JP2024095333A - Photoelectric conversion element and its manufacturing method - Google Patents

Abstract

The present invention provides a photoelectric conversion element that exhibits excellent photoelectric conversion characteristics and has little deviation in the characteristics.
[Solution] A photoelectric conversion element 10 includes a first electrode 12, a hole transport layer 13, a photoelectric conversion layer 14 containing a perovskite compound, an electron transport layer 15, and a second electrode. The hole transport layer 13 contains a compound represented by chemical formula (I), and in at least a part of Ar ¹ of the compound represented by chemical formula (I), a salt is formed between a nitrogen atom constituting an aromatic ring and an anion.
Ar ¹ -(L ¹ -X ¹ )n. ． ． (I)
In chemical formula (I), Ar ¹ is a structure containing an aromatic ring, and may contain a heteroatom among the atoms constituting the aromatic ring, and Ar ¹ may have a substituent other than -L ¹ -X ^1. n is an integer of 1 or more, and when n is 2 or more, the structures represented by -L ¹ -X ¹ may be the same or different from each other. L ¹ is a divalent linking group that bonds Ar ¹ and X ¹ , or a single bond.
[Selected Figure] Figure 1

Description

The present invention relates to a photoelectric conversion element.

In recent years, solar power generation has been attracting attention as a clean energy source, and the development of solar cells is progressing. One such type of solar cell is one that uses a perovskite material in the light absorption layer, and is rapidly gaining attention as a next-generation solar cell that can be manufactured at low cost. For example, Non-Patent Document 1 reports a solution-type solar cell that uses a perovskite material in the light absorption layer. In addition, Non-Patent Document 2 reports that solid-state perovskite-type solar cells exhibit high efficiency.

Known basic structures of perovskite solar cells include a forward structure in which an electron transport layer, a light absorption layer (perovskite layer), a hole transport layer (also called a hole transport layer), and a back electrode are stacked in that order on an electrode, and an inverted structure in which a hole transport layer, a light absorption layer, an electron transport layer, and a back electrode are stacked in that order on an electrode. An electron transport layer made of a porous shape may be provided between the electron transport layer and the perovskite layer. Of these, an organic semiconductor hole transport material is generally used for the hole transport layer (for example, Non-Patent Documents 3 to 10).

Journal of the American Chemical Society, 2009, 131, 6050-6051. Science, 2012, 388, 643-647. ACS Appl. Mater. Interfaces, 2017, 9, 24778-24787. Energy Environ. Sci. , 2014, 7, 1454-1460. J. Mater. Chem. A, 2014, 2, 6305-6309. J. Mater. Chem. A, 2015, 3, 12139-12144. J. Mater. Chem. A, 2018, 6, 7950-7958. ACS Appl. Mater. Interfaces, 2015, 7, 11107-11116. Energy & Environmental Science 2014, 7, 2963-2967. Adv. Energy Matter. , 2018, 8, 1801892.

However, the photoelectric conversion efficiency of conventional perovskite solar cells is not sufficient. In order to improve the photoelectric conversion efficiency of solar cells, it is particularly important to improve the characteristics of the hole transport layer. For example, trachene compounds (Non-Patent Document 3), diketopyrrolopyrrole compounds (Non-Patent Document 4), thiophene compounds (Non-Patent Documents 5 and 6), dithienopyrrole (Non-Patent Document 7), etc. have been reported as hole transport materials used in the hole transport layer. However, there have been almost no reports of compounds that can exhibit a photoelectric conversion efficiency that can be said to be useful as a perovskite solar cell. Therefore, Spiro-OMeTAD ([2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamino)-9,9'-spirobifluorene]), which was developed as a hole transport material for dye-sensitized solar cells, has been proposed, but it is known to have low heat resistance (Non-Patent Document 8). In addition, a polymer material having a triphenylamine skeleton, called PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]), is also known to have low light resistance. Furthermore, when these materials are used as hole transport materials for the p-buffer layer, it is necessary to add LiTFSI salt (lithium bis(trifluoromethanesulfonyl)imide) as an additive to improve the conductivity, which is thought to be one of the causes of deterioration of the element (Non-Patent Document 9). In addition, a carbazole-type hole transport material having phosphonic acid has been reported in recent years (Non-Patent Document 10). This compound reacts with an indium tin compound (ITO) used as a transparent electrode to form a monolayer on the transparent electrode. This hole transport compound that forms a monolayer is a very excellent compound, with a photoelectric conversion efficiency of more than 20% reported, but the surface of the hole transport layer becomes hydrophobic, which causes the perovskite solution to be repelled when a perovskite layer is formed on this hole transport layer. If repelling occurs even partially within the surface of the hole transport layer, it will cause bias in the photoelectric conversion characteristics, which will become a major problem when enlarging the device.

The present invention aims to provide a photoelectric conversion element that exhibits excellent photoelectric conversion characteristics and has little bias in the characteristics.

One aspect of the present invention is a photoelectric conversion element. The photoelectric conversion element includes:
a first electrode, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode are laminated in this order;
the photoelectric conversion layer contains a perovskite compound,
The hole transport layer contains a compound represented by the following chemical formula (I), and in at least a part of Ar ¹ in the compound represented by the following chemical formula (I), a salt is formed between a nitrogen atom constituting the aromatic ring and an anion.
Ar ¹ -(L ¹ -X ¹ )n. ． ． (I)
In the chemical formula (I), Ar ¹ is a structure containing an aromatic ring, and may contain a heteroatom among the atoms constituting the aromatic ring, and Ar ¹ may have a substituent other than -L ¹ -X ^1. n is an integer of 1 or more, and when n is 2 or more, the structures represented by -L ¹ -X ¹ may be the same or different from each other. L ¹ is a divalent linking group that bonds Ar ¹ and X ¹ , or a single bond. X ¹ is a group that can form a chemical bond or a hydrogen bond with the first electrode.
Another aspect of the present invention is a photoelectric conversion element. The photoelectric conversion element includes:
a first electrode, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode are laminated in this order;
the photoelectric conversion layer contains a perovskite compound,
The hole transport layer contains a compound represented by the following chemical formula (I) and a compound represented by the following chemical formula (II), and satisfies at least one of the following conditions (a) and (b):
Ar ¹ -(L ¹ -X ¹ )n. ． ． (I)
In the chemical formula (I), Ar ¹ is a structure containing an aromatic ring, and the atoms constituting the aromatic ring contain a nitrogen atom, and Ar ¹ may have a substituent other than -L ¹ -X ^1. n is an integer of 1 or more, and when n is 2 or more, the structures represented by -L ¹ -X ¹ may be the same or different from each other. L ¹ is a divalent linking group that bonds Ar ¹ and X ¹ , or a single bond. X ¹ is a group that can form a chemical bond or a hydrogen bond with the first electrode.
A ¹ -L ² -X ² . ． ． (II)
A ¹ is an atomic group containing one or more substituents or structures selected from the group consisting of an alkoxy group, a hydroxy group, a carboxy group, a dihydroxyphosphoryl group, a dialkylphosphoryl group, a hydroxysulfonyl group, an amino group, a monoalkylamino group, a dialkylamino group, a monoarylamino group, a diarylamino group, a monoalkylaminocarbonyl group, a dialkylaminocarbonyl group, an alkylcarbonyloxy group, an alkoxycarbonyl group, an aminocarbonyl group, an aminocarbonylamino group, an alkylcarbonylamino group, an alkylsulfonylamino group, an aminosulfonyl group, and a nitrogen-containing heterocyclic group. L ² is a divalent linking group or a single bond that bonds A ¹ and X ^2. X ² is a group capable of chemically bonding or hydrogen bonding with the first electrode.
Condition (a): Ar ¹ in the compound represented by chemical formula (I) contains a nitrogen atom among atoms constituting the aromatic ring, and in at least a part of Ar ¹ in the compound represented by chemical formula (I), the nitrogen atom constituting the aromatic ring and an anion form a salt.
Condition (b): A ¹ in the compound represented by chemical formula (II) contains a nitrogen atom, and at least a part of A ¹ in the compound represented by chemical formula (II) forms a salt from the nitrogen atom and an anion.
In the photoelectric conversion element of the above embodiment, the molar ratio of the compound represented by chemical formula (II) to the compound represented by chemical formula (I) may be 1:100 to 1:1.
Furthermore, each X ¹ in the chemical formula (I) may be independently selected from the group consisting of a dihydroxyphosphoryl group (-P=O(OH) ₂ ), a carboxy group (-COOH), a sulfo group (-SO ₃ H), a boronic acid group (-B(OH) ₂ ), a trihalogenated silyl group (-SiX ₃ , where X is a halo group), and a trialkoxysilyl group (-Si(OR) ₃ , where R is an alkyl group).
^X2 in the chemical formula (II) may be selected from the group consisting of a dihydroxyphosphoryl group (-P=O(OH) ₂ ), a carboxy group (-COOH), a sulfo group ( _-SO3H ), a boronic acid group (-B(OH) ₂ ), a trihalogenated silyl group ( _-SiX3 , where X is a halo group), a trialkoxysilyl group (-Si(OR) ₃ , where R is an alkyl group), a trihydroxysilyl group, and a dialkylphosphoryl group.
The perovskite compound may be an organic-inorganic perovskite compound.
The perovskite compound may contain at least one of tin and lead.
The organic-inorganic perovskite compound may contain at least one of tin and lead.

According to the present invention, it is possible to provide a photoelectric conversion element in which the hole transport layer exhibits excellent photoelectric conversion characteristics, and in which a uniform perovskite layer is formed, resulting in little deviation in characteristics even when the size increases.

FIG. 1 is a cross-sectional view showing an example of the configuration of a photoelectric conversion element according to an embodiment.

The present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following description. In the following, the case where the photoelectric conversion element according to the embodiment is a solar cell will be described.

[Photoelectric conversion element]
Fig. 1 is a cross-sectional view showing an example of the configuration of a photoelectric conversion element 10 according to an embodiment. For convenience of explanation, Fig. 1 is drawn in a schematic manner with appropriate omissions, exaggeration, etc. As shown in Fig. 1, the photoelectric conversion element 10 has a laminated structure in which a first electrode 12, a hole transport layer 13, a photoelectric conversion layer 14, an electron transport layer 15, and a second electrode 16 are laminated in this order on a support (also called a substrate, base material, etc.) 11.
Each component of the photoelectric conversion element 10 will be described in detail below.

[Support]
The support 11 is not particularly limited, and may be, for example, a substrate that can be used for a photoelectric conversion element such as a general solar cell. Examples of the substrate include glass, a plastic plate, a plastic film, and an inorganic crystal. In addition, a substrate having at least one film of a metal film, a semiconductor film, a conductive film, and an insulating film formed on a part or all of the surface of the substrate can also be suitably used as the support 11. The size, thickness, etc. of the support 11 are also not particularly limited, and may be the same as or equivalent to a photoelectric conversion element such as a general solar cell.

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

The first electrode 12 may be formed directly on the support 11, for example. The first electrode 12 may be a transparent electrode formed from a conductor, for example. The transparent electrode is not particularly limited, but may be, for example, a tin-doped indium oxide (ITO) film, an impurity-doped indium oxide (In2O3) film, an impurity-doped zinc oxide (ZnO) film, a fluorine-doped tin dioxide (FTO) film, a laminate film formed by laminating two or more of these, gold, silver, copper, aluminum, tungsten, titanium, chromium, nickel, and cobalt. These may be used alone or in a mixture of two or more types, and may be a single layer or a laminate. These films may also function as, for example, a diffusion prevention layer. The thickness of the first electrode 12 is not particularly limited, but it is preferable to adjust the sheet resistance to, for example, 5 to 15 Ω/□ (per unit area). The method of forming the first electrode 12 is not particularly limited, but it can be obtained by a known film formation method depending on the material to be formed. The shape of the first electrode 12 is not particularly limited, but may be, for example, a film or a lattice such as a mesh. The method of forming the first electrode 12 on the support 11 is not particularly limited, but may be, for example, a known method, and vacuum film formation such as vacuum deposition or sputtering is preferable. The first electrode 12 may be patterned. The patterning method is not limited to, but may be, for example, a method of immersing in a laser or etching solution, or a method of patterning using a mask during vacuum film formation, and any method may be used in the present invention. The first electrode 12 may also be used in combination with metal wiring or the like for the purpose of reducing the electrical resistance value. The material of the metal wiring (metal lead wire) is not particularly limited, but may be, for example, aluminum, copper, silver, gold, platinum, nickel, etc. The metal lead wire can be used in combination by forming, for example, a first substrate by deposition, sputtering, pressure bonding, etc., and providing an ITO or FTO layer thereon, or by providing it on ITO or FTO.

[Hole transport layer]
(First embodiment of the hole transport layer)
In a first embodiment of the hole transport layer 13, the hole transport layer 13 contains a compound represented by the following chemical formula (I), and in at least a part of Ar ¹ of the compound represented by the following chemical formula (I), a salt is formed between a nitrogen atom constituting the aromatic ring and an anion. In a more preferred embodiment, in the hole transport layer 13, the compound represented by the following chemical formula (I) is chemically bonded or hydrogen bonded to the first electrode 12.
In addition, in at least a part of Ar ¹ in which a salt is formed, when there are multiple nitrogen atoms constituting an aromatic ring, all of the nitrogen atoms may form salts with anions, or only a part of them may form salts with anions.
Ar ¹ -(L ¹ -X ¹ )n. ． ． (I)
When the hole transport layer is the first embodiment, in the chemical formula (I), Ar ¹ is a structure containing an aromatic ring, and the atoms constituting the aromatic ring contain a nitrogen atom, and Ar ¹ may have a substituent other than -L ¹ -X ^1. n is an integer of 1 or more, and when n is 2 or more, the structures represented by -L ¹ -X ¹ may be the same or different from each other. L ¹ is a divalent linking group that bonds Ar ¹ and X ¹ , or a single bond. X ¹ is a group that can form a chemical bond or a hydrogen bond with the first electrode.

(Compound represented by chemical formula (I))
In chemical formula (I), each ^X1 is independently selected from the group consisting of a dihydroxyphosphoryl group (-P=O(OH) ₂ ), a carboxyl group (-COOH), a sulfo group ( _-SO3H ), a boronic acid group (-B(OH) ₂ ), a trihalogenated silyl group ( _-SiX3 , where X is a halo group), a trialkoxysilyl group (-Si(OR) ₃ , where R is an alkyl group), a trihydroxysilyl group, and a dialkylphosphoryl group.

In the case where the hole transport layer is the first embodiment, in chemical formula (I), Ar ¹ is specifically, for example, any one of an aromatic ring group, a group in which a plurality of aromatic ring groups are bonded by single bonds, and a group in which one or more aromatic ring groups are condensed with a ring having no aromaticity, and at least one of the one or more aromatic ring groups contained in these groups contains a nitrogen atom (preferably 1 to 5 atoms).

In the aromatic ring group, the group in which a plurality of aromatic ring groups are bonded to each other by single bonds, and the group in which one or more aromatic ring groups are condensed to a ring having no aromaticity, each aromatic ring group may be independently a monocyclic or polycyclic (e.g., 2 to 14 rings) and may have one or more (e.g., 1 to 10) heteroatoms (such as nitrogen atoms, sulfur atoms, and/or oxygen atoms). The number of ring atoms in the aromatic ring group is preferably 5 to 40.
Examples of the aromatic ring group include a benzene ring group, a pyrrole ring group, a furan ring group, a thiophene ring group, and a group formed by condensing two or more (eg, 2 to 14) rings selected from these.
However, when Ar ¹ is an aromatic ring group itself, the aromatic ring group is an aromatic ring group having a nitrogen atom.
The aromatic ring group having a nitrogen atom may be a monocyclic ring or a polycyclic ring (e.g., 2 to 14 rings), has one or more (e.g., 1 to 10) nitrogen atoms, and may have one or more (e.g., 1 to 10) heteroatoms other than nitrogen atoms (such as sulfur atoms and/or oxygen atoms), and the number of ring atoms is preferably 5 to 40. When the aromatic ring group is a polycyclic ring, if a nitrogen atom is present as a ring member atom in at least one of the multiple rings, the polycyclic ring corresponds to an aromatic ring group having a nitrogen atom.

In the aromatic ring group constituting the group in which the above-mentioned multiple aromatic ring groups are bonded by single bonds, the number of aromatic ring groups bonded by single bonds is preferably, for example, 2 to 6. At least one of these aromatic ring groups (for example, 1 to 6) is the above-mentioned aromatic ring group having a nitrogen atom.

In the group in which one or more aromatic ring groups are condensed to a ring having no aromaticity, the number of aromatic ring groups condensed to the ring having no aromaticity is, for example, preferably 2 to 6. When the number of the condensed aromatic ring groups is 1, the aromatic ring group is the above-mentioned aromatic ring group having a nitrogen atom. When the number of the condensed aromatic ring groups is 2 or more, at least one of these aromatic ring groups (for example, 1 to 6) is the above-mentioned aromatic ring group having a nitrogen atom.
The group in which one or more aromatic ring groups are condensed with a ring having no aromaticity may have only one ring having no aromaticity or may have a plurality of rings having no aromaticity.
In the group in which one or more aromatic ring groups are condensed with a ring having no aromaticity, the ring having no aromaticity may be independently a monocyclic ring or a polycyclic ring (e.g., 2 to 14 rings) and may have one or more (e.g., 1 to 10) heteroatoms (such as a nitrogen atom, a sulfur atom, and/or an oxygen atom).
Specific examples of the group in which one or more aromatic ring groups are condensed with a ring having no aromaticity include a phenothiazine ring group and a 1,2:3,4:5,6:7,8-tetrakis[imino(1,2-phenylene)]cyclooctatetraene ring group.

When the hole transport layer is the first embodiment, in the chemical formula (I), the divalent linking group L ¹ may be, for example, *1-alkylene group-*2 or *1-alkylene group-aromatic ring group-*2. Here, *1 represents the bonding position on the Ar ¹ side, and *2 represents the bonding position on the X ¹ side. The alkylene group may be linear or branched, and preferably has 1 to 6 carbon atoms. Examples of the aromatic ring group include the same aromatic ring groups as those mentioned above as the aromatic ring group that Ar ¹ may be. The alkylene group and the aromatic ring group may further have a substituent.

When the hole transport layer is the first embodiment, in at least a part of Ar ¹ of the compound represented by the above chemical formula (I), when a salt is formed from a nitrogen atom constituting an aromatic ring and an anion, the salt may be an acid addition salt or a base addition salt. Furthermore, the acid forming the acid addition salt may be an inorganic acid or an organic acid, and the base forming the base addition salt may be an inorganic base or an organic base. The inorganic acid is not particularly limited, but examples thereof include sulfuric acid, phosphoric acid, hydrofluoric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, hypofluorous acid, hypochlorous acid, hypobromous acid, hypoiodous acid, fluorous acid, chlorous acid, bromous acid, iodous acid, fluorine acid, chlorine acid, bromine acid, iodic acid, perfluorine acid, perchloric acid, perbromine acid, and periodic acid. The organic acid is not particularly limited, and examples thereof include p-toluenesulfonic acid, methanesulfonic acid, oxalic acid, p-bromobenzenesulfonic acid, carbonic acid, succinic acid, citric acid, benzoic acid, and acetic acid. The inorganic base is not particularly limited, and examples thereof include ammonium hydroxide, alkali metal hydroxides, alkaline earth metal hydroxides, carbonates, and hydrogen carbonates, and more specifically, examples thereof include sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, calcium hydroxide, and calcium carbonate. The organic base is also not particularly limited, and examples thereof include ethanolamine, triethylamine, and tris(hydroxymethyl)aminomethane. The method for producing these salts is also not particularly limited, and for example, they can be produced by a method in which the above-mentioned acid or base is appropriately added to the compound represented by the above chemical formula (I) by a known method.

In the case where the hole transport layer is the first embodiment, examples of anions that form a salt with a nitrogen atom constituting an aromatic ring in at least a part of Ar ¹ of the compound represented by chemical formula (I) include OH ^- , O ₂ ^- , SO ₄ ^2- , PO ₄ ^3- , F ^- , Cl ^- , Br ^- , I ^- , CN ^- , FO ^- , ClO ^- , BrO ^- , IO ^- , ClO ₂ ^- , BrO ₂ ^- , IO ₂ ^- , ClO ₃ ^- , BrO ₃ ^- , IO ₃ ^- , ClO ₄ ^- , BrO ₄ ^- , IO ₄ ^- , H ₄ IO ₆ ^- , H ₃ IO ₆ ^2- , H ₂ IO ₆ ^3- , HCO ₃ ^- , CO ₃ ^2- , p-toluenesulfonate anion, methanesulfonate anion, oxalate anion, p-bromobenzenesulfonate anion, succinate anion, citrate anion, benzoate anion, and acetate anion.
The anion may also be an anion represented by RCOO ^- , RSO ₃ ^- , ROPO(OH)O ^- , RPO(OH)O ^- , ROSO ₃ ^- , or L(-COO ^- ) _n .
In the above, R each independently represents a hydrogen atom or an organic group, preferably having 1 to 14 carbon atoms.
In the above, n represents an integer of 2 or more, and preferably 2 to 6.
In the above, L represents an n-valent linking group, which may be a single bond when n is 2. The n-valent linking group preferably has 1 to 10 carbon atoms.
The valence of the anion is not limited and may be, for example, 1 to 6.

The compound represented by formula (I) and its salt may be formed, for example, as a monolayer on the first electrode 12 .
When the hole transport layer is the first aspect, the content of the compound represented by chemical formula (I) (including the above-mentioned salt form) in the hole transport layer 13 is preferably 20 to 100 mass %, more preferably 60 to 100 mass %, and even more preferably 99 to 100 mass %, relative to the mass of the hole transport layer 13.

(Second embodiment of the hole transport layer)
In a second embodiment of the hole transport layer 13, the hole transport layer 13 contains a compound represented by the following chemical formula (I) and a compound represented by the following chemical formula (II), and satisfies at least one of the following conditions (a) and (b): In a more preferred embodiment, in the hole transport layer 13, the compound represented by the following chemical formula (I) and the compound represented by the following chemical formula (II) are chemically bonded or hydrogen bonded to the first electrode.
Ar ¹ -(L ¹ -X ¹ )n. ． ． (I)
When the hole transport layer is the second embodiment, in the chemical formula (I), Ar ¹ is a structure containing an aromatic ring, and the atoms constituting the aromatic ring may contain a heteroatom, and Ar ¹ may have a substituent other than -L ¹ -X ^1. n is an integer of 1 or more, and when n is 2 or more, the structures represented by -L ¹ -X ¹ may be the same or different from each other. L ¹ is a divalent linking group that bonds Ar ¹ and X ¹ , or a single bond. X ¹ is a group that can form a chemical bond or a hydrogen bond with the first electrode.
A ¹ -L ² -X ² . ． ． (II)
A ¹ is an atomic group containing one or more substituents or structures selected from the group consisting of an alkoxy group, a hydroxy group, a carboxy group, a dihydroxyphosphoryl group, a dialkylphosphoryl group, a hydroxysulfonyl group, an amino group, a monoalkylamino group, a dialkylamino group, a monoarylamino group, a diarylamino group, a monoalkylaminocarbonyl group, a dialkylaminocarbonyl group, an alkylcarbonyloxy group, an alkoxycarbonyl group, an aminocarbonyl group, an aminocarbonylamino group, an alkylcarbonylamino group, an alkylsulfonylamino group, an aminosulfonyl group, and a nitrogen-containing heterocyclic group. L ² is a divalent linking group or a single bond that bonds A ¹ and X ^2. X ² is a group capable of chemically bonding or hydrogen bonding with the first electrode.
Condition (a): Ar ¹ in the compound represented by chemical formula (I) contains a nitrogen atom among atoms constituting the aromatic ring, and in at least a part of Ar ¹ in the compound represented by chemical formula (I), the nitrogen atom constituting the aromatic ring and an anion form a salt.
In addition, in at least a part of Ar ¹ in which a salt is formed, when there are multiple nitrogen atoms constituting an aromatic ring, all of the nitrogen atoms may form salts with anions, or only some of them may form salts with anions.
Condition (b): A ¹ in the compound represented by chemical formula (II) contains a nitrogen atom, and at least a part of A ¹ in the compound represented by chemical formula (II) forms a salt from the nitrogen atom and an anion.
In addition, in at least a part of A ¹ in which a salt has been formed, when there are a plurality of nitrogen atoms, all of the nitrogen atoms may form salts with anions, or only a part of the nitrogen atoms may form salts with anions.

(Compound represented by formula (I))
When the photoelectric conversion element satisfies the condition (a), the compound represented by chemical formula (I) is the same as the compound represented by chemical formula (I) described in the first embodiment of the hole transport layer, and therefore further description is omitted.
When condition (a) is satisfied, the aspect in which at least a part of Ar ¹ in the compound represented by chemical formula (I) forms a salt with a nitrogen atom constituting an aromatic ring and an anion is similar to the aspect in which at least a part of Ar ¹ in the compound represented by chemical formula (I) described in the first aspect of the hole transport layer forms a salt with a nitrogen atom constituting an aromatic ring and an anion, and therefore a description thereof will be omitted. The same applies to acids, bases, and anions that can be used to form salts, and therefore a description thereof will be omitted.

When the photoelectric conversion element does not satisfy the condition (a), the compound represented by the chemical formula (I) may be in a form in which the structure corresponding to Ar ¹ (structure containing an aromatic ring) does not contain a nitrogen atom in the atoms constituting the aromatic ring, or may be in a form in which the structure corresponding to Ar 1 (structure containing an aromatic ring) does not contain a nitrogen atom in the atoms constituting the aromatic ring. Even if the structure corresponding to Ar ¹ (structure containing an aromatic ring) contains a nitrogen atom in the atoms constituting the aromatic ring, if no salt is formed between the nitrogen atom constituting the aromatic ring and an anion in any of the Ar ¹ , the condition (a) is not satisfied.
In the case where the photoelectric conversion element does not satisfy the condition (a), specifically, in the chemical formula (I), Ar ¹ is preferably, for example, an aromatic ring group, a group in which a plurality of aromatic ring groups are bonded to each other through single bonds, or a group in which one or more aromatic ring groups are condensed with a ring having no aromaticity.

The aromatic ring group may be a monocyclic or polycyclic (e.g., 2 to 14 rings) group and may have one or more (e.g., 1 to 10) heteroatoms (such as nitrogen atoms, sulfur atoms, and/or oxygen atoms). The number of ring atoms in the aromatic ring group is preferably 5 to 40.
Examples of the aromatic ring group include a benzene ring group, a pyrrole ring group, a furan ring group, a thiophene ring group, and a group formed by condensing two or more (eg, 2 to 14) rings selected from these.

Examples of the aromatic ring group constituting the group formed by bonding a plurality of aromatic ring groups with single bonds include the aromatic ring groups described above. The number of aromatic ring groups bonded with single bonds is preferably 2 to 6, for example.
Specific examples of the group in which a plurality of aromatic ring groups are bonded together through single bonds include a biphenyl ring group and a bithiophene ring group.

Examples of the aromatic ring group constituting the group in which one or more aromatic ring groups are condensed with a ring having no aromaticity include the aromatic ring groups described above.
Of the above-mentioned groups in which one or more aromatic ring groups are condensed to a ring having no aromaticity, the number of aromatic ring groups condensed to the ring having no aromaticity is preferably 2 to 6, for example.
The group in which one or more aromatic ring groups are condensed with a ring having no aromaticity may have only one ring having no aromaticity or may have a plurality of rings having no aromaticity.
In the group in which one or more aromatic ring groups are condensed with a ring having no aromaticity, the ring having no aromaticity may be independently a monocyclic ring or a polycyclic ring (e.g., 2 to 14 rings) and may have one or more (e.g., 1 to 10) heteroatoms (such as a nitrogen atom, a sulfur atom, and/or an oxygen atom).
Specific examples of the group in which one or more aromatic ring groups are condensed with a ring having no aromaticity include a phenothiazine ring group and a 1,2:3,4:5,6:7,8-tetrakis[imino(1,2-phenylene)]cyclooctatetraene ring group.

Chemical formula (I) in the case where the photoelectric conversion element does not satisfy condition (a) is the same as chemical formula (I) described in the first embodiment of the hole transport layer except for the requirement of Ar ¹ , and other description will be omitted.
The compound represented by chemical formula (I) in the case where the photoelectric conversion element does not satisfy the condition (a) may also form a salt with an anion if possible, and the salt may be an acid addition salt or a base addition salt. The acid that forms the acid addition salt and the base that forms the base addition salt are the same as the acid and base described in the case where a salt is formed from a nitrogen atom constituting an aromatic ring and an anion in at least a part of Ar ¹ of the compound represented by chemical formula (I) in the case where the hole transport layer is the first embodiment, and the description is omitted. The same applies to the anion that can be used to form a salt, and the description is omitted.

Specific examples of the compound represented by chemical formula (I) that can be used in the first or second aspect of the hole transport layer include compounds (A-01) to (A-30) having the following structures. Note that in the following, when the compound represented by chemical formula (I) is any of compounds (A-01) to (A-06), condition (a) is not satisfied.

In the compound represented by chemical formula (I), examples of the case where a salt is formed between a nitrogen atom constituting an aromatic ring and an anion include compounds (A-06a) to (A-30a) having the following structure. In the compounds (A-06a) to (A-30a), "AN ^- " represents an anion. As the anion (AN ^- ), for example, a monovalent anion among the anions listed as examples of anions that form a salt with the compound represented by chemical formula (I) when the hole transport layer is of the first embodiment can be mentioned.

The compound represented by chemical formula (I) and its salt may be formed, for example, as a monolayer on the first electrode 12.

(Compound represented by chemical formula (II))
When the hole transport layer is of the second aspect, in the hole transport layer 13 constituting the photoelectric conversion element 10 according to this embodiment, in addition to the compound represented by the above-mentioned chemical formula (I), the compound represented by the above-mentioned chemical formula (II) is used in combination as a co-adsorbent.
In the compound represented by chemical formula (II), ^A1 has a hydrophilic function, which improves wettability with respect to the perovskite solution that is applied and formed on the hole transport layer 13. It is considered that the improved wettability with respect to the perovskite solution allows the perovskite layer to be applied with a uniform thickness, which reduces variation in thickness, particularly when applying over a large area.

In the chemical formula (II), A ¹ represents an organic amino group such as a monoalkylamino group, a dialkylamino group, a monoarylamino group, a diarylamino group, an aminocarbonylamino group, an alkylcarbonylamino group, or an alkylsulfonylamino group, an alkoxy group, a hydroxy group, a carboxy group, a dihydroxyphosphoryl group, a dialkylphosphoryl group, a hydroxysulfonyl group, an amino group, a monoalkylaminocarbonyl group, a dialkylaminocarbonyl group, an alkylcarbonyloxy group, an alkoxycarbonyl group, an aminocarbonyl group, an aminosulfonyl group, or a nitrogen-containing heterocyclic group (which may or may not have aromaticity, may be a monocyclic or polycyclic ring, and preferably has 5 to 15 ring atoms, and preferably has 1 to 5 nitrogen atoms in the ring atoms). Preferably, it may have a heteroatom other than a nitrogen atom (preferably 1 to 3). For example, it is an atomic group containing one or more substituents or structures selected from the group consisting of a pyridine ring group, a quinoline ring group, an aziridine ring group, an azetidine ring group, a pyrrolidine ring group, an imidazolidine ring group, an imidazolidin-2-one ring group, a 2,3-dihydro-1H-pyrrole ring group, a pyrrole ring group, a pyrazole ring group, an imidazole ring group, a 1H-1,2,3-triazole ring group, a 2H-1,2,3-triazole ring group, a thiazole ring group, a morpholine ring group, a piperidine ring group, a piperazine ring group, a pyrazine ring group, a hexamethyleneimine ring group, a 1H-azepine ring group, an indole ring group, a 2,3-trimethyleneindoline ring group, and a quinoxaline ring group. ^{A 1} may be the substituent or structure listed above. In addition, when the substituents or structures enumerated above in ^A1 have an alkyl group portion (including an alkyl group portion in an alkoxy group), the alkyl group may be each independently linear or branched and preferably has 1 to 8 carbon atoms.

However, when condition (b) is satisfied, A ¹ in chemical formula (II) contains a nitrogen atom.
When the condition (b) is satisfied, specifically, ^A1 in the chemical formula (II) is preferably an amino group, a monoalkylamino group, a dialkylamino group, a monoarylamino group, a diarylamino group, a monoalkylaminocarbonyl group, a dialkylaminocarbonyl group, an aminocarbonylamino group, an alkylcarbonylamino group, an alkylsulfonylamino group, an aminosulfonyl group, or a nitrogen-containing heterocyclic group.
In addition, in at least a part of A ¹ in which a salt has been formed, when there are a plurality of nitrogen atoms, all of the nitrogen atoms may form salts with anions, or only a part of the nitrogen atoms may form salts with anions.

When the photoelectric conversion element does not satisfy the condition (b), the compound represented by the chemical formula (II) may be in a form in which the atomic group corresponding to A ¹ does not contain a nitrogen atom or may be in a form in which the atomic group corresponding to A ¹ contains a nitrogen atom. Even when the atomic group corresponding to A ¹ contains a nitrogen atom, condition (b) is not satisfied as long as no salt is formed between the nitrogen atom and an anion in any A 1.
In chemical formula (II), each ^X2 is independently selected from the group consisting of a dihydroxyphosphoryl group (-P=O(OH) ₂ ), a carboxyl group (-COOH), a sulfo group ( _-SO3H ), a boronic acid group (-B(OH) ₂ ), a trihalogenated silyl group ( _-SiX3 , where X is a halo group), or a trialkoxysilyl group (-Si(OR) ₃ , where R is an alkyl group), a trihydroxysilyl group, or a dialkylphosphoryl group.

In the chemical formula (II), the divalent linking group L ² is, for example, an alkylene group (which may be linear or branched, and preferably has 1 to 8 carbon atoms), a vinylene group, a vinylidene group, an acetylene group, an aromatic ring group (for example, the aromatic ring group described as the aromatic ring group that Ar ¹ in the chemical formula (I) can be when the condition (a) is not satisfied), a non-aromatic ring group (which may be monocyclic or polycyclic and may have a heteroatom. For example, a piperazine ring group can be mentioned), -O-, -S-, -NR ^N - (R ^N is a hydrogen atom or an alkyl group. The alkyl group may be linear or branched, and preferably has 1 to 8 carbon atoms), and a divalent linking group consisting of a combination of two or more of these (for example, 2 to 6). The divalent linking group consisting of a combination of two or more of the above may be a combination of the same type of groups (however, this does not include a combination in which alkylene groups are bonded consecutively).
If possible, these divalent linking groups may further have one or more (e.g., 1 to 6) substituents, for example, they may have one or more (e.g., 1 to 6) groups similar to those explained as ^A1 or ^X2 as the substituents.

Specific examples of compounds represented by chemical formula (II) include 3-methoxypropionic acid, 3-hydroxypropionic acid, 2-hydroxypropionic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid, terephthalic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid, methylenesuccinic acid, allylmalonic acid, isopropylidenesuccinic acid, acetylenedicarboxylic acid, dimethyl terephthalate, diethyl terephthalate, 4,4'-biphenyldicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and diethylphenyldicarboxylate, 4-methoxybenzoic acid, 3,4-dimethoxybenzoic acid, 4-(methylamino)benzoic acid, 4-(methylamino)benzenesulfonic acid, 4-(methylamino)butanoic acid, 3-(carboxymethylamino)propionic acid, 6-acetoxy-2-naphthoic acid, acetylsalicylic acid, 4-(methoxycarbonyl)cyclohexanecarboxylic acid, 4-(methoxycarbonyl)phenylboronic acid, 4-(N,N-diethylaminocarbonyl)phenylboronic acid, 3-( methylaminocarbonyl)acrylic acid, N-(aminocarbonyl)aspartic acid, 4-acetylaminobenzoic acid, 2-(acetylamino)acrylic acid, gallic acid, 4-pyridinecarboxylic acid, 6-quinolinecarboxylic acid, aspartic acid, 2,2-diethoxyethylphosphonic acid, methylene diphosphonic acid, 1,2-ethylene diphosphonic acid, 1,2-ethylene diphosphonic acid tetraethyl, 1,3-propylene diphosphonic acid, 3,4-dimethoxyphenylphosphonic acid, (4-hydroxybenzoyl) (p-phenyl)phosphonic acid, 4-hydroxyphenylphosphonic acid, [3-(3-carboxypiperazin-1-yl)propyl]phosphonic acid, (pyridin-4-ylmethyl)phosphonic acid, (pyridin-3-ylmethyl)phosphonic acid, 4-phosphonobenzoic acid, 3-phosphonopropionic acid, 4-phosphonobutyric acid, diethyl (4-methoxybenzyl)phosphonate, p-carboxybenzenesulfonylamide, 2-(dimethylamino)ethanesulfonic acid, 1,2-ethanesulfonic acid, etc.

Specific examples of ^L2 include alkylenes such as 1,1-ethylene, 1,2-ethylene, 1,3-propylene, and 2-ethyl-1,6-hexylene, in which a portion of the alkylene may be an alkenylene having a carbon-carbon double bond or an alkynylene having a triple bond, and further include arylenes such as 1,2-phenylene, 1,4-phenylene, 1,5-naphthylene, and 4,4'-biphenylene, and divalent heterocycles such as 2,5-thienylene, 5,5'-bithienylene, 2,5-thieno[3,2-b]thienylene, and 2,6-pyridylene.

When condition (b) is satisfied, in the case where at least a part of A ¹ in the compound represented by chemical formula (II) forms a salt with a nitrogen atom and an anion, the form of the salt, the type of acid, base, anion, etc. that can be used are the same as the form of the salt, the type of acid, base, anion, etc. that can be used when at least a part of Ar ¹ in the compound represented by chemical formula (I) forms a salt with a nitrogen atom constituting an aromatic ring, and an anion when the hole transport layer is in the first form, and therefore the description thereof will be omitted.

In addition, when condition (b) is satisfied, examples of salts formed from nitrogen atoms and anions in the compound represented by the above chemical formula (II) include ammonium salts, aziridinium salts, azirinium salts, azetidinium salts, pyrrolidinium salts, pyrrolinium salts, pyrazolinium salts, pyrrolinium salts, pyrazolinium salts, imidazolinium salts, triazolinium salts, tetrazolinium salts, piperidinium salts, piperazinium salts, pyridinium salts, pyrazinium salts, morpholinium salts, thiazolinium salts, azepanium salts, azepinium salts, indolinium salts, indolinium salts, quinolinium salts, isoquinolinium salts, quinoxalinium salts, phenanthrolinium salts, and phenazinium salts. The acid that reacts with the compound represented by the above chemical formula (II) to form a salt may be any of the above organic acids, inorganic acids, or a mixture thereof.

In chemical formula (II), specific examples of compounds that do not form a salt (specific examples for the case of a method in which a hole transport layer is formed on ITO and then a salt is formed) include compounds (B-01) to (B-52) having the following structures.

More specifically, in the case where a salt is formed from a nitrogen atom and an anion in the compound represented by chemical formula (II), compounds (B-01a) to (B-52a) having the following structure can be mentioned. In the compounds (B-01a) to (B-52a), "AN ^- " represents an anion. As the anion (AN ^- ), for example, a monovalent anion among the anions mentioned as examples of anions that form a salt with the compound represented by chemical formula (I) when the hole transport layer is of the first embodiment can be mentioned.

The compound represented by chemical formula (I) and its salt, and the compound represented by chemical formula (II) and its salt may be formed, for example, as a monolayer on the first electrode 12.

In the case where the hole transport layer is of the second aspect, the content of the compound represented by chemical formula (I) (including the above-mentioned salt form) and the compound represented by chemical formula (II) (including the above-mentioned salt form) in the hole transport layer 13 is preferably 70 to 100 mass %, more preferably 90 to 100 mass %, and even more preferably 99 to 100 mass %, relative to the mass of the hole transport layer 13.
The molar ratio of the compound represented by chemical formula (I) (including the above-mentioned salt forms) to the compound represented by chemical formula (II) (including the above-mentioned salt forms) is preferably 1:100 to 1:1, more preferably 1:80 to 1:2, and even more preferably 1:50 to 1:5.

(Method of forming hole transport layer)
The method for forming the hole transport layer 13 is not particularly limited. For example, the hole transport layer 13 of this embodiment can be produced by a method in which a compound represented by chemical formula (I) or a compound represented by chemical formulas (I) and (II) is adsorbed onto the first electrode 12 to form a monomolecular layer, and then the above-mentioned acid or base is appropriately added by a known method.
The method of adsorbing the compound represented by chemical formula (I) or the compound represented by chemical formula (I) and chemical formula (II) on the first electrode 12 to form a monolayer is not particularly limited, but for example, the compound represented by chemical formula (I) or the compound represented by chemical formula (I) and chemical formula (II) may be dissolved in a solvent and brought into contact with the first electrode 12 to bond. The bond between the compound represented by chemical formula (I) and the first electrode 12 and the bond between the compound represented by chemical formula (II) and the first electrode 12 are not particularly limited, and may be a physical bond or a chemical bond. The type of the bond is also not particularly limited, and may be, for example, any of a hydrogen bond, an ester bond, a chelate bond, etc. The solvent for dissolving the compound represented by chemical formula (I) and the compound represented by chemical formula (II) is also not particularly limited, and may be, for example, one of water and an organic solvent, or both. More specifically, the solvent may be water, methanol, ethanol, 2-propanol, and other alcohols; diethyl ether, diisopropyl ether, and other ethers; acetone, methyl isobutyl ketone, and other ketones; ethyl acetate, isobutyl acetate, γ-butyrolactone, and other esters; tetrahydrofuran, thiophene, and other heterocyclic rings; N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and other amides; dimethyl sulfoxide, and other sulfones; diethyl sulfone, sulfolane, and other sulfones; acetonitrile, 3-methoxypropionitrile, and other nitriles; benzene, toluene, chlorobenzene, and other aromatic compounds; dichloromethane, chloroform, and other halogen-based solvents; chlorofluorocarbon, hydrochlorofluorocarbon, hydrofluorocarbon, and other fluorine-based solvents; and these may be used alone or in combination of two or more.

The specific method for adsorbing the compound represented by chemical formula (I) or the compound represented by chemical formula (I) and chemical formula (II) onto the first electrode 12 to form a monolayer is not particularly limited, but examples thereof include known methods such as dipping, spraying, spin coating, and bar coating. The temperature during adsorption is not particularly limited, but is preferably -20°C to 100°C, and more preferably 0°C to 50°C. The adsorption time is also not particularly limited, but is preferably 1 second to 48 hours, and more preferably 10 seconds to 1 hour.

After the adsorption treatment, for example, cleaning may or may not be performed. The method of cleaning is not particularly limited, but for example, a known method may be used as appropriate.

After the above-mentioned adsorption treatment or cleaning, a heat treatment may or may not be performed. The temperature of the heat treatment is preferably 50°C to 150°C, more preferably 70°C to 120°C. The heat treatment time is preferably 1 second to 48 hours, more preferably 10 seconds to 1 hour. This heat treatment may be performed, for example, in the atmosphere or in a vacuum.

In this embodiment, the "substituent" is not particularly limited, but examples thereof include an alkyl group, an alkenyl group, an alkynyl group, an unsaturated aliphatic hydrocarbon group, an alkoxy group, an aralkyl group, an aryl group, an arylalkenyl group, a heteroaryl group, a halogen atom (such as a fluorine atom, a chlorine atom, and/or a bromine atom), a hydroxyl group (-OH), a mercapto group (-SH), an alkylthio group (-SR, where R is an alkyl group), an amino group, a sulfo group, a nitro group, a diazo group, a cyano group, a trifluoromethyl group, and the like.

In addition, in this embodiment, if the compound has isomers such as tautomers or stereoisomers (e.g., geometric isomers, conformational isomers, and optical isomers), any isomer can be used in this embodiment unless otherwise specified.

[Photoelectric conversion layer]
The photoelectric conversion layer 14 is not particularly limited and may be the same as a photoelectric conversion layer used in a photoelectric conversion element such as a general solar cell. The photoelectric conversion layer 14 includes, for example, a perovskite compound. The perovskite compound may be, for example, an organic-inorganic perovskite compound represented by the following chemical formula (III).
XαYβZγ. ． ． (III)

In the chemical formula (III), the ratio of α:β:γ is 3:1:1, and β and γ represent integers greater than 1. X represents a halogen ion, Y represents an organic compound having an amino group, and Z represents a metal ion. The photoelectric conversion layer 14 containing the perovskite compound is preferably disposed adjacent to the electron transport layer 15 described below. Note that the ratio of α:β:γ does not necessarily have to be 3:1:1, for example, 3:1.05:0.95.

X in the chemical formula (III) is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include halogen ions such as chlorine, bromine, and iodine. These may be used alone or in combination of two or more.

In the chemical formula (III), Y may be an alkylamine compound ion (an organic compound having an amino group) such as methylamine, ethylamine, n-butylamine, or formamidine, or an alkali metal ion such as cesium, potassium, or rubidium, not limited to organic ions. The alkylamine compound ion or alkali metal ion may be used alone or in combination of two or more kinds. In addition, an organic ion (alkylamine compound ion) and an inorganic ion (alkali metal ion) may be used in combination, for example, a cesium ion and formamidine may be used in combination.

There is no particular restriction on Z in the chemical formula (III) and it can be appropriately selected according to the purpose. For example, metals such as lead, indium, antimony, tin, copper, and bismuth can be used. These may be used alone or in combination of two or more. Lead is particularly preferable, and a combination of lead and tin is particularly preferable. In addition, it is preferable that the perovskite layer exhibits a layered perovskite structure in which a layer made of a metal halide and a layer in which organic cation molecules are arranged are alternately laminated. The perovskite layer may contain an alkali metal. It is advantageous in that the output is high when the perovskite layer contains at least an alkali metal. Examples of alkali metals include cesium, rubidium, and potassium. Among these, cesium is preferable.

As described above, the photoelectric conversion layer 14 may be a perovskite layer formed from a perovskite compound. There are no particular limitations on the method for forming such a perovskite layer, and it can be appropriately selected depending on the purpose. For example, there is a method in which a solution in which a metal halide and an alkylamine halide are dissolved or dispersed is applied and then dried.

In addition, examples of methods for forming a perovskite layer include a two-step precipitation method in which a solution in which a metal halide is dissolved or dispersed is applied and dried, and then the substrate is immersed in a solution in which a halogenated alkylamine is dissolved, thereby forming a perovskite compound.

Other methods for forming a perovskite layer include, for example, applying a solution in which a metal halide and an alkylamine halide are dissolved or dispersed, while adding a poor solvent (a solvent with low solubility) for the perovskite compound to precipitate crystals.

Another method for forming a perovskite layer is, for example, a method in which a metal halide is evaporated in a gas filled with methylamine or the like.

A particularly preferred method for forming a perovskite layer is to apply a solution in which a metal halide and an alkylamine halide are dissolved or dispersed, while adding a poor solvent for the perovskite compound to precipitate crystals. There are no particular limitations on the method for applying these solutions, and they can be appropriately selected depending on the purpose, and examples include immersion, spin coating, spraying, dipping, roller, and air knife methods. In addition, the method for applying the solution may be, for example, a method in which crystals are precipitated in a supercritical fluid using carbon dioxide or the like. In the method of precipitating crystals by adding the above-mentioned poor solvent, examples of the poor solvent that can be used include hydrocarbons such as n-hexane and n-octane, alcohols such as methanol, ethanol, and 2-propanol, ethers such as diethyl ether and diisopropyl ether, ketones such as acetone and methyl isobutyl ketone, esters such as ethyl acetate, isobutyl acetate, and γ-butyrolactone, nitriles such as acetonitrile and 3-methoxypropionitrile, aromatic hydrocarbon compounds such as benzene, toluene, and chlorobenzene, halogen-based solvents such as dichloromethane and chloroform, and fluorine-based solvents such as chlorofluorocarbons, hydrochlorofluorocarbons, and hydrofluorocarbons.

The thickness of the photoelectric transport layer 14 (e.g., a light absorbing layer, e.g., a perovskite layer) is not particularly limited, but from the viewpoint of further suppressing performance degradation due to defects and peeling, it is preferably 50 to 1200 nm, and more preferably 200 to 1000 nm.

[Electron Transport Layer]
The material used for the electron transport layer 15 is not particularly limited and can be appropriately selected depending on the purpose, but is preferably a semiconductor material. The semiconductor material is not particularly limited and any known material can be used, such as an elemental semiconductor, a compound semiconductor, or an organic n-type semiconductor.

The elemental semiconductor is not particularly limited, but examples include silicon and germanium.

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

The organic n-type semiconductor is not particularly limited, but examples thereof include perylene tetracarboxylic anhydride, perylene tetracarboxydiimide compound, naphthalene diimide-bithiophene copolymer, benzobisimidazobenzophenanthroline polymer, fullerane compounds such as C ₆₀ , C ₇₀ , and PCBM ([6,6]-phenyl-C ₆₁ -butyric acid methyl ester), carbonyl bridge-bithiazole compound, and ALq ₃
(tris(8-quinolinolato)aluminum), triphenylene bipyridyl compounds, silole compounds, oxadiazole compounds, and the like.

Among the above-mentioned materials used for the electron transport layer 15, organic n-type semiconductors are particularly preferred.

The material used to form the electron transport layer 15 may be a single type, or two or more types may be used in combination. The crystal type of the semiconductor material is not particularly limited and can be appropriately selected depending on the purpose. It may be single crystal, polycrystalline, or amorphous.

There are no particular limitations on the film thickness of the electron transport layer 15 and it can be selected appropriately depending on the purpose, but it is preferably 5 nm to 1000 nm, and more preferably 10 nm to 700 nm.

There is no particular restriction on the method of forming the electron transport layer 15, and it can be appropriately selected according to the purpose. For example, a method of forming a thin film in a vacuum (vacuum film-forming method), a wet film-forming method, etc. can be mentioned. Examples of the vacuum film-forming method include a sputtering method, a pulsed laser deposition method (PLD method), an ion beam sputtering method, an ion-assisted method, an ion plating method, a vacuum deposition method, an atomic layer deposition method (ALD method), and a chemical vapor deposition method (CVD method). Examples of the wet film-forming method include a method of forming a film by applying a solvent in which an electron transport material is dissolved, and in the case of an oxide semiconductor, a sol-gel method can be mentioned. The sol-gel method is a method in which a gel is produced from a solution through chemical reactions such as hydrolysis, polymerization, and condensation, and then densification is promoted by heat treatment. When the sol-gel method is used, the method of applying the sol solution is not particularly limited and can be appropriately selected depending on the purpose. Examples of the method include dipping, spraying, wire bar, spin coating, roller coating, blade coating, and gravure coating. Wet printing methods include letterpress, offset, gravure, intaglio, rubber plate, and screen printing. The temperature during the heat treatment after applying the sol solution is preferably 80°C or higher, and more preferably 100°C or higher.

After forming the electron transport layer 15, an electron injection layer (hole blocking layer) may be formed between the second electrode 16. An example of a material used for the electron injection layer is BCP (bathocuproine), which may be doped with cesium. The electron injection layer is preferably 1 to 100 nm, more preferably 3 to 20 nm.

[Second Electrode]
The second electrode 16 (which may be, for example, a back electrode) is, for example, a layer having a function of extracting electrons from the photoelectric conversion layer 14 via the electron transport layer. In addition, the second electrode 16 is, for example, a layer that functions as an anode (negative electrode).

The second electrode 16 may be formed directly on the electron transport layer (also called the electron injection layer) 15. The material of the second electrode 16 is not particularly limited, and may be the same material as the first electrode 12, for example. The shape, structure, and size of the second electrode 16 are not particularly limited, and may be appropriately selected depending on the purpose. Examples of materials for the second electrode 16 include metals, carbon compounds, conductive metal oxides, and conductive polymers.

Examples of the metal include platinum, gold, silver, copper, and aluminum.

Examples of the carbon compounds include graphite, fullerene, carbon nanotubes, and graphene.

Examples of the conductive metal oxide include ITO, FTO, and ATO.

Examples of the conductive polymer include polythiophene and polyaniline.

The material used to form the second electrode 16 may be a single material or a combination of two or more materials.

The second electrode 16 can be formed on the electron transport layer 15 by coating, laminating, vacuum deposition, CVD, bonding, or other methods, depending on the type of material used and the type of hole transport layer 13.

In addition, in the photoelectric conversion element 10 of this embodiment, it is preferable that at least one of the first electrode 12 and the second electrode 16 is substantially transparent. When using the photoelectric conversion element 10 of this embodiment, it is preferable to make the electrodes transparent and allow incident light to enter from the electrode side. In this case, it is preferable to use a material that reflects light for the back electrode (the electrode opposite the transparent electrode, for example, the second electrode 16), and metals, glass on which conductive oxides are vapor-deposited, plastics, metal thin films, etc. are preferably used. In addition, providing an anti-reflection layer on the electrode on the incident light side is also an effective measure.

The configuration of the photoelectric conversion element 10 is not limited to the configuration of FIG. 1. For example, the support 11 may be disposed on the opposite side to that of FIG. 1 (above the second electrode 16 in FIG. 1), and the second electrode 16, the electron transport layer 15, the photoelectric conversion layer 14, the hole transport layer 13, and the first electrode 12 may be laminated on the support 11 in the above order. Also, for example, as described above, other components may or may not be present between the layers of the support 11, the first electrode 12, the hole transport layer 13, the photoelectric conversion layer 14, the electron transport layer 15, and the second electrode 16. Also, although an example in which the first electrode 12 is a transparent electrode and the second electrode 16 is a back electrode has been described, the photoelectric conversion element 10 is not limited to this. For example, in the photoelectric conversion element 10, the first electrode 12 may be a back electrode and the second electrode 16 may be a transparent electrode.

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

The material for the sealing member is not particularly limited and can be appropriately selected depending on the purpose. For example, it is preferable to use an epoxy resin or an acrylic resin and to harden it, but it does not matter if it is unhardened or only partially hardened.

The epoxy resin is not particularly limited, but examples thereof include water-dispersed, solvent-free, solid, heat-cured, curing agent-mixed, and ultraviolet-cured resins. Of these, heat-cured and ultraviolet-cured resins are preferred, and ultraviolet-cured resins are more preferred. Even if the resin is ultraviolet-cured, it is possible to perform heating, and it is preferred to perform heating even after ultraviolet curing. Specific examples of epoxy resins include bisphenol A type, bisphenol F type, novolac type, cyclic aliphatic type, long-chain aliphatic type, glycidylamine type, glycidyl ether type, and glycidyl ester type, which may be used alone or in combination of two or more types. In addition, it is preferred to mix a curing agent or various additives into the epoxy resin as necessary. Epoxy resin compositions that are already commercially available can be used in this embodiment. Among these, there are also epoxy resin compositions that have been developed and are commercially available for use in solar cells and organic EL elements, which can be used particularly effectively in this embodiment. Examples of commercially available epoxy resin compositions include TB3118, TB3114, TB3124, TB3125F (manufactured by ThreeBond Co., Ltd.), WorldRock5910, WorldRock5920, WorldRock8723 (manufactured by Kyoritsu Chemical Industries Co., Ltd.), WB90US(P), WB90US-HV (manufactured by Moresco Co., Ltd.), etc.

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

The curing agent is not particularly limited and can be appropriately selected depending on the purpose. Examples of the curing agent include amine-based, acid anhydride-based, polyamide-based, and other curing agents. Examples of the amine-based curing agent include aliphatic polyamines such as diethylenetriamine and triethylenetetramine, and aromatic polyamines such as metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone. Examples of the acid anhydride-based curing agent include phthalic anhydride, tetrahydrophthalic anhydride and hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, pyromellitic anhydride, HET anhydride, and dodecenyl succinic anhydride. Examples of other curing agents include imidazoles and polymercaptan. These may be used alone or in combination of two or more.

The additives are not particularly limited and can be appropriately selected according to the purpose. Examples of the additives include a filler, a gap agent, a polymerization initiator, a drying agent (moisture absorbent), a curing accelerator, a coupling agent, a flexibilizer, a colorant, a flame retardant assistant, an antioxidant, and an organic solvent. Among these, a filler, a gap agent, a curing accelerator, a polymerization initiator, and a drying agent (moisture absorbent) are preferred, and a filler and a polymerization initiator are more preferred. By including a filler as an additive, it is possible to suppress the intrusion of moisture and oxygen, and further to obtain effects such as a reduction in volumetric shrinkage during curing, a reduction in the amount of outgassing during curing or heating, an improvement in mechanical strength, and control of thermal conductivity and fluidity. Therefore, including a filler as an additive is very effective in maintaining a stable output in various environments.

In addition, when it comes to the output characteristics and durability of photoelectric conversion elements, the effects of not only the intrusion of moisture and oxygen, but also the outgassing that occurs when the sealing material is cured or heated cannot be ignored. In particular, the outgassing that occurs when heated has a significant effect on the output characteristics when stored in a high-temperature environment. By incorporating a filler, gap agent, or desiccant into the sealing material, these themselves can suppress the intrusion of moisture and oxygen, and by reducing the amount of sealing material used, the effect of reducing outgassing can be obtained. Incorporating a filler, gap agent, or desiccant into the sealing material is effective not only during curing, but also when storing photoelectric conversion elements in a high-temperature environment.

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

The average primary particle size of the filler is not particularly limited, but is preferably 0.1 μm or more and 10 μm or less, and more preferably 1 μm or more and 5 μm or less. When the average primary particle size of the filler is within the above preferred range, the effect of suppressing the intrusion of moisture and oxygen can be sufficiently obtained, the viscosity becomes appropriate, the adhesion to the substrate and the degassing property are improved, and it is also effective in controlling the width of the sealing part and workability.

The content of the filler is preferably 10 parts by mass or more and 90 parts by mass or less, and more preferably 20 parts by mass or more and 70 parts by mass or less, relative to the entire sealing member (100 parts by mass). When the content of the filler is within the above preferred range, the effect of suppressing the intrusion of moisture and oxygen is sufficiently obtained, the viscosity is appropriate, and the adhesion and workability are also good.

The gap agent is also called a gap control agent or spacer agent. By including a gap agent as an additive, it becomes possible to control the gap of the sealing portion. For example, when a sealing member is applied onto a first substrate or a first electrode, and a second substrate is placed on top of that to perform sealing, since the sealing member contains a gap agent, the gap of the sealing portion is aligned to the size of the gap agent, and therefore the gap of the sealing portion can be easily controlled.

The gap agent is not particularly limited, but is preferably granular, has a uniform particle size, and has high solvent resistance and heat resistance, and can be appropriately selected according to the purpose. The gap agent is preferably one that has high affinity with epoxy resin and has a spherical particle shape. Specifically, glass beads, silica fine particles, organic resin fine particles, etc. are preferable. These may be used alone or in combination of two or more. The particle size of the gap agent can be selected according to the gap of the sealing part to be set, but is preferably 1 μm or more and 100 μm or less, and more preferably 5 μm or more and 50 μm or less.

The polymerization initiator is not particularly limited, but examples thereof include polymerization initiators that use heat or light to initiate polymerization, and can be appropriately selected according to the purpose. For example, thermal polymerization initiators and photopolymerization initiators can be used. Thermal polymerization initiators are compounds that generate active species such as radicals and cations when heated, and examples of such initiators include azo compounds such as 2,2'-azobisbutyronitrile (AIBN) and peroxides such as benzoyl peroxide (BPO). As thermal cationic polymerization initiators, benzenesulfonic acid esters and alkylsulfonium salts can be used. As photopolymerization initiators, photocationic polymerization initiators are preferably used in the case of epoxy resins. When the photocationic polymerization initiator is mixed with the epoxy resin and irradiated with light, the photocationic polymerization initiator decomposes to generate acid, which causes the epoxy resin to polymerize, and the curing reaction proceeds. The photocationic polymerization initiator has the effects of having little volume shrinkage during curing, not being inhibited by oxygen, and having high storage stability.

Examples of the photocationic polymerization initiator include aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts, methacerone compounds, and silanol aluminum complexes. In addition, photoacid generators that have the function of generating acid by irradiation with light can also be used as polymerization initiators. Photoacid generators act as acids that initiate cationic polymerization, and examples of such photoacid generators include onium salts, such as ionic sulfonium salts and iodonium salts, which are composed of a cationic portion and an anionic portion. These may be used alone or in combination of two or more types.

The amount of the polymerization initiator to be added is not particularly limited and may vary depending on the material used, but is preferably 0.5 parts by mass to 10 parts by mass, and more preferably 1 part by mass to 5 parts by mass, relative to the entire sealing member (100 parts by mass). By adding an amount within the above preferred range, curing proceeds properly, the amount of uncured material remaining can be reduced, and excessive outgassing can be prevented.

The desiccant (also called moisture absorbent) is a material that has the function of physically or chemically adsorbing or absorbing moisture, and by including it in the sealing member, moisture resistance can be further improved and the effects of outgassing can be reduced. There are no particular limitations on the desiccant and it can be selected appropriately depending on the purpose, but particulate desiccants are preferred, and examples of such desiccants include inorganic water-absorbing materials such as calcium oxide, barium oxide, magnesium oxide, magnesium sulfate, sodium sulfate, calcium chloride, silica gel, molecular sieves, and zeolite. Among these, zeolite, which has a high moisture absorption capacity, is preferred. These may be used alone or in combination of two or more types.

The curing accelerator (also called a curing catalyst) is a material that accelerates the curing speed, and is mainly used for thermosetting epoxy resins. There are no particular limitations on the curing accelerator, and it can be appropriately selected according to the purpose. Examples of the curing accelerator include tertiary amines or tertiary amine salts such as DBU (1,8-diazabicyclo(5,4,0)-undecene-7) and DBN (1,5-diazabicyclo(4,3,0)-nonene-5), imidazoles such as 1-cyanoethyl-2-ethyl-4-methylimidazole and 2-ethyl-4-methylimidazole, and phosphines or phosphonium salts such as triphenylphosphine and tetraphenylphosphonium tetraphenylborate. These may be used alone or in combination of two or more.

The coupling agent is not particularly limited as long as it is a material that has the effect of increasing molecular bonding strength, and can be appropriately selected according to the purpose. For example, silane coupling agents can be mentioned. Specific examples include silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, N-(2-(vinylbenzylamino)ethyl)3-aminopropyltrimethoxysilane hydrochloride, and 3-methacryloxypropyltrimethoxysilane. These may be used alone or in combination of two or more.

In this embodiment, for example, a sheet-like adhesive can be used. The sheet-like adhesive is, for example, a resin layer formed on a sheet using a sealing resin in advance, and the sheet can be made of glass or a film with high gas barrier properties. The sheet-like adhesive may also be formed using only the sealing resin. It is also possible to attach the sheet-like adhesive to the sealing film. In this case, it is also possible to provide a hollow portion in the sheet constituting the sheet-like adhesive attached to the sealing film, and then attach it to the device.

When sealing is performed using the sealing film, the sealing film is disposed opposite the support so as to sandwich the photoelectric conversion device. There are no particular limitations on the shape, structure, size, or type of the substrate of the sealing film, and it can be appropriately selected according to the purpose. The sealing film forms a barrier layer on the surface of the substrate to prevent the passage of moisture and oxygen, and may be formed on only one side or both sides of the substrate.

The barrier layer may be composed of a material mainly composed of, for example, a metal oxide, a metal, or a mixture formed of a polymer and a metal alkoxide. Examples of the metal oxide include aluminum oxide, silicon oxide, and aluminum. Examples of the polymer include polyvinyl alcohol, polyvinylpyrrolidone, and methyl cellulose. Examples of the metal alkoxide include tetraethoxysilane, triisopropoxyaluminum, 3-glycidoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatopropyltriethoxysilane.

The barrier layer may be, for example, transparent or opaque. The barrier layer may be a single layer or a laminated structure of multiple layers made of a combination of the above materials. The barrier layer may be formed by any known method, including vacuum film formation such as sputtering, dipping, roll coating, screen printing, spraying, gravure printing, and other coating methods.

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

A lead wire is a general term for electrical wires used to electrically connect power sources and electronic components in an electrical circuit, and examples include vinyl wire and enamel wire.

The photoelectric conversion element 10 described above has excellent photoelectric conversion characteristics and has the advantage of having little bias in the photoelectric conversion characteristics depending on the location.

[application]
The application and method of use of the photoelectric conversion element 10 of this embodiment are not particularly limited, and can be widely used for applications similar to those of a general photoelectric conversion element (for example, a general solar cell). The photoelectric conversion element (for example, a solar cell) of this embodiment can be applied to a power supply device by combining it with a circuit board that controls the generated current, for example. Examples of devices that use a power supply device include electronic desk calculators and solar radio watches. The solar cell of this embodiment can also be applied as a power supply device to mobile phones, electronic paper, thermometers, hygrometers, etc. In addition, it can be applied to auxiliary power sources for extending the continuous use time of rechargeable or battery-powered electrical appliances, and to nighttime use by combining it with secondary batteries. It can also be used as an independent power source that does not require battery replacement or power wiring.

The following describes examples of the present invention. However, the present invention is not limited to the following examples.

[Example 1]
A solar cell, which is a photoelectric conversion element, was prepared (manufactured) in the following manner.

1 mL of the DMF solution in which the above-mentioned (A-15) (0.1 mmol/L) was dissolved was placed on the ITO of an ITO glass substrate (a glass substrate serving as a support on which a first electrode was formed, 75 mm square size), and a monolayer (hole transport layer) was formed on the ITO (first electrode) using a spin coater (3,000 rpm, 30 seconds). Methanolic hydrochloric acid (0.5 mol/L) was placed on this monolayer and allowed to stand for 1 minute, and excess solution was removed using a spin coater (3,000 rpm, 30 seconds). Next, a solution of cesium iodide (0.738 g), formamidine iodide (7.512 g), methylamine bromide (0.905 g), lead iodide (23.888 g), and lead bromide (1.022 g) dissolved in DMF (40.0 mL) and dimethyl sulfoxide (DMSO, 12.0 mL) was formed on the above substrate by spin coating. Spin coating was performed at 3000 rpm, and chlorobenzene (0.3 mL) was dropped 30 seconds after the start. After that, the substrate was heated at 150 ° C for 10 minutes to obtain a perovskite layer (photoelectric conversion layer). Next, 20 nm of C ₆₀ (electron transport layer), bathocuproine (BCP, 8 nm) (electron injection layer), and Ag (100 nm) (second electrode) were formed by vacuum deposition to prepare a photoelectric conversion element. After fabrication, the 75 mm square photoelectric conversion element was divided into nine 25 mm squares, and the solar cell characteristics of each were evaluated. Table 1 shows the performance of the best cell and the average performance of the nine cells.

The photoelectric conversion characteristics of the sealed device prepared in Example 1 were measured by a method conforming to the output measurement method of silicon crystal solar cell of JIS C8913: 1998. A solar simulator (SMO-250III type manufactured by Bunkoukeiki Co., Ltd.) combined with an air mass filter equivalent to AM1.5G was adjusted to a light amount of 100 mW / cm ² with a secondary reference Si solar cell as a measurement light source, and the I-V curve characteristics were measured using a source meter (manufactured by Keithley Instruments Inc., 2400 type general-purpose source meter) while irradiating a test sample of a perovskite solar cell (sealed device prepared in Example 1), and the short-circuit current (Isc), open circuit voltage (Voc), fill factor (FF), and short-circuit current density (Jsc), and photoelectric conversion efficiency (PCE) obtained from the I-V curve characteristics measurement were obtained.

Equation 1: Short-circuit current density (Jsc; mA/cm ² )=Isc (mA)/effective light-receiving area S (cm ² )
Equation 2: Photoelectric conversion efficiency (PCE; %)=Voc(V)×Jsc(mA/cm ² )×FF×100/100(mW/cm ² )

[Example 2]
A photoelectric conversion element was produced (manufactured) and the photoelectric conversion efficiency was measured in the same manner as in Example 1, except that a chlorobenzene solution (0.5 mol/L) of p-toluenesulfonic acid was used instead of the methanolic hydrochloric acid in Example 1. The solar cell characteristic results are shown in Table 1 below.

[Example 3]
A photoelectric conversion element was produced (manufactured) and the photoelectric conversion efficiency was measured in the same manner as in Example 1, except that a DMF solution containing (A-15) (0.1 mmol/L) and (B-35) (12 mmol/L) was used instead of (A-15) (0.1 mmol/L) in Example 1. The solar cell characteristic results are shown in Table 1 below.

[Example 4]
A photoelectric conversion element was produced (manufactured) and the photoelectric conversion efficiency was measured in the same manner as in Example 1, except that (A-25) (0.1 mmol/L) was used instead of (A-15) (0.1 mmol/L) in Example 1. The solar cell characteristic results are shown in Table 1 below.

[Example 5]
A photoelectric conversion element was produced (manufactured) and the photoelectric conversion efficiency was measured in the same manner as in Example 2, except that (A-15) (0.1 mmol/L) and (B-35) were used instead of (A-15) (0.1 mmol/L) in Example 2. The solar cell characteristic results are shown in Table 1 below.

[Example 6]
A photoelectric conversion element was produced (manufactured) and the photoelectric conversion efficiency was measured in the same manner as in Example 4, except that a chlorobenzene solution (0.5 mol/L) of p-toluenesulfonic acid was used instead of the methanolic hydrochloric acid in Example 4. The solar cell characteristic results are shown in Table 1 below.

[Example 7]
A photoelectric conversion element was produced (manufactured) and the photoelectric conversion efficiency was measured in the same manner as in Example 3, except that a DMF solution of (B-22) (1 mmol/L) was used instead of (B-35) (12 mmol/L) in Example 3. The solar cell characteristic results are shown in Table 1 below.

[Example 8]
A photoelectric conversion element was produced (manufactured) and the photoelectric conversion efficiency was measured in the same manner as in Example 3, except that (B-51) (0.1 mmol/L) was used instead of (B-35) (12 mmol/L) in Example 3. The solar cell characteristic results are shown in Table 1 below.

[Example 9]
A photoelectric conversion element was produced (manufactured) and the photoelectric conversion efficiency was measured in the same manner as in Example 8, except that an aqueous solution (0.1 mol/L) of hydroiodic acid was used instead of the methanolic hydrochloric acid in Example 8. The solar cell characteristic results are shown in Table 1 below.

[Example 10]
A photoelectric conversion element was produced (manufactured) and the photoelectric conversion efficiency was measured in the same manner as in Example 3, except that (A-04) (0.1 mmol/L) was used instead of (A-15) (0.1 mmol/L) in Example 3. The solar cell characteristic results are shown in Table 1 below.

[Example 11]
A photoelectric conversion element was produced (manufactured) and the photoelectric conversion efficiency was measured in the same manner as in Example 8, except that (A-04) (0.1 mmol/L) was used instead of (A-15) (0.1 mmol/L) in Example 8. The solar cell characteristic results are shown in Table 1 below.

[Example 12]
A photoelectric conversion element was produced (manufactured) in the same manner as in Example 10, except that (A-04) (0.1 mmol/L) and (B-13a) (18 mmol/L) were used instead of (A-04) (0.1 mmol/L) and (B-35) (12 mmol/L) in Example 10, and that after forming a hole transport layer on an ITO glass substrate, no acid treatment was performed, and then the photoelectric conversion efficiency was measured. The solar cell characteristic results are shown in Table 1 below.

[Comparative Example 1]
A photoelectric conversion element was produced (manufactured) and its photoelectric conversion efficiency was measured in the same manner as in Example 1, except that the treatment with methanolic hydrochloric acid (acid treatment) in Example 1 was not carried out. The solar cell characteristic results are shown in Table 1 below.

[Comparative Example 2]
A photoelectric conversion element was produced (manufactured) and the photoelectric conversion efficiency was measured in the same manner as in Comparative Example 1, except that (B-35) (12 mmol/L) was used instead of (A-15) (0.1 mmol/L) in Comparative Example 1. The solar cell characteristic results are shown in Table 1 below.

[Comparative Example 3]
A photoelectric conversion element was produced (manufactured) and the photoelectric conversion efficiency was measured in the same manner as in Example 1, except that (A-04) (0.1 mmol/L) was used instead of (A-15) (0.1 mmol/L) in Example 1. The solar cell characteristic results are shown in Table 1 below.

[Comparative Example 4]
A photoelectric conversion element was produced (manufactured) and the photoelectric conversion efficiency was measured in the same manner as in Example 10, except that octylphosphonic acid (12 mmol/L) was used instead of (B-35) (12 mmol/L) in Example 10. The solar cell characteristic results are shown in Table 1 below.

From Table 1, it can be seen from the comparison between Example 1 and Comparative Example 1 that the acid treatment improves the interface between the photoelectric conversion layer (perovskite layer) and the hole transport layer formed of a monomolecule, thereby forming a uniform perovskite layer, and as a result, a photoelectric conversion element with little variation can be obtained. In addition, from Comparative Example 3, even if the acid treatment is performed using a hole transport material that does not have a nitrogen atom, the hole transport material does not form a salt, so the interface between the perovskite layer and the hole transport layer formed of a monomolecule is not improved, and good characteristics cannot be obtained. Similarly, from Comparative Example 4, when a compound that does not have a nitrogen atom is used in both the hole transport material and the co-adsorbent, even if the acid treatment is performed, the hole transport material does not form a salt, so the interface between the perovskite layer and the hole transport layer formed of a monomolecule is not improved, and good characteristics cannot be obtained.
On the other hand, comparisons between Examples 3 and 5, between Examples 4 and 6, and between Examples 8 and 9 show that even when p-toluenesulfonic acid or hydroiodide is used as an acid other than hydrochloric acid, good characteristics and good uniformity are obtained, and that the present invention is superior. Also, Examples 10 and 11 show that even when a compound not having a nitrogen atom is used as the hole transport material, the interface is improved by acid treatment by using a co-adsorbent containing a nitrogen atom in combination, and good performance and uniformity are obtained. These results clearly show that the present invention exhibits excellent photoelectric conversion characteristics.

As described above, this example confirms that by using the hole transport material of the above-mentioned aspect in the hole transport layer, it is possible to obtain a uniform, high-performance photoelectric conversion element with little variation.

The present invention has been described above using embodiments and examples. However, the present invention is not limited to the embodiments and examples described above, and can be arbitrarily and appropriately combined, modified, or selected and adopted as necessary within the scope of the spirit of the present invention.

As explained above, the photoelectric conversion element of the present invention is useful, for example, as a solar cell. The application and method of use of the photoelectric conversion element of the present invention are not particularly limited, and it can be applied in a wide range of fields, for example, with the same application and method of use as a general photoelectric conversion element (for example, a general solar cell).

REFERENCE SIGNS LIST 10 Photoelectric conversion element 11 Support 12 First electrode 13 Hole transport layer 14 Photoelectric conversion layer 15 Electron transport layer 16 Second electrode

Claims (8)

a first electrode, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode are laminated in this order;
the photoelectric conversion layer contains a perovskite compound,
The hole transport layer contains a compound represented by the following chemical formula (I), and in at least a part of Ar ¹ in the compound represented by the following chemical formula (I), a salt is formed between a nitrogen atom constituting the aromatic ring and an anion.
Ar ¹ -(L ¹ -X ¹ )n. ． ． (I)
In the chemical formula (I), Ar ¹ is a structure containing an aromatic ring, and the atoms constituting the aromatic ring contain a nitrogen atom, and Ar ¹ may have a substituent other than -L ¹ -X ^1. n is an integer of 1 or more, and when n is 2 or more, the structures represented by -L ¹ -X ¹ may be the same or different from each other. L ¹ is a divalent linking group that bonds Ar ¹ and X ¹ , or a single bond. X ¹ is a group that can form a chemical bond or a hydrogen bond with the first electrode. a first electrode, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode are laminated in this order;
the photoelectric conversion layer contains a perovskite compound,
The photoelectric conversion element, wherein the hole transport layer contains a compound represented by the following chemical formula (I) and a compound represented by the following chemical formula (II), and satisfies at least one of the following conditions (a) and (b):
Ar ¹ -(L ¹ -X ¹ )n. ． ． (I)
In the chemical formula (I), Ar ¹ is a structure containing an aromatic ring, and may contain a heteroatom among the atoms constituting the aromatic ring, and Ar ¹ may have a substituent other than -L ¹ -X ^1. n is an integer of 1 or more, and when n is 2 or more, the structures represented by -L ¹ -X ¹ may be the same or different from each other. L ¹ is a divalent linking group that bonds Ar ¹ and X ¹ , or a single bond. X ¹ is a group that can form a chemical bond or a hydrogen bond with the first electrode.
A ¹ -L ² -X ² . ． ． (II)
A ¹ is an atomic group containing one or more substituents or structures selected from the group consisting of an alkoxy group, a hydroxy group, a carboxy group, a dihydroxyphosphoryl group, a dialkylphosphoryl group, a hydroxysulfonyl group, an amino group, a monoalkylamino group, a dialkylamino group, a monoarylamino group, a diarylamino group, a monoalkylaminocarbonyl group, a dialkylaminocarbonyl group, an alkylcarbonyloxy group, an alkoxycarbonyl group, an aminocarbonyl group, an aminocarbonylamino group, an alkylcarbonylamino group, an alkylsulfonylamino group, an aminosulfonyl group, and a nitrogen-containing heterocyclic group. L ² is a divalent linking group or a single bond that bonds A ¹ and X ^2. X ² is a group capable of chemically bonding or hydrogen bonding with the first electrode.
Condition (a): Ar ¹ in the compound represented by chemical formula (I) contains a nitrogen atom among atoms constituting the aromatic ring, and in at least a part of Ar ¹ in the compound represented by chemical formula (I), the nitrogen atom constituting the aromatic ring and an anion form a salt.
Condition (b): A ¹ in the compound represented by chemical formula (II) contains a nitrogen atom, and at least a part of A ¹ in the compound represented by chemical formula (II) forms a salt from the nitrogen atom and an anion. The photoelectric conversion element according to claim 2, characterized in that the molar ratio of the compound represented by chemical formula (II) to the compound represented by chemical formula (I) is 1:100 to 1:1. 3. The photoelectric conversion element according to claim 1, wherein each X ¹ in the chemical formula (I) is independently selected from the group consisting of a dihydroxyphosphoryl group (-P=O(OH) ₂ ), a carboxy group (-COOH), a sulfo group (-SO ₃ H), a boronic acid group (-B(OH) ₂ ), a trihalogenated silyl group (-SiX ₃ , where X is a halo group), and a trialkoxysilyl group (-Si(OR) ₃ , where R is an alkyl group). 4. The photoelectric conversion element according to claim 2 or 3, wherein X ² in the chemical formula (II) is selected from the group consisting of a dihydroxyphosphoryl group (-P=O(OH) ₂ ), a carboxyl group (-COOH), a sulfo group (-SO ₃ H), a boronic acid group (-B(OH) ₂ ), a trihalogenated silyl group (-SiX ₃ , where X is a halo group), a trialkoxysilyl group (-Si(OR) ₃ , where R is an alkyl group), a trihydroxysilyl group, and a dialkylphosphoryl group. The photoelectric conversion element according to claim 1 or 2, wherein the perovskite compound is an organic-inorganic perovskite compound. The photoelectric conversion element according to claim 1 or 2, wherein the perovskite compound contains at least one of tin and lead. The photoelectric conversion element according to claim 6 , wherein the organic-inorganic perovskite compound contains at least one of tin and lead.