Photoelectric conversion element and photoelectric conversion device

Abstract

To provide a photoelectric conversion element and a photoelectric conversion device using a compound that exhibits excellent photoelectric conversion efficiency even without dopants as a hole transport material.SOLUTION: A photoelectric conversion element has a first electrode, a second electrode, and a photoelectric conversion layer containing a crystal of a perovskite structure and arranged between the first electrode and the second electrode. Between the photoelectric conversion layer and the first electrode, a hole transport layer including a compound represented by Formula (1) is provided.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] In order to solve the problem of depletion of fossil energy and the environmental problems of the earth caused by the use of fossil energy, research on renewable and clean alternative energy sources such as solar energy, wind power, and hydropower is actively underway. Among them, the interest in solar cells that directly convert sunlight into electrical energy is increasing. Here, a solar cell means a battery that absorbs light energy from sunlight and generates a current-voltage using the photovoltaic effect in which electrons and holes are generated. Currently, n-p diode type silicon (Si) single crystal-based solar cells having a light energy conversion efficiency exceeding 20% are widely known and are actually used for solar power generation. However, these have problems in that they require a high-temperature treatment process and the cost per unit power is high because the price of the material itself is high. Also, from the perspective of silicon resources, there are also problems in supply.

[0003] On one hand, organic solar cells (hereinafter referred to as "organic solar cells") do not require high-temperature treatment processes, can be produced in a so-called roll-to-roll manner on a sheet-like substrate, and are expected to reduce costs. However, for the practical application of organic solar cells, further improvement in power generation efficiency and durability is desired. In particular, perovskite solar cells having perovskite-structured crystals as a photoelectric conversion layer are being developed for practical use of solar cells because of their excellent photoelectric conversion properties. In perovskite solar cells, a hole transport material is often used in the device. The purpose of using a hole transport material is to enhance the function of selectively transporting holes and improve the photoelectric conversion efficiency. As a standard hole transport material, Spiro-OMeTAD, a spirobifluorene-based organic compound, is often used. However, pure Spiro-OMeTAD has relatively low hole mobility and conductivity. Therefore, additives such as lithium bis(trifluoromethane)sulfonimide (LiTFSI) and 4-tert-butylpyridine (4-tert-butyl pyridine; TBP), that is, dopants, are added to improve the above-mentioned electronic properties. However, LiTFSI and TBP have the disadvantages of promoting battery degradation due to their hygroscopicity and volatility, and being easily diffused because they are not covalently bonded to the hole transport material. Therefore, they are not suitable for device manufacturing and also increase costs.

[0004] Therefore, in recent years, the development of hole transport materials to replace Spiro-OMeTAD has been underway. For example, Patent Document 1 discloses a technique for obtaining a photoelectric conversion device that exhibits higher photoelectric conversion efficiency and durability than Spiro-OMeTAD by using a compound represented by the general formula (B-1) as a hole transport material.

Chemical formula

[0005] In addition, Non-Patent Document 1 reports an example of using a compound represented by the formula (B-2) as a hole transport material in dye-sensitized solar cell applications.

Chemical formula

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Non-Patent Documents

[0007]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] According to the studies of the present inventors, the photoelectric conversion element described in Patent Document 1 has not shown high electron characteristics without a dopant, and there is still room for improvement in the conversion efficiency of the photoelectric conversion element described in Non-Patent Document 1. Therefore, an object of the present invention is to provide a photoelectric conversion element and a photoelectric conversion device using a compound that exhibits good photoelectric conversion efficiency even without a dopant as a hole transport material.

Means for Solving the Problems

[0009] The above object is achieved by the following present invention. That is, the photoelectric conversion element according to the present invention is a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a perovskite structure crystal disposed between the first electrode and the second electrode, characterized in that it has a hole transport layer containing a compound represented by the following formula (1) between the photoelectric conversion layer and the first electrode.

Chemical Formula

[0010] According to the present invention, a photoelectric conversion element that exhibits good photoelectric conversion efficiency even without a dopant can be provided. [Brief Description of the Drawings]

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0012] The present invention has the following gist. A photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a perovskite-structured crystal disposed between the first electrode and the second electrode, wherein a hole transport layer containing a compound represented by the following formula (1) is provided between the photoelectric conversion layer and the first electrode.

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0013] As a result of investigations, the present inventors have found that by having the above hole transport layer, a photoelectric conversion device excellent in conversion efficiency can be obtained even without a dopant. Although the details are not clear regarding the reason why a higher conversion efficiency can be obtained than when using a known compound in the present invention, it is considered as follows. When a DAD (donor·acceptor·donor) type organic low molecule having a fluorenone structure in the acceptor part is used as the hole transport material, it is presumed that high photoelectric conversion efficiency can be obtained even without a dopant from the viewpoints of an increase in carrier density, energy matching with the lower layer, and passivation with the perovskite structure crystals contained in the photoelectric conversion layer. Further, an intermediate layer containing phthalocyanine particles may be provided between the photoelectric conversion layer and the hole transport layer containing the organic low molecule as the hole transport material. It is presumed that the DAD type organic low molecule having a fluorenone structure in the acceptor part has excellent compatibility with phthalocyanine particles and improves hysteresis by improving the film adhesion.

[0014] According to the study by the present inventors, in the compound represented by the formula (B-1), which is a DAD-type organic small molecule having a fluorenone structure in the acceptor portion, the nitrogen atom of the diphenylamine in the donor portion is not adjacent to the acceptor portion, and the distribution of HOMO is biased toward the donor portion. For this reason, it is considered that the hole transport ability is low without dopant. Similarly, in the compound represented by the formula (B-2), which is a DAD-type organic small molecule having a fluorenone structure in the acceptor portion, the donor portion has only a methoxy group as a substituent, and therefore it was found that there is room for further bias in electron density.

[0015] Therefore, in the present invention, the photoelectric conversion efficiency can be improved by using a compound represented by the above formula (1), in which A and B are different and C and D are different, as a hole transport material. The inventors presume that the nitrogen atom of diphenylamine in the donor portion is adjacent to the acceptor portion, thereby broadening the HOMO and improving the hole transport ability. In addition, the HOMO level of the entire molecule becomes shallower, improving the donor property. Furthermore, they presume that the introduction of different substituents into two phenyl groups bonded to the same nitrogen atom strengthens the bias in the electron density of the donor portion and promotes an increase in the carrier density of the entire molecule.

[0016] In the formula (1), in order to spread the HOMO distribution evenly to the left and right and improve the carrier transport efficiency, it is preferable that A and B are different, C and D are different, A and C are the same, and B and D are the same.

[0017] In the present invention, R in A to D 1 ~R 20Since an increase in carrier density is expected due to a strongly donor-like substituent, each independently, a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent, or a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent is preferred.

[0018] In particular, since a bias in electron density is likely to occur in the donor part, the photoelectric conversion efficiency is good when used in a photoelectric conversion element as a hole transport material. Therefore, R 1 、R 2 、R 4 、R 5 、R 6 、R 7 、R 9 、R 10 、R 11 、R 12 、R 14 、R 15 、R 16 、R 17 、R 19 and R 20 are hydrogen atoms, and it is more preferable that R 3 、R 8 、R 13 and R 18 satisfy the following conditions. R 3 and R 13 are hydrogen atoms, when R 8 and R 18 are preferably a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, or an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent. R 3 and R 13 are a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, when R 8and R 18 is preferably an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, or an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent. R 3 and R 13 When is a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent, R 8 and R 18 is preferably a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent. R 3 and R 13 When is an alkylthio group or arylthio group having 1 to 20 carbon atoms which may have a substituent, R 8 and R 18 is preferably a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent.

[0019] Hereinafter, the compound represented by the formula (1), which is a hole transporting material used for the hole transporting layer of the photoelectric conversion element of the present invention, will be specifically described, but the present invention is not limited thereto.

[0020] In A to D in the formula (1), R 1 ~R 20Each independently represents a hydrogen atom, a trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent, an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent, a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, an aromatic hydrocarbon group having 6 to 36 carbon atoms having a substituent, or a heterocyclic group having 5 to 36 ring-forming atoms which may have a substituent.

[0021] R 1 ~R 20 Examples of the "linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent" represented by R 1 ~R 20 include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, an n-pentyl group, an isopentyl group, an n-hexyl group, a 2-ethylhexyl group, a heptyl group, an octyl group, an isooctyl group, a nonyl group, and a decyl group.

[0022] R 1 ~R 20 Examples of the "linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent" represented by R 1 ~R 20 include a vinyl group, a 1-propenyl group, an allyl group, a 1-methylethenyl group, a 1-butenyl group, a 2-butenyl group, a 1-pentenyl group, a 1-hexenyl group, a 2-methyl-1-propenyl group, a 2-methyl-2-propenyl group, and a 1-ethylethenyl group, and linear or branched alkenyl groups having 2 to 20 carbon atoms in which a plurality of these alkenyl groups are bonded.

[0023] R 1 ~R20 Examples of the "cycloalkyl group having 3 to 10 carbon atoms which may have a substituent" represented by [chemical formula] include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecyl group, a cyclododecyl group, a 4-methylcyclohexyl group, and a 4-ethylcyclohexyl group.

[0024] R 1 ~R 20 Examples of the "alkoxy group having 1 to 20 carbon atoms which may have a substituent" represented by [chemical formula] include a methoxy group, an ethoxy group, a propoxy group, an n-butoxy group, an n-pentyloxy group, an n-hexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, a decyloxy group, an isopropoxy group, an isobutoxy group, an s-butoxy group, a t-butoxy group, an isooctyloxy group, a t-octyloxy group, a phenoxy group, a tolyloxy group, a biphenylyloxy group, a terphenylyloxy group, a naphthyloxy group, an anthryloxy group, a phenanthryloxy group, a fluorenyloxy group, and an indenyl oxy group.

[0025] R 1 ~R 20 Examples of the "cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent" represented by [chemical formula] include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, a cyclohexyloxy group, and a 4-methylcyclohexyloxy group.

[0026] R 1 ~R 20 Examples of the "alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent" represented by [chemical formula] include a methylthio group, an ethylthio group, a propylthio group, a phenylthio group, and a biphenylthio group.

[0027] R 1 ~R 20 In the "(di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent" represented by, examples of the "(di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms" include an ethylamino group and a phenylamino group as a monosubstituted amino group, and a diethylamino group and a diphenylamino group as a disubstituted amino group. In addition to the above-mentioned amino groups, an acetylamino group, an acetylphenylamino group, etc. may be selected.

[0028] R 1 ~R 20 Examples of the "aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent" represented by include a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a biphenyl group, an anthracenyl group (anthryl group), a phenanthryl group, a fluorenyl group, an indenyl group, a pyrenyl group, a perylenyl group, a fluoranthenyl group, and a triphenylenyl group. In the present invention, the aromatic hydrocarbon group includes a "condensed polycyclic aromatic group".

[0029] R 1 ~R 20 Examples of the "heterocyclic group having 5 to 36 ring-forming atoms which may have a substituent" represented by include a pyridyl group, a pyrimidinyl group, a triazinyl group, a morpholino group, a thienyl group, a furyl group (furanyl group), a pyrrolyl group, an imidazolyl group, a pyrazolyl group, a triazolyl group, a quinolyl group, an isoquinolyl group, a naphthyridinyl group, an acridinyl group, a phenanthrolinyl group, a benzofuranyl group, a benzothienyl group, an oxazolyl group, an indolyl group, a carbazolyl group, a benzoxazolyl group, a thiazolyl group, a benzothiazolyl group, a quinoxalinyl group, a benzimidazolyl group, a pyrazolyl group, a dibenzofuranyl group, and a dibenzothienyl group.

[0030] R1 ~R 20The "substituent" in the "linear or branched alkyl group having 1 to 18 carbon atoms which may have a substituent", "linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent", "cycloalkyl group having 3 to 10 carbon atoms which may have a substituent", "alkoxy group having 1 to 20 carbon atoms which may have a substituent", "cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent", "acyl group having 1 to 20 carbon atoms which may have a substituent", "alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent", "(di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent", "aromatic hydrocarbon group having 6 to 36 carbon atoms having a substituent", or "heterocyclic group having 5 to 36 ring-forming atoms which may have a substituent" includes a trimethylsilyl group; linear or branched alkyl groups having 1 to 18 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, an n-pentyl group, an isopentyl group, an n-hexyl group, a 2-ethylhexyl group, a heptyl group, an octyl group, an isooctyl group, a nonyl group and a decyl group; linear or branched alkenyl groups having 2 to 18 carbon atoms such as an ethenyl group (vinyl group), a 1-propenyl group, a 2-propenyl group (allyl group), a 1-butenyl group, a 2-butenyl group, a 1-pentenyl group, a 1-hexenyl group, a 2-methyl-1-propenyl group, a 2-methyl-2-propenyl group and a 1-ethyl ethenyl group; alkoxy groups having 1 to 18 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, a t-butoxy group, a pentyloxy group and a hexyloxy group; aromatic hydrocarbon groups having 6 to 30 carbon atoms such as a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group and a pyrenyl group;Heterocyclic groups having 5 to 30 ring-forming atoms such as pyridyl group, pyrimidinyl group, triazinyl group, thienyl group, furyl group (furanyl group), pyrrolyl group, imidazolyl group, pyrazolyl group, triazolyl group, quinolyl group, isoquinolyl group, naphthyldinyl group, acridinyl group, phenanthrolinyl group, benzofuranyl group, benzothienyl group, oxazolyl group, indolyl group, carbazolyl group, benzoxazolyl group, thiazolyl group, benzothiazolyl group, quinoxalinyl group, benzimidazolyl group, pyrazolyl group, dibenzofuranyl group, dibenzothienyl group; monosubstituted amino groups such as amino group (-NH2), ethylamino group, acetylamino group and phenylamino group, and disubstituted amino groups such as diethylamino group, diphenylamino group and acetylphenylamino group; thiol group: -SH, methylthio group, ethylthio group, propylthio group, phenylthio group and biphenylthio group, etc. can be mentioned. These "substituents" may be contained in plural, and when contained in plural, they may be the same or different from each other. Further, these "substituents" may further have the substituents exemplified above.;

[0031] Furthermore, in the formula (1), it is preferable that A to D have one of a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, or a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, or an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent, at one position of the ortho position or the para position.;

[0032] Specific examples of the compound represented by the formula (1) of the present invention are shown in Table 1, but the present invention is not limited thereto. In Table 1, A to D represent A to D in the formula (1), and the substituent description item represents the substituent on the phenyl group. Also, in Table 1, "without substituent", and further, among R 1 ~R 20 those not described in the table are hydrogen atoms.;

[0033]

Table 1

[0034] In the present invention, it is more preferable that the compound represented by the formula (1) is any one of the compounds represented by the following formulas (A-8), (A-12), (A-14), (A-16), and (A-23).

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0035] The compound represented by the formula (1) can be synthesized by a known method. For example, it can be synthesized by a backward Hartwig cross-coupling reaction between 2,7-dibromofluorenone represented by the following formula (2) and amine compounds represented by the following general formulas (3) and (4).

Chemical formula

Chemical formula

Chemical formula

[0036] As a method for purifying the compound represented by the formula (1), purification by column chromatography, adsorption purification using silica gel, activated carbon, activated clay, etc., purification by recrystallization or crystallization using a solvent, etc. can be mentioned. Alternatively, it is effective to use a compound with increased purity by using these methods in combination. In addition, these compounds can be identified by nuclear magnetic resonance analysis (NMR).

[0037] Hereinafter, the present invention will be described in detail with reference to preferred embodiments. The present invention is not limited to the following embodiments, and those obtained by appropriately changing or improving the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the gist of the present invention are also included in the scope of the present invention. In addition, in this specification, the "layer" means not only a layer having a clear boundary or a flat thin film-like layer, but also a layer having a concentration gradient in which the contained elements gradually change, or a layer that can form a complex intertwined structure together with other layers. Further, the elemental analysis of the layer can be performed, for example, by performing TOF-SIMS / FE-TEM / EDS line analysis measurement on the cross-section of the photoelectric conversion element to confirm the elemental distribution of specific elements.

[0038] FIG. 1 is a cross-sectional view schematically showing the configuration of an embodiment of the photoelectric conversion element of the present invention. On the substrate 2, a second electrode 3, an electron transport layer 4, a photoelectric conversion layer 5, a hole transport layer 6, and a first electrode 7 are provided. An intermediate layer 8 (not shown in the figure) 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 is a cathode, and a current can be taken out by connecting the first electrode 7 and the second electrode 3 with an external circuit. The photoelectric conversion layer 5 is excited by the light incident through the substrate 2, the second electrode 3, the electron transport layer 4, or the first electrode 7, the hole transport layer 6, or the first electrode 7, the hole transport layer 6, and the intermediate layer 8 not shown in the figure, generating 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, 7, and may not be formed in some cases. The electron transport layer 4 and the photoelectric conversion layer 5 may be stacked in multiple layers. Such a form can also be called a tandem structure. Each member will be described below. Also, as shown in FIG. 2, a photoelectric conversion element may be fabricated on the substrate 2 in the order of the first electrode 7, the hole transport layer 6, the photoelectric conversion layer 5, the electron transport layer 4, and the second electrode 3. An intermediate layer 8 not shown in the figure may be formed between the hole transport layer 6 and the photoelectric conversion layer 5.

[0039] [Photoelectric conversion element] The photoelectric conversion element of the present invention is a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a perovskite-structured crystal disposed between the first electrode and the second electrode, wherein a hole transport layer containing the compound represented by the formula (1) is provided between the photoelectric conversion layer and the first electrode. Further, in order to improve the photoelectric conversion efficiency, a tandem type in which photoelectric conversion elements are stacked may be used. The photoelectric conversion elements to be stacked are not limited to the type of photoelectric conversion elements, such as perovskite solar cells using perovskite-structured crystals in the photoelectric conversion layer, silicon solar cells, and CIGS solar cells.

[0040] Examples of the method for forming each layer including the photoelectric conversion layer of the photoelectric conversion element of the present invention include a coating method and a vapor deposition method. Examples of the coating method include dip coating, spin coating, spray coating, inkjet coating, meniscus coating, screen coating, roll coating, die coating, blade coating, curtain coating, and wire bar coating. The coating method is a method of preparing a coating solution for each layer to be described later, coating it in the desired order of the layers, and drying it. These film-forming methods can be selected as desired according to each layer.

[0041] Hereinafter, the substrate and each layer will be described. 〔Substrate〕 The photoelectric conversion element 1 of the present invention may include a substrate 2. For example, a soda-lime glass, a transparent glass substrate of non-alkali glass, a ceramic substrate, or a transparent plastic substrate can be used. When light is taken in from the first electrode 7 side, the substrate 2 can be made of an opaque material. When light is taken in from the second electrode 3 side, the substrate 2 is made of a transparent material.

[0042] 〔Electrode〕 The materials of the first electrode 7 and the second electrode 3 are not particularly limited, and conventionally known materials can be used. For example, metals such as gold, silver, titanium, and copper, sodium, sodium-potassium alloy, lithium, magnesium, carbon, carbon nanotube, aluminum, magnesium-silver mixture, magnesium-indium mixture, aluminum-lithium alloy, Al / Al2O3 mixture, and Al / LiF mixture can be mentioned. As the transparent electrode material, for example, conductive transparent materials such as CuI, ITO (indium tin oxide), SnO2, AZO (aluminum zinc oxide), IZO (indium zinc oxide), GZO (gallium zinc oxide), FTO (fluorine-doped tin oxide), and ATO (antimony-doped tin oxide), and conductive transparent polymers can be mentioned. These materials may be used alone or in combination of two or more. At least one of the electrodes on the light incident side of the first electrode 7 and the second electrode 3 is a transparent electrode, and the other may be a transparent electrode or may also serve as a reflective layer formed of a light-reflective material, or may be a transparent electrode provided with 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 may be used as a transparent electrode, and the substrate 2 may be used as a reflective layer. Note that the transparent electrode may be a patterned electrode.

[0043] 〔Photoelectric conversion layer〕 The photoelectric conversion element of the present invention has a photoelectric conversion layer disposed between the first electrode and the second electrode and containing a perovskite structure crystal. The photoelectric conversion layer 5 has a perovskite structure crystal. The crystal of the perovskite structure used in the present invention is preferably represented by the following general formula [5]. ABX3 [5] In the above general formula [5], A is a monovalent cation of an organic molecule or a metal atom, B is a divalent metal cation, and X is a monovalent halide anion. As A in the above general formula [5], for example, in the case of an organic molecule, it is preferably represented by CpNqHr (where p, q, and r are all positive integers). Specifically, methylammonium and formamidinium can be mentioned. The metal atom is not particularly limited, but lithium, cesium, sodium, potassium, and rubidium are preferred. These organic molecules or metal atoms may be used alone or in combination of two or more.

[0044] When the cation of A constituting it is too large to fit within the crystal of the three-dimensional perovskite structure, a crystal of a two-dimensional perovskite structure, a 2.5-dimensional perovskite structure crystal having both two-dimensional and three-dimensional properties, a two-layer crystal of three-dimensional and two-dimensional perovskite structures, or a crystal of a mixed three-dimensional·two-dimensional perovskite structure is formed, and all of them function as a photoelectric conversion layer. The two-layer crystal of three-dimensional and two-dimensional perovskite means a crystal in which crystals of three-dimensional and two-dimensional perovskite structures are laminated as independent and separate layers, and the mixed three-dimensional·two-dimensional perovskite refers to a crystal having a structure in which both regions or domains of two-dimensional or 2.5-dimensional layered and three-dimensional perovskite structure crystals are mixed.

[0045] The two-dimensional perovskite or the crystal of the 2.5-dimensional perovskite structure is preferably represented by the following general formulas [6] to [8]. (n is a positive integer) R’2A n-1 B n X 3n+1 [6] R’’A n-1 B n X 3n+1 [7] R’’’A n B n X 3n+1 [8]

[0046] Each of the above general formulas forms a perovskite structure where [6] is of the RP (Ruddlesden-Popper) type, [7] is of the DJ (Dion-Jacobson) type, and [8] is of the ACI (Alternating cations in the interlayer) type.

[0047] R’, R’’, and R’’’ in the above general formulas [6] to [8] are cations of organic molecules or metals that may have substituents. Specifically, ethylammonium, propylammonium, n-butylammonium, n-hexylammonium, n-octylammonium, 1,6-hexadiammonium, iso-butylammonium, 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, pyrrolidinium, cyclohexylammonium, 4-fluorophenethylammonium, 4-fluorophenethylammonium, trifluoromethylbenzylammonium, pentafluorobenzylammonium, pentafluorophenylethylammonium, 4-methoxyphenethylammonium, imidazolium, pyridinium, 3-thiophenemethylammonium, 2-thiopheneethylammonium, 2-thiopheneformamidium, 2-thiophenemethylammonium, 1-naphthylmethylammonium, 2-naphthylmethylammonium, phenethylammonium, phenylammonium, benzylammonium, 2,5-thiophenedimethylammonium, phenylpropylammonium, 1,4-phenylenedimethanamine, 3-phenyl-2-propen-1-ammonium, phenylbutylammonium, 4-tert-butyl-benzylammonium, 3-(aminomethyl)piperidinium, 4-(aminomethyl)piperidinium are preferred.

[0048] In the above general formulas [5] to [8], B is a metal atom, for example, lead, tin, bismuth, zinc, titanium, antimony, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, europium. Among them, lead, tin, and bismuth are preferred from the perspective of the overlap of electron orbits. These metal atoms may be used alone or in combination of two or more.

[0049] In the above general formulas [5] to [8], X is a halogen atom, for example, chlorine, bromine, iodine. These halogen atoms may be used alone or in combination of two or more. Among them, since the crystal of the perovskite structure becomes soluble in an organic solvent by containing halogen in the structure and can be applied to an inexpensive printing method, etc., a halogen atom is preferred. Furthermore, iodine is more preferred because the energy band gap of the crystal of the perovskite structure becomes narrow.

[0050] Specifically, the three-dimensional perovskite, two-dimensional perovskite, and mixed three-dimensional / two-dimensional perovskite include MAPbI3, FAPbCl3, FAPbI3, MAPbIxBr 3-x 、MAPbIxCl 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, Csx(MA) 1-x PbI3, Csx(FA) 1-x PbI3, MAx(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)2Pb3I 10 , (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)2MA2Pb3I10 、(BA)2MA4Pb5I 16 、(BA)2MA3Pb4I 13 、CsSnBr3, CsSnI3, FA 0.75 MA 0.25 Sn 0.95 Ge 0.05 I3, FAMASnGeI3, FASnBr3, FASnI3, MA2Sn3I8, MASnBr3, MASnGeI3, MASnI3 are preferred. Depending on the purpose, the A-site, B-site, or X-site in the above general formulas [5] to [8] may be adjusted to be too little or excessive, and the combination of x1 to x5 may be changed according to the purpose. The combination of x1 to x5 is as shown in Table 2, for example. A particularly preferred range of the combination of x1 to x5 is 0.03 ≦ x1 ≦ 0.10, 0.80 ≦ x2 ≦ 0.96, 0.95 ≦ x3 ≦ 1.05, 0.80 ≦ x4 ≦ 0.96, 2.95 ≦ x5 ≦ 3.05. Note that MACl may be included as a material for forming perovskite crystals.

[0051]

Table 2

[0052] In the above specific examples, "MA" represents methylammonium, "FA" represents formamidinium, "PEA" represents phenethylammonium, "PTA" represents phenyltriethylammonium, "ThMA" represents 2-thiophenemethylammonium, "3BBA" represents 3-bromobenzylammonium, "3AMPY" represents 3-(aminomethyl)pyridine, "PDMA" represents 1,4-phenylenedimethaneammonium, "TTDMA" represents thieno[3,2-b]thiophene-2,5-diyl dimethaneammonium, "4FPEA" represents 4-fluorophenethylammonium, "BA" represents butylammonium, and "TEA" represents 2-thiophenethylammonium.

[0053] The crystal of the perovskite structure preferably has a cubic crystal structure in which a metal atom M is at the body center, an organic molecule R is at each vertex, and a halogen atom or chalcogen atom X is at the face center. Although the details are not clear, it is presumed that having such a structure allows the orientation of the octahedrons in the crystal lattice to easily change, resulting in a higher mobility of electrons in the perovskite structure crystal and an improvement in the photoelectric conversion efficiency of the photoelectric conversion element.

[0054] The crystal of the perovskite structure used in the present invention is preferably a crystalline semiconductor. A crystalline semiconductor means a semiconductor in which the X-ray scattering intensity distribution is measured and scattering peaks can be detected. When the perovskite structure crystal is a crystalline semiconductor, the mobility of electrons in the perovskite structure crystal increases, and the photoelectric conversion efficiency of the photoelectric conversion element improves.

[0055] The thickness of the photoelectric conversion layer according to the present invention is preferably 5 nm or more and 2000 nm or less. If the thickness is 5 nm or more, light can be sufficiently absorbed, and if it is 2000 nm or less, the generated charges can be transported to each electrode. A more preferable lower limit is 50 nm, a more preferable upper limit is 1200 nm, an even more preferable lower limit is 100 nm, and an even more preferable upper limit is 1000 nm.

[0056] 〔Hole transport layer〕 In the photoelectric conversion element of the present invention, a hole transport layer 6 is provided between the photoelectric conversion layer and the first electrode 7. The hole transport layer 6 is a layer containing the compound represented by the formula (1) as a hole transport material. Two or more hole transport materials may be used in combination in the hole transport layer, and other hole transport materials not belonging to the present invention may also be used in combination. In that case, it is preferable to contain 50 wt% or more of the compound represented by the formula (1) as a hole transport material. Examples of other hole transporting materials not belonging to the present invention include spirofluorene compounds, triphenylamine compounds, chrysene compounds, pyrene compounds, phthalocyanine compounds, carbazole compounds, fluorene compounds, phenylcyclohexane compounds, benzidine compounds, phenoxazine compounds, phenylenediamine compounds, thiocyanate compounds, and thiophene compounds.

[0057] 〔Electron transport layer〕 In the photoelectric conversion element of the present invention, as shown in FIG. 1, an electron transport layer 4 may be disposed between the second electrode 3 and the photoelectric conversion layer 5. The material of the electron transport layer 4 is not particularly limited, and examples thereof 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. Specifically, for example, cyano group-containing polyphenylene vinylene, boron-containing polymers, bathocuproine, bathophenanthrene, aluminum hydroxyquinolinate, oxadiazole compounds, benzimidazole compounds, naphthalene tetracarboxylic acid compounds, fullerene compounds, perylene derivatives, phosphine oxide compounds, phosphine sulfide compounds, fluorine group-containing phthalocyanine, titanium oxide, zinc oxide, indium oxide, tin oxide, gallium oxide, tin sulfide, indium sulfide, and zinc sulfide. The thickness of the electron transport layer 4 preferably has a lower limit of 1 nm and an upper limit of 2000 nm. If such a thickness is 1 nm or more, holes can be sufficiently blocked, and if it is 2000 nm or less, it is difficult to cause resistance during electron transport, and the photoelectric conversion efficiency is high. A more preferable lower limit of the thickness is 3 nm, and a more preferable upper limit is 1000 nm. A further preferable lower limit is 5 nm, and a further preferable upper limit is 500 nm.

[0058] 〔Intermediate layer〕 The photoelectric conversion element 1 may have one or more intermediate layers 8 for the purpose of reducing an energy gap or the like that hinders charge movement, or suppressing migration between layers. The intermediate layer contains either an inorganic compound or an organic compound. Examples of the inorganic compound include an Al compound, a Mo compound, a Ni compound, a Ti compound, a Sn compound, and a Zn compound. Examples of the organic compound include a fullerene compound, a phthalocyanine compound, a spirofluorene compound, a triphenylamine compound, a chrysene compound, a pyrene compound, a phthalocyanine compound, a carbazole compound, a fluorene compound, a phenylcyclohexane compound, a benzidine compound, a phenoxazine compound, a phenylenediamine compound, a thiocyanate compound, a butyral resin, an acrylic resin, a polycarbonate resin, a polyester resin, a polyvinyl acetal resin, an epoxy resin, a melamine resin, a polyurethane resin, a phenol resin, a polyvinylphenol resin, an alkyd resin, a polyvinyl alcohol resin, a polyethylene oxide resin, a polypropylene oxide resin, a polyamide resin, a polyamic acid resin, a polyimide resin, a polyamideimide resin, and a cellulose resin. Among these, a phthalocyanine compound is preferable because of its good compatibility with the compound represented by the general formula (1) of the present invention. The thickness of the intermediate layer is preferably 5 nm or more and 800 nm or less. If the thickness is 5 nm or more, an effect of suppressing migration between layers can be expected, and if the thickness is 800 nm or less, it is easy to transport charges to each electrode favorably. More preferably, it is 40 nm or more and 600 nm or less, and still more preferably 40 nm or more and 400 nm or less. Further, the intermediate layer can also be expected to have an effect of reducing an energy gap or the like that hinders charge movement between layers.

[0059] <Application Example> The application examples of the present invention relate to a photoelectric conversion device, a moving body, and a building material. [Photoelectric Conversion Device] By using a plurality of the photoelectric conversion elements of the present invention, a photoelectric conversion device can be configured. When a plurality of photoelectric conversion elements are connected, such a photoelectric conversion device can also be referred to as a photoelectric conversion cell or a photoelectric conversion module. The photoelectric conversion elements may be stacked with elements having different absorption wavelengths in order to increase the output voltage. Further, the photoelectric conversion device includes the photoelectric conversion element of the present invention and an inverter. The inverter may be a converter that converts direct current into alternating current. The photoelectric conversion device may have a power storage unit connected to the photoelectric conversion element. The power storage unit is not limited as long as it can store electricity. For example, a secondary battery using lithium ions, an all-solid-state battery, and an electric double layer capacitor can be mentioned. In order to provide functions such as maintaining or increasing the amount of incident light, a surface layer that is not easily soiled with water or dirt, or a function of condensing or guiding light may be added.

[0060] 〔Mobile body〕 FIG. 3 is a perspective view schematically showing an embodiment of a mobile body including the photoelectric conversion element of the present invention. The mobile body 30 includes the photoelectric conversion element 31 of the present invention and a body 32 including the photoelectric conversion element 31. The photoelectric conversion element 31 is disposed at a position where it can receive external light of the body 32. If the mobile body 30 is an automobile, the photoelectric conversion element 31 may be disposed on the roof. The electric energy obtained by the photoelectric conversion element 31 may be used as the power of the mobile body 30 or the power of other electric devices. The electric energy generated from the power of the mobile body 30 may be used as the power of the photoelectric conversion element 31. If the mobile body 30 is an automobile, the frictional energy generated by braking may be converted into electric energy and used for the control of the photoelectric conversion element 31. The mobile body 30 may be, for example, an automobile, a motorcycle, a railway vehicle, a ship, an artificial satellite, an airplane, or a flying body including a drone. The configuration of the body 32 of the mobile body 30 is not particularly limited, but it is preferably made of a material having high strength.

[0061] 〔Building materials〕 FIG. 4 is a perspective view schematically showing an embodiment of a building material provided with the photoelectric conversion element of the present invention. The building material 40 may be a roof of a building. The building material 40 of the present embodiment includes a photoelectric conversion element 41 of the present invention, a protective member 42 for protecting the photoelectric conversion element 41, a heat dissipation member 43, and exteriors 44a and 44b.

[0062] The building material 40 of the present invention may have a heat dissipation member 43 having a higher thermal conductivity than the photoelectric conversion element 41. When used on a roof or the like, the temperature of the photoelectric conversion element 41 may rise due to sunlight, and the photoelectric conversion efficiency may decrease. By using the heat dissipation member 43, a decrease in the photoelectric conversion efficiency can be reduced. Examples of the heat dissipation member 43 include metals, alloys, liquid metals, and liquid resins.

[0063] Further, the building material 40 of the present invention may have exteriors 44a and 44b. The exterior 44a and the exterior 44b may emit different colors or the same color. 44a and 44b may be composed of the same member or different members. As the exterior, paint or a transparent substrate may be used. Those having low light absorption and high heat insulation properties are preferable. In addition to the above application examples, the following application examples can be cited. As a portable device, for example, a calculator, a sensor, a small solar panel. As a wearable device, for example, a glasses-type terminal, a wristwatch-type terminal, a portable medical device. As a sheet structure supported by a plurality of frames, for example, a tent, a greenhouse, a truck bed. As a structure used fixedly, for example, a road surface panel, a floating panel, a building material utilizing the flexibility of a substrate, a wall surface type building material, a glass type building material, a megasolar panel can be cited.

[0064] [Regarding the manufacturing method of the photoelectric conversion element] The method for manufacturing the photoelectric conversion element of the present invention includes a step of forming a first electrode, a step of forming a second electrode, and a step of forming a photoelectric conversion layer containing a perovskite structure crystal between the first electrode and the second electrode. Hereinafter, each step of the manufacturing method will be described.

[0065] [Process of forming the first electrode and process of forming the second electrode] The method for manufacturing a photoelectric conversion element of the present invention includes a process of forming a first electrode and a process of forming a second electrode. In the process of forming the first electrode and the process of forming the second electrode, an appropriate method 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 method, vacuum evaporation method, CVD method (chemical vapor deposition method), SPD method (spray pyrolysis deposition method), etc. 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 the transparent electrode is preferably 0.03 μm or more and 3 μm or less. When manufacturing a solar cell, cutting may be performed for circuit formation between each process. Examples of cutting include mechanical patterning and laser patterning.

[0066] [Module formation process] The element formed up to the electrodes may be sealed. Examples of the sealing method include sealing with resin or sealing with a film. Examples of the material used for sealing include silazane, silicone rubber, resin having a siloxane skeleton, and glass. Also, from the viewpoint of suppressing adhesion between elements that occurs when winding in a roll to roll manner, a hairline treatment may be performed on the surface of the sealed element.

[0067] [Process of forming the photoelectric conversion layer] The process of forming the photoelectric conversion layer may include a process of applying a liquid containing the material of the photoelectric conversion layer described above. Examples of the application method include, but are not limited to, spin coating method, blade coating method, slit die coating method, screen printing method, bar coater method, casting method, printing transfer method, dipping and pulling method, inkjet method, spraying method, vacuum evaporation method, etc. Appropriate selection is made from these according to the characteristics of the photoelectric conversion layer to be fabricated, such as thickness control and orientation control.

[0068] In order to remove the solvent or dispersion medium from the liquid containing the material of the applied photoelectric conversion layer, annealing treatment may be performed under reduced pressure or in an inert atmosphere (nitrogen or argon atmosphere). The temperature of the annealing treatment is preferably 40°C or higher and 300°C or lower, and more preferably 50°C or higher and 150°C or lower. By performing the annealing treatment, at the interface between the laminated layers, the materials constituting each layer may penetrate each other, increasing the contact area and possibly increasing the short-circuit current, which is preferable.

[0069] [Step of forming the intermediate layer] As a method for manufacturing the photoelectric conversion element of the present invention, a step of forming an intermediate layer may be included between the photoelectric conversion layer and the first electrode. Examples of the step of forming the intermediate layer include the following. A method of applying and drying a resin solution in which an insulating resin is dissolved after arranging charge-transporting particles on the surface of the photoelectric conversion layer. Or, a method of arranging charge-transporting particles after applying a resin solution in which an insulating resin is dissolved on the surface of the photoelectric conversion layer, and then drying the resin solution. Or, a method of applying and drying a solution in which charge-transporting particles are dispersed in a resin solution in which an insulating resin is dissolved on the surface of the photoelectric conversion layer.

Examples

[0070] Hereinafter, the present invention will be specifically described with reference to the drawings by way of examples, but the present invention is not limited to the following examples. In addition, the identification of the compounds obtained in the synthesis examples was 1 performed by 1H-NMR measurement (apparatus: AVANCE3-500 manufactured by BRUKER).

[0071] (Synthesis Example 1) Synthesis of Compound (A-8) 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 charged into a reaction vessel, and degassing was performed for 30 minutes. Xphos (0.21 g, manufactured by Sigma-Aldrich), tris(dibenzylideneacetone)dipalladium(0) (0.28 g, manufactured by Tokyo Chemical Industry Co., Ltd.), and sodium t-butoxide (1.40 g, manufactured by Tokyo Chemical Industry Co., Ltd.) were charged, and the mixture was stirred under heating and reflux for 24 hours in a nitrogen atmosphere. After completion of the reaction, filtration was performed 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 obtain the compound represented by the following formula (A-8) as a black-purple powder (yield 1.79 g, yield 59%). The 1 The identification results by 1H-NMR measurement are shown below. 1 1H-NMR (500 MHz, 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). [Chemical formula]

[0072] (Synthesis Example 2) Synthesis of Compound (B-1) Used in Comparative Example 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 charged into a reaction vessel and degassed for 30 minutes. Tetrakis(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, and the mixture was stirred at 100 °C for 24 hours under a nitrogen atmosphere. After completion of the reaction, the mixture was extracted with ethyl acetate, washed with a saturated aqueous sodium chloride solution, and dried over sodium sulfate. After concentration, the crude product was purified by silica gel column chromatography (hexane:ethyl acetate = 7:1) to obtain the compound represented by the following formula (B-1) as a black-purple powder (yield 1.97 g, yield 50%). The 1 The identification results by 1H-NMR measurement are shown below. 1 1H-NMR (500 MHz, 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). [Chemical formula]

[0073] (Synthesis Example 3) Synthesis of the compound (B-2) used in the comparative example 2,7-Dibromofluorenone (1.70 g, manufactured by Tokyo Chemical Industry Co., Ltd.), 4,4'-dimethoxydiphenylamine (2.35 g, manufactured by Nard Institute), and toluene (100 mL) were charged into a reaction vessel, and degassing was performed for 30 minutes. 1,1'-Bis(diphenylphosphino)ferrocene (0.17 g, manufactured by Sigma-Aldrich), palladium(0) acetate (0.048 g, manufactured by Tokyo Chemical Industry Co., Ltd.), and cesium carbonate (4.90 g, manufactured by Tokyo Chemical Industry Co., Ltd.) were charged, and the mixture was stirred under heating under reflux for 24 hours in a nitrogen atmosphere. After completion of the reaction, filtration was performed 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 obtain the compound represented by the following formula (B-2) as a black-purple powder (yield 1.44 g, yield 45%). The 1 The identification results by 1H-NMR measurement are shown below. 1 1H-NMR (500 MHz, CDCl3): δ (ppm) = 7.17 (2H), 7.13 (2H), 7.02 (8H), 6.94 (2H), 6.83 (8H), 3.80 (12H). [Chemical formula]

[0074] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited in any way by the following Examples as long as the gist thereof is not exceeded. In the description of the following Examples, "parts" means parts by mass unless otherwise specified.

[0075] <Preparation of Particle 1> Step (1) Under a nitrogen flow atmosphere, 5.46 parts of ortho-phthalonitrile and 45 parts of α-chloronaphthalene were charged into a reaction kettle, and then heated to raise the temperature to 30°C and maintained at this temperature. Next, 3.75 parts of gallium trichloride were charged at this temperature (30°C). The moisture concentration of the mixed solution at the time of charging was 150 ppm. Then, the temperature was raised to 200°C. Next, under a nitrogen flow atmosphere, after reacting at 200°C for 4.5 hours, it was cooled, and when the temperature reached 150°C, the product was filtered. The obtained filtrate was dispersed and washed at 140°C for 2 hours using N,N-dimethylformamide, and then filtered. The obtained filtrate was washed with methanol and then dried to obtain chlorogallium phthalocyanine particles with a yield of 71%.

[0076] Step (2) 4.65 parts of the chlorogallium phthalocyanine particles were dissolved in 139.5 parts of concentrated sulfuric acid at 10°C, and while stirring, it was dropped into 620 parts of ice water for reprecipitation, and then vacuum filtered using a filter press. At this time, No. 5C (manufactured by Advantec) was used as the filter. The obtained wet cake (filtrate) was dispersed and washed with 2% aqueous ammonia for 30 minutes, and then filtered using a filter press. Next, the obtained wet cake (filtrate) was dispersed and washed with ion-exchanged water, and then the filtration using a filter press was repeated 3 times. Finally, freeze-drying was performed to obtain hydroxygallium phthalocyanine particles (hydrous hydroxygallium phthalocyanine particles) with a solid content of 23% by mass with a yield of 71%. The hydroxygallium phthalocyanine particles were dried using a hyper-dry dryer (product name: HD-06R, frequency (oscillation frequency): 2455 MHz ± 15 MHz, manufactured by Nippon Bio-Con) to obtain hydroxygallium phthalocyanine particles (crystals) with a water content of 1.0% by mass or less.

[0077] Step (3) 5 parts of the hydroxygallium phthalocyanine particles were subjected to a dispersion treatment for 6 hours using a sand mill (TSG-1 / 4G-4U, manufactured by Igarashi Machinery Manufacturing (now Imex), disk diameter 70 mm, number of disks 5) enclosing 5 parts of N-methylformamide solvent and 5 parts of glass beads, and then filtered and dried to obtain Particle 1.

[0078] 〈Preparation of Resin Solution 1〉 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 obtain Resin Solution 1.

[0079] (Example 1) 〔Formation of Electron Transport Layer〕 The glass substrate with an ITO film was cleaned, and 3 mass% of tin (II) oxide adjusted thereon was applied by spin coating and then heated at 150 °C for 30 minutes to form a thin film-like electron transport layer with a thickness of 15 nm.

[0080] 〔Formation of Photoelectric Conversion Layer〕 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 stirred at 70 °C for 24 hours. Then, a cesium iodide solution prepared by dissolving 0.035 g of cesium iodide in 0.1 g of dimethyl sulfoxide was added to prepare a photoelectric conversion layer coating solution. By spin coating this coating solution on the electron transport layer, a photoelectric conversion layer with a thickness of 500 nm composed of Cs5(MA 0.17 FA 0.83 ) 95 Pb(I 0.83 Br 0.17 )3 was formed.

[0081] 〔Introduction of Hole Transport Layer〕 0.075 g of compound (A-8), which is a hole transport material obtained in Synthesis Example 1, was dissolved in 1.1 g of chlorobenzene to prepare a hole transport material solution. By applying this by spin coating method on the above photoelectric conversion layer, a hole transport layer with a thickness of 300 nm was formed.

[0082] 〔Formation of First Electrode〕 On the hole transport layer, a gold electrode with a thickness of 80 nm and an area of 0.09 cm 2 was formed by vacuum evaporation method, and by forming the first electrode, a photoelectric conversion element was obtained.

[0083] 〔Analysis of film thickness〕 The film thickness was confirmed by cross-sectional SEM (equipment: Carl Zeiss Co., Ltd., SmartSEM) after cutting the photoelectric conversion element and fixing it on an inclined sample stage.

[0084] (Example 2) A photoelectric conversion element is obtained in the same manner as in Example 1 except that compound (A-12) is used for the hole transport layer.

[0085] (Example 3) A photoelectric conversion element is obtained in the same manner as in Example 1 except that compound (A-14) is used for the hole transport layer.

[0086] (Example 4) A photoelectric conversion element is obtained in the same manner as in Example 1 except that compound (A-16) is used for the hole transport layer.

[0087] (Example 5) A photoelectric conversion element is obtained in the same manner as in Example 1 except that compound (A-23) is used for the hole transport layer.

[0088] (Example 6) A photoelectric conversion element was obtained in the same manner as in Example 1 except that an intermediate layer described below was provided between the photoelectric conversion layer and the hole transport layer. 〔Formation of intermediate layer〕 0.1 g of the particles 1, 0.01 g of calixarene compound (Japanese Patent Laid-Open No. 2003-207913), 10.6 g of 2-propanol, and 11 g of zirconia beads were sealed and subjected to paint shaker dispersion (manufactured by Toyo Seiki) for 6 hours. Then, 0.2 g of resin solution 1 was added, and paint shaker dispersion was performed again for 6 hours to prepare a charge transport solution. The charge transport solution was spin-coated on the photoelectric conversion layer to form an intermediate layer with a thickness of 150 nm.

[0089] 〔Analysis of compound amount〕 The electrode surface of the photoelectric conversion element was peeled off to expose the surface of the intermediate layer. The surface of this intermediate layer was wiped with a cotton swab dipped in a solvent and dissolved in heavy sulfuric acid, and 1H-NMR measurement (device: AVANCE3-500 manufactured by BRUKER) was performed. In addition, the peeled-off components were subjected to mass and structure analysis by GPC, MALDI-TOF-MS, IR, and gas chromatography to confirm the presence of the compound.

[0090] (Comparative Example 1) A photoelectric conversion element was obtained in the same manner as in Example 1 except that the compound (B-1) obtained in Synthesis Example 2 was used for the hole transport layer.

[0091] (Comparative Example 2) A photoelectric conversion element was obtained in the same manner as in Example 1 except that the compound (B-2) obtained in Synthesis Example 3 was used for the hole transport layer.

[0092] [Evaluation] The following evaluations were performed on the photoelectric conversion elements obtained in each Example and Comparative Example. (Power Generation Efficiency Evaluation) A power supply (model 236 manufactured by KEITHLEY) was connected between the electrodes of the photoelectric conversion element, and a constant light was irradiated using a solar simulator (manufactured by Yamashita Electric Co., Ltd.) with an intensity of 100 mW / cm 2 The photoelectric conversion efficiency was evaluated by measuring the generated current and voltage. (Hysteresis Evaluation) The photoelectric conversion efficiency (PCE) obtained in the above measurement was evaluated for each voltage application direction as PCE for. and PCE rev. Using these, the hysteresis index (HI) was calculated by the following formula (9). The smaller the HI, the smaller the hysteresis. [Equation] The results are shown in Table 3.

[0093] [Table 3]

[0094] The disclosure of this embodiment includes the following configurations. (Configuration 1) A photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a perovskite-structured crystal disposed between the first electrode and the second electrode, The photoelectric conversion element having a hole transport layer containing a compound represented by the following formula (1) between the photoelectric conversion layer and the first electrode. [Chemical formula] (In formula (1), A is [Chemical formula] and B is [Chemical formula] and C is [Chemical formula] and D is [Chemical formula] and R in A to D 1 ~R 20Each independently represents a hydrogen atom, a trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent, an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent, a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, an aromatic hydrocarbon group having 6 to 36 carbon atoms having a substituent, or a heterocyclic group having 5 to 36 ring-forming atoms which may have a substituent. In the formula, * represents the bonding position with formula (1). However, A and B are different, and C and D are different.) (Configuration 2) In the formula (1), the photoelectric conversion element according to Configuration 1, wherein the hole transport layer contains a compound in which A and B are different, C and D are different, A and C are the same, and B and D are the same. (Configuration 3) In A to D of the formula (1), R 1 ~R 20 Each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, or a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent, and the hole transport layer contains the compound, and the photoelectric conversion element according to Configuration 1 or 2. (Configuration 4) In the formula (1), when A to D are each a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, or a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, or an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent, and one of them is located at either the ortho-position or the para-position, the hole transport layer contains a compound, and the photoelectric conversion element according to any one of Configurations 1 to 3. (Configuration 5) In the formula (1), when the phenyl group in A does not contain a substituent, the phenyl group in B has a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, or an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent, when the phenyl group in A has a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, the phenyl group in B has an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, or an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent, when the phenyl group in A has a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent, the phenyl group in B has a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, when the phenyl group in A has an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent, the phenyl group in B has a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, and the photoelectric conversion element according to Configuration 2. (Configuration 6) The photoelectric conversion element according to any one of Configurations 1 to 5, wherein the compound represented by the formula (1) is any one of the compounds represented by the following formulas (A-8), (A-12), (A-14), (A-16), and (A-23).

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Explanation of reference numerals

[0095] 1 Photoelectric conversion element 2 Substrate 3 Second electrode 4 Electron transport layer 5 Photoelectric conversion layer 6 Hole transport layer 7 First electrode

Claims

1. A photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a perovskite-structured crystal disposed between the first electrode and the second electrode, The photoelectric conversion element having a hole transport layer containing a compound represented by the following formula (1) between the photoelectric conversion layer and the first electrode. 【Chemical 1】 (In formula (1), A is [Chemical Formula 2] whereas B is [Chemical Formula 3] whereas C is 【Chemical Formula 4】 whereas D is 【Chemical Formula 5】 whereas R in A to D １ to R ２０ each independently represents a hydrogen atom, a trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent, an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent, a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, an aromatic hydrocarbon group having 6 to 36 carbon atoms having a substituent, or a heterocyclic group having 5 to 36 ring-forming atoms which may have a substituent. In the formula, * represents the bonding position with formula (1). However, 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 in the formula (1), the A and the B are different, the C and the D are different, the A and the C are the same, and the B and the D are the same, and the hole transport layer contains a compound.

3. In A to D of the formula (1), R １ to R ２０ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, or a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, or an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent, and the hole transport layer contains a compound represented by the above, and the photoelectric conversion element according to claim 1.

4. In the formula (1), the hole transport layer contains a compound in which A to D are one of a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, or an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent, and is located at one position in the ortho position or para position. The photoelectric conversion element according to claim 1.

5. In the formula (1), When the phenyl group in A does not contain a substituent, the phenyl group in B has a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, or an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent, When the phenyl group in A has a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, the phenyl group in B has an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, or an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent, When the phenyl group in A has a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent, the phenyl group in B has a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent, The photoelectric conversion element according to claim 2, wherein when the phenyl group in A has an alkylthio group or arylthio group having 1 to 18 carbon atoms which may have a substituent, the phenyl group in B has a (di)alkylamino group or (di)arylamino group having 1 to 20 carbon atoms which may have a substituent.

6. The photoelectric conversion element according to claim 1, wherein the compound represented by the formula (1) is any one of the compounds represented by the following formulas (A-8), (A-12), (A-14), (A-16), and (A-23). 【Chemical Formula 6】 【Chemical Formula 7】 [Chemical Formula 8] 【Chemical Formula 9】 【Chemical Formula 10】

7. The photoelectric conversion element according to claim 1, which has an intermediate layer containing phthalocyanine particles between the hole transport layer and the photoelectric conversion layer.

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