Photoelectric conversion element and photoelectric conversion device

Abstract

The present application addresses the problem of providing a photoelectric conversion element using a compound that exhibits good photoelectric conversion efficiency even when not containing a dopant as a hole-transporting material. To solve this problem, the present application relates to a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer disposed between the first electrode and the second electrode and containing a crystal of a perovskite structure. The photoelectric conversion element has a hole-transporting layer containing a compound represented by formula (1) between the photoelectric conversion layer and the first electrode.

Description

Technical Field

[0001] This invention relates to photoelectric conversion elements and photoelectric conversion devices. Background Technology

[0002] To address the depletion of fossil fuels and the global environmental problems caused by their use, research has been actively conducted on renewable and clean alternative energy sources such as solar, wind, and hydropower. In particular, there is increasing interest in solar cells, which directly convert sunlight into electricity. As used herein, the term "solar cell" refers to a cell that generates current and voltage using the photovoltaic effect, in which light energy is absorbed from sunlight to produce electrons and holes.

[0003] Currently, NP diode-based silicon (Si) monocrystalline solar cells with a light conversion efficiency exceeding 20% ​​are widely known and have been practically used in solar power generation. However, solar cells require high-temperature processing, and the materials themselves are expensive, resulting in high unit electricity costs. Furthermore, the supply of silicon resources remains an issue.

[0004] Meanwhile, solar cells using organic materials (hereinafter also referred to as "organic solar cells") do not require high-temperature processing and can be manufactured using sheet-like substrates in a so-called roll-to-roll system. Therefore, cost reduction can be expected. However, for the practical application of organic solar cells, further improvements in power generation efficiency and durability are needed. In particular, perovskite solar cells, which include crystals with a perovskite structure as the photoelectric conversion layer, have been promoted for practical application due to their excellent photoelectric conversion performance. In perovskite solar cells, hole-transporting materials are typically used in their elements, and the purpose of using hole-transporting materials is, for example, to enhance the selective transport of holes to improve photoelectric conversion efficiency.

[0005] Spiro-OMeTAD, a spirobisfluorene-based organic compound, is commonly used as a standard hole transport material; however, pure Spiro-OMeTAD exhibits relatively low hole mobility and conductivity. Therefore, additives, i.e., dopants, such as lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) or 4-tert-butylpyridine (TBP), are added to improve these electronic properties. However, LiTFSI and TBP each have the following drawbacks: the compounds promote battery degradation due to their hygroscopic and volatile properties; and the compounds do not covalently bond with the hole transport material, thus readily diffusing. Therefore, LiTFSI and TBP are unsuitable for device fabrication and increase costs.

[0006] In view of the above, the development of hole transport materials to replace Spiro-OMeTAD has been carried out in recent years. For example, Patent Document 1 discloses a technique for obtaining a photoelectric conversion element by using a compound represented by the following formula (B-1) as a hole transport material, which exhibits higher photoelectric conversion efficiency and durability than Spiro-OMeTAD.

[0007] [Chemistry 1]

[0008]

[0009] In addition, Non-Patent Literature 1 reports an example in which a compound represented by the following formula (B-2) is used as a hole transport material, but this use is for dye-sensitized solar cell applications.

[0010] [Chemistry 2]

[0011]

[0012] Existing technical documents

[0013] Patent documents

[0014] Patent Document 1: International Publication No. WO2022 / 153962

[0015] Non-patent literature

[0016] Non-patent literature 1: PM Lahti et al., RSC Adv., 2013, 3, 15626-15629 Summary of the Invention

[0017] The problem the invention aims to solve

[0018] According to research conducted by the inventors of this invention, the photoelectric conversion element described in Patent Document 1 does not exhibit high electronic properties when free of dopants, and there is room for improvement in the conversion efficiency of photoelectric conversion elements not described in Patent Document 1. Therefore, this invention relates to providing a photoelectric conversion element that uses a compound as a hole transport material that exhibits satisfactory photoelectric conversion efficiency even when free of dopants. This invention also relates to providing a photoelectric conversion device that uses a compound as a hole transport material that exhibits satisfactory photoelectric conversion efficiency even when free of dopants.

[0019] Solution for solving the problem

[0020] The aforementioned photoelectric conversion element and photoelectric conversion device are provided by the present invention described below. Specifically, the photoelectric conversion element according to the present invention is a photoelectric conversion element comprising: a first electrode; a second electrode; and a photoelectric conversion layer disposed between the first electrode and the second electrode, the photoelectric conversion layer comprising a crystal having a perovskite structure, wherein the photoelectric conversion element includes a hole transport layer comprising a compound represented by the following formula (1) between the photoelectric conversion layer and the first electrode:

[0021] [Chemistry 3]

[0022] ,

[0023] In equation (1), A represents

[0024] [Chemistry 4]

[0025] ,

[0026] B indicates

[0027] [Chemistry 5]

[0028] ,

[0029] C indicates

[0030] [Chemistry 6]

[0031] ,

[0032] D indicates

[0033] [Chemistry 7]

[0034] ,

[0035] Furthermore, R in A to D 1 To R 20 Each of the following can independently represent a hydrogen atom, a trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms that may have a substituent, a linear or branched alkenyl group having 2 to 20 carbon atoms that may have a substituent, a cycloalkyl group having 3 to 10 carbon atoms that may have a substituent, an alkoxy group having 1 to 20 carbon atoms that may have a substituent, a cycloalkoxy group having 3 to 10 carbon atoms that may have a substituent, an alkylthio or arylthio group having 1 to 18 carbon atoms that may have a substituent, a (di)alkylamino or (di)aryamino group having 1 to 20 carbon atoms that may have a substituent, an aromatic hydrocarbon group having 6 to 36 carbon atoms that may have a substituent, or a heterocyclic group having 5 to 36 cyclic atoms that may have a substituent, and in each formula * indicates a bonding position with formula (1), provided that A and B are different from each other and C and D are different from each other.

[0036] The effects of the invention

[0037] According to the present invention, a photoelectric conversion element that exhibits satisfactory photoelectric conversion efficiency even without dopants can be provided. Attached Figure Description

[0038] [ Figure 1 [Illustration 1] is a cross-sectional schematic diagram in the thickness direction of the photoelectric conversion element according to the first embodiment of the present invention.

[0039] [ Figure 2 [Illustration 1] is a cross-sectional schematic diagram in the thickness direction of a photoelectric conversion element according to a second embodiment of the present invention.

[0040] [ Figure 3 [Illustrated] is a perspective view schematically showing a moving body including a photoelectric conversion element according to one embodiment of the present invention.

[0041] [ Figure 4 [This is a perspective view used to schematically illustrate building materials including a photoelectric conversion element according to one embodiment of the present invention.] Detailed Implementation

[0042] The present invention has the following key features. A photoelectric conversion element includes: a first electrode; a second electrode; and a photoelectric conversion layer disposed between the first electrode and the second electrode, the photoelectric conversion layer comprising a crystal having a perovskite structure, wherein the photoelectric conversion element includes a hole transport layer comprising a compound represented by the following formula (1) between the photoelectric conversion layer and the first electrode:

[0043] [Chemistry 8]

[0044] ,

[0045] In equation (1), A represents

[0046] [Chemistry 9]

[0047] ,

[0048] B indicates

[0049] [Chemistry 10]

[0050] ,

[0051] C indicates

[0052] [Chemistry 11]

[0053] ,

[0054] D indicates

[0055] [Chemistry 12]

[0056] ,

[0057] Furthermore, R in A to D 1 To R 20 Each of the following can independently represent a hydrogen atom, a trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms that may have a substituent, a linear or branched alkenyl group having 2 to 20 carbon atoms that may have a substituent, a cycloalkyl group having 3 to 10 carbon atoms that may have a substituent, an alkoxy group having 1 to 20 carbon atoms that may have a substituent, a cycloalkoxy group having 3 to 10 carbon atoms that may have a substituent, an alkylthio or arylthio group having 1 to 18 carbon atoms that may have a substituent, a (di)alkylamino or (di)aryamino group having 1 to 20 carbon atoms that may have a substituent, an aromatic hydrocarbon group having 6 to 36 carbon atoms that may have a substituent, or a heterocyclic group having 5 to 36 cyclic atoms that may have a substituent, and in each formula * indicates a bonding position with formula (1), provided that A and B are different from each other and C and D are different from each other.

[0058] As a result of research conducted by the inventors of this invention, it has been discovered that when the photoelectric conversion element includes the aforementioned hole transport layer, the conversion efficiency of the photoelectric conversion element is excellent even without dopants. The details of why a higher conversion efficiency can be obtained in this invention than when using known compounds are not clear, but possible reasons are described below.

[0059] It is envisioned that when donor-acceptor-donor (DAD) type organic low-molecular-weight polymers with fluorenone structures in the acceptor portion are used as hole transport materials, high photoelectric conversion efficiency can be achieved even without dopants, considering the increased carrier density, energy matching with the underlying layer, and passivation with the perovskite-structured crystal in the photoelectric conversion layer. Furthermore, the photoelectric conversion element can include an intermediate layer containing phthalocyanine particles between the photoelectric conversion layer and the hole transport layer containing the organic low-molecular-weight polymer as the hole transport material. Since the DAD type organic low-molecular-weight polymers with fluorenone structures in the acceptor portion exhibit excellent compatibility with phthalocyanine particles, it is envisioned that hysteresis can be improved by enhancing film adhesion.

[0060] According to research conducted by the inventors of the present invention, in compounds represented by formula (B-1) that are DAD-type organic low molecules having a fluorenone structure in the acceptor portion, the HOMO distribution is biased towards the donor portion because the nitrogen atom of the diphenylamine in the donor portion is not adjacent to the acceptor portion. Therefore, it is believed that this compound has low hole transport capability when doped. Furthermore, similarly, it has been found that in compounds represented by formula (B-2) that are DAD-type organic low molecules having a fluorenone structure in the acceptor portion, there is space for further electron density bias because the substituents in the donor portion are unified only by methoxy groups.

[0061] In view of the above, in this invention, the photoelectric conversion efficiency can be improved by using a compound represented by formula (1) as a hole transport material, wherein A to D in formula (1) are such that A and B are different from each other, and C and D are different from each other. The inventors of this invention speculate that HOMO diffusion and hole transport capability are improved when the nitrogen atom of the diphenylamine in the donor portion is adjacent to the acceptor portion. Furthermore, the HOMO energy level of the entire molecule becomes shallower, and the donor property is improved. In addition, it is envisioned that the bias of the electron density of the donor portion and the increase of the carrier density of the entire molecule can be enhanced by introducing different substituents into the two phenyl groups bonded to the same nitrogen atom, respectively.

[0062] In equation (1), A to D are preferably such that A and B are different from each other, C and D are different from each other, A and C are the same as each other, and B and D are the same as each other, so as to spread the HOMO distribution equally to the left and right and improve the carrier transport efficiency.

[0063] In this invention, since it is expected that the carrier density will be increased by substituents with strong donor properties, it is preferred that R in A to D is [the substituent name is missing]. 1 To R 20 Each of the following can independently represent a hydrogen atom, a straight-chain or branched alkyl group having 1 to 20 carbon atoms that may have substituents, an alkoxy group having 1 to 20 carbon atoms that may have substituents, an alkylthio group or arylthio group having 1 to 18 carbon atoms that may have substituents, or a (di)alkylamino or (di)aryamino group having 1 to 20 carbon atoms that may have substituents.

[0064] In particular, when an electron density bias easily occurs in the donor portion, the photoelectric conversion efficiency is satisfactory when hole transport materials are used in the photoelectric conversion element. Therefore, R is more preferably preferred. 1 R 2 R 4 R 5 R 6 R 7 R 9 R 10 R11 R 12 R 14 R 15 R 16 R 17 R 19 and R 20 Each represents a hydrogen atom, and R 3 R 8 R 13 and R 18 The following conditions must be met.

[0065] When R 3 and R 13 When each represents a hydrogen atom, R is preferred. 8 and R 18 Each of the following can be a straight-chain or branched alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a (di)alkylamino or (di)aryamino group having 1 to 20 carbon atoms, or an alkylthio or arythio group having 1 to 18 carbon atoms.

[0066] When R 3 and R 13 When each refers to a straight-chain or branched alkyl group having 1 to 20 carbon atoms that may have substituents, R is preferred. 8 and R 18 Each of the following can be a substituent of an alkoxy group having 1 to 20 carbon atoms, a substituent of a (di)alkylamino or (di)aryamino group having 1 to 20 carbon atoms, or a substituent of an alkylthio or arythio group having 1 to 18 carbon atoms.

[0067] When R 3 and R 13 When each represents a linear or branched alkoxy group having 1 to 20 carbon atoms that may have substituents, R is preferred. 8 and R 18 Each represents a (di)alkylamino or (di)aromaticamino group having 1 to 20 carbon atoms that may have substituents.

[0068] When R 3 and R 13 When each represents an alkylthio group or arylthio group having 1 to 20 carbon atoms that may have substituents, R is preferred. 8 and R 18 Each represents a (di)alkylamino or (di)aromaticamino group having 1 to 20 carbon atoms that may have substituents.

[0069] In formula (1), from the viewpoint of further improving photoelectric conversion efficiency, when the phenyl in A does not contain substituents, the phenyl in B preferably has a straight-chain or branched alkyl group having 1 to 20 carbon atoms that may have substituents, an alkoxy group having 1 to 20 carbon atoms that may have substituents, a (di)alkylamino or (di)arylamino group having 1 to 20 carbon atoms that may have substituents, or an alkylthio or arylthio group having 1 to 18 carbon atoms that may have substituents.

[0070] In formula (1), from the viewpoint of further improving photoelectric conversion efficiency, when the phenyl in A has a straight-chain or branched alkyl group having 1 to 20 carbon atoms that may have substituents, it is preferable that the phenyl in B has an alkoxy group having 1 to 20 carbon atoms that may have substituents, a (di)alkylamino or (di)arylamino group having 1 to 20 carbon atoms that may have substituents, or an alkylthio or arylthio group having 1 to 18 carbon atoms that may have substituents.

[0071] In formula (1), from the viewpoint of further improving photoelectric conversion efficiency, when the phenyl in A has a straight-chain or branched alkoxy group having 1 to 20 carbon atoms that may have substituents, it is preferable that the phenyl in B has a (di)alkylamino or (di)aromaticamino group having 1 to 20 carbon atoms that may have substituents.

[0072] In formula (1), from the viewpoint of further improving photoelectric conversion efficiency, when the phenyl in A has an alkylthio group or an arylthio group having 1 to 18 carbon atoms that may have substituents, it is preferable that the phenyl in B has a (di)alkylamino group or (di)aryamino group having 1 to 20 carbon atoms that may have substituents.

[0073] The compound represented by formula (1) used as the hole transport material for the hole transport layer of the photoelectric conversion element of the present invention is described in detail below, but the present invention is not limited thereto.

[0074] In equation (1), A to D are R 1 To R 20 Each of the following can independently represent a hydrogen atom, a trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms that may have a substituent, a linear or branched alkenyl group having 2 to 20 carbon atoms that may have a substituent, a cycloalkyl group having 3 to 10 carbon atoms that may have a substituent, an alkoxy group having 1 to 20 carbon atoms that may have a substituent, a cycloalkoxy group having 3 to 10 carbon atoms that may have a substituent, an alkylthio or arylthio group having 1 to 18 carbon atoms that may have a substituent, a (di)alkylamino or (di)aryamino group having 1 to 20 carbon atoms that may have a substituent, an aromatic hydrocarbon group having 6 to 36 carbon atoms that may have a substituent, or a heterocyclic group having 5 to 36 cyclic atoms that may have a substituent.

[0075] By R 1 To R 20 Examples of "linear or branched alkyl groups having 1 to 20 carbon atoms" in each of the following expressions may include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, 2-ethylhexyl, heptyl, octyl, isooctyl, nonyl, and decyl.

[0076] By R 1 To R 20 Examples of "linear or branched alkenyl groups having 2 to 20 carbon atoms" in each of the following expressions can include vinyl, 1-propenyl, allyl, 1-methylvinyl, 1-butenyl, 2-butenyl, 1-pentenyl, 1-hexenyl, 2-methyl-1-propenyl, 2-methyl-2-propenyl, and 1-ethylvinyl, as well as linear or branched alkenyl groups having 2 to 20 carbon atoms bonded together with a plurality of these alkenyl groups.

[0077] By R 1 To R 20 Examples of "cycloalkyl group having 3 to 10 carbon atoms" in each of the following expressions can include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl, cyclododecyl, 4-methylcyclohexyl, and 4-ethylcyclohexyl.

[0078] By R 1 To R 20 Examples of "alkoxy groups having 1 to 20 carbon atoms" in each of the following expressions can include methoxy, ethoxy, propoxy, n-butoxy, n-pentoxy, n-hexoxy, heptoxy, octoxy, nonoxy, decoxy, isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, isooctoxy, tert-octoxy, phenoxy, tolyloxy, biphenyloxy, terphenyloxy, naphthoxy, anthraquinoneoxy, phenanthroxy, fluorenoxy, and indoxy.

[0079] By R 1 To R 20 Examples of “cycloalkoxy groups having 3 to 10 carbon atoms” in each of the following expressions can include cyclopropoxy, cyclobutoxy, cyclopentoxy, cyclohexoxy and 4-methylcyclohexoxy.

[0080] By R 1 To R20 Each instance of "alkoxythio or arylthio with 1 to 18 carbon atoms" in the phrase "may have substituents" may include methylthio, ethylthio, propylthio, phenylthio, and biphenylthio.

[0081] By R 1 To R 20 Examples of "(di)alkylamino or (di)arylamino" having 1 to 20 carbon atoms, which may have substituents, may include: monosubstituted amino groups, such as ethylamino and phenylamino; and disubstituted amino groups, such as diethylamino and diphenylamino. In addition to the amino groups mentioned above, acetamino and acetylphenylamino may also be selected.

[0082] By R 1 To R 20 Examples of "aromatic hydrocarbon group having 6 to 36 carbon atoms that may have substituents" in the present invention may include phenyl, biphenyl, terphenyl, naphthyl, anthraceneyl group, phenanthryl, fluorenyl, indene, pyrene, perylene, fluoranyl, and triphenylenyl group. In this invention, aromatic hydrocarbon group encompasses "condensed polycyclic aromatic groups".

[0083] By R 1 To R 20 Examples of "heterocyclic groups having 5 to 36 cyclic atoms" in each of the following can include pyridinyl, pyrimidinyl, triazine, morpholinyl, thiophene, furanyl (furyl group), pyrroloyl, imidazolyl, pyrazolyl, triazolyl, quinolinyl, isoquinolinyl, naphridinyl, acridineyl, phenanthrolinel, benzofuranyl, benzothiophene, oxazolyl, indolyl, carbazolyl, benzooxazolyl, thiazolyl, benzothiazolyl, quinoxalinyl, pyrazolyl, dibenzofuranyl, and dibenzothiophene.

[0084] By R 1 To R 20Each of the following represents "a linear or branched alkyl group having 1 to 18 carbon atoms that may have substituents", "a linear or branched alkenyl group having 2 to 20 carbon atoms that may have substituents", "a cycloalkyl group having 3 to 10 carbon atoms that may have substituents", "an alkoxy group having 1 to 20 carbon atoms that may have substituents", "a cycloalkoxy group having 3 to 10 carbon atoms that may have substituents", "an acyl group having 1 to 20 carbon atoms that may have substituents", "an alkylthio or arylthio group having 1 to 18 carbon atoms that may have substituents", "a (di)alkylamino or () alkylthio group having 1 to 20 carbon atoms that may have substituents". Examples of "substituents" in "aromatic amino", "aromatic hydrocarbon group having 6 to 36 carbon atoms with substituents", or "heterocyclic group having 5 to 36 cyclic atoms that may have substituents" can include: trimethylsilyl; straight-chain or branched alkyl groups each having 1 to 18 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, 2-ethylhexyl, heptyl, octyl, isooctyl, nonyl, and decyl; straight-chain or branched alkenyl groups each having 2 to 18 carbon atoms, such as vinyl groups. group), 1-propenyl, 2-propenyl (allyl), 1-butenyl, 2-butenyl, 1-pentenyl, 1-hexenyl, 2-methyl-1-propenyl, 2-methyl-2-propenyl and 1-ethyl vinyl; alkoxy groups, each having 1 to 18 carbon atoms, such as methoxy, ethoxy, propoxy, tert-butoxy, pentoxy and hexoxy; aromatic hydrocarbon groups, each having 6 to 30 carbon atoms, such as phenyl, naphthyl, anthracene, phenanthryl and pyrene; heterocyclic groups, each having 5 to 30 cyclic atoms, such as pyridyl, pyrimidinyl, triazine, thiophene, furanyl (furyl group) (furanyl (furanyl) (group) , pyrroloyl, imidazolyl, pyrazolyl, triazolyl, quinolinyl, isoquinolinyl, naphridinyl, acridineyl, phenanthrololinyl, benzofuranyl, benzothiopheneyl, oxazolyl, indolyl, carbazoleyl, benzooxazolyl, thiazolyl, benzothiazolyl, quinoxolinyl, benzimidazolyl, pyrazolyl, dibenzofuranyl and dibenzothiopheneyl; monosubstituted amino groups, such as amino (-NH2), ethylamino, acetamino and phenylamino; and disubstituted amino groups, such as diethylamino, diphenylamino and acetaminophenamino; and thiol groups: -SH, methylthio, ethylthio, propylthio, phenylthio and biphenylthio. Multiple such "substituents" may be included, and when multiple "substituents" are included, the "substituents" may be the same as or different from each other. Furthermore, each of these "substituents" may further have substituents given as examples above.

[0085] Furthermore, in formula (1), it is preferred that each of A to D has a hydrogen atom at one of the ortho or para positions, a straight-chain or branched alkyl group having 1 to 20 carbon atoms that may have a substituent, an alkoxy group having 1 to 20 carbon atoms that may have a substituent, a (di)alkylamino or (di)arylamino group having 1 to 20 carbon atoms that may have a substituent, or an alkylthio or arylthio group having 1 to 18 carbon atoms that may have a substituent.

[0086] Specific examples of compounds of formula (1) of the present invention are shown in Table 1, but the invention is not limited thereto. In Table 1, A to D represent A to D in formula (1), and the substituent description portion represents the substituents on the phenyl group. In Table 1, "no substituents" and R other than those described in the table are also listed. 1 To R 20 Each represents a hydrogen atom.

[0087] [Table 1]

[0088] Table 1

[0089]

[0090] In this invention, the compound represented by formula (1) is more preferably selected from any one of the following: the compound represented by formula (A-8), the compound represented by formula (A-12), the compound represented by formula (A-14), the compound represented by formula (A-16), and the compound represented by formula (A-23).

[0091] [Chemistry 13]

[0092] ,

[0093] [Chemistry 14]

[0094] ,

[0095] [Chemistry 15]

[0096] ,

[0097] [Chemistry 16]

[0098] ,

[0099] [Chemistry 17]

[0100] .

[0101] The compound represented by formula (1) can be synthesized by known methods. For example, the compound can be synthesized by a Buchwald-Hartwig cross-coupling reaction of 2,7-dibromofluorenone represented by formula (2) with an amine compound represented by each of the following general formulas (3) and (4).

[0102] [Chemistry 18]

[0103]

[0104] [Chemistry 19]

[0105]

[0106] [Chemistry 20]

[0107]

[0108] R in equations (3) and (4) 1 To R 20 R in equation (1) 1 To R 20 same.

[0109] The compounds represented by formula (1) can be purified, for example, by column chromatography, adsorption with silica gel, activated carbon, or activated clay, or by recrystallization or crystallization with a solvent. Alternatively, it is effective to use compounds whose purity is improved by combining these methods. Furthermore, these compounds can be identified by nuclear magnetic resonance (NMR) analysis.

[0110] The present invention is described in detail below through preferred embodiments. The present invention is not limited to the following embodiments, and the following embodiments, which may be appropriately modified and altered based on the ordinary knowledge of those skilled in the art without departing from the spirit of the invention, are also covered within the scope of the present invention.

[0111] As used herein, the term "layer" refers not only to a layer with clear boundaries or a flat, thin-film shape, but also to a layer with a concentration gradient in which the concentration of the element to be introduced gradually changes, or a layer that can form an intricate structure together with other layers. Furthermore, elemental analysis of layers can be performed, for example, by conducting TOF-SIMS / FE-TEM / EDS line analysis measurements of the cross-section of the photoelectric conversion element and determining the elemental distribution of specific elements.

[0112] Figure 1This is a cross-sectional view schematically illustrating the configuration of a photoelectric conversion element according to one embodiment of the present invention. The photoelectric conversion element 1 includes a substrate 2 and a second electrode 3, an electron transport layer 4, a photoelectric conversion layer 5, a hole transport layer 6, and a first electrode 7 disposed thereon. An intermediate layer 8 (not shown) may be formed between the photoelectric conversion layer 5 and the hole transport layer 6. One of the first electrode 7 and the second electrode 3 is an anode, and the other electrode is a cathode. Current can be extracted by connecting the first electrode 7 and the second electrode 3 to an external circuit.

[0113] The photoelectric conversion layer 5 is activated by light entering the layer through the following: substrate 2, second electrode 3, and electron transport layer 4; first electrode 7 and hole transport layer 6; or first electrode 7, hole transport layer 6, and intermediate layer 8 (not shown), to generate electrons or holes. That is, the photoelectric conversion layer 5 generates a current between the first electrode 7 and the second electrode 3. The electron transport layer 4 is a layer disposed between the photoelectric conversion layer 5 and the two electrodes 3 and 7, and in some cases, it is not required. Multiple layers of the electron transport layer 4 and the photoelectric conversion layer 5 can be stacked. This form can also be called a "tandem structure". The components are described below. Furthermore, as... Figure 2 As shown, a photoelectric conversion element can be fabricated in the following order: first electrode 7, hole transport layer 6, photoelectric conversion layer 5, electron transport layer 4, and second electrode 3 on substrate 2. An intermediate layer 8 (not shown) can be formed between the hole transport layer 6 and the photoelectric conversion layer 5.

[0114] [Photoelectric conversion element]

[0115] The photoelectric conversion element of the present invention comprises: a first electrode; a second electrode; and a photoelectric conversion layer disposed between the first electrode and the second electrode, the photoelectric conversion layer comprising a crystal having a perovskite structure, wherein the photoelectric conversion element comprises a hole transport layer comprising a compound represented by formula (1) between the photoelectric conversion layer and the first electrode. Furthermore, to improve photoelectric conversion efficiency, a series configuration in which the photoelectric conversion elements are stacked can be employed. There is no limitation on the type of photoelectric conversion element to be stacked, and for example, in addition to using a perovskite-type solar cell with a perovskite structure crystal in its photoelectric conversion layer, a silicon-type solar cell or a CIGS-type solar cell can be used.

[0116] Methods for forming the photoelectric conversion layers of the photoelectric conversion element of the present invention include, for example, coating methods or vapor deposition methods. Examples of coating methods include dip coating, spin coating, spray coating, inkjet coating, meniscus coating, screen coating, roll coating, die coating, blade coating, curtain coating, and wire rod coating. Coating methods include preparing a coating liquid for each layer (described later), applying the liquid in the desired layer sequence, and drying the liquid. As such a formation method, the desired method can be selected according to each layer.

[0117] The following describes the substrate and each layer.

[0118] [Substrate]

[0119] The photoelectric conversion element 1 of the present invention may include a substrate 2, and examples of such substrates include a transparent glass substrate, a ceramic substrate, and a transparent plastic substrate made of soda-lime glass or alkali-free glass. When light is incident from the side of the first electrode 7, an opaque material may be used as the substrate 2, and when light is incident from the side of the second electrode 3, the substrate 2 is formed of a transparent material.

[0120] [electrode]

[0121] There are no particular restrictions on the materials used for the first electrode 7 or the second electrode 3, and materials known to date can be used. Examples include: metals such as gold, silver, titanium, and copper; sodium; sodium-potassium alloys; lithium; magnesium; carbon; carbon nanotubes; aluminum; magnesium-silver mixtures; magnesium-indium mixtures; aluminum-lithium alloys; Al / Al2O3 mixtures; and Al / LiF mixtures.

[0122] Examples of transparent electrode materials include: conductive transparent materials such as CuI, indium tin oxide (ITO), SnO2, zinc aluminum oxide (AZO), indium zinc oxide (IZO), zinc gallium oxide (GZO), fluorine-doped tin oxide (FTO), and antimony-doped tin oxide (ATO); and conductive transparent polymers. These materials can be used alone or in combination.

[0123] At least one of the first electrode 7 or the second electrode 3 on the light incident side is a transparent electrode, and the other may be a transparent electrode or a reflective layer formed of a light-reflective material, or a transparent electrode including a reflective layer on the side opposite to the light incident side. When the first electrode 7 is on the light incident side, the second electrode 3 and the substrate 2 may be a transparent electrode and a reflective layer, respectively. The transparent electrode may be a patterned electrode.

[0124] [Photoelectric conversion layer]

[0125] The photoelectric conversion element of the present invention includes a photoelectric conversion layer disposed between a first electrode and a second electrode, the photoelectric conversion layer comprising a crystal having a perovskite structure. The photoelectric conversion layer 5 comprises a crystal having a perovskite structure. The perovskite structure crystal used in the present invention is preferably represented by the following general formula [5].

[0126] ABX3 [5]

[0127] In the general formula [5], A represents a monovalent cation of an organic molecule or metal atom, B represents a divalent metal cation, and X represents a monovalent halide anion.

[0128] In the case of, for example, organic molecules, A in general formula [5] preferably represents C. p N q H r ("p", "q", and "r" each represent a positive integer). Specific examples include methylammonium and formamidinium.

[0129] Furthermore, there are no particular restrictions on the metal atoms, but lithium, cesium, sodium, potassium, and rubidium are preferred. These organic molecules or metal atoms can be used alone or in combination.

[0130] When the cation A to be included is too large to be suitable within a crystal with a three-dimensional perovskite structure, a crystal with a two-dimensional perovskite structure, a crystal with a 2.5-dimensional perovskite structure possessing properties of both two-dimensional and three-dimensional perovskite structures, a bilayer crystal with a three-dimensional and two-dimensional perovskite structure, or a crystal with a mixed three-dimensional / two-dimensional perovskite structure is formed, and any of these structures functions as a photoelectric conversion layer. A bilayer crystal with a three-dimensional and two-dimensional perovskite structure refers to a crystal in which crystals with three-dimensional and two-dimensional perovskite structures are stacked as independent and separate layers. A crystal with a mixed three-dimensional / two-dimensional perovskite structure refers to a crystal with a structure in which regions or domains of crystals with two-dimensional or 2.5-dimensional layered structures and three-dimensional perovskite structures are mixed.

[0131] Preferably, a crystal having a two-dimensional perovskite or 2.5-dimensional perovskite structure is represented by each of the following general formulas [6] to [8] ("n" represents a positive integer).

[0132] R'2A n-1 B n X 3n+1 [6]

[0133] R''A n-1 B n X 3n+1 [7]

[0134] R'''A n B n X3n+1 [8]

[0135] Formulas [6], [7] and [8] form perovskite structures of type Ruddlesden-Popper (RP), type Dion-Jacobson (DJ), and type Alternating cations in the interlayer (ACI), respectively.

[0136] In general formulas [6] to [8], R', R'', and R''' each represent an organic molecule or a metal cation that may have substituents. Specifically, ethylammonium, propylammonium, n-butylammonium, n-hexylammonium, n-octylammonium, 1,6-hexammonium, isobutylammonium, 3-(nonafluoro-tert-butoxy)propylamine, 1,3-propanediammonium, 1,5-pentamethylenediamine, octyldiammonium, 2,2-(ethylenedioxy)bis(ethylammonium), 5-aminovaleric acid, 4-tert-butylammonium, N,N'-dimethylethylene-1,2-diammonium, 2,2,3,3,3-pentafluoropropylammonium, guanidinium, propylammonium, propargylamine, alkylammonium, cyclohexylmethylammonium, 4-(aminomethyl)piperidinium, piperidinium, pyrrolidineonium, cyclohexylammonium, 4-fluoro Phenethylammonium, 4-fluorophenylethylammonium, trifluoromethylbenzylammonium, pentafluorobenzylammonium, pentafluorophenylethylammonium, 4-methoxyphenylethylammonium, imidazolium, pyridinium, 3-thiophenemethylammonium, 2-thiopheneethylammonium, 2-thiopheneformamidinium, 2-thiophenemethylammonium, 1-naphthylmethylammonium, 2-naphthylmethylammonium, phenethylammonium, phenylammonium, benzylammonium, 2,5-thiophene dimethylammonium, phenylpropylammonium, 1,4-phenylene dimethylamine, 3-phenyl-2-propen-1-ammonium, phenylbutylammonium, 4-tert-butylbenzylammonium, 3-(aminomethyl)piperidinium, and 4-(aminomethyl)piperidinium are preferred.

[0137] In each of the general formulas [5] to [8], B represents a metal atom, and examples of such atom include lead, tin, bismuth, zinc, titanium, antimony, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, and europium. Among these, lead, tin, and bismuth are preferred from the viewpoint of overlap of electron orbitals. These metal atoms may be used individually or in combination.

[0138] In each of the general formulas [5] to [8], X represents a halogen atom, and examples include chlorine, bromine, and iodine. These halogen atoms can be used alone or in combination. Halogen atoms are preferred because when halogen atoms are introduced into the structure, the crystals with the perovskite structure described above readily become soluble in organic solvents, thus enabling their application in inexpensive printing methods, etc. Furthermore, iodine is more preferred because the band gap of crystals with the perovskite structure narrows.

[0139] Specifically, MAPbI3, FAPbCl3, FAPbI3, and MAPbI are three-dimensional perovskites, two-dimensional perovskites, and mixed three-dimensional / two-dimensional perovskites. x Br 3-x MAPbI x Cl 3-x Cs 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.83 Br 0.17 )3、{Cs x1 (FA x2 MA 1-x2 ) 1-x1} x3 Pb(I x4 Br 1-x4 ) x5 Cs 0.05 FA 0.88 MA 0.07 PbI 2.56 Br 0.44 (FAPbI3) 0.95 (MAPbBr3) 0.05 (FAPbI3) 0.85 (MAPbBr3) 0.15 CsPbI3, CsPbBr3, Cs x (MA) 1-x PbI3, Cs x (FA) 1-x PbI3, MA x (FA) 1-x PbI3, MA 0.17 FA 0.83 Pb(I 0.83 Br 0.17 3. Cs 0.15 FA 0.85 PbI 2.55 Br 0.45 Cs 0.05 FA 0.88 MA 0.07 PbI 2.56 Br 0.44 Cs 0.15 FA 0.85 PbI 2.55 Br 0.45 (PEA)2(MA)2Pb3I 10 (PTA)2(MA)4Pb5I 16 (PEA)2(MA)4Pb5I 16 (ThMA)2(MA)2Pb3I10 (3BBA)2(MA)2Pb3I 10 (ThMA)2(FA)4Pb5I 16 (4FPEA)2(FA) 0.3 MA 0.7 )4Pb5I 16 (PDMA)FA2Pb3I 10 (3AMPY)(MA)3Pb4I 13 (PDMA)MA5Pb6I 19 (PDMA)MA3Pb4I 13 (TTDMA)MA3Pb4I 13 (TTDMA)MA4Pb5I 16 、(BA 0.9 PEA 0.1 )2MA4Pb5I 16 、(BA 0.9 PEA 0.1 )2MA3Pb4I 13 (4FPEA)2MA3Pb4I 13 (4FPEA)2MA4Pb5I 16 (BA)2MA2Pb3I 10 (BA)2MA3Pb4I 13 (TEA)2MA2Pb3I 10 (BA)2MA4Pb5I 16 (BA)2MA3Pb4I 13 CsSnBr3, CsSnI3, FA 0.75 MA 0.25 Sn 0.95 Ge 0.05 I3, FAMASnGeI3, FAMnBr3, FAMnI3, MA2Sn3I8, MASnBr3, MASnGeI3, and MASnI3 are preferred.

[0140] The A, B, or X sites in each of the general formulas [5] to [8] can be adjusted to be insufficient or excessive depending on the purpose, and the combination of x1 to x5 can be changed depending on the purpose. Examples of the combinations of x1 to x5 are shown in Table 2. Particularly preferred ranges for the combinations of x1 to x5 are 0.03 ≤ x1 ≤ 0.10, 0.80 ≤ x2 ≤ 0.96, 0.95 ≤ x3 ≤ 1.05, 0.80 ≤ x4 ≤ 0.96, and 2.95 ≤ x5 ≤ 3.05. MACl can be introduced as a material for forming perovskite crystals.

[0141] [Table 2]

[0142] Table 2

[0143]

[0144] In the specific examples above, "MA" represents methylammonium, "FA" represents formamidinium, "PEA" represents phenylethylammonium, "PTA" represents phenyltriethylammonium, "ThMA" represents 2-thiophenemethylammonium, "3BBA" represents 3-bromobenzylammonium, "3AMPY" represents 3-(aminomethyl)pyridine, "PDMA" represents 1,4-phenylene dimethylammonium, "TTDMA" represents thieno[3,2-b]thiophene-2,5-dimethylammonium, "4FPEA" represents 4-fluorophenylethylammonium, "BA" represents butylammonium, and "TEA" represents 2-thiopheneethylammonium.

[0145] The aforementioned perovskite-structured crystal preferably has a cubic structure in which metal atoms M, organic molecules R, and halogen atoms or chalcogenide atoms are respectively disposed at the body-center, vertices, and face-centers. Details are unclear, but it is envisioned that when such a structure exists, the orientation of the octahedrons in the lattice can be easily changed, thus increasing the electron mobility in the perovskite-structured crystal and improving the photoelectric conversion efficiency of the photoelectric conversion element.

[0146] The crystal with a perovskite structure used in this invention is preferably a crystalline semiconductor. The term "crystalline semiconductor" refers to a semiconductor capable of measuring the X-ray scattering intensity distribution to detect scattering peaks. When the crystal with the perovskite structure is a crystalline semiconductor, the electron mobility in the perovskite-structured crystal increases, and the photoelectric conversion efficiency of the photoelectric conversion element is improved.

[0147] The thickness of the photoelectric conversion layer according to the present invention is preferably 5 to 2,000 nm. When the thickness is 5 nm or more, sufficient light absorption is possible, and when the thickness is 2,000 nm or less, the generated charge can be transported to each electrode. More preferably, the lower limit is 50 nm, more preferably, the upper limit is 1,200 nm, even more preferably, the lower limit is 100 nm, and even more preferably, the upper limit is 1,000 nm.

[0148] [Hollow transport layer]

[0149] The photoelectric conversion element of the present invention includes a hole transport layer 6 between the photoelectric conversion layer and the first electrode 7. The hole transport layer 6 is a layer containing a compound represented by formula (1) as a hole transport material. In the hole transport layer, two or more hole transport materials can be used in combination, or it can be used in combination with any other hole transport material, such as those not belonging to the present invention. In this case, it is preferable to introduce 50 wt% or more of the compound represented by formula (1) as a hole transport material.

[0150] Examples of other cavitation transport materials not included in this invention include spirofluorene compounds, triphenylamine compounds, phenylene compounds, pyrene compounds, phthalocyanine compounds, carbazole compounds, fluorene compounds, phenylcyclohexane compounds, benzidine compounds, phenoxazine compounds, phenylenediamine compounds, thiocyanate compounds, and thiophene compounds.

[0151] [Electron transport layer]

[0152] In the photoelectric conversion element of the present invention, the electron transport layer 4 can be disposed between the second electrode 3 and the photoelectric conversion layer 5, such as... Figure 1 As shown.

[0153] There are no particular limitations on the materials used for electron transport layer 4, and examples include N-type conductive polymers, N-type low molecular weight organic semiconductors, N-type metal oxides, N-type metal sulfides, alkali metal halides, alkali metals, and surfactants. Specific examples include cyano-containing polyphenylene vinylene, boron-containing polymers, bathocuproine, bathophenanthroline, hydroxyquinolinatoaluminum, oxadiazole compounds, benzimidazole compounds, naphthalenetetracarboxylic acid compounds, fullerene compounds, perylene derivatives, phosphine oxide compounds, phosphine sulfide compounds, fluorine-containing phthalocyanines, titanium dioxide, zinc oxide, indium oxide, tin oxide, gallium oxide, tin sulfide, indium sulfide, and zinc sulfide.

[0154] The preferred lower limit for the thickness of the electron transport layer 4 is 1 nm, and its preferred upper limit is 2,000 nm. When the thickness is above 1 nm, holes can be sufficiently blocked, and when the thickness is below 2,000 nm, the electron transport layer 4 is less likely to become a resistor during electron transport, thus improving photoelectric conversion efficiency. A more preferred lower limit for the thickness is 3 nm, its more preferred upper limit is 1,000 nm, its even more preferred lower limit is 5 nm, and its even more preferred upper limit is 500 nm.

[0155] [Middle Layer]

[0156] For purposes such as reducing the bandgap that may hinder charge transfer or suppressing interlayer migration, the photoelectric conversion element 1 may include one or more intermediate layers 8. The intermediate layers comprise any of inorganic or organic compounds. Examples of inorganic compounds include Al compounds, Mo compounds, Ni compounds, Ti compounds, Sn compounds, and Zn compounds. Examples of organic compounds include fullerene compounds, phthalocyanine compounds, spirofluorene compounds, triphenylamine compounds, hydroxyl compounds, pyrene compounds, phthalocyanine compounds, carbazole compounds, fluorene compounds, phenylcyclohexane compounds, benzidine compounds, phenoxazine compounds, phenylenediamine compounds, thiocyanate compounds, butyral resins, acrylic resins, polycarbonate resins, polyester resins, polyvinyl alcohol acetal resins, epoxy resins, melamine resins, polyurethane resins, phenolic resins, polyvinylphenol resins, alkyd resins, polyvinyl alcohol resins, polyethylene oxide resins, polypropylene oxide resins, polyamide resins, polyamic acid resins, polyimide resins, polyamide-imide resins, and cellulose resins. Phthalocyanine compounds are preferred because of their satisfactory compatibility with the compounds of the present invention represented by general formula (1).

[0157] The thickness of the intermediate layer is preferably 5 to 800 nm. When the thickness is 5 nm or more, a suppression effect on interlayer migration can be expected, and when the thickness is 800 nm or less, charge can be easily and satisfactorily transported to each electrode. The thickness is more preferably 40 to 600 nm, and even more preferably 40 to 400 nm. In addition, the intermediate layer can be expected to have a reduction effect on band gaps and the like, which may hinder interlayer charge transfer.

[0158] <Application Example>

[0159] Applications of the present invention relate to photoelectric conversion devices, mobile bodies, and building materials.

[0160] Photoelectric conversion device

[0161] The photoelectric conversion device of the present invention includes the photoelectric conversion element of the present invention. The photoelectric conversion device can be formed by using multiple photoelectric conversion elements of the present invention. When multiple photoelectric conversion elements are connected, such a photoelectric conversion device can also be called a "photoelectric conversion unit" or a "photoelectric conversion module". In the photoelectric conversion element, elements with different absorption wavelengths can be stacked to increase the output voltage. Furthermore, the photoelectric conversion device includes the photoelectric conversion element of the present invention and an inverter. The inverter can be a converter for converting DC voltage to AC voltage.

[0162] Photoelectric conversion devices may include an energy storage unit connected to the photoelectric conversion element. There are no limitations on the energy storage unit as long as it can store electricity. Examples include secondary batteries using lithium ions, all-solid-state batteries, and double-layer capacitors. To impart functions such as maintaining or increasing the amount of incident light, a surface layer that is difficult for water or dirt to adhere to can be added, or functions that collect or guide light can be added.

[0163] [Moving Object]

[0164] The mobile body of the present invention includes the photoelectric conversion element of the present invention. Figure 3 This is a perspective view schematically illustrating a moving body including a photoelectric conversion element according to one embodiment of the present invention. The moving body 30 includes a photoelectric conversion element 31 and a body 32 including the photoelectric conversion element 31. The photoelectric conversion element of the present invention is applicable to the photoelectric conversion element 31. The photoelectric conversion element 31 is disposed at a position on the body 32 where it can receive external light. When the moving body 30 is a vehicle, the photoelectric conversion element 31 may be disposed on the roof. The electrical energy obtained by the photoelectric conversion element 31 can be used as the power source for the moving body 30 or for any other electrical equipment. The electrical energy generated by the power source of the moving body 30 can be used to power the photoelectric conversion element 31. When the moving body 30 is a vehicle, the frictional energy generated by the brakes can be converted into electrical energy for the control of the photoelectric conversion element 31.

[0165] The mobile body 30 can be, for example, a car, motorcycle, railway vehicle, ship, or flying body including artificial satellites, airplanes, and drones. There are no particular restrictions on the composition of the body 32 of the mobile body 30, but it is preferably formed of a material with high strength.

[0166] [Building Materials]

[0167] The building materials of this invention include the photoelectric conversion element of this invention. Figure 4 This is a perspective view schematically illustrating a building material including a photoelectric conversion element according to one embodiment of the invention. Building material 40 may be the roof of a building. Building material 40 of this embodiment includes a photoelectric conversion element 41, a protective member 42 for protecting the photoelectric conversion element 41, a heat dissipation member 43, and exteriors 44a and 44b. The photoelectric conversion element of the present invention is applicable to photoelectric conversion element 41.

[0168] The building material 40 of the present invention may include a heat dissipation member 43 with a thermal conductivity higher than that of the photoelectric conversion element 41. When the building material 40 is used in the roof or the like, the temperature of the photoelectric conversion element 41 may rise due to sunlight, and thus the photoelectric conversion efficiency may decrease. By using the heat dissipation member 43, the decrease in photoelectric conversion efficiency can be suppressed. Examples of heat dissipation members 43 include metals, alloys, liquid metals, and liquid resins.

[0169] Furthermore, the building material 40 of the present invention may include exterior finishes 44a and 44b. Exterior finishes 44a and 44b may display different colors, or they may display the same color. Exterior finishes 44a and 44b may be formed from the same components, or they may be formed from different components. Paint or a transparent substrate may be used for each exterior finish. Exterior finishes with low light absorption and high heat shielding are preferred.

[0170] In addition to the above-mentioned application examples, the following application examples can be given: portable devices, such as calculators, sensors, and small solar panels; wearable devices, such as glasses-type terminals, watch-type terminals, and portable medical machines; sheet structures supported by multiple frames, such as tents, plastic houses, and truck loading platforms; and structures used by fixing, such as road panels, floating panels, building materials utilizing substrate flexibility, wall-type building materials, glass-type building materials, and large solar panels.

[0171] [Manufacturing Method of Photoelectric Conversion Components]

[0172] The method for manufacturing the photoelectric conversion element of the present invention includes the following steps: a step of forming a first electrode; a step of forming a second electrode; and a step of forming a photoelectric conversion layer comprising a crystal having a perovskite structure between the first electrode and the second electrode.

[0173] The following describes each step of the manufacturing process.

[0174] [The process of forming the first electrode and the process of forming the second electrode]

[0175] The method for manufacturing the photoelectric conversion element of the present invention includes the following steps: a step of forming a first electrode; and a step of forming a second electrode. In the steps of forming the first electrode and forming the second electrode, appropriate methods can be selected according to the materials of the first electrode and the second electrode, respectively. Examples of such methods include, but are not limited to, sputtering, vacuum phase deposition, chemical vapor deposition (CVD), and spray pyrolysis deposition (SPD). The materials of the first electrode and the second electrode are as described above. When one or both of the first electrode and the second electrode are transparent electrodes, the thickness of each transparent electrode is preferably 0.03 to 3 μm.

[0176] When manufacturing solar cells, machining processes can be performed between steps to form circuits. Examples of machining processes include mechanical patterning and laser patterning.

[0177] [Modular Process]

[0178] The element formed up to the electrode can be sealed. Sealing methods include, for example, sealing with resin or sealing with a membrane. Examples of materials used for sealing include silazane, silicone rubber, resins each having a siloxane backbone, and glass.

[0179] Furthermore, from the viewpoint of suppressing adhesion between components that occurs during winding in a roll-to-roll system, a hairline treatment can be applied to the surface of the sealing element.

[0180] [Process for forming the photoelectric conversion layer]

[0181] The process of forming the photoelectric conversion layer may include applying a liquid containing a material comprising the photoelectric conversion layer as described above. Examples of application methods include spin coating, blade coating, slot die coating, screen printing, bar coating, casting, printing transfer, dip-coating, inkjet printing, spraying, and vacuum phase deposition. The appropriate method is selected based on the characteristics of the photoelectric conversion layer to be manufactured, such as thickness control and orientation control.

[0182] To remove the solvent or dispersion medium from the liquid containing the applied photoelectric conversion layer, annealing can be performed under reduced pressure or in an inactive atmosphere (nitrogen or argon). The annealing temperature is preferably 40 to 300°C, more preferably 50 to 150°C. Annealing is preferred because the materials used to form the layers may interpenetrate at the interfaces between the stacked layers, increasing the contact area and thus increasing the short-circuit current.

[0183] [The process of forming the intermediate layer]

[0184] The manufacturing method of the photoelectric conversion element of the present invention may include a step of forming an intermediate layer between the photoelectric conversion layer and the first electrode.

[0185] Examples of processes for forming an intermediate layer include: a method comprising disposing charge-transporting particles on the surface of a photoelectric conversion layer, then coating and drying a resin solution in which an insulating resin is dissolved; a method comprising coating a resin solution in which an insulating resin is dissolved on the surface of a photoelectric conversion layer, then disposing charge-transporting particles thereon, and then drying the resin solution; and a method comprising coating a solution obtained by dispersing charge-transporting particles in a resin solution in which an insulating resin is dissolved onto the surface of a photoelectric conversion layer, and drying the coated solution.

[0186] [Example]

[0187] The present invention is described in detail below with reference to the accompanying drawings and embodiments. However, the present invention is not limited to the following embodiments. The identification of the compounds obtained in the synthetic embodiments is as follows: 1H-NMR measurements were performed (equipment: AVANCE 3-500, manufactured by BRUKER).

[0188] (Synthetic Example 1) Synthesis of Compound (A-8)

[0189] 2,7-Dibromofluorenone (1.69 g, manufactured by Tokyo Chemical Industry Co., Ltd.), 4-methoxy-4'-methyldiphenylamine (2.16 g, manufactured by Tokyo Chemical Industry Co., Ltd.), and toluene (100 mL) were added to a reaction vessel and degassed for 30 minutes. Xphos (0.21 g, manufactured by Sigma-Aldrich Co. LLC), tris(dibenzylacetone)dipalladium(O) (0.28 g, manufactured by Tokyo Chemical Industry Co., Ltd.), and sodium tert-butoxide (1.40 g, manufactured by Tokyo Chemical Industry Co., Ltd.) were added to the reaction vessel, and the mixture was stirred under nitrogen atmosphere with heating and reflux for 24 hours. After the reaction was complete, the mixture was filtered with ethyl acetate using activated clay. The filtrate was concentrated, and the crude product was purified by silica gel column chromatography (hexane:ethyl acetate = 7:1) to provide the compound represented by formula (A-8) as a blackish-purple powder (yield: 1.79 g, yield: 59%). 1 The identification results of the obtained compound represented by the following formula (A-8) by H-NMR measurement are shown below. 1 H-NMR (500MHz, CDCl3): δ (ppm) = 7.14 (2H), 7.08 (2H), 6.98 (4H), 6.96 (4H), 6.93 (2H), 6.88 (8H), 6.76 (8H), 3.73 (6H), 2.24 (6H).

[0190] [Chemistry 21]

[0191]

[0192] (Synthesis Example 2) Synthesis of compound (B-1) used in comparative examples

[0193] 2,7-Dibromofluorenone (1.69 g, manufactured by Tokyo Chemical Industry Co., Ltd.), bis-(4-methoxyphenyl)-[4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-phenyl]-amine (3.34 g, manufactured by Tokyo Chemical Industry Co., Ltd.), toluene (28 mL), ethanol (9.5 mL), and water (9.0 mL) were added to a reaction vessel and degassed for 30 minutes. Tetra(triphenylphosphine)palladium(0) (0.24 g, manufactured by Tokyo Chemical Industry Co., Ltd.) and potassium carbonate (1.83 g, manufactured by Nippon Soda Co., Ltd.) were added to a reaction vessel, and the mixture was stirred at 100 °C for 24 hours under a nitrogen atmosphere. After the reaction was complete, the mixture was extracted with ethyl acetate, washed with a saturated aqueous sodium chloride solution, and then dried over sodium sulfate. After concentration, the crude product was purified by silica gel column chromatography (hexane:ethyl acetate = 7:1) to provide the compound represented by formula (B-1) as a blackish-purple powder (yield: 1.97 g, 50%). 1 The identification results of the compound obtained by H-NMR measurement, represented by the following formula (B-1), are shown below. 1 H-NMR (500MHz, CDCl3): δ (ppm) = 7.79 (2H), 7.60 (2H), 7.45 (2H), 7.37 (4H), 7.03 (8H), 6.91 (4H), 6.79 (8H), 3.74 (12H).

[0194] [Chemistry 22]

[0195]

[0196] (Synthetic Example 3) Synthesis of compound (B-2) used in comparative examples

[0197] 2,7-Dibromofluorenone (1.70 g, manufactured by Tokyo Chemical Industry Co., Ltd.), 4,4'-dimethoxydiphenylamine (2.35 g, manufactured by Nard Institute, Ltd.), and toluene (100 mL) were added to a reaction vessel and degassed for 30 minutes. 1,1'-bis(diphenylphosphine)ferrocene (0.17 g, manufactured by Sigma-Aldrich Co. LLC), palladium acetate (0) (0.048 g, manufactured by Tokyo Chemical Industry Co., Ltd.), and cesium carbonate (4.90 g, manufactured by Tokyo Chemical Industry Co., Ltd.) were added to the reaction vessel, and the mixture was stirred under nitrogen atmosphere with heating and reflux for 24 hours. After the reaction was complete, the mixture was filtered with ethyl acetate using activated clay. The filtrate was concentrated, and the crude product was purified by silica gel column chromatography (hexane:ethyl acetate = 4:1) to provide the compound represented by formula (B-2) as a blackish-purple powder (yield: 1.44 g, yield: 45%). 1 The identification results of the compound obtained by H-NMR measurement, represented by the following formula (B-2), are shown below. 1 H-NMR (500MHz, CDCl3): δ (ppm) = 7.17 (2H), 7.13 (2H), 7.02 (8H), 6.94 (2H), 6.83 (8H), 3.80 (12H).

[0198] [Chemistry 23]

[0199]

[0200] The invention is described in more detail below with reference to embodiments and comparative examples. The invention is by no means limited to the following embodiments without departing from its spirit. In the description of the following embodiments, unless otherwise stated, the term "parts" refers to a quantity by weight.

[0201] <Manufacturing of Particle 1>

[0202] Process (1)

[0203] Under a nitrogen atmosphere, 5.46 parts of phthalonitrile and 45 parts of α-chloronaphthalene were added to a reactor. The mixture was then heated to 30°C and maintained at that temperature. Next, 3.75 parts of gallium trichloride were added to the reactor at this temperature (30°C). The water concentration of the mixture at the time of addition was 150 ppm. The temperature of the mixture was then raised to 200°C. The mixture was then reacted at 200°C for 4.5 hours under a nitrogen atmosphere, followed by cooling. The product was filtered when the temperature reached 150°C. The resulting filter residue was dispersed and washed with N,N-dimethylformamide at 140°C for 2 hours, followed by filtration. The resulting filter residue was washed with methanol and then dried to provide gallium chlorophthalocyanine particles in a 71% yield.

[0204] Process (2)

[0205] 4.65 parts of gallium chlorophthalocyanine particles were dissolved in 139.5 parts of concentrated sulfuric acid at 10°C, and the solution was added dropwise to 620 parts of ice water with stirring, causing the particles to precipitate again. The solution was then filtered under reduced pressure using a filter press. A No. 5C filter (manufactured by Advantec Toyo Kaisha, Ltd.) was used as the filter. The resulting wet filter cake (filter residue) was dispersed and washed with 2% ammonia for 30 minutes, and then filtered again using a filter press. Next, the resulting wet filter cake (filter residue) was dispersed and washed with deionized water, and then filtered three times using a filter press. Finally, the filter residue was freeze-dried to provide hydroxy gallium phthalocyanine particles (hydrated hydroxy gallium phthalocyanine particles) with a solid content of 23% by mass, yielding 71%. The hydroxy gallium phthalocyanine particles were dried using an ultra-drying dryer (trade name: HD-06R, frequency (oscillation frequency): 2,455MHz ± 15MHz, manufactured by Biocon (Japan) Ltd.). Thus, hydroxy gallium phthalocyanine particles (crystals) with a water content of less than 1.0% by mass were obtained.

[0206] Process (3)

[0207] Five parts of hydroxygallium phthalocyanine particles were dispersed for 6 hours in a sand mill (TSG-1 / 4G-4U, manufactured by Igarashi Machine Production Co., Ltd. (now AIMEX Co., Ltd.), with a disc diameter of 70 mm and a number of discs of 5) containing 5 parts of N-methylformamide solvent and 5 parts of glass beads, then filtered and dried to provide particle 1.

[0208] <Preparation of Resin Solution 1>

[0209] 1.0 g of polyvinyl butyral (trade name: BM-2, manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 19 g of 2-propanol by stirring for 24 hours to provide resin solution 1.

[0210] (Example 1)

[0211] [Formation of the electron transport layer]

[0212] Clean the glass substrate with ITO, apply tin oxide (II) adjusted to 3% by mass on it by spin coating, and then heat at 150°C for 30 minutes to form an electron transport layer as a thin film with a thickness of 15 nm.

[0213] [Formation of the photoelectric conversion layer]

[0214] 0.41 g of formamidinium iodide, 1.2 g of lead iodide, 0.05 g of methylammonium bromide, and 0.17 g of lead bromide were dissolved in 1.67 g of N,N-dimethylformamide and 0.49 g of dimethyl sulfoxide, and the mixture was stirred at 70 °C for 24 hours. Then, a cesium iodide solution containing 0.035 g of cesium iodide dissolved in 0.1 g of dimethyl sulfoxide was added to the mixture to prepare the photoelectric conversion layer coating solution. The coating solution was then spin-coated onto the electron transport layer to form a Cs... 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.83 Br 0.17 )3 A photoelectric conversion layer with a thickness of 500nm is formed.

[0215] [Introduction of the hole transport layer]

[0216] 0.075 g of compound (A-8) obtained in Synthesis Example 1, used as a hole transport material, was dissolved in 1.1 g of chlorobenzene to prepare a hole transport material solution. The solution was then spin-coated onto the aforementioned photoelectric conversion layer to form a hole transport layer with a thickness of 300 nm.

[0217] [Formation of the first electrode]

[0218] A hole transport layer with a thickness of 80 nm and an area of ​​0.09 cm² was formed on the hole transport layer using vacuum phase deposition. 2 A gold electrode is used to form the first electrode. Thus, a photoelectric conversion element is obtained.

[0219] [Thickness Analysis]

[0220] After cutting the photoelectric conversion element and fixing the sample onto the tilted sample stage, the thickness was determined using a cross-sectional SEM (equipment: SmartSEM manufactured by Carl Zeiss Co., Ltd.).

[0221] (Example 2)

[0222] The photoelectric conversion element was obtained in the same manner as in Example 1, except that compound (A-12) was used in the hole transport layer.

[0223] (Example 3)

[0224] The photoelectric conversion element was obtained in the same manner as in Example 1, except that compound (A-14) was used in the hole transport layer.

[0225] (Example 4)

[0226] The photoelectric conversion element was obtained in the same manner as in Example 1, except that compound (A-16) was used in the hole transport layer.

[0227] (Example 5)

[0228] The photoelectric conversion element was obtained in the same manner as in Example 1, except that compound (A-23) was used in the hole transport layer.

[0229] (Example 6)

[0230] The photoelectric conversion element is obtained in the same manner as in Example 1, except that the intermediate layer described below is disposed between the photoelectric conversion layer and the hole transport layer.

[0231] [Formation of the intermediate layer]

[0232] 0.1 g of particle 1, 0.01 g of calixarene compound (Japanese Patent Application Laid-Open No. 2003-207913), 10.6 g of 2-propanol, and 11 g of zirconium oxide beads were added, and the material was dispersed for 6 hours using a paint shaker (manufactured by Toyo Seiki Seisaku-sho, Ltd.). Then, 0.2 g of resin solution 1 was added, and the material was again dispersed for 6 hours using a paint shaker to prepare a charge transport solution. The charge transport solution was then spin-coated onto the photoelectric conversion layer to form an intermediate layer with a thickness of 150 nm.

[0233] [Analysis of compound amount]

[0234] The electrode surfaces of the photoelectric conversion element are peeled off, exposing the surface of the intermediate layer. The surface of the intermediate layer is then wiped with a cotton swab containing solvent, dissolved in deuterated sulfuric acid, and then... 1¹H-NMR measurements (equipment: AVANCE 3-500, manufactured by BRUKER). Furthermore, the presence of compounds was confirmed by mass and structural analysis of the stripped components using GPC and MALDI-TOF-MS, IR, and gas chromatography.

[0235] (Comparative Example 1)

[0236] Except that the compound (B-1) obtained in Synthesis Example 2 was used in the hole transport layer, the photoelectric conversion element was obtained in the same manner as in Example 1.

[0237] (Comparative Example 2)

[0238] Except that the compound (B-2) obtained in Synthesis Example 3 was used in the hole transport layer, the photoelectric conversion element was obtained in the same manner as in Example 1.

[0239] [evaluate]

[0240] The photoelectric conversion elements obtained in each embodiment and comparative example are evaluated as follows.

[0241] (Power generation efficiency evaluation)

[0242] A power supply (Type 236, manufactured by Keithley Instruments) was connected between the electrodes of the photoelectric conversion element, and its photoelectric conversion efficiency was evaluated by using an intensity of 100 mW / cm². 2 The solar simulator (manufactured by Yamashita Denso Corporation) illuminates the element with constant light and measures the resulting current and voltage.

[0243] (Lag evaluation)

[0244] By using PCE for. and PCE rev. The lag index (HI) is calculated from the following equation (9), PCE for. and PCE rev. The value is obtained by evaluating the photoelectric conversion efficiency (PCE) in each voltage application direction using the measurements described above. A smaller HI can be considered to indicate a smaller hysteresis.

[0245] [Number.1]

[0246]

[0247] The results are shown in Table 3.

[0248] [Table 3]

[0249] Table 3

[0250]

[0251] This invention is not limited to the embodiments described above, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, the appended claims are attached to disclose the scope of the invention.

[0252] This application claims priority to Japanese Patent Application No. 2023-216293, filed on December 21, 2023, and Japanese Patent Application No. 2024-086008, filed on May 28, 2024, the entire contents of which are incorporated herein by reference.

[0253] [Explanation of reference numerals in the attached figures]

[0254] 1. Photoelectric conversion element

[0255] 2 substrate

[0256] 3 Second electrode

[0257] 4. Electron transport layer

[0258] 5 Photoelectric conversion layer

[0259] 6 Hole transport layer

[0260] 7 First Electrode

Claims

1. A photoelectric conversion element, comprising: First electrode; Second electrode; and A photoelectric conversion layer is disposed between the first electrode and the second electrode, the photoelectric conversion layer comprising crystals having a perovskite structure. The photoelectric conversion element comprises a hole transport layer between the photoelectric conversion layer and the first electrode, the hole transport layer comprising a compound represented by the following formula (1): [Chemistry 1] ， In equation (1), A represents [Chemistry 2] ， B indicates [Chemistry 3] ， C indicates [Chemistry 4] ， D indicates [Chemistry 5] ， Furthermore, R in A to D 1 To R 20 Each of the following can independently represent a hydrogen atom, a trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms that may have a substituent, a linear or branched alkenyl group having 2 to 20 carbon atoms that may have a substituent, a cycloalkyl group having 3 to 10 carbon atoms that may have a substituent, an alkoxy group having 1 to 20 carbon atoms that may have a substituent, a cycloalkoxy group having 3 to 10 carbon atoms that may have a substituent, an alkylthio or arylthio group having 1 to 18 carbon atoms that may have a substituent, a (di)alkylamino or (di)aryamino group having 1 to 20 carbon atoms that may have a substituent, an aromatic hydrocarbon group having 6 to 36 carbon atoms that may have a substituent, or a heterocyclic group having 5 to 36 cyclic atoms that may have a substituent, and in each formula * indicates a bonding position with formula (1), provided that A and B are different from each other and C and D are different from each other.

2. The photoelectric conversion element according to claim 1, wherein the hole transport layer comprises a compound represented by formula (1), wherein A and B are different from each other, C and D are different from each other, A and C are the same as each other, and B and D are the same as each other.

3. The photoelectric conversion element according to claim 1 or 2, wherein the hole transport layer comprises a compound represented by formula (1), wherein R in A to D of formula (1) 1 To R 20 Each of the following can independently represent a hydrogen atom, a straight-chain or branched alkyl group having 1 to 20 carbon atoms that may have substituents, an alkoxy group having 1 to 20 carbon atoms that may have substituents, a (di)alkylamino or (di)arylamino group having 1 to 20 carbon atoms that may have substituents, or an alkylthio or arylthio group having 1 to 18 carbon atoms that may have substituents.

4. The photoelectric conversion element according to any one of claims 1 to 3, wherein the hole transport layer comprises a compound represented by formula (1), wherein each of A to D in formula (1) has a hydrogen atom at one of the ortho or para positions, a linear or branched alkyl group having 1 to 20 carbon atoms that may have a substituent, an alkoxy group having 1 to 20 carbon atoms that may have a substituent, a (di)alkylamino or (di)arylamino group having 1 to 20 carbon atoms that may have a substituent, or an alkylthio or arylthio group having 1 to 18 carbon atoms that may have a substituent.

5. The photoelectric conversion element according to any one of claims 1 to 4, wherein, In the above formula (1), When the phenyl group in A is unsubstituent, the phenyl group in B has a linear or branched alkyl group having 1 to 20 carbon atoms that may have substituents, an alkoxy group having 1 to 20 carbon atoms that may have substituents, a (di)alkylamino or (di)arylamino group having 1 to 20 carbon atoms that may have substituents, or an alkylthio or arylthio group having 1 to 18 carbon atoms that may have substituents. When the phenyl group in A has a straight-chain or branched alkyl group having 1 to 20 carbon atoms that may have substituents, the phenyl group in B has an alkoxy group having 1 to 20 carbon atoms that may have substituents, a (di)alkylamino or (di)arylamino group having 1 to 20 carbon atoms that may have substituents, or an alkylthio or arylthio group having 1 to 18 carbon atoms that may have substituents. When the phenyl group in A has a linear or branched alkoxy group having 1 to 20 carbon atoms that may have substituents, the phenyl group in B has a (di)alkylamino or (di)arylamino group having 1 to 20 carbon atoms that may have substituents, and When the phenyl group in A has an alkylthio group or an arylthio group having 1 to 18 carbon atoms that may have substituents, the phenyl group in B has a (di)alkylamino group or a (di)aryamino group having 1 to 20 carbon atoms that may have substituents.

6. The photoelectric conversion element according to any one of claims 1 to 5, wherein the compound represented by formula (1) is selected from any one of the following: a compound represented by formula (A-8), a compound represented by formula (A-12), a compound represented by formula (A-14), a compound represented by formula (A-16), and a compound represented by formula (A-23): [Chemistry 6] ， [Chemistry 7] ， [Chemistry 8] ， [Chemistry 9] ， [Chemistry 10] 。 7. The photoelectric conversion element according to any one of claims 1 to 6, further comprising an intermediate layer containing phthalocyanine particles between the hole transport layer and the photoelectric conversion layer.

8. A photoelectric conversion device comprising a photoelectric conversion element according to any one of claims 1 to 7.

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