Method for manufacturing photoelectric conversion element

Abstract

The present invention addresses the problem of providing a photoelectric conversion element which achieves both mass productivity and uniformity in photoelectric conversion efficiency. In order to solve the problem, the present invention provides a method for manufacturing a photoelectric conversion element, the method including: a step (A) in which a photoelectric conversion layer that includes a crystal having a perovskite structure is formed using a large-area film formation method; and a step (B) in which a charge transport layer is formed by applying a coating material for a charge transport layer onto the surface of the photoelectric conversion layer and subsequently drying the coating material. This method for manufacturing a photoelectric conversion element is characterized in that the coating material for a charge transport layer contains charge transport particles and an insulating resin.

Description

Photoelectric conversion element manufacturing method

[0001] The present invention relates to a method for manufacturing a photoelectric conversion element.

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

[0003] Currently, n-p diode-type silicon (Si) single crystal-based solar cells with a light energy conversion efficiency of over 20% are widely known and are actually used for solar power generation. However, these require high-temperature processing steps and the materials themselves are expensive, resulting in high costs per unit of power. Furthermore, there are also supply issues due to the limited silicon resources.

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

[0005] Various manufacturing methods have been proposed for forming films of these perovskite crystals. While spin coating is often used in research-level studies, in studies aimed at mass production, die coating and blade coating, which are suitable for mass production, are often used, 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 roll-to-roll methods.

[0006] On the other hand, perovskite crystals are difficult to manufacture, and so various defects of various sizes occur, including molecular-level defects and defects in the coating film. These defects reduce the ability to transport carriers to the layers above and below, which reduces photoelectric conversion efficiency and accelerates the deterioration of perovskite solar cells over long periods of use. Therefore, research into suppressing defects and improving carrier transport capacity is being actively conducted.

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

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

[0009] JP 2023-148126 A U.S. Patent Application Publication No. 2021 / 057591 JP 2018-170382 A

[0010] Q. Hu, et al. Sol. RRL,2019,3,1800264

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

[0012] The above object is achieved by the present invention, which is a method for producing a photoelectric conversion element, comprising: step (A) of forming a photoelectric conversion layer containing crystals of a perovskite structure by using a large-area film formation method; and step (B) of applying a paint for a charge transport layer onto the surface of the photoelectric conversion layer and then drying the paint to form a charge transport layer, wherein the paint for the charge transport layer contains charge transport particles and an insulating resin.

[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 of photoelectric conversion efficiency.

[0014] Fig. 1 is a schematic diagram of a layer structure in the thickness direction of a first embodiment of a photoelectric conversion element of the present invention. Fig. 2 is a perspective view schematically showing an embodiment of a moving body including a photoelectric conversion element of the present invention. Fig. 3 is a perspective view schematically showing an embodiment of a building material including a photoelectric conversion element of the present invention. Fig. 4 is a schematic cross-sectional view of an embodiment of a photoelectric conversion element of the present invention.

[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 manufacturing a photoelectric conversion element of the present invention includes: a step (A) of forming a photoelectric conversion layer containing crystals with a perovskite structure using a large-area film formation method; and a step (B) of applying a paint for a charge transport layer onto the surface of the photoelectric conversion layer and then drying the paint to form a charge transport layer, wherein the paint for the charge transport layer contains 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 process, a photoelectric conversion element that is both mass-producible and has uniform photoelectric conversion efficiency can be obtained. The reasons for this are considered to be as follows.

[0017] 4 is a cross-sectional schematic diagram of one embodiment of the photoelectric conversion element of the present invention. The photoelectric conversion element 1 has, on a substrate 2, 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. One of the first electrode 7 and the second electrode 3 is an anode and the other is a cathode, and current can be extracted by connecting the first electrode 7 and the second electrode 3 to an external circuit.

[0018] First, mass productivity can be improved by forming the photoelectric conversion layer 11 using a large-area film formation method. Using a large-area film formation method makes it possible to fabricate many photoelectric conversion elements 1 in a limited time, thereby reducing manufacturing costs. In addition, connectivity with previous and subsequent processes in the manufacturing line is improved, making it possible to apply the method to a roll-to-roll system. Unlike the formation of other layers, the formation of the photoelectric conversion layer 11 requires the appropriate fabrication of perovskite crystals, making it more 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 irregularities on the crystal surface and gaps between crystal grains. If defects such as these irregularities 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 irregularities and gaps with respect to the flow of charge will also 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.Furthermore, if a high-resistance charge transport layer is formed on the surface of a photoelectric conversion layer made of perovskite crystals, the exchange of charges is hindered, 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 using 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 thought that the charge transport efficiency from the perovskite crystal to the first electrode 7 is maintained because the charge transport material is present as particles on the perovskite crystal, and the insulating resin 13 does not hinder charge transport.

[0023] Furthermore, as a result of intensive research by the present inventors, it has been found that the larger the area of ​​the film formation method used, the more likely the unevenness and gaps in the photoelectric conversion layer are to occur, and that the effect of improving the uniformity of the conversion efficiency of the photoelectric conversion element by forming the charge transport layer described above is even greater. The following reasons, for example, are thought to be the reasons why the large-area film formation method makes the photoelectric conversion layer more likely to have unevenness.

[0024] First, forming a photoelectric conversion layer over a large area is one example. When a photoelectric conversion layer is formed over a large area, the probability of unevenness or gaps occurring increases with the increase in area. Generally, if a defect exists anywhere in the photoelectric conversion layer of a photoelectric conversion element, carrier recombination and sample degradation will occur from that point onward, resulting in a decrease in photoelectric conversion efficiency and durability greater than the area of ​​the defect.

[0025] Another factor is the method used to form the photoelectric conversion layer. In research-level experiments, the photoelectric conversion layer is often formed by combining a method in which a uniform wet film is formed by rotating the substrate (hereinafter referred to as the "spin coating method") with a method in which a poor solvent is applied to the wet film to grow perovskite crystals (hereinafter referred to as the "poor solvent method").

[0026] When considering mass production, the process of applying a poor solvent poses environmental challenges and cost issues due to the need for a separate process to remove the solvent. Therefore, methods that promote the growth of perovskite crystals by spraying gas or reducing pressure are often used. These methods slow the rate at which crystallization progresses compared to the poor solvent method, in which the good solvent in the material is instantly replaced. This results in differences in the size of the resulting crystals, making it more likely that unevenness will occur in the photoelectric conversion layer. As explained above, the synergistic effects of each component make 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 those 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 with clear boundaries or a flat, thin-film layer, but also to a layer with a gradually changing concentration gradient of contained elements, or to a layer that can form a complex, intricate structure together with other layers. Elemental analysis of a layer can be performed, for example, by performing TOF-SIMS / FE-TEM / EDS line analysis of a cross section of a photoelectric conversion element to confirm the element distribution of a specific element. Analysis of each layer may be performed by peeling and removing the completed photoelectric conversion element to expose the layer to be analyzed. In the present invention, the volume ratio is quantified by using the area ratio of the exposed surface or cross section as the volume ratio of that layer.

[0029] 1 is a cross-sectional view schematically illustrating the 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 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 through the first electrode 7 and the charge transport layer 6, and generates electrons or holes. That is, the photoelectric conversion layer 5 generates a current between the first electrode 7 and the second electrode 3. The electron transport layer 4 is a layer disposed between the photoelectric conversion layer 5 and two electrodes (the second electrode 3 and the first electrode 7), and may not be formed in some cases. A structure in which multiple electron transport layers 4 and photoelectric conversion layers 5 are stacked may be used. Such a structure may also be called a tandem structure. Each component will be described below. Alternatively, a photoelectric conversion element may be fabricated on the substrate 2 in the following order: the first electrode 7, the charge transport layer 6, the photoelectric conversion layer 5, the electron transport layer 4, and the second electrode 3.

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

[0032] Vapor deposition is a method of forming a film by volatilizing a solid raw material and then re-solidifying it 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, step (A) preferably includes step (A-1) of uniformly coating a coating material for the photoelectric conversion layer, and 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] Photovoltaic conversion layers require not only conventional film-forming techniques but also the production of perovskite crystals in the desired state, making them difficult to produce in large areas. The spin-coating method, by its very nature, requires the substrate or film to be rotated at high speed, which poses safety and uniformity challenges when producing large areas. Furthermore, spin-coating requires batch-type manufacturing, which poses challenges when connecting with previous and subsequent processes on the production line, making it unsuitable as a method for producing large-area photovoltaic 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. Furthermore, step (A-1) may be used alone or in combination with other coating methods. Among these, in the method for producing a photoelectric conversion element of the present invention, from the viewpoint of being able to further increase mass productivity, step (A-1) preferably 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, and more preferably 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 surface of a substrate. Inkjet coating is a method of forming a uniform coating film by dripping paint drop by drop onto the surface of a substrate.

[0038] Screen coating is a coating method that uses a stencil with 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. Roll coating has a wide range of applications, including methods that control the amount of paint that gets on the roller beforehand using die coating or blade coating, and then apply it to the substrate; methods that use rollers to control the gap of the paint that passes through them to make the coating film uniform; and methods such as the roll-to-roll method, which uses a roll to apply a uniform coating surface to a deformable film such as a film.

[0039] Gravure coating is a method of applying paint by attaching it to a gravure roll with an uneven surface and then transferring it to a substrate. Die coating is a method of forming a coating film by extruding the paint at a uniform flow rate across the width through a wide slit 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 dropping paint onto a substrate and passing it between the substrate and a blade. Curtain coating is a method of forming a coating film by extruding paint at a uniform flow rate in the width direction from a wide slit, transferring the paint directly onto the substrate without forming puddles. Bar coating is a method of forming a uniform coating film by dropping paint onto a substrate and passing it between bars with grooves at the end of the bar.

[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 rate is preferable because slow drying can cause the wet film to move during drying, leading to unevenness in the film, and too few perovskite crystal nuclei can easily form spaces 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 between 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 migration of raw material ions of the perovskite crystals across the interfaces. Therefore, it is preferable that the drying rate in step (A-2) be within an appropriate range.

[0044] Examples of step (A-2) include a poor solvent method, a gas quenching method, a reduced pressure method, a rapid heating method, and air drying. 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 coating material for the photoelectric conversion layer, thereby generating perovskite crystals. Because the good solvent is instantly replaced, many nuclei of perovskite crystals are generated.

[0045] Therefore, defects in the film are less likely to occur, roughness tends to be smaller, and individual crystals tend to be smaller. The gas quenching method is a method of producing perovskite crystals by spraying gas onto the wet film to promote drying. Because moisture promotes the decomposition of perovskite crystals, it is preferable that the gas sprayed be low in moisture content.

[0046] Examples of the gas to be blown include nitrogen gas and dry air. Hot air may be blown by preheating the gas. The decompression method is a method in which the space in which the wet film exists is decompressed to promote the evaporation of the solvent in the wet film, thereby drying the wet film.

[0047] Rapid heating is a method of accelerating drying by heating a wet film. Heating can be performed by directly heating the substrate with a heat source or indirectly by using infrared rays or the like.

[0048] Among these, in the method for producing a photoelectric conversion element of the present invention, it is preferable that step (A-2) does not include a step of applying a poor solvent to the raw material of the crystals of the perovskite structure (does not include a poor solvent method). Because 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 from the viewpoint of the cost of adding a step of removing the poor solvent.

[0049] In the case of a method that does not use a poor solvent method, the rate of nucleation of perovskite crystals is slower than in the case of a poor solvent method, so defects in the film are relatively more likely to occur, roughness is more likely to increase, and individual crystals are more likely to become large. In the method for producing a photoelectric conversion element of the present invention, 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 a gas quenching method). The gas quenching method is cost-effective because the equipment can be assembled relatively easily, and can dry the wet film at the desired speed.

[0050] In the method for producing a photoelectric conversion element of the present invention, in step (A), the film formation area of ​​the photoelectric conversion layer is 5 cm ２ It is preferable that the length is 20 cm or more. ２ More preferably, the above is the case. By doing so, mass productivity can be improved and the recombination suppression effect of the insulating resin can be enhanced. The larger the film formation area of ​​the photoelectric conversion layer, the better the mass productivity. Furthermore, the larger the film formation area, the more likely it is that unevenness 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 materials of the perovskite crystal at once, or by depositing the raw materials in multiple batches. When depositing the raw materials in multiple batches, the effect of the present invention can be achieved by including step (A) in at least one of the batches.

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

[0053] [Step of Forming Charge Transport Layer (Step B)] The method for producing a photoelectric conversion element of the present invention includes step (B) of applying a coating material for the charge transport layer onto the surface of the photoelectric conversion layer and then drying the coating material to form a charge transport layer. In step (B), methods 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, etc.

[0054] Unlike the formation of the photoelectric conversion layer, the charge transport layer is less difficult to form since no perovskite crystals are formed, and so spin coating can also be used. Among these, in the method for producing a photoelectric conversion element of the present invention, from the viewpoint of enabling higher mass productivity, it is preferable that 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, and it is more preferable that it includes a coating step using 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 paint 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 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 in which an insulating resin has been dissolved, a method of applying a resin solution in which an insulating resin has been dissolved on the surface of the photoelectric conversion layer and then disposing charge transport particles, or a method of applying a resin solution in which an insulating resin has been dissolved and a solution in which charge transport particles have been dispersed on the surface of the photoelectric conversion layer may be used.

[0059] [Charge Transport Particles] In the method for producing a photoelectric conversion element of the present invention, the coating material 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 preferably nm or less.

[0060] Within the above range, the penetration of the charge transport particles between the perovskite crystal grains can be suppressed, and the uniformity of the film can be maintained, thereby suppressing loss of charge transport properties. The particle size of the charge transport particles contained in the charge transport layer can be determined as a volume average particle size from a 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 particles with a small aspect ratio, such as an approximately spherical shape, a rugby ball shape, a cylindrical shape, a flat shape, etc. For example, particles with a large aspect ratio, such as needle-shaped particles, must be deposited in the same direction to improve coverage.

[0062] That is, even if the charge-transport particles can be deposited on the photoelectric conversion layer in a stable dispersed state without excessive aggregation, their shape tends to leave portions of the photoelectric conversion layer that are not covered with the charge-transport particles.Furthermore, since the particles tend to pile up on other particles, voids tend to remain between the photoelectric conversion layer and the layer of charge-transport particles, thereby reducing the effect of the present invention.

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

[0064] The shape and aspect ratio of the charge transporting 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 transport particles preferably contain a cyclic conjugated compound formed by covalently bonding a plurality of pyrrole rings. By molding the cyclic conjugated compound formed by covalently bonding a plurality of pyrrole rings into charge transport particles, the charge transport particles exhibit high charge transport 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 even more preferably contain a hydroxygallium phthalocyanine compound. The charge-transporting particles can more efficiently transport charges generated in the photoelectric conversion layer.

[0068] (M in the above formula (Pc-2) is H ２ , a metal atom having a ligand, or a metal atom having no ligand.

[0069] The structure of the chemical substance of the charge transport particle of the present invention can be confirmed by nuclear magnetic resonance (NMR). ２When this is the case, the above formula (Pc-2) is expressed by the following formula (Pc-1):

[0070]

[0071] [Insulating Resin] In the method for producing a photoelectric conversion element of the present invention, the coating material for the charge transport layer contains an insulating resin. Specific examples of insulating resins include polyacetal resin, acrylic resin, polyarylate resin, polycarbonate resin, polyvinyl acetate resin, polyester resin, polyamide resin, polyurethane resin, and polystyrene resin. In the method for producing a photoelectric conversion element of the present invention, among these, the insulating resin is preferably polyvinyl acetal resin or polyvinyl butyral resin. This insulating resin is likely to come into close contact with the charge transport material (charge transport particles), allowing for the formation of a more effective charge distribution.

[0072] In the method for producing a photoelectric conversion element of the present invention, the glass transition temperature of the insulating resin is preferably less than 100°C, and more preferably 95°C or lower. Within this range, the insulating resin is easily in close contact with the charge transport material (charge transport particles), allowing for the formation of a more effective charge distribution. The glass transition temperature can be determined by a differential scanning calorimeter (DSC).

[0073] In the present invention, the molecular weight of the insulating resin is preferably 10,000 or more. In the present invention, the charge transport layer preferably contains an aromatic ring compound having a hydroxy group that is different from the charge transport material (charge transport particles) and the insulating resin. The presence of the aromatic ring compound having a hydroxy group makes it easier for the charge transport material (charge transport particles) and the insulating resin to come into contact with each other, thereby forming a more effective charge distribution.

[0074] In the method for producing a photoelectric conversion element of the present invention, the photoelectric conversion element may have a second charge transport layer, which 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.

[0075] Each layer will be described below. [Photoelectric conversion element] The photoelectric conversion element of the present invention is characterized by comprising a photoelectric conversion layer containing crystals with 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 crystals with 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.

[0076] Furthermore, 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 perovskite solar cells that use perovskite crystals in the photoelectric conversion layer, silicon solar cells, CIGS solar cells, or the like.

[0077] The methods for forming the photoelectric conversion layer and each layer including the charge transport layer of the photoelectric conversion element of the present invention include coating methods and vapor deposition methods. Examples of coating methods include dip coating, spin coating, spray coating, inkjet coating, meniscus coating, screen coating, roll coating, die coating, blade coating, curtain coating, and wire bar coating. A desired method can be selected from these film formation methods depending on each layer.

[0078] Each layer will be described below. [Substrate] The photoelectric conversion element 1 of the present invention may include a substrate 2, for example, 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.

[0079] [Electrodes] The photoelectric conversion element of the present invention has a first electrode and a second electrode. The materials for 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, and Al / Al ２ O３ Examples of suitable materials include a mixture of Al and LiF, and an Al / LiF mixture.

[0080] Transparent electrode materials include, for example, CuI, ITO (indium tin oxide), and SnO ２ Examples of the conductive transparent material include AZO (aluminum zinc oxide), IZO (indium zinc oxide), GZO (gallium zinc oxide), FTO (fluorine-doped tin oxide), and ATO (antimony-doped tin oxide), as well as conductive transparent polymers. These materials may be used alone or in combination of two or more.

[0081] At least one of the first electrode 7 and the second electrode 3 on the light incident side is a transparent electrode, and the other may be a transparent electrode or may double as a reflective layer made of a light-reflective material, or may be a transparent electrode with a reflective layer on the side opposite to the light incident side. When the first electrode 7 is on the light incident side, the second electrode 3 may be a transparent electrode and the substrate 2 may be a reflective layer. The electrodes may be patterned electrodes.

[0082] [Step of forming a first electrode and step of forming a second electrode] The method for manufacturing a photoelectric conversion element of the present invention includes a step of forming a first electrode and a step of forming a second electrode. For the step of forming the first electrode and the step of forming the second electrode, an appropriate method can be selected depending on the material of the first electrode and the material of the second electrode, respectively. Examples of such methods include, but are not limited to, sputtering, vacuum deposition, CVD (chemical vapor deposition), and SPD (spray pyrolysis deposition). The materials for 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.

[0083] When manufacturing solar cells, cutting is generally performed between each process to form circuits. Examples of cutting processes include mechanical patterning and laser patterning.

[0084] [Photoelectric Conversion Layer] The photoelectric conversion element of the present invention has a photoelectric conversion layer containing 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]

[0085] In the 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. ｐ N ｍ H ｎ (where p, m, and n are all positive integers) Specific examples include methylammonium and formamidium.

[0086] 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.

[0087] If the constituent cation A is too large to fit within the three-dimensional perovskite crystal, it will form a two-dimensional perovskite crystal, a 2.5-dimensional perovskite crystal having properties of both two and three dimensions, a bilayer crystal of three-dimensional and two-dimensional perovskite structures, or a mixed three-dimensional and two-dimensional perovskite crystal, all of which will function as a photoelectric conversion layer.

[0088] A two-layer crystal of three-dimensional and two-dimensional perovskite refers to a crystal in which crystals with three-dimensional and two-dimensional perovskite structures are stacked as independent, separate layers, while a mixed three-dimensional / two-dimensional perovskite refers to a crystal with a structure in which both regions or domains of two-dimensional or 2.5-dimensional layered and three-dimensional perovskite structure crystals are mixed.

[0089] The crystal of the two-dimensional perovskite or 2.5-dimensional perovskite structure is preferably represented by the following general formulas [2] to [4], where n is a positive integer: R' ２ A ｎ－１ B ｎ X３ｎ＋１ [2] R''A ｎ－１ B ｎ X ３ｎ＋１ [3] R'''A ｎ B ｎ X ３ｎ＋１ [4]

[0090] 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.

[0091] R', R'', and R''' in the above general formulas [2] to [4] are organic molecules or metal cations which may have a substituent, and specific examples thereof include ethylammonium, propylammonium, n-butylammonium, n-hexylammonium, n-octylammonium, 1,6-hexadiammonium, isobutylammonium, 3-(nonafluoro-tert-butyloxy)propylamine, 1,3-propanediammonium, 1,5-pentamethylenediamine, octyldiammonium, 2,2-(ethylenedioxy)bis(ethylammonium), 5-aminovaleric acid, 4-tert-butylammonium, N,N'-dimethylethylene-1,2-diammonium, 2,2,3,3,3-pentafluoropropylammonium, guanidium, propylammonium, propargylamine, alkylammonium, cyclohexylmethylammonium, 4-(aminomethyl)piperidinium, piperidinium, pyrrolidinium, 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.

[0092] 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.

[0093] X in the above general formulas [1] to [4] is a halogen atom, such as chlorine, bromine, or iodine. These halogen atoms may be used alone or in combination of two or more. Among these, halogen atoms are preferred because the inclusion of halogen in the structure makes the perovskite structure crystal more soluble in organic solvents, enabling application to inexpensive printing methods, etc. Furthermore, iodine is more preferred because it narrows the energy band gap of the perovskite structure crystal.

[0094] Specifically, 3D perovskite, 2D perovskite, and mixed 3D / 2D perovskite are MAPbI ３ and FAPbCl ３ , FAPbI ３ , MAPbI ｘ Br ３－ｘ , MAPbI ｘ Cl ３－ｘ , Cs ０．０５ (MA ０．１７ FA ０．８３ ) ０．９５ Pb(I ０．８３ Br ０．１７ ) ３ , {Cs ｘ１ (FA ｘ２ MA １－ｘ２ ) １－ｘ１} ｘ３ Pb(I ｘ４ Br １－ｘ４ ) ｘ５ , Cs ０．０５ FA ０．８８ MA ０．０７ PbI ２．５６ Br ０．４４ , (FAPbI ３ ) ０．９５ (MAPbBr３ ) 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 PEA ０．１ ) ２ MA ４ Pb ５ I １６ 、(BA ０．９ PEA 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 I １３ 、CsSnBr ３ 、CsSnI３ , 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.

[0095] Depending on the purpose, the A site, B site, or X site in the above general formula may be adjusted to be insufficient or excessive, and the combination of x1 to x5 may be changed depending on the purpose. Combinations of x1 to x5 are, for example, as shown in Table 1. Particularly preferred ranges are 0.03≦x1≦0.10, 0.80≦x2≦0.96, 0.95≦x3≦1.05, 0.80≦x4≦0.96, and 2.95≦x5≦3.05. MACl may also be included as a material for forming perovskite crystals.

[0096]

[0097] In the above specific examples, "MA" represents methylammonium, "FA" represents formamidinium, "PEA" represents phenethylammonium, "PTA" represents phenyltriethylammonium, "ThMA" represents 2-thiophenemethylammonium, "3BBA" represents 3-bromobenzylammonium, "3AMPY" represents 3-(aminomethyl)pyridine, "PDMA" represents 1,4-phenylenedimethaneammonium, "TTDMA" represents thieno[3,2-b]thiophene-2.5-diyldimethaneammonium, "4FPEA" represents 4-fluorophenethylammonium, "BA" represents butylammonium, and "TEA" represents 2-thiophenethylammonium.

[0098] The perovskite crystal preferably has a cubic structure in which a metal atom B is located at the body center, an organic molecule A at each vertex, and a halogen atom X at the face center. Although the details are not clear, it is presumed that such a structure allows the orientation of the octahedra in the crystal lattice to be easily changed, thereby increasing the mobility of electrons in the perovskite crystal and improving the photoelectric conversion efficiency of the photoelectric conversion element.

[0099] The organic-inorganic perovskite compound used in the present invention is preferably a crystalline semiconductor. A crystalline semiconductor refers to a semiconductor from which a scattering peak can be detected by measuring an X-ray scattering intensity distribution. When the organic-inorganic perovskite compound is a crystalline semiconductor, the mobility of electrons in the organic-inorganic perovskite compound increases, improving the photoelectric conversion efficiency of the photoelectric conversion element.

[0100] Furthermore, the photoelectric conversion layer according to the present invention may contain a material other than the organic-inorganic perovskite structure crystal, as long as the material does not impair the photoelectric conversion efficiency or charge transport property. The thickness of the photoelectric conversion layer according to the present invention is preferably 5 nm or more and 2000 nm or less. A thickness of 5 nm or more allows sufficient absorption of light, and a thickness of 2000 nm or less allows the generated charges to be transported to each electrode. A more preferred lower limit is 50 nm or more, a more preferred upper limit is 1200 nm, an even more preferred lower limit is 100 nm, and an even more preferred upper limit is 1000 nm.

[0101] 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 reasons described above. Furthermore, if the photoelectric conversion layer has voids, the charge transport particles may easily penetrate to the second electrode side of the photoelectric conversion layer, which may reduce the recombination suppression effect.

[0102] 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 crystal size 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 irregular shape, and the arithmetic mean roughness is greater. 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.

[0103] Furthermore, if the arithmetic mean roughness Ra is greater than 200 nm, the charge transport particles may easily penetrate into the second electrode side of the photoelectric conversion layer, which may reduce the recombination suppression effect. 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, and the arithmetic mean roughness tends to become large, for the reasons described above.

[0104] [Charge Transport Layer] In the photoelectric conversion element of the present invention, a charge transport layer is disposed between the photoelectric conversion layer and the 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.

[0105] 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 or more and 30 or less. The ratio of the volume of the charge transport particles to the volume of the insulating resin can be determined, for example, by observing the 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 10８ It is Ω·cm or more.

[0106] 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 improvement in conversion efficiency can be expected when the photoelectric conversion layer is produced by a large-area film formation method. Furthermore, by reducing the film thickness of the charge transport layer, it is possible to suppress a decrease in current and power generation due to the charge transport layer acting as a resistor.

[0107] The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing the above-mentioned materials and solvent, forming this coating film on the photoelectric conversion layer, and drying it. Examples of solvents used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, alcohol-based solvents and aromatic hydrocarbon-based solvents are preferred.

[0108] [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 7.

[0109] 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 at the film interface, those having an aromatic ring are preferred, and Spiro-OMeTAD, PTAA, and phthalocyanine compounds are preferred.

[0110] The second charge transport layer may contain a dopant as an additive to improve its charge transport capability. Examples of a substance that can be used as a dopant include lithium compounds such as bis(trifluoromethanesulfonyl)imide lithium, cobalt compounds such as [tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(3)tris(bis(trifluoromethylsulfonyl)imide)], boron compounds such as tetrakis(pentafluorophenyl)borate, molybdenum compounds such as tris[1-(methoxycarbonyl)-2-(trifluoromethyl)-ethane-1,2-dithiolene]molybdenum, organic compounds having a tetracyanoquinodimethane skeleton such as 2,3,4,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, and organic compounds having a pyridine skeleton such as 4-tert-butylpyridine.

[0111] [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 .

[0112] The material for the electron transport layer 4 is not particularly limited, and examples thereof include N-type conductive polymers, N-type low-molecular-weight organic semiconductors, N-type metal oxides, N-type metal sulfides, alkali metal halides, alkali metals, surfactants, etc. Specific examples thereof include cyano group-containing polyphenylene vinylene, boron-containing polymers, bathocuproine, bathophenanthrene, hydroxyquinolinatoaluminum, oxadiazole compounds, benzimidazole compounds, naphthalene tetracarboxylic acid compounds, fullerene compounds, perylene derivatives, phosphine oxide compounds, phosphine sulfide compounds, fluoro group-containing phthalocyanines, titanium oxide, zinc oxide, indium oxide, tin oxide, gallium oxide, tin sulfide, indium sulfide, zinc sulfide, etc. In particular, tin oxide may be obtained by reacting tin(2) chloride, tin(4) chloride, tin(2) chloride dihydrate, or tin(4) chloride pentahydrate.

[0113] The thickness of the electron transport layer 4 is preferably 1 nm or more in lower limit and 2000 nm or more in upper limit. When the thickness of the electron transport layer 4 is 1 nm or more, holes can be sufficiently blocked, and when the thickness is 2000 nm or less, the layer is less likely to act as a resistance during electron transport, resulting in high photoelectric conversion efficiency. The thickness is more preferably 3 nm or less in lower limit and 1000 nm or less in upper limit, and even more preferably 5 nm or less in lower limit and 500 nm or more in upper limit.

[0114] [Control of particle size of charge transport particles] The particle size of the charge transport particles can be changed by dispersing the coating liquid for the charge transport layer using a paint shaker, and the particle size can be reduced by extending the dispersion time.Furthermore, the particle size can be reduced by centrifuging the coating liquid for the charge transport layer.

[0115] [Modularization Step] The method for manufacturing a photoelectric conversion element of the present invention may include a modularization step of encapsulating the element after electrodes have been formed. Examples of the encapsulation method include encapsulation with a resin or a film. Examples of materials used for encapsulation include silazane, silicone rubber, a resin having a siloxane skeleton, and glass. Furthermore, in order to prevent adhesion between elements that occurs when the element is wound up using a roll-to-roll method, the surface of the encapsulated element may be subjected to a hairline treatment.

[0116] [Application Examples] Application examples of the present invention relate to photoelectric conversion devices, mobile objects, and building materials. [Photoelectric Conversion Device] The photoelectric conversion device of the present invention has the above-described photoelectric conversion element. A photoelectric conversion device can be configured by using a plurality of photoelectric conversion elements of the present invention. When a plurality of photoelectric conversion elements are connected, the photoelectric conversion device can also be called a photoelectric conversion cell or a photoelectric conversion module. The photoelectric conversion element may be stacked with photoelectric conversion elements having different absorption wavelengths to increase the output voltage.

[0117] Furthermore, a photoelectric conversion device includes the photoelectric conversion element of the present invention and an inverter. The inverter may be a converter that converts direct current to alternating current. The photoelectric conversion device may include a storage unit connected to the photoelectric conversion element. The storage unit is not limited as long as it can store electricity. Examples of the storage unit include secondary batteries using lithium ions or the like, all-solid-state batteries, and electric double layer capacitors. In order to provide 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 to collect or guide light may be added.

[0118] [Mobile object] The mobile object of the present invention has the photoelectric conversion element described above. FIG. 2 is a perspective view schematically showing one embodiment of a mobile object equipped with the photoelectric conversion element of the present invention. The mobile object 30 has a photoelectric conversion element 31 of the present invention and a body 32 equipped with the photoelectric conversion element 31. The photoelectric conversion element 31 is disposed in a position on the body 32 where it can receive external light. If the mobile object 30 is an automobile, it may be disposed on the roof. The electrical energy obtained by the photoelectric conversion element 31 may power the mobile object 30 or may power other electrical equipment. Electrical energy generated from the power of the mobile object 30 may be used to power the photoelectric conversion element 31. If the mobile object 30 is an automobile, frictional energy generated by braking may be converted into electrical energy and used to control the photoelectric conversion element 31.

[0119] The mobile object 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 mobile object 30 is not particularly limited, but it is preferably made of a high-strength material.

[0120] [Building Material] The building material of the present invention has the photoelectric conversion element described above. Fig. 3 is a perspective view schematically showing one embodiment of a building material including the photoelectric conversion element of the present invention. The building material 40 may be the roof of a building. The building material 40 of this embodiment has the photoelectric conversion element 41 of the present invention, a protective member 42 that protects the photoelectric conversion element 41, a heat dissipation member 43, and exterior coverings 44a and 44b.

[0121] The building material 40 of the present invention may have a heat dissipation member 43 having a higher thermal conductivity than the photoelectric conversion element 41. When used on a roof or the like, sunlight may increase the temperature of the photoelectric conversion element 41, potentially reducing the photoelectric conversion efficiency. The use of the heat dissipation member 43 can reduce the reduction in photoelectric conversion efficiency. Examples of the heat dissipation member 43 include a metal, an alloy, a liquid metal, and a liquid resin.

[0122] The building material 40 of the present invention may also have exterior coatings 44a and 44b. The exterior coatings 44a and 44b may emit different colors or may be the same. 44a and 44b may be made of the same material or different materials. Paint or a transparent substrate may be used as the exterior coating. A material with low light absorption and high heat insulation properties is preferred.

[0123] In addition to the above application examples, other 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, 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.

[0124] [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. Furthermore, if the deposited shape 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.

[0125] Because perovskite crystals have a color such as black, the areas where the photoelectric conversion layer is formed can be visually confirmed. Furthermore, when observing with a scanning electron microscope (described below), the difference in contrast of the observed image and composition analysis using SEM-EDX can also be used to distinguish perovskite crystals from other layers.

[0126] 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 area where the photoelectric conversion layer was formed was confirmed visually. The length of each side of the obtained photoelectric conversion layer was measured using a ruler, and the film area was calculated.

[0127] [Confirmation of voids in 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 on which the photoelectric conversion layer has been formed, or by cutting the photoelectric conversion element and observing the cross section.

[0128] 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 (device: Carl Zeiss, Smart SEM). 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.

[0129] [Measurement of Average Film Thickness] The average film thickness of the photoelectric conversion layer or 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 or 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 (device: Carl Zeiss, Smart SEM). 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 an SEM-EDX function, and the average film thickness of the charge transport layer portion was measured by image processing of images taken at 50,000x magnification. Five randomly selected locations were photographed, and the average of the five average values ​​was taken as the average film thickness of the charge transport layer.

[0130] [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 measurement methods 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.

[0131] In this example, the arithmetic mean roughness Ra was calculated by image analysis of an atomic force microscope AFM / SPM (MFP-3D Origin manufactured by Oxford Instruments) obtained in AM-FM mode. The measurement conditions were as follows: a cantilever: OMCL-AC-160TS (manufactured by Olympus Corporation) was used, and a range of 90 μm × 90 μm was measured at a scanning frequency of 1 Hz. The number of X data points was 256, and the number of Y data points was 256.

[0132] [Measurement of the size of the crystals of the perovskite structure in the photoelectric conversion layer] The size of the crystals of the perovskite structure in the photoelectric conversion layer (hereinafter also referred to as "crystal size") can be confirmed using an SEM. For example, the crystal size 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.

[0133] In the present invention, the crystal size was measured as follows: First, the upper layer of the photoelectric conversion element was peeled off using a solvent or the like that does not destroy the perovskite crystal, thereby exposing the perovskite crystal. Next, the sample with the exposed perovskite crystal was fixed to a stage, and the surface was observed using an SEM (device: Carl Zeiss, SmartSEM).

[0134] During the observation, perovskite crystals were distinguished from other layers based on differences in contrast in the observed images and composition analysis using SEM-EDX, and the long diameter of the largest perovskite crystal was measured in an image taken at a magnification of 10,000x. Three randomly selected locations were photographed, and the average value of the long diameter of the largest perovskite crystal in each image was taken as the crystal size.

[0135] 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.

[0136] Example 1 Preparation of Charge Transport Particles 1 Step (1) Under a nitrogen flow atmosphere, 5.46 parts of orthophthalonitrile and 45 parts of α-chloronaphthalene were charged into a reaction vessel, and the vessel was heated to a temperature of 30°C and maintained at this temperature. Next, 3.75 parts of gallium trichloride was charged at this temperature (30°C). The water concentration of the mixture at the time of charging was 150 ppm.

[0137] The temperature was then raised to 200°C. Next, the mixture was reacted at 200°C for 4.5 hours under a nitrogen flow atmosphere, and then cooled. When the temperature reached 150°C, the product was filtered. The resulting filtrate was dispersed and washed using N,N-dimethylformamide at 140°C for 2 hours, and then filtered. The resulting filtrate was washed with methanol and dried to obtain chlorogallium phthalocyanine particles in a yield of 71%.

[0138] Step (2): 4.65 parts of the chlorogallium phthalocyanine particles were dissolved in 139.5 parts of concentrated sulfuric acid at 10°C, and the solution was added dropwise to 620 parts of ice water under stirring to reprecipitate the solution, which was then filtered under reduced pressure using a filter press. A No. 5C filter (manufactured by Advantec Co., Ltd.) was used. The resulting wet cake (filtered product) was dispersed and washed with 2% aqueous ammonia for 30 minutes, and then filtered using a filter press.

[0139] The resulting wet cake (filtrate) was then dispersed and washed with ion-exchanged water, and then filtered three times using a filter press. Finally, freeze-drying was performed to obtain hydroxygallium phthalocyanine particles (hydrated hydroxygallium phthalocyanine particles) with a solids content of 23% by mass in a yield of 71% by mass. The hydroxygallium phthalocyanine particles were dried in a Hyper Dry dryer (trade name: HD-06R, frequency (oscillation frequency): 2455 MHz±15 MHz, manufactured by Nippon Biocon) to obtain hydroxygallium phthalocyanine (OHGaPc) particles (crystals) with a moisture content of 1.0% by mass or less.

[0140] Step (3) Five parts of the hydroxygallium phthalocyanine (hereinafter also referred to as "HOGaPc") particles were mixed with five parts of N-methylformamide solvent, and this 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, followed by filtration and drying to obtain charge-transporting particles 1 (specific gravity 1.6). The aspect ratio was 3 or less.

[0141] <Preparation of Resin Solution 1> Resin solution 1 was obtained by dissolving 1.0 g of polyvinyl butyral (product name: BM-2, manufactured by Sekisui Chemical Co., Ltd., specific gravity 1.6) in 19 g of 2-propanol with stirring for 24 hours.

[0142] [Formation of Electron Transport Layer] Two square ITO-coated glass substrates, each 100 mm on a side, were cleaned, and a 5-fold diluted tin oxide (2) colloidal solution (15% aqueous dispersion, manufactured by Alfa Aesar) was applied thereon by spin coating, followed by heating at 150°C for 30 minutes to form a thin film electron transport layer with a thickness of 16 nm.

[0143] [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 solution 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. Finally, by heating, 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.

[0144] [Formation of Charge Transport Layer] 0.10 g of the charge transport particles 1 and 0.010 g of a calixarene compound (JP 2003-207913 A) 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 Seisakusho Co., Ltd.) for 7 hours.

[0145] Then, 0.20 g of resin solution 1 was added, and dispersion was again carried out using a paint shaker for 6 hours to prepare a charge transport layer coating solution. This charge transport layer solution was applied to the photoelectric conversion layer of one of the two substrates with the photoelectric conversion layer formed thereon 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.

[0146] [Introduction of Second Charge Transport Layer] 0.15 g of Spiro-OMeTAD was dissolved in 2.2 g of chlorobenzene as a material for the second charge transport layer. 36 μL of an acetonitrile solution obtained by dissolving 0.2 g of lithium bis(trifluoromethanesulfonyl)imide in 0.3 g of acetonitrile was added to the chlorobenzene solution, and 60 μL of 4-tert-butylpyridine (TBP) were added and mixed.

[0147] Further, 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 solution 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.

[0148] [Formation of First Electrode] Three 25 mm square substrates were cut out from the portion of the ITO-coated glass substrate where 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. ２ The ratio of the volume of the charge transport particles to the volume of the insulating resin in the charge transport layer of the resulting photoelectric conversion element was 7.1.

[0149] (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 with one side measuring 25 mm. In forming the first electrode, a gold electrode was formed on one 25 mm square substrate.

[0150] Example 3 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the gas quenching wind speed is increased in forming the photoelectric conversion layer. In forming the photoelectric conversion layer, blackening during gas quenching occurs more quickly than in Example 1.

[0151] 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 gas quenching speed in step (A-2) is further increased.

[0152] Example 5 A photoelectric conversion element is obtained in the same manner as in Example 1, except that methylammonium chloride is not used in preparing the coating liquid 1 for photoelectric conversion layer.

[0153] Example 6 In forming the photoelectric conversion layer, MAPbI was obtained by performing laser co-deposition of lead iodide and methylammonium iodide. ３ A photoelectric conversion element is obtained in the same manner as in Example 2, except that a photoelectric conversion layer made of

[0154] 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.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] (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 used is changed to an ITO-coated film, and in forming the photoelectric conversion layer, the coating method is changed to gravure coating.

[0160] 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.

[0161] Example 14 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the charge transport layer is formed by spin coating instead of die coating.

[0162] Example 15 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the charge transport layer is formed by blade coating instead of die coating.

[0163] Example 16 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the charge transport layer is formed by bar coating instead of die coating.

[0164] Example 17 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the charge transport layer is formed by spray coating instead of die coating.

[0165] Example 18 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the charge transport layer is formed by inkjet coating instead of die coating.

[0166] (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, gravure coating is used instead of die coating.

[0167] Example 20 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the charge transport layer is formed by screen coating instead of bar coating.

[0168] Example 21 A photoelectric conversion element is obtained in the same manner as in Example 9, except that the charge transport layer is formed by bar coating instead of die coating.

[0169] 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 a poor solvent method instead of a gas quenching method.

[0170] Example 23 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the photoelectric conversion layer is formed by air drying instead of using the gas quenching method.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] Example 27 A photoelectric conversion element was obtained in the same manner as in Example 1, except that the charge transport layer was formed by centrifuging the charge transport layer coating liquid to remove coarse particles. The color of the obtained film was lighter than that of the other samples.

[0175] Example 28 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the charge transporting particles 1 are replaced with quinacridone particles.

[0176] 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).

[0177] 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).

[0178]

[0179] 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.).

[0180] 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.).

[0181] 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.

[0182] Example 34 A photoelectric conversion element was prepared in the same manner as in Example 1, except that the photoelectric conversion layer was formed using the photoelectric conversion layer coating solution 2 prepared by the following method instead of the photoelectric conversion layer coating solution 1. 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 were dissolved in 4.25 g of N,N-dimethylformamide and 1.216 g of dimethyl sulfoxide and stirred for 1 hour (Solution 1). 0.100 g of cesium iodide was further dissolved in 0.285 g of dimethyl sulfoxide and stirred for 1 hour (Solution 2). The dissolved cesium iodide solution (Solution 2) was then added to Solution 1 to prepare the photoelectric conversion layer coating solution 2.

[0183] 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, second charge transport layer coating solution 2 prepared by dissolving 60 mg of P3HT in 3 mL of chlorobenzene is used instead of second charge transport layer coating solution 1. The film thickness of the second charge transport layer is 50 nm.

[0184] 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.

[0185] 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.

[0186] (Example 38) In forming the charge transport layer, a photoelectric conversion element is obtained in the same manner as in Example 1, except that the amount of resin solution 1 added 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 photoelectric conversion efficiency of the photoelectric conversion elements having charge transport layers prepared in Examples 1 to 37 is better than the maximum photoelectric conversion efficiency of the photoelectric conversion element having a charge transport layer prepared in Example 38.

[0187] Comparative Example 1 A photoelectric conversion element was obtained in the same manner as in Example 2, except that the photoelectric conversion layer was formed by spin coating instead of die coating.

[0188] Comparative Example 2 A photoelectric conversion element is obtained in the same manner as in Example 1, except that the charge transport particles 1 are not used in forming the charge transport layer.

[0189] 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.

[0190] Comparative Example 4 A photoelectric conversion element is obtained in the same manner as in Example 1, except that P3HT is used as the conductive resin instead of the insulating resin in forming the charge transport layer.

[0191] 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.

[0192] (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 applied instead of the charge transport layer coating liquid and then air-dried. Table 2 shows some of the production conditions for the photoelectric conversion elements produced in Examples 1 to 38 and Comparative Examples 1 to 6.

[0193] [Evaluation] [Analysis of Compound Amount] The electrode surface of the photoelectric conversion element was peeled off to expose the charge transport layer surface. This charge transport layer surface was wiped with a cotton swab or the like soaked in a solvent, dissolved in heavy water sulfuric acid, and subjected to 1H-NMR measurement (apparatus: AVANCE3-500, manufactured by BRUKER). In addition, the peeled charge transport layer components were subjected to mass and structural analysis by elemental analysis such as GPC, MALDI-TOF-MS, IR, gas chromatography, XPS, and EDX to confirm the presence of the compound.

[0194] [Confirmation of 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 of voids was confirmed by cross-sectional observation using an SEM (device: 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. The results are shown in Table 3.

[0195] [Confirmation of the deposition area of ​​the photoelectric conversion layer] The deposition area of ​​the photoelectric conversion layer was confirmed by the method described above. 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.

[0196] [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 a sample on which the photoelectric conversion layer had been formed, an atomic force microscope AFM / SPM (MFP-3D Origin manufactured by Oxford Instruments) was used to obtain a height image 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 (manufactured by Olympus Corporation) was used, and a range of 90 μm × 90 μm was measured at a scanning frequency of 1 Hz.

[0197] The number of X data pieces was 256, and the number of Y data pieces was 256. In Example 1, it was confirmed that the Ra measured by the above method after removing the first electrode and the charge transport layer from the photoelectric conversion element was the same as the Ra of the sample on which the photoelectric conversion layer had been formed. The results are shown in Table 3.

[0198] [Measurement of Crystal Size of Perovskite Structure in Photoelectric Conversion Layer] The crystal size was measured using 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 crystal, thereby exposing the perovskite crystal. Next, the sample with the exposed perovskite crystal was fixed to a stage, and the surface was observed using an SEM (device: Carl Zeiss, SmartSEM).

[0199] During the observation, perovskite crystals were distinguished from other layers based on differences in contrast in the observed image and composition analysis using SEM-EDX, and the major axis 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 major axis of the largest perovskite crystal in each image was taken as the crystal size. The results are shown in Table 3.

[0200] [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 an SEM (device: Carl Zeiss Smart SEM).

[0201] During 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 SEM-EDX, and the average film thickness of the charge transport layer portion was measured using image processing of images taken at 50,000x magnification. Five randomly selected locations were photographed, 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.

[0202] [Evaluation of Mass-Producibility] As for the mass-producibility, it was determined that the photoelectric conversion layer was not suitable for mass production when it was formed by spin coating, as described in the embodiment of the present invention. The results are shown in Table 2.

[0203] [Evaluation of Uniformity] A power supply (manufactured by KEITHLEY, Model 236) was connected between the electrodes of each of the photoelectric conversion elements formed with a charge transport layer and the photoelectric conversion element not formed with a charge transport layer, which were fabricated in the Examples and Comparative Examples. 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. The measurement was performed on each of the 10 electrodes for all 25 mm square samples of each photoelectric conversion element.

[0204] The difference between the highest and lowest photoelectric conversion efficiencies was calculated for each of the sample with a charge transport layer and the photoelectric conversion element without a charge transport layer, and ΔPCE １ , ΔPCE ０ When the area where the photoelectric conversion layer is formed is large and a plurality of 25 mm square photoelectric conversion elements are cut out in forming the first electrode, ΔPCE was calculated using the highest and lowest photoelectric conversion efficiencies among the plurality of photoelectric conversion elements. １ and ΔPCE ０ For example, the photoelectric conversion element produced in Example 1 has three samples each having a charge transport layer formed thereon, and therefore, the difference between the highest and lowest photoelectric conversion efficiencies measured at a total of 30 electrodes was calculated as ΔPCE １ Similarly, 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 used as ΔPCE. ０ The obtained ΔPCE１ and ΔPCE ０ The difference is ΔΔPCE = ΔPCE ０ -ΔPCE １ The results are shown in Table 3.

[0205] If ΔΔPCE was 2% or more, it was determined that the effect of the present invention was manifested (uniformity of photoelectric conversion efficiency was present). 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.

[0206]

[0207]

[0208] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0209] This application is related to Japanese Patent Application No. 2023-184761 filed on October 27, 2023, Japanese Patent Application No. 2023-184756 filed on October 27, 2023, Japanese Patent Application No. 2023-184750 filed on October 27, 2023, Japanese Patent Application No. 2023-216294 filed on December 21, 2023, Japanese Patent Application No. 2023-216296 filed on December 21, 2023, and Japanese Patent Application No. 2023-2162 filed on December 21, 2023. 99, Japanese Patent Application No. 2024-022244 filed on February 16, 2024, Japanese Patent Application No. 2024-022251 filed on February 16, 2024, Japanese Patent Application No. 2024-022246 filed on February 16, 2024, Japanese Patent Application No. 2024-145656 filed on August 27, 2024, and Japanese Patent Application No. 2024-186710 filed on October 23, 2024. Priority is claimed based on the above, the entire contents of which are incorporated herein by reference.

[0210] REFERENCE SIGNS LIST 1 Photoelectric conversion element 2 Substrate 3 Second electrode 4 Electron transport layer 5 Photoelectric conversion layer 6 Charge transport layer 7 First electrode 11 Perovskite crystal 12 Charge transport particles 13 Insulating resin 30 Mobile body 31, 41 Photoelectric conversion element 32 Machine body 40 Building material 42 Protective member 43 Heat dissipation member 44a, 44b Exterior

Claims

1. A method for producing a photoelectric conversion element, comprising: step (A) of forming a photoelectric conversion layer containing crystals of a perovskite structure by using a large-area film formation method; and step (B) of forming a charge transport layer by applying a paint for a charge transport layer onto the surface of the photoelectric conversion layer and then drying the paint, 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 or 2, wherein the photoelectric conversion layer has voids.

4. The method for producing a photoelectric conversion element according to any one of claims 1 to 3, 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 any one of claims 1 to 4, wherein the size of the crystal is 1.0 μm or more.

6. The method for producing a photoelectric conversion element according to any one of claims 1 to 5, wherein the step (A) comprises 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 or 7, wherein the step (A-2) does not include a step of applying a poor solvent to the raw material for the crystals.

9. The method for producing a photoelectric conversion element according to any one of claims 6 to 8, 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 any one of claims 6 to 9, wherein the step (B) has the same coating method as the step (A-1).

11. The method for producing a photoelectric conversion element according to any one of claims 1 to 10, wherein 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 any one of claims 1 to 11, wherein the average film thickness of the charge transport layer is 50 nm or more.

13. The method for producing a photoelectric conversion element according to any one of claims 1 to 12, 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 any one of claims 1 to 13, wherein the charge transporting particles contain a phthalocyanine compound.

15. The method for producing a photoelectric conversion element according to any one of claims 1 to 14, wherein the charge transporting particles contain a hydroxygallium phthalocyanine compound.

16. The method for producing a photoelectric conversion element according to any one of claims 1 to 15, wherein the glass transition point of the insulating resin is lower than 100°C.

17. The method for producing a photoelectric conversion element according to any one of claims 1 to 16, 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 any one of claims 1 to 17, wherein the photoelectric conversion element has a second charge transport layer not containing charge transport particles on the charge transport layer.

19. The method for producing a photoelectric conversion element according to any one of claims 1 to 18, wherein in the charge transport layer, the ratio of the volume of the charge transport particles to the volume of the insulating resin is 5 or more and 30 or less.

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