Perovskite solar cell, liquid composition, and hydrogen halide salt

Abstract

Provided are: a perovskite solar cell having high photoelectric conversion efficiency; a liquid composition used for manufacturing the perovskite solar cell; and a hydrogen halide salt that is suitably added to the liquid composition.　In a photoelectric conversion layer containing a perovskite compound in this perovskite solar cell, passivation is carried out by at least one passivation material selected from hydrogen halide salts represented by formula (1) and hydrogen halide salts of amines having a fluorinated alkyl group. (1): R1R2N-C(=NH)-NH-C(=NH)-NH2·HX (in formula (1), R1 and R2 each independently represent a hydrogen atom or a monovalent organic group, and X represents a halogen atom.)

Description

Perovskite solar cell, liquid composition, and hydrogen halide salt

[0001] The present invention relates to a perovskite solar cell, a liquid composition, and a hydrogen halide salt.

[0002] The use of solar cells is expanding as an energy source with a low environmental impact. In various solar cells, a passivation layer is sometimes provided to repair defects in the photoelectric conversion layer in order to suppress carrier recombination loss caused by defects at the interface of the photoelectric conversion layer. Perovskite solar cells, which have a photoelectric conversion layer mainly made of a perovskite compound, are known as one type of solar cell. It has been proposed to use an organic material that ionizes and bonds to defects in the perovskite compound as a passivation material (passivator) to repair defects in the perovskite compound (see, for example, Patent Document 1).

[0003] Forming a passivation layer after forming a photoelectric conversion layer complicates the solar cell manufacturing process and increases manufacturing costs. In response to this, Patent Document 1 proposes simultaneously forming a photoelectric conversion layer and a passivation layer by applying a perovskite precursor liquid in which a precursor for forming a perovskite compound and a passivation material are dissolved in a solvent, and then removing the solvent.

[0004] Special table 2017-501576 publication

[0005] However, further improvement in the photoelectric conversion efficiency of solar cells is required. To improve the photoelectric conversion efficiency, improvements are also required in materials that have a passivation effect on the photoelectric conversion layer that constitutes the passivation layer.

[0006] An object of the present invention is to provide a perovskite solar cell with high photoelectric conversion efficiency, a liquid composition used in producing the perovskite solar cell, and a hydrogen halide salt that can be suitably added to the liquid composition.

[0007] A perovskite solar cell according to one embodiment of the present invention is a perovskite solar cell that includes a photoelectric conversion layer containing a perovskite compound, and in which one or more passivation materials selected from a hydrohalide salt represented by the following formula (1) and a hydrohalide salt of an amine having a fluoroalkyl group are present on the surface and / or inside of the photoelectric conversion layer: １ R ２ NC(=NH)-NH-C(=NH)-NH ２ ・HX...(1) (In formula (1), R １ , and R ２ are each independently a hydrogen atom or a monovalent organic group, and X is a halogen atom.

[0008] In the above-mentioned perovskite solar cell, the passivation material contains a hydrohalide salt represented by the above formula (1), and R １ , and R ２ One of these may be an aromatic hydrocarbon group and the other may be a hydrogen atom.

[0009] In the above-mentioned perovskite solar cell, the passivation material may be hydroiodide.

[0010] The above-described perovskite solar cell may include a plate-shaped or sheet-shaped substrate, a first electrode layer laminated on one main surface of the substrate, a hole transport layer laminated on the first electrode layer, a photoelectric conversion layer laminated on the hole transport layer, an electron transport layer laminated on the photoelectric conversion layer, and a second electrode layer laminated on the electron transport layer.

[0011] A liquid composition according to one embodiment of the present invention is a liquid composition comprising one or more passivation materials selected from hydrohalide salts represented by the following formula (1) and hydrohalide salts of amines having a fluorinated alkyl group, and a solvent. １ R ２ NC(=NH)-NH-C(=NH)-NH ２ ・HX...(1) (In formula (1), R １ , and R ２ are each independently a hydrogen atom or a monovalent organic group, and X is a halogen atom.

[0012] The liquid composition described above may further contain a perovskite precursor.

[0013] The liquid composition may further contain a hole transport material.

[0014] In the liquid composition, the hydrohalide may be a hydroiodide.

[0015] A method for manufacturing a perovskite solar cell according to one aspect of the present invention includes the steps of: applying a liquid composition containing a perovskite precursor, or a perovskite precursor and a hole transport material, to a laminate having at least a plate- or sheet-like substrate and a first electrode layer; and volatilizing the solvent from the coating film made of the liquid composition to produce crystals of a perovskite compound.

[0016] A hydrohalide salt according to one embodiment of the present invention is a hydrohalide salt represented by the following formula (1): １ R ２ NC(=NH)-NH-C(=NH)-NH ２ ・HX...(1) (In formula (1), R １ , and R ２ are each independently a hydrogen atom or a monovalent organic group, and X is a halogen atom.

[0017] In the above hydrohalide salts, R １ , and R ２ One of these may be an aromatic hydrocarbon group and the other may be a hydrogen atom.

[0018] The hydrohalide salt may be a hydroiodide salt.

[0019] The present invention can provide a perovskite solar cell with high photoelectric conversion efficiency, a liquid composition used in the production of the perovskite solar cell, and a hydrogen halide salt that can be suitably added to the liquid composition.

[0020] 1 is a schematic cross-sectional view showing the configuration of an embodiment of a solar cell according to the present invention; 2 is a flowchart showing the procedure of an embodiment of a solar cell manufacturing method according to the present invention;

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the dimensions of various components in the drawings have been adjusted for clarity and convenience. In addition, in embodiments described later, components similar to those in embodiments described earlier will be designated by the same reference numerals, and redundant description will be omitted.

[0022] 1 is a schematic cross-sectional view showing a suitable configuration of a perovskite solar cell 1 according to an embodiment of the present invention. The perovskite solar cell 1 shown in Fig. 1 comprises a plate- or sheet-shaped substrate 10, a first electrode layer 20 laminated on one main surface (the lower side in Fig. 1 ) of the substrate 10, a hole transport layer 30 laminated on one surface of the first electrode layer 20, a photoelectric conversion layer 40 laminated on one surface of the hole transport layer 30 and containing a perovskite compound, an electron transport layer 50 laminated on one side of the photoelectric conversion layer 40, and a second electrode layer 60 (cathode) laminated on one side of the electron transport layer 50.

[0023] In the perovskite solar cell 1, one or more types selected from a hydrohalide salt represented by the following formula (1) and a hydrohalide salt of an amine having a fluoroalkyl group are present as a passivation material on the surface and / or inside of the photoelectric conversion layer 40. The passivation material is an organic compound that suppresses defects in the photoelectric conversion layer by interacting with anionic species and cationic species on the surface and / or inside of the photoelectric conversion layer 40. Passivation of defects in the photoelectric conversion layer suppresses recombination of charges and holes, improving photoelectric conversion efficiency.

[0024] The passivation material may be present as a layer having a certain thickness on the surface of the photoelectric conversion layer 40, or may be present as a single molecule or a complex of multiple molecules inside the photoelectric conversion layer 40 (for example, inside the perovskite crystal bulk or at the crystal grain boundaries). The presence of the passivation material in the photoelectric conversion layer 40 may be in any of the above-mentioned modes. In any of the above-mentioned modes, the photoelectric conversion efficiency of the perovskite solar cell 1 is improved.

[0025] When the passivation material is present as a layer on the surface of the photoelectric conversion layer 40, the surface of the photoelectric conversion layer 40 is passivated by applying the passivation material to the interface between the hole transport layer 30 and the photoelectric conversion layer 40 and / or the interface between the electron transport layer 50 and the photoelectric conversion layer 40. In this case, the layer made of the passivation material may be present on at least a part of the main surface of the photoelectric conversion layer 40 or on the entire main surface, and is preferably present on the entire main surface of the photoelectric conversion layer 40.

[0026] When the passivation material is present inside the photoelectric conversion layer 40 as a single molecule or a complex of multiple molecules, the interaction between the passivation material as a single molecule or a complex of multiple molecules and the perovskite crystals passivates defects inside the photoelectric conversion layer 40. In this case, typically, the passivation material acts on the crystal lattice of the perovskite compound in the photoelectric conversion layer 40, thereby passivating the crystal grain boundaries and the like.

[0027] The structure of the perovskite solar cell 1 is not particularly limited as long as one or more types selected from the group consisting of a hydrohalide salt represented by the formula (1) described below and a hydrohalide salt of an amine having a fluoroalkyl group are present as a passivation material on the surface and / or inside of the photoelectric conversion layer 40.

[0028] The substrate 10 is a structure that supports the other layers and ensures the strength of the perovskite solar cell 1. When the perovskite solar cell 1 receives light from the substrate 10 side, the substrate 10 is formed from a transparent material. Specifically, when the strength of the solar cell 1 is important, the substrate 10 is preferably made of glass. When the lightweight and flexible properties of the solar cell 1 are important, the substrate 10 is preferably made of resin. Preferred resin materials for the substrate 10 include polyimide, polyamide, and polyethylene terephthalate. From the viewpoint of dimensional stability, polyimide is particularly preferable. When product cost is important, polyethylene terephthalate is particularly preferable. Furthermore, when the perovskite solar cell 1 receives light from the second electrode layer 60 side, the substrate 10 may be formed from a composite material including a metal layer, or the like.

[0029] The first electrode layer 20 collects holes generated in the photoelectric conversion layer 40 through the hole transport layer 30 and outputs them to the outside. The first electrode layer 20 may be formed of a transparent conductive oxide (TCO) having electrical conductivity and optical transparency. Examples of transparent conductive oxides that can be used to form the first electrode layer 20 include indium oxide, tin oxide, zinc oxide, titanium oxide, and composite oxides thereof. Among these, indium-based composite oxides containing indium oxide, zinc oxide, tungsten oxide, molybdenum oxide, or the like as their main components, and fluorine-doped tin oxide are preferred. From the viewpoints of high electrical conductivity and transparency, indium oxide is particularly preferred. The first electrode layer 20 is preferably subjected to a surface treatment, such as ozone treatment, to improve the formability of the hole transport layer 30. The first electrode layer 20 may have a multilayer structure having a p-type oxide semiconductor layer, for example, containing nickel oxide, niobium oxide, or the like as its main component, on its surface.

[0030] The hole transport layer 30 effectively transports holes generated in the photoelectric conversion layer 40 to the first electrode layer 20. The hole transport layer 30 is typically a self-assembled monolayer made of a compound that constitutes the hole transport layer 30.

[0031] The compound constituting the hole transport layer 30 is not particularly limited as long as it is a compound conventionally used to form hole transport layers in perovskite solar cells. A carbazole compound is preferred as a compound constituting a self-assembled monolayer as the hole transport layer 30. The carbazole compound preferably has a functional group such as a phosphonic acid group, a carboxy group, a sulfonic acid group, a boric acid group, a hydroxy group, an amino group, or a mercapto group. Among these, the phosphonic acid group, the carboxy group, the amino group, and the mercapto group are particularly preferred, with the phosphonic acid group and the mercapto group being even more preferred. When the carbazole compound has these functional groups, the interaction between these functional groups and the surface of the first electrode layer 20 facilitates the formation of a self-assembled monolayer as the hole transport layer 30.

[0032] When the hole transport layer 30 contains a carbazole compound, the carbazole compound is selected from the group consisting of N-(2-phosphonoethyl)carbazole (2PACz), N-(2-phosphonoethyl)-3,6-dimethoxycarbazole (MeO-2PACz), N-(2-phosphonoethyl)-3,6-dimethylcarbazole (Me-2PACz), N-(3-phosphonopropyl)carbazole (3PACz), N-(3-phosphonopropyl)-3,6-dimethoxycarbazole (MeO-3PACz), and N-(3-phosphonopropyl)-3,6 Preferably, the compound contains one or more selected from the group consisting of N-(4-phosphonobutyl)-3,6-dimethylcarbazole (Me-3PACz), N-(4-phosphonobutyl)carbazole (4PACz), N-(4-phosphonobutyl)-3,6-dimethoxycarbazole (MeO-4PACz), and N-(4-phosphonobutyl)-3,6-dimethylcarbazole (Me-4PACz), and more preferably contains one or more selected from the group consisting of 2PACz, MeO-2PACz, Me-2PACz, MeO-4PACz, and Me-4PACz.

[0033] The hole transport layer 30 may contain, as a compound other than the carbazole compound, a phosphonic acid compound such as n-butylphosphonic acid, n-pentylphosphonic acid, n-hexylphosphonic acid, n-octylphosphonic acid, n-decylphosphonic acid, n-octadecylphosphonic acid, 2-ethylhexylphosphonic acid, methoxymethylphosphonic acid, 3-acryloyloxypropylphosphonic acid, 11-hydroxyundecylphosphonic acid, or 1H,1H,2H,2H-perfluorophosphonic acid, or a compound such as acetic acid, propionic acid, isobutyric acid, nonanoic acid, fluoroacetic acid, α-chloropropionic acid, or glyoxylic acid. These compounds may be used alone or in combination of two or more.

[0034] The self-assembled monolayer serving as the hole transport layer 30 more preferably contains one or more selected from the group consisting of 2PACz, MeO-2PACz, and Me-4PACz, and even more preferably contains 2PACz and / or MeO-2PACz. A self-assembled monolayer serving as the hole transport layer 30 containing one or more selected from the group consisting of 2PACz, MeO-2PACz, and Me-4PACz has sufficient hole-selective function, and therefore, even when the photoelectric conversion layer 40 is directly laminated thereon, it is easy to efficiently extract holes while blocking electrons.

[0035] When the hole transport layer 30 contains 2PACz and MeO-2PACz, the lower limit of the mass ratio of 2PACz to MeO-2PACz (proportion of 2PACz) in the hole transport layer 30 is preferably 1:99, more preferably 10:90. On the other hand, the upper limit of the mass ratio of 2PACz to MeO-2PACz is preferably 60:40, more preferably 55:45, even more preferably 50:50, and particularly preferably 30:70. When the mass ratio of 2PACz to MeO-2PACz is within the above range, it is easy to form a hole transport layer 30 with few pinholes, and further, the hole transport layer 30 has appropriate wettability with a photoelectric conversion layer-forming material solution for forming the photoelectric conversion layer 40, making it easy to appropriately form the photoelectric conversion layer 40. This optimizes the generation of carriers (holes and electrons) by the photoelectric conversion layer 40 and the transfer of holes from the photoelectric conversion layer 40 to the hole transport layer 30, thereby improving the photoelectric conversion efficiency of the perovskite solar cell 1.

[0036] The hole transport layer 30 can be formed by applying and drying a coating liquid containing the above-described compounds constituting the hole transport layer. As described above, the coating liquid preferably contains a carbazole compound. The carbazole compound preferably contains one or more compounds selected from the group consisting of N-(2-phosphonoethyl)carbazole (2PACz), N-(2-phosphonoethyl)-3,6-dimethoxycarbazole (MeO-2PACz), and N-(4-phosphonoethyl)-3,6-dimethylcarbazole (Me-4PACz), and more preferably contains 2PACz and / or MeO-2PACz.

[0037] The coating liquid used to form the hole transport layer 30 usually contains an organic solvent. Examples of the organic solvent include alcohols such as methanol, ethanol, isopropanol, and butanol; ethers such as diethyl ether, diisopropyl ether, tetrahydrofuran, 4-methyltetrahydropyran, 2-methyltetrahydrofuran, and cyclopentyl methyl ether; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; amides such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP); esters such as ethyl acetate, butyl acetate, isoamyl acetate, and γ-butyrolactone (GBL); nitriles such as acetonitrile and 3-methoxypropionitrile; aromatic compounds such as benzene, toluene, chlorobenzene, and nitrobenzene; chlorinated hydrocarbons such as dichloromethane, chloroform, and 1,2-dichloroethane; and fluorinated hydrocarbons such as chlorofluorocarbons, hydrochlorofluorocarbons, and hydrofluorocarbons.

[0038] The total concentration of the compounds that constitute the self-assembled monolayer (hole transport layer 30) contained in the coating liquid is preferably 5.0 mg / mL or less.

[0039] When the coating liquid contains a perovskite precursor (described later) used to form the photoelectric conversion layer 40, the hole transport layer 30 and the photoelectric conversion layer 40 can be formed simultaneously by applying the coating liquid to the first electrode layer 20, drying the coating liquid, and crystallizing the perovskite precursor. In this case, the material that constitutes the hole transport layer 30, which is contained in the coating liquid, forms a self-assembled monolayer on the first electrode layer 20 during the process of forming the photoelectric conversion layer 40.

[0040] A layer of a passivation material may be present on the principal surface of the photoelectric conversion layer 40 facing the hole transport layer 30. It is preferable that a layer of a passivation material be present on the principal surface of the photoelectric conversion layer 40 facing the hole transport layer 30. When forming a layer of a passivation material on the principal surface of the photoelectric conversion layer 40 facing the hole transport layer 30, for example, a layer of a passivation material may be formed on the hole transport layer 30, and then the photoelectric conversion layer 40 may be formed on the layer of the passivation material. Specifically, a liquid composition containing a passivation material is applied to the hole transport layer 30, and the resulting coating film is dried to form a layer of the passivation material. The method for applying the liquid composition is not particularly limited. Application can be performed using, for example, a spin coater, a die coater, a bar coater, or the like. The temperature during application is not particularly limited, but is preferably −20°C to 200°C, and more preferably 0°C to 150°C. The application time is not particularly limited, but is preferably from 1 second to 24 hours, more preferably from 5 seconds to 1 hour.

[0041] As described above, the passivation material contains one or more compounds selected from the group consisting of hydrohalide salts represented by the following formula (1) and hydrohalide salts of amines having a fluorinated alkyl group. The passivation material may contain other compounds in addition to the one or more compounds selected from the group consisting of hydrohalide salts represented by the formula (1) and hydrohalide salts of amines having a fluorinated alkyl group. In the specification and claims of this application, "amine" is defined as a compound that does not fall under the category of a "biguanide compound."

[0042] R １ R ２ NC(=NH)-NH-C(=NH)-NH ２ ・HX...(1) (In formula (1), R １ , and R ２ are each independently a hydrogen atom or a monovalent organic group, and X is a halogen atom.

[0043] In formula (1), R １ , and R ２are each independently a hydrogen atom or a monovalent organic group. Examples of the monovalent organic group include an alkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, a heterocyclic group which may have a substituent, an aliphatic acyl group, and an aromatic acyl group. Examples of the substituent that the alkyl group may have include an alkoxy group having 1 to 6 carbon atoms, a halogen atom, a nitro group, and a cyano group. Examples of the substituent that the aromatic hydrocarbon group and the heterocyclic group may have include an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a halogenated alkyl group having 1 to 6 carbon atoms, a halogenated alkoxy group having 1 to 6 carbon atoms, an aliphatic acyl group having 2 to 6 carbon atoms, an aliphatic acyloxy group having 2 to 6 carbon atoms, a halogen atom, a nitro group, and a cyano group.

[0044] Specific examples of the substituent include alkyl groups having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, and an n-hexyl group; alkoxy groups having 1 to 6 carbon atoms, such as a methoxy group, an ethoxy group, an n-propyloxy group, an isopropyloxy group, an n-butyloxy group, an isobutyloxy group, a sec-butyloxy group, a tert-butyloxy group, an n-pentyloxy group, and an n-hexyloxy group; and alkyl groups having 1 to 6 carbon atoms, such as a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a chloromethyl group, a dichloromethyl group, a trichloromethyl group, a bromomethyl group, a dibromomethyl group, and a tribromethyl group. halogenated alkoxy groups having from 1 to 6 carbon atoms, such as a fluoromethoxy group, a difluoromethoxy group, a trifluoromethoxy group, a chloromethoxy group, a dichloromethoxy group, a trichloromethoxy group, a bromomethoxy group, a dibromomethoxy group, and a tribromethoxy group; aliphatic acyl groups having from 2 to 6 carbon atoms, such as an acetyl group, a propionyl group, a butanoyl group, a pentanoyl group, and a hexanoyl group; aliphatic acyloxy groups having from 2 to 6 carbon atoms, such as an acetyloxy group, a propionyloxy group, a butanoyloxy group, a pentanoyloxy group, and a hexanoyloxy group; halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom; a nitro group; and a cyano group.

[0045] R １ , and R ２ As the monovalent organic group, an alkyl group which may have a substituent and an aromatic hydrocarbon group which may have a substituent are preferred, and an aromatic hydrocarbon group which may have a substituent is particularly preferred.

[0046] Specific preferred examples of the aromatic hydrocarbon group which may have a substituent include a phenyl group; naphthyl groups such as a naphthalen-1-yl group and a naphthalen-2-yl group; methylphenyl groups such as a 2-methylphenyl group, a 3-methylphenyl group, and a 4-methylphenyl group; dimethylphenyl groups such as a 2,3-dimethylphenyl group, a 2,4-dimethylphenyl group, a 2,5-dimethylphenyl group, a 2,6-dimethylphenyl group, a 3,4-dimethylphenyl group, and a 3,5-dimethylphenyl group; methoxyphenyl groups such as a 2-methoxyphenyl group, a 3-methoxyphenyl group, and a 4-methoxyphenyl group; a 2,3-dimethoxyphenyl group, a 2,4-dimethoxyphenyl group, a 2,5-dimethoxyphenyl group, a 2,6-dimethoxyphenyl group, a 3,4-dimethoxyphenyl group, and ...4-dimethoxyphenyl group; dimethoxyphenyl groups such as a 2-chlorophenyl group, a 3-chlorophenyl group, and a 4-chlorophenyl group; dichlorophenyl groups such as a 2,3-dichlorophenyl group, a 2,4-dichlorophenyl group, a 2,5-dichlorophenyl group, a 2,6-dichlorophenyl group, a 3,4-dichlorophenyl group, and a 3,5-dichlorophenyl group; bromophenyl groups such as a 2-bromophenyl group, a 3-bromophenyl group, and a 4-bromophenyl group; and dibromophenyl groups such as a 2,3-dibromophenyl group, a 2,4-dibromophenyl group, a 2,5-dibromophenyl group, a 2,6-dibromophenyl group, a 3,4-dibromophenyl group, and a 3,5-dibromophenyl group.

[0047] Among these groups, preferred are phenyl groups; naphthyl groups such as naphthalen-1-yl and naphthalen-2-yl groups; and methylphenyl groups such as 2-methylphenyl, 3-methylphenyl, and 4-methylphenyl groups, with phenyl groups, 2-methylphenyl, 3-methylphenyl, and 4-methylphenyl groups being more preferred.

[0048] In formula (1), R １ , and R ２ Preferably, one of these is an aromatic hydrocarbon group which may have a substituent, and the other is a hydrogen atom.

[0049] The hydrohalide salt represented by formula (1) is represented by the following formula (1-1): １ R ２ NC(=NH)-NH-C(=NH)-NH ２ ...(1-1) (In formula (1-1), R １ , and R ２ is R in formula (1). １ , and R ２ and a hydrohalic acid represented by HX.

[0050] Examples of the hydrohalic acid represented by HX include hydrofluoric acid, hydrochloric acid, hydrobromic acid, and hydroiodic acid, with hydrobromic acid and hydroiodic acid being preferred, and hydroiodic acid being more preferred.

[0051] Specific examples of suitable hydrohalides represented by formula (1) include H ２ NC(=NH)-NH-C(=NH)-NH ２ ・HI, Me-NH-C(=NH)-NH-C(=NH)-NH ２ ・HI, Et-NH-C(=NH)-NH-C(=NH)-NH ２ ・HI, Ph-NH-C(=NH)-NH-C(=NH)-NH ２ ・HI, o-Tol-NH-C(=NH)-NH-C(=NH)-NH ２ ・HI, m-Tol-NH-C(=NH)-NH-C(=NH)-NH ２ ・HI, p-Tol-NH-C(=NH)-NH-C(=NH)-NH ２ HI, (Me) ２ NC(=NH)-NH-C(=NH)-NH ２ HI, (Et) ２ NC(=NH)-NH-C(=NH)-NH ２ ・HI, (Ph) ２ NC(=NH)-NH-C(=NH)-NH ２ ・HI, (o-Tol) ２ NC(=NH)-NH-C(=NH)-NH ２ ・HI, (m-Tol) ２ NC(=NH)-NH-C(=NH)-NH ２HI, and (p-Tol) ２ NC(=NH)-NH-C(=NH)-NH ２ ・HI is one example.

[0052] In the above formula, Ph is a phenyl group. Me is a methyl group. Et is an ethyl group. o-Tol is an o-tolyl group (2-methylphenyl group). m-Tol is an m-tolyl group (3-methylphenyl group). p-Tol is a p-tolyl group (4-methylphenyl group).

[0053] Among these compounds, Me-NH-C(=NH)-NH-C(=NH)-NH ２ ・HI, Et-NH-C(=NH)-NH-C(=NH)-NH ２ ・HI, Ph-NH-C(=NH)-NH-C(=NH)-NH ２ ・HI, o-Tol-NH-C(=NH)-NH-C(=NH)-NH ２ ・HI, m-Tol-NH-C(=NH)-NH-C(=NH)-NH ２ ・HI, and p-Tol-NH-C(=NH)-NH-C(=NH)-NH ２ HI is preferred, Ph-NH-C(=NH)-NH-C(=NH)-NH ２ ・HI, o-Tol-NH-C(=NH)-NH-C(=NH)-NH ２ ・HI, m-Tol-NH-C(=NH)-NH-C(=NH)-NH ２ ・HI, and p-Tol-NH-C(=NH)-NH-C(=NH)-NH ２ HI is more preferred, Ph-NH-C(=NH)-NH-C(=NH)-NH ２ ・HI, and o-Tol-NH-C(=NH)-NH-C(=NH)-NH ２ HI is particularly preferred.

[0054] The method for producing the hydrohalide salt represented by formula (1) is not particularly limited. The hydrohalide salt represented by formula (1) can be obtained, for example, by mixing a solution or suspension containing the biguanide compound described above with a solution of hydrohalic acid represented by HX. The solvent or dispersion medium for dissolving or suspending the biguanide compound is not particularly limited as long as it is a liquid that does not react with hydrohalic acid. As the solvent or dispersion medium, in addition to organic solvents similar to those that may be contained in the coating liquid used to form the hole transport layer 30, pure water can also be used. The hydrohalic acid solution may be an aqueous solution or an organic solvent solution.

[0055] Hereinafter, hydrohalide salts of amines having a fluorinated alkyl group will be described. The structure of the amine having a fluorinated alkyl group is not particularly limited as long as the structure has a fluorinated alkyl group. The fluorinated alkyl group may be a linear fluorinated alkyl group or a branched fluorinated alkyl group. The amine having a fluorinated alkyl group may have two or more fluorinated alkyl groups, and preferably has one fluorinated alkyl group.

[0056] The fluorinated alkyl group may be a perfluoroalkyl group, or a group in which some of the hydrogen atoms in the alkyl group have been substituted with fluorine atoms.

[0057] Examples of amines having a fluorinated alkyl group include fluorinated alkylamines, di(fluorinated alkyl)amines, tri(fluorinated alkylamines), fluorinated alkylarylamines, and fluorinated alkoxyalkylamines.

[0058] The number of carbon atoms in the fluorinated alkyl group of the amine having a fluorinated alkyl group is not particularly limited as long as the consuming effect is not impaired. The number of carbon atoms in the fluorinated alkyl group is preferably 1 to 20, more preferably 1 to 16, even more preferably 2 to 12, and particularly preferably 2 to 8.

[0059] When the amine having a fluorinated alkyl group is a secondary amine or a tertiary amine, an organic group other than the fluorinated alkyl group may be bonded to the nitrogen atom together with the fluorinated alkyl group. Examples of the organic group other than the fluorinated alkyl group include an alkyl group having from 1 to 10 carbon atoms, an aromatic hydrocarbon group having from 6 to 10 carbon atoms, an alicyclic hydrocarbon group having from 3 to 10 carbon atoms, and a heterocyclic group having from 2 to 9 carbon atoms.

[0060] The hydrohalide salt of an amine having a fluorinated alkyl group may be any of hydrofluoride, hydrochloride, hydrobromide, and hydroiodide, of which hydrobromide and hydroiodide are preferred, and hydroiodide is more preferred.

[0061] A specific example of a hydrohalide salt of an amine having a fluorinated alkyl group is 1H,1H-undecafluorohexylamine hydroiodide (CF ３ (CF ２ ) ４ CH ２ NH ２ HI), 1H,1H-undecafluorohexylamine hydrochloride (CF ３ (CF ２ ) ４ CH ２ NH ２ HCl), (1H,1H-undecafluorohexylamine hydrobromide (CF ３ (CF ２ ) ４ CH ２ NH ２ HBr), 2,2,2-trifluoroethylamine hydroiodide (CF ３ CH ２ NH ２ HI), 2,2,2-trifluoroethylamine hydrochloride (CF ３ CH ２ NH ２ HCl), 2,2,2-trifluoroethylamine hydrobromide (CF ３ CH ２ NH ２ HBr), 1H,1H-heptafluorobutylamine hydroiodide (CF ３ (CF ２ )２ CH ２ NH ２ and hydrohalides of amine compounds containing a fluorinated alkyl group moiety, such as HCl.

[0062] The liquid composition contains, as a passivation material, one or more compounds selected from the hydrohalide salt represented by formula (1) and the hydrohalide salt of an amine having a fluorinated alkyl group. The liquid composition may contain, as a passivation material, one or more compounds selected from the hydrohalide salt represented by formula (1) and the hydrohalide salt of an amine having a fluorinated alkyl group, as well as the hydrohalide salt represented by formula (1) and the hydrohalide salt of an amine having a fluorinated alkyl group, as long as the desired effect is not impaired. The liquid composition may contain two or more passivation materials selected from the hydrohalide salt represented by formula (1) and the hydrohalide salt of an amine having a fluorinated alkyl group. Furthermore, the liquid composition may contain two or more compounds other than the hydrohalide salt represented by formula (1) and the hydrohalide salt of an amine having a fluorinated alkyl group.

[0063] Suitable examples of other compounds as passivation materials include various amines or their hydrohalides, such as hydrofluorides, hydrochlorides, hydrobromides, and hydroiodides, with hydrobromides and hydroiodides being preferred, and hydroiodides being more preferred.

[0064] Specific preferred examples of other compounds as passivation materials include n-butylamine hydrobromide, n-butylamine hydroiodide, n-hexylamine hydrobromide, n-hexylamine hydroiodide, n-decylamine hydrobromide, n-octadecylamine hydroiodide, pyridine hydrobromide, aniline hydroiodide, hydrazine dihydrobromide, ethylenediamine dihydroiodide, phenethylamine hydroiodide, 4-fluorophenethylamine hydroiodide, phenylenediamine dihydrochloride, diphenylamine hydrobromide, diphenylamine hydroiodide, benzylamine hydroiodide, and 4-diphenylaminophenethylamine hydroiodide.

[0065] As other compounds suitable as passivation materials, fluorine-containing amine compounds and salts thereof are also preferred. Specific examples of suitable fluorine-containing amine compounds include compounds having a fluorinated aromatic group and an amino acid group, such as pentafluorophenylethylalanine hydroiodide, and salts thereof; 1H,1H-undecafluorohexylamine (CF ３ (CF ２ ) ４ CH ２ NH ２ ), 2,2,2-trifluoroethylamine (CF ３ CH ２ NH ２ ), 1H,1H-heptafluorobutylamine (CF ３ (CF ２ ) ２ CH ２ NH ２ fluoroalkylamines such as 4-fluorophenylethylamine hydroiodide; compounds having a fluorinated aromatic group and an amino group, such as 4-fluorophenylethylamine hydroiodide, and salts thereof.

[0066] The desired effect can be achieved even if the passivation material is an amine compound rather than a hydrohalide, as described above. In this case, the amine compound interacts with lead ions and other elements that form the perovskite crystal through the unshared electron pair on the nitrogen atom, thereby passivating defects.

[0067] Among these other compounds, from the viewpoints of availability and the balance between cost and performance, amine compounds containing a fluorinated alkyl group moiety or compounds having a fluorinated aromatic group and an amino group are preferred.

[0068] When the liquid composition containing a passivation material contains a passivation material selected from the group consisting of the hydrogen halide salt represented by formula (1) and the hydrohalide salt of an amine having a fluorinated alkyl group, and other compounds, the ratio of the mass of the passivation material selected from the group consisting of the hydrogen halide salt represented by formula (1) and the hydrohalide salt of an amine having a fluorinated alkyl group to the total mass of the passivation material contained in the liquid composition is preferably 50 mass% or more, more preferably 70 mass% or more, even more preferably 80 mass% or more, particularly preferably 90 mass% or more, and most preferably 100 mass%.

[0069] The liquid composition containing the passivation material may contain the material that constitutes the hole transport layer 30 and / or the perovskite precursor.

[0070] When the liquid composition contains a passivation material and a material that constitutes the hole transport layer 30, the liquid composition is applied to the first electrode layer 20 to form a coating film, and then the coating film is dried, thereby forming the hole transport layer 30 and a layer made of the passivation material in this order on the first electrode layer 20.

[0071] When the liquid composition contains a passivation material and a perovskite precursor, the liquid composition is applied to the hole transport layer 30 to form a coating film, and then the coating film is dried to form the photoelectric conversion layer 40 containing the passivation material. The photoelectric conversion layer 40 formed in this manner may have the passivation material present on its surface and / or inside. As a result, defects on the surface and inside the photoelectric conversion layer 40 are suppressed by the passivation material.

[0072] When the liquid composition contains a passivation material, a material constituting the hole transport layer 30, and a perovskite precursor, the liquid composition is applied to the first electrode layer 20 to form a coating film, and then the coating film is dried, thereby forming the hole transport layer 30 and the photoelectric conversion layer 40 in this order on the first electrode layer 20. In this case, the passivation material may be present on both main surfaces of the photoelectric conversion layer 40 and / or inside the photoelectric conversion layer. As a result, defects on the surface and inside the photoelectric conversion layer 40 are suppressed by the passivation material. That is, a perovskite solar cell can be easily formed by a method comprising the steps of: applying a liquid composition containing a passivation material, a material constituting the hole transport layer 30, and a perovskite precursor onto the first electrode layer of a laminate having at least a plate- or sheet-like substrate 10 and a first electrode layer 20; and volatilizing the solvent from the coating film made of the liquid composition to produce crystals of a perovskite compound.

[0073] By using a liquid composition containing a passivation material, a material constituting the hole transport layer 30, and a perovskite precursor, defects in the photoelectric conversion layer 40 are passivated by the passivation material, and the hole transport layer 30 and the photoelectric conversion layer 40 can be formed simultaneously on the first electrode layer 20.

[0074] The photoelectric conversion layer 40 contains a perovskite compound that performs photoelectric conversion and absorbs incident light to generate photocarriers. The perovskite compound contained in the photoelectric conversion layer 40 is not particularly limited as long as the desired effect is not impaired, and can be appropriately selected from well-known compounds. As a preferred example, the perovskite compound contains an organic atomic group A containing at least one of a monovalent organic ammonium ion and an amidinium-based ion, a metal atom B that generates a divalent metal ion, and a halogen atom X containing at least one of an iodide ion I, a bromide ion Br, a chloride ion Cl, and a fluoride ion F, and has a structure of ABX ３ The organic atomic group A is not particularly limited as long as the desired effect is not impaired, and can be appropriately selected from well-known organic compounds. Examples of the organic atomic group A include methylammonium MA (CH ３ NH３ ), Formamidinium FA (CH ３ N ２ ) etc.

[0075] The metal atom B is not particularly limited as long as it is a metal atom that has conventionally been used to form perovskite compounds. Preferred examples of the metal atom B include lead (Pb) and tin (Sn). When emphasis is placed on the power generation efficiency of the perovskite solar cell 1, it is preferable that the metal atom B be mainly lead. The lower limit of the proportion of lead in the metal atom B is preferably 50 wt %, more preferably 80 wt %, and even more preferably 90 wt %, in order to achieve the desired performance. On the other hand, when emphasis is placed on the environmental impact of lead, it is preferable that the metal atom B be mainly tin (Sn). The lower limit of the proportion of tin in the metal atom B is preferably 50 wt %, more preferably 80 wt %, and particularly preferably 90 wt %, in order to achieve the desired performance.

[0076] The halogen atom is not particularly limited. The halogen atom X is preferably at least one of iodide I, bromide Br, and chloride Cl. Furthermore, substituting a part or all of the organic atomic group A with an alkali metal Am has also been considered, and such a perovskite compound can also be used. The alkali metal Am is not particularly limited. Examples of preferred alkali metals Am include potassium K, cesium Cs, and rubidium Rb. Among these, when emphasis is placed on the durability and water resistance of the perovskite solar cell 1, cesium Cs and rubidium Rb are preferred as the alkali metal Am, and cesium Cs is particularly preferred from the standpoints of cost and availability.

[0077] Specifically, preferred perovskite compounds include, for example, MAPbI ３ , MAPbBr ３ , MAPbCl ３ Methylammonium lead halides (MAPbX) such as ３ ), and FAPbI ３ , FAPbBr ３ , FAPbCl ３ Formamidinium lead halide (FAPbX) ３The halogen atom X may contain multiple types, and the organic atomic group A may be FA containing both methylammonium and formamidinium. ｙ MA １－ｙ PbX ３ In addition, when the alkali metal Am is contained, Am ｙ FA ｚ MA １－ｙ－ｚ PbIX, Am ｙ FA １－ｙ Am may be a single type of Cs, Rb, or K, or may contain a plurality of types of Am (where y and z are any positive integers).

[0078] When a passivation material is present on the main surface of the photoelectric conversion layer 40 facing the electron transport layer 50, the action of the passivation material at the interface between the photoelectric conversion layer 40 and the electron transport layer 50 prevents recombination of charge carriers at the interface between the photoelectric conversion layer 40 and the electron transport layer 50, and promotes the arrival of electrons at the electron transport layer 50.

[0079] As the passivation material present on the main surface of the photoelectric conversion layer 40 on the electron transport layer 50 side, the same material as that present on the main surface of the photoelectric conversion layer 40 on the hole transport layer 30 side can be used.

[0080] When the passivation material is present in a layer on the main surface of the photoelectric conversion layer 40 facing the electron transport layer 50, the passivation material can be arranged in a layer on the main surface of the photoelectric conversion layer 40 facing the electron transport layer 50 by applying a liquid composition containing the passivation material and an organic solvent to the photoelectric conversion layer 40 and drying it, just as when the passivation material is present in a layer on the main surface of the photoelectric conversion layer 40 facing the hole transport layer 30.

[0081] As described above, when a perovskite precursor is contained in a liquid composition containing a passivation material, the liquid composition is applied to the hole transport layer 30, and then dried, and the perovskite precursor is crystallized, whereby the grain boundaries on both main surfaces of the photoelectric conversion layer 40 and within the photoelectric conversion layer 40 can be passivated with the passivation material.

[0082] Furthermore, when the passivation material is an ionizable nitrogen-containing compound, the ionized passivation material acts on defects in the perovskite crystals of the photoelectric conversion layer 40. Furthermore, when the passivation material contained in the liquid composition containing a perovskite precursor is a hydrohalide, the hydrohalide easily bonds with the perovskite precursor, making it easy to form a homogeneous liquid composition.

[0083] When the liquid composition contains a passivation material and a perovskite precursor, it is preferable that the liquid composition contains a fluorine-containing amine compound or a salt thereof as the passivation material, since this facilitates deposition of the passivation material at the interface or surface of the perovskite polycrystal by utilizing the hydrophobic interaction of fluorine atoms. In this case, the passivation material is easily present on both main surfaces of the photoelectric conversion layer 40.

[0084] The content of fluorine atoms in the fluorine-containing amine compound is preferably 1 mass % or more, more preferably 5 mass % or more, and even more preferably 10 mass % or more, in terms of the mass of fluorine atoms relative to the molecular weight of each compound. When the fluorine-containing amine compound and its salt contain fluorine atoms in the above ratio, sufficient hydrophobic interaction makes it easy for the fluorine-containing amine compound to precipitate on the perovskite crystal surface.

[0085] The electron transport layer 50 effectively transmits electrons and transfers them to the second electrode layer 60. The material constituting the electron transport layer 50 is not particularly limited as long as the desired effect is not impaired. The material constituting the electron transport layer 50 can be appropriately selected from various compounds conventionally used to form electron transport layers in perovskite solar cells. The electron transport layer 50 is preferably formed from a material mainly composed of, for example, fullerene or naphthalene diimide. Examples of fullerenes include C60, C70, and their hydrides, oxides, metal complexes, and derivatives with alkyl groups added thereto, such as PCBM ([6,6]-Phenyl-C61-Butyric Acid Methyl Ester). Furthermore, a hole-blocking layer such as pasocuproine (BCP), lithium fluoride (LiF), or magnesium fluoride (MgF) may be provided between the electron transport layer 50 and the second electrode layer 60.２ ), tin oxide (SnO ２ ), aluminum-doped zinc oxide (ZnO), titanium oxide (TiO ２ The inorganic oxide layer may be doped with another metal material. The hole blocking layer material is not limited to these.

[0086] When the perovskite solar cell 1 receives light from the side of the substrate 10, the second electrode layer 60 preferably includes a metal layer made of, for example, copper in order to reduce electrical resistance. The metal constituting the metal layer is not limited to copper. Furthermore, when the perovskite solar cell 1 receives light from the side of the second electrode layer 60, the second electrode layer 60 may be made of a transparent conductive oxide.

[0087] The perovskite solar cell 1 having the above configuration can be manufactured by an embodiment of the solar cell manufacturing method shown in FIG. 2 .

[0088] Hereinafter, as a preferred manufacturing method, a method of simultaneously forming the hole transport layer 30 and the photoelectric conversion layer 40 using a liquid composition containing a perovskite precursor and a material that constitutes the hole transport layer 30 together with a passivation material will be described.

[0089] The solar cell manufacturing method of this embodiment includes a first electrode layer forming step (step S11), a liquid composition applying step (step S12), a crystallization step (step S13), an electron transport layer forming step (step S14), and a second electrode layer forming step (step S15).

[0090] In the first electrode layer formation process of step S11, a first electrode layer 20 is formed on one main surface of the substrate 10. The first electrode layer 20 can be deposited using a vacuum film-forming technique such as sputtering. In the first electrode layer process, it is preferable to modify the surface of the deposited first electrode layer 20 to facilitate the formation of the hole transport layer 30 in the next process. Specific methods for modifying the surface of the first electrode layer 20 include, for example, surface hydroxylation by ultraviolet-ozone treatment or ozone water washing, film formation by a vacuum film-forming technique such as sputtering of an oxide such as nickel oxide, which is prone to grow a self-assembled film, film formation by a coating technique of oxide nanoparticles, and heat treatment to activate the surface to facilitate the growth of a self-assembled film and remove impurities.

[0091] In the liquid composition application step of step S12, a liquid composition containing a perovskite precursor and a material for forming the hole transport layer 30, together with a passivation material, is applied onto the first electrode layer 20. The perovskite precursor is as described above. The liquid composition may further contain a hydrochloride that promotes crystal growth of the perovskite compound.

[0092] The liquid composition contains an organic solvent. Examples of organic solvents include amide solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP); sulfoxides such as dimethyl sulfoxide (DMSO), diethyl sulfoxide, and dibutyl sulfoxide; esters such as ethyl acetate, butyl acetate, amyl acetate, and γ-valerolactone (GBL); and aprotic polar solvents such as acetonitrile. These organic solvents may be used alone or in combination, and may further contain other types of organic solvents. The boiling points of these organic solvents are preferably as low as possible because they must be distilled off during the formation of the perovskite crystal. Specifically, the boiling point under atmospheric pressure is preferably 300°C or lower, more preferably 200°C or lower, and even more preferably 180°C or lower. When an organic solvent having such a boiling point is used, the organic solvent is less likely to remain in the perovskite crystal, facilitating the production of a perovskite solar cell 1 with the desired performance. The concentration of the perovskite precursor in the liquid composition is related to the conditions of the crystallization step. The solids concentration of the perovskite precursor in the liquid composition is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by weight or more. When the solids concentration of the perovskite precursor in the liquid composition is within this range, the organic solvent can be volatilized with less energy when forming the photoelectric conversion layer 40, and the perovskite solar cell 1 can be produced at low cost while reducing the environmental impact.

[0093] The perovskite precursor contains a metal halide BX and at least one of a halogenated organic compound AX and an alkali metal halide AmX in a predetermined ratio. Lead halide is preferably used as the metal halide BX. Formamidine hydrohalide and methylamine hydrohalide are preferably used as the halogenated organic compound AX, and cesium iodide is preferably used as the alkali metal halide AmX. The molar concentration of the metal atom B is preferably 0.5 mol% or more and 10 mol% or less in excess of the sum of the molar concentration of the organic compound and the molar concentration of the alkali metal Am. This expels other materials to the front and back interfaces of the layer made of the perovskite precursor during the crystallization process, thereby preventing a decrease in photoelectric conversion efficiency due to other materials remaining in the perovskite crystal.

[0094] When the liquid composition contains a perovskite precursor together with a passivation material, the passivation material is more likely to reach areas where defects exist on at least one of the surface, grain boundaries, and within the crystals of the photoelectric conversion layer 40 .

[0095] The hydrochloride promotes the crystallization of the perovskite compound and increases the grain size of the perovskite crystals. This reduces the area of ​​the grain boundaries in the photoelectric conversion layer 40 and suppresses a decrease in photoelectric conversion efficiency due to impurities between the perovskite crystals. Examples of hydrochlorides include methylammonium hydrochloride (MACl), formamidinium hydrochloride (FACl), and methylenediaminium hydrochloride (MDACl). ２ ) or the like is used. The portion other than the hydrochloride salt preferably has a size equal to or smaller than the crystal lattice of the perovskite crystal and has an amino group. The concentration of the hydrochloride salt in the liquid composition can be 1 mol % or more and 40 mol % or less relative to the molar concentration of the ion of the metal atom B in the perovskite compound. The liquid composition can be applied using, for example, a spin coater, a die coater, a bar coater, or the like.

[0096] In the crystallization step of step S13, the coating film made of the liquid composition is dried (the solvent is evaporated) to produce crystals of the perovskite compound. This results in the formation of a photoelectric conversion layer 40 mainly made of the perovskite compound, whose defect structure has been repaired by the passivation material, and also forms the hole transport layer 30. As a method for promoting the production of crystals of the perovskite compound in the coating film made of the liquid composition, it is preferable to employ, for example, poor solvent quenching, vacuum quenching, gas quenching, laser treatment, etc. In the crystallization step of step S13, the dried coating film of the liquid composition may be further heated.

[0097] In the electron transport layer forming step S14, the electron transport layer 50 is formed by a method such as coating or vacuum deposition. A hole blocking layer may be formed on the electron transport layer 50 by vacuum deposition or atomic deposition.

[0098] In the second electrode layer forming step S15, the second electrode layer 60 is formed by a method such as sputtering, vacuum deposition, plating, or coating depending on the material used.

[0099] The perovskite solar cell described above exhibits high photoelectric conversion efficiency.

[0100] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and various modifications and variations are possible. The solar cell according to the present invention may include an additional functional layer. For example, the electron transport layer may be omitted in the perovskite solar cell. Furthermore, the perovskite solar cell may be a tandem solar cell that uses a photoelectric converter such as a crystalline silicon solar cell as a substrate.

[0101] The present invention will be specifically described below based on examples, but the present invention is not limited to the following examples.

[0102] Example 1-1 Synthesis of Biguanide Passivator P-1 (o-Tolylbiguanide Hydrogen Iodide) Under a nitrogen atmosphere, an aqueous solution (1.17 g) of hydroiodic acid with a concentration of approximately 57% by mass was added dropwise to a suspension of o-tolylbiguanide (1.00 g) dispersed in pure water (7.5 g) while stirring the suspension. After stirring the reaction solution for 2 days, the precipitate was filtered. The filtered precipitate was washed with pure water and dried under reduced pressure to obtain biguanide passivator P-1 as a white solid. The obtained biguanide passivator P-1 １ H-NMR was as follows: １ H-NMR (400MHz, DMSO-d ６ ): δ = 8.65 (br s, 1H), 7.32 (d, 1H), 7.23 (d, 1H), 7.19 (td, 1H), 7.11 (td, 1H), 6.99 (br d, 5H), 2.23 (s, 3H),

[0103] Example 1-2 Synthesis of Biguanide Passivator P-2 (Phenylbiguanide Hydrogen Iodide) Under a nitrogen atmosphere, an aqueous solution (1.26 g) of hydroiodic acid with a concentration of approximately 57% by mass was added dropwise to a suspension in which phenylbiguanide (0.993 g) was dispersed in pure water (8.2 g) while stirring the suspension. The reaction solution was stirred for two days, and then the precipitate was filtered. The filtered precipitate was washed with pure water and dried under reduced pressure to obtain biguanide passivator P-2 as a white solid. The obtained biguanide passivator P-2 １ H-NMR was as follows: １ H-NMR (400MHz, DMSO-d ６ ): δ = 9.09 (br s, 1H), 7.32 (m, 4H), 7.18 (br s, 3H), 7.11-7.03 (m, 2H), 6.90 (br s, 2H),

[0104] Example 1-3 Synthesis of Biguanide Passivator P-3 (3,5-Difluorophenylbiguanide Hydrogen Iodide) Under a nitrogen atmosphere, an aqueous solution (4.50 g) of hydroiodic acid with a concentration of approximately 57% by mass was added dropwise to a suspension of 3,5-difluorophenylbiguanide (0.500 g) dispersed in pure water (1.0 g) while stirring the suspension. The reaction solution was stirred for 5 days, and then the precipitate was filtered. The filtered precipitate was washed with pure water and dried under reduced pressure to obtain biguanide passivator P-3 as a white solid. The obtained biguanide passivator P-3 １ H-NMR was as follows: １ H-NMR (400MHz, DMSO-d ６ ): δ = 7.67 (br s, 4H), 7.43 (br s, 2H), 7.11 (m, 2H), 6.94 (m, 1H),

[0105] Example 1-4 Synthesis of Biguanide Passivator P-4 (3,5-bistrifluoromethylphenylbiguanide Hydrogen Iodide) Under a nitrogen atmosphere, an aqueous solution (4.50 g) of hydroiodic acid with a concentration of approximately 57% by mass was added dropwise to a suspension of 3,5-bistrifluoromethylphenylbiguanide (0.500 g) dispersed in pure water (1.0 g) while stirring the suspension. The reaction solution was stirred for 5 days, and then the precipitate was filtered. The filtered precipitate was washed with pure water and dried under reduced pressure to obtain biguanide passivator P-4 as a white solid. The obtained biguanide passivator P-4 １ H-NMR was as follows: １ H-NMR (400MHz, DMSO-d ６ ): δ = 9.60 (br s, 1H), 8.02 (s, 2H), 7.73 (s, 1H), 7.71-7.32 (br s, 2H), 7.14 (s, 2H)

[0106] Example 1-5 Synthesis of Biguanide Passivator P-5 (o-Tolylbiguanide Hydrobromide) A white solid biguanide passivator P-5 was obtained in the same manner as in Example 1, except that hydrobromic acid was used instead of hydroiodic acid. １ H-NMR was as follows:１ H-NMR (400MHz, DMSO-d6): δ = 8.73 (br s, 1H), 7.32 (d, 1H), 7.22 (d, 1H), 7.18 (t, 1H), 7.10 (t, 1H), 7.02 (br s, 5H), 2.22 (s, 3H)

[0107] Example 1-6 Synthesis of biguanide passivator P-6 (o-tolylbiguanide hydrochloride) A white solid biguanide passivator P-6 was obtained in the same manner as in Example 1, except that hydrochloric acid was used instead of hydroiodic acid. １ H-NMR was as follows: １ H-NMR (400MHz, DMSO-d6): δ = 9.14 (br s, 1H), 7.32 (d, 1H), 7.26-7.00 (m, 8H), 2.24 (s, 3H)

[0108] Next, perovskite solar cells were fabricated using the biguanide-based passivators P-1 and P-2, and their performance was evaluated.

[0109] Example 1-7: A NiOx film was formed on the FTO layer of a glass / FTO substrate. The glass / FTO substrate is a substrate in which FTO constituting the first electrode layer is pre-laminated on a glass base material. PbI was used as a perovskite precursor. ２ A mixture of a 1:0.9:0.1 molar ratio of (metal halide), FAI, and CsI was dissolved in a 1:6 volume ratio mixed solvent of NMP and DMF to a total concentration of 2.4 M of perovskite precursor components to prepare a liquid. Approximately 0.5 mg / mL of MeO-4PACz was dissolved as a hole transport layer-forming compound, and 0.25 mmol / L of biguanide passivator P-1 was dissolved as a passivation material to prepare a liquid composition. The coating film formed by spin-coating the liquid composition was dried at 130°C for 30 minutes to obtain a perovskite film. Furthermore, 20 nm of fullerene was vapor-deposited as an electron transport layer, followed by SnO as a buffer layer. ２ A 20 nm thick layer was formed by atomic deposition, and then 100 nm of silver was evaporated to obtain a perovskite solar cell.

[0110] Example 1-8 A perovskite solar cell was obtained in the same manner as in Example 1-7, except that the biguanide-based passivator P-1 was changed to a biguanide-based passivator P-2.

[0111] Examples 1-9 and 1-10 In Example 1-9, the biguanide passivator P-1 was changed to biguanide passivator P-5. In Example 1-10, the biguanide passivator P-1 was changed to biguanide passivator P-6. Apart from these changes, a perovskite solar cell was obtained in the same manner as in Example 1-7.

[0112] Comparative Example 1-1 A perovskite solar cell was obtained in the same manner as in Example 1-7, except that the biguanide-based passivator P-1 was not used.

[0113] The results of measuring the IV characteristics of the obtained perovskite solar cells of Examples 1-7 to 1-10 and Comparative Example 1 are shown in Table 1 below.

[0114] Table 1 shows that the perovskite solar cells of Examples 1-7 to 1-10, which have a photoelectric conversion layer containing the hydrohalide salt represented by formula (1) as a passivation material, have superior photoelectric conversion efficiency to the perovskite solar cell of the comparative example, which has a photoelectric conversion layer that does not contain the hydrohalide salt represented by formula (1).

[0115] Example 1-11: A NiOx film was formed on the FTO layer of a glass / FTO substrate. The glass / FTO substrate was a substrate in which FTO, which constituted the first electrode layer, had been pre-laminated on a glass substrate. Next, a solution of a material for forming a hole transport layer, dissolved in ethanol at a concentration of 1 mg / mL, was spin-coated onto the NiOx layer. The material for forming the hole transport layer was 2PACz and MeO-2PACz at a molar ratio of 1:1 (2PACz:MeO-2PACz). The spin-coated coating film was dried at 100°C for 10 minutes to form a hole transport layer. A solution of 4-fluorophenylethylamine hydroiodide, a passivation material, dissolved in DMF at a concentration of 80 mM was spin-coated onto the hole transport layer. The spin-coated coating film was dried at 100°C for 5 minutes to form a layer of the passivation material. A liquid composition in which a perovskite precursor was dissolved at a concentration of 3.2 M in a mixed solvent of DMSO and DMF at a volume ratio of 1:4 was spin-coated onto the layer made of the passivation material. ２ A liquid composition was used in which a biguanide-based passivator P-1 was added to a mixture of a 1:0.83:0.17 molar ratio of (metal halide), FAI, and MABr (halogenated organic compound) at 0.25 mmol / L. The coating film formed by spin coating was heated at 120°C for 30 minutes to form a photoelectric conversion layer. A solution of 1H,1H-undecafluorohexylamine hydroiodide as a passivation material dissolved in 2-propanol at 0.25 mmol / L was spin-coated onto the photoelectric conversion layer. The spin-coated coating film was dried at 100°C for 10 minutes to form a layer of the passivation material. In this manner, a photoelectric conversion layer was formed having a passivation material layered on both main surfaces and containing the biguanide-based passivator P-1. Further, 20 nm of fullerene was vapor-deposited as an electron transport layer, followed by a SnO buffer layer. ２ A 20 nm layer was formed by atomic deposition, and then 100 nm of silver was evaporated to obtain a perovskite solar cell.

[0116] Comparative Example 1-2 A perovskite solar cell was obtained in the same manner as in Example 1-11, except that the biguanide-based passivator P-1 was not used.

[0117] The results of measuring the IV characteristics of the obtained perovskite solar cells of Examples 1-11 and Comparative Examples 1-2 are shown in Table 2 below.

[0118] Table 2 shows that the perovskite solar cell of the example, which has a photoelectric conversion layer containing the hydrohalide salt represented by formula (1) as a passivation material, has superior photoelectric conversion efficiency to the perovskite solar cell of the comparative example, which has a photoelectric conversion layer that does not contain the hydrohalide salt represented by formula (1).

[0119] Example 2-1: PbI was used as a perovskite precursor. ２ A mixture of (metal halide), FAI, and MABr (halogenated organic compound) in a molar ratio of 1:0.83:0.17 was dissolved in a mixed solvent of DMSO and DMF in a volume ratio of 1:4 to give a total concentration of the perovskite precursor components of 3.2 M. To this prepared solution, 2PACz and MeO-2PACz in a molar ratio of approximately 1:1 as hole transport layer-forming compounds were dissolved at approximately 0.1 mg / mL, and 1H,1H-undecafluorohexylamine hydroiodide was dissolved as a passivation material at a concentration of 0.25 mmol / L to prepare a perovskite precursor solution.

[0120] <Examples 2-2 to 2-5> In Example 2-2, the passivation material was changed to 1H,1H-undecafluorohexylamine hydrochloride. In Example 2-3, the passivation material was changed to 1H,1H-undecafluorohexylamine hydrobromide. In Example 2-4, the passivation material was changed to 2,2,2-trifluoroethylamine hydroiodide. In Example 2-5, the passivation material was changed to 2,2,2-trifluoroethylamine hydrochloride. Apart from these changes, a perovskite precursor liquid was prepared in the same manner as in Example 2-1.

[0121] Comparative Example 2-1 A perovskite precursor liquid was prepared in the same manner as in Example 2-1, except that L-α-phosphatidylcholine was used as the passivation material.

[0122] Using a commercially available glass / FTO substrate (a glass substrate on which FTO constituting the first electrode layer was previously laminated), a NiOx film was formed on the FTO, and then the perovskite precursor liquid obtained in Examples 2-1 to 2-5 or Comparative Example 2-1 was applied and the solvent was dried to form a hole transport layer, a perovskite layer, and a passivation layer, and then a second electrode layer was laminated, thereby producing prototype solar cells. The results of measuring the IV characteristics of these prototypes are shown in Table 3 below.

[0123]

[0124] In this way, it was confirmed that the photoelectric conversion efficiency of solar cells can be improved by adding a hydrogen halide salt of an amine having a fluoroalkyl group as a passivation material to the perovskite precursor liquid.

[0125] REFERENCE SIGNS LIST 1 Perovskite solar cell 10 Substrate 20 First electrode layer 30 Hole transport layer 40 Photoelectric conversion layer 50 Electron transport layer 60 Second electrode layer

Claims

1. A perovskite solar cell comprising a photoelectric conversion layer containing a perovskite compound, wherein one or more passivation materials selected from a hydrohalide salt represented by the following formula (1) and a hydrohalide salt of an amine having a fluoroalkyl group are present on the surface and / or inside of the photoelectric conversion layer. １ R ２ NC(=NH)-NH-C(=NH)-NH ２ ・HX...(1) (In formula (1), R １ , and R ２ are each independently a hydrogen atom or a monovalent organic group, and X is a halogen atom.

2. The passivation material contains a hydrohalide salt represented by formula (1), and R １ , and R ２ 2. The perovskite solar cell according to claim 1 , wherein one of the groups is an aromatic hydrocarbon group which may have a substituent, and the other is a hydrogen atom.

3. The perovskite solar cell according to claim 1 or 2, wherein the passivation material is a hydroiodide.

4. A perovskite solar cell according to claim 1 or 2, comprising: a plate-like or sheet-like substrate; a first electrode layer laminated on one main surface of the substrate; a hole transport layer laminated on the first electrode layer; the photoelectric conversion layer laminated on the hole transport layer; an electron transport layer laminated on the photoelectric conversion layer; and a second electrode layer laminated on the electron transport layer.

5. A liquid composition comprising one or more passivation materials selected from the group consisting of hydrohalide salts represented by the following formula (1) and hydrohalide salts of amines having a fluorinated alkyl group, and a solvent. １ R ２ NC(=NH)-NH-C(=NH)-NH ２ ・HX...(1) (In formula (1), R １ , and R ２ are each independently a hydrogen atom or a monovalent organic group, and X is a halogen atom.

6. The liquid composition of claim 5, further comprising a perovskite precursor.

7. The liquid composition according to claim 6, further comprising a hole transport material.

8. The liquid composition according to any one of claims 5 to 7, wherein the passivation material is a hydroiodide salt.

9. A method for manufacturing a perovskite solar cell, comprising the steps of: applying the liquid composition according to claim 7 onto a laminate having at least a plate- or sheet-like substrate and a first electrode layer; and generating crystals of a perovskite compound by volatilizing the solvent from a coating film made of the liquid composition.

10. A hydrohalide salt represented by the following formula (1): R １ R ２ NC(=NH)-NH-C(=NH)-NH ２ ・HX...(1) (In formula (1), R １ , and R ２ are each independently a hydrogen atom or a monovalent organic group, and X is a halogen atom.

11. R １ , and R ２ The hydrohalide salt according to claim 10, wherein one of the groups is an aromatic hydrocarbon group which may have a substituent, and the other is a hydrogen atom.

12. The hydrohalide salt of claim 10 or 11, which is a hydroiodide salt.

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