Method for manufacturing photoelectric conversion element

Abstract

This invention provides a method for manufacturing a photoelectric conversion element with improved photoelectric conversion efficiency. This method for manufacturing a photoelectric conversion element having a first electrode, a photoelectric conversion layer including a crystal of a perovskite structure, a charge transport layer, and a second electrode includes a step for forming the charge transport layer by applying a charge transport layer coating liquid on a surface of the photoelectric conversion layer, the method being characterized in that the charge transport layer coating liquid includes an alcohol liquid, resin, and charge transport particles.

Description

Photoelectric conversion element manufacturing method

[0001] The present invention relates to a method for manufacturing a photoelectric conversion element.

[0002] In order to solve the problems of fossil energy depletion and the global environmental problems caused by the use of fossil energy, active research is being conducted on renewable and clean alternative energy sources such as solar energy, wind power, and hydropower. Among these, interest is growing in solar cells that directly convert sunlight into electrical energy. Here, a solar cell refers to a cell that generates current and voltage by absorbing light energy from sunlight and utilizing the photovoltaic effect, in which electrons and holes are generated.

[0003] Currently, n-p diode-type silicon (Si) single crystal-based solar cells with a light energy conversion efficiency of over 20% are widely known and are actually used for solar power generation. However, these require high-temperature processing steps and the materials themselves are expensive, resulting in high costs per unit of power. Furthermore, there are also supply issues due to the limited silicon resources.

[0004] On the other hand, solar cells using organic materials (hereinafter referred to as "organic solar cells") do not require high-temperature processing and can be produced using a sheet-like substrate in a so-called roll-to-roll method, which is expected to reduce costs. However, further improvements in power generation efficiency and durability are desired for the practical use of organic solar cells. In particular, perovskite solar cells, which have crystals with a perovskite structure as a photoelectric conversion layer, have excellent photoelectric conversion characteristics, and development is underway toward the practical use of solar cells.

[0005] For example, Patent Document 1 describes a technique for improving peeling from an electrode by including an organic semiconductor and a polymer compound having a glass transition temperature of 100°C or higher in the hole transport layer. Patent Document 2 describes a technique for improving photoelectric conversion efficiency by forming a layer containing a phthalocyanine compound between the hole transport layer and perovskite. Non-Patent Document 1 describes a technique for improving conversion efficiency by mixing copper phthalocyanine and a conductive polymer in the hole transport layer.

[0006] JP 2018-170382 A JP 2022-168820 A

[0007] Q. Hu, et al. Sol. RRL,2019,3,1800264

[0008] According to the investigations of the present inventors, it has been found that there is room for improvement in the photoelectric conversion efficiency of the photoelectric conversion elements described in Patent Document 1, Patent Document 2, and Non-Patent Document 1. Therefore, an object of the present invention is to provide a method for manufacturing a photoelectric conversion element that improves the photoelectric conversion efficiency.

[0009] The above object is achieved by the present invention, which provides a method for producing a photoelectric conversion element having a first electrode, a photoelectric conversion layer containing crystals of a perovskite structure, a charge transport layer, and a second electrode, the method comprising the step of forming a charge transport layer by applying a charge transport layer coating liquid onto the surface of the photoelectric conversion layer, the charge transport layer coating liquid containing an alcohol liquid, a resin, and charge transport particles.

[0010] According to the present invention, it is possible to provide a method for manufacturing a photoelectric conversion element with improved photoelectric conversion efficiency.

[0011] 1 is a schematic cross-sectional view in the thickness direction of a photoelectric conversion element manufactured by the method for manufacturing a photoelectric conversion element of the present invention; 2 is a perspective view schematically showing an example of a moving body equipped with a photoelectric conversion element manufactured by the method for manufacturing a photoelectric conversion element of the present invention; 3 is a perspective view schematically showing an example of a building material equipped with a photoelectric conversion element manufactured by the method for manufacturing a photoelectric conversion element of the present invention.

[0012] One embodiment relates to a method for manufacturing a photoelectric conversion element. The method for manufacturing a photoelectric conversion element of the present invention is a method for manufacturing a photoelectric conversion element having a first electrode, a photoelectric conversion layer containing crystals of a perovskite structure, a charge transport layer, and a second electrode, and includes a step of applying a charge transport layer coating liquid onto a surface of the photoelectric conversion layer to form a charge transport layer, and the charge transport layer coating liquid contains an alcohol liquid, a resin, and charge transport particles.

[0013] As a result of investigations, the present inventors have found that the above manufacturing method can produce a photoelectric conversion element with excellent photoelectric conversion efficiency. A photoelectric conversion element was produced by applying a coating liquid in which charge transport particles were dispersed in a non-alcoholic solvent onto the surface of a photoelectric conversion layer containing crystals with a perovskite structure. When the cross section of the photoelectric conversion element was observed under an electron microscope, voids were found between the photoelectric conversion layer and the layer of charge transport particles, and areas where the photoelectric conversion layer was not covered with charge transport particles were found.

[0014] In contrast, it has been found that in the case of a photoelectric conversion element formed by the manufacturing method of the present invention, voids and uncovered areas are reduced, and a layer containing charge transport particles that is denser and more closely adhered to the photoelectric conversion layer can be formed. This is thought to facilitate smooth transfer of charges from the photoelectric conversion layer to the electrode, improving the photoelectric conversion efficiency. The inventors of the present invention speculate as follows about the reason why the charge transport particles form a layer with good coverage that is dense and closely adhered to the photoelectric conversion layer.

[0015] The charge transport layer coating liquid of the present invention is a liquid containing an alcohol liquid, a resin, and charge transport particles. The charge transport particles are dispersed in the alcohol liquid. The charge transport layer is formed by coating the charge transport layer coating liquid on the surface of the photoelectric conversion layer, and then volatilizing the alcohol liquid to form a layer containing the charge transport particles and the resin.

[0016] As the alcohol liquid evaporates in the applied charge transport layer coating solution, the distance between the charge transport particles decreases. At this time, the presence of a resin between the charge transport particles stabilizes the particle dispersion state due to the steric barrier created by the resin, preventing excessive aggregation during the process of reducing the interparticle distance. This allows the alcohol liquid to be stably deposited on the photoelectric conversion layer, resulting in a layer with good coverage. Furthermore, because the alcohol liquid has a balanced combination of both hydrophilic portions due to hydroxyl groups and hydrophobic portions made of hydrocarbons, it stably intervenes between the charge transport particles, contributing to preventing excessive particle aggregation during the formation of the coating film. Furthermore, the perovskite-structured crystals of the photoelectric conversion layer have a hydrogen-bonding surface, which allows for good compatibility with the alcohol liquid through hydrogen-bonding interactions.

[0017] In the case of non-alcoholic liquids, the mixture is not very compatible, so the non-alcoholic particles tend to aggregate together, which results in particle aggregation and the creation of uncoated areas. Alcoholic liquids are compatible with both the perovskite structure crystals and the charge transport particles, so excessive particle aggregation does not occur during the coating film formation process as the alcohol liquid evaporates. As explained by the above mechanism, the synergistic effects of each component contribute to the formation of a dense, tightly adhered layer of charge transport particles on the photoelectric conversion layer, improving photoelectric conversion efficiency.

[0018] As explained above, the effects of the present invention can be achieved by the synergistic effects of the various components.

[0019] The present invention will be described in detail below with reference to preferred embodiments. The present invention is not limited to the following embodiments, and any modifications or improvements to the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention are also included in the scope of the present invention.

[0020] In this specification, the term "layer" refers not only to a layer with clear boundaries or a flat, thin-film layer, but also to a layer with a gradually changing concentration gradient of contained elements, or to a layer that can form a complex, intricate structure together with other layers. Elemental analysis of a layer can be performed, for example, by TOF-SIMS / FE-TEM / EDS line analysis of a cross section of a photoelectric conversion element to confirm the elemental distribution of a specific element. Analysis of each layer may be performed by peeling off the completed photoelectric conversion element to expose the layer to be analyzed. Furthermore, analysis of compounds in a charge transport layer coating solution can be performed by mass and structural analysis using elemental analysis such as 1H-NMR, GPC, MALDI-TOF-MS, IR, gas chromatography, liquid chromatography, XPS, and EDX.

[0021] The method for manufacturing a photoelectric conversion element of the present invention includes a first electrode, a photoelectric conversion layer containing crystals with a perovskite structure, a charge transport layer, and a second electrode. Figure 1 is a cross-sectional view schematically showing the configuration of a photoelectric conversion element manufactured by the method for manufacturing a photoelectric conversion element of the present invention. The element has a second electrode 3, an electron transport layer 4, a photoelectric conversion layer 5, a charge transport layer 6, and a first electrode 7 on a substrate 2. One of the first electrode 7 and the second electrode 3 is an anode and the other is a cathode, and current can be extracted by connecting the first electrode 7 and the second electrode 3 to an external circuit.

[0022] The photoelectric conversion layer 5 is excited by light incident through the substrate 2, the second electrode 3, and the electron transport layer 4, or through the first electrode 7 and the charge transport layer 6, and generates electrons or holes. That is, the photoelectric conversion layer 5 generates a current between the first electrode 7 and the second electrode 3. The electron transport layer 4 is a layer disposed between the photoelectric conversion layer 5 and the two electrodes (the second electrode 3 and the first electrode 7), and may not be formed in some cases. A configuration in which a plurality of electron transport layers 4 and photoelectric conversion layers 5 are stacked may be used. Such a configuration may also be called a tandem structure.

[0023] The photoelectric conversion element of the present invention is characterized by having a first electrode 7, a second electrode 3, a photoelectric conversion layer 5 containing a crystal with a perovskite structure disposed between the first electrode 7 and the second electrode 3, and a charge transport layer 6 between the photoelectric conversion layer 5 and the first electrode 7. In order to improve photoelectric conversion efficiency, the photoelectric conversion elements 1 may be stacked in a tandem configuration. The photoelectric conversion elements to be stacked are not limited to the type of photoelectric conversion element, and may include a perovskite solar cell using a crystal with a perovskite structure for the photoelectric conversion layer 5, a silicon solar cell, a CIGS solar cell, or the like.

[0024] Methods for forming each layer, including the photoelectric conversion layer and charge transport layer, of the photoelectric conversion element 1 include coating methods and vapor deposition methods. Examples of coating methods include dip coating, spin coating, spray coating, inkjet coating, meniscus coating, screen coating, roll coating, die coating, blade coating, curtain coating, and wire bar coating. The coating method involves preparing a coating solution for each layer, which will be described later, applying the solution in the desired layer order, and drying the solution. A desired method can be selected from these film formation methods depending on the layer. Each step will be described below.

[0025] [Step of forming charge transport layer] The method for manufacturing a photoelectric conversion element of the present invention includes a step of applying a charge transport layer coating liquid onto the surface of the photoelectric conversion layer 5 to form a charge transport layer 6, and the charge transport layer coating liquid includes an alcohol liquid, a resin, and charge transport particles.

[0026] The thickness of the charge transport layer 6 is preferably 1 nm or more and 1000 nm or less, more preferably 5 nm or more and 500 nm or less, and particularly preferably 10 nm or more and 200 nm or less.

[0027] In the method for producing a photoelectric conversion element of the present invention, the charge transport layer coating liquid contains an alcohol liquid, a resin, and charge transport particles (as a charge transport material). In the charge transport layer coating liquid of the present invention, the charge transport material (charge transport particles) is dispersed in the coating liquid and exists in a particulate form. By forming the charge transport layer in a particulate form, the charge transport layer can maintain high crystallinity and exhibit its inherent high charge transport ability.

[0028] The particle shape of the charge transport particles is preferably particles with a small aspect ratio, such as an approximately spherical shape, a rugby ball shape, a cylindrical shape, a flat shape, etc. For example, particles with a large aspect ratio, such as needle-shaped particles, must be deposited in the same direction to improve coverage.

[0029] That is, even if the charge-transport particles can be deposited on the photoelectric conversion layer in a stable dispersed state without excessive aggregation, their shape tends to leave portions of the photoelectric conversion layer that are not covered with the charge-transport particles.Furthermore, since the particles tend to pile up on other particles, voids tend to remain between the photoelectric conversion layer and the layer of charge-transport particles, thereby reducing the effect of the present invention.

[0030] The aspect ratio of the charge transporting particles is preferably 5 or less, and more preferably 3 or less. Examples of particle shapes that reduce the effect of the present invention include needle-like and fibrous shapes. The aspect ratio is greater than 10.

[0031] Specific examples of charge transporting particles include phthalocyanine pigments, azo pigments, lake pigments, quinacridone pigments, dioxazine pigments, perylene pigments, and isoindolinone pigments.

[0032] In the method for producing a photoelectric conversion element of the present invention, the charge transport particles are preferably particles containing a cyclic conjugated compound formed by conjugating multiple pyrrole rings. The cyclic conjugated compound formed by conjugating multiple pyrrole rings has a planar structure, and the particles are composed of an aggregate of crystallites in which these planar structures overlap. The crystallites have a highly polar surface containing a π-electron cloud and a nitrogen atom on the vertical surface of the planar structure, and a non-polar surface on the horizontal surface of the planar structure.

[0033] Therefore, particles formed by the accumulation of these crystallites have a polar surface and a non-polar surface. Since alcohol has both a hydrophilic portion and a hydrophobic portion, particles containing a cyclic conjugated compound in which multiple pyrrole rings are conjugated with alcohol are suitably dispersed, improving the coverage of the charge transport layer on the photoelectric conversion layer. Furthermore, particles containing a cyclic conjugated compound in which multiple pyrrole rings are conjugated with alcohol are preferred because they exhibit high charge transport ability.

[0034] In the method for producing a photoelectric conversion element of the present invention, the charge transport particles are preferably particles containing a phthalocyanine compound, and more preferably, the charge transport particles are particles having a structure represented by the following formula (Pc-2). By doing so, the charge transport particles are more likely to interact with alcohols and resins, and the coating properties are more likely to be improved. Furthermore, this is more preferable because it has good crystallinity and high charge transport properties.

[0035] In the formula (Pc-2), M is H. ２, a metal atom having a ligand, or a metal atom having no ligand. In the present invention, the structure of a chemical substance can be determined by nuclear magnetic resonance (NMR). In particular, when M in the above formula (Pc-2) is H ２ When this is the case, the above formula (Pc-2) is expressed by the following formula (Pc-1):

[0036] Specific examples of the resin include polyacetal resin, acrylic resin, polyarylate resin, polycarbonate resin, polyvinyl acetate resin, polyester resin, polyamide resin, polyurethane resin, and polystyrene resin.

[0037] In the method for producing a photoelectric conversion element of the present invention, the resin is preferably a resin having a Lewis basic functional group. The Lewis basic functional group acts electronically on the charge transport particles, thereby enhancing the interaction between the particles and the resin, making it easier for the resin to intervene between the particles, and making it easier to achieve the effect of steric barrier stabilization by the resin. If the particles are cyclic conjugated compounds formed by conjugating multiple pyrrole rings, electronic interaction with the Lewis basic functional group is easier, making it more effective.

[0038] Specific examples of the Lewis basic functional group include a hydroxy group, a halogen, a sulfo group, an amino group, a carbonyl group, an ester group, an ether group, a carboxyl group, an aldehyde group, a methoxy group, an amide group, a sulfide group, a cyano group, a thienyl group, a thienylidene group, a pyridyl group, a furyl group, a pyrazolyl group, an imidazolyl group, an oxazolyl group, a thiazolyl group, etc. Among these, a hydroxy group, a carbonyl group, an ether group, an ester group, a pyridyl group, and a thienylidene group are preferred from the viewpoint of electronic interaction.

[0039] In the method for producing a photoelectric conversion element of the present invention, the resin preferably has at least one functional group selected from the group consisting of a hydroxy group, a carbonyl group, an ether group, an ester group, a pyridyl group, and a thienylidene group. In the present invention, the functional group of the resin can be confirmed, for example, by nuclear magnetic resonance (NMR). The thienylidene group has a structure represented by the following formula (A):

[0040] In particular, it is more preferable to have at least two of these functional groups in terms of ease of interaction. Different functional groups may be contained in one resin, or two resins having different functional groups may be mixed. It is preferable that the Lewis basic functional group is contained in the repeating structure of the resin.

[0041] Specific examples of resins having a Lewis basic functional group that are preferably used in the present invention are listed below. Polyvinyl butyral, poly(4-vinylpyridine), poly(vinyl chloride), poly(vinylidene fluoride), polyacrylonitrile, poly(vinylidene fluoride-co-hexafluoropropylene), poly(acrylonitrile-co-butadiene), poly(styrene-co-acrylonitrile), polychloroprene, poly(4-chlorostyrene), polymethyl methacrylate, polyvinyl acetate, polyethyleneimine, polyvinyl alcohol, polyacrylic acid, poly(sodium 4-styrenesulfonate), poly(allylamine hydrochloride), sodium polyacrylate, poly(allylamine hydrochloride), poly(4-styrenesulfonic acid), poly(N-isopropylacrylamide), poly(2-ethyl-2-oxazoline), poly(ethylene-alt-maleic anhydride), poly(2-acrylamido-2-methyl-1-propanesulfonic acid), poly(vinyl sulfate) potassium salt, polyanethol sulfonic acid sodium salt, poly(2-dimethylamino)ethyl methacrylate) methyl chloride quaternary salt, poly(methyl vinyl ether), poly(2-propyl acrylic acid), polyvinylpyrrolidone, polypropylene glycol, poly(propylene carbonate), polyvinyl acetate, poly(tetrahydrofuran), nylon-6, poly(ethylene-co-vinyl acetate), poly(propylene glycol) bis(2-aminopropyl ether), poly(bisphenol A carbonate), poly(1,4-butylene adipate), poly(4-vinylphenol), poly(propylene glycol) monobutyl ether, poly Preferred are poly(glycidyl methacrylate), polybutyl acrylate, poly(ethylene succinate), poly(propylene glycol) methacrylate, nylon 11, nylon 12, poly(2-ethylhexyl acrylate), poly(bisphenol A carbonate), poly(propylene glycol) bis(2-aminopropyl ether), polyetherimide, poly(vinyl formal), poly(vinyl methyl ketone), poly(3-hexylthiophene-2,5-diyl), polyaniline, and a composite of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid (PEDOT:PSS).Among these, from the viewpoint of electronic interaction, polyvinyl butyral, polymethyl methacrylate, poly(3-hexylthiophene-2,5-diyl), polyvinyl acetate, polyvinyl alcohol, polyacrylic acid, poly(2-propylacrylic acid), polybutyl acrylate, and poly(4-vinylpyridine) are more preferred, and polyvinyl acetal resin and polyvinyl butyral resin are particularly preferred. In the method for producing a photoelectric conversion element of the present invention, the resin preferably contains a polyvinyl acetal resin, and more preferably contains a polyvinyl butyral resin. These resins are likely to interact with the charge-transporting particles.

[0042] In the method for producing a photoelectric conversion element of the present invention, the glass transition temperature of the resin is preferably 95° C. or lower. Within this range, the resin is easily in close contact with the charge transport particles, and the coating property is more effectively improved by interaction. In the present invention, the glass transition temperature can be determined by a differential scanning calorimeter (DSC).

[0043] The molecular weight of the resin is preferably in the range of 1,000 to 1,000,000 in terms of dispersibility and film-forming properties.

[0044] In the method for producing a photoelectric conversion element of the present invention, the mass of the charge transport particles in the charge transport layer coating liquid is preferably 5 to 20 times the mass of the resin in the charge transport layer coating liquid. This facilitates interaction between the resin and the charge transport particles, improving coverage. If the mass is more than 20 times, the improvement in coverage due to the resin interaction is likely to be insufficient. If the mass is less than 5 times, charge transfer from the photoelectric conversion layer to the particles becomes insufficient, making it difficult to improve the photoelectric conversion efficiency. In the present invention, the ratio of the mass of the charge transport particles to the mass of the resin can be confirmed, for example, by taking a small amount of the charge transport layer coating liquid, dissolving it in deuterated DMSO at a low concentration, and determining the peak ratio due to each structure by NMR measurement.

[0045] The charge transport layer coating liquid contains an alcohol liquid. The alcohol liquid functions as a dispersion medium for the charge transport particles in the coating liquid. In addition, the alcohol liquid has low surface tension, which allows the charge transport layer coating liquid to exhibit good wettability on the surface of the photoelectric conversion layer containing crystals of a perovskite structure.

[0046] In the method for producing a photoelectric conversion element of the present invention, the alcohol liquid preferably contains an aliphatic alcohol, and in particular, preferably contains an alcohol having 5 or less carbon atoms. This range provides a good balance between the hydrophobic and hydrophilic portions, which can contribute favorably to improved coverage. This is particularly preferred because it can favorably disperse particles containing a cyclic conjugated compound formed by conjugating multiple pyrrole rings, thereby improving coverage. In the present invention, chemical substances such as alcohol liquids can be identified, for example, by nuclear magnetic resonance (NMR).

[0047] The charge transport layer coating liquid may contain two or more types of alcohol liquids in combination. Furthermore, the charge transport layer coating liquid may contain a solvent other than the alcohol liquid. When a solvent other than the alcohol liquid is contained, it is preferable that the mass of the alcohol liquid is 40% or more of the mass of the total solvent in the charge transport layer coating liquid, since this makes it easier to achieve the above-mentioned effects.

[0048] In the method for producing a photoelectric conversion element of the present invention, the particle diameter of the charge transport particles in the charge transport layer coating liquid is 1.0×10 １ nm or more 5.0×10 ２ If the particle size is within the above range, the dispersion stability of the charge transport particles during application is more effectively improved, and the coating property is likely to be improved.

[0049] In the present invention, the particle size of the charge transport particles in the charge transport layer coating solution can be measured using a Zetasizer Nano-ZS (manufactured by MALVERN). This device can measure particle size by dynamic light scattering. First, the particles to be measured are diluted to a solid-liquid ratio of 0.10% by mass (±0.02% by mass), collected in a quartz cell, and placed in the measurement unit. The diluted solution is prepared to be the same as the solvent constituting the charge transport layer coating solution. The measurement conditions are entered using the control software Zetasizer software 6.30, and the refractive index and viscosity of the dispersion solvent at 20°C are input, and measurement is performed under conditions where the liquid is kept at 20°C to determine the Z-average particle size. In the case of a mixed solvent, the mass average value of the dispersion medium to be mixed is used.

[0050] The particle size of the charge transport particles can be changed by dispersing the charge transport layer coating solution using a paint shaker, and the particle size can be reduced by extending the dispersion time, or by centrifuging the charge transport layer coating solution.

[0051] The charge transport layer coating liquid preferably contains an aromatic ring compound having a hydroxyl group, which is different from the charge transport particles and the resin. The inclusion of the aromatic ring compound having a hydroxyl group more effectively improves the dispersion stability of the charge transport particles during coating, and thus the coating properties are likely to be improved.

[0052] The charge transport layer can be formed by preparing a charge transport layer coating solution containing the above-mentioned materials and solvent, forming this coating film on the photoelectric conversion layer, and drying it. Methods for forming the coating film include dip coating, spin coating, spray coating, inkjet coating, meniscus coating, screen coating, roll coating, die coating, blade coating, curtain coating, and wire bar coating.

[0053] The photoelectric conversion element of the present invention may have a second charge transport layer between the first electrode and the charge transport layer. The presence of the second charge transport layer may facilitate the transfer of carriers to the electrode.

[0054] [Substrate] The photoelectric conversion element 1 of the present invention may include a substrate 2, and examples thereof include a transparent glass substrate such as soda-lime glass or alkali-free glass, a ceramic substrate, a transparent plastic substrate, etc. When light is taken in from the first electrode 7 side, an opaque material can be used for the substrate 2, and when light is taken in from the second electrode 3 side, the substrate 2 is made of a transparent material.

[0055] [First Electrode and Second Electrode] The first electrode and the second electrode can be formed by, for example, vacuum deposition, sputtering, or other known methods, such as, but not limited to, sputtering, vacuum deposition, CVD (chemical vapor deposition), and SPD (spray pyrolysis deposition).

[0056] There are no particular limitations on the materials for the first electrode 7 and the second electrode 3, and conventionally known materials can be used. For example, metals such as gold, silver, titanium, and copper, sodium, sodium-potassium alloy, lithium, magnesium, carbon, carbon nanotubes, aluminum, magnesium-silver mixture, magnesium-indium mixture, aluminum-lithium alloy, and Al / Al ２ O ３ Examples of suitable materials include a mixture of Al and LiF, and an Al / LiF mixture.

[0057] Transparent electrode materials include, for example, CuI, ITO (indium tin oxide), and SnO ２ Examples of the conductive transparent material include AZO (aluminum zinc oxide), IZO (indium zinc oxide), GZO (gallium zinc oxide), FTO (fluorine-doped tin oxide), and ATO (antimony-doped tin oxide), as well as conductive transparent polymers. These materials may be used alone or in combination of two or more.

[0058] Of the first electrode 7 and the second electrode 3, at least one electrode on the light incident side is a transparent electrode, and the other may be a transparent electrode or may double as a reflective layer formed of a light-reflective material, or may be a transparent electrode with a reflective layer on the side opposite to the light incident side. When the first electrode 7 is on the light incident side, the second electrode 3 may be a transparent electrode and the substrate 2 may be a reflective layer. The electrode may be a patterned electrode. When either or both of the first electrode and the second electrode are transparent electrodes, the thickness of the transparent electrode is preferably 0.03 μm or more and 3 μm or less.

[0059] When manufacturing solar cells, cutting is generally performed between each process to form circuits. Examples of cutting include mechanical patterning and laser patterning.

[0060] <Modularization Process> The elements having electrodes formed thereon may be sealed. Examples of sealing methods include sealing with a resin or sealing with a film. Examples of materials used for sealing include silazane, silicone rubber, resins having a siloxane skeleton, and glass. Furthermore, from the viewpoint of suppressing adhesion between elements that occurs when winding in a roll-to-roll manner, the surfaces of the sealed elements may be subjected to a hairline treatment.

[0061] [Photoelectric Conversion Layer] The method for forming the photoelectric conversion layer includes a step of applying a liquid containing a material for the photoelectric conversion layer. Examples of the application method include spin coating, blade coating, slit die coating, screen printing, bar coating, casting, print transfer, immersion and lifting, ink jet printing, spraying, and vacuum deposition. Among these, an appropriate method is selected depending on the properties of the photoelectric conversion layer to be produced, such as thickness control and orientation control.

[0062] In order to remove the solvent or dispersion medium from the liquid containing the material of the applied photoelectric conversion layer, annealing may be performed under reduced pressure or in an inert atmosphere (nitrogen or argon atmosphere). The temperature of the annealing is preferably 40° C. or higher and 300° C. or lower, more preferably 50° C. or higher and 150° C. or lower. Note that annealing is preferable because it may increase the contact area at the interface between the stacked layers due to the penetration of the materials constituting each layer into each other, thereby increasing the short-circuit current.

[0063] The photoelectric conversion layer 5 has a crystal having a perovskite structure. The crystal having a perovskite structure used in the present invention is preferably represented by the following general formula [1]: ABX ３ [1] In the above general formula [1], A is a monovalent cation of an organic molecule or a metal atom, B is a divalent metal cation, and X is a monovalent halide anion.

[0064] As A in the general formula [1], for example, in the case of an organic molecule, C ｐ N ｑ H r(p, q, and r are all positive integers) Specific examples include methylammonium and formamidium.

[0065] The metal atom is not particularly limited, but lithium, cesium, sodium, potassium, and rubidium are preferred. These organic molecules or metal atoms may be used alone or in combination of two or more.

[0066] If the constituent cation A is too large to fit within a three-dimensional perovskite structure crystal, the resulting crystal may be a two-dimensional perovskite structure crystal, a 2.5-dimensional perovskite structure crystal having both two-dimensional and three-dimensional properties, a bilayer crystal of three-dimensional and two-dimensional perovskite structures, or a mixed three-dimensional / two-dimensional perovskite structure crystal, all of which function as a photoelectric conversion layer. A bilayer crystal of three-dimensional and two-dimensional perovskite structures refers to a crystal in which three-dimensional and two-dimensional perovskite structure crystals are stacked as independent, separate layers, while a mixed three-dimensional / two-dimensional perovskite structure crystal refers to a crystal in which regions or domains of both two-dimensional or 2.5-dimensional layered and three-dimensional perovskite structure crystals are mixed.

[0067] The crystal having a two-dimensional perovskite structure or the crystal having a 2.5-dimensional perovskite structure is preferably represented by the following general formulas [2] to [4]: ​​(n is a positive integer) R' ２ A ｎ－１ B ｎ X ３ｎ＋１ [2] R''A ｎ－１ B ｎ X ３ｎ＋１ [3] R'''A ｎ B ｎ X ３ｎ＋１ [4] In the above general formulas, [2] forms an RP (Ruddlesden-Popper) type perovskite structure, [3] forms a DJ (Dion-Jacobson) type perovskite structure, and [4] forms an ACI (Alternating cations in the interlayer) type perovskite structure.

[0068] As R', R'', and R''' in the above general formulas [2] to [4], for example, in the case of organic molecules, C ｐ Nｍ H ｎ (p, m, and n are all positive integers). A is an organic molecule or metal cation which may have a substituent, and specific examples thereof include ethylammonium, propylammonium, n-butylammonium, n-hexylammonium, n-octylammonium, 1,6-hexadiammonium, isobutylammonium, 3-(nonafluoro-tert-butyloxy)propylamine, 1,3-propanediammonium, 1,5-pentamethylenediamine, octyldiammonium, 2,2-(ethylenedioxy)bis(ethylammonium), 5-aminovaleric acid, 4-tert-butylammonium, N,N'-dimethylethylene-1,2-diammonium, 2,2,3,3,3-pentafluoropropylammonium, guanidium, propylammonium, propargylamine, alkylammonium, cyclohexylmethylammonium, 4-(aminomethyl)piperidinium, piperidinium, pyrrolidinium, cyclohexylammonium, 4- Fluorophenethylammonium, 4-fluorophenethylammonium, trifluoromethylbenzylammonium, pentafluorobenzylammonium, pentafluorophenylethylammonium, 4-methoxyphenethylammonium, imidazolium, pyridinium, 3-thiophenemethylammonium, 2-thiopheneethylammonium, 2-thiopheneformamidium, 2-thiophenemethylammonium, 1-naphthylmethylammonium, 2-naphthylmethylammonium, phenethylammonium, phenylammonium, benzylammonium, 2,5-thiophenedimethylammonium, phenylpropylammonium, 1,4-phenylenedimethanamine, 3-phenyl-2-propene-1-ammonium, phenylbutylammonium, 4-tert-butyl - benzylammonium, 3- (aminomethyl) piperidinium, 4- (aminomethyl) piperidinium is preferred.

[0069] In the above general formulas [1] to [4], B is a metal atom, such as lead, tin, bismuth, zinc, titanium, antimony, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, and europium. Among these, lead, tin, and bismuth are preferred from the viewpoint of electron orbital overlap. These metal atoms may be used alone or in combination of two or more.

[0070] X in the above general formulas [1] to [4] is a halogen atom, such as chlorine, bromine, or iodine. These halogen atoms may be used alone or in combination of two or more. Among these, halogen atoms are preferred because the inclusion of halogen in the structure makes the perovskite structure crystal more soluble in organic solvents, enabling application to inexpensive printing methods, etc. Furthermore, iodine is more preferred because it narrows the energy band gap of the perovskite structure crystal.

[0071] Specifically, the three-dimensional perovskite structure crystal, the two-dimensional perovskite structure crystal, and the mixed three-dimensional / two-dimensional perovskite structure crystal are MAPbI ３ and FAPbCl ３ , FAPbI ３ , MAPbI ｘ Br ３－ｘ , MAPbI ｘ Cl ３－ｘ , Cs ０．０５ (MA ０．１７ FA ０．８３ ) ０．９５ Pb(I ０．８３ Br ０．１７ ) ３ , {Cs ｘ１ (FA ｘ２ MA １－ｘ２ ) １－ｘ１} ｘ３ Pb(I ｘ４ Br １－ｘ４ ) ｘ５ , Cs ０．０５ FA ０．８８ MA ０．０７ PbI ２．５６ Br ０．４４ , (FAPbI ３ )０．９５ (MAPbBr ３ ) ０．０５ 、(FAPbI ３ ) ０．８５ (MAPbBr ３ ) ０．１５ 、CsPbI ３ 、CsPbBr ３ 、Cs ｘ (MA) １－ｘ PbI ３ 、Csx(FA) １－ｘ PbI ３ 、MA ｘ (FA) １－ｘ PbI ３ 、MA ０．１７ FA ０．８３ Pb(I ０．８３ Br ０．１７ ) ３ 、Cs ０．１５ FA ０．８５ PbI ２．５５ Br ０．４５ 、Cs ０．０５ FA ０．８８ MA ０．０７ PbI ２．５６ Br ０．４４ 、Cs ０．１５ FA ０．８５ PbI ２．５５ Br ０．４５ 、(PEA) ２ (MA) ２ Pb ３ I １０ 、(PTA) ２ (MA) ４ Pb ５ I １６ 、(PEA) ２ (MA) ４ Pb ５ I １６ 、(ThMA) ２ (MA) ２ Pb ３ I １０ 、(3BBA) ２ (MA) ２ Pb ３ I １０ 、(ThMA) ２ (FA) ４ Pb ５ I １６ 、(4FPEA) ２ (FA ０．３ MA０．７ ) ４ Pb ５ I １６ 、(PDMA)FA ２ Pb ３ I １０ 、(3AMPY)(MA) ３ Pb ４ I １３ 、(PDMA)MA ５ Pb ６ I １９ 、(PDMA)MA ３ Pb ４ I １３ 、(TTDMA)MA ３ Pb ４ I １３ 、(TTDMA)MA ４ Pb ５ I １６ 、(BA ０．９ PEA ０．１ ) ２ MA ４ Pb ５ I １６ 、(BA ０．９ PEA ０．１ ) ２ MA ３ Pb ４ I １３ 、(4FPEA) ２ MA ３ Pb ４ I １３ 、(4FPEA) ２ MA ４ Pb ５ I １６ 、(BA) ２ MA ２ Pb ３ I １０ 、(BA) ２ MA ３ Pb ４ I １３ 、(TEA) ２ MA ２ Pb ３ I １０ 、(BA) ２ MA ４ Pb ５ I １６ 、(BA) ２ MA ３ Pb ４ I １３ 、CsSnBr３ , CsSnI ３ , F.A. ０．７５ MA ０．２５ Sn ０．９５ Ge ０．０５ I ３ , FAMASnGeI ３ , FASnBr ３ , FASnI ３ , M.A. ２ Sn ３ I ８ , MASnBr ３ , MASnGeI ３ , MASnI ３ is preferred. Depending on the purpose, the A site, B site, or X site in the above general formula may be adjusted to be insufficient or excessive, and the combinations of x1 to x5 may be changed depending on the purpose. Combinations of x1 to x5 are shown in Table 1, for example. Particularly preferred ranges are 0.03≦x1≦0.10, 0.80≦x2≦0.96, 0.95≦x3≦1.05, 0.80≦x4≦0.96, and 2.95≦x5≦3.05. MACl may also be included as a material for forming a crystal with a perovskite structure.

[0072]

[0073] In the above specific examples, "MA" represents methylammonium, "FA" represents formamidinium, "PEA" represents phenethylammonium, "PTA" represents phenyltriethylammonium, "ThMA" represents 2-thiophenemethylammonium, "3BBA" represents 3-bromobenzylammonium, "3AMPY" represents 3-(aminomethyl)pyridine, "PDMA" represents 1,4-phenylenedimethaneammonium, "TTDMA" represents thieno[3,2-b]thiophene-2.5-diyldimethaneammonium, "4FPEA" represents 4-fluorophenethylammonium, "BA" represents butylammonium, and "TEA" represents 2-thiophenethylammonium.

[0074] The perovskite crystal preferably has a cubic structure in which a metal atom B is located at the body center, an organic molecule A at each vertex, and a halogen atom X at the face center. Although the details are not clear, it is presumed that such a structure allows the orientation of the octahedra in the crystal lattice to be easily changed, thereby increasing the mobility of electrons in the perovskite crystal and improving the photoelectric conversion efficiency of the photoelectric conversion element.

[0075] The organic-inorganic perovskite compound used in the present invention is preferably a crystalline semiconductor. A crystalline semiconductor refers to a semiconductor from which a scattering peak can be detected by measuring an X-ray scattering intensity distribution. When the organic-inorganic perovskite compound is a crystalline semiconductor, the mobility of electrons in the organic-inorganic perovskite compound increases, improving the photoelectric conversion efficiency of the photoelectric conversion element. Furthermore, the photoelectric conversion layer according to the present invention may contain a material other than the crystal of the organic-inorganic perovskite structure, as long as the material does not impair the photoelectric conversion efficiency or charge transport properties.

[0076] The thickness of the photoelectric conversion layer according to the present invention is preferably 5 nm or more and 2000 nm or less. A thickness of 5 nm or more allows sufficient absorption of light, and a thickness of 2000 nm or less allows generated charges to be transported to each electrode. A more preferred lower limit is 50 nm or more, a more preferred upper limit is 1200 nm, an even more preferred lower limit is 100 nm, and an even more preferred upper limit is 1000 nm.

[0077] [Second Charge Transport Layer] In the present invention, from the viewpoint of film compatibility of the charge transport layer 6, a step of forming a second charge transport layer on the surface of the charge transport layer 6 (between the charge transport layer 6 and the first electrode 7) may be further included. The method for forming the second charge transport layer is as described above.

[0078] The material for the second charge transport layer is not particularly limited, and examples thereof include spirofluorene compounds, triphenylamine compounds, chrysene compounds, pyrene compounds, phthalocyanine compounds, carbazole compounds, fluorene compounds, phenylcyclohexane compounds, benzidine compounds, phenoxazine compounds, phenylenediamine compounds, thiocyanate compounds, and thiophene compounds. In particular, from the viewpoint of compatibility at the film interface, compounds having an aromatic ring are preferred, and Spiro-OMeTAD, PTAA, and phthalocyanine compounds are preferred.

[0079] The second charge transport layer may contain a dopant as an additive to improve its charge transport capability. Examples of a substance that can be used as a dopant include lithium compounds such as bis(trifluoromethanesulfonyl)imide lithium, cobalt compounds such as [tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(3)tris(bis(trifluoromethylsulfonyl)imide)], boron compounds such as tetrakis(pentafluorophenyl)borate, molybdenum compounds such as tris[1-(methoxycarbonyl)-2-(trifluoromethyl)-ethane-1,2-dithiolene]molybdenum, organic compounds having a tetracyanoquinodimethane skeleton such as 2,3,4,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, and organic compounds having a pyridine skeleton such as 4-tert-butylpyridine.

[0080] [Electron Transport Layer] In the photoelectric conversion element of the present invention, as shown in FIG. 1, an electron transport layer 4 may be disposed between the second electrode 3 and the photoelectric conversion layer 5 .

[0081] The material for the electron transport layer 4 is not particularly limited, and examples thereof include N-type conductive polymers, N-type low-molecular-weight organic semiconductors, N-type metal oxides, N-type metal sulfides, alkali metal halides, alkali metals, surfactants, etc. Specific examples thereof include cyano group-containing polyphenylene vinylene, boron-containing polymers, bathocuproine, bathophenanthrene, hydroxyquinolinatoaluminum, oxadiazole compounds, benzimidazole compounds, naphthalene tetracarboxylic acid compounds, fullerene compounds, perylene derivatives, phosphine oxide compounds, phosphine sulfide compounds, fluoro group-containing phthalocyanines, titanium oxide, zinc oxide, indium oxide, tin oxide, gallium oxide, tin sulfide, indium sulfide, zinc sulfide, etc. In particular, tin oxide may be obtained by reacting tin(2) chloride, tin(4) chloride, tin(2) chloride dihydrate, or tin(4) chloride pentahydrate.

[0082] The thickness of the electron transport layer 4 is preferably 1 nm at its lower limit and 2000 nm at its upper limit. A thickness of 1 nm or more sufficiently blocks holes, while a thickness of 2000 nm or less prevents electron transport and increases photoelectric conversion efficiency. A more preferred lower limit is 3 nm, a more preferred upper limit is 1000 nm, an even more preferred lower limit is 5 nm, and an even more preferred upper limit is 500 nm.

[0083] <Photoelectric Conversion Element and Its Application Examples> Photoelectric conversion elements manufactured by the method for manufacturing a photoelectric conversion element of the present invention and their application examples will be described below.

[0084] [Photoelectric conversion element] The photoelectric conversion element of the present invention is manufactured by the above-described method for manufacturing a photoelectric conversion element. The photoelectric conversion element 1 has a second electrode 3, an electron transport layer 4, a photoelectric conversion layer 5, a charge transport layer 6, and a first electrode 7 on a substrate 2. One of the first electrode 7 and the second electrode 3 is an anode and the other is a cathode, and current can be extracted by connecting the first electrode 7 and the second electrode 3 to an external circuit.

[0085] The photoelectric conversion layer 5 is excited by light incident through the substrate 2, the second electrode 3, and the electron transport layer 4, or through the first electrode 7 and the charge transport layer 6, and generates electrons or holes. That is, the photoelectric conversion layer 5 generates a current between the first electrode 7 and the second electrode 3. The electron transport layer 4 is a layer disposed between the photoelectric conversion layer 5 and the two electrodes (the second electrode 3 and the first electrode 7), and may not be formed in some cases. A configuration in which a plurality of electron transport layers 4 and photoelectric conversion layers 5 are stacked may be used. Such a configuration may also be called a tandem structure.

[0086] The photoelectric conversion element of the present invention is characterized by having a first electrode 7, a second electrode 3, a photoelectric conversion layer 5 containing a crystal with a perovskite structure disposed between the first electrode 7 and the second electrode 3, and a charge transport layer 6 between the photoelectric conversion layer 5 and the first electrode 7. In order to improve photoelectric conversion efficiency, the photoelectric conversion elements 1 may be stacked in a tandem configuration. The photoelectric conversion elements to be stacked are not limited to the type of photoelectric conversion element, and may include a perovskite solar cell using a crystal with a perovskite structure for the photoelectric conversion layer 5, a silicon solar cell, a CIGS solar cell, or the like.

[0087] In the photoelectric conversion element of the present invention, a charge transport layer 6 is preferably disposed between the photoelectric conversion layer 5 and the first electrode 7, the charge transport layer 6 containing charge transport particles and a resin, and disposed on the surface of the photoelectric conversion layer 5. The film thickness of the charge transport layer 6 is preferably 1 nm or more and 1000 nm or less, more preferably 5 nm or more and 500 nm or less, and particularly preferably 10 nm or more and 200 nm or less.

[0088] The thickness of the photoelectric conversion layer is preferably 5 nm or more and 2000 nm or less. If the thickness is 5 nm or more, light can be sufficiently absorbed, and if the thickness is 2000 nm or less, the generated charges can be transported to each electrode. The lower limit is more preferably 50 nm or more, the upper limit is more preferably 1200 nm, the lower limit is even more preferably 100 nm, and the upper limit is even more preferably 1000 nm.

[0089] In the present invention, the presence of each layer can be confirmed, for example, by X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR), or energy dispersive X-ray spectroscopy (EDS) using an electron gun of a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The shape and aspect ratio of the charge transport particles can also be confirmed by a scanning electron microscope (SEM) or a transmission electron microscope (TEM). In the present invention, the film thickness of each layer can be confirmed, for example, by observing a cross section of a photoelectric conversion element with a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

[0090] [Photoelectric conversion device] The photoelectric conversion device of the present invention has the above-described photoelectric conversion element. A photoelectric conversion device can be configured by using a plurality of photoelectric conversion elements of the present invention. When a plurality of photoelectric conversion elements are connected, the photoelectric conversion device can also be called a photoelectric conversion cell or a photoelectric conversion module.

[0091] The photoelectric conversion element may be a stack of photoelectric conversion elements with different absorption wavelengths to increase the output voltage. Furthermore, the photoelectric conversion device includes the photoelectric conversion element of the present invention and an inverter. The inverter may be a converter that converts direct current to alternating current. The photoelectric conversion device may include a storage unit connected to the photoelectric conversion element. The storage unit is not limited as long as it can store electricity. Examples of the storage unit include secondary batteries using lithium ions, all-solid-state batteries, and electric double layer capacitors. To provide a function such as maintaining or increasing the amount of incident light, a surface layer that is resistant to water and dirt, or a function to collect or guide light may be added.

[0092] [Mobile object] The mobile object of the present invention has the above-described photoelectric conversion element. Fig. 2 is a perspective view showing a schematic diagram of one embodiment of a mobile object equipped with the photoelectric conversion element of the present invention. Mobile object 30 has photoelectric conversion element 31 of the present invention and body 32 equipped with this photoelectric conversion element 31.

[0093] The photoelectric conversion element 31 is disposed in a position on the body 32 where it can receive external light. If the mobile body 30 is an automobile, it may be disposed on the roof. The electrical energy obtained by the photoelectric conversion element 31 may power the mobile body 30 or may power other electrical equipment. Electrical energy generated from the power of the mobile body 30 may be used to power the photoelectric conversion element 31. If the mobile body 30 is an automobile, frictional energy generated by braking may be converted into electrical energy and used to control the photoelectric conversion element 31.

[0094] The mobile object 30 may be, for example, an automobile, a motorcycle, a railroad vehicle, a ship, an artificial satellite, an airplane, or a flying object including a drone. The configuration of the body 32 of the mobile object 30 is not particularly limited, but it is preferably made of a high-strength material.

[0095] [Building Material] The building material of the present invention has the photoelectric conversion element described above. Fig. 3 is a perspective view schematically showing one embodiment of a building material including the photoelectric conversion element of the present invention. The building material 40 may be the roof of a building. The building material 40 of this embodiment has the photoelectric conversion element 41 of the present invention, a protective member 42 that protects the photoelectric conversion element 41, a heat dissipation member 43, and exterior coverings 44a and 44b.

[0096] The building material 40 of the present invention may have a heat dissipation member 43 having a higher thermal conductivity than the photoelectric conversion element 41. When used on a roof or the like, sunlight may increase the temperature of the photoelectric conversion element 41, potentially reducing the photoelectric conversion efficiency. The use of the heat dissipation member 43 can reduce the reduction in photoelectric conversion efficiency. Examples of the heat dissipation member 43 include a metal, an alloy, a liquid metal, and a liquid resin.

[0097] The building material 40 of the present invention may also have exterior coatings 44a and 44b. The exterior coatings 44a and 44b may emit different colors or may be the same. 44a and 44b may be made of the same material or different materials. Paint or a transparent substrate may be used as the exterior coating. A material with low light absorption and high heat insulation properties is preferred.

[0098] In addition to the above application examples, other examples include the following: Portable devices such as calculators, sensors, and small solar panels. Wearable devices such as eyeglass-type terminals, wristwatch-type terminals, and portable medical equipment. Sheet structures supported by multiple frames such as tents, greenhouses, and truck beds. Fixed structures such as road panels, floating panels, building materials that take advantage of the flexibility of the substrate, wall-type building materials, glass-type building materials, and mega solar panels.

[0099] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited to the following examples without departing from the gist of the present invention. In the following description of the examples, "parts" are by mass unless otherwise specified.

[0100] <Preparation of Particles 1> Step (1) Under a nitrogen flow atmosphere, 5.46 parts of orthophthalonitrile and 45 parts of α-chloronaphthalene were charged into a reaction vessel, and the vessel was heated to a temperature of 30°C and maintained at this temperature. Next, 3.75 parts of gallium trichloride was charged at this temperature (30°C). The water concentration of the mixed solution at the time of charging was 150 ppm. Then, the temperature was raised to 200°C.

[0101] Next, the mixture was reacted at 200°C for 4.5 hours under a nitrogen flow atmosphere, and then cooled. When the temperature reached 150°C, the product was filtered. The resulting filtrate was dispersed and washed using N,N-dimethylformamide at 140°C for 2 hours, and then filtered. The resulting filtrate was washed with methanol and dried to obtain chlorogallium phthalocyanine particles in a yield of 71% by mass.

[0102] Step (2): 4.65 parts of the chlorogallium phthalocyanine particles were dissolved in 139.5 parts of concentrated sulfuric acid at 10°C, and the solution was added dropwise to 620 parts of ice water with stirring to reprecipitate the solution, which was then filtered under reduced pressure using a filter press. A No. 5C filter (manufactured by Advantec Co., Ltd.) was used. The resulting wet cake (filtered product) was dispersed and washed with 2% aqueous ammonia for 30 minutes, and then filtered using a filter press.

[0103] The resulting wet cake (filtrate) was then dispersed and washed with ion-exchanged water, and then filtered three times using a filter press. Finally, freeze-drying was performed to obtain hydroxygallium phthalocyanine particles (hydrated hydroxygallium phthalocyanine particles) with a solids content of 23% by mass in a yield of 71% by mass. The hydroxygallium phthalocyanine particles were dried in a Hyper Dry dryer (trade name: HD-06R, frequency (oscillation frequency): 2455 MHz±15 MHz, manufactured by Nippon Biocon) to obtain hydroxygallium phthalocyanine (OHGaPc) particles (crystals) with a moisture content of 1.0% by mass or less.

[0104] Step (3): Five parts of the hydroxygallium phthalocyanine particles were mixed with five parts of N-methylformamide solvent, and the mixture was dispersed for six hours using a sand mill (TSG-1 / 4G-4U, manufactured by Igarashi Machine Manufacturing Co., Ltd. (now Imex Co., Ltd.), disk diameter 70 mm, number of disks 5) containing five parts of glass beads, followed by filtration and drying to obtain particles 1 (specific gravity 1.6). The aspect ratio was 3 or less.

[0105] <Preparation of Resin Solution 1> 1.0 g of polyvinyl acetal resin (product name: S-LEC (registered trademark) BM-2, manufactured by Sekisui Chemical Co., Ltd., glass transition temperature 71°C) was dissolved in 19 g of 2-propanol as a solvent with stirring for 24 hours to obtain Resin Solution 1.

[0106] <Preparation of Resin Solution 2> 1.0 g of polyvinyl acetal resin (product name: S-LEC (registered trademark) BX-1, manufactured by Sekisui Chemical Co., Ltd., glass transition temperature 95°C) was dissolved in 19 g of ethanol as a solvent with stirring for 24 hours to obtain Resin Solution 2.

[0107] <Preparation of Resin Solution 3> 1.0 g of polyvinyl acetal resin (product name: S-LEC (registered trademark) BL-S, manufactured by Sekisui Chemical Co., Ltd., glass transition temperature 66°C) was dissolved in 19 g of 2-propanol as a solvent with stirring for 24 hours to obtain Resin Solution 3.

[0108] <Preparation of Resin Solution 4> Resin solution 4 was obtained by dissolving 1.0 g of polymethyl methacrylate (PMMA, manufactured by Sigma-Aldrich, glass transition temperature 70° C.) in 19 g of chlorobenzene as a solvent with stirring for 24 hours.

[0109] <Preparation of Resin Solution 5> Resin solution 5 was obtained by dissolving 1.0 g of polymethyl methacrylate (PMMA, manufactured by Sigma-Aldrich, glass transition temperature 100° C.) in 19 g of chlorobenzene as a solvent with stirring for 24 hours.

[0110] <Preparation of Resin Solution 6> Resin solution 6 was obtained by dissolving 1.0 g of poly(3-hexylthiophene-2,5-diyl) (P3HT, glass transition temperature 130° C.) in 19 g of chlorobenzene as a solvent with stirring for 24 hours.

[0111] <Preparation of Resin Solution 7> Resin solution 7 was obtained by dissolving 1.0 g of poly(4-vinylpyridine) (glass transition temperature: 137° C.) in 19 g of 2-propanol as a solvent with stirring for 24 hours.

[0112] <Preparation of Resin Solution 8> Resin solution 8 was obtained by dissolving 1.0 g of poly[9,9-bis-(2-ethylhexyl)-9H-fluorene-2,7-diyl] (glass transition temperature 45° C.) in 19 g of chlorobenzene as a solvent with stirring for 24 hours.

[0113] <Preparation of Resin Solution 9> Resin solution 9 was obtained by dissolving 1.0 g of poly(3-hexylthiophene-2,5-diyl) (P3HT, glass transition temperature 130° C.) in 19 g of dichlorobenzene as a solvent with stirring for 24 hours.

[0114] <Preparation of Resin Solution 10> 1.0 g of polyvinyl acetal resin (product name: S-LEC (registered trademark) BL-S, manufactured by Sekisui Chemical Co., Ltd., glass transition temperature 66°C) was dissolved in 19 g of acetone as a solvent with stirring for 24 hours to obtain resin solution 10.

[0115] Example 1 Formation of Electron Transport Layer A glass substrate with ITO was cleaned, and a 5-fold diluted tin oxide (2) colloidal solution (15% aqueous dispersion, manufactured by Alfa Aesar) was applied thereon by spin coating, followed by heating at 150°C for 30 minutes to form a thin-film electron transport layer with a thickness of 16 nm.

[0116] [Formation of Photoelectric Conversion Layer] 1.1 g of lead iodide and 0.39 g of methylammonium iodide were dissolved in 0.36 g of N,N-dimethylformamide and 1.45 g of dimethyl sulfoxide to prepare a photoelectric conversion layer coating solution. This coating solution was spin-coated on the electron transport layer to form MAPbI ３ A photoelectric conversion layer having a thickness of 500 nm was formed.

[0117] [Formation of Charge Transport Layer] 0.1 g of the particles 1 and 0.01 g of a calixarene compound (JP 2003-207913 A) were mixed with 10.6 g of 2-propanol as a solvent. 11 g of beads (zirconia beads, Treceram (registered trademark) zirconia beads, 0.3 mm) were encapsulated in this mixture, and the mixture was dispersed in a paint shaker (manufactured by Toyo Seiki Seisaku-sho) for 3 hours. Then, 0.2 g of resin solution 1 was added, and the mixture was dispersed again in a paint shaker for 4 hours to prepare a charge transport layer coating liquid. This charge transport layer coating liquid was spin-coated on the photoelectric conversion layer to form a charge transport layer with a thickness of 180 nm.

[0118] [Introduction of Second Charge Transport Layer] 0.15 g of Spiro-OMeTAD, a material for the second charge transport layer, was dissolved in 2.2 g of chlorobenzene. To this chlorobenzene solution, 36 μL of an acetonitrile solution obtained by dissolving 0.2 g of lithium bis(trifluoromethanesulfonyl)imide in 0.3 g of acetonitrile was added, and 60 μL of 4-tert-butylpyridine (TBP) were mixed. This solution was further mixed with 58 μL of an acetonitrile solution obtained by dissolving 0.11 g of [tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(3)tris(bis(trifluoromethylsulfonyl)imide)] in 0.3 g of acetonitrile to prepare a material solution for the second charge transport layer. This solution was applied to the charge transport layer by spin coating to form a second charge transport layer with a thickness of 150 nm.

[0119] [Formation of First Electrode] A first electrode having a thickness of 80 nm and an area of ​​0.36 cm was formed on the second charge transport layer. ２ A gold electrode was formed by vacuum deposition to obtain a photoelectric conversion element.

[0120] [Analysis of Compound Amount] The electrode surface of the photoelectric conversion element was peeled off to expose the charge transport layer surface. This charge transport layer surface was wiped with a cotton swab or the like soaked in a solvent, dissolved in heavy water sulfuric acid, and subjected to 1H-NMR measurement (apparatus: AVANCE3-500, manufactured by BRUKER). The peeled charge transport layer components were subjected to mass and structural analysis using elemental analysis such as GPC, MALDI-TOF-MS, IR, gas chromatography, XPS, and EDX to confirm the presence of the compound. The film thickness was also confirmed by cutting the photoelectric conversion element, fixing it to an inclined sample stage, and then using a cross-sectional SEM (apparatus: SmartSEM, manufactured by Carl Zeiss K.K.).

[0121] [Analysis of Particle Size of Charge Transporting Particles] The particle size of the charge transporting particles in the charge transport layer coating liquid was determined by measuring the Z-average particle size using the above-mentioned Zetasizer Nano-ZS (manufactured by MALVERN).

[0122] Example 2 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating liquid, the amount of resin solution 1 added is changed to 0.25 g.

[0123] Example 3 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating liquid, the amount of resin solution 1 added is changed to 0.40 g.

[0124] Example 4 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating liquid, the amount of resin solution 1 added is changed to 0.10 g.

[0125] Example 5 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating liquid, the amount of resin solution 1 added is changed to 0.50 g.

[0126] Example 6 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating liquid, the amount of resin solution 1 added is changed to 0.08 g.

[0127] (Example 7) In preparing the charge transport layer coating liquid, the time for dispersion in the paint shaker before adding resin solution 1 was changed to 6 hours, and the obtained dispersion was centrifuged (15,000 rpm, 2 minutes) to reduce the particle size in the dispersion. Thereafter, resin solution 1 was added so that the mass ratio of the charge transport particles to the resin was 10 times, and the dispersion was again carried out in the paint shaker for 4 hours. A photoelectric conversion element was obtained in the same manner as in Example 1, except for this.

[0128] (Example 8) A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating liquid, the time for dispersion in the paint shaker before adding resin solution 1 is changed to 1 hour, and the time for dispersion in the paint shaker after adding resin solution 1 is changed to 1 hour.

[0129] Example 9 A photoelectric conversion element was obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating solution, 10.6 g of 2-propanol was changed to 10.6 g of ethanol and resin solution 1 was changed to resin solution 2.

[0130] Example 10 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating liquid, particles 1 are changed to copper phthalocyanine particles.

[0131] Example 11 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating liquid, particles 1 are changed to tetraphenylporphyrin (TPP) particles.

[0132] Example 12 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating liquid, particles 1 are changed to quinacridone particles.

[0133] Example 13 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating liquid, particles 1 are changed to particles having a compound represented by the following formula (Pc-3).

[0134] Example 14 A photoelectric conversion element is obtained in the same manner as in Example 1, except that resin solution 1 is changed to resin solution 4 in the preparation of the charge transport layer coating liquid.

[0135] Example 15 A photoelectric conversion element is obtained in the same manner as in Example 1, except that resin solution 1 is changed to resin solution 5 in the preparation of the charge transport layer coating liquid.

[0136] Example 16 A photoelectric conversion element is obtained in the same manner as in Example 1, except that resin solution 1 is changed to resin solution 3 in the preparation of the charge transport layer coating liquid.

[0137] Example 17 A photoelectric conversion element is obtained in the same manner as in Example 1, except that resin solution 1 is changed to resin solution 6 in the preparation of the charge transport layer coating liquid.

[0138] Example 18 A photoelectric conversion element is obtained in the same manner as in Example 1, except that resin solution 1 is changed to resin solution 7 in the preparation of the charge transport layer coating liquid.

[0139] Example 19 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating solution, the amount of resin solution 1 added is 0.25 g and the second charge transport layer is not provided.

[0140] Example 20 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in preparing the charge transport layer coating solution, the solvent is changed to 4.2 g of 2-propanol and 6.4 g of chlorobenzene.

[0141] Example 21 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating solution, 10.6 g of 2-propanol is changed to 10.6 g of methanol.

[0142] Example 22 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating solution, 10.6 g of 2-propanol is changed to 10.6 g of 1-butanol.

[0143] Example 23 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating solution, 10.6 g of 2-propanol is changed to 10.6 g of 1-pentanol.

[0144] Example 24 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating solution, 10.6 g of 2-propanol is changed to 10.6 g of benzyl alcohol.

[0145] Example 25 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating liquid, resin solution 1 is changed to resin solution 8 and the amount added is changed to 0.14 g.

[0146] Example 26 A photoelectric conversion element was obtained in the same manner as in Example 1, except that the photoelectric conversion layer coating solution was changed as follows to form a photoelectric conversion layer. 0.487 g of methylammonium bromide, 1.034 g of formamidium iodide, 2.903 g of lead iodide, and 0.139 g of methylammonium bromide were dissolved in 4.25 g of N,N-dimethylformamide and 1.216 g of dimethyl sulfoxide, and the mixture was stirred for 1 hour (Solution 1). Furthermore, 0.100 g of cesium iodide was dissolved in 0.285 g of dimethyl sulfoxide, and the mixture was stirred for 1 hour (Solution 2). The dissolved cesium iodide solution (Solution 2) was then added to Solution 1 to prepare a photoelectric conversion layer coating solution. This coating solution was spin-coated onto the electron transport layer, resulting in the formation of Cs ０．０５ (FA ０．８３ MA ０．１７ ) ０．９５ Pb(I ０．８３ Br ０．１７ ) ３ A photoelectric conversion layer having a thickness of 600 nm is formed.

[0147] Comparative Example 1 A photoelectric conversion element was obtained in the same manner as in Example 1, except that resin solution 1 was not used in preparing the charge transport layer coating liquid.

[0148] Comparative Example 2 A photoelectric conversion element was obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating solution, particles 1 were replaced with particles having a compound represented by the following formula (Pc-4), 10.6 g of 2-propanol was replaced with 10.6 g of dichlorobenzene, resin solution 1 was replaced with resin solution 9, and the solvent was changed to only dichlorobenzene.

[0149] Comparative Example 3 A photoelectric conversion element was obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating solution, 10.6 g of 2-propanol was changed to 10.6 g of acetone, Resin solution 1 was changed to Resin solution 10, and the solvent was changed to acetone only.

[0150] Comparative Example 4 A photoelectric conversion element was obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating solution, 10.6 g of 2-propanol was changed to 10.6 g of chlorobenzene (chlorobenzene alone was used as the solvent) and resin solution 1 was not used.

[0151] Comparative Example 5 A photoelectric conversion element was obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating solution, particles 1 were replaced with nickel(II) phthalocyanine-tetrasulfonic acid tetrasodium salt, 10.6 g of 2-propanol was replaced with 10.6 g of water, resin solution 1 was replaced with PEDOT:PSS (2.7% by mass, manufactured by Sigma-Aldrich Co.) and the amount added was changed to 0.37 g, and the solvent was changed to water only.

[0152] Comparative Example 6 A photoelectric conversion element was obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating solution, 10.6 g of 2-propanol was changed to 10.6 g of chlorobenzene, particles 1 were changed to Spiro-OMeTAD, resin solution 1 was changed to resin solution 5, and the solvent was changed to chlorobenzene only.

[0153] [Evaluation] A power supply (manufactured by Keithley, Model 236) was connected between the electrodes of the photoelectric conversion element prepared in Example 1, and an intensity of 100 mW / cm ２ The photoelectric conversion efficiency was measured by irradiating the device with a constant amount of light using a solar simulator (manufactured by Yamashita Denso Co., Ltd.) and measuring the generated current and voltage. The results are shown in Table 2.

[0154] The photoelectric conversion efficiency of Examples 2 to 26 and Comparative Examples 1 to 6 was evaluated in the same manner as in Example 1. The results are shown in Table 2. In Table 2, the photoelectric conversion efficiency of Example 1 was set to 100, and the conversion efficiency of each photoelectric conversion element was expressed as a percentage of this efficiency. In Comparative Examples 5 and 6, the charge transport material was dissolved in a solvent and the particles were not dispersed, so the particle size was not measured.

[0155]

[0156] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0157] This application is related to Japanese Patent Application No. 2023-184761 filed on October 27, 2023, Japanese Patent Application No. 2023-184756 filed on October 27, 2023, Japanese Patent Application No. 2023-184750 filed on October 27, 2023, Japanese Patent Application No. 2023-216294 filed on December 21, 2023, Japanese Patent Application No. 2023-216296 filed on December 21, 2023, and Japanese Patent Application No. 2023-2162 filed on December 21, 2023. 99, Japanese Patent Application No. 2024-022244 filed on February 16, 2024, Japanese Patent Application No. 2024-022251 filed on February 16, 2024, Japanese Patent Application No. 2024-022246 filed on February 16, 2024, Japanese Patent Application No. 2024-082826 filed on May 21, 2024, and Japanese Patent Application No. 2024-186504 filed on October 23, 2024. Priority is claimed based on the Japanese Patent Application No. 2024-186504 filed on October 23, 2024, the entire contents of which are incorporated herein by reference.

[0158] REFERENCE SIGNS LIST 1 Photoelectric conversion element 2 Substrate 3 Second electrode 4 Electron transport layer 5 Photoelectric conversion layer 6 Charge transport layer 7 First electrode 30 Mobile body 31, 41 Photoelectric conversion element 32 Airframe 40 Building material 42 Protective member 43 Heat dissipation member 44a, 44b Exterior

Claims

1. A method for producing a photoelectric conversion element having a first electrode, a photoelectric conversion layer containing crystals of a perovskite structure, a charge transport layer, and a second electrode, comprising a step of forming a charge transport layer by applying a charge transport layer coating liquid onto a surface of the photoelectric conversion layer, the charge transport layer coating liquid comprising an alcohol liquid, a resin, and charge transport particles.

2. The method for producing a photoelectric conversion element according to claim 1, wherein the alcohol liquid contains an aliphatic alcohol.

3. The method for producing a photoelectric conversion element according to claim 1 or 2, wherein the alcohol liquid contains an alcohol having 5 or less carbon atoms.

4. The method for producing a photoelectric conversion element according to any one of claims 1 to 3, wherein the resin is a resin having a Lewis basic functional group.

5. The method for producing a photoelectric conversion element according to any one of claims 1 to 4, wherein the resin has at least one functional group selected from the group consisting of a hydroxy group, a carbonyl group, an ether group, an ester group, a pyridyl group, and a thienylidene group.

6. The method for producing a photoelectric conversion element according to any one of claims 1 to 5, wherein the resin includes a polyvinyl acetal resin.

7. The method for producing a photoelectric conversion element according to any one of claims 1 to 6, wherein the glass transition temperature of the resin is 95°C or lower.

8. The method for producing a photoelectric conversion element according to any one of claims 1 to 7, wherein the mass of the charge transport particles in the charge transport layer coating liquid is 5 to 20 times the mass of the resin in the charge transport layer coating liquid.

9. The particle diameter of the charge transporting particles in the charge transport layer coating liquid is 1.0×10 １ nm or more 5.0×10 ２ The method for producing a photoelectric conversion element according to any one of claims 1 to 8, wherein the thickness of the photoelectric conversion element is 1 nm or less.

10. The method for producing a photoelectric conversion element according to any one of claims 1 to 9, wherein the charge transporting particles are particles containing a cyclic conjugated compound in which a plurality of pyrrole rings are conjugated.

11. The method for producing a photoelectric conversion element according to any one of claims 1 to 10, wherein the charge transporting particles are particles containing a phthalocyanine compound.

12. The method for producing a photoelectric conversion element according to any one of claims 1 to 11, wherein the charge transporting particles are particles having a structure represented by the following formula (Pc-2): (In the above formula (Pc-2), M represents H2, a metal atom having a ligand, or a metal atom having no ligand.) 13. The method for producing the photoelectric conversion element according to any one of claims 1 to 12, further comprising a step of forming a second charge transport layer on a surface of the charge transport layer.

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