Semiconductor nanoparticles and their manufacturing method

Abstract

Provided is a method for producing semiconductor nanoparticles that exhibit band-edge luminescence and have an emission spectrum with a narrow half-width. The method for producing semiconductor nanoparticles comprises: preparing a first mixture containing an organic solvent and at least one compound selected from the group consisting of compounds having an indium (In)-sulfur (S) bond and compounds having a gallium (Ga)-sulfur (S) bond; adjusting the first mixture to a first temperature in the range of 40-180°C, and then mixing with a solution containing a silver (Ag) salt and an organic solvent to obtain a second mixture including composite particles of silver sulfide and a sulfide containing at least one of indium and gallium; and heat-treating the second mixture by adjusting the second mixture to a second temperature in the range of 130-240°C, and maintaining the second temperature for one second or more to obtain first semiconductor nanoparticles.

Description

[Technical Field]

[0001] The present disclosure relates to semiconductor nanoparticles and methods for making same. [Background technology]

[0002] It is known that semiconductor particles exhibit a quantum size effect when their particle size is, for example, 10 nm or less, and such nanoparticles are called quantum dots (also called semiconductor quantum dots). The quantum size effect refers to the phenomenon in which the valence band and conduction band, which are considered continuous in bulk particles, become discrete when the particle size is reduced to nanometers, and the band gap energy changes depending on the particle size.

[0003] Quantum dots can absorb light and convert its wavelength to light corresponding to its band gap energy, so white light-emitting devices utilizing quantum dot emission have been proposed (see, for example, JP 2012-212862 A and JP 2010-177656 A). Wavelength conversion films using core-shell structured semiconductor quantum dots that can emit band edge light and have a low toxicity composition have also been proposed (see, for example, WO 2014 / 129067 A). Furthermore, sulfide nanoparticles (see, for example, WO 2018 / 159699 A, WO 2019 / 160094 A, and WO 2020 / 162622 A) have been investigated as ternary semiconductor nanoparticles that can emit band edge light and have a low toxicity composition. Summary of the Invention [Problem to be solved by the invention]

[0004] An object of one aspect of the present disclosure is to provide semiconductor nanoparticles that exhibit band-edge emission and have a narrow half-width in the emission spectrum, and a method for producing the same. [Means for solving the problem]

[0005] A first aspect is a method for producing semiconductor nanoparticles, the method including: preparing a first mixture containing at least one compound selected from the group consisting of compounds having an indium (In)-sulfur (S) bond and compounds having a gallium (Ga)-sulfur (S) bond, and an organic solvent; adjusting the first mixture to a first temperature in the range of 40°C or higher and 180°C or lower, and mixing the first mixture with a solution containing a silver (Ag) salt and the organic solvent to obtain a second mixture containing composite particles of silver sulfide and a sulfide containing at least one of indium and gallium; and adjusting the second mixture to a second temperature in the range of 130°C or higher and 240°C or lower, and holding the second temperature for one second or longer to heat-treat the second mixture, thereby obtaining first semiconductor nanoparticles.

[0006] A second aspect is a semiconductor nanoparticle comprising a first semiconductor containing silver (Ag), at least one of indium (In) and gallium (Ga), and sulfur (S). A second semiconductor containing gallium (Ga) and sulfur (S) and substantially no silver (Ag) is disposed on the surface of the semiconductor nanoparticle. The semiconductor nanoparticle exhibits band-edge emission with an emission peak wavelength in the wavelength range of 450 nm to 700 nm when irradiated with light having a wavelength of 365 nm, has a band-edge emission purity of 70% or more, and an internal quantum yield of the band-edge emission of 15% or more, and the standard deviation of the average particle size of the first semiconductor is 0.6 nm or less.

[0007] A third aspect is a light-emitting device comprising a light conversion member containing the semiconductor nanoparticles of the second aspect and a semiconductor light-emitting element. A fourth aspect is a light-emitting device comprising a cathode, a light-emitting layer containing the semiconductor nanoparticles of the second aspect, and Yang and an anode, and the light-emitting layer is disposed between the cathode and the anode. [Effects of the Invention]

[0008] According to one aspect of the present disclosure, it is possible to provide semiconductor nanoparticles that exhibit band-edge emission and have a narrow half-width in the emission spectrum, and a method for producing the same. [Brief explanation of the drawings]

[0009] [Figure 1] 3 is a diagram showing the absorption spectrum and the emission spectrum of the first semiconductor nanoparticles according to Example 1. FIG. [Figure 2] 1 is a diagram showing the absorption spectrum and the emission spectrum of the semiconductor nanoparticles according to Example 1. FIG. [Figure 3] 1 is a diagram showing an example of a transmission electron microscope (TEM) image of first semiconductor nanoparticles according to Example 1. FIG. [Figure 4] FIG. 2 is a diagram showing an example of a TEM image of semiconductor nanoparticles according to Example 1. [Figure 5] FIG. 10 is a diagram showing an example of a TEM image of semiconductor nanoparticles according to Example 2. [Figure 6] FIG. 2 is a diagram showing an example of the X-ray diffraction pattern of first semiconductor nanoparticles according to Example 1 and Reference Example 1. [Figure 7] FIG. 10 is a diagram showing the emission spectrum of semiconductor nanoparticles according to Example 17. DETAILED DESCRIPTION OF THE INVENTION

[0010] As used herein, the term "process" refers not only to an independent process, but also to processes that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. Furthermore, when multiple substances corresponding to each component are present in the composition, the content of each component refers to the total amount of those substances present in the composition, unless otherwise specified. Furthermore, the upper and lower limits of the numerical ranges described herein can be arbitrarily selected and combined from the numerical ranges exemplified. In this specification, in formulas representing the composition of phosphors or luminescent materials, multiple elements separated by a comma (,) mean that at least one of those multiple elements is contained in the composition. In formulas representing the composition of phosphors, the part before the colon (:) represents the host crystal, and the part after the colon (:) represents the activator element. In this specification, the relationship between color names and chromaticity coordinates, the relationship between the wavelength range of light and the color name of monochromatic light, etc., follows JIS Z8110. The half width of semiconductor nanoparticles refers to the wavelength width (full width at half maximum; FWHM) of the emission spectrum of the semiconductor nanoparticles where the emission intensity is 50% of the maximum emission intensity. Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments shown below are intended to exemplify semiconductor nanoparticles and methods for producing the same in order to embody the technical concept of the present invention, and the present invention is not limited to the semiconductor nanoparticles and methods for producing the same shown below.

[0011] Method for producing semiconductor nanoparticles The method for producing semiconductor nanoparticles includes a first step of preparing a first mixture containing at least one compound selected from the group consisting of compounds having an indium (In)-sulfur (S) bond and compounds having a gallium (Ga)-sulfur (S) bond, and an organic solvent; a second step of adjusting the first mixture to a first temperature in the range of 40°C or higher and 180°C or lower, and mixing the first mixture with a solution containing a silver (Ag) salt and an organic solvent to obtain a second mixture containing composite particles of silver sulfide and a sulfide containing at least one of indium and gallium; and a third step of adjusting the second mixture to a second temperature in the range of 130°C or higher and 240°C or lower, and maintaining the second temperature for one second or longer to heat-treat the second mixture, thereby obtaining first semiconductor nanoparticles.

[0012] It is believed that nanoparticles containing silver sulfide (e.g., AgS) are produced by adjusting a first mixture containing at least one compound selected from the group consisting of compounds having an In-S bond and compounds having a Ga-S bond to a predetermined first temperature and mixing it with an Ag salt in that state. The produced silver sulfide nanoparticles are believed to form composite particles with a sulfide containing at least one of indium and gallium. The composite particles are believed to be composed, for example, of silver sulfide nanoparticles and a sulfide containing at least one of indium and gallium disposed on their surfaces. It is believed that heat-treating a second mixture containing such composite particles at a second temperature promotes crystal transformation of the silver sulfide nanoparticles due to, for example, indium sulfide, gallium sulfide, etc. deposited on the surfaces of the silver sulfide nanoparticles, thereby producing first semiconductor nanoparticles with a uniform particle size. Furthermore, a second semiconductor containing gallium sulfide is disposed on the surfaces of the resulting first semiconductor nanoparticles to form second semiconductor nanoparticles. It is believed that this results in semiconductor nanoparticles that exhibit band-edge emission and have a narrow half-width in their emission spectra.

[0013] In the first step, a first mixture is prepared by mixing at least one compound selected from the group consisting of compounds having an In-S bond and compounds having a Ga-S bond with an organic solvent. The In-S bond in the compound having an In-S bond may be any of a covalent bond, an ionic bond, a coordinate bond, etc. Examples of the compound having an In-S bond include In salts of sulfur-containing compounds, which may be organic acid salts, inorganic acid salts, organometallic compounds, etc. Specific examples of sulfur-containing compounds include thiocarbamic acid, dithiocarbamic acid, thiocarbonates, dithiocarbonates (xanthogenic acid), trithiocarbonates, thiocarboxylic acids, dithiocarboxylic acids, and derivatives thereof. Among these, at least one compound selected from the group consisting of dithiocarbamic acid, xanthogenic acid, and derivatives thereof is preferred because it decomposes at relatively low temperatures. Specific examples of sulfur-containing compounds are the same as those described above. Specific examples of the compound having an In-S bond include indium trisdimethyldithiocarbamate, indium trisdiethyldithiocarbamate (In(DDTC)3), indium chlorobisdiethyldithiocarbamate, indium ethylxanthogenate (In(EX)3), etc. The first mixture may contain one compound having an In-S bond alone, or may contain two or more compounds in combination.

[0014] The Ga-S bond in a compound having a Ga-S bond may be any of a covalent bond, an ionic bond, a coordinate bond, etc. Examples of compounds having a Ga-S bond include Ga salts of sulfur-containing compounds, which may be organic acid salts of Ga, inorganic acid salts, organometallic compounds, etc. Specific examples of sulfur-containing compounds include thiocarbamic acid, dithiocarbamic acid, thiocarbonates, dithiocarbonates (xanthogenic acid), trithiocarbonates, thiocarboxylic acids, dithiocarboxylic acids, and derivatives thereof. Among these, at least one selected from the group consisting of dithiocarbamic acid, xanthogenic acid, and derivatives thereof is preferred because it decomposes at relatively low temperatures. Specific examples of sulfur-containing compounds are the same as those described above. Specific examples of compounds having a Ga-S bond include gallium trisdimethyldithiocarbamate, gallium trisdiethyldithiocarbamate (Ga(DDTC)3), gallium chlorobisdiethyldithiocarbamate, and gallium ethylxanthogenate (Ga(EX)3). The first mixture may contain one compound having a Ga—S bond alone, or may contain two or more compounds in combination.

[0015] Examples of organic solvents constituting the first mixture include amines having a hydrocarbon group containing 4 to 20 carbon atoms, such as alkylamines or alkenylamines having 4 to 20 carbon atoms; thiols having a hydrocarbon group containing 4 to 20 carbon atoms, such as alkylthiols or alkenylthiols having 4 to 20 carbon atoms; and phosphines having a hydrocarbon group containing 4 to 20 carbon atoms, such as alkylphosphines or alkenylphosphines having 4 to 20 carbon atoms. It is preferable to include at least one selected from the group consisting of these organic solvents. These organic solvents may ultimately be used to modify the surface of the resulting first semiconductor nanoparticles. Two or more organic solvents may be used in combination; for example, a mixed solvent may be used that combines at least one thiol having a hydrocarbon group containing 4 to 20 carbon atoms with at least one amine having a hydrocarbon group containing 4 to 20 carbon atoms. These organic solvents may be used in combination with other organic solvents. When the organic solvent contains the thiol and the amine, the volume ratio of the thiol to the amine (thiol / amine) may be, for example, greater than 0 and equal to or less than 1, and preferably equal to or greater than 0.007 and equal to or less than 0.2.

[0016] The first mixture may further contain at least one selected from the group consisting of an indium (In) salt and a gallium (Ga) salt other than the compound having an In-S bond and the compound having a Ga-S bond. The In salt and Ga salt in the first mixture may be either an organic acid salt or an inorganic acid salt. Specific examples of inorganic acid salts include nitrates, sulfates, hydrochlorides, and sulfonates. Examples of organic acid salts include formates, acetates, oxalates, and acetylacetonates. The In salt and Ga salt may preferably be at least one selected from the group consisting of these salts, and more preferably at least one selected from the group consisting of organic acid salts such as acetates and acetylacetonates, because these salts have high solubility in organic solvents and allow the reaction to proceed more uniformly. The first mixture may contain one In salt and one Ga salt, respectively, alone or in combination of two or more.

[0017] The first mixture may preferably contain at least one compound having a Ga-S bond. In addition to the compound having a Ga-S bond, the first mixture may contain at least one selected from the group consisting of a compound having an In-S bond, an In salt, and a Ga salt, and may contain at least an In salt.

[0018] The ratio of the number of In atoms to the total number of In and Ga atoms in the first mixture (In / (In+Ga)) may be, for example, 0.01 or more and less than 1, and preferably 0.1 or more or 0.15 or more, and may be 0.99 or less, 0.95 or less, 0.6 or less, 0.5 or less, or 0.4 or less. When the ratio of the number of In atoms to the total number of In and Ga atoms is within a predetermined range, a short emission peak wavelength (for example, 545 nm or less) can be obtained.

[0019] In one embodiment, the ratio of the number of In atoms to the total number of In and Ga atoms in the first mixture (In / (In+Ga)) may preferably be 0.5 or more, 0.7 or more, or 0.8 or more, and may be 0.99 or less, or 0.95 or less. When the ratio of the number of In atoms to the total number of In and Ga atoms is within a predetermined range, a long-wavelength emission peak wavelength (e.g., 600 nm or more) can be obtained.

[0020] The first mixture may further contain at least one source of a Group 13 element other than In and Ga. The Group 13 element other than In and Ga may include at least one of Al and Tl. The Group 13 element source may be either an organic acid salt or an inorganic acid salt of the Group 13 element. The organic acid salt and the inorganic acid salt are as described above. The first mixture may be substantially free of a source of a Group 13 element other than In and Ga. Here, "substantially" indicates that the ratio of the number of atoms of Group 13 elements other than In and Ga to the total number of atoms of the Group 13 elements is, for example, 10% or less, preferably 5% or less, and more preferably 1% or less.

[0021] The first mixture is preferably substantially free of Ag salts, where "substantially" means that the ratio of the number of Ag atoms to the total number of Group 13 element atoms in the first mixture is, for example, 10% or less, preferably 5% or less, and more preferably 1% or less.

[0022] The total molar concentration of In and Ga contained in the first mixture may be, for example, 5 mmol / L or more and 200 mmol / L or less, preferably 20 mmol / L or more or 40 mmol / L or more, and may be 150 mmol / L or less, 100 mmol / L or less, or 80 mmol / L or less.

[0023] The first mixture is preferably in a solution state from the viewpoint of controlling the particle size of the first semiconductor nanoparticles. The first mixture in the form of a solution may be prepared, for example, by heat-treating a precursor mixture containing at least one compound selected from the group consisting of compounds having an In-S bond and compounds having a Ga-S bond, at least one compound selected from the group consisting of an In salt and a Ga salt, if necessary, and an organic solvent, at a temperature of 40°C to 150°C. The heat-treatment temperature may preferably be 60°C or higher, 80°C or higher, or 100°C or higher, and may be 160°C or lower, or 150°C or lower. The heat-treatment time may be, for example, 5 seconds to 60 minutes, and preferably 30 seconds to 30 minutes, 1 minute to 3 minutes, or 30 minutes or shorter, or 10 minutes or shorter.

[0024] In the second step, the first mixture is adjusted to a first temperature in the range of 40°C to 180°C, and mixed with a solution containing a silver (Ag) salt and an organic solvent (hereinafter also referred to as Ag solution) to obtain a second mixture. The first temperature may preferably be 60°C or higher, 80°C or higher, or 100°C or higher, and may be 160°C or lower, or 150°C or lower. The adjustment to the first temperature may be performed by raising or lowering the temperature of the first mixture.

[0025] The Ag salt contained in the Ag solution to be mixed with the first mixture may be either an organic acid salt or an inorganic acid salt. Examples of inorganic acid salts include nitrates, sulfates, hydrochlorides, and sulfonates. Examples of organic acid salts include formates, acetates, oxalates, and acetylacetonates. The Ag salt may be at least one selected from the group consisting of these salts, and more preferably at least one selected from the group consisting of organic acid salts such as acetates and acetylacetonates, as these salts have high solubility in organic solvents and allow the reaction to proceed more uniformly. The Ag salt may be used alone or in combination of two or more.

[0026] The organic solvent for dissolving the Ag salt may be the same as the organic solvent in the first mixture. The organic solvent for dissolving the Ag salt may be the same as or different from the organic solvent constituting the first mixture, and preferably the same. The Ag solution can be prepared by mixing the Ag salt with the organic solvent. The mixture of the Ag salt and the organic solvent may be heated as needed. The heating temperature may be, for example, 30°C or higher and 100°C or lower.

[0027] The concentration of the Ag salt in the Ag solution may be, for example, 5 mmol / L or more and 100 mmol / L or less, preferably 10 mmol / L or more, or 20 mmol / L or more, and may be 80 mmol / L or less, or 50 mmol / L or less.

[0028] The Ag solution may further contain, in addition to the Ag salt, other metal salts other than the Ag salt. Examples of other metal salts include copper (Cu) salts, lithium (Li) salts, sodium (Na) salts, and potassium (K) salts. When the Ag solution contains, for example, a Cu salt in addition to the Ag salt, the ratio of the number of Cu atoms to the total number of Ag and Cu atoms in the Ag solution (Cu / (Ag+Cu)) may be, for example, 0.01 or more and less than 1, preferably 0.02 or more, 0.05 or more, or 0.07 or more, and may be 0.8 or less, 0.7 or more, or 0.5 or less. When the ratio of the number of Ag atoms to the total number of Ag and Cu atoms is within a predetermined range, a long-wavelength emission peak wavelength (e.g., 600 nm or more) can be obtained.

[0029] The first mixture and the Ag solution can be mixed, for example, by adding the Ag solution to the first mixture heated to a predetermined first temperature. Mixing may be performed while stirring the first mixture, if necessary. The Ag solution may be added gradually to the first mixture, or all at once. Preferably, the Ag solution may be added in a short time, for example, 10 seconds or less, or 2 seconds or less. Mixing the first mixture and the Ag solution is preferably performed, for example, in an inert gas atmosphere. By using an inert gas atmosphere, it is possible to reduce or prevent the by-production of oxides and the oxidation of the surfaces of the resulting first semiconductor nanoparticles. The inert gas atmosphere may be, for example, a rare gas atmosphere such as argon, a nitrogen atmosphere, or the like.

[0030] The amount of Ag solution mixed into the first mixture may be such that the ratio of the total number of moles of In and Ga to the number of moles of Ag in the second mixture is, for example, 0.8 or more and 10 or less, preferably 0.9 or more, 1 or more, or 1.1 or more, or may be such that the ratio is 8 or less, 6 or less, or 4 or less.

[0031] The second step may include a first temperature maintenance step of maintaining the first temperature after mixing the Ag solution into the first mixture. The time for maintaining the first temperature may be, for example, 1 minute or more and 120 minutes or less, and preferably 5 minutes or more or 30 minutes or less. When the time for maintaining the first temperature is within the above range, the ratio of the total number of moles of Ag contained in the produced first semiconductor nanoparticles to the total number of moles of Ag contained in the second mixture (also referred to as Ag-based production yield) tends to be further improved.

[0032] In the third step, the second mixture is adjusted to a second temperature in the range of 130°C to 240°C, and the second temperature is maintained for 1 second or longer to heat-treat the second mixture, thereby obtaining first semiconductor nanoparticles. The second temperature at which the second mixture is heat-treated may preferably be 140°C or higher or 150°C or higher, and may be 220°C or lower or 200°C or lower. The second temperature may be higher than the first temperature. The difference between the second temperature and the first temperature may be, for example, 10°C or higher and 100°C or lower, preferably 20°C or higher or 40°C or higher, and preferably 80°C or lower or 60°C or lower. The rate of temperature adjustment from the first temperature to the second temperature may be, for example, 5°C / min to 1000°C / min, preferably 10°C / min to 30°C / min, and may be 500°C / min or lower or 100°C / min or lower.

[0033] The heat treatment time of the second mixture may preferably be 5 seconds or more, 10 seconds or more, 60 seconds or more, or 5 minutes or more, and may be 60 minutes or less, or 30 minutes or less. Here, the heat treatment time of the second mixture is started when the above-mentioned second temperature is reached and ended when the temperature-lowering operation is performed. The atmosphere in the third step may be, for example, an inert gas atmosphere. By using an inert gas atmosphere, it is possible to reduce or prevent the by-production of oxides and the oxidation of the surfaces of the obtained first semiconductor nanoparticles. The inert gas atmosphere may be, for example, a rare gas atmosphere such as argon, a nitrogen atmosphere, or the like.

[0034] The method for producing semiconductor nanoparticles may further include a cooling step of lowering the temperature of the resulting dispersion containing the first semiconductor nanoparticles following the above-mentioned step 3. The cooling step begins when the temperature-lowering operation is performed and ends when the temperature has been cooled to 50°C or below.

[0035] The method for producing semiconductor nanoparticles may further include a separation step of separating the first semiconductor nanoparticles from the dispersion, and may further include a purification step as necessary. In the separation step, for example, the dispersion containing the first semiconductor nanoparticles may be centrifuged to extract a supernatant containing the first semiconductor nanoparticles. In the purification step, for example, an appropriate organic solvent such as alcohol may be added to the supernatant obtained in the separation step, followed by centrifugation to extract the first semiconductor nanoparticles as a precipitate. The first semiconductor nanoparticles can also be extracted by volatilizing the organic solvent from the supernatant. The extracted precipitate may be dried, for example, by vacuum degassing, natural drying, or a combination of vacuum degassing and natural drying. Natural drying may be performed, for example, by leaving the mixture in the air at room temperature and normal pressure, in which case it may be left for 20 hours or more, for example, about 30 hours. The extracted precipitate may also be dispersed in an appropriate organic solvent.

[0036] In the method for producing semiconductor nanoparticles, a purification step involving the addition of an organic solvent such as an alcohol, a ketone solvent, or an ester solvent, followed by centrifugation may be performed multiple times as necessary. The alcohol used for purification may be a lower alcohol having 1 to 4 carbon atoms, such as methanol, ethanol, or n-propyl alcohol. Furthermore, the ketone solvent may be acetone or methyl ethyl ketone, and the ester solvent may be ethyl acetate or propyl acetate. When dispersing the precipitate in an organic solvent, the organic solvent may be a halogenated solvent such as chloroform, dichloromethane, dichloroethane, trichloroethane, or tetrachloroethane, or a hydrocarbon solvent such as toluene, cyclohexane, hexane, pentane, or octane. From the viewpoint of internal quantum yield, the organic solvent in which the precipitate is dispersed may be a halogenated solvent.

[0037] The first semiconductor nanoparticles obtained as described above may be in the form of a dispersion liquid or a dried powder. The first semiconductor nanoparticles may exhibit band-edge emission or defect emission. Alternatively, they may exhibit both band-edge emission and defect emission simultaneously. The semiconductor nanoparticles obtained by the method for producing semiconductor nanoparticles may be the first semiconductor nanoparticles, the second semiconductor nanoparticles obtained after the fourth step described below, or the third semiconductor nanoparticles obtained after the fifth step.

[0038] The average particle size of the first semiconductor nanoparticles obtained by the above-mentioned production method may be, for example, 2 nm or more and 8 nm or less, and preferably 3 nm or more or 6 nm or less. The standard deviation of the average particle size of the first semiconductor nanoparticles may be, for example, 0.6 nm or less, and preferably 0.5 nm or less or 0.4 nm or less. The lower limit of the standard deviation may be, for example, 0.1 nm or more. A method for measuring the average particle size of semiconductor nanoparticles will be described later.

[0039] The first semiconductor nanoparticles obtained by the method for producing semiconductor nanoparticles are produced by crystal transformation of composite particles, and therefore the Ag contained in the second mixture is efficiently utilized. That is, the method for producing semiconductor nanoparticles is excellent in terms of the production yield of the first semiconductor nanoparticles based on Ag. Specifically, the ratio of the total number of moles of silver (Ag) contained in the produced first semiconductor nanoparticles to the total number of moles of silver (Ag) contained in the second mixture (Ag-based production yield; %) may be, for example, 40% or more, preferably 50% or more, or 55% or more. This is also demonstrated by the fact that, for example, in a conventional method for producing first semiconductor nanoparticles by heat-treating a mixture containing Ag, at least one of In and Ga, and an S source, centrifugation was required to remove coarse particles produced as by-products, whereas in the production method according to this embodiment, the production of coarse particles is suppressed and centrifugation is not required.

[0040] The method for producing semiconductor nanoparticles may further include a step of disposing a second semiconductor containing gallium sulfide on the surfaces of first semiconductor nanoparticles obtained by the above-mentioned production method to obtain second semiconductor nanoparticles. That is, the method for producing semiconductor nanoparticles may include a fourth step of heat-treating a third mixture containing the first semiconductor nanoparticles obtained by the above-mentioned production method including steps 1 to 3, at a third temperature, and at least one selected from the group consisting of a first compound containing a gallium (Ga)-sulfur (S) bond and a mixture of a second compound containing gallium (Ga) but not sulfur (S) and a compound containing sulfur (S), and an organic solvent to obtain second semiconductor nanoparticles containing the first semiconductor and having the second semiconductor disposed on their surfaces. The second semiconductor nanoparticles may have a layer containing the second semiconductor disposed on the surfaces of the first semiconductor nanoparticles, or an attachment containing the second semiconductor disposed on the surfaces of the first semiconductor nanoparticles.

[0041] In the fourth step, a third mixture is prepared containing the first semiconductor nanoparticles, a Ga source and an S source comprising at least one selected from the group consisting of a first compound containing a Ga-S bond and a mixture of a second compound containing Ga but not S and a compound containing S, and an organic solvent, and the third mixture is heat-treated at a third temperature to obtain second semiconductor nanoparticles. The third mixture contains at least one Ga source and an S source selected from the group consisting of the first compound and a mixture of the second compound and a compound containing S. That is, the third mixture may contain, in addition to the first semiconductor nanoparticles and the organic solvent, at least one of the first compounds as the Ga source and the S source, at least one of the mixtures of the second compound and a compound containing S as the Ga source and the S source, or at least one of the first compounds and at least one of the mixtures of the second compound and a compound containing S as the Ga source and the S source.

[0042] The first compound is a compound having a Ga-S bond. The first compound may serve as both a Ga source and an S source for constituting the second semiconductor. Examples of the compound having a Ga-S bond include Ga salts of sulfur-containing compounds, which may be organic acid salts of Ga, inorganic acid salts, organometallic compounds, etc. Specific examples of sulfur-containing compounds include thiocarbamic acid, dithiocarbamic acid, thiocarbonates, dithiocarbonates (xanthogenic acid), trithiocarbonates, thiocarboxylic acids, dithiocarboxylic acids, and derivatives thereof. Among these, at least one selected from the group consisting of dithiocarbamic acid, xanthogenic acid, and derivatives thereof is preferred because it decomposes at a relatively low temperature. Specific examples of sulfur-containing compounds are the same as those described above. Specific examples of compounds having a Ga-S bond include gallium trisdimethyldithiocarbamate, gallium trisdiethyldithiocarbamate (Ga(DDTC)3), gallium chlorobisdiethyldithiocarbamate, and gallium ethylxanthogenate (Ga(EX)3). The third mixture may contain one compound having a Ga—S bond alone, or may contain two or more compounds in combination.

[0043] The second compound is a compound containing Ga but not S. The second compound may be a Ga source constituting the second semiconductor. The second compound may be a Ga salt, and may be either an organic acid salt or an inorganic acid salt of Ga. Specific examples of inorganic acid salts include nitrate and hydrochloride. Examples of organic acid salts include formate, acetate, oxalic acid, and acetylacetonate. The Ga salt may be at least one selected from the group consisting of these salts, and more preferably at least one selected from the group consisting of organic acid salts such as acetate and acetylacetonate, because they have high solubility in organic solvents and allow the reaction to proceed more uniformly. The third mixture may contain one type of second compound alone, or two or more types in combination.

[0044] The S-containing compound combined with the second compound to form the mixture may be an S source for the second semiconductor. Examples of S-containing compounds include diethyldithiocarbamate; thiourea; and alkylthioureas such as dimethylthiourea and diethylthiourea. Liquid compounds may also be used as the S-containing compound. Examples of S-containing liquid compounds include β-dithiones such as 4-pentanedithione; and dithiols such as 1,2-bis(trifluoromethyl)ethylene-1,2-dithiol. The S-containing compounds may be used singly or in combination of two or more. In the third mixture, a portion of the S-containing compound may be substituted with a compound containing a Group 16 element other than S. The ratio of the number of S atoms to the total number of Group 16 element atoms in the third mixture may be, for example, 90% or more, preferably 95% or more, or 99% or more.

[0045] The organic solvent constituting the third mixture may be the same as the organic solvent in the first mixture, and may be the same as or different from the organic solvent constituting the first mixture.

[0046] The third mixture can be prepared, for example, by mixing a mixture containing a Ga source and an S source, each of which is at least one selected from the group consisting of the first compound and a mixture of the second compound and a compound containing S, and an organic solvent, with a dispersion containing the first semiconductor nanoparticles.

[0047] The solvent for dispersing the first semiconductor nanoparticles can be any organic solvent. The organic solvent can be a surface modifier or a solution containing a surface modifier. For example, the organic solvent can be at least one selected from nitrogen-containing compounds having a hydrocarbon group with 4 to 20 carbon atoms. Alternatively, the organic solvent can be at least one selected from sulfur-containing compounds having a hydrocarbon group with 4 to 20 carbon atoms. Alternatively, the organic solvent can be a combination of at least one selected from nitrogen-containing compounds having a hydrocarbon group with 4 to 20 carbon atoms and at least one selected from sulfur-containing compounds having a hydrocarbon group with 4 to 20 carbon atoms. Preferred nitrogen-containing compounds include n-tetradecylamine and oleylamine because they are easily available in high purity and have a boiling point exceeding 290°C. Preferred sulfur-containing compounds include dodecanethiol. Specific organic solvents include oleylamine, n-tetradecylamine, dodecanethiol, or a combination thereof. The solvent for dispersing the first semiconductor nanoparticles can also be a halogen-based solvent such as chloroform.

[0048] The third mixture may have a concentration of the first semiconductor nanoparticles of, for example, 5.0×10 -7 5.0 x 10 moles / liter or more -5 moles / liter or less, especially 1.0 x 10 -6 moles / liter or greater, 1.0 x 10 -5 The third mixture may be prepared so that the concentration is 1 mole / liter or less. If the concentration of the first semiconductor nanoparticles in the third mixture is too low, it becomes difficult to recover the product by the aggregation and precipitation process in a poor solvent, and if it is too high, the rate of Ostwald ripening of the material constituting the core and fusion due to collision increases, and the particle size distribution tends to become broader. Here, the concentration of the first semiconductor nanoparticles is the molar concentration when one first semiconductor nanoparticle is considered to be a giant molecule, and the number of first semiconductor nanoparticles contained in 1 L of the dispersion is calculated using Avogadro's number (NA = 6.022 × 10 23 ) divided by .

[0049] The feed ratio of the Ga source and the S source in the third mixture may be determined to correspond to the stoichiometric composition ratio of the second semiconductor containing Ga and S, but it does not necessarily have to be the stoichiometric composition ratio. When the feed ratio is not the stoichiometric composition ratio, the raw materials may be fed in an amount in excess of the amount of the target second semiconductor to be produced. For example, the S source may be less than the stoichiometric composition ratio, and for example, the feed ratio (Ga:S) may be 1:1. Furthermore, the feed ratio (Ga:S) of the Ga source and the S source may be in the range of 1:1.5 to 1:1, corresponding to the composition formula Ga2S3.

[0050] The amounts of the Ga source and S source added to the third mixture may be selected taking into consideration the amount of first semiconductor nanoparticles contained in the third mixture so that the second semiconductor is arranged to a desired thickness on the first semiconductor nanoparticles. For example, the amounts of the Ga source and S source added may be determined so that a compound semiconductor having a stoichiometric composition consisting of Ga and S is produced in an amount of 1 μmol to 10 mmol, particularly 5 μmol to 1 mmol, per 10 nmol of the first semiconductor nanoparticles in terms of particle substance. The amounts of substance in terms of particles are as described above.

[0051] The third mixture may further contain at least one halogen compound, if necessary. Heat-treating the third mixture containing the halogen compound may further improve the luminous efficiency of the resulting second semiconductor nanoparticles. Examples of halogen compounds include organic compounds containing halogen atoms and inorganic compounds containing halogen atoms. Specific examples of halogen compounds will be described later. When the third mixture contains a halogen compound, the content of the halogen compound in the third mixture may be, for example, 0.1% by mass or more and 1.0% by mass or less, and preferably 0.15% by mass or more or 0.3% by mass or less. The molar ratio of the number of first semiconductor nanoparticles contained in the third mixture to the number of particles may be, for example, 3,000 to 50,000, and preferably 4,500 to 9,000.

[0052] A method for preparing a third mixture and heat-treating it at a third temperature to obtain second semiconductor nanoparticles may involve, for example, preparing a mixture in which a Ga source and an S source are dispersed or dissolved in an organic solvent, and then adding this mixture in small amounts, for example, dropwise, to a dispersion containing first semiconductor nanoparticles. In this case, the mixture may be added at a rate of 0.1 mL / hour to 10 mL / hour, particularly 1 mL / hour to 5 mL / hour. Alternatively, the mixture may be added to a heated dispersion. Specifically, for example, the dispersion may be heated until its peak temperature reaches a third temperature of 200°C to 310°C. After the third temperature is reached, the mixture is added in small amounts while maintaining the third temperature, and then the temperature is lowered to form the second semiconductor on the surface of the first semiconductor nanoparticles (slow injection method). The third temperature may be maintained as needed even after the addition of the mixture is completed.

[0053] When the third temperature is equal to or higher than the aforementioned temperature, the second semiconductor tends to be sufficiently formed due to reasons such as sufficient desorption of the surface modifier modifying the first semiconductor nanoparticles or sufficient progress of the chemical reaction for producing the second semiconductor. When the third temperature is equal to or lower than the aforementioned temperature, deterioration of the first semiconductor nanoparticles is suppressed, and good band-edge emission tends to be obtained. The total time for maintaining the third temperature can be, for example, from 1 minute to 300 minutes, or from 10 minutes to 120 minutes, from the start of addition of the mixed solution. The maintenance time for the third temperature is selected in relation to the third temperature. A longer maintenance time is selected when the third temperature is lower, and a shorter maintenance time is selected when the third temperature is higher, which facilitates the formation of a good second semiconductor. The rate of temperature increase and rate of temperature decrease are not particularly limited. The temperature decrease may be performed, for example, by maintaining the third temperature for a predetermined time, then stopping heating by a heat source (e.g., an electric heater), and allowing the mixture to cool.

[0054] Alternatively, the entire amount of the Ga source and the S source may be added directly to a dispersion containing the first semiconductor nanoparticles. Then, the dispersion containing the Ga source and the S source may be heated to form and arrange the second semiconductor on the surface of the first semiconductor nanoparticles (heating-up method). Specifically, the dispersion containing the Ga source and the S source may be heated, for example, gradually until the peak temperature reaches a third temperature of 200°C or higher and 310°C or lower, and then maintained at the third temperature for 1 minute to 300 minutes, followed by gradually lowering the temperature. The temperature increase rate may be, for example, 1°C / min to 50°C / min, and the temperature decrease rate may be, for example, 1°C / min to 100°C / min. Alternatively, the temperature increase rate may be controlled without particular control, and the mixture may be heated to a predetermined third temperature. Alternatively, the temperature decrease may be performed by stopping heating by the heat source and allowing the mixture to cool, rather than at a constant rate. The advantages of the third temperature being within the above range are as explained in the method of adding a mixed liquid (slow injection method) described above.

[0055] The heat treatment is preferably performed in an inert gas atmosphere, such as an argon atmosphere or a nitrogen atmosphere, which can reduce or prevent the by-production of oxides.

[0056] In this manner, the second semiconductor is disposed on the surface of the first semiconductor nanoparticles to form second semiconductor nanoparticles. The obtained second semiconductor nanoparticles may be separated from the solvent and, if necessary, further purified and dried. The methods for separation, purification, and drying are as described above, and therefore detailed descriptions thereof will be omitted here.

[0057] The method for producing semiconductor nanoparticles may further include a fifth step of heat-treating the second semiconductor nanoparticles at a fourth temperature in the presence of a halogen compound to obtain third semiconductor nanoparticles. Heat-treating the second semiconductor nanoparticles with a halogen compound may further improve the luminous efficiency. This may be because, for example, halogen ions produced from the halogen compound produce gallium halide, which has good solubility in solvents, thereby repairing lattice defects in the second semiconductor and forming a deposit or semiconductor layer with a well-ordered atomic arrangement.

[0058] Examples of halogen compounds include organic compounds containing halogen atoms and inorganic compounds containing halogen atoms. Examples of halogen atoms contained in halogen compounds include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, with chlorine atoms and bromine atoms being preferred. The halogen atoms contained in the halogen compounds may be one type alone or a combination of two or more types. Furthermore, the halogen compounds used in the fifth step may be one type alone or a combination of two or more types.

[0059] Examples of organic compounds containing halogen atoms include halogenated hydrocarbons and tetraalkylammonium halides. The number of carbon atoms in the organic compounds containing halogen atoms may be, for example, 1 to 20, preferably 1 to 12 or 1 to 6. Specific examples of halogenated hydrocarbons include dichloromethane, chloroform, tetrachloromethane, bromoform, hexachlorobenzene, and chlorobenzene. Specific examples of tetraalkylammonium halides include hexadecyltrimethylammonium chloride and hexadecyltrimethylammonium bromide.

[0060] Examples of inorganic compounds containing halogen atoms include hydrogen halides and metal halides. Hydrogen halides include hydrogen chloride and hydrogen bromide. Metal halides include gallium chloride and aluminum chloride.

[0061] Examples of methods for heat-treating the second semiconductor nanoparticles together with a halogen compound include mixing a dispersion containing the second semiconductor nanoparticles with a halogen compound to prepare a halogen mixture, and then heat-treating the prepared halogen mixture. Furthermore, the fifth step of heat-treating the second semiconductor nanoparticles together with a halogen compound may be carried out consecutively with the fourth step, or the temperature may be adjusted to the third temperature in the fourth step, followed by adding the halogen compound and heat-treating at the fourth temperature. Alternatively, the fourth and fifth steps may be carried out simultaneously by heat-treating the third mixture containing the halogen compound.

[0062] The heat treatment of the halogen mixture containing the second semiconductor nanoparticles and the halogen compound may be carried out only once, or may be carried out two or more times. When the heat treatment of the halogen mixture is carried out multiple times, the type and amount of the halogen compound used in each heat treatment may be the same or different, the heat treatment temperature may be the same or different, and the heat treatment time may be the same or different. In addition, the heat treatment of the halogen mixture multiple times may be carried out continuously, or may be carried out intermittently by lowering the temperature after each treatment.

[0063] The content of the halogen compound in the halogen mixture may be, for example, 0.1% by mass or more and 1.0% by mass or less, and preferably 0.15% by mass or more or 0.3% by mass or less. The ratio of the number of second semiconductor nanoparticles contained in the halogen mixture to the number of particles may be, for example, 3,000 to 50,000, and preferably 4,500 to 9,000.

[0064] The fourth temperature of the heat treatment in the fifth step may be, for example, 80° C. or more and 330° C. or less, preferably 180° C. or more or 200° C. or more, and may be 300° C. or less or 280° C. or less. The heat treatment time may be, for example, 10 minutes or more and 12 hours or less.

[0065] In this way, semiconductor nanoparticles are formed as third semiconductor nanoparticles (for example, core-shell type semiconductor nanoparticles having a core-shell structure). The obtained semiconductor nanoparticles may be separated from the dispersion liquid and, if necessary, further purified and dried. The methods for separation, purification, and drying are as explained above in relation to the first semiconductor nanoparticles, and therefore detailed explanations thereof will be omitted here.

[0066] The method for producing semiconductor nanoparticles may further include a sixth step of disposing a surface modifier on the second semiconductor nanoparticles obtained in the fourth step or the third semiconductor nanoparticles obtained in the fifth step. The sixth step may include, for example, contacting the second semiconductor nanoparticles or the third semiconductor nanoparticles with a surface modifier, or may include contacting the second semiconductor nanoparticles or the third semiconductor nanoparticles with a specific modifier containing phosphorus (P) having a negative oxidation state. This allows the production of semiconductor nanoparticles that exhibit band-edge emission with a superior quantum yield.

[0067] In the sixth step, the second or third semiconductor nanoparticles may be brought into contact with the surface modifier by mixing the second or third semiconductor nanoparticles with the surface modifier. The ratio of the surface modifier to the second or third semiconductor nanoparticles in the sixth step is, for example, 1×10 of the second or third semiconductor nanoparticles. -8 1 x 10 per mole -6 mol or more, preferably 2 × 10 -4 More than 5×10 moles -2 The contact temperature may be, for example, -80°C or higher and 300°C or lower, and preferably -40°C or higher and 200°C or lower. The contact time may be, for example, 10 seconds or longer and 10 days or shorter, and preferably 1 minute or longer and 1 day or shorter. The contact atmosphere may be air or an inert gas atmosphere. An inert gas atmosphere may be preferred, and an argon atmosphere or a nitrogen atmosphere may be more preferred.

[0068] Specific examples of the surface modifier used in the sixth step include amino alcohols having from 2 to 20 carbon atoms, ionic surface modifiers, nonionic surface modifiers, nitrogen-containing compounds having a hydrocarbon group having from 4 to 20 carbon atoms, sulfur-containing compounds having a hydrocarbon group having from 4 to 20 carbon atoms, oxygen-containing compounds having a hydrocarbon group having from 4 to 20 carbon atoms, and phosphorus-containing compounds having a hydrocarbon group having from 4 to 20 carbon atoms. One type of surface modifier may be used alone, or two or more different types may be used in combination.

[0069] The amino alcohol used as a surface modifier may be any compound having an amino group and an alcoholic hydroxyl group, and including a hydrocarbon group having 2 to 20 carbon atoms. The number of carbon atoms in the amino alcohol is preferably 10 or less, more preferably 6 or less. The hydrocarbon group constituting the amino alcohol may be derived from a hydrocarbon such as a linear, branched, or cyclic alkane, alkene, or alkyne. "Derived from a hydrocarbon" means that the amino alcohol is formed by removing at least two hydrogen atoms from a hydrocarbon. Specific examples of amino alcohols include aminoethanol, aminopropanol, aminobutanol, aminopentanol, aminohexanol, and aminooctanol. For example, when the amino group of the amino alcohol is bonded to the surface of a semiconductor nanoparticle and the hydroxyl group is exposed on the opposite outermost surface of the particle, the polarity of the semiconductor nanoparticle changes, improving dispersibility in alcoholic solvents (e.g., methanol, ethanol, propanol, butanol, etc.).

[0070] Examples of ionic surface modifiers used as surface modifiers include nitrogen-containing compounds, sulfur-containing compounds, and oxygen-containing compounds having an ionic functional group in the molecule. The ionic functional group may be either cationic or anionic, and preferably has at least a cationic group. Specific examples of surface modifiers and surface modification methods can be found in, for example, Chemistry Letters, Vol. 45, pp. 898-900, 2016.

[0071] The ionic surface modifier may be, for example, a sulfur-containing compound having a tertiary or quaternary alkylamino group. The number of carbon atoms in the alkyl group of the alkylamino group may be, for example, 1 to 4. The sulfur-containing compound may also be an alkyl or alkenyl thiol having 2 to 20 carbon atoms. Specific examples of the ionic surface modifier include hydrogen halide salts of dimethylaminoethanethiol, halogen salts of trimethylammoniumethanethiol, hydrogen halide salts of dimethylaminobutanethiol, and halogen salts of trimethylammoniumbutanethiol.

[0072] Examples of nonionic surface modifiers used as surface modifiers include nitrogen-containing compounds, sulfur-containing compounds, and oxygen-containing compounds having nonionic functional groups including alkylene glycol units and alkylene glycol monoalkyl ether units. The number of carbon atoms in the alkylene group in the alkylene glycol unit may be, for example, 2 to 8, and preferably 2 to 4. The number of repeating alkylene glycol units may be, for example, 1 to 20, and preferably 2 to 10. The nitrogen-containing compound constituting the nonionic surface modifier may have an amino group, the sulfur-containing compound may have a thiol group, and the oxygen-containing compound may have a hydroxyl group. Specific examples of nonionic surface modifiers include methoxytriethyleneoxyethanethiol and methoxyhexaethyleneoxyethanethiol.

[0073] Examples of nitrogen-containing compounds having a hydrocarbon group with 4 to 20 carbon atoms include amines and amides. Examples of sulfur-containing compounds having a hydrocarbon group with 4 to 20 carbon atoms include thiols. Examples of oxygen-containing compounds having a hydrocarbon group with 4 to 20 carbon atoms include carboxylic acids, alcohols, ethers, aldehydes, and ketones. Examples of phosphorus-containing compounds having a hydrocarbon group with 4 to 20 carbon atoms include trialkylphosphines, triarylphosphines, trialkylphosphine oxides, and triarylphosphine oxides.

[0074] The specific modifying agent also contains P, which has a negative oxidation number as a Group 15 element. The oxidation number of P is −1 when one hydrogen atom or hydrocarbon group is bonded to P, and +1 when one oxygen atom is bonded to P via a single bond, and changes depending on the substitution state of P. For example, the oxidation number of P in trialkylphosphines and triarylphosphines is −3, and in trialkylphosphine oxides and triarylphosphine oxides it is −1.

[0075] The specific modifier may contain, in addition to P having a negative oxidation number, other Group 15 elements, such as N, As, and Sb.

[0076] The specific modifying agent may be, for example, a phosphorus-containing compound having a hydrocarbon group having 4 to 20 carbon atoms. Examples of the hydrocarbon group having 4 to 20 carbon atoms include linear or branched saturated aliphatic hydrocarbon groups such as n-butyl, isobutyl, n-pentyl, n-hexyl, octyl, ethylhexyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl; linear or branched unsaturated aliphatic hydrocarbon groups such as oleyl; alicyclic hydrocarbon groups such as cyclopentyl and cyclohexyl; aromatic hydrocarbon groups such as phenyl and naphthyl; and arylalkyl groups such as benzyl and naphthylmethyl. Of these, saturated aliphatic hydrocarbon groups or unsaturated aliphatic hydrocarbon groups are preferred. When the specific modifying agent has multiple hydrocarbon groups, they may be the same or different.

[0077] Specific examples of the specific modifying agent include tributylphosphine, triisobutylphosphine, tripentylphosphine, trihexylphosphine, trioctylphosphine, tris(ethylhexyl)phosphine, tridecylphosphine, tridodecylphosphine, tritetradecylphosphine, trihexadecylphosphine, trioctadecylphosphine, triphenylphosphine, tributylphosphine oxide, triisobutylphosphine oxide, tripentylphosphine oxide, trihexylphosphine oxide, trioctylphosphine oxide, tris(ethylhexyl)phosphine oxide, tridecylphosphine oxide, tridodecylphosphine oxide, tritetradecylphosphine oxide, trihexadecylphosphine oxide, trioctadecylphosphine oxide, and triphenylphosphine oxide, and the specific modifying agent may contain at least one selected from the group consisting of these.

[0078] The contact of the second semiconductor nanoparticles or the third semiconductor nanoparticles with the specific modifier can be carried out, for example, by mixing a dispersion of the second semiconductor nanoparticles or the third semiconductor nanoparticles with the specific modifier. Alternatively, the second semiconductor nanoparticles or the third semiconductor nanoparticles may be mixed with a liquid specific modifier. A solution of the specific modifier may also be used. A dispersion of the second semiconductor nanoparticles can be obtained by mixing the second semiconductor nanoparticles with an appropriate organic solvent. Examples of organic solvents used for dispersion include halogenated solvents such as chloroform; aromatic hydrocarbon solvents such as toluene; and aliphatic hydrocarbon solvents such as cyclohexane, hexane, pentane, and octane. The concentration of the substance amount in the dispersion of the second semiconductor nanoparticles is, for example, 1×10 -7 mol / L or more 1×10 -3 mol / L or less, preferably 1×10 -6 mol / L or more 1×10 -4 mol / L or less.

[0079] The amount of the specific modifying agent used relative to the second semiconductor nanoparticles or the third semiconductor nanoparticles is, for example, 1 to 50,000 times in terms of molar ratio. -7 mol / L or more 1.0×10 -3 When a dispersion of second semiconductor nanoparticles having a concentration of mol / L or less is used, the dispersion and the specific modifying agent may be mixed at a volume ratio of 1:1000 to 1000:1.

[0080] The temperature during contact between the second semiconductor nanoparticles or the third semiconductor nanoparticles and the specific modifying agent may be, for example, -100°C or higher and 100°C or lower, or 30°C or higher and 75°C or lower. The contact time may be appropriately selected depending on the amount of the specific modifying agent used, the concentration of the dispersion, and the like. The contact time may be, for example, 1 minute or longer, preferably 1 hour or longer, and may be 100 hours or shorter, preferably 48 hours or shorter. The atmosphere during contact may be, for example, an inert gas atmosphere such as nitrogen gas or a rare gas.

[0081] semiconductor nanoparticles The semiconductor nanoparticles include a first semiconductor containing silver (Ag), at least one of indium (In) and gallium (Ga), and sulfur (S). A second semiconductor containing gallium (Ga) and sulfur (S) but substantially free of silver (Ag) is disposed on the surface of the semiconductor nanoparticles. The semiconductor nanoparticles exhibit band-edge emission with an emission peak wavelength in the wavelength range of 450 nm to 700 nm when irradiated with light having a wavelength of 365 nm, have a band-edge emission purity of 70% or more, and an internal quantum yield of the band-edge emission of 15% or more. The first semiconductor constituting the semiconductor nanoparticles has an average particle size with a standard deviation of 0.6 nm or less. The semiconductor nanoparticles may be obtained, for example, by the above-described method for producing semiconductor nanoparticles.

[0082] When irradiated with light having a wavelength of 365 nm, the semiconductor nanoparticles exhibit band-edge emission with a peak wavelength in the wavelength range of 450 nm to 700 nm, and exhibit high band-edge emission purity and high internal quantum yield of band-edge emission. This can be attributed, for example, to the fact that the crystal structure of the first semiconductor present in the center of the semiconductor nanoparticle is substantially tetragonal (chalcopyrite structure), and the second semiconductor disposed on the surface of the semiconductor nanoparticle has a crystal structure with few Ga defects (e.g., Ga-deficient portions). The second semiconductor may be a semiconductor with a higher Ga composition ratio than the first semiconductor, or a semiconductor with a lower Ag composition ratio than the first semiconductor, or may be a semiconductor consisting essentially of Ga and S. Furthermore, in the semiconductor nanoparticles, a deposit containing the second semiconductor may be disposed on the surface of a particle containing the first semiconductor, or the particle containing the first semiconductor may be coated with a deposit containing the second semiconductor. Furthermore, the semiconductor nanoparticles may have a core-shell structure in which, for example, a particle containing the first semiconductor serves as a core, and a deposit containing the second semiconductor serves as a shell, with the shell disposed on the surface of the core.

[0083] The first semiconductor constituting the semiconductor nanoparticles contains at least one of Ag, In, and Ga, as well as S. Generally, semiconductors containing Ag, In, and S and having a tetragonal, hexagonal, or orthorhombic crystal structure are introduced in literature as being represented by the composition formula AgInS2. However, in reality, the composition is not stoichiometric as represented by the general formula above. In particular, the ratio of the number of Ag atoms to the number of In and Ga atoms (Ag / In+Ga) may be less than 1, or conversely, may be greater than 1. Furthermore, the sum of the number of Ag atoms and the number of In and Ga atoms may not be the same as the number of S atoms. Therefore, in this specification, when a semiconductor containing a specific element is used, and it does not matter whether it is stoichiometric or not, the semiconductor composition will be expressed by a formula in which the constituent elements are connected by a "-", such as Ag-In-Ga-S. Therefore, the semiconductor composition of the semiconductor nanoparticles in this embodiment can be considered to be, for example, Ag-In-Ga-S or Ag-Ga-S, where some or all of the In, a Group 13 element, is replaced by Ga, also a Group 13 element.

[0084] A first semiconductor containing the above elements and having a hexagonal crystal structure is a wurtzite type, and a semiconductor having a tetragonal crystal structure is a chalcopyrite type. The crystal structure is identified, for example, by measuring an XRD pattern obtained by X-ray diffraction (XRD) analysis. Specifically, the XRD pattern obtained from the first semiconductor is compared with a known XRD pattern of semiconductor nanoparticles expressed by the composition AgInS2, or an XRD pattern obtained by simulation using crystal structure parameters. If any of the known patterns and simulated patterns matches the pattern of the first semiconductor, the crystal structure of the semiconductor nanoparticles can be said to be the crystal structure of the matching known or simulated pattern.

[0085] In an aggregate of semiconductor nanoparticles, semiconductor nanoparticles containing first semiconductors of different crystal structures may be present together. In this case, peaks derived from a plurality of crystal structures are observed in the XRD pattern. In one embodiment of the semiconductor nanoparticles, the first semiconductor may be substantially tetragonal, and peaks corresponding to the tetragonal crystal structure may be observed, while peaks derived from other crystal structures may not be observed substantially.

[0086] The total Ag content in the composition of the first semiconductor may be, for example, 10 mol% to 30 mol%, and preferably 15 mol% to 25 mol%. The total In and Ga content in the composition of the first semiconductor may be, for example, 15 mol% to 35 mol%, and preferably 20 mol% to 30 mol%. The total S content in the composition of the first semiconductor may be, for example, 35 mol% to 55 mol%, and preferably 40 mol% to 55 mol%.

[0087] The first semiconductor contains at least one of In and Ga, and may further contain at least one of Al and Tl by substitution of a portion thereof, or may be substantially composed of In and Ga. Here, "substantially" indicates that the ratio of the number of atoms of elements other than In and Ga to the total number of atoms of In and Ga and elements other than In and Ga is, for example, 10% or less, preferably 5% or less, and more preferably 1% or less.

[0088] The ratio of the number of In atoms to the total number of In and Ga atoms in the first semiconductor (In / (In+Ga)) may be, for example, 0.01 or more and less than 1, and preferably 0.1 or more and 0.99 or less. When the ratio of the number of In atoms to the total number of In and Ga atoms is within a predetermined range, a short wavelength emission peak wavelength (for example, 545 nm or less) can be obtained. Furthermore, the ratio of the number of Ag atoms to the total number of In and Ga atoms (Ag / (In+Ga)) may be, for example, 0.3 or more and 1.2 or less, and preferably 0.5 or more and 1.1 or less. The ratio of the number of S atoms to the total number of Ag, In, and Ga atoms (S / (Ag+In+Ga)) may be, for example, 0.8 or more and 1.5 or less, and preferably 0.9 or more and 1.2 or less.

[0089] The first semiconductor may contain S, a portion of which may be substituted to further contain at least one of Se and Te, or may be substantially composed of S. Here, "substantially" indicates that the ratio of the number of atoms of elements other than S to the total number of atoms of S and elements other than S is, for example, 10% or less, preferably 5% or less, and more preferably 1% or less.

[0090] The first semiconductor may be substantially composed of Ag, In, Ga, S, and elements that partially replace the aforementioned elements. Here, the term "substantially" is used in consideration of the fact that elements other than Ag, In, Ga, S, and the elements partially replacing the aforementioned elements are inevitably included due to the inclusion of impurities, etc.

[0091] The first semiconductor may have a composition represented by the following formula (1), for example. Ag q In r Ga (1-r) S (q+3) / 2 (1) Here, q and r satisfy 0.20 < q ≤ 1.2 and 0 < r < 1.

[0092] Due to the manufacturing method, the variation in the composition of each particle composed of the first semiconductor is small. As a result, the full width at half maximum in the emission spectrum can be made narrower. The variation in the composition of each particle composed of the first semiconductor can be evaluated, for example, by dividing the particles composed of the first semiconductor into a plurality of particle groups and analyzing the composition of each particle group. Conversely, it can also be considered that a narrow full width at half maximum in the emission spectrum indicates a small variation in the composition of each particle.

[0093] The semiconductor nanoparticles may have a second semiconductor disposed on their surface. The second semiconductor may include a semiconductor having a larger bandgap energy than the first semiconductor. The composition of the second semiconductor may have a larger molar content of Ga compared to the composition of the first semiconductor. The ratio of the molar content of Ga in the composition of the second semiconductor to the molar content of Ga in the composition of the first semiconductor may be, for example, greater than 1 and less than or equal to 5, preferably greater than or equal to 1.1, and also preferably less than or equal to 3.

[0094] Also, the composition of the second semiconductor may have a smaller molar content of Ag compared to the composition of the first semiconductor. The ratio of the molar content of Ag in the composition of the second semiconductor to the molar content of Ag in the composition of the first semiconductor may be, for example, greater than or equal to 0.1 and less than or equal to 0.7, preferably greater than or equal to 0.2, and also preferably less than or equal to 0.5. The ratio of the molar content of Ag in the composition of the second semiconductor may be, for example, less than or equal to 0.5, preferably less than or equal to 0.2, or less than or equal to 0.1, and may be substantially 0. Here, "substantially" means that when the total number of atoms of all elements contained in the second semiconductor is 100%, the ratio of the number of Ag atoms is, for example, 10% or less, preferably 5% or less, more preferably 1% or less.

[0095] In the semiconductor nanoparticles, the second semiconductor disposed on the surface may include a semiconductor containing Ga and S. The semiconductor containing Ga and S may be a semiconductor having a larger band gap energy than the first semiconductor.

[0096] In the composition of the semiconductor containing Ga and S contained in the second semiconductor, a portion of Ga may be substituted with at least one Group 13 element selected from the group consisting of boron (B), aluminum (Al), indium (In), and thallium (Tl), and a portion of S may be substituted with at least one Group 16 element selected from the group consisting of oxygen (O), selenium (Se), tellurium (Te), and polonium (Po).

[0097] The semiconductor containing Ga and S may be a semiconductor consisting essentially of Ga and S. Here, "substantially" means that when the total number of atoms of all elements contained in the semiconductor containing Ga and S is taken as 100%, the proportion of the number of atoms of elements other than Ga and S is, for example, 10% or less, preferably 5% or less, and more preferably 1% or less.

[0098] The semiconductor containing Ga and S may be configured by selecting its composition and the like depending on the band gap energy of the first semiconductor described above. Alternatively, if the composition and the like of the semiconductor containing Ga and S are determined first, the first semiconductor may be designed so that its band gap energy is smaller than that of the semiconductor containing Ga and S. Generally, a semiconductor made of Ag—In—S has a band gap energy of 1.8 eV or more and 1.9 eV or less.

[0099] Specifically, the semiconductor containing Ga and S may have a band gap energy of, for example, 2.0 eV to 5.0 eV, particularly 2.5 eV to 5.0 eV. The band gap energy of the semiconductor containing Ga and S may be greater than the band gap energy of the first semiconductor by, for example, about 0.1 eV to 3.0 eV, particularly about 0.3 eV to 3.0 eV, and more particularly about 0.5 eV to 1.0 eV. When the difference between the band gap energy of the semiconductor containing Ga and S and the band gap energy of the first semiconductor is equal to or greater than the lower limit, the proportion of emission other than band edge emission in the light emission from the semiconductor nanoparticles tends to decrease, and the proportion of band edge emission tends to increase.

[0100] The second semiconductor may contain oxygen (O) atoms. Semiconductors containing oxygen atoms tend to have a larger bandgap energy than the first semiconductor. The form of the second semiconductor containing oxygen atoms is not clear, but it may be, for example, Ga—OS, Ga2O3, etc.

[0101] The second semiconductor is an alkali metal (M) in addition to Ga and S. a ) The alkali metal contained in the second semiconductor may include at least lithium. When the second semiconductor includes an alkali metal, the ratio of the number of alkali metal atoms to the sum of the number of alkali metal atoms and the number of Ga atoms may be, for example, 0.01 or more and less than 1, or 0.1 or more and 0.9 or less. Furthermore, the ratio of the number of S atoms to the sum of the number of alkali metal atoms and the number of Ga atoms may be, for example, 0.25 or more and 0.75 or less.

[0102] The second semiconductor may have a crystal system similar to that of the first semiconductor, and its lattice constant may be the same as or close to that of the first semiconductor. A second semiconductor with a similar crystal system and a similar lattice constant (here, a second semiconductor whose lattice constant multiples are similar to that of the first semiconductor) may effectively coat the periphery of the first semiconductor. For example, the first semiconductor is generally tetragonal, but examples of similar crystal systems include tetragonal and orthorhombic. When Ag-In-S is tetragonal, its lattice constants are 0.5828 nm, 0.5828 nm, and 1.119 nm. The second semiconductor coating it is preferably tetragonal or orthorhombic, and its lattice constant or multiples thereof are similar to that of Ag-In-S. Alternatively, the second semiconductor may be amorphous.

[0103] Whether the second semiconductor is amorphous can be confirmed by observing the semiconductor nanoparticles with HAADF-STEM. When the second semiconductor is amorphous, specifically, a portion having a regular pattern, such as a striped or dotted pattern, is observed in the center, and surrounding portions that do not appear to have a regular pattern are observed in HAADF-STEM. With HAADF-STEM, substances with a regular structure, such as crystalline substances, are observed as having a regular pattern, while substances without a regular structure, such as amorphous substances, are not observed as having a regular pattern. Therefore, when the second semiconductor is amorphous, the second semiconductor can be observed as a portion that is clearly different from the first semiconductor (which may have a tetragonal or other crystalline structure), which is observed as having a regular pattern.

[0104] Furthermore, when the second semiconductor is made of Ga—S, Ga is a lighter element than Ag and In contained in the first semiconductor, and therefore the second semiconductor tends to be observed as a darker image than the first semiconductor in an image obtained with HAADF-STEM.

[0105] Whether the second semiconductor is amorphous or not can also be confirmed by observing the semiconductor nanoparticles of this embodiment with a high-resolution transmission electron microscope (HRTEM). In the image obtained with HRTEM, the first semiconductor portion is observed as a crystal lattice image (an image having a regular pattern), while the amorphous second semiconductor portion is not observed as a crystal lattice image, and is observed as a portion where black and white contrast is observed but no regular pattern is visible.

[0106] On the other hand, it is preferable that the second semiconductor does not form a solid solution with the first semiconductor. If the second semiconductor forms a solid solution with the first semiconductor, the two become integrated, and the mechanism of this embodiment, in which band-edge emission is obtained by disposing the second semiconductor on the surface of the semiconductor nanoparticles, is not achieved. For example, it has been confirmed that band-edge emission cannot be obtained from semiconductor nanoparticles even when stoichiometric or non-stoichiometric zinc sulfide (Zn-S) is disposed on the surface of semiconductor nanoparticles containing a first semiconductor made of Ag-In-S. In relation to Ag-In-S, Zn-S satisfies the above-mentioned conditions regarding band gap energy and provides type-I band alignment. Despite this, the failure to obtain band-edge emission from the specific semiconductor is presumably due to the formation of a solid solution between the first semiconductor and ZnS.

[0107] The semiconductor nanoparticles may have an average particle size of, for example, 50 nm or less. From the viewpoints of ease of production and the internal quantum yield of band-edge emission, the average particle size is preferably in the range of 1 nm to 20 nm, more preferably 1.6 nm to 8 nm, and particularly preferably 2 nm to 7.5 nm.

[0108] The average particle size of semiconductor nanoparticles may be determined, for example, from a transmission electron microscope (TEM) image. Specifically, the particle size of an individual particle refers to the longest line segment that connects any two points on the periphery of the particle observed in the TEM image and exists within the particle.

[0109] However, when the particles have a rod shape, the length of the minor axis is considered to be the particle size. Here, rod-shaped particles refer to particles that have a minor axis and a major axis perpendicular to the minor axis in a TEM image, and the ratio of the length of the major axis to the length of the minor axis is greater than 1.2. Rod-shaped particles are observed in TEM images as, for example, quadrangular, including rectangular, elliptical, or polygonal shapes. The cross-sectional shape of the rod, which is a plane perpendicular to the major axis, may be, for example, circular, elliptical, or polygonal. Specifically, for rod-shaped particles, the length of the major axis refers to the length of the longest line segment connecting any two points on the periphery of the particle in the case of an elliptical shape; and in the case of a rectangular or polygonal shape, refers to the length of the longest line segment connecting any two points on the periphery of the particle that is parallel to the longest side defining the periphery. The length of the minor axis refers to the length of the longest line segment connecting any two points on the periphery that is perpendicular to the line segment defining the length of the major axis.

[0110] The average particle size of semiconductor nanoparticles is determined by measuring the particle size of all measurable particles observed in a TEM image at magnifications of 50,000x to 150,000x and then calculating the arithmetic mean of those particle sizes. Here, "measurable" particles are those whose entire outline can be observed in a TEM image. Therefore, particles whose outline is "cut off" in a TEM image, where part of the particle outline is not included in the imaging range, are not measurable. If the number of measurable particles in a single TEM image is 100 or more, that TEM image is used to determine the average particle size. On the other hand, if the number of measurable particles in a single TEM image is less than 100, the imaging location is changed, additional TEM images are acquired, and the particle sizes of the 100 or more measurable particles in two or more TEM images are measured to determine the average particle size.

[0111] In the semiconductor nanoparticles, the portion consisting of the first semiconductor may be particulate and may have an average particle size of, for example, 10 nm or less, 8 nm or less, or less than 7.5 nm. The average particle size of the first semiconductor may be, for example, 1.5 nm or more and 10 nm or less, preferably 1.5 nm or more and less than 8 nm, or 1.5 nm or more and less than 7.5 nm. When the average particle size of the first semiconductor is equal to or less than the upper limit, a quantum size effect is easily obtained. The average particle size of the semiconductor nanoparticles in the portion consisting of the first semiconductor may be a value calculated as the average particle size of the first semiconductor nanoparticles in the method for producing semiconductor nanoparticles.

[0112] In the semiconductor nanoparticles, the standard deviation of the average particle size of the portion consisting of the first semiconductor may be, for example, 0.6 nm or less. The standard deviation of the average particle size of the portion consisting of the first semiconductor may preferably be 0.5 nm or less, or 0.4 nm or less, with the lower limit being, for example, 0.1 nm or more. A standard deviation of the average particle size of 0.6 nm or less means that the particle size distribution of the portion consisting of the first semiconductor is narrow. This allows the half-width in the emission spectrum to be narrower.

[0113] The thickness of the portion of the semiconductor nanoparticle made of the second semiconductor may be in the range of 0.1 nm to 50 nm, 0.1 nm to 10 nm, or 0.3 nm to 3 nm. When the thickness of the second semiconductor is equal to or greater than the lower limit, the effect of disposing the second semiconductor in the semiconductor nanoparticle is sufficiently obtained, and band-edge emission is easily obtained.

[0114] The average particle size of the first semiconductor and the thickness of the second semiconductor may be determined by observing the semiconductor nanoparticles, for example, with HAADF-STEM. In particular, when the second semiconductor is amorphous, the thickness of the second semiconductor portion, which is easily observed as a portion distinct from the first semiconductor, can be easily determined with HAADF-STEM. In this case, the particle size of the first semiconductor can be determined according to the method described above for semiconductor nanoparticles. When the thickness of the second semiconductor is not constant, the smallest thickness is taken as the thickness of the second semiconductor in the semiconductor nanoparticle.

[0115] The semiconductor nanoparticles preferably have a substantially tetragonal crystal structure. The crystal structure is identified by measuring the XRD pattern obtained by X-ray diffraction (XRD) analysis as described above. "Substantially tetragonal" means that the ratio of the height of the peak around 48°, which indicates hexagonal and orthorhombic crystals, to the height of the main peak around 26°, which indicates tetragonal crystals, is, for example, 10% or less, or 5% or less.

[0116] The semiconductor nanoparticles may exhibit band edge emission having a peak emission wavelength in the wavelength range of 450 nm to 700 nm when irradiated with light having a wavelength of 365 nm. In one embodiment, the range of the peak emission wavelength may preferably be 475 nm to 560 nm, 510 nm to 550 nm, or 515 nm to 545 nm. In another embodiment, the range of the peak emission wavelength may preferably be 600 nm to 700 nm, 640 nm to 690 nm, or 650 nm to 680 nm. Furthermore, when the semiconductor nanoparticles have a peak emission wavelength of 475 nm to 560 nm, the half width of their emission spectrum may be 45 nm or less, preferably 40 nm or less, 35 nm or less, or 30 nm or less. For example, when the emission peak wavelength is 600 nm or more and 700 nm or less, the half-width of the emission spectrum may be 100 nm or less, preferably 80 nm or less, 60 nm or less, or 55 nm or less. The lower limit of the half-width may be, for example, 15 nm or more. Furthermore, it is preferable that the lifetime of the emission of the main component (band edge emission) is 200 ns or less.

[0117] Here, the "luminescence lifetime" refers to the lifetime of luminescence measured using a device known as a fluorescence lifetime measurement device. Specifically, the "luminescence lifetime of the main component" is determined according to the following procedure. First, semiconductor nanoparticles are irradiated with excitation light to cause them to emit light, and the time-dependent change in the decay (afterglow) of light with a wavelength near the peak of the emission spectrum, for example, a wavelength within ±50 nm of the peak wavelength, is measured. The time-dependent change is measured from the point at which irradiation with the excitation light is stopped. The resulting decay curve is generally the sum of multiple decay curves resulting from relaxation processes such as luminescence and heat. Therefore, in this embodiment, assuming that three components (i.e., three decay curves) are included, parameter fitting is performed so that the decay curve can be expressed by the following equation when the luminescence intensity is I(t). Parameter fitting is performed using dedicated software. I(t) = A1exp(-t / τ1) + A2exp(-t / τ2) + A3exp(-t / τ3)

[0118] In the above formula, τ1, τ2, and τ3 of each component are the time required for the emission intensity to decay to 1 / e (36.8%) of the initial value, which corresponds to the emission lifetime of each component. τ1, τ2, and τ3 are arranged in order of shortest emission lifetime. Also, A1, A2, and A3 are the contribution rates of each component. For example, A x exp(-t / τ x When the component with the largest integral value of the curve represented by A is selected as the main component, the luminescence lifetime τ of the main component is 200 ns or less. Such luminescence is presumed to be band edge luminescence. x exp(-t / τ x ) from 0 to infinity. x ×τ x The component with the largest value is selected as the principal component.

[0119] Note that the deviation between the decay curves drawn by equations obtained by parameter fitting assuming that the luminescence decay curve contains three, four, or five components and the actual decay curve is not significantly different. Therefore, in this embodiment, when determining the luminescence lifetime of the main component, the number of components contained in the luminescence decay curve is assumed to be three, thereby avoiding the complexity of parameter fitting.

[0120] The emission of semiconductor nanoparticles may include defect emission (e.g., donor-acceptor emission) in addition to band-edge emission, but preferably consists essentially of band-edge emission alone. Defect emission generally has a long emission lifetime, a broad spectrum, and a peak at a longer wavelength than band-edge emission. Here, "substantially consisting of band-edge emission alone" means that the purity of the band-edge emission component in the emission spectrum (hereinafter also referred to as "band-edge emission purity") is 40% or more, preferably 70% or more, more preferably 80% or more, even more preferably 90% or more, and particularly preferably 95% or more. The upper limit of the purity of the band-edge emission component may be, for example, 100% or less, less than 100%, or 99% or less. The "purity of the band-edge emission component" is expressed by the following formula when parameter fitting is performed on the emission spectrum assuming that the peak shape of the band-edge emission follows a normal distribution, and the area of ​​the band-edge emission peak is calculated as a1 and the area of ​​the entire emission spectrum is calculated as a2. Purity of band edge emission component (%) = (a1 / a2) × 100 If the emission spectrum does not contain any band-edge emission, i.e., if it contains only defect emission, it is 0%, and if it contains only band-edge emission, it is 100%.

[0121] The internal quantum yield of band edge emission is defined as the internal quantum yield calculated using a quantum yield measurement device at a temperature of 25°C under the conditions of an excitation light wavelength of 450 nm and a fluorescence wavelength range of 470 nm to 900 nm, or the internal quantum yield calculated under the conditions of an excitation light wavelength of 365 nm and a fluorescence wavelength range of 450 nm to 950 nm, or the internal quantum yield calculated under the conditions of an excitation light wavelength of 450 nm and a fluorescence wavelength range of 500 nm to 950 nm, multiplied by the purity of the band edge emission component and divided by 100. The internal quantum yield of band edge emission of the semiconductor nanoparticles is, for example, 15% or more, preferably 50% or more, more preferably 60% or more, even more preferably 70% or more, and particularly preferably 80% or more.

[0122] The peak position of the band-edge emission emitted by semiconductor nanoparticles can be changed by changing the particle size of the semiconductor nanoparticles. For example, decreasing the particle size of the semiconductor nanoparticles tends to shift the peak wavelength of the band-edge emission to shorter wavelengths. Furthermore, decreasing the particle size of the semiconductor nanoparticles tends to decrease the half-width of the spectrum of the band-edge emission.

[0123] When the semiconductor nanoparticles exhibit defect luminescence in addition to band-edge luminescence, the intensity ratio of the band-edge luminescence may be, for example, 0.75 or more, preferably 0.85 or more, more preferably 0.9 or more, and particularly preferably 0.93 or more, and the upper limit may be, for example, 1 or less, less than 1, or 0.99 or less. The intensity ratio of the band-edge luminescence is expressed by the following formula when the emission spectrum is separated into two peaks, the band-edge luminescence peak and the defect luminescence peak, by performing parameter fitting assuming that the shapes of the band-edge luminescence peak and the defect luminescence peak are normal distributions, and the maximum peak intensities are b1 and b2, respectively. Band edge emission intensity ratio = b1 / (b1+b2) The band-edge emission intensity ratio is 0 when the emission spectrum does not contain any band-edge emission, i.e., contains only defect emission; 0.5 when the maximum peak intensities of the band-edge emission and defect emission are the same; and 1 when only band-edge emission is contained.

[0124] The semiconductor nanoparticles preferably have an absorption spectrum or excitation spectrum (also referred to as a fluorescence excitation spectrum) that exhibits an exciton peak. The exciton peak is a peak obtained by exciton generation, and its appearance in the absorption spectrum or excitation spectrum indicates that the particles have a small particle size distribution and are suitable for band-edge emission with few crystal defects. The steeper the exciton peak, the more particles with uniform particle size and few crystal defects are contained in the semiconductor nanoparticle aggregate. Therefore, the half-width of the emission is narrower, and the luminous efficiency is expected to improve. In the absorption spectrum or excitation spectrum of the semiconductor nanoparticles of this embodiment, the exciton peak is observed, for example, within a range of 400 nm to 550 nm, preferably 430 nm to 500 nm. The excitation spectrum for determining the presence or absence of an exciton peak may be measured by setting the observation wavelength near the peak wavelength.

[0125] The surface of the semiconductor nanoparticles may be modified with a surface modifier. Specific examples of surface modifiers include amino alcohols having 2 to 20 carbon atoms, ionic surface modifiers, nonionic surface modifiers, nitrogen-containing compounds having a hydrocarbon group having 4 to 20 carbon atoms, sulfur-containing compounds having a hydrocarbon group having 4 to 20 carbon atoms, oxygen-containing compounds having a hydrocarbon group having 4 to 20 carbon atoms, phosphorus-containing compounds having a hydrocarbon group having 4 to 20 carbon atoms, and halides of Group 2, Group 12, or Group 13 elements. The surface modifiers may be used alone or in combination of two or more different types. Details of the surface modifiers exemplified here are as described above.

[0126] The surface of the semiconductor nanoparticles may be surface-modified with a gallium halide. By surface-modifying the surface of the semiconductor nanoparticles with a gallium halide, the internal quantum yield of the band-edge emission is improved. Specific examples of the gallium halide include gallium chloride, gallium fluoride, gallium bromide, and gallium iodide.

[0127] The surface of the second semiconductor in the semiconductor nanoparticles may be surface-modified with a gallium halide, which improves the internal quantum yield of band-edge emission.

[0128] The emission of semiconductor nanoparticles surface-modified with gallium halide may include defect emission (donor-acceptor emission) in addition to band-edge emission, but is preferably substantially band-edge emission only. Substantially band-edge emission only means as described above for the semiconductor nanoparticles, and the purity of the band-edge emission component is preferably 70% or more, more preferably 80% or more, even more preferably 90% or more, and particularly preferably 95% or more.

[0129] The internal quantum yield of the band edge emission of semiconductor nanoparticles surface-modified with a gallium halide is measured as described above for the semiconductor nanoparticles. The internal quantum yield of the band edge emission is, for example, 15% or more, preferably 50% or more, more preferably 60% or more, even more preferably 70% or more, and particularly preferably 80% or more.

[0130] Light-emitting devices The light-emitting device includes a light conversion member and a semiconductor light-emitting element, and the light conversion member contains semiconductor nanoparticles (e.g., core-shell semiconductor nanoparticles) obtained by the manufacturing method described above. In this light-emitting device, for example, the semiconductor nanoparticles absorb a portion of the light emitted from the semiconductor light-emitting element, and light of a longer wavelength is emitted. Then, the light from the semiconductor nanoparticles and the remaining portion of the light emitted from the semiconductor light-emitting element are mixed, and the mixed light can be used as the light emitted by the light-emitting device.

[0131] The semiconductor nanoparticles obtained by the above-described manufacturing method have excellent luminous efficiency due to the manufacturing method. It is believed that the semiconductor nanoparticles produced by the above-described manufacturing method have improved luminous efficiency, for example, because the occurrence of lattice defects in the surface semiconductor layer (e.g., shell) is suppressed compared to core-shell semiconductor nanoparticles obtained by conventional manufacturing methods. The crystal structure of the surface semiconductor layer can be investigated by techniques such as X-ray diffraction. However, the presence or absence of lattice defects in the surface semiconductor layer is merely a slight difference in the crystal structure, and its analysis is considered technically difficult. Therefore, at present, it is technically impossible or hardly practical to specifically clarify the detailed aspects of the crystal structure of the surface semiconductor layer.

[0132] Specifically, a light-emitting device that emits white light can be obtained by using semiconductor light-emitting elements that emit blue-violet or blue light with a peak wavelength of approximately 400 nm to 490 nm and semiconductor nanoparticles that absorb blue light and emit yellow light. Alternatively, a white light-emitting device can be obtained by using two types of semiconductor nanoparticles: one that absorbs blue light and emits green light, and one that absorbs blue light and emits red light.

[0133] Alternatively, a white light-emitting device can be obtained by using a semiconductor light-emitting element that emits ultraviolet light with a peak wavelength of 400 nm or less and three types of semiconductor nanoparticles that absorb the ultraviolet light and emit blue light, green light, and red light, respectively. In this case, it is desirable to have all of the light from the light-emitting element absorbed and converted by the semiconductor nanoparticles so that the ultraviolet light emitted from the light-emitting element does not leak to the outside.

[0134] Alternatively, by using a material that emits blue-green light with a peak wavelength of approximately 490 nm or more and 510 nm or less, and using semiconductor nanoparticles that absorb the blue-green light and emit red light, a device that emits white light can be obtained.

[0135] Alternatively, the semiconductor light-emitting element may be one that emits visible light, for example, red light having a wavelength of 700 nm or more and 780 nm or less, and if the semiconductor nanoparticles are one that absorbs visible light and emits near-infrared light, a light-emitting device that emits near-infrared light can be obtained.

[0136] The semiconductor nanoparticles may be used in combination with other semiconductor quantum dots or other non-quantum dot phosphors (e.g., organic or inorganic phosphors). Other semiconductor quantum dots are, for example, the binary semiconductor quantum dots described in the Background Art section. Non-quantum dot phosphors include garnet-based phosphors such as aluminum garnet-based phosphors. Garnet-based phosphors include cerium-activated yttrium-aluminum-garnet-based phosphors and cerium-activated lutetium-aluminum-garnet-based phosphors. Other examples include nitrogen-containing calcium aluminosilicate phosphors activated with europium and / or chromium, europium-activated silicate-based phosphors, β-SiAlON-based phosphors, nitride-based phosphors such as CASN-based or SCASN-based phosphors, and LnSiN 11 rare earth nitride phosphors such as BaSi2O2N2:Eu or Ba3Si6O 12 Examples of phosphors that can be used include oxynitride phosphors such as N2:Eu; sulfide phosphors such as CaS, SrGa2S4, and ZnS; chlorosilicate phosphors; SrLiAl3N4:Eu phosphors; SrMg3SiN4:Eu phosphors; and manganese-activated fluoride complex phosphors such as K2(Si,Al)F6:Mn phosphors. In the formulas representing the phosphor compositions, multiple elements separated by commas (,) indicate that at least one of these multiple elements is contained in the composition. In addition, in the formulas representing the phosphor compositions, the part before the colon (:) represents the host crystal, and the part after the colon (:) represents the activator element.

[0137] In a light-emitting device, the light conversion member containing semiconductor nanoparticles may be, for example, a sheet- or plate-like member, or a member having a three-dimensional shape. An example of a member having a three-dimensional shape is a sealing member formed by filling a resin into a recess formed in a package of a surface-mounted light-emitting diode, in which a semiconductor light-emitting element is placed on the bottom surface of the recess, to seal the light-emitting element.

[0138] Another example of the light converting member is a resin member formed to surround the upper and side surfaces of the semiconductor light emitting element with a substantially uniform thickness when the semiconductor light emitting element is disposed on a flat substrate. Alternatively, yet another example of the light converting member is a resin member formed in a flat plate shape with a predetermined thickness on top of the semiconductor light emitting element and the resin member containing the reflector when the semiconductor light emitting element is surrounded by a resin member containing a reflector with its upper end being flush with the semiconductor light emitting element.

[0139] The light converting member may be in contact with the semiconductor light emitting element or may be provided at a distance from the semiconductor light emitting element. Specifically, the light converting member may be a pellet-shaped member, sheet-shaped member, plate-shaped member, or rod-shaped member that is disposed at a distance from the semiconductor light emitting element, or may be a member that is provided in contact with the semiconductor light emitting element, such as a sealing member, a coating member (a member that covers the light emitting element and is provided separately from the molding member), or a molding member (including, for example, a lens-shaped member).

[0140] Furthermore, when a light-emitting device uses two or more types of semiconductor nanoparticles that emit light at different wavelengths, the two or more types of semiconductor nanoparticles may be mixed in one light conversion member, or two or more light conversion members each containing only one type of semiconductor nanoparticle may be used in combination. In this case, the two or more types of light conversion members may form a laminated structure or may be arranged in a dotted or striped pattern on a plane.

[0141] An example of a semiconductor light-emitting device is an LED chip. The LED chip may have a semiconductor layer made of one or more materials selected from the group consisting of GaN, GaAs, InGaN, AlInGaP, GaP, SiC, ZnO, etc. A semiconductor light-emitting device that emits blue-violet light, blue light, or ultraviolet light may have a composition of, for example, In. X Al Y Ga 1-X-Y The semiconductor layer is a GaN-based compound represented by N(0≦X, 0≦Y, X+Y<1).

[0142] The light-emitting device of this embodiment is preferably incorporated into a liquid crystal display device as a light source. Because the band-edge emission of semiconductor nanoparticles has a short emission lifetime, a light-emitting device using such nanoparticles is suitable as a light source for a liquid crystal display device that requires a relatively fast response speed. Furthermore, the semiconductor nanoparticles of this embodiment can exhibit an emission peak with a narrow half-width as band-edge emission. Therefore, in a light-emitting device, blue light having a peak wavelength of 420 nm or more and 490 nm or less is obtained by a blue semiconductor light-emitting element, and green light having a peak wavelength of 510 nm or more and 550 nm or less, preferably 530 nm or more and 540 nm or less, and red light having a peak wavelength of 600 nm or more and 680 nm or less, preferably 630 nm or more and 650 nm or less is obtained by semiconductor nanoparticles; or in a light-emitting device, ultraviolet light having a peak wavelength of 400 nm or less is obtained by a semiconductor light-emitting element, and blue light having a peak wavelength of 430 nm or more and 470 nm or less, preferably 440 nm or more and 460 nm or less, green light having a peak wavelength of 510 nm or more and 550 nm or less, preferably 530 nm or more and 540 nm or less, and red light having a peak wavelength of 600 nm or more and 680 nm or less, preferably 630 nm or more and 650 nm or less is obtained by semiconductor nanoparticles, thereby making it possible to obtain a liquid crystal display device with good color reproducibility without using a dark color filter. The light emitting device may be used, for example, as a direct backlight or as an edge backlight.

[0143] Alternatively, a sheet, plate-like member, or rod made of resin, glass, or the like, containing semiconductor nanoparticles may be incorporated into a liquid crystal display device as a light conversion member independent of the light-emitting device.

[0144] electroluminescent element The electroluminescent device includes a cathode, a light-emitting layer containing semiconductor nanoparticles obtained by the manufacturing method described above, and Yang The light-emitting layer is disposed between the cathode and the anode. For details of the configuration of the electroluminescence element, reference can be made to, for example, JP 2022-018524 ​​A and JP 2020-161476 A.

[0145] The electroluminescent device may have a configuration in which, for example, a substrate, a cathode, an electron injection layer, a light-emitting layer, a hole transport layer, a hole injection layer, and an anode are stacked in this order. The light-emitting layer may contain an electron transport material in addition to semiconductor nanoparticles. The electroluminescent device may further have an electron transport layer between the electron injection layer and the light-emitting layer.

[0146] The substrate may be made of a light-transmitting or non-light-transmitting material. Examples of light-transmitting materials include glass, quartz, and resin films. Examples of resin film materials include polyimide, polyethylene terephthalate, polyethylene naphthalate, polypropylene, cycloolefin polymer, polyamide, polyethersulfone, polymethyl methacrylate, polycarbonate, and polyarylate. The average thickness of the substrate may be, for example, 0.001 mm or more and 30 mm or less.

[0147] In the case of a bottom-emission element in which light is extracted from the substrate side, the cathode is preferably made of a transparent, highly conductive material. In this case, the cathode can be made of a conductive transparent oxide such as indium tin oxide (ITO) or indium zinc oxide (IZO). The average thickness of the cathode can be, for example, 10 nm to 500 nm.

[0148] Examples of materials for the electron injection layer include zinc oxide (ZnO), lithium fluoride (LiF), lithium oxide (Li2O), titanium oxide (TiO2), silicon oxide (SiO2), tin oxide (SnO2), tungsten oxide (WO3), tantalum oxide (Ta2O3), zirconium oxide (ZrO2), hafnium oxide (HfO2), and aluminum oxide (Al2O3). Nanoparticles with an average particle size of 1 nm or more and 100 nm or less can be used to form the electron injection layer. The average thickness of the electron injection layer can be, for example, 5 nm or more and 200 nm or less.

[0149] Examples of materials constituting the electron transport layer include nitrogen-containing heterocyclic compounds such as triazine derivatives, pyridine derivatives, oxadiazole derivatives, triazole derivatives, and phenanthroline derivatives.

[0150] As the electron transport material constituting the light-emitting layer, for example, a compound containing a phosphine oxide group can be used. Specific examples of the compound containing a phosphine oxide group include 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (PO-T2T), [4'-(9H-carbazol-9-yl)-2,2'-dimethyl-(1,1'-biphenyl)-4-yl]diphenylphosphine oxide, {5-[9'H-(9,3':6',9"-terephthalcarbazol)-9'-yl]pyridin-3-yl}diphenylphosphine oxide, 2-(diphenylphosphine 2,7-bis(diphenylphosphoryl)-9,9'-spirobifluorene, 3-(diphenylphosphoryl)-9-[4-(diphenylphosphoryl)phenyl]-9H-carbazole, 2,7-bis(diphenylphosphoryl)-spiro[9H-fluorene-9,9'-quino[3.2.1-kl]phenoxazine], 2,7-bis(diphenylphosphoryl)-9-phenyl-9H-carbazole, bis[4-(N-carbazolyl)phenyl]phenylphosphine oxide, 2,7-bis(diphenylphosphoryl)-9,9'-spirobifluorene, 3-(diphenylphosphoryl)-9-[4-(diphenylphosphoryl)phenyl]-9H-carbazole, 2,7-bis(diphenylphosphoryl) 9-[3-(9H-carbazol-9-yl)phenyl]-3-(diphenylphosphoryl)-9H-carbazole, 9-[8-(diphenylphosphoryl)dibenzo[b,d]furan-2-yl]-9H-carbazole, 3,3',3"-phosphinylidintris(9-phenyl-9H -carbazole), 2,4,6-tris[3-(diphenylphosphinyl)phenyl]pyridine, 3,5-bis[3-(diphenylphosphinyl)phenyl]pyridine, 2,5-bis[3-(diphenylphosphinyl)phenyl]-1,3,4-oxadiazole, 3,5-bis[3-(diphenylphosphinyl)phenyl]-1,2,4-triazole, 4,7-bis[3-(diphenylphosphinyl)phenyl]-1,10-phenanthroline, etc. The average thickness of the light-emitting layer can be, for example, 5 nm or more and 200 nm or less.

[0151] Examples of materials constituting the hole transport layer include 4,4',4"-tris(carbazol-9-yl)triphenylamine (TCTA), 2,2'-bis(N-carbazole)-9,9'-spirobifluorene (CFL), 4,4'-bis(carbazole-9-yl)biphenyl (CBP), 4,4',4"-trimethyltriphenylamine, N,N,N',N'-tetraphenyl-1,1'-biphenyl-4,4'-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD1), and N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD1). Examples of suitable hole transport layers include N,N'-bis(4-methoxyphenyl)-1,1'-biphenyl-4,4'-diamine (TPD2), N,N,N',N'-tetrakis(4-methoxyphenyl)-1,1'-biphenyl-4,4'-diamine (TPD3), N,N'-di(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (α-NPD), and 4,4',4"-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA). The average thickness of the hole transport layer can be, for example, 10 nm or more and 500 nm or less.

[0152] Examples of materials constituting the hole injection layer include inorganic materials such as molybdenum oxide (MoO), vanadium oxide (VO), ruthenium oxide (RuO), rhenium oxide, tungsten oxide, and manganese oxide. Polymer organic materials such as PEDOT:PSS may also be used. PEDOT stands for poly(3,4-ethylenedioxythiophene), and PSS stands for poly(styrenesulfonic acid). The average thickness of the hole transport layer can be, for example, 1 nm or more and 500 nm or less.

[0153] In the case of a bottom-emission element in which light is extracted from the substrate side, a thin metal film can be used as the anode. Metal materials used for the anode include, for example, Al, Au, Pt, Ni, W, Cr, Mo, Fe, Co, and Cu. Furthermore, when light is extracted from the anode side, a conductive transparent oxide can be used. The average thickness of the anode can be, for example, 10 nm or more and 500 nm or less. [Example]

[0154] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0155] Example 1 Process 1 to Process 3 0.15 mmol of indium acetate (In(OAc)3) and 0.40 mmol of gallium trisdiethyldithiocarbamate (Ga(DDTC)3) were degassed in 10 mL of oleylamine and heated to 80 °C under an argon atmosphere to completely dissolve the mixture, yielding a first mixture. Separately, 0.20 mmol of silver acetate (Ag(OAc)) was dissolved in 1 mL of oleylamine with gentle heating to prepare an Ag solution, which was then loaded into a gas-tight syringe. The temperature controller of the heating device for the first mixture was then set to 150 °C. When the first temperature of 130 °C was reached, the silver acetate oleylamine solution (Ag solution) was injected all at once. The temperature dropped by about 5 °C during the injection, but quickly recovered, so the temperature was allowed to rise. After reaching a second temperature of 150 °C, the temperature was maintained for 20 minutes for heat treatment. The mixture was then allowed to cool, yielding a dispersion of first semiconductor nanoparticles. Thereafter, only the particle components were isolated by precipitation and re-dispersion using acetone and methanol as poor solvents and chloroform as a good solvent, and dispersed in 1 mL of hexane to obtain a dispersion of first semiconductor nanoparticles.

[0156] Steps 4 and 5 0.15 mmol of gallium acetylacetonate (Ga(acac)3), 0.15 mmol of 1,3-dimethylthiourea, and 0.05 mmol of gallium trisdiethyldithiocarbamate (Ga(DDTC)3) were added to 10 mL of oleylamine. Subsequently, 1 / 5 of the amount of the dispersion of the first semiconductor nanoparticles obtained above was added to obtain a third mixture. After degassing, the mixture was rapidly heated to 230 °C under an argon atmosphere, then heated to a third temperature of 280 °C at a rate of 2 °C / min, and maintained at the third temperature for 1 minute. The mixture was then allowed to cool to below 100 °C, and 50 μL of a 35 wt % HCl aqueous solution was added as a halogen compound. The mixture was then heated at a fourth temperature of 260 °C for 30 minutes. The resulting solution emitted green light. The particle components purified in the same manner as above were dispersed in 4 mL of chloroform to obtain a dispersion of semiconductor nanoparticles (third semiconductor nanoparticles) of Example 1.

[0157] In Examples 2 to 12 shown below, dispersions of first semiconductor nanoparticles were obtained in the same manner as in Example 1, except that the synthesis conditions for steps 1 to 3 were changed as shown in the table below. Furthermore, for steps 4 and 5, the conditions were changed as follows to obtain the respective semiconductor nanoparticles. An outline of the changes made to steps 4 and 5 is also shown in the remarks column of the table below.

[0158] Example 2 The semiconductor nanoparticles of Example 2 were obtained in the same manner as in Example 1, except that the first semiconductor nanoparticles obtained in the same manner as in Example 1 were dispersed in 1 mL of chloroform to form a dispersion of the first semiconductor nanoparticles, the fourth step was carried out in the same manner as in Example 1, and the fourth temperature in the fifth step was set to 280°C and the heat treatment time was set to 30 minutes.

[0159] Example 3 Semiconductor nanoparticles of Example 3 were obtained in the same manner as in Example 1, except that 0.41 mmol of hexadecyltrimethylammonium chloride was used as the halogen compound added in the fifth step.

[0160] Example 4 The semiconductor nanoparticles of Example 4 were obtained in the same manner as Example 1, except that in the fourth step, after the temperature reached 280°C, 1.75 mL of an oleylamine solution containing 0.35 mmol of gallium chloride as a halogen compound was added without lowering the temperature, and heat treatment was carried out at the fourth temperature of 280°C for 30 minutes.

[0161] Example 5 The semiconductor nanoparticles of Example 5 were obtained in the same manner as Example 1, except that in the fourth step, after the temperature reached 280°C, 1.5 mL of an oleylamine solution containing 0.30 mmol of gallium chloride as a halogen compound was added without lowering the temperature, and heat treatment was carried out at the fourth temperature of 280°C for 30 minutes.

[0162] Example 6 The semiconductor nanoparticles of Example 6 were obtained in the same manner as Example 1, except that 1.5 mL of an oleylamine solution containing 0.30 mmol of gallium chloride was added as the halogen compound added in the fifth step, and heat treatment was carried out at 280°C for 30 minutes.

[0163] Example 7 The semiconductor nanoparticles of Example 7 were obtained in the same manner as Example 1, except that in the fourth step, after the temperature reached 280°C, 1.5 mL of an oleylamine solution containing 0.30 mmol of gallium chloride as a halogen compound was added without lowering the temperature, and heat treatment was carried out at the fourth temperature of 280°C for 30 minutes.

[0164] In Example 7, the ratio of the total number of moles of silver contained in the isolated first semiconductor nanoparticles to the total number of moles of silver contained in the Ag solution injected in the second step (Ag-based production yield) was 58%.

[0165] Example 8 The semiconductor nanoparticles of Example 8 were obtained in the same manner as in Example 1, except that in the fourth step, after degassing the third mixture, 50 μL of chloroform was added under an argon atmosphere, and after the fourth step was completed, the mixture was allowed to cool to room temperature, and the fifth step was not performed.

[0166] Example 9 The semiconductor nanoparticles of Example 9 were obtained in the same manner as in Example 1, except that 1 mL of an oleylamine solution containing 0.09 mmol of gallium chloride was added as the halogen compound added in the fifth step, and heat treatment was carried out at 280°C for 30 minutes.

[0167] Example 10 The semiconductor nanoparticles of Example 10 were obtained in the same manner as Example 1, except that in the fourth step, after the temperature reached 280°C, 1.75 mL of an oleylamine solution containing 0.35 mmol of gallium chloride as a halogen compound was added without lowering the temperature, and heat treatment was carried out at the fourth temperature of 280°C for 30 minutes.

[0168] Examples 11 and 12 The semiconductor nanoparticles of Examples 11 and 12 were obtained in the same manner as Example 1, except that the conditions for steps 1 to 3 were changed as shown in the table below, and that in step 4, when the temperature reached 230°C, 1.75 mL of an oleylamine solution containing 0.35 mmol of gallium chloride as a halogen compound was added, and then the temperature was raised to the third temperature of 280°C at a rate of 2°C / min, and heat treatment was carried out for 30 minutes at the fourth temperature of 280°C without lowering the temperature.

[0169] In Example 12, the ratio of the total number of moles of silver contained in the isolated first semiconductor nanoparticles to the total number of moles of silver contained in the Ag solution injected in the second step (Ag-based production yield) was 60%.

[0170] [Table 1]

[0171] Comparative Example 1 In a reaction vessel, 0.2 mmol of silver acetate (AgOAc), 0.1 mmol of indium acetate (In(OAc)3), and 0.4 mmol of gallium diethyldithiocarbamate (Ga(DDTC)3) were mixed with 10 mL of distilled and purified oleylamine (OLA) to obtain a first mixture. The first mixture was heated to 80°C, degassed under vacuum, and then replaced with an argon atmosphere. The mixture was then heated to 150°C and maintained at 150°C for 30 minutes. The mixture was then allowed to cool to room temperature, and coarse particles were removed by centrifugation. Methanol was then added to the supernatant to precipitate the semiconductor nanoparticles that would become the cores, which were then recovered by centrifugation. The recovered solid was dispersed in 2 mL of oleylamine to obtain a dispersion of semiconductor nanoparticles of Comparative Example 1.

[0172] 0.1 mmol of gallium acetylacetonate (Ga(acac)3) and 0.1 mmol of 1,3-dimethylthiourea were weighed out and added to 8 mL of distilled and purified oleylamine. The oleylamine dispersion of semiconductor nanoparticles synthesized above was then added in an amount equivalent to 30 nmol of nanoparticles to obtain a third mixture. The resulting third mixture was degassed at approximately 60 °C and replaced with an argon atmosphere. The temperature was then rapidly increased to 230 °C (heating rate: approximately 60 °C / min). After 230 °C, the temperature was further increased to 280 °C at a rate of 2 °C / min and heat-treated at 280 °C for 30 minutes. The mixture was then allowed to cool to room temperature, and methanol was added to precipitate the core-shell semiconductor particles. After washing, the resulting semiconductor nanoparticles were dispersed in chloroform to obtain a dispersion of semiconductor nanoparticles with the second semiconductor attached, as in Comparative Example 1.

[0173] In Comparative Example 1, removal of coarse particles by centrifugation was required to obtain a dispersion of semiconductor nanoparticles before the second semiconductor was attached, whereas in the production method according to the example, removal of coarse particles by centrifugation was not required to obtain a dispersion of first semiconductor nanoparticles.

[0174] Reference example 1 A dispersion of first semiconductor nanoparticles was obtained in the same manner as in Example 1, except that the second temperature was changed to 180°C.

[0175] Measurement of emission spectrum The emission spectrum of the first semiconductor nanoparticles obtained above was measured, and the emission peak wavelength, half width, and emission quantum yield were calculated. The emission spectrum was measured using a JASCO FP-8600 spectrofluorometer, and the emission quantum yield was measured using a Hamamatsu Hodonics PMA-12 quantum efficiency measurement system at room temperature (25°C) with an excitation light wavelength of 450 nm, over a wavelength range of 460 nm to 1010 nm, and the emission quantum yield was calculated from a wavelength range of 480 nm to 950 nm.

[0176] The first semiconductor nanoparticles of Example 1 had an emission peak wavelength of 615 nm, a half width of 127 nm, and an emission quantum yield of 30%. The emission spectrum and absorption spectrum of the first semiconductor nanoparticles of Example 1 are shown in FIG.

[0177] The emission spectrum of the semiconductor nanoparticles of Example 1 obtained above was measured, and the band-edge emission peak wavelength, half-width, and emission quantum yield were calculated in the same manner as above. Furthermore, 0.5 mL of trioctylphosphine was added to the semiconductor nanoparticle dispersion and treated, after which the emission spectrum was measured and the emission quantum yield was calculated. Furthermore, the band-edge emission purity was calculated as follows. In the emission spectrum, only the band-edge emission portion was fitted to a Gaussian function, and the resulting area was calculated as A. Subsequently, the entire emission spectrum was numerically integrated, and the resulting area was calculated as B. The band-edge emission purity (%) was calculated as a percentage of A / B, which was the area of ​​the fitted Gaussian function divided by the area of ​​the entire emission spectrum.

[0178] The semiconductor nanoparticles of Example 1 had an emission peak wavelength of 532 nm, a half-width of 37 nm, an emission quantum yield of 52%, and a band-edge emission purity of 75.6%. After treatment with trioctylphosphine, the emission peak wavelength was 532 nm, a half-width of 37 nm, an emission quantum yield of 72%, and a band-edge emission purity of 73.3%. The emission spectrum and absorption spectrum of the semiconductor nanoparticles of Example 1 before treatment with trioctylphosphine are shown in Figure 2.

[0179] For the semiconductor nanoparticles obtained in Examples 2 to 12 and Comparative Example 1, the band-edge emission peak wavelength (nm), band-edge emission half-width (nm), band-edge emission purity (%), emission quantum yield (%), and emission quantum yield after phosphine treatment (%) were calculated in the same manner as above. The results are shown in Table 2. For the phosphine treatment, trioctylphosphine was used for the semiconductor nanoparticles of Example 1, and tributylphosphine was used for the semiconductor nanoparticles of Examples 4 and 10 to 12.

[0180] [Table 2]

[0181] Composition analysis The compositions of the first semiconductor nanoparticles and the second semiconductor nanoparticles obtained in Example 1 were analyzed using an inductively coupled plasma (ICP) optical emission spectrometer (Shimadzu Corporation, ICPS-7510). The results are shown in Table 3. Table 3 shows the composition ratios of indium (In), gallium (Ga), and sulfur (S) relative to silver (Ag) (1.00).

[0182] [Table 3]

[0183] The first semiconductor nanoparticles contain excess amounts of group 13 and group 16 elements. This is thought to be due to the adsorption of DDTC complexes of In and Ga on the surface (see, for example, Hoisang, W.; Uematsu, T.; Torimoto, T.; Kuwabata, S. Inorg. Chem., 2021, 60, 13101). On the other hand, the second semiconductor nanoparticles are generally within theoretically consistent values. For example, in this case, Ag(In 0.68 Ga 0.32 ) S2, the first semiconductor, Ga 0.67 S 0.99 The second semiconductor can be considered to have a composition in which the second semiconductor is attached.

[0184] Transmission electron microscope (TEM) observation The shapes of the semiconductor nanoparticles obtained above were observed using a transmission electron microscope (TEM, Hitachi High-Technologies Corporation, product name H-7650), and their average particle diameters were measured from TEM images at 80,000 to 150,000 magnifications. Here, a Hi-Res Carbon HRC-C10 STEM Cu100P grid (Oken Shoji Co., Ltd.) was used as the TEM grid. The shapes of the obtained particles are considered to be spherical or polygonal. The average particle diameter was determined by selecting three or more TEM images, measuring the particle diameters of all measurable nanoparticles contained in these images, i.e., all particles except for those in which the particle images were cut off at the edges of the images, and then calculating the arithmetic mean. In both the examples and the comparative examples described below, the particle diameters of nanoparticles at a total of 100 or more points were measured using three or more TEM images.

[0185] The first semiconductor nanoparticles of Example 1 had an average particle size of 3.6 nm with a standard deviation of 0.4 nm. The semiconductor nanoparticles of Example 1 had an average particle size of 6.3 nm with a standard deviation of 1.0 nm. On the other hand, the first semiconductor nanoparticles of Comparative Example 1 had an average particle size of 4.4 nm with a standard deviation of 0.8 nm. TEM images of the first semiconductor nanoparticles of Example 1 are shown in FIG. 3 and the second semiconductor nanoparticles of Example 1 are shown in FIG. 4.

[0186] The semiconductor nanoparticles of Example 1 were observed using a high-resolution transmission electron microscope (HRTEM; JEM-2100; manufactured by JEOL Ltd.). An HRTEM image is shown in Figure 5. As shown in Figure 5, since there is material in which no lattice fringes are observed around the particles in which lattice fringes are observed, it is believed that the crystalline first semiconductor nanoparticles are coated with an amorphous second semiconductor.

[0187] X-ray diffraction pattern The X-ray diffraction (XRD) patterns of the first semiconductor nanoparticles obtained in Example 1 and Reference Example 1 were measured using an X-ray diffractometer (SmartLab, manufactured by Rigaku Corporation), and the results are shown in FIG.

[0188] For the first semiconductor nanoparticles of Example 1, which were heat-treated at 150° C., the XRD pattern was broadened, suggesting that crystallization was insufficient or that the crystallite size was approximately 1 nm or less. On the other hand, for the first semiconductor nanoparticles of Reference Example 1, which were heat-treated at 180° C., a peak with a half-width specific to nanoparticles was observed at a position believed to represent an alloy of tetragonal AgInS and tetragonal AgGaS.

[0189] Example 13 Process 1 to Process 3 0.20 mmol of indium chloride (InCl3), 0.30 mmol of indium trisdiethyldithiocarbamate (In(DDTC)3), and 0.10 mmol of gallium trisdiethyldithiocarbamate (Ga(DDTC)3) were degassed in 10 mL of oleylamine and heated to 80 °C under an argon atmosphere to completely dissolve the mixture, yielding a first mixture. Separately, 0.225 mmol of silver acetate (Ag(OAc)) and 0.025 mmol of copper(II) acetate (Cu(OAc)2) were dissolved in 1 mL of oleylamine with gentle heating to prepare an Ag solution, which was then loaded into a gas-tight syringe. The temperature controller of the heating device for the first mixture was then set to 200 °C, and when the first temperature of 120 °C was reached, the Ag solution was injected all at once. The temperature dropped by about 5°C during the injection operation, but recovered quickly, so the temperature was continued to rise until it reached the second temperature of 200°C, at which point it was maintained for 20 minutes for heat treatment. The mixture was then allowed to cool, yielding a dispersion of first semiconductor nanoparticles. Subsequently, the particle components were isolated by precipitation and redispersion using acetone and methanol as poor solvents and chloroform as a good solvent, and dispersed in 1 mL of hexane to yield a dispersion of first semiconductor nanoparticles.

[0190] Steps 4 and 5 0.10 mmol of gallium trisdiethyldithiocarbamate (Ga(DDTC)3) and 0.20 mmol of gallium chloride were added to 10 mL of oleylamine. The solution was dehydrated and degassed by evacuating at 100 °C, and then the temperature controller was set to 230 °C under an argon atmosphere. When the temperature reached 160 °C, 200 μL of the first semiconductor nanoparticle dispersion was injected using a gas-tight syringe. After the solution reached 230 °C, the temperature was raised to a third temperature of 280 °C at a rate of 2 °C / min. Then, in the fifth step, an oleylamine solution containing 0.20 mmol of gallium chloride was injected using a gas-tight syringe. The fourth temperature was maintained for 30 minutes, and then the solution was allowed to cool to near room temperature. Only the particle components were isolated using methanol as a poor solvent and dispersed in 1 mL of chloroform to obtain a dispersion of semiconductor nanoparticles (third semiconductor nanoparticles) of Example 13.

[0191] Examples 14 and 15 In Examples 14 and 15, dispersions of the respective first semiconductor nanoparticles were obtained in the same manner as in Example 13, except that the synthesis conditions for steps 1 to 3 were changed as shown in Table 4. Note that Ag(DDTC) and Cu(DDTC) crystals dissolved in oleylamine but not in dioctyl phthalate, and therefore were crushed together with the solvent in a mortar and injected as a suspension.

[0192] Example 16 The amount of In(DDTC) in the first mixture was changed to 0.1 mmol, and the dispersion solvent for Ag(DDTC) and Cu(DDTC) was changed to octadecene. Since it did not dissolve in octadecene, it was crushed in a mortar and injected as a suspension. The reagent used in the fourth step was changed; 0.10 mmol of Ga(DDTC) and 0.10 mmol of elemental sulfur were mixed with 10 mL of oleylamine, and heating was performed using the same procedure as in Example 13. When the solution temperature reached 230 °C, an oleylamine solution containing 0.1 mmol of gallium chloride was injected. After reaching a third temperature of 280 °C, an oleylamine solution containing 0.40 mmol of gallium chloride was injected using a gas-tight syringe as the fifth step (the total amount of gallium chloride injected as a post-treatment was 0.50 mmol). After maintaining the third temperature for 30 minutes, the mixture was allowed to cool to room temperature, and the particle components were isolated. The mixture was dispersed in 1 mL of chloroform to obtain a dispersion of semiconductor nanoparticles (third semiconductor nanoparticles) of Example 16.

[0193] Example 17 Steps 1 to 3 were carried out in the same manner as in Example 16. The concentration of the reagent used in Step 4 was changed; 0.20 mmol of Ga(DDTC)3 and 0.20 mmol of elemental sulfur were mixed with 10 mL of oleylamine, and heating was initiated in the same manner as in Example 16. When the solution temperature reached 160°C, 400 μL of the first semiconductor nanoparticle dispersion was injected using a syringe. When the solution temperature reached 230°C, an oleylamine solution containing gallium chloride at a concentration of 0.2 mmol / mL was added dropwise using a syringe pump. The temperature was raised to a third temperature of 280°C at a rate of 2°C / min, maintained at that temperature for 30 minutes, and then allowed to cool to near room temperature. The particle components were isolated and dispersed in 1 mL of chloroform to obtain a dispersion of semiconductor nanoparticles (third semiconductor nanoparticles) of Example 17.

[0194] Example 18 The first step was carried out in the same manner as in Example 16, and in the second step, Ag(DDTC), Cu(DDTC), and octadecene were added and ground in a planetary ball mill to obtain a dispersion. In the third step, after reaching a second temperature of 200 °C, the same temperature was maintained for 60 minutes. After cooling to room temperature, the nanoparticle components were isolated using the same procedure as in Example 16 to obtain a first semiconductor nanoparticle dispersion. The fourth step was carried out using the same procedure as in Example 16, and when the temperature reached 230 °C, an oleylamine solution containing 0.50 mmol of gallium chloride was added. After reaching a third temperature of 280 °C, an oleylamine solution containing 0.50 mmol of gallium chloride was injected using a gas-tight syringe in the fifth step, and the fourth temperature of 280 °C was maintained for 60 minutes (the total amount of gallium chloride injected as a post-treatment was 0.60 mmol). The particle components were isolated after cooling to room temperature and dispersed in 1 mL of chloroform to obtain a dispersion of semiconductor nanoparticles (third semiconductor nanoparticles) of Example 18.

[0195] Example 19 The first step was carried out in the same manner as in Example 16, and in the second step, the temperature (first temperature) at which the octadecene dispersion of Ag(DDTC) and Cu(DDTC) (prepared without using a ball mill) was injected into the first mixture was changed to 160°C. The third step was carried out using the same procedure as in Example 16. Note that the fourth step and subsequent steps were carried out using the same procedure as in Example 18 (the total amount of gallium chloride injected as a post-treatment was 0.60 mmol), and a dispersion of semiconductor nanoparticles (third semiconductor nanoparticles) of Example 19 was obtained.

[0196] Examples 20 and 21 Based on Example 19, the amounts of Ag(DDTC) and Cu(DDTC) in the octadecene dispersion of Ag(DDTC) and Cu(DDTC) added in the second step were changed as shown in Table 4, to obtain dispersions of semiconductor nanoparticles for Examples 20 and 21.

[0197] Example 22 Example 22 was prepared based on Example 19, but the amounts of substances in the first mixture were changed as shown in Table 4. The second step and subsequent steps were carried out in the same manner as in Example 19, to obtain a dispersion of semiconductor nanoparticles.

[0198] [Table 4]

[0199] The luminescence properties of the semiconductor nanoparticles obtained above were evaluated. The results are shown in Table 5. The luminescence spectra of the first semiconductor nanoparticles (core) and the third semiconductor nanoparticles (core / shell) obtained in Example 17 are shown in Figure 7.

[0200] [Table 5]

[0201] Reference example 2 First semiconductor nanoparticles were prepared under the same conditions as in Example 4. That is, after the temperature of the first mixture reached a first temperature of 130°C, an Ag solution was injected, and the temperature was raised to a second temperature of 200°C, and then maintained at that temperature for 20 minutes to perform heat treatment to prepare first semiconductor nanoparticles. After the Ag solution was injected, samples were taken at the following time points: immediately after reaching 130°C, 160°C, and 200°C, after maintaining at 200°C for 5 minutes, and after maintaining at 200°C for 20 minutes. The obtained samples were evaluated using TEM images, absorption spectra, emission spectra, compositional analysis by ICP, and XRD.

[0202] Immediately after the Ag solution was injected at the first temperature, the reaction solution turned dark brown. TEM images confirmed the presence of nanoparticles at this point. The absorption spectrum showed a left-sloping trend with an absorption edge at 700 nm, consistent with the characteristics of Ag2S nanoparticles. However, composition analysis revealed that the nanoparticles contained In and Ga at this point, and were not pure Ag2S nanoparticles. XRD analysis then yielded a diffraction pattern consistent with the characteristics of InGaS. This confirmed the simultaneous presence of Ag2S and InGaS. Subsequent conversion to Ag-In-Ga-S occurred before the second temperature was reached, suggesting that Ag2S and InGaS do not exist as separate particles, but rather coexist in a core / shell structure or a similar morphology.

[0203] Example 23 Process 1 to Process 3 0.3 mmol of indium chloride (InCl3) and 0.40 mmol of gallium trisdiethyldithiocarbamate (Ga(DDTC)3) were degassed in 10 mL of oleylamine and heated to 80 °C under an argon atmosphere to completely dissolve, yielding a first mixture. Separately, 0.25 mmol of silver acetate (Ag(OAc)) was dissolved in 1 mL of oleylamine with gentle heating and filled into a gas-tight syringe. The temperature controller of the heating device for the first mixture was then set to 130 °C. When the first temperature of 130 °C was reached, the silver acetate oleylamine solution was injected all at once. The first temperature was maintained for 10 minutes, and then the temperature controller was set to 200 °C. After the second temperature of 200 °C was reached, the temperature was maintained for 20 minutes for heat treatment. The mixture was then allowed to cool, yielding a dispersion of first semiconductor nanoparticles. Thereafter, only the particle components were isolated by precipitation and re-dispersion using acetone and methanol as poor solvents and chloroform as a good solvent, and dispersed in 1 mL of hexane to obtain a dispersion of first semiconductor nanoparticles.

[0204] Steps 4 and 5 0.10 mmol of gallium trisdiethyldithiocarbamate (Ga(DDTC)3) and 0.1 mmol of elemental sulfur (S) were added to 10 mL of oleylamine. After degassing, the temperature controller was set to 230 °C under an argon atmosphere, and when the temperature of the solution reached 170 °C, 1 / 5 of the obtained dispersion of first semiconductor nanoparticles was added. After reaching 230 °C, the temperature was raised to a third temperature of 280 °C at a rate of 2 °C / min, and then 1.5 mL of an oleylamine solution containing 0.60 mmol of gallium chloride as a halogen compound was added, and heat treatment was performed for 30 minutes at a fourth temperature of 280 °C. After cooling, the obtained solution exhibited green luminescence. The particle components after purification in the same manner as above were dispersed in 1 mL of chloroform to obtain a dispersion of semiconductor nanoparticles (third semiconductor nanoparticles) of Example 23.

[0205] The Ag-based production yield of the first semiconductor nanoparticles in Example 23 was 75%.

[0206] Example 24 The first to third steps were carried out in the same manner as in Example 23, except that in the second step, the first temperature at which the silver acetate oleylamine solution of Example 23 was injected was changed to 100°C. The holding time at the first temperature was 10 minutes. The fourth and fifth steps were carried out in the same manner as in Example 23, except that the composition of the third mixture was changed as shown in Table 6, to obtain a dispersion of semiconductor nanoparticles (third semiconductor nanoparticles) of Example 24.

[0207] The Ag-based production yield of the first semiconductor nanoparticles in Example 24 was 77%.

[0208] Example 25 Process 1 to Process 3 0.05 mmol of indium chloride (InCl3), 0.40 mmol of gallium trisdiethyldithiocarbamate (Ga(DDTC)3), and 0.10 mmol of gallium chloride (GaCl3) were degassed in 10 mL of oleylamine and heated to 80 °C under an argon atmosphere to completely dissolve the mixture, yielding a first mixture. Separately, 0.10 mmol of silver acetate (Ag(OAc)) was dissolved in 1 mL of oleylamine with gentle heating and filled into a gas-tight syringe. The temperature controller of the heating device for the first mixture was then set to 210 °C. When the first temperature of 130 °C was reached, the silver acetate oleylamine solution was injected all at once. After reaching a second temperature of 210 °C, the temperature was maintained for 20 minutes for heat treatment. The mixture was then allowed to cool, yielding a dispersion of first semiconductor nanoparticles. Thereafter, only the particle components were isolated by precipitation and re-dispersion using acetone and methanol as poor solvents and chloroform as a good solvent, and dispersed in 1 mL of hexane to obtain a dispersion of first semiconductor nanoparticles.

[0209] Steps 4 and 5 0.10 mmol of gallium trisdiethyldithiocarbamate (Ga(DDTC)3), 0.1 mmol of elemental sulfur (S), and 0.05 mmol of aluminum chloride (AlCl3) were added to 10 mL of oleylamine. After degassing, the temperature controller was set to 230 °C under an argon atmosphere. When the solution temperature reached 170 °C, 1 / 5 of the resulting first semiconductor nanoparticle dispersion was added. After reaching 230 °C, the temperature was increased to a third temperature of 280 °C at a rate of 2 °C / min. The temperature was then lowered again to 230 °C, and 0.375 mL of an oleylamine solution containing 0.10 mmol of aluminum chloride was added. The mixture was then heated at the same temperature for 10 minutes. The temperature was then raised again to 280 °C, and 1.125 mL of an oleylamine solution containing 0.3 mmol of gallium chloride was added. The mixture was then heated at the same temperature for 30 minutes. After cooling, the resulting solution emitted blue light. The particle components that had been purified in the same manner as above were dispersed in 1 mL of chloroform to obtain a dispersion of semiconductor nanoparticles of Example 25 (third semiconductor nanoparticles).

[0210] Example 26 A dispersion of semiconductor nanoparticles (third semiconductor nanoparticles) of Example 25 was obtained in the same manner as in Example 25, except that the second step was changed as follows.

[0211] In the second step, 0.20 mmol of silver acetate was injected at 130°C, and then the mixture was maintained at 150°C for 10 minutes. The temperature controller was then set to 240°C, and after reaching a second temperature of 240°C, the mixture was heat-treated by maintaining that temperature for 30 minutes. The mixture was then allowed to cool, yielding a dispersion of first semiconductor nanoparticles. Subsequently, the particle components were isolated by precipitation and redispersion using acetone and methanol as poor solvents and chloroform as a good solvent, and dispersed in 1 mL of hexane to obtain a dispersion of first semiconductor nanoparticles.

[0212] [Table 6]

[0213] The luminescence properties were evaluated for the semiconductor nanoparticles obtained in Examples 23 to 26. The results are shown in Table 7.

[0214] [Table 7]

[0215] The disclosure of Japanese Patent Application No. 2022-022901 (filing date: February 17, 2022) is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. Preparing a first mixture containing at least one compound selected from the group consisting of a compound having an indium (In)-sulfur (S) bond and a compound having a gallium (Ga)-sulfur (S) bond, and an organic solvent; adjusting the first mixture to a first temperature in the range of 40° C. to 180° C., and mixing the first mixture with a solution containing a silver (Ag) salt and an organic solvent to obtain a second mixture containing composite particles of silver sulfide and a sulfide containing at least one of indium and gallium; adjusting the second mixture to a second temperature in the range of 130°C or higher and 240°C or lower, and maintaining the second temperature for one second or longer to heat-treat the second mixture, thereby obtaining first semiconductor nanoparticles.

2. The method according to claim 1 , wherein the first mixture further contains at least one selected from the group consisting of an indium (In) salt and a gallium (Ga) salt.

3. 2. The manufacturing method according to claim 1, comprising heat-treating a precursor mixture containing at least one compound selected from the group consisting of a compound having an indium (In)-sulfur (S) bond and a compound having a gallium (Ga)-sulfur (S) bond, and an organic solvent, at a temperature of 40° C. or higher and 150° C. or lower to obtain a first mixture that is a solution.

4. The method according to claim 1 , wherein the first mixture contains silver (Ag) atoms in a ratio of 10% or less to the total number of atoms of the Group 13 elements.

5. 2. The method according to claim 1, wherein the ratio of the total number of moles of indium (In) and gallium (Ga) to the number of moles of silver (Ag) in the second mixture is 0.8 or more and 10 or less.

6. The manufacturing method according to claim 1 , wherein the ratio of the total number of moles of silver (Ag) contained in the first semiconductor nanoparticles to the total number of moles of silver (Ag) contained in the second mixture is 40% or more.

7. Preparing first semiconductor nanoparticles by the manufacturing method according to any one of claims 1 to 6; and heat-treating a third mixture containing the first semiconductor nanoparticles, at least one compound selected from the group consisting of a first compound containing a gallium (Ga)-sulfur (S) bond, and a mixture of a second compound containing gallium (Ga) but not sulfur (S) and a compound containing sulfur (S), and an organic solvent to obtain second semiconductor nanoparticles.

8. The method for producing semiconductor nanoparticles according to claim 7 , further comprising heat treating the second semiconductor nanoparticles with a halogen compound.

9. A semiconductor nanoparticle including a first semiconductor containing silver (Ag), at least one of indium (In) and gallium (Ga), and sulfur (S), wherein a second semiconductor containing gallium (Ga) and sulfur (S) is disposed on a surface of the semiconductor nanoparticle; The second semiconductor has a ratio of the number of silver (Ag) atoms to the number of atoms of all elements contained in the second semiconductor of 10% or less, the semiconductor nanoparticles exhibit band edge emission having an emission peak wavelength in a wavelength range of 450 nm to 700 nm when irradiated with light having a wavelength of 365 nm, have a band edge emission purity of 70% or more, and have an internal quantum yield of the band edge emission of 15% or more; The first semiconductor is semiconductor nanoparticles having an average particle size with a standard deviation of 0.6 nm or less.

10. A light-emitting device comprising: a light conversion member containing the semiconductor nanoparticles according to claim 9; and a semiconductor light-emitting element.

11. 10. An electroluminescence device comprising: a cathode; a light-emitting layer containing the semiconductor nanoparticles according to claim 9; and an anode, wherein the light-emitting layer is disposed between the cathode and the anode.

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