Thin film, device, and method for manufacturing thin film

Abstract

This thin film includes chalcogenide perovskite particles and an organic component that modifies the particles. A mean square roughness of the thin film surface is less than 1000 nm.

Description

Thin film, device and method for manufacturing thin film

[0001] The present invention relates to thin films comprising chalcogenite perovskites.

[0002] In recent years, semiconductor light-emitting materials have been widely used as light-emitting materials in lighting and display devices, wavelength conversion (color conversion, down-conversion) elements, and also as photoelectric conversion materials in photoelectric conversion elements. In these fields, high durability (e.g., stability against water, oxygen, heat, etc.) and high light absorption properties are required of materials. Therefore, as this type of semiconductor light-emitting material, chalcogenite perovskites have attracted attention because they have superior durability and a high light absorption coefficient compared to other materials and do not contain harmful metals.

[0003] When chalcogenite perovskite is applied to various devices, a thin film containing chalcogenite perovskite can be formed on the device as one embodiment. Thin films containing chalcogenite perovskite are known, for example, from the following Non-Patent Documents 1 to 3.

[0004] Xiucheng Wei et al., “Realization of BaZrS3 chalcogenide perovskite thin films for optoelectronics”, Nano Energy Volume 68, February 2020, 104317Apurva A. Pradhan et al., “Synthesis of BaZrS3 and BaHfS3 Chalcogenide Perovskite Films Using Single-Phase Molecular Precursors at Moderate Temperatures”, Angew. Chem.Int. Ed.2023,62, e2023010Vikash Kumar Ravi et al., “Colloidal BaZrS3 chalcogenide perovskite nanocrystals for thin film device fabrication”, Nanoscale, 2021,13, 1616-1623

[0005] In the above-mentioned Non-Patent Documents 1 and 2, when forming a thin film, the material is exposed to high temperatures due to sputtering or precursor baking, which causes the organic matter contained in the thin film material to volatilize. Therefore, in Non-Patent Documents 1 and 2, it is not possible to add an organic matter as a ligand to the chalcogenite perovskite in the thin film to impart functions such as surface passivation or electrical conduction / insulation.

[0006] On the other hand, the surfaces of the thin films in Non-Patent Documents 2 and 3 are uneven and rough, which tends to reduce the optical performance of the thin films. Furthermore, in Non-Patent Documents 2 and 3, when other films are laminated on the thin films to form multilayer films, defects such as voids tend to occur between the films.

[0007] In one embodiment, the thin film includes chalcogenide perovskite particles and an organic component that modifies the particles. The thin film surface has a root mean square roughness of less than 1000 nm.

[0008] According to one embodiment, a thin film can be provided that is excellent in smoothness and is suitable for improving the luminescence properties of chalcogenite perovskite and controlling electrical conductivity.

[0009] 1A is a schematic cross-sectional view of a thin film according to the present embodiment, (a) is a view showing the cross section of the thin film in an example under a scanning electron microscope, and (b) is a view showing the surface of the thin film in an example under an atomic force microscope. (a) is a graph showing the X-ray diffraction spectrum of the thin film in the example, and (b) is a graph showing the results of absorption spectroscopy measurement of the thin film in the example.

[0010] Hereinafter, embodiments will be described with reference to the drawings. In the embodiments, in order to make the description easier to understand, structures or elements other than the main parts of the present invention will be described in a simplified or omitted manner. Furthermore, in the drawings, the same elements are given the same reference numerals. Note that in the drawings, the shape, dimensions, etc. of each element are shown schematically and do not represent the actual shape, dimensions, etc.

[0011] <Example of Thin Film Configuration> Fig. 1 is a cross-sectional schematic diagram of a thin film 1 according to this embodiment. The thin film 1 of this embodiment is formed by agglomerating chalcogenide perovskite particles 2 in a planar form on a substrate 3. The particles 2 may be deposited in the thickness direction of the substrate 3. The substrate 3 on which the thin film 1 is formed may be appropriately selected from a semiconductor substrate, a glass substrate, a resin substrate, a metal substrate, etc., depending on the application of the device described below. The substrate 3 may also be a flexible substrate.

[0012] The chalcogenite perovskite particles 2 are so-called nanoparticles whose overall shape is on the order of nanometers.

[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 a transition metal element and an alkaline earth metal element, as components of the perovskite-type crystal structure.

[0014] In this embodiment, the chalcogenide perovskite has a composition represented by the following formula (1) or (2), for example: ABCh ３ ... (1) A' ２ A ｎ－１ B ｎ Ch ３ｎ＋１ ...(2)

[0015] In formulas (1) and (2), A and A' are Mg, Ca, Sr, Ba, or a combination of these in any ratio; B is Ti, Zr, Hf, or a combination of these in any ratio; and Ch is S, Se, Te, or a combination of these in any ratio. In formula (2), n is an integer of 1 or more and 10 or less. In formula (2), A and A' may be the same or different.

[0016] In this embodiment, the chalcogenide perovskite may be a solid solution in which part or all of A, A', B, and Ch in the composition represented by formula (1) or (2) are substituted with other elements.

[0017] Chalcogenide perovskite (ABCh) represented by formula (1) ３ ) indicates, for example, the crystal structure of cubic perovskite, tetragonal perovskite, orthorhombic perovskite, or double perovskite. As an example, chalcogenite perovskite expressed by the chemical formula ABCh3 includes the following substances. In the following examples, Ch is selected from (S, Se), which are dominant materials among chalcogen elements, A is selected from (Sr, Ba), which are dominant materials among elements in Group 2, and B is selected from (Zr, Hf), which are dominant materials among elements in Group 4: SrZrS3, SrZrSe3, SrHfS3, SrHfSe3, BaZrS3, BaZrSe3, BaHfS3, BaHfSe3

[0018] A chalcogenide perovskite (A') represented by formula (2) ２ A ｎ－１ B ｎ Ch ３ｎ＋１ ) represents, for example, the crystal structure of a Ruddlesden-Popper type layered perovskite. ２ A ｎ－１ B ｎ Ch ３ｎ＋１ The chalcogenite perovskite represented by the formula (1) includes the following substances: Ch is selected from (S, Se) which is a dominant material among chalcogen elements, A, A' are selected from (Sr, Ba) which is a dominant material among elements in Group 2, and B is selected from (Zr, Hf) which is a dominant material among elements in Group 4. SrBa n-1 Zr n S 3n+1 , SrBa n-1 Zr n Se 3n+1 , Sr n+1 Zr n S 3n+1 , Sr n+1 Zr n Se 3n+1 , BaSr n-1 Zr n S 3n+1 , BaSr n-1 Zr n Se 3n+1 , Ba n+1 Zr nS 3n+1 , Ba n+1 Zr n Se 3n+1 , SrBa n-1 Hf n S 3n+1 , SrBa n-1 Hf n Se 3n+1 , Sr n+1 Hf n S 3n+1 , Sr n+1 Hf n Se 3n+1 , BaSr n-1 Hf n S 3n+1 , BaSr n-1 Hf n Se 3n+1 , Ba n+1 Hf n S 3n+1 , Ba n+1 Hf n Se 3n+1

[0019] These chalcogenide perovskites include (Sr x Ba 1-x ) (Zr y Hf 1-y ) (S z Se 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 Se 1-z ) 3n+1 (where x, x', y, and z are values ​​between 0 and 1).

[0020] In chalcogenide perovskites, the carrier concentration or crystal structure can be controlled, and other physical and chemical properties can be adjusted, by partially substituting elements of the same or different groups for the constituent elements. For example, elements of Group 1 can be substituted with elements of Groups 1 and 2, elements of Group 2 with elements of Groups 1, 2, and 3, elements of Group 3 with elements of Groups 2, 3, and 4, elements of Group 4 with elements of Groups 3, 4, and 5, and elements of Group 16 with elements of Groups 15, 16, and 17.

[0021] The chalcogenide perovskite particles 2 preferably have an average particle size of at least 1 nm or more so that they can exist stably.

[0022] On the other hand, if the particle size of the particles 2 is large, when a large number of particles 2 are contained in the thin film 1, the gaps become larger, reducing the density of the particles 2 in the thin film 1, which may result in a reduction in the optical function of the thin film 1. Furthermore, large particle sizes of the particles 2 may also pose a problem in the film formation process of the thin film 1. For example, when applying ink in which the particles 2 are dispersed in a solvent by an inkjet method, nozzle clogging may occur if the particle size of the particles 2 is too large.

[0023] From the above viewpoints, the average particle size of the particles 2 is preferably less than 1000 nm, more preferably less than 100 nm, even more preferably less than 40 nm, even more preferably less than 30 nm, even more preferably less than 20 nm, and particularly preferably less than 12 nm.

[0024] Furthermore, the above-mentioned particles 2 are preferably synthesized by a liquid-phase synthesis method, such as a hot injection method, a heat-up method, or a flow synthesis method. Compared to solid-phase synthesis, liquid-phase synthesis is less likely to introduce impurities into the particles during the synthesis process. Furthermore, liquid-phase synthesis is characterized by uniform nucleation and particle growth from the liquid phase, making it possible to obtain fine nanoparticles with a narrow particle size distribution by preventing aggregation of the nuclei generated in the liquid phase (see, for example, "Kanie, S. et al., 'Liquid-Phase Synthesis of Size- and Shape-Controlled Functional Inorganic Nanoparticles and Their Application to Hybrid Materials through Surface Precise Organic Modification,' Journal of the Japanese Society for Crystal Growth, 2017, Vol. 44, No. 2, pp. 66-73"). Therefore, liquid-phase synthesis minimizes the incorporation of impurities into particles 2, and enables the production of chalcogenide perovskite nanoparticles with a narrow and uniform particle size distribution. Furthermore, when using liquid-phase synthesis, the average particle size of particles 2 can be easily controlled, for example, by adjusting the concentration of each complex in the liquid phase and the reaction time.

[0025] Furthermore, although not particularly limited, the above-mentioned particle 2 may have a core-shell structure in which an inner core is covered with an outer shell. In the case of particle 2 having a core-shell structure, the core may be formed of a chalcogenide perovskite, and the shell may be formed of a chalcogenide perovskite. Furthermore, the core and the shell may be formed of different chalcogenide perovskites.

[0026] Furthermore, the chalcogenide perovskite particles 2 in this embodiment are surface-modified with ligands 4 of organic components.

[0027] The ligands 4, for example, serve to facilitate isolation of the particles 2 from one another. The ligands 4 improve dispersibility in a dispersion medium such as a solvent or a polymer compound, and also suppress regrowth or destruction due to contact between the particles 2. The ligands 4 also suppress surface defects of the particles 2 by capping the tangling bonds, thereby improving the luminescence efficiency of the chalcogenide perovskite. The ligands 4 may also have an electrical conducting / insulating function and be added to control the electrical conductivity of the particles 2.

[0028] There is no limitation on the type of organic component of the ligand 4 that modifies the particle 2. As an example, the organic component includes one or more selected from the group consisting of polymer materials and molecules having functional groups.

[0029] The polymeric material as the organic component may be, for example, one or more selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polystyrene, and polycarbonate. The molecule having a functional group as the organic component may be one or more selected from the group consisting of amine, carboxylic acid, thiol, and phosphine.

[0030] The thickness of the thin film 1 is at least equal to or greater than the particle diameter of the particles 2, and is set appropriately based on the specifications of the optical performance required of the thin film 1 in the device.

[0031] Furthermore, in the thin film 1, the particles 2 are distributed approximately uniformly in the planar direction of the substrate 3. Therefore, the smoothness of the surface of the thin film 1 in this embodiment is determined according to the average particle size of the particles 2. For example, the root mean square roughness (RMS) of the surface of the thin film 1 has a positive correlation with the average particle size of the particles 2 contained in the thin film 1, and the smaller the average particle size of the particles 2 contained in the thin film 1, the smaller the root mean square roughness of the surface of the thin film 1. In this embodiment, by forming the thin film 1 using chalcogenite perovskite particles 2 on the order of nanometers, a chalcogenite perovskite thin film with high smoothness can be realized.

[0032] As an example, when the average particle size of the particles 2 contained in the thin film 1 is less than 1000 nm, the root mean square roughness of the surface of the thin film 1 is less than 1000 nm. When the average particle size of the particles 2 contained in the thin film 1 is less than 100 nm, the root mean square roughness of the surface of the thin film 1 is less than 100 nm. When the average particle size of the particles 2 contained in the thin film 1 is less than 40 nm, the root mean square roughness of the surface of the thin film 1 is less than 40 nm. When the average particle size of the particles 2 contained in the thin film 1 is less than 12 nm, the root mean square roughness of the surface of the thin film 1 is less than 12 nm.

[0033] The root mean square roughness of the surface of the thin film 1 is preferably less than 1000 nm, more preferably less than 100 nm, even more preferably less than 40 nm, even more preferably less than 30 nm, even more preferably less than 20 nm, and particularly preferably less than 12 nm.

[0034] The function of the thin film 1 of this embodiment will be described below. The thin film 1 of this embodiment includes chalcogenide perovskite particles 2 and organic ligands 4 that modify the particles 2. The chalcogenide perovskite particles 2 in the thin film 1 are modified with the organic ligands 4. Therefore, the thin film 1 of this embodiment makes it relatively easy to improve the luminescence characteristics of the particles 2 and control their electrical conductivity, thereby further improving the electrical and optical functions of the thin film 1. Furthermore, the thin film 1 of this embodiment has a surface with a root mean square roughness of less than 1000 nm, providing high smoothness on the nanometer order. Therefore, the thin film 1 of this embodiment makes it easy to suppress light scattering on the thin film surface. Furthermore, when forming a multilayer film by stacking other films on the thin film 1, defects such as voids are less likely to occur between films, which can improve the yield of devices using the thin film 1.

[0035] <Method for Manufacturing Thin Film> The method for manufacturing the thin film 1 in this embodiment is not particularly limited as long as the chalcogenite perovskite particles 2 having the above average particle size are contained in the thin film 1 and the organic component ligands 4 remain in the thin film 1.

[0036] As an example, a dispersion in which nanoparticles of chalcogenide perovskite are dispersed in a liquid dispersion medium, or a precursor material of chalcogenide perovskite (e.g., 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) is used to form a film on a substrate by a solution film formation method such as coating, spraying, doctor blade, or inkjet.The substrate after film formation can then be dried, fired, or otherwise treated as necessary to form a thin film of chalcogenide perovskite.

[0037] The method for producing the thin film is not limited to the above-described film formation method, and for example, a thin film of chalcogenide perovskite may be formed by forming a film from chalcogenide perovskite nanoparticles (e.g., powder containing nanoparticles, a molded or fired body of the powder, etc.) or a precursor material of chalcogenide perovskite using a vacuum process such as vacuum deposition, and then, if necessary, performing firing or other treatments.

[0038] When the thin film 1 is heated, baked, or otherwise processed in the manufacturing process thereof, the temperature to which the thin film 1 is heated is set, for example, to a temperature lower than the boiling point of the organic component of the ligand 4. Even when the thin film 1 is heated at a temperature equal to or higher than the boiling point of the solvent, the organic component may remain due to bonding between the nanoparticles and molecules, and therefore the temperature to which the thin film 1 is heated may be equal to or higher than the boiling point of the organic component of the ligand 4.

[0039] Furthermore, when treatments such as heating and firing are performed in the manufacturing process of the thin film 1, the chalcogenide perovskite particles 2 in the thin film 1 that is finally obtained do not necessarily need to maintain the particle shape that they had before the heating treatment or the like.

[0040] <Applications of Thin Film> The chalcogenide perovskite thin film 1 according to this embodiment can be applied to a wide range of applications without any particular limitations. The chalcogenide perovskite thin film 1 according to this embodiment is suitable, for example, as a light-emitting material in light-emitting devices such as displays, or as an element of a wavelength conversion element or a photoelectric conversion element. Furthermore, the chalcogenide perovskite thin film 1 according to this embodiment can be applied, for example, to down-conversion of ultraviolet light, blue light, or the like in various devices.

[0041] Furthermore, the chalcogenide perovskite thin film 1 according to this embodiment can be suitably used in the manufacture of various devices such as light-emitting devices such as LEDs and organic EL devices, display devices including such light-emitting devices, lighting devices including such light-emitting devices, image sensors, photoelectric conversion devices, bioluminescent tags, etc. In other words, the various devices described above can include the chalcogenide perovskite thin film 1 according to this embodiment.

[0042] Examples of the present invention will be described below. In the examples, precursor complexes were synthesized according to the following Production Examples 1 and 2, and nanoparticles were synthesized using these precursor complexes. Then, thin films containing nanoparticles were formed, and the physical properties of the obtained thin films were analyzed.

[0043] (Production Example 1: Synthesis of Ba diisobutyldithiocarbamate) Barium hydroxide (5140 mg) was weighed into a 100 ml three-neck flask, 50 ml of purified water was added, and the flask was sealed and stirred. Next, diisobutylamine (10.39 ml) was added to the three-neck flask, and after stirring for an additional 10 minutes, carbon disulfide (3.63 ml) was added and stirred for 3 hours. Gradual precipitation of a white solid was observed upon stirring. The precipitated solid was collected by filtration, washed with hexane, and then vacuum dried to obtain a compound containing Ba diisobutyldithiocarbamate. The yield of the compound was approximately 70%.

[0044] (Production Example 2: Synthesis of Zr diisobutyldithiocarbamate) Zirconium chloride (2913 mg) was weighed into a 200 ml three-neck flask, 75 ml of THF was added, and the container was sealed and stirred for approximately 15 minutes. Next, diisobutylamine (29.2 ml) was added to the three-neck flask and stirred for 10 minutes. After that, carbon disulfide (10.2 ml) was added and stirred for an additional 3 hours. After stirring was completed, the precipitated solid was filtered, and the filtrate was recovered and transferred to another container. Next, the solvent was removed from the recovered filtrate using a known method, and the resulting residue was dispersed in hexane to obtain a white suspension. The white suspension was filtered, and the resulting solid was washed with hexane and then vacuum dried to obtain a synthetic product containing Zr diisobutyldithiocarbamate. The yield of the synthetic product was approximately 80%.

[0045] (Synthesis of nanoparticles) Ba diisobutyldithiocarbamate (527.94 mg) obtained in Production Example 1 and Zr diisobutyldithiocarbamate (908.76 mg) obtained in Production Example 2 were weighed into a 50 ml three-necked flask, and 1-octadecene (5 ml) was added and stirred. Next, the three-necked flask was heated to a temperature of 1000° C., and the internal atmosphere was changed to N 2 ２ While being kept in the ambient atmosphere, the flask was moved into a draft and heated to 310°C at a rate of 5°C / min. Then, room temperature oleylamine (3200 mg) was injected using a Luer-lock syringe. Next, the solution in the three-neck flask was stirred for 3 hours while being kept at 310°C. After the reaction was completed, the reaction solution was washed with toluene and ethanol, and the recovered BaZrS ３The nanoparticles were dispersed in 5 mml of chloroform.

[0046] (Evaluation of particle size of nanoparticles) A ​​chloroform dispersion of the synthesized nanoparticles was dropped onto a TEM grid, dried, and observed using a scanning transmission electron microscope (manufactured by JEOL Ltd., "JSM-7610F") at an acceleration voltage of 5 kV and a magnification of 200,000 or 400,000 (hereinafter referred to as STEM observation). Observation was performed at multiple arbitrary locations, and the number average particle size of the particles contained in the obtained observation image was taken as the average particle size.

[0047] (Formation of a thin film containing nanoparticles) The cleaned glass substrate with FTO was placed on a spin coater, and the spin coater was rotated at 1000 rpm. ３ 100 μL of the chloroform dispersion was dropped onto a glass substrate, and rotation was continued for 40 seconds after the drop. Then, rotation of the spin coater was stopped, and ethanol was dropped onto the glass substrate and held for 20 seconds. Next, the glass substrate was rotated at 4000 rpm using the spin coater to remove the ethanol from the glass substrate. The glass substrate was then placed on a hot plate set at 85°C and dried.

[0048] (Analysis of Thin Film) In the examples, a cross section of the thin film obtained in the above steps was observed using a scanning electron microscope (SEM, S-4300 manufactured by Hitachi High-Technologies).

[0049] 2(a) is a diagram showing a cross section of a thin film taken by a scanning electron microscope in the example. In the example, as shown in FIG. 2(a), BaZrS ３ It can be seen that the thin film is formed almost uniformly.

[0050] In the examples, the surface of the thin film obtained in the above steps was observed using an atomic force microscope (AFM, AFM5300E manufactured by Hitachi High-Technologies) to evaluate the root mean square roughness (RMS) of the thin film surface.

[0051] 2(b) is a diagram showing the surface of the thin film in Example 1, as viewed with an atomic force microscope. The root mean square roughness of the surface of the thin film in Example 1 was 3.4 nm.

[0052] In the examples, the crystallinity of the thin film obtained in the above steps was evaluated using an X-ray diffraction measurement device (XRD, X7Pert Pro manufactured by Malvern Panalytical).

[0053] 3(a) is a graph showing the X-ray diffraction spectrum of the thin film of the example. The diffraction spectrum profile of FIG. 3(a) is ３ The peak positions match well with the characteristics of the database. Therefore, from FIG. 3(a), it can be seen that the thin film of the example is BaZrS ３ It is found to contain

[0054] In the examples, the organic components in the thin films obtained in the above steps were evaluated using a Fourier transform infrared absorption spectrophotometer (FT-IR, IRSpirit manufactured by Shimadzu Corporation).

[0055] FIG. 3(b) is a graph showing the results of absorption spectroscopy of the thin film of the example. The horizontal axis of FIG. 3(b) represents wavelength, and the vertical axis of FIG. 3(b) represents transmittance. In the graph of FIG. 3(a), the amino group (NH ２ 3B, a decrease in transmittance due to absorption from the organic component can be seen.

[0056] Although the embodiments of the present invention have been described above, they are presented as examples and are not intended to limit the scope of the present invention. The 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. The embodiments and their modifications are included within the scope and spirit of the present invention, and the inventions described in the claims and their equivalents are also included within the scope and spirit of the present invention.

[0057] This application claims priority based on Japanese Patent Application No. 2024-057127, filed on March 29, 2024, the entire contents of which are incorporated herein by reference.

[0058] 1... Thin film 2... Particle 3... Substrate 4... Ligand

Claims

1. A thin film comprising particles of a chalcogenide perovskite and an organic component modifying the particles, wherein the mean square roughness of the surface of the thin film is less than 1000 nm.

2. The thin film of claim 1, wherein the particles have an average particle size of less than 1000 nm.

3. The thin film according to claim 2, wherein the average particle size of the particles is 1 nm or more and less than 40 nm.

4. A thin film according to any one of claims 1 to 3, wherein the mean square roughness of the surface of the thin film is less than 100 nm.

5. The thin film of claim 4, wherein the mean square roughness of the thin film surface is less than 40 nm.

6. The thin film of claim 5, wherein the mean square roughness of the thin film surface is less than 12 nm.

7. The thin film according to any one of claims 1 to 6, wherein the chalcogenide perovskite has a composition represented by the following formula (1) or (2): ABCh ３ ... (1) A' ２ A ｎ－１ B ｎ Ch ３ｎ＋１ ...(2) (In formulas (1) and (2), A and A' are Mg, Ca, Sr, Ba, or a combination of these in any ratio; B is Ti, Zr, Hf, or a combination of these in any ratio; and Ch is S, Se, Te, or a combination of these in any ratio. In formula (2), n is an integer of 1 or more and 10 or less, and A and A' may be the same or different. The chalcogenide perovskite includes a solid solution in which part or all of A, A', B, and Ch in the composition represented by formula (1) or (2) are substituted with other elements.) 8. The thin film according to any one of claims 1 to 7, wherein the organic component comprises one or more selected from the group consisting of polymer materials and molecules having functional groups.

9. The thin film according to claim 8, wherein the polymer material is one or more selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polystyrene, and polycarbonate.

10. The thin film according to claim 8 or 9, wherein the molecule having a functional group is one or more selected from the group consisting of amine, carboxylic acid, thiol, and phosphine.

11. A device comprising a thin film according to any one of claims 1 to 10.

12. A method for producing a thin film according to any one of claims 1 to 10, comprising the steps of: applying a dispersion liquid containing the particles and the organic component; and removing the dispersion medium of the dispersion liquid by heating or drying, thereby forming the thin film.

13. The method of claim 12, wherein the heating is performed at a temperature below the boiling point of the organic component.

14. The method of claim 12, wherein the heating is performed at a temperature above the boiling point of the organic component.

15. The method of any one of claims 12 to 14, wherein the particles are synthesized by a liquid phase synthesis method.

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