Photoelectric conversion element and photoelectric conversion device

Abstract

The present invention addresses the problem of providing a photoelectric conversion element that exhibits enhanced durability. In order to solve the problem, the present invention provides a photoelectric conversion element comprising a first electrode, a second electrode, and a photoelectric conversion layer which is disposed between the first electrode and the second electrode and includes perovskite-structure crystals. The photoelectric conversion element is characterized by having a charge transfer layer between the photoelectric conversion layer and the first electrode, and is characterized in that: the charge transfer layer contains a charge transfer substance and an insulating resin which are phase-separated; the ratio of the volume of the region of the charge transfer substance with respect to the volume of the region of the insulating resin is 5-30; and in a binary image of a two-dimensional spatial distribution of a region A and a region B, which is obtained by measuring the charge transfer layer with an optical microscope, when a value which is obtained by subjecting the binary image to Fourier analysis and is acquired by a calculation method for D is defined as D [μm], said D [μm] satisfies 4≤D≤12.

Description

Photoelectric conversion element and photoelectric conversion device

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

[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 utilizing the photovoltaic effect, in which light energy from sunlight is absorbed and 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 using 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 application 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 application of solar cells. For example, Patent Document 1 describes a technology that improves peeling from the electrode by including an organic semiconductor and a polymer compound with a glass transition temperature of 100°C or higher in the hole transport layer. Non-Patent Document 1 describes a technology for a charge transport layer for a reverse layer that improves photoelectric conversion efficiency by doping PEDOT:PSS with nickel phthalocyanine having a substituent.

[0005] JP 2018-170382 A

[0006] Xian-Fu Zhang, et al, J. Mater. Chem. A, 2018, 6, 12515-12522

[0007] According to the investigations of the present inventors, it has been found that there is room for improvement in durability 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. Another object of the present invention is to provide a photoelectric conversion device.

[0008] The above object can be achieved by the present invention, which provides a photoelectric conversion element having a first electrode, a second electrode, and a photoelectric conversion layer containing crystals of a perovskite structure and disposed between the first electrode and the second electrode, wherein a charge transport layer is provided between the photoelectric conversion layer and the first electrode, the charge transport layer containing a phase-separated charge transport material and an insulating resin, the ratio of the volume of the charge transport material region to the volume of the insulating resin region being 5 to 30, and wherein a value obtained by Fourier analysis of a binarized image of a two-dimensional spatial distribution of regions A and B obtained by measuring the charge transport layer with an optical microscope, the value being D [μm] calculated by the following calculation method for D, satisfies the following formula (E1): 4≦D≦12 (E1) <Calculation method of D> For region A and region B, a two-dimensional spatial distribution image having a size of L [μm] × L [μm] (L [μm] is 100 μm or more) is binarized by Otsu's binarization method according to the following formula (E3). where m and n are integers between -N / 2 and N / 2-1, inclusive, and represent coordinates within the two-dimensional spatial distribution, for discrete data of N x N pixels obtained by dividing L by N, where N is an even number greater than or equal to 1024. Next, c[m, n] obtained by the above formula (E3) is subjected to a discrete Fourier transform according to the following formula (E4) (where k and l are integers between -N / 2 and N / 2, inclusive). Then, the domain size: D [μm] is calculated according to the following formula (E5) using C [k, l] obtained by the above formula (E4).

[0009] According to the present invention, a photoelectric conversion element with improved durability can be provided.

[0010] Fig. 1 is a schematic cross-sectional view in the thickness direction of a photoelectric conversion element of the present invention. Fig. 2 is a perspective view schematically showing an example of a moving body equipped with a photoelectric conversion element of the present invention. Fig. 3 is a perspective view schematically showing an example of a building material equipped with a photoelectric conversion element of the present invention. Fig. 4 is an example of a binarized image obtained in Example 1 of the present invention.

[0011] 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 including a crystal of a perovskite structure disposed between the first electrode and the second electrode, wherein a charge transport layer is provided between the photoelectric conversion layer and the first electrode, the charge transport layer containing a phase-separated charge transport material and an insulating resin, and the ratio of the volume of a region of the charge transport material to the volume of a region of the insulating resin is 5 to 30, and wherein a value obtained by Fourier analysis of a binarized image of a two-dimensional spatial distribution of regions A and B obtained by measuring the charge transport layer with an optical microscope, where D [μm] is a value obtained by the calculation method for D below, satisfies the following formula (E1): 4≦D≦12 (E1) <Calculation method of D> For region A and region B, a two-dimensional spatial distribution image having a size of L [μm] × L [μm] (L [μm] is 100 μm or more) is binarized by Otsu's binarization method according to the following formula (E3). where m and n are integers between -N / 2 and N / 2-1, inclusive, and represent coordinates within the two-dimensional spatial distribution, for discrete data of N x N pixels obtained by dividing L by N, where N is an even number greater than or equal to 1024. Next, c[m, n] obtained by the above formula (E3) is subjected to a discrete Fourier transform according to the following formula (E4) (where k and l are integers between -N / 2 and N / 2, inclusive). Then, the domain size: D [μm] is calculated according to the following formula (E5) using C [k, l] obtained by the above formula (E4).

[0012] The measurement conditions for the optical microscope are as follows: <Measurement conditions for the optical microscope> Device name: OPTELICS HYBRID L3 (manufactured by Lasertec Corporation) Software: LMeye7 Lens: 100X / 0.95 OFN25 WD0.32 (Nicon) Light source: White light CCD mode: Select according to the object to be measured Scan rate: Standard Image size: 1024 x 1024 Operation: Normal Exposure time: Standard Confocal: ON

[0013] <Meaning of D> In order to explain the meaning of D, the continuous variable representation of the above formula (E4) is shown in the following formula (E7). where: corresponds to the continuous variable representation of equation (E3), and the position vector: teeth This (x, y) is a continuous variable representation (continuous coordinates) of the discrete coordinates [m, n]. Also, the wave vector: teeth This (q ｘ , q ｙ ) corresponds to [k, l] in the discrete notation above. is a continuous variable representation of the original binary data is the continuous Fourier transform of . Therefore, the absolute value squared of this: is called the power spectrum, and in the discrete variable representation Also, the reciprocal of the absolute value of the wave vector: has the dimension of distance, and in the discrete variable table In view of the above correspondence, the continuous variable representation corresponding to equation (E5) is given by the following equation (E8).

[0014] As is clear from the above formula (E8), D in continuous variable representation is The value with the dimension of distance is For , the power spectrum: The power spectrum obtained by Fourier transform: has a large value at the wave number q corresponding to the spatial period characteristic of the system of interest, and therefore the weighted average value D obtained by the above formula (E8) has the meaning of being a representative value of the length of the spatial period characteristic of the system.

[0015] The above meaning of D is also true in the discrete variable representation. In this case, the system of interest is a binarized image, so D calculated by the above formula (E5) has the meaning of a representative value of the length of the spatial period characteristic of the binarized image. Therefore, on the one hand, if D is small, the mesh of the two-dimensional spatial distribution formed by areas A and B of the binarized image will be fine, and on the other hand, if D is large, the mesh of the two-dimensional spatial distribution will be coarse.

[0016] In the summation in the wavenumber space [k, l] of the above formula (E5), the origin [k, l] = [0, 0] is excluded. This is because the value at the origin of the discrete Fourier transform C[k, l] contains information about the area ratio between region A and region B in the original binarized image, and only the spatial period of the two-dimensional spatial distribution formed by region A and region B is required as information for D in the present invention.

[0017] As a result of their investigations, the inventors have found that by satisfying the above-mentioned configuration, interlayer migration of organic anions contained in the perovskite crystals of the photoelectric conversion layer can be suppressed, thereby improving the durability of the photoelectric conversion element. It has been known that organic anions in the photoelectric conversion layer migrate toward the anode electrode, causing damage to the photoelectric conversion element. Therefore, the inventors provided a charge transport layer between the photoelectric conversion layer and the anode electrode. This charge transport layer contained a charge transport material and an insulating resin, and phase separation was observed under an optical microscope. The value D calculated by the above formula was used to evaluate the size of this phase separation. As a result, when the ratio of the volume of the charge transport material region to the volume of the insulating resin region was 5 to 30 and D [μm] satisfied formula (E1), damage to the photoelectric conversion element could be suppressed. The inventors speculate that the reason for this is as follows.

[0018] When an appropriate amount of insulating resin and charge transport material are phase-separated, when charge carriers are generated, a strong electrical interaction occurs between the insulating resin, which does not easily allow carriers to flow, and the charge transport material, which does, allowing carriers to flow easily, resulting in a bias in the charge distribution. It is believed that this charge bias suppresses migration of organic anions in the photoelectric conversion layer, thereby improving the durability of the photoelectric conversion element with the above configuration. In this mechanism, in order for the charge bias to sufficiently capture the organic anions and suppress deterioration in durability due to migration, the distribution of the charge bias must be sufficiently fine. From this perspective, the inventors' investigations revealed that it was necessary to satisfy the condition represented by the above formula (E1): 4≦D≦12 (E1). As described above in <Meaning of D>, if D is greater than 12, the mesh of the two-dimensional spatial distribution becomes coarse, and the distribution of the charge imbalance generated by the electrical interaction between region A and region B in the two-dimensional spatial distribution also becomes coarse, causing the organic anions to slip through the parts where there is no charge imbalance, causing migration and accelerating durability degradation of the photoelectric conversion element. Conversely, if D is smaller than 4, region A and region B become well mixed, which makes the distinction between the insulating resin region and the charge transport material region unclear, weakening the electrical interaction between the two regions and making it impossible to sufficiently capture the organic anions.

[0019] In a binary image of the two-dimensional spatial distribution of the region A and the region B obtained by measuring the charge transport layer with an optical microscope, the binary image is subjected to Fourier analysis, and P is a value calculated by the following calculation method for P. It is preferable that P satisfies the following formula (E2): 8.0≦P≦9.7 (E2)

[0020] <Calculation Method of P> Using C[k, l] obtained by the above formula (E4), the order parameter: P is calculated according to the following formula (E6).

[0021] <Meaning of P> To explain the meaning of P, the continuous variable representation of the above formula (E6) is shown in the following formula (E9). In the above formula (E9), As mentioned above, is the power spectrum, and has a large value at the wave number q corresponding to the spatial period characteristic of the system under consideration. Therefore, the value obtained by dividing the power spectrum by the integral in that wave number space is: is a weighting function that takes values ​​between 0 and 1. Equation (E9) is the calculation of Shannon entropy by equating this weighting function with probability, so P calculated by the above equation (E9) corresponds to a parameter that represents the degree of order of the original binarized image, i.e., entropy.

[0022] When P is in the range that satisfies the above formula (E2), migration of organic anions can be further suppressed.

[0023] In the photoelectric conversion element of the present invention, the charge transport material has a particle size of 1.0×10 １ nm or more 5.0×10 ２ It is preferable that the pigment has a particle size of 100 nm or less. If the particle size is within the above range, it is easy to form a charge distribution that can suppress migration. Specific examples of pigments include phthalocyanine pigments, azo pigments, lake pigments, quinacridone pigments, dioxazine pigments, perylene pigments, and isoindolinone pigments. The particle size can be selected by selecting the type of insulating resin, the ratio of the volume of the charge transport material to the volume of the insulating resin (volume ratio), the use of a dispersant during dispersion, the dispersion conditions, or centrifugal separation.

[0024] In the photoelectric conversion element of the present invention, the charge transport material is more preferably a phthalocyanine compound, and more preferably the phthalocyanine compound has a structure represented by the following formula (Pc-2): This charge transport material can more efficiently form a charge distribution that suppresses migration. In the formula (Pc-2), M is H. ２ , a metal atom having a ligand, or a metal atom having no ligand. In the present invention, the structure of a chemical substance can be determined by nuclear magnetic resonance (NMR) spectroscopy.

[0025] In particular, M in the above formula (Pc-2) is H ２ When this is the case, the above formula (Pc-2) is expressed by the following formula (Pc-1):

[0026] Specific examples of insulating resins include polyacetal resin, acrylic resin, polyarylate resin, polycarbonate resin, polyvinyl acetate resin, polyester resin, polyamide resin, polyurethane resin, and polystyrene resin. The molecular weight is preferably in the range of 1,000 to 1,000,000 in weight average molecular weight.

[0027] In the photoelectric conversion element of the present invention, the insulating resin preferably has a glass transition temperature of 95° C. or lower. Within this range, the insulating resin is easily in close contact with the charge transport material, and a more effective charge distribution can be formed. The glass transition temperature can be determined by a differential scanning calorimeter (DSC).

[0028] In the photoelectric conversion element of the present invention, the insulating resin is preferably a polyvinyl acetal resin or a polyvinyl butyral resin, which is likely to come into close contact with the charge transport material and form a more effective charge distribution.

[0029] In the photoelectric conversion element of the present invention, the charge transport layer preferably contains an aromatic ring compound having a hydroxy group, which is different from the charge transport material (pigment) and the insulating resin. The presence of the aromatic ring compound having a hydroxy group facilitates contact between the charge transport material and the insulating resin, thereby forming a more effective charge distribution.

[0030] In order to control D so as to satisfy the range of formula (E1) of the present invention, 4≦D≦12, it is necessary to appropriately select the film thickness of the charge transport layer, the type of charge transport material, the type of insulating resin, etc., in addition to the ratio of the volume of the charge transport material to the volume of the insulating resin. １ nm or more 5.0×10 ２ One effective means for satisfying the range of formula (E1) is to set the average particle size to 0.1 nm or less.

[0031] Furthermore, in order to control P so that the range of formula (E2) of the present invention is satisfied, 8.0≦P≦9.7, it is necessary to appropriately select the means for forming the charge transport layer. For example, when forming the charge transport layer by spin coating, one example is to select the distance between the location where the coating solution is dropped and the location of the photoelectric conversion element of the present invention. The farther the location of the photoelectric conversion element of the present invention is from the location where the spin coating is dropped, the more likely it is that the two-dimensional spatial distribution of region A and region B will have anisotropy due to centrifugal force, and therefore the order will be higher and P will tend to be smaller.

[0032] 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.

[0033] As explained above, the effects of the present invention can be achieved by the synergistic effects of the various components.

[0034] 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.

[0035] 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 photoelectric conversion element to expose the layer to be analyzed. In the present invention, the volume ratio is quantified by using the area ratio of the exposed surface or cross section as the volume ratio of that layer.

[0036] 1 is a cross-sectional view schematically illustrating the configuration of one embodiment of the photoelectric conversion element of the present invention. The photoelectric conversion 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.

[0037] 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 following order: the first electrode 7, the charge transport layer 6, the photoelectric conversion layer 5, the electron transport layer 4, and the second electrode 3.

[0038] [Photoelectric Conversion Element] The photoelectric conversion element of the present invention is characterized by having a first electrode, a second electrode, a photoelectric conversion layer containing a crystal of a perovskite structure disposed between the first electrode and the second electrode, and a charge transport layer between the photoelectric conversion layer and the first electrode. Furthermore, in order to improve the 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, in addition to perovskite solar cells that use perovskite crystals in the photoelectric conversion layer, silicon solar cells, CIGS solar cells, and the like.

[0039] Methods for forming each layer, including the photoelectric conversion layer and the charge transport 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.

[0040] [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.

[0041] [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, carbon nanotubes, aluminum-lithium alloy, and Al / Al ２ O ３ Examples of transparent electrode materials include CuI, ITO (indium tin oxide), and SnO. ２Examples of the conductive transparent material 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. These materials may be used alone or in combination of two or more. The first electrode 7 and the second electrode 3 are configured such that at least one electrode on the light incident side is a transparent electrode, and the other electrode 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 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.

[0042] [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]: 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.

[0043] The o, p, and q satisfy the conditions 0≦o≦10, 0≦p≦10, and 0≦q≦20, respectively, and A, B, and X may each be composed of a single material or a combination of two or more materials. Additives may be added within the range in which the above general formula is established. The above general formula generally forms a perovskite crystal with a three-dimensional structure, but when the constituent cation A is large enough to fit within a three-dimensional perovskite crystal, a two-dimensional perovskite crystal, a 2.5-dimensional perovskite crystal having 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 / two-dimensional perovskite crystal is formed, all of which function as a photoelectric conversion layer. A two-layer crystal of three-dimensional and two-dimensional perovskite refers to a crystal in which crystals of three-dimensional and two-dimensional perovskite structures are stacked as independent, separate layers, and a mixed three-dimensional / two-dimensional perovskite refers to a crystal having a structure in which regions or domains of both two-dimensional or 2.5-dimensional layered and three-dimensional perovskite structure crystals are mixed. Crystals of two-dimensional perovskite or 2.5-dimensional perovskite structures may form Ruddlesden-Popper (RP), Dion-Jacobson (DJ), or alternating cations in the interlayer (ACI) perovskite structures.

[0044] The cation represented by A in the general formula [1] is not particularly limited. The cation represented by A may or may not have a substituent, and specific examples thereof include those represented by the following formulae (C1) to (C67).

[0045] 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.

[0046] In the general formula [1], B is a cation 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, 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.

[0047] X in the general formula [1] is a halogen or chalcogen atom, such as chlorine, bromine, iodine, oxygen, sulfur, selenium, tellurium, or polonium. These halogen or chalcogen 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.

[0048] 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 ０．０５ (MA ０．１７ FA ０．８３ ) ０．９５ Pb(I ０．８３ Br ０．１７ ) ３ , {Cs ｘ１ (FA ｘ２ MA １－ｘ２ ) １－ｘ１} ｘ３ Pb(I ｘ４ Br １－ｘ４ ) ｘ５ , Cs ０．０５ FA ０．８８ MA ０．０７ PbI ２．５６ Br ０．４４ , (FAPbI３ ) ０．９５ (MAPbBr ３ ) ０．０５ 、(FAPbI ３ ) ０．８５ (MAPbBr ３ ) ０．１５ 、CsPbI ３ 、CsPbBr ３ 、Cs ｘ (MA) １－ｘ PbI ３ 、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 、(3AAMPY)(MA) ３ Pb ４ I １３ 、(PDMA)MA ５ Pb 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 、Cs.Br ３ 、CsSﾎI ３ 、FA ０．７５ MA ０．２５ Se ０．９５ Ge ０．０５ I ３ 、FAMASGGeI ３ 、FAS.Br ３ 、FASII ３ 、MA ２ Se ３ I ８ 、MAS.Br ３ 、MASGGeI ３ 、MASII ３is preferred.

[0049] 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. Combinations of x1 to x5 are, for example, as shown in Table 1. 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.

[0050]

[0051] 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.

[0052] 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.

[0053] 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.

[0054] [Charge Transport Layer] In the photoelectric conversion element of the present invention, the charge transport layer contains a phase-separated region of a charge transport material and a region of an insulating resin, and the ratio of the volume of the region of the charge transport material to the volume of the region of the insulating resin is 5 to 30. In the present invention, the charge transport layer contains a charge transport material that is a P-type semiconductor and an insulating resin. The insulating resin has a volume resistivity of 10 ８ The ratio of the volume of the insulating resin region to the volume of the charge transport material region can be measured, for example, from the area ratio of the cross section determined by FE-TEM / EDS, as described above.

[0055] 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.

[0056] 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, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, alcohol-based solvents and aromatic hydrocarbon-based solvents are preferred.

[0057] [Second Charge Transport Layer] In the present invention, a second charge transport layer may be further provided between the charge transport layer 6 and the first electrode 7 from the viewpoint of film compatibility of the charge transport layer 6 .

[0058] 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, thiocyanate compounds, and thiophene compounds. In particular, from the viewpoint of compatibility at the film interface, compounds having an aromatic ring are preferred, and Spiro-OMeTAD, PTAA, and phthalocyanine compounds are preferred.

[0059] The second charge transport layer may contain a dopant as an additive to improve its charge transport capability. Examples of a substance 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.

[0060] [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 .

[0061] The material for 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, etc. 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 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, zinc sulfide, etc. In particular, tin oxide may be obtained by reacting tin(2) chloride, tin(4) chloride, tin(2) chloride dihydrate, or tin(4) chloride pentahydrate.

[0062] 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.

[0063] <Application Examples> Application examples of the present invention relate to photoelectric conversion devices, mobile objects, and building materials. [Photoelectric Conversion Device] The photoelectric conversion device of the present invention includes the photoelectric conversion element of the present invention. A photoelectric conversion device can be constructed by using multiple photoelectric conversion elements of the present invention. When multiple 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 stacked with photoelectric conversion elements having different absorption wavelengths to increase the output voltage. The photoelectric conversion device may also include 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 include a power storage unit connected to the photoelectric conversion element. The power storage unit is not limited as long as it can store electricity. Examples include secondary batteries using lithium ions, all-solid-state batteries, and electric double-layer capacitors. To impart functionality such as maintaining or increasing the amount of incident light, a surface layer that is resistant to water and dirt, or a function to collect or guide light, may be added.

[0064] [Mobile Object] The mobile object of the present invention includes the photoelectric conversion element of the present invention. FIG. 2 is a perspective view schematically illustrating one embodiment of a mobile object including the photoelectric conversion element of the present invention. The mobile object 30 includes the photoelectric conversion element 31 of the present invention and a vehicle 32 including the photoelectric conversion element 31. The photoelectric conversion element 31 is disposed in a position on the vehicle 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 other electrical equipment. Electrical energy generated by 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. The mobile object 30 may be, for example, an automobile, a motorcycle, a railroad vehicle, a ship, or an aerial vehicle including an artificial satellite, an airplane, or a drone. The configuration of the vehicle 32 of the mobile object 30 is not particularly limited, but it is preferably made of a high-strength material.

[0065] [Building Material] The building material of the present invention has the photoelectric conversion element of the present invention. 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.

[0066] 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.

[0067] 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.

[0068] [Other] In addition to the above application examples, the following application examples 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, 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.

[0069] [Regarding the manufacturing method of a photoelectric conversion element] The method includes a step of forming a first electrode, a second electrode, a photoelectric conversion layer containing crystals with a perovskite structure disposed between the first electrode and the second electrode, and a step of forming a charge transport layer between the photoelectric conversion layer and the first electrode. Each step of the manufacturing method will be described below.

[0070] (Step of forming a first electrode and step of forming a second electrode) The method for manufacturing a photoelectric conversion element of the present invention includes a step of forming a first electrode and a step of forming a second electrode. For the step of forming the first electrode and the step of forming the second electrode, an appropriate method can be selected depending on 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 (chemical vapor 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 step to form a circuit. Examples of cutting include mechanical patterning and laser patterning.

[0071] (Modularization Process) The elements having electrodes formed thereon may be sealed. Examples of sealing methods include sealing with a resin or sealing with a film. Examples of materials used for sealing include silazane, silicone rubber, resins having a siloxane skeleton, and glass. In addition, from the viewpoint of suppressing adhesion between elements that occurs when winding in a roll-to-roll manner, the surfaces of the sealed elements may be subjected to a hairline treatment.

[0072] (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 for the photoelectric conversion layer described above. Examples of application methods include spin coating, blade coating, slit die coating, screen printing, bar coating, casting, print transfer, immersion and lifting, inkjet printing, spraying, and vacuum deposition. Among these, an appropriate method is selected depending on the properties of the photoelectric conversion layer to be produced, such as thickness control and orientation control.

[0073] In order to remove the solvent or dispersion medium from the liquid containing the material of the applied photoelectric conversion layer, annealing may be performed under reduced pressure or in an inert atmosphere (nitrogen or argon atmosphere). The temperature of the annealing is preferably 40° C. or higher and 300° C. or lower, more preferably 50° C. or higher and 150° C. or lower. Note that annealing is preferable because it may increase the contact area at the interface between the stacked layers due to the penetration of the materials constituting each layer into each other, thereby increasing the short-circuit current.

[0074] (Step of forming charge transport layer) The step of forming the charge transport layer is preferably performed by a method of applying a resin solution in which an insulating resin is dissolved. Examples of the step of forming the charge transport layer include the following: a method of disposing a charge transport material on the surface of the photoelectric conversion layer and then applying a resin solution in which an insulating resin is dissolved, a method of applying a resin solution in which an insulating resin is dissolved on the surface of the photoelectric conversion layer and then disposing a charge transport material, and a method of applying a solution in which a charge transport material is dispersed in a resin solution in which an insulating resin is dissolved on the surface of the photoelectric conversion layer.

[0075] 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.

[0076] <Preparation of Particles 1> Step (1) Under a nitrogen flow atmosphere, 5.46 parts of orthophthalonitrile and 45 parts of α-chloronaphthalene were added to a reaction vessel, which was then heated to 30°C and maintained at that temperature. Next, 3.75 parts of gallium trichloride was added at this temperature (30°C). The water concentration of the mixed solution at the time of addition was 150 ppm. The temperature was then increased to 200°C. Next, under a nitrogen flow atmosphere, the mixture was reacted at 200°C for 4.5 hours, cooled, and 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, followed by filtration. The resulting filtrate was washed with methanol and dried to obtain chlorogallium phthalocyanine particles in a yield of 71%.

[0077] 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 dropped into 620 parts of ice water under stirring to reprecipitate, followed by vacuum filtration using a filter press. No. 5C (manufactured by Advantec Co., Ltd.) was used as the filter. The obtained wet cake (filtrate) was dispersed and washed with 2% aqueous ammonia for 30 minutes, and then filtered using a filter press. Next, the obtained wet cake (filtrate) was dispersed and washed with ion-exchanged water, and then filtered three times using a filter press. Finally, freeze-drying was performed to obtain hydroxygallium phthalocyanine particles (hydrated hydroxygallium phthalocyanine particles) with a solids content of 23% by mass in 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 Nippon Biocon) to obtain hydroxygallium phthalocyanine (OHGaPc) particles (crystals) with a water content of 1.0 mass % or less.

[0078] Step (3) Five parts of the hydroxygallium phthalocyanine particles were mixed with five parts of N-methylformamide solvent, and the mixture was dispersed 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, filtered, and dried to obtain particles 1 (specific gravity 1.6).

[0079] <Preparation of Resin Solution 1> Resin solution 1 was obtained by dissolving 1.0 g of polyvinyl butyral (product name: BM-2, manufactured by Sekisui Chemical Co., Ltd., specific gravity 1.6) in 19 g of 2-propanol with stirring for 24 hours.

[0080] Example 1 Formation of Electron Transport Layer A glass substrate with ITO was cleaned, and a 5-fold diluted tin oxide (2) colloidal solution (15% aqueous dispersion, manufactured by Alfa Aesar) was applied thereon by spin coating, followed by heating at 150°C for 30 minutes to form a thin-film electron transport layer with a thickness of 16 nm.

[0081] [Formation of Photoelectric Conversion Layer] 0.487 g of methylammonium bromide, 1.034 g of formamidium iodide, 2.903 g of lead iodide, and 0.139 g of methylammonium bromide were dissolved in 4.25 g of N,N-dimethylformamide and 1.216 g of dimethyl sulfoxide, and the mixture was stirred for 1 hour (Solution 1). Furthermore, 0.100 g of cesium iodide was dissolved in 0.285 g of dimethyl sulfoxide, and the mixture was stirred for 1 hour (Solution 2). The dissolved cesium iodide solution (Solution 2) was then added to Solution 1 to prepare a photoelectric conversion layer coating solution. This coating solution was spin-coated on the electron transport layer, resulting in a Cs ０．０５ (FA ０．８３ MA ０．１７ ) ０．９５ Pb(I ０．８３ Br ０．１７ ) ３ A photoelectric conversion layer having a thickness of 600 nm was formed.

[0082] [Formation of Charge Transport Layer] 0.1 g of the particles 1 and 0.01 g of a calixarene compound (JP 2003-207913 A) were mixed with 10.6 g of 2-propanol. 11 g of beads (zirconia beads, Treceram (registered trademark) 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) for 3 hours. Then, 0.2 g of resin solution 1 was added, and the mixture was dispersed again in a paint shaker for 4 hours to prepare a charge transport layer solution. This charge transport layer solution was spin-coated on the photoelectric conversion layer to form a charge transport layer with a thickness of 160 nm.

[0083] [Introduction of Second Charge Transport Layer] 0.15 g of Spiro-OMeTAD, a material for the second charge transport layer, was dissolved in 2.2 g of chlorobenzene. To this chlorobenzene solution, 36 μL of an acetonitrile solution obtained by dissolving 0.2 g of lithium bis(trifluoromethanesulfonyl)imide in 0.3 g of acetonitrile was added and mixed with 60 μL of 4-tert-butylpyridine (TBP). This solution was further mixed with 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 to prepare a material solution for the second charge transport layer. This solution was applied to the charge transport layer by spin coating to form a second charge transport layer with a thickness of 100 nm.

[0084] [Formation of First Electrode] A first electrode having a thickness of 80 nm and an area of ​​0.09 cm was formed on the second charge transport layer. ２ A gold electrode was formed by vacuum deposition to obtain a photoelectric conversion element.

[0085] [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). The peeled charge transport layer components were subjected to mass and structural analysis using elemental analysis such as GPC, MALDI-TOF-MS, IR, gas chromatography, XPS, and EDX to confirm the presence of the compound. The film thickness was also confirmed by cutting the photoelectric conversion element, fixing it to an inclined sample stage, and then using a cross-sectional SEM (apparatus: SmartSEM, manufactured by Carl Zeiss K.K.).

[0086] [Analysis of particle size of charge transport material] The particle size of the charge transport material is the number average particle size in the particle size distribution. In the present invention, the particle size of the charge transport material was determined by an image imaging method using a TEM. Specifically, first, using the obtained TEM image of the cross section of the charge transport layer, N particles (N is 1,000 or more) were extracted using image processing software Photoshop (manufactured by Adobe). Next, the area S of each particle was determined, and the diameter of a circle having the same area as this area (= 2 × (S / π) １／２ ) was used as the particle size, and the average value of the median 80% of the N particles was taken.

[0087] Example 2 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the ratio of the volume of the charge transport material to the volume of the insulating resin is set to 8.

[0088] Example 3 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the ratio of the volume of the charge transport material to the volume of the insulating resin is set to 15.

[0089] Example 4 A photoelectric conversion element was obtained in the same manner as in Example 1, except that in forming the charge transport layer, the particle size in the dispersion obtained by paint shaker dispersion was reduced by centrifuging (15,000 rpm, 6 minutes) the dispersion, and then the ratio of the volume of the charge transport material to the volume of the insulating resin was adjusted to 10.

[0090] Example 5 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the polyvinyl butyral (trade name: BM-2, manufactured by Sekisui Chemical Co., Ltd.) is replaced with polyvinyl butyral (trade name: BX-1, manufactured by Sekisui Chemical Co., Ltd.).

[0091] Example 6 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the calixarene compound is 2-naphthol.

[0092] Example 7 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the particles 1 are copper phthalocyanine particles.

[0093] Example 8 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the second charge transport layer is not provided.

[0094] Example 9 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the calixarene compound is not used.

[0095] Example 10 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the polyvinyl butyral is replaced with polymethyl methacrylate (PMMA, manufactured by Sigma-Aldrich, glass transition temperature 70° C.).

[0096] Example 11 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the polyvinyl butyral is replaced with polymethyl methacrylate (PMMA, manufactured by Sigma-Aldrich, glass transition temperature 100° C.).

[0097] Example 12 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the particles 1 are changed to particles containing the compound represented by (Pc-3).

[0098] Example 13 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the particles 1 are quinacridone particles.

[0099] Example 14 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the ratio of the volume of the charge transport material to the volume of the insulating resin is set to 20.

[0100] Example 15: The composition of the photoelectric conversion layer was changed to MAPbI３ A photoelectric conversion element was obtained in the same manner as in Example 1, except for changing the temperature to

[0101] Comparative Example 1 A photoelectric conversion element was obtained in the same manner as in Example 1, except that the ratio of the volume of the charge transport material to the volume of the insulating resin was set to 2.

[0102] Comparative Example 2 A photoelectric conversion element was obtained in the same manner as in Example 1, except that the insulating resin was not used.

[0103] Comparative Example 3 A photoelectric conversion element was obtained in the same manner as in Example 11, except that the particles 1 were replaced with SPIRO-OMeTAD and the second charge transport layer was not provided.

[0104] Comparative Example 4 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the particles 1 are replaced with nickel (II) phthalocyanine-tetrasulfonic acid tetrasodium salt particles and the insulating resin is replaced with PEDOT:PSS.

[0105] (Comparative Example 5) A photoelectric conversion element is obtained in the same manner as in Example 1, except that the particles 1 are replaced with particles having a compound represented by the following formula (Pc-4), and the insulating resin is replaced with a conductive resin, P3HT.

[0106] (Comparative Example 6) A photoelectric conversion element is obtained in the same manner as in Example 1, except that the particles 1 are carbon nanotubes (multi-walled carbon nanotubes) and the insulating resin is polycarbonate resin (product name: PCZ200, manufactured by Mitsubishi Gas Chemical Company).

[0107] Comparative Example 7 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the particles 1 are those represented by the following formula (H-1) and the insulating resin is a polycarbonate resin (PCZ200).

[0108] [Evaluation] The surface of the charge transport layer prepared in Example 1 was observed with an optical microscope, and the values ​​of D and P were determined. The results are shown in Table 2. The CCD mode of the optical microscope was set to "color." The white light used as the light source for the optical microscope was a xenon lamp (LC8 manufactured by Hamamatsu Photonics). The color image observed with the optical microscope was imported into a personal computer and subjected to 8-bit grayscale processing in the OpenCV library (Ver. 4.8.1) on Python (registered trademark). As described above, Otsu's binarization processing was performed using pixel values ​​to determine the values ​​of D and P.

[0109] Next, a power supply (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 the sample with a constant amount of light using a solar simulator (manufactured by Yamashita Denso Co., Ltd.) and measuring the generated current and voltage. The sample was then continuously irradiated with 10,000 Lx of light from a white LED, and the photoelectric conversion efficiency after 60 days was measured. The maintenance rate of the photoelectric conversion efficiency after 60 days relative to the initial photoelectric conversion efficiency was then evaluated. The results are shown in Table 2.

[0110] Examples 2 to 15 and Comparative Examples 1 to 7 were also evaluated in the same manner as in Example 1, and were evaluated based on the maintenance rate of photoelectric conversion efficiency. The results are shown in Table 2. In Comparative Examples 3 to 7, no phase separation was observed in the charge transport layer, and the particle size could not be measured.

[0111]

[0112] 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.

[0113] 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. 2023-2162 filed on December 21, 2023. 99, 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. 2024-085999 filed on May 28, 2024, and Japanese Patent Application No. 2024-186505 filed on October 23, 2024. Priority is claimed based on the Japanese Patent Application No. 2024-085999 filed on May 28, 2024, and Japanese Patent Application No. 2024-186505 filed on October 23, 2024, the entire contents of which are incorporated herein by reference.

[0114] 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 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 crystals of a perovskite structure disposed between the first electrode and the second electrode, wherein a charge transport layer is provided between the photoelectric conversion layer and the first electrode, the charge transport layer containing a phase-separated charge transport material and an insulating resin, the ratio of the volume of the region of the charge transport material to the volume of the region of the insulating resin being 5 or more and 30 or less, wherein a value obtained by Fourier analysis of a binary image of a two-dimensional spatial distribution of region A and region B obtained by measuring the charge transport layer with an optical microscope, the binary image being D [μm], where D [μm] is a value obtained by the calculation method of D below, satisfies the following formula (E1). 4≦D≦12 (E1) <Calculation method of D> For area A and area B, a two-dimensional spatial distribution image with a size of L [μm] × L [μm] (L [μm] is 100 μm or more) is binarized by Otsu's binarization method according to the following formula (E3). where m and n are integers between -N / 2 and N / 2-1, inclusive, and represent coordinates within a two-dimensional spatial distribution, for discrete data of N x N pixels obtained by dividing L by N, where N is an even number not less than 1024. Next, c[m, n] obtained by the above formula (E3) is subjected to a discrete Fourier transform according to the following formula (E4) (where k and l are integers between -N / 2 and N / 2, inclusive). Then, the domain size: D [μm] is calculated according to the following formula (E5) using C [k, l] obtained by the above formula (E4).

2. The photoelectric conversion element according to claim 1, wherein, in a binary image of a two-dimensional spatial distribution of the region A and the region B obtained by measuring the charge transport layer with an optical microscope, the binary image is subjected to Fourier analysis, and when a value P is determined by the following calculation method for P, the P satisfies the following formula (E2): 8.0≦P≦9.7 (E2) <Calculation method for P> An order parameter P is calculated according to the following formula (E6) using C[k,l] obtained by the formula (E4).

3. The charge transport material has a particle size of 1.0×10 １ nm or more 5.0×10 ２ The photoelectric conversion element according to claim 1 , wherein the pigment has a particle size of 0.1 nm or less.

4. The photoelectric conversion element according to any one of claims 1 to 3, wherein the charge transport material is a phthalocyanine compound.

5. The photoelectric conversion element according to claim 4, wherein the phthalocyanine compound has a structure represented by the following formula (Pc-2): (M in the above formula (Pc-2) is H ２ , a metal atom having a ligand, or a metal atom having no ligand.

6. The photoelectric conversion element according to any one of claims 1 to 5, wherein the insulating resin has a glass transition temperature of 95°C or lower.

7. The photoelectric conversion element according to any one of claims 1 to 6, wherein the insulating resin is a polyvinyl acetal resin or a polyvinyl butyral resin.

8. The photoelectric conversion element according to claim 3, wherein said charge transport layer contains an aromatic ring compound having a hydroxyl group, which is different from said pigment and said insulating resin.

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. A photoelectric conversion device comprising the photoelectric conversion element according to any one of claims 1 to 9.

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