Perovskite solar cell, triarylamine compound, diarylamine compound, liquid composition, and method for manufacturing perovskite solar cell

Abstract

Provided are: a perovskite solar cell having high photoelectric conversion efficiency; a liquid composition suitably used for forming a hole transport layer; a triarylamine compound or diarylamine compound suitably added to the liquid composition; and a method for manufacturing a perovskite solar cell using the liquid composition.　In the perovskite solar cell, a hole transport layer contains: a triarylamine compound represented by formula (1): (HO)2P(=O)-Ar1-N(Ar2)2 (in formula (1), Ar1 is a divalent aromatic hydrocarbon group that optionally has a substituent, and Ar2 is a phenyl group or the like); or a diarylamine compound represented by formula (1'): (HO)2P(=O)-R1-N(Ar1)2 (in formula (1'), R1 is a chain aliphatic group that optionally has a substituent and optionally contains a hetero atom, and Ar1 is an aromatic hydrocarbon group optionally substituted with a halogen atom or the like).

Description

Perovskite solar cell, triarylamine compound, diarylamine compound, liquid composition, and method for manufacturing perovskite solar cell

[0001] The present invention relates to a perovskite solar cell, a triarylamine compound, a diarylamine compound, a liquid composition, and a method for producing a perovskite solar cell.

[0002] The use of solar cells is expanding as an energy source with a low environmental impact. When installing solar cells in various devices, vehicles, buildings, etc., the available installation area is limited, making the photoelectric conversion efficiency of the solar cell important. Perovskite solar cells, which use organic materials, have been researched as solar cells with high photoelectric conversion efficiency. A basic perovskite solar cell comprises a substrate, a first electrode (anode or cathode), a hole transport layer (hole transport layer or electron transport layer), a photoelectric conversion layer (perovskite layer), an electron transport layer (electron transport layer or hole transport layer), and a first electrode (cathode or anode) stacked in this order. Furthermore, it is known that the photoelectric conversion efficiency can be improved by providing a first buffer layer between the first electrode and the hole transport layer or by providing a second buffer layer between the electron transport layer and the second electrode.

[0003] Furthermore, Patent Document 1 describes a solar cell in which a monomolecular film is formed on the surface of a first electrode laminated on a substrate, a photoelectric conversion layer is directly laminated on the monomolecular film, and an electron transport layer and a transparent electrode are further laminated.

[0004] JP 2010-141165 A

[0005] Patent Document 1 recommends adding a hole transport layer between the monomolecular film and the photoelectric conversion layer to enable more efficient extraction of charges. The hole transport layer improves the photoelectric conversion efficiency by increasing the selectivity of holes that reach the electrode.

[0006] However, there is a demand for further improvements in the photoelectric conversion efficiency of perovskite solar cells, and there is room for improvement of the hole transport layer in order to increase the photoelectric conversion efficiency.

[0007] An object of the present invention is to provide a perovskite solar cell with high photoelectric conversion efficiency, a triarylamine compound or diarylamine compound that can be suitably added to the liquid composition, a liquid composition that can be suitably used for forming a hole transport layer in the production of the perovskite solar cell, and a method for producing a perovskite solar cell that uses the liquid composition.

[0008] A perovskite solar cell according to a first aspect of the present invention comprises a first electrode layer, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode layer in this order, wherein the hole transport layer is represented by the following formula (1): (HO) ２ P(=O)-Ar １ -N(Ar ２ ) ２ (1) (In formula (1), Ar １ is a divalent aromatic hydrocarbon group which may have a substituent, and Ar ２ is a phenyl group, a phenyl group substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms, or an aromatic hydrocarbon group having from 10 to 20 carbon atoms which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms), or a group represented by the following formula (1-1): (HO) ２ P(=O)-R １０ -Ar １ -N(Ar ２０ ) ２ (1-1) (In formula (1-1), R １０ represents a chain aliphatic group which may have a substituent and which may contain a heteroatom, and Ar １ is a divalent aromatic hydrocarbon group which may have a substituent, and Ar ２０ is a phenyl group, a halogen atom, an alkyl group having 1 to 6 carbon atoms, (HO) ２ P(=O)-(CH ２ ) ｎ- (where n is an integer of 1 to 6), and / or an alkoxy group having from 1 to 6 carbon atoms, or an aromatic hydrocarbon group having from 10 to 20 carbon atoms in which a plurality of aromatic rings are linked or condensed, and which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms.

[0009] In the perovskite solar cell according to the first aspect described above, Ar １ However, it may also be a phenylene group.

[0010] In the perovskite solar cell according to the first aspect described above, the self-assembled monolayer comprises a compound represented by the following formula (2): (HO) together with a triarylamine compound. ２ P(=O)-Ar １ -N(Ar ３ ) ２ (2) (In formula (2), Ar １ is a divalent aromatic hydrocarbon group which may have a substituent, and Ar ３ is a phenyl group.

[0011] The triarylamine compound according to the first aspect of the present invention is represented by the following formula (1): (HO) ２ P(=O)-Ar １ -N(Ar ２ ) ２ (1) (In formula (1), Ar １ is a divalent aromatic hydrocarbon group which may have a substituent, and Ar ２ is a phenyl group, a phenyl group substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms, or an aromatic hydrocarbon group having from 10 to 20 carbon atoms which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms), or a group represented by the following formula (1-1): (HO) ２ P(=O)-R １０ -Ar １ -N(Ar２０ ) ２ (1-1) (In formula (1-1), R １０ represents a chain aliphatic group which may have a substituent and which may contain a heteroatom, and Ar １ is a divalent aromatic hydrocarbon group which may have a substituent, and Ar ２０ is a phenyl group, a halogen atom, an alkyl group having 1 to 6 carbon atoms, (HO) ２ P(=O)-(CH ２ ) ｎ - (where n is an integer of 1 to 6), and / or a phenyl group substituted with an alkoxy group having from 1 to 6 carbon atoms, or an aromatic hydrocarbon group having from 10 to 20 carbon atoms in which a plurality of aromatic rings are linked or condensed, and which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms.

[0012] A liquid composition according to a first aspect of the present invention is a liquid composition for forming a hole transport layer in a perovskite solar cell according to the first aspect, and comprises a compound represented by the following formula (1): (HO) ２ P(=O)-Ar １ -N(Ar ２ ) ２ (1) (In formula (1), Ar １ is a divalent aromatic hydrocarbon group which may have a substituent, and Ar ２ is a phenyl group substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms, or an aromatic hydrocarbon group having from 10 to 20 carbon atoms which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms), or a group represented by the following formula (1-1): (HO) ２ P(=O)-R １０ -Ar １ -N(Ar ２０ ) ２ (1-1) (In formula (1-1), R １０ represents a chain aliphatic group which may have a substituent and which may contain a heteroatom, and Ar １is a divalent aromatic hydrocarbon group which may have a substituent, and Ar ２０ is a phenyl group, a halogen atom, an alkyl group having 1 to 6 carbon atoms, (HO) ２ P(=O)-(CH ２ ) ｎ - (where n is an integer of 1 to 6), and / or an alkoxy group having 1 to 6 carbon atoms, or an aromatic hydrocarbon group having 10 to 20 carbon atoms in which a plurality of aromatic rings are linked or condensed, and which may be substituted with an alkyl group having 1 to 6 carbon atoms and / or an alkoxy group having 1 to 6 carbon atoms.

[0013] The liquid composition according to the first aspect described above may further contain a perovskite precursor and / or a passivation material.

[0014] A method for producing a perovskite solar cell according to a first aspect of the present invention is a method comprising: applying the liquid composition according to the first aspect to a first electrode layer formed on one main surface of a plate-like or sheet-like substrate to form a hole transport layer; forming a photoelectric conversion layer containing a perovskite compound on the hole transport layer; forming an electron transport layer on the photoelectric conversion layer; and forming a second electrode layer on the electron transport layer.

[0015] In the method for producing a perovskite solar cell according to the first aspect described above, the liquid composition may contain a perovskite precursor and a passivation material, and the liquid composition according to the first aspect may be applied to the first electrode layer to form a hole transport layer and a photoelectric conversion layer in this order, with the passivation material being present on the surface and / or inside of the photoelectric conversion layer.

[0016] A perovskite solar cell according to a second aspect of the present invention comprises a first electrode layer, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode layer in this order, wherein the hole transport layer is represented by the following formula (1'): (HO) ２ P(=O)-R １ -N(Ar １ )２ (1') (In formula (1'), R １ represents a chain aliphatic group which may have a substituent and which may contain a heteroatom, and Ar １ is an aromatic hydrocarbon group having from 6 to 20 carbon atoms which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms.

[0017] In the perovskite solar cell according to the second aspect, Ar １ may be a phenyl group or a naphthyl group.

[0018] The diarylamine compound according to the second aspect of the present invention is represented by the following formula (1'): (HO) ２ P(=O)-R １ -N(Ar １ ) ２ (1') (In formula (1'), R １ represents a chain aliphatic group which may have a substituent and which may contain a heteroatom, and Ar １ is an aromatic hydrocarbon group having 6 to 20 carbon atoms which may be substituted with an alkyl group having 1 to 6 carbon atoms and / or an alkoxy group having 1 to 6 carbon atoms.

[0019] A liquid composition according to a second aspect of the present invention is a liquid composition for forming a hole transport layer in a perovskite solar cell according to the second aspect, and is a liquid composition represented by the following formula (1'): (HO) ２ P(=O)-R １ -N(Ar １ ) ２ (1') (In formula (1'), R １ represents a chain aliphatic group which may have a substituent and which may contain a heteroatom, and Ar １ is an aromatic hydrocarbon group having from 6 to 20 carbon atoms which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms.

[0020] The liquid composition according to the second aspect described above may further contain a perovskite precursor and / or a passivation material.

[0021] A method for producing a perovskite solar cell according to a second aspect of the present invention includes: applying the liquid composition according to the second aspect to a first electrode layer formed on one main surface of a plate-like or sheet-like substrate to form a hole transport layer; forming a photoelectric conversion layer containing a perovskite compound on the hole transport layer; forming an electron transport layer on the photoelectric conversion layer; and forming a second electrode layer on the electron transport layer.

[0022] In the method for producing a perovskite solar cell according to the second aspect described above, the liquid composition according to the second aspect may contain a perovskite precursor and a passivation material, and the liquid composition according to the second aspect may be applied to the first electrode layer to form a hole transport layer and a photoelectric conversion layer in this order, with the passivation material being present on the surface and / or inside of the photoelectric conversion layer.

[0023] The present invention can provide a perovskite solar cell with high photoelectric conversion efficiency, a triarylamine compound or diarylamine compound that can be suitably added to the liquid composition, a liquid composition that can be suitably used to form a hole transport layer in the production of the perovskite solar cell, and a method for producing a perovskite solar cell that uses the liquid composition.

[0024] 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 steps of an embodiment of a solar cell manufacturing method according to the present invention;

[0025] A first embodiment of the present invention will be described below with reference to the drawings. The dimensions of various components in the drawings have been adjusted for clarity and convenience. In the following embodiments, components similar to those in the first embodiment will be designated by the same reference numerals, and redundant description will be omitted.

[0026] [First embodiment] Figure 1 is a schematic cross-sectional view showing the configuration of a perovskite solar cell 1 according to a first embodiment of the present invention. The perovskite solar cell 1 comprises a plate- or sheet-shaped substrate 10, a first electrode layer 20 laminated on one main surface of the substrate 10 (the lower side in Figure 1), 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, an electron transport layer 50 laminated on one surface of the photoelectric conversion layer 40, and a second electrode layer 60 (cathode) laminated on one side of the electron transport layer 50. A passivation material (not shown) may be present on and / or inside the photoelectric conversion layer 40.

[0027] 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.

[0028] 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.

[0029] 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 a compound represented by the following formula (1): (HO) ２ P(=O)-Ar １ -N(Ar ２ ) ２ (1) (In formula (1), Ar １ is a divalent aromatic hydrocarbon group which may have a substituent, and Ar ２ is a phenyl group, a phenyl group substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms, or an aromatic hydrocarbon group having from 10 to 20 carbon atoms which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms), or a group represented by the following formula (1-1): (HO) ２ P(=O)-R １０ -Ar １ -N(Ar ２０ ) ２ (1-1) (In formula (1-1), R １０ represents a chain aliphatic group which may have a substituent and which may contain a heteroatom, and Ar １ is a divalent aromatic hydrocarbon group which may have a substituent, and Ar２０ is a phenyl group, a halogen atom, an alkyl group having 1 to 6 carbon atoms, (HO) ２ P(=O)-(CH ２ ) ｎ and n is an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms, and is an aromatic hydrocarbon group having from 10 to 20 carbon atoms in which a plurality of aromatic rings are linked or condensed. This monomolecular film is a so-called self-assembled monolayer (SAM).

[0030] In formula (1), Ar １ is a divalent aromatic hydrocarbon group which may have a substituent. １ The number of carbon atoms in the divalent aromatic hydrocarbon group as Ar is preferably 6 or more and 30 or less, more preferably 6 or more and 20 or less, and even more preferably 6 or more and 12 or less. １ Specific examples of the divalent aromatic hydrocarbon group as Ar include phenylene groups such as o-phenylene, m-phenylene, and p-phenylene; naphthylene groups such as naphthalene-1,2-diyl, naphthalene-1,3-diyl, naphthalene-1,4-diyl, naphthalene-1,5-diyl, naphthalene-1,7-diyl, naphthalene-1,8-diyl, naphthalene-2,3-diyl, naphthalene-2,6-diyl, and naphthalene-2,7-diyl; and biphenyldiyl groups such as biphenyl-4,4'-diyl, biphenyl-3,4'-diyl, and biphenyl-3,3'-diyl. １ The divalent aromatic hydrocarbon group as may be an anthracenediyl group, a phenanthrenediyl group, a terphenyldiyl group, or the like.

[0031] Ar １The divalent aromatic hydrocarbon group as is preferably an m-phenylene group, a p-phenylene group, a naphthalene-1,4-diyl group, a naphthalene-2,6-diyl group, a naphthalene-2,7-diyl group, a biphenyl-4,4'-diyl group, a biphenyl-3,4'-diyl group, or a biphenyl-3,3'-diyl group, more preferably a p-phenylene group, a naphthalene-2,6-diyl group, a naphthalene-2,7-diyl group, or a biphenyl-4,4'-diyl group, and particularly preferably a p-phenylene group.

[0032] Ar １ Specific examples of the substituent that the divalent aromatic hydrocarbon group may have include an alkyl group having from 1 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, a halogen atom, a hydroxyl group, a nitro group, and a cyano group. Examples of the alkyl group having from 1 to 6 carbon atoms include 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. Examples of the alkoxy group having from 1 to 6 carbon atoms include 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.

[0033] In formula (1), Ar ２ is a phenyl group, a phenyl group substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms, or an aromatic hydrocarbon group having from 10 to 20 carbon atoms which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms.

[0034] Ar ２ is a phenyl group substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms, the alkyl group having from 1 to 6 carbon atoms and the alkoxy group having from 1 to 6 carbon atoms are each independently selected from Ar １The same applies to the alkyl group having 1 to 6 carbon atoms and the alkoxy group having 1 to 6 carbon atoms that may be substituted on the divalent aromatic hydrocarbon group represented by Ar. ２ The number of alkyl groups having 1 to 6 carbon atoms and / or alkoxy groups having 1 to 6 carbon atoms that the phenyl group has as the aryl group is, for example, preferably 1 to 4, more preferably 1 to 3, even more preferably 1 or 2, and particularly preferably 1.

[0035] Ar ２ Examples of the phenyl group substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms as the aryl group include an o-methylphenyl group, an m-methylphenyl group, a p-methylphenyl group, 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, a 3,5-dimethylphenyl group, an o-methoxyphenyl group, an m-methoxyphenyl group, a p-methoxyphenyl group, an o-methoxymethylphenyl group, an m-methoxymethylphenyl group, and a p-methoxymethylphenyl group. Among these, an m-methylphenyl group, a p-phenylmethyl group, an m-methoxyphenyl group, and a p-methoxymethylphenyl group are preferred, an m-methoxyphenyl group and a p-methoxymethylphenyl group are more preferred, and a p-methoxymethylphenyl group is even more preferred.

[0036] Ar ２ may be an aromatic hydrocarbon group having from 10 to 20 carbon atoms which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms.

[0037] Ar ２Examples of the aromatic hydrocarbon group having 10 to 20 carbon atoms as the aromatic hydrocarbon group include a naphthalene-1-yl group, a naphthalene-2-yl group, an o-phenylphenyl group, an m-phenylphenyl group, a p-phenylphenyl group, an anthracen-1-yl group, an anthracen-2-yl group, an anthracen-9-yl group, a phenanthrene-1-yl group, a phenanthrene-2-yl group, a phenanthrene-3-yl group, a phenanthrene-4-yl group, and a phenanthrene-9-yl group.

[0038] Ar ２ The alkyl group having 1 to 6 carbon atoms and the alkoxy group having 1 to 6 carbon atoms that may be substituted on the aromatic hydrocarbon group having 10 to 20 carbon atoms as Ar １ The same applies to the alkyl group having 1 to 6 carbon atoms and the alkoxy group having 1 to 6 carbon atoms that the divalent aromatic hydrocarbon group may have as a substituent.

[0039] Ar ２ As the aromatic hydrocarbon group having from 10 to 20 carbon atoms which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms, an unsubstituted aromatic hydrocarbon group having from 10 to 20 carbon atoms is preferred. As the unsubstituted aromatic hydrocarbon group having from 10 to 20 carbon atoms, a naphthalene-1-yl group, a naphthalene-2-yl group, an m-phenylphenyl group, and a p-phenylphenyl group are preferred.

[0040] Specific preferred examples of the triarylamine compound represented by formula (1) include the following compounds: In the following formula, Me is a methyl group.

[0041]

[0042]

[0043] In formula (1-1), R １０ R is a chain aliphatic group which may have a substituent and may contain a heteroatom. １０The chain aliphatic group represented by R may contain two or more heteroatoms, or may contain two or more types of heteroatoms. １０ The chain aliphatic group as R may be linear or branched. １０ The chain aliphatic group as may have one or more unsaturated bonds, and is preferably a chain saturated aliphatic group.

[0044] R １０ Heteroatoms that may be contained in the chain aliphatic group as defined above include oxygen, sulfur, nitrogen, phosphorus, boron, silicon, and halogen atoms. Among these heteroatoms, oxygen and sulfur atoms are preferred. Examples of oxygen and sulfur atoms include -O-, -C(=O)-, -S-, -S-S-, -C(=S)-, -SO ２ It may be present in a chain aliphatic group as - and -S(=O)-.

[0045] R １０ Suitable examples of the chain aliphatic group as -R include an alkylene group, １１ -O-R １２ -, -R １３ -C(=O)-R １４ -, -R １５ -C(=O)-OR １７ - and -R １８ -S-R １９ - is mentioned. １１ ~R １９ are each independently an alkylene group having 1 to 6 carbon atoms, preferably an alkylene group having 1 to 3 carbon atoms.

[0046] R １０ The chain aliphatic group as R is preferably an alkylene group, more preferably an alkylene group having 1 to 6 carbon atoms. １０Specific preferred examples of the alkylene group as the alkylene group include a methylene group, an ethane-1,2-diyl group (ethylene group), an ethane-1,1-diyl group, a propane-1,3-diyl group (propylene group), a propane-1,2-diyl group (butylene group), a propane-2,2-diyl group, a butane-1,4-diyl group, a butane-1,3-diyl group, a butane-1,2-diyl group, a pentane-1,5-diyl group, and a hexane-1,6-diyl group. Among these alkylene groups, a methylene group, an ethane-1,2-diyl group (ethylene group), a propane-1,3-diyl group (propylene group), a butane-1,4-diyl group, and a butane-1,3-diyl group (butylene group) are preferred, and an ethane-1,2-diyl group (ethylene group), a propane-1,3-diyl group (propylene group), and a butane-1,3-diyl group (butylene group) are more preferred.

[0047] In formula (1-1), Ar １ is a divalent aromatic hydrocarbon group which may have a substituent. １ The number of carbon atoms in the divalent aromatic hydrocarbon group as Ar is preferably 6 or more and 30 or less, more preferably 6 or more and 20 or less, and even more preferably 6 or more and 12 or less. １ Specific examples of the divalent aromatic hydrocarbon group as Ar include phenylene groups such as o-phenylene, m-phenylene, and p-phenylene; naphthylene groups such as naphthalene-1,2-diyl, naphthalene-1,3-diyl, naphthalene-1,4-diyl, naphthalene-1,5-diyl, naphthalene-1,7-diyl, naphthalene-1,8-diyl, naphthalene-2,3-diyl, naphthalene-2,6-diyl, and naphthalene-2,7-diyl; and biphenyldiyl groups such as biphenyl-4,4'-diyl, biphenyl-3,4'-diyl, and biphenyl-3,3'-diyl. １ The divalent aromatic hydrocarbon group as may be an anthracenediyl group, a phenanthrenediyl group, a terphenyldiyl group, or the like.

[0048] Ar １The divalent aromatic hydrocarbon group as is preferably an m-phenylene group, a p-phenylene group, a naphthalene-1,4-diyl group, a naphthalene-2,6-diyl group, a naphthalene-2,7-diyl group, a biphenyl-4,4'-diyl group, a biphenyl-3,4'-diyl group, or a biphenyl-3,3'-diyl group, more preferably a p-phenylene group, a naphthalene-2,6-diyl group, a naphthalene-2,7-diyl group, or a biphenyl-4,4'-diyl group, and particularly preferably a p-phenylene group.

[0049] Ar １ Specific examples of the substituent that the divalent aromatic hydrocarbon group may have include an alkyl group having from 1 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, a halogen atom, a hydroxyl group, a nitro group, and a cyano group. Examples of the alkyl group having from 1 to 6 carbon atoms include 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. Examples of the alkoxy group having from 1 to 6 carbon atoms include 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.

[0050] In formula (1-1), Ar ２０ is a phenyl group substituted with a halogen atom, an alkyl group having from 1 to 6 carbon atoms, and / or an alkoxy group having from 1 to 6 carbon atoms, or an aromatic hydrocarbon group having from 10 to 20 carbon atoms in which a plurality of aromatic rings are linked or condensed, and which may be substituted with an alkyl group having from 1 to 6 carbon atoms, and / or an alkoxy group having from 1 to 6 carbon atoms.

[0051] Ar ２０is a phenyl group or a phenyl group substituted with a halogen atom, an alkyl group having from 1 to 6 carbon atoms, and / or an alkoxy group having from 1 to 6 carbon atoms, the halogen atom is F, Cl, Br, and I, and the alkyl group having from 1 to 6 carbon atoms and the alkoxy group having from 1 to 6 carbon atoms are Ar １ The same applies to the alkyl group having 1 to 6 carbon atoms and the alkoxy group having 1 to 6 carbon atoms that the divalent aromatic hydrocarbon group may have as a substituent.

[0052] Ar ２０ But (HO) ２ P(=O)-(CH ２ ) ｎ When the phenyl group is a phenyl group substituted with a group represented by - (where n is an integer of 1 or more and 6 or less), (HO) ２ P(=O)-(CH ２ ) ｎ Examples of the group represented by - (where n is an integer of 1 or more and 6 or less) include the following substituents.

[0053] Ar ２０ an alkyl group having 1 to 6 carbon atoms which the phenyl group has as the alkyl group (HO) ２ P(=O)-(CH ２ ) ｎ The number of groups represented by - (where n is an integer of 1 or more and 6 or less) and / or alkoxy groups having 1 to 6 carbon atoms is, for example, preferably 1 to 4, more preferably 1 to 3, even more preferably 1 or 2, and particularly preferably 1.

[0054] Ar ２０ a halogen atom, an alkyl group having 1 to 6 carbon atoms, (HO) ２ P(=O)-(CH ２ ) ｎ- (where n is an integer of 1 to 6) and / or the phenyl group substituted with an alkoxy group having from 1 to 6 carbon atoms includes an o-chlorophenyl group, an m-chlorophenyl group, a p-chlorophenyl group, an o-methylphenyl group, an m-methylphenyl group, a p-methylphenyl group, 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; Examples of the phenyl group include an o-methoxyphenyl group, an m-methoxyphenyl group, a p-methoxyphenyl group, an o-methoxymethylphenyl group, an m-methoxymethylphenyl group, and a p-methoxymethylphenyl group. Among these, an m-chlorophenyl group, a p-chlorophenyl group, an m-methylphenyl group, a p-phenylmethyl group, an m-methoxyphenyl group, and a p-methoxymethylphenyl group are preferred, a p-chlorophenyl group, a p-methoxyphenyl group, and a p-methoxymethylphenyl group are more preferred, and a p-chlorophenyl group and a p-methoxyphenyl group are even more preferred.

[0055] Ar ２０ may be an aromatic hydrocarbon group having from 10 to 20 carbon atoms in which a plurality of aromatic rings are linked or condensed, and which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms.

[0056] Ar ２０ Examples of the aromatic hydrocarbon group having from 10 to 20 carbon atoms in which a plurality of aromatic rings are linked or condensed as the aromatic hydrocarbon group include a naphthalene-1-yl group, a naphthalene-2-yl group, an o-phenylphenyl group, an m-phenylphenyl group, a p-phenylphenyl group, an anthracen-1-yl group, an anthracen-2-yl group, an anthracen-9-yl group, a phenanthrene-1-yl group, a phenanthrene-2-yl group, a phenanthrene-3-yl group, a phenanthrene-4-yl group, and a phenanthrene-9-yl group.

[0057] Ar ２０The alkyl group having 1 to 6 carbon atoms and the alkoxy group having 1 to 6 carbon atoms which may be substituted on the aromatic hydrocarbon group having 10 to 20 carbon atoms in which a plurality of aromatic rings are linked or condensed as Ar １ The same applies to the alkyl group having 1 to 6 carbon atoms and the alkoxy group having 1 to 6 carbon atoms that the divalent aromatic hydrocarbon group may have as a substituent.

[0058] Ar ２０ As the aromatic hydrocarbon group having from 10 to 20 carbon atoms, in which a plurality of aromatic rings are linked or condensed and which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms, it is preferable that the aromatic hydrocarbon group has from 10 to 20 carbon atoms. As the unsubstituted aromatic hydrocarbon group having from 10 to 20 carbon atoms, a naphthalene-1-yl group, a naphthalene-2-yl group, an m-phenylphenyl group, and a p-phenylphenyl group are preferable.

[0059] Specific examples of suitable triarylamine compounds represented by formula (1-1) include the following compounds: In the following formula, Me is a methyl group.

[0060]

[0061] The compounds represented by formula (1) and formula (1-1) are preferably compounds in which the difference between the HOMO (Highest Occupied Molecular Orbital) of the compound and the VB edge (Valence Band) of the perovskite compound constituting the photoelectric conversion layer 40 is small. The difference is preferably 0.00 to 1.00 eV, more preferably 0.00 to 0.50 eV, and even more preferably 0.00 to 0.30 eV. The HOMO can be determined by photoelectron spectroscopy or quantum chemical calculations based on density functional theory. In this case, B3LYP can be used as the exchange-correlation functional, and 6-311G(d) and 6-311++G(d,p) can be used as the basis functions for optimizing the molecular structure and calculating the energy, respectively.

[0062] The method for producing the triarylamine compounds represented by formula (1) and formula (1-1) is not particularly limited. The triarylamine compounds represented by formula (1) and formula (1-1) can be synthesized, for example, by the following method.

[0063] Specifically, first, a haloarylphosphonic acid diester represented by the following formula (1a) and HN(Ar ２ ) ２ and a diarylamine compound represented by the formula (I) and palladium acetate (Pd(OAc) ２ In the formula (1a), R is condensed in the presence of a transition metal catalyst according to a well-known method to obtain a triarylamine compound having a phosphonic acid diester group represented by the following formula (1b): １１ is a monovalent organic group, preferably a hydrocarbon group. The hydrocarbon group is preferably an alkyl group, more preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group or an ethyl group. Next, the phosphonic acid diester group in the triarylamine compound having the phosphonic acid diester group represented by formula (1b) is hydrolyzed by a well-known method to obtain the triarylamine compound represented by formula (1). (R １１ O) ２ P(=O)-Ar １ -Hal (1a) (R １１ O) ２ P(=O)-Ar １ -N(Ar ２ ) ２ (1b) (in formula (1a) and formula (1b), Ar １ , and Ar ２ are the same as those in formula (1). Hal is a halogen atom. R １１ is a monovalent organic group.

[0064] Also, a haloarylphosphonic acid diester represented by the following formula (1a-1) and HN(Ar ２ ) ２ and a diarylamine compound represented by the formula (I) and palladium acetate (Pd(OAc) ２) or the like, according to a known method, to obtain a triarylamine compound having a phosphonic acid diester group represented by the following formula (1b-1): １１ is a monovalent organic group, preferably a hydrocarbon group. The hydrocarbon group is preferably an alkyl group, more preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group or an ethyl group. Next, the phosphonic acid diester group in the triarylamine compound having the phosphonic acid diester group represented by formula (1b-1) is hydrolyzed by a well-known method to obtain the triarylamine compound represented by formula (1-1). (R １１ O) ２ P(=O)-R １０ -Ar １ -Hal (1a-1) (R １１ O) ２ P(=O)-R １０ -Ar １ -N(Ar ２０ ) ２ (1b-1) (in formula (1a-1) and formula (1b-1), Ar １ , and Ar ２０ are the same as those in formula (1-1). Hal is a halogen atom. R １１ is a monovalent organic group.

[0065] The above method is merely an example, and the triarylamine compounds represented by formula (1) and formula (1-1) may be produced by combining various known methods as necessary.

[0066] The self-assembled monolayer serving as the hole transport layer 30 may contain, in addition to the triarylamine compound represented by formula (1) or formula (1-1), a compound other than the triarylamine compound represented by formula (1).

[0067] The self-assembled monolayer serving as the hole transport layer 30 may contain, in addition to the triarylamine compound represented by formula (1) or formula (1-1), a compound other than the triarylamine compound represented by formula (1) or formula (1-1). The other compound is preferably a carbazole compound. 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 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 serving as the hole transport layer 30.

[0068] When the hole transport layer 30 contains a carbazole compound together with the triarylamine compounds represented by formula (1) and formula (1-1), examples of the carbazole compound include 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 (3P Examples of the carbazole include N-(3-phosphonopropyl)-3,6-dimethoxycarbazole (MeO-3PACz), N-(3-phosphonopropyl)-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). Among these, 2PACz, MeO-2PACz, Me-2PACz, MeO-4PACz, and Me-4PACz are more preferred.

[0069] It is also preferable that the hole transport layer 30 contains a second triarylamine compound represented by the following formula (2) in addition to the triarylamine compounds represented by formula (1) and formula (1-1).

[0070] (HO)２ P(=O)-Ar １ -N(Ar ３ ) ２ (2) (In formula (2), Ar １ is a divalent aromatic hydrocarbon group which may have a substituent, and Ar ３ is a phenyl group.

[0071] Ar in formula (2) １ is Ar in formula (1). １ is the same as:

[0072] Preferable specific examples of the second triarylamine compound represented by formula (2) include (diphenylamino)phenylphosphonic acids such as 2-(N,N-diphenylamino)phenylphosphonic acid, 3-(N,N-diphenylamino)phenylphosphonic acid, and 4-(N,N-diphenylamino)phenylphosphonic acid; 2-(4-N,N-diphenylaminophenyl)phenylphosphonic acid, 3-(4-N,N-diphenylaminophenyl)phenylphosphonic acid, 4-(4-N,N-diphenylaminophenyl)phenylphosphonic acid, 2-(3-N,N-diphenylaminophenyl)phenylphosphonic acid, 3-(3-N,N-diphenylaminophenyl)phenylphosphonic acid, 4-(3-N (diphenylamino)biphenylphosphonic acids such as 2-(2-N,N-diphenylaminophenyl)phenylphosphonic acid, 3-(2-N,N-diphenylaminophenyl)phenylphosphonic acid, and 4-(2-N,N-diphenylaminophenyl)phenylphosphonic acid; and (diphenylamino)naphthylphosphonic acids such as 4-(N,N-diphenylamino)naphthalen-1-ylphosphonic acid, 5-(N,N-diphenylamino)naphthalen-2-ylphosphonic acid, 6-(N,N-diphenylamino)naphthalen-2-ylphosphonic acid, and 7-(N,N-diphenylamino)naphthalen-2-ylphosphonic acid.

[0073] The ratio of the number of moles of the triarylamine compounds represented by formula (1) and formula (1-1) to the total number of moles of compounds constituting the self-assembled monolayer as the hole transport layer 30 is not particularly limited as long as the desired effect is not impaired. The ratio of the number of moles of the triarylamine compounds represented by formula (1) and formula (1-1) to the total number of moles of compounds constituting the self-assembled monolayer as the hole transport layer 30 is preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 70 mol% or more, particularly preferably 90 mol% or more, and most preferably 100 mol%.

[0074] The hole transport layer 30 may contain, as compounds other than the triarylamine compounds represented by formula (1) and formula (1-1), phosphonic acid compounds 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, and 1H,1H,2H,2H-perfluorophosphonic acid, as well as compounds such as acetic acid, propionic acid, isobutyric acid, nonanoic acid, fluoroacetic acid, α-chloropropionic acid, and glyoxylic acid. These compounds may be used alone or in combination of two or more.

[0075] The hole transport layer 30 can be formed by applying and drying a liquid composition containing the triarylamine compounds represented by the above-mentioned formulas (1) and (1-1). The liquid composition may contain, in addition to the triarylamine compounds represented by formulas (1) and (1-1), compounds other than the triarylamine compounds represented by formulas (1) and (1-1). The compounds other than the triarylamine compounds represented by formulas (1) and (1-1) are as described above.

[0076] The liquid composition used to form the hole transport layer 30 usually contains an organic solvent. Examples of organic solvents include alcohols such as methanol, ethanol, 2-methoxyethanol, 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, propyl acetate, isopropyl acetate, butyl acetate, isoamyl acetate, and γ-butyrolactone (GBL); nitriles such as acetonitrile, propionitrile, 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. These may be used alone or in combination of two or more.

[0077] The total concentration of the materials constituting the self-assembled monolayer contained in the liquid composition is preferably 5.0 mg / mL or less.

[0078] The liquid composition may contain a perovskite precursor, which will be described later and is used to form the photoelectric conversion layer 40. When a liquid composition containing a perovskite precursor is used, the hole transport layer 30 and the photoelectric conversion layer 40 can be formed simultaneously by applying the liquid composition onto the first electrode layer 20, drying it, and crystallizing the perovskite precursor. In this case, in the process of forming the photoelectric conversion layer 40, compounds such as the triarylamine compounds represented by formula (1) and formula (1-1) contained in the perovskite precursor liquid form a self-assembled monolayer on the first electrode layer 20.

[0079] It is also preferable that a passivation material be present between the hole transport layer 30 and the photoelectric conversion layer 40. The passivation material between the hole transport layer 30 and the photoelectric conversion layer 40 is not shown in Figure 1. It is preferable that a passivation material be present between the hole transport layer 30 and the photoelectric conversion layer 40.

[0080] 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. By passivating the defects in the photoelectric conversion layer, recombination of charges and holes is suppressed, improving the photoelectric conversion efficiency.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] The passivation material is not particularly limited as long as the desired effect is not impaired. The passivation material can be appropriately selected from various compounds conventionally used to form passivation layers in perovskite solar cells. Suitable examples of the passivation material include various amines or their hydrohalides. Examples of hydrohalides include hydrofluorides, hydrochlorides, hydrobromides, and hydroiodides, with hydrobromides and hydroiodides being preferred, and hydroiodides being more preferred.

[0085] Specific examples of suitable 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.

[0086] Also preferred as the passivation material are fluorine-containing amine compounds and salts thereof. 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; fluoroalkylamines, such as 6,6,6,5,5,4,4,3,3,2,2-undecafluoropentylamine hydroiodide and 5,5,5,4,4,3,3,2,2-nonafluoropentylamine hydroiodide, and salts thereof; and compounds having a fluorinated aromatic group and an amino group, such as 4-fluorophenylethylamine hydroiodide, and salts thereof.

[0087] As the passivation material, a hydrohalide salt represented by the following formula (01) is also preferred: R ０１ R ０２NC(=NH)-NH-C(=NH)-NH ２ ・HX...(01) (In formula (01), R ０１ , and R ０２ are each independently a hydrogen atom or a monovalent organic group, and X is a halogen atom.

[0088] In formula (01), R ０１ , and R ０２ are 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, 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.

[0089] 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; and methoxy groups, ethoxy groups, 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. 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.

[0090] R ０１ , and R０２ 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.

[0091] 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.

[0092] 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.

[0093] In formula (01), R ０１, and R ０２ Preferably, one of these is an aromatic hydrocarbon group which may have a substituent, and the other is a hydrogen atom.

[0094] The hydrohalide salt represented by formula (01) is represented by the following formula (01-1): ０１ R ０２ NC(=NH)-NH-C(=NH)-NH ２ ...(01-1) (In formula (01-1), R １ , and R ２ is R in formula (1). ０１ , and R ０２ and a hydrohalic acid represented by HX.

[0095] Examples of hydrohalides 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.

[0096] Preferable specific examples of the hydrohalide salt represented by formula (01) 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) ２NC(=NH)-NH-C(=NH)-NH ２ ・HI, (m-Tol) ２ NC(=NH)-NH-C(=NH)-NH ２ HI, and (p-Tol) ２ NC(=NH)-NH-C(=NH)-NH ２ ・HI is one example.

[0097] 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).

[0098] 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.

[0099] The method for producing the hydrohalide salt represented by formula (01) 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, pure water can be used in addition to organic solvents similar to those that may be contained in the liquid composition used to form the hole transport layer 30. The hydrohalic acid solution may be an aqueous solution or an organic solvent solution.

[0100] Among these, from the viewpoints of availability and the balance between cost and performance, an amine compound containing a fluorinated alkyl group moiety and / or a salt thereof, or a compound having a fluorinated aromatic group and an amino group is preferred, and a salt of an amine compound containing a fluorinated alkyl group is more preferred.

[0101] When a passivation material is present between the hole transport layer 30 and the photoelectric conversion layer 40, a passivation material solution containing the passivation material and an organic solvent is applied to the hole transport layer 30 and dried to form a thin film of the passivation material. The organic solvent can be the same as the solvent used to form the hole transport layer 30 described above. The application method 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 1 second to 24 hours, and more preferably 5 seconds to 1 hour.

[0102] It should be noted that by adding a passivation material to the liquid composition, a layer made of the passivation material can be formed on the surface of the hole transport layer 30 .

[0103] 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 NH ３ ), Formamidinium FA (CH ３ N ２ ) etc.

[0104] 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.

[0105] 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 portion 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.

[0106] 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) ３ The 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).

[0107] When a passivation material is present between the photoelectric conversion layer 40 and the electron transport layer 50, recombination of photocarriers at the interface between the photoelectric conversion layer 40 and the electron transport layer 50 is prevented, and the arrival of electrons at the electron transport layer 50 is promoted.

[0108] The passivation material present between the photoelectric conversion layer 40 and the electron transport layer 50 can be the same as the passivation material present between the hole transport layer 30 and the photoelectric conversion layer 40. The passivation material present between the photoelectric conversion layer 40 and the electron transport layer 50 is preferably the above-mentioned hydrohalide salt of an amine, an amine having a fluorinated alkyl group, or a hydrohalide salt thereof.

[0109] The passivation material may be 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 pairs on the nitrogen atoms, preventing charge recombination.

[0110] When a passivation material is present between the photoelectric conversion layer 40 and the electron transport layer 50, it can be formed by applying a passivation material solution containing a passivation material and an organic solvent onto the photoelectric conversion layer 40 and drying it, similar to the passivation material present between the hole transport layer 30 and the photoelectric conversion layer 40.

[0111] When a passivation material is contained in the perovskite precursor liquid used to form the photoelectric conversion layer 40, the perovskite precursor liquid is applied to the hole transport layer 30, dried, and the perovskite precursor is crystallized, thereby making it possible to cause the passivation material to be present on the surface and / or inside the photoelectric conversion layer 40.

[0112] Furthermore, the liquid composition containing the materials constituting the self-assembled monolayer may contain a perovskite precursor and a passivation material for forming the photoelectric conversion layer 40. In this case, by applying the liquid composition onto the first electrode layer 20 and drying it, and then crystallizing the perovskite precursor, the hole transport layer 30 and the photoelectric conversion layer 40 can be formed simultaneously, while the passivation material can be present on the surface and / or inside of the photoelectric conversion layer 40.

[0113] When the perovskite precursor liquid contains a passivation material and a perovskite precursor, fluorine-containing amine compounds and salts thereof are preferred as passivation materials because they are easily precipitated at the interface or surface of the perovskite polycrystal by utilizing the hydrophobic interaction of fluorine atoms. The content of fluorine atoms in the fluorine-containing amine compound is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, in terms of the mass of fluorine atoms in the molecular weight of each compound. When the fluorine-containing amine compound and salts thereof contain fluorine atoms in the above ratio, the fluorine-containing amine compound is easily precipitated on the perovskite crystal surface by sufficient hydrophobic interaction.

[0114] 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.

[0115] 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.

[0116] The perovskite solar cell 1 having the above configuration can be manufactured by a method including: applying the above-mentioned liquid composition to a first electrode layer 20 formed on one main surface of a plate-like or sheet-like substrate 10 to form a hole transport layer 30; forming a photoelectric conversion layer 40 containing a perovskite compound on the hole transport layer 30; forming an electron transport layer 50 on the photoelectric conversion layer 40; and forming a second electrode layer 60 on the electron transport layer.

[0117] Specifically, the perovskite solar cell 1 can be manufactured by an embodiment of a solar cell manufacturing method shown in FIG. 2 . The solar cell manufacturing method of this embodiment includes a first electrode layer forming step (step S11), a hole transport layer forming step (step S12), a precursor liquid application step (step S13), a crystallization step (step S14), an electron transport layer forming step (step S15), and a second electrode layer forming step (step S16). The embodiment of the solar cell manufacturing method shown in FIG. 2 may include a first passivation material applying step (step S01, not shown in FIG. 2 ) between the hole transport layer forming step (step S12) and the precursor liquid application step (step S13). Furthermore, when a precursor liquid not containing a passivation material is used in the precursor liquid application step (step S13), the embodiment of the solar cell manufacturing method shown in FIG. 2 may also include a second passivation material applying step (step S02, not shown in FIG. 2 ).

[0118] 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.

[0119] In the hole transport layer formation step of step S12, the hole transport layer 30 is laminated on the first electrode layer 20. The hole transport layer 30 can be formed by a method such as coating a solution containing the material that constitutes the hole transport layer 30 and an organic solvent, followed by drying. The drying temperature is, for example, preferably 50°C or higher, more preferably 80°C or higher, and even more preferably 100°C or higher. The drying time is preferably 1 minute or longer, more preferably 5 minutes or longer, and even more preferably 10 minutes or longer. When drying is performed under the above conditions, the organic solvent is sufficiently removed from the coating film, making it easier to obtain the desired crystals in the subsequent step of forming perovskite polycrystals.

[0120] After forming the hole transport layer 30 in step S12, a first passivation material application step (step S01) may be performed as necessary to apply a passivation material onto the hole transport layer 30. In the first passivation material application step (step S01), a passivation material solution containing a passivation material and an organic solvent is applied onto the hole transport layer 30, and then the applied film is dried. In this case, the passivation material can be present on the hole transport layer 30.

[0121] The passivation material solution can be applied using, for example, a spin coater, a die coater, or a bar coater.

[0122] In addition, in step S12, the passivation material can also be present on the hole transport layer 30 by applying a liquid composition containing the material that constitutes the hole transport layer 30 and the passivation material to form the hole transport layer 30.

[0123] In the precursor liquid application step of step S13, a perovskite precursor liquid is applied to a laminate of the substrate 10, the first electrode layer 20, and the hole transport layer 30. When step S01 is performed, the perovskite precursor liquid is applied onto the passivation material applied onto the hole transport layer 30. The perovskite precursor liquid can be applied using, for example, a spin coater, a die coater, a bar coater, or the like.

[0124] The perovskite precursor liquid contains an organic solvent and a perovskite precursor that forms a perovskite compound that performs photoelectric conversion. The perovskite precursor liquid may further contain a hydrochloride that promotes crystal growth of the perovskite compound.

[0125] The photoelectric conversion layer 40 may be formed using a liquid composition containing the material that constitutes the hole transport layer 30 and a perovskite precursor. In this case, step S12 of forming the hole transport layer 30 may be omitted. This is because the hole transport layer 30 is formed in the process of forming the photoelectric conversion layer 40 in steps S13 and S14.

[0126] A passivation material may be further added to the liquid composition containing the material constituting the hole transport layer 30 and the perovskite precursor. When a liquid composition containing the material constituting the hole transport layer 30, the perovskite precursor, and the passivation material is used, the photoelectric conversion layer 40 can be formed while the hole transport layer 30 is being formed by steps S13 and S14, and the passivation material can be present on the surface and / or inside of the photoelectric conversion layer 40.

[0127] The perovskite precursor liquid may contain a passivation material. In this case, the passivation material may be present on the surface and / or inside of the photoelectric conversion layer 40 during the process of forming the photoelectric conversion layer 40 in steps S13 and S14.

[0128] The perovskite precursor contained in the perovskite precursor liquid is as described above.

[0129] Examples of organic solvents include alcohols such as methanol, ethanol, and 2-methoxyethanol; 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, propyl acetate, isopropyl acetate, amyl acetate, and γ-valerolactone (GBL); and aprotic polar solvents such as acetonitrile and propionitrile. 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 solution is related to the conditions of the crystallization step. The solids concentration of the perovskite precursor solution 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 solution 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.

[0130] 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 perovskite precursor liquid during the crystallization process, thereby preventing a decrease in photoelectric conversion efficiency due to other materials remaining in the perovskite crystal.

[0131] When the perovskite precursor solution contains a passivation material, the recombination of photocarriers (holes and electrons) at the interface of the photoelectric conversion layer 40 is suppressed by the action of the passivation material present on the surface and / or inside the photoelectric conversion layer 40.

[0132] 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 The moiety 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 perovskite precursor liquid may be 1 mol % or more and 40 mol % or less relative to the molar concentration of the ions of the metal atom B in the perovskite compound.

[0133] In the crystallization step of step S14, the film of the perovskite precursor liquid is dried (the solvent is evaporated) to generate crystals of the perovskite compound. This forms a photoelectric conversion layer 40 mainly composed of the perovskite compound. If the perovskite precursor solution contains a passivation material, the photoelectric conversion layer 40 is formed, and the passivation material can be present on the surface and / or inside of the photoelectric conversion layer 40. As a method for promoting the generation of crystals of the perovskite compound in the film of the perovskite precursor liquid, for example, poor solvent quenching, vacuum quenching, gas quenching, laser treatment, etc. may be preferably employed. In the crystallization step of step S14, the dried coating film of the perovskite precursor liquid may be further heated.

[0134] After forming the photoelectric conversion layer 40 in steps S13 and S14, a second passivation material application step (step S02) may be performed as necessary to cause the passivation material to be present on the main surface of the photoelectric conversion layer 40 opposite to the hole transport layer 30. In the second passivation material application step (step S02), a passivation material solution containing a passivation material and an organic solvent is applied onto the photoelectric conversion layer 40, and the applied film is then dried to cause the passivation material to be present on the photoelectric conversion layer 40.

[0135] In the electron transport layer forming step S15, 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.

[0136] In the second electrode layer forming step S16, the second electrode layer 60 is formed by a method such as sputtering, vacuum deposition, plating, or coating depending on the forming material.

[0137] The perovskite solar cell described above exhibits high photoelectric conversion efficiency.

[0138] 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.

[0139] A second embodiment of the present invention will be described below with reference to the drawings. The dimensions of various components in the drawings have been adjusted for clarity. In the second embodiment, components similar to those in the first embodiment are designated by the same reference numerals, and redundant description may be omitted.

[0140] Second Embodiment Figure 1 is a schematic cross-sectional view showing the configuration of a perovskite solar cell 1 according to an embodiment of the present invention. The perovskite solar cell 1 includes a plate- or sheet-shaped substrate 10, a first electrode layer 20 laminated on one main surface of the substrate 10 (the lower side in Figure 1), 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, an electron transport layer 50 laminated on one surface of the photoelectric conversion layer 40, and a second electrode layer 60 (cathode) laminated on one side of the electron transport layer 50. A passivation material (not shown) may be present on and / or inside the photoelectric conversion layer 40.

[0141] 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.

[0142] 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.

[0143] 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 a compound represented by the following formula (1'): (HO) ２ P(=O)-R １ -N(Ar １ ) ２ (1') (In formula (1'), R １represents a chain aliphatic group which may have a substituent and which may contain a heteroatom, and Ar １ is an aromatic hydrocarbon group having 6 to 20 carbon atoms which may be substituted with an alkyl group having 1 to 6 carbon atoms and / or an alkoxy group having 1 to 6 carbon atoms. This monomolecular film is a so-called self-assembled monolayer (SAM).

[0144] In formula (1′), R １ R is a chain aliphatic group which may have a substituent and may contain a heteroatom. １ The chain aliphatic group represented by R may contain two or more heteroatoms, or may contain two or more types of heteroatoms. １ The chain aliphatic group as R may be linear or branched. １ The chain aliphatic group as may have one or more unsaturated bonds, and is preferably a chain saturated aliphatic group.

[0145] R １ Heteroatoms that may be contained in the chain aliphatic group as defined above include oxygen, sulfur, nitrogen, phosphorus, boron, silicon, and halogen atoms. Among these heteroatoms, oxygen and sulfur atoms are preferred. Examples of oxygen and sulfur atoms include -O-, -C(=O)-, -S-, -S-S-, -C(=S)-, -SO ２ It may be present in a chain aliphatic group as - and -S(=O)-.

[0146] R １ Suitable examples of the chain aliphatic group as -R include an alkylene group, １１ -O-R １２ -, -R １３ -C(=O)-R １４ -, -R １５ -C(=O)-OR １７ - and -R １８ -S-R １９ - is mentioned. １１ ~R １９are each independently an alkylene group having 1 to 6 carbon atoms, preferably an alkylene group having 1 to 3 carbon atoms.

[0147] R １ The chain aliphatic group as R is preferably an alkylene group, more preferably an alkylene group having 1 to 6 carbon atoms. １ Specific preferred examples of the alkylene group as the alkylene group include a methylene group, an ethane-1,2-diyl group (ethylene group), an ethane-1,1-diyl group, a propane-1,3-diyl group (propylene group), a propane-1,2-diyl group (butylene group), a propane-2,2-diyl group, a butane-1,4-diyl group, a butane-1,3-diyl group, a butane-1,2-diyl group, a pentane-1,5-diyl group, and a hexane-1,6-diyl group. Among these alkylene groups, a methylene group, an ethane-1,2-diyl group (ethylene group), a propane-1,3-diyl group (propylene group), a butane-1,4-diyl group, and a butane-1,3-diyl group (butylene group) are preferred, and an ethane-1,2-diyl group (ethylene group), a propane-1,3-diyl group (propylene group), and a butane-1,3-diyl group (butylene group) are more preferred.

[0148] In formula (1′), Ar １ Ar is an aromatic hydrocarbon group having 6 to 20 carbon atoms which may be substituted with an alkyl group having 1 to 6 carbon atoms and / or an alkoxy group having 1 to 6 carbon atoms. １ The aromatic hydrocarbon group preferably has 6 or more and 12 or less carbon atoms.

[0149] Ar １Specific examples of the substituent that the aromatic hydrocarbon group may have include an alkyl group having from 1 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, a halogen atom, a hydroxyl group, a nitro group, and a cyano group. Examples of the alkyl group having from 1 to 6 carbon atoms include 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. Examples of the alkoxy group having from 1 to 6 carbon atoms include 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. The position at which these substituents are bonded to the aromatic hydrocarbon group is not particularly limited, but may be determined arbitrarily in consideration of the electrical properties of the compound represented by formula (1'), such as HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital).

[0150] Ar １ The number of alkyl groups having 1 to 6 carbon atoms and / or alkoxy groups having 1 to 6 carbon atoms contained in the aromatic hydrocarbon group represented by formula (I) is, for example, preferably 0 to 4, more preferably 0 to 3, even more preferably 0 to 2, and particularly preferably 0 or 1.

[0151] Ar １ Examples of the aromatic hydrocarbon group having 6 to 20 carbon atoms as the aromatic hydrocarbon group include a phenyl group, a naphthalene-1-yl group, a naphthalene-2-yl group, an o-phenylphenyl group, an m-phenylphenyl group, a p-phenylphenyl group, an anthracen-1-yl group, an anthracen-2-yl group, an anthracen-9-yl group, a phenanthrene-1-yl group, a phenanthrene-2-yl group, a phenanthrene-3-yl group, a phenanthrene-4-yl group, and a phenanthrene-9-yl group.

[0152] Ar １When the phenyl group as the substituted phenyl group is substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms, examples of the substituted phenyl group include an o-methylphenyl group, an m-methylphenyl group, a p-methylphenyl group, 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. Among these, an m-methylphenyl group, a p-phenylmethyl group, an m-methoxyphenyl group, and a p-methoxymethyl group are preferred, an m-methoxyphenyl group and a p-methoxymethyl group are more preferred, and a p-methoxymethyl group is even more preferred.

[0153] The above-described Ar １ As the aromatic hydrocarbon group having from 6 to 20 carbon atoms which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms, a phenyl group, a m-methylphenyl group, a p-phenylmethyl group, a m-methoxyphenyl group, a p-methoxymethyl group, a naphthalen-1-yl group, a naphthalen-2-yl group, a m-phenylphenyl group, and a p-phenylphenyl group are preferred.

[0154] Specific preferred examples of the diarylamine compound represented by formula (1') include the following compounds: In the following formula, Me is a methyl group.

[0155]

[0156]

[0157]

[0158] The compound represented by formula (1') is preferably a compound having a small difference between the HOMO of the compound and the VB edge (Valence Band) of the perovskite compound constituting the photoelectric conversion layer 40. The HOMO difference is preferably 0.00 to 1.00 eV, more preferably 0.00 to 0.50 eV, and even more preferably 0.00 to 0.30 eV. The HOMO can be determined by photoelectron spectroscopy or quantum chemical calculations based on density functional theory. In this case, the exchange-correlation functional is B3LYP, and the basis functions used are 6-311G(d) for molecular structure optimization and 6-311++G(d,p) for energy calculation.

[0159] The method for producing the diarylamine compound represented by formula (1') is not particularly limited. The diarylamine compound represented by formula (1') can be synthesized, for example, by the following method.

[0160] Specifically, first, a haloarylphosphonic acid diester represented by the following formula (1′a) and HN(Ar １ ) ２ In the presence of a base, a diarylamine compound having a phosphonic acid diester group represented by the following formula (1′b) is reacted with a diarylamine compound represented by the following formula (1′a) according to a well-known method. １１ is a monovalent organic group, preferably a hydrocarbon group. The hydrocarbon group is preferably an alkyl group, more preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group or an ethyl group. Next, the phosphonic acid diester group in the diarylamine compound having the phosphonic acid diester group represented by formula (1'b) is hydrolyzed by a well-known method to obtain the diarylamine compound represented by formula (1'). (R １１ O) ２ P(=O)-R １ -Hal (1'a) (R １１ O) ２ P(=O)-R １ -N(Ar １ ) ２ (1′b) (In formula (1′a) and formula (1b), R１ , and Ar １ are the same as those in formula (1'). Hal is a halogen atom. R １１ is a monovalent organic group.

[0161] The above method is merely an example, and the diarylamine compound represented by formula (1') may be produced by combining various known methods as necessary.

[0162] The self-assembled monolayer serving as the hole transport layer 30 may contain, in addition to the diarylamine compound represented by formula (1'), a compound other than the diarylamine compound represented by formula (1').

[0163] The self-assembled monolayer serving as the hole transport layer 30 may contain, in addition to the diarylamine compound represented by formula (1'), a compound other than the diarylamine compound represented by formula (1'). The other compound is preferably a carbazole compound. 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 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 serving as the hole transport layer 30.

[0164] When the hole transport layer 30 contains a carbazole compound together with the diarylamine compound represented by formula (1′), examples of the carbazole compound include N-(2-phosphonoethyl)carbazole (2PACz), N-(2-phosphonoethyl)-3,6-dimethoxycarbazole (MeO-2PACz), N-(2-phosphonoethyl)-3,6-dimethylcarbazole (Me-2PACz), and N-(3-phosphonopropyl)carbazole (3PACz). , N-(3-phosphonopropyl)-3,6-dimethoxycarbazole (MeO-3PACz), N-(3-phosphonopropyl)-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). Among these, 2PACz, MeO-2PACz, Me-2PACz, MeO-4PACz, and Me-4PACz are more preferred.

[0165] It is also preferable that the hole transport layer 30 contains a triarylamine compound represented by the following formula (2') in addition to the diarylamine compound represented by formula (1').

[0166] (HO) ２ P(=O)-Ar ２ -N(Ar １ ) ２ (2') (In formula (2'), Ar ２ is a divalent aromatic hydrocarbon group which may have a substituent, and Ar １ is Ar １ is an aromatic hydrocarbon group having 6 to 20 carbon atoms which may be substituted with an alkyl group having 1 to 6 carbon atoms and / or an alkoxy group having 1 to 6 carbon atoms.

[0167] Ar in formula (2') １ is Ar in formula (1'). １ is the same as:

[0168] In formula (2'), Ar ２ is a divalent aromatic hydrocarbon group which may have a substituent.２ The number of carbon atoms in the divalent aromatic hydrocarbon group as Ar is preferably 6 or more and 30 or less, more preferably 6 or more and 20 or less, and even more preferably 6 or more and 12 or less. ２ Specific examples of the divalent aromatic hydrocarbon group as Ar include phenylene groups such as o-phenylene, m-phenylene, and p-phenylene; naphthylene groups such as naphthalene-1,2-diyl, naphthalene-1,3-diyl, naphthalene-1,4-diyl, naphthalene-1,5-diyl, naphthalene-1,7-diyl, naphthalene-1,8-diyl, naphthalene-2,3-diyl, naphthalene-2,6-diyl, and naphthalene-2,7-diyl; and biphenyldiyl groups such as biphenyl-4,4'-diyl, biphenyl-3,4'-diyl, and biphenyl-3,3'-diyl. ２ The divalent aromatic hydrocarbon group as may be an anthracenediyl group, a phenanthrenediyl group, a terphenyldiyl group, or the like.

[0169] Ar ２ The divalent aromatic hydrocarbon group as is preferably an m-phenylene group, a p-phenylene group, a naphthalene-1,4-diyl group, a naphthalene-2,6-diyl group, a naphthalene-2,7-diyl group, a biphenyl-4,4'-diyl group, a biphenyl-3,4'-diyl group, or a biphenyl-3,3'-diyl group, more preferably a p-phenylene group, a naphthalene-2,6-diyl group, a naphthalene-2,7-diyl group, or a biphenyl-4,4'-diyl group, and particularly preferably a p-phenylene group.

[0170] Ar ２Specific examples of the substituent that the divalent aromatic hydrocarbon group may have include an alkyl group having from 1 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, a halogen atom, a hydroxyl group, a nitro group, and a cyano group. Examples of the alkyl group having from 1 to 6 carbon atoms include 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. Examples of the alkoxy group having from 1 to 6 carbon atoms include 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.

[0171] Specific examples of suitable triarylamine compounds represented by formula (2') include (diphenylamino)phenylphosphonic acids such as 2-(N,N-diphenylamino)phenylphosphonic acid, 3-(N,N-diphenylamino)phenylphosphonic acid, and 4-(N,N-diphenylamino)phenylphosphonic acid; 2-(4-N,N-diphenylaminophenyl)phenylphosphonic acid, 3-(4-N,N-diphenylaminophenyl)phenylphosphonic acid, 4-(4-N,N-diphenylaminophenyl)phenylphosphonic acid, 2-(3-N,N-diphenylaminophenyl)phenylphosphonic acid, 3-(3-N,N-diphenylaminophenyl)phenylphosphonic acid, 4-(3-N, (diphenylamino)biphenylphosphonic acids such as 2-(N-diphenylaminophenyl)phenylphosphonic acid, 2-(2-N,N-diphenylaminophenyl)phenylphosphonic acid, 3-(2-N,N-diphenylaminophenyl)phenylphosphonic acid, and 4-(2-N,N-diphenylaminophenyl)phenylphosphonic acid; and (diphenylamino)naphthylphosphonic acids such as 4-(N,N-diphenylamino)naphthalen-1-ylphosphonic acid, 5-(N,N-diphenylamino)naphthalen-2-ylphosphonic acid, 6-(N,N-diphenylamino)naphthalen-2-ylphosphonic acid, and 7-(N,N-diphenylamino)naphthalen-2-ylphosphonic acid.

[0172] The following compounds are also preferred as the triarylamine compounds represented by formula (2').

[0173]

[0174]

[0175] The ratio of the number of moles of the diarylamine compound represented by formula (1') to the total number of moles of compounds constituting the self-assembled monolayer as the hole transport layer 30 is not particularly limited as long as the desired effect is not impaired. The ratio of the number of moles of the diarylamine compound represented by formula (1') to the total number of moles of compounds constituting the self-assembled monolayer as the hole transport layer 30 is preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 70 mol% or more, particularly preferably 90 mol% or more, and most preferably 100 mol%.

[0176] The hole transport layer 30 may contain, as compounds other than the diarylamine compound represented by formula (1'), 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, phosphonic acid compounds such as 1H,1H,2H,2H-perfluorophosphonic acid, acetic acid, propionic acid, isobutyric acid, nonanoic acid, fluoroacetic acid, α-chloropropionic acid, and glyoxylic acid. These compounds may be used alone or in combination of two or more.

[0177] The hole transport layer 30 can be formed by applying and drying a liquid composition containing the diarylamine compound represented by the above-mentioned formula (1'). The liquid composition may contain, in addition to the diarylamine compound represented by formula (1'), a compound other than the diarylamine compound represented by formula (1'). The compound other than the diarylamine compound represented by formula (1') is as described above.

[0178] The liquid composition used to form the hole transport layer 30 usually contains an organic solvent. Examples of organic solvents include alcohols such as methanol, ethanol, 2-methoxyethanol, 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, propyl acetate, isopropyl acetate, butyl acetate, isoamyl acetate, and γ-butyrolactone (GBL); nitriles such as acetonitrile, propionitrile, 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. These may be used alone or in combination of two or more.

[0179] The total concentration of the materials constituting the self-assembled monolayer contained in the liquid composition is preferably 5.0 mg / mL or less.

[0180] The liquid composition may contain a perovskite precursor, which will be described later and is used to form the photoelectric conversion layer 40. When a liquid composition containing a perovskite precursor is used, the hole transport layer 30 and the photoelectric conversion layer 40 can be formed simultaneously by applying the liquid composition to the first electrode layer 20, drying it, and crystallizing the perovskite precursor. In this case, in the process of forming the photoelectric conversion layer 40, a compound such as the diarylamine compound represented by formula (1′) contained in the perovskite precursor liquid forms a self-assembled monolayer on the first electrode layer 20.

[0181] It is also preferable that a passivation material be present between the hole transport layer 30 and the photoelectric conversion layer 40. The passivation material between the hole transport layer 30 and the photoelectric conversion layer 40 is not shown in Figure 1. It is preferable that a passivation material be present between the hole transport layer 30 and the photoelectric conversion layer 40.

[0182] 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. By passivating the defects in the photoelectric conversion layer, recombination of charges and holes is suppressed, improving the photoelectric conversion efficiency.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] The passivation material is not particularly limited as long as the desired effect is not impaired. The passivation material can be appropriately selected from various compounds conventionally used to form passivation layers in perovskite solar cells. Suitable examples of the passivation material include various amines or their hydrohalides. Examples of hydrohalides include hydrofluorides, hydrochlorides, hydrobromides, and hydroiodides, with hydrobromides and hydroiodides being preferred, and hydroiodides being more preferred.

[0187] Specific examples of suitable 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.

[0188] Also preferred as the passivation material are fluorine-containing amine compounds and salts thereof. 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; fluoroalkylamines, such as 6,6,6,5,5,4,4,3,3,2,2-undecafluoropentylamine hydroiodide and 5,5,5,4,4,3,3,2,2-nonafluoropentylamine hydroiodide, and salts thereof; and compounds having a fluorinated aromatic group and an amino group, such as 4-fluorophenylethylamine hydroiodide, and salts thereof.

[0189] As the passivation material, a hydrohalide salt represented by the following formula (01′) is also preferred: R ０１ R ０２２NC(=NH)-NH-C(=NH)-NH ２ ・HX...(01') (In formula (01'), R ０１ , and R ０２ are each independently a hydrogen atom or a monovalent organic group, and X is a halogen atom.

[0190] In formula (01'), R ０１ , and R ０２ are 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, 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.

[0191] 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; and methoxy groups, ethoxy groups, 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. 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.

[0192] R ０１, and R ０２ 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.

[0193] 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.

[0194] 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.

[0195] In formula (01′), R０１ , and R ０２ Preferably, one of these is an aromatic hydrocarbon group which may have a substituent, and the other is a hydrogen atom.

[0196] The hydrohalide salt represented by formula (01′) is represented by the following formula (01′-1): ０１ R ０２ NC(=NH)-NH-C(=NH)-NH ２ ...(01'-1) (In formula (01'-1), R １ , and R ２ is R in formula (1′). ０１ , and R ０２ and a hydrohalic acid represented by HX.

[0197] Examples of hydrohalides 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.

[0198] Preferable specific examples of the hydrohalide salt represented by formula (01') 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 ２ HI, and (p-Tol) ２ NC(=NH)-NH-C(=NH)-NH ２ ・HI is one example.

[0199] 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).

[0200] 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.

[0201] The method for producing the hydrohalide salt represented by formula (01') 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, pure water can be used in addition to organic solvents similar to those that may be contained in the liquid composition used to form the hole transport layer 30. The hydrohalic acid solution may be an aqueous solution or an organic solvent solution.

[0202] Among these, from the viewpoints of availability and the balance between cost and performance, an amine compound containing a fluorinated alkyl group moiety and / or a salt thereof, or a compound having a fluorinated aromatic group and an amino group is preferred, and a salt of an amine compound containing a fluorinated alkyl group is more preferred.

[0203] When a passivation material is present between the hole transport layer 30 and the photoelectric conversion layer 40, a passivation material solution containing the passivation material and an organic solvent is applied to the hole transport layer 30 and dried to form a thin film of the passivation material. The organic solvent can be the same as the solvent used to form the hole transport layer 30 described above. The application method 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 1 second to 24 hours, and more preferably 5 seconds to 1 hour.

[0204] It should be noted that by adding a passivation material to the liquid composition, a layer made of the passivation material can be formed on the surface of the hole transport layer 30 .

[0205] 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 NH ３ ), Formamidinium FA (CH ３ N ２ ) etc.

[0206] 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.

[0207] 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 portion 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.

[0208] 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) ３ The 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).

[0209] When a passivation material is present between the photoelectric conversion layer 40 and the electron transport layer 50, recombination of photocarriers at the interface between the photoelectric conversion layer 40 and the electron transport layer 50 is prevented, and the arrival of electrons at the electron transport layer 50 is promoted.

[0210] The passivation material present between the photoelectric conversion layer 40 and the electron transport layer 50 can be the same as the passivation material present between the hole transport layer 30 and the photoelectric conversion layer 40. The passivation material present between the photoelectric conversion layer 40 and the electron transport layer 50 is preferably the above-mentioned hydrohalide salt of an amine, an amine having a fluorinated alkyl group, or a hydrohalide salt thereof.

[0211] The passivation material may be 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 pairs on the nitrogen atoms, preventing charge recombination.

[0212] When a passivation material is present between the photoelectric conversion layer 40 and the electron transport layer 50, it can be formed by applying a passivation material solution containing a passivation material and an organic solvent onto the photoelectric conversion layer 40 and drying it, similar to the passivation material present between the hole transport layer 30 and the photoelectric conversion layer 40.

[0213] When a passivation material is contained in the perovskite precursor liquid used to form the photoelectric conversion layer 40, the perovskite precursor liquid is applied to the hole transport layer 30, dried, and the perovskite precursor is crystallized, thereby making it possible to cause the passivation material to be present on the surface and / or inside the photoelectric conversion layer 40.

[0214] Furthermore, the liquid composition containing the materials constituting the self-assembled monolayer may contain a perovskite precursor and a passivation material for forming the photoelectric conversion layer 40. In this case, by applying the liquid composition onto the first electrode layer 20 and drying it, and then crystallizing the perovskite precursor, the hole transport layer 30 and the photoelectric conversion layer 40 can be formed simultaneously, while the passivation material can be present on the surface and / or inside of the photoelectric conversion layer 40.

[0215] When the perovskite precursor liquid contains a passivation material and a perovskite precursor, fluorine-containing amine compounds and salts thereof are preferred as passivation materials because they are easily precipitated at the interface or surface of the perovskite polycrystal by utilizing the hydrophobic interaction of fluorine atoms. The content of fluorine atoms in the fluorine-containing amine compound is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, in terms of the mass of fluorine atoms in the molecular weight of each compound. When the fluorine-containing amine compound and salts thereof contain fluorine atoms in the above ratio, the fluorine-containing amine compound is easily precipitated on the perovskite crystal surface by sufficient hydrophobic interaction.

[0216] 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.

[0217] 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.

[0218] The perovskite solar cell 1 having the above configuration can be manufactured by a method including: applying the above-mentioned liquid composition to a first electrode layer 20 formed on one main surface of a plate-like or sheet-like substrate 10 to form a hole transport layer 30; forming a photoelectric conversion layer 40 containing a perovskite compound on the hole transport layer 30; forming an electron transport layer 50 on the photoelectric conversion layer 40; and forming a second electrode layer 60 on the electron transport layer.

[0219] Specifically, the perovskite solar cell 1 can be manufactured by an embodiment of a solar cell manufacturing method shown in FIG. 2 . The solar cell manufacturing method of this embodiment includes a first electrode layer forming step (step S11), a hole transport layer forming step (step S12), a precursor liquid application step (step S13), a crystallization step (step S14), an electron transport layer forming step (step S15), and a second electrode layer forming step (step S16). The embodiment of the solar cell manufacturing method shown in FIG. 2 may include a first passivation material applying step (step S01, not shown in FIG. 2 ) between the hole transport layer forming step (step S12) and the precursor liquid application step (step S13). Furthermore, when a precursor liquid not containing a passivation material is used in the precursor liquid application step (step S13), the embodiment of the solar cell manufacturing method shown in FIG. 2 may also include a second passivation material applying step (step S02, not shown in FIG. 2 ).

[0220] 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.

[0221] In the hole transport layer formation step of step S12, the hole transport layer 30 is laminated on the first electrode layer 20. The hole transport layer 30 can be formed by a method such as coating a solution containing the material that constitutes the hole transport layer 30 and an organic solvent, followed by drying. The drying temperature is, for example, preferably 50°C or higher, more preferably 80°C or higher, and even more preferably 100°C or higher. The drying time is preferably 1 minute or longer, more preferably 5 minutes or longer, and even more preferably 10 minutes or longer. When drying is performed under the above conditions, the organic solvent is sufficiently removed from the coating film, making it easier to obtain the desired crystals in the subsequent step of forming perovskite polycrystals.

[0222] After forming the hole transport layer 30 in step S12, a first passivation material application step (step S01) may be performed as necessary to apply a passivation material onto the hole transport layer 30. In the first passivation material application step (step S01), a passivation material solution containing a passivation material and an organic solvent is applied onto the hole transport layer 30, and then the applied film is dried. In this case, the passivation material can be present on the hole transport layer 30.

[0223] The passivation material solution can be applied using, for example, a spin coater, a die coater, or a bar coater.

[0224] In addition, in step S12, the passivation material can also be present on the hole transport layer 30 by applying a liquid composition containing the material that constitutes the hole transport layer 30 and the passivation material to form the hole transport layer 30.

[0225] In the precursor liquid application step of step S13, a perovskite precursor liquid is applied to a laminate of the substrate 10, the first electrode layer 20, and the hole transport layer 30. When step S01 is performed, the perovskite precursor liquid is applied onto the passivation material applied onto the hole transport layer 30. The perovskite precursor liquid can be applied using, for example, a spin coater, a die coater, a bar coater, or the like.

[0226] The perovskite precursor liquid contains an organic solvent and a perovskite precursor that forms a perovskite compound that performs photoelectric conversion. The perovskite precursor liquid may further contain a hydrochloride that promotes crystal growth of the perovskite compound.

[0227] The photoelectric conversion layer 40 may be formed using a liquid composition containing the material that constitutes the hole transport layer 30 and a perovskite precursor. In this case, step S12 of forming the hole transport layer 30 may be omitted. This is because the hole transport layer 30 is formed in the process of forming the photoelectric conversion layer 40 in steps S13 and S14.

[0228] A passivation material may be further added to the liquid composition containing the material constituting the hole transport layer 30 and the perovskite precursor. When a liquid composition containing the material constituting the hole transport layer 30, the perovskite precursor, and the passivation material is used, the photoelectric conversion layer 40 can be formed while the hole transport layer 30 is being formed by steps S13 and S14, and the passivation material can be present on the surface and / or inside of the photoelectric conversion layer 40.

[0229] The perovskite precursor liquid may contain a passivation material. In this case, the passivation material may be present on the surface and / or inside of the photoelectric conversion layer 40 during the process of forming the photoelectric conversion layer 40 in steps S13 and S14.

[0230] The perovskite precursor contained in the perovskite precursor liquid is as described above.

[0231] Examples of organic solvents include alcohols such as methanol, ethanol, and 2-methoxyethanol; 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, propyl acetate, isopropyl acetate, amyl acetate, and γ-valerolactone (GBL); and aprotic polar solvents such as acetonitrile and propionitrile. 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 solution is related to the conditions of the crystallization step. The solids concentration of the perovskite precursor solution 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 solution 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.

[0232] 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 perovskite precursor liquid during the crystallization process, thereby preventing a decrease in photoelectric conversion efficiency due to other materials remaining in the perovskite crystal.

[0233] When the perovskite precursor solution contains a passivation material, the recombination of photocarriers (holes and electrons) at the interface of the photoelectric conversion layer 40 is suppressed by the action of the passivation material present on the surface and / or inside the photoelectric conversion layer 40.

[0234] 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 The moiety 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 perovskite precursor liquid may be 1 mol % or more and 40 mol % or less relative to the molar concentration of the ions of the metal atom B in the perovskite compound.

[0235] In the crystallization step of step S14, the film of the perovskite precursor liquid is dried (the solvent is evaporated) to generate crystals of the perovskite compound. This forms a photoelectric conversion layer 40 mainly composed of the perovskite compound. If the perovskite precursor solution contains a passivation material, the photoelectric conversion layer 40 is formed, and the passivation material can be present on the surface and / or inside of the photoelectric conversion layer 40. As a method for promoting the generation of crystals of the perovskite compound in the film of the perovskite precursor liquid, for example, poor solvent quenching, vacuum quenching, gas quenching, laser treatment, etc. may be preferably employed. In the crystallization step of step S14, the dried coating film of the perovskite precursor liquid may be further heated.

[0236] After forming the photoelectric conversion layer 40 in steps S13 and S14, a second passivation material application step (step S02) may be performed as necessary to cause the passivation material to be present on the main surface of the photoelectric conversion layer 40 opposite to the hole transport layer 30. In the second passivation material application step (step S02), a passivation material solution containing a passivation material and an organic solvent is applied onto the photoelectric conversion layer 40, and the applied film is then dried to cause the passivation material to be present on the photoelectric conversion layer 40.

[0237] In the electron transport layer forming step S15, 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.

[0238] In the second electrode layer forming step S16, the second electrode layer 60 is formed by a method such as sputtering, vacuum deposition, plating, or coating depending on the forming material.

[0239] The perovskite solar cell described above exhibits high photoelectric conversion efficiency.

[0240] 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.

[0241] The first embodiment of the present invention will be specifically described below based on examples, but the present invention is not limited to the following examples.

[0242] <Synthesis Example 1> Synthesis of SAM-1 Tri-tert-butylphosphine (40 μL) was added to a mixture of diethyl (4-bromophenyl)phosphonate (0.701 g), 4,4′-dimethoxydiphenylamine (0.579 g), palladium acetate (0.026 g), potassium carbonate (1.08 g), and 10 mL of xylene, which was being stirred under a nitrogen atmosphere at room temperature. The reaction mixture was then stirred at 120° C. for 21 hours. Thereafter, the reaction mixture was filtered through Celite. Volatiles were removed from the obtained filtrate by distillation under reduced pressure. The crude product obtained as the residue was purified by silica gel column chromatography to obtain diethyl 4-(N,N-di(4-methoxyphenyl)amino)phenylphosphonate as a pale purple solid, as intermediate A-1. The obtained intermediate A-1 １ H-NMR was as follows: １ H-NMR (400MHz, CDCl ３ ): δ = 7.56 (m, 2H), 7.13 (m, 4H), 6.93-6.82 (m, 6H), 4.10 (m, 4H), 3.83 (s, 6H), 1.34 (t, 6H)

[0243] Next, the obtained intermediate A-1 (0.340 g) was dissolved in 2 mL of 1,4-dioxane. To the solution of the intermediate stirred at room temperature, 1.20 mL of trimethylsilyl bromide was added, and the mixture was stirred at room temperature for 21 hours. Then, the volatile matter was distilled off under reduced pressure. The obtained crude product was mixed with 2.0 mL of methanol and 2.5 mL of pure water, and the mixture was stirred at room temperature for 5 hours. Then, the precipitate was filtered and washed three times with 2 mL of pure water. The volatile matter was distilled off under vacuum at 70°C, yielding SAM-1 as a pale purple solid. １ H-NMR was as follows: １ H-NMR (400 MHz, DMSO-d6): δ = 7.44 (m, 2H), 7.08 (m, 4H), 6.95 (m, 4H), 6.72 (m, 2H), 3.75 (s, 6H). The HOMO and LUMO of SAM-1 obtained from the above-mentioned DFT calculation were −5.30 eV and −1.09 eV, respectively.

[0244] <Synthesis Example 2> Synthesis of SAM-2 Tri-tert-butylphosphine (40 μL) was added to a mixture of diethyl (4-bromophenyl)phosphonate (0.692 g), diphenylamine (0.424 g), palladium acetate (0.024 g), potassium carbonate (1.04 g), and 10 mL of xylene, which was being stirred under a nitrogen atmosphere at room temperature. The reaction mixture was then stirred at 120°C for 21 hours. Thereafter, the reaction mixture was filtered through Celite. Volatiles were removed from the obtained filtrate by distillation under reduced pressure. The crude product obtained as a residue was purified by silica gel column chromatography to obtain diethyl 4-(N,N-diphenylamino)phenylphosphonate as a brown liquid, as intermediate A-2. １ H-NMR was as follows: １ H-NMR (400MHz, CDCl ３ ): δ = 7.66-7.57 (m, 2H), 7.36-7.30 (t, 4H), 7.19-7.11 (m, 6H), 7.07-7.02 (dd, 2H), 4.25-4.04 (m, 4H), 1.35 (t, 6H)

[0245] Next, the obtained intermediate A-2 (0.340 g) was dissolved in 2 mL of 1,4-dioxane. To the solution of the intermediate stirred at room temperature, 1.20 mL of trimethylsilyl bromide was added, and the mixture was stirred at room temperature for 21 hours. Then, the volatile matter was distilled off under reduced pressure. The obtained crude product was mixed with 2.0 mL of methanol and 2.5 mL of pure water, and the mixture was stirred at room temperature for 5 hours. Then, the precipitate was filtered and washed three times with 2 mL of pure water. The volatile matter was distilled off under vacuum at 70°C, and a white solid, SAM-2, was obtained. １ H-NMR was as follows: １ H-NMR (400MHz, DMSO-d ６ ): δ = 7.54 (m, 2H), 7.35 (t, 4H), 7.12 (t, 2H), 7.07 (d, 4H), 6.95 (dd, 2H). The HOMO of SAM-2 obtained from the above-mentioned DFT calculation was −5.63 eV, and the LUMO was −1.31 eV.

[0246] <Synthesis Example 3> Synthesis of SAM-3 Tri-tert-butylphosphine (35 μL) was added to a mixture of diethyl (4-bromophenyl)phosphonate (0.495 g), 4,4′-dimethyldiphenylamine (0.495 g), palladium acetate (0.023 g), potassium carbonate (0.995 g), and 10 mL of xylene, which was being stirred under a nitrogen atmosphere at room temperature. The reaction mixture was then stirred at 120° C. for 21 hours. Thereafter, the reaction mixture was filtered through Celite. Volatiles were removed from the obtained filtrate by distillation under reduced pressure. The crude product obtained as the residue was purified by silica gel column chromatography to obtain diethyl 4-(N,N-di(4-methylphenyl)amino)phenylphosphonate as a pale purple solid, as intermediate A-3. The obtained intermediate A-3 １ H-NMR was as follows: １ H-NMR (400MHz, CDCl ３ ): δ = 7.56 (m, 2H), 7.10 (m, 4H), 6.85 (m, 6H), 4.12 (m, 4H), 2.25 (s, 6H), 1.34 (t, 6H)

[0247] Next, the obtained intermediate A-3 (0.250 g) was dissolved in 2 mL of 1,4-dioxane. 1.00 mL of trimethylsilyl bromide was added to the solution of the intermediate stirred at room temperature, and the mixture was stirred at room temperature for 25 hours. Then, the volatile matter was distilled off under reduced pressure. 3.0 mL of methanol and 3.0 mL of pure water were added to the obtained crude product, and the mixture was stirred at room temperature for 24 hours. Then, the precipitate was filtered and washed three times with 3 mL of pure water. The volatile matter was distilled off under vacuum at 70°C, and a pale purple solid, SAM-3, was obtained. １ H-NMR was as follows: １ H-NMR (400MHz, DMSO-d6): δ = 7.40 (m, 2H), 7.05 (m, 4H), 6.90 (m, 4H), 6.72 (m, 2H), 2.20 (s, 6H)

[0248] <Synthesis Example 4> SAM-4 4-Bromophenol (2.07 g), diethyl (3-bromopropyl)phosphonate (2.58 g), potassium carbonate (1.33 g), and N,N-dimethylformamide (50 ml) were weighed, mixed, and stirred at 100°C for 10 hours. Next, 70 ml of pure water was added, and the mixture was extracted four times with 15 ml of ethyl acetate. The obtained organic phase was washed once with 20 ml of saturated aqueous potassium carbonate solution, five times with 20 ml of pure water, and once with 15 ml of saturated saline, and then dried over magnesium sulfate. Volatiles were distilled off under reduced pressure. The obtained crude product was purified by silica gel chromatography to obtain A-4 (1.32 g) as a colorless, transparent liquid. The obtained compound A-4 １ H-NMR was as follows: １ H-NMR (400MHz, CDCl ３): δ = 7.37 (m, 2H), 6.77 (m, 2H), 4.11 (m, 4H), 3.98 (t, 2H), 2.08 (m, 2H), 1.92 (m, 2H), 1.32 (t, 6H). Next, A-4 (0.31 g), bis(4-biphenyl)amine (0.292 g), potassium carbonate (0.357 g), palladium acetate (0.0194 g), tri-tert-butylphosphine (63 μL), and xylene (4 ml) were mixed and stirred at 120°C for 17 hours. The reaction mixture was filtered through Celite, and volatiles were distilled off from the obtained filtrate under reduced pressure. The obtained crude product was purified by silica gel chromatography to obtain A-5 (0.221 g) as a colorless, transparent liquid. １ H-NMR was as follows: １ H-NMR (400MHz, CDCl ３ ): δ = 7.57 (d, 4H), 7.47 (d, 4H), 7.41 (t, 4H), 7.30 (m, 2H), 7.14 (m, 6H), 6.88 (m, 2H), 4.02 (m, 2H), 2.09 (m, 2H), 1.96 (m, 2H). Next, the obtained A-5 (0.221 g) was dissolved in 1 ml of dichloromethane, and 0.75 ml of trimethylsilyl bromide was added and reacted at room temperature for 17 hours. Thereafter, the volatile matter was distilled off under reduced pressure, and 0.5 ml of methanol was added to the obtained crude product, and 1 ml of pure water was added, followed by stirring at room temperature for 24 hours. Thereafter, the precipitate was filtered and washed three times with 1 ml of pure water, and the volatile matter was distilled off under reduced pressure to obtain a green solid, SAM-4 (0.117 g). The obtained compound SAM-4 １ H-NMR was as follows: １ H-NMR (400MHz, DMSO-d ６ ): δ = 7.65 (dd, 8H), 7.43 (t, 4H), 7.31 (t, 2H), 7.10 (d, 2H), 7.05 (d, 4H), 6.97 (d, 2H), 4.03 (t, 2H), 1.91 (m, 2H), 1.67 (m, 2H)

[0249] <Synthesis Example 5> SAM-5 SAM-5 was obtained in the same manner as in Synthesis Example 4, except that bis(4-biphenyl)amine was changed to 2,2'-dinaphthylamine. １H-NMR was as follows: １ H-NMR (400MHz, DMSO-d ６ ): δ = 7.82 (m, 4H), 7.67 (d, 2H), 7.47-7.30 (m, 6H), 7.24 (dd, 2H), 7.11 (m, 2H) 6.93 (d, 2H), 4.03 (m, 2H), 1.92 (m, 2H), 1.67 (m, 2H)

[0250] In this way, the triphenylamine compounds represented by formula (1) and formula (1-1) can be obtained by a simple method.

[0251] Next, cell performance was evaluated using SAM-1, SAM-2 (4-(N,N-diphenylamino)phenylphosphonic acid), SAM-3, SAM-4, and SAM-5. SAM-2 is a triarylamine compound represented by the above formula (2).

[0252] Example 1a: First, a NiOx film was formed on the FTO layer of a commercially available glass / FTO substrate. The glass / FTO substrate was a substrate in which FTO constituting the first electrode layer was 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 1.0 mg / mL was spin-coated onto the NiOx layer. SAM-1 obtained in Example 1a was used as the material for forming the hole transport layer. The coating film formed by spin-coating was dried at 100°C for 10 minutes to form a hole transport layer. A solution of 4-fluorophenylethylamine hydroiodide dissolved in DMF at a concentration of 80 mM was spin-coated onto the hole transport layer. The coating film formed by spin-coating was dried at 100°C for 5 minutes to attach a passivation material onto the hole transport layer. A perovskite precursor solution, in which the perovskite precursor was dissolved in a mixed solvent of DMSO and DMF at a volume ratio of 1:4 to a total solid concentration of 3.2 M, was spin-coated onto the hole transport layer to which the passivation material had been attached, and a poor solvent was added dropwise to obtain a coating film. ２A mixture of FAI (metal halide) and MABr (halogenated organic compound) in a molar ratio of 1:0.83:0.17 was used. 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 dissolved in 2-propanol at a concentration of 0.25 mmol / L was spin coated onto the photoelectric conversion layer. The coating film formed by spin coating was dried at 100°C for 10 minutes to adhere a passivation material onto the photoelectric conversion layer. Further, fullerene was vapor-deposited to a thickness of 20 nm as an electron transport layer, followed by a 220 nm thick SnO ２ A thin film was formed by atomic deposition, and silver was then vapor-deposited to a thickness of 100 nm. A second electrode layer was then laminated on the electron transport layer with the passivation material attached, thereby obtaining a perovskite solar cell.

[0253] Example 2a A perovskite solar cell was obtained in the same manner as in Example 1a, except that the material for forming the hole transport layer was changed from SAM-1 to an equimolar mixture of SAM-1 and SAM-2.

[0254] Examples 4a to 7a Perovskite solar cells were obtained in the same manner as in Example 1a, except that the material for forming the hole transport layer was changed to a 1:1 (mol / mol) mixture of SAM-1 and SAM-3 in Example 4a, a 1:1 (mol / mol) mixture of SAM-1 and MeO-2PACz in Example 5a, SAM-4 in Example 6a, and SAM-5 in Example 7a.

[0255] Comparative Examples 1a to 4a Perovskite solar cells were obtained in the same manner as in Example 1a, except that the material for forming the hole transport layer was changed from SAM-1 to the material listed in Table 1. The materials listed in Table 1 are as follows: 2PACz: N-(2-phosphonoethyl)carbazole Me-2PACz: N-(2-phosphonoethyl)-3,6-dimethylcarbazole MeO-2PACz: N-(2-phosphonoethyl)-3,6-dimethoxycarbazole

[0256] The IV characteristics of the obtained perovskite solar cells of Examples 1a, 2a, 4a to 7a, and Comparative Examples 1a to 4a were measured, and the results are shown in Table 1 below.

[0257]

[0258] Table 1 shows that the perovskite solar cells of Examples 1a, 2a, and 4a to 7a, which contain the triarylamine compound represented by the above formula (1) in the hole transport layer, have superior photoelectric conversion efficiency to the perovskite solar cells of Comparative Examples 1 to 4, which do not contain the triarylamine compound represented by the above formula (1) or (1-1) in the hole transport layer.

[0259] Example 3a: PbI was used as a perovskite precursor. ２ A mixture of a 1:0.92:0.08 molar ratio of (metal halide), FAI, and CsI was dissolved in a 1:6 volume ratio mixed solvent of NMP and DMF to a perovskite composition concentration of 1.2 M to prepare a third preparation liquid. SAM-1 and SAM-2 were dissolved in a molar ratio of about 1:1 as hole transport layer-forming compounds at about 0.1 mg / mL, and 1H,1H-undecafluorohexylamine hydroiodide was dissolved as a passivation material at 0.25 mmol / L to prepare a perovskite precursor solution. The perovskite precursor solution was spin-coated, reduced to a vacuum, and then heated at 130°C for 20 minutes to obtain a perovskite film. The obtained perovskite film was coated with C in the same manner as in Example 1. ６０ , SnO ２ Then, silver was layered on top of the film to obtain a perovskite solar cell.

[0260] Examples 8a and 9a Perovskite solar cells were obtained in the same manner as in Example 3, except that the material for forming the hole transport layer was changed to a 1:1 (mol / mol) mixture of SAM-1 and SAM-3 in Example 8, and to a 1:1 (mol / mol) mixture of SAM-1 and MeO-2PACz in Example 9.

[0261] Comparative Example 5a A perovskite solar cell was obtained in the same manner as in Example 3a, except that SAM-1 was changed to SAM-2 (4-(N,N-diphenylamino)phenylphosphonic acid).

[0262] The results of measuring the IV characteristics of the obtained perovskite solar cells of Examples 3a, 8a, 9a, and Comparative Example 5a are shown in Table 2 below.

[0263]

[0264] Table 2 shows that the perovskite solar cells of Examples 3a, 8a, and 9a, in which the hole transport layer contains the triarylamine compound represented by the formula (1) or (1-1), have superior photoelectric conversion efficiency to the perovskite solar cell of Comparative Example 5a, in which the hole transport layer does not contain the triarylamine compound represented by the formula (1) or (1-1).

[0265] Next, to further evaluate the hole transport materials that are considered suitable for the present invention, quantum chemical calculations based on density functional theory were performed. The exchange-correlation functional used was B3LYP, and the basis functions used were 6-311G(d) for optimizing the molecular structure and 6-311++G(d,p) for calculating the energy. The results are shown in Tables 3 and 4.

[0266]

[0267]

[0268] An excellent hole transport material must be selected by comprehensively taking into consideration various characteristics. Among these, the HOMO, LUMO, and rearrangement energy are particularly important because they are characteristic values ​​related to hole transport. Other characteristics that should be taken into consideration include the ease of coating the electrode with the hole transport material, wettability with the precursor liquid for forming the power generation layer, and surface energy. The HOMO of the hole transport material is preferably close to the energy level of the valence band of the perovskite polycrystal used in the power generation layer, and more preferably slightly higher and closer to that level. Generally, hole transport materials used in solar cell applications have a HOMO of preferably higher than -5.50 eV, more preferably higher than -5.40 eV, and even more preferably higher than -5.30 eV. The LUMO of the hole transport material is preferably higher than -1.35 eV, more preferably higher than -1.25 eV, and even more preferably higher than -1.20 eV, from the viewpoint of suppressing the inflow of charge-separated electrons. The rearrangement energy of the hole transport material is preferably lower than 0.45 eV, more preferably higher than 0.35 eV, and even more preferably higher than 0.25 eV, from the viewpoint of the speed at which charge-separated holes are received from the power generation layer and transferred to the electrode. It is preferable that these characteristic values ​​satisfy all of the conditions simultaneously, but it is not necessary to satisfy all of them simultaneously.

[0269] The second embodiment of the present invention will be specifically described below based on examples, but the present invention is not limited to the following examples.

[0270] Example 1b: Synthesis of SAM-1' A mixture of diphenylamine (1.05 g) and DMF (5 mL) was added to a dispersion of sodium hydride (0.262 g) in 10 mL of N,N-dimethylformamide (hereinafter abbreviated as DMF) stirred at room temperature under a nitrogen atmosphere. The resulting mixture was stirred at room temperature for 1 hour. Next, the above-mentioned mixture containing sodium hydride and diphenylamine was slowly added dropwise to a mixture of diethyl (3-bromopropyl)phosphonate (1.55 g) and DMF (3 mL) stirred at room temperature. The resulting reaction mixture was stirred at 100°C overnight. Thereafter, the reaction mixture was filtered using a backlight, and volatiles were distilled off from the obtained filtrate under reduced pressure. The obtained crude product was purified by silica gel chromatography to obtain a light brown solid of N,N-diphenyl-3-aminopropylphosphonic acid diethyl ester as intermediate A-1'. １ H-NMR was as follows: １ H-NMR (400MHz, CDCl ３ ): δ = 7.28 (m, 4H), 7.04-6.92 (m, 6H), 4.18-4.00 (m, 4H), 3.80 (t, 2H), 2.06-1.90 (m, 2H), 1.88-1.71 (m, 2H), 1.30 (t, 6H)

[0271] Next, the obtained intermediate A-1' (0.117 g) was dissolved in 1 mL of 1,4-dioxane. To the solution of the intermediate stirred at room temperature, 0.44 mL of trimethylsilyl bromide was added, and the mixture was stirred at room temperature for 20 hours. Then, the volatile matter was distilled off under reduced pressure. The obtained crude product was mixed with 0.5 mL of methanol and 0.5 mL of pure water, and the mixture was stirred at room temperature for 1 hour. Then, the precipitate was filtered and washed three times with 5 mL of diethyl ether. The volatile matter was distilled off under vacuum at 65°C to obtain SAM-1' as a pale green solid. The obtained compound SAM-1' １ H-NMR was as follows: １ H-NMR (400MHz, DMSO-d ６): δ = 7.27 (m, 4H), 7.04-6.87 (m, 6H), 3.74 (t, 2H), 1.85-1.65 (m, 2H), 1.65-1.47 (m, 2H). The HOMO of SAM-1' obtained from the above-mentioned DFT calculation was -5.46 eV, and the LUMO was -0.75 eV.

[0272] Example 2b: Synthesis of SAM-2' A pale green solid, SAM-2' (N,N-di(naphthalen-2-yl)-3-aminopropylphosphonic acid), was obtained in the same manner as in Example 1b, except that diphenylamine (0.356 g) was replaced with 2,2'-dinaphthylamine (1.49 g). １ H-NMR was as follows: １ H-NMR (400MHz, DMSO-d ６ ): δ = 7.81 (d, 4H), 7.76 (d, 2H), 7.51 (d, 2H), 7.44 (td, 2H), 7.35 (td, 2H), 7.26 (dd, 2H), 4.01 (t, 2H), 1.99-1.80 (m, 2H), 1.74-1.58 (m, 2H). Furthermore, the HOMO of SAM-2' obtained from the above-mentioned DFT calculation was -5.38 eV, and the LUMO was -1.58 eV.

[0273] Example 6b: Synthesis of SAM-4' SAM-4' was obtained in the same manner as in Example 1b, except that 2,2'-dinaphthylamine was replaced with 4,4'-dimethyldiphenylamine. １ H-NMR was as follows: １ H-NMR (400MHz, DMSO-d ６ ): δ = 7.05 (d, 4H), 6.83 (d, 4H), 3.65 (t, 2H), 2.23 (s, 6H), 1.71 (m, 2H), 1.52 (m, 2H)

[0274] Next, the performance of the cells was evaluated using SAM-1', SAM-2', and SAM-4'.

[0275] Example 3b: First, a NiOx film was formed on the FTO layer of a commercially available glass / FTO substrate. The glass / FTO substrate was a substrate in which FTO constituting the first electrode layer was 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 1.0 mg / mL was spin-coated onto the NiOx layer. SAM-1' obtained in Example 1b was used as the material for forming the hole transport layer. The coating film formed by spin-coating was dried at 100°C for 10 minutes to form a hole transport layer. A solution of 4-fluorophenylethylamine hydroiodide dissolved in DMF at a concentration of 80 mM was spin-coated onto the hole transport layer. The coating film formed by spin-coating was dried at 100°C for 5 minutes to attach a passivation material onto the hole transport layer. A perovskite precursor solution, in which the perovskite precursor was dissolved in a mixed solvent of DMSO and DMF at a volume ratio of 1:4 to a total solid concentration of 3.2 M, was spin-coated onto the hole transport layer to which the passivation material had been attached. ２ A mixture of (metal halide) and FAI and MABr (halogenated organic compound) in a molar ratio of 1:0.83:0.17 was used. A poor solvent was added dropwise to a spin-coated coating film, which was then heated at 120°C for 30 minutes to form a photoelectric conversion layer. A solution of 1H,1H-undecafluorohexylamine hydroiodide dissolved in 2-propanol at a concentration of 0.2 mmol / L was spin-coated onto the photoelectric conversion layer. The spin-coated coating film was dried at 100°C for 10 minutes to deposit a passivation material onto the photoelectric conversion layer. Further, fullerene was vapor-deposited to a thickness of 20 nm as an electron transport layer, followed by the formation of a 20 nm-thick SnO2 thin film as a buffer layer by atomic deposition. Copper was then vapor-deposited to a thickness of 100 nm, and a second electrode layer was then laminated on the electron transport layer with the passivation material, thereby obtaining a perovskite solar cell.

[0276] Example 4b A perovskite solar cell was obtained in the same manner as in Example 3b, except that the material for forming the hole transport layer was changed from SAM-1′ to SAM-2′ obtained in Example 2b.

[0277] Examples 7b to 10b Perovskite solar cells were obtained in the same manner as in Example 3b, except that the material for forming the hole transport layer was changed to a 1:1 (mol / mol) mixture of SAM-1′ and SAM-2′ in Example 7b, a 1:1 (mol / mol) mixture of SAM-1′ and MeO-2PACz in Example 8b, a 1:1 (mol / mol) mixture of SAM-2′ and MeO-2PACz in Example 9b, and SAM-4′ in Example 10b.

[0278] Comparative Examples 1b to 4b Perovskite solar cells were obtained in the same manner as in Example 3b, except that the material for forming the hole transport layer was changed from SAM-1' to the material listed in Table 5. The materials listed in Table 5 are as follows: SAM-3': N-phenyl-3-aminopropylphosphonic acid 2PACz: N-(2-phosphonoethyl)carbazole Me-2PACz: N-(2-phosphonoethyl)-3,6-dimethylcarbazole MeO-2PACz: N-(2-phosphonoethyl)-3,6-dimethoxycarbazole

[0279] The results of measuring the IV characteristics of the obtained perovskite solar cells of Example 3b, Example 4b, and Comparative Examples 1b to 4b are shown in Table 5 below.

[0280]

[0281] Table 5 shows that the perovskite solar cells of Examples 3b, 4b, and 7b to 10b, which contain the diarylamine compound represented by formula (1') in the hole transport layer, have superior photoelectric conversion efficiency to the perovskite solar cells of Comparative Examples 1b to 4b, which do not contain the diarylamine compound represented by formula (1') in the hole transport layer.

[0282] Example 5b: PbI was used as a perovskite precursor. ２A mixture of (metal halide), FAI, and CsI in a molar ratio of 1:0.92:0.08 was dissolved in a mixed solvent of NMP and DMF in a volume ratio of 1:6 to give a perovskite composition concentration of 1.2 M. A third preparation liquid was prepared by dissolving SAM-1' as a hole transport layer-forming compound at approximately 0.1 mg / ml and 1H,1H-undecafluorohexylamine hydroiodide as a passivation material at 0.25 mmol / L, respectively, to prepare a perovskite precursor solution. The perovskite precursor solution was spin-coated, reduced to a vacuum, and then heated at 130°C for 20 minutes to obtain a perovskite film. The obtained perovskite film was coated with C in the same manner as in Example 2. ６０ , SnO ２ Then, copper was layered on top of the metal to obtain a perovskite solar cell.

[0283] Examples 11b and 12b Perovskite solar cells were obtained in the same manner as in Example 5b, except that the hole-transport layer-forming compound was changed to a 1:1 (mol / mol) mixture of SAM-1′ and SAM-2′ in Example 11b, and to a 1:1 (mol / mol) mixture of SAM-1′ and MeO-2PACz in Example 12b.

[0284] Comparative Example 5b A perovskite solar cell was obtained in the same manner as in Example 5b, except that SAM-1' was changed to SAM-4' (4-(N,N-diphenylamino)phenylphosphonic acid).

[0285] The results of measuring the IV characteristics of the obtained perovskite solar cells of Examples 5b, 11b, 12b, and Comparative Example 5b are shown in Table 6 below.

[0286]

[0287] Table 6 shows that the perovskite solar cells of Examples 5b, 11b, and 12b, in which the hole transport layer contains the diarylamine compound represented by formula (1'), have superior photoelectric conversion efficiency to the perovskite solar cell of Comparative Example 5, in which the hole transport layer does not contain the diarylamine compound represented by formula (1').

[0288] Next, to further evaluate the hole transport materials considered suitable for the present invention, quantum chemical calculations based on density functional theory were performed. The exchange-correlation functional used was B3LYP, and the basis functions used were 6-311G(d) for optimizing the molecular structure and 6-311++G(d,p) for calculating the energy. The results are shown in Tables 7 and 8.

[0289]

[0290]

[0291] An excellent hole transport material must be selected by comprehensively taking into consideration various characteristics. Among these, the HOMO, LUMO, and rearrangement energy are particularly important because they are characteristic values ​​related to hole transport. Other characteristics that should be taken into consideration include the ease of coating the electrode with the hole transport material, wettability with the precursor liquid for forming the power generation layer, and surface energy. The HOMO of the hole transport material is preferably close to the energy level of the valence band of the perovskite polycrystal used in the power generation layer, and more preferably slightly higher and closer to that level. Generally, hole transport materials used in solar cell applications have a HOMO of preferably higher than -5.50 eV, more preferably higher than -5.40 eV, and even more preferably higher than -5.30 eV. The LUMO of the hole transport material is preferably higher than -1.35 eV, more preferably higher than -1.25 eV, and even more preferably higher than -1.20 eV, from the viewpoint of suppressing the inflow of charge-separated electrons. The rearrangement energy of the hole transport material is preferably lower than 0.45 eV, more preferably higher than 0.35 eV, and even more preferably higher than 0.25 eV, from the viewpoint of the speed at which charge-separated holes are received from the power generation layer and transferred to the electrode. It is preferable that these characteristic values ​​satisfy all of the conditions simultaneously, but it is not necessary to satisfy all of them simultaneously.

[0292] 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 device comprising a first electrode layer, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode layer in this order, wherein the hole transport layer is represented by the following formula (1): (HO) ２ P(=O)-Ar １ -N(Ar ２ ) ２ (1) (In formula (1), Ar １ is a divalent aromatic hydrocarbon group which may have a substituent, and Ar ２ is a phenyl group, a phenyl group substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms, or an aromatic hydrocarbon group having from 10 to 20 carbon atoms which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms), or a group represented by the following formula (1-1): (HO) ２ P(=O)-R １０ -Ar １ -N(Ar ２０ ) ２ (1-1) (In formula (1-1), R １０ represents a chain aliphatic group which may have a substituent and which may contain a heteroatom, and Ar １ is a divalent aromatic hydrocarbon group which may have a substituent, and Ar ２０ is a phenyl group, a halogen atom, an alkyl group having 1 to 6 carbon atoms, (HO) ２ P(=O)-(CH ２ ) ｎ - (where n is an integer of 1 to 6), and / or an alkoxy group having from 1 to 6 carbon atoms, or an aromatic hydrocarbon group having from 10 to 20 carbon atoms in which a plurality of aromatic rings are linked or condensed, and which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms.

2. The Ar １ The perovskite solar cell according to claim 1 , wherein is a phenylene group.

3. The self-assembled monolayer is reacted with the triarylamine compound to form a compound represented by the following formula (2): (HO) ２ P(=O)-Ar １ -N(Ar ３ ) ２ (2) (In formula (2), Ar １ is a divalent aromatic hydrocarbon group which may have a substituent, and Ar ３ The perovskite solar cell according to claim 1 or 2, comprising a second triarylamine compound represented by the following formula:

4. The following formula (1): (HO) ２ P(=O)-Ar １ -N(Ar ２ ) ２ (1) (In formula (1), Ar １ is a divalent aromatic hydrocarbon group which may have a substituent, and Ar ２ is a phenyl group, a phenyl group substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms, or an aromatic hydrocarbon group having from 10 to 20 carbon atoms which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms), or a group represented by the following formula (1-1): (HO) ２ P(=O)-R １０ -Ar １ -N(Ar ２０ ) ２ (1-1) (In formula (1-1), R １０ represents a chain aliphatic group which may have a substituent and which may contain a heteroatom, and Ar １ is a divalent aromatic hydrocarbon group which may have a substituent, and Ar ２０ is a phenyl group, a halogen atom, an alkyl group having 1 to 6 carbon atoms, (HO) ２ P(=O)-(CH ２ ) ｎ - (where n is an integer of 1 to 6), and / or an alkoxy group having from 1 to 6 carbon atoms, or an aromatic hydrocarbon group having from 10 to 20 carbon atoms in which a plurality of aromatic rings are linked or condensed, and which may be substituted with an alkyl group having from 1 to 6 carbon atoms and / or an alkoxy group having from 1 to 6 carbon atoms.

5. A liquid composition for forming a hole transport layer in forming a perovskite solar cell, comprising: ２ P(=O)-Ar １ -N(Ar ２ ) ２ (1) (In formula (1), Ar １ is a phenyl group or a divalent aromatic hydrocarbon group which may have a substituent, and Ar ２ is a phenyl group substituted with an alkyl group having 1 to 6 carbon atoms and / or an alkoxy group having 1 to 6 carbon atoms, or an aromatic hydrocarbon group having 10 to 20 carbon atoms which may be substituted with an alkyl group having 1 to 6 carbon atoms and / or an alkoxy group having 1 to 6 carbon atoms, or a group represented by the following formula (1-1): (HO) ２ P(=O)-R １０ -Ar １ -N(Ar ２０ ) ２ (1-1) (In formula (1-1), R １０ represents a chain aliphatic group which may have a substituent and which may contain a heteroatom, and Ar １ is a divalent aromatic hydrocarbon group which may have a substituent, and Ar ２０ is a phenyl group, a halogen atom, an alkyl group having 1 to 6 carbon atoms, (HO) ２ P(=O)-(CH ２ ) ｎ - (where n is an integer of 1 to 6), and / or an alkoxy group having 1 to 6 carbon atoms, or an aromatic hydrocarbon group having 10 to 20 carbon atoms in which a plurality of aromatic rings are linked or condensed, and which may be substituted with an alkyl group having 1 to 6 carbon atoms and / or an alkoxy group having 1 to 6 carbon atoms.

6. The liquid composition of claim 5, further comprising a perovskite precursor and / or a passivation material.

7. A method for manufacturing a perovskite solar cell, comprising: applying the liquid composition according to claim 5 to a first electrode layer formed on one main surface of a plate-like or sheet-like substrate to form a hole transport layer; forming a photoelectric conversion layer containing a perovskite compound on the hole transport layer; forming an electron transport layer on the photoelectric conversion layer; and forming a second electrode layer on the electron transport layer.

8. A method for producing a perovskite solar cell according to claim 7, wherein the liquid composition comprises a perovskite precursor and a passivation material, and the hole transport layer and the photoelectric conversion layer are formed in this order by applying the liquid composition onto the first electrode layer, and the passivation material is present on the surface and / or inside of the photoelectric conversion layer.

9. A device comprising a first electrode layer, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode layer in this order, wherein the hole transport layer is represented by the following formula (1'): (HO) ２ P(=O)-R １ -N(Ar １ ) ２ (1') (In formula (1'), R １ represents a chain aliphatic group which may have a substituent and which may contain a heteroatom, and Ar １ is an aromatic hydrocarbon group having from 6 to 20 carbon atoms which may be substituted with a halogen atom, an alkyl group having from 1 to 6 carbon atoms, and / or an alkoxy group having from 1 to 6 carbon atoms.

10. The Ar １ The perovskite solar cell according to claim 9 , wherein is a phenyl group or a naphthyl group.

11. The following formula (1'): (HO) ２ P(=O)-R １ -N(Ar １ ) ２ (1') (In formula (1'), R １ represents a chain aliphatic group which may have a substituent and which may contain a heteroatom, and Ar １ is an aromatic hydrocarbon group having 6 to 20 carbon atoms which may be substituted with a halogen atom, an alkyl group having 1 to 6 carbon atoms, and / or an alkoxy group having 1 to 6 carbon atoms.

12. A liquid composition for forming a hole transport layer in forming a perovskite solar cell, comprising: a compound represented by the following formula (1'): (HO) ２ P(=O)-R １ -N(Ar １ ) ２ (1') (In formula (1'), R １ represents a chain aliphatic group which may have a substituent and which may contain a heteroatom, and Ar １ is an aromatic hydrocarbon group having from 6 to 20 carbon atoms which may be substituted with a halogen atom, an alkyl group having from 1 to 6 carbon atoms, and / or an alkoxy group having from 1 to 6 carbon atoms.

13. The liquid composition of claim 12, further comprising a perovskite precursor and / or a passivation material.

14. A method for manufacturing a perovskite solar cell, comprising: applying the liquid composition according to claim 13 onto a first electrode layer formed on one main surface of a plate-like or sheet-like substrate to form a hole transport layer; forming a photoelectric conversion layer containing a perovskite compound on the hole transport layer; forming an electron transport layer on the photoelectric conversion layer; and forming a second electrode layer on the electron transport layer.

15. A method for producing a perovskite solar cell as described in claim 14, wherein the liquid composition contains a perovskite precursor and a passivation material, and the hole transport layer and the photoelectric conversion layer are formed in this order by applying the liquid composition onto the first electrode layer, and the passivation material is present on the surface and / or inside of the photoelectric conversion layer.

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