JP7759435B2 - Luminescent perovskite nanoparticles - Google Patents

Description

Article 30, paragraph 2 of the Patent Act applies [Publications, etc.] Date of issue: February 25, 2019 Publication: Proceedings of the 66th Spring Academic Conference of the Japan Society of Applied Physics, Japan Society of Applied Physics (distributed by CD-ROM) [Publications, etc.] Date of event: March 9, 2019 Meeting name, location: 66th Spring Academic Conference of the Japan Society of Applied Physics, Ookayama Campus, Tokyo Institute of Technology (2-12-1 Ookayama, Meguro-ku, Tokyo) [Publications, etc.] Date of event: June 14, 2019 Meeting name, location: 3rd Symposium of the Electrochemical Society of Japan Student Branch Members, Yamagata University Student Branch, Yamagata University Yonezawa Campus (4-3-16 Jonan, Yonezawa City, Yamagata Prefecture) [Publications, etc.] Date of issue: June 25, 2019 Publication: Proceedings of the 10th International Conference on Organic Molecules and Bioelectronics, p. 302, Japan Society of Applied Physics [Publications, etc.] Date held: June 26, 2019 Meeting name, location: 10th International Conference on Organic Molecules and Bioelectronics, Nara Kasugano International Forum IRAKA (101 Kasugano-cho, Nara City, Nara Prefecture) [Publications, etc.] Issued: September 21, 2019 Publication: Proceedings of the Tohoku Conference of the Association of Chemical Sciences, p. 137, Tohoku Branch of the Chemical Society of Japan [Publications, etc.] Date held: September 21, 2019 (held from September 21 to September 22, 2019) Meeting name, location: Tohoku Conference of the Association of Chemical Sciences, Yamagata University Kojirakawa Campus (1-4-12 Kojirakawa-cho, Yamagata City, Yamagata Prefecture) [Publications, etc.] Issued: October 10, 2019 Publication Proceedings of the 7th International Conference on Smart Systems Engineering, page 59, Yamagata University, National University Corporation, Frontier Flex Graduate School of Organic Materials Systems Creation [Publications, etc.] Date: October 11, 2019 (Dates: October 10, 2019 - October 11, 2019) Name of the conference, location: 7th International Conference on Smart Systems Engineering, Yamagata University, Yonezawa Campus (3-16 Jonan 4-chome, Yonezawa City, Yamagata Prefecture) [Publications, etc.] Date: December 6, 2019 Name of the conference, location: CANON Foundation Reunion 2019 (2F First Square East Tower, 1-5-1 Otemachi, Chiyoda-ku, Tokyo)

Article 30, paragraph 2 of the Patent Act applies [Publications, etc.] Date held: December 11, 2019 (Duration: December 11, 2019 - December 13, 2019) Meeting name, venue: Materials Research Meeting 2019 Yokohama Sangyo Hall Marineria (2 Yamashita-cho, Naka-ku, Yokohama, Kanagawa Prefecture) [Publications, etc.] Date posted on website: December 11, 2019 Website address: https://iopscience.iop.org/article/10.7567/1347-4065/ab4ecd/meta

The present invention relates to luminescent perovskite nanoparticles.

Perovskite-type luminescent nanoparticles have excellent optical and electronic properties, making them a promising material for applications in many fields, including organic light-emitting diodes (LEDs), solar cells, laser light sources, micro-LED displays, liquid crystal displays, and UV sensors (Patent Document 1).

Japanese Patent Application Laid-Open No. 2018-525671

However, there is still room for improvement in the photoluminescence quantum yield (PLQY) of perovskite-type luminescent nanoparticles.

The luminescent nanoparticles of the present invention are perovskite-type luminescent nanoparticles, which have a half-width of 0.53 to 5.5° for the peak corresponding to the (110) plane in a powder X-ray diffraction pattern measured using CuKα radiation, and contain an organic cation as the A-site cation.

The luminescent nanoparticles of the present invention may also be perovskite-type luminescent nanoparticles, in which the half-width of the peak corresponding to the (100) plane in a powder X-ray diffraction pattern measured using CuKα radiation is 0.55 to 1.1°, and which contain an organic cation as the A-site cation.

The luminescent nanoparticles of the present invention are perovskite-type luminescent nanoparticles, in which the half-width of the peak corresponding to the (200) plane in the powder X-ray diffraction pattern measured using CuKα radiation is 0.55° to 1.5°, and may contain an organic cation as the A-site cation.

In the above-mentioned luminescent nanoparticles, it is preferable that 60 mol% or more of the A-site cations are at least one selected from the group consisting of ammonium cations, guanidium cations, imidazolium cations, pyridinium cations, pyrrolidinium cations, and protonated thiourea cations.

The present invention provides luminescent perovskite nanoparticles with improved PLQY.

The luminescent nanoparticles of this embodiment are perovskite-type luminescent nanoparticles, contain an organic cation as an A-site cation, and satisfy at least one of the conditions (1) to (3).
(1) The half-width of the peak corresponding to the (110) plane in the powder X-ray diffraction pattern is 0.53 to 5.5°.
(2) The half-width of the peak corresponding to the (100) plane in the powder X-ray diffraction pattern is 0.55 to 1.1°.
(3) The half-width of the peak corresponding to the (200) plane in the powder X-ray diffraction pattern is 0.55 to 1.5°.
The luminescent nanoparticles preferably satisfy two or more of the conditions (1) to (3), and preferably satisfy all of the conditions (1) to (3). In this specification, the half-width refers to the full width at half maximum. The powder X-ray diffraction pattern is expressed with the horizontal axis representing the diffraction angle (2θ). In this specification, the powder X-ray diffraction pattern is measured using CuKα radiation (wavelength: approximately 0.15418 nm).

The lower limit of the half-width of the peak corresponding to the (110) plane in the powder X-ray diffraction pattern is 0.53°, and preferably 0.55°. The upper limit of the half-width of the peak corresponding to the (110) plane in the powder X-ray diffraction pattern is 5.5°, preferably 4°, more preferably 2°, even more preferably 1.5°, and particularly preferably 1.1°.

The lower limit of the half-width of the peak corresponding to the (100) plane in the powder X-ray diffraction pattern is 0.55°, and preferably 0.56°. The upper limit of the half-width of the peak corresponding to the (100) plane in the powder X-ray diffraction pattern is 1.1°, preferably 1.0°, more preferably 0.9°, even more preferably 0.8°, and particularly preferably 0.75°.

The lower limit of the half-width of the peak corresponding to the (200) plane in the powder X-ray diffraction pattern is 0.55°, preferably 0.56°, and more preferably 0.57°. The upper limit of the half-width of the peak corresponding to the (200) plane in the powder X-ray diffraction pattern is 1.5°, preferably 1.3°, more preferably 1.2°, even more preferably 1.0°, and particularly preferably 0.9°.

In powder X-ray diffraction measurements, corrections such as background correction, smoothing, and kα2 removal may be performed on the acquired data.

The luminescent nanoparticles of this embodiment are perovskite-type luminescent nanoparticles, i.e., compounds represented by the general formula _ABX3 . Here, A is a chemical species occupying the A site (i.e., A-site cation), B is a chemical species occupying the B site (i.e., B-site cation), and X is a chemical species occupying the X site. Note that although the terms A-site cation and B-site cation have formal charges of +1 and +2, respectively, they merely represent the chemical species at the A site and B site, and the actual compound may not necessarily have the charges indicated by the formal charges.

The A-site cation is at least one of an organic cation and an inorganic cation. Inorganic cations include alkali metal ions. Examples of alkali metal ions include Cs ⁺ , Rb ⁺ , K ⁺ , Na ⁺ , and Li ⁺ .

The organic cation at the A site may be a nitrogen-containing organic cation. Examples of the nitrogen-containing organic cation include at least one cation selected from the group consisting of ammonium cation, amidinium cation, guanidinium cation, imidazolium cation, pyridinium cation, pyrrolidinium cation, and protonated thiourea cation. More specifically, examples include cations represented by the following formulas (A-1) to (A-7): primary to quaternary ammonium cation (A-1) (excluding (A-2)), pyrrolidinium cation (A-2), amidinium cation (A-3), guanidinium cation (A-4), imidazolium cation (A-5), pyridinium cation (A-6), and protonated thiourea cation (A-7).

In formula (A-1), R's each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group, a benzyl group, a phenethyl group, a halogen atom, or a pseudohalogen, or two R's together form an alkylene group having 2 to 6 carbon atoms.
When R is an alkyl group, examples of R include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group.
When two R's combine to form an alkylene group having 2 to 6 carbon atoms, examples of the alkylene group include an ethylene group, an n-propylene group, and a 2,2-dimethylpropylene group.
Examples of the cation represented by formula (A-1) include benzylammonium cation, iso-butylammonium cation, n-butylammonium cation, t-butylammonium cation, diethylammonium cation, dimethylammonium cation, ethylammonium cation, methylammonium cation (MA), phenethylammonium cation, iso-propylammonium cation, and n-propylammonium cation, and the methylammonium cation is preferred.

In formulas (A-2) to (A-7), ^R2 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. A methyl group or an ethyl group is preferred, and a methyl group is more preferred. When there are multiple ^R2s in a molecule, the ^R2s may be different from each other or the same.
In formula (A-3), R ¹ represents a methyl group, a hydrogen atom, a halogen atom, or a pseudohalogen.
Examples of the cation of formula (A-3) include acetamidinium cation and formamidinium cation (FA), with formamidinium cation being preferred.
Examples of the cations of formula (A-2) and formulas (A-4) to (A-7) include pyridinium cation, guanidinium cation, imidazolium cation, 1-methylimidazolium cation, pyridinium cation, 1-methylpyridinium cation, and protonated thiourea cation.

At least 60 mol %, preferably at least 70 mol %, and more preferably at least 80 mol % of the A-site cations may be at least one selected from the group consisting of ammonium cations, guanidium cations, imidazolium cations, pyridinium cations, pyrrolidinium cations, and protonated thiourea cations. Also, up to 40 mol %, preferably up to 30 mol %, and more preferably up to 20 mol % of the A-site cations may be amidinium cations. The A-site cations do not necessarily contain amidinium cations.

In particular, ammonium cations are preferred as A-site cations, with primary ammonium cations having an alkyl group with 1 to 4 carbon atoms being more preferred, and methylammonium cations being even more preferred. Ammonium cations should account for at least 60 mol%, preferably at least 70 mol%, and more preferably at least 80 mol% of the A-site cations.

B-site cations include cations of metal elements selected from Ge, Sn, Pb, Sb, Bi, Cu, Ni, Co, Fe, Mn, Cr, Pd, Cd, Eu, Yb, Ag, etc., with Pb or Sn cations being preferred. There may be only one type of B-site cation, or two or more types.

X is a chemical species occupying the X site. The X site is a site located at the vertex of an octahedral structure centered on the element located at the B site, and corresponds to the site where oxygen exists in a perovskite-type oxide. Examples of X include Cl, Br, I, -CN (cyanide), -SCN (thiocyanate), -NSC (isothiocyanate), and -S (sulfide), which may exist as anions or may be coordinately bonded to the element occupying the B site. X is preferably Cl, Br, or I. Luminescent nanoparticles can contain one or more chemical species as X.

A, B, and X can be selected appropriately taking into consideration the potential within the luminescent nanoparticle and the sizes of the atoms contained in A, B, and X.

The luminescent nanoparticles may be surface-treated with a surfactant. There are no particular limitations on the surfactant, and it may be any of a nonionic surfactant, cationic surfactant, zwitterionic surfactant, and anionic surfactant.

Preferred surfactants include amine compounds, quaternary ammonium salts, and carboxylic acids with 8 to 30 carbon atoms.

The carbon number of the carboxylic acid as a surfactant is preferably 10 to 25, and more preferably 12 to 20. The carboxylic acid may be a monocarboxylic acid or a polycarboxylic acid. The carboxyl groups of the carboxylic acid may be partially or completely neutralized (i.e., partially or completely may be in the form of a salt). The salt of the carboxylic acid is not particularly limited, but examples thereof include alkali metal salts. The carboxylic acid as a surfactant may be either an aromatic carboxylic acid or an aliphatic carboxylic acid, but is preferably an aliphatic carboxylic acid. The aliphatic carboxylic acid is preferably a fatty acid.
The fatty acid preferably has 8 to 30 carbon atoms, and more preferably 12 to 20 carbon atoms. Specific examples of the fatty acid include oleic acid, stearic acid, palmitic acid, etc., with oleic acid being preferred. Examples of the salt of the fatty acid include alkali metal salts.
Examples of aromatic carboxylic acids include 3-phenylpropionic acid, 4-phenyl-3-butenoic acid, phenylacetic acid, and benzoic acid.

The amine compound as a surfactant may be any of a primary amine compound, a secondary amine compound, and a tertiary amine compound, and may be either an aromatic amine or an aliphatic amine.
Examples of the hydrocarbon group contained in the amine compound as a surfactant include an alkyl group, an alkenyl group, an aryl group, and a cycloalkyl group, and the alkyl group is preferred. The alkyl group may be a linear or branched alkyl group.
The aliphatic amine compound is preferably a primary aliphatic monoamine compound. Examples of the primary aliphatic amine compound include primary aliphatic amine compounds having an aliphatic hydrocarbon group having 2 to 20 carbon atoms, more specifically, propylamine, butylamine, pentylamine, octylamine, hexadecylamine, octadecylamine, etc., with octylamine being preferred. Examples of the aliphatic amine compound also include aliphatic diamines such as 1,8-octyldiamine.
Examples of aromatic amines include benzylamine, phenethylamine, 3-phenyl-2-propen-1-amine, phenylmethylamine, 2,2'-iminodibenzoic acid, aniline, 3-phenylpropylamine, and 4-phenylbutylamine.
Examples of quaternary ammonium salts as surfactants include aliphatic quaternary ammonium salts, such as didodecyldimethylammonium and 3-(N,N-dimethyloctadecylammonio)propanesulfonate.

The surfactant may contain a phosphorus-containing compound such as phosphonic acid or phospholipid. Examples of phosphonic acid include octylphosphonic acid and tetradecylphosphonic acid. Examples of phospholipid include trioctylphosphine oxide.
The surfactant may also contain an alkylthiol. The alkylthiol may be an alkylthiol having 6 to 20 carbon atoms, and specific examples thereof include 1-octanethiol.

The luminescent nanoparticles may be surface-treated with a metal halide compound. Examples of the metal halide compound include metals other than the B-site metals, more specifically, Zn, Mn, Ga, In, etc. Examples of the metal halide compound include ZnBr ₂ , MnBr ₂ , GaBr ₂ , InBr ₂ , etc. When modified with a metal halide compound, the luminescent nanoparticles are preferably those in which the chemical species occupying the A-site is a metal element.

The luminescent nanoparticles of this embodiment have excellent PLQY. As described in Patent Document 1 and elsewhere, conventional perovskite-type luminescent nanoparticles have a very small half-width of the peak corresponding to the (110), (100), or (200) plane in the powder X-ray diffraction pattern, for example, approximately 0.1°. However, after extensive research, the inventors have found that the PLQY actually improves when the half-width of the peak corresponding to the (110), (100), or (200) plane in the powder X-ray diffraction pattern is in a range larger than conventional values (i.e., within the range of conditions (1) to (3)). The reason for this is not entirely clear, but it is believed that the broadening of the half-width indicates the formation of an amorphous structure, and that the amorphous state of the nanocrystal surface acts as a passivation layer, improving the PLQY.

The method for producing the perovskite-type luminescent nanoparticles of this embodiment is not particularly limited, but they can be produced, for example, by the LARP (Ligand Assisted Reprecipitation) method.

In the LARP method, a precursor solution is first prepared by dissolving raw materials and ligands in a good solvent. Next, a poor solvent is added to the precursor solution, causing luminescent nanoparticles to precipitate. Adding the poor solvent batchwise to the precursor solution in a single reaction vessel makes it easier to obtain luminescent nanoparticles that satisfy at least one of the above conditions (1) to (3).

The raw materials for the luminescent nanoparticles include raw materials containing A-site chemical species, raw materials containing B-site chemical species, and compounds containing X-site chemical species. The raw materials for the luminescent nanoparticles may be any material that can provide any of A, B, and X in the general formula _ABX3, and may contain multiple A, B, and X chemical species.

Examples of raw materials containing A-site chemical species include compounds containing A-site chemical species and X. For example, if the A-site cation contains an alkali metal ion, the raw material containing the A-site cation is preferably a salt of an alkali metal and X, and is preferably an alkali metal halide. However, compounds that do not contain X, such as alkali metal carbonates and alkali metal acetates, may also be used.

When the chemical species at the A site is an organic cation, examples of suitable raw materials include salts of the organic cation and X. More specifically, examples of raw materials containing the chemical species at the A site include at least one compound selected from the group consisting of ammonium salts, amidinium salts, guanidinium salts, imidazolium salts, pyridinium salts, pyrrolidinium salts, and salts of protonated thiourea. These salts are preferably halide salts, and more preferably bromide salts, iodide salts, or chloride salts. Examples of raw materials containing the chemical species at the A site include ammonium halide salts such as methylammonium bromide, and formamidinium halide salts such as formamidinium bromide.

Examples of raw materials containing B-site cations include B-site metal-containing compounds, such as salts of B-site cations and X. The B-site metal-containing compound is preferably a compound containing at least one metal element selected from the group consisting of Ge, Sn, Pb, Sb, Bi, Cu, Ni, Co, Fe, Mn, Cr, Pd, Cd, Eu, Yb, and Ag. More specifically, the B-site metal-containing compound includes halides (fluorides, chlorides, bromides, or iodides) of Ge, Sn, Pb, Sb, or Bi, with bromides, iodides, or chlorides of Ge, Sn, Pb, Sb, or Bi being preferred.

Compounds containing X-site chemical species include compounds containing the above-mentioned A-site or B-site chemical species and X-site chemical species, as well as compounds such as HCl and HI that do not contain either A-site or B-site chemical species.

Examples of ligands include those exemplified as surfactants above. However, using an aliphatic monoamine (preferably one having an alkyl group with 3 to 16 carbon atoms) or an aromatic amine in combination with a carboxylic acid with 8 to 30 carbon atoms makes it easier to obtain luminescent nanoparticles that satisfy at least one of the above conditions (1) to (3). The alkyl group of the aliphatic monoamine used as a ligand may be either a branched or linear alkyl group, but a linear alkyl group is preferred. Furthermore, the number of carbon atoms in the alkyl group of the aliphatic monoamine is preferably 3 to 16, more preferably 4 to 12, and even more preferably 4 to 8. Specific examples of alkyl groups of aliphatic monoamines include n-propyl, butyl, pentyl, hexyl, heptyl, and octyl groups.

Aromatic amines used as ligands include amines having an aryl group, with amines having a phenyl group or a substituted phenyl group being particularly preferred. Among these, compounds having a structure in which a phenyl group or a substituted phenyl group is linked to a nitrogen atom via an alkylene group having 2 to 6 carbon atoms are preferred. Specific examples include 2-phenylethylamine, 3-phenylpropylamine, and 4-phenylbutylamine, with 2-phenylethylamine being particularly preferred. Substituents on the substituted phenyl group include halogen atoms. Substituted phenyl groups preferably have one or two substituents per phenyl group. Examples of aromatic amines having a substituted phenyl group include 2-phenylethylamine, 3-phenylpropylamine, and 4-phenylbutylamine, in which the hydrogen atom of the phenyl group is substituted with a substituent (e.g., a halogen atom).

As the carboxylic acid ligand, a carboxylic acid having 8 to 30 carbon atoms is preferred, a carboxylic acid having 10 to 20 carbon atoms is more preferred, and a carboxylic acid having 12 to 20 carbon atoms is even more preferred. Specific examples of carboxylic acids as ligands include oleic acid, stearic acid, and palmitic acid.

Good solvents include those with a solubility (25°C) of 1 g/L or more for the raw material, such as N-methylpyrrolidone (NMP) and N,N-dimethylformamide (DMF).

Examples of poor solvents include those with a solubility (25°C) of less than 1 g/L in the raw material. Specific examples include hydrocarbon solvents such as toluene, hexane, and octadecene, and halogenated hydrocarbon solvents such as chlorobenzene and chloroform. The solubility of the poor solvent in the raw material is preferably 10 mg/L or less, and more preferably 1 mg/L or less.

The amount of poor solvent used is preferably 10 times or more, and more preferably 15 times or more, by volume relative to the precursor solution, in order to prevent re-dissolution of the luminescent nanoparticles after they have precipitated.

There are no restrictions on the amount of ligand used (amount added), as long as it is equal to or less than the saturation solubility (the maximum amount of surfactant that can dissolve in the dispersion medium at the reaction temperature), and it is preferably 1% by mass or less of the total amount of raw materials for the luminescent nanoparticles. The ligands used during production may be removed from the luminescent nanoparticles by washing after production, or the ligands may be almost completely removed. Furthermore, from the perspective of suppressing aggregation of the luminescent nanoparticles, the luminescent nanoparticles may be surface-treated with another surfactant after ligand removal. Alternatively, a surfactant may be added to the resulting luminescent nanoparticles for further surface treatment without removing the ligands.

The molar ratio of the raw material containing the A-site chemical species to the raw material containing the B-site chemical species in the above mixture is not particularly limited, but the raw material containing the B-site chemical species can be used in excess of the raw material containing the A-site chemical species. For example, the molar ratio of the A-site chemical species to the B-site chemical species is preferably 1.0:1.0 to 1.0:35, and more preferably 1.0:1.0 to 1.0:7. The raw material containing the A-site chemical species can also be used in excess of the raw material containing the B-site chemical species. In this case, the molar ratio of the A-site chemical species to the B-site chemical species is preferably 1.0:1.0 to 70:1.0, and more preferably 1.0:1.0 to 14:1.0.

The resulting luminescent nanoparticles can be recovered by separation methods such as decantation, filtration, and centrifugation.

The luminescent nanoparticles of this embodiment can be used in organic LEDs, solar cells, laser light sources, micro LED displays, liquid crystal displays, UV sensors, and the like. The luminescent nanoparticles of this embodiment can be used as a composition containing the luminescent nanoparticles and a binder. Examples of binders include resins, which may be either thermoplastic resins or thermosetting resins. To improve dispersibility in the binder, the surfaces of the luminescent nanoparticles of this embodiment may be surface-modified with a dispersant such as a silane coupling agent.

(Production Examples 1 to 7)
As raw materials, 3.6 mg of methylammonium bromide and 14.7 mg of lead(II) bromide were dissolved in 1 mL of N,N-dimethylformamide, and 4 μL of an amine compound shown in Table 1 and 5 μL of oleic acid were added as ligands to prepare a precursor solution.
The obtained precursor solution was added to chloroform in a volume ratio of 25 times to obtain a dispersion liquid in which luminescent nanoparticles were dispersed.

The dispersions obtained in Production Examples 1 to 7 were centrifuged at 9000 rpm for 10 minutes. After centrifugation, the precipitate layer was collected from the dispersion, applied to a glass plate, and dried overnight to obtain a measurement sample.
The powder X-ray diffraction pattern was measured using the above measurement sample. The equipment used was a "Fully Automatic Multipurpose X-ray Diffractometer SmartLab 9kW" manufactured by Rigaku Corporation, and the radiation source used was CuKα radiation. The acquired powder X-ray diffraction measurement data was imported into Rigaku Integrated Powder X-ray Analysis Software, and "background correction, smoothing, and kα2 removal" processing was performed. The results are shown in Table 2.

The fluorescence intensity of the luminescent nanoparticles was measured using a fluorescence spectrophotometer (manufactured by HORIBA, product name: FluoroMax-2) to determine the emission peak wavelength of the luminescent nanoparticles. PLQY was also measured using an absolute PL quantum yield analyzer (manufactured by Hamamatsu Photonics, product name: C9920-01). The results are shown in Table 2.

Claims (4)

Luminescent nanoparticles of the perovskite type comprising a compound represented by the general formula _ABX3 ,
the half-width of the peak corresponding to the (110) plane in the powder X-ray diffraction pattern measured using CuKα radiation is 0.53 to 2 °;
containing a nitrogen-containing organic cation as an A-site cation;
containing at least one cation of Pb and Sn as a B-site cation;
Luminescent nanoparticles, wherein X comprises Cl, Br, or I. Luminescent nanoparticles of the perovskite type comprising a compound represented by the general formula _ABX3 ,
the half-width of the peak corresponding to the (100) plane in the powder X-ray diffraction pattern measured using CuKα radiation is 0.55 to 0.9 °;
containing a nitrogen-containing organic cation as an A-site cation;
containing at least one cation of Pb and Sn as a B-site cation;
Luminescent nanoparticles, wherein X comprises Cl, Br, or I. Luminescent nanoparticles of the perovskite type comprising a compound represented by the general formula _ABX3 ,
the half-width of the peak corresponding to the (200) plane in the powder X-ray diffraction pattern measured using CuKα radiation is 0.55 to 1.2 °;
containing a nitrogen-containing organic cation as an A-site cation;
containing at least one cation of Pb and Sn as a B-site cation;
Luminescent nanoparticles, wherein X comprises Cl, Br, or I. The luminescent nanoparticle according to any one of claims 1 to 3, wherein 60 mol% or more of the A-site cations are at least one selected from the group consisting of ammonium cations, guanidium cations, imidazolium cations, pyridinium cations, pyrrolidinium cations, and protonated thiourea cations.