Photoelectric conversion element, solar cell module, and solar water heater

Abstract

To provide a photoelectric conversion element that has light resistance, heat resistance, and infrared light transmittance, and has excellent conversion efficiency.SOLUTION: A photoelectric conversion element includes a first substrate, a first electrode, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode, in this order. The first electrode includes a metal nanowire, and the hole transport layer includes a polymer of a hole transport material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a photoelectric conversion element, a solar cell module, and a solar water heater. [Background technology]

[0002] In recent years, solar cells that use photoelectric conversion elements are expected to have a wide range of applications, not only as an alternative to fossil fuels and a measure against global warming, but also as a stand-alone power source that does not require battery replacement or power wiring, etc. Furthermore, as a stand-alone power source, solar cells are attracting a great deal of attention as one of the energy harvesting technologies required for IoT (Internet of Things) devices, artificial satellites, etc.

[0003] Solar cells include inorganic solar cells that use silicon and other materials that have been widely used for a long time, as well as organic solar cells such as dye-sensitized solar cells, organic thin-film solar cells, and perovskite solar cells. Perovskite solar cells can be manufactured using conventional printing methods without using electrolytes containing organic solvents, and are therefore advantageous in terms of improving safety and reducing manufacturing costs.

[0004] It is also known that electrodes have been produced using silver nanowires in the manufacture of large-area perovskite solar cells based on inkjet printing (see, for example, Non-Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to provide a photoelectric conversion element that has light resistance, heat resistance, infrared light transmittance, and excellent conversion efficiency. [Means for solving the problem]

[0006] The photoelectric conversion element of this embodiment is a photoelectric conversion element having, in this order, a first substrate, a first electrode, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode, wherein the first electrode contains metal nanowires and the hole transport layer contains a polymer of a hole transport material. [ka] In the general formula (1), X represents an aromatic hydrocarbon group which may have a substituent, and Y represents a pyridine group which may have a substituent. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a photoelectric conversion element that has light resistance, heat resistance, infrared light transmittance, and excellent conversion efficiency. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of an example of an inverted structure solar cell as an embodiment of a photoelectric conversion element. [Figure 2] FIG. 2 is a schematic diagram of another example of an inverted structure solar cell as an embodiment of a photoelectric conversion element. [Figure 3] FIG. 3 is a schematic diagram showing an embodiment of a solar cell module. [Figure 4] FIG. 4 is a schematic diagram showing another embodiment of the solar cell module. [Figure 5] FIG. 5 is a schematic diagram showing another embodiment of the solar cell module. [Figure 6] FIG. 6 is a diagram showing the IR spectrum of Compound No. 1 in Synthesis Example 1. [Figure 7] FIG. 7 is a graph showing the infrared light transmittance of the first electrode and the first substrate in Example 1. As shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Photoelectric conversion element)

[0010] The photoelectric conversion element means an element capable of converting light energy into electrical energy or electrical energy into light energy, and is used in solar cells, photodiodes, and the like. The photoelectric conversion element of this embodiment is a so-called inverted structure photoelectric conversion element having a first substrate, a first electrode, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode in this order. The first electrode includes metal nanowires, and the hole transport layer includes a polymer of a hole transporting material. The inverted structure photoelectric conversion element preferably further includes a passivation layer between the photoelectric conversion layer and the electron transport layer.

[0011] The photoelectric conversion element of this embodiment is an invention based on the inventors' discovery of problems in the prior art and the following findings. That is, electrodes containing metal nanowires have higher infrared light transmittance than ITO substrates, making it possible to effectively utilize infrared light, but silver nanowires pose a problem of silver corrosion due to halogen ions derived from the perovskite layer. Adsorption-type hole-transport materials (e.g., hole-transport materials with phosphonic acid or carboxylic acid groups), which can achieve high output in inverted perovskite solar cells, are unable to achieve chemical adsorption to metal nanowire materials, making it difficult to achieve high conversion efficiency and durability in photoelectric conversion elements. Hole transport layers made of conductive polymers such as poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonic acid) (PEDOT / PSS) are also known. The prior art described in Non-Patent Document 1 reports a perovskite solar cell that combines an electrode containing silver nanowires with a hole transport layer containing PEDOT / PSS, but this has the problem of poor light resistance in the photoelectric conversion element.

[0012] As a result of extensive research conducted by the inventors to solve the above-mentioned conventional problems and achieve the above-mentioned object, they discovered that a photoelectric conversion element having a first substrate, a first electrode, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode in this order, in which the first electrode contains metal nanowires and the hole transport layer contains a polymer of a hole transport material, can provide: (1) high conversion efficiency and improved light resistance due to excellent charge injection properties in the first electrode containing metal nanowires and the photoelectric conversion layer, respectively, by the hole transport layer containing the polymer of the hole transport material; (2) improved heat resistance due to suppression of halogen corrosion from the photoelectric conversion layer made of silver nanowires; and (3) excellent infrared light transmittance due to the first electrode containing metal nanowires, thereby providing a photoelectric conversion element that has light resistance, heat resistance, and infrared light transmittance and excellent conversion efficiency, thereby completing the present invention. In addition, in a tandem solar cell module, by using a top cell (photoelectric conversion element on the light-receiving surface side) that combines a first electrode containing metal nanowires with a second electrode (translucent counter electrode) that also contains metal nanowires, the top cell has excellent infrared light transmittance, thereby achieving high conversion efficiency in the solar cell module. Furthermore, in a solar water heater having a photoelectric conversion element, the high infrared light transmittance of the photoelectric conversion element of this embodiment not only allows the transmitted infrared light to be collected and used efficiently to heat hot water, but also allows the heat generated by the photoelectric conversion element itself to be used to heat hot water, contributing to higher efficiency of the solar water heater having a photoelectric conversion element.

[0013] <First board> The shape, structure, and size of the first substrate are not particularly limited and can be appropriately selected depending on the purpose. The material of the first substrate is not particularly limited as long as it has infrared light transparency and insulating properties, and can be appropriately selected depending on the purpose, and examples thereof include glass, plastic film, ceramic, etc. Among these, when a firing step is included in forming the electron transport layer as described below, a substrate that is heat resistant to the firing temperature is preferred. Furthermore, a flexible first substrate is more preferred.

[0014] A second substrate may be provided on the outermost side of the second electrode side. The second substrate may be selected appropriately from the items described above for the first substrate. Hereinafter, the substrate provided at the outermost position on the first electrode side will be referred to as the first substrate, and the substrate provided at the outermost position on the second electrode side will be referred to as the second substrate, and the first substrate and second substrate will be collectively referred to as substrates. The average thickness of the substrate is not particularly limited and can be appropriately selected depending on the purpose, and may be, for example, 50 μm or more and 5 mm or less.

[0015] <First electrode> The first electrode is not particularly limited in shape or size, as long as it contains metal nanowires and has infrared light transparency, and can be appropriately selected depending on the purpose. Hereinafter, the electrode provided on the first substrate side will be referred to as the first electrode, the electrode provided on the second substrate side will be referred to as the second electrode, and the first electrode and second electrode will be collectively referred to as the electrode.

[0016] The structure of the first electrode is not particularly limited and can be appropriately selected depending on the purpose, and may be a single-layer structure or a structure in which multiple materials are laminated.

[0017] -Metal nanowires- The metal nanowires are not particularly limited and can be appropriately selected depending on the purpose. For example, nanowires made of a metal selected from the group consisting of silver, silver alloys, copper, and copper alloys are preferred, and silver nanowires and silver alloy nanowires are more preferred.

[0018] In the first electrode, the plurality of metal nanowires are partially in contact with or fused with one another to form a network structure such as a mesh or lattice. This forms a plurality of conductive paths, forming a conductive cluster or conductive layer in which the entire structure is connected. To increase the conductivity of the first electrode, it is preferable that the density of the metal nanowires is high. On the other hand, to obtain an electrode for use in a device that requires transparency and flexibility, it is preferable that the density of the nanowires is below a certain level. The content or coating amount of the metal nanowires in the first electrode is not particularly limited and can be appropriately selected depending on the purpose. However, from the viewpoint of achieving sufficient transparency, flexibility, and conductivity in the resulting first electrode, a content of 0.05 g / m 2 ~50g / m 2 is preferred, and 0.1 g / m 2 ~10g / m 2 More preferably, 0.15 g / m 2 ~1g / m 2 is more preferred.

[0019] The size of the metal nanowires is not particularly limited and can be appropriately selected depending on the purpose. Generally, longer nanowires are more likely to form conductive clusters, and nanowires with larger diameters have higher conductivity.

[0020] The diameter of the metal nanowires is preferably 10 nm to 500 nm, more preferably 20 nm to 150 nm, and even more preferably 30 nm to 120 nm, in order to achieve sufficient transparency, flexibility, and conductivity in the resulting first electrode. If the diameter is less than 10 nm, the electrical resistance of the nanowire itself tends to increase, and if it exceeds 500 nm, there is a risk of light scattering and the like increasing, resulting in a decrease in transparency.On the other hand, it is preferable that the diameter is 10 nm to 500 nm.

[0021] The length of the metal nanowires is preferably 0.1 μm to 50 μm, more preferably 1 μm to 40 μm, and even more preferably 5 μm to 30 μm, in order to achieve sufficient transparency, flexibility, and conductivity in the resulting first electrode. If the length is less than 0.1 μm, sufficient conductive clusters will not be formed, and the electrical resistance will tend to be high, while if it exceeds 50 μm, dispersion in a solvent when producing an electrode or the like will tend to be unstable.

[0022] The diameter and length of metal nanowires can be measured, for example, by analyzing SEM images taken with a scanning electron microscope (SEM).

[0023] The method for producing the metal nanowires is not particularly limited and can be appropriately selected depending on the purpose. For example, silver nanowires can be produced by reducing an aqueous solution of silver ions using various reducing agents. The shape and size of the silver nanowires can be controlled by selecting the type of reducing agent, protective polymer or dispersant, and coexisting ions used. To produce silver nanowires, it is preferable to use a polyhydric alcohol such as ethylene glycol as the reducing agent and polyvinylpyrrolidone or its derivatives as the protective polymer. By using these raw materials, so-called nanowires on the nanometer order can be obtained.

[0024] The first electrode can be composed only of the metal nanowires, but may also contain other components such as a binder polymer; a conductive polymer, or a conductive material such as metal nanoparticles or conductive oxide nanoparticles.

[0025] Depending on the type, the binder polymer can function as a binder for the metal nanowires or can improve the adhesion between the first electrode and the first substrate, thereby preventing the first electrode from peeling off. Examples of the binder polymer include polyolefins, acrylic polymers, and polyurethane polymers having polar groups. When used in combination with the binder polymer, the content of the binder polymer is preferably low from the viewpoint of maintaining the electrical resistance of the first electrode, and is preferably 5 parts by mass or less per 100 parts by mass of the total amount of the first electrode.

[0026] In one embodiment, it is preferable that the first electrode further contains a conductive polymer, and that the mass ratio (A / B) of the metal nanowires (A) to the conductive polymer (B) in the first electrode is 2 or more and 6 or less.

[0027] The average thickness of the first electrode is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5 nm to 100 μm, more preferably 50 nm to 10 μm. When the first electrode is made of carbon or metal, the average thickness of the first electrode is preferably set to an average thickness that ensures light transmittance.

[0028] The first electrode can be formed by a known method such as a die coating method, a spin coating method, a spray method, or an ink jet method.

[0029] Examples of materials for the metal lead wire include aluminum, copper, silver, gold, platinum, and nickel. The metal lead wires can be formed on a substrate by, for example, vapor deposition, sputtering, or pressure bonding, and then a layer of metal nanowires can be provided thereon, or the metal lead wires can be provided on the first electrode for combined use.

[0030] <Hole transport layer> The hole transport layer refers to a layer that transports holes (positive holes) generated in the photoelectric conversion layer to the adjacent first electrode. Therefore, the hole transport layer is preferably disposed adjacent to the photoelectric conversion layer directly or via a salt. The hole transport layer contains a polymer of a hole transport material, and may further contain other components as required.

[0031] <<Hole transport materials>> The hole transporting material is a material that has a polymerizable group and can form a polymer, and the polymer has hole transporting properties. The polymerizable group is not particularly limited as long as it is a polymerizable group, and a known polymerizable group can be appropriately selected depending on the purpose. Examples of the polymerizable group include a group having a carbon-carbon multiple bond, a group having a small ring, and a combination of groups capable of forming an ester bond or an amide bond. These may be used alone or in combination of two or more, and may have a substituent as a linking group (divalent group).

[0032] Examples of the group having a carbon-carbon multiple bond include a vinyl group, an acetylene group (ethynyl group), a butenyl group, an acryl group (acryloyl group), an acrylate group (acryloyloxy group), an acrylamide group (acryloylamino group), a methacryl group (methacryloyl group), a methacrylate group (methacryloyloxy group), a methacrylamide group (methacryloylamino group), an aryl group, an allyl group, a vinyl ether group (vinyloxy group), a vinylamino group, a furanyl group, a pyrrolyl group, a thiophenyl group, and a silolyl group. Examples of the group having a small ring include a cyclopropyl group, a cyclobutyl group, an epoxy group (oxiranyl group), an oxetane group (oxetanyl group), a diketene group, an episulfide group, a lactone group, and a lactam group. Examples of the combination of groups capable of forming an ester bond or an amide bond include a combination of an ester group and an amino group, an ester group and a hydroxyl group, and the like.

[0033] Among the polymerizable groups, from the viewpoint of reactivity, an oxetane group, an epoxy group, a vinyl group, a vinyl ether group, an acrylate group, and a methacrylate group are preferred.

[0034] The hole transport material may or may not have a pyridine group. However, from the viewpoint of obtaining higher light resistance, it preferably has a pyridine group, and is more preferably a compound represented by the following general formula (1): [ka] In the general formula (1), X represents an aromatic hydrocarbon group which may have a substituent, and Y represents a pyridine group which may have a substituent.

[0035] The aromatic hydrocarbon group for X is preferably a benzene ring. The substituent for X may be a monovalent group or a divalent group, and examples thereof include alkyl groups such as a methyl group and an ethyl group; alkylene groups such as a methylene group and an ethylene group; and alkene groups such as an ethenyl group (-CH=CH-).

[0036] X in the general formula (1) is preferably selected from the group consisting of the following: where R 1 and R 2 each independently represents a hydrogen atom or a methyl group. The compounds and the substituents include any cis-trans isomers. In particular, with respect to the following X having an ethenyl group as a substituent, the ethenyl group may be a cis isomer, a trans isomer, or a mixture of cis and trans isomers, but from the viewpoint of solubility, it is preferable that it contains a cis isomer, and a mixture of cis and trans isomers (a cis-trans mixed ethenyl group) is preferred. [ka]

[0037] Suitable examples of the substituent for Y include divalent groups such as alkylene groups such as methylene and ethylene groups, and arylene groups such as phenylene and naphthylene groups. The arylene group may have a substituent, and examples of the substituent include alkyl groups such as methyl and ethyl groups. In consideration of the energy level and charge transportability, the substituent in Y is preferably an arylene group, and the pyridine group in Y preferably does not have a monovalent group.

[0038] Y in the general formula (1) is preferably selected from the group consisting of the following: where R 3 and R 4 each independently represents a hydrogen atom or a methyl group. [ka]

[0039] Examples of the hole transport material represented by the general formula (1) include the following compounds No. 1 to No. 13. [ka] [ka] [ka]

[0040] In organic electronics devices (organic photoreceptors, organic LEDs) such as organic solar cells, the hole transport material to be coated and laminated onto the formed functional layer is preferably insoluble in the coating solvent, and various insolubilization methods are known (e.g., thermal curing, ultraviolet curing, electron beam curing, etc.). The hole-transporting material represented by the general formula (1) has the following properties (1) to (3), and thus provides a solvent-resistant hole-transporting material that can be used to produce highly durable photoelectric conversion elements. The hole-transporting material can be suitably used as a thermally crosslinked hole-transporting material and hole-transporting layer (HTL) in inverted perovskite solar cells (PSCs). (1) a polymerizable group capable of forming a (three-dimensional) polymerized molecular structure by a thermal reaction; (2) a polymerizable group located at the N-para position of the triphenylamine structure, which has high thermal reactivity; and (3) Pyridine groups, which are known to chemically coordinate in the perovskite crystal structure.

[0041] In addition, when X in the general formula (1) has a mixed cis-trans ethenyl group, the polymer obtained by polymerizing the hole transport material has high amorphous properties and forms structural isomers, which is advantageous in that the temperature during curing is lowered and the reaction rate is increased.

[0042] The hole transport material may be a hole transport material represented by general formula (1) having another polymerizable group instead of the terminal bifunctional vinyl group, such as the following compound No. 14 having an oxetane group and a substituent (divalent group). Alternatively, the hole transport material may have no pyridine group, or may have the pyridine group in the hole transport material represented by the general formula (1) substituted with a phenyl group, and examples thereof include Compound No. 15 below. In addition, the compound may have a trifunctional polymerizable group at the end, for example, Compound No. 16 below. [ka]

[0043] Suitable examples of the hole transporting material include the hole transporting material represented by the general formula (2). [ka] In the general formula (2), each X independently represents a polymerizable group which may have a substituent, and each Y independently represents a group selected from the group consisting of a pyridine group which may have a substituent, and an alkoxy group.

[0044] The polymerizable group for X can be appropriately selected from the above-mentioned polymerizable groups, and is preferably an oxetane group, an epoxy group, a vinyl group, a vinyl ether group, an acrylate group, or a methacrylate group. The substituent for X may be, for example, a monovalent group or a divalent group, and examples thereof include alkyl groups such as a methyl group and an ethyl group; alkylene groups such as a methylene group and an ethylene group; and oxyalkylene groups such as an oxymethylene group and an oxyethylene group.

[0045] Suitable examples of the substituent for Y include divalent groups such as alkylene groups such as methylene and ethylene groups, and arylene groups such as phenylene and naphthylene groups. The arylene group may have a substituent, and examples of the substituent include alkyl groups such as methyl and ethyl groups. Examples of the alkoxy group represented by Y include a methoxy group and an ethoxy group.

[0046] Examples of the hole transport material represented by the general formula (2) include the following compounds No. 17 to No. 20. [ka] [ka]

[0047] The hole transport layer can be formed by applying a liquid composition containing the hole transport material, a solvent, and, if necessary, other components such as a polymerization initiator, onto the first electrode.

[0048] -solvent- The solvent is not particularly limited and can be appropriately selected depending on the purpose. Examples of the solvent include ketones, esters, ethers, amides, halogenated hydrocarbons, and hydrocarbons. Examples of ketones include acetone, methyl ethyl ketone, and methyl isobutyl ketone. Examples of the ester include ethyl formate, ethyl acetate, and n-butyl acetate. Examples of the ether include diisopropyl ether, dimethoxyethane, tetrahydrofuran, dioxolane, and dioxane. Examples of the amide include N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone. Examples of halogenated hydrocarbons include dichloromethane, chloroform, bromoform, methyl iodide, dichloroethane, trichloroethane, trichloroethylene, chlorobenzene, o-dichlorobenzene, fluorobenzene, bromobenzene, iodobenzene, and 1-chloronaphthalene. Examples of hydrocarbons include n-pentane, n-hexane, n-octane, 1,5-hexadiene, cyclohexane, methylcyclohexane, cyclohexadiene, benzene, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, and cumene. These may be used alone or in combination of two or more.

[0049] -Polymerization initiator- A polymerization initiator may be mixed to promote the polymerization of the formula (1). Examples of the polymerization initiator include a thermal polymerization initiator that uses heat to initiate polymerization, and a photopolymerization initiator that uses light to initiate polymerization. The thermal polymerization initiator is a compound that generates active species such as radicals or cations when heated, and specifically, an azo compound such as 2,2'-azobisbutyronitrile (AIBN), a peroxide such as benzoyl peroxide (BPO), etc. The thermal cationic polymerization initiator is, for example, a benzenesulfonate ester or an alkylsulfonium salt. On the other hand, in the case of an epoxy resin, a photocationic polymerization initiator is preferably used as the photopolymerization initiator. When the epoxy resin is mixed with the photocationic polymerization initiator and irradiated with light, the photocationic polymerization initiator decomposes to generate a strong acid, which then induces polymerization of the epoxy resin, thereby progressing the curing reaction. The photocationic polymerization initiator has the effects of causing little volume shrinkage during curing, not being inhibited by oxygen, and having high storage stability. Examples of the photocationic polymerization initiator include aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts, methacerone compounds, and silanol-aluminum complexes.

[0050] Photoacid generators that generate acid upon irradiation with light can also be used. Photoacid generators act as acids that initiate cationic polymerization, and examples include ionic onium salts such as sulfonium salts and iodonium salts that consist of a cationic moiety and an anionic moiety. Ionic compounds having a structure in which an alkylamino group is present in the cationic moiety and a tetrakis(pentafluorophenyl)borate group in the anionic moiety are more preferred. These may be used alone or in combination of two or more. The amount of the polymerization initiator added may vary depending on the material used, but is preferably 0.5 parts by mass to 10 parts by mass, and more preferably 1 part by mass to 5 parts by mass, relative to 100 parts by mass of the total amount of the sealing member. By adding an amount within the above range, curing proceeds appropriately, the amount of uncured material remaining can be reduced, and excessive outgassing can be prevented, which is effective.

[0051] The method for identifying the hole transport material and the hole transport layer is not particularly limited and can be appropriately selected depending on the purpose. For example, the hole transport material can be identified by using a Fourier transform infrared spectrometer (FT-IR) (for example, an IRTracer-100, manufactured by Shimadzu Corporation). In the hole transport layer, the hole transport material, which is a component of the polymer of the hole transport material, exists as a residual monomer. Therefore, by identifying the residual hole transport material, the component of the polymer of the hole transport material can be identified.

[0052] In addition to the polymer of the hole transport material described above, the hole transport layer may contain a compound having a structural unit of the following general formula (3) and a compound represented by the following general formula (4): By adding the dopant represented by the general formula (4), the hole transport solution does not gel, and the resistance of the hole transport layer formed using the ink is reduced.

[0053] [ka] Ar in the general formula (3) 1 represents an aryl group. Examples of the aryl group include a phenyl group, a 1-naphthyl group, and a 9-anthracenyl group. The aryl group may have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, and an aryl group. Ar 2 , and Ar 3 each independently represents an arylene group, a divalent heterocyclic group, or the like. Examples of arylene groups include 1,4-phenylene, 1,1'-biphenylene, and 9,9'-di-n-hexylfluorene. Examples of divalent heterocyclic groups include 2,5-thiophene.

[0054] The compound having the structural unit of the general formula (3) is preferably a compound represented by the general formula (3A), which can reduce the resistance of the hole transport layer.

[0055] [ka] However, in the general formula (3A), Ar 1 represents an aromatic hydrocarbon group which may have a substituent, Ar2 and Ar 3 each independently represents a divalent group of an optionally substituted monocyclic, optionally substituted non-fused polycyclic, or optionally substituted fused polycyclic aromatic hydrocarbon group, Ar 4 represents a divalent group of optionally substituted benzene, optionally substituted thiophene, optionally substituted biphenyl, optionally substituted anthracene, or optionally substituted naphthalene, n represents an integer of 2 or more. The weight average molecular weight of the polymer represented by the general formula (3A) is preferably 2,000 or more.

[0056] Ar in the general formula (3A) 1 represents an aromatic hydrocarbon group which may have a substituent, for example, an aryl group which may have a substituent. Examples of the aryl group include a phenyl group, a 1-naphthyl group, a 9-anthracenyl group, etc. Examples of the substituent include an alkyl group, an alkoxy group, an aryl group, etc. Ar 2 and Ar 3 Each independently represents a divalent group of an optionally substituted monocyclic, optionally substituted non-fused polycyclic, or optionally substituted fused polycyclic aromatic hydrocarbon group, such as an optionally substituted arylene group or an optionally substituted divalent heterocyclic group. Examples of arylene groups include 1,4-phenylene, 1,1'-biphenylene, and 9,9'-di-n-hexylfluorene. Examples of divalent heterocyclic groups include 2,5-thiophene. Examples of substituents include alkyl groups, alkoxy groups, and aryl groups. Ar4 represents a divalent group of benzene, thiophene, biphenyl, anthracene, or naphthalene, which may be substituted with a substituent, such as an alkyl group, an alkoxy group, or an aryl group.

[0057] The compound represented by the general formula (3A) is preferably a compound represented by the following general formula (3B).

[0058] [ka] In the general formula (3B), R5 represents a methyl group or a methoxy group, R6 and R7 represent an alkoxy group, and n represents an integer of 2 or more.

[0059] The weight average molecular weight of the compound (polymer) represented by the general formula (3) is preferably 2,000 or more and 150,000 or less. The weight average molecular weight can be measured by gel permeation chromatography (GPC).

[0060] Specific examples of the polymer represented by the general formula (3) include the following (A-01) to (A-31), but are not limited to these.

[0061] [ka] [ka] [ka] [ka] [ka] [ka]

[0062] [ka] In the general formula (4), M represents any one of boron, aluminum, phosphorus, and antimony, and R2, R3, and R4 each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, a heteroaryl group, an ether bond, or an ester bond.

[0063] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the alkyl group include alkyl groups having a carbon number of 1 to 6. The alkyl group may be substituted with a halogen atom. Examples of the alkoxy group include alkoxy groups having 1 to 6 carbon atoms. The aryl group may, for example, be a phenyl group.

[0064] Specific examples of the compound represented by the general formula (4) include the following (B-1) to (B-17), but are not limited to these.

[0065] [ka] [ka]

[0066] The hole transport layer may further contain, for example, other solid hole transport materials, and may contain other materials as needed. The other solid hole transport material (hereinafter, sometimes simply referred to as "hole transport material") is not particularly limited as long as it has the property of transporting holes and can be appropriately selected depending on the purpose, but it is preferable that it contains an organic compound.

[0067] When an organic compound is used as the hole transporting material, the hole transport layer contains, for example, a plurality of types of organic compounds.

[0068] The organic compound may be, for example, a polymer material. The polymer material used in the hole transport layer is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include polythiophene compounds, polyphenylene vinylene compounds, polyfluorene compounds, polyphenylene compounds, polyarylamine compounds, and polythiadiazole compounds. Examples of polythiophene compounds include poly(3-n-hexylthiophene), poly(3-n-octyloxythiophene), poly(9,9'-dioctyl-fluorene-co-bithiophene), poly(3,3'''-didodecyl-quaterthiophene), poly(3,6-dioctylthieno[3,2-b]thiophene), and poly(2,5-bis(3-decylthiophen-2-yl)thieno[3,2 -b]thiophene), poly(3,4-didecylthiophene-co-thieno[3,2-b]thiophene), poly(3,6-dioctylthieno[3,2-b]thiophene-co-thieno[3,2-b]thiophene), poly(3,6-dioctylthieno[3,2-b]thiophene-co-thiophene), or poly(3,6-dioctylthieno[3,2-b]thiophene-co-bithiophene). Examples of polyphenylene vinylene compounds include poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylene vinylene], and poly[(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene)-co-(4,4′-biphenylene vinylene)]. Examples of polyfluorene compounds include poly(9,9'-didodecylfluorenyl-2,7-diyl), poly[(9,9-dioctyl-2,7-divinylenefluorene)-alt-co-(9,10-anthracene)], poly[(9,9-dioctyl-2,7-divinylenefluorene)-alt-co-(4,4'-biphenylene)], poly[(9,9-dioctyl-2,7-divinylenefluorene)-alt-co-(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene)], and poly[(9,9-dioctyl-2,7-diyl)-co-(1,4-(2,5-dihexyloxy)benzene)]. Examples of polyphenylene compounds include poly[2,5-dioctyloxy-1,4-phenylene] and poly[2,5-di(2-ethylhexyloxy-1,4-phenylene]]. Examples of the polyarylamine compound include poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(N,N'-diphenyl)-N,N'-di(p-hexylphenyl)-1,4-diaminobenzene], poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(N,N'-bis(4-octyloxyphenyl)benzidine-N,N'-(1,4-diphenylene)], poly[(N,N'-bis(4-octyloxyphenyl)benzidine-N,N'-(1,4-diphenylene)], poly poly[(N,N'-bis(4-(2-ethylhexyloxy)phenyl)benzidine-N,N'-(1,4-diphenylene)], poly[phenylimino-1,4-phenylenevinylene-2,5-dioctyloxy-1,4-phenylenevinylene-1,4-phenylene], poly[p-tolylimino-1,4-phenylenevinylene-2,5-di(2-ethylhexyloxy)-1,4-phenylenevinylene-1,4-phenylene], poly[4-(2-ethylhexyloxy)phenylimino-1,4-biphenylene], and the like. Examples of polythiadiazole compounds include poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(1,4-benzo(2,1′,3)thiadiazole], poly(3,4-didecylthiophene-co-(1,4-benzo(2,1′,3)thiadiazole), and the like. Among these, polythiophene compounds and polyarylamine compounds are preferred in consideration of carrier mobility and ionization potential.

[0069] The hole transport layer may contain not only the above-mentioned polymers but also a low molecular weight compound alone or a mixture of a low molecular weight compound and a high molecular weight compound. The low-molecular-weight hole-transporting material is not particularly limited in chemical structure, and examples thereof include oxadiazole compounds, triphenylmethane compounds, pyrazoline compounds, hydrazone compounds, tetraarylbenzidine compounds, stilbene compounds, spirobifluorene compounds, and thiophene oligomers. Examples of the oxadiazole compound include the oxadiazole compounds disclosed in JP-B No. 34-5466 and JP-A No. 56-123544. Examples of the triphenylmethane compound include the triphenylmethane compounds disclosed in Japanese Patent Publication No. 45-555. Examples of the pyrazoline compounds include those disclosed in Japanese Patent Publication No. 52-4188. Examples of the hydrazone compounds include those disclosed in Japanese Patent Publication No. 55-42380. Examples of the tetraarylbenzidine compound include the tetraarylbenzidine compounds disclosed in JP-A-54-58445. Examples of the stilbene compounds include those disclosed in JP-A Nos. 58-65440 and 60-98437. Examples of spirobifluorene compounds include those disclosed in JP 2007-115665 A, JP 2014-72327 A, JP 2001-257012 A, WO 2004 / 063283 A, WO 2011 / 030450 A, WO 2011 / 45321 A, WO 2013 / 042699 A, and WO 2013 / 121835 A. Examples of the thiophene oligomer include the thiophene oligomers disclosed in JP-A-2-250881 and JP-A-2013-033868.

[0070] When a polymer and a low molecular weight compound are mixed, the difference in their ionization potentials is preferably 0.2 eV or less. Ionization potential is the energy required to remove one electron from a molecule and is expressed in units of electron volts (eV). There are no particular restrictions on the method for measuring ionization potential, but photoelectron spectroscopy is preferred.

[0071] Other materials contained in the hole transport layer are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include additives and oxidizing agents.

[0072] The additive is not particularly limited and can be appropriately selected depending on the purpose. Examples of the additive include metal iodides such as iodine, lithium iodide, sodium iodide, potassium iodide, cesium iodide, calcium iodide, copper iodide, iron iodide, and silver iodide; quaternary ammonium salts such as tetraalkylammonium iodide and pyridinium iodide; metal bromides such as lithium bromide, sodium bromide, potassium bromide, cesium bromide, and calcium bromide; tetraalkylammonium bromide and pyridinium bromide; metal chlorides such as copper chloride or silver chloride; metal acetates such as copper acetate, silver acetate or palladium acetate; metal sulfates such as copper sulfate or zinc sulfate; metal complexes such as ferrocyanide-ferricyanide or ferrocene-ferricinium ion; sulfur compounds such as sodium polysulfide or alkylthiol-alkyldisulfide; viologen dyes; hydroquinone; and basic compounds such as pyridine, 4-t-butylpyridine or benzimidazole.

[0073] Additionally, an oxidizing agent can be added. The oxidizing agent is not particularly limited and can be appropriately selected depending on the purpose. Examples include tris(4-bromophenyl)aminium hexachloroantimonate, silver hexafluoroantimonate, nitrosonium tetrafluoroborate, silver nitrate, cobalt complexes, and 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate. It is not necessary for the oxidizing agent to oxidize the entire hole transport material; partial oxidation is sufficient. The oxidizing agent may or may not be removed from the system after the reaction. By including an oxidizing agent in the hole transport layer, part or all of the hole transport material can be converted into radical cations, thereby improving the conductivity and enhancing the durability and stability of the output characteristics.

[0074] The average thickness of the hole transport layer is not particularly limited and can be appropriately selected depending on the purpose. On the photoelectric conversion layer, the average thickness is preferably 0.01 μm or more and 20 μm or less, more preferably 0.1 μm or more and 10 μm or less, and even more preferably 0.2 μm or more and 2 μm or less.

[0075] The hole transport layer can be formed directly on the photoelectric conversion layer. The method for producing the hole transport layer is not particularly limited and can be appropriately selected depending on the purpose, and examples include a method for forming a thin film in a vacuum, such as vacuum deposition, and a wet film-forming method. Among these, in terms of production costs, the wet film-forming method is particularly preferred, and the method of coating on the photoelectric conversion layer is more preferred. The wet film-forming method is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include dipping, spraying, wire bar coating, spin coating, roller coating, blade coating, gravure coating, inkjet coating, etc. Furthermore, examples of wet printing methods that can be used include relief printing, offset printing, gravure printing, intaglio printing, rubber printing, and screen printing.

[0076] The hole transport layer may also be prepared by forming a film in, for example, a supercritical fluid or a subcritical fluid at a temperature and pressure lower than the critical point. A supercritical fluid is a fluid that exists as a non-aggregating high-density fluid in a temperature and pressure range above the limit (critical point) at which gas and liquid can coexist, does not aggregate even when compressed, and is in a state above the critical temperature and critical pressure. There are no particular limitations on the supercritical fluid and it can be selected appropriately depending on the purpose, but one with a low critical temperature is preferred. The subcritical fluid is not particularly limited as long as it exists as a high-pressure liquid in a temperature and pressure range near the critical point, and can be appropriately selected depending on the purpose. Fluids exemplified as supercritical fluids can also be suitably used as subcritical fluids.

[0077] Examples of supercritical fluids include carbon monoxide, carbon dioxide, ammonia, nitrogen, water, alcohol solvents, hydrocarbon solvents, halogen solvents, and ether solvents. Examples of alcohol solvents include methanol, ethanol, and n-butanol. Examples of hydrocarbon solvents include ethane, propane, 2,3-dimethylbutane, benzene, toluene, etc. Examples of halogen solvents include methylene chloride, chlorotrifluoromethane, etc. The ether solvent may, for example, be dimethyl ether. These may be used alone or in combination of two or more. Among these, carbon dioxide is preferred because it has a critical pressure of 7.3 MPa and a critical temperature of 31° C., and therefore can easily produce a supercritical state, and is non-flammable and easy to handle.

[0078] The critical temperature and critical pressure of the supercritical fluid are not particularly limited and can be appropriately selected depending on the purpose. The critical temperature of the supercritical fluid is preferably −273° C. or higher and 300° C. or lower, and more preferably 0° C. or higher and 200° C. or lower.

[0079] Furthermore, in addition to the supercritical fluid and subcritical fluid, an organic solvent and an entrainer can be used in combination. By adding the organic solvent and the entrainer, it is possible to more easily adjust the solubility in the supercritical fluid. The organic solvent is not particularly limited and can be appropriately selected depending on the purpose. For example, the organic solvent can be appropriately selected from the solvents listed above for the liquid composition of this embodiment.

[0080] <Photoelectric conversion layer> The photoelectric conversion layer is not particularly limited as long as it is a layer that performs photoelectric conversion, and can be appropriately selected depending on the purpose. Examples thereof include a perovskite layer and a bulk heterojunction layer.

[0081] <<Perovskite layer>> The perovskite layer refers to a layer that contains a perovskite compound and absorbs light to sensitize the electron transport layer, and is therefore preferably disposed adjacent to the electron transport layer.

[0082] The shape and size of the perovskite layer are not particularly limited and can be appropriately selected depending on the purpose.

[0083] The perovskite compound is a composite material of an organic compound and an inorganic compound, and is represented by the following general formula (5). X α Y β Z γ ...General formula (5) In the general formula (5), the ratio of α:β:γ is 3:1:1, β and γ represent integers greater than 1, X represents a halogen atom, Y represents an organic compound having an amino group, and Z represents a metal ion.

[0084] X in the general formula (5) is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include halogen atoms such as chlorine, bromine, iodine, etc. These may be used alone or in combination of two or more.

[0085] Y in the general formula (5) is not particularly limited as long as it is an organic cation and can be appropriately selected depending on the purpose. Examples include alkylamine compound ions such as methylamine, ethylamine, n-butylamine, and formamidine, and inorganic alkali metal cations such as Sb atom, Cs atom, Rb atom, and K atom. These may be used alone or in combination of two or more, or inorganic alkali metal cations and organic cations may be used in combination. Among these, organic compounds having an amino group are preferred. In addition, in the case of lead halide-methylammonium perovskite compounds, the peak λmax of the optical absorption spectrum shifts to longer wavelengths in the following order: approximately 350 nm when the halide ion is Cl, approximately 410 nm when the halide ion is Br, and approximately 540 nm when the halide ion is I; therefore, the available spectral width (band width) differs.

[0086] Z in the general formula (5) is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include ions of metals such as lead, indium, antimony, tin, copper, bismuth, etc. These may be used alone or in combination of two or more.

[0087] The perovskite layer preferably has a layered perovskite structure in which layers made of metal halide and layers in which organic cation molecules are arranged are alternately laminated.

[0088] The average thickness of the perovskite layer is preferably 50 nm or more and 2 μm or less, and more preferably 100 nm or more and 600 nm or less.

[0089] The method for forming the perovskite layer is not particularly limited and can be appropriately selected depending on the purpose. For example, a method of applying a solution in which a metal halide, an alkylamine halide, a cesium halide, or the like is dissolved or dispersed, followed by drying can be used. In addition, examples of methods for forming a perovskite layer include a two-stage precipitation method in which a solution in which a metal halide is dissolved or dispersed is applied and dried, and then the substrate is immersed in a solution in which a halogenated alkylamine is dissolved, thereby forming a perovskite compound. Furthermore, examples of methods for forming a perovskite layer include a method in which a solution in which a metal halide and an alkylamine halide are dissolved or dispersed is applied, and a poor solvent (a solvent with low solubility) for the perovskite compound is added to precipitate crystals. Additionally, examples of methods for forming a perovskite layer include a method in which a metal halide is vapor-deposited in a gas filled with methylamine or the like. Among these, a preferred method is to apply a solution in which a metal halide and an alkylamine halide are dissolved or dispersed, and then add a poor solvent for the perovskite compound to precipitate crystals.

[0090] The method for applying the solution is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include immersion, spin coating, spraying, dipping, roller coating, air knife coating, inkjet coating, etc. Furthermore, the method for applying the solution may be, for example, a method in which the solution is precipitated in a supercritical fluid using carbon dioxide or the like.

[0091] The perovskite layer may also contain a sensitizing dye. The method for forming the perovskite layer containing the sensitizing dye is not particularly limited and can be appropriately selected depending on the purpose. Examples of the method include a method of mixing a perovskite compound with a sensitizing dye, and a method of forming a perovskite layer and then adsorbing the sensitizing dye.

[0092] The sensitizing dye is not particularly limited as long as it is a compound that is photoexcited by the excitation light used, and can be appropriately selected depending on the purpose. Examples of the sensitizing dye include metal complex compounds, coumarin compounds, polyene compounds, indoline compounds, thiophene compounds, cyanine dyes, merocyanine dyes, 9-arylxanthene compounds, triarylmethane compounds, phthalocyanine compounds, and porphyrin compounds. Examples of the metal complex compounds include those described in JP-A-7-500630, JP-A-10-233238, JP-A-2000-26487, JP-A-2000-323191, JP-A-2001-59062, and the like. Examples of the coumarin compound include those described in JP-A Nos. 10-93118, 2002-164089, and 2004-95450, and J. Phys. Chem. C, 7224, Vol. 111 (2007). Examples of the polyene compound include the polyene compounds described in JP-A No. 2004-95450 and Chem. Commun., 4887 (2007). Examples of the indoline compound include the indoline compounds described in JP-A Nos. 2003-264010, 2004-63274, 2004-115636, 2004-200068, 2004-235052, J. Am. Chem. Soc., 12218, Vol. 126 (2004), Chem. Commun., 3036 (2003), Angew. Chem. Int. Ed., 1923, Vol. 47 (2008), and the like. Examples of the thiophene compound include those described in J. Am. Chem. Soc., 16701, Vol. 128 (2006), J. Am. Chem. Soc., 14256, Vol. 128 (2006), and the like. Examples of the cyanine dye include those described in JP-A Nos. 11-86916, 11-214730, 2000-106224, 2001-76773, and 2003-7359. Examples of the merocyanine dye include those described in JP-A Nos. 11-214731, 11-238905, 2001-52766, 2001-76775, and 2003-7360. Examples of the 9-arylxanthene compound include the 9-arylxanthene compounds described in JP-A Nos. 10-92477, 11-273754, 11-273755, and 2003-31273. Examples of the triarylmethane compound include the triarylmethane compounds described in JP-A Nos. 10-93118 and 2003-31273. Examples of the phthalocyanine compounds and the porphyrin compounds include those described in JP-A-9-199744, JP-A-10-233238, JP-A-11-204821, JP-A-11-265738, J. Phys. Chem., 2342, Vol. 91 (1987), J. Phys. Chem. B, 6272, Vol. 97 (1993), Electroanal. Chem., 31, Vol. 537 (2002), JP-A-2006-032260, and J. Porphyrins Examples of suitable phthalocyanine compounds include phthalocyanine compounds and porphyrin compounds described in Phthalocyanines, 230, Vol. 3 (1999), Angew. Chem. Int. Ed., 373, Vol. 46 (2007), and Langmuir, 5436, Vol. 24 (2008). Among these, metal complex compounds, indoline compounds, thiophene compounds, and porphyrin compounds are preferred.

[0093] <Electron transport layer> The electron transport layer refers to a layer that transports electrons generated in the photoelectric conversion layer (described later) to the electrode. For this reason, the electron transport layer is preferably disposed adjacent to the second electrode.

[0094] The shape and size of the electron transport layer are not particularly limited and can be appropriately selected depending on the purpose.

[0095] The electron transport layer may have a single layer structure or a multilayer structure in which a plurality of layers are laminated.

[0096] The electron transport layer contains an electron transport material. The electron transport material is not particularly limited and can be appropriately selected depending on the purpose, but is preferably a semiconductor material.

[0097] The semiconductor material is not particularly limited, and known materials can be used, such as elemental semiconductors and compounds having compound semiconductors. Examples of elemental semiconductors include silicon and germanium. Compound semiconductors include, for example, metal chalcogenides.

[0098] Examples of metal chalcogenides include metal oxides (oxide semiconductors), metal sulfides, metal selenides, and metal tellurides. Examples of metal oxides (oxide semiconductors) include oxides of titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium, tantalum, and the like. Examples of metal sulfides include sulfides of cadmium, zinc, lead, silver, antimony, bismuth, and the like. Examples of metal selenides include selenides of cadmium, lead, and the like. Examples of metal tellurides include tellurides of cadmium and the like. Other compound semiconductors include, for example, phosphides of zinc, gallium, indium, cadmium, etc., gallium arsenide, copper-indium-selenide, copper-indium-sulfide, and the like.

[0099] Among semiconductor materials, metal oxides (oxide semiconductors) are preferred, and at least one of titanium oxide, zinc oxide, tin oxide, and niobium oxide is more preferred, with tin oxide being even more preferred. These may be used alone or in combination of two or more. The crystal type of the semiconductor material is not particularly limited and can be appropriately selected depending on the purpose, and may be single crystal, polycrystalline, or amorphous.

[0100] The electron transport layer preferably contains at least one compound selected from the group consisting of a phosphonic acid compound, a boronic acid compound, a sulfonic acid compound, a halogenated silyl compound, and an alkoxysilyl compound on the electron transport material on the surface facing the photoelectric conversion layer. By containing these compounds on the electron transport material on the surface facing the photoelectric conversion layer, the electron transport layer is expected to control the physical properties of the interface between the electron transport layer and the photoelectric conversion layer. In other words, by coating the electron transport material on the surface facing the photoelectric conversion layer with these compounds, the interface resistance between the electron transport layer and the photoelectric conversion layer can be reduced, and smooth electron transfer can be expected. These compounds may be bonded to the electron transport material by, for example, a covalent bond or an ionic bond.

[0101] The compound is at least one of a phosphonic acid compound, a boronic acid compound, a sulfonic acid compound, a silyl halide compound, and an alkoxysilyl compound. The compound preferably contains a nitrogen atom in terms of compatibility with the photoelectric conversion layer (perovskite layer) described below.

[0102] The phosphonic acid compound is not particularly limited as long as it contains a phosphonic acid group, and can be appropriately selected depending on the purpose. Specific examples will be described later.

[0103] The boronic acid compound is not particularly limited as long as it contains a boronic acid group, and can be appropriately selected depending on the purpose. Specific examples will be described later.

[0104] The sulfonic acid compound is not particularly limited as long as it contains a sulfonic acid group, and can be appropriately selected depending on the purpose. Specific examples will be described later.

[0105] The halogenated silyl compound is not particularly limited as long as it contains a halogenated silyl group, and can be appropriately selected depending on the purpose. Specific examples will be described later.

[0106] The alkoxysilyl compound is not particularly limited as long as it contains an alkoxysilyl group, and can be appropriately selected depending on the purpose. Specific examples will be described later.

[0107] The molecular weight of the compound is not particularly limited and can be appropriately selected depending on the purpose, and may be, for example, from 100 to 500.

[0108] The compound is represented by, for example, the following general formula (X). [ka] In the general formula (X), R1 and R2 represent a hydrogen atom, an alkyl group, an aryl group, or a heterocycle, and may be the same or different. R3 represents a divalent alkylene group, a divalent aryl group, or a divalent heterocycle, and R4 represents a phosphonic acid group, a boronic acid group, a sulfonic acid group, a halogenated silyl group, or an alkoxysilyl group. R1 or R2, R3, and N may together form a ring structure.

[0109] Examples of the compound include the following compounds (X-01) to (X-56). [ka]

[0110] [ka]

[0111] [ka]

[0112] [ka]

[0113] The surface of the metal oxide is preferably coated on the electron transport layer with a compound having a substituent that reacts with the metal oxide, such as phosphonic acid, sulfonic acid, or a silyl halide group. Specific examples of the compound that coats the surface include, but are not limited to, methylphosphonic acid, phenylphosphonic acid, phenethylphosphonic acid, (1-aminoethyl)phosphonic acid, (2-aminoethyl)phosphonic acid, methanesulfonic acid, benzenesulfonic acid, 2-thienylboronic acid, methyltrichlorosilane, and n-hexyltriethoxysilane.

[0114] The average thickness of the electron transport layer is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5 nm or more and 1 μm or less, and more preferably 10 nm or more and 700 nm or less.

[0115] The surface of the electron transport layer on the photoelectric conversion layer side is preferably as smooth as possible. As an index of smoothness, the smaller the roughness factor, the better. However, in relation to the average thickness of the electron transport layer, the roughness factor of the electron transport layer on the photoelectric conversion layer side is preferably 20 or less, more preferably 10 or less. There is no particular limitation on the lower limit of the roughness factor, which can be appropriately selected depending on the purpose, and is, for example, 1 or more. The roughness factor is the ratio of the actual surface area to the apparent surface area, and is also called the Wenzel roughness factor. The actual surface area can be measured, for example, by measuring the BET specific surface area, and the roughness factor can be calculated by dividing that value by the apparent surface area.

[0116] The method for producing a thin film of the electron transport material in the electron transport layer is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include a method for forming a thin film of the electron transport material in a vacuum (vacuum film-forming method) and a wet film-forming method. Examples of vacuum film formation methods include sputtering, pulsed laser deposition (PLD), ion beam sputtering, ion-assisted deposition, ion plating, vacuum evaporation, atomic layer deposition (ALD), and chemical vapor deposition (CVD). Examples of wet film-forming methods include the sol-gel method. The sol-gel method involves producing a gel from a solution through chemical reactions such as hydrolysis, polymerization, and condensation, followed by heat treatment to promote densification. When using the sol-gel method, the method for applying the sol solution is not particularly limited and can be appropriately selected depending on the purpose. Examples include dipping, spraying, wire bar coating, spin coating, roller coating, blade coating, gravure coating, and inkjet printing. Wet printing methods include relief printing, offset printing, gravure printing, intaglio printing, rubber printing, and screen printing. The temperature during heat treatment after application of the sol solution is preferably 80°C or higher, and more preferably 100°C or higher.

[0117] The method for applying the compound onto the electron transport material is not particularly limited and can be appropriately selected depending on the purpose. For example, a method of applying a solution containing the compound onto a thin film of the electron transport material and then drying the applied solution can be mentioned. The coating method is not particularly limited and can be appropriately selected depending on the purpose. Examples include dipping, spraying, wire bar coating, spin coating, roller coating, blade coating, and gravure coating. The temperature during the drying treatment after the solution is applied is preferably 40°C or higher, more preferably 50°C or higher.

[0118] Alternatively, a press treatment may be performed after laminating an electron transport layer on the photoelectric conversion layer. By performing the press treatment, the electron transport layer and the hole transport layer are more closely attached to the photoelectric conversion layer, which may improve the power generation efficiency. The method of press treatment is not particularly limited and can be selected appropriately depending on the purpose. Examples include press molding using a flat plate, such as an IR (infrared spectroscopy) tablet molding machine, and roll press using rollers. The pressure used for pressing is 10 kgf / cm 2 More than 30kgf / cm is preferable. 2 The above is more preferable. The pressing time is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 hour or less. Heat may be applied during the pressing.

[0119] During the pressing process, a release agent may be placed between the press and the electrode. The release agent is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include fluororesins such as polytetrafluoroethylene, polychlorotrifluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, perfluoroalkoxy fluoride resin, polyvinylidene fluoride, ethylene tetrafluoroethylene copolymer, ethylene chlorotrifluoroethylene copolymer, and polyvinyl fluoride. These may be used alone or in combination of two or more.

[0120] <Passivation layer> The inverted structure photoelectric conversion element preferably further includes a passivation layer between the photoelectric conversion layer and the electron transport layer. The passivation layer preferably contains an amine compound different from the compound contained in the photoelectric conversion layer, and preferably contains a compound represented by the following general formula (6). AX...General formula (6) In the general formula (6), A represents at least one of an amino cation compound, a pyridinium cation compound, an imidazolinium cation compound, and a pyrrolidinium cation compound represented by either the following general formula (7) or the following general formula (8), and X represents a halogen ion. [ka] In the general formula (7), R1 represents any one of -H, -F, -CF3, and -OCH3, n represents 1 or 2, and X represents any one of Br and I. [ka] In the general formula (8), n represents an integer of 3 or more and 12 or less, and X represents either Br or I.

[0121] Specific examples of the general formula (7) include, but are not limited to, (E-1) to (E-12) shown below.

[0122] [ka]

[0123] Specific examples of the general formula (8) include 5-aminopentanoic acid hydroiodide, 5-aminopentanoic acid hydrobromide, 6-aminohexanoic acid hydroiodide, 6-aminohexanoic acid hydrobromide, 7-aminoheptanoic acid hydroiodide, 7-aminoheptanoic acid hydrobromide, 8-aminoheptanoic acid hydroiodide, 8-aminoheptanoic acid hydrobromide, 9-aminononanoic acid hydroiodide, 9-aminononanoic acid hydrobromide, 10-aminodecanoic acid hydroiodide, 10-aminodecanoic acid hydrobromide, 11-aminoundecanoic acid hydroiodide, 12-aminoundecanoic acid hydrobromide, 12-aminododecanoic acid hydroiodide, and 12-aminododecanoic acid hydrobromide.

[0124] The photoelectric conversion element is expected to have the passivation layer between the photoelectric conversion layer and the hole transport layer, thereby controlling the physical properties of the interface. When the photoelectric conversion layer is a perovskite layer, the compound (organic salt or inorganic salt) represented by the general formula (6) is preferably a salt different from the salt constituting the perovskite layer.

[0125] The salt is not particularly limited and can be appropriately selected depending on the purpose, but in particular when a perovskite compound is used in the photoelectric conversion layer, it is preferable that the salt contains a halogen atom, such as chlorine, iodine, or bromine, in terms of compatibility.

[0126] In particular, when a perovskite compound is used in the photoelectric conversion layer, the organic salt is preferably an amine hydrohalide salt from the viewpoint of compatibility. In particular, when a perovskite compound is used in the photoelectric conversion layer, the inorganic salt is preferably an alkali metal halide, such as lithium, sodium, potassium, rubidium, or cesium, from the viewpoint of compatibility.

[0127] The A is at least one of an amino cation compound, a pyridinium cation compound, an imidazolinium cation compound, and a pyrrolidinium cation compound represented by either of the following general formula (7) and the following general formula (8). [ka] In the general formula (7), R1 represents any one of -H, -F, -CF3, and -OCH3, n represents 1 or 2, and X represents any one of Br and I. [ka] In the general formula (8), n represents an integer of 3 or more and 12 or less, and X represents either Br or I.

[0128] Examples of X in the general formula (6) include a halogen anion such as a bromine (Br) anion and an iodine (I) anion.

[0129] The method for forming the passivation layer between the photoelectric conversion layer and the electron transport layer is not particularly limited and can be appropriately selected depending on the purpose, but for example, a method can be used in which a solution containing a compound (organic salt or inorganic salt) represented by general formula (6) is applied to the photoelectric conversion layer, followed by drying, and then forming an electron transport layer thereon. Examples of the solution include an aqueous solution, alcohol, etc. The coating method is not particularly limited and can be appropriately selected depending on the purpose. Examples include dipping, spraying, wire bar coating, spin coating, roller coating, blade coating, gravure coating, and inkjet coating. The solution may be applied by, for example, precipitating it in a supercritical fluid using carbon dioxide, etc. There is no limitation on the thickness of this layer, and it may be adsorbed as a single molecule or may be in the form of islands with no continuity. The temperature during the drying treatment after the solution is applied is not particularly limited and can be appropriately selected depending on the purpose. The average thickness of the passivation layer is preferably 0.5 nm or more and 100 nm or less, and more preferably 1 nm or more and 50 nm or less. Furthermore, the compound (organic salt or inorganic salt) represented by the general formula (6) does not need to be uniformly distributed at the interface between the photoelectric conversion layer and the hole transport layer. For example, it may be present in multiple localized regions (e.g., island-like). Furthermore, when the photoelectric conversion layer is a perovskite layer, the perovskite compound may be distributed within the perovskite layer or the hole transport layer by reacting the perovskite compound with a hole transport material of the hole transport layer. In other words, it is sufficient that there is a region in which the compound (organic salt or inorganic salt) represented by the general formula (6) is present between the perovskite layer in which the compound (organic salt or inorganic salt) is not present and the hole transport layer in which the organic salt and inorganic salt are not present.

[0130] <Second electrode> The second electrode is not particularly limited and can be appropriately selected depending on the purpose. In one embodiment, the second electrode preferably contains metal nanowires, which makes both the first electrode and the second electrode transparent and improves the infrared light transmittance of the photoelectric conversion element. The second electrode can be formed on the electron transport layer. The second electrode does not necessarily require a support if it has a structure that maintains sufficient strength and airtightness. The second electrode can be formed by coating on the electron transport layer by a suitable method such as coating, laminating, vapor deposition, CVD, or pasting, depending on the type of material used and the type of electron transport layer.

[0131] The structure of the second electrode is not particularly limited and can be appropriately selected depending on the purpose, and may be a single-layer structure or a structure in which multiple materials are laminated.

[0132] The material for the second electrode is not particularly limited as long as it is conductive and can be appropriately selected depending on the purpose. Examples include transparent conductive metal oxides, carbon, and metals.

[0133] Examples of transparent conductive metal oxides include indium tin oxide (hereinafter referred to as "ITO"), fluorine-doped tin oxide (hereinafter referred to as "FTO"), antimony-doped tin oxide (hereinafter referred to as "ATO"), niobium-doped tin oxide (hereinafter referred to as "NTO"), aluminum-doped zinc oxide (hereinafter referred to as "AZO"), indium zinc oxide, and niobium titanium oxide. Examples of carbon include carbon black, carbon nanotubes, graphene, and fullerene. Examples of metals include gold, silver, aluminum, nickel, indium, tantalum, and titanium. These may be used alone or in combination of two or more. Among these, transparent conductive metal oxides with high transparency are preferred, and ITO, FTO, ATO, NTO, and AZO are more preferred.

[0134] The average thickness of the second electrode is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5 nm to 100 μm, more preferably 50 nm to 10 μm. When the second electrode is made of carbon or metal, the average thickness of the second electrode is preferably set to an average thickness that ensures light transmission.

[0135] The second electrode can be formed by a known method such as die coating, spin coating, sputtering, vapor deposition, or spraying.

[0136] <Sealing member> The photoelectric conversion element can effectively use a sealing member that can shield at least the electron transport layer and the hole transport layer from the external environment of the photoelectric conversion element. In other words, in this embodiment, it is preferable that the photoelectric conversion element further includes a sealing member that shields the photoelectric conversion layer from the external environment of the photoelectric conversion element. Any conventionally known material can be used as the sealing member as long as it can reduce the intrusion of excess moisture, oxygen, etc. from the external environment into the sealed interior. The sealing member also has the effect of preventing mechanical damage caused by pressure from the outside, and any conventionally known material can be used as long as it can achieve this effect.

[0137] Sealing methods can be broadly divided into "frame sealing," in which a sealing material is applied to the periphery of the power generation area, which consists of the photoelectric conversion layer of the photoelectric conversion element, and then bonded to the second substrate, and "surface sealing," in which a sealing material is applied to the entire power generation area and then bonded to the second substrate. The former, "frame sealing," allows for the creation of a hollow space inside the seal, making it possible to appropriately adjust the amount of moisture and oxygen inside the seal. Furthermore, since the second electrode does not come into contact with the sealing material, it has the effect of reducing the impact of electrode peeling. On the other hand, the latter, "surface sealing," is excellent at preventing the intrusion of excess water and oxygen from the outside. Furthermore, the large adhesive surface area with the sealing material provides high sealing strength, making it particularly suitable when a flexible substrate is used for the first substrate.

[0138] The type of the sealing member is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include curable resins, low-melting-point glass resins, etc. The curable resin is not particularly limited as long as it is a resin that is cured by light or heat, and can be appropriately selected depending on the purpose, and among them, acrylic resins and epoxy resins are preferably used.

[0139] The cured acrylic resin may be any known material as long as it is a cured product of a monomer or oligomer having an acrylic group in the molecule. The cured epoxy resin may be any known material as long as it is a cured product of a monomer or oligomer having an epoxy group in the molecule. Examples of the epoxy resin include a water-dispersed type, a solventless type, a solid type, a heat-curing type, a curing agent mixed type, and an ultraviolet-curing type. Among these, the heat-curing type and the ultraviolet-curing type are preferred, and the ultraviolet-curing type is more preferred. Even in the case of an ultraviolet-curing type, heating can be performed, and it is preferred to perform heating even after ultraviolet curing. Examples of the epoxy resin include bisphenol A type, bisphenol F type, novolac type, cyclic aliphatic type, long-chain aliphatic type, glycidyl amine type, glycidyl ether type, glycidyl ester type, etc. These may be used alone or in combination of two or more types.

[0140] The epoxy resin is preferably mixed with a curing agent and various additives as required. The curing agent is classified into amine-based, acid anhydride-based, polyamide-based and other curing agents, and is appropriately selected depending on the purpose. Examples of the amine-based curing agent include aliphatic polyamines such as diethylenetriamine and triethylenetetramine, and aromatic polyamines such as metaphenylenediamine, diaminodiphenylmethane and diaminodiphenylsulfone. Examples of the acid anhydride curing agent include phthalic anhydride, tetrahydrophthalic anhydride and hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, pyromellitic anhydride, HET anhydride, and dodecenyl succinic anhydride. Examples of the other curing agents include imidazoles, polymercaptans, etc. These may be used alone or in combination of two or more.

[0141] Examples of the additives include a filler, a gap agent, a polymerization initiator, a desiccant (moisture absorbent), a curing accelerator, a coupling agent, a flexibilizing agent, a colorant, a flame retardant aid, an antioxidant, an organic solvent, etc. Among these, the filler, the gap agent, the curing accelerator, the polymerization initiator, and the desiccant (moisture absorbent) are preferred, and the filler and the polymerization initiator are more preferred.

[0142] The filler is effective in suppressing the intrusion of moisture and oxygen, and also has the effects of reducing volumetric shrinkage during curing, reducing the amount of outgassing during curing or heating, improving mechanical strength, and controlling thermal conductivity and fluidity, making it extremely effective in maintaining stable output in various environments. In particular, the output characteristics and durability of a photoelectric conversion element are not simply affected by the intrusion of moisture and oxygen, but are also affected by the outgassing generated during curing or heating of the sealing member. In particular, the outgassing generated during heating has a significant impact on output characteristics during storage in a high-temperature environment. In this case, by incorporating a filler, gap agent, or desiccant into the sealing material, these materials themselves can suppress the penetration of moisture and oxygen, and the amount of sealing material used can be reduced, thereby achieving the effect of reducing outgassing. This is effective not only during curing, but also when the photoelectric conversion element is stored in a high-temperature environment.

[0143] The filler is not particularly limited and can be appropriately selected depending on the purpose, and preferred examples include crystalline or amorphous inorganic fillers such as silica, talc, alumina, aluminum nitride, silicon nitride, calcium silicate, calcium carbonate, etc. These may be used alone or in combination of two or more. The average primary particle size of the filler is preferably 0.1 μm to 10 μm, more preferably 1 μm to 5 μm. When the amount added is within the preferred range, the effect of suppressing the penetration of moisture and oxygen can be sufficiently obtained, the viscosity becomes appropriate, and it is also effective in improving adhesion to the substrate and defoaming properties, and in controlling the width of the sealing member and workability.

[0144] The content of the filler is preferably 10 parts by mass or more and 90 parts by mass or less, and more preferably 20 parts by mass or more and 70 parts by mass or less, relative to 100 parts by mass of the total amount of the sealing member. When the content of the filler is within the above range, a sufficient effect of suppressing the penetration of moisture and oxygen is obtained, the viscosity is appropriate, and adhesion and workability are also good.

[0145] The gap agent, also called a gap control agent or spacer agent, enables the gap of the sealing member to be controlled. For example, when a sealing member is applied onto a first substrate or a first electrode, and a second substrate is placed thereon for sealing, the gap of the sealing member is made equal to the size of the gap agent by mixing the gap agent into the epoxy resin, and therefore the gap of the sealing member can be easily controlled. Any known material can be used as the gap agent as long as it is granular, has a uniform particle size, and has high solvent resistance and heat resistance. Materials with high affinity for epoxy resin and spherical particle shape are preferred. Specific examples include glass beads, silica microparticles, and organic resin microparticles. These may be used alone or in combination of two or more. The average particle size of the gap agent can be selected according to the gap of the sealing member to be set, but is preferably 1 μm or more and 100 μm or less, and more preferably 5 μm or more and 50 μm or less.

[0146] Examples of the polymerization initiator include a thermal polymerization initiator that uses heat to initiate polymerization, and a photopolymerization initiator that uses light to initiate polymerization. The thermal polymerization initiator is a compound that generates active species such as radicals or cations when heated, and specifically, an azo compound such as 2,2'-azobisbutyronitrile (AIBN), a peroxide such as benzoyl peroxide (BPO), etc. The thermal cationic polymerization initiator is, for example, a benzenesulfonate ester or an alkylsulfonium salt. On the other hand, in the case of an epoxy resin, a photocationic polymerization initiator is preferably used as the photopolymerization initiator. When the epoxy resin is mixed with the photocationic polymerization initiator and irradiated with light, the photocationic polymerization initiator decomposes to generate a strong acid, which then induces polymerization of the epoxy resin, thereby progressing the curing reaction. The photocationic polymerization initiator has the effects of causing little volume shrinkage during curing, not being inhibited by oxygen, and having high storage stability. Examples of the photocationic polymerization initiator include aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts, methacerone compounds, and silanol-aluminum complexes.

[0147] Photoacid generators that generate acid upon irradiation with light can also be used. Photoacid generators act as acids that initiate cationic polymerization, and examples of such photoacid generators include ionic onium salts, such as sulfonium salts and iodonium salts, which are composed of a cation moiety and an anion moiety. These may be used alone or in combination of two or more. The amount of the polymerization initiator added may vary depending on the material used, but is preferably 0.5 parts by mass to 10 parts by mass, and more preferably 1 part by mass to 5 parts by mass, relative to 100 parts by mass of the total amount of the sealing member. By adding an amount within the above range, curing proceeds appropriately, the amount of uncured material remaining can be reduced, and excessive outgassing can be prevented, which is effective.

[0148] The desiccant is also called a moisture absorbent, and is a material that has the function of physically or chemically adsorbing or absorbing moisture. When the desiccant is contained in the sealing member, it is effective because it can further increase the moisture resistance and reduce the effects of outgassing in some cases. The desiccant is preferably particulate, and examples thereof include inorganic water-absorbing materials such as calcium oxide, barium oxide, magnesium oxide, magnesium sulfate, sodium sulfate, calcium chloride, silica gel, molecular sieves, and zeolite. Among these, zeolite and calcium oxide, which have a high moisture absorption capacity, are preferred. These may be used alone or in combination of two or more.

[0149] The curing accelerator is also called a curing catalyst and is used for the purpose of accelerating the curing rate, and is mainly used for thermosetting epoxy resins. Examples of the curing accelerator include tertiary amines or tertiary amine salts such as DBU (1,8-diazabicyclo(5,4,0)-undecene-7) and DBN (1,5-diazabicyclo(4,3,0)-nonene-5); imidazoles such as 1-cyanoethyl-2-ethyl-4-methylimidazole and 2-ethyl-4-methylimidazole; and phosphine or phosphonium salts such as triphenylphosphine and tetraphenylphosphonium tetraphenylborate. These may be used alone or in combination of two or more.

[0150] The coupling agent has the effect of increasing molecular bonding strength, and examples thereof include silane coupling agents, such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, N-(2-(vinylbenzylamino)ethyl)3-aminopropyltrimethoxysilane hydrochloride, and 3-methacryloxypropyltrimethoxysilane. These may be used alone or in combination of two or more.

[0151] Furthermore, epoxy resin compositions commercially available as encapsulants, sealants, or adhesives are known for the sealing member, and can be effectively used in the present embodiment. Among these, there are epoxy resin compositions developed and commercially available for use in solar cells and organic EL devices, such as TB3118, TB3114, TB3124, and TB3125F (all manufactured by ThreeBond Co., Ltd.), WorldRock5910, WorldRock5920, and WorldRock8723 (all manufactured by Kyoritsu Chemical Co., Ltd.), and WB90US(P) (manufactured by Moresco). Examples of commercially available acrylic resins include those under the trade names TB3035B and TB3035C (both manufactured by ThreeBond Co., Ltd.) and NICHIBAN UM (both manufactured by Nichiban Co., Ltd.). These sealing members can be subjected to heat treatment after being cured by irradiation with ultraviolet light or the like, which is effective in this embodiment. By performing heat treatment, it may be possible to reduce the amount of uncured components, which is effective in reducing the amount of outgassing that affects output characteristics, improving sealing performance, and improving output characteristics and their sustainability.

[0152] On the other hand, low-melting-point glass resins are applied and then baked to decompose the resin components, and then the resin is melted using an infrared laser or the like, and the glass substrate is brought into close contact with the resin to seal. At this time, the low-melting-point glass components diffuse into the metal oxide layer and are physically bonded, thereby achieving high sealing performance. Furthermore, since the resin components are eliminated, outgassing does not occur as with ultraviolet-curable resins, which is effective in improving the durability of photoelectric conversion elements. Generally, glass frits or glass pastes are commercially available, and these can be used effectively. In one embodiment, those with lower melting points are preferred.

[0153] The heat treatment temperature is not particularly limited and can be freely set depending on the sealing member used, but is preferably from 50° C. to 200° C., more preferably from 60° C. to 150° C., and even more preferably from 70° C. to 100° C. The heat treatment time is not particularly limited and can be freely set depending on the sealing member used, but is preferably from 10 minutes to 10 hours, more preferably from 20 minutes to 5 hours, and even more preferably from 30 minutes to 3 hours.

[0154] In one embodiment, a sheet-shaped sealing material can also be effectively used. Sheet-type encapsulant is a sheet on which an epoxy resin layer or a pressure-sensitive adhesive layer has been formed in advance. The sheet is made of glass or a film with high gas barrier properties, and corresponds to the second substrate. The sheet-type encapsulant is attached to the second electrode of the photoelectric conversion element and then cured, forming the encapsulant and substrate at the same time. If the resin layer formed on the sheet covers the entire surface, it becomes "surface encapsulation," but depending on the formation pattern of the resin layer, it can also become "frame encapsulation," which creates a hollow space inside the photoelectric conversion element. By incorporating oxygen into the hollow space inside the sealed region, it becomes possible to stably maintain the hole transport function of the hole transport layer for a long period of time, which may be effective in improving the durability of the photoelectric conversion element. While an oxygen concentration of more than 0% by volume in the hollow space inside the sealed region is effective, it is more preferable that the oxygen concentration be 5.0% by volume or more and 21.0% by volume or less, and even more preferable that the oxygen concentration be 10.0% by volume or more and 21.0% by volume or less.

[0155] The oxygen concentration in the hollow space can be controlled by sealing it in a glove box in which the oxygen concentration is adjusted. The oxygen concentration can be adjusted by using a gas cylinder having a specific oxygen concentration or by using a nitrogen gas generator. The oxygen concentration inside the glove box can be measured using a commercially available oxygen concentration meter or oxygen monitor. The oxygen concentration in the hollow space formed by sealing can be measured, for example, by moisture and residual gas analysis in the sealed package (IVA), atmospheric pressure ionization mass spectrometry (API-MS), etc. Specifically, the photoelectric conversion element is placed in a chamber filled with a high vacuum or an inert gas, the seal is removed in the chamber, and the gas and moisture in the chamber are analyzed by mass spectrometry to quantify all components in the gas contained in the hollow space, and the proportion of oxygen to the total can be calculated to determine the oxygen concentration.

[0156] The gas other than oxygen contained inside the sealed space is preferably an inert gas, such as nitrogen or argon. When sealing, it is preferable to control the dew point as well as the oxygen concentration inside the glove box, which is effective in improving output and durability. The dew point is defined as the temperature at which condensation begins when a gas containing water vapor is cooled. The dew point is not particularly limited, but is preferably 0° C. or lower, more preferably −20° C. or lower. The lower limit is preferably −50° C. or higher.

[0157] The method for forming the sealing member is not particularly limited and can be performed according to a known method. For example, various methods such as a dispensing method, a wire bar method, a spin coating method, a roller coating method, a blade coating method, an inkjet method, a gravure coating method, a letterpress method, an offset method, an intaglio method, a rubber plate method, and a screen printing method can be used.

[0158] Furthermore, a passivation layer may be provided between the sealing member and the second electrode. The passivation layer is not particularly limited as long as it is disposed so that the sealing member does not come into contact with the second electrode, and can be appropriately selected depending on the purpose, but aluminum oxide, silicon nitride, silicon oxide, etc. are preferably used.

[0159] <Other materials> The other members are not particularly limited and can be appropriately selected depending on the purpose.

[0160] Hereinafter, an example of a photoelectric conversion element according to this embodiment will be described with reference to the drawings. However, the present invention is not limited to this example, and for example, the number, position, shape, etc. of the following components not described in this embodiment are also included in the scope of the present invention.

[0161] FIG. 1 is a schematic diagram of an example of an inverted structure solar cell as an embodiment of a photoelectric conversion element. The solar cell 50 in FIG. 1 has a first substrate 1, a first electrode 2, a hole transport layer 3, a perovskite layer 5 which is a photoelectric conversion layer, a (dense) electron transport layer 7, and a second electrode 8. The first electrode 2 is in contact with the hole transport layer 3. The hole transport layer 3 is in contact with the perovskite layer 5. The perovskite layer 5 is in contact with the electron transport layer 7. The electron transport layer 7 is in contact with the second electrode 8.

[0162] FIG. 2 is a schematic diagram of another example of an inverted structure solar cell as an embodiment of a photoelectric conversion element. The solar cell 60 in FIG. 2 is an embodiment in which, compared to the solar cell 50 in FIG. 1, a passivation layer 6 is further provided between the perovskite layer 5 and the electron transport layer 7.

[0163] (Photoelectric conversion module) The photoelectric conversion module of this embodiment is a tandem-type photoelectric conversion module having multiple stacked photoelectric conversion elements, with adjacent photoelectric conversion elements electrically connected in series or parallel, and the photoelectric conversion element on the light-receiving surface side is a photoelectric conversion element of this embodiment in which the second electrode contains metal nanowires. The photoelectric conversion module preferably has, for example, one or more photoelectric conversion elements on a substrate, with the photoelectric conversion element of the present embodiment stacked on the light-receiving surface side, and further has a second substrate different from the aforementioned substrate, a sealing member, and other members as necessary. The photoelectric conversion module may be, for example, a solar cell module.

[0164] In the tandem photovoltaic conversion module, by using a top cell (photovoltaic conversion element on the light-receiving surface side) that combines a first electrode containing metal nanowires with a second electrode (translucent counter electrode) that also contains metal nanowires, the top cell has excellent infrared light transmittance, thereby achieving high conversion efficiency in the photovoltaic conversion module. When the number n of photoelectric conversion elements to be stacked is 3 or more, the photoelectric conversion elements of this embodiment in which the second electrode contains metal nanowires can be used as the photoelectric conversion elements from the photoelectric conversion element closest to the light-receiving surface to the (n-1)th photoelectric conversion element from the light-receiving surface side, and the one photoelectric conversion element on the opposite side from the light-receiving surface can be a known photoelectric conversion element or a photoelectric conversion element of this embodiment.

[0165] The photoelectric conversion module may be a tandem-type photoelectric conversion module in which each layer of the tandem-type photoelectric conversion element has multiple photoelectric conversion elements, or a single-layer photoelectric conversion module having multiple photoelectric conversion elements on the same plane instead of a tandem-type. The photoelectric conversion module may also be one in which the multiple photoelectric conversion elements are provided on a substrate or in the same layer, and it is preferable that the hole transport layers of at least two adjacent photoelectric conversion elements are continuous with each other, and the first electrodes, electron transport layers, and photoelectric conversion layers of at least two adjacent photoelectric conversion elements are separated by a hole transport layer. In such a photoelectric conversion module, the electron transport layer and photoelectric conversion layer are disconnected, reducing electron recombination due to diffusion, allowing the power generation efficiency to be maintained even after long-term exposure to high-intensity light.

[0166] The photoelectric conversion module can be applied to a power supply device by combining it with a circuit board or the like that controls the generated current. Examples of devices that use power supply devices include electronic desk calculators and wristwatches. Power supply devices having the photoelectric conversion module can also be applied to mobile phones, electronic organizers, electronic paper, and the like. Furthermore, power supply devices having the photoelectric conversion module of the present invention can be used as auxiliary power sources to extend the continuous operating time of rechargeable or battery-powered electrical appliances, or as power sources that can be used at night by combining them with secondary batteries, etc. Furthermore, they can also be used in IoT devices, artificial satellites, and the like as standalone power sources that do not require battery replacement or power wiring.

[0167] (solar cell module) The solar cell module of this embodiment is a tandem solar cell module, having multiple stacked photoelectric conversion elements, with adjacent photoelectric conversion elements electrically connected in series or parallel, and the photoelectric conversion element on the light-receiving surface side is the photoelectric conversion element of this embodiment, in which the second electrode contains metal nanowires. The solar cell module is similar to the photovoltaic conversion module.

[0168] Fig. 3 is a cross-sectional view showing another example of a solar cell module according to this embodiment. As shown in Fig. 3, the solar cell module 100 has a photoelectric conversion element on a first substrate 1, the photoelectric conversion element having a first electrode 2, a hole transport layer 3, a perovskite layer 5, a passivation layer 6, an electron transport layer 7, and a second electrode 8. The first electrode 2 and the second electrode 8 have paths that connect them to an output terminal. Furthermore, in the solar cell module 100, a second substrate 11 is disposed opposite the first substrate 1 so as to sandwich the photoelectric conversion element therebetween, and a sealing member 10 is disposed between the first substrate 1 and the second substrate 11. In the solar cell module 100, the first electrode 2, the hole transport layer 3, and the perovskite layer 5 in the photoelectric conversion element a having the first electrode 2a and the second electrode 8a, and the photoelectric conversion element b having the first electrode 2b and the second electrode 8b are separated by an electron transport layer 7, which is a continuous layer extending between the photoelectric conversion element a and the photoelectric conversion element b.

[0169] Fig. 4 is a cross-sectional view showing an example of the cross-sectional structure of a solar cell module of this embodiment. As shown in Fig. 4, a solar cell module 101 has a photoelectric conversion element on a first substrate 1, the photoelectric conversion element having a first electrode 2, a hole transport layer 3, a perovskite layer 5, a passivation layer 6, an electron transport layer 7, and a second electrode 8. The first electrode 2 and the second electrode 8 have paths that connect them to an output terminal. Furthermore, in the solar cell module 101, a second substrate 11 is disposed opposite the first substrate 1 so as to sandwich the photoelectric conversion element therebetween, and a sealing member 10 is disposed between the first substrate 1 and the second substrate 11. In the solar cell module 101, the first electrode 2 and the hole transport layer 3 in the photoelectric conversion element a having the first electrode 2a and the second electrode 8a, and the photoelectric conversion element b having the first electrode 2b and the second electrode 8b are separated by a perovskite layer 5 and an electron transport layer 7, which are continuous layers extending between the photoelectric conversion element a and the photoelectric conversion element b.

[0170] Fig. 5 is a cross-sectional view showing an example of the cross-sectional structure of a solar cell module according to this embodiment. As shown in Fig. 5, a solar cell module 102 has a photoelectric conversion element on a first substrate 1, the photoelectric conversion element having a first electrode 2, a hole transport layer 3, a perovskite layer 5, a passivation layer 6, an electron transport layer 7, and a second electrode 8. The first electrode 2 and the second electrode 8 have paths that connect them to an output terminal. Furthermore, in the solar cell module 102, a second substrate 11 is disposed opposite the first substrate 1 so as to sandwich the photoelectric conversion element therebetween, and a sealing member 10 is disposed between the first substrate 1 and the second substrate 11. In the solar cell module 102, the first electrode 2 and the hole transport layer 3 in the photoelectric conversion element a having the first electrode 2a and the second electrode 8a, and the photoelectric conversion element b having the first electrode 2b and the second electrode 8b are separated by a perovskite layer 5 and an electron transport layer 7, which are continuous layers extending between the photoelectric conversion element a and the photoelectric conversion element b.

[0171] Solar cell modules 100-102 are sealed by a first substrate 1, a sealing member 10, and a second substrate 11. This makes it possible to control the moisture content and oxygen concentration in the hollow space between the second electrode 8 and the second substrate 11. Controlling the moisture content and oxygen concentration in the hollow space of solar cell modules 100-102 can improve power generation performance and durability. That is, by further including a second substrate disposed opposite the first substrate so as to sandwich the photoelectric conversion element, and a sealing member disposed between the first and second substrates to seal the photoelectric conversion element, the moisture content and oxygen concentration in the hollow space can be controlled, thereby improving power generation performance and durability. The oxygen concentration in the hollow portion is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 0% or more and 21% or less, more preferably 0.05% or more and 10% or less, and even more preferably 0.1% or more and 5% or less.

[0172] Furthermore, in the solar cell modules 100 to 102, the second electrode 8 and the second substrate 11 are not in contact with each other, so that the second electrode 8 can be prevented from peeling off or being damaged.

[0173] Furthermore, the solar cell modules 100 to 102 have a through portion 15 that electrically connects the photoelectric conversion element a and the photoelectric conversion element b. In the solar cell modules 100 to 102, the second electrode 8a of the photoelectric conversion element a and the first electrode 2b of the photoelectric conversion element b are electrically connected by the through portion 15 that penetrates the electron transport layer 7, thereby connecting the photoelectric conversion element a and the photoelectric conversion element b in series. By connecting a plurality of photoelectric conversion elements in series in this way, the open circuit voltage of the solar cell module can be increased.

[0174] The through-holes 15 may penetrate the first electrode 2 and reach the first substrate 1, or may stop processing inside the first electrode 2 and not reach the first substrate 1. When the through-holes 15 are shaped as micropores that penetrate the first electrode 2 and reach the first substrate 1, if the total opening area of ​​the micropores is too large relative to the area of ​​the through-holes 15, the film cross-sectional area of ​​the first electrode 2 will decrease, increasing the resistance and possibly causing a decrease in photoelectric conversion efficiency. Therefore, the ratio of the total opening area of ​​the micropores to the area of ​​the through-holes 15 is preferably 5 / 100 or more and 60 / 100 or less.

[0175] The method for forming the through-hole is not particularly limited and can be selected appropriately depending on the purpose. Examples include sandblasting, water blasting, chemical etching, laser processing, and methods using abrasive paper. Among these, laser processing is preferred because it allows fine holes to be formed without using sand, etching, resist, etc., thereby enabling clean and reproducible processing. Another reason why laser processing is preferred is that when forming the through-hole 15, at least one of the hole transport layer 3, perovskite layer 5, passivation layer 6, electron transport layer 7, and second electrode 8 can be removed by impact peeling using laser processing. This eliminates the need for a mask during stacking, and allows for the removal of the material forming the photoelectric conversion element and the formation of the through-hole to be easily performed simultaneously.

[0176] Here, the perovskite layer in photoelectric conversion element a and the perovskite layer in photoelectric conversion element b may be separated or extended. When separated, the distance is preferably 1 μm to 100 μm, more preferably 5 μm to 50 μm. When the distance between the perovskite layer in photoelectric conversion element a and the perovskite layer in photoelectric conversion element b is 1 μm to 100 μm, the porous titanium oxide layer and the perovskite layer are disconnected, reducing electron recombination due to diffusion, making it possible to maintain power generation efficiency even after prolonged exposure to high-intensity light. That is, in at least two adjacent photoelectric conversion elements, when the distance between the electron transport layer and perovskite layer in one photoelectric conversion element and the electron transport layer and perovskite layer in the other photoelectric conversion element is 1 μm to 100 μm, it is possible to maintain power generation efficiency even after prolonged exposure to high-intensity light. In at least two adjacent photoelectric conversion elements, the distance between the electron transport layer and perovskite layer in one photoelectric conversion element and the electron transport layer and perovskite layer in another photoelectric conversion element refers to the shortest distance between the outer peripheries (ends) of the electron transport layer and perovskite layer in each photoelectric conversion element.

[0177] The solar cell module of the present embodiment can be applied to a power supply device by combining it with a circuit board or the like that controls the generated current. Examples of devices that use power supply devices include electronic desk calculators and wristwatches. Power supply devices having the photoelectric conversion element of the present embodiment can also be applied to mobile phones, electronic organizers, electronic paper, and the like. Furthermore, power supply devices having the photoelectric conversion element of the present embodiment can be used as auxiliary power sources for extending the continuous use time of rechargeable or battery-powered electrical appliances, or as power sources that can be used at night or other times by combining them with secondary batteries. Furthermore, they can also be used in IoT devices, artificial satellites, and the like as standalone power sources that do not require battery replacement or power wiring.

[0178] (electronic equipment) The electronic device of this embodiment includes at least one of the photoelectric conversion element and photoelectric conversion module of this embodiment, and a device that operates using power generated by photoelectric conversion by at least one of the photoelectric conversion element and photoelectric conversion module, and may further include other devices as necessary. In addition, the electronic device of this embodiment includes at least one of the photoelectric conversion element and photoelectric conversion module of this embodiment, a storage battery capable of storing the electricity generated by photoelectric conversion by at least one of the photoelectric conversion element and photoelectric conversion module, and a device that operates using the electricity stored in the storage battery, and may further include other devices as necessary.

[0179] (Power supply module) The power supply module of this embodiment includes at least one of the photoelectric conversion element and the photoelectric conversion module of this embodiment, a power supply integrated circuit (power supply IC, Integrated Circuit), and may further include other devices as necessary.

[0180] (solar water heater) The solar water heater of this embodiment has a heat collection section that receives and collects heat from sunlight, a hot water storage tank that stores hot water heated by the heat collection section, and a photoelectric conversion element of this embodiment, the second electrode of which contains metal nanowires, on the light-receiving surface side of the heat collection section, and may further have other components such as a liquid delivery pipe, an exterior, and a storage battery, as necessary.

[0181] The solar water heater main body having the heat collecting section and the hot water storage tank is not particularly limited, and any known solar water heater can be appropriately selected depending on the purpose. There are also no particular restrictions on components such as the liquid supply pipe that supplies water to the heat collection unit, the liquid supply pipe that supplies heated hot water from the heat collection unit to the hot water storage tank, the liquid supply pipe that supplies hot water from the hot water storage tank to an external device, and the exterior that arranges and secures these components, and known solar water heater components can be selected appropriately depending on the purpose.

[0182] The solar water heater of this embodiment has a photoelectric conversion element of this embodiment, in which the second electrode contains metal nanowires, on the light-receiving surface side of the heat collection unit. The photoelectric conversion element converts light energy into electrical energy, and the photoelectric conversion element has high infrared light transmittance, so that the transmitted infrared light can be collected and efficiently used to heat water. In addition, the heat generated by the photoelectric conversion element itself can be used to heat water. This contributes to improving the efficiency of the solar water heater. Furthermore, since the solar water heater has a storage battery that can store the electricity generated by the photoelectric conversion of the photoelectric conversion element, the generated electricity can be used to drive the solar water heater main body at the required time. [Example]

[0183] EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to the examples exemplified here.

[0184] <Synthesis example> <<Synthesis of styrene derivatives>> 4-Chloromethylstryrene (Tokyo Chemical Industry Co., Ltd., 25 g) and triphenylphosphine (Tokyo Chemical Industry Co., Ltd., 45.1 g) were placed in a 300 ml four-neck flask, 50 ml of toluene was added, and the mixture was refluxed and stirred for 2 hours. After cooling, ethyl acetate was added and the mixture was filtered. 45.1 g of a white solid powder of a styrene derivative having the following structure was obtained. [ka]

[0185] <<Synthesis of pyridine derivative 1>> 4,4'-((4-Bromophenyl)azanediyl)dibenzaldehyde (BLD-pharm, 1.14 g), 4-Pyridylbononic acid (Tokyo Chemical Industry Co., Ltd., 0.55 g), and potassium carbonate (Kanto Chemical Co., Ltd., 0.42 g) were dissolved in tetrahydrofuran / methanol (30 ml / 30 ml) and stirred at room temperature under argon. Tetrakis(triphenylphosphine)palladium(0) (Tokyo Chemical Industry Co., Ltd., 0.173 g) was added, and the mixture was refluxed and stirred for 4 hours. The mixture was extracted with dichloromethane, filtered, and washed. Column purification was performed using ethyl acetate / dichloromethane (3 / 2 vol) to obtain 1.15 g of a clear liquid, pyridine derivative 1, having the following structure.

[0186] [ka]

[0187] [ka]

[0188] <Synthesis Example 1: Synthesis example of compound No. 1> Pyridine derivative 1 (1.15 g) and styrene derivative (2.74 g) were dissolved in 100 ml of dehydrated dimethylformamide, and potassium tert-butoxide (Kanto Chemical Co., Ltd., 0.8 g) was added under argon gas at 3-5°C. The mixture was stirred at room temperature for 2 hours. The mixture was neutralized with acetic acid and extracted with dichloromethane. After concentration under reduced pressure, column purification was performed using dichloromethane / ethyl acetate (1 / 1 vol). 0.85 g of compound No. 1 having the following structure was obtained.

[0189] The obtained compound No. 1 was subjected to FT-IR measurement using a Fourier transform infrared spectrometer (FT-IR, device name: IRTracer-100, manufactured by Shimadzu Corporation). The IR spectrum shown in FIG. 6 was obtained, and it was confirmed that the desired compound No. 1 had been obtained.

[0190] [ka]

[0191] Example 1 <Fabrication of inverted solar cells> A film (15 Ω / sq, transmittance 80%) of silver nanowires (TranDuctive N15, manufactured by GenesInk) was formed on a glass substrate as a first substrate by die coating, to form a first electrode on the first substrate.

[0192] Next, a chlorobenzene solution (10 mg / ml) of Compound No. 1 as a hole transport material was applied to the first electrode by spin coating, and then heated and dried for 20 minutes at 200° C. The average thickness of the hole transport layer was adjusted to 10 nm to 40 nm.

[0193] Next, lead(II) iodide (0.5306 g), lead(II) bromide (0.0736 g), methylamine bromide (0.0224 g), and formamidine iodide (0.1876 g) were added to N,N-dimethylformamide (0.8 ml) and dimethyl sulfoxide (0.2 ml). The mixture was heated and stirred at 60°C. The resulting solution was then applied to the hole transport layer using a spin coating method, while chlorobenzene (0.3 ml) was added to form a perovskite film. The resulting solution was then dried at 150°C for 30 minutes to form a perovskite layer. The average thickness of the perovskite layer was adjusted to 200 nm to 350 nm.

[0194] Next, a chlorobenzene solution (10 mg / ml) of phenyl C61 butyric acid methyl ester (PCBM, manufactured by Frontier Carbon, E100) was spin-coated to form a film with an average thickness of 30 nm, and the film was dried by heating at 120°C for 3 minutes to form an electron transport layer. Finally, a silver nanowire (GenesInk, TranDuctive N15) was die-coated to form a film (15 Ω / sq, transmittance 80%) as the second electrode. In this way, the inverted solar cell shown in Figure 1 was obtained.

[0195] <Evaluation of infrared light transmittance> The transmittance of the first electrode made of the first substrate and metal nanowires produced in Example 1 at wavelengths of 400 nm to 1600 nm was measured using a spectrophotometer (device name: UV-1280, manufactured by Shimadzu Corporation). For comparison, the transmittance was measured in the same manner using an ITO glass substrate (manufactured by Geomatec Co., Ltd.) with a resistance value of 10 Ω / sq. The results are shown in Figure 7. In FIG. 7, the horizontal axis represents wavelength, the vertical axis represents transmittance (%), the solid line represents the first electrode and first substrate in Example 1, and the dashed line represents the ITO glass substrate for comparison.

[0196] The results in Figure 6 show that the transmittance is superior to that of an ITO glass substrate used for comparison, particularly in the infrared region (from a wavelength of 800 nm, which is not absorbed by perovskite solar cells, to a wavelength of 1400 nm, which is absorbed by CIS solar cells).

[0197] <Evaluation of light resistance> <<Conversion efficiency (evaluation of solar cell characteristics)>> The light resistance of the obtained solar cell was evaluated based on the maintenance rate of the conversion efficiency after the light resistance test. First, the obtained solar cell was measured using a solar simulator (SS-80XIL manufactured by Eiko Seiki Co., Ltd.) at AM1.5G and 100 mW / cm 2 The current-voltage characteristics were measured using a solar cell evaluation system (NF Corporation, product name: As-510-PV03) while irradiating light under the conditions. The conversion efficiency η (%) of the solar cell characteristics (initial characteristics) was calculated from the obtained current-voltage curve.

[0198] <<Light resistance (retention rate of conversion efficiency after light resistance test)>> The initial photoelectric conversion element was subjected to 500 hours of continuous irradiation (AM1.5, 100mW / cm 2The conversion efficiency retention rate ηx (%) after the light resistance test was calculated using the following formula: ηx / η (%) and evaluated based on the following criteria. The results are shown in Table 1. -Evaluation criteria- 〇: The conversion efficiency after the light resistance test is maintained at 80% or more, and the light resistance is excellent. △: The retention rate of conversion efficiency after the light resistance test is 60% or more and less than 80%, which is within the practical range. ×: The retention rate of conversion efficiency after the light resistance test is less than 60%, which is outside the practical range.

[0199] <Evaluation of heat resistance> <<Heat resistance (retention rate of conversion efficiency after heat resistance test)>> The initial photoelectric conversion element was subjected to a durability test in which it was stored at 90°C for 500 hours, and the retention rate of conversion efficiency after the durability test, ηx (%), was calculated using the following formula: ηx / η (%) and evaluated based on the following criteria. The results are shown in Table 1. -Evaluation criteria- 〇: The conversion efficiency after heat resistance testing is maintained at 80% or more, demonstrating excellent heat resistance. △: The retention rate of conversion efficiency after the heat resistance test is 60% or more and less than 80%, which is within the practical range. ×: The retention rate of conversion efficiency after the heat resistance test is less than 60%, which is outside the practical range.

[0200] Examples 2 to 9 Inverted structure solar cells of Examples 2 to 9 were produced and evaluated in the same manner as in Example 1, except that the hole transport material in Example 1 was changed to the hole transport material shown in Table 1. The results are shown in Table 1.

[0201] Example 10 An inverted structure solar cell of Example 10 shown in Figure 2 was manufactured and evaluated in the same manner as in Example 1, except that a 1 mM solution of 5-aminopentanoic acid hydroiodide as the compound represented by general formula (8) was applied by spin coating onto the perovskite layer of Example 1 to form a passivation layer containing the compound represented by general formula (8). The results are shown in Table 1.

[0202] Example 11 The silver nanowires (TranDuctive N15, manufactured by GenesInk) in Example 1 were coated with a conductive polymer, PEDOT / PSS (CLEVIOS, manufactured by Heraeus). TM An inverted structure solar cell of Example 11 was manufactured and evaluated in the same manner as in Example 1, except that HTL Solar 3) was added and mixed so that the mass ratio of AgNW:PEDOT / PSS was 4:1. The results are shown in Table 1.

[0203] Example 12 An inverted structure solar cell of Example 12 was manufactured and evaluated in the same manner as in Example 1, except that the material for the perovskite layer in Example 1 was changed to a material obtained by adding lead (II) iodide (2.5471 g), lead (II) bromide (0.3578 g), methylamine bromide (0.1092 g), and formamidine iodide (0.9501 g) to N,N-dimethylformamide (4 ml) and dimethyl sulfoxide (1 ml). The results are shown in Table 1.

[0204] Example 13 An inverted structure solar cell of Example 13 was manufactured and evaluated in the same manner as in Example 1, except that the material for the perovskite layer in Example 1 was changed to a material obtained by adding lead (II) iodide (2.1437 g), lead (II) bromide (0.4955 g), formamidine iodide (0.1548 g), and cesium iodide (1.325 g) to N,N-dimethylformamide (4 ml) and dimethyl sulfoxide (1 ml). The results are shown in Table 1.

[0205] (Comparative Example 1) An inverted structure solar cell of Comparative Example 1 was manufactured and evaluated in the same manner as in Example 1, except that the hole transporting material in Example 1 was changed to [2-(3,6-dibromo-9H-carbazol-9-yl)ethyl]phosphonic acid (Br-2PACz, manufactured by Tokyo Chemical Industry Co., Ltd.) having the following structure. The results are shown in Table 1. [ka]

[0206] (Comparative Example 2) An inverted structure solar cell of Comparative Example 2 was manufactured and evaluated in the same manner as in Example 1, except that the hole transport material in Example 1 was changed to poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA, manufactured by Sigma-Aldrich, where n is an integer) represented by the following general formula. The results are shown in Table 1. [ka]

[0207] (Comparative Example 3) An inverted structure solar cell of Comparative Example 3 was produced and evaluated in the same manner as in Example 1, except that the hole transport material in Example 1 was changed to poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonic acid) (PEDOT / PSS represented by the following general formula, manufactured by Sigma-Aldrich, where n, x, and y each independently represent an integer.) The results are shown in Table 1. [ka]

[0208] Comparative Example 4 An inverted structure solar cell of Comparative Example 4 was produced and evaluated in the same manner as in Example 1, except that the hole transporting material in Example 1 was changed to Compound A having the following structure. The results are shown in Table 1. [ka]

[0209] [Table 1]

[0210] The results in Table 1 show that in Examples 1 to 13, the hole transport material had a polymerizable group, and the hole transport layer contained a polymer of the hole transport material, which provided good filling and coverage between the silver nanowires, protecting the perovskite layer material from halogen ion diffusion and providing light resistance and heat resistance. In particular, in Examples 1 to 6, it was found that the hole transport material had a pyridine group, which is presumably responsible for the passivation effect achieved by coordination with the unpaired electron of the lead atom in the perovskite layer, resulting in high light resistance.

[0211] Example 14: Manufacturing of solar cell module The solar cell of Example 1 was stacked on top (light-receiving surface side) of a single crystal silicon solar cell (KXOB25-04X3F, manufactured by Anysolar) and electrically connected in series to produce a tandem solar cell module of Example 14. The obtained solar cell module was used to measure AM1.5, 100mW / cm 2 The output power was evaluated at 30.8 mW.

[0212] (Comparative Example 5) The solar cell module of Comparative Example 5 was formed by stacking only the monocrystalline silicon solar cell without stacking the solar cell of Example 1 on the upper side (light-receiving side) of a monocrystalline silicon solar cell (KXOB25-04X3F, manufactured by Anysolar Corporation), and output evaluation was carried out in the same manner as in Example 14. The obtained output was 22.0 mW.

[0213] (Comparative Example 6) A tandem solar cell module of Comparative Example 6 was produced in the same manner as in Example 14, except that in the solar cell of Example 1 used in the solar cell module of Example 14, the first substrate and first electrode were changed to an ITO glass substrate (manufactured by Geomatec Co., Ltd.) having a resistance value of 10 Ω / sq, and output evaluation was carried out in the same manner as in Example 14. The obtained output was 27.5 mW.

[0214] The results of Example 14 and Comparative Examples 5 and 6 show that, compared to a single-layer monocrystalline silicon solar cell (Comparative Example 5) and a perovskite solar cell module using an ITO glass substrate (Comparative Example 6), the perovskite solar cell module using silver nanowires with high infrared light transmittance (Example 14) can obtain higher output when evaluated as a tandem solar cell module.

[0215] For example, aspects of the present invention are as follows. <1> A photoelectric conversion element having, in this order, a first substrate, a first electrode, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode, the first electrode contains metal nanowires; The photoelectric conversion element is characterized in that the hole transport layer contains a polymer of a hole transport material. <2> The hole transport material has a pyridine group. <1> The photoelectric conversion element is described in <3> The compound represented by the following general formula (1): <2> The photoelectric conversion element is described in [ka] In the general formula (1), X represents an aromatic hydrocarbon group which may have a substituent, and Y represents a pyridine group which may have a substituent. <4> X in the general formula (1) is selected from the group consisting of: 1 and R 2 each independently represents a hydrogen atom or a methyl group, [ka] Y in the general formula (1) is selected from the group consisting of: 3 and R 4 each independently represents a hydrogen atom or a methyl group. <3> The photoelectric conversion element is described in [ka] <5> The metal nanowires are silver nanowires. <1> from <4> The photoelectric conversion element according to any one of the above items. <6> The photoelectric conversion layer contains a perovskite compound represented by the following general formula (5): <1> from <5> The photoelectric conversion element according to any one of the above items. X α Y β Z γ ...General formula (5) In general formula (5), the ratio of α:β:γ is 3:1:1, β and γ represent integers greater than 1, X represents a halogen atom, Y represents an organic compound having an amino group, and Z represents a metal ion. <7> The photoelectric conversion layer contains at least one of methylamine, ethylamine, n-butylamine, and formamidine. <1> from <6> The photoelectric conversion element according to any one of the above items. <8> a passivation layer is provided between the photoelectric conversion layer and the electron transport layer; The passivation layer contains an amine compound different from the compound contained in the photoelectric conversion layer. <1> from <7> The photoelectric conversion element according to any one of the above items. <9> The second electrode contains metal nanowires. <1> from <8> The photoelectric conversion element according to any one of the above items. <10> the first electrode further contains a conductive polymer; the mass ratio (A / B) of the metal nanowires (A) to the conductive polymer (B) in the first electrode is 2 or more and 6 or less; <1> from <9> The photoelectric conversion element according to any one of the above items. <11> A plurality of photoelectric conversion elements are stacked, Adjacent photoelectric conversion elements are electrically connected in series or in parallel, A solar cell module, wherein the photoelectric conversion element on the light-receiving surface side is the photoelectric conversion element according to claim 9. <12> a heat collecting section that receives sunlight and collects heat; a hot water storage tank that stores the hot water heated by the heat collecting unit; The light receiving surface side of the heat collecting portion is <9> or <10> or the photoelectric conversion element described in <11> and the tandem solar cell according to claim 1.

[0216] The aforementioned <1> from <10> The photoelectric conversion element according to any one of <11> The solar cell module according to <12> The solar water heater described in the above can solve the above-mentioned problems in the prior art and achieve the object of the present invention. [Explanation of symbols]

[0217] 1 First board 2 First electrode 3. Hole transport layer 5 Perovskite Layer 6 Passivation Layer 7 Electron transport layer 8 Second electrode 50, 60 solar cells [Prior art documents] [Non-patent literature]

[0218] [Non-Patent Document 1] Bowen Gao and Jing Meng,Solar Energy,vol.230,p.598-604(2021)

Claims

1. A photoelectric conversion element having, in this order, a first substrate, a first electrode, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode, the first electrode contains metal nanowires; The photoelectric conversion element, wherein the hole transport layer contains a polymer of a hole transport material.

2. 2. The photoelectric conversion element according to claim 1, wherein the hole transporting material has a pyridine group.

3. 3. The photoelectric conversion element according to claim 2, wherein the hole transporting material is represented by the following general formula (1): 【Chemical Formula 1】 In the general formula (1), X represents an aromatic hydrocarbon group which may have a substituent, and Y represents a pyridine group which may have a substituent.

4. X in the general formula (1) is selected from the group consisting of: １ and R ２ each independently represents a hydrogen atom or a methyl group, 【Chemistry 2】 Y in the general formula (1) is selected from the group consisting of: ３ and R ４ The photoelectric conversion element according to claim 3 , wherein each independently represents a hydrogen atom or a methyl group. 【Chemistry 3】

5. The photoelectric conversion element according to claim 1 or 2, wherein the metal nanowires are silver nanowires.

6. 3. The photoelectric conversion element according to claim 1, wherein the photoelectric conversion layer contains a perovskite compound represented by the following general formula (5): X α Y β Z γ ・・・General formula (5) In general formula (5), the ratio of α:β:γ is 3:1:1, β and γ represent integers greater than 1, X represents a halogen atom, Y represents an organic compound having an amino group, and Z represents a metal ion.

7. 3. The photoelectric conversion element according to claim 1, wherein the photoelectric conversion layer contains at least one of methylamine, ethylamine, n-butylamine, and formamidine.

8. a passivation layer is provided between the photoelectric conversion layer and the electron transport layer; 3. The photoelectric conversion element according to claim 1, wherein the passivation layer contains an amine compound different from a compound contained in the photoelectric conversion layer.

9. The photoelectric conversion element according to claim 1 , wherein the second electrode contains metal nanowires.

10. the first electrode further contains a conductive polymer; 3. The photoelectric conversion element according to claim 1, wherein a mass ratio (A / B) of the metal nanowires (A) to the conductive polymer (B) in the first electrode is 2 or more and 6 or less.

11. A plurality of photoelectric conversion elements are stacked, Adjacent photoelectric conversion elements are electrically connected in series or in parallel, A solar cell module, wherein the photoelectric conversion element on the light-receiving surface side is the photoelectric conversion element according to claim 9.

12. a heat collecting section that receives sunlight and collects heat; a hot water storage tank that stores the hot water heated by the heat collecting unit; A solar water heater comprising: the photoelectric conversion element according to claim 9 on the light-receiving surface side of the heat collecting portion.

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