Photoelectric conversion element

Abstract

To provide a photoelectric conversion element that exhibits excellent photoelectric conversion characteristics and improved durability. [Solution] A photoelectric conversion element 10 in one aspect of the present invention has a structure in which a first electrode 12, a hole transport layer 13, a photoelectric conversion layer 14, an electron transport layer 15, and a second electrode 16 are stacked in this order. The photoelectric conversion layer 14 contains a perovskite structure. The hole transport layer 13 contains a compound represented by chemical formula (1). TIFF2026061681000032.tif68170

Description

Technical Field

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

Background Art

[0002] In recent years, as clean energy, solar power generation has attracted attention, and the development of solar cells has been progressing. As one of them, as a next-generation solar cell that can be manufactured at low cost, a solar cell using a perovskite material as a light absorption layer has rapidly attracted attention. For example, in Non-Patent Document 1, a solution-type solar cell using a perovskite material as a light absorption layer has been reported. Also, in Non-Patent Document 2, it has been reported that a solid-type perovskite solar cell exhibits high efficiency.

Prior Art Documents

Non-Patent Documents

[0003] <00C0087>

Non-Patent Document 1

Non-Patent Document 2

[0007] According to the present invention, a photoelectric conversion element is provided that exhibits excellent photoelectric conversion characteristics and has improved durability. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing the cross-sectional structure of the photoelectric conversion element 10 according to the embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described in detail below. In this specification, unless otherwise specified, the notation "a~b" in the description of numerical ranges means a or greater and b or less. Next, the present invention will be described in detail with reference to examples. However, the present invention is not limited to the following description. Also, when describing with reference to the drawings, the dimensions and other details in each drawing may differ from those in reality for convenience.

[0010] In this specification, "on top of" or "on a surface" may refer to a state of direct contact with the top of or on a surface, or it may refer to a state of contact via other components, etc.

[0011] The photoelectric conversion element of the embodiment includes, for example, a power generation unit, the power generation unit each including a first electrode, a photoelectric conversion layer, and a second electrode, and the first electrode, the photoelectric conversion layer, and the second electrode are stacked in this order. The photoelectric conversion element of the embodiment may further include a support (also referred to as a substrate, base material, etc.). Here, between the first electrode and the photoelectric conversion layer, other components other than the first electrode, the photoelectric conversion layer, the second electrode, and the support (hereinafter sometimes simply referred to as "other components") may be included. Also, other components may be included between the photoelectric conversion layer and the second electrode. Examples of the other components include an electron transport layer, a hole transport layer, etc.

[0012] [Photoelectric conversion element] Figure 1 is a schematic diagram showing the cross-sectional structure of a photoelectric conversion element 10 according to an embodiment. As shown in Figure 1, the photoelectric conversion element 10 has an inverted structure in which a support 11, a first electrode 12, a hole transport layer 13, a photoelectric conversion layer 14, an electron transport layer 15, and a second electrode 16 are stacked in this order.

[0013] The photoelectric conversion element 10 may or may not include, for example, a first electrode 12, a hole transport layer 13, a photoelectric conversion layer 14, an electron transport layer 15, a second electrode 16, and other components. For example, the first electrode 12 and the hole transport layer 13 may be directly stacked without other components present, or other components may be present between them. Similarly, the hole transport layer 13 and the photoelectric conversion layer 14 may be directly stacked without other components present, or other components may be present between them. Similarly, the photoelectric conversion layer 14 and the electron transport layer 15 may be directly stacked without other components present, or other components may be present between them. Similarly, the electron transport layer 15 and the second electrode 16 may be directly stacked without other components present, or other components may be present between them.

[0014] Next, the configuration and components of the photoelectric conversion element 10 of this embodiment will be described in more detail, using the case shown in Figure 1 as an example. However, the photoelectric conversion element 10 of this embodiment is not limited to the following example. In the following, the case in which the photoelectric conversion element 10 of this embodiment is a solar cell will be mainly described.

[0015] [Support] The support 11 is not particularly limited, and may be any substrate suitable for use in photoelectric conversion elements such as general solar cells. Examples of substrates include glass, plastic plates including plastic films, plastic films, inorganic crystals, etc. The thickness of the substrate is not particularly limited, and is, for example, a thickness that does not hinder the flexibility of the photoelectric conversion element 10 of this embodiment. In this disclosure, "flexible" means, for example, that the photoelectric conversion element 10 of this embodiment does not crack or break after stress is applied, and is flexible to such an extent that it does not affect the performance of the photoelectric conversion element 10. If the substrate is glass, its thickness is, for example, 0.5 mm to 1.1 mm. If the substrate is a plastic film, its thickness is, for example, 50 μm to 125 μm. Furthermore, composite substrates in which at least one of the following films—a metal film, a semiconductor film, a conductive film, and an insulating film—is formed on part or all of the surface of these substrates can also be suitably used as the support 11. The size and thickness of the support 11 are not particularly limited, and may be the same as or similar to those of a photoelectric conversion element such as a general solar cell.

[0016] [First electrode] The first electrode 12 is, for example, a layer that supports the hole transport layer 13 and has the function of extracting holes from the photoelectric conversion layer 14, and the first electrode 12 is a layer that acts as a cathode (positive electrode).

[0017] The first electrode 12 may be formed directly on the support 11, for example. The first electrode 12 may also be a transparent electrode formed from a conductor, for example. The transparent electrode is not particularly limited and includes, for example, a tin-doped indium oxide (ITO) film, an impurity-doped indium oxide (In2O3) film, an impurity-doped zinc oxide (ZnO) film, a fluorine-doped tin dioxide (FTO) film, a laminated film formed by laminating two or more of these, gold, silver, copper, aluminum, tungsten, titanium, chromium, nickel, and cobalt. These may be used individually or in combination of two or more, and may be a single layer or a laminate. Furthermore, these films may function as a diffusion-blocking layer, for example. The thickness of the first electrode 12 is, from the viewpoint of suppressing the reduction in transmittance due to optical interference, for example, 50 nm to 100 nm or 60 nm to 80 nm. Furthermore, the shape of the first electrode 12 is not particularly limited and may be, for example, a film or a grid-like structure. In addition, the first electrode 12 may be used in combination with metal wiring, for example, to reduce its electrical resistance. The material of the metal wiring (metal lead wire) is not particularly limited and may include, for example, aluminum, copper, silver, gold, platinum, and nickel. Furthermore, it is desirable that the first electrode 12 contains a metal oxide. If the first electrode 12 itself does not contain a metal oxide, it is desirable to form a metal oxide layer, either alone or in mixtures, made from oxides such as nickel, copper, and aluminum (specifically, NiO, CuO, AlNiO, AlCuO, etc.) on the surface of the first electrode 12 (at the interface between the first electrode 12 and the hole transport layer 13 described later). This improves the interfacial adhesion with the hole transport layer described later.

[0018] [Hole transport layer] In this embodiment, the hole transport layer 13 is a layer that has the function of transporting electric charge. The hole transport layer 13 may contain compounds represented by general formulas (1) to (3). [ka] In the above chemical formula (1), R1 ~R 3 These may be the same or different, and represent an alkyl group, an alkoxy group, an aryl group, or a halogen atom. 1 ~X 3 This shows a structure that forms an aromatic ring, and the atoms constituting the aromatic ring may or may not contain heteroatoms. 1 ~Y 3 Y is a group represented by a hydrogen atom or -LZ. 1 ~Y 3 At least one of these is a group represented by -LZ. In a group represented by -LZ, L represents a divalent alkyl group, alkoxy group, or aryl group bonded to a nitrogen atom. 1 ~Y 3 If only one of them is a group represented by -LZ, then Z indicates a substituent that can bond to a material at the interface between the first electrode 12 and the hole transport layer 13, such as a metal oxide. 1 ~Y 3 If two or more of these groups are represented by -LZ, then at least one Z represents a substituent capable of bonding to a substance at the interface between the first electrode 12 and the hole transport layer 13, and the remaining Z represents hydrogen. More specifically, Z represents a substituent capable of bonding to a metal oxide by covalent or hydrogen bonding. Y 1 ~Y 3 Of these, Y 1 , Y 2 It is preferable that both are groups represented by -LZ. This improves adhesion with the photoelectric conversion layer 14, which will be described later, and consequently further improves the photoelectric conversion efficiency and durability of the photoelectric conversion element 10.

[0019] The above chemical formula (1) may also be a compound represented by the following chemical formula (1a). [ka] In chemical formula (1a), R 1 ~R 3 These may be the same or different, and represent an alkyl group, an alkoxy group, an aryl group, or a halogen atom. 1 ~X 3This shows a structure that forms an aromatic ring, and the atoms constituting the aromatic ring may or may not contain heteroatoms. 1 ~L 3 Z represents a divalent alkyl group, alkoxy group, or aryl group bonded to a nitrogen atom, and may be the same or different. 1 ~Z 3 Of these, at least one represents a substituent that can bond to a material at the interface between the first electrode 12 and the hole transport layer 13, such as a metal oxide, and the rest represent hydrogen.

[0020] The above chemical formula (1) may more specifically refer to a compound represented by the following chemical formula (2). [ka] In chemical formula (2), R 1 ~R 3 These may be the same or different, and represent an alkyl group, an alkoxy group, an aryl group, or a halogen atom. 1 ~X 3 This shows a structure that forms an aromatic ring, and the atoms constituting the aromatic ring may or may not contain heteroatoms. Also, X 1 ~X 3 L is optional. 1 ~L 3 Z represents a divalent alkyl group, alkoxy group, or aryl group bonded to a nitrogen atom, and may be the same or different. 1 ~Z 3 Of these, at least one represents a substituent that can bond to a material at the interface between the first electrode 12 and the hole transport layer 13, such as a metal oxide, and the rest represent hydrogen.

[0021] Furthermore, the above chemical formula (2) may more specifically refer to a compound represented by the following chemical formula (3). [ka] In the above chemical formula (3), R 1 ~R 3These may be the same or different, and represent an alkyl group, an alkoxy group, an aryl group, or a halogen atom. 1 ~L 3 This represents a divalent alkyl group, alkoxy group, or aryl group bonded to a nitrogen atom, and may be the same or different.

[0022] More detailed specific examples of general formula (1) include the compounds shown below in A-01 to A-56.

[0023] [ka]

[0024] [ka]

[0025] [ka]

[0026] [ka]

[0027] [ka]

[0028] [ka]

[0029] [ka]

[0030] [ka]

[0031] [ka]

[0032] [ka]

[0033] Furthermore, in this disclosure, if a compound has isomers such as tautomers or stereoisomers (e.g., geometric isomers, conformational isomers, and optical isomers), any of the isomers may be used unless otherwise specified. Also, in this disclosure, if a compound can form a salt, the salt may be used unless otherwise specified. The salt may be an acid addition salt or a base addition salt. Furthermore, the acid forming the acid addition salt may be an inorganic acid or an organic acid, and the base forming the base addition salt may be an inorganic base or an organic base. The inorganic acid is not particularly limited and includes, for example, sulfuric acid, phosphoric acid, hydrofluoric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, hypofluorite, hypochlorous acid, hypobromous acid, hypoiodic acid, hypofluorite, chlorous acid, bromous acid, iodic acid, fluorite, chlorite, bromic acid, iodic acid, perfluorite, perchlorite, perbromic acid, and periodic acid. The organic acid is not particularly limited and includes, for example, p-toluenesulfonic acid, methanesulfonic acid, oxalic acid, p-bromobenzenesulfonic acid, carbonic acid, succinic acid, citric acid, benzoic acid, and acetic acid. The inorganic base is not particularly limited and includes, for example, ammonium hydroxide, alkali metal hydroxide, alkaline earth metal hydroxide, carbonate, and bicarbonate. More specifically, it includes, for example, sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, calcium hydroxide, and calcium carbonate. The organic base is also not particularly limited and includes, for example, ethanolamine, triethylamine, and tris(hydroxymethyl)aminomethane. The method for producing these salts is also not particularly limited and can be produced, for example, by appropriately adding the above-mentioned acids and bases to the compound by known methods.

[0034] The hole transport layer of this embodiment uses the compound represented by the chemical formula (1) described above. The method for adsorbing the compound represented by chemical formula (1) onto the first electrode 12 is not particularly limited; the compound represented by chemical formula (1) can be dissolved in a solvent and brought into contact with the first electrode 12 to bond with it. The bond between the compound represented by chemical formula (1) and the first electrode 12 is not particularly limited; it can be a physical bond or a chemical bond. The type of bond is also not particularly limited; it can be a hydrogen bond, an ester bond, a chelate bond, or any other. The solvent used to dissolve the compound represented by chemical formula (1) is also not particularly limited; for example, it may be water and / or an organic solvent, or a mixture thereof. Examples of organic solvents include alcohols such as methanol, ethanol, and 2-propanol; ethers such as diethyl ether and diisopropyl ether; ketones such as acetone and methyl isobutyl ketone; esters such as ethyl acetate, isobutyl acetate, and γ-butyrolactone; heterocyclic solvents such as tetrahydrofuran and thiophene; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; sulfoxides such as dimethyl sulfoxide; sulfones such as diethyl sulfone and sulfolane; nitriles such as acetonitrile and 3-methoxypropionitrile; aromatic compounds such as benzene, toluene, and chlorobenzene; halogenated solvents such as dichloromethane and chloroform; and fluorinated solvents such as chlorofluorocarbon and hydrochlorofluorocarbon. These can be used individually or in mixtures of two or more.

[0035] The specific method for adsorbing the compound represented by chemical formula (1) onto the first electrode 12 to form an electron transport layer is not particularly limited, but known methods such as dipping, spraying, spin coating, and bar coating can be mentioned. The temperature during adsorption is not particularly limited, but -20°C to 100°C is preferred, and 0°C to 50°C is more preferred. The adsorption time is also not particularly limited, but for example, 1 second to 48 hours is preferred, and 10 seconds to 1 hour is more preferred.

[0036] Furthermore, washing may or may not be performed after the adsorption treatment. The washing method is not particularly limited, and any known method may be used as appropriate. Heat treatment may or may not be performed after the adsorption treatment or washing. The temperature of the heat treatment is preferably 50°C to 150°C, and more preferably 70°C to 120°C. The heat treatment time is preferably 1 second to 48 hours, and more preferably 10 seconds to 1 hour. This heat treatment may be performed, for example, in the atmosphere or in a vacuum.

[0037] When adsorbing the compound represented by the general formula (1) onto the first electrode 12, a co-adsorbent may also be used. Specific examples of co-adsorbents include phosphonic acid compounds such as n-butylphosphonic acid, n-hexylphosphonic acid, n-decylphosphonic acid, n-octadecylphosphonic acid, 2-ethylhexylphosphonic acid, methoxymethylphosphonic acid, 3-acryloyloxypropylphosphonic acid, 11-hydroxyundecylphosphonic acid, and 1H,1H,2H,2H-perfluorophosphonic acid, as well as acetic acid, propionic acid, isobutyric acid, nonanoic acid, fluoroacetic acid, α-chloropropionic acid, and glyoxylic acid. These may be used individually or in combination of two or more types.

[0038] The method for adsorbing the co-adsorbent onto the first electrode 12 is not particularly limited, but it is preferable to dissolve it in a solvent before adsorption, similar to the compound represented by chemical formula (1). The solvent is also not particularly limited, but it may be the same as the solvent exemplified for the compound represented by chemical formula (1). Furthermore, the co-adsorbent may be adsorbed by first adsorbing the compound represented by chemical formula (1) onto the substrate, and then immersing the first electrode 12 in a solvent in which the co-adsorbent is dissolved, or it may be used after mixing and dissolving it together with the compound represented by chemical formula (1) in an organic solvent.

[0039] The hole transport layer 13 may contain components other than those of chemical formula (1) above. Examples of components other than those of chemical formula (1) include PATAT (Phosphonic acid functionalized triazatruxene). In other words, the hole transport layer 13 may be a mixture of those of chemical formula (1) and those other than those of chemical formula (1). Based on the total mass of the hole transport layer 13, the content of the compound represented by the above chemical formula (1) is preferably 5% by mass or more and 100% by mass or less, and more preferably 50% by mass or more and 100% by mass or less.

[0040] [Photoelectric conversion layer] The photoelectric conversion layer 14 is not particularly limited and may be the same as the photoelectric conversion layer used in general photoelectric conversion elements such as solar cells. The photoelectric conversion layer 14 includes a perovskite structure (perovskite compound). The perovskite compound may be, for example, a compound represented by the following chemical formula (4). XαYβZγ...(4)

[0041] In chemical formula (4), the ratio of α:β:γ is 3:1:1, where β and γ represent integers greater than 1. X represents a halogen ion, Y represents an organic compound having an amino group, and Z represents a metal ion. The perovskite layer is preferably positioned adjacent to the electron transport layer. Note that the ratio of α:β:γ does not necessarily have to be 3:1:1, for example, 3:1.05:0.95. Furthermore, there are no particular restrictions on X, and it can be appropriately selected depending on the purpose, for example, halogen ions such as chlorine, bromine, and iodine. These may be used individually or in combination of two or more. Y may be alkylamine compound ions (organic compounds having an amino group) such as methylamine, ethylamine, n-butylamine, and formamidine, or alkali metal ions such as cesium, potassium, and rubidium, not limited to organic compounds. Alkylamine compound ions and alkali metal ions may each be used individually or in combination of two or more. Furthermore, organic (alkylamine compound ions) and inorganic (alkali metal ions) can be used in combination; for example, cesium ions and formamidine may be used in combination. There are no particular restrictions on Z, and it can be appropriately selected depending on the purpose. Examples include metals such as lead, indium, antimony, tin, copper, and bismuth. These may be used individually or in combination of two or more. Lead is particularly preferred, and among these, the combination of lead and tin is especially preferred. In addition, the perovskite layer preferably exhibits a layered perovskite structure in which layers made of metal halides and layers in which organic cation molecules are arranged are alternately stacked. The perovskite layer may contain alkali metals. It is advantageous that the perovskite layer contains at least alkali metals in that it increases the output. Examples of alkali metals include cesium, rubidium, and potassium. Among these, cesium is preferred.

[0042] As described above, the photoelectric conversion layer 14 may be a perovskite layer formed from a perovskite compound. There are no particular restrictions on the method for forming such a perovskite layer, and it can be appropriately selected depending on the purpose. For example, one method is to coat a solution in which a metal halide and an alkylamine halide are dissolved or dispersed, and then dry it.

[0043] Furthermore, methods for forming the perovskite layer include, for example, a two-step deposition method in which a solution containing dissolved or dispersed metal halides is applied, dried, and then immersed in a solution containing dissolved alkylamine halides to form the perovskite compound. Other methods include applying a solution containing dissolved or dispersed metal halides and alkylamine halides while adding a poor solvent (solvent with low solubility) for the perovskite compound to precipitate crystals. In addition, a method of depositing metal halides in a gas filled with methylamine or the like is also possible. Moreover, a method of applying a solution containing dissolved or dispersed metal halides and alkylamine halides while adding a poor solvent for the perovskite compound to precipitate crystals is particularly preferred. There are no particular restrictions on the method of applying these solutions, and they can be appropriately selected according to the purpose, and examples include immersion method, spin coating method, spray method, dip method, roller method, and air knife method. Furthermore, the method of applying the solution may also be deposition in a supercritical fluid using carbon dioxide or the like. Examples of poor solvents that can be used in the method of precipitating crystals by adding the poor solvents described above include hydrocarbons such as n-hexane and n-octane, alcohols such as methanol, ethanol, and 2-propanol, ethers such as diethyl ether and diisopropyl ether, ketones such as acetone and methyl isobutyl ketone, esters such as ethyl acetate, isobutyl acetate, and γ-butyrolactone, nitriles such as acetonitrile and 3-methoxypropionitrile, aromatic hydrocarbon compounds such as benzene, toluene, and chlorobenzene, halogenated solvents such as dichloromethane and chloroform, and fluorinated solvents such as chlorofluorocarbons, hydrochlorofluorocarbons, and hydrofluorocarbons.

[0044] The thickness of the photoelectric conversion layer 14 (for example, a light absorption layer, such as a perovskite layer) is not particularly limited, but from the viewpoint of further suppressing performance degradation due to defects and delamination, 50 to 1200 nm is preferred, and 200 to 800 nm is more preferred.

[0045] [Electron transport layer] The material used for the electron transport layer 15 is not particularly limited and can be appropriately selected depending on the purpose, but semiconductor materials are preferred, for example. The semiconductor material is not particularly limited and known materials can be used, for example, elemental semiconductors, compound semiconductors, organic n-type semiconductors, etc.

[0046] The aforementioned single semiconductor is not particularly limited, and examples include silicon and germanium.

[0047] The compound semiconductor is not particularly limited, and examples include metal chalcogenides, specifically oxides of titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium, tantalum, etc.; sulfides of cadmium, zinc, lead, silver, antimony, bismuth, etc.; selenides of cadmium, lead, etc.; tellurides of cadmium, etc. Other compound semiconductors include, for example, phosphides of zinc, gallium, indium, cadmium, etc., gallium arsenide, copper-indium-selenium, copper-indium-sulfide, etc.

[0048] The aforementioned organic n-type semiconductor is not particularly limited, and examples include perylenetetracarboxylic anhydride, perylenetetracarboxydiimide compounds, naphthalenediimide-bithiophene copolymers, benzbisimidazobenzophenanthroline polymers, fullerene compounds such as C60, C70, PCBM ([6,6]-phenyl-C61-methyl butyrate), carbonyl bridge-bithiazole compounds, ALq3 (tris(8-quinolinolato)aluminum), triphenylene bipyridyl compounds, silole compounds, and oxadiazole compounds.

[0049] Among the aforementioned materials used in the electron transport layer 15, organic n-type semiconductors are particularly preferred.

[0050] The material used to form the electron transport layer 15 may be, for example, one type alone or two or more types in combination. If the material used to form the electron transport layer 15 is a semiconductor material, the crystal type of the semiconductor material is not particularly limited and can be appropriately selected according to the purpose. For example, it may be a single crystal, a polycrystalline material, or an amorphous material.

[0051] The thickness of the electron transport layer 15 is not particularly limited and can be appropriately selected depending on the purpose, for example, 5 nm to 1000 nm or 10 nm to 700 nm.

[0052] In the case of an inverted structure, an electron injection layer (hole blocking layer) may be provided between the electron transport layer 15 and the second electrode 16. Examples of materials used for the electron injection layer include metal oxides such as BCP (basocuproine) and tin oxide, and may be doped with cesium or the like. The thickness of the electron injection layer is, for example, 1 nm to 100 nm or 3 nm to 20 nm.

[0053] [Second electrode] The second electrode 16 (which may be, for example, a back electrode) is a layer that has the function of extracting holes or electrons from the photoelectric conversion layer 14 via, for example, a hole transport layer 13 or an electron transport layer 15.

[0054] The second electrode 16 may be formed directly on the hole transport layer 13 if the photoelectric conversion element 10 has a forward structure (see Figure 2), or directly on the electron transport layer 15 if it has the reverse structure. The material of the second electrode 16 is not particularly limited, and for example, the same material as the first electrode 12 can be used. The shape, structure, and size of the second electrode 16 are not particularly limited and can be appropriately selected according to the purpose. Examples of materials for the second electrode 16 include metals, carbon compounds, conductive metal oxides, and conductive polymers. Examples of metals include platinum, gold, silver, copper, and aluminum. Examples of carbon compounds include graphite, fullerene, carbon nanotubes, and graphene. Examples of conductive metal oxides include ITO, IZO (Indium Zinc Oxide), fluorine-doped tin oxide (FTO), and antimond-doped tin oxide (ATO). Examples of conductive polymers include polythiophene and polyaniline. Furthermore, the material used to form the second electrode 16 may be, for example, one type alone, or two or more types in combination.

[0055] Furthermore, in the photoelectric conversion element 10 of this embodiment, it is preferable that at least one of the first electrode 12 and the second electrode 16 is substantially transparent. When using the photoelectric conversion element 10 of this embodiment, it is preferable to make the electrodes transparent and allow the incident light to enter from the transparent electrode side. In this case, it is preferable to use a light-reflecting material for the back electrode (the electrode opposite to the transparent electrode, for example, the second electrode 16), and metals, glass with a conductive oxide deposited on it, plastics, and thin metal films are preferably used. Providing an anti-reflective layer on the electrode on the light incident side is also an effective means.

[0056] Furthermore, the configuration of the photoelectric conversion element 10 in this embodiment is not limited to the configuration shown in Figure 1. For example, the support 11 may be positioned on the opposite side from Figure 1 (above the second electrode 16 in Figure 1), and the second electrode 16, electron transport layer 15, photoelectric conversion layer 14, hole transport layer 13, and first electrode 12 may be stacked on the support 11 in this order. Also, as mentioned above, other components may or may not exist between each layer of the first electrode 12, hole transport layer 13, photoelectric conversion layer 14, electron transport layer 15, second electrode 16, and support 11. In addition, although an example in which the first electrode 12 is a transparent electrode and the second electrode 16 is a back electrode has been described, the embodiment is not limited to this. For example, in the photoelectric conversion element 10 of this embodiment, the first electrode 12 may be a back electrode and the second electrode 16 may be a transparent electrode.

[0057] The total thickness of the photoelectric conversion element 10 in this embodiment can be appropriately changed depending on the thickness of the support 11 used.

[0058] [Sealed] The photoelectric conversion element 10 (e.g., a solar cell) of this embodiment is preferably sealed to protect it from water and oxygen. The sealing structure is not particularly limited and may be the same as that of a general photoelectric conversion module (e.g., a solar cell). For example, the sealing material may be applied only to the outer periphery of the photoelectric conversion element 10 of this embodiment and covered with glass or film, the sealing material may be applied to the entire surface of the photoelectric conversion element 10 of this embodiment and covered with glass or film, or the sealing material may be applied to the entire surface of the photoelectric conversion element 10 of this embodiment.

[0059] The material of the sealing member is not particularly limited and can be appropriately selected depending on the purpose. For example, epoxy resin or acrylic resin is preferably used and cured, but it may be uncured or partially cured.

[0060] The epoxy resin used for encapsulation is not particularly limited and includes, for example, water-dispersible, solvent-free, solid, heat-curing, curing agent-mixed, and UV-curing types. Among these, the heat-curing and UV-curing types are preferred, and the UV-curing type is more preferred. Even if the epoxy resin is UV-curing, heating is possible, and it is preferable to heat it even after UV curing. Specifically, epoxy resins include bisphenol A type, bisphenol F type, novolac type, cyclic aliphatic type, long-chain aliphatic type, glycidylamine type, glycidyl ether type, and glycidyl ester type. These may be used individually or in combination of two or more types. It is also preferable to mix the epoxy resin with a curing agent and various additives as needed. Existing commercially available epoxy resin compositions can be used in the present invention. Examples of such commercially available epoxy resin compositions include those developed and sold for solar cells and organic EL (Electro-Luminescence) elements, which can be used particularly effectively in the present invention. Examples of commercially available epoxy resin compositions include TB3118, TB3114, TB3124, TB3125F (manufactured by ThreeBond Corporation), WorldRock5910, WorldRock5920, WorldRock8723 (manufactured by Kyōritsu Chemical Industry Co., Ltd.), WB90US(P), and WB90US-HV (manufactured by Moresco).

[0061] The acrylic resin used for sealing is not particularly limited, and for example, those developed and commercially available for solar cells and organic EL elements can be effectively used. Examples of such commercially available acrylic resin compositions include TB3035B and TB3035C (manufactured by ThreeBond Co., Ltd.).

[0062] The curing agent used for curing epoxy resins is not particularly limited and can be appropriately selected depending on the purpose. Examples include amine-based, acid anhydride-based, polyamide-based, and other curing agents. Examples of amine-based curing agents include aliphatic polyamines such as diethylenetriamine and triethylenetetramine; and aromatic polyamines such as metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone. Examples of acid anhydride-based curing agents include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, pyromellitic anhydride, hetic anhydride, and dodecenyl succinic anhydride. Examples of other curing agents include imidazoles and polymer captans. One type of curing agent may be used alone, or two or more types may be used in combination.

[0063] The additives added to the epoxy resin are not particularly limited and can be appropriately selected depending on the purpose. Examples include fillers, gap fillers, polymerization initiators, desiccants (hygroscopic agents), curing accelerators, coupling agents, softening agents, colorants, flame retardant aids, antioxidants, and organic solvents. Fillers, gap fillers, curing accelerators, polymerization initiators, and desiccants (hygroscopic agents) are preferred, and fillers and polymerization initiators are more preferred. Including the filler as an additive suppresses the penetration of moisture and oxygen, and further reduces volume shrinkage during curing, reduces outgassing during curing or heating, improves mechanical strength, and controls thermal conductivity and fluidity. Therefore, including the filler as an additive is very effective in maintaining stable output in various environments.

[0064] Furthermore, regarding the output characteristics and durability of the photoelectric conversion element 10, the effects of outgassing generated during the curing or heating of the sealing member cannot be ignored, in addition to the effects of moisture and oxygen that penetrate. In particular, the effects of outgassing generated during heating have a significant impact on the output characteristics when stored in a high-temperature environment. By including the filler, gap agent, and desiccant in the sealing member, these materials themselves can suppress the penetration of moisture and oxygen, and the amount of sealing member used can be reduced, thereby reducing outgassing. Including the filler, gap agent, and desiccant in the sealing member is effective not only during curing but also when storing the photoelectric conversion module in a high-temperature environment.

[0065] The filler is not particularly limited and can be appropriately selected depending on the purpose. Examples include crystalline silica, amorphous silica, silicate minerals such as talc, inorganic fillers such as alumina, aluminum nitride, silicon nitride, calcium silicate, and calcium carbonate, with hydrotalcite being particularly preferred. The filler may be used alone or in combination of two or more types.

[0066] The average primary particle size of the filler is not particularly limited, and is, for example, 0.1 μm to 10 μm or 1 μm to 5 μm. If the average primary particle size of the filler is within the above range, the effect of suppressing the intrusion of moisture and oxygen can be sufficiently obtained, the viscosity becomes appropriate, adhesion to the support 11 and defoaming properties are improved, and it is also effective in controlling the width of the sealing part and improving workability.

[0067] The content of the filler is, for example, 10 to 90 parts by mass or 20 to 70 parts by mass relative to the entire sealing member (100 parts by mass). If the content of the filler is within the above range, sufficient inhibition of moisture and oxygen penetration is obtained, the viscosity is appropriate, and adhesion and workability are also good.

[0068] The gap agent is also called a gap control agent or spacer agent. Including the gap agent as an additive makes it possible to control the gap of the sealed portion. For example, when sealing is performed by applying a sealing member to a support 11 or a first electrode 12 and placing a second electrode 16 on top of it, if the sealing member includes a gap agent, the gap of the sealed portion will be adjusted to the size of the gap agent, making it easy to control the gap of the sealed portion.

[0069] The gap filler is not particularly limited, but is preferably granular with a uniform particle size and high solvent resistance and heat resistance, and can be appropriately selected depending on the purpose. The gap filler is preferably highly compatible with epoxy resin and has a spherical particle shape. Specifically, the gap filler is preferably glass beads, silica fine particles, organic resin fine particles, etc. One type of gap filler may be used alone, or two or more types may be used in combination. The particle size of the gap filler can be selected according to the gap of the sealing part to be set, but is preferably 1 μm to 100 μm or 5 μm to 50 μm.

[0070] The polymerization initiator is not particularly limited and, for example, can be a polymerization initiator that initiates polymerization using heat or light, and can be appropriately selected depending on the purpose. Examples include thermal cation polymerization initiators and photocationic polymerization initiators. The thermal polymerization initiator is a compound that generates active species such as radicals and cations when heated, and examples include azo compounds such as 2,2'-azobisbutyronitrile (AIBN) and peroxides such as benzoyl peroxide (BPO). Examples of thermal cationic polymerization initiators include benzenesulfonic acid esters and alkylsulfonium salts. The photocationic polymerization initiator is preferably used, for example, when the material of the sealing member is epoxy resin. When the photocationic polymerization initiator is mixed with epoxy resin and irradiated with light, the photocationic polymerization initiator decomposes and generates acid, which causes polymerization of the epoxy resin and the curing reaction proceeds. The photocationic polymerization initiator has the effect of low volume shrinkage during curing, not being affected by oxygen inhibition, and having high storage stability.

[0071] Examples of the photocatalytic polymerization initiators include aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts, metacerone compounds, and silanol-aluminum complexes. As the polymerization initiator, a photoacid generator that generates acid upon irradiation with light can also be used. The photoacid generator acts as an acid that initiates cationic polymerization and includes ionic sulfonium salts and iodonium salts, etc., consisting of a cation and anion. The photoacid generator may be used alone or in combination of two or more types.

[0072] The amount of polymerization initiator added is not particularly limited and may vary depending on the material used, but for example, it is 0.5 to 10 parts by mass or 1 to 5 parts by mass per 100 parts by mass of the entire sealing member. If the amount added is within the above range, curing will proceed properly, the amount of uncured material remaining can be reduced, and excessive outgassing can be prevented.

[0073] The desiccant (also called a moisture absorber) is a material that has the function of physically or chemically adsorbing and absorbing moisture, and by incorporating it into the sealing member, moisture resistance can be further enhanced and the effects of outgassing can be reduced. The desiccant is not particularly limited and can be appropriately selected according to the purpose, and particulate form is preferred. Examples include inorganic water-absorbing materials such as calcium oxide, barium oxide, magnesium oxide, magnesium sulfate, sodium sulfate, calcium chloride, silica gel, molecular sieves, and zeolites, with zeolites, which have a high moisture absorption capacity, being preferred. The desiccant may be used alone or in combination of two or more types.

[0074] The curing accelerator (also called a curing catalyst) is a material that speeds up the curing process and is mainly used with thermosetting epoxy resins. The curing accelerator is not particularly limited and can be appropriately selected depending on the purpose. Examples 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 phosphines or phosphonium salts such as triphenylphosphine and tetraphenylphosphonium·tetraphenylborate. The curing accelerator may be used alone or in combination of two or more types.

[0075] The coupling agent is not particularly limited as long as it is a material that has the effect of increasing molecular bonding strength, and can be appropriately selected according to the purpose, for example, silane coupling agents. Specifically, the coupling agent can be 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. The coupling agent may be used alone or in combination of two or more types.

[0076] In this embodiment, for example, a sheet-like adhesive can be used. The sheet-like adhesive is, for example, a sheet on which a resin layer has been formed in advance, and the sheet can be made of glass, a film with high gas barrier properties, or the like. Alternatively, the sheet may be formed using only sealing resin. The sheet-like adhesive can also be attached to a sealing film. Furthermore, the sheet-like adhesive can be bonded to the module after a structure with a hollow portion has been created on the sealing film.

[0077] When sealing using the sealing film, it is positioned opposite the support 11 so as to sandwich the photoelectric conversion element 10. The shape, structure, size, and type of the substrate of the sealing film are not particularly limited and can be appropriately selected according to the purpose. The sealing film has a barrier layer formed on the surface of the substrate that prevents the passage of moisture and oxygen, and this layer may be formed on one surface of the substrate or on both surfaces.

[0078] The barrier layer may be composed of a material whose main components are, for example, a metal oxide, a metal, or a mixture formed from a polymer and a metal alkoxide. Examples of the metal oxide include aluminum oxide, silicon oxide, and aluminum oxide. Examples of the polymer include polyvinyl alcohol, polyvinylpyrrolidone, and methylcellulose. Examples of the metal alkoxide include tetraethoxysilane, triisopropoxyaluminum, 3-glycidoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatetopropyltriethoxysilane.

[0079] The barrier layer may be transparent or opaque, for example. Furthermore, the barrier layer may be a single layer formed from a combination of the aforementioned materials, or it may be a multi-layered structure. The barrier layer can be formed using known methods, including vacuum deposition methods such as sputtering, dipping, roll coating, screen printing, spraying, and gravure printing.

[0080] [wiring] In this embodiment, the photoelectric conversion element 10 (for example, a solar cell) preferably has lead wires (wirings) connected to the electrodes and back electrode in order to efficiently extract the current generated by light. The lead wires are connected, for example, to the first electrode 12 and the second electrode 16 using a conductive material such as solder, silver paste, or graphite. The conductive material may be used alone, or it may be used in a mixed or laminated structure of two or more types. Furthermore, the parts to which the lead wires are attached may be covered with an acrylic resin or epoxy resin from the viewpoint of physical protection.

[0081] Lead wires are a general term for wires used to electrically connect power sources, electronic components, etc., in electrical circuits. Examples include vinyl-coated wires and enameled wires.

[0082] The photoelectric conversion element 10 described above not only possesses excellent photoelectric conversion characteristics but also boasts superior durability.

[0083] [application] The applications and methods of use of the photoelectric conversion element 10 of this embodiment are not particularly limited, and it can be widely used for the same purposes as a general photoelectric conversion element (e.g., a general solar cell). The photoelectric conversion element 10 of this embodiment (e.g., a solar cell) can be applied to a power supply device by combining it with, for example, a circuit board that controls the generated current. Examples of devices that utilize a power supply device include electronic desktop calculators and solar-powered radio-controlled watches. It is also possible to apply the photoelectric conversion element 10 of this embodiment as a power supply device to mobile phones, electronic paper, thermometers and hygrometers, etc. Furthermore, it can be used as an auxiliary power source to extend the continuous use time of rechargeable or battery-powered electrical appliances, or in combination with a secondary battery for nighttime use. It can also be used as a self-contained power source that does not require battery replacement or power wiring.

[0084] The embodiments of the present invention have been described above, but these are merely examples, and various other configurations can also be adopted. [Examples]

[0085] The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0086] [Synthesis Example 1] Synthesis of iso-TAT [ka] Indole (Tokyo Chemical Industries, I0021, 119 mg, 1.01 mmol) and copper acetate (Sigma-Aldrich, 326755, 9.1 mg, 5.1 mol%) were dissolved in toluene (5.0 ml). This solution was cooled to 0°C, and a toluene (5.0 ml) solution containing (bis(trifluoroacetoxy)iodo)benzene (Tokyo Chemical Industries, B1175, 432 mg, 1.0 mmol) was added dropwise while stirring. After stirring at 0°C for 10 minutes, saturated sodium bicarbonate aqueous solution was added to the reaction mixture to stop the reaction. Organic components were extracted with ethyl acetate, dried over sodium sulfate, and concentrated under reduced pressure. The resulting crude was purified by silica gel column chromatography (eluent: n-hexane / ethyl acetate = 7:5) to obtain the target product iso-TAT (68.2 mg, 0.2 mmol, yield 59%).

[0087] [Synthesis Example 2] Synthesis of iso-PETAT [ka] iso-TAT (150 mg, 0.43 mmol) was dissolved in N,N-dimethylformamide (4.5 ml), and sodium hydride (87 mg, 2.17 mmol) was added over 30 minutes at room temperature with stirring. Next, (3-bromopropyl)phosphonate ethyl ester (Tokyo Chemical Industries, B1591, 0.52 ml, 2.61 mmol) was added, and stirring was continued overnight at 70°C. After cooling to room temperature, the reaction was stopped by pouring the reaction mixture into water, saturated brine was added, and the organic components were extracted with dichloromethane. The organic layer was separated, dried over sodium sulfate, and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (eluent:acetone:methanol = 10:1) to obtain the target product iso-PETAT (202 mg, 0.23 mmol, yield 53%, brown oily). 1H NMR (400 MHz, acetone-d6): δ 9.01 (d, J=7.6Hz,1H), 8.95(d, J=7.6Hz, 1H), 8.51 (d, J = 7.6 Hz, 1H), 7.91 (t, J = 7.6 Hz, 3H), 7.52 (m, 6H), 5.20 (t, J = 7.0 Hz, 2H), 5.02 (t, J = 7.0 Hz, 2H), 4.92 (t, J = 7.0 Hz, 2H), 3.96 (m, 4H), 3.68 (m, 8H), 2.32 (m, 2H), 1.85 (m, 2H), 1.58 (m, 2H), 1.48 (m, 2H), 1.25 (m, 4H), 1.17 (t, J = 7.2 Hz, 6H), 0.96 (t, J = 7.2 Hz, 12H). 13C NMR (101 MHz, acetone-d6): δ 145.5, 144.2, 141.8, 134.4, 132.4, 127.5, 127.4, 126.8, 125.8, 125.5, 125.3, 124.9, 124.5, 124.2, 123.7, 122.8, 121.9, 121.3, 120.4, 120.3, 114.1, 113.9, 113.2, 111.3, 110.7, 61.9, 61.8, 61.6 (61.61), 61.6 (61.58), 61.5 (61.54), 61.5 (61.52), 52.6, 49.3, 49.2, 48.9, 48.8, 47.4, 47.2, 26.7, 25.3, 24.4 (24.40), 24.4 (24.36), 23.7, 23.6, 23.5, 22.3, 22.2, 22.1, 21.8, 21.7, 21.4 (21.40), 21.4 (21.35), 21.2, 16.8, 16.7 (16.74), 16.7 (16.69), 16.5 (16.52), 16.5 (16.46). HRMS (APCI) (m / z): [M+H]+ calcd. for C45H61N3O9P3, 880.3615; found, 880.3611.

[0088] [Synthesis Example 3] Synthesis of Compound A-10 [ka] iso-PETAT (121 mg, 0.14 mmol) was dissolved in dichloromethane (4.0 ml), and bromotrimethylsilane (Tokyo Chemical Industries, B1087, 0.18 ml, 1.37 mmol) was added dropwise. The mixture was stirred overnight at room temperature. Under reduced pressure, the dichloromethane was removed, methanol (10.0 ml) was added, and the mixture was stirred at room temperature for 30 minutes. Under reduced pressure, the methanol was removed, and the resulting solid was washed with dichloromethane to obtain the target compound A-10 (57.4 mg, 81 μmol, yield 59%, pale green crystals). 1 H NMR (400 MHz, DMSO-d6): δ8.89 (d, J = 8.0 Hz, 1H), 8.83 (d, J = 8.0 Hz, 1H), 8.40 (d, J = 8.0 Hz, 1H), 7.91 (m, 3H), 7.49 (m, 6H), 5.08 (t, J = 8.0 Hz, 2H), 4.81 (t, J = 8.0 Hz, 2H), 4.72 (t, J = 8.0 Hz, 2H), 1.94 (t, J = 8.0 Hz, 2H), 1.46 (t, J = 8.0 Hz, 2H), 1.33 (t, J = 8.0 Hz, 2H), 1.16 (m, 2H), 0.89 (m, 4H). 13 C NMR (101 MHz, DMSO-d6): δ 144.1, 142.9, 141.0, 133.0, 131.2, 126.1, 125.7, 125.0, 124.5, 124.0, 123.6, 123.4, 123.0, 122.7, 121.7, 121.1, 120.5, 119.6, 118.5, 113.3, 113.2, 111.7, 111.0, 109.4, 48.6, 48.4, 48.2, 46.5, 46.3, 25.3, 25.2, 24.0, 23.8, 23.4, 21.6, 21.2 (21.23), 21.2 (21.18). HRMS (ESI) (m / z): [MH] -calcd. for C 33 H 35 N3O9P3, 710.1592; found, 710.1583.

[0089] [Synthesis Example 4] Synthesis of iso-TAT-Br [ka] 5-Bromoindole (Tokyo Chemical Industries, B1738, 1.96 g, 10 mmol) and copper acetate (Sigma-Aldrich, 326755, 90 mg, 1.0 mol%) were dissolved in toluene (25 ml). This solution was cooled to 0°C, and a toluene (70 ml) solution containing (bis(trifluoroacetoxy)iodo)benzene (Tokyo Chemical Industries, B1175, 4.30 g, 10 mmol) was added dropwise while stirring. The mixture was stirred at 0°C for 30 minutes, and the reaction was stopped by adding saturated sodium bicarbonate aqueous solution to the reaction mixture. The organic components were extracted with ethyl acetate, dried over sodium sulfate, and concentrated under reduced pressure. The resulting crude was recrystallized with ethyl acetate to obtain the target product, iso-TAT-Br (862 mg, 1.5 mmol, yield 45%).

[0090] [Synthesis Example 5] Synthesis of iso-PETAT-Br [ka] iso-TAT-Br (291 mg, 0.50 mmol) was dissolved in N,N-dimethylformamide (5.0 ml), and sodium hydride (70 mg, 1.75 mmol) was added over 30 minutes at room temperature with stirring. Next, (3-bromopropyl)phosphonate ethyl ester (Tokyo Chemical Industries, B1591, 0.60 ml, 3.0 mmol) was added, and stirring was continued overnight at 70°C. After cooling to room temperature, the reaction was stopped by pouring the reaction mixture into water, saturated brine was added, and the organic components were extracted with dichloromethane. The organic layer was separated, dried over sodium sulfate, and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (eluent:ethyl acetate:methanol = 5:1) to obtain the target product iso-PETAT-Br (671 mg, 0.60 mmol, yield 72%, brown oily). 1H NMR (400 MHz, acetone-d6): δ 8.89 (s, 1H), 8.79 (s, 1H), 8.49 (s, 1H), 7.90 (dd, J = 8.4 Hz, 6.0 Hz, 2H), 7.81 (d, J = 8.4 Hz,1H), 7.69 (d, J = 8.4 Hz, 2H), 7.55 (d, J = 8.4 Hz,1H), 5.02 (m,4H), 4.91 (t, J = 6.8 Hz, 2H), 4.91 (t, J = 6.8 Hz, 2H), 4.01 (m, 4H), 3.74 (m, 8H), 2.31 (m, 2H), 1.91 (m, 2H), 1.61 (m, 2H), 1.61 (m, 2H), 1.54 (m, 2H), 1.32 (m, 4H), 1.12 (t, J = 7.2 Hz, 6H), 1.00 (dd, J = 7.2 Hz, 12H). 13C NMR (101 MHz, acetone-d6): δ 143.8, 142.5, 140.0, 134.5, 132.8, 128.5, 128.4, 128.1, 127.6, 127.0, 126.6, 126.1, 125.8 (125.82), 125.8 (125.75), 124.6, 119.2, 115.8, 115.5, 114.6, 113.8, 112.9, 112.8, 111.7, 109.7, 61.9 (61.92), 61.96 (61.86), 61.7, 61.6, 61.5, 55.0, 49.4, 49.2, 49.1, 49.0, 47.3, 47.1, 24.6, 24.5, 23.5, 23.4 (23.43), 23.4 (23.39), 22.8, 22.1, 22.0 (22.03), 22.0 (21.99), 21.9, 21.6 (21.61), 21.6 (21.57), 21.3, 16.8, 16.7, 16.6, 16.5. HRMS (APCI) (m / z): [M+H]+ calcd. for C45H58Br3N3O9P3, 1114.0935; found, 114.0931.

[0091] [Synthesis Example 6] Synthesis of Compound A-18 [ka] iso-PETAT-Br (47.8 mg, 43 mmol) was dissolved in dichloromethane (2.0 ml), and bromotrimethylsilane (Tokyo Chemical Industries, B1087, 0.06 ml, 0.455 mmol) was added dropwise. The mixture was stirred overnight at room temperature. Under reduced pressure, the dichloromethane was removed, methanol (5.0 ml) was added, and the mixture was stirred at room temperature for 30 minutes. Under reduced pressure, the methanol was removed, and the resulting solid was washed with dichloromethane to obtain the target compound A-18 (31 mg, 32 mmol, yield 76%, pale green crystals). 1H NMR (400 MHz, DMASO-d6): δ8.34 (s, 3H), 7.90 (d, J = 8.6 Hz, 3H), 7.64 (d, J = 8.6 Hz, 3H), 5.00 (m, 6H), 1.93 (m, 6H), 1.17 (m, 6H). 13C NMR (101 MHz, DMSO--d6): δ 142.6, 141.4, 139.3, 133.3, 131.9, 127.7, 127.3, 126.9, 126.6, 126.1, 125.3, 124.9, 124.7, 124.5, 123.3, 117.5, 115.5, 115.2, 113.5, 113.0, 112.7, 111.8, 110.3, 108.6, 48.71, 48.6, 48.4, 46.5, 46.3, 25.1, 24.9, 23.7, 23.5, 21.7, 21.4, 0.8. HRMS (ESI) (m / z): [MH]- calcd. for C33H32Br3N3O9P3, 943.8907; found, 943.8898.

[0092] [Example 1] Specific example A-10's DMF solution (0.1 mmol / L) was placed in 100 μL portions onto the ITO of an ITO glass substrate (a glass substrate on which the first electrode was formed as a support), and a monolayer (hole transport layer) was formed on the ITO (first electrode) using a spin coater (3,000 rpm, 30 seconds). Next, a solution of cesium iodide (0.738 g), formamidine iodide (7.512 g), methylamine bromide (0.905 g), lead iodide (23.888 g), and lead bromide (1.022 g) dissolved in DMF (40.0 mL) and dimethyl sulfoxide (DMSO, 12.0 mL) was deposited on the substrate using spin coating. Spin coating was performed at 3000 rpm, and chlorobenzene (0.3 mL) was added dropwise 30 seconds after the start. Subsequently, the material was heated at 150°C for 10 minutes to obtain a perovskite layer (photoelectric conversion layer). Next, C60 (20 nm, electron transport layer), vasocuproin (BCP, 8 nm, electron injection layer), and Ag (100 nm, second electrode) were deposited by vacuum deposition to fabricate a photoelectric conversion element. Furthermore, Nagase ChemteX XNR5516 was coated onto the outer periphery of the photoelectric conversion element, bonded to glass under an inert gas atmosphere, and irradiated with UV light to fabricate a sealed device.

[0093] The photoelectric conversion characteristics of the encapsulated device fabricated in Example 1 were measured using a method compliant with the output measurement method for silicon crystalline solar cells specified in JISC8913:1998. A solar simulator (SMO-250III, manufactured by Spectrometer Co., Ltd.) combined with an air mass filter equivalent to AM1.5G was used with a secondary reference Si solar cell at 100 mW / cm². 2The light intensity was adjusted to serve as the light source for measurement, and while irradiating a test sample of a perovskite solar cell (the sealed device fabricated in Example 1) with light, the IV curve characteristics were measured using a source meter (Keithley Instruments Inc., 2400 general-purpose source meter). The short-circuit current (Isc), open-circuit voltage (Voc), fill factor (FF), short-circuit current density (Jsc), and photoelectric conversion efficiency (PCE) obtained from the IV curve characteristics measurement were calculated using the following equations 1 and 2. The results are shown in Table 1 below. In addition, the photoelectric conversion efficiency was measured after 500 hours in a dark place and in a 100°C dryer. The results are also shown in Table 1.

[0094] Equation 1: Short-circuit current density (Jsc; mA / cm²) 2 )=Isc(mA) / Effective photosensitive area S(cm 2 ) Equation 2: Photoelectric conversion efficiency (PCE; %) = Voc(V) × Jsc(mA / cm) 2 ) × FF × 100 / 100 (mW / cm 2 )

[0095] [Example 2] A photoelectric conversion element was fabricated in the same manner as in Example 1, except that the DMF solution (0.1 mmol / L) of Specific Example A-10 in Example 1 was changed to the DMF solution (0.1 mmol / L) of Specific Example A-18, and its characteristics were evaluated. The results are shown in Table 1.

[0096] [Comparative Example 1] A photoelectric conversion element was fabricated in the same manner as in Example 1, except that the DMF solution (0.1 mmol / L) in Specific Example A-10 of Example 1 was changed to the 2PACz DMF solution (0.1 mmol / L) shown below, and its characteristics were evaluated. The results are shown in Table 1. TIFF2026061681000025.tif44170

[0097] [Comparative Example 2] A photoelectric conversion element was fabricated in the same manner as in Example 1, except that the DMF solution (0.1 mmol / L) of Specific Example A-10 in Example 1 was replaced with the DMF solution (0.1 mmol / L) of PATAT shown below, and its characteristics were evaluated. The results are shown in Table 1. TIFF2026061681000026.tif64170

[0098] [Table 1]

[0099] [Example 3] In Example 2, a photoelectric conversion element was fabricated in the same manner as in Example 1, except that the DMF solution (0.1 mmol / L) of Specific Example A-18 was replaced with a solution prepared by mixing the DMF solution (0.1 mmol / L) of Specific Example A-18 and the DMF solution (0.1 mmol / L) of PATAT in a volume ratio of 9:1. The characteristics were then evaluated. The results are shown in Table 2.

[0100] [Example 4] In Example 2, a photoelectric conversion element was fabricated in the same manner as in Example 1, except that the DMF solution (0.1 mmol / L) of Specific Example A-18 was replaced with a solution prepared by mixing the DMF solution (0.1 mmol / L) of Specific Example A-18 and the DMF solution (0.1 mmol / L) of PATAT in a volume ratio of 5:5. The characteristics were then evaluated. The results are shown in Table 2.

[0101] [Example 5] In Example 2, a photoelectric conversion element was fabricated in the same manner as in Example 1, except that the DMF solution (0.1 mmol / L) of Specific Example A-18 was replaced with a solution prepared by mixing the DMF solution (0.1 mmol / L) of Specific Example A-18 and the DMF solution (0.1 mmol / L) of PATAT in a volume ratio of 1:9. The characteristics were then evaluated. The results are shown in Table 2.

[0102] [Example 6] NiO was formed on an ITO glass substrate (a glass substrate with the first electrode formed on it) by sputtering at a density of 10 nm. The surface roughness Ra (arithmetic mean roughness) of this NiO was 12 nm. 100 μL of the DMF solution (0.1 mmol / L) of specific example A-18 was placed on this NiO, and a monolayer (hole transport layer) was formed on the NiO using a spin coater (3,000 rpm, 30 seconds). Next, a solution of cesium iodide (0.738 g), formamidine iodide (7.512 g), methylamine bromide (0.905 g), lead iodide (23.888 g), and lead bromide (1.022 g) dissolved in DMF (40.0 mL) and dimethyl sulfoxide (DMSO, 12.0 mL) was formed on the substrate using spin coating. Spin coating was performed at 3000 rpm, and chlorobenzene (0.3 mL) was added dropwise 30 seconds after the start. Then, the mixture was heated at 150°C for 10 minutes to obtain a perovskite layer (photoelectric conversion layer). Next, C60 (20 nm, electron transport layer), vasocuproin (BCP, 8 nm, electron injection layer), and Ag (100 nm, second electrode) were deposited by vacuum deposition to fabricate a photoelectric conversion element. Furthermore, Nagase ChemteX XNR5516 was coated onto the outer periphery of the photoelectric conversion element, bonded to glass under an inert gas atmosphere, and irradiated with UV light to fabricate a sealed device. The characteristics of this photoelectric conversion element are shown in Table 2.

[0103] [Example 7] A photoelectric conversion element was fabricated in the same manner as in Example 6, except that the DMF solution (0.1 mmol / L) of Specific Example A-18 in Example 6 was replaced with a solution prepared by mixing the DMF solution (0.1 mmol / L) of Specific Example A-18 and the DMF solution (0.1 mmol / L) of PATAT in a volume ratio of 5:5. The characteristics were then evaluated. The results are shown in Table 2.

[0104] [Example 8] NiO was formed on an ITO glass substrate (a glass substrate with the first electrode formed on it) by sputtering at a density of 10 nm. The surface roughness Ra (arithmetic mean roughness) of this NiO was 12 nm. 100 μL of the DMF solution (0.1 mmol / L) of specific example A-18 was placed on this NiO, and a monolayer (hole transport layer) was formed on the NiO using a spin coater (3,000 rpm, 30 seconds). Next, a solution of cesium iodide (0.738 g), formamidine iodide (7.512 g), methylamine bromide (0.905 g), lead iodide (23.888 g), and lead bromide (1.022 g) dissolved in DMF (40.0 mL) and dimethyl sulfoxide (DMSO, 12.0 mL) was formed on the substrate using spin coating. Spin coating was performed at 3000 rpm, and chlorobenzene (0.3 mL) was added dropwise 30 seconds after the start. Then, the mixture was heated at 150°C for 10 minutes to obtain a perovskite layer (photoelectric conversion layer). Next, a photoelectric conversion element was fabricated by vacuum deposition of 20 nm SnO2 (electron transport layer) and 100 nm Cu (second electrode) using ALD (atomic layer deposition). Furthermore, Nagase ChemteX XNR5516 was applied to the outer periphery of the photoelectric conversion element, bonded to glass under an inert gas atmosphere, and irradiated with UV light to fabricate a sealed device. The characteristics of this photoelectric conversion element are shown in Table 2.

[0105] [Example 9] A photoelectric conversion element was fabricated in the same manner as in Example 8, except that the DMF solution (0.1 mmol / L) of Specific Example A-18 in Example 8 was replaced with a solution prepared by mixing the DMF solution (0.1 mmol / L) of Specific Example A-18 and the DMF solution (0.1 mmol / L) of PATAT in a volume ratio of 5:5. The characteristics were then evaluated. The results are shown in Table 2.

[0106] [Table 2]

[0107] The hole transport material of this embodiment is characterized by the rotational asymmetricity of the nitrogen atom (N) moiety with respect to the central benzene ring. Due to steric hindrance, one of the opposing nitrogen atom moieties can react with a metal oxide in or on the first electrode, such as ITO or NiO. On the other hand, the remaining nitrogen atom moiety is located on the perovskite layer side and remains unreacted. Since the substituents that can bond to metal oxides are hydrophilic groups, they are compatible with the perovskite layer, which is formed from ions, and the interfacial adhesion between the hole transport layer and the perovskite layer is increased, resulting in high durability. In contrast, in the case of PATAT alone, a comparative example in which the nitrogen atom (N) moiety is rotationally symmetric, there are almost no unreacted substituents on the perovskite layer side, so it is not expected that the effect of improving interfacial adhesion with the perovskite layer can be expected. Therefore, it is thought that by adding even a small amount of the hole transport material of this embodiment to PATAT, a comparative example, high durability can be achieved without impairing the photoelectric conversion characteristics. Furthermore, since the hole transport material of this embodiment has halogen atoms as substituents, the coating area of ​​the substrate increases, which reduces the number of recombination points and is expected to further improve the properties. [Industrial applicability]

[0108] As described above, this disclosure provides a photoelectric conversion element with excellent photoelectric conversion characteristics and durability. The photoelectric conversion element of this disclosure is useful, for example, as a solar cell. The applications and methods of use of the photoelectric conversion element of this disclosure are not particularly limited and can be applied to a wide range of fields in the same applications and methods as general photoelectric conversion modules (e.g., general solar cells). [Explanation of Symbols]

[0109] 10 Photoelectric conversion element, 11 Support, 12 First electrode, 13 Hole transport layer, 14 Photoelectric conversion layer, 15 Electron transport layer, 16 Second electrode

Claims

1. The first electrode, hole transport layer, photoelectric conversion layer, electron transport layer, and second electrode are stacked in this order. The aforementioned photoelectric conversion layer includes a perovskite structure, The hole transport layer is a photoelectric conversion element containing a compound represented by the following chemical formula (1). 【Chemistry 1】 In the above chemical formula (1), R １ ~R ３ These may be the same or different, and represent an alkyl group, an alkoxy group, an aryl group, or a halogen atom. １ ~X ３ This shows a structure that forms an aromatic ring, and the atoms constituting the aromatic ring may or may not contain heteroatoms. １ ~Y ３ Y is a group represented by a hydrogen atom or -L-Z. １ ~Y ３ At least one of these is a group represented as -L-Z. In the group represented as -L-Z, L represents a divalent alkyl group, alkoxy group, or aryl group bonded to a nitrogen atom, and Z represents a substituent that can bond to a substance at the interface between the first electrode and the hole transport layer.

2. The photoelectric conversion element according to claim 1, wherein the chemical formula (1) is a compound represented by the following chemical formula (2). 【Chemistry 2】 In the chemical formula (2), R １ to R ３ may be the same or different and each represents an alkyl group, an alkoxy group, an aryl group, or a halogen atom. X １ to X ３ represents a structure forming an aromatic ring, and the atoms constituting the aromatic ring may or may not contain a heteroatom. Also, X １ to X ３ may be absent. L １ to L ３ represent a divalent alkyl group, an alkoxy group, or an aryl group bonded to a nitrogen atom, and may be the same or different. Among Z １ to Z ３ , at least one represents a substituent capable of bonding to a substance at the interface between the first electrode and the hole transport layer, and the rest represent hydrogen.

3. The photoelectric conversion element according to claim 2, wherein the chemical formula (2) is a compound represented by the following chemical formula (3). 【Transformation 3】 In the above chemical formula (3), R １ ~R ３ These may be the same or different, and represent an alkyl group, an alkoxy group, an aryl group, or a halogen atom. １ ~L ３ This represents a divalent alkyl group, alkoxy group, or aryl group bonded to a nitrogen atom, and may be the same or different.

4. The photoelectric conversion element according to claim 1, wherein the content of the compound represented by the above chemical formula (1) is 5% by mass or more, based on the total mass of the hole transport layer.

Images