Method for manufacturing hydrophilic quantum dots

Abstract

The present invention provides a method for producing hydrophilic quantum dots, which is characterized by adding a metal halide, two or more phosphorus compounds, an organic acid having a mercapto group or an alcohol having a mercapto group, and an aprotic polar solvent to hydrophobic quantum dots dispersed in a non-polar solvent and heating the mixture to thereby produce the hydrophilic quantum dots. Therefore, hydrophilic treatment of the hydrophobic quantum dots is carried out. As a result, provided is a method for producing hydrophilic quantum dots that can be hydrophilized during a hydrophilization treatment without deteriorating the characteristics of the quantum dots.

Description

Technical Field

[0001] This invention relates to a method for manufacturing hydrophilic quantum dots. Background Technology

[0002] Semiconductor crystal particles with a diameter of nanometers are called quantum dots. Because excitons generated by light absorption are confined to a nanometer-sized region, the energy levels of the semiconductor crystal particles are discrete, and their band gap varies with particle size. Due to these effects, quantum dots exhibit higher brightness and efficiency in fluorescence emission compared to conventional phosphors, and their emission spectra are also sharper.

[0003] Furthermore, quantum dots possess the characteristic that their band gap varies with their particle size, thus enabling control over the emission wavelength. This makes them promising applications as wavelength conversion materials in solid-state lighting or displays. For example, by using quantum dots as wavelength conversion materials in displays, a wider color gamut and lower power consumption can be achieved compared to existing phosphor materials.

[0004] As an assembly method for using quantum dots as wavelength conversion materials, the following method is proposed: dispersing quantum dots in a resin material, laminating the resin material containing quantum dots with a transparent film, thereby producing a wavelength conversion film and installing it in a backlight unit (Patent Document 1).

[0005] Furthermore, it was proposed that by using quantum dots as color filter materials, the quantum dots absorb blue monochromatic light from the backlight unit and emit red or green light, thereby functioning as color filters and wavelength conversion materials, and thus being suitable for image elements with high efficiency and excellent color reproduction (Patent Document 2).

[0006] In such applications, quantum dots are typically mixed with photocurable, thermocurable, or thermoplastic polymers, or with monomers that are polymerized by light or heat, to form films or filters. The compatibility of quantum dots with these polymers or monomers is important because it affects stability and properties.

[0007] Existing technical documents Patent documents Patent Document 1: Japanese Patent Publication No. 2013-544018 Patent Document 2: Japanese Patent Application Publication No. 2017-21322 Summary of the Invention

[0008] (a) Technical problems to be solved However, quantum dots are hydrophobic because their surfaces contain ligands such as thiols, carboxylic acids, and amines with long-chain alkyl groups. On the other hand, photopolymerizable or thermopolymerizable polymers or monomers have polymerizable functional groups such as acryloyl or epoxy groups, and are therefore polar. This leads to poor compatibility of quantum dots, resulting in problems such as aggregation or decreased stability. To solve these problems, quantum dots are hydrophilized.

[0009] As a method for hydrophilicizing quantum dots, studies have been conducted on micellization using amphiphilic surfactants, formation of metal oxide layers such as silica, and introduction of polar functional groups through silane coupling agents. However, each of these methods can lead to the detachment of ligands already present on the quantum dot surface, resulting in problems such as luminescence degradation or decreased stability.

[0010] This invention was made to solve the above-mentioned problems, and its purpose is to provide a method for manufacturing hydrophilic quantum dots that can be hydrophilized in a hydrophilization process without degrading the properties of the quantum dots.

[0011] (II) Technical Solution To achieve the above objectives, the present invention provides a method for manufacturing hydrophilic quantum dots, characterized in that the hydrophilization treatment of the hydrophobic quantum dots is carried out by adding metal halides, two or more phosphorus compounds, organic acids or alcohols with thiol groups and aprotic polar solvents to hydrophobic quantum dots dispersed in a nonpolar solvent and heating them.

[0012] This method of manufacturing hydrophilic quantum dots allows for hydrophilization during the hydrophilization process without degrading the properties of the quantum dots.

[0013] At this time, chlorides, bromides, or iodides of zinc, gallium, indium, cadmium, silver, copper, aluminum, zirconium, titanium, magnesium, manganese, germanium, and lead can be used as the metal halide.

[0014] Therefore, it is advantageous in suppressing the degradation of quantum dot properties during hydrophilization treatment.

[0015] At this time, any two or more of the following can be used as the phosphorus compound: tributylphosphine, dibutylphenylphosphine, trihexylphosphine, trioctylphosphine oxide, triphenylphosphine, triphenylphosphine oxide, diphenylpropylphosphine, methyldiphenylphosphine, isopropyldiphenylphosphine, tris(m-tolyl)phosphine, tris(p-tolyl)phosphine, diphenylpropylphosphine, cyclohexyldiphenylphosphine, and 4-(diphenylphosphino)benzoic acid.

[0016] Therefore, it is advantageous in terms of hydrophilic treatment.

[0017] At this time, any one of the following can be used as the organic acid or alcohol having a thiol group: mercaptosuccinic acid, 3-mercaptoisobutyric acid, thiolactic acid, 3-mercaptopropionic acid, mercaptoundecanoic acid, 2-mercaptobenzoic acid, 3-mercaptobenzoic acid, 4-mercaptobenzoic acid, 2-mercaptoethanol, 3-mercaptophenol, 4-mercaptophenol, mercaptobutanol, mercaptopropanol, 6-mercaptohexanol, 2,3-dimercapto-1-propanol, and 1-thioglycerol.

[0018] Therefore, it is advantageous to perform hydrophilization in the hydrophilization process without degrading the properties of the quantum dots.

[0019] At this time, any one of N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide, dimethylacetamide, and N-methylpyrrolidone can be used as the aprotic polar solvent.

[0020] Therefore, it is advantageous to perform hydrophilization in the hydrophilization process without degrading the properties of the quantum dots.

[0021] At this point, the quantum yield of the hydrophilized quantum dots can be higher than that before the hydrophilized treatment.

[0022] Thus, if the method for manufacturing hydrophilic quantum dots of the present invention is adopted, the quantum yield of the quantum dots after hydrophilization treatment can be improved compared with that before hydrophilization treatment.

[0023] (III) Beneficial Effects As described above, the method for manufacturing hydrophilic quantum dots of the present invention enables hydrophilization during hydrophilization treatment without degrading the properties of the quantum dots. Attached Figure Description

[0024] Figure 1 A flowchart illustrating a method for manufacturing hydrophilic quantum dots according to an embodiment of the present invention is shown. Detailed Implementation

[0025] The present invention will now be described in detail, but the present invention is not limited thereto.

[0026] As described above, a method for manufacturing hydrophilic quantum dots is sought that allows for hydrophilization during the hydrophilization process without degrading the properties of the quantum dots.

[0027] The inventors of this application have conducted in-depth research on the above-mentioned technical problems and discovered that, through the following method for manufacturing hydrophilic quantum dots, hydrophilization can be achieved in the hydrophilization process without deteriorating the properties of the quantum dots, thus completing the present invention. The method for manufacturing hydrophilic quantum dots is characterized by adding metal halides, two or more phosphorus compounds, organic acids or alcohols with thiol groups, and aprotic polar solvents to hydrophobic quantum dots dispersed in a nonpolar solvent and then heating them to perform the hydrophilization process on the hydrophobic quantum dots.

[0028] The following is for reference Figure 1 The method for manufacturing hydrophilic quantum dots according to an embodiment of the present invention will be described, and more specifically, the method for manufacturing hydrophilic quantum dots soluble in polar solvents will be described.

[0029] First, prepare hydrophobic quantum dots dispersed in a nonpolar solvent. Figure 1 S1).

[0030] In this invention, as long as the hydrophobic quantum dot is hydrophobic, there are no particular limitations on its composition and manufacturing method, and quantum dots corresponding to the purpose can be selected. Examples of quantum dot compositions include group II-IV semiconductors, group III-V semiconductors, group II-VI semiconductors, group I-III-VI semiconductors, group II-IV-V semiconductors, group IV semiconductors, perovskite semiconductors, etc.

[0031] Furthermore, quantum dots can have only a core or a core-shell structure.

[0032] Specifically, examples of nuclear materials include CdSe, CdS, CdTe, InP, InAs, InSb, AlP, AlAs, AlSb, ZnSe, ZnS, ZnTe, Zn3P2, GaP, GaAs, GaSb, CuInSe2, CuInS2, CuInTe2, CuGaSe2, CuGaS2, CuGaTe2, CuAlSe2, CuAlS2, CuAlTe2, AgInSe2, AgInS2, AgInTe2, AgGaSe2, AgGaS2, AgGaTe2, PbSe, PbS, PbTe, Si, Ge, graphene, CsPbCl3, CsPbBr3, CsPbI3, CH3NH3PbCl3, and mixtures of these components or substances formed by adding dopants to these components.

[0033] Examples of shell materials include ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, AlSb, BeS, BeSe, BeTe, MgS, MgSe, MgTe, PbS, PbSe, PbTe, SnS, SnSe, SnTe, CuF, CuCl, CuBr, CuI, and mixed crystals of these components.

[0034] Furthermore, quantum dots can be spherical, cubic, or rod-shaped. The shape of quantum dots is unrestricted and can be freely chosen.

[0035] The particle size of quantum dots can be appropriately selected to match the target wavelength range, but the average particle size is preferably below 20 nm. If the average particle size is below 20 nm, the quantum size effect can be reliably obtained, improving luminous efficiency or making it easy to control the band gap through particle size.

[0036] The particle size of a quantum dot can be calculated by measuring the average of the unidirectional maximum particle diameter (Feret diameter) of more than 20 particles obtained using a transmission electron microscope (TEM). However, the method for determining the average particle size is not limited to this method; other methods can also be used.

[0037] Ligands can exist on the surface of quantum dots, such as oleic acid, stearic acid, palmitic acid, myristic acid, lauric acid, decanoic acid, octanoic acid, 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, tributylphosphine oxide, etc.

[0038] As long as the quantum dots are well dispersed, there are no particular restrictions on the nonpolar solvent, and it can be freely selected. Preferably, the nonpolar solvent is one that does not mix with aprotic polar solvents. Examples of nonpolar solvents include hexane, cyclohexane, pentane, toluene, heptane, and 1-octadecene.

[0039] Next, a metal halide, two or more phosphorus compounds, an organic acid with a thiol group or an alcohol with a thiol group, and an aprotic polar solvent are added to the hydrophobic quantum dots dispersed in a nonpolar solvent, and the mixture is heated to perform the hydrophilization treatment of the hydrophobic quantum dots. Figure 1 (S2).

[0040] There are no particular restrictions on the metal halide, but metal halides composed of quantum dots are preferred. For example, if it is an InP / ZnS core-shell quantum dot, zinc or indium halides are suitable. There are no particular restrictions on the type of halogen, but chlorides, bromides, or iodides are preferred.

[0041] As specific metal halides, chlorides, bromides, or iodides of zinc, gallium, indium, cadmium, silver, copper, aluminum, zirconium, titanium, magnesium, manganese, germanium, and lead can be used.

[0042] If the quantum dot is set to 1, then the amount of metal halide added is preferably 2 or more by weight, and particularly preferably 5 or more.

[0043] The combination and mixing ratio of two or more phosphorus compounds can be freely selected, and appropriate choices can be made based on the type of quantum dots or the type and combination of phosphorus compounds. If only one phosphorus compound is used, hydrophilization will be insufficient.

[0044] The smaller the steric hindrance effect of the ligands, the easier it is to induce coordination with quantum dots. On the other hand, if the steric hindrance effect decreases, it is easier for quantum dots to aggregate. If aggregation occurs, only some of the existing ligands are exchanged, and hydrophilization cannot occur. Therefore, by combining two phosphorus compounds to replace the existing ligands on the surface of quantum dots with a phosphorus compound with higher coordination, and further exchanging a phosphorus compound with lower coordination and higher steric hindrance effect with a phosphorus compound with higher coordination, it is possible to suppress the aggregation of quantum dots and effectively promote ligand exchange on the surface of quantum dots.

[0045] As a phosphorus compound, it preferably contains two or more selected from tributylphosphine, dibutylphenylphosphine, trihexyphosphine, trioctylphosphine, trioctylphosphine oxide, triphenylphosphine, triphenylphosphine oxide, diphenylpropylphosphine, methyldiphenylphosphine, isopropyldiphenylphosphine, tris(m-tolyl)phosphine, tris(p-tolyl)phosphine, diphenylpropylphosphine, cyclohexyldiphenylphosphine, and 4-(diphenylphosphino)benzoic acid.

[0046] If the quantum dot is set to 1, then the amount of phosphorus compound added is preferably 5 or more by weight, and particularly preferably 10 or more.

[0047] Suitable organic acids or alcohols containing thiol groups include mercaptosuccinic acid, 3-mercaptoisobutyric acid, thiolactic acid, 3-mercaptopropionic acid, mercaptoundecanoic acid, 2-mercaptobenzoic acid, 3-mercaptobenzoic acid, 4-mercaptobenzoic acid, 2-mercaptoethanol, 3-mercaptophenol, 4-mercaptophenol, mercaptobutanol, mercaptopropanol, 6-mercaptohexanol, 2,3-dimercapto-1-propanol, and 1-thioglycerol.

[0048] If the quantum dot is set to 1, then the amount of organic acid or alcohol containing a thiol group added, by weight, is preferably 10 or more, particularly preferably 20 or more. The organic acid or alcohol containing a thiol group can be freely selected, and can be appropriately chosen according to the type of quantum dot or the type and combination of added phosphorus compounds.

[0049] As a non-protic polar solvent, solvents that do not mix with non-polar solvents are preferred, and N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide, dimethylacetamide, and N-methylpyrrolidone are suitable.

[0050] The amount of aprotic polar solvent added can be freely selected, and can be appropriately selected according to the required quantum dot concentration after hydrophilization treatment.

[0051] Thus, a method for manufacturing hydrophilic quantum dots involves adding metal halides, two or more phosphorus compounds, thiol-containing organic acids or thiol-containing alcohols, and an aprotic polar solvent to hydrophobic quantum dots dispersed in a nonpolar solvent, followed by heating. This hydrophilization process extracts the quantum dots from the nonpolar solvent into the aprotic polar solvent. The heating temperature is preferably 50°C or higher, particularly preferably 100°C or higher, and lower than the boiling point of the solvent. The heating time is simply the time required for the quantum dots to be extracted from the nonpolar solvent into the aprotic polar solvent, for example, approximately 60 minutes.

[0052] Furthermore, the quantum yield, such as the internal quantum efficiency, of the quantum dots after hydrophilization treatment is higher than that before hydrophilization treatment. If the method for manufacturing hydrophilic quantum dots of the present invention is applicable, the quantum yield of the quantum dots after hydrophilization treatment can be improved compared to that before hydrophilization treatment.

[0053] Example The following examples and comparative examples of the present invention are shown to illustrate the present invention in more detail, but the present invention is not limited to these examples and comparative examples.

[0054] In this embodiment and comparative example, InP / ZnSe / ZnS core-shell quantum dots are used as quantum dot materials.

[0055] (Quantum dot nucleosynthesis process) 0.23 g (0.9 mmol) of palmitic acid, 0.088 g (0.3 mmol) of indium acetate, and 10 mL of 1-octadecene were added to a flask. The mixture was heated and stirred at 100 °C under reduced pressure to dissolve the raw materials while simultaneously degassing for 1 hour. Then, the flask was purged with nitrogen, and 0.75 mL (0.15 mmol) of a solution of tris(trimethylsilyl)phosphine and trioctylphosphine, adjusted to 0.2 M, was added. The temperature was raised to 300 °C, and the solution changed from yellow to red, confirming the formation of nuclei.

[0056] (Quantum dot shell synthesis process) Next, 2.85 g (4.5 mmol) of zinc stearate and 15 mL of 1-octadecene were added to another flask, heated to 100 °C under reduced pressure, stirred to dissolve and degassed for 1 hour to prepare a 0.3 M zinc stearate octadecene solution. 3.0 mL (0.9 mmol) was added to the reaction solution after nucleosynthesis and cooled to 200 °C.

[0057] Next, 0.474 g (6 mmol) of selenium and 4 mL of trioctylphosphine were added to another flask and heated to 150 °C to dissolve them, preparing a 1.5 M solution of selenium trioctylphosphine. The reaction solution after the nucleosynthesis step, which had been cooled to 200 °C, was heated to 320 °C over 30 minutes. At the same time, the selenium trioctylphosphine solution was added in increments of 0.1 mL, for a total of 0.6 mL (0.9 mmol). The solution was kept at 320 °C for 10 minutes and then cooled to room temperature.

[0058] Then, 0.44 g (2.2 mmol) of zinc acetate was added, and the mixture was heated to 100 °C under reduced pressure with stirring to dissolve it. The flask was then purged again with nitrogen, heated to 230 °C, and 0.98 mL (4 mmol) of 1-dodecyl mercaptan was added. The mixture was kept at this temperature for 1 hour. The resulting solution was cooled to room temperature to prepare a solution containing core-shell quantum dots composed of InP / ZnSe / ZnS.

[0059] (Quantum dot dispersion process) After the reaction was completed and cooled to room temperature, ethanol was added to precipitate the reactants, followed by centrifugation to remove the supernatant. The same purification process was then performed, dispersing the product in hexane, a nonpolar solvent, to obtain a hexane solution containing quantum dots. The concentration of quantum dots in this solution was 1 wt%.

[0060] When the quantum efficiency measurement system (QE-2100) manufactured by OTSUKA ELECTRONICS CO.,LTD. was used to measure the emission wavelength, fluorescence emission half-width at half-maximum, and fluorescence emission efficiency (internal quantum efficiency) of quantum dots with an excitation wavelength of 450 nm, the emission wavelength was 533 nm, the half-width at half-maximum was 40 nm, and the internal quantum efficiency was 70%.

[0061] (Example 1) Add 5 mL of hexane solution containing quantum dots to a 50 mL flask, then add 0.2 g of triphenylphosphine and 1.0 mL of trioctylphosphine, and stir. Further, while stirring, add 0.25 g of zinc bromide and 5 mL of N,N-dimethylformamide.

[0062] After all the solid components were dissolved, 0.4 mL of 3-mercaptopropionic acid was added. The mixture was stirred briefly at room temperature, then heated to 100°C under reflux for 60 minutes. Following the reaction, the quantum dots migrated from the hexane layer to the N,N-dimethylformamide layer, yielding hydrophilized quantum dots.

[0063] When the emission wavelength, fluorescence half-width at half-maximum (FWHM), and fluorescence efficiency (internal quantum efficiency) of the hydrophilicated quantum dots were measured under the same conditions as when the quantum dot dispersion process was just completed, the emission wavelength was 533 nm, the FWHM was 40 nm, and the internal quantum efficiency was 81%.

[0064] (Example 2) Add 5 mL of hexane solution containing quantum dots to a 50 mL flask, then add 0.2 g of isopropyl diphenylphosphine and 1.0 mL of trioctylphosphine, and stir. Further, while stirring, add 0.25 g of aluminum chloride and 5 mL of dimethyl sulfoxide.

[0065] After all the solid components were dissolved, 0.4 mL of 6-mercaptohexanol was added. The mixture was stirred briefly at room temperature, then heated to 100°C under reflux for 60 minutes. Following the reaction, the quantum dots migrated from the hexane layer to the dimethyl sulfoxide layer, yielding hydrophilized quantum dots.

[0066] When the emission wavelength, fluorescence emission half-width at half-maximum, and fluorescence emission efficiency (internal quantum efficiency) of the hydrophilicated quantum dots were measured in the same manner as in Example 1, the emission wavelength was 533 nm, the half-width at half-maximum was 39 nm, and the internal quantum efficiency was 77%.

[0067] (Comparative Example 1) Add 5 mL of hexane solution containing quantum dots to a 50 mL flask, add 1.0 g of triphenylphosphine, and stir. Thus, only one phosphorus compound was added in Comparative Example 1. Further, while stirring, add 0.25 g of zinc bromide and 5 mL of N,N-dimethylformamide.

[0068] After all the solid components were dissolved, 0.4 mL of 6-mercaptohexanol was added. The mixture was stirred briefly at room temperature, then heated to 100°C under reflux for 60 minutes. After the reaction, most of the quantum dots remained in the hexane layer. Therefore, the hydrophilization of the quantum dots was incomplete.

[0069] (Comparative Example 2) Add 5 mL of hexane solution containing quantum dots to a 50 mL flask, then add 0.25 g of zinc bromide and 5 mL of N,N-dimethylformamide. After all the solid components have dissolved, add 0.4 mL of 3-mercaptopropionic acid.

[0070] After stirring briefly at room temperature, the mixture was heated to 100°C under reflux for 60 minutes. Following the reaction, the quantum dots migrated from the hexane layer to the N,N-dimethylamide layer, yielding hydrophilized quantum dots. Thus, in Comparative Example 2, hydrophilization was performed without the addition of phosphorus compounds.

[0071] When the emission wavelength, fluorescence half-width at half-maximum (FWHM), and fluorescence efficiency (internal quantum efficiency) of the hydrophilicated quantum dots were measured in the same manner as in Example 1, the emission wavelength was 536 nm, the FWHM was 42 nm, and the internal quantum efficiency was 52%. Therefore, the internal quantum efficiency decreased after hydrophilication treatment compared to before hydrophilication treatment.

[0072] (Comparative Example 3) Add 5 mL of hexane solution containing quantum dots to a 50 mL flask, then add 0.2 g of isopropyl diphenylphosphine and 1.0 mL of trioctylphosphine, and stir. Further, while stirring, add 5 mL of dimethyl sulfoxide.

[0073] After all the solid components were dissolved, 0.4 mL of 6-mercaptohexanol was added. The mixture was stirred briefly at room temperature, then heated to 100°C under reflux for 60 minutes. Following the reaction, the quantum dots migrated from the hexane layer to the dimethyl sulfoxide layer, yielding hydrophilized quantum dots. Thus, in Comparative Example 3, hydrophilization was performed without the addition of metal halides.

[0074] When the emission wavelength, fluorescence half-width at half-maximum (FWHM), and fluorescence efficiency (internal quantum efficiency) of the hydrophilicated quantum dots were measured in the same manner as in Example 1, the emission wavelength was 535 nm, the FWHM was 45 nm, and the internal quantum efficiency was 43%. Therefore, the internal quantum efficiency decreased after hydrophilication treatment compared to before hydrophilication treatment.

[0075] Thus, the hydrophilization treatment in the comparative examples was insufficient (Comparative Example 1) or it was confirmed that the luminescence intensity decreased due to the hydrophilization treatment (Comparative Examples 2 and 3). On the other hand, the hydrophilization treatment in the embodiments was fully implemented, and the quantum yield did not decrease due to the hydrophilization treatment.

[0076] As described above, it has been confirmed that by performing a hydrophilic treatment on the hydrophilic quantum dots of the present invention according to the manufacturing method, the hydrophilic treatment can be performed without degrading the luminescence properties of the quantum dots.

[0077] This manual contains the following solutions.

[0078] [1]: A method for manufacturing hydrophilic quantum dots, characterized in that the hydrophilic quantum dots are hydrophilized by adding metal halides, two or more phosphorus compounds, organic acids with thiol groups or alcohols with thiol groups and aprotic polar solvents to hydrophobic quantum dots dispersed in a nonpolar solvent and heating them.

[0079] [2]: The method for manufacturing hydrophilic quantum dots according to [1] above is characterized in that the chloride, bromide or iodide of zinc, gallium, indium, cadmium, silver, copper, aluminum, zirconium, titanium, magnesium, manganese, germanium or lead is used as the metal halide.

[0080] [3]: The method for manufacturing hydrophilic quantum dots according to [1] or [2] above is characterized in that any two or more of the following are used as the phosphorus compound: tributylphosphine, dibutylphenylphosphine, trihexylphosphine, trioctylphosphine, trioctylphosphine oxide, triphenylphosphine, triphenylphosphine oxide, diphenylpropylphosphine, methyldiphenylphosphine, isopropyldiphenylphosphine, tris(m-tolyl)phosphine, tris(p-tolyl)phosphine, diphenylpropylphosphine, cyclohexyldiphenylphosphine, and 4-(diphenylphosphino)benzoic acid.

[0081] [4]: The method for manufacturing hydrophilic quantum dots according to any one of [1] to [3] above is characterized in that any one of mercaptosuccinic acid, 3-mercaptoisobutyric acid, thiolactic acid, 3-mercaptopropionic acid, mercaptoundecanoic acid, 2-mercaptobenzoic acid, 3-mercaptobenzoic acid, 4-mercaptobenzoic acid, 2-mercaptoethanol, 3-mercaptophenol, 4-mercaptophenol, mercaptobutanol, mercaptopropanol, 6-mercaptohexanol, 2,3-dimercapto-1-propanol, and 1-thioglycerol is used as the organic acid or alcohol having a mercapto group.

[0082] [5]: The method for manufacturing hydrophilic quantum dots according to any one of [1] to [4] above is characterized in that any one of N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide, dimethylacetamide, and N-methylpyrrolidone is used as the aprotic polar solvent.

[0083] [6]: The method for manufacturing hydrophilic quantum dots according to any one of [1] to [5] above is characterized in that the quantum yield of the quantum dots after hydrophilization treatment is higher than the quantum yield before hydrophilization treatment.

[0084] Furthermore, this invention is not limited to the above-described embodiments. The above embodiments are illustrative examples, and any technical solution having a substantially identical structure and achieving the same effect as the technical concept described in the claims of this invention is included within the technical scope of this invention.

Claims

1. A method for manufacturing hydrophilic quantum dots, characterized in that, The hydrophilization of the hydrophobic quantum dots is achieved by adding a metal halide, two or more phosphorus compounds, an organic acid with a thiol group or an alcohol with a thiol group and an aprotic polar solvent to the hydrophobic quantum dots dispersed in a nonpolar solvent and then heating them.

2. The method for manufacturing hydrophilic quantum dots according to claim 1, characterized in that, The metal halide is described using chlorides, bromides, or iodides of zinc, gallium, indium, cadmium, silver, copper, aluminum, zirconium, titanium, magnesium, manganese, germanium, or lead.

3. The method for manufacturing hydrophilic quantum dots according to claim 1, characterized in that, The phosphorus compound may be any two or more selected from the following: tributylphosphine, dibutylphenylphosphine, trihexylphosphine, trioctylphosphine, trioctylphosphine oxide, triphenylphosphine, triphenylphosphine oxide, diphenylpropylphosphine, methyldiphenylphosphine, isopropyldiphenylphosphine, tris(m-tolyl)phosphine, tris(p-tolyl)phosphine, diphenylpropylphosphine, cyclohexyldiphenylphosphine, and 4-(diphenylphosphino)benzoic acid.

4. The method for manufacturing hydrophilic quantum dots according to claim 1, characterized in that, The following can be used as the organic acid or alcohol containing a thiol group: mercaptosuccinic acid, 3-mercaptoisobutyric acid, thiolactic acid, 3-mercaptopropionic acid, mercaptoundecanoic acid, 2-mercaptobenzoic acid, 3-mercaptobenzoic acid, 4-mercaptobenzoic acid, 2-mercaptoethanol, 3-mercaptophenol, 4-mercaptophenol, mercaptobutanol, mercaptopropanol, 6-mercaptohexanol, 2,3-dimercapto-1-propanol, and 1-thioglycerol.

5. The method for manufacturing hydrophilic quantum dots according to claim 1, characterized in that, The nonprotic polar solvent is described using any one of N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide, dimethylacetamide, and N-methylpyrrolidone.

6. The method for manufacturing hydrophilic quantum dots according to any one of claims 1 to 5, characterized in that, The quantum yield of the quantum dots after hydrophilization treatment is higher than that before hydrophilization treatment.

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