Method for producing semiconductor nanoparticles

Abstract

Disclosed is a method for producing semiconductor nanoparticles, wherein a precursor material for semiconductor nanoparticles is reacted in a liquid phase in a solvent that contains a poly-α-olefin oil (PAO). The PAO has a boiling point of 320°C or higher.

Description

Method for manufacturing semiconductor nanoparticles

[0001] This invention relates to a method for producing semiconductor nanoparticles.

[0002] In recent years, semiconductor light-emitting materials have been widely used as light-emitting materials in lighting and display devices, as well as as wavelength conversion (color conversion, downconversion) elements and as photoelectric conversion materials in photoelectric conversion elements. These fields require materials with high durability (e.g., stability against water, oxygen, heat, etc.) and high light absorption. For this reason, chalcogenide perovskites have attracted attention as this type of semiconductor light-emitting material because they have superior durability and a high light absorption coefficient compared to other materials, and do not contain harmful metals such as cadmium (see, for example, Non-Patent Documents 1 and 2 and Patent Documents 1 and 2).

[0003] For example, Non-Patent Documents 1 and 2 disclose chalcogenide perovskites synthesized by solid-phase synthesis. While the synthesis of fine particles by solid-phase synthesis is a widely known method, it has problems such as the ease with which impurities are introduced during the synthesis process and significant particle aggregation. For this reason, it is difficult to miniaturize the particle size of particles obtained by solid-phase synthesis, and it is difficult to control the particle size and shape, resulting in a wide particle size distribution. Furthermore, solid-phase synthesis generally yields particles of micron size, and when these are further pulverized to nanoparticles, numerous defects occur on the surface and inside the particles, resulting in a significant decrease in fluorescence intensity.

[0004] In contrast, liquid-phase synthesis is attracting attention as a method that can solve the problems of the solid-phase synthesis method described above in the synthesis of fine particles. As an example of using liquid-phase synthesis, for example, Patent Document 2 discloses a method for producing chalcogenide perovskite particles with a crystallite size of less than 40 nm by liquid-phase synthesis.

[0005] U.S. Patent Application Publication No. 2019 / 0225883, Specification International Publication No. 2023 / 100919

[0006] VKRavi et al., “Colloidal BaZrS3 chalcogenide perovskite nanocrystals for thin film device fabrication”, The Royal Society of Chemistry, Nanoscale, 2021, Vol.13, p.1616-1623S. Filippone et al., “High densification of BaZrS3 powder inspired by the cold-sintering process”, Journal of Materials Research, 2021, Vol. 36, p.4404-4412

[0007] In the production of this type of semiconductor nanoparticle, there is a need for methods to improve the reaction temperature of semiconductor nanoparticles in liquid-phase synthesis, for example, in order to improve properties such as the reaction rate in liquid-phase synthesis.

[0008] One aspect of the present invention is a method for producing semiconductor nanoparticles, wherein a precursor material for semiconductor nanoparticles is reacted in the liquid phase in a solvent containing poly-alpha-olefin oil (PAO), and the boiling point of the PAO is 320°C or higher.

[0009] According to one aspect of the present invention, a manufacturing method is provided that can improve the reaction temperature of semiconductor nanoparticles in liquid-phase synthesis compared to conventional methods.

[0010] BaZrS under conditions of 310°C with ODE applied ３ This figure shows the XRD patterns of the products at various reaction times when BaZrS is synthesized in the liquid phase. Applying ODE and PAO ３ This figure shows the XRD pattern of the product when synthesized in liquid phase. This figure shows the TEM observation image of the semiconductor nanoparticles obtained under condition 5. This figure shows the TEM observation image of the semiconductor nanoparticles obtained under condition 6.

[0011] <Semiconductor Nanoparticles> The semiconductor nanoparticles in this embodiment have an overall shape that is particulate on the nanometer scale, for example, CdSe, InP, ZnSe, (Cu,Ag)(In,Ga)(Se,S) ２The semiconductor nanoparticles consist of PbS, halide perovskite, chalcogenide perovskite, etc. The semiconductor nanoparticles of this embodiment can be produced by reacting a precursor material for semiconductor nanoparticles in the liquid phase in a solvent containing PAO (boiling point of 320°C or higher). In the following description, chalcogenide perovskite particles made of chalcogenide perovskite will be described as an example of semiconductor nanoparticles.

[0012] <Structure of Chalcogenide Perovskite Particles> The chalcogenide perovskite particles of this embodiment consist of chalcogenide perovskite and have an overall shape in the nanometer scale. The chalcogenide perovskite particles are applied, for example, as a light-emitting material or a power-generating material, absorbing incident excitation light and re-emitting (luminescing) light of different energies (wavelengths).

[0013] Here, chalcogenide perovskite is a compound having a perovskite-type crystal structure and containing chalcogen (a Group 16 element other than oxygen (S, Se, or Te)). In addition to chalcogen, chalcogenide perovskite contains two or more metal elements, such as transition metal elements and alkaline earth metal elements, as components of the perovskite-type crystal structure.

[0014] The perovskites described above represent a group of materials having a cubic crystal structure based on a Bch6 octahedron, represented by the chemical formula ABCh3, and can take on tetragonal or orthorhombic crystal structures with lattice distortion. Furthermore, several stable crystal structures have been computationally demonstrated for the same ABCh3 composition. These crystal structures range from those similar to perovskites to those quite different. In addition, there are derived structures such as the Ruddlesden-Popper type and Dion-Jacobson type layered perovskites based on the perovskite structure, and double perovskite crystal structures in which different elements are alternately arranged at the B site. In this specification, the above crystal structures are collectively referred to as the "perovskite crystal structure group."

[0015] The perovskite crystal structure group specifically includes materials with the following crystal structures: cubic perovskite, tetragonal perovskite, GdFeO3-type orthorhombic, YScS3-type orthorhombic, NH4CdCl3-type orthorhombic, BaNiO3-type hexagonal, FePS3-type monoclinic, PbPS3-type monoclinic, CeTmS3-type monoclinic, Ruddlesden-Popper-type layered perovskite, Dion-Jacobson-type layered perovskite, and double perovskite. Note that the crystal structure and electronic structure of perovskite crystal structures change depending on the composition and synthesis conditions, resulting in changes to photoelectronic properties and chemical properties. Therefore, the composition and conditions are selected to obtain a crystal structure suitable for the purpose.

[0016] For example, materials having cubic perovskites, tetragonal perovskites, GdFeO3-type orthorhombic perovskites, Ruddlesden-Popper-type layered perovskites, and double perovskite structures exhibit excellent photoelectronic and chemical properties. Furthermore, chemical stability can be further improved by adopting a Dion-Jacobson-type layered perovskite structure. In particular, materials having a GdFeO3-type orthorhombic perovskite crystal structure represented by ABCh3 (A = Group 2, B = Group 4) are known to possess excellent photoelectronic properties, including a high light absorption coefficient.

[0017] In this embodiment, the chalcogenide perovskite has a composition represented by, for example, the following formula (101) or (102): ABCh ３ ...(101) A' ２ A ｎ－１ B ｎ Ch ３ｎ＋１ ... (102)

[0018] In equations (101) and (102), A and A' are Mg, Ca, Sr, Ba, or any combination thereof in any ratio, B is Ti, Zr, Hf, or any combination thereof, and Ch is S, Se, Te, or any combination thereof in any ratio. In equation (102), n is an integer between 1 and 10, inclusive. In equation (102), A and A' may be the same or different.

[0019] In the present embodiment, the chalcogenide perovskite may be a solid solution in which part or all of A, A', B, and Ch are substituted with other elements in the composition represented by formula (101) or (102).

[0020] The chalcogenide perovskite (ABCh ３ ) represented by formula (101) exhibits, for example, a crystal structure of cubic perovskite, tetragonal perovskite, orthorhombic perovskite, or double perovskite. As an example, the chalcogenide perovskite represented by the chemical formula ABCh3 includes the following substances. In the following examples, Ch is selected from the dominant materials among the chalcogen elements (S, Se), A is selected from the dominant materials among the Group 2 elements (Sr, Ba), and B is selected from the dominant materials among the Group 4 elements (Zr, Hf). SrZrS3, SrZrSe3, SrHfS3, SrHfSe3, BaZrS3, BaZrSe3, BaHfS3, BaHfSe3

[0021] The chalcogenide perovskite (A' ２ A ｎ－１ B ｎ Ch ３ｎ＋１ ) represented by formula (102) exhibits, for example, a crystal structure of Ruddlesden-Popper type layered perovskite. As an example, the chalcogenide perovskite represented by the chemical formula (A' ２ A ｎ－１ B ｎ Ch ３ｎ＋１ ) includes the following substances. Ch is selected from the dominant materials among the chalcogen elements (S, Se), A and A' are selected from the dominant materials among the Group 2 elements (Sr, Ba), and B is selected from the dominant materials among the Group 4 elements (Zr, Hf). Sr2Ba n-1 Zr n S 3n+1 , Sr2Ba n-1 Zr n Se 3n+1 Sr n+1 Zr n S 3n+1 Sr n+1 Zr nSee 3n+1 Ba2Sr n-1 Zr n S 3n+1 Ba2Sr n-1 Zr n See 3n+1 Ba n+1 Zr n S 3n+1 Ba n+1 Zr n See 3n+1 , Sr2Ba n-1 HF n S 3n+1 , Sr2Ba n-1 HF n See 3n+1 , Sr n+1 HF n S 3n+1 , Sr n+1 HF n See 3n+1 Ba2Sr n-1 HF n S 3n+1 Ba2Sr n-1 HF n See 3n+1 Ba n+1 HF n S 3n+1 Ba n+1 HF n See 3n+1

[0022] Furthermore, the chemical formulas for chalcogenide perovskite are A''A'''B''2X7 and A''A2B''3X 10 It can also be expressed as A2BB'X6. In the above chemical formula, X represents a chalcogen element (S, Se, Te). A and A' represent elements of Group 2 (Ca, Sr, Ba), A'' represents elements of Group 1 (Li, Na, K, Rb, Cs), and A''' represents elements of Group 3 (rare earth elements) and Bi. B and B' represent elements of Group 4 (Ti, Zr, Hf), and B'' represents elements of Group 5 (V, Nb, Ta). Also, n is a positive integer. Note that A and A', and B and B' may be the same element. Furthermore, A, A', A'', A''', B, B', B'', and X include mixtures of elements from each group in any ratio.

[0023] These chalcogenide perovskites are (Sr x Ba1-x ) (Zr y HF 1-y ) (S z See 1-z ) 3 or (Sr x’ Ba 1-x’ ) 2 (Sr x Ba 1-x ) n-1 (Zr y HF 1-y ) n (S z See 1-z ) 3n+1 It can also be expressed as (where x, x', y, and z are values ​​between 0 and 1, and n is a positive integer).

[0024] In chalcogenide perovskites, carrier concentration or crystal structure, as well as other physical and chemical properties, can be controlled by partial substitution of constituent elements with elements from the same or different groups. For example, elements in Group 1 can be substituted with elements from Groups 1 and 2, elements in Group 2 with elements from Groups 1, 2, and 3, elements in Group 3 with elements from Groups 2, 3, and 4, elements in Group 4 with elements from Groups 3, 4, and 5, and elements in Group 16 with elements from Groups 15, 16, and 17.

[0025] The following are some of the characteristics of chalcogenide perovskites as semiconductor materials: Chalcogenide perovskites have a large light absorption coefficient and excellent luminescence performance (luminescence efficiency, full width at half maximum). In addition, the light absorption coefficient profile of chalcogenide perovskites rises sharply at the band edge. Therefore, chalcogenide perovskites have the characteristic of high absorbance near the band gap edge.

[0026] Furthermore, chalcogenide perovskites have high chemical stability and excellent resistance to external environmental factors and stimuli such as air, moisture, heat, and light. In addition, chalcogenide perovskites are highly safe because they do not contain toxic elements, and they have low raw material costs because they do not contain rare metals.

[0027] Furthermore, although not particularly limited, chalcogenide perovskite particles may have their outer periphery covered with a shell. By providing a shell on the outer periphery of chalcogenide perovskite particles, for example, the durability of the particles can be further improved. In the following description, chalcogenide perovskite particles with their outer periphery covered with a shell will also be referred to as chalcogenite perovskite composites.

[0028] The shell material can be any material generally used for nanoparticle shells. For example, the shell material can be a group II-VI semiconductor, a group III-V semiconductor, a group III-VI semiconductor, a group I-III-VI semiconductor, a group I-II-IV-VI semiconductor, a group IV-VI semiconductor, a semiconductor containing group VI other than those listed above, a halide perovskite semiconductor, an oxide perovskite, an organic-inorganic perovskite, Si, a carbon material, silicon dioxide, a metal oxide, or a mixed crystal compound thereof. Examples of the metal oxides mentioned above include aluminum oxide, zirconium oxide, and zinc oxide. Alternatively, the shell may be formed with a chalcogenide perovskite different from the chalcogenide perovskite contained in the chalcogenide perovskite particles.

[0029] Furthermore, although not particularly limited, the chalcogenide perovskite may be surface-modified with ligands. Chalcogenide perovskite particles containing surface-modified chalcogenide perovskite can be easily dispersed in a dispersion medium. There are no restrictions on the type of ligand used to surface-modify the chalcogenide perovskite; any ligand commonly used for dispersing nanoparticles is acceptable. The dispersion medium for dispersing the chalcogenide perovskite particles may be a liquid or a solid such as a polymer compound.

[0030] Furthermore, examples of ligands used to surface-modify chalcogenide perovskites include one or more selected from the group consisting of amines, carboxylic acids, thiols, and phosphines.

[0031] The chalcogenide perovskite contained in the chalcogenide perovskite particles may have a portion of its surface replaced or passivated with other metals or elements such as oxygen or halogens. Alternatively, the replacement of elements on the chalcogenide perovskite surface may be suppressed by coating the outer periphery of the chalcogenide perovskite particles with a shell.

[0032] <Dimensions of Chalcogenide Perovskite Particles> In this embodiment, the chalcogenide perovskite particles have a particle size of, for example, less than 1 μm, as determined by transmission electron microscopy (TEM) observation. Furthermore, it is preferable that the chalcogenide perovskite particles have a particle size of at least 1 nm or larger, which is the particle size at which they can stably exist. Note that, in the case of liquid-phase synthesis, the particle size of the chalcogenide perovskite particles can be controlled, for example, by adjusting the concentration of each complex in the liquid phase and the reaction time.

[0033] <Product Forms and Application Examples of Chalcogenide Perovskite Particles> Examples of product forms for the chalcogenide perovskite particles in this embodiment include powder, dispersion, thin film, sheet, etc.

[0034] (Powder) In this specification, a powder containing chalcogenide perovskite particles means an aggregate or aggregation of chalcogenide perovskite particles (or chalcogenide perovskite composites). A powder containing chalcogenide perovskite particles may contain other materials as additives for the purpose of improving various properties such as luminescence properties, dispersibility in other materials, and film-forming properties when used as a composition as described later. In other words, a powder containing chalcogenide perovskite particles means an aggregate of chalcogenide perovskite particles (or chalcogenide perovskite composites), or a mixture of these and additives.

[0035] The applications of the powder containing chalcogenide perovskite particles are not particularly limited. For example, the powder may be dispersed in a liquid dispersion medium and used as a liquid composition (dispersion), or it may be dispersed in a resin or a solid medium (solid dispersion medium) and used as a solid composition. Alternatively, the powder may be sintered and used as a sintered body. A sintered body of powder containing chalcogenide perovskite particles can be used, for example, as a sputtering target. The powder may also be used in its powder form. Powder containing chalcogenide perovskite particles can be used, for example, as a vapor deposition source when performing vapor deposition.

[0036] (Dispersion) In this specification, a dispersion containing chalcogenide perovskite particles means a dispersion in which chalcogenide perovskite particles (or chalcogenide perovskite composites) are dispersed in a liquid dispersion medium. Here, "dispersed chalcogenide perovskite particles" means a state in which the chalcogenide perovskite particles are suspended or floating in the liquid dispersion medium, and some of the chalcogenide perovskite particles may settle in the dispersion.

[0037] Dispersions containing chalcogenide perovskite particles may also contain additives such as acids, bases, and binder materials in addition to chalcogenide perovskite, for the purpose of improving various properties of chalcogenide perovskite, such as dispersibility, luminescence properties, and film-forming properties. The size of the chalcogenide perovskite particles (or chalcogenide perovskite composites) contained in the above dispersion is not particularly limited.

[0038] The type of liquid dispersion medium used in the above dispersion is not particularly limited, but examples include water, esters such as methyl formate, ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, and pentyl acetate; ketones such as γ-butyrolactone, acetone, dimethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone; ethers such as diethyl ether, methyl-tert-butyl ether, diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, 4-methyldioxolane, tetrahydrofuran, methyltetrahydrofuran, anisole, and phenethole; methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, 2-methyl-2-butanol, methoxypropanol, diacetone alcohol, cyclohexanol, and 2-fluoroethanol. Examples include alcohols such as 2,2,2-trifluoroethanol and 2,2,3,3-tetrafluoro-1-propanol; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, and triethylene glycol dimethyl ether; organic solvents having amide groups such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, acetamide, and N,N-dimethylacetamide; organic solvents having nitrile groups such as acetonitrile, isobutyronitrile, propionitrile, and methoxyacetonitrile; organic solvents having carbonate groups such as ethylene carbonate and propylene carbonate; organic solvents having halogenated hydrocarbon groups such as methylene chloride and chloroform; organic solvents having hydrocarbon groups such as n-pentane, cyclohexane, n-hexane, benzene, toluene, and xylene; and dimethyl sulfoxide. Note that one type of liquid dispersion medium may be used alone in the above dispersion, or two or more types may be used in combination.

[0039] The uses of the dispersion described above are not particularly limited. For example, it may be used as a film-forming material when forming films using solution-based film-forming methods such as coating, spraying, or doctor blade methods, or it may be used as a composite composition by combining a dispersion containing chalcogenide perovskite particles with a solid dispersion medium.

[0040] (Thin film) In this specification, a thin film containing chalcogenide perovskite particles means a film in which chalcogenide perovskite particles (or chalcogenide perovskite composites) are aggregated in a planar manner.

[0041] Thin films containing chalcogenide perovskite particles may also contain other materials as additives to improve various properties such as the dispersibility and luminescence characteristics of the chalcogenide perovskite particles within the film. The size of the chalcogenide perovskite particles (or chalcogenide perovskite composite) contained in the thin film is not particularly limited.

[0042] The method for producing the thin film described above is not particularly limited. For example, a dispersion of chalcogenide perovskite particles in a liquid dispersion medium, or a precursor material of chalcogenide perovskite particles (for example, a dispersion of a complex having a first metal atom and a complex having a second metal atom in a dispersion medium containing poly-α-olefin oil (PAO)) may be used to form a thin film by a solution deposition method such as coating, spraying, doctor blade, or inkjet, and then drying, calcining, or other treatments as necessary to form a thin film containing chalcogenide perovskite particles, thereby obtaining chalcogenide perovskite particles.

[0043] For example, when a precursor material (a dispersion in which a complex having a first metal atom and a complex having a second metal atom are dispersed in a dispersion medium containing PAO) is used as the film-forming material and a film is formed by a solution film-forming method such as coating, the complex having the first metal atom and the complex having the second metal atom react in the film when the coating is heated at a predetermined temperature. This results in a thin film containing chalcogenide perovskite particles. The method for producing the thin film is not limited to the film-forming method described above. For example, a thin film containing chalcogenide perovskite particles (e.g., a powder containing chalcogenide perovskite particles or a chalcogenide perovskite composite, a molded body of the powder, or a sintered body of the powder, etc.) or a precursor material of chalcogenide perovskite particles may be formed using a vacuum process such as sputtering or vacuum deposition, and then, if necessary, fired or otherwise treated to form a thin film containing chalcogenide perovskite particles. Furthermore, when heat, calcination, or other treatments are performed during the formation of a thin film, the chalcogenide perovskite particles in the final thin film do not necessarily have to maintain the particle shape before the heat treatment or other treatments.

[0044] (Sheet) In this specification, a sheet containing chalcogenide perovskite particles refers to a composition formed in a planar shape from which chalcogenide perovskite particles (or chalcogenide perovskite composites) are dispersed in a solid dispersion medium. A sheet containing chalcogenide perovskite may also contain additives other than chalcogenide perovskite, such as silica nanoparticles, acids, bases, binder materials, etc., for the purpose of improving various properties such as the dispersibility and luminescence properties of the chalcogenide perovskite. The size of the chalcogenide perovskite particles (or chalcogenide perovskite composites) contained in the above sheet is not particularly limited.

[0045] Any known polymer material used for this type of purpose can be arbitrarily applied as the solid dispersion medium for the sheet described above. The polymer material used as the solid dispersion medium for the sheet is preferably one that exhibits a translucent or semi-transparent appearance when formed into a sheet.

[0046] Furthermore, the solid dispersion medium used in the above-mentioned sheet is not particularly limited, but examples include polyvinyl butyral, polyvinyl acetate, silicone and silicone derivatives, ionomers, polyethylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polypropylene, polyester, polycarbonate, polystyrene, polyacrylonitrile, ethylene vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-methacrylic acid copolymer film, nylon, etc. Examples of silicone derivatives include polyphenylmethylsiloxane, polyphenylalkylsiloxane, polydiphenylsiloxane, polydialkylsiloxane, fluorinated silicones, and vinyl and hydride-substituted silicones.

[0047] Furthermore, the method for producing the above-mentioned sheet is not particularly limited. For example, a sheet containing chalcogenide perovskite particles may be produced by kneading a powder containing the above-mentioned chalcogenide perovskite particles with a solid dispersion medium and then stretching the mixture. Alternatively, the above-mentioned sheet may be produced by applying a dispersion, which is a mixture of a liquid composition containing chalcogenide perovskite particles and various additives, with a solid dispersion medium or a precursor of a solid dispersion medium, onto a sheet, and then drying it as necessary.

[0048] (Devices) The applications of the above chalcogenide perovskite particles, powders, dispersions, thin films, and sheets are not particularly limited. For example, the above chalcogenide perovskite particles, powders, dispersions, thin films, and sheets are envisioned for application in the down-conversion of ultraviolet light or blue light in various devices. Furthermore, the above chalcogenide perovskite particles, powders, dispersions, thin films, and sheets can be suitably used in the manufacture of various devices such as light-emitting devices like LEDs and organic ELs, display devices including such light-emitting devices, lighting devices including such light-emitting devices, image sensors, photoelectric conversion devices, and bioluminescent labels.

[0049] <Method for Producing Chalcogenide Perovskite Particles> Next, as an example of a method for producing semiconductor nanoparticles according to this embodiment, a method for producing chalcogenide perovskite particles will be described. However, the method is not particularly limited to the following, as long as it involves reacting a precursor material for chalcogenide perovskite particles (semiconductor nanoparticles) in the liquid phase in a solvent containing PAO (boiling point of 320°C or higher). The chalcogenide perovskite particles of this embodiment can be produced by reacting a complex having a first metal atom and a complex having a second metal atom in the liquid phase in a solvent containing poly-α-olefin oil (PAO).

[0050] From the viewpoint of suppressing side reactions in the liquid phase and exhibiting a crystal structure similar to that of solid-phase synthesis, it is preferable that the complex having the first metal atom and the complex having the second metal atom each have ligands that do not contain oxygen atoms (O) and halogen atoms (X) as coordinating atoms. Here, examples of halogen atoms (X) include fluorine atoms (F), chlorine atoms (Cl), bromine atoms (Br), iodine atoms (I), and the like.

[0051] The ligands of the complex having the first metal atom and the complex having the second metal atom are not particularly limited. For example, ligands can be selected from the group consisting of nitrogen (N), sulfur (S), selenium (Se), tellurium (Te), carbon (C), and phosphorus (P). The ligands of the complex having the first metal atom and the ligands of the complex having the second metal atom may be of the same type or of different types.

[0052] Ligands that coordinate with a nitrogen atom include alkylamines (NR) such as amines, dimethylamine, diethylamine, and methylethylamine. ２ ); arylamines such as phenylamine (NHAr); trialkylsilylamines such as silylamine and trimethylsilylamine (N(SiR ３ ) ２ Examples include nitrogen-containing aromatic rings such as pyrazoles.

[0053] Ligands that coordinate with a sulfur atom include dithiocarbamates (S ２ CNR２ ), xanthate (S ２ COR), trithiocarbamate (S ２ CSR), dithioester (S ２ CR), thiolate (SR), etc. are mentioned.

[0054] As the ligand coordinated by a selenium atom or a tellurium atom, compounds in which some or all of the sulfur atoms of the ligand coordinated by the above sulfur atom are replaced by a selenium atom or a tellurium atom are mentioned.

[0055] The complex having the first metal atom and the complex having the second metal atom may be a single compound (polynuclear complex). A single compound (polynuclear complex) refers to a compound having both the first metal atom and the second metal atom as the central metal ions of the complex in one complex. Preferably, the first metal atom and the second metal atom may be bonded through a ligand coordinated by a sulfur atom, a selenium atom, or a tellurium atom. As the polynuclear complex in which the ligand is coordinated by a sulfur atom, heterobimetal thiolate, heterobimetal sulfide, etc. are mentioned. In these polynuclear complexes, the first metal atom and the second metal atom are bonded through thiolate or sulfide (ligand coordinated by a sulfur atom) as the ligand. As the polynuclear complex in which the ligand is coordinated by a selenium atom or a tellurium atom, those in which some or all of the sulfur atoms in the polynuclear complex in which the ligand is coordinated by a sulfur atom are replaced by a selenium atom or a tellurium atom are mentioned.

[0056] As the ligand coordinated by a carbon atom, alkanes such as methyl and ethyl; unsaturated hydrocarbon rings such as cyclopentadiene, cyclooctadiene, and indene, or groups derived from the benzyl group and other above-mentioned unsaturated hydrocarbon rings; cyanide (CN), etc. are mentioned.

[0057] As the ligand coordinated by a phosphorus atom, trialkylphosphines (PR ３ ), such as trioctylphosphine and tricyclohexylphosphine; triarylphosphines (PAr ３ ), such as triphenylphosphine and tri(o-tolyl)phosphine; diphosphine (R ２ P-(CH ２ )) ｍ -PR２ ) and the like.

[0058] The ligand may be a derivative of the above-described ligand.

[0059] In each of the above general formulas, R is a hydrogen atom, a saturated hydrocarbon group having 1 to 20 carbon atoms, or an unsaturated hydrocarbon. When one ligand contains two or more Rs, the Rs may be the same or different from each other. Ar is an aryl group having 6 to 20 carbon atoms which may have a substituent, such as a phenyl group, a naphthyl group, an anthracenyl group, etc. Examples of the substituent include an alkyl group having 1 to 10 carbon atoms. When one ligand contains two or more Ars, the Ars may be the same or different from each other. m is an integer of 1 to 10.

[0060] Among the above-described ligands, a ligand that coordinates with a nitrogen atom or a ligand that coordinates with a sulfur atom is preferable. Also, a ligand having a structure selected from the group consisting of the following formulas (1) to (7) is preferable. S ２ CNR ａ ２ (1) S ２ COR (2) S ２ CSR ａ (3) S ２ CR ａ (4) SR ａ (5) NR ａ ２ (6) N(SiR ａ ３ ) ２ (7) (In the formula, R ａ is a hydrogen atom, a saturated hydrocarbon group having 1 to 20 carbon atoms, or an unsaturated hydrocarbon group having 1 to 20 carbon atoms. When one ligand has a plurality of Rs ａ , the plurality of Rs ａ may be the same or different from each other.)

[0061] Examples of the saturated hydrocarbon group and unsaturated hydrocarbon mentioned above include C1-C20 alkyl groups, C3-C20 cycloalkyl groups, C2-C20 alkenyl groups, C2-C20 alkynyl groups, C3-C20 cycloalkenyl groups, C3-C20 cycloalkynyl groups, C3-C20 cycloalkadienyl groups, and C6-C20 aryl groups. The saturated hydrocarbon group and unsaturated hydrocarbon may have substituents. Examples of substituents include C1-C10 alkyl groups.

[0062] For example, the ligand is preferably a compound represented by formula (1) above. Also, R in formula (1) ａ It is preferably an alkyl group having 1 to 10 carbon atoms, and more preferably an alkyl group having 2 to 6 carbon atoms.

[0063] The ligands used in this embodiment can be synthesized according to conventional methods. Alternatively, commercially available compounds may be used.

[0064] The metal atom of the complex having the first metal atom is a metal atom selected from alkaline earth metal elements, and the metal atom of the complex having the second metal atom is a metal atom selected from transition metal elements. For example, the metal atom of the complex having the first metal atom includes at least one of Sr and Ba, and the metal atom of the complex having the second metal atom includes at least one of Zr and Hf. At least one of the metal atoms of the complex having the first metal atom and the metal atom of the complex having the second metal atom may further include at least one selected from Ti, Ca, and Mg. For example, the metal atom of the complex having the first metal atom may include at least one of Sr and Ba, as well as at least one of Ti, Ca, and Mg. Also, the metal atom of the complex having the second metal atom may include at least one of Zr and Hf, as well as Ti. By including Ti in the chalcogenide perovskite, it becomes possible to control the band gap of the chalcogenide perovskite. Furthermore, when Ti is included in the chalcogenide perovskite, the chalcogenide perovskite is (Sr x Ba 1-x ) (Zry Ti ｙ’ HF 1-y-y’ ) (S z See 1-z ) 3 or (Sr x’ Ba 1-x’ ) 2 (Sr x Ba 1-x ) n-1 (Zr y Ti ｙ’ HF 1-y-y’ ) n (S z See 1-z ) 3n+1 It can also be expressed as (where x, x', y, y', and z are values ​​between 0 and 1, and n is a positive integer).

[0065] The complexes having the first metal atom and the complex having the second metal atom can be synthesized by selecting the starting components according to the type of metal atom and ligand they each possess, using known methods. Alternatively, commercially available metal complexes may be used.

[0066] In this embodiment, considering that the liquid phase may be heated to a high temperature of, for example, 300°C or higher in the liquid phase synthesis step described later, a solvent containing poly-α-olefin oil (PAO) is used. The solvent containing PAO only needs to contain at least PAO; for example, the solvent may consist only of PAO, or the solvent may mainly contain PAO.

[0067] PAO is a general term for polymers produced from α-olefins through polymerization and hydrogenation. PAO is characterized by being completely free of impurities such as sulfur, compared to, for example, mineral oil. Being completely free of impurities means, for example, that the sulfur content in PAO is 0.1% by mass or less. If impurities are present, it may be impossible to synthesize particles, or the nucleation and growth of particles may become non-uniform, making it impossible to obtain nanoparticles with the desired phase and shape. Such structural non-uniformity and increased defects can also have unintended effects on optoelectronic performance, such as luminescence efficiency. On the other hand, because PAO is free of impurities, the possibility of such problems is extremely low.

[0068] PAO exhibits a higher boiling point compared to, for example, octadecene (ODE). Therefore, when a solvent containing PAO is applied to the production of chalcogenide perovskite particles, it becomes possible to synthesize the complex having the first metal atom and the complex having the second metal atom under higher temperature conditions in the liquid phase compared to when a solvent containing ODE is applied. The boiling point of PAO is preferably 320°C or higher, more preferably 350°C or higher, and even more preferably 400°C or higher. There is no particular upper limit to the boiling point of PAO, but for example, the boiling point of PAO may be 550°C. The boiling point shall be measured by distillation using gas chromatography (JIS K2254). Furthermore, the boiling point of PAO can be adjusted, for example, by controlling the degree of polymerization.

[0069] The solvent containing PAO may also contain additives such as saturated aliphatic hydrocarbons, unsaturated aliphatic hydrocarbons, aromatic hydrocarbons, nitrogen-containing heterocyclic compounds, alcohols, aldehydes, carboxylic acids, primary amines, secondary amines, tertiary amines, phosphine compounds, thiols, etc.

[0070] Furthermore, using PAO is expected to result in a higher temperature during the reaction, i.e., a state of higher atomic mobility, thereby improving the reaction rate compared to conventional methods. This may allow for the production of chalcogenide perovskite particles in a shorter time than before. Moreover, as atomic mobility improves with heating, it is thought that the particles will form the most stable crystalline state during the cooling process. Using PAO is expected to result in a higher temperature during the reaction, i.e., a state of higher atomic mobility, and a reduction in the amorphous region of the particles formed during the cooling process. This may lead to improved crystallinity of chalcogenide perovskite particles when using PAO.

[0071] In this embodiment, for example, in addition to the complex having the first metal atom and the complex having the second metal atom described above, an amine compound can be further added to the liquid phase. The amine compound functions as a reaction initiator. Preferably, the amine compound does not contain oxygen atoms (O) or halogen atoms (X). Examples include alkylamines having one alkyl group, such as oleylamine, hexadecylamine, and octadecylamine; dialkylamines having two alkyl groups having 1 to 30 carbon atoms; and trialkylamines having three alkyl groups having 1 to 30 carbon atoms (e.g., trioctylamine). From the viewpoint of fully exhibiting its function as a reaction initiator between the ligand and the metal component, it is preferable to add an amount of the amine compound equal to or greater than the total amount of ligands contained in the complex having the first metal atom and the complex having the second metal atom added to the liquid phase. Furthermore, the amine compound may be added to the liquid phase in excess of the amount mentioned above (equal to the total amount of ligands) from the viewpoint of exhibiting its function as a surfactant that adheres to the particle surface of the chalcogenide perovskite ultimately obtained. Although not particularly limited, it is more preferable that the amine compound be added in an amount of substance that is preferably 4 to 48 times, more preferably 8 to 36 times, and even more preferably 12 to 24 times, the total amount (mol) of ligands contained in the compound having the first metal atom and the compound having the second metal atom added to the liquid phase. The more the amount of amine compound added, the better the dispersibility can be. On the other hand, by not adding too much amine compound, the generation of impurities can be suppressed.

[0072] Furthermore, in addition to the complex having the first metal atom and the complex having the second metal atom, a chalcogen compound can be added to the liquid phase. For example, if the ligands of the complex having the first metal atom and the complex having the second metal atom do not contain chalcogen elements such as sulfur (S), or if the chalcogen elements contained in the ligands are insufficient, the composition of the target chalcogenide perovskite can be adjusted by adding an appropriate amount of chalcogen compound to the liquid phase.

[0073] Preferably, the chalcogen compound used does not contain oxygen atoms (O) or halogen atoms (X). For example, sulfur or carbon disulfide (CS ２ ), hydrogen sulfide (H ２ Sulfides such as S, selenium or selenides, tellurium or tellurides, hexanethiol, octanthiol, decanethiol, dodecanethiol (n-dodecanethiol, t-dodecanethiol), hexadecanethiol, mercaptopropylsilane, dialkylthiourea (S=C(NR ２ ) ２ Examples include sulfur-trioctylphosphine (trioctylphosphine sulfide; S-TOP), sulfur-tributylphosphine (S-TBP), sulfur-triphenylphosphine (S-TPP), sulfur-trioctylamine (S-TOA), bis(trimethylsilyl) sulfide, ammonium sulfide, sodium sulfide, selenium-trioctylphosphine (Se-TOP), selenium-tributylphosphine (Se-TBP), and selenium-triphenylphosphine. Among these, dialkylthiourea (S=C(NR ２ Thioureas such as ) are, for example, carbon disulfide (CS ２ Because it has a higher boiling point than ), it can be suitably used as a chalcogen compound.

[0074] In the manufacturing method of this embodiment, the complex having the first metal atom and the complex having the second metal atom described above are reacted in the liquid phase with PAO and, if necessary, with a chalcogen compound and an amine compound, and the procedure is not particularly limited. The manufacturing method of this embodiment can be carried out by known methods such as the hot injection method, the heat-up method, and the flow synthesis method. The mixing ratio of the complex having the first metal atom and the complex having the second metal atom can be adjusted according to the composition of the target chalcogenide perovskite particles. Although not particularly limited, it is preferable that the mixing ratio of the compound having the first metal atom and the compound having the second metal atom be determined such that the ratio of the amount of substance of the first metal atom to the amount of substance of the second metal atom is 0.8 times or more and 1.2 times or less, preferably 0.9 times or more and 1.1 times or less, and more preferably 1.0 times, the atomic ratio in the composition of the chalcogenide perovskite-type compound to be manufactured.

[0075] In the manufacturing method of this embodiment, when the raw material components include a complex having at least a first metal atom, a complex having a second metal atom, and a solvent containing PAO, a first raw material is prepared from the said raw material components, which includes at least the solvent, and a second raw material is prepared, which includes at least the remaining raw material components not included in the first raw material. Then, the reaction is brought about by adding the second raw material to the first raw material. In this embodiment, it is preferable to add the second raw material to the first raw material after preheating at least one of the first and second raw materials. Alternatively, the second raw material may be added to the first raw material and then heated to bring about the reaction.

[0076] The method for producing chalcogenide perovskite particles in this embodiment will be described below, using the hot injection method as an example. First, the first raw material is preheated. The heating rate is not particularly limited, but for example, it is heated at a heating rate of 1 to 30°C / min, typically 1 to 10°C / min. The temperature of the first raw material after heating is not particularly limited, but for example, it may be room temperature to 550°C, or 120 to 550°C. Next, the second raw material is added to the first raw material to cause a reaction between a complex having a first metal atom and a complex having a second metal atom. The second raw material may also be preheated in the same way as the first raw material. The rate of addition of the second raw material is not particularly limited, but it is preferable to adjust it considering the decrease in the temperature of the liquid phase due to the addition of the second raw material. The liquid phase temperature after mixing is preferably room temperature to 550°C, more preferably 120 to 550°C.

[0077] For example, either the complex having the first metal atom or the complex having the second metal atom may have a ligand represented by the above formula (1) (dithiocarbamate (S ２ CNR ２ If the ligand is present, and the liquid phase temperature is 120°C or higher, the metal complex having the ligand can be initiated by the amine compound, and the reaction between the complex having the first metal atom and the complex having the second metal atom proceeds smoothly. Although the reaction can be initiated without using an amine compound, in this case it is preferable to raise the liquid phase temperature above 120°C.

[0078] In this embodiment, by preheating the first raw material and then adding the second raw material to the first raw material, the components contributing to the synthesis of chalcogenide perovskite (solvent containing PAO, a complex having a first metal atom, and a complex having a second metal atom) are all present in the liquid phase, and at the same time, all of them reach a high temperature. Therefore, the reaction start times of the complex having the first metal atom and the reaction start times of the complex having the second metal atom can be made almost simultaneous. As a result, the reactions of the complex having the first metal atom and the complex having the second metal atom proceed in a well-balanced manner, and chalcogenide perovskite can be synthesized with high purity.

[0079] In this embodiment, when the above-mentioned amine compound is added to the liquid phase as a reaction initiator, the raw material components include a solvent containing PAO, a complex having a first metal atom, a complex having a second metal atom, and an amine compound. The combination of the first raw material component and the second raw material component is not particularly limited.

[0080] For example, the first raw material may be a solvent containing PAO, and the second raw material may be a mixture of a complex having a first metal atom, a complex having a second metal atom, and an amine compound. Alternatively, the first raw material may be a mixture of a solvent containing PAO and an amine compound, and the second raw material may be a mixture of a complex having a first metal atom and a complex having a second metal atom. Alternatively, the first raw material may be a mixture of either the complex having a first metal atom or the complex having a second metal atom and a solvent containing PAO, and the second raw material may be a mixture of the other of the complex having a first metal atom or the complex having a second metal atom and an amine compound.

[0081] In this embodiment, when the chalcogen compound described above is added to the liquid phase, the raw material components include a solvent containing PAO, a complex having a first metal atom, a complex having a second metal atom, and a chalcogen compound. The combination of the first raw material component and the second raw material component is not particularly limited.

[0082] For example, the first raw material may be a solvent containing PAO, and the second raw material may be a mixture of a complex having a first metal atom, a complex having a second metal atom, and a chalcogen compound. Alternatively, the first raw material may be a mixture of a solvent containing PAO and a chalcogen compound, and the second raw material may be a mixture of a complex having a first metal atom and a complex having a second metal atom. Alternatively, the first raw material may be a mixture of either the complex having a first metal atom or the complex having a second metal atom and a solvent containing PAO, and the second raw material may be a mixture of the other of the complex having a first metal atom or the complex having a second metal atom and a chalcogen compound.

[0083] In this embodiment, the liquid phase obtained by adding the second raw material to the first raw material is heated and stirred for, for example, 0 to 24 hours while maintaining a temperature preferably between room temperature and 550°C, more preferably between 120 and 550°C. After stirring is complete, the precipitate formed in the liquid phase is isolated by a known method to obtain the target product, chalcogenide perovskite particles.

[0084] In the series of liquid-phase synthesis described above, it is preferable to carry out the synthesis in an environment where components such as water and oxygen are removed as much as possible. For example, the series of liquid-phase synthesis described above is preferably carried out in an inert atmosphere filled with nitrogen or argon.

[0085] The method for producing chalcogenide perovskite particles in this embodiment may be, for example, by the flow synthesis method described below. First, a complex having a first metal atom, a complex having a second metal atom, and at least one of a chalcogen compound and an amine compound are each dissolved in a solvent containing PAO, and then passed through separately as raw material flows.

[0086] Next, the reaction is initiated by combining all the raw material flows simultaneously or in stages. At this time, it is preferable to preheat at least one of the raw material flows before combining them. The raw material flow that is preheated is preferably the flow with the highest flow rate. Furthermore, since the reaction field is small in flow synthesis, the temperature can be raised instantaneously even if heating is done immediately after the combination of each raw material flow, and the reaction start time of the complex having the first metal atom and the reaction start time of the complex having the second metal atom can be made approximately simultaneous. The heating rate and the temperature of the components after heating are the same as in the hot injection method.

[0087] <Description of Examples> Examples and comparative examples of the present invention will be described below. First, the preparation steps for the examples and comparative examples will be described.

[0088] (Barium bis-diisobutyldithiocarbamate (Ba(DiBuDTC)) ２(Synthesis) In a nitrogen glove box (moisture content 1 ppm or less), a stirring bar and barium hydroxide (Ba(OH)) are placed in a 500 mL three-necked flask. ２ 10.3 g of (anhydrous, Merck) was placed in the flask, which was then sealed with a rubber stopper and a glass stopper and removed from the glove box. A pressure-maintaining dropping funnel was attached to the flask, and the inside was purged with argon. Ultrapure water (18.2 MΩcm, Merck Millipore, Integral-3) immediately after collection was quickly added and stirred with a magnetic stirrer. 132 mmol of diisobutylamine (TCI), which had been stored in the glove box, was placed in the dropping funnel, and the lid was closed and the solution was slowly added dropwise over 10 minutes. The solution was heated to 40°C using a heat gun to obtain a gray suspension. Subsequently, 132 mmol of carbon disulfide (Fujifilm Wako) was added to the dropping funnel, and the lid was closed and the solution was added dropwise over 20 minutes. The clarity of the solution initially increased, but then it began to become cloudy. The solution was stirred at room temperature for 5 hours. 300 mL of ultrapure water was added to the obtained suspension, and the solution was heated to 50°C in a water bath, at which point the amount of precipitate decreased. A layer of Celite (manufactured by Fujifilm Wako) approximately 5 mm thick was spread on filter paper (ADVANTEC, #131), and the precipitate was removed by suction filtration to obtain a clear solution. Ultrapure water was then poured over the Celite to wash the precipitate. The filtrate was concentrated using a rotary evaporator (EYELA, N-1115) to obtain colorless crystals. After cooling in a flask with ice, the precipitate was filtered off by suction filtration. Vacuum drying was performed overnight at 40°C, and Ba (DiBuDTC) was added. ２ White crystals were obtained.

[0089] (Zirconium tetrakisdiisobutyldithiocarbamate (Zr(DiBuDTC)) ４ (Synthesis) In a nitrogen glove box (moisture content 1 ppm or less), a stirring bar and zirconium chloride (ZrCl) were added to a 300 mL three-necked flask. ４) was added, the flask was sealed with a rubber stopper and a glass stopper, and then removed from the glove box. A pressure-maintaining dropping funnel was attached to the flask, the inside was purged with argon, and then the flask was cooled with ice. 180 mL of tetrahydrofuran (THF) was added using the dropping funnel while stirring with a magnetic stirrer. Next, 500 mmol of diisobutylamine (TCI), which had been stored in the glove box, was placed in the dropping funnel, the lid was closed, and it was slowly added dropwise over 10 minutes, after which stirring was continued for another 10 minutes. Next, 250 mmol of carbon disulfide (Fujifilm Wako) was added to the dropping funnel and added dropwise to the reaction solution over 20 minutes. After stirring at room temperature for 5 hours, an orange suspension was obtained. A Celite bed was prepared by spreading Celite (Fujifilm Wako) to a thickness of approximately 5 mm on filter paper (ADVANTEC, #131), and the precipitate (isobutylammonium chloride) was removed. A yellow, transparent THF solution was concentrated using a rotary evaporator to a total volume of 30 mL. While stirring, hexane was gradually added to this solution, totaling 300 mL, to obtain a white precipitate. The solid was filtered off by suction filtration and washed with hexane. The obtained solid was white or pale pink. The solid was dispersed in 300 mL of ethanol, stirred for several minutes, then recovered again by suction filtration and washed with ethanol. The obtained white solid was vacuum-dried overnight at 40°C, and Zr(DiBuDTC) was extracted. ４ I obtained it.

[0090] (Setup of Nanoparticle Synthesis Reactor) A mantle heater was set at the bottom of a 50 mL two-neck flask and placed on top of a magnetic stirrer. A thyristor voltage regulator was connected to the output terminal of a PID-controlled temperature controller, and the voltage was adjusted to apply 40 V to the mantle heater with a maximum output of 50 W. A stainless steel K-type thermocouple was connected to this temperature controller and inserted into the two-neck flask to measure the liquid temperature. The PID parameters of the temperature controller were optimized so that the liquid temperature in the reaction vessel quickly reached the set temperature within the range of 100 to 350 °C.

[0091] (Comparative Example) In the comparative example, semiconductor nanoparticles were obtained by the following method. First, 1 mmol of barium bis-diisobutyldithiocarbamate (Ba(DiBuDTC))２ ), 1 mmol of zirconium tetrakisdiisobutyldithiocarbamate (Zr(DiBuDTC) ４ ), 5 mL of 1-octadecene (ODE) was placed in a 50 mL two-necked flask. This mixture is called mixture A.

[0092] Mixture A was heated to 80°C under vacuum for 5 minutes while being stirred with a magnetic stirrer. After degassing and dehydrating the reaction vessel, argon was introduced into the reaction vessel and heated to 310°C, the boiling point of octadecene. Mixture A was reacted at 310°C for a maximum of 180 minutes.

[0093] Four milliliters of oleylamine (OLA) were placed in a gastight syringe and injected into mixture A, which was being heated and stirred. Starting from the time when the OLA was injected (0 minutes), 1 mL of the solution was withdrawn using a syringe at 1 minute, 5 minutes, 10 minutes, 15 minutes, 30 minutes, 60 minutes, 90 minutes, and 120 minutes.

[0094] Each of the solutions extracted and separated at the above timing, as well as the solution reacted for 180 minutes, were transferred to a centrifuge tube. 3 mL of propanol was added to each of the separated solutions to precipitate semiconductor nanoparticles. After centrifugation (2500 rpm, 2 minutes) of each separated solution, the supernatant was discarded, and the brown precipitate (semiconductor nanoparticles) was allowed to stand overnight under vacuum to dry and become powder. Then, using an X-ray diffractometer (Rigaku Corporation, "SmartLab type"), a parallel beam of CuKα rays (1.5418 Å) was incident on the obtained powdered semiconductor nanoparticles, and the X-ray diffraction (XRD) patterns in the range of 2θ from 5 to 80° were measured by 2θ / θ measurement. The measurement conditions are shown below. Measurement device: SmartLab (manufactured by Rigaku Corporation) X-ray source: CuKα (1.5418 Å), output 45 kV, 200 mA Incident optical system: Parallel beam optical system Receiver side solar slit: 5.0° Slit: Incident side IS = 1.0 mm Receiver side RS1 = 1.0 mm, RS2 = 1.0 mm Scanning conditions: Scanning axis 2θ / θ Scanning speed: 2° / min Step width: 0.02°

[0095] Figure 1 shows BaZrS under conditions of 310°C with ODE applied as the solvent. ３This figure shows the XRD patterns of the product at various reaction times when the product is synthesized in the liquid phase. In Figure 1, the XRD patterns of the product (semiconductor nanoparticles) are shown from top to bottom at reaction times of 1 minute, 5 minutes, 10 minutes, 15 minutes, 30 minutes, 60 minutes, 120 minutes, and 180 minutes, respectively.

[0096] In Figure 1, the XRD pattern of the product up to 10 minutes of reaction time shows BaZrS ３ No corresponding diffraction pattern could be confirmed. Furthermore, in the XRD pattern of the product after a reaction time of 15 minutes, BaZrS ３ A slight diffraction pattern corresponding to this was observed. In the XRD patterns of products with reaction times up to 15 minutes, BaCO was generated when the BaS in the product was exposed to air during the XRD measurement. ３ The diffraction pattern has been confirmed, and in the example in Figure 1, in liquid-phase synthesis with a reaction time of up to 15 minutes, BaZrS ３ BaZrS was not obtained as the main product. On the other hand, in the XRD pattern of the product after 30 minutes of reaction, BaZrS ３ Only the diffraction pattern corresponding to this has been obtained. From this, it can be seen that BaZrS is obtained when ODE is applied as the solvent and the temperature is 310°C. ３ When synthesizing in the liquid phase, a reaction time of 15 minutes is insufficient; a reaction time of 30 minutes or more is required.

[0097] (Examples and Comparative Examples of Semiconductor Nanoparticle Production) As examples and comparative examples of semiconductor nanoparticle production, powdered semiconductor nanoparticles were obtained under the following conditions 1 to 4.

[0098] (Condition 1: Comparative Example) Mixture A was heated to 80°C under vacuum for 5 minutes while being stirred with a magnetic stirrer. After degassing and dehydrating the reaction vessel, argon was introduced into the reaction vessel and heated to 310°C, the boiling point of octadecene. 4 mL of oleylamine (OLA) was placed in a gas-tight syringe and injected into mixture A, which was being heated and stirred. The timing of the OLA injection was set as 0 minutes, and 1 mL of the solution was withdrawn using the syringe at 30 minutes. The solution withdrawn and separated at the above timing was transferred to a centrifuge tube, and 3 mL of propanol was added to precipitate semiconductor nanoparticles in the separated solution. After centrifugation of the separated solution (2500 rpm, 2 minutes), the supernatant was discarded, and the brown precipitate (semiconductor nanoparticles) was allowed to stand overnight under vacuum to dry and powderize to obtain semiconductor nanoparticles.

[0099] (Condition 2: Example) In Condition 2, based on Condition 1, 5 mL of PAO was applied instead of ODE to produce mixture A, and otherwise the procedure was carried out in the same manner as Condition 1 to obtain powdered semiconductor nanoparticles. (Condition 3: Example) In Condition 3, based on Condition 2, mixture A to which 5 mL of PAO was applied was heated to 340°C, and otherwise the procedure was carried out in the same manner as Condition 2 to obtain powdered semiconductor nanoparticles. (Condition 4: Example) In Condition 4, based on Condition 2, mixture A to which 5 mL of PAO was applied was heated to 340°C, and 1 mL of the solution was withdrawn using a syringe at a timing of 5 minutes, with the timing of OLA injection being set as 0 minutes. Otherwise the procedure was carried out in the same manner as Condition 2 to obtain powdered semiconductor nanoparticles.

[0100] Then, the XRD patterns of the semiconductor nanoparticles obtained in powder form under each of the above conditions 1 to 4 were measured using an X-ray diffractometer (Rigaku, SmartLab).

[0101] Figure 2 shows the results of applying ODE and PAO as solvents to BaZrS ３This figure shows the XRD patterns of the products when synthesized in the liquid phase. In Figure 2, from top to bottom, the XRD patterns of the products synthesized in the liquid phase using ODÉ as the solvent at 310°C for 30 minutes (Condition 1), the XRD patterns of the products synthesized in the liquid phase using PAO as the solvent at 310°C for 30 minutes (Condition 2), the XRD patterns of the products synthesized in the liquid phase using PAO as the solvent at 340°C for 30 minutes (Condition 3), and the XRD patterns of the products synthesized in the liquid phase using PAO as the solvent at 340°C for 5 minutes (Condition 4) are shown.

[0102] When PAO is used as the solvent, BaZrS is produced under conditions of 340°C, which is above the boiling point of octadecene (315°C). ３ Liquid-phase synthesis becomes possible. Therefore, BaZrS with PAO applied as the solvent ３ In liquid-phase synthesis, high-temperature conditions that cannot be applied in ODE (Oxygen-Derived Emission) can be used.

[0103] Furthermore, as shown in Figure 2, the XRD pattern of the product synthesized in liquid phase at 340°C for 5 minutes using PAO as the solvent showed BaZrS, similar to the case with a 30-minute reaction time. ３ The corresponding diffraction pattern was confirmed. Therefore, BaZrS with PAO applied as the solvent ３ In the liquid-phase synthesis, the reaction rate is improved by carrying out the reaction at a temperature of 340°C, and in the case of ODE, BaZrS ３ BaZrS in a short time when it cannot be obtained ３ It can be seen that the production of BaZrS can be achieved under the above conditions. ３ Its crystal structure is GdFeO3-type orthorhombic.

[0104] (TEM observation of semiconductor nanoparticles obtained by applying ODÉ and PAO as solvents) The shapes of semiconductor nanoparticles obtained when ODÉ was applied as the solvent (Condition 5: Comparative Example) and when PAO was applied as the solvent (Condition 6: Example) were observed using a transmission electron microscope (TEM).

[0105] For conditions 5 and 6, semiconductor nanoparticles were synthesized separately from those for conditions 1 to 4 for TEM observation. In condition 5, under the same conditions as in condition 1, with OLA injection time set to 0 minutes, 1 mL of the solution was withdrawn using a syringe at 30 minutes, and 3 mL of 1-propanol was added to the withdrawn semiconductor nanoparticle dispersion. Subsequently, a precipitate of semiconductor nanoparticles was obtained by centrifugation (2500 rpm, 2 minutes), and the precipitate was dispersed in toluene. Similarly, in condition 6, under the same conditions as in condition 4, with OLA injection time set to 0 minutes, 1 mL of the solution was withdrawn using a syringe at 5 minutes, and 3 mL of 1-propanol was added to the withdrawn semiconductor nanoparticle dispersion. Subsequently, a precipitate of semiconductor nanoparticles was obtained by centrifugation (2500 rpm, 2 minutes), and the precipitate was dispersed in toluene.

[0106] Subsequently, a TEM grid, specifically the product name Hi-Res Carbon HRC-C10 STEM Cu100P grid (purchased from Ouken Shoji), was used. Then, semiconductor nanoparticles in the dispersions obtained under conditions 5 and 6 were observed using a TEM (Hitachi High-Technologies Corporation, product name H-7650).

[0107] Figure 3 shows the TEM observation image of semiconductor nanoparticles obtained under condition 5, and Figure 4 shows the TEM observation image of semiconductor nanoparticles obtained under condition 6. From Figures 3 and 4, it can be seen that in both condition 5 and condition 6, TEM observation revealed semiconductor nanoparticles (BaZrS ３ It can be seen that this can be confirmed. Under condition 6, when ODE is applied as the solvent, BaZrS ３ The generation of BaZrS takes 30 minutes, but under condition 6, where PAO was applied as the solvent and the reaction was carried out at 340°C, BaZrS was produced in a reaction time of 5 minutes. ３ It can be seen that it is possible to generate this.

[0108] As described above, embodiments of the present invention have been explained, but these embodiments are presented as examples and are not intended to limit the scope of the present invention. Embodiments can be implemented in various forms other than those described above, and various omissions, substitutions, modifications, etc., can be made without departing from the spirit of the present invention. Embodiments and their variations are included in the scope and spirit of the present invention, as are the inventions described in the claims and their equivalents.

[0109] This application claims priority based on Japanese Patent Application No. 2025-020047, filed on 10 February 2025, and the entire contents of Japanese Patent Application No. 2025-020047 are incorporated herein by reference.

Claims

1. A method for producing semiconductor nanoparticles, wherein a precursor material for the semiconductor nanoparticles is reacted in a liquid phase in a solvent containing poly-alpha-olefin oil (PAO), and the boiling point of the PAO is 320°C or higher.

2. The method for producing according to claim 1, wherein the semiconductor nanoparticles are chalcogenide perovskite particles containing a chalcogenide perovskite, and the precursor material comprises a complex having a first metal atom and a complex having a second metal atom.

3. The manufacturing method according to claim 2, wherein the complex having the first metal atom and the complex having the second metal atom each have ligands that do not contain oxygen atoms (O) and halogen atoms (X) as coordinating atoms.

4. The manufacturing method according to claim 2 or 3, wherein the complex having the first metal atom and the complex having the second metal atom each have a ligand that coordinates with an atom selected from the group consisting of nitrogen (N), sulfur (S), selenium (Se), tellurium (Te), carbon (C), and phosphorus (P).

5. The manufacturing method according to claim 3 or 4, wherein the ligand is a dithiocarbamate, xanthate, trithiocarbamate, dithioester, thiolate, sulfide, or a compound in which some or all of the sulfur atoms contained therein are substituted with a selenium atom or a tellurium atom, alkylamine, arylamine, trialkylsilylamine, nitrogen-containing aromatic ring, alkane, unsaturated hydrocarbon ring, or a group derived from the unsaturated hydrocarbon ring, cyanide, trialkylphosphine, triarylphosphine, or diphosphine.

6. The manufacturing method according to any one of claims 2 to 5, wherein the metal atom of the complex having the first metal atom comprises at least one of Sr and Ba, and the metal atom of the complex having the second metal atom comprises at least one of Zr and Hf.

7. The manufacturing method according to claim 6, wherein at least one of the metal atoms of the complex having the first metal atom and the metal atoms of the complex having the second metal atom further comprises at least one selected from Ti, Ca, and Mg.

8. The manufacturing method according to any one of claims 2 to 7, wherein the complex having the first metal atom and the complex having the second metal atom are a single compound, forming a binuclear complex.

9. The manufacturing method according to claim 8, wherein the metal atom of the complex having the first metal atom and the metal atom of the complex having the second metal atom are bonded via a ligand coordinated by a sulfur atom, a selenium atom, or a tellurium atom.

10. The method for producing the chalcogenide perovskite according to any one of claims 2 to 9, wherein the chalcogenide perovskite has a composition represented by the following formula (101) or (102): ABCh ３ ...(101) A' ２ A ｎ－１ B ｎ Ch ３ｎ＋１ ... (102) (However, in formulas (101) and (102), A and A' are Mg, Ca, Sr, Ba, or any combination thereof in any ratio, B is Ti, Zr, Hf, or any combination thereof, and Ch is S, Se, Te, or any combination thereof in any ratio. In formula (102), n is an integer between 1 and 10, and A and A' may be the same or different from each other. The chalcogenide perovskite includes a solid solution in which some or all of A, A', B, and Ch are substituted with other elements in the composition represented by formula (101) or (102).) 11. The manufacturing method according to any one of claims 2 to 10, wherein a chalcogen compound is further added to the liquid phase.

12. The manufacturing method according to any one of claims 2 to 11, wherein an amine compound is further added to the liquid phase.

13. The manufacturing method according to any one of claims 2 to 12, wherein the temperature of the liquid phase is set to room temperature to 550°C.

14. The manufacturing method according to claim 13, wherein the temperature of the liquid phase is 120°C to 550°C.

15. The manufacturing method according to any one of claims 2 to 14, wherein the reaction is produced by adding a second raw material, which contains at least the raw material components not included in the first raw material, to a first raw material component containing at least the solvent, from among the raw material components containing the first metal atom complex, the second metal atom complex, and the solvent containing the PAO.

16. The manufacturing method according to claim 15, wherein at least one of the first raw material and the second raw material is preheated, and the second raw material is added to the first raw material to cause the reaction.

17. The manufacturing method according to claim 15, wherein the second raw material is added to the first raw material, and then the first raw material and the second raw material are heated to produce the reaction.

18. The manufacturing method according to any one of claims 2 to 14, comprising simultaneously mixing the complex having the first metal atom, the complex having the second metal atom, and at least one of the chalcogen compound and the amine compound to produce the reaction.

19. The manufacturing method according to claim 18, wherein the reaction is produced by flowing the complex having the first metal atom, the complex having the second metal atom, and at least one of the chalcogen compound and the amine compound as separate flows, and then simultaneously combining the flows.

20. The manufacturing method according to claim 18 or 19, wherein at least one of the complex having the first metal atom, the complex having the second metal atom, the chalcogen compound, the complex having the first metal atom, the complex having the second metal atom, and at least one of the amine compound, or the complex having the first metal atom, the complex having the second metal atom, the chalcogen compound, and at least one of the amine compound is preheated.

21. The manufacturing method according to claim 17, wherein a dispersion in which the complex having the first metal atom and the complex having the second metal atom are dispersed in a dispersion medium containing the PAO is formed into a film by a coating method, a spray method, a doctor blade method, or an inkjet method, and the obtained coating film is heat-treated to obtain the chalcogenide perovskite particles.

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