Photoelectric conversion element and method for manufacturing the same

Abstract

To provide a photoelectric conversion element that can prevent the leakage of solution. [Solution] The photoelectric conversion element 1 comprises a transparent electrode layer 3 and a second conductive layer 7, a photoelectric conversion layer provided between the transparent electrode layer 3 and the second conductive layer 7, and a protective wall portion 9 formed to surround the photoelectric conversion layer at a distance from it. The photoelectric conversion layer includes a porous electron transport layer 5 containing a perovskite compound in its voids, and an insulating layer 6 containing a perovskite compound in its voids and laminated on the porous electron transport layer 5. The insulating layer 6 and the protective wall portion 9 contain the same porous material.

Description

[Technical Field]

[0001] This disclosure relates to a photoelectric conversion element using a perovskite compound and a method for manufacturing the same. [Background technology]

[0002] In recent years, solar cells have become increasingly popular as a method of utilizing renewable energy. While solar cells using inorganic photoelectric elements (e.g., silicon-based solar cells, CIGS-based solar cells, and CdTe-based solar cells) are widely used, solar cells using organic photoelectric elements (e.g., organic thin-film solar cells, dye-sensitized solar cells, and perovskite solar cells) are also being investigated. Perovskite solar cells, in particular, are being actively researched from the standpoint that they can be manufactured at a lower cost compared to conventional solar cells (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2016-178167 [Overview of the project] [Problems that the invention aims to solve]

[0004] Conventional solar cells have a substrate, a base layer laminated on the substrate, and a light-absorbing layer containing an organic-inorganic perovskite compound formed inside the base layer. The base layer is formed by spraying at least one of N-type semiconductor nanoparticles and insulating nanoparticles to which the organic-inorganic perovskite compound is attached onto the substrate.

[0005] In conventional solar cells, a process of applying a solution containing a perovskite compound or its precursor is used to form the light-absorbing layer. However, there is a problem in that the solution does not remain within the underlying layer but leaks out. As a result, the formation of the perovskite compound is insufficient, leading to a problem in achieving sufficient power generation performance.

[0006] This disclosure is made to solve the above-mentioned problems and aims to provide a photoelectric conversion element that can prevent the leakage of solution, and a method for manufacturing the same. [Means for solving the problem]

[0007] The photoelectric conversion element according to this disclosure comprises a first conductive layer and a second conductive layer, a photoelectric conversion layer provided between the first conductive layer and the second conductive layer, and a protective wall portion formed to surround the photoelectric conversion layer at a distance from it, wherein the photoelectric conversion layer includes a porous layer in which a perovskite compound is contained in the voids, and the porous layer and the protective wall portion include the same porous material.

[0008] In the photoelectric conversion element according to this disclosure, the porous layer includes a first porous layer containing a perovskite compound in its voids, and a second porous layer containing a perovskite compound in its voids and laminated on the first porous layer, and the barrier portion may be configured to include the same porous material as the second porous layer.

[0009] In the photoelectric conversion element according to this disclosure, the protective wall portion may have the same thickness as the second porous layer.

[0010] In the photoelectric conversion element according to this disclosure, the protective wall portion may be configured such that a liquid-repellent portion having liquid-repellent properties is formed in the void.

[0011] In the photoelectric conversion element according to this disclosure, the liquid-repellent portion may be formed of a fluorine-based silane compound.

[0012] The photoelectric conversion element according to this disclosure comprises a first conductive layer and a second conductive layer, a photoelectric conversion layer provided between the first conductive layer and the second conductive layer, and a protective wall portion formed on the outside of the photoelectric conversion layer when viewed in cross-section, wherein the photoelectric conversion layer includes a porous layer in which a perovskite compound is contained in the voids, and the porous layer and the protective wall portion include the same porous material.

[0013] A method for manufacturing a photoelectric conversion element according to this disclosure includes the steps of providing a first conductive layer, a photoelectric conversion layer, and a second conductive layer in order from a substrate, and forming a protective wall portion spaced apart from the photoelectric conversion layer and surrounding it, wherein the photoelectric conversion layer includes a porous layer containing a perovskite compound in its voids, and the porous layer and the protective wall portion contain the same porous material.

[0014] The method for manufacturing a photoelectric conversion element according to this disclosure may include a step of simultaneously laminating a porous material in the region corresponding to the porous layer and the barrier portion. [Effects of the Invention]

[0015] According to this disclosure, by providing a barrier, it is possible to prevent the solution dropped onto the porous layer from flowing out of the photoelectric conversion layer. This prevents insufficient formation of the perovskite compound in the voids of the porous layer. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic cross-sectional view showing a photoelectric conversion element according to an embodiment of the present disclosure. [Figure 2] This is a schematic top view showing a photoelectric conversion element according to an embodiment of the present disclosure. [Figure 3] This is a schematic cross-sectional view showing the process of forming a porous electron transport layer before firing in a method for manufacturing a photoelectric conversion element. [Figure 4] This is a schematic cross-sectional view showing the process of forming the insulating layer and protective wall portion before firing in a method for manufacturing a photoelectric conversion element. [Figure 5]It is a schematic cross-sectional view showing a firing step in a method for manufacturing a photoelectric conversion element. [Figure 6] It is a schematic cross-sectional view showing a step of forming a second conductive layer in a method for manufacturing a photoelectric conversion element. [Figure 7] It is a schematic cross-sectional view showing a step of dropping a liquid repellent material in a method for manufacturing a photoelectric conversion element. [Figure 8] It is a schematic cross-sectional view showing a step of dropping a perovskite solution in a method for manufacturing a photoelectric conversion element. [Figure 9] It is a schematic cross-sectional view showing a photoelectric conversion module including a plurality of photoelectric conversion elements. [Figure 10] It is a schematic top view showing a photoelectric conversion module including a plurality of photoelectric conversion elements. DESCRIPTION OF EMBODIMENTS

[0017] Hereinafter, a photoelectric conversion element according to an embodiment of the present disclosure will be described with reference to the drawings.

[0018] FIG. 1 is a schematic cross-sectional view showing a photoelectric conversion element according to an embodiment of the present disclosure, and FIG. 2 is a schematic top view showing the photoelectric conversion element according to an embodiment of the present disclosure.

[0019] In the photoelectric conversion element 1 according to the first embodiment of the present disclosure, a transparent electrode layer 3 (an example of a first conductive layer) and a dense electron transport layer 4 are laminated on a base body 2. A photoelectric conversion layer (a porous electron transport layer 5 and an insulating layer 6) and a second conductive layer 7 are laminated on the dense electron transport layer 4 at a portion corresponding to the element region SR. Further, a barrier portion 9 is laminated on the dense electron transport layer 4 at a portion corresponding to a frame region WR which is provided so as to be spaced apart from the element region SR and surround the periphery when viewed from above (see FIG. 2).

[0020] However, the element region basically refers to the region on the substrate 2 where all layers of the transparent electrode layer 3, dense electron transport layer 4, photoelectric conversion layer (porous electron transport layer 5 and insulating layer 6), and second conductive layer 7 are stacked and superimposed. Furthermore, it is desirable that the element region also includes the region occupied by at least the photoelectric conversion layer, in addition to the basic region described above. Furthermore, the element region may also include the region occupied by at least the electron transport layer, in addition to some of the regions described above. Furthermore, the element region may also include the region occupied by the hole transport layer, if one is present, in addition to some of the regions described above. Furthermore, the element region may also include the region occupied by at least the second conductive layer 7, in addition to some of the regions described above. Furthermore, the element region may, in some cases, include the region occupied by at least the transparent electrode layer 3, in addition to some of the regions described above. In addition, the frame region refers to all regions that are not part of each of the element regions described above. That is, the frame region is defined as the region that is not part of each element region.

[0021] Furthermore, "surrounding a certain region" means, for example, in a microscopic observation of any region from the light-receiving surface side (or the back side opposite the light-receiving surface side), it is sufficient to confirm that at least a portion of each of the two ends of a certain region (for example, any two opposing sides of a certain region) is located outside the ends of the region in the observation images obtained by individually observing each side. Alternatively, if confirmation is difficult with the above microscopic observation, "surrounding a certain region" may be confirmed by performing a cross-sectional observation and confirming that the region is located outside the respective ends in the observation images obtained by individually observing both ends of the region in at least one cross-section. As stated above, confirmation of "surrounding a certain region" is sufficient by observing two points on any two opposing sides or any cross-section, but it is even more preferable to confirm this by observing two points on two opposing sides different from the two opposing sides, or two points on any cross-section perpendicular to any cross-section.

[0022] Substrate 2 is the substrate for the photoelectric conversion element 1, and is the same as or contains the same as the substrate or base material. It may be hard and rigid, or it may be flexible and have low rigidity. Examples of materials that can be used as substrate 2 include glass and organic films. Examples of organic film materials include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyetherimide (PEI), polytetrafluoroethylene (PTFE), polyamideimide (PAI), and polyethylene naphthalate (PEN), but other resins can also be used as long as they meet the requirements. The thickness of the organic film that forms substrate 2 is preferably about 50 μm to 100 μm.

[0023] When light is shone (light is incident on) the surface of the photoelectric conversion element 1 on the substrate 2 side (the bottom surface of the substrate 2 in Figure 1), that is, when the side of the substrate 2 is the light-receiving surface, it is preferable that the substrate 2 is transparent. However, when light is shone from the opposite side, the substrate 2 may be opaque. Note that transparency means that light is transmitted, but this does not exclude anything that reflects or absorbs even a little light; it is sufficient that light is transmitted appropriately, and this can be considered synonymous with being provided on the light-receiving surface side of the solar cell (including the part where light is incident, as is the case in this disclosure). Therefore, it can be said that it is transparent if it is provided at least on the light-receiving surface side of the solar cell.

[0024] The first conductive layer is a conductive material. That is, the transparent electrode layer 3, which is an example of the first conductive layer in this embodiment, is a conductive material. The first conductive layer is formed on the substrate 2, on the surface of the substrate 2, or on one side of the substrate 2 (for example, the upper side), and functions as an electrode for extracting the photovoltaic power of the photoelectric conversion element 1. The transparent electrode layer 3 is formed of a transparent conductive material, such as conductive transparent materials such as FTO (fluorine-doped tin oxide), CuI (copper iodide), ITO (indium tin oxide), SnO2 (tin oxide), AZO (aluminum zinc oxide), IZO (indium zinc oxide), GZO (gallium zinc oxide), ATO (antimond-doped tin oxide), or conductive transparent polymers. Note that the chemical formulas are representative examples and any compound name is acceptable (similarly in this disclosure). Furthermore, while a stoichiometric composition ratio of the chemical formula is desirable, it does not necessarily have to be stoichiometric (similarly in this disclosure). The transparent electrode layer 3 may have a configuration in which a conductive metal such as silver or its fine wires are formed on an oxide film of a conductive transparent material. The term "film" does not specify a thickness or width, and includes patterned or island-shaped films or films with parts of different thicknesses. Preferably, the film has a substantially constant thickness. Unless otherwise specified, "substantially" or "to a certain extent" refers to the range of manufacturing tolerances, and preferentially indicates that a variation of plus 15% and minus 15% of that value is acceptable. As long as the solar cell functions as a solar cell, it can be confirmed that the parts with the appropriate material are conductive, and it is not necessary to check the physical properties of the conductive layer to confirm conductivity.

[0025] The dense electron transport layer 4 is a layer capable of transporting electrons generated in the light-absorbing portion (for example, a perovskite compound). The dense electron transport layer 4 naturally possesses this function as long as the solar cell has a photoelectric conversion function, and can be considered equivalent to being located on the electron transport side of the light-absorbing portion of the solar cell. Therefore, as long as it is located on the electron transport side of the perovskite compound, it can be said to have an electron transport function. It is preferable that the dense electron transport layer 4 has a function of blocking hole transport. The dense electron transport layer 4 is dense. Details regarding the dense material are described below, but it is preferable that the layer has few or no pores. Furthermore, it is preferable that most of these pores are independent and not connected. The dense layer can function as a layer where, even if a liquid is dropped onto it, the liquid hardly penetrates the dense layer. In this embodiment, the dense electron transport layer 4 is formed of titanium oxide or tin oxide. Furthermore, the dense electron transport layer 4 is provided on top of the transparent electrode layer 3.

[0026] Furthermore, the term "electron transport layer" can refer to both dense electron transport layers and porous electron transport layers, or to each of these layers individually, or it can refer to an electron transport layer as a general concept that includes other layers with electron transport functions.

[0027] A layer does not define thickness or width, and includes patterns, islands, or parts with different thicknesses. Preferably, a layer is a component with approximately constant thickness.

[0028] Compact matter, also known as compact or compact quality, can be the same as or contain the same as these.

[0029] Porous, also known as porous or mesoporous, can be the same as or include the same. In this disclosure, porous means a material that can contain light-absorbing portions (e.g., perovskite compounds) in its voids (which can be described in various ways, such as gaps, holes, or pores). The porous layer may include, but is not limited to, a porous electron transport layer or an insulating layer, or a porous electron transport layer and an insulating layer. Preferably, the porous electron transport layer is located on one side of the thickness direction of the porous layer (e.g., the bottom side), and the insulating layer is located on the opposite side (e.g., the top side). The porous layer may also include a porous hole transport layer or a second conductive layer.

[0030] Furthermore, it is preferable that the compact material has almost no voids or, if any, extremely small voids. In this disclosure, compact material means that, upon observation, one side of the compact material in the thickness direction (for example, the lower side) is free of light-absorbing regions (in this embodiment, for example, a perovskite compound, and hereinafter described as a perovskite compound). In other words, even if a perovskite compound is present on the upper side of the compact material, it is possible to ensure that it does not penetrate and remain absent on the lower side of the compact material. Preferably, compact material has extremely small voids. Preferably, compact material has a maximum void width of less than 5 nm. Preferably, compact material suppresses the penetration of perovskite compounds, and allows for a state where perovskite compounds are absent on one side of the compact material in the thickness direction. Even more preferably, compact material means that perovskite compounds cannot be contained in the voids, or that there are no regions in which perovskite compounds exist continuously throughout the thickness of the compact material. In other words, if the dense layer cannot be confirmed by the maximum width of its voids, it is sufficient if observation by SEM or EDX shows that there are no areas where the perovskite compound penetrates the layer thickness. In this disclosure, unless otherwise contradictory, observation by SEM is sufficient if it can be confirmed by observing a 400 nm wide cross-sectional SEM (or EDX) image. For example, if observation by a single 400 nm wide cross-sectional SEM or EDX shows no areas where the perovskite compound penetrates the layer thickness, then that layer can be said to be dense. The dense electron transport layer 4 can be deposited by known methods, such as sputtering, die coating, or screen printing. The layer thickness may be, for example, 10 nm to 200 nm, but is not limited to this.

[0031] The porous electron transport layer 5 (an example of the first porous layer) functions as an electron transport layer that transports electrons generated in the light absorption section to the electrodes. For example, titanium oxide, tin oxide, and aluminum oxide can be used as materials for the porous electron transport layer 5. Furthermore, any N-type inorganic oxide is preferable for the porous electron transport layer 5. The electron transport layer naturally possesses this function as long as the solar cell has the function of photoelectric conversion, and can be considered equivalent to being located on the electron transport side of the light absorption section of the solar cell. Therefore, as long as it is located on the electron transport side of the perovskite compound, it can be said to have an electron transport function. It is preferable that the electron transport layer also has the function of blocking hole transport.

[0032] As previously explained in detail, a porous layer is preferably one that has numerous pores within it, and these pores are interconnected. Because it is porous, when a liquid (one with good wettability) is dropped onto a porous layer (one with hollow pores), the liquid seeps into the porous layer. Furthermore, the term "porous layer" refers to a layer formed entirely of porosity. If each layer, such as the photoelectric conversion layer, porous electron transport layer 5, insulating layer 6, hole transport layer, and second conductive layer 7, is porous or contains porous parts, then these porous parts are also included in the term "porous layer."

[0033] In this embodiment, the porous electron transport layer 5 is a porous layer containing voids, and is occupied by the first metal oxide 5a that constitutes itself and the voids that are the gaps between the first metal oxide 5a, and the voids of the porous electron transport layer 5 are filled with the perovskite compound 8. The porous electron transport layer 5, like the dense electron transport layer 4, is a layer that can transport electrons generated by the perovskite compound, and naturally has that function insofar as it functions as a solar cell. That is, as long as it is located on the electron transport side (or negative electrode side, similarly in this disclosure) of the perovskite compound of the solar cell, it can be said to have an electron transport function. The porous electron transport layer 5 may preferably be a mesoporous layer. Furthermore, it is even better if the porous electron transport layer 5 is a mesoporous nanocrystalline layer.

[0034] The insulating layer 6 (an example of the second porous layer) is made of a porous material. Examples of materials for the insulating layer 6 include metal oxides containing titanium oxide, zirconium dioxide, and aluminum oxide, and oxides containing silicon dioxide. It should be noted that insulation does not necessarily have to completely prevent the movement of charge; depending on its thickness and structure, it is acceptable if it cannot completely prevent but can suppress the movement of charge. Adding an insulating layer increases the distance between the first conductive layer (including the electron transport layer if any) and the second conductive layer (including the hole transport layer if any), suppressing physical contact between the materials on both sides and preventing the recombination of electrons and holes generated in the light-absorbing area. In other words, adding an insulating layer can improve the performance of the solar cell and contribute to achieving commercial-level performance. Therefore, the insulating layer exists between the first conductive layer (including the electron transport layer, if present) and the second conductive layer (including the hole transport layer, if present), contributing to increasing the distance between each side. As a result, if the solar cell is commercially available, verification is sufficient, and there is no need to verify the physical properties of the insulating performance.

[0035] The insulating layer 6 is a porous layer containing voids, preferably having many voids with a size of 20 nm or more. Light-absorbing portions that absorb irradiated light are provided in the voids of the insulating layer 6. In this embodiment, the insulating layer 6 is occupied by the second metal oxide 6a that constitutes itself and voids which are the gaps between the second metal oxide 6a, and the voids of the insulating layer 6 are filled with the perovskite compound 8. The insulating layer 6 also has voids with a size of less than 20 nm, and these small voids may also be considered as voids.

[0036] The second conductive layer 7 is a conductive material. It functions as an electrode for extracting the photovoltaic power of the photoelectric conversion element 1. It has the function of collecting holes photoexcited in the light absorption section, and is preferably formed of a porous carbon material.

[0037] As the second conductive layer 7, for example, a metal film with a work function of 5 eV or higher can be used. By having the second conductive layer 7 composed of a metal with a deep work function (5 eV or higher), it becomes easier to generate a band structure bend that allows for smooth hole flow at the interface between the light-absorbing layer or light-absorbing portion or the layer on the light-absorbing portion side and the second conductive layer. As the material for the second conductive layer 7, for example, metals such as Ni, Pt, and Pd can be used. The film thickness of the second conductive layer 7 is preferably around 50 nm to 150 nm. The second conductive layer 7 can be formed by methods such as sputtering or vacuum deposition. In addition, conductive carbon materials such as graphite, graphene, carbon nanowires, carbon nanofibers, carbon nanotubes, and carbon black can be used. In principle, any material that is conductive is not excluded from application. As long as the solar cell functions as a solar cell, it is possible to confirm that the part with the appropriate material is conductive, and it is not necessary to check the physical properties of the conductive layer to confirm conductivity.

[0038] The light-absorbing portion described above contains a perovskite compound. In this embodiment, the porous electron transport layer 5, the insulating layer 6, and the second conductive layer 7 also have light-absorbing portions. That is, the light-absorbing portions are arranged in the voids (which can be expressed in various ways, such as gaps, holes, or pores) of these layers. Preferably, it is desirable that the voids in the porous electron transport layer 5, the insulating layer 6, and the second conductive layer 7 are filled with light-absorbing portions. As long as a solar cell has a photoelectric conversion function, it naturally includes a light-absorbing portion as a component. The light-absorbing portion generates electrons and holes by absorbing light, the electrons generated in the light-absorbing portion move to the electron transport layer, and the holes generated in the light-absorbing portion move to the second conductive layer 7, where the charge is separated. As long as a solar cell has a photoelectric conversion function, it can be confirmed that electrons and holes are generated by absorbing light in the portion with the appropriate material, and it is not necessary to check the physical properties of the photoelectric conversion of the light-absorbing portion in order to confirm that it is a light-absorbing portion.

[0039] A light-absorbing region refers to a specific area (for example, a perovskite compound) that absorbs light, and this region can be collectively described as a light-absorbing layer. Here, a light-absorbing region can mean a specific area or part of the light-absorbing layer. Furthermore, a light-absorbing layer can mean a collection of discretely existing light-absorbing regions in a region with a certain thickness (which does not need to be constant) in a certain direction.

[0040] The perovskite compound contained in the light-absorbing portion is composed of a compound represented by the general formula: ABX3···(1). However, while the composition ratio of each is preferably 1:1:3, it is not necessarily 1:1:3, the content of each element may be adjusted as appropriate, and each constituent element does not need to be of only one type. As long as the light-absorbing portion has a photoelectric conversion function, the perovskite compound contained in the light-absorbing portion is exhibiting that photoelectric conversion function, and therefore, it is reasonable to assume that it is exhibiting that function even with the degree of freedom in composition as described in terms of composition ratio and type of constituent element. In general formula (1), A is an organic molecule (including an organic group or organic cation, as is the case in this disclosure) or an inorganic atom or molecule (including an inorganic group or inorganic cation, as is the case in this disclosure) or a combination thereof, B is a metal atom or molecule (including a metal cation, as is the case in this disclosure), and X is a halogen atom or molecule or a chalcogen atom or molecule (including a halogen anion or chalcogen anion, as is the case in this disclosure). In general formula (1), the three X's may be the same or different from each other. As long as a solar cell has a photoelectric conversion function, the perovskite compound contained in the light-absorbing part is exhibiting a photoelectric conversion function, and this should be taken into consideration. That is, if it can be confirmed that a compound is a perovskite compound, it is reasonable to consider it a perovskite compound that exhibits a photoelectric conversion function if it has A, B, and X. For example, it is sufficient if it is found to have an organic molecule, a metal atom, and a halogen atom. Furthermore, as long as a solar cell has a photoelectric conversion function, it can be confirmed that a compound is a perovskite compound if elements corresponding to A, B, and X are detected. For example, as organic molecules, molecules containing carbon, nitrogen, and hydrogen are suitable, and therefore, it is sufficient if carbon, nitrogen, hydrogen, a metal element, and a halogen or chalcogen are detected. Alternatively, a compound is a perovskite compound if it has A, B, and X. For example, it is sufficient if it is found to have an inorganic atom, a metal atom, and a halogen atom. Furthermore, the presence of a perovskite compound can be confirmed if elements A, B, and X are detected, as long as the solar cell has a photoelectric conversion function.For example, cesium or rubidium are preferred as inorganic atoms; therefore, it is sufficient if cesium or rubidium, a metallic element, and a halogen or chalcogen are detected. Furthermore, the fact that it is a perovskite compound is based on the premise that a solar cell has a crystalline structure as long as it has a photoelectric conversion function, and therefore confirmation of the presence of a crystalline structure is not required. The light-absorbing portion may contain substances other than the perovskite compound.

[0041] The light-absorbing portion may contain organic-inorganic hybrid compounds. An organic-inorganic hybrid compound refers to a compound containing both inorganic and organic materials. Perovskite compounds are also included in organic-inorganic hybrid compounds, and solar cells using perovskite compounds are also called organic-inorganic hybrid solar cells. "Organic" typically refers to materials composed of multiple carbon atoms. However, carbon materials such as graphite, graphene, carbon nanowires, carbon nanofibers, carbon nanotubes, and carbon or carbon black that function as electrodes are not specifically considered organic materials. In other words, organic refers to materials that, excluding the above-mentioned carbon materials such as graphite, have multiple carbon atoms as one of their constituent elements. "Inorganic" refers to materials that are not organic.

[0042] The light-absorbing portion may include quantum dots. A quantum dot is defined as a dot with a maximum width of 100 nm or less. The shape of the quantum dot is not particularly restricted and is not limited to a spherical three-dimensional shape (circular cross-sectional shape), as long as it satisfies the above maximum width. For example, it may have a polygonal cross-sectional shape, a rod-shaped three-dimensional shape, a branch-shaped three-dimensional shape, a three-dimensional shape with irregularities on the surface, or a combination thereof. The quantum dot is typically made of a semiconductor. A semiconductor is any material that can absorb light and may include at least the materials described below. The semiconductor includes, for example, at least one selected from the group consisting of group II-VI compounds, group III-V compounds, chalcogenides, and perovskite compounds. Note that group II-VI compounds mean compounds containing group II and group VI elements, and group III-V compounds mean compounds containing group III and group V elements. Furthermore, Group II elements include Group 2 and Group 12 elements, Group III elements include Group 3 and Group 13 elements, Group V elements include Group 5 and Group 15 elements, and Group VI elements may include Group 6 and Group 16 elements. Here, the group numbering of elements using Roman numerals is based on the old IUPAC or old CAS system, and the group numbering of elements using Arabic numerals is based on the current IUPAC system. Semiconductors include, for example, at least one selected from the group consisting of MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, GaAs, GaP, InN, InAs, InP, and InSb.

[0043] Examples of organic molecules represented by A in general formula (1) include alkylamines, alkylammonium compounds, and nitrogen-containing heterocyclic compounds. In perovskite compound (1), the organic molecule represented by A may be only one type of organic molecule, or it may be two or more types of organic molecules.

[0044] Examples of alkylamines include methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, ethylmethylamine, methylpropylamine, butylmethylamine, methylpentylamine, hexylmethylamine, ethylpropylamine, and ethylbutylamine.

[0045] Alkylammonium compounds are ionized compounds of the alkylamines mentioned above. Examples of alkylammonium compounds include methylammonium, ethylammonium, propylammonium, butylammonium, pentylammonium, hexylammonium, dimethylammonium, diethylammonium, dipropylammonium, dibutylammonium, dipentylammonium, dihexylammonium, trimethylammonium, triethylammonium, tripropylammonium, tributylammonium, tripentylammonium, trihexylammonium, ethylmethylammonium, methylpropylammonium, butylmethylammonium, methylpentylammonium, hexylmethylammonium, ethylpropylammonium, and ethylbutylammonium.

[0046] Examples of nitrogen-containing heterocyclic compounds include imidazole, azole, pyrrole, aziridine, azirine, azetidine, azeto, azole, imidazoline, and carbazole. Nitrogen-containing heterocyclic compounds may also be ionized. Phenethylammonium is preferred as an ionized nitrogen-containing heterocyclic compound.

[0047] In general formula (1), the organic molecule represented by A is preferably methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, methylammonium, ethylammonium, propylammonium, butylammonium, pentylammonium, hexylammonium, or phenethylammonium, more preferably methylamine, ethylamine, propylamine, methylammonium, ethylammonium, or propylammonium, and even more preferably methylammonium.

[0048] In general formula (1), examples of metal atoms represented by B include lead, tin, zinc, titanium, antimony, bismuth, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, and europium. In perovskite compounds, the metal atom represented by B may be only one type of metal atom, or it may be two or more types of metal atoms. From the viewpoint of improving the light absorption and charge generation characteristics of perovskite compounds, lead atoms or tin atoms are preferred as the metal atom represented by B. From the viewpoint of reducing lead, tin atoms are preferred.

[0049] In general formula (1), examples of halogen atoms represented by X include fluorine, chlorine, bromine, and iodine atoms, while examples of chalcogen atoms include oxygen, sulfur, selenium, and tellurium atoms. In a perovskite compound, the halogen atom or chalcogen atom represented by X may be one or two or more. From the viewpoint of enabling the perovskite compound to utilize light in a broad wavelength range, iodine is preferred as the halogen atom represented by X. More specifically, it is preferable that at least one of the three Xs represents an iodine atom, and more preferably that all three Xs represent iodine atoms.

[0050] As the perovskite compound, compounds represented by the general formula "CH3NH3PbX3 (where X represents a halogen atom)" are preferred, and CH3NH3PbI3 is more preferred. By using a compound represented by the general formula "CH3NH3PbX3" (especially CH3NH3PbI3) as the perovskite compound, electrons and holes can be generated more efficiently in the perovskite compound, and as a result, the photoelectric conversion efficiency of the photoelectric conversion element 1 can be further improved.

[0051] A photoelectric conversion layer is a layer that converts light into electricity. It can include a porous layer and a light-absorbing layer, and refers to a layer located at least between the first conductive layer and the second conductive layer. The light-absorbing layer is often located between the first conductive layer and the second conductive layer, and if the light-absorbing layer is located only between the first and second conductive layers, then the photoelectric conversion layer is also located only between the first and second conductive layers. However, if the first and second conductive layers have a special shape, such as being porous, the light-absorbing layer may include a region encompassing the first and second conductive layers themselves. In such cases, the portion of the first and second conductive layers containing the light-absorbing layer can also be included in the photoelectric conversion layer. Even in that case, the photoelectric conversion layer is located at least between the first and second conductive layers. In other words, in all cases, a solar cell (photoelectric conversion element) is provided with a first conductive layer, a photoelectric conversion layer, and a second conductive layer in that order from the substrate, and this does not exclude the first and second conductive layers themselves from being included, nor does it exclude the presence of a photoelectric conversion layer in parts other than between the first and second conductive layers.

[0052] In this embodiment, the hole transport layer may be placed between the perovskite compound, which is the light-absorbing portion, and the second conductive layer 7. The hole transport layer may also be porous. If the hole transport layer is porous, it can contain the light-absorbing portion within the voids of the porous layer, similar to other porous materials (layers). The hole transport layer is a layer that has the function of moving holes generated in the light-absorbing portion to the second conductive layer 7. It is self-evident that, as long as the solar cell has a photoelectric conversion function, the hole transport layer located on the hole transport side (or positive electrode side, similarly in this disclosure) or on the hole transport side of the light-absorbing portion has the function of transporting holes, and confirmation of the hole transport function is not required. That is, as long as the solar cell functions as a solar cell, the layer located on the hole transport side of the light-absorbing portion or on the hole transport side of the light-absorbing portion is called the hole transport layer. The hole transport layer may, for example, be composed of a material with a band gap of 2 eV or more and an ionization potential smaller than 5.4 eV (shallow). The hole transport layer may be composed of an inorganic material. The thickness of the hole transport layer can be, for example, between 30 nm and 100 nm. Specific materials that constitute the hole transport layer include oxides and sulfides such as copper oxide (Cu2O), zinc sulfide (ZnS), and nickel oxide. Fine particles of oxides or sulfides may also be used. Organic materials may also be used. Furthermore, the hole transport layer may inhibit electron transport (electron blocking). The hole transport layer may also be accompanied by a separate electron blocking layer. Alternatively, there may be no hole transport layer, and instead, an electron blocking layer may be present.

[0053] The protective wall portion 9 is formed of the same porous material as the insulating layer 6. In other words, the protective wall portion 9 is a porous layer containing voids similar to those of the insulating layer 6, but differs in that a liquid-repellent portion 9c is formed in the voids. Specifically, the protective wall portion 9 is occupied by the third metal oxide 9a that constitutes itself and the voids that are the gaps between the third metal oxide 9a, and the voids (liquid-repellent portion 9c) of the protective wall portion 9 are filled with a liquid-repellent material. As shown in Figure 1, when viewed in cross-section, the protective wall portion 9 is formed on the left and right sides of the outside of the photoelectric conversion layer, in the frame region WR between adjacent photoelectric conversion elements 1. The relationship between the perovskite compound 8 provided in the element region SR and the protective wall portion 9 will be explained in conjunction with the manufacturing method of the photoelectric conversion element 1, which will be described later. Note that the protective wall portion 9 does not exclude materials other than the same porous material as the insulating layer 6. For example, a porous material other than the insulating layer 6 may be used in a part of the protective wall portion 9. As long as the solar cells are functioning as solar cells, the insulation between newly installed elements can be considered to be maintained, and the fact that the solar cells are functioning as solar cells confirms that the barrier section 9 is not impairing the insulation between adjacent elements.

[0054] The liquid-repellent material used in the liquid-repellent portion 9c is preferably a material that repels the perovskite solution 12 (described later), is not affected by the perovskite solution 12, and is not conductive. A preferred example of a liquid-repellent material is a fluorine-based coating agent. Examples of fluorine-based coating agents include compounds derived from fluorine-based silane compounds (also referred to as "fluorine-containing silane compounds"). Compounds derived from fluorine-based silane compounds have high liquid-repellent, antifouling, weather-resistant, and abrasion-resistant properties. Furthermore, considering that fluorine-based silane compounds can be dissolved in non-fluorine-based organic solvents rather than fluorine-based organic solvents, they are also easy to handle. In this way, sufficient liquid repellency can be ensured by using fluorine-based silane compounds.

[0055] The fluorine-based silane compound is a fluorine-containing compound having an alkoxysilyl group. The alkoxysilyl group is not particularly limited as long as it is a group in which 1 to 3 alkoxy groups are bonded to a silicon atom, and examples of the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group.

[0056] As the fluorine-based silane compound, for example, "CF3(CF2) q -O(CF2CF2O) m (CF2) p (CH2) n SiR 1 (3-a) (OR 2 ) a " it is preferable to use a compound represented by general formula (2). In general formula (2), R 1 and R 2 each independently represents a monovalent hydrocarbon group having 1 to 4 carbon atoms, a represents an integer of 2 to 3, p represents an integer of 1 to 2, q represents an integer of 0 to 5, m represents an integer of 1 to 3, n represents an integer of 2 to 4, and p+q+2m+n is an integer of 5 to 14.

[0057] Next, a method for manufacturing the photoelectric conversion element 1 will be described with reference to FIGS. 3 to 8. In FIGS. 3 to 8, hatching is omitted for the sake of visibility of the drawings; however, to make changes during the process easy to understand, hatching is applied to the porous electron transport layer 5, the insulating layer 6, and the barrier portion 9 before firing.

[0058] FIG. 3 is a schematic cross-sectional view showing the step of forming a porous electron transport layer before firing in the method for manufacturing a photoelectric conversion element.

[0059] When fabricating the photoelectric conversion element 1, a laminated substrate is first prepared by appropriately setting the areas for each layer of the photoelectric conversion element 1 using general photolithography or screen printing processes. Specifically, a glass substrate having a fluorine-doped tin oxide film was used for the substrate 2 and the transparent electrode layer 3. Then, a dense titanium oxide layer (dense electron transport layer 4) was formed on the fluorine-doped tin oxide film using a spray pyrolysis method.

[0060] Next, the porous electron transport layer 5 before firing is formed on the dense electron transport layer 4 by depositing a titanium oxide paste, which is a mixture of a first metal oxide 5a and a first binder 5b such as a resin, using methods such as screen printing, die coating, or gravure printing. As described above, the porous electron transport layer 5 before firing is formed in the device region SR, which is a part of the dense electron transport layer 4. After the deposition of the porous electron transport layer 5 before firing, the solvent is removed by drying at a low temperature (low-temperature firing, approximately 120°C).

[0061] Figure 4 is a schematic cross-sectional view showing the process of forming the insulating layer and protective wall portion before firing in the manufacturing method of a photoelectric conversion element.

[0062] The insulating layer 6 before firing is formed on the porous electron transport layer 5 using the same formation method as for the porous electron transport layer 5. This method involves depositing a zirconium dioxide paste, which is a mixture of a second metal oxide 6a and a second binder 6b such as a resin. As described above, the insulating layer 6 before firing is formed on the porous electron transport layer 5 in the element region SR.

[0063] When forming the insulating layer 6 before firing, a pre-firing barrier portion 9 is simultaneously formed in the frame region WR, which is a part of the dense electron transport layer 4. The pre-firing barrier portion 9, like the pre-firing insulating layer 6, is formed from a zirconium dioxide paste, which is a mixture of a third metal oxide 9a and a third binder 9b such as a resin. In other words, the second metal oxide 6a and the third metal oxide 9a are the same metal oxide, and the second binder 6b and the third binder 9b are the same resin. After the deposition of the insulating layer 6 and the barrier portion 9, the solvent is removed by drying at a low temperature (low-temperature firing, approximately 120°C), similar to the porous electron transport layer 5.

[0064] In Figure 4, the film thickness of the porous electron transport layer 5 is shown to be larger to make it more prominent. However, in reality, the film thickness of the porous electron transport layer 5 is smaller than that of the insulating layer 6, and the insulating layer 6 and the barrier layer 9 have the same film thickness (height). Since the barrier layer 9 and the insulating layer 6, which are made of the same porous material, have the same film thickness, the film deposition process for both can be shared, simplifying the process.

[0065] Figure 5 is a schematic cross-sectional view showing the firing process in the manufacturing method of a photoelectric conversion element.

[0066] The firing (high-temperature firing) here is carried out at, for example, 500°C. Through this firing, the first binder 5b, the second binder 6b, and the third binder 9b are removed from the porous electron transport layer 5, the insulating layer 6, and the barrier layer 9, respectively, resulting in porous layers with voids.

[0067] Figure 6 is a schematic cross-sectional view showing the process of forming a second conductive layer in the manufacturing method of a photoelectric conversion element.

[0068] Using the same formation method as for the porous electron transport layer 5, a carbon paste, which is the material for the second conductive layer 7, is deposited on the insulating layer 6. As described above, the second conductive layer 7 is formed on the insulating layer 6 in the device region SR. The carbon paste contains a binder, similar to the porous electron transport layer 5 before firing, and the binder is removed by firing after film formation. As a result, the second conductive layer 7 is formed in a state with voids.

[0069] Figure 7 is a schematic cross-sectional view showing the step of dropping a liquid-repellent material in a method for manufacturing a photoelectric conversion element.

[0070] In the frame region WR, a fluorine-based coating agent (liquid-repellent material 11) is dropped from above the barrier portion 9 and heated and dried to form a liquid-repellent portion 9c in the void of the barrier portion 9. The concentration, viscosity, and amount of the liquid-repellent material 11 to be dropped should be adjusted so that it does not spill out from the barrier portion 9.

[0071] If the liquid-repellent material 11 were to be dropped onto a flat, dense electron transport layer 4 without the barrier portion 9, the liquid-repellent material 11 could not be kept in one place and there is a risk that it would seep into the porous electron transport layer 5 or the insulating layer 6. In contrast, in this embodiment, since the barrier portion 9 with voids is formed, the dropped liquid-repellent material 11 can be allowed to penetrate into the voids of the barrier portion 9 and kept in place so as not to spread to the surrounding area.

[0072] Figure 8 is a schematic cross-sectional view showing the step of dropping a perovskite solution in the manufacturing method of a photoelectric conversion element.

[0073] In the element region SR, a solution containing a perovskite compound or a precursor of a perovskite compound (hereinafter referred to as perovskite solution) is dropped onto the second conductive layer 7 and calcined. In this embodiment, perovskite solution 12 was prepared by mixing and stirring methylamine iodide (1.14 M), lead iodide (1.2 M), 5-aminovaleric acid hydroiodide (0.06 M), and γ-butyrolactone (solvent).

[0074] The dropped perovskite solution 12 gradually seeps in from top to bottom, penetrating the second conductive layer 7, the insulating layer 6, and the porous electron transport layer 5. Since a barrier portion 9 is formed in the frame region WR surrounding the device region SR, the dropped perovskite solution 12 is contained within the device region SR and does not spill out of the frame region WR. Subsequently, firing is performed to evaporate the perovskite solution 12, thereby forming the perovskite compound 8 in the voids of the second conductive layer 7, the insulating layer 6, and the porous electron transport layer 5. In this way, by providing the barrier portion 9, it is possible to prevent the perovskite solution 12 dropped into the porous layer from flowing out of the photoelectric conversion layer. This prevents insufficient formation of the perovskite compound 8 in the voids of the porous layer. Furthermore, since a liquid-repellent portion 9c is formed in the voids of the barrier portion 9, the outflow of the perovskite solution 12 can be prevented more reliably.

[0075] However, if the protective wall portion 9 is excessively high, it may get in the way when forming the second conductive layer 7. For this reason, it is preferable that the protective wall portion 9 be formed to be about the same height as the insulating layer 6, and not excessively higher than the insulating layer 6.

[0076] In this embodiment, a configuration in which the same material as the insulating layer 6 is laminated onto the frame region WR to form the barrier portion 9 has been described, but the invention is not limited to this, and the same material as the porous electron transport layer 5 may be laminated onto the frame region WR. In other words, the same material as the porous electron transport layer 5 and insulating layer 6 before firing is laminated onto the frame region WR, just as in the element region SR. Even when two layers are stacked on the frame region WR, the liquid-repellent portion 9c can be similarly formed by removing the binder by firing to create a porous layer with voids.

[0077] In this embodiment, a configuration is shown in which an element region SR is provided at one location on the substrate 2. However, the embodiment is not limited to this, and multiple element regions SR may be provided on the substrate 2. As shown in Figures 9 and 10, a photoelectric conversion module 100 may be provided in which multiple photoelectric conversion elements 1 are arranged in a row. In this case, adjacent photoelectric conversion elements 1 may share some of the protective wall portions 9. In other words, in the photoelectric conversion module 100, protective wall portions 9 provided at the boundaries between photoelectric conversion elements 1 can be used as protective wall portions 9 corresponding to multiple photoelectric conversion elements 1.

[0078] Furthermore, the embodiments disclosed herein are illustrative in all respects and do not constitute a limiting interpretation. Accordingly, the technical scope of this disclosure is not to be interpreted solely by the embodiments described above, but is defined based on the claims. This includes all modifications within the meaning and scope of equivalents to the claims.

[0079] (Note) (Aspect 1) A first conductive layer and a second conductive layer, A photoelectric conversion layer provided between the first conductive layer and the second conductive layer, A photoelectric conversion element comprising a protective wall portion formed to surround the photoelectric conversion layer at a distance from it, The aforementioned photoelectric conversion layer is The voids contain a porous layer containing a perovskite compound. The porous layer and the barrier portion contain the same porous material. A photoelectric conversion element characterized by the following.

[0080] (Aspect 2) A photoelectric conversion element according to Embodiment 1, The porous layer is A first porous layer containing a perovskite compound in the voids, The voids contain a perovskite compound, and the voids include a second porous layer laminated on top of the first porous layer, The barrier portion contains the same porous material as the second porous layer. A photoelectric conversion element characterized by the following.

[0081] (Aspect 3) A photoelectric conversion element according to embodiment 2, The protective wall portion has the same thickness as the second porous layer. A photoelectric conversion element characterized by the following.

[0082] (Aspect 4) A photoelectric conversion element according to any one of Embodiments 1 to 3, The aforementioned protective wall portion has a liquid-repellent portion formed in the void. A photoelectric conversion element characterized by the following.

[0083] (Appendix 5) A photoelectric conversion element according to Embodiment 4, The aforementioned liquid-repellent portion is formed of a fluorine-based silane compound. A photoelectric conversion element characterized by the following.

[0084] (Aspect 6) A first conductive layer and a second conductive layer, A photoelectric conversion layer provided between the first conductive layer and the second conductive layer, A photoelectric conversion element comprising a protective wall portion formed on the outside of the photoelectric conversion layer when viewed in cross-section, The aforementioned photoelectric conversion layer is The voids contain a porous layer containing a perovskite compound. The porous layer and the barrier portion contain the same porous material. A photoelectric conversion element characterized by the following.

[0085] (Aspect 7) The steps include providing a first conductive layer, a photoelectric conversion layer, and a second conductive layer in order from the substrate, The step includes forming a protective wall portion that is spaced apart from the photoelectric conversion layer and surrounds it, The aforementioned photoelectric conversion layer is The voids contain a porous layer containing a perovskite compound. The porous layer and the barrier portion contain the same porous material. A method for manufacturing a photoelectric conversion element characterized by the following.

[0086] (Pattern 8) A method for manufacturing a photoelectric conversion element according to Embodiment 7, The step includes simultaneously laminating a porous material in the region corresponding to the porous layer and the barrier portion. A method for manufacturing a photoelectric conversion element characterized by the following. [Explanation of Symbols]

[0087] 1. Photoelectric conversion element 2 Base 3 Transparent electrode layer 4 Dense electron transport layer 5 Porous electron transport layer 6. Insulating layer 7. Second conductive layer 8 Perovskite Compounds 9. Barrier section 9c Liquid repellent part 11 Liquid repellent material 12 Perovskite solution SR element region WR border area

Claims

1. A first conductive layer and a second conductive layer, A photoelectric conversion layer provided between the first conductive layer and the second conductive layer, A photoelectric conversion element comprising a protective wall portion formed to surround the photoelectric conversion layer at a distance from it, The aforementioned photoelectric conversion layer is The voids contain a porous layer containing a perovskite compound. The porous layer and the barrier portion contain the same porous material. A photoelectric conversion element characterized by the following.

2. A photoelectric conversion element according to claim 1, The porous layer is A first porous layer containing a perovskite compound in the voids, The voids contain a perovskite compound, and the voids include a second porous layer laminated on top of the first porous layer, The barrier portion contains the same porous material as the second porous layer. A photoelectric conversion element characterized by the following.

3. A photoelectric conversion element according to claim 2, The barrier portion has the same thickness as the second porous layer. A photoelectric conversion element characterized by the following.

4. A photoelectric conversion element according to claim 1, The aforementioned protective wall portion has a liquid-repellent portion formed in the void. A photoelectric conversion element characterized by the following.

5. A photoelectric conversion element according to claim 4, The aforementioned liquid-repellent portion is formed of a fluorine-based silane compound. A photoelectric conversion element characterized by the following.

6. A first conductive layer and a second conductive layer, A photoelectric conversion layer provided between the first conductive layer and the second conductive layer, A photoelectric conversion element comprising a protective wall portion formed on the outside of the photoelectric conversion layer when viewed in cross-section, The aforementioned photoelectric conversion layer is The voids contain a porous layer containing a perovskite compound. The porous layer and the barrier portion contain the same porous material. A photoelectric conversion element characterized by the following.

7. The steps include providing a first conductive layer, a photoelectric conversion layer, and a second conductive layer in order from the substrate, The step includes forming a protective wall portion that is spaced apart from the photoelectric conversion layer and surrounds it, The aforementioned photoelectric conversion layer is The voids contain a porous layer containing a perovskite compound. The porous layer and the barrier portion contain the same porous material. A method for manufacturing a photoelectric conversion element characterized by the following.

8. A method for manufacturing a photoelectric conversion element according to claim 7, The step includes simultaneously laminating a porous material in the region corresponding to the porous layer and the barrier portion. A method for manufacturing a photoelectric conversion element characterized by the following.

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