensures that the metal oxide is reliably coated onto the semiconductor nanoparticles, and allows for more efficient production of coated semiconductor nanoparticles with suppressed degradation of fluorescence luminescence efficiency.

[0074] At this time, the dispersion medium for the semiconductor nanoparticles and metal oxide precursors in the coating step is preferably one or more of a polar solvent, a non-polar solvent, and an ionic liquid, and the coating is carried out in the solvent. Such solvents are suitable as dispersion media for semiconductor nanoparticles and metal oxide precursors.

[0075] In this case, it is preferable to set the proportion of non-polar solvent to 90% or more by volume. If such a solvent is used, the degradation of fluorescence efficiency during coating can be suppressed.

[0076] Furthermore, it is preferable to use one or more of the following non-polar solvents in the coating step: toluene, hexane, cyclohexane, benzene, and diethyl ether. Such non-polar solvents can further improve the dispersibility of semiconductor nanoparticles. Also, when the solvent is non-polar, a heating element such as a microwave adsorption element, called Weflon, can be used arbitrarily during the coating step.

[0077] There are no particular limitations on the metal oxide precursor, but it is preferable to use one or more of metal alkoxides, metal halides, and metal complexes. These metal oxide precursors are highly reactive and suitable for coating the surface of semiconductor nanoparticles with metal oxides.

[0078] Examples of metal alkoxide compounds include tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetraisopropyl orthosilicate, tetrabutyl orthosilicate, tetra(2-ethylhexyloxy)silane, trimethoxysilane, triethoxysilane, (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, (3-mercaptopropyl)trimethoxysilane, (3- Mercaptopropyl)triethoxysilane, titanium ethoxide, tetraisopropyl titanium ethoxide, tetrabutyl titanium ethoxide, tetraisobutyl titanium ethoxide, tetra(2-ethylhexyl) titanate, zinc isopropyl oxide, zinc tributyl oxide, zirconium ethoxide, zirconium propionate oxide, zirconium butyrate oxide, aluminum ethoxide, aluminum isopropyl oxide, aluminum tributyl oxide, aluminum dibutyl oxide, yttrium isopropyl oxide, hafnium ethoxide, hafnium tributyl oxide, iron ethoxide, iron isopropyl oxide.

[0079] Also, examples of metal halide compounds include titanium chloride, zinc chloride, silicon tetrachloride, zirconium chloride, aluminum chloride, yttrium chloride, ferric chloride (II), ferric chloride (III), titanium bromide, zinc bromide, zirconium bromide, hafnium bromide, aluminum bromide, yttrium bromide, ferric bromide (II), ferric bromide (III), titanium iodide, zinc iodide, silicon tetraiodide, zirconium iodide, hafnium iodide, aluminum iodide, yttrium iodide, ferric iodide (II), ferric iodide (III), etc.

[0080] Also, examples of metal complexes include aluminum acetone, titanium acetone, iron acetone (III), zinc acetone, and zirconium acetone.

[0081] From a stability point of view, silicon alkoxides, aluminum alkoxides, zirconium alkoxides, and titanyl alkoxides are preferred as metal oxide precursors. The mixing ratio (weight ratio) of semiconductor nanoparticles and metal oxide precursors is preferably 1:0.4 to 1:3.

[0082] At this time, a catalyst is preferably used during the coating step to promote the reaction of the metal oxide precursor. In particular, when using metal alkoxides, a catalyst is preferably used to promote the sol-gel reaction. As a catalyst, acidic or alkaline aqueous solutions can be used, and from the viewpoint of the film thickness of the coated layer, an alkaline aqueous solution is particularly preferred. The mixing ratio (molar ratio) of the catalyst to the metal oxide precursor is preferably 1:0.4 to 1:2, and the mixing ratio (molar ratio) of the metal oxide precursor to water is preferably 1:2 to 1:10.

[0083] Furthermore, in the coating step, from the viewpoint of the dispersibility of the metal oxide precursor, it is preferable to use a surfactant. There are no particular limitations on the surfactant, but examples include cationic surfactants such as the quaternary ammonium salt of cetyltrimethylammonium bromide, anionic surfactants such as carboxylates or sulfonates, and nonionic surfactants such as polyoxyethylene alkyl ethers. From the viewpoint of the dispersibility of the metal oxide precursor, cationic surfactants are particularly preferred. The surfactant can be added directly or dissolved in a polar solvent such as an alcohol, as described later, to form a solution.

[0084] Furthermore, it is preferable to perform the coating step in the presence of an alcohol. If the coating is performed in the presence of an alcohol, the dispersibility of the metal oxide precursor is better. Also, when a surfactant is added, dispersibility can be further improved by dissolving it in a polar solvent such as an alcohol.

[0085] Furthermore, prior to the coating step, it is preferable to include a step of modifying the surface of the semiconductor nanoparticles with a surface modifier. Through this modification step, since the metal oxide precursor reacts on the surface of the semiconductor nanoparticles through the surface modifier, the metal oxide layer can be coated onto the surface of the semiconductor nanoparticles more efficiently, and the degradation of fluorescence luminescence efficiency can be suppressed during microwave irradiation treatment.

[0086] The surface modifier is preferably a compound containing a substituent such as an SH group or NH2 group at one end of the molecule that is adsorbed onto the surface of the semiconductor nanocrystalline particles, and a substituent such as a -Si(OR)3 group (R: an alkyl group with 4 or fewer carbon atoms) or an OH group or a COOH group at another end that reacts with the metal oxide precursor. Examples of surface modifiers include (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, (3-mercaptopropyl)trimethoxysilane, (3-mercaptopropyl)triethoxysilane, 6-mercapto-1-hexanol, mercaptoacetic acid, 3-mercaptopropionic acid, and 4-mercaptobenzoic acid, which can be used alone or in combination. There are no particular limitations on the environment in which the surface modifier is modified, but it can be carried out, for example, in an inert gas environment such as nitrogen.

[0087] At this time, although the reaction temperature of microwave irradiation treatment varies with the solvent, from the point of view of preventing the deterioration of fluorescence luminescence efficiency, it is preferably 40~100℃, and more preferably 50~80℃.

[0088] At this time, from the point of view of preventing the reduction of fluorescence luminescence efficiency, the processing time of microwave irradiation should be 3 to 30 minutes, and more preferably 5 to 15 minutes.

[0089] Furthermore, the present invention provides a semiconductor nanoparticle, which is a coated semiconductor nanoparticle on the surface of a semiconductor nanoparticle coated with a metal oxide, wherein: the aforementioned metal oxide is coated on the surface of the aforementioned semiconductor nanoparticle by microwave irradiation treatment.

[0090] The coated semiconductor nanoparticles of the present invention are metal oxides coated onto the surface of semiconductor nanoparticles by microwave treatment. Such coated semiconductor nanoparticles of the present invention suppress the degradation of fluorescence luminescence efficiency. Examples of semiconductor nanoparticles and metal oxides include the aforementioned semiconductor nanoparticles and metal oxides.

[0091] The microwave irradiation coating of the present invention involves coating the surface of semiconductor nanoparticles with a metal oxide coated with microwave irradiation. The microwave is as described above.

[0092] Furthermore, the aforementioned coated semiconductor nanoparticles are preferably used as a resin composition dispersed in the resin. In this way, it can become a resin composition in which the degradation of fluorescence luminescence efficiency is suppressed.

[0093] The resin material is not particularly limited, but it is preferably one that does not cause aggregation of coated semiconductor nanoparticles or deterioration of fluorescence luminescence efficiency. Examples include polysiloxane resin, acrylic resin, epoxy resin, urethane resin, and fluororesin. Since these materials are intended to improve fluorescence luminescence efficiency as wavelength conversion materials, they are preferably those with high transmittance, especially 80% or higher.

[0094] Furthermore, it is preferable to use a cured material containing the aforementioned resin composition as a wavelength conversion material. Such a wavelength conversion material improves reliability. The wavelength conversion material can be used directly or processed. For example, one form is a wavelength conversion film in which a composite is dispersed in a resin after being processed into a sheet and then cured.

[0095] There is no particular limitation on the method of making wavelength conversion materials, but for example, a resin composition in which coated semiconductor nanoparticles are dispersed in a resin can be coated on a transparent film such as PET or polyimide and then hardened, and the wavelength conversion material can be obtained by lamination.

[0096] The coating of the transparent film can be performed using spraying or inkjet methods, spin coating, bar coating, or doctor blade coating to form a resin layer. Furthermore, the thickness of the resin layer and the transparent film is not particularly limited and can be appropriately selected according to the application.

[0097] There is no particular limitation on the method of hardening the resin composition, but for example, the film coated with the resin composition can be heated at 60°C for 2 hours and then heated at 150°C for 4 hours.

[0098] Furthermore, it is preferable to use it as a light-emitting element employing the aforementioned wavelength conversion material. There are no particular limitations on the light-emitting element; examples include light-emitting diodes. Light-emitting elements employing such wavelength conversion materials exhibit particularly excellent reliability. Example

[0099] Hereinafter, the present invention will be specifically described using examples and comparative examples, but the present invention is not limited thereto.

[0100] (Evaluation of luminescence properties) In the manufacturing examples and embodiments, as an evaluation of the fluorescence luminescence properties of semiconductor nanoparticles, the fluorescence luminescence efficiency (internal quantum efficiency) at an excitation wavelength of 450 nm was measured using a quantum efficiency measurement system (QE-2100) manufactured by Otsuka Electronics Co., Ltd.

[0101] (Manufacturing of Semiconductor Nanoparticles) (Manufacturing Example 1) 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 added to a flask. The mixture was heated and stirred at 100°C under reduced pressure, and degassed for 1 hour while dissolving. After cooling the flask to room temperature, nitrogen gas was purged, and 0.50 mL (0.17 mmol) of a 10 vol% (ref) trimethylsilylphosphine / octadecene solution was added to the flask. The flask was heated to 300°C and stirred for 20 minutes to synthesize InP semiconductor core particles.

[0102] Next, after cooling the flask to 200°C, 4.0 mL (1.2 mmol) of 0.30 M zinc stearate / octadecene solution was added and stirred for 30 minutes. Then, 0.60 mL (0.90 mmol) of 1.5 M selenium / trioctylphosphine solution was added to the flask and stirred for 30 minutes. Next, after cooling the flask to room temperature, 0.22 g (1.1 mmol) of zinc acetate was added, and the mixture was heated and stirred at 100°C under reduced pressure, degassing for 1 hour while dissolving. After purging the flask with nitrogen, it was heated to 230°C, and 0.48 mL (2.0 mmol) of 1-DDT (dodecanethiol) was added and stirred for 30 minutes.

[0103] The obtained solution was cooled to room temperature, ethanol was added, and the semiconductor nanoparticles were precipitated by centrifugation. The supernatant was removed. Toluene was then added to the precipitate to disperse it, ethanol was added again, and the mixture was centrifuged to remove the supernatant, thus redispersing the nanoparticles in toluene to prepare an InP / ZnSe / ZnS semiconductor nanoparticle toluene solution. The fluorescence efficiency of the solution was 76%.

[0104] (Manufacturing Example 2) 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 added to a flask. The mixture was heated and stirred at 100°C under reduced pressure, and degassed for 1 hour while dissolving. After cooling the flask to room temperature, nitrogen gas was purged, and 0.50 mL (0.17 mmol) of a 10 vol% (ref) trimethylsilylphosphine / octadecene solution was added to the flask. The flask was heated to 300°C and stirred for 20 minutes to synthesize InP semiconductor core particles.

[0105] Next, after cooling the flask to 200°C, 4.0 mL (1.2 mmol) of 0.30 M zinc stearate / octadecene solution was added and stirred for 30 minutes. Then, 0.60 mL (0.90 mmol) of 1.5 M selenium / trioctylphosphine solution was added to the flask and stirred for 30 minutes. Next, after cooling the flask to room temperature, 0.22 g (1.1 mmol) of zinc acetate was added, and the mixture was heated and stirred at 100°C under reduced pressure, degassing for 1 hour while dissolving. After purging the flask with nitrogen, it was heated to 230°C, and 0.48 mL (2.0 mmol) of 1-DDT was added and stirred for 30 minutes. Then, 0.70 mL (3.0 mmol) of (3-aminopropyl)triethoxysilane was added to the flask and stirred for 30 minutes.

[0106] The obtained solution was cooled to room temperature, ethanol was added, and the semiconductor nanoparticles were precipitated by centrifugation. The supernatant was removed. Toluene was then added to the precipitate to disperse it, ethanol was added again, and the mixture was centrifuged to remove the supernatant, thus redispersing the nanoparticles in toluene to prepare an InP / ZnSe / ZnS semiconductor nanoparticle toluene solution. The fluorescence efficiency of the solution was 75%.

[0107] (Manufacturing Example 3) 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 added to a flask. The mixture was heated and stirred at 100°C under reduced pressure, and degassed for 1 hour while dissolving. After cooling the flask to room temperature, nitrogen gas was purged, and 0.50 mL (0.17 mmol) of a 10 vol% (ref) trimethylsilylphosphine / octadecene solution was added to the flask. The flask was heated to 300°C and stirred for 20 minutes to synthesize InP semiconductor core particles.

[0108] Next, after cooling the flask to 200°C, 4.0 mL (1.2 mmol) of 0.30 M zinc stearate / octadecene solution was added and stirred for 30 minutes. Then, 0.60 mL (0.90 mmol) of 1.5 M selenium / trioctylphosphine solution was added to the flask and stirred for 30 minutes. Next, after cooling the flask to room temperature, 0.22 g (1.1 mmol) of zinc acetate was added, and the mixture was heated and stirred at 100°C under reduced pressure, degassing for 1 hour while dissolving. After purging the flask with nitrogen, it was heated to 230°C, and 0.48 mL (2.0 mmol) of 1-DDT was added and stirred for 30 minutes. Then, 0.72 mL (3.0 mmol) of (3-mercaptopropyl)triethoxysilane was added to the flask and stirred for 30 minutes.

[0109] The obtained solution was cooled to room temperature, ethanol was added, and the semiconductor nanoparticles were precipitated by centrifugation. The supernatant was removed. Toluene was then added to the precipitate to disperse it, ethanol was added again, and the mixture was centrifuged to remove the supernatant, thus redispersing the nanoparticles in toluene to prepare an InP / ZnSe / ZnS semiconductor nanoparticle toluene solution. The fluorescence efficiency of the solution was 74%.

[0110] (Manufacturing Example 4) 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 added to a flask. The mixture was heated and stirred at 100 °C under reduced pressure, and degassed for 1 hour while dissolving. After cooling the flask to room temperature, nitrogen gas was purged, and 0.50 mL (0.17 mmol) of a 10 vol% (ref) trimethylsilylphosphine / octadecene solution was added to the flask. The flask was heated to 300 °C and stirred for 20 minutes to synthesize InP semiconductor core particles.

[0111] Next, after cooling the flask to 200°C, 4.0 mL (1.2 mmol) of 0.30 M zinc stearate / octadecene solution was added, and the mixture was stirred for 30 minutes. Then, 0.60 mL (0.90 mmol) of 1.5 M selenium / trioctylphosphine solution was added to the flask, and the mixture was stirred for 30 minutes. Next, after cooling the flask to room temperature, 0.22 g (1.1 mmol) of zinc acetate was added, and the mixture was heated and stirred at 100°C under reduced pressure, degassing 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-DDT was added, and the mixture was stirred for 30 minutes. Then, 0.35 mL (1.5 mmol) of (3-aminopropyl)triethoxysilane and 0.36 mL (1.5 mmol) of (3-mercaptopropyl)triethoxysilane were added to the flask, and the mixture was stirred for 30 minutes.

[0112] The obtained solution was cooled to room temperature, ethanol was added, and the semiconductor nanoparticles were precipitated by centrifugation. The supernatant was removed. Toluene was then added to the precipitate to disperse it, ethanol was added again, and the mixture was centrifuged to remove the supernatant, thus redispersing the nanoparticles in toluene to prepare an InP / ZnSe / ZnS semiconductor nanoparticle toluene solution. The fluorescence efficiency of the solution was 74%.

[0113] Table 1 summarizes the manufacturing examples 1 to 4 above.

[0114]

[0115] (Manufacturing of Coated Semiconductor Nanoparticles) Hereinafter, the method for manufacturing coated semiconductor nanoparticles of the present invention will be implemented using the semiconductor nanoparticles manufactured in Examples 1 to 4. Furthermore, microwave irradiation will be performed using a microwave synthesis reaction apparatus (flexi WAVE manufactured by MILESTONE CENERAL).

[0116] (Example 1) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution, 100 μL of tetraethyl orthosilicate, and 50 μL of a 25% ammonia (NH3) aqueous solution obtained in Example 1 were added to a high-pressure reaction vessel. The mixing ratios were semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:0.94, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio): H2O = 1:4.6. Then, metal oxide coating was performed by heating at 2450 MHz and 60 °C for 10 minutes using the above-described microwave synthesis reaction apparatus. The resulting coated semiconductor nanoparticles were settled by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The fluorescence efficiency of the resulting coated semiconductor nanoparticles was 72%. The reduction rate of fluorescence efficiency compared to that before the coating step was 5.3%.

[0117] (Example 2) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and 0.010 g of cetyltrimethylammonium bromide obtained in Example 1 were added to a high-pressure reaction vessel. The mixing ratio was semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:0.94, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio): H2O = 1:4.6. Then, using the above-described microwave synthesis reaction apparatus, metal oxide coating was performed by heating at 2450 MHz at 60°C for 10 minutes. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 70%, which is a decrease of 7.9% compared to the fluorescence efficiency before the coating step.

[0118] (Example 3) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Example 1, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution were added to a high-pressure reaction vessel. The mixing ratio was semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:0.94, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio): H2O = 1:4.6. Then, using the above-described microwave synthesis reaction apparatus, metal oxide coating was performed by heating at 2450 MHz at 60°C for 10 minutes. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 70%, which is a decrease of 7.9% compared to the fluorescence efficiency before the coating step.

[0119] (Example 4) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution, 0.092 g of isopropyl alumina, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution obtained in Example 1 were added to a high-pressure reaction vessel. The mixing ratios were semiconductor nanoparticles: isopropyl alumina (weight ratio) = 1:0.92, NH3: isopropyl alumina (molar ratio) = 1:0.89, and isopropyl alumina (molar ratio): H2O = 1:4.6. Then, using the above-described microwave synthesis reaction apparatus, metal oxide coating was performed by heating at 2450 MHz at 60°C for 10 minutes. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 68%, which is 10.5% lower than the fluorescence efficiency before the coating step.

[0120] (Example 5) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution, 0.153 g of tetrabutyl titanium dioxide, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution obtained in Example 1 were added to a high-pressure reaction vessel. The mixing ratios were semiconductor nanoparticles: tetrabutyl titanium dioxide (weight ratio) = 1:1.5, NH3: tetrabutyl titanium dioxide (molar ratio) = 1:0.89, and tetrabutyl titanium dioxide (molar ratio): H2O = 1:4.6. Then, metal oxide coating was performed by heating at 2450 MHz and 60 °C for 10 minutes using the above-described microwave synthesis reaction apparatus. The resulting coated semiconductor nanoparticles were settled by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 65%, which is 14.5% lower than the fluorescence efficiency before the coating step.

[0121] (Example 6) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution, 0.147 g of zirconium oxypropane, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution obtained in Example 1 were added to a high-pressure reaction vessel. The mixing ratios were semiconductor nanoparticles:zirconia (weight ratio) = 1:1.5, NH3:zirconia (molar ratio) = 1:0.89, and zirconium oxypropane (molar ratio):H2O = 1:4.6. Then, metal oxide coating was performed by heating at 2450 MHz and 60 °C for 10 minutes using the above-described microwave synthesis reaction apparatus. The resulting coated semiconductor nanoparticles were settled by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 67%, which is 11.8% lower than the fluorescence efficiency before the coating step.

[0122] (Example 7) 10 g of the 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Example 1, 50 μL of tetraethyl orthosilicate, 50 μL of 25% ammonia solution, and 0.010 g / 100 μL of cetyltrimethylammonium bromide / ethanol solution were added to a high-pressure reaction vessel. The mixing ratio was: semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:0.47, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio): H2O = 1:4.6. Then, using the above-described microwave synthesis apparatus, metal oxide coating was performed by heating at 2450 MHz at 60°C for 10 minutes. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 73%, which is 3.9% lower than the fluorescence efficiency before the coating step.

[0123] (Example 8) 10 g of the 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Example 1, 200 μL of tetraethyl orthosilicate, 50 μL of 25% ammonia solution, and 0.010 g / 100 μL of cetyltrimethylammonium bromide / ethanol solution were added to a high-pressure reaction vessel. The mixing ratios were: semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:1.9, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio): H2O = 1:4.6. Then, using the above-described microwave synthesis apparatus, metal oxide coating was performed by heating at 2450 MHz at 60°C for 10 minutes. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 70%, which is a decrease of 7.9% compared to the fluorescence efficiency before the coating step.

[0124] (Example 9) 10 g of the 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Example 1, 300 μL of tetraethyl orthosilicate, 50 μL of 25% ammonia solution, and 0.010 g / 100 μL of cetyltrimethylammonium bromide / ethanol solution were added to a high-pressure reaction vessel. The mixing ratios were: semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:2.8, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio): H2O = 1:4.6. Then, using the above-described microwave synthesis apparatus, metal oxide coating was performed by heating at 2450 MHz at 60°C for 10 minutes. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 68%, which is 10.5% lower than the fluorescence efficiency before the coating step.

[0125] (Example 10) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Example 1, 100 μL of tetraethyl orthosilicate, 25 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution were added to a high-pressure reaction vessel. The mixing ratios were: semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:0.94, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.45, and tetraethyl orthosilicate (molar ratio): H2O = 1:2.3. Then, using the above-described microwave synthesis apparatus, metal oxide coating was performed by heating at 2450 MHz at 60°C for 10 minutes. The resulting coated semiconductor nanoparticles were centrifuged to allow sedimentation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 73%, which is 3.9% lower than the fluorescence efficiency before the coating step.

[0126] (Example 11) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Example 1, 100 μL of tetraethyl orthosilicate, 100 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution were added to a high-pressure reaction vessel. The mixing ratios were: semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:0.94, NH3: tetraethyl orthosilicate (molar ratio) = 1:1.8, and tetraethyl orthosilicate (molar ratio): H2O = 1:9.2. Then, using the above-described microwave synthesis apparatus, metal oxide coating was performed by heating at 2450 MHz at 60°C for 10 minutes. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 68%, which is 10.5% lower than the fluorescence efficiency before the coating step.

[0127] (Example 12) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Example 1, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution were added to a high-pressure reaction vessel. The mixing ratios were semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:0.94, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio): H2O = 1:4.6. Then, using the above-described microwave synthesis reaction apparatus, metal oxide coating was performed by heating at 2450 MHz at 40°C for 10 minutes. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 73%, which is 3.9% lower than the fluorescence efficiency before the coating step.

[0128] (Example 13) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Example 1, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution were added to a high-pressure reaction vessel. Then, using the aforementioned microwave synthesis apparatus, metal oxide coating was performed by heating at 2450 MHz and 50°C for 10 minutes. The resulting coated semiconductor nanoparticles were settled by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles had a fluorescence efficiency of 72%, representing a reduction of 5.3% compared to the fluorescence efficiency before the coating step.

[0129] (Example 14) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Example 1, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution were added to a high-pressure reaction vessel. The mixing ratios were semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:0.94, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio): H2O = 1:4.6. Then, using the above-described microwave synthesis reaction apparatus, metal oxide coating was performed by heating at 2450 MHz and 80°C for 10 minutes. The resulting coated semiconductor nanoparticles were settled by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 67%, which is 11.8% lower than the fluorescence efficiency before the coating step.

[0130] (Example 15) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Example 1, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution were added to a high-pressure reaction vessel. The mixing ratios were semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:0.94, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio): H2O = 1:4.6. Then, using the above-described microwave synthesis reaction apparatus, metal oxide coating was performed by heating at 2450 MHz at 100°C for 10 minutes. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 62%, which is 18.4% lower than the fluorescence efficiency before the coating step.

[0131] (Example 16) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Example 1, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution were added to a high-pressure reaction vessel. The mixing ratios were semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:0.94, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio): H2O = 1:4.6. Then, using the above-described microwave synthesis reaction apparatus, metal oxide coating was performed by heating at 2450 MHz at 60°C for 3 minutes. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 73%, which is 3.9% lower than the fluorescence efficiency before the coating step.

[0132] (Example 17) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Example 1, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution were added to a high-pressure reaction vessel. The mixing ratios were semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:0.94, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio): H2O = 1:4.6. Then, using the above-described microwave synthesis reaction apparatus, metal oxide coating was performed by heating at 2450 MHz at 60°C for 5 minutes. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 73%, which is 3.9% lower than the fluorescence efficiency before the coating step.

[0133] (Example 18) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Example 1, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution were added to a high-pressure reaction vessel. The mixing ratios were semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:0.94, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio): H2O = 1:4.6. Then, using the above-described microwave synthesis reaction apparatus, metal oxide coating was performed by heating at 2450 MHz at 60°C for 15 minutes. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 70%, which is a decrease of 7.9% compared to the fluorescence efficiency before the coating step.

[0134] (Example 19) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Example 1, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution were added to a high-pressure reaction vessel. Then, using the aforementioned microwave synthesis apparatus, metal oxide coating was performed by heating at 2450 MHz at 60°C for 20 minutes. The respective mixing ratios were semiconductor nanoparticles:tetraethyl orthosilicate (weight ratio) = 1:0.94, NH3:tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio):H2O = 1:4.6. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 69%, which is 9.2% lower than the fluorescence efficiency before the coating step.

[0135] (Example 20) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Example 1, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution were added to a high-pressure reaction vessel. Then, using the aforementioned microwave synthesis apparatus, the metal oxide was produced by heating at 2450 MHz at 60°C for 30 minutes. The mixing ratios were semiconductor nanoparticles:tetraethyl orthosilicate (weight ratio) = 1:0.94, NH3:tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio):H2O = 1:4.6. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, the supernatant was removed, toluene was added, and the particles were redispersed by ultrasonic irradiation. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 67%, which is 11.8% lower than the fluorescence efficiency before the coating step.

[0136] (Example 21) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution obtained in Example 2 were added to a high-pressure reaction vessel. The mixing ratios were semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:0.94, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio): H2O = 1:4.6. Then, metal oxide coating was performed by heating at 2450 MHz at 60°C for 10 minutes using the above-described microwave synthesis apparatus. The resulting coated semiconductor nanoparticles were settled by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 74%, which is 1.3% lower than the fluorescence efficiency before the coating step.

[0137] (Example 22) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Example 3, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution were added to a high-pressure reaction vessel. The mixing ratios were semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:0.94, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio): H2O = 1:4.6. Then, using the above-described microwave synthesis reaction apparatus, metal oxide coating was performed by heating at 2450 MHz at 60°C for 10 minutes. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 73%, which is 1.4% lower than the fluorescence efficiency before the coating step.

[0138] (Example 23) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of a cetyltrimethylammonium bromide / ethanol solution obtained in Example 4 were added to a high-pressure reaction vessel. The mixing ratios were semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:0.94, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate (molar ratio): H2O = 1:4.6. Then, using the above-described microwave synthesis reaction apparatus, metal oxide coating was performed by heating at 2450 MHz at 60°C for 10 minutes. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The resulting coated semiconductor nanoparticles have a fluorescence efficiency of 74%, which is 1.3% lower than the fluorescence efficiency before the coating step.

[0139] Table 2 summarizes the manufacturing methods of Examples 1 to 23 above.

[0140]

[0141] (Comparative Example 1) 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Mixed Manufacturing Example 1, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and 0.010 g / 100 μL of cetyltrimethylammonium bromide / ethanol solution were added to a flask. The flask was then heated and stirred at 60°C for 6 hours under a heating mantle to coat the nanoparticles with metal oxides. The coated semiconductor nanoparticles were centrifuged to allow them to settle, the supernatant was removed, toluene was added, and the flask was subjected to ultrasonic irradiation to redisperse them. The resulting coated semiconductor nanoparticles exhibited a fluorescence efficiency of 56%, representing a 35.7% reduction in fluorescence efficiency compared to the method using microwave irradiation. This demonstrates a significant decrease in fluorescence efficiency compared to the manufacturing method using microwave irradiation.

[0142] (Comparative Example 2) 50 mL of cyclohexane, 1.2 g of polyoxyethylene (5) nonylphenyl ether (IGEPAL-CO520 manufactured by RHODIA), and 100 μL of tetraethyl orthosilicate were added, followed by 5 g of a 2.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Manufacturing Example 1. The mixture was stirred at room temperature (25°C). While stirring, 1 mL of 10% ammonia solution was added little by little, and the mixture was stirred for 48 hours to achieve metal oxide coating. The coated semiconductor nanoparticles were centrifuged to allow them to settle, the supernatant was removed, toluene was added, and ultrasonic irradiation was performed to redisperse them. The fluorescence efficiency of the resulting coated semiconductor nanoparticles was 26%, representing a reduction of 65.8% compared to the fluorescence efficiency before the coating step. Compared with the manufacturing method using microwave irradiation, a significant reduction in fluorescence efficiency was confirmed.

[0143] As described above, Comparative Example 1 used a heating mantle instead of microwave irradiation, which resulted in a longer treatment time and a significant decrease in fluorescence efficiency. Furthermore, in Comparative Example 2, the treatment was completed at room temperature for 48 hours, which was longer than in Comparative Example 1, and the fluorescence efficiency was significantly lower than in Comparative Example 1.

[0144] On the other hand, in Examples 1 to 23 of the method for manufacturing coated semiconductor nanoparticles of the present invention, microwave irradiation is used to coat the surface of the semiconductor nanoparticles with metal oxide in a short time, thereby suppressing the degradation of fluorescence luminescence efficiency in the coating step and confirming that coated semiconductor nanoparticles with high fluorescence luminescence efficiency can be efficiently manufactured.

[0145] (Method for Manufacturing Wavelength Conversion Material) Using the coated semiconductor nanoparticles obtained in Examples 1-23, Comparative Examples 1 and 2, and the uncoated semiconductor nanoparticles obtained in Manufacturing Example 1 as a direct user, a wavelength conversion material was prepared as Comparative Example 3. 1.0 g of a 1.0 wt% toluene solution of the aforementioned semiconductor nanoparticles or coated semiconductor nanoparticles was mixed with 10.0 g of polysiloxane resin (LPS-5547 manufactured by Shin-Etsu Chemical Industry Co., Ltd.), and solvent removal was performed under reduced pressure while stirring and heating at 60°C. Then, vacuum degassing was performed, and the mixture was coated onto a 50 μm thick polyethylene terephthalate (PET) film, forming a 100 μm thick semiconductor nanoparticle resin layer using a rod coater. Furthermore, a PET film was laminated onto this resin layer. The film was heated at 60°C for 2 hours and then at 150°C for 4 hours to harden the semiconductor nanoparticle resin layer, thus preparing the wavelength conversion material.

[0146] The obtained wavelength conversion material was treated at 85°C and 85%RH (relative humidity) for 100 hours. The fluorescence efficiency of the treated wavelength conversion material was measured, and its reliability was evaluated. Table 3 shows the fluorescence efficiency of the wavelength conversion material after fabrication and the fluorescence efficiency after reliability evaluation.

[0147]

[0148] According to the results in Table 3, the fluorescence luminescence efficiency of the wavelength conversion material after reliability evaluation was 17% for Comparative Example 1, 9% for Comparative Example 2, and 17% for Comparative Example 3. The fluorescence luminescence efficiency after reliability evaluation was less than 20% among all the comparative examples.

[0149] On the other hand, the coated semiconductor nanoparticles manufactured by the method of manufacturing coated semiconductor nanoparticles of the present invention (Examples 1-23) have a fluorescence luminescence efficiency of 20% or more after reliability evaluation. As mentioned above, the coated semiconductor nanoparticles manufactured by the method of manufacturing coated semiconductor nanoparticles of the present invention exhibit high stability, and the wavelength conversion materials using them suppress the degradation of fluorescence luminescence efficiency under high temperature and high humidity conditions, confirming high reliability. Thus, the coated semiconductor nanoparticles manufactured by the method of manufacturing coated semiconductor nanoparticles of the present invention have better physical properties than conventional materials, and are significantly different from conventional materials.

[0150] Furthermore, the present invention is not limited to the above-described embodiments. The above-described embodiments are examples of any invention that has a structure substantially the same as the technical concept described in the claims of the present invention and achieves the same effect, and are all included in the technical scope of the present invention.

Claims

1. A method for manufacturing coated semiconductor nanoparticles, comprising the step of coating a metal oxide onto the surface of semiconductor nanoparticles, characterized in that: a metal oxide precursor is subjected to microwave irradiation treatment, and the metal oxide is coated onto the surface of the semiconductor nanoparticles; the semiconductor nanoparticles used in the coating step are configured to include a semiconductor nanoparticle core and one or more semiconductor nanoparticle shells covering the semiconductor nanoparticle core; the semiconductor nanoparticle core is configured as InP; the semiconductor nanoparticle shells are configured as ZnS or ZnSe; the semiconductor nanoparticles are configured as InP / ZnSe / ZnS; the metal oxide precursor used in the coating step is selected from metal alkoxides; and the compound of the metal alkoxide is any one of tetrabutyl titanium oxide, zirconium propylene oxide, or isopropyl alumina.

2. The method for manufacturing coated semiconductor nanoparticles as claimed in claim 1, wherein in the aforementioned coating step, in the coexistence of the aforementioned semiconductor nanoparticles and the aforementioned metal oxide precursor, the aforementioned metal oxide precursor in the coexistence is subjected to the aforementioned microwave irradiation treatment, and the aforementioned metal oxide is coated on the surface of the aforementioned semiconductor nanoparticles.

3. The method for manufacturing coated semiconductor nanoparticles as claimed in claim 1 or 2, wherein the aforementioned coating step is performed in one or more solvents, namely a polar solvent, a non-polar solvent, and an ionic liquid.

4. The method for manufacturing coated semiconductor nanoparticles as claimed in claim 3, wherein the solvent used in the aforementioned coating step is a solvent containing more than 90% of the aforementioned non-polar solvent by volume.

5. The method for manufacturing coated semiconductor nanoparticles as claimed in claim 3, wherein the nonpolar solvent used in the aforementioned coating step is set to one or more solvents such as toluene, hexane, cyclohexane, benzene, and diethyl ether.

6. A method for manufacturing coated semiconductor nanoparticles as claimed in claim 1 or 2, wherein the aforementioned coating step is performed in the presence of an alkaline aqueous solution.

7. A method for manufacturing coated semiconductor nanoparticles as claimed in claim 1 or 2, wherein the aforementioned coating step is performed in the presence of a surfactant.

8. A method for manufacturing coated semiconductor nanoparticles as claimed in claim 1 or 2, wherein the aforementioned coating step is performed in the presence of alcohol.

9. The method for manufacturing coated semiconductor nanoparticles as claimed in claim 1 or 2, wherein the processing time of the microwave irradiation treatment in the aforementioned coating step is set to a range of 3 to 30 minutes.

10. A method for manufacturing coated semiconductor nanoparticles as claimed in claim 1 or 2, wherein the heating temperature of the microwave irradiation treatment in the aforementioned coating step is set to a range of 40 to 100°C.

11. A method for manufacturing coated semiconductor nanoparticles as claimed in claim 1 or 2, wherein prior to the aforementioned coating step, a step of modifying the surface of the aforementioned semiconductor nanoparticles with a surface modifier is included.

12. The method for manufacturing coated semiconductor nanoparticles as claimed in claim 11, wherein the aforementioned surface modifier is selected from (3-aminopropyl)triethoxysilane and (3-mercaptopropyl)triethoxysilane, either alone or in combination.