Photoelectric conversion element, photoelectric conversion device, mobile body, and building material

Abstract

The present invention addresses the problem of providing a photoelectric conversion element (1) which has improved durability and photoelectric conversion efficiency thereof. In order to solve the problem, the present invention comprises a photoelectric conversion element (1) which comprises a first electrode (7), a second electrode (3), and a photoelectric conversion layer (5) that is disposed between the first electrode (7) and the second electrode (3) and contains a crystal having a perovskite structure. The photoelectric conversion element (1) is characterized in that: the photoelectric conversion element (1) comprises a charge transport layer (6) between the photoelectric conversion layer (5) and the first electrode (7); the charge transport layer (6) has a P-type semiconductor crystal and a resin; and the P-type semiconductor crystal comprises at least one functional group that is selected from the group consisting of a hydroxy group, a carboxy group, an amino group, an imino group, and a sulfo group.

Description

Photoelectric conversion element, photoelectric conversion device, mobile body, and building material

[0001] The present invention relates to a photoelectric conversion element, a photoelectric conversion device, a mobile object, and a building material.

[0002] In order to solve the problems 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 hydropower. Among these, interest is growing in solar cells that directly convert sunlight into electrical energy. Here, a solar cell refers to a cell that generates current and voltage by absorbing light energy from sunlight and utilizing the photovoltaic effect, in which electrons and holes are generated.

[0003] Currently, n-p 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 solar power generation. However, these require high-temperature processing steps and the materials themselves are expensive, resulting in high costs per unit of power. Furthermore, there are also supply issues due to the limited 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 in a so-called roll-to-roll method, which is expected to reduce costs. However, further improvements in power generation efficiency and durability are desired for the practical use of organic solar cells. In particular, perovskite solar cells, which have crystals with a perovskite structure as a photoelectric conversion layer, have excellent photoelectric conversion characteristics, and development is underway toward the practical use of solar cells.

[0005] For example, Patent Document 1 describes a technique for improving peeling from the electrode by including an organic semiconductor and a polymer compound having a glass transition temperature of 100° C. or higher in the hole transport layer. Non-Patent Document 1 describes improving conversion efficiency by mixing copper phthalocyanine and a conductive polymer in the hole transport layer.

[0006] JP 2018-170382 A

[0007] Q. Hu, et al. Sol. RRL,2019,3,1800264

[0008] According to the inventors' investigations, it was found that there is room for improvement in the durability and photoelectric conversion efficiency of the photoelectric conversion elements described in Patent Document 1 and Non-Patent Document 1. Therefore, an object of the present invention is to provide a photoelectric conversion element with improved durability and photoelectric conversion efficiency. Another object of the present invention is to provide a photoelectric conversion device.

[0009] The present invention relates to a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a crystal of a perovskite structure and disposed between the first electrode and the second electrode, wherein the photoelectric conversion element has a charge transport layer between the photoelectric conversion layer and the first electrode, the charge transport layer containing a P-type semiconductor crystal and a resin, and the P-type semiconductor crystal has at least one functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, an imino group, and a sulfo group.The present invention also relates to a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a crystal of a perovskite structure and disposed between the first electrode and the second electrode, wherein the photoelectric conversion element has a charge transport layer between the photoelectric conversion layer and the first electrode, the charge transport layer containing a P-type semiconductor crystal and a resin, and the P-type semiconductor crystal has a functional group that can act as a hydrogen bond donor. The present invention also relates to a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a crystal of a perovskite structure and disposed between the first electrode and the second electrode, wherein the photoelectric conversion element has a charge transport layer between the photoelectric conversion layer and the first electrode, the charge transport layer containing a P-type semiconductor crystal and a resin, and the P-type semiconductor crystal having a Lewis basic functional group. The present invention also relates to a photoelectric conversion device having the above-described photoelectric conversion element. The present invention also relates to a mobile object having the above-described photoelectric conversion element. The present invention also relates to a building material having the above-described photoelectric conversion element.

[0010] According to the present invention, it is possible to provide a photoelectric conversion element having improved durability and photoelectric conversion efficiency.

[0011] 1 is a schematic diagram of a layer structure in a thickness direction of one embodiment of a photoelectric conversion element of the present invention; 2 is a perspective view schematically showing one embodiment of a moving body including a photoelectric conversion element of the present invention; 3 is a perspective view schematically showing one embodiment of a building material including a photoelectric conversion element of the present invention;

[0012] <One Embodiment> One embodiment relates to a 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 and disposed between the first electrode and the second electrode, characterized in that a charge transport layer is disposed between the photoelectric conversion layer and the first electrode, the charge transport layer containing a P-type semiconductor crystal and a resin, and the P-type semiconductor crystal has at least one functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, an imino group, and a sulfo group. The photoelectric conversion element of the present invention is also a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing a crystal of a perovskite structure and disposed between the first electrode and the second electrode, characterized in that a charge transport layer is disposed between the photoelectric conversion layer and the first electrode, the charge transport layer containing a P-type semiconductor crystal and a resin, and the P-type semiconductor crystal has a functional group that can act as a hydrogen bond donor. 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 with a perovskite structure and 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, the charge transport layer contains a P-type semiconductor crystal and a resin, and the P-type semiconductor crystal has a Lewis basic functional group.

[0013] As a result of investigations, the present inventors have found that the inclusion of the above-described charge transport layer results in a photoelectric conversion element having excellent durability and conversion efficiency. The reasons for this are believed to be as follows.

[0014] On the perovskite surface, undercoordinated Pb ２＋ions, Pb clusters, iodine vacancies, organic A cation vacancies, under-coordinated I － These surface defects include several types of defects, such as ions. These surface defects can cause electron-hole recombination through non-radiative channels, which can lead to degradation of the photovoltaic device and a decrease in conversion efficiency. In addition, in perovskite solar cells, external water molecules and ions and molecules that make up the photovoltaic device can migrate to other layers, destroying the structure of the photovoltaic device.

[0015] In response to this, it is believed that the deterioration of durability and conversion efficiency can be prevented by incorporating a P-type semiconductor crystal having a Lewis basic functional group or a functional group that can act as a hydrogen bond donor into the charge transport layer in contact with the photoelectric conversion layer. This is because the Lewis acidic defects present on the perovskite surface are passivated by interaction with the Lewis base, and the hydrogen atoms contained in the functional group are used to convert under-coordinated I. － Furthermore, because the defects in the crystals of the perovskite structure are several tens to several hundreds of nanometers in size, it was found that even when a hole transport layer or an insulating layer of several tens of nanometers is introduced between the charge transport layer and the photoelectric conversion layer of the present invention, it contributes to improving durability and conversion efficiency.

[0016] Furthermore, by including P-type semiconductor crystals and a resin in the charge transport layer, it is thought that the functional groups of the resin interact with defects on the perovskite surface that cannot be compensated for by P-type semiconductor crystals alone. Furthermore, P-type semiconductor crystals, which have high charge transport properties and hole mobility, do not hinder charge transport even when formed into thick films, and by including a resin therein, the photoelectric conversion layer can be reliably coated, thereby improving durability while maintaining charge transport.

[0017] As explained above, the effects of the present invention can be achieved by the synergistic effects of the various components.

[0018] 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 those skilled in the art without departing from the spirit of the present invention are also included in the scope of the present invention.

[0019] In this specification, the term "layer" refers not only to a layer with clear boundaries or a flat, thin-film layer, but also to a layer with a gradually changing concentration gradient of contained elements, or to a layer that can form a complex, intricate structure together with other layers. Elemental analysis of a layer can be performed, for example, by performing TOF-SIMS / FE-TEM / EDS line analysis of a cross section of a photoelectric conversion element to confirm the element distribution of a specific element. Analysis of each layer may be performed by peeling and removing the completed element to expose the layer to be analyzed. The volume ratio can also be quantified by using the area ratio of the exposed surface or cross section as the volume ratio of that layer.

[0020] 1 is a cross-sectional view schematically illustrating the configuration of one embodiment of the photoelectric conversion element of the present invention. The element has a second electrode 3, an electron transport layer 4, a photoelectric conversion layer 5, a charge transport layer 6, and a first electrode 7 on a substrate 2. One of the first electrode 7 and the second electrode 3 is an anode and the other is a cathode, and current can be extracted by connecting the first electrode 7 and the second electrode 3 to an external circuit.

[0021] 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 through 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 two electrodes (the second electrode 3 and the first electrode 7), and may not be formed in some cases. A structure in which multiple electron transport layers 4 and photoelectric conversion layers 5 are stacked may be used. Such a structure may also be called a tandem structure. Each component will be described below. Alternatively, 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.

[0022] [Photoelectric Conversion Element] The photoelectric conversion element of the present invention is characterized by 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. Furthermore, in order to improve photoelectric conversion efficiency, the photoelectric conversion elements may be stacked in a tandem configuration. The photoelectric conversion elements to be stacked are not limited to a specific type of photoelectric conversion element, and may include perovskite solar cells that use perovskite crystals in the photoelectric conversion layer, silicon solar cells, CIGS solar cells, and the like.

[0023] Methods for forming each layer of the photoelectric conversion element of the present invention include coating methods and vapor deposition methods. Examples of coating methods include dip coating, spin coating, spray coating, inkjet coating, meniscus coating, screen coating, roll coating, die coating, blade coating, curtain coating, and wire bar coating. The coating method involves preparing a coating solution for each layer described below, applying the solution in the desired layer order, and drying the solution. A desired method can be selected from these film formation methods depending on the layer. Each layer will be described below.

[0024] [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, a transparent plastic substrate, etc. 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.

[0025] [Electrodes] There are no particular limitations on the materials for the first electrode 7 and the second electrode 3, and conventionally known materials can be used. For example, metals such as gold, silver, titanium, and copper, sodium, sodium-potassium alloy, lithium, magnesium, carbon, aluminum, magnesium-silver mixture, magnesium-indium mixture, aluminum-lithium alloy, and Al / Al ２ O ３ Examples of suitable materials include a mixture of Al and LiF, and an Al / LiF mixture.

[0026] Transparent electrode materials include, for example, CuI, ITO (indium tin oxide), and SnO ２Examples 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), as well as conductive transparent polymers.

[0027] These materials may be used alone or in combination of two or more. At least one of the first electrode 7 and the second electrode 3 on the light incident side is a transparent electrode, and the other may be a transparent electrode or may double as a reflective layer formed of a light-reflective material, or may be a transparent electrode 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 electrodes may be patterned electrodes.

[0028] [Photoelectric Conversion Layer] The photoelectric conversion layer 5 has a crystal with a perovskite structure. The crystal with a perovskite structure used in the present invention is preferably represented by the following general formula [1]: ABX ３ [1] In the above general formula [1], 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.

[0029] As A in the general formula [1], for example, in the case of an organic molecule, it is preferable that it is represented by CpNqHr (p, q, and r are all positive integers). Specific examples include methylammonium and formamidium.

[0030] 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.

[0031] If the constituent cation A is too large to fit within the three-dimensional perovskite crystal, it will form a two-dimensional perovskite crystal, a 2.5-dimensional perovskite crystal having properties of both two and three dimensions, a bilayer crystal of three-dimensional and two-dimensional perovskite structures, or a mixed three-dimensional and two-dimensional perovskite crystal, all of which will function as a photoelectric conversion layer.

[0032] A two-layer crystal of three-dimensional and two-dimensional perovskite refers to a crystal in which crystals with three-dimensional and two-dimensional perovskite structures are stacked as independent, separate layers, while a mixed three-dimensional / two-dimensional perovskite refers to a crystal with a structure in which both regions or domains of two-dimensional or 2.5-dimensional layered and three-dimensional perovskite structure crystals are mixed.

[0033] The crystal of the two-dimensional perovskite or 2.5-dimensional perovskite structure is preferably represented by the following general formulas [2] to [4] (n is a positive integer): R' ２ A ｎ－１ B ｎ X ３ｎ＋１ [2] R''A ｎ－１ B ｎ X ３ｎ＋１ [3] R'''A ｎ B ｎ X ３ｎ＋１ [4] In the above general formulas, [2] forms an RP (Ruddlesden-Popper) type perovskite structure, [3] forms a DJ (Dion-Jacobson) type perovskite structure, and [4] forms an ACI (Alternating cations in the interlayer) type perovskite structure.

[0034] R', R'', and R''' in the above general formulas [2] to [4] are organic molecules or metal cations which may have a substituent, and specific examples thereof include ethylammonium, propylammonium, n-butylammonium, n-hexylammonium, n-octylammonium, 1,6-hexadiammonium, isobutylammonium, 3-(nonafluoro-tert-butyloxy)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, guanidium, propylammonium, propargylamine, alkylammonium, cyclohexylmethylammonium, 4-(aminomethyl)piperidinium, piperidinium, pyrrolidinium ... xylammonium, 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-propene-1-ammonium, phenylbutylammonium, 4-tert-butyl - benzylammonium, 3- (aminomethyl) piperidinium, 4- (aminomethyl) piperidinium is preferred.

[0035] In the above general formulas [1] to [4], B is a metal atom, such as lead, tin, bismuth, zinc, titanium, antimony, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, and europium. Among these, lead, tin, and bismuth are preferred from the viewpoint of electron orbital overlap. These metal atoms may be used alone or in combination of two or more.

[0036] X in the above general formulas [1] to [4] is a halogen atom, such as chlorine, bromine, or iodine. These halogen atoms may be used alone or in combination of two or more. Among these, halogen atoms are preferred because the inclusion of halogen in the structure makes the perovskite structure crystal more soluble in organic solvents, enabling application to inexpensive printing methods, etc. Furthermore, iodine is more preferred because it narrows the energy band gap of the perovskite structure crystal.

[0037] Specifically, 3D perovskite, 2D perovskite, and mixed 3D / 2D perovskite are MAPbI ３ and FAPbCl ３ , FAPbI ３ , MAPbI ｘ Br ３－ｘ , MAPbI ｘ Cl ３－ｘ , Cs ０．１ (MA ０．１７ FA ０．８３ ) ０．９ Pb(I ０．９ Br ０．１ ) ３、 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 FA０．８８ 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 PbI ３ ,Csx(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 、(4FFEA) ２ (FA ０．３ MA ０．７ ) ４ Pb ５ I １６ 、(PDMA)FA ２ Pb ３ I １０ 、(3AAMPY)(MA) ３ Pb ４ I １３ 、(PDMA)MA ５ Pb ６ I １９ 、(PDMA)MA ３ Pb ４ I １３ 、(TTDMA)MA ３ Pb ４ I １３ 、(TTDMA)MA ４ Pb ５ I １６ 、 (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 、(4FFEA) ２ MA ３ Pb ４ I １３ 、(4FFEA) ２ MA ４ Pb ５ I １６ 、(BA) ２ MA ２ Pb ３ I １０ 、(BA) ２ MA ３ Pb ４ I １３ 、(TEA) ２ MA ２ Pb ３ I １０ 、(BA) ２ MA ４ Pb ５ I１６ , (BA) ２ MA ３ Pb ４ I １３ is preferred.

[0038] Depending on the purpose, the A site, B site, or X site in the above general formula may be adjusted to be insufficient or excessive, and the combination of x1 to x5 may be changed depending on the purpose. Particularly preferred ranges 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 also be included as a material for forming perovskite crystals.

[0039]

[0040] 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-diyldimethaneammonium, "4FPEA" represents 4-fluorophenethylammonium, "BA" represents butylammonium, and "TEA" represents 2-thiophenethylammonium.

[0041] The perovskite crystal 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 such a structure allows the orientation of the octahedra in the crystal lattice to be easily changed, thereby increasing the mobility of electrons in the perovskite crystal and improving the photoelectric conversion efficiency of the photoelectric conversion element.

[0042] The organic-inorganic perovskite compound used in the present invention is preferably a crystalline semiconductor. A crystalline semiconductor refers to a semiconductor from which a scattering peak can be detected by measuring an X-ray scattering intensity distribution. When the organic-inorganic perovskite compound is a crystalline semiconductor, the mobility of electrons in the organic-inorganic perovskite compound increases, improving the photoelectric conversion efficiency of the photoelectric conversion element.

[0043] The thickness of the photoelectric conversion layer according to the present invention is preferably 5 nm or more and 2000 nm or less. A thickness of 5 nm or more allows sufficient absorption of light, and a thickness of 2000 nm or less allows generated charges to be transported to each electrode. A more preferred lower limit is 50 nm or more, a more preferred upper limit is 1200 nm, an even more preferred lower limit is 100 nm, and an even more preferred upper limit is 1000 nm.

[0044] [Charge Transport Layer] The photoelectric conversion element of the present invention has a charge transport layer between the photoelectric conversion layer and the first electrode. The charge transport layer of the photoelectric conversion element of the present invention contains a P-type semiconductor crystal as a charge transport material and a resin. In the photoelectric conversion element of the present invention, the P-type semiconductor crystal has a Lewis basic functional group, more specifically, a functional group capable of acting as a hydrogen bond donor, and at least one functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, an imino group, and a sulfo group. These functional groups can be confirmed, for example, using X-ray photoelectron spectroscopy (XPS) or nuclear magnetic resonance (NMR).

[0045] In the photoelectric conversion element of the present invention, the charge transport layer is preferably in contact with the photoelectric conversion layer, which not only traps ions migrated from the photoelectric conversion layer but also directly interacts with defects on the surface of the perovskite that is the photoelectric conversion layer, thereby enhancing the effect of preventing carrier recombination.

[0046] In the photoelectric conversion element of the present invention, the P-type semiconductor crystals are preferably dispersed in the resin, which facilitates uniform contact between the charge transport material and the resin, thereby enabling the formation of an effective charge distribution.

[0047] From the viewpoint of durability of charge transportability, the photoelectric conversion element of the present invention preferably has a mass ratio of the P-type semiconductor crystal to the resin in the charge transport layer of 5 to 30 times. The mass ratio of the P-type semiconductor crystal and the resin can be confirmed using, for example, X-ray photoelectron spectroscopy (XPS) or energy dispersive spectroscopy (EDS).

[0048] In the photoelectric conversion element of the present invention, from the viewpoint of durability, the thickness of the charge transport layer is preferably 10 nm to 400 nm, more preferably 100 nm to 200 nm. The thickness of the charge transport layer can be confirmed, for example, by observing a cross section of the photoelectric conversion element with a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

[0049] In the photoelectric conversion element of the present invention, the resin is preferably a polyvinyl acetal resin, more preferably a polyvinyl butyral resin. It is believed that this resin is likely to come into close contact with the charge transport material, and that the ions constituting the perovskite interact with the functional groups of the resin. In the present invention, the chemical substance can be identified, for example, by nuclear magnetic resonance (NMR).

[0050] In the photoelectric conversion element of the present invention, from the viewpoint of charge transportability, the P-type semiconductor crystal is preferably a cyclic conjugated compound formed by conjugating a plurality of pyrrole rings. In the present invention, the chemical substance can be identified by, for example, nuclear magnetic resonance (NMR) spectroscopy.

[0051] 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 solvents used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, thioether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, alcohol-based solvents and aromatic hydrocarbon-based solvents are preferred.

[0052] [Second Charge Transport Layer] The photoelectric conversion element of the present invention may have a second charge transport layer between the first electrode and the charge transport layer. The presence of the second charge transport layer may facilitate the transfer of carriers to the electrode. The material for 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, and thiocyanate compounds. In particular, from the viewpoint of compatibility at the film interface, those having an aromatic ring are preferred, and Spiro-OMeTAD, PTAA, and phthalocyanine compounds are preferred.

[0053] [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 .

[0054] 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, perylene derivatives, 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.

[0055] The thickness of the electron transport layer 4 is preferably 1 nm or more at the lower limit and 2000 nm or more at the upper limit. A thickness of 1 nm or more ensures sufficient hole blocking, while a thickness of 2000 nm or less reduces resistance during electron transport, resulting in high photoelectric conversion efficiency. The thickness is more preferably 3 nm or less at the lower limit and 1000 nm or less at the upper limit, and even more preferably 5 nm or less at the lower limit and 500 nm or less at the upper limit.

[0056] <Application Examples> Application examples of the present invention are photoelectric conversion devices, moving bodies, and building materials.

[0057] [Photoelectric Conversion Device] The photoelectric conversion device of the present invention has the photoelectric conversion element described above. A photoelectric conversion device can be constructed by using a plurality of photoelectric conversion elements of the present invention. When a plurality of photoelectric conversion elements are connected, the photoelectric conversion device can also be called a photoelectric conversion cell or a photoelectric conversion module. The photoelectric conversion element may be a stack of photoelectric conversion elements with different absorption wavelengths to increase the output voltage. The photoelectric conversion device also has 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. Examples include secondary batteries using lithium ions or the like, all-solid-state batteries, and electric double layer capacitors.

[0058] [Mobile object] The mobile object of the present invention has the photoelectric conversion element described above. FIG. 2 is a perspective view schematically showing one embodiment of a mobile object equipped with the photoelectric conversion element of the present invention. The mobile object 30 has a photoelectric conversion element 31 of the present invention and a body 32 equipped with the photoelectric conversion element 31. The photoelectric conversion element 31 is disposed in a position on the body 32 where it can receive external light. If the mobile object 30 is an automobile, it may be disposed on the roof. The electrical energy obtained by the photoelectric conversion element 31 may power the mobile object 30 or may power other electrical equipment. Electrical energy generated from the power of the mobile object 30 may be used to power the photoelectric conversion element 31. If the mobile object 30 is an automobile, frictional energy generated by braking may be converted into electrical energy and used to control the photoelectric conversion element 31.

[0059] The mobile body 30 may be, for example, an automobile, a ship, an airplane, or a drone. The configuration of the body 32 of the mobile body 30 is not particularly limited, but it is preferably made of a high-strength material.

[0060] [Building Material] The building material of the present invention has the photoelectric conversion element described above. Fig. 3 is a perspective view schematically showing one embodiment of a building material including the 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 the 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 exterior coverings 44a and 44b.

[0061] 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, sunlight may increase the temperature of the photoelectric conversion element 41, potentially reducing the photoelectric conversion efficiency. The use of the heat dissipation member 43 can reduce the reduction in photoelectric conversion efficiency. Examples of the heat dissipation member 43 include a metal, an alloy, a liquid metal, and a liquid resin.

[0062] The building material 40 of the present invention may also have exterior coatings 44a and 44b. The exterior coatings 44a and 44b may emit different colors or may be the same. 44a and 44b may be made of the same material or different materials. Paint or a transparent substrate may be used as the exterior coating. A material with low light absorption and high heat insulation properties is preferred.

[0063] 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.

[0064] <Preparation of P-Type Semiconductor Crystal Particles 1> Step (1) Under a nitrogen flow atmosphere, 5.46 parts of orthophthalonitrile and 45 parts of α-chloronaphthalene were charged into a reaction vessel, and the mixture was heated to a temperature of 30°C and maintained at this temperature. Next, 3.75 parts of gallium trichloride was charged at this temperature (30°C). The water concentration of the mixture at the time of charging was 150 ppm.

[0065] The temperature was then raised to 200°C. Next, the mixture was reacted at 200°C for 4.5 hours under a nitrogen flow atmosphere, and then cooled. When the temperature reached 150°C, the product was filtered. The resulting filtrate was dispersed and washed using N,N-dimethylformamide at 140°C for 2 hours, and then filtered. The resulting filtrate was washed with methanol and dried to obtain chlorogallium phthalocyanine particles in a yield of 71%.

[0066] Step (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., and the solution was added dropwise to 620 parts of ice water under stirring to reprecipitate, followed by filtration under reduced pressure using a filter press, No. 5C (manufactured by Advantec Co., Ltd.).

[0067] 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 filtered using a filter press three times.

[0068] Finally, freeze-drying (lyophilization) was carried out to obtain hydroxygallium phthalocyanine particles (hydrated hydroxygallium phthalocyanine particles) with a solid content of 23% by mass in a yield of 71%. These hydroxygallium phthalocyanine particles were dried in a Hyper Dry dryer (trade name: HD-06R, frequency (oscillation frequency): 2455 MHz±15 MHz, manufactured by Nippon Biocon) to obtain hydroxygallium phthalocyanine (OHGaPc) particles (crystals) with a water content of 1.0% by mass or less.

[0069] Step (3) Five parts of the hydroxygallium phthalocyanine particles were mixed with five parts of N-methylformamide solvent, and the mixture was subjected to a dispersion treatment for six hours using a sand mill (TSG-1 / 4G-4U, manufactured by Igarashi Machinery Mfg. Co., Ltd. (now Imex Co., Ltd.), disk diameter 70 mm, number of disks 5) containing five parts of glass beads, followed by filtration and drying, thereby obtaining P-type semiconductor crystal particles 1 (specific gravity 1.6).

[0070] <Preparation of Resin Solution 1> Resin solution 1 was obtained by dissolving 1.0 part of polyvinyl butyral resin (product name: S-LEC (registered trademark) BM-2, manufactured by Sekisui Chemical Co., Ltd., specific gravity 1.6) in 19 parts of 2-propanol with stirring for 24 hours.

[0071] Example 1 Formation of an Electron Transport Layer A square ITO-coated glass substrate with sides of 25 mm was cleaned, and a solution prepared by diluting a tin oxide (2) colloidal dispersion with water at a volume ratio of 1 / 7 was spin-coated onto the substrate at 5000 rpm for 30 seconds. The substrate was then heated at 150°C for 30 minutes and dried in a humid environment with an outdoor temperature of -20°C to form an electron transport layer.

[0072] [Formation of Photoelectric Conversion Layer] Lead iodide (1.2 M), lead bromide (0.15 M), formamidinium iodide (1.0 M), methylammonium bromide (0.15 M), and cesium iodide (0.13 M) were dissolved in N,N-dimethylformamide:dimethyl sulfoxide = 4:1 (volume ratio) to prepare a photoelectric conversion layer coating solution. This coating solution was spin-coated onto the electron transport layer at 2700 rpm for 10 seconds, then at 5000 rpm for 20 seconds. Five seconds before the end of spin coating, 150 μL of chlorobenzene was dropped onto the substrate. Finally, the substrate was heated at 130° C. for 15 minutes to form a Cs ０．１ (MA ０．１７ FA ０．８３ ) ０．９ Pb(I ０．９ Br ０．１ ) ３ A photoelectric conversion layer consisting of the above was formed.

[0073] [Formation of Charge Transport Layer] 0.1 parts of the P-type semiconductor crystal particles 1 and 0.01 parts of a calixarene compound (see JP 2003-207913 A) were mixed with 10.6 parts of 2-propanol. 11 parts of beads (zirconia beads, Treceram® zirconia beads, 0.3 mm) were encapsulated in this mixture, and the mixture was dispersed in a paint shaker (manufactured by Toyo Seiki Seisaku-sho). 0.2 parts of resin solution 1 was then added, and the mixture was dispersed in a paint shaker for another 4 hours to prepare a charge transport layer solution. This charge transport layer solution was spin-coated on the photoelectric conversion layer at 1000 rpm for 30 seconds and heated at 60°C for 10 minutes to form a charge transport layer with a thickness of approximately 150 nm.

[0074] [Introduction of Second Charge Transport Layer] 0.08 parts of Spiro-OMeTAD, a material for the second charge transport layer, was dissolved in 1.13 parts of chlorobenzene. This chlorobenzene solution was mixed with 0.019 parts of a 2M acetonitrile solution of lithium bis(trifluoromethanesulfonyl)imide, 0.030 parts of 4-tert-butylpyridine (TBP), and 0.016 parts of a 0.25M acetonitrile solution of [tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(3) tris(bis(trifluoromethylsulfonyl)imide)] to prepare a material solution for the second charge transport layer. This solution was applied to the charge transport layer by spin coating at 2000 rpm for 30 seconds to form a second charge transport layer.

[0075] [Formation of First Electrode] A first electrode having a thickness of 70 nm and an area of ​​0.09 cm was formed on the second charge transport layer. ２ Gold electrodes of this type were formed at 10 locations by vacuum deposition to obtain a photoelectric conversion element.

[0076] [Analysis of Compound Amount] The electrode surface of the photoelectric conversion element was peeled off to expose the charge transport layer surface. This charge transport layer surface was wiped with a cotton swab or the like soaked in a solvent, dissolved in heavy water sulfuric acid, and subjected to 1H-NMR measurement (apparatus: AVANCE3-500, manufactured by BRUKER). In addition, the peeled charge transport layer components were subjected to mass and structural analysis by elemental analysis such as GPC, MALDI-TOF-MS, IR, gas chromatography, XPS, and EDX to confirm the presence of the compound.

[0077] The film thickness was confirmed by cutting the photoelectric conversion element, fixing it on an inclined sample stage, and then using a cross-sectional SEM (apparatus: Carl Zeiss, Smart SEM).

[0078] Example 2 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the thickness of the charge transport layer is changed to 200 nm.

[0079] Example 3 A photoelectric conversion element was obtained in the same manner as in Example 1, except that the mass ratio of the P-type semiconductor crystal particles 1 to the resin was changed to three times.

[0080] Example 4 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the mass ratio of the P-type semiconductor crystal particles 1 to the resin is changed to five times.

[0081] Example 5 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the mass ratio of the P-type semiconductor crystal particles 1 to the resin is changed to 30 times.

[0082] Example 6 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the mass ratio of the P-type semiconductor crystal particles 1 to the resin is changed to 35 times.

[0083] Example 7 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the thickness of the charge transport layer is changed to 89 nm.

[0084] Example 8 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the thickness of the charge transport layer is changed to 300 nm.

[0085] Example 9 A photoelectric conversion element is obtained in the same manner as in Example 1, except that tetraphenylporphyrin (TPP) is used as the P-type semiconductor crystalline particles 1. Tetraphenylporphyrin (TPP) used as the P-type semiconductor crystalline particles 1 is crystalline.

[0086] Example 10 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the P-type semiconductor crystal particles 1 are changed to 4,4',4",4'"-(porphine-5,10,15,20-tetralyl)tetrakis(benzoic acid). 4,4',4",4'"-(porphine-5,10,15,20-tetralyl)tetrakis(benzoic acid) used as the P-type semiconductor crystal particles 1 is crystalline.

[0087] Example 11 A photoelectric conversion element is obtained in the same manner as in Example 1, except that 1-aminoanthraquinone-2-sulfonic acid is used as the P-type semiconductor crystal particles 1. The 1-aminoanthraquinone-2-sulfonic acid used as the P-type semiconductor crystal particles 1 is crystalline.

[0088] Example 12 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the calixarene compound is not used.

[0089] Example 13 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the second charge transport layer is not provided.

[0090] Example 14 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the resin is poly(3-hexylthiophene-2,5-diyl) (P3HT).

[0091] Example 15 A photoelectric conversion element is obtained in the same manner as in Example 1, except that quinacridone particles are used instead of the P-type semiconductor crystal particles 1. The quinacridone particles used as the P-type semiconductor crystal particles 1 are crystalline.

[0092] Comparative Example 1 In the process for producing P-type semiconductor crystalline particles 1, step (3) was not performed, and P-type semiconductor particles 2 that had not undergone crystal conversion were obtained. A photoelectric conversion element was obtained in the same manner as in Example 1, except that P-type semiconductor particles 2 were used instead of P-type semiconductor crystalline particles 1 in forming the charge transport layer. The P-type semiconductor particles 2 that had not undergone crystal conversion were amorphous.

[0093] Comparative Example 2 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the P-type semiconductor crystal particles 1 are replaced with copper phthalocyanine particles.

[0094] Comparative Example 3 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the resin is not used.

[0095] Comparative Example 4 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the P-type semiconductor crystal particles 1 are SPIRO-OMeTAD and the polyvinyl butyral is polymethyl methacrylate (PMMA, manufactured by Sigma-Aldrich).

[0096] [Evaluation] A power supply (manufactured by Keithley, Model 236) was connected between the electrodes of the photoelectric conversion element prepared in Example 1, and an intensity of 110 mW / cm ２ The photoelectric conversion efficiency was measured by irradiating a constant amount of light using a solar simulator (manufactured by Yamashita Denso Co., Ltd.) and measuring the generated current and voltage. Measurements were also made at 10 electrodes for each device, and the maximum value was used as the representative value for that device. After that, the device was continuously irradiated with 10,000 Lx of light from a white LED, and the photoelectric conversion efficiency after 60 days was measured. Durability was evaluated by evaluating the retention rate of the photoelectric conversion efficiency after 60 days relative to the initial photoelectric conversion efficiency. The results, along with the initial photoelectric conversion efficiency, are shown in Table 2.

[0097] Examples 2 to 15 and Comparative Examples 1 to 4 were also evaluated based on the initial photoelectric conversion efficiency and the maintenance rate of the photoelectric conversion efficiency after 60 days, in the same manner as in Example 1. The results are shown in Table 2.

[0098]

[0099] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0100] This application is related to Japanese Patent Application No. 2023-184761 filed on October 27, 2023, Japanese Patent Application No. 2023-184756 filed on October 27, 2023, Japanese Patent Application No. 2023-184750 filed on October 27, 2023, Japanese Patent Application No. 2023-216294 filed on December 21, 2023, Japanese Patent Application No. 2023-216296 filed on December 21, 2023, and Japanese Patent Application No. 2023-21629 filed on December 21, 2023. 9, Japanese Patent Application No. 2024-022244 filed on February 16, 2024, Japanese Patent Application No. 2024-022251 filed on February 16, 2024, Japanese Patent Application No. 2024-022246 filed on February 16, 2024, Japanese Patent Application No. 2024-077353 filed on May 10, 2024, and Japanese Patent Application No. 2024-186698 filed on October 23, 2024. Priority is claimed based on the Japanese Patent Application No. 2024-186698 filed on October 23, 2024, the entire contents of which are incorporated herein by reference.

[0101] REFERENCE SIGNS LIST 1 Photoelectric conversion element 2 Substrate 3 Second electrode 4 Electron transport layer 5 Photoelectric conversion layer 6 Charge transport layer 7 First electrode 8 Second charge transport layer 30 Mobile body 31, 41 Photoelectric conversion element 32 Airframe 40 Building material 42 Protective member 43 Heat dissipation member 44a, 44b Exterior

Claims

1. 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, wherein the photoelectric conversion element has a charge transport layer between the photoelectric conversion layer and the first electrode, the charge transport layer contains a P-type semiconductor crystal and a resin, and the P-type semiconductor crystal has at least one functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, an imino group, and a sulfo group.

2. 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 element has a charge transport layer between the photoelectric conversion layer and the first electrode, the charge transport layer contains a P-type semiconductor crystal and a resin, and the P-type semiconductor crystal has a functional group capable of acting as a hydrogen bond donor.

3. 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 element has a charge transport layer between the photoelectric conversion layer and the first electrode, the charge transport layer contains a P-type semiconductor crystal and a resin, and the P-type semiconductor crystal has a Lewis basic functional group.

4. The photoelectric conversion element according to any one of claims 1 to 3, wherein the charge transport layer is in contact with the photoelectric conversion layer.

5. The photoelectric conversion element according to any one of claims 1 to 4, wherein the charge transport layer has the P-type semiconductor crystals dispersed in the resin.

6. The photoelectric conversion element according to any one of claims 1 to 5, wherein the content of the P-type semiconductor crystal in the charge transport layer is 5 times or more and 30 times or less, in terms of mass ratio, the content of the resin in the charge transport layer.

7. The photoelectric conversion element according to any one of claims 1 to 6, wherein the charge transport layer has a thickness of 10 nm or more and 400 nm or less.

8. The photoelectric conversion element according to any one of claims 1 to 6, wherein the charge transport layer has a thickness of 100 nm or more and 200 nm or less.

9. The photoelectric conversion element according to any one of claims 1 to 8, further comprising a second charge transport layer between the first electrode and the charge transport layer.

10. The photoelectric conversion element according to any one of claims 1 to 9, wherein the resin is a polyvinyl acetal resin.

11. The photoelectric conversion element according to any one of claims 1 to 10, wherein the P-type semiconductor crystal is a cyclic conjugated compound formed by conjugating a plurality of pyrrole rings.

12. A photoelectric conversion device comprising the photoelectric conversion element according to any one of claims 1 to 11.

13. A moving object having a photoelectric conversion element according to any one of claims 1 to 11.

14. A building material comprising the photoelectric conversion element according to any one of claims 1 to 11.

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