Method for manufacturing photoelectric conversion element

Abstract

To provide a photoelectric conversion element that achieves both mass productivity and uniformity of photoelectric conversion efficiency.SOLUTION: A method for manufacturing a photoelectric conversion element includes: a step (A) of forming a photoelectric conversion layer including a crystal of a perovskite structure by using a large-area deposition method; and a step (B) of applying a coating for a charge transport layer on a surface of the photoelectric conversion layer, and subsequently drying the coating to form a charge transport layer. The coating for a charge transport layer contains charge transporting particles and insulating resin.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for producing a photoelectric conversion element. [Background technology]

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

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

[0004] On the other hand, solar cells using organic materials (hereinafter referred to as "organic solar cells") do not require high-temperature processing and can be produced using a sheet-like substrate by the so-called roll-to-roll method, which is expected to reduce costs. Among them, perovskite-type solar cells, which have crystals with a perovskite structure (hereinafter also referred to as "perovskite crystals") as a photoelectric conversion layer, are being developed for practical use as they have excellent photoelectric conversion characteristics.

[0005] Various methods have been proposed for forming films of perovskite crystals. While spin-coating is often used in research-level studies, die-coating and blade-coating methods that are more suitable for mass production are often used in studies aimed at mass production, taking into account factors such as connectivity with previous and subsequent processes, the size of the area that can be coated at one time, and applicability to the roll-to-roll method.

[0006] On the other hand, perovskite crystals are difficult to manufacture, and so they suffer from a variety of defects, large and small, including molecular-level defects, defects in the coating, etc. These defects reduce the ability to transport carriers to the layers above and below, which means a decrease in photoelectric conversion efficiency, and can accelerate the deterioration of perovskite solar cells over long periods of use, so research is being actively conducted to suppress defects and improve the carrier transport ability.

[0007] Patent Document 1 describes a technique for applying a perovskite thin film material film using a coating method suitable for large area applications. Patent Document 2 describes a technology for protecting the defects and improving the performance of perovskite solar cells by forming an extremely thin insulating material layer on the surface of the perovskite crystal, which interacts with the defects.

[0008] Patent Document 3 describes a technique for improving peeling from an electrode by including an organic semiconductor and a polymer compound having a glass transition temperature of 100° C. or higher in a hole transport layer. Non-Patent Document 1 describes that the conversion efficiency is improved by mixing copper phthalocyanine and a conductive polymer in the hole transport layer. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2023-148126 A [Patent Document 2] US Patent Application Publication No. 2021 / 057591 [Patent Document 3] JP 2018-170382 A [Non-patent literature]

[0010] [Non-Patent Document 1] Q. Hu,et al,Sol.RRL,2019,3,1800264 Summary of the Invention [Problem to be solved by the invention]

[0011] According to the studies of the present inventors, it has been found that the photoelectric conversion elements described in Patent Document 1, Patent Document 2, Patent Document 3, and Non-Patent Document 1 have room for improvement in mass productivity and uniformity of photoelectric conversion efficiency. Therefore, an object of the present invention is to provide a method for manufacturing a photoelectric conversion element which achieves both mass productivity and uniformity in photoelectric conversion efficiency. [Means for solving the problem]

[0012] The above object can be achieved by the present invention. A step (A) of forming a photoelectric conversion layer including a crystal having a perovskite structure by using a large-area film formation method; A step (B) of applying a coating material for a charge transport layer onto the surface of the photoelectric conversion layer and then drying the coating material to form a charge transport layer; A method for producing a photoelectric conversion element, comprising: The method for producing a photoelectric conversion element is characterized in that the paint for the charge transport layer contains charge transport particles and an insulating resin. Effect of the Invention

[0013] According to the present invention, it is possible to provide a method for manufacturing a photoelectric conversion element that achieves both mass productivity and uniformity in photoelectric conversion efficiency. [Brief description of the drawings]

[0014] [Figure 1]1 is a schematic diagram of a layer structure in a thickness direction of a first embodiment of a photoelectric conversion element of the present invention. [Diagram 2] 1 is a perspective view showing a schematic diagram of an embodiment of a moving body including a photoelectric conversion element of the present invention; [Diagram 3] FIG. 1 is a perspective view illustrating a schematic diagram of one embodiment of a building material including a photoelectric conversion element of the present invention. [Figure 4] 1 is a schematic cross-sectional view of one embodiment of a photoelectric conversion element of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention will be described in detail below with reference to preferred embodiments. <One embodiment> One embodiment is a method for manufacturing a photoelectric conversion element. The method for producing a photoelectric conversion element of the present invention includes the steps of: A step (A) of forming a photoelectric conversion layer including a crystal having a perovskite structure by using a large-area film formation method; A step (B) of applying a coating material for a charge transport layer onto the surface of the photoelectric conversion layer and then drying the coating material to form a charge transport layer; A method for producing a photoelectric conversion element, comprising: The coating material for the charge transport layer is characterized by containing charge transport particles and an insulating resin.

[0016] As a result of investigations, the present inventors have found that by manufacturing a photoelectric conversion element having a charge transport layer according to the above-mentioned process, a photoelectric conversion element that is both mass-producible and has a uniform photoelectric conversion efficiency can be obtained. The reason for this is considered to be as follows.

[0017] 4 is a schematic cross-sectional view of one embodiment of the photoelectric conversion element of the present invention. The photoelectric conversion element 1 has a second electrode 3, a photoelectric conversion layer 11, a charge transport layer having charge transport particles 12 and an insulating resin 13, 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 a current can be extracted by connecting the first electrode 7 and the second electrode 3 with an external circuit.

[0018] First, by forming the photoelectric conversion layer 11 using a large-area film formation method, mass productivity can be improved. By using the large-area film formation method, it becomes possible to fabricate many photoelectric conversion elements 1 in a limited time, and manufacturing costs can be reduced. In addition, the connectivity with the previous and next processes in the manufacturing line is improved, and application to the roll-to-roll method is also possible. Unlike the formation of other layers, the formation of the photoelectric conversion layer 11 requires appropriate fabrication of perovskite crystals, and therefore is highly difficult to fabricate. Therefore, compared to the formation of other layers, it is important to improve mass productivity in the formation of the photoelectric conversion layer.

[0019] The photoelectric conversion layer 11 made of perovskite crystals may have unevenness on the crystal surface and gaps between crystal grains. If defects such as these unevenness or gaps exist, the photoelectric conversion efficiency decreases and deterioration is likely to progress due to oxygen or the like entering the defects, so it is preferable to fill them with a charge transport layer or the like. However, if a low-resistance charge transport layer is formed on the surface of the photoelectric conversion layer made of crystals with a perovskite structure, the surface on the side of the unevenness or gaps with respect to the flow of charges will be covered with a low-resistance material.

[0020] As a result, electrons and holes are more likely to recombine, which can reduce the photoelectric conversion efficiency. In addition, when a high-resistance charge transport layer is formed on the surface of a photoelectric conversion layer made of crystals with a perovskite structure, charge exchange is inhibited, which can reduce the conversion efficiency of the photoelectric conversion element.

[0021] On the other hand, when a charge transport layer is formed on a perovskite crystal with charge transport particles 12 and insulating resin 13, the charge transport particles 12 and insulating resin 13 exist independently. As a result, the insulating resin 13 preferentially penetrates into the side surfaces of the irregularities and gaps in the perovskite crystal, suppressing the recombination of electrons and holes that occurs there.

[0022] At the same time, it is believed that the charge transporting material is present as particles on the perovskite crystal, so that the insulating resin 13 does not become an obstacle to charge transport, and the efficiency of charge transport from the perovskite crystal to the first electrode 7 is maintained.

[0023] Furthermore, as a result of intensive research by the present inventors, it was found that the unevenness and gaps in the photoelectric conversion layer are more likely to occur when a large-area film formation method is used for film formation, and the effect of improving the uniformity of the conversion efficiency of the photoelectric conversion element by forming the above-mentioned charge transport layer is further enhanced. The following reasons, for example, are considered to be the reasons why the unevenness is more likely to occur in the photoelectric conversion layer when a large-area film formation method is used.

[0024] First, the photoelectric conversion layer is formed in a large area. When the photoelectric conversion layer is formed in a large area, the probability of unevenness or gaps occurring somewhere increases with the increase in area. In general, if there is even one defect in the photoelectric conversion layer of a photoelectric conversion element, carrier recombination and sample deterioration will progress from that point, and the photoelectric conversion efficiency and durability will decrease more than the area of ​​the defective part.

[0025] Another factor is the method of forming the photoelectric conversion layer. In research-level experiments, the photoelectric conversion layer is often formed by combining a method of forming a uniform wet film by rotating the substrate (hereinafter also referred to as the "spin coating method") with a method of growing crystals with a perovskite structure by applying a poor solvent to the wet film (hereinafter also referred to as the "poor solvent method").

[0026] When considering mass production, the process of applying a poor solvent poses problems in terms of the environmental impact and the cost of requiring a separate process to remove the solvent, so methods that promote the growth of crystals with a perovskite structure by spraying gas or reducing pressure are often used. These methods have a slower rate of crystallization compared to the poor solvent method, in which the good solvent in the material is instantly replaced, so there is a difference in the size of the crystals obtained, and unevenness is likely to occur in the photoelectric conversion layer. As explained above, the respective components exert a synergistic effect on each other, thereby making it possible to achieve the effects of the present invention.

[0027] The present invention will be described in detail below with reference to preferred embodiments. The present invention is not limited to the following embodiments, and any modifications or improvements to the following embodiments based on the ordinary knowledge of a person skilled in the art without departing from the spirit of the present invention are also included in the scope of the present invention.

[0028] In this specification, the term "layer" refers not only to a layer having a clear boundary or a flat thin-film layer, but also to a layer having a concentration gradient in which the contained elements change gradually, or to a layer that can form a complex structure together with other layers. Elemental analysis of a layer can be performed, for example, by performing TOF-SIMS / FE-TEM / EDS line analysis measurement 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 the layer.

[0029] 1 is a cross-sectional view showing a schematic configuration of one embodiment of a photoelectric conversion element of the present invention. The photoelectric conversion element 1 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 a current can be extracted by connecting the first electrode 7 and the second electrode 3 to an external circuit.

[0030] The photoelectric conversion layer 5 is excited by light incident through the substrate 2, the second electrode 3, and the electron transport layer 4, or the first electrode 7 and the charge transport layer 6, and generates electrons or holes. That is, the photoelectric conversion layer 5 generates a current between the first electrode 7 and the second electrode 3. The electron transport layer 4 is a layer disposed between the photoelectric conversion layer 5 and two electrodes (the second electrode 3 and the first electrode 7), and may not be formed in some cases. A form in which a plurality of electron transport layers 4 and photoelectric conversion layers 5 are laminated may be used. Such a form may also be called a tandem structure. Each member will be described below. In addition, a photoelectric conversion element may be fabricated on the substrate 2 in the order of the first electrode 7, the charge transport layer 6, the photoelectric conversion layer 5, the electron transport layer 4, and the second electrode 3.

[0031] [Step of forming a photoelectric conversion layer (step (A))] The method for producing a photoelectric conversion element of the present invention includes a step (A) of forming a photoelectric conversion layer containing crystals with a perovskite structure by using a large-area film formation method. Large area film formation methods can be divided into coating methods and vapor deposition methods.

[0032] Vapor deposition is a method of forming a film by volatilizing solid raw materials and then re-solidifying them on the surface of a substrate. Vapor deposition methods include physical vapor deposition (PVD) and chemical vapor deposition (CVD). Examples of PVD methods include co-evaporation, pulsed laser deposition (PLD), electron beam evaporation, and molecular beam epitaxy. Examples of CVD methods include thermal CVD, plasma CVD, and atomic layer deposition (ALD).

[0033] The coating method is a method in which a coating liquid for each layer described below is prepared, coated on a desired substrate or layer, and dried. In the method for producing a photoelectric conversion element of the present invention, the step (A) preferably includes a step (A-1) of uniformly coating a coating material for the photoelectric conversion layer, and a step (A-2) of drying the coating material for the photoelectric conversion layer. In this way, the mass productivity of the method for producing a photoelectric conversion element of the present invention can be further improved.

[0034] Examples of the process (A-1) include dip coating, spray coating, inkjet coating, screen coating, roll coating, gravure coating, die coating, blade coating, curtain coating, bar coating, etc. 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.

[0035] Photoelectric conversion layers require general film formation techniques and the production of perovskite crystals in the targeted state, making them very difficult to produce in large areas. The nature of spin coating requires the substrate or film to be rotated at high speed, which poses safety and uniformity issues when producing large areas. In addition, spin coating requires batch production, which creates issues when connecting with previous and subsequent processes on the production line, making the spin coating method unsuitable for large-area film formation of photoelectric conversion layers.

[0036] The method of the above-mentioned step (A-1) is merely an example, and a coating method obtained by improving these general-purpose coating methods may also be used. Moreover, the step (A-1) may be used alone or in combination with other coating methods. Among these, in the manufacturing method of the photoelectric conversion element of the present invention, from the viewpoint of being able to further increase mass productivity, it is preferable that the step (A-1) includes a coating step by any one coating method selected from the group consisting of die coating, blade coating, roll coating, spray coating, inkjet coating, gravure coating, and screen coating, and it is more preferable that the step (A-1) includes die coating.

[0037] Dip coating is a method of coating a substrate by immersing it in paint and then pulling it out. Spin coating is a method of dripping paint onto a substrate and rotating it to form a uniform coating film by centrifugal force. Spray coating is a method of forming a coating film by spraying paint onto the substrate surface. Inkjet coating is a method of forming a uniform coating film by dripping paint drop by drop onto the substrate surface.

[0038] Screen coating is a coating method that uses a plate made of a screen mesh woven from synthetic or metal fibers. The paint passes through the mesh of the screen mesh and is applied to the substrate. Roll coating is a coating method that uses one or more rollers to obtain an optimal coating surface. There are a wide variety of applications for roll coating, including a method in which the amount of paint placed on the roller is controlled in advance using a die coat or blade coat, and then applied to the substrate, a method in which a roller is used to control the gap of the paint passing through and make the coating film uniform, and a method such as the roll-to-roll method in which a deformable film such as a film is used to make the coating surface uniform.

[0039] Gravure coating is a method of applying paint by attaching it to a gravure roll with an uneven surface and transferring it to a substrate. Die coating is a method of forming a coating film by extruding the paint at a uniform flow rate in the width direction through a slit with a width called a slot die, forming a liquid pool called a bead between the substrate and the slit.

[0040] Blade coating is a method of forming a uniform coating film by passing paint dripped onto a substrate between the substrate and a blade. Curtain coating is a method of forming a coating film by extruding paint from a wide slit at a uniform flow rate in the width direction and transferring the paint directly onto the substrate without forming puddles. Bar coating is a method of forming a uniform coating film by passing paint dripped onto a substrate between bars with grooves at the back.

[0041] Step (A-2) is a step of drying the wet film of the paint for the photoelectric conversion layer obtained in step (A-1) to produce a film of perovskite crystals. In addition to drying a typical wet film, step (A-2) is also a step of generating nuclei of perovskite crystals and growing them.

[0042] A fast drying speed is preferable because slow drying can cause the wet film to move during drying, resulting in unevenness in the film, and the number of perovskite crystal nuclei can be so small that spaces tend to form between the perovskite crystals.On the other hand, if drying is too fast, too many perovskite crystal nuclei are generated, resulting in small individual perovskite crystals.

[0043] As the perovskite crystals become smaller, the number of interfaces of the perovskite crystals increases, which leads to a decrease in photoelectric conversion efficiency due to an increase in interface resistance, and a decrease in durability due to the migration of raw material ions of the perovskite crystals across the interfaces. Therefore, it is preferable that the drying speed in step (A-2) is within an appropriate range.

[0044] Examples of step (A-2) include the poor solvent method, gas quenching method, reduced pressure method, rapid heating method, air drying, etc. The poor solvent method is a method in which a poor solvent is applied to a wet film obtained by a coating method to instantly replace the good solvent in the paint for the photoelectric conversion layer and generate perovskite crystals. Since the good solvent is instantly replaced, many nuclei of perovskite crystals are generated.

[0045] Therefore, defects in the film are less likely to occur, the roughness is likely to be small, and each crystal is likely to be small. The gas quenching method is a method of producing perovskite crystals by promoting the drying of the wet film by blowing gas. Since the decomposition of perovskite crystals is promoted by moisture, it is preferable that the gas to be blown has a low moisture content.

[0046] Examples of the gas to be blown include nitrogen gas and dry air. Hot air may be blown by heating the gas in advance. The decompression method is a method of drying the wet film by promoting the evaporation of the solvent in the wet film by reducing the pressure in the space in which the wet film exists.

[0047] The rapid heating method is a method of promoting drying by heating a wet film. Examples of heating methods include a method of directly heating the substrate by contacting a heat source with the substrate, and a method of indirectly heating the substrate by using infrared rays, etc.

[0048] Among these, the method for producing a photoelectric conversion element of the present invention is preferably such that step (A-2) does not include a step of applying a poor solvent to the raw material of the crystal of the perovskite structure (does not include a poor solvent method).Since the poor solvent method requires the additional use of a solvent that places a burden on the environment, it is preferable not to include the poor solvent method from the viewpoint of reducing the environmental burden and the cost of adding a step of removing the poor solvent.

[0049] In the case of a method that does not use the poor solvent method, the rate of nucleation of perovskite crystals is slower than that of the poor solvent method, so that defects in the film are relatively likely to occur, roughness is likely to increase, and each crystal is likely to become large. In the manufacturing method of the photoelectric conversion element of the present invention, the step (A-2) is preferably a step of drying the paint for the photoelectric conversion layer by spraying gas using a gas spraying means (a step using the gas quenching method). The gas quenching method is excellent in cost because the device can be relatively easily assembled, and can dry the wet film at a desired speed.

[0050] In the method for producing a photoelectric conversion element of the present invention, in step (A), the deposition area of ​​the photoelectric conversion layer is 5 cm 2 It is preferable that the length is at least 20cm. 2 More preferably, the above ratio is satisfied. In this way, mass productivity can be improved and the recombination suppression effect of the insulating resin can be enhanced. The larger the deposition area of ​​the photoelectric conversion layer, the better the mass productivity. In addition, the larger the deposition area, the more likely it is that uneven shapes and voids will occur in the photoelectric conversion layer, and the more likely it is that the recombination suppression effect of the insulating resin will be exhibited.

[0051] In the present invention, the photoelectric conversion layer may be formed by depositing the raw material of the perovskite crystal at once, or may be formed by dividing the raw material into several times. When the raw material is divided into several times and then deposited, the effect of the present invention can be achieved by including step (A) in at least one of the divided times.

[0052] In order to completely remove the solvent or dispersion medium from the liquid containing the material of the photoelectric conversion layer, an annealing treatment may be performed under reduced pressure or in an inert atmosphere (nitrogen or argon atmosphere). The temperature of the annealing treatment is preferably 40°C or higher and 300°C or lower, and more preferably 50°C or higher and 150°C or lower. Note that the annealing treatment is preferable because it may increase the contact area at the interface between the stacked layers by allowing the materials constituting each layer to penetrate into each other, thereby increasing the short-circuit current.

[0053] [Step of forming a charge transport layer (Step B)] The method for producing a photoelectric conversion element of the present invention includes a step (B) of forming a charge transport layer by applying a coating material for a charge transport layer onto the surface of a photoelectric conversion layer and then drying the coating material. In the step (B), examples of the method for applying the coating material for the charge transport layer include dip coating, spin coating, spray coating, inkjet coating, screen coating, roll coating, gravure coating, die coating, blade coating, curtain coating, bar coating, and the like.

[0054] Unlike the formation of a photoelectric conversion layer, the charge transport layer is less difficult to form since there is no formation of perovskite crystals, and therefore a spin coating method can also be used. Among these, from the viewpoint of enabling higher mass productivity, the method for producing a photoelectric conversion element of the present invention preferably includes a coating step by any one coating method selected from the group consisting of die coating, blade coating, roll coating, spray coating, inkjet coating, gravure coating, and screen coating, and more preferably includes a coating step by die coating.

[0055] Step (B) may be used alone or in combination with other coating methods. Furthermore, in the method for producing a photoelectric conversion element of the present invention, from the viewpoints of further improving mass productivity, reducing equipment costs, and improving connectivity with other steps, it is preferable that step (B) includes a coating step using the same coating method as step (A-1).

[0056] The method for drying the coating material for the charge transport layer is not particularly limited, but examples thereof include heating, blowing gas, reducing pressure, etc. Among these, drying by heating is preferred from the viewpoint of simplicity.

[0057] In step (B), it is preferable to use a method of applying a resin solution in which an insulating resin is dissolved, which allows the insulating resin to easily and preferentially penetrate into the gaps between the perovskite crystal grains.

[0058] In addition, in step (B), for example, a method of disposing charge transport particles on the surface of the photoelectric conversion layer and then applying a resin solution having an insulating resin dissolved therein, a method of applying a resin solution having an insulating resin dissolved therein on the surface of the photoelectric conversion layer and then disposing charge transport particles, or a method of applying a resin solution having an insulating resin dissolved therein and a solution having charge transport particles dispersed therein on the surface of the photoelectric conversion layer may be used.

[0059] [Charge transporting particles] In the method for producing a photoelectric conversion element of the present invention, the paint for the charge transport layer contains charge transport particles. By containing the charge transport particles, it becomes possible to smoothly flow the charges generated in the photoelectric conversion layer. The average particle size of the charge transport particles is 1.0×10 1 nm or more 3.0×10 2 It is preferable that the thickness is less than nm.

[0060] Within the above range, the charge transport particles can be prevented from penetrating between the perovskite crystal grains, and the uniformity of the film can be maintained, thereby suppressing the loss of charge transport properties. The particle size of the charge transport particles contained in the charge transport layer can be determined as the volume average particle size from the particle size distribution determined by an image imaging method using a scanning electron microscope (SEM).

[0061] The particle shape of the charge transport particles is preferably a particle with a small aspect ratio, such as an approximately spherical shape, a rugby ball shape, a cylindrical shape, a flat shape, etc. For example, if the particle has a large aspect ratio, such as a needle shape, the particles must be deposited in the same direction in order to improve the coverage.

[0062] In other words, even if the particles can be deposited on the photoelectric conversion layer without excessive aggregation while remaining in a stable dispersion state, the shape of the particles tends to leave some parts of the photoelectric conversion layer that are not covered with the charge transport particles.In addition, the particles tend to pile up on other particles, so that voids tend to remain between the photoelectric conversion layer and the layer of charge transport particles, which reduces the effect of the present invention.

[0063] The aspect ratio of the charge transporting particles is preferably 5 or less, more preferably 3 or less. Examples of particle shapes that reduce the effect of the present invention include needles and fibers. The aspect ratio is greater than 10.

[0064] The shape and aspect ratio of the charge transport particles can be confirmed by a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

[0065] Specific examples of materials for the charge transporting particles include phthalocyanine pigments, azo pigments, lake pigments, quinacridone pigments, dioxazine pigments, perylene pigments, and isoindolinone pigments.

[0066] In the method for producing a photoelectric conversion element of the present invention, the charge transporting particles preferably contain a cyclic conjugated compound formed by covalently bonding a plurality of pyrrole rings. By forming the cyclic conjugated compound formed by covalently bonding a plurality of pyrrole rings into charge transporting particles, the charge transporting particles exhibit high charge transporting ability.

[0067] In the method for producing a photoelectric conversion element of the present invention, the charge transporting particles preferably contain a phthalocyanine compound, more preferably contain a structure represented by the following formula (Pc-2), and further preferably contain a hydroxygallium phthalocyanine compound. The charge transporting particles can more efficiently transport charges generated in the photoelectric conversion layer. [ka] (M in the above formula (Pc-2) is H 2 , a metal atom having a ligand, or a metal atom having no ligand.

[0068] The structure of chemical substances such as the charge transport particles of the present invention can be confirmed by a nuclear magnetic resonance (NMR) method. In particular, M in the above formula (Pc-2) is H 2 When this is the case, the above formula (Pc-2) is represented by the following formula (Pc-1). [ka]

[0069] [Insulating resin] In the method for producing a photoelectric conversion element of the present invention, the paint for the charge transport layer contains an insulating resin. Specific examples of the insulating resin include polyacetal resin, acrylic resin, polyarylate resin, polycarbonate resin, polyvinyl acetate resin, polyester resin, polyamide resin, polyurethane resin, and polystyrene resin. In the method for producing a photoelectric conversion element of the present invention, the insulating resin is preferably a polyvinyl acetal resin or a polyvinyl butyral resin among these. This insulating resin is easily in close contact with the charge transport material (charge transport particles), and can form a more effective charge distribution.

[0070] In the method for producing a photoelectric conversion element of the present invention, the glass transition point of the insulating resin is preferably less than 100° C., and more preferably 95° C. or less. Within this range, it is easy to come into close contact with the charge transport material (charge transport particles), and a more effective charge distribution can be formed. The glass transition temperature can be determined by a differential scanning calorimeter (DSC).

[0071] In the present invention, the molecular weight of the insulating resin is preferably 10,000 or more. In the present invention, it is preferable that the charge transport layer contains an aromatic ring compound having a hydroxyl group, which is different from the charge transport material (charge transport particles) and the insulating resin. By containing the aromatic ring compound having a hydroxyl group, the charge transport material (charge transport particles) and the insulating resin can be more easily contacted with each other, and a more effective charge distribution can be formed.

[0072] In the method for producing a photoelectric conversion element of the present invention, the photoelectric conversion element may have a second charge transport layer that does not contain charge transport particles on the charge transport layer between the first electrode and the charge transport layer, which may facilitate the transfer of carriers to the electrode.

[0073] Each layer will be described below. [Photoelectric conversion element] The photoelectric conversion element of the present invention is characterized by including a photoelectric conversion layer containing a crystal of a perovskite structure, and a charge transport layer having charge transport particles and an insulating resin. The photoelectric conversion element may have 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.

[0074] In order to improve the photoelectric conversion efficiency, photoelectric conversion elements may be stacked in a tandem configuration. The photoelectric conversion elements to be stacked are not limited to the type of photoelectric conversion element, and may be a perovskite solar cell using a perovskite crystal in the photoelectric conversion layer, a silicon solar cell, a CIGS solar cell, or the like.

[0075] The method for forming each layer including the photoelectric conversion layer and the charge transport layer of the photoelectric conversion element of the present invention includes a coating method and a vapor deposition method. Examples of the coating method include dip coating, spin coating, spray coating, inkjet coating, meniscus coating, screen coating, roll coating, die coating, blade coating, curtain coating, and wire bar coating. A desired method can be selected from these film formation methods according to each layer.

[0076] Each layer will be described below. 〔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.

[0077] 〔electrode〕 The photoelectric conversion element of the present invention has a first electrode and a second electrode. The materials of the first electrode 7 and the second electrode 3 are not particularly limited, and conventionally known materials can be used. For example, metals such as gold, silver, titanium, and copper, sodium, sodium-potassium alloy, lithium, magnesium, carbon, carbon nanotubes, aluminum, magnesium-silver mixture, magnesium-indium mixture, aluminum-lithium alloy, Al / Al 2 O 3 mixtures, Al / LiF mixtures, etc.

[0078] Transparent electrode materials include, for example, CuI, ITO (indium tin oxide), and SnO 2 Examples of the conductive transparent materials include AZO (aluminum zinc oxide), IZO (indium zinc oxide), GZO (gallium zinc oxide), FTO (fluorine-doped tin oxide), ATO (antimony-doped tin oxide), conductive transparent polymers, etc. These materials may be used alone or in combination of two or more.

[0079] 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 also serve as a reflective layer formed of a light-reflective material, or may be a transparent electrode provided with a reflective layer on the side opposite to the light incident side. When the first electrode 7 is on the light incident side, the second electrode 3 may be a transparent electrode and the substrate 2 may be a reflective layer. The electrodes may be patterned electrodes.

[0080] [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. In the step of forming the first electrode and the step of forming the second electrode, an appropriate method can be selected according to the material of the first electrode and the material of the second electrode, respectively. Examples of such methods include, but are not limited to, sputtering vacuum deposition, CVD (vapor phase deposition), and SPD (spray pyrolysis deposition). The materials of the first electrode and the second electrode are as described above. When either or both of the first electrode and the second electrode are transparent electrodes, the thickness of the transparent electrode is preferably 0.03 μm or more and 3 μm or less.

[0081] When manufacturing solar cells, cutting is generally performed between each process to form circuits. Examples of cutting include mechanical patterning and laser patterning.

[0082] [Photoelectric Conversion Layer] The photoelectric conversion element of the present invention has a photoelectric conversion layer including a crystal having a perovskite structure. The photoelectric conversion layer 5 has a crystal having a perovskite structure. The crystal having a perovskite structure used in the present invention is preferably represented by the following general formula [1]. ABX 3 [1]

[0083] 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. As A in the above general formula [1], for example, in the case of an organic molecule, C p Nm H n (wherein p, m, and n are all positive integers) are preferred. Specific examples include methylammonium and formamidium.

[0084] 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.

[0085] When the constituent A cations are too large to fit within the 3D perovskite crystal, they form 2D perovskite crystals, 2.5D perovskite crystals that have both 2D and 3D properties, bilayer crystals of 3D and 2D perovskite structures, or mixed 3D and 2D perovskite crystals, all of which can function as a photovoltaic layer.

[0086] A bilayer crystal of 3D and 2D perovskite is a crystal in which 3D and 2D perovskite structure crystals are stacked as independent, separate layers, while a mixed 3D / 2D perovskite is a crystal with a structure that combines regions or domains of both 2D or 2.5D layered and 3D perovskite structure crystals.

[0087] The crystals having a two-dimensional perovskite or 2.5-dimensional perovskite structure are preferably represented by the following general formulas [2] to [4], where 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]

[0088] 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.

[0089] 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, iso-butylammonium, 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, guanidinium, propylammonium, propargylamine, alkylammonium, cyclohexylmethylammonium, 4-(aminomethyl)piperidinium, piperidinium, pyrrolidinium, and the like. ammonium, cyclohexylammonium, 4-fluorophenethylammonium, 4-fluorophenethylammonium, trifluoromethylbenzylammonium, pentafluorobenzylammonium, pentafluorophenylethylammonium, 4-methoxyphenethylammonium, imidazolium, pyridinium, 3-thiophenemethylammonium, 2-thiopheneethylammonium, 2-thiopheneformamidium, 2-thiophenemethylammonium, 1-naphthylmethylammonium, 2-naphthylmethylammonium, phenethylammonium, phenylammonium, benzylammonium, 2,5-thiophenedimethylammonium, phenylpropylammonium, 1,4-phenylenedimethanamine, 3-phenyl-2-propene-1-ammonium, phenylbutylammonium, 4-tert-butyl-benzylammonium, 3-(aminomethyl)piperidinium are preferred.

[0090] 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.

[0091] X in the above general formulas [1] to [4] is a halogen atom, such as chlorine, bromine, and iodine. These halogen atoms may be used alone or in combination of two or more. Among them, halogen atoms are preferred because the perovskite crystals are easily soluble in organic solvents by containing halogen in the structure, making it possible to apply the perovskite crystals to inexpensive printing methods and the like. Furthermore, iodine is more preferred because the energy band gap of the perovskite crystals is narrowed.

[0092] Specifically, 3D perovskites, 2D perovskites, and mixed 3D / 2D perovskites are synthesized using MAPbI 3 or FAPbCl 3 , FAPbI 3 , MAPbI x Br 3-x , MAPbI x Cl 3-x , Cs 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.83 Br 0.17 ) 3 , {Cs x1 (FA x2 MA 1-x2 ) 1-x1} x3 Pb(I x4 Br 1-x4 ) x5 , Cs 0.05 FA 0.88 MA 0.07 PbI 2.56 Br 0.44、(FAPbI 3 ) 0.95 (MAPbBr 3 ) 0.05 、(FAPbI 3 ) 0.85 (MAPbBr 3 ) 0.15 、CsPbI 3 、CsPbBr 3 、Cs x (MA) 1-x 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 、(4FPEA) 2(FA 0.3 MA 0.7 ) 4 Pb 5 I 16 、(PDMA)FA 2 Pb 3 I 10 、(3AMPY)(MA) 3 Pb 4 I 13 、(PDMA)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 BUT 0.1 ) 2 MA 4 Pb 5 I 16 、(BA 0.9 BUT 0.1 ) 2 MA 3 Pb 4 I 13 、(4FPEA) 2 MA 3 Pb 4 I 13 、(4FPEA) 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 I 16 、(BA) 2 MA 3 Pb 4 I13 , CsSnBr 3 , CsSnI 3 , F.A. 0.75 MA 0.25 Sn 0.95 Ge 0.05 I 3 , FAMASnGeI 3 , FASnBr 3 , FASnI 3 , M.A. 2 Sn 3 I 8 , MASnBr 3 , MASnGeI 3 , MASnI 3 is preferred.

[0093] Depending on the purpose, the A site, B site, or X site in the above general formula may be adjusted to be under- or over-adjusted, and the combination of x1 to x5 may be changed depending on the purpose. Combinations of x1 to x5 are, for example, as shown in Table 1. Particularly preferred ranges are 0.03≦x1≦0.10, 0.80≦x2≦0.96, 0.95≦x3≦1.05, 0.80≦x4≦0.96, and 2.95≦x5≦3.05. MACl may be included as a material for forming perovskite crystals.

[0094] [Table 1]

[0095] In the above specific examples, "MA" stands for methylammonium, "FA" stands for formamidinium, "PEA" stands for phenethylammonium, "PTA" stands for phenyltriethylammonium, "ThMA" stands for 2-thiophenemethylammonium, "3BBA" stands for 3-bromobenzylammonium, "3AMPY" stands for 3-(aminomethyl)pyridine, "PDMA" stands for 1,4-phenylenedimethaneammonium, "TTDMA" stands for thieno[3,2-b]thiophene-2.5-diyldimethaneammonium, "4FPEA" stands for 4-fluorophenethylammonium, "BA" stands for butylammonium, and "TEA" stands for 2-thiophenethylammonium.

[0096] The crystal with the perovskite structure preferably has a cubic structure in which a metal atom B is located at the body center, an organic molecule A at each vertex, and a halogen atom X at the face center. Although the details are not clear, it is presumed that the presence of such a structure makes it easy to change the orientation of the octahedron in the crystal lattice, thereby increasing the mobility of electrons in the crystal with the perovskite structure and improving the photoelectric conversion efficiency of the photoelectric conversion element.

[0097] The organic-inorganic perovskite compound used in the present invention is preferably a crystalline semiconductor. The crystalline semiconductor means a semiconductor in which the scattering peak can be detected by measuring the X-ray scattering intensity distribution. By using the organic-inorganic perovskite compound as a crystalline semiconductor, the mobility of electrons in the organic-inorganic perovskite compound is increased, and the photoelectric conversion efficiency of the photoelectric conversion element is improved.

[0098] Furthermore, the photoelectric conversion layer according to the present invention may contain materials other than the crystals having the organic-inorganic perovskite structure, as long as the photoelectric conversion efficiency and charge transport properties are not impaired. The thickness of the photoelectric conversion layer according to the present invention is preferably 5 nm or more and 2000 nm or less. If the thickness is 5 nm or more, light can be sufficiently absorbed, and if the thickness is 2000 nm or less, the generated charge can be transported to each electrode. The more preferred lower limit is 50 nm or more, the more preferred upper limit is 1200 nm, the even more preferred lower limit is 100 nm, and the even more preferred upper limit is 1000 nm.

[0099] In the method for producing a photoelectric conversion element of the present invention, the photoelectric conversion layer preferably has voids. In a method for producing a photoelectric conversion layer that is suitable for mass production, voids are likely to occur for the above-mentioned reasons. In addition, when the photoelectric conversion layer has voids, the charge transport particles are likely to penetrate to the second electrode side of the photoelectric conversion layer, which may reduce the effect of suppressing recombination.

[0100] In the method for producing a photoelectric conversion element of the present invention, the size of the crystals of the perovskite structure of the photoelectric conversion layer is preferably 1.0 μm or more. Here, the size of the crystals means the major axis of the largest perovskite crystal observed. When the perovskite crystals are large, the perovskite surface is more likely to have an uneven shape, and the arithmetic mean roughness is large. In the method for producing a photoelectric conversion element of the present invention, the arithmetic mean roughness Ra of the surface of the photoelectric conversion layer is preferably 10 nm or more and 200 nm or less. When the arithmetic mean roughness Ra is 10 nm or more, the recombination suppression effect of the insulating resin is more easily exhibited.

[0101] Furthermore, when the arithmetic mean roughness Ra is greater than 200 nm, the charge transporting particles are more likely to penetrate into the second electrode side of the photoelectric conversion layer, and the recombination suppression effect may decrease. In the method for producing a photoelectric conversion element of the present invention, the arithmetic mean roughness Ra of the surface of the photoelectric conversion layer is more preferably 20 nm or more and 180 nm or less, and even more preferably 40 nm or more and 150 nm or less. In a method for producing a photoelectric conversion layer that is suitable for mass production, the perovskite crystals tend to become large for the above-mentioned reasons, and the arithmetic mean roughness tends to become large.

[0102] [Charge transport layer] In the photoelectric conversion element of the present invention, a charge transport layer is disposed between a photoelectric conversion layer and a first electrode, and the charge transport layer is formed on the surface of the photoelectric conversion layer from charge transport particles and an insulating resin. In the photoelectric conversion element of the present invention, it is preferable that the insulating resin is disposed between the crystals of the perovskite structure of the photoelectric conversion layer. The charge transport particles, insulating resin, and other items are as described above.

[0103] In the present invention, the charge transport layer contains charge transport particles that are P-type semiconductors and an insulating resin, and the ratio of the volume of the charge transport particles in the charge transport layer to the volume of the insulating resin in the charge transport layer is preferably 5 to 30. The ratio of the volume of the charge transport particles to the volume of the insulating resin can be determined, for example, by observing a cross section of the charge transport layer using a scanning electron microscope (SEM), or can be calculated from the weight and specific gravity of the charge transport particles and insulating resin added to the paint for the charge transport layer. The insulating resin has a volume resistivity of 10 8 Ω·cm or more.

[0104] In the method for producing a photoelectric conversion element of the present invention, the average film thickness of the charge transport layer is preferably 1 nm or more and 1000 nm or less, more preferably 5 nm or more and 500 nm or less, even more preferably 10 nm or more and 200 nm or less, and particularly preferably 50 nm or more and 200 nm or less. The larger the film thickness of the charge transport layer, the greater the effect of concealing voids generated in the photoelectric conversion layer, and the improvement of the conversion efficiency can be expected when the photoelectric conversion layer is produced by a large-area film formation method. In addition, by making the film thickness of the charge transport layer small, the decrease in current and power generation due to the charge transport layer acting as a resistor can be suppressed.

[0105] The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing the above-mentioned materials and solvent, forming this coating film on the photoelectric conversion layer, and drying it. Examples of the solvent used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, alcohol-based solvents or aromatic hydrocarbon-based solvents are preferred.

[0106] [Second Charge Transport Layer] In the present invention, from the viewpoint of film compatibility of the charge transport layer 6, it is preferable to further have a second charge transport layer that does not contain charge transport particles between the charge transport layer 6 and the first electrode .

[0107] Examples of materials for the second charge transport layer 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 with the film interface, it is preferable that the compound has an aromatic ring, and Spiro-OMeTAD, PTAA, and phthalocyanine compounds are preferable.

[0108] The second charge transport layer may have a dopant as an additive to improve the charge transport ability. Examples of materials that can be used as a dopant include lithium compounds such as bis(trifluoromethanesulfonyl)imide lithium, cobalt compounds such as [tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(3)tris(bis(trifluoromethylsulfonyl)imide)], boron compounds such as tetrakis(pentafluorophenyl)borate, molybdenum compounds such as tris[1-(methoxycarbonyl)-2-(trifluoromethyl)-ethane-1,2-dithiolene]molybdenum, organic compounds having a tetracyanoquinodimethane skeleton such as 2,3,4,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, and organic compounds having a pyridine skeleton such as 4-tert-butylpyridine.

[0109] [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.

[0110] The material of the electron transport layer 4 is not particularly limited, and examples thereof include N-type conductive polymers, N-type low-molecular 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, naphthalenetetracarboxylic 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 chloride (2), tin chloride (4), tin chloride (2) dihydrate, or tin chloride (4) pentahydrate.

[0111] The thickness of the electron transport layer 4 is preferably 1 nm at the lower limit and 2000 nm at the upper limit. If the thickness of the electron transport layer 4 is 1 nm or more, holes can be blocked sufficiently, and if it is 2000 nm or less, it is unlikely to become a resistance during electron transport, and the photoelectric conversion efficiency is high. The thickness is more preferably 3 nm at the lower limit and 1000 nm at the upper limit, and even more preferably 5 nm at the lower limit and 500 nm at the upper limit.

[0112] [Control of particle size of charge transport particles] The particle size of the charge transporting particles can be changed by dispersing the coating liquid for the charge transport layer with a paint shaker, and the particle size can be reduced by extending the dispersion time, and the particle size can be further reduced by centrifuging the coating liquid for the charge transport layer.

[0113] [Modularization process] The method for producing a photoelectric conversion element of the present invention may include a modularization step of sealing the element having the electrodes formed thereon. Examples of the sealing method 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 preventing adhesion between elements that occurs when the elements are wound in a roll-to-roll system, the surfaces of the encapsulated elements may be subjected to a hairline treatment.

[0114] [Application example] Application examples of the present invention include photoelectric conversion devices, moving objects, and building materials. [Photoelectric conversion device] The photoelectric conversion device of the present invention has the above-mentioned photoelectric conversion element. A photoelectric conversion device can be configured by using a plurality of the photoelectric conversion elements of the present invention. When a plurality of photoelectric conversion elements are connected, the photoelectric conversion device can 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 in order to increase the output voltage.

[0115] The photoelectric conversion device 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. For example, a secondary battery using lithium ions or the like, an all-solid-state battery, an electric double layer capacitor, etc. may be mentioned. In order to impart a function such as maintaining or increasing the amount of incident light, a surface layer that is resistant to water and dirt, or a function of collecting or guiding light may be added.

[0116] [Mobile object] The moving body of the present invention has the above-mentioned photoelectric conversion element. FIG. 2 is a perspective view showing an embodiment of a moving body equipped with the photoelectric conversion element of the present invention. The moving body 30 has the photoelectric conversion element 31 of the present invention and a vehicle 32 equipped with the photoelectric conversion element 31. The photoelectric conversion element 31 is arranged at a position where the vehicle 32 can receive external light. If the moving body 30 is an automobile, it may be arranged on the roof. The electric energy obtained by the photoelectric conversion element 31 may be used as the power of the moving body 30 or as the power of other electric devices. The electric energy generated from the power of the moving body 30 may be used to power the photoelectric conversion element 31. If the moving body 30 is an automobile, frictional energy generated by braking may be converted into electric energy and used to control the photoelectric conversion element 31.

[0117] The moving body 30 may be, for example, an automobile, a motorcycle, a railroad vehicle, a ship, an artificial satellite, an airplane, or a flying object including a drone. The configuration of the body 32 of the moving body 30 is not particularly limited, but it is preferable that the body 32 be made of a high-strength material.

[0118] [Building materials] The building material of the present invention has the above-mentioned photoelectric conversion element. Fig. 3 is a perspective view showing an 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 exteriors 44a and 44b.

[0119] The building material 40 of the present invention may have a heat dissipation member 43 having a higher thermal conductivity than the photoelectric conversion element 41. When used on a roof or the like, the temperature of the photoelectric conversion element 41 may increase due to sunlight, and the photoelectric conversion efficiency may decrease. The use of the heat dissipation member 43 can reduce the decrease in photoelectric conversion efficiency. Examples of the heat dissipation member 43 include metal, alloy, liquid metal, and liquid resin.

[0120] Furthermore, the building material 40 of the present invention may have exteriors 44a and 44b. The exteriors 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. A material with low light absorption and high heat insulation is preferable.

[0121] In addition to the above application examples, other application examples include the following: Portable devices, such as calculators, sensors, and small solar panels. Wearable devices, such as eyeglass-type terminals, wristwatch-type terminals, and portable medical equipment. Sheet structures supported by multiple frames, such as tents, vinyl greenhouses, and truck beds. Fixed structures, such as 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.

[0122] [Confirmation of the deposition area of ​​the photoelectric conversion layer] The deposition area of ​​the photoelectric conversion layer can be measured, for example, by acquiring an image of a sample on which the photoelectric conversion layer is formed and processing the image. In addition, if the shape of the deposited film is a general shape such as a circle or a rectangle, the length of each side of the sample on which the photoelectric conversion layer is formed can be measured using a ruler, and the deposition area can be calculated.

[0123] Since perovskite crystals have a color such as black, the locations where the photoelectric conversion layer is formed can be confirmed with the naked eye. In addition, perovskite crystals can be distinguished from other layers by the difference in contrast of the observed image when observed with a scanning electron microscope (described later) or by composition analysis using the SEM-EDX function.

[0124] In the present invention, the photoelectric conversion layer was formed into a rectangular shape. Since the photoelectric conversion layer of the present invention is black, the portion where the photoelectric conversion layer was formed was visually confirmed. The length of each side of the obtained photoelectric conversion layer was measured using a ruler, and the film formation area was calculated.

[0125] [Checking for voids in the photoelectric conversion layer] The voids in the photoelectric conversion layer can be confirmed using a scanning electron microscope (hereinafter also referred to as "SEM"). For example, the voids can be confirmed by observing the surface of a sample in which the photoelectric conversion layer has been formed, or by cutting the photoelectric conversion element and observing the cross section.

[0126] In the present invention, the presence or absence of voids in the photoelectric conversion layer was confirmed by cutting the photoelectric conversion element, fixing it to an inclined sample stage, and then observing the cross section using an SEM (apparatus: Carl Zeiss, SmartSEM). In the observation, the charge transport layer was distinguished from other layers based on the difference in contrast of the observed image and composition analysis using the SEM-EDX function, and voids were confirmed from images taken at a magnification of 10,000 times. This was photographed at 10 random locations, and the total number of voids confirmed was counted.

[0127] [Measurement of average film thickness] The average film thickness of the photoelectric conversion layer or the charge transport layer can be measured, for example, by cutting the photoelectric conversion element and observing the cross section using an SEM. In the present invention, the average film thickness of the photoelectric conversion layer and the charge transport layer was confirmed by cutting the photoelectric conversion element, fixing it to an inclined sample stage, and then observing the cross section using an SEM (apparatus: Carl Zeiss, SmartSEM). In the observation, the charge transport layer was distinguished from other layers based on the difference in contrast of the observed image and composition analysis using the SEM-EDX function, and the average film thickness of the charge transport layer portion was measured by image processing of an image taken at a magnification of 50,000 times. This was taken at five random locations, and the average of the five average values ​​was taken as the average film thickness of the charge transport layer.

[0128] [Measurement of arithmetic mean roughness Ra of photoelectric conversion layer] The arithmetic mean roughness Ra of the photoelectric conversion layer is the roughness of the surface on the first electrode side. Examples of the measurement method include a method of measuring the photoelectric conversion layer after removing the first electrode and the charge transport layer from the photoelectric conversion element using an AFM / SPM, and a method of calculating from a cross-sectional image of the photoelectric conversion element.

[0129] In this embodiment, the arithmetic mean roughness Ra was calculated by image analysis of an image obtained by using an atomic force microscope AFM / SPM (MFP-3D Origin, Oxford Instruments) in AM-FM mode to obtain a height image. The measurement conditions were as follows: a cantilever: OMCL-AC-160TS (Olympus), a range of 90 μm × 90 μm, and a scanning frequency of 1 Hz. The number of X data points was 256, and the number of Y data points was 256.

[0130] [Measurement of the size of the perovskite crystals in the photoelectric conversion layer] The size of the crystals of the perovskite structure of the photoelectric conversion layer (hereinafter also referred to as "crystal size") can be confirmed using an SEM. For example, the size of the crystals can be confirmed by observing the surface of a sample on which the photoelectric conversion layer has been formed, or by cutting the photoelectric conversion element and observing the cross section.

[0131] In the present invention, the size of the crystals was measured as follows. First, the upper layer of the photoelectric conversion element was peeled off using a solvent that does not destroy the perovskite crystals, thereby exposing the perovskite crystals. Next, the sample with the exposed perovskite crystals was fixed to a stage, and the size was confirmed by surface observation using an SEM (device: Carl Zeiss, SmartSEM).

[0132] In the observation, perovskite crystals were distinguished from other layers based on the difference in contrast of the observed images and composition analysis using the SEM-EDX function, and the long diameter of the largest perovskite crystal was measured in an image taken at a magnification of 10,000x. This was done in three random locations, and the average value of the long diameter of the largest perovskite crystal in each image was taken as the size of the crystal. EXAMPLES

[0133] 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.

[0134] Example 1 Preparation of Charge-Transporting Particles 1 Process (1) In 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 a temperature of 30° C. and maintained at this temperature. Next, 3.75 parts of gallium trichloride were added at this temperature (30° C.). The water concentration of the mixture at the time of addition was 150 ppm.

[0135] 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, then cooled, and the product was filtered when the temperature reached 150°C. 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%.

[0136] Process (2) 4.65 parts of the chlorogallium phthalocyanine particles were dissolved in 139.5 parts of concentrated sulfuric acid at a temperature of 10° C., dropped into 620 parts of ice water under stirring to reprecipitate, and filtered under reduced pressure using a filter press. No. 5C (manufactured by Advantec Co., Ltd.) was used as the filter. The obtained wet cake (filtrate) was dispersed and washed with 2% ammonia water for 30 minutes, and then filtered using a filter press.

[0137] 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 solid content of 23% by mass at a yield of 71% by mass. These hydroxygallium phthalocyanine particles were dried in a Hyper Dry dryer (product name: HD-06R, frequency (oscillation frequency): 2455MHz ± 15MHz, manufactured by Japan Biocon) to obtain hydroxygallium phthalocyanine (OHGaPc) particles (crystals) with a water content of 1.0% by mass or less.

[0138] Process (3) Five parts of the hydroxygallium phthalocyanine (hereinafter also referred to as "HOGaPc") 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 Machine Manufacturing (now Imex), disk diameter 70 mm, number of disks 5) containing five parts of glass beads, filtered, and dried to obtain charge transport particles 1 (specific gravity 1.6). The aspect ratio was 3 or less.

[0139] Preparation of resin solution 1 1.0 g of polyvinyl butyral (product name: BM-2, manufactured by Sekisui Chemical Co., Ltd., specific gravity 1.6) was dissolved in 19 g of 2-propanol with stirring for 24 hours to obtain resin solution 1.

[0140] [Formation of Electron Transport Layer] Two square ITO-coated glass substrates with sides of 100 mm were cleaned, and a 5-fold diluted tin oxide (2) colloidal solution (15% water dispersion, manufactured by Alfa Aesar) was spin-coated onto them, followed by heating at 150°C for 30 minutes to form a thin-film electron transport layer with a thickness of 16 nm.

[0141] [Formation of photoelectric conversion layer] 8.245 g of lead iodide, 2.843 g of methylammonium iodide, and 0.362 g of methylammonium chloride were dissolved in 6.10 g of N,N-dimethylformamide and 7.45 g of N-methyl-2-pyrrolidone, and the mixture was stirred for 1 hour to prepare coating solution 1 for the photoelectric conversion layer. This coating solution was applied onto the electron transport layer heated to 55° C. using a die coater equipped with a die head having a width of 30 mm, and then dried by a gas quenching method and finally heated to obtain MAPbI 3 A black photoelectric conversion layer having a width of 30 mm, a length of 100 mm, a thickness of 600 nm, and an arithmetic mean roughness Ra of 125 nm was formed.

[0142] [Formation of Charge Transport Layer] 0.10 g of the charge transport particles 1 and 0.010 g of a calixarene compound (JP Patent Publication No. 2003-207913) were mixed with 10.6 g of 2-propanol, and 11 g of beads (zirconia beads, Treceram (registered trademark) zirconia beads, 0.3 mm) were encapsulated in this mixture, followed by dispersion using a paint shaker (manufactured by Toyo Seiki Co., Ltd.) for 7 hours.

[0143] Then, 0.20 g of resin solution 1 was added, and dispersion was performed again for 6 hours using a paint shaker to prepare a coating solution for the charge transport layer. This charge transport layer solution was applied onto the photoelectric conversion layer of one of the two substrates on which the photoelectric conversion layer was formed, using a die coater equipped with a 30 mm-wide die head, and then dried to form a charge transport layer with a thickness of 150 nm.

[0144] [Introduction of a second charge transport layer] 0.15 g of Spiro-OMeTAD as a material for the second charge transport layer was dissolved in 2.2 g of chlorobenzene. 36 μL of an acetonitrile solution obtained by dissolving 0.2 g of lithium bis(trifluoromethanesulfonyl)imide in 0.3 g of acetonitrile and 60 μL of 4-tert-butylpyridine (TBP) were added to the chlorobenzene solution and mixed.

[0145] Furthermore, 58 μL of an acetonitrile solution obtained by dissolving 0.11 g of [tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(3)tris(bis(trifluoromethylsulfonyl)imide)] in 0.3 g of acetonitrile was mixed to prepare a second charge transport layer coating solution 1. This was applied by spin coating onto the charge transport layer and onto the photoelectric conversion layer on which the charge transport layer was not applied, to form a second charge transport layer having a thickness of 100 nm.

[0146] [Formation of the first electrode] Three 25 mm square substrates were cut from the portion of the ITO-coated glass substrate on which the second charge transport layer was formed. Each of the obtained 25 mm square substrates had a thickness of 80 nm and an area of ​​0.09 cm. 2The gold electrodes were formed at 10 locations by vacuum deposition to obtain a photoelectric conversion element. The ratio of the volume of the charge transport particles to the volume of the insulating resin in the charge transport layer of the obtained photoelectric conversion element was 7.1.

[0147] Example 2 A photoelectric conversion element was obtained in the same manner as in Example 1, except that the ITO-coated glass substrate used in forming the electron transport layer was changed to a square substrate having a side length of 25 mm. In forming the first electrode, a gold electrode was formed on one substrate having a side length of 25 mm.

[0148] Example 3 In forming the photoelectric conversion layer, except that the wind speed of the gas quenching was increased, a photoelectric conversion element was obtained in the same manner as in Example 1. In forming the photoelectric conversion layer, blackening during gas quenching occurred earlier than in Example 1.

[0149] Example 4 A photoelectric conversion element is obtained in the same manner as in Example 3, except that in forming the photoelectric conversion layer, the wind speed of the gas quench in step (A-2) is further increased.

[0150] Example 5 A photoelectric conversion element is obtained in the same manner as in Example 1, except that methylammonium chloride was not used in preparing the coating solution 1 for the photoelectric conversion layer.

[0151] Example 6 In forming the photoelectric conversion layer, MAPbI was obtained by co-evaporating lead iodide and methylammonium iodide with laser. 3 A photoelectric conversion element is obtained in the same manner as in Example 2, except that a photoelectric conversion layer made of

[0152] Example 7 Photoelectric conversion element 7 is obtained in the same manner as in Example 1, except that in forming the photoelectric conversion layer, die coating is changed to bar coating, and a poor solvent method is used instead of gas quenching.

[0153] Example 8 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the photoelectric conversion layer, the coating method is changed to bar coating.

[0154] Example 9 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the photoelectric conversion layer, the coating method is changed to blade coating.

[0155] Example 10 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the photoelectric conversion layer, the coating method is changed to spray coating.

[0156] Example 11 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the photoelectric conversion layer, the coating method is changed to inkjet coating.

[0157] Example 12 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the electron transport layer, the ITO-coated glass substrate is changed to an ITO-coated film, and in forming the photoelectric conversion layer, the coating method is changed to gravure coating.

[0158] (Example 13) A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the photoelectric conversion layer, the coating method is changed to screen coating.

[0159] Example 14 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the charge transport layer, spin coating is used instead of die coating.

[0160] Example 15 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the charge transport layer, blade coating is used instead of die coating.

[0161] (Example 16) A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the charge transport layer, bar coating is used instead of die coating.

[0162] (Example 17) A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the charge transport layer, spray coating is used instead of die coating.

[0163] (Example 18) A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the charge transport layer, inkjet coating is used instead of die coating.

[0164] (Example 19) A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the electron transport layer, the ITO-coated glass substrate is changed to an ITO-coated film, and in forming the charge transport layer, the film is formed by gravure coating instead of die coating.

[0165] (Example 20) A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the charge transport layer, the film is formed by screen coating instead of bar coating.

[0166] Example 21 A photoelectric conversion element is obtained in the same manner as in Example 9, except that in forming the charge transport layer, bar coating is used instead of die coating.

[0167] Example 22 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the photoelectric conversion layer, drying is performed by the poor solvent method instead of the gas quenching method.

[0168] Example 23 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the photoelectric conversion layer, the gas quenching method is not used and the photoelectric conversion layer is dried by air drying.

[0169] Example 24 A photoelectric conversion element is obtained in the same manner as in Example 8, except that the coating method in forming the charge transport layer is changed to spin coating.

[0170] (Example 25) A photoelectric conversion element is obtained in the same manner as in Example 8, except that in forming the charge transport layer, the coating method is changed to bar coating.

[0171] (Example 26) A photoelectric conversion element is obtained in the same manner as in Example 8, except that in forming the charge transport layer, the coating method is changed to blade coating.

[0172] Example 27 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the charge transport layer, the charge transport layer coating liquid is centrifuged to remove coarse particles, and a coating liquid is used. The color of the obtained film is lighter than that of the other samples.

[0173] (Example 28) A photoelectric conversion element is obtained in the same manner as in Example 1, except that the charge transporting particles 1 are quinacridone particles.

[0174] (Example 29) A photoelectric conversion element is obtained in the same manner as in Example 1, except that the charge transporting particles 1 are changed to tetraphenylporphyrin (TPP).

[0175] (Example 30) A photoelectric conversion element is obtained in the same manner as in Example 1, except that the charge transporting particles 1 are particles having a compound represented by the following formula (Pc-3). [ka]

[0176] (Example 31) 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.).

[0177] Example 32 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.).

[0178] (Example 33) A photoelectric conversion element is obtained in the same manner as in Example 1, except that the second charge transport layer is not formed.

[0179] (Example 34) In forming the photoelectric conversion layer, a photoelectric conversion element is prepared in the same manner as in Example 1, except that instead of the photoelectric conversion layer coating solution 1, the photoelectric conversion layer coating solution 2 prepared by the following method is used. 0.487 g of lead bromide, 1.034 g of formamidium iodide, 2.903 g of lead iodide, 0.139 g of methylammonium bromide, and 0.364 g of methylammonium chloride are dissolved in 4.25 g of N,N-dimethylformamide and 1.216 g of dimethyl sulfoxide and stirred for 1 hour (solution 1). Furthermore, 0.100 g of cesium iodide is dissolved in 0.285 g of dimethyl sulfoxide and stirred for 1 hour (solution 2). Then, the dissolved cesium iodide solution (solution 2) is added to solution 1 to prepare the photoelectric conversion layer coating solution 2.

[0180] Example 35 A photoelectric conversion element is produced in the same manner as in Example 1, except that in forming the second charge transport layer, a second charge transport layer coating solution 2 prepared by dissolving 60 mg of P3HT in 3 mL of chlorobenzene is used instead of the second charge transport layer coating solution 1. The film thickness of the second charge transport layer is 50 nm.

[0181] (Example 36) A photoelectric conversion element is obtained in the same manner as in Example 1, except that the amount of resin solution 1 added in forming the charge transport layer is changed to 0.28 g. The ratio of the volume of the charge transport particles to the volume of the insulating resin in the charge transport layer of the obtained photoelectric conversion element is 5.0.

[0182] (Example 37) A photoelectric conversion element is obtained in the same manner as in Example 1, except that the amount of resin solution 1 added in forming the charge transport layer is changed to 0.05 g. The ratio of the volume of the charge transport particles to the volume of the insulating resin in the charge transport layer of the obtained photoelectric conversion element is 29.5.

[0183] (Example 38) A photoelectric conversion element is obtained in the same manner as in Example 1, except that the amount of resin solution 1 added in the formation of the charge transport layer is changed to 0.40 g. The ratio of the volume of the charge transport particles to the volume of the insulating resin in the charge transport layer of the obtained photoelectric conversion element is 3.5. The maximum value of the photoelectric conversion efficiency of the photoelectric conversion elements having the charge transport layer prepared in Examples 1 to 37 is better than the maximum value of the photoelectric conversion efficiency of the photoelectric conversion element having the charge transport layer prepared in Example 38.

[0184] Comparative Example 1 A photoelectric conversion element was obtained in the same manner as in Example 2, except that in forming the photoelectric conversion layer, spin coating was used instead of die coating.

[0185] Comparative Example 2 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the charge transporting particles 1 are not used in forming the charge transporting layer.

[0186] Comparative Example 3 A photoelectric conversion element is obtained in the same manner as in Example 1, except that no insulating resin is used in forming the charge transport layer.

[0187] Comparative Example 4 A photoelectric conversion element is obtained in the same manner as in Example 1, except that in forming the charge transport layer, P3HT is used as the conductive resin instead of the insulating resin.

[0188] Comparative Example 5 A photoelectric conversion element is obtained in the same manner as in Comparative Example 1, except that in forming the photoelectric conversion layer, drying is performed by a poor solvent method instead of gas quenching.

[0189] Comparative Example 6 A photoelectric conversion element was obtained in the same manner as in Example 1, except that in forming the charge transport layer, a solution in which 0.25 parts of phenethylamine hydroiodide was dissolved in 78.5 parts of 2-propanol was coated instead of the coating liquid for the charge transport layer, and then air-dried. Table 2 shows some of the manufacturing conditions for the photoelectric conversion elements produced in Examples 1 to 38 and Comparative Examples 1 to 6.

[0190] [evaluation] [Analysis of compound amounts] 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 soaked in a solvent, dissolved in heavy water sulfuric acid, and 1H-NMR measurement (apparatus: AVANCE3-500, manufactured by BRUKER) was performed. In addition, the peeled off charge transport layer components were subjected to mass and structure analysis by elemental analysis such as GPC, MALDI-TOF-MS, IR, gas chromatography, XPS, and EDX to confirm the presence of compounds.

[0191] [Checking for voids in the photoelectric conversion layer] The presence or absence of voids in the photoelectric conversion layer was confirmed by the method described above. That is, the photoelectric conversion element was cut and fixed to an inclined sample stage, and then the presence or absence was confirmed by cross-sectional observation using an SEM (equipment: Carl Zeiss, SmartSEM). In the observation, the charge transport layer was distinguished from other layers based on the difference in contrast of the observed image and composition analysis using the SEM-EDX function, and voids were confirmed from images taken at a magnification of 10,000 times. Photographs were taken at 10 random locations, and the total number of voids confirmed was counted. The results are shown in Table 3.

[0192] [Confirmation of the deposition area of ​​the photoelectric conversion layer] The deposition area of ​​the photoelectric conversion layer was confirmed by the above-mentioned method. That is, first, the portion where the photoelectric conversion layer was deposited was visually confirmed. Next, the length of each side of the obtained photoelectric conversion layer was measured using a ruler, and the deposition area was calculated.

[0193] [Measurement of arithmetic mean roughness Ra of photoelectric conversion layer] The arithmetic mean roughness Ra of the photoelectric conversion layer was measured by the following method. For samples with the photoelectric conversion layer formed, an atomic force microscope AFM / SPM (MFP-3D Origin, Oxford Instruments) was used to obtain height images in AM-FM mode, and the arithmetic mean roughness Ra was calculated by image analysis. The measurement conditions were as follows: a cantilever: OMCL-AC-160TS (Olympus), and a range of 90 μm × 90 μm was measured at a scanning frequency of 1 Hz.

[0194] Further, the number of X data was 256, and the number of Y data was 256. In Example 1, it was confirmed that the value measured by the above method after removing the first electrode and the charge transport layer from the photoelectric conversion element was the same as Ra of the sample formed up to the photoelectric conversion layer. The results are shown in Table 3.

[0195] [Measurement of the size of the perovskite crystals in the photoelectric conversion layer] The size of the crystals was measured by the method described above. That is, first, the upper layer of the photoelectric conversion element was peeled off using a solvent that does not destroy the perovskite crystals, exposing the perovskite crystals. Next, the sample with the exposed perovskite crystals was fixed to the stage, and the surface was observed using a SEM (equipment: Carl Zeiss, SmartSEM).

[0196] In the observation, perovskite crystals were distinguished from other layers based on the difference in contrast of the observed image and composition analysis using the SEM-EDX function, and the long diameter of the largest perovskite crystal was measured in an image taken at 10,000x magnification. This was done at three random locations, and the average value of the long diameter of the largest perovskite crystal in each image was taken as the crystal size. The results are shown in Table 3.

[0197] [Measurement of average film thickness] The average film thickness of the photoelectric conversion layer and the charge transport layer was confirmed by the method described above, that is, by cutting the photoelectric conversion element, fixing it to an inclined sample stage, and then observing the cross section using a SEM (equipment: Carl Zeiss, SmartSEM).

[0198] In the observation, the charge transport layer was distinguished from other layers based on the difference in contrast of the observed image and composition analysis using the SEM-EDX function, and the average film thickness of the charge transport layer portion was measured by image processing of the image taken at a magnification of 50,000 times. This was done by taking pictures of five randomly selected points, and the average of the five average values ​​was taken as the average film thickness of the charge transport layer. The results are shown in Table 3.

[0199] [Evaluation of mass production] Regarding mass productivity, as described in the embodiment of the invention, it was determined that mass productivity was not possible when the photoelectric conversion layer was formed by spin coating. The results are shown in Table 2.

[0200] [Evaluation of uniformity] A power source (KEITHLEY, Model 236) was connected between the electrodes of each of the photoelectric conversion elements with and without a charge transport layer, which were prepared in the examples and comparative examples, and an intensity of 114 mW / cm was applied. 2 The photoelectric conversion efficiency was measured by irradiating a certain amount of light using a solar simulator (manufactured by Yamashita Denso Co., Ltd.) and measuring the generated current and voltage. Measurements were performed on each of the 10 electrodes for all 25 mm square samples of each photoelectric conversion element.

[0201] The difference between the highest and lowest photoelectric conversion efficiencies was calculated for the sample with a charge transport layer and the photoelectric conversion element without a charge transport layer, and ΔPCE 1 , ΔP 0 When the area in which the photoelectric conversion layer is formed is large and multiple 25 mm square photoelectric conversion elements are cut out in the formation of the first electrode, the highest photoelectric conversion efficiency and the lowest photoelectric conversion efficiency among the multiple photoelectric conversion elements are used to calculate ΔPCE 1 and ΔPCE 0 For example, the photoelectric conversion element produced in Example 1 had three samples with a charge transport layer formed thereon, so the difference between the highest and lowest photoelectric conversion efficiencies measured at a total of 30 electrodes was calculated as ΔPCE 1Similarly, there were three samples in which the charge transport layer was not formed, so the difference between the highest and lowest photoelectric conversion efficiencies measured at a total of 30 electrodes was taken as ΔPCE 0 The obtained ΔPCE 1 and ΔPCE 0 The difference between ΔΔPCE and ΔPCE is 0 -ΔP.C.E. 1 The results are shown in Table 3.

[0202] If ΔΔPCE was 2% or more, it was determined that the effect of the present invention was realized (there was uniformity in the photoelectric conversion efficiency). However, for Comparative Example 2, the photoelectric conversion efficiency of the sample having the charge transport layer formed thereon was very low, and the performance as a photoelectric conversion element was not exhibited. Therefore, it was determined that the sample did not function as a photoelectric conversion element, and ΔΔPCE was not calculated.

[0203] [Table 2] [Table 3]

[0204] The disclosure of this embodiment includes the following method. (Method 1) A step (A) of forming a photoelectric conversion layer including a crystal having a perovskite structure by using a large-area film formation method; A step (B) of applying a coating material for a charge transport layer onto the surface of the photoelectric conversion layer and then drying the coating material to form a charge transport layer; A method for producing a photoelectric conversion element, comprising: The method for producing a photoelectric conversion element is characterized in that the paint for the charge transport layer contains charge transport particles and an insulating resin. (Method 2) In the step (A), the deposition area of ​​the photoelectric conversion layer is 20 cm 2 The method for producing a photoelectric conversion element according to Method 1 is as described above. (Method 3) The method for producing a photoelectric conversion element according to Method 1 or 2, wherein the photoelectric conversion layer has voids. (Method 4) The method for producing a photoelectric conversion element according to any one of Methods 1 to 3, wherein the arithmetic mean roughness of the surface of the photoelectric conversion layer is 40 nm or more. (Method 5) 5. The method for producing a photoelectric conversion element according to any one of Methods 1 to 4, wherein the crystal size is 1.0 μm or more. (Method 6) The method for producing a photoelectric conversion element according to any one of Methods 1 to 5, wherein the step (A) includes a step (A-1) of uniformly applying a paint for a photoelectric conversion layer, and a step (A-2) of drying the paint for the photoelectric conversion layer. (Method 7) The method for producing a photoelectric conversion element according to Method 6, wherein the step (A-1) includes a coating step using any one of coating methods selected from the group consisting of die coating, blade coating, roll coating, spray coating, inkjet coating, gravure coating, and screen coating. (Method 8) The method for producing a photoelectric conversion element according to Method 6 or 7, wherein the step (A-2) does not include a step of applying a poor solvent to the raw material of the crystals. (Method 9) The method for producing a photoelectric conversion element according to any one of Methods 6 to 8, wherein the step (A-2) includes a step of drying the paint for the photoelectric conversion layer by spraying gas using a gas spraying means. (Method 10) 10. The method for producing a photoelectric conversion element according to any one of Methods 6 to 9, wherein the step (B) has the same coating method as the step (A-1). (Method 11) The method for producing a photoelectric conversion element according to any one of Methods 1 to 10, wherein the step (B) includes a coating step using any one coating method selected from the group consisting of die coating, blade coating, roll coating, spray coating, inkjet coating, gravure coating, and screen coating. (Method 12) 12. The method for producing a photoelectric conversion element according to any one of Methods 1 to 11, wherein the charge transport layer has an average thickness of 50 nm or more. (Method 13) 13. The method for producing a photoelectric conversion element according to any one of Methods 1 to 12, wherein the charge transporting particles contain a cyclic conjugated compound in which a plurality of pyrrole rings are conjugated. (Method 14) 14. The method for producing a photoelectric conversion element according to any one of Methods 1 to 13, wherein the charge transporting particles contain a phthalocyanine compound. (Method 15) 15. The method for producing a photoelectric conversion element according to any one of Methods 1 to 14, wherein the charge transporting particles contain a hydroxygallium phthalocyanine compound. (Method 16) 16. The method for producing a photoelectric conversion element according to any one of Methods 1 to 15, wherein the insulating resin has a glass transition point of lower than 100°C. (Method 17) 17. The method for producing a photoelectric conversion element according to any one of Methods 1 to 16, wherein the insulating resin is a polyvinyl acetal resin or a polyvinyl butyral resin. (Method 18) 18. The method for producing a photoelectric conversion element according to any one of Methods 1 to 17, wherein the photoelectric conversion element has a second charge transport layer not containing charge transport particles on the charge transport layer. (Method 19) 19. The method for producing a photoelectric conversion element according to any one of Methods 1 to 18, wherein in the charge transport layer, a ratio of the volume of the charge transport particles to the volume of the insulating resin is 5 or more and 30 or less. [Explanation of symbols]

[0205] 1 Photoelectric conversion element 2. Board 3 Second electrode 4 Electron transport layer 5 Photoelectric conversion layer 6 Charge transport layer 7 First electrode 11 Perovskite crystals 12 Charge transporting particles 13 Insulating resin 30 Mobile 31, 41 Photoelectric conversion element 32 Aircraft 40 Building materials 42 Protective materials 43 Heat dissipation materials 44a, 44b Exterior

Claims

1. A step (A) of forming a photoelectric conversion layer including a crystal having a perovskite structure by using a large-area film formation method; A step (B) of applying a coating material for a charge transport layer onto the surface of the photoelectric conversion layer and then drying the coating material to form a charge transport layer; A method for producing a photoelectric conversion element, comprising: The method for producing a photoelectric conversion element is characterized in that the paint for the charge transport layer contains charge transport particles and an insulating resin.

2. In the step (A), the deposition area of ​​the photoelectric conversion layer is 20 cm ２ The method for producing a photoelectric conversion element according to claim 1 .

3. The method for producing a photoelectric conversion element according to claim 1 , wherein the photoelectric conversion layer has voids.

4. The method for producing a photoelectric conversion element according to claim 1 , wherein the arithmetic mean roughness of the surface of the photoelectric conversion layer is 40 nm or more.

5. The method for producing a photoelectric conversion element according to claim 1 , wherein the crystal size is 1.0 μm or more.

6. The method for producing a photoelectric conversion element according to claim 1, wherein the step (A) includes a step (A-1) of uniformly applying a paint for a photoelectric conversion layer, and a step (A-2) of drying the paint for the photoelectric conversion layer.

7. The method for producing a photoelectric conversion element according to claim 6, wherein the step (A-1) includes a coating step using any one coating method selected from the group consisting of die coating, blade coating, roll coating, spray coating, inkjet coating, gravure coating, and screen coating.

8. The method for producing a photoelectric conversion element according to claim 6, wherein the step (A-2) does not include a step of applying a poor solvent to the raw material of the crystals.

9. 7. The method for producing a photoelectric conversion element according to claim 6, wherein the step (A-2) includes a step of drying the paint for the photoelectric conversion layer by spraying a gas using a gas spraying means.

10. The method for producing a photoelectric conversion element according to claim 6, wherein the step (B) has the same coating method as the step (A-1).

11. 2. The method for producing a photoelectric conversion element according to claim 1, wherein the step (B) includes a coating step using any one coating method selected from the group consisting of die coating, blade coating, roll coating, spray coating, inkjet coating, gravure coating, and screen coating.

12. The method for producing a photoelectric conversion element according to claim 1 , wherein the charge transport layer has an average thickness of 50 nm or more.

13. The method for producing a photoelectric conversion element according to claim 1 , wherein the charge transporting particles contain a cyclic conjugated compound in which a plurality of pyrrole rings are conjugated.

14. The method for producing a photoelectric conversion element according to claim 1 , wherein the charge transporting particles contain a phthalocyanine compound.

15. The method for producing a photoelectric conversion element according to claim 1 , wherein the charge transporting particles contain a hydroxygallium phthalocyanine compound.

16. The method for producing a photoelectric conversion element according to claim 1 , wherein the insulating resin has a glass transition point of less than 100° C.

17. The method for producing a photoelectric conversion element according to claim 1 , wherein the insulating resin is a polyvinyl acetal resin or a polyvinyl butyral resin.

18. The method for producing a photoelectric conversion element according to claim 1 , wherein the photoelectric conversion element has a second charge transport layer not containing charge transport particles on the charge transport layer.

19. 2 . The method for producing a photoelectric conversion element according to claim 1 , wherein in the charge transport layer, a ratio of a volume of the charge transport particles to a volume of the insulating resin is 5 or more and 30 or less.

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