Coated semiconductor nanoparticles and methods of making the same

Abstract

A method for producing a coated semiconductor nanoparticle, including a step of coating a metal oxide on a surface of a semiconductor nanoparticle, characterized in that the metal oxide is coated on the surface of the semiconductor nanoparticle by microwave irradiation treatment of a metal oxide precursor. Thus, a method for efficiently producing a coated semiconductor nanoparticle in which deterioration of fluorescence emission efficiency is suppressed is provided.

Description

Technical Field

[0001] This invention relates to coated semiconductor nanoparticles and their manufacturing methods. Background Technology

[0002] Nanoscale semiconductor particles, due to the excitons generated by light absorption being encapsulated within nanoscale spaces, exhibit discrete energy levels, and their band gaps are size-dependent. Therefore, the fluorescence emission of semiconductor nanoparticles is highly efficient and exhibits a sharp emission spectrum.

[0003] Furthermore, based on the characteristic that the band gap changes with the 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 forming dangling bonds on their surfaces. Oxidation reactions caused by oxygen or moisture occur at these surface defects, leading to the formation of new defect energy levels. As a result, the fluorescence efficiency deteriorates over time.

[0005] For currently available semiconductor nanoparticles, factors such as heat or humidity, photoexcitation, and particle aggregation can sometimes adversely affect fluorescence efficiency. Furthermore, depending on their application in displays, these wavelength-converting materials are often dispersed in resins or similar materials; however, it is known that semiconductor nanoparticles can experience reduced fluorescence efficiency due to aggregation or decreased stability within the resin.

[0006] Based on the above points, as a method to suppress the degradation of fluorescence luminescence efficiency of semiconductor nanoparticles, a technique is proposed that uses a metal oxide protective layer to coat the surface of semiconductor nanoparticles, thereby improving stability.

[0007] For example, Patent Document 2 discloses a method for manufacturing a composite in which semiconductor nanoparticles are dispersed in silicon glass by causing a phased reaction of metal alkoxides on the surface of semiconductor nanoparticles to accumulate a silicon glass layer. It also discloses that this manufacturing method can provide a composite containing semiconductor nanoparticles with high fluorescence efficiency and stability.

[0008] However, when using the composite disclosed in Patent Document 2 as a wavelength conversion material, further improvements in fluorescence luminescence efficiency are needed. Furthermore, regarding stability, in addition to room temperature atmospheric conditions, it is also necessary to suppress the deterioration of fluorescence luminescence efficiency under high temperature and high humidity conditions.

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

[0010] According to the method in Patent Document 3, a glass composite exhibiting high fluorescence luminescence efficiency can be provided. However, the reaction time in this manufacturing method takes several days and uses a large amount of solvent and surfactant, thus posing technical problems that make it difficult to mass-produce or reduce costs.

[0011] Existing technical documents

[0012] Patent documents

[0013] Patent Document 1: Japanese Patent Application Publication No. 2012-022028

[0014] Patent Document 2: International Publication No. 2011 / 081037

[0015] Patent Document 3: Japanese Patent No. 4403270 Summary of the Invention

[0016] The technical problem to be solved by the present invention

[0017] This invention was implemented to solve the above-mentioned problems, and its object is to provide a method for efficiently manufacturing coated semiconductor nanoparticles in which the degradation of fluorescence luminescence efficiency is suppressed. Furthermore, this invention also provides coated semiconductor nanoparticles in which the degradation of fluorescence luminescence efficiency is suppressed.

[0018] Technical means to solve technical problems

[0019] This invention is implemented to achieve the above-mentioned objective. This invention provides a method for manufacturing coated semiconductor nanoparticles, which includes a step of coating the surface of the semiconductor nanoparticles with a metal oxide, wherein...

[0020] The metal oxide precursor is microwave irradiated to coat the surface of the semiconductor nanoparticles with the metal oxide.

[0021] If this method of manufacturing coated semiconductor nanoparticles is adopted, it is possible to efficiently manufacture coated semiconductor nanoparticles in which the degradation of fluorescence luminescence efficiency can be suppressed.

[0022] In this case, preferably, during the coating process, in the coexistence of the semiconductor nanoparticles and the metal oxide precursor, the metal oxide is coated onto the surface of the semiconductor nanoparticles by subjecting the coexisting metal oxide precursor to microwave irradiation treatment.

[0023] Therefore, metal oxides can be reliably coated onto semiconductor nanoparticles, enabling the more efficient production of coated semiconductor nanoparticles that further suppress the degradation of fluorescence luminescence efficiency.

[0024] In this case, preferably, the semiconductor nanoparticles used in the coating process are semiconductor nanoparticles comprising a semiconductor nanoparticle core and one or more semiconductor nanoparticle shells covering the semiconductor nanoparticle core.

[0025] This enables the efficient fabrication of semiconductor nanoparticles with excellent fluorescence luminescence properties and stability.

[0026] At this time, the semiconductor nanoparticle core used in the coating process can be a single one, 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.

[0027] These compounds are suitable for use in semiconductor nanoparticle cores due to their excellent fluorescence properties and stability. Based on these properties, ZnSe, ZnTe, CdSe, CdS, and InP are particularly preferred.

[0028] At this time, it is preferred that the semiconductor nanoparticle shell used in the coating process is a single one, multiple, alloy or mixed crystal selected from ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, and InSb.

[0029] Therefore, semiconductor nanoparticles with large band gaps and low lattice mismatches relative to the core material can be fabricated. From the perspective of improving fluorescence efficiency and stability, ZnSe, ZnS, CdSe, and CdS from these compounds are particularly preferred.

[0030] In this case, it is preferable to carry out the coating process in one or more solvents selected from polar solvents, non-polar solvents, and ionic liquids.

[0031] These solutions are suitable for use as dispersion media for semiconductor nanoparticles and metal oxide precursors.

[0032] In this case, it is preferable that the solvent used in the coating process is a solvent containing more than 90% of the non-polar solvent by volume.

[0033] Therefore, it is possible to more effectively suppress the degradation of fluorescence luminescence efficiency during coating.

[0034] At this time, it is preferred that the non-polar solvent used in the coating process is one or more solvents selected from toluene, hexane, cyclohexane, benzene, and diethyl ether.

[0035] These nonpolar solvents can further improve the dispersibility of semiconductor nanoparticles.

[0036] In this case, it is preferable that the metal oxide precursor used in the coating process is one or more selected from metal alkoxides, metal halides, and metal complexes.

[0037] These metal oxide precursors are highly reactive and suitable for coating the surface of semiconductor nanoparticles as metal oxides.

[0038] In this case, it is preferable to carry out the coating process in the presence of an alkaline aqueous solution.

[0039] Therefore, the thickness of the coating layer can be easily controlled.

[0040] In this case, it is preferable to perform the coating process in the presence of a surfactant.

[0041] Therefore, the metal oxide precursor exhibits excellent dispersibility.

[0042] In this case, it is preferable to carry out the coating process in the presence of alcohol.

[0043] As a result, the metal oxide precursor exhibits superior dispersibility.

[0044] Furthermore, the microwave irradiation treatment time in the coating process is preferably in the range of 3 to 30 minutes, and more preferably in the range of 5 to 15 minutes.

[0045] If the above processing time is used, the reduction in fluorescence luminescence efficiency can be effectively prevented.

[0046] Furthermore, it is preferable that the heating temperature of the microwave irradiation treatment in the coating process is in the range of 40 to 100°C, and more preferably in the range of 50 to 80°C.

[0047] Although the reaction temperature for microwave irradiation varies depending on the solvent, the above-mentioned temperature can more effectively prevent the degradation of fluorescence luminescence efficiency.

[0048] In this case, preferably, a step of modifying the surface of the semiconductor nanoparticles with a surface modifier is included before the coating step.

[0049] Therefore, by using surface modifiers to react the metal oxide precursor on the surface of semiconductor nanoparticles, the metal oxide can be coated onto the surface of semiconductor nanoparticles more efficiently, and the degradation of fluorescence luminescence efficiency can be suppressed during microwave irradiation treatment.

[0050] At this time, the surface modifier is preferably 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.

[0051] These compounds are suitable for use as surface modifiers.

[0052] Furthermore, the present invention provides a coated semiconductor nanoparticle, which is a semiconductor nanoparticle with a metal oxide coating on its surface, wherein...

[0053] The metal oxide is coated onto the surface of the semiconductor nanoparticles by microwave irradiation.

[0054] The degradation of fluorescence luminescence efficiency in this coated semiconductor nanoparticle was suppressed.

[0055] At this point, it is preferable to prepare a resin composition in which the coated semiconductor nanoparticles are dispersed in a resin.

[0056] This resin composition is one that suppresses the degradation of fluorescence luminescence efficiency.

[0057] At this point, it is preferable to prepare a wavelength conversion material using a cured resin composition.

[0058] If this wavelength conversion material is used, the reliability will be increased.

[0059] At this point, it is preferable to manufacture a light-emitting element using a wavelength conversion material.

[0060] If this type of light-emitting element is used, its reliability is particularly excellent.

[0061] Invention Effects

[0062] As described above, the method for manufacturing coated semiconductor nanoparticles according to the present invention can efficiently manufacture coated semiconductor nanoparticles in which the degradation of fluorescence luminescence efficiency is suppressed. Furthermore, the coated semiconductor nanoparticles of the present invention are coated semiconductor nanoparticles in which the degradation of fluorescence luminescence efficiency is suppressed. In addition, the coated semiconductor nanoparticles of the present invention are suitable for use in resin compositions, wavelength conversion materials using cured resin compositions, and light-emitting elements using wavelength conversion materials. Detailed Implementation

[0063] The embodiments of the present invention will be described below. However, in the present invention, the composition or preparation method of the semiconductor nanoparticles and metal oxides is not limited to the following embodiments.

[0064] As described above, there is a technical problem in efficiently manufacturing semiconductor nanoparticles that suppress the degradation of fluorescence luminescence efficiency. The inventors of this application have repeatedly and thoroughly studied this technical problem. As a result, it was discovered that a method for manufacturing coated semiconductor nanoparticles, which includes a process of coating the surface of semiconductor nanoparticles with metal oxide and performing the coating process by microwave irradiation, can efficiently manufacture coated semiconductor nanoparticles that suppress the degradation of fluorescence luminescence efficiency, thus completing this invention.

[0065] That is, the present invention is a method for manufacturing semiconductor nanoparticles coated with metal oxide, which includes the step of coating the surface of semiconductor nanoparticles with metal oxide, wherein the metal oxide is coated on the surface of semiconductor nanoparticles by subjecting a metal oxide precursor to microwave irradiation treatment.

[0066] The inventors of this application speculate the following mechanism for solving the above-mentioned technical problems.

[0067] For methods that use the stobol method or reverse micelle method to coat the surface of semiconductor nanoparticles with metal oxides, the semiconductor nanoparticles will coexist with water or oxygen for a long time. Therefore, oxidation reaction will occur on the particle surface or particle aggregation will occur due to ligand detachment, which will gradually degrade the fluorescence luminescence efficiency.

[0068] However, in methods utilizing microwave irradiation, the metal oxide precursor is selectively and directly heated from the inside, and a reaction occurs within a short time. Therefore, it can efficiently coat metal oxides under mild conditions, mitigating the detachment of ligands adsorbed on the surface of semiconductor nanoparticles (quantum dots) or surface oxidation reactions, thereby suppressing the degradation of fluorescence luminescence efficiency.

[0069] Therefore, by subjecting the metal oxide precursor to microwave irradiation, the metal oxide can be coated onto the surface of semiconductor nanoparticles, which can alleviate ligand detachment or surface oxidation reaction, thereby suppressing the deterioration of fluorescence luminescence efficiency.

[0070] The above mechanism is based on speculation only, and its correctness or incorrectness will not affect the technical scope of the present invention.

[0071] (Semiconductor nanoparticles)

[0072] The structure of the semiconductor nanoparticles in this invention is not particularly limited, but from the perspective of fluorescence emission characteristics and stability, core / shell structured semiconductor nanoparticles are preferred. That is, semiconductor nanoparticles comprising a semiconductor nanoparticle core and one or more semiconductor nanoparticle shells covering the semiconductor nanoparticle core are preferred. For core / shell structured semiconductor nanoparticles with a nanoscale semiconductor particle as the core and a semiconductor with a larger band gap and lower lattice mismatch as the shell, the fluorescence emission efficiency is increased because the excitons generated by the shell are confined inside the core particle, and the stability is increased because the core surface is covered by the shell.

[0073] The material of the semiconductor nanoparticle core of the core / shell semiconductor nanoparticle is not particularly limited. For example, it is preferred to use one or more, alloys or mixed crystals selected from group II-VI compounds, group III-V compounds, group I-III-VI compounds, group II-IV-V compounds.

[0074] Specific core materials include compounds such as 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. These compounds are suitable for use as semiconductor nanoparticle cores due to their excellent fluorescence properties and stability. From the perspective of fluorescence properties and stability, ZnSe, ZnTe, CdSe, CdS, and InP are particularly preferred among these compounds.

[0075] The material used as the shell for semiconductor nanoparticles is not particularly limited, but materials with a large band gap and low lattice mismatch relative to the core material are preferred. It is also preferred to use a single, multiple, alloy, or mixed crystal selected from group II-VI and group III-V compounds.

[0076] Specific shell compounds include ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, and InSb. These compounds can be used to create materials with large band gaps and low lattice mismatches relative to the core material. From the perspective of improving fluorescence efficiency and stability, ZnSe, ZnS, CdSe, and CdS are particularly preferred.

[0077] Various methods exist for manufacturing semiconductor nanoparticles, such as liquid-phase or gas-phase methods, but none are particularly limited in this invention. From the perspective of exhibiting high fluorescence luminescence efficiency, semiconductor nanoparticles obtained by hot soaping or hot-injection methods, in which the precursor seeds are reacted in a high-boiling-point nonpolar solvent at high temperature, are preferred.

[0078] Furthermore, to reduce surface defects, semiconductor nanoparticles preferably have organic ligands, known as ligands, coordinated on their surface. From the perspective of suppressing the aggregation of semiconductor nanoparticles, the 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, stearyl(octadecyl)amine, dodecyl(lauryl)amine, decylamine, octylamine, octadecanyl mercaptan, hexadecyl mercaptan, tetradecyl mercaptan, dodecyl mercaptan, decyl mercaptan, octyl mercaptan, trioctylphosphine, trioctylphosphine oxide, triphenylphosphine, triphenylphosphine oxide, tributylphosphine, and tributylphosphine oxide. These ligands can be used alone or in combination.

[0079] (Coated semiconductor nanoparticles)

[0080] The method for manufacturing coated semiconductor nanoparticles of the present invention involves coating the surface of semiconductor nanoparticles with metal oxide by subjecting a metal oxide precursor to microwave irradiation. By using microwaves, the metal oxide precursor is heated directly from the inside, allowing for selective coating in a shorter time.

[0081] Here, "microwave" refers to electromagnetic waves that typically have a frequency of 300 MHz to 3 THz. Furthermore, methods of microwave irradiation include, for example, using the flexi wave manufactured by Milestone, but there are no particular limitations.

[0082] Furthermore, in this invention, silicon oxide is included within a metal oxide.

[0083] The "coating" of the metal oxide on the surface of the semiconductor particles in the manufacturing method of the coated semiconductor nanoparticles of the present invention can be either partial or complete. Furthermore, the coating layer can be a uniform core-shell structure, an uneven coating layer, or a structure in which multiple semiconductor nanoparticles are coated with metal oxide. The thickness of the metal oxide film is not particularly limited, but from the perspective of light transmittance, it is preferably 100 nm or less.

[0084] In this case, preferably, during the coating process, in the presence of both semiconductor nanoparticles and a metal oxide precursor, the metal oxide precursor is microwave-irradiated to coat the surface of the semiconductor nanoparticles. This reliably coats the semiconductor nanoparticles with metal oxide, enabling more efficient fabrication of coated semiconductor nanoparticles where degradation of fluorescence luminescence efficiency is further suppressed.

[0085] In this case, it is preferable that the dispersion medium for the semiconductor nanoparticles and metal oxide precursors in the coating process is selected from one or more of polar solvents, non-polar solvents, and ionic liquids, and the coating is carried out in such solvents. These solvents are suitable for use as dispersion media for the semiconductor nanoparticles and metal oxide precursors.

[0086] At this point, the proportion of non-polar solvent in the solvent is preferably 90% or more by volume. Using such a solvent can suppress the deterioration of fluorescence efficiency during coating.

[0087] Furthermore, it is preferable that the non-polar solvent used in the coating process is one or more solvents selected from toluene, hexane, cyclohexane, benzene, and diethyl ether. These non-polar solvents can further improve the dispersibility of semiconductor nanoparticles. In addition, when the solvent is non-polar, a microwave-absorbing heating element called WEFLON can be used arbitrarily during the coating process.

[0088] There are no particular limitations on the metal oxide precursors used, but one or more selected from metal alkoxides, metal halides, and metal complexes are preferred. These metal oxide precursors are highly reactive and suitable for coating the surface of semiconductor nanoparticles as metal oxides.

[0089] Compounds that are metal alkoxides include methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, isopropyl orthosilicate, butyl orthosilicate, tetra(2-ethylhexyloxy)silane, trimethoxysilane, triethoxysilane, (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, (3-mercaptopropyl)trimethoxysilane, (3-mercaptopropyl)triethoxysilane, ethyl titanate, tetraisopropyl titanate, tetrabutyl titanate, tetra(2-ethylhexyl) titanate, zinc isopropoxide, zinc tert-butoxy, zirconium ethoxide, zirconium propoxide, zirconium butoxide, aluminum triethanolamine, aluminum isopropoxide, aluminum tert-butoxide, aluminum sec-butoxide, yttrium isopropoxide, hafnium ethoxide, hafnium tert-butoxide, iron ethoxide, and iron isopropoxide.

[0090] In addition, as metal halide compounds, examples 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.

[0091] In addition, as metal complex compounds, examples include aluminum acetylacetone, titanium acetylacetone, iron (III) acetylacetone, zinc acetylacetone, and zirconium acetylacetone.

[0092] From a stability perspective, silanols, aluminum alkoxides, zirconium alkoxides, and titanium alkoxides are preferred as metal oxide precursors. The mixing ratio (by weight) of semiconductor nanoparticles to metal oxide precursors is preferably 1:0.4 to 1:3.

[0093] At this point, it is preferable to use a catalyst during the coating process to promote the reaction of the metal oxide precursor. Particularly when using metal alkoxides, it is preferable to use a catalyst to promote the sol-gel reaction. Examples of catalysts include acidic or alkaline aqueous solutions; alkaline aqueous solutions are particularly preferred from the perspective of the coating thickness. 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.

[0094] Furthermore, when performing the coating process, surfactants are preferred from the perspective of dispersibility of the metal oxide precursor. Surfactants are not particularly limited; examples include quaternary ammonium salts such as hexadecyltrimethylammonium bromide as cationic surfactants, carboxylates or sulfonates as anionic surfactants, and polyoxyethylene alkyl ethers as nonionic surfactants. Cationic surfactants are particularly preferred from the perspective of dispersibility of the metal oxide precursor. Surfactants can be added directly or dissolved in a polar solvent such as an alcohol (described later) to prepare a solution before addition.

[0095] Furthermore, the coating process is preferably performed in the presence of an alcohol. When coating is performed in the presence of an alcohol, the dispersibility of the metal oxide precursor is better. In addition, when a surfactant is added, the dispersibility can be further improved by dissolving it in a polar solvent such as an alcohol.

[0096] Furthermore, it is preferable to include a process of modifying the surface of the semiconductor nanoparticles with a surface modifier before the coating process. Through this modification process, the metal oxide precursor reacts on the surface of the semiconductor nanoparticles via the surface modifier, thereby enabling the metal oxide layer to be coated on the surface of the semiconductor nanoparticles more efficiently and suppressing the degradation of fluorescence luminescence efficiency during microwave irradiation treatment.

[0097] The preferred surface modifier is a compound that contains, at one end of the molecule, a substituent such as an SH group or an NH2 group as a substituent adsorbed onto the surface of semiconductor nanocrystal particles, and at the other end, a -Si(OR)3 group (R: an alkyl group with 4 or fewer carbon atoms), an OH group, or a COOH group as a substituent reacting 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. One or more of these surface modifiers can be used alone. The atmosphere in which the modification is performed using the surface modifier is not particularly limited; for example, it can be performed under an inert gas atmosphere such as nitrogen.

[0098] At this time, although the reaction temperature in microwave irradiation treatment varies depending on the solvent, from the perspective of preventing the deterioration of fluorescence luminescence efficiency, it is preferably 40 to 100°C, and more preferably 50 to 80°C.

[0099] Furthermore, from the perspective of preventing a decrease in fluorescence luminescence efficiency, the processing time in microwave irradiation is preferably 3 to 30 minutes, more preferably 5 to 15 minutes.

[0100] Furthermore, the present invention provides a coated semiconductor nanoparticle, which is a semiconductor nanoparticle with a metal oxide coating on its surface, wherein...

[0101] The metal oxide is coated onto the surface of the semiconductor nanoparticles by microwave irradiation.

[0102] The semiconductor nanoparticles of the present invention are particles formed by microwave treatment of metal oxides to coat the surface of semiconductor nanoparticles. The degradation of fluorescence luminescence efficiency in these coated semiconductor nanoparticles of the present invention is suppressed. Examples of semiconductor nanoparticles and metal oxides include, for example, the semiconductor nanoparticles and metal oxides described above.

[0103] The microwave irradiation coating of this invention refers to coating the surface of semiconductor nanoparticles with a metal oxide that has been irradiated by microwaves. The microwave is as described above.

[0104] Furthermore, it is preferable to use it as a resin composition in which the aforementioned coated semiconductor nanoparticles are dispersed in a resin. This allows for the production of a resin composition in which the degradation of fluorescence luminescence efficiency is suppressed.

[0105] The resin material is not particularly limited, but it is preferred to use a resin material that does not cause aggregation of semiconductor nanoparticles or deterioration of fluorescence efficiency. Examples include silicone resins, acrylic resins, epoxy resins, urethane resins, and fluororesins. In order to improve fluorescence efficiency as a wavelength conversion material, these materials are preferably those with high transmittance, and particularly preferably those with a transmittance of 80% or more.

[0106] Furthermore, it is preferable to use a wavelength conversion material that is a cured product of the aforementioned resin composition. Using such a wavelength conversion material increases reliability. The wavelength conversion material can be used directly or after processing. For example, one possible approach is a wavelength conversion film in which a composite is dispersed in a resin after processing into a sheet and then curing.

[0107] There are no particular limitations on the method of fabricating wavelength conversion materials. For example, wavelength conversion materials can be obtained by coating a resin composition in which semiconductor nanoparticles are dispersed in a resin onto a transparent film such as PET or polyimide, curing it, and then performing a lamination process.

[0108] The transparent film can be coated using spraying or inkjet methods, spin coating or rod coating, or doctor blade coating to form a resin layer. Furthermore, there are no particular limitations on the thickness of the resin layer and the transparent film; they can be selected appropriately based on the intended application.

[0109] There is no particular limitation on the method for curing the resin composition. For example, it can be carried out by heating a film coated with the resin composition at 60°C for 2 hours and then heating it at 150°C for 4 hours.

[0110] Furthermore, it is preferable to use it as a light-emitting element employing the aforementioned wavelength conversion material. The light-emitting element is not particularly limited, and examples include light-emitting diodes (LEDs). If the light-emitting element uses the aforementioned wavelength conversion material, its reliability is particularly excellent.

[0111] Example

[0112] The present invention will now be specifically described using examples and comparative examples, but the present invention is not limited thereto.

[0113] (Evaluation of luminescent properties)

[0114] 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 OTSUKAELECTRONICS CO.,LTD.

[0115] (Manufacturing of semiconductor nanoparticles)

[0116] (Manufacturing Example 1)

[0117] 0.070 g indium acetate (0.24 mmol), 0.256 g (0.72 mmol) 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, degassing for 1 hour while dissolving. After cooling the flask to room temperature, nitrogen was purged. 0.50 mL (0.17 mmol) of a 10 vol% tris(trimethylsilyl)phosphine / octadecene solution was added to the flask. The flask was then heated to 300 °C and stirred for 20 minutes to synthesize InP semiconductor core particles.

[0118] 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. Further, 0.60 mL (0.90 mmol) of 1.5 M selenium / trioctylphosphine solution was added to the flask and stirred for 30 minutes. Then, 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 (dodecyl mercaptan) was added and stirred for 30 minutes.

[0119] The obtained solution was cooled to room temperature, and ethanol was added. Centrifugation was then performed to precipitate the semiconductor nanoparticles, and the supernatant was removed. Toluene was further added to the precipitate to disperse it, and ethanol was added again, followed by centrifugation to remove the supernatant. The precipitate was then dispersed again in toluene, thereby preparing an InP / ZnSe / ZnS semiconductor nanoparticle toluene solution. The fluorescence efficiency of the solution was 76%.

[0120] (Manufacturing Example 2)

[0121] 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 was purged. Then, 0.50 mL (0.17 mmol) of a 10 vol% tris(trimethylsilyl)phosphine / 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.

[0122] 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. Further, 0.60 mL (0.90 mmol) of 1.5 M selenium / trioctylphosphine solution was added to the flask and stirred for 30 minutes. Then, 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 for 1 hour to dissolve the zinc. 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. Further, 0.70 mL (3.0 mmol) of (3-aminopropyl)triethoxysilane was added to the flask and stirred for 30 minutes.

[0123] The obtained solution was cooled to room temperature, and ethanol was added. Centrifugation was then performed to precipitate the semiconductor nanoparticles, and the supernatant was removed. Toluene was further added to the precipitate to disperse it, and ethanol was added again, followed by centrifugation. The supernatant was removed, and the precipitate was redispersed in toluene, thereby preparing an InP / ZnSe / ZnS semiconductor nanoparticle toluene solution. The fluorescence efficiency of the solution was 75%.

[0124] (Manufacturing Example 3)

[0125] 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 was purged. Then, 0.50 mL (0.17 mmol) of a 10 vol% tris(trimethylsilyl)phosphine / 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.

[0126] Then, 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. Next, 0.60 mL (0.90 mmol) of 1.5 M selenium / trioctylphosphine solution was added to the flask and stirred for 30 minutes. 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 for 1 hour to dissolve the zinc. 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. Next, 0.72 mL (3.0 mmol) of (3-mercaptopropyl)triethoxysilane was added to the flask and stirred for 30 minutes.

[0127] The obtained solution was cooled to room temperature, and ethanol was added. Centrifugation was then performed to precipitate the semiconductor nanoparticles, and the supernatant was removed. Toluene was further added to the precipitate to disperse it, and ethanol was added again, followed by centrifugation. The supernatant was removed, and the precipitate was redispersed in toluene, thereby preparing an InP / ZnSe / ZnS semiconductor nanoparticle toluene solution. The fluorescence efficiency of the solution was 74%.

[0128] (Manufacturing Example 4)

[0129] 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 was purged. Then, 0.50 mL (0.17 mmol) of a 10 vol% tris(trimethylsilyl)phosphine / 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.

[0130] 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. Further, 0.60 mL (0.90 mmol) of 1.5 M selenium / trioctylphosphine solution was added to the flask and stirred for 30 minutes. Then, 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. Further, 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 stirred for 30 minutes.

[0131] The obtained solution was cooled to room temperature, and ethanol was added. Centrifugation was then performed to precipitate the semiconductor nanoparticles, and the supernatant was removed. Toluene was further added to the precipitate to disperse it, and ethanol was added again, followed by centrifugation. The supernatant was removed, and the precipitate was redispersed in toluene, thereby preparing an InP / ZnSe / ZnS semiconductor nanoparticle toluene solution. The fluorescence efficiency of the solution was 74%.

[0132] The manufacturing examples 1 to 4 above are summarized in Table 1.

[0133] [Table 1]

[0134]

[0135] (Manufacturing of semiconductor nanoparticles)

[0136] 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 (flexiWAVE manufactured by Milestone General KK).

[0137] (Example 1)

[0138] 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle solution obtained in Example 1, along with 100 μL of tetraethyl orthosilicate and 50 μL of a 25% ammonia (NH3) aqueous solution, was mixed and 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: H2O (molar ratio) = 1:4.6. Then, using the aforementioned microwave synthesis apparatus, metal oxide coating was performed by heating at 2450 MHz and 60 °C for 10 minutes. The resulting coated semiconductor nanoparticles were settled by centrifugation, and the supernatant was removed. They were then redispersed by adding toluene and ultrasonic irradiation. The resulting coated semiconductor nanoparticles exhibited a fluorescence efficiency of 72%, representing a 5.3% reduction in fluorescence efficiency compared to the initial coating process.

[0139] (Example 2)

[0140] 10 g of a 1.0 wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Manufacturing Example 1, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and 0.010 g of cetyltrimethylammonium bromide were mixed and 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: H2O (molar ratio) = 1:4.6. Then, using the aforementioned microwave synthesis apparatus, metal oxide coating was performed by heating at 60°C for 10 minutes at 2450 MHz. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, and the supernatant was removed. They were then redispersed by adding toluene and ultrasonic irradiation. The resulting coated semiconductor nanoparticles exhibited a fluorescence efficiency of 70%, representing a 7.9% reduction in fluorescence efficiency compared to the initial coating process.

[0141] (Example 3)

[0142] A mixture of 10g of a 1.0wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Preparation Example 1, 100μL of tetraethyl orthosilicate, 50μL of a 25% ammonia solution, and a 0.010g / 100μL solution of hexadecyltrimethylammonium bromide / ethanol was 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: H2O (molar ratio) = 1:4.6. The metal oxide coating was then performed using the aforementioned microwave synthesis apparatus at 2450MHz and 60°C for 10 minutes. The coated semiconductor nanoparticles were settled by centrifugation, and the supernatant was removed. The nanoparticles were then redispersed by adding toluene and subjecting the nanoparticles to ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 70%, which is a reduction of 7.9% compared to the fluorescence efficiency before the coating process.

[0143] (Example 4)

[0144] A mixture of 10g of a 1.0wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Manufacturing Example 1, 0.092g of aluminum isopropoxide, 50μL of a 25% ammonia solution, and a cetyltrimethylammonium bromide / ethanol solution of 0.010g / 100μL was added to a high-pressure reaction vessel. The mixing ratios were: semiconductor nanoparticles:aluminum isopropoxide (weight ratio) = 1:0.92, NH3:aluminum isopropoxide (molar ratio) = 1:0.89, and aluminum isopropoxide:H2O (molar ratio) = 1:4.6. The metal oxide coating was then performed using the aforementioned microwave synthesis apparatus at 2450MHz and 60°C for 10 minutes. The coated semiconductor nanoparticles were centrifuged to allow sedimentation, and the supernatant was removed. The nanoparticles were then redispersed by adding toluene and ultrasonic irradiation. The resulting coated semiconductor nanoparticles exhibited a fluorescence efficiency of 68%, representing a 10.5% reduction in fluorescence efficiency compared to the initial coating step.

[0145] (Example 5)

[0146] A mixture of 10 g of a 1.0 wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Preparation Example 1, 0.153 g of tetrabutyl titanate, 50 μL of a 25% ammonia solution, and a 0.010 g / 100 μL solution of hexadecyltrimethylammonium bromide / ethanol was added to a high-pressure reaction vessel. The mixing ratios were: semiconductor nanoparticles:tetrabutyl titanate (weight ratio) = 1:1.5, NH3:tetrabutyl titanate (molar ratio) = 1:0.89, and tetrabutyl titanate:H2O (molar ratio) = 1:4.6. The metal oxide coating was then performed using the aforementioned microwave synthesis apparatus at 2450 MHz and 60 °C for 10 minutes. The coated semiconductor nanoparticles were settled by centrifugation, and the supernatant was removed. The nanoparticles were then redispersed by adding toluene and ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 65%, which is 14.5% lower than the fluorescence efficiency before the coating process.

[0147] (Example 6)

[0148] A mixture of 10g of a 1.0wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Manufacturing Example 1, 0.147g of zirconium propoxide, 50μL of a 25% ammonia solution, and a cetyltrimethylammonium bromide / ethanol solution of 0.010g / 100μL was added to a high-pressure reaction vessel. The mixing ratios were: semiconductor nanoparticles:zirconium propoxide (weight ratio) = 1:1.5, NH3:zirconium propoxide (molar ratio) = 1:0.89, and zirconium propoxide:H2O (molar ratio) = 1:4.6. The metal oxide coating was then performed using the aforementioned microwave synthesis apparatus at 2450MHz and 60°C for 10 minutes. The coated semiconductor nanoparticles were centrifuged to allow sedimentation, and the supernatant was removed. They were then redispersed by adding toluene and ultrasonic irradiation. The resulting coated semiconductor nanoparticles exhibited a fluorescence efficiency of 67%, representing an 11.8% reduction in fluorescence efficiency compared to the initial coating process.

[0149] (Example 7)

[0150] 10 g of a 1.0 wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Preparation Example 1, 50 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and a 0.010 g / 100 μL solution of hexadecyltrimethylammonium bromide / ethanol were mixed and added to a high-pressure reaction vessel. The mixing ratios were: semiconductor nanoparticles: tetraethyl orthosilicate (weight ratio) = 1:0.47, NH3: tetraethyl orthosilicate (molar ratio) = 1:0.89, and tetraethyl orthosilicate: H2O (molar ratio) = 1:4.6. Then, using the aforementioned microwave synthesis apparatus, metal oxide coating was performed by heating at 60 °C for 10 minutes at 2450 MHz. The coated semiconductor nanoparticles were precipitated by centrifugation, and the supernatant was removed. They were then redispersed by adding toluene and subjecting the nanoparticles to ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 73%, which is 3.9% lower than the fluorescence efficiency before the coating process.

[0151] (Example 8)

[0152] A 1.0 wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Manufacturing Example 1, 200 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and a 0.010 g / 100 μL solution of hexadecyltrimethylammonium bromide / ethanol were mixed and 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: H2O (molar ratio) = 1:4.6. The metal oxide coating was then performed using the aforementioned microwave synthesis apparatus at 2450 MHz and 60 °C for 10 minutes. The coated semiconductor nanoparticles were settled by centrifugation, and the supernatant was removed. They were then redispersed by adding toluene and subjecting the nanoparticles to ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 70%, which is a reduction of 7.9% compared to the fluorescence efficiency before the coating process.

[0153] (Example 9)

[0154] 10 g of a 1.0 wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Preparation Example 1, 300 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and a 0.010 g / 100 μL solution of hexadecyltrimethylammonium bromide / ethanol were mixed and 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: H2O (molar ratio) = 1:4.6. The metal oxide coating was then performed using the aforementioned microwave synthesis apparatus at 2450 MHz and 60 °C for 10 minutes. The coated semiconductor nanoparticles were precipitated by centrifugation, and the supernatant was removed. The nanoparticles were then redispersed by adding toluene and ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 68%, which is 10.5% lower than the fluorescence efficiency before the coating process.

[0155] (Example 10)

[0156] 10 g of a 1.0 wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Preparation Example 1, 100 μL of tetraethyl orthosilicate, 25 μL of a 25% ammonia solution, and a 0.010 g / 100 μL solution of hexadecyltrimethylammonium bromide / ethanol were mixed and 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: H2O (molar ratio) = 1:2.3. Then, using the aforementioned microwave synthesis apparatus, metal oxide coating was performed by heating at 60 °C for 10 minutes at 2450 MHz. The coated semiconductor nanoparticles were precipitated by centrifugation, and the supernatant was removed. They were then redispersed by adding toluene and ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 73%, which is 3.9% lower than the fluorescence efficiency before the coating process.

[0157] (Example 11)

[0158] 10g of a 1.0wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Manufacturing Example 1, 100μL of tetraethyl orthosilicate, 100μL of a 25% ammonia solution, and a 0.010g / 100μL solution of hexadecyltrimethylammonium bromide / ethanol were mixed and 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: H2O (molar ratio) = 1:9.2. Then, using the aforementioned microwave synthesis apparatus, metal oxide coating was performed by heating at 60°C for 10 minutes at 2450MHz. The coated semiconductor nanoparticles were precipitated by centrifugation, and the supernatant was removed. They were then redispersed by adding toluene and subjecting the nanoparticles to ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 68%, which is 10.5% lower than the fluorescence efficiency before the coating process.

[0159] (Example 12)

[0160] 10 g of a 1.0 wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Preparation Example 1, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and a 0.010 g / 100 μL solution of hexadecyltrimethylammonium bromide / ethanol were mixed and added to a high-pressure reaction vessel. 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: H2O (molar ratio) = 1:4.6. Then, using the above-described microwave synthesis apparatus, metal oxide coating was performed by heating at 40 °C for 10 minutes at 2450 MHz. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, and the supernatant was removed. They were then redispersed by adding toluene and performing ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 73%, which is 3.9% lower than the fluorescence efficiency before the coating process.

[0161] (Example 13)

[0162] A mixture of 10g of a 1.0wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Manufacturing Example 1, 100μL of tetraethyl orthosilicate, 50μL of a 25% ammonia solution, and a 0.010g / 100μL solution of hexadecyltrimethylammonium bromide / ethanol was added to a high-pressure reaction vessel. The metal oxide coating was then performed using the aforementioned microwave synthesis apparatus at 2450MHz and 50°C for 10 minutes. The resulting coated semiconductor nanoparticles were settled by centrifugation, and the supernatant was removed. They were then redispersed by adding toluene and ultrasonic irradiation. The resulting coated semiconductor nanoparticles exhibited a fluorescence efficiency of 72%, representing a 5.3% reduction in fluorescence efficiency compared to the initial coating step.

[0163] (Example 14)

[0164] A mixture of 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Preparation Example 1, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and a 0.010 g / 100 μL solution of hexadecyltrimethylammonium bromide / ethanol was 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: H2O (molar ratio) = 1:4.6. The metal oxide coating was then performed using the aforementioned microwave synthesis apparatus at 2450 MHz and 80 °C for 10 minutes. The coated semiconductor nanoparticles were precipitated by centrifugation, and the supernatant was removed. The nanoparticles were then redispersed by adding toluene and ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 67%, which is 11.8% lower than the fluorescence efficiency before the coating process.

[0165] (Example 15)

[0166] 10 g of a 1.0 wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Preparation Example 1, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and a 0.010 g / 100 μL solution of hexadecyltrimethylammonium bromide / ethanol were mixed and 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: H2O (molar ratio) = 1:4.6. Then, using the aforementioned microwave synthesis apparatus, metal oxide coating was performed by heating at 100 °C for 10 minutes at 2450 MHz. The resulting coated semiconductor nanoparticles were precipitated by centrifugation, and the supernatant was removed. They were then redispersed by adding toluene and ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 62%, which is 18.4% lower than the fluorescence efficiency before the coating process.

[0167] (Example 16)

[0168] A mixture of 10g of a 1.0wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Preparation Example 1, 100μL of tetraethyl orthosilicate, 50μL of a 25% ammonia solution, and a 0.010g / 100μL solution of hexadecyltrimethylammonium bromide / ethanol was 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: H2O (molar ratio) = 1:4.6. The metal oxide coating was then performed using the aforementioned microwave synthesis apparatus at 2450MHz and 60°C for 3 minutes. The coated semiconductor nanoparticles were settled by centrifugation, and the supernatant was removed. The nanoparticles were then redispersed by adding toluene and ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 73%, which is 3.9% lower than the fluorescence efficiency before the coating process.

[0169] (Example 17)

[0170] A mixture of 10g of a 1.0wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Preparation Example 1, 100μL of tetraethyl orthosilicate, 50μL of a 25% ammonia solution, and a 0.010g / 100μL solution of hexadecyltrimethylammonium bromide / ethanol was 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: H2O (molar ratio) = 1:4.6. The metal oxide coating was then performed using the aforementioned microwave synthesis apparatus at 2450MHz and 60°C for 5 minutes. The coated semiconductor nanoparticles were settled by centrifugation, and the supernatant was removed. The nanoparticles were then redispersed by adding toluene and ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 73%, which is 3.9% lower than the fluorescence efficiency before the coating process.

[0171] (Example 18)

[0172] A mixture of 10 g of a 1.0 wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Preparation Example 1, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and a 0.010 g / 100 μL solution of hexadecyltrimethylammonium bromide / ethanol was 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: H2O (molar ratio) = 1:4.6. The metal oxide coating was then performed using the microwave synthesis apparatus described above, heated at 2450 MHz and 60 °C for 15 minutes. The coated semiconductor nanoparticles were settled by centrifugation, and the supernatant was removed. The nanoparticles were then redispersed by adding toluene and ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 70%, which is a reduction of 7.9% compared to the fluorescence efficiency before the coating process.

[0173] (Example 19)

[0174] A mixture of 10g of a 1.0wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Preparation Example 1, 100μL of tetraethyl orthosilicate, 50μL of a 25% ammonia solution, and a 0.010g / 100μL solution of hexadecyltrimethylammonium bromide / ethanol was added to a high-pressure reaction vessel. The metal oxide coating was then performed using the aforementioned microwave synthesis apparatus at 2450MHz and 60°C for 20 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: H2O (molar ratio) = 1:4.6. The coated semiconductor nanoparticles were centrifuged to allow sedimentation, and the supernatant was removed. The nanoparticles were then redispersed by adding toluene and subjecting the nanoparticles to ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 69%, which is 9.2% lower than the fluorescence efficiency before the coating process.

[0175] (Example 20)

[0176] A mixture of 10g of a 1.0wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Preparation Example 1, 100μL of tetraethyl orthosilicate, 50μL of a 25% ammonia solution, and a 0.010g / 100μL solution of hexadecyltrimethylammonium bromide / ethanol was added to a high-pressure reaction vessel. The metal oxide coating was then performed using the aforementioned microwave synthesis apparatus at 2450MHz and 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: H2O (molar ratio) = 1:4.6. The coated semiconductor nanoparticles were settled by centrifugation, and the supernatant was removed. The nanoparticles were then redispersed by adding toluene and subjecting the nanoparticles to ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 67%, which is 11.8% lower than the fluorescence efficiency before the coating process.

[0177] (Example 21)

[0178] A mixture of 10g of a 1.0wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Manufacturing Example 2, 100μL of tetraethyl orthosilicate, 50μL of a 25% ammonia solution, and a 0.010g / 100μL solution of hexadecyltrimethylammonium bromide / ethanol was 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: H2O (molar ratio) = 1:4.6. The metal oxide coating was then performed using the aforementioned microwave synthesis apparatus at 2450MHz and 60°C for 10 minutes. The coated semiconductor nanoparticles were settled by centrifugation, and the supernatant was removed. The nanoparticles were then redispersed by adding toluene and ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 74%, which is 1.3% lower than the fluorescence efficiency before the coating process.

[0179] (Example 22)

[0180] A mixture of 10 g of a 1.0 wt% InP / ZnSe / ZnS semiconductor nanoparticle toluene solution obtained in Preparation Example 3, 100 μL of tetraethyl orthosilicate, 50 μL of a 25% ammonia solution, and a 0.010 g / 100 μL solution of hexadecyltrimethylammonium bromide / ethanol was 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: H2O (molar ratio) = 1:4.6. The metal oxide coating was then performed using the aforementioned microwave synthesis apparatus at 2450 MHz and 60 °C for 10 minutes. The coated semiconductor nanoparticles were settled by centrifugation, and the supernatant was removed. The nanoparticles were then redispersed by adding toluene and ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 73%, which is 1.4% lower than the fluorescence efficiency before the coating process.

[0181] (Example 23)

[0182] A mixture of 10g of a 1.0wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Preparation Example 4, 100μL of tetraethyl orthosilicate, 50μL of a 25% ammonia solution, and a 0.010g / 100μL solution of hexadecyltrimethylammonium bromide / ethanol was 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: H2O (molar ratio) = 1:4.6. The metal oxide coating was then performed using the aforementioned microwave synthesis apparatus at 2450MHz and 60°C for 10 minutes. The coated semiconductor nanoparticles were settled by centrifugation, and the supernatant was removed. The nanoparticles were then redispersed by adding toluene and ultrasonic irradiation. The obtained coated semiconductor nanoparticles have a fluorescence efficiency of 74%, which is 1.3% lower than the fluorescence efficiency before the coating process.

[0183] The manufacturing methods of Examples 1 to 23 are summarized in Table 2.

[0184] [Table 2]

[0185]

[0186] (Comparative Example 1)

[0187] A mixture of 10g of a 1.0wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Manufacturing Example 1, 100μL of tetraethyl orthosilicate, 50μL of a 25% ammonia solution, and a 0.010g / 100μL solution of hexadecyltrimethylammonium bromide / ethanol was added to a flask. The metal oxide coating was then performed by heating at 60°C and stirring for 6 hours using a mantle heater. The coated semiconductor nanoparticles were settled by centrifugation, and the supernatant was removed. They were then redispersed by adding toluene and ultrasonic irradiation. The resulting coated semiconductor nanoparticles exhibited a fluorescence efficiency of 56%, representing a 35.7% reduction in fluorescence efficiency compared to the method before coating. This confirmed a significant decrease in fluorescence efficiency compared to the method using microwave irradiation.

[0188] (Comparative Example 2)

[0189] After adding 50 mL of cyclohexane, 1.2 g of polyoxyethylene (5) nonylphenyl ether (IGEPAL-CO520 manufactured by Roadia Co., Ltd.), and 100 μL of tetraethyl orthosilicate, 5 g of a 2.0 wt% toluene solution of InP / ZnSe / ZnS semiconductor nanoparticles obtained in Manufacturing Example 1 was added, and the mixture was stirred at room temperature (25°C). While stirring, 1 mL of a 10% ammonia solution was gradually added in small amounts, and the mixture was stirred for 48 hours to perform metal oxide coating. The coated semiconductor nanoparticles were centrifuged to allow them to settle, and the supernatant was removed. They were then redispersed by adding toluene and subjecting the nanoparticles to ultrasonic irradiation. The fluorescence efficiency of the resulting coated semiconductor nanoparticles was 26%, representing a 65.8% reduction compared to the fluorescence efficiency before the coating process. This confirmed a significant decrease in fluorescence efficiency compared to the manufacturing method using microwave irradiation.

[0190] As described above, when Comparative Example 1 used a covered resistance heater instead of microwave irradiation for heating, it not only required a longer time but also resulted in a significant decrease in fluorescence luminescence efficiency. Furthermore, in Comparative Example 2, it required 48 hours at room temperature, which was not only longer than that of Comparative Example 1 but also resulted in an even more significant decrease in fluorescence luminescence efficiency compared to Comparative Example 1.

[0191] On the other hand, in Examples 1 to 23, which are embodiments of the method for manufacturing coated semiconductor nanoparticles of the present invention, it was confirmed that by using microwave irradiation treatment to coat the surface of semiconductor nanoparticles with metal oxide in a short time, the degradation of fluorescence luminescence efficiency in the coating process was suppressed, and coated semiconductor nanoparticles exhibiting high fluorescence luminescence efficiency could be efficiently manufactured.

[0192] (Manufacturing method of wavelength conversion materials)

[0193] Wavelength conversion materials were prepared using the coated semiconductor nanoparticles obtained in Examples 1-23, Comparative Examples 1 and 2, and particles used directly without coating the semiconductor nanoparticles obtained in Manufacturing Example 1 (Comparative Example 3). 1.0 g of the aforementioned semiconductor nanoparticles or a 1.0 wt% toluene solution coating semiconductor nanoparticles was mixed with 10.0 g of silicone resin (LPS-5547 manufactured by Shin-Etsu Chemical Co., Ltd.). The mixture was heated at 60°C while stirring, and the solvent was removed under reduced pressure. Then, vacuum degassing was performed, and the mixture was coated onto a 50 μm thick polyethylene terephthalate (PET) film. A 100 μm thick semiconductor nanoparticle resin layer was formed using a rod coater. The PET film was then laminated onto this resin layer. The film was heated at 60°C for 2 hours and then at 150°C for 4 hours to cure the semiconductor nanoparticle resin layer, thus preparing the wavelength conversion material.

[0194] The obtained wavelength conversion material was treated at 85℃ and 85%RH (relative humidity) for 100 hours, and the fluorescence efficiency of the treated wavelength conversion material was measured to evaluate its reliability. The fluorescence efficiency after fabrication of the wavelength conversion material and the fluorescence efficiency after reliability evaluation are shown in Table 3.

[0195] [Table 3]

[0196]

[0197] According to the results in Table 3, the fluorescence luminescence efficiency of the wavelength conversion materials after reliability evaluation was 17% for Comparative Example 1, 9% for Comparative Example 2, and 17% for Comparative Example 3. Moreover, the fluorescence luminescence efficiency after reliability evaluation was less than 20% in all comparative examples.

[0198] However, the fluorescence luminescence efficiency of the coated semiconductor nanoparticles (Examples 1-23) manufactured by the method of the present invention after reliability evaluation is all above 20%. As shown above, it has been confirmed that the coated semiconductor nanoparticles manufactured by the method of the present invention exhibit high stability, and the wavelength conversion material using the coated semiconductor nanoparticles can suppress the degradation of fluorescence luminescence efficiency under high temperature and high humidity conditions, demonstrating high reliability. Therefore, it can be seen that the physical properties of the coated semiconductor nanoparticles manufactured by the method of the present invention are superior to those of conventional products, and significantly different from existing products.

[0199] Furthermore, this invention is not limited to the above-described embodiments. The above embodiments are examples, and any technical solutions having substantially the same structure and achieving the same technical effect as the technical concept described in the claims of this invention are included within the technical scope of this invention.

Claims

1. A method for manufacturing coated semiconductor nanoparticles, comprising the step of coating the surface of semiconductor nanoparticles with metal oxide, characterized in that, The semiconductor nanoparticles used in the coating process are semiconductor nanoparticles comprising a semiconductor nanoparticle core and one or more semiconductor nanoparticle shells covering the semiconductor nanoparticle core. The semiconductor nanoparticle core is InP, and the semiconductor nanoparticle shell is ZnS or ZnSe; therefore, the semiconductor nanoparticles are InP / ZnSe / ZnS. The metal oxide precursor is coated onto the surface of the semiconductor nanoparticles by microwave irradiation. The metal in the metal oxide is any one of zinc (Zn), iron (Fe), yttrium (Y), aluminum (Al), zirconium (Zr), titanium (Ti), and hafnium (Hf).

2. The method for manufacturing coated semiconductor nanoparticles according to claim 1, characterized in that, In the coating process, with the semiconductor nanoparticles and the metal oxide precursor coexisting, the metal oxide is coated onto the surface of the semiconductor nanoparticles by subjecting the coexisting metal oxide precursor to microwave irradiation treatment.

3. The method for manufacturing coated semiconductor nanoparticles according to claim 1, characterized in that, The coating process is carried out in one or more solvents selected from polar solvents, non-polar solvents, and ionic liquids.

4. The method for manufacturing coated semiconductor nanoparticles according to claim 3, characterized in that, The solvent used in the coating process is a solvent containing more than 90% of the non-polar solvent by volume.

5. The method for manufacturing coated semiconductor nanoparticles according to claim 3, characterized in that, The non-polar solvent used in the coating process is any one or more solvents selected from toluene, hexane, cyclohexane, benzene, and diethyl ether.

6. The method for manufacturing coated semiconductor nanoparticles according to claim 1, characterized in that, The metal oxide precursor used in the coating process is selected from one or more of the following: metal alkoxides, metal halides, and metal complexes.

7. The method for manufacturing coated semiconductor nanoparticles according to claim 1, characterized in that, The coating process is carried out in the presence of an alkaline aqueous solution.

8. The method for manufacturing coated semiconductor nanoparticles according to claim 1, characterized in that, The coating process is carried out in the presence of a surfactant.

9. The method for manufacturing coated semiconductor nanoparticles according to claim 1, characterized in that, The coating process is carried out in the presence of alcohol.

10. The method for manufacturing coated semiconductor nanoparticles according to claim 1, characterized in that, The microwave irradiation treatment in the coating process takes place in the range of 3 to 30 minutes.

11. The method for manufacturing coated semiconductor nanoparticles according to claim 1, characterized in that, The heating temperature of the microwave irradiation treatment in the coating process is in the range of 40 to 100°C.

12. The method for manufacturing coated semiconductor nanoparticles according to any one of claims 1 to 11, characterized in that, Prior to the coating process, there is a process of modifying the surface of the semiconductor nanoparticles with a surface modifier.

13. The method for manufacturing coated semiconductor nanoparticles according to claim 12, characterized in that, The surface modifier is selected from one or more of (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.

14. A type of coated semiconductor nanoparticle, comprising semiconductor nanoparticles having a metal oxide coating on their surface, characterized in that, The semiconductor nanoparticle is a semiconductor nanoparticle comprising a semiconductor nanoparticle core and one or more semiconductor nanoparticle shells covering the semiconductor nanoparticle core. The semiconductor nanoparticle core is InP, and the semiconductor nanoparticle shell is ZnS or ZnSe; therefore, the semiconductor nanoparticles are InP / ZnSe / ZnS. The metal oxide is coated onto the surface of the semiconductor nanoparticles by microwave irradiation. The metal in the metal oxide is any one of zinc (Zn), iron (Fe), yttrium (Y), aluminum (Al), zirconium (Zr), titanium (Ti), and hafnium (Hf).

15. A resin composition, characterized in that, It is a resin composition formed by dispersing the coated semiconductor nanoparticles as described in claim 14 in a resin.

16. A wavelength conversion material, characterized in that, It uses a cured product of the resin composition of claim 15.

17. A light-emitting element, characterized in that, It uses the wavelength conversion material as described in claim 16.

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