Photoelectric conversion element and photoelectric conversion device

Abstract

To provide a photoelectric conversion element that protects a crystal of a perovskite structure from a flaw and improves leakage resistance and conversion efficiency.SOLUTION: A photoelectric conversion element has a first electrode, a second electrode, and a photoelectric conversion layer arranged between the first electrode and the second electrode and including a crystal of a perovskite structure. The photoelectric conversion element has, between the photoelectric conversion layer and the first electrode, a charge transport layer including an annular conjugated compound in which a plurality of pyrrole rings are conjugated and bonded, and an aliphatic resin having at least one functional group selected from the group consisting of a hydroxy group and a carboxy group.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In order to solve the problem of fossil energy depletion and the global environmental problems caused by the use of fossil energy, active research is being conducted on renewable and clean alternative energy sources such as solar energy, wind power, and hydroelectric power. Among them, interest in solar cells that directly convert sunlight into electrical energy is increasing. Here, a solar cell refers to a cell that generates a current and voltage by utilizing the photovoltaic effect in which light energy from sunlight is absorbed and electrons and holes are generated.

[0003] Currently, np diode type silicon (Si) single crystal-based solar cells with a light energy conversion efficiency of over 20% are widely known and are actually used for photovoltaic power generation. However, these require high-temperature processing and the materials themselves are expensive, so they have the problem of high cost per unit of power. In addition, there are problems with supply in terms of silicon resources.

[0004] On the other hand, solar cells using organic materials (hereinafter referred to as "organic solar cells") do not require high-temperature processing and can be produced using a sheet-like substrate by the so-called roll-to-roll method, which is expected to reduce costs. However, further improvements in power generation efficiency and durability are required for the practical use of organic solar cells. In particular, perovskite-type solar cells, which have crystals with a perovskite structure as a photoelectric conversion layer, have excellent photoelectric conversion properties, so development is being promoted for the practical use of solar cells.

[0005] For example, Patent Document 1 describes that by mixing an insulating polymer and a hole transport material in the hole transport layer, peeling from the anode is suppressed, and conversion efficiency and durability are improved. Non-Patent Document 1 describes that by including polymethyl methacrylate (PMMA) as a leak prevention layer in the upper layer of the perovskite, conversion efficiency is increased due to the suppression of shunt leak. Non-Patent Document 2 describes that by mixing copper phthalocyanine and a conductive polymer in the hole transport layer, conversion efficiency is improved. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-170382 A [Non-patent literature]

[0007] [Non-Patent Document 1] F. Wang,et al,J.Phys.Chem.C,2017,121,1562 [Non-Patent Document 2] Q. Hu,et al,Sol.RRL,2019,3,1800264 Summary of the Invention [Problem to be solved by the invention]

[0008] According to the studies of the present inventors, the photoelectric conversion elements described in Patent Document 1 and Non-Patent Documents 1 and 2 have a problem in achieving a further improvement in conversion efficiency while maintaining the suppression of shunt leak.

[0009] Therefore, an object of the present invention is to provide a photoelectric conversion element having improved leak resistance and conversion efficiency by protecting crystal defects in a perovskite structure, and to provide a photoelectric conversion device having improved leak resistance and conversion efficiency. [Means for solving the problem]

[0010] The above object can be achieved by the present invention as described below. 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 crystal of a perovskite structure disposed between the first electrode and the second electrode, characterized in that the photoelectric conversion layer has a charge transport layer between the photoelectric conversion layer and the first electrode, the charge transport layer containing a cyclic conjugated compound formed by conjugating a plurality of pyrrole rings, and an aliphatic resin having at least one functional group selected from the group consisting of a hydroxy group and a carboxy group. Effect of the Invention

[0011] According to the present invention, it is possible to provide a photoelectric conversion element having improved leakage resistance and conversion efficiency. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic cross-sectional view in a thickness direction of a first embodiment of a photoelectric conversion element of the present invention. [Diagram 2] FIG. 4 is a schematic cross-sectional view in the thickness direction of a second embodiment of a photoelectric conversion element of the present invention. [Diagram 3] 1 is a perspective view showing a schematic diagram of an embodiment of a moving body including a photoelectric conversion element of the present invention; [Figure 4] FIG. 1 is a perspective view showing a schematic diagram of one embodiment of a building material including a photoelectric conversion element of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] 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 crystal of a perovskite structure disposed between the first electrode and the second electrode, and has a charge transport layer between the photoelectric conversion layer and the first electrode, the charge transport layer containing a cyclic conjugated compound formed by covalently bonding a plurality of pyrrole rings, and an aliphatic resin having at least one functional group selected from the group consisting of a hydroxy group and a carboxy group.

[0014] As a result of investigations, the present inventors have found that the inclusion of the charge transport layer results in a photoelectric conversion element having excellent leakage resistance and conversion efficiency. Although the details of why a photoelectric conversion element having high stability is obtained in the present invention are not clear, it is believed to be as follows. By forming a film of the cyclic conjugated compound in which a plurality of pyrrole rings are covalently bonded as a charge transport material, a high hole transport ability is exhibited. Furthermore, according to the conventional study by the present inventors, when the photoelectric conversion layer contains a crystal of a perovskite structure, submicron unevenness occurs on the surface, and it is presumed that by filling the concaves of such unevenness with pigment particles made of a phthalocyanine compound, the interface junction is stabilized and high photoelectric conversion efficiency can be obtained. However, it was found that filling with the pigment made of the phthalocyanine compound may not be able to suppress leakage due to crystal defects or deterioration of the crystal of the perovskite structure. Furthermore, according to the study by the present inventors, in the photoelectric conversion element described in Non-Patent Document 1, it is required to form a film of an extremely thin insulating resin from the viewpoint of electrical conductivity, so it is difficult to completely cover the crystal of the perovskite structure with large defect sites, and it was found that there is room for further improvement in leakage resistance.

[0015] In the present invention, therefore, the charge transport layer is formed containing a cyclic conjugated compound in which a plurality of pyrrole rings are covalently bonded, and an aliphatic resin having at least one functional group selected from the group consisting of a hydroxyl group and a carboxyl group, thereby making it possible to improve leakage resistance and conversion efficiency. The present inventors presume that the aliphatic resin improves leakage resistance, and that the electronic interaction between the cyclic conjugated compound and the aliphatic resin suppresses an increase in the series resistance of the film, thereby contributing to an increase in conversion efficiency.

[0016] The present inventors believe that the combination of an aliphatic resin having at least one functional group selected from the group consisting of a hydroxyl group and a carboxyl group with a cyclic conjugated compound formed by covalently bonding a plurality of pyrrole rings can contribute to improving leakage resistance and conversion efficiency. This is because when a plurality of pyrrole rings are covalently bonded to form a cyclic conjugated compound, the π electron cloud is greatly expanded in the direction perpendicular to the large planar cyclic surface, and the electronic interaction with other molecules becomes greater. When the cyclic conjugated compound, which is prone to electronic interaction, electronically interacts with the functional group of the aliphatic resin, an electronic bias occurs inside the cyclic conjugated compound, increasing the carrier density.

[0017] As a result, it is presumed that the electrical conductivity of the cyclic conjugated compound itself, which is a charge transport material, increases, contributing to the increase in leakage resistance and conversion efficiency. Furthermore, since the crystal defects of the perovskite structure are several tens to several hundreds of nm, it has been found that even when a hole transport layer or an insulating layer is introduced to a thickness of several tens of nm between the charge transport layer and the photoelectric conversion layer of the present invention, it contributes to the improvement of leakage resistance and conversion efficiency. It is particularly preferable that the charge transport layer is in contact with the photoelectric conversion layer from the viewpoint of leakage resistance.

[0018] Specific examples of the hole transport layer or insulating layer that may be interposed between the charge transport layer and the photoelectric conversion layer of the present invention include sodium chloride, sodium iodide, potassium iodide, rubidium iodide, cesium acetate, copper bromide (1), copper iodide (1), nickel chloride (2), zinc iodide, germanium dioxide, aluminum acetylacetonate, europium (3) acetylacetonate, 1,8-diaminooctane dihydroiodide, 1,4-butanediamine dihydroiodide, hexylamine hydrobromide, n-octylamine hydrobromide, 2-phenylethylammonium iodide, ethylenediamine Hydrogen diiodide, sodium fluoride, cesium chloride, methylammonium chloride, lead thiocyanate(2), lead acetate(2), potassium chloride, niobium fluoride(5), choline chloride, L-α-phosphatidylcholine, fullerene, phenyl C61 butyric acid methyl ester (PCBM((6,6)-phenyl C61 butyric acid methyl ester)), iodopentafluorobenzene, F4TCNQ, thiophene, pyridine, pentafluorobenzyl bromide, (3-mercaptopropyl) Preferred examples include trimethoxysilane, thiourea, benzylamine, hexamethylenetetramine, N-(3-aminopropyl)-2-pyrrolidinone, theophylline, caffeine, 2-aminoethanesulfonamide hydrochloride, tri-n-octylphosphine oxide, graphene oxide, poly(3-hexylthiophene-2,5-diyl), poly(4-vinylpyridine), polyethylene oxide, polyvinylpyrrolidone, and poly(methyl methacrylate). Among these, sodium chloride, potassium iodide, rubidium iodide, cesium acetate, nickel(2) chloride, aluminum acetylacetonate, n-octylamine hydrobromide, 2-phenylethylammonium iodide, sodium fluoride, cesium chloride, methylammonium chloride, potassium chloride, niobium(5) fluoride, thiophene, pyridine, trimethoxysilane, thiourea, benzylamine, theophylline, poly(4-vinylpyridine), and poly(methyl methacrylate) are particularly preferred.

[0019] From the viewpoint of leak resistance, the molecular weight of the aliphatic resin is preferably 10,000 or more. From the viewpoint of interaction with the cyclic conjugated compound, it is preferable that the functional group of the aliphatic resin having at least one functional group selected from the group consisting of a hydroxy group and a carboxy group further has at least one functional group selected from the group consisting of a carbonyl group, an ester group (ester bond), an ether group (ether bond), a carboxy group, a methoxy group, an amino group, a sulfo group, an aldehyde group, an amide group (amide bond), and a sulfide group.

[0020] From the viewpoints of leakage resistance and conversion efficiency, the content of the cyclic conjugated compound in which a plurality of pyrrole rings are covalently bonded is preferably 5 to 30 mass %, and more preferably 8 to 20 mass %, based on the aliphatic resin having at least one functional group selected from the group consisting of a hydroxy group and a carboxy group.

[0021] In the present invention, the aliphatic resin having at least one functional group selected from the group consisting of a hydroxyl group and a carboxyl group refers to a resin having the functional group in either the main chain or the side chain. It is preferable that the functional group is contained in a position other than the terminal of the main chain. In addition, the hydroxyl group and the carboxyl group are Lewis basic functional groups.

[0022] Specific examples of the aliphatic resin preferably used in the present invention are given below. Polyvinyl alcohol, polyacrylic acid, poly(2-propylacrylic acid), poly(4-vinylphenol), polyvinyl butyral, poly(butadiene / maleic acid), poly(2-hydroxyethyl methacrylate), and poly(methyl methacrylate / methacrylic acid) are preferred. Among these, polyvinyl alcohol, polyacrylic acid, polyvinyl butyral, poly(butadiene / maleic acid), poly(2-hydroxyethyl methacrylate), and poly(methyl methacrylate / methacrylic acid) are particularly preferred from the viewpoint of electronic interaction.

[0023] The cyclic conjugated compound formed by covalently bonding a plurality of pyrrole rings used in the present invention is preferably a porphyrin compound or a phthalocyanine compound, more preferably a phthalocyanine compound, from the viewpoint of the spread of the π-electron cloud that is the starting point of the interaction. The phthalocyanine compound may have a central element, and examples of the central element include Ga, Cu, Ti, Zn, Si, V, Pb, and Pt. Among them, Ga is preferred from the viewpoint of electronic interaction with an aliphatic resin having at least one functional group selected from the group consisting of a hydroxy group and a carboxy group, and in particular, a hydroxygallium phthalocyanine compound is preferred from the viewpoint of interaction with the functional group. The aliphatic resin having at least one functional group selected from the group consisting of a hydroxy group and a carboxy group in the present invention preferably has a glass transition temperature of 95° C. or lower from the viewpoint of the mixed state of the film.

[0024] Specific examples of the porphyrin compound of the present invention are given below. [ka] [ka] In the above formulas (P-1) and (P-2), R 1 ~R 12 each independently represents an organic group containing hydrogen, an aromatic group which may have a substituent, or an aliphatic group which may have a substituent.

[0025] R 1 ~R 12As the X, hydrogen, a methyl group, an ethyl group, a propyl group, a isopropyl group, a butyl group, an octyloxy group, a butoxy group, a halogen atom, a phenyl group, a phenoxy group, a carboxyphenyl group, a benzenesulfonic acid group, a hydroxyphenyl group, a dihydroxyphenyl group, a trihydroxyphenyl group, a methoxyphenyl group, a dimethoxyphenyl group, a trimethoxyphenyl group, a methylphenyl group, a dimethylphenyl group, a trimethylphenyl group, a pyridyl group, an aminophenyl group, a sodium sulfonate base, a 4-cumylphenoxy group, a sulfonic acid group, a phenylthio group, a tert-butyl group, a hydroxy group, a carbonyl group, a methoxy group, an amino group, a sulfo group, and an aldehyde group are preferable. In the above formulas (P-1) and (P-2), X represents an inorganic atom including a metal atom, and specifically, Ga, GaOH, GaCl, TiO, Ti, Si, V, Pb, SiCl 2、 Cu, Zn, Pd, Pb, Ni, Pt, Co, MnCl, FeCl, VO, RuCO are preferred.

[0026] Specific examples of the phthalocyanine compound of the present invention are given below. [ka] [ka] [ka]

[0027] In the above formulas (P-3) and (P-4), R 13 ~R 28 R each independently represents an organic group containing a hydrogen atom, an aromatic group which may have a substituent, or an aliphatic group which may have a substituent. 13 ~R 28Examples of the aryl group include hydrogen atom, methyl group, ethyl group, propyl group, isopropyl group, butyl group, octyloxy group, butoxy group, halogen atom, phenyl group, phenoxy group, carboxyphenyl group, benzenesulfonic acid group, hydroxyphenyl group, dihydroxyphenyl group, trihydroxyphenyl group, methoxyphenyl group, dimethoxyphenyl group, trimethoxyphenyl group, methylphenyl group, dimethylphenyl group, trimethylphenyl group, pyridyl group, aminophenyl group, sodium sulfonate base, 4-cumylphenoxy group, sulfonic acid group, phenylthio group, tert-butyl group, hydroxy group, carbonyl group, methoxy group, amino group, sulfo group, and aldehyde group. Among them, methyl group, ethyl group, propyl group, butyl group, halogen atom, sulfonic acid group, hydroxy group, carbonyl group, methoxy group, amino group, sulfo group, and aldehyde group are preferred.

[0028] In the above formulas (P-3), (P-4), and (P-5), X represents an inorganic atom including a metal atom, specifically, Ga, GaOH, GaCl, Ti, TiO, Si, V, SiCl 2、 Cu, Zn, Pd, Pb, Ni, Pt, Co, MnCl, FeCl, VO, RuCO, among them Ga, GaOH, GaCl, TiO, Ti, SiCl 2、 Cu, Zn, Pd, Pb, Ni, Pt, Co, MnCl, FeCl, VO, and RuCO are preferred, and Ga, GaOH, GaCl, and TiO are more preferred.

[0029] As explained above, the components constituting the present invention exert a synergistic effect on each other, thereby making it possible to achieve the effects of the present invention.

[0030] The present invention will be described in detail below with reference to preferred embodiments. The present invention is not limited to the following embodiments, and any modifications or improvements to the following embodiments based on the ordinary knowledge of a person skilled in the art without departing from the spirit of the present invention are also included in the scope of the present invention.

[0031] In this specification, the term "layer" refers not only to a layer having a clear boundary or a flat thin-film layer, but also to a layer having a concentration gradient in which the contained elements change gradually, or to a layer that can form a complex structure together with other layers. Elemental analysis of the layer can be performed, for example, by performing TOF-SIMS / FE-TEM / EDS line analysis measurement of the cross section of the photoelectric conversion element to confirm the element distribution of a specific element. Furthermore, the chemical structure of functional groups and the like can be confirmed by nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FT-IR).

[0032] 1 is a cross-sectional view showing a schematic configuration of one embodiment of the photoelectric conversion element of the present invention. A second electrode 3, an electron transport layer 4, a photoelectric conversion layer 5, a charge transport layer 6, and a first electrode 7 are provided on a substrate 2. One of the first electrode 7 and the second electrode 3 is a positive electrode and the other is a negative electrode, and a current can be extracted by connecting the first electrode 7 and the second electrode 3 to an external circuit.

[0033] The photoelectric conversion layer 5 is excited by light incident through the substrate 2, the second electrode 3, and the electron transport layer 4, or the first electrode 7 and the charge transport layer 6, and generates 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 may not be formed in some cases. A form in which a plurality of electron transport layers 4 and photoelectric conversion layers 5 are stacked may be used. Such a form may be called a tandem structure. In addition, a photoelectric conversion element may be fabricated on the substrate 2 in the order of the first electrode 7, the charge transport layer 6, the photoelectric conversion layer 5, the electron transport layer 4, and the second electrode 3.

[0034] Each member constituting the photoelectric conversion element of the present invention will be described below. [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 crystal of a perovskite structure disposed between the first electrode and the second electrode, characterized in that a charge transport layer is provided between the photoelectric conversion layer and the first electrode. In addition, in order to improve the photoelectric conversion efficiency, the photoelectric conversion elements may be stacked in a tandem type. The photoelectric conversion elements to be stacked are not limited to the type of photoelectric conversion element, and may include a perovskite solar cell using a crystal of a perovskite structure in the photoelectric conversion layer, a silicon solar cell, a CIGS solar cell, and the like.

[0035] The photoelectric conversion layer of the photoelectric conversion element of the present invention and each layer including the charge transport layer can be formed by coating or vapor deposition. 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 in which the coating liquid for each layer described later is prepared, coated in the desired layer order, and dried. A desired method can be selected from these film formation methods according to each layer. Each layer will be described below.

[0036] 〔substrate〕 The photoelectric conversion element 1 of the present invention may include a substrate 2, examples of which include a transparent glass substrate such as soda-lime glass or alkali-free glass, a ceramic substrate, and a transparent plastic substrate. When light is taken in from the first electrode 7 side, an opaque material can be used for the substrate 2, and when light is taken in from the second electrode 3 side, the substrate 2 is made of a transparent material.

[0037] 〔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 nanotubes, aluminum, magnesium-silver mixture, magnesium-indium mixture, aluminum-lithium alloy, Al / Al 2 O 3Examples of transparent electrode materials include CuI, ITO (indium tin oxide), SnO 2 Examples of the conductive transparent materials include 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. These materials may be used alone or in combination of two or more. The first electrode 7 and the second electrode 3 are such that at least one electrode on the light incident side is a transparent electrode, and the other may be a transparent electrode or a layer that also serves as a reflective layer formed of a light-reflective material, or 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 a transparent electrode and the substrate 2 may be a reflective layer. The transparent electrode may be a patterned electrode.

[0038] [Photoelectric Conversion Layer] The photoelectric conversion layer 5 has a crystal having a perovskite structure. The crystal having a perovskite structure used in the present invention is preferably represented by the following general formula [1]. A o B p X q [1] In the above general formula [1], A is a cation, B is a cation, and X is an anion. o, p, and q satisfy 0≦o≦10, 0≦p≦10, and 0≦q≦20, respectively, and A, B, and X may be composed of a single material or may be used in combination of two or more types. Additives may be added within the range in which the above general formula is established. The above general formula generally forms a three-dimensional perovskite crystal, but when the constituent A cation is large enough to fit within the three-dimensional perovskite crystal, it forms a two-dimensional perovskite crystal, a 2.5-dimensional perovskite crystal with both two-dimensional and three-dimensional properties, a two-layer crystal of a three-dimensional and two-dimensional perovskite structure, or a mixed three-dimensional and two-dimensional perovskite crystal, all of which function as a photoelectric conversion layer.

[0039] A bilayer crystal of 3D and 2D perovskite refers to a crystal in which 3D and 2D perovskite structure crystals are stacked as independent layers, and a mixed 3D-2D perovskite refers to a crystal with a structure in which both regions or domains of 2D or 2.5D layered and 3D perovskite structure crystals are mixed. A 2D perovskite or 2.5D perovskite structure crystal may form a Ruddlesden-Popper (RP), Dion-Jacobson (DJ), or Alternating cations in the interlayer (ACI) perovskite structure.

[0040] As A in the above general formula [1], there is no particular limitation on the A cation. The A cation may or may not have a substituent, and specific examples thereof include the following structural formulas. [ka] [ka]

[0041] The inorganic atom is not particularly limited, but lithium, cesium, sodium, potassium, and rubidium are preferred. These organic molecules or inorganic atoms may be used alone or in combination of two or more.

[0042] B in the above general formula [1] is a cationic atom, and examples thereof 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, bismuth, and silver are preferred from the viewpoint of the stability of the perovskite crystal structure. These atoms may be used alone or in combination of two or more.

[0043] X in the above general formula [1] is a halogen or chalcogen atom, such as chlorine, bromine, iodine, oxygen, sulfur, selenium, tellurium, and polonium. These halogens or chalcogen atoms may be used alone or in combination of two or more. Among them, halogen atoms are preferred because the perovskite structure crystal is easily soluble in an organic solvent by containing halogen in the structure, making it possible to apply it to inexpensive printing methods, etc. Furthermore, iodine is more preferred because the energy band gap of the perovskite structure crystal is narrowed.

[0044] Specifically, we investigated 3D perovskite, 2D perovskite, and mixed 3D-2D perovskite. The MAPbI 3 or FAPbCl 3 , FAPbI 3 , MAPbI 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 , (FAPbI 3 ) 0.95 (MAPbBr 3 ) 0.05 , (FAPbI 3 ) 0.85 (MAPbBr 3 ) 0.15 , CsPbI 3 , CsPbBr 3 , Cs x (MA) 1-x PbI3 、Cs x (FA) 1-x PbI 3 、MA x (FA) 1-x PbI 3 、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) 2 Pb 3 I 10 、(PTA) 2 (MA) 4 Pb 5 I 16 、(PEA) 2 (MA) 4 Pb 5 I 16 、(ThMA) 2 (MA) 2 Pb 3 I 10 、(3BBA) 2 (MA) 2 Pb 3 I 10 、(ThMA) 2 (FA) 4 Pb 5 I 16 、(pF-PEA) 2 (FA 0.3 MA 0.7 ) 4 Pb 5 I 16 、(PDMA)FA 2 Pb 3 I 10 、(3AMPY)(MA) 3 Pb 4 I 13 、(PDMA)A 5Pb 6 I 19 、(PDMA)MA 3 Pb 4 I 13 、(BA 0.9 PEA 0.1 ) 2 MA 4 Pb 5 I 16 、(BA 0.9 PEA 0.1 ) 2 MA 3 Pb 4 I 13 、BA) 2 、MA 2 Pb 3 I 10 、(BA) 2 MA 3 Pb 4 I 13 、(BA) 2 MA 4 Pb 5 I 16 、(BA) 2 MA 3 Pb 4 I 13 、CsSnBr 3 、CsSnI 3 、FA 0.75 MA 0.25 Sn 0.95 Ge 0.05 I 3 、FAMASnGeI 3 、FASnBr 3 、FASnI 3 、MA 2 Sn 3 I 8 、MASnBr 3 、MASnGeI 3 、MASnI 3 are preferred.

[0045] Depending on the purpose, the A site, B site, or X site in the above general formula may be adjusted to be under- or over-adjusted, and the combination of x1 to x5 may be changed depending on the purpose. Combinations of x1 to x5 are, for example, as shown in Table 1. Particularly preferred ranges of 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 may be included as a material for forming perovskite crystals.

[0046] [Table 1]

[0047] The crystal with the perovskite structure preferably has a cubic structure in which a metal atom B is located at the body center, an organic molecule A at each vertex, and a halogen atom X at the face center. Although the details are not clear, it is presumed that the presence of such a structure makes it easy to change the orientation of the octahedron in the crystal lattice, thereby increasing the mobility of electrons in the crystal with the perovskite structure and improving the photoelectric conversion efficiency of the photoelectric conversion element.

[0048] The perovskite crystal used in the present invention is preferably a crystalline semiconductor. The crystalline semiconductor means a semiconductor in which the scattering peak can be detected by measuring the X-ray scattering intensity distribution. By using the perovskite crystal as a crystalline semiconductor, the mobility of electrons in the perovskite crystal is increased, and the photoelectric conversion efficiency of the photoelectric conversion element is improved.

[0049] 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 the thickness is 2000 nm or less, the generated charge can be transported to each electrode. The more preferred lower limit is 50 nm, the more preferred upper limit is 1200 nm, the even more preferred lower limit is 100 nm, and the even more preferred upper limit is 1000 nm.

[0050] [Charge transport layer] In the present invention, the charge transport layer preferably contains a cyclic conjugated compound in which a plurality of pyrrole rings are conjugated, and at least one functional group selected from the group consisting of a hydroxy group and a carboxy group. Furthermore, the aliphatic resin having at least one functional group selected from the group consisting of a hydroxy group and a carboxy group preferably has a molecular weight of 10,000 or more. The aliphatic resin having at least one functional group selected from the group consisting of a hydroxy group and a carboxy group preferably further has at least one functional group selected from the group consisting of a carbonyl group, an ester group, an ether group, a carboxy group, a methoxy group, an amino group, a sulfo group, an aldehyde group, an amide group, and a sulfide group.

[0051] The content by mass of the cyclic conjugated compound in the charge transport layer is preferably 5 to 30 times, and more preferably 8 to 20 times, the content by mass of the aliphatic resin in the charge transport layer.

[0052] The cyclic conjugated compound contained in the charge transport layer is preferably a phthalocyanine compound, and the phthalocyanine compound preferably has a central element. Furthermore, the phthalocyanine compound is preferably a metal phthalocyanine compound, more preferably a gallium phthalocyanine compound, and more preferably a hydroxygallium phthalocyanine compound.

[0053] The thickness of the charge transport layer is preferably from 1 nm to 1000 nm, more preferably from 5 nm to 500 nm, and particularly preferably from 10 nm to 200 nm.

[0054] The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing the above-mentioned materials and solvent, forming this coating film on the photoelectric conversion layer, and drying it. Examples of the solvent used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, alcohol-based solvents or aromatic hydrocarbon-based solvents are preferred.

[0055] [Second Charge Transport Layer] In the present invention, from the viewpoint of film compatibility of the charge transport layer 6, a second charge transport layer may be further provided between the charge transport layer 6 and the first electrode . The material of the second charge transport layer is not particularly limited, and examples thereof 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. In particular, the second charge transport layer preferably has an aromatic ring from the viewpoint of compatibility with the film interface, and preferably contains a spirofluorene compound or a triphenylamine compound, and preferably contains Spiro-OMeTAD or PTAA.

[0056] The second charge transport layer may have a dopant as an additive to improve the charge transport ability. Examples of materials that can be used as a dopant include lithium compounds such as bis(trifluoromethanesulfonyl)imide lithium, cobalt compounds such as [tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(3)tris(bis(trifluoromethylsulfonyl)imide)], boron compounds such as tetrakis(pentafluorophenyl)borate, molybdenum compounds such as tris[1-(methoxycarbonyl)-2-(trifluoromethyl)-ethane-1,2-dithiolene]molybdenum, organic compounds having a tetracyanoquinodimethane skeleton such as 2,3,4,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, and organic compounds having a pyridine skeleton such as 4-tert-butylpyridine.

[0057] [Electron transport layer] In the photoelectric conversion element of the present invention, as shown in FIGS. 1 and 2, 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, surfactants, and the like. Specific examples thereof include cyano group-containing polyphenylene vinylene, boron-containing polymers, bathocuproine, bathophenanthrene, hydroxyquinolinatoaluminum, oxadiazole compounds, benzimidazole compounds, naphthalene tetracarboxylic acid compounds, fullerene compounds, perylene compounds, phosphine oxide compounds, phosphine sulfide compounds, fluoro group-containing phthalocyanines, titanium oxide, zinc oxide, indium oxide, tin oxide, gallium oxide, tin sulfide, indium sulfide, and zinc sulfide.

[0058] The thickness of the electron transport layer 4 is preferably 1 nm at the lower limit and 2000 nm at the upper limit. If the thickness is 1 nm or more, holes can be blocked sufficiently, and if the thickness is 2000 nm or less, the layer is unlikely to become a resistance during electron transport, and the photoelectric conversion efficiency is increased. The more preferable lower limit of the thickness is 3 nm, the more preferable upper limit is 1000 nm, the even more preferable lower limit is 5 nm, and the even more preferable upper limit is 500 nm.

[0059] [Photoelectric conversion device] The photoelectric conversion device of the present invention has the photoelectric conversion element of the present invention. A photoelectric conversion device can be configured by using a plurality of photoelectric conversion elements of the present invention. When a plurality of photoelectric conversion elements are connected, such a photoelectric conversion device can also be called a photoelectric conversion cell or a photoelectric conversion module. The photoelectric conversion element may be stacked with elements having different absorption wavelengths in order to increase the output voltage. The photoelectric conversion device may have the photoelectric conversion element of the present invention and an inverter. The inverter may be a converter that converts direct current to alternating current. The photoelectric conversion device may have a storage unit connected to the photoelectric conversion element. The 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 impart a function such as maintaining or increasing the amount of incident light, a surface layer that is resistant to water and dirt, or a function of collecting or guiding light may be added.

[0060] [Mobile object] FIG. 3 is a perspective view showing a schematic diagram of an embodiment of a moving body equipped with a photoelectric conversion element of the present invention. The moving body 30 has a photoelectric conversion element 31 of the present invention and a vehicle 32 equipped with the photoelectric conversion element 31. The photoelectric conversion element 31 is disposed at a position on the vehicle 32 where it can receive external light. If the moving 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 source for the moving body 30 or may be used as the power source for other electric devices. The electric energy generated from the power source of the moving body 30 may be used as the power source for the photoelectric conversion element 31. If the moving body 30 is an automobile, the frictional energy generated by the brakes may be converted into electric energy and used to control the photoelectric conversion element 31.

[0061] The moving body 30 may be, for example, an automobile, a motorcycle, a railroad vehicle, a ship, an artificial satellite, an airplane, or a flying object including a drone. The configuration of the body 32 of the moving body 30 is not particularly limited, but it is preferable that the body 32 be made of a high-strength material.

[0062] [Building materials] 4 is a perspective view showing an embodiment of a building material including a photoelectric conversion element of the present invention. The building material 40 may be the roof of a building. The building material 40 of this embodiment has a photoelectric conversion element 41 of the present invention, a protective member 42 that protects the photoelectric conversion element 41, a heat dissipation member 43, and exteriors 44a and 44b.

[0063] 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. In general, when a building material having a photoelectric conversion element is used on a roof or the like, the temperature of the photoelectric conversion element 41 may increase due to sunlight, and the photoelectric conversion efficiency may decrease. In this case, the decrease in photoelectric conversion efficiency can be reduced by using the heat dissipation member 43. Examples of the heat dissipation member 43 include metal, alloy, liquid metal, and liquid resin.

[0064] The building material 40 of the present invention may have exteriors 44a and 44b. The exteriors 44a and 44b may emit different colors or the same color. The exteriors 44a and 44b may be made of the same material or different materials. Paint or a transparent substrate may be used as the exterior material, and it is preferable to use one with low light absorption and high heat insulation.

[0065] In addition to the above application examples, the following application examples using the photoelectric conversion element of the present invention can be mentioned. Portable devices include, for example, calculators, sensors, and small solar panels. Wearable devices include, for example, eyeglass-type terminals, wristwatch-type terminals, and portable medical equipment. Sheet structures supported by multiple frames include, for example, tents, vinyl greenhouses, and truck beds. Fixed structures include, for example, road panels, floating panels, building materials that take advantage of the flexibility of the substrate, wall-type building materials, glass-type building materials, and mega solar panels.

[0066] [About the manufacturing method of photoelectric conversion element] A method for producing a photoelectric conversion element of the present invention includes the steps of forming a first electrode, forming a second electrode, forming a photoelectric conversion layer containing crystals with a perovskite structure between the first electrode and the second electrode, and forming a charge transport layer between the photoelectric conversion layer and the first electrode. Each step of the manufacturing method will be described below.

[0067] [Step of forming a first electrode and step of forming a second electrode] In the step of forming the first electrode and the step of forming the second electrode, an appropriate method can be selected according to the material of the first electrode and the material of the second electrode, respectively. Examples of such methods include, but are not limited to, sputtering vacuum deposition, CVD (vapor phase deposition), and SPD (spray pyrolysis deposition). The materials of the first electrode and the second electrode are as described above. When either 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 between each process to form a circuit. Examples of cutting include mechanical patterning and laser patterning.

[0068] [Modularization process] The element having the electrodes formed thereon may be sealed. Examples of the sealing method include sealing with a resin or sealing with a film. Examples of the material used for sealing include silazane, silicone rubber, a resin having a siloxane skeleton, and glass. In addition, from the viewpoint of preventing adhesion between elements that occurs when the elements are wound in a roll-to-roll system, the surfaces of the encapsulated elements may be subjected to a hairline treatment.

[0069] [Step of forming photoelectric conversion layer] The step of forming the photoelectric conversion layer may include a step of applying a liquid containing the material of the photoelectric conversion layer described above. Examples of the application method include spin coating, blade coating, slit die coating, screen printing, bar coater, mold method, print transfer method, immersion and pulling method, inkjet method, spray method, and vacuum deposition method. Among these, the method is appropriately selected according to the characteristics of the photoelectric conversion layer to be produced, such as thickness control and orientation control. In order to remove the solvent or dispersion medium from the applied liquid containing the material of the photoelectric conversion layer, an annealing treatment may be performed under reduced pressure or in an inert atmosphere (nitrogen, 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. It is preferable to perform the annealing treatment because the materials constituting each layer penetrate each other at the interface between the stacked layers, increasing the contact area and increasing the short-circuit current.

[0070] [Step of forming charge transport layer] The step of forming the charge transport layer is preferably a method of applying a liquid containing the material of the charge transport layer, such as spin coating, blade coating, slit die coating, screen printing, bar coater, casting, print transfer, immersion and pulling, inkjet, spraying, and vacuum deposition. EXAMPLES

[0071] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited to the following examples without departing from the gist of the present invention. In the following description of the examples, "parts" are by mass unless otherwise specified.

[0072] Preparation of particle 1 Process (1) In a nitrogen flow atmosphere, 5.46 parts of orthophthalonitrile and 45 parts of α-chloronaphthalene were put into a reaction vessel, and then heated to a temperature of 30°C and maintained at this temperature. Next, 3.75 parts of gallium trichloride were put in at this temperature (30°C). The water concentration of the mixed liquid at the time of putting in was 150 ppm. Then, the temperature was raised to 200°C. Next, under a nitrogen flow atmosphere, the reaction was carried out at a temperature of 200°C for 4.5 hours, and then cooled. When the temperature reached 150°C, the product was filtered. The obtained filtrate was dispersed and washed using N,N-dimethylformamide at a temperature of 140°C for 2 hours, and then filtered. The obtained filtrate was washed with methanol and then dried to obtain chlorogallium phthalocyanine particles with a yield of 71%.

[0073] Process (2) 4.65 parts of the chlorogallium phthalocyanine particles were dissolved in 139.5 parts of concentrated sulfuric acid at a temperature of 10° C., dropped into 620 parts of ice water under stirring to reprecipitate, and filtered under reduced pressure using a filter press. At this time, No. 5C (manufactured by Advantec Co., Ltd.) was used as the filter. The obtained wet cake (filtrate) was dispersed and washed with 2% ammonia water 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 filtration using a filter press was repeated three times. Finally, freeze-drying was performed to obtain hydroxygallium phthalocyanine particles (hydrated hydroxygallium phthalocyanine particles) with a solid content of 23% by mass at a yield of 71%. The hydroxygallium phthalocyanine particles were dried in a Hyper Dry dryer (product name: HD-06R, frequency (oscillation frequency): 2455 MHz ± 15 MHz, manufactured by Japan Biocon) to obtain hydroxygallium phthalocyanine (OHGaPc) particles (crystals) with a moisture content of 1.0 mass% or less.

[0074] Process (3) Five parts of the hydroxygallium phthalocyanine particles were mixed with 5 parts of N-methylformamide solvent, and the mixture was dispersed 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) containing 5 parts of glass beads, filtered, and dried to obtain Particle 1.

[0075] Preparation of resin solution 1 1.0 g of polyvinyl butyral (product name: BM-2, manufactured by Sekisui Chemical Co., Ltd., glass transition temperature 71° C.) was dissolved in 19 g of 2-propanol with stirring for 24 hours to obtain resin solution 1.

[0076] Example 1 [Formation of Electron Transport Layer] A glass substrate with ITO was cleaned, and tin oxide (2) adjusted to 3 mass % was applied thereon by spin coating, and then heated at 150° C. for 30 minutes to form a thin-film electron transport layer with a thickness of 15 nm.

[0077] [Formation of photoelectric conversion layer] 22.4 mg of methylammonium bromide, 172 mg of formamidium iodide, and 576 mg of lead iodide were dissolved in 600 μL of N,N-dimethylformamide and 160 μL of dimethyl sulfoxide, and the mixture was stirred for 1 hour (solution 1). Furthermore, 389.72 mg of cesium iodide was dissolved in 1000 μL of dimethyl sulfoxide, and the mixture was stirred for 1 hour (solution 2). Then, 40 μL of the dissolved cesium iodide solution (solution 2) was added to solution 1 to prepare a photoelectric conversion layer coating solution. This coating solution was spin-coated on the electron transport layer to produce Cs 0.05 (FA 0.83 MA 0.17 ) 0.96 Pb(I 0.95 Br 0.05 ) 3 A photoelectric conversion layer having a thickness of 500 nm was formed.

[0078] [Formation of Charge Transport Layer] 0.1g of the particles 1 and 0.01g of a calixarene compound (JP Patent Publication 2003-207913) were mixed with 10.6g of 2-propanol, 11g of zirconia beads were enclosed in this mixture, and dispersion was performed for 6 hours using a paint shaker (manufactured by Toyo Seiki Co., Ltd.). Then, 0.2g of resin solution 1 was added, and dispersion was performed again for 6 hours using a paint shaker to prepare a charge transport layer coating liquid. This charge transport layer coating liquid was spin-coated on the photoelectric conversion layer to form a charge transport layer having a thickness of 150nm.

[0079] [Introduction of a second charge transport layer] 0.15 g of Spiro-OMeTAD as a material for the second charge transport layer was dissolved in 2.2 g of chlorobenzene. 36 μL of an acetonitrile solution obtained by dissolving 0.2 g of lithium bis(trifluoromethanesulfonyl)imide in 0.3 g of acetonitrile and 60 μL of 4-tert-butylpyridine (TBP) were added to this chlorobenzene solution and mixed. Furthermore, 58 μL of an acetonitrile solution obtained by dissolving 0.11 g of [tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(3)tris(bis(trifluoromethylsulfonyl)imide)] in 0.3 g of acetonitrile was mixed to prepare a material solution for the second charge transport layer. This was applied by spin coating on the charge transport layer to form a second charge transport layer with a thickness of 200 nm.

[0080] [Formation of the first electrode] On the second charge transport layer, a layer having a thickness of 80 nm and an area of ​​0.09 cm 2 A gold electrode was formed by vacuum deposition to obtain a photoelectric conversion element.

[0081] [Analysis of compound amounts] The electrode surface of the photoelectric conversion element was peeled off to expose the charge transport layer surface. The charge transport layer surface was wiped with a cotton swab soaked in a solvent, dissolved in heavy water sulfuric acid, and 1H-NMR measurement (apparatus: AVANCE3-500, manufactured by BRUKER) was performed. In addition, the peeled off charge transport layer components were subjected to mass and structure analysis by elemental analysis such as GPC, MALDI-TOF-MS, IR, gas chromatography, XPS, and EDX to confirm the presence of compounds. The film thickness was confirmed by cutting the photoelectric conversion element, fixing it to an inclined sample stage, and then performing cross-sectional SEM (equipment: Carl Zeiss SmartSEM). The crystallinity of the material was confirmed by confirming the diffraction peaks using XRD measurement (equipment: Rigaku Corporation X-ray diffraction equipment RINT-TTRII).

[0082] Example 2 A photoelectric conversion element is obtained in the same manner as in Example 1, except that a polyvinyl butyral resin (product name: BM-S, manufactured by Sekisui Chemical Co., Ltd., glass transition temperature 67°C) having a different ratio of hydroxyl groups is used as the aliphatic resin having hydroxyl groups.

[0083] Example 3 Between the charge transport layer and the photoelectric conversion layer, 2.49 mg of 2-phenethylethylamine hydroiodide is dissolved in 1 mL of 2-propanol to prepare a solution for the thin film layer, and the solution for the thin film layer is spin-coated on the photoelectric conversion layer to form a thin film layer having a thickness of 20 nm. A photoelectric conversion element is obtained in the same manner as in Example 1 except for the above.

[0084] Example 4 The cyclic conjugated compound formed by conjugating a plurality of pyrrole rings is changed to chlorogallium phthalocyanine (ClGaPc), and a photoelectric conversion element is obtained in the same manner as in Example 1.

[0085] Example 5 The cyclic conjugated compound formed by conjugating a plurality of pyrrole rings is changed to copper phthalocyanine (CuPc), and a photoelectric conversion element is obtained in the same manner as in Example 1.

[0086] Example 6 The cyclic conjugated compound formed by conjugating a plurality of pyrrole rings is changed to titanyl phthalocyanine (TiOPc), and a photoelectric conversion element is obtained in the same manner as in Example 1.

[0087] Example 7 The cyclic conjugated compound formed by conjugating a plurality of pyrrole rings is changed to zinc phthalocyanine (ZnPc), and a photoelectric conversion element is obtained in the same manner as in Example 1.

[0088] Example 8 The cyclic conjugated compound formed by conjugating a plurality of pyrrole rings is treated with silicon phthalocyanine dichloride (SiPcCl 2 ) is changed. A photoelectric conversion element is obtained in the same manner as in Example 1 except for the above.

[0089] Example 9 The cyclic conjugated compound formed by conjugating a plurality of pyrrole rings is changed to ligand-free phthalocyanine (Pc), and otherwise a photoelectric conversion element is obtained in the same manner as in Example 1.

[0090] Example 10 The cyclic conjugated compound formed by conjugating a plurality of pyrrole rings is changed to tetraphenylporphyrin (TPP), and otherwise a photoelectric conversion element is obtained in the same manner as in Example 1.

[0091] Example 11 A photoelectric conversion element is obtained in the same manner as in Example 1, except that 0.2 g of the particles 1 is used in the preparation of the charge transport layer coating solution 1.

[0092] Example 12 A photoelectric conversion element is obtained in the same manner as in Example 1, except that 0.08 g of the particles 1 is used in the preparation of the charge transport layer coating solution 1.

[0093] Example 13 A photoelectric conversion element is obtained in the same manner as in Example 1, except that 0.3 g of the particles 1 is used in preparing the charge transport layer coating solution 1.

[0094] Example 14 A photoelectric conversion element is obtained in the same manner as in Example 1, except that 0.05 g of the particles 1 is used in the preparation of the charge transport layer coating solution 1.

[0095] Example 15 A photoelectric conversion element is obtained in the same manner as in Example 1, except that 0.35 g of the particles 1 is used in the preparation of the charge transport layer coating solution 1.

[0096] Example 16 A photoelectric conversion element is obtained in the same manner as in Example 1, except that 0.02 g of the particles 1 is used in preparing the charge transport layer coating solution 1.

[0097] (Example 17) In the preparation of the resin solution 1, the aliphatic resin having a hydroxyl group is changed to KS-10 (manufactured by Sekisui Chemical Co., Ltd., glass transition temperature 105° C.) Except for this, a photoelectric conversion element is obtained in the same manner as in Example 1.

[0098] (Example 18) In preparing the resin solution 1, the resin solution is changed to PBMA (a compound represented by the following formula (E-1)), which is an aliphatic resin having a carboxy group. A photoelectric conversion element is obtained in the same manner as in Example 1 except for the above. [ka]

[0099] (Example 19) In preparing the resin solution 1, the resin solution is changed to PHM (a compound represented by the following formula (E-2)), which is an aliphatic resin having a hydroxyl group. A photoelectric conversion element is obtained in the same manner as in Example 1 except for the above. [ka]

[0100] (Example 20) In preparing the resin solution 1, the resin solution is changed to PVA (a compound represented by the following formula (E-3)), which is an aliphatic resin having a hydroxyl group. A photoelectric conversion element is obtained in the same manner as in Example 1 except for the above. [ka]

[0101] Example 21 In preparing the resin solution 1, the resin solution is changed to PMMMA (a compound represented by the following formula (E-4)), which is an aliphatic resin having a hydroxyl group. A photoelectric conversion element is obtained in the same manner as in Example 1 except for the above. [ka]

[0102] Example 22 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the second charge transport layer is not used.

[0103] (Example 23) In the preparation of the resin solution 1, the aliphatic resin having a hydroxyl group is changed to BX-1 (manufactured by Sekisui Chemical Co., Ltd., glass transition temperature 95° C.) Except for this, a photoelectric conversion element is obtained in the same manner as in Example 1.

[0104] Example 24 In the preparation of the resin solution 1, the resin solution is changed to polyacrylic acid (weight molecular weight 25000, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), which is an aliphatic resin having a carboxy group, and 2-propanol is changed to ethanol. A photoelectric conversion element is obtained in the same manner as in Example 1 except for the above.

[0105] Comparative Example 1 A photoelectric conversion element was obtained in the same manner as in Example 1, except that in preparing the resin solution 1, an aliphatic resin having at least one group selected from the group consisting of a hydroxyl group or a carboxyl group was not used (i.e., resin solution 1 was not used).

[0106] Comparative Example 2 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating liquid, a cyclic conjugated compound in which a plurality of pyrrole rings are conjugated is not used.

[0107] Comparative Example 3 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the charge transport layer coating solution, a cyclic conjugated compound formed by conjugating a plurality of pyrrole rings is not used, and instead, Spiro-OMeTAD is used.

[0108] Comparative Example 4 In preparing the resin solution 1, a photoelectric conversion element is obtained in the same manner as in Example 1, except that an aliphatic resin having at least one group selected from the group consisting of a hydroxyl group and a carboxyl group is not used, and instead, poly(3-hexylthiophene-2,5-diyl) P3HT (Sigma-Aldrich, glass transition temperature 9.3°C) is used.

[0109] Comparative Example 5 In the preparation of the resin solution 1, the aliphatic resin having at least one group selected from the group consisting of a hydroxyl group and a carboxyl group is changed to Kureha KF polymer (manufactured by Kuraray Co., Ltd., glass transition temperature -35°C). A photoelectric conversion element is obtained in the same manner as in Example 1 except for the above.

[0110] Comparative Example 6 In the preparation of the resin solution 1, the aliphatic resin having at least one group selected from the group consisting of a hydroxyl group and a carboxyl group is changed to PSTFSI (a compound represented by the following formula (E-5)). Furthermore, a photoelectric conversion element is obtained in the same manner as in Example 1, except that the cyclic conjugated compound formed by conjugating the multiple pyrrole rings is changed to copper phthalocyanine (CuPc). [ka]

[0111] Comparative Example 7 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in the preparation of the resin solution 1, the aliphatic resin having at least one group selected from the group consisting of a hydroxy group and a carboxy group is changed to PSTFSI.

[0112] Table 2 shows the specific configuration of the charge transport layer and the presence or absence of the second charge transport layer and the thin film layer in the photoelectric conversion elements produced in Examples 1 to 24 and Comparative Examples 1 to 7.

[0113] [evaluation] The photoelectric conversion elements obtained in each of the examples and comparative examples were evaluated as follows. (Power generation efficiency evaluation) In Example 1, a power supply (KEITHLEY, Model 236) was connected between the electrodes of the photoelectric conversion element, and the intensity was 100 mW / cm 2 A constant amount of light was irradiated using a solar simulator (manufactured by Yamashita Denso Co., Ltd.) and the generated current and voltage were measured to evaluate the photoelectric conversion efficiency. The series resistance was calculated by approximating the inverse of the slope of the obtained current-voltage curve near Voc, and the shunt resistance was calculated by approximating the inverse of the slope of the obtained current-voltage curve near Jsc. The leakage resistance was evaluated from the series resistance value and the shunt resistance value. The photoelectric conversion efficiency was calculated by evaluating Examples 2 to 24 and Comparative Examples 1 to 7 in the same manner as in Example 1. The results are shown as relative values ​​when the result of Example 1 is set to 1. The results are shown in Table 3.

[0114] [Table 2]

[0115] [Table 3]

[0116] The disclosure of this embodiment includes the following configuration. (Configuration 1) A photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer including a crystal having a perovskite structure and disposed between the first electrode and the second electrode, a charge transport layer between the photoelectric conversion layer and the first electrode, the charge transport layer including a cyclic conjugated compound formed by conjugating a plurality of pyrrole rings and an aliphatic resin having at least one functional group selected from the group consisting of a hydroxy group and a carboxy group. (Configuration 2) The photoelectric conversion element according to configuration 1, further comprising a second charge transport layer between the first electrode and the charge transport layer. (Configuration 3) The photoelectric conversion element according to configuration 2, wherein the second charge transport layer contains a spirofluorene compound. (Configuration 4) The photoelectric conversion element according to any one of configurations 1 to 3, wherein the aliphatic resin having at least one functional group selected from the group consisting of a hydroxy group and a carboxy group further has at least one functional group selected from the group consisting of a carbonyl group, an ester group, an ether group, a carboxy group, a methoxy group, an amino group, a sulfo group, an aldehyde group, an amide group, and a sulfide group. Carboxy group (Configuration 5) 5. The photoelectric conversion element according to any one of configurations 1 to 4, wherein the content by mass of the cyclic conjugated compound in the charge transport layer is 5 to 30 times the content by mass of the aliphatic resin in the charge transport layer. (Configuration 6) 6. The photoelectric conversion element according to any one of configurations 1 to 5, wherein the mass of the cyclic conjugated compound in the charge transport layer is 8 to 20 times the mass of the aliphatic resin in the charge transport layer. (Configuration 7) The photoelectric conversion element according to any one of configurations 1 to 6, wherein the cyclic conjugated compound is a phthalocyanine compound. (Configuration 8) The photoelectric conversion element according to configuration 7, wherein the phthalocyanine compound has a central element. (Configuration 9) The photoelectric conversion element according to configuration 7 or 8, wherein the phthalocyanine compound is a metal phthalocyanine compound. (Configuration 10) 10. The photoelectric conversion element according to configuration 9, wherein the metal phthalocyanine compound is a gallium phthalocyanine compound. (Configuration 11) 11. The photoelectric conversion element according to configuration 10, wherein the gallium phthalocyanine compound is a hydroxygallium phthalocyanine compound. (Configuration 12) 12. The photoelectric conversion element according to any one of configurations 1 to 11, wherein the aliphatic resin having at least one functional group selected from the group consisting of a hydroxy group and a carboxy group has a glass transition temperature of 95° C. or lower. (Configuration 13) A photoelectric conversion device comprising the photoelectric conversion element according to any one of configurations 1 to 12. [Explanation of symbols]

[0117] 1 Photoelectric conversion element 2. Board 3 Second electrode 4 Electron transport layer 5 Photoelectric conversion layer 6 Charge transport layer 7 First electrode

Claims

1. A photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer including a crystal having a perovskite structure and disposed between the first electrode and the second electrode, a charge transport layer between the photoelectric conversion layer and the first electrode, the charge transport layer including a cyclic conjugated compound formed by conjugating a plurality of pyrrole rings and an aliphatic resin having at least one functional group selected from the group consisting of a hydroxy group and a carboxy group.

2. The photoelectric conversion element according to claim 1 , further comprising a second charge transport layer between the first electrode and the charge transport layer.

3. The photoelectric conversion element according to claim 2 , wherein the second charge transport layer comprises a spirofluorene compound.

4. 2. The photoelectric conversion element according to claim 1, wherein the aliphatic resin further has at least one functional group selected from the group consisting of a carbonyl group, an ester group, an ether group, a carboxy group, a methoxy group, an amino group, a sulfo group, an aldehyde group, an amide group, and a sulfide group.

5. 2. The photoelectric conversion element according to claim 1, wherein the mass of said cyclic conjugated compound in said charge transport layer is 5 to 30 times the mass of said aliphatic resin in said charge transport layer.

6. 2. The photoelectric conversion element according to claim 1, wherein the mass of said cyclic conjugated compound in said charge transport layer is 8 to 20 times the mass of said aliphatic resin in said charge transport layer.

7. The photoelectric conversion element according to claim 1 , wherein the cyclic conjugated compound is a phthalocyanine compound.

8. The photoelectric conversion element according to claim 7 , wherein the phthalocyanine compound has a central element.

9. The photoelectric conversion element according to claim 7 , wherein the phthalocyanine compound is a metal phthalocyanine compound.

10. The photoelectric conversion element according to claim 9 , wherein the metal phthalocyanine compound is a gallium phthalocyanine compound.

11. The photoelectric conversion element according to claim 10 , wherein the gallium phthalocyanine compound is a hydroxygallium phthalocyanine compound.

12. 2. The photoelectric conversion element according to claim 1, wherein the aliphatic resin has a glass transition temperature of 95° C. or lower.

13. A photoelectric conversion device comprising the photoelectric conversion element according to any one of claims 1 to 12.

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