Method for manufacturing solar battery cell, method for manufacturing solar battery module, solar battery cell, and solar battery module

Abstract

A method for manufacturing a solar battery cell (100) according to the present disclosure is characterized by comprising: a step for forming an electron transport layer (20) on a first electrode (10); a step for forming a light absorption layer (30) including a first perovskite layer on the electron transport layer (20); a step for forming a separator layer (40) on the light absorption layer (30); a step for forming a hole transport layer (50) on the separator layer (40); and a step for forming a second electrode (55) on the separator layer (40). The method is also characterized in that the separator layer (50) includes a spacer material (42).

Description

Method for manufacturing a solar cell, method for manufacturing a solar cell module, solar cell, and solar cell module

[0001] The present disclosure relates to a method for manufacturing a solar cell, a method for manufacturing a solar cell module, a solar cell, and a solar cell module. This application claims priority to Japanese Patent Application No. 2023-137812, filed on August 28, 2023, the contents of which are incorporated herein by reference.

[0002] Solar cells have been disclosed in the past.

[0003] For example, Patent Document 1 discloses a perovskite solar cell including: a first collector; an electron transport layer disposed on the first collector and containing a semiconductor; a light absorbing layer disposed on the electron transport layer and containing a perovskite compound represented by the composition formula ABX3, where A is a monovalent cation, B is a divalent cation, and X is a halogen anion; a hole transport layer disposed on the light absorbing layer and containing a hole transport material, wherein the number of moles C of oxidized sites in the hole transport material and the number of moles D of reduced sites in the hole transport material satisfy the relationship 0.1≦100C / (C+D)≦1.1 (1); and a second collector disposed on the hole transport layer.

[0004] Japanese Patent Application Laid-Open No. 2017-126731

[0005] However, a durability issue is that the hygroscopic dopant in the hole transport material (HTM) causes degradation of the perovskite layer, leading to decomposition of the perovskite structure and the formation of PbI. ２ Heavy deposition can reduce durability and cause contact between the hole transport layer and the electron transport layer, potentially resulting in short circuits in the device, while HTM solvents can damage the light absorption layer, reducing light absorption and resulting in efficiency losses.

[0006] In view of the above problems, the present disclosure provides a method for manufacturing a solar cell, a method for manufacturing a solar cell module, a solar cell, and a solar cell module with improved conversion efficiency and durability.

[0007] In one aspect of the present disclosure, a light-emitting device includes the steps of forming an electron transport layer on a first electrode, forming a light-absorbing layer including a first perovskite layer on the electron transport layer, forming a separator layer on the light-absorbing layer, forming a hole transport layer on the separator layer, and forming a second electrode on the separator layer, wherein the separator layer includes a spacer material.

[0008] Another aspect of the present disclosure is characterized in that solar cells manufactured by the solar cell manufacturing method are integrated and modularized.

[0009] In another aspect of the present disclosure, a light-emitting device includes a first electrode, an electron transport layer formed on the first electrode, a light-absorbing layer formed on the electron transport layer and including a first perovskite layer, a separator layer formed on the light-absorbing layer, a hole transport layer formed on the separator layer, and an electrode formed on the separator layer, wherein the separator layer includes a spacer material.

[0010] Another aspect of the present disclosure is a solar cell module in which solar cells are integrated and modularized, characterized in that the first electrode is a transparent conductive substrate.

[0011] As described above, according to the present disclosure, it is possible to provide a method for manufacturing a solar cell, a method for manufacturing a solar cell module, a solar cell, and a solar cell module with improved conversion efficiency and durability.

[0012] FIG. 1 is a schematic cross-sectional view of a solar cell according to the present disclosure. FIG. 2 is an enlarged cross-sectional view of the periphery of the separator layer shown in FIG. 1. FIG. 3A is a schematic view of a separator layer having a spacer material unevenly distributed in the lower layer of the separator layer. FIG. 3B is an enlarged view of the spacer material shown in FIG. 3A being closely packed. FIG. 4 is a cross-sectional view of a spacer material having a core and an intervening layer formed on the surface of the core. FIG. 5A is a schematic view of a separator layer having a spacer material unevenly distributed in the lower layer of the separator layer, having a core and an intervening layer coating the core. FIG. 5B is an enlarged view of the spacer material shown in FIG. 5A being closely packed. FIG. 6 is an explanatory diagram of the conduction electron band level and the valence band level. FIG. 7 is a schematic cross-sectional view of the solar cell (variant) shown in FIG. 1. FIG. 8 is a schematic cross-sectional view of a solar cell module including a solar cell according to the present disclosure. FIG. 9 is a schematic cross-sectional view of a solar cell module including a solar cell (variant) according to the present disclosure. Fig. 10 is a diagram in which a schematic cross-sectional view of one solar cell included in a solar cell module and an equivalent circuit of the solar cell are superimposed. Fig. 11 is an equivalent circuit of a solar cell module. Fig. 12 is a process diagram of a method for manufacturing a solar cell according to the present disclosure. Fig. 13 is an explanatory diagram of a manufacturing method in which a perovskite compound solution is applied and dried to form a light absorbing layer. Fig. 14 is an explanatory diagram when a second perovskite layer is formed.

[0013] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present disclosure described in the claims, and not all of the configurations described in the embodiments are necessarily essential to the solutions of the present disclosure. In addition, the light incident side will be expressed as the lower side, and the side opposite to the light incident side will be expressed as the upper side.

[0014] 1. Solar Cell Fig. 1 is a schematic cross-sectional view of a solar cell 100 according to the present disclosure. As shown in Fig. 1, the solar cell 100 according to the present disclosure includes a first electrode 10, an electron transport layer 20 formed on the first electrode 10, a light absorbing layer 30 formed on the electron transport layer 20 and including a first perovskite layer, a separator layer 40 formed on the light absorbing layer 30, a hole transport layer 50 formed on the separator layer 40, and an electrode 55 formed on the separator layer 40. The first electrode 10 is in contact with the electron transport layer 20, the electron transport layer 20 is in contact with the light absorbing layer 30, the light absorbing layer 30 is in contact with the separator layer 40, the separator layer 40 is in contact with the hole transport layer 50, and the hole transport layer 50 is in contact with a second electrode 55. Each component is described in detail below. Although the first electrode and the second electrode may be described as electrodes, they do not necessarily have to be the same, and it is acceptable for them to be different from each other.

[0015] [First Electrode] The first electrode 10 is preferably, for example, a transparent conductive substrate. In the present embodiment, the first electrode is described as a transparent conductive substrate, but it does not necessarily have to be a transparent conductive substrate. As shown in FIG. 1 , the transparent conductive substrate 10 includes a transparent substrate 11 and a transparent conductive film 12.

[0016] (Transparent Substrate) The transparent substrate 11 is the base of the solar cell 100 and is the same as or includes the substrate or base material. The transparent substrate 11 is made of a transparent material. The transparent substrate 11 is disposed on the light-receiving side of the solar cell 100. Furthermore, during the manufacturing process of the solar cell 100, the electron transport layer 20, the light absorption layer 30, and the like are laminated on the transparent conductive substrate (first electrode 10). Note that "transparent" means that it transmits light, but does not exclude materials that reflect light even slightly. It is sufficient that it is disposed on the light-receiving side of the solar cell and can transmit light appropriately. This can be considered synonymous with being disposed on the light-receiving side of the solar cell (including the portion where light is incident, the same applies in the present disclosure). Therefore, being disposed at least on the light-receiving side can be considered transparent. In other words, a transparent substrate refers to a substrate disposed on the light-receiving side of the solar cell.

[0017] Examples of materials for the transparent substrate 11 include transparent glass (more specifically, soda-lime glass, alkali-free glass, etc.), and transparent resins such as heat-resistant organic films of polyethylene, polyethylene terephthalate, etc. By using a flexible substrate, the solar cell itself can be made flexible.

[0018] When the material of the transparent substrate 11 is a transparent resin such as an organic film, the solar cell 100 desirably has a barrier layer on the transparent substrate 11. In this way, it is possible to prevent moisture and the like from penetrating into the light absorbing layer 30.

[0019] Unless otherwise specified, the transparent substrate 11 on the light-receiving side is not limited in thickness, but typically has a thickness of about 300 μm to 1500 μm, which reduces the risk of moisture and the like penetrating the light-absorbing layer 30 and reducing the conversion efficiency and durability of the solar cell 100. On the other hand, the second electrode 55 (hereinafter simply the electrode 55) and the hole transport layer 50 on the non-light-receiving side (including a portion that reflects light, the same applies below) are not limited in thickness unless otherwise specified, but typically have a thin thickness of 50 μm to 300 μm, which reduces the risk of moisture and the like penetrating the light-absorbing layer 30 and reducing the conversion efficiency and durability of the solar cell 100 due to structural limitations.

[0020] Therefore, by providing the hybrid hole transport layer 50 of the solar cell 100 according to the present disclosure, the conversion efficiency and durability are prevented from decreasing and are improved, as will be described later.

[0021] (Transparent conductive film) The transparent conductive film 12 is a conductive film on the light-receiving surface side of the solar cell 100. Examples of materials that constitute the transparent conductive film 12 include transparent conductive materials (particularly, transparent conductive oxides (TCOs)) and non-transparent conductive materials. Examples of transparent conductive materials include copper iodide (CuI), indium tin oxide (ITO), and tin oxide (SnO ２Examples of suitable conductive materials include fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), indium zinc oxide (IZO), and gallium-doped zinc oxide (GZO). A non-transparent conductive material refers to a material that, even if its physical properties are non-transparent at a certain thickness, can become transparent depending on the thickness of the material and can therefore be used as a conductive film on the light-receiving surface of a solar cell 100. The term "film" does not specify thickness or width, and includes patterned or island-shaped structures and structures with portions of varying thickness. A film preferably refers to a member with a substantially constant thickness. Unless otherwise specified, "approximately" refers to the degree of manufacturing error, and preferably indicates that a variation of plus or minus 15% of the numerical value is allowed. Note that chemical formulas are representative examples and may refer to the names of compounds (as in the present disclosure). Furthermore, while stoichiometric composition ratios in the chemical formulas are desirable, they do not necessarily have to be stoichiometric (as in the present disclosure).

[0022] [Electron Transport Layer] The electron transport layer 20 is a layer capable of transporting electrons. It has the function of transporting electrons generated by photoexcitation in the perovskite layer (hereinafter referred to as the perovskite compound) contained in the light absorbing layer 30 to the transparent conductive film 12. It is also preferable that the electron transport layer 20 has the function of blocking holes generated by photoexcitation in the perovskite compound. As long as the solar cell 100 has a photoelectric conversion function, it naturally has the electron transport function if it is arranged on the electron transport side of the light absorbing layer or on the electron transport side of the light absorbing layer. As long as the solar cell has a photoelectric conversion function, it can be said to have this function. In other words, the electron transport layer means a layer arranged on the electron transport side of the light absorbing layer or on the electron transport side of the light absorbing layer. The electron transport layer 20 preferably contains a material that easily transfers electrons generated in the perovskite compound to the transparent substrate 11. In the solar cell 100, the electron transport layer 20 can contain titanium oxide. Specifically, the electron transport layer 20 can include a dense titanium oxide layer with a relatively small porosity, a porous titanium oxide layer that is a porous layer with a higher porosity than the dense titanium oxide layer, or both a dense titanium oxide layer and a porous titanium oxide layer. The dense titanium oxide layer can be disposed on the transparent conductive film 12, and the porous titanium oxide layer can be disposed on the dense titanium oxide layer. The term "layer" does not specify thickness or width, and includes patterned or island-shaped structures and structures with varying thicknesses. The term "layer" preferably refers to a member with a substantially uniform thickness. The term "dense" refers to materials that are dense, compact, compact, etc., and includes or are equivalent to these. The term "porous" refers to materials that are porous, porous, mesoporous, etc., and includes or are equivalent to these. The term "porous" refers to materials that can contain a perovskite compound in the voids. The term "dense" refers to materials with extremely small voids. In other words, a dense material refers to materials in which the maximum void width is less than 5 nm when observed cross-sectionally by SEM. In the present disclosure, unless otherwise stated, SEM observation is sufficient as long as observation and confirmation are performed on a cross-sectional SEM image with a width of 400 nm.For example, if the maximum width of the voids in a single 400 nm wide cross-sectional SEM image is less than 5 nm, the layer can be said to be dense.

[0023] Preferably, the dense material is one that can suppress the penetration of the perovskite compound and is free of the perovskite compound on one side of the thickness direction of the dense material. More preferably, the dense material means one that cannot contain the perovskite compound in voids or one that does not have a portion where the perovskite compound is continuously present throughout the thickness of the dense material. That is, if the dense material cannot be confirmed at the maximum void width, it is sufficient that observation by SEM or EDX shows that there is no portion where the perovskite compound is present throughout the layer thickness. In the present disclosure, unless otherwise stated, SEM observation can be performed on a 400 nm wide cross-sectional SEM (or EDX) image and confirmed. For example, if there is no portion where the perovskite compound is present throughout the layer thickness in a single 400 nm wide cross-sectional SEM or EDX observation, the layer can be said to be dense. In addition, the definition of dense material as being one in which the voids are extremely small as described above takes precedence, and if this cannot be confirmed, the above preferred definition can be applied, and if this still cannot be confirmed, the above even more preferred definition can be applied.

[0024] The dense titanium oxide layer and porous titanium oxide layer that make up the electron transport layer 20 will be described below. While titanium oxide will be used as an example, the material is not limited as long as it is disposed on the electron transport side within the light absorption layer of the solar cell 100 or on the electron transport side of the light absorption layer, and it is not necessary to confirm that it naturally has the function. Examples include inorganic oxides such as zinc oxide, indium oxide, tin oxide, aluminum oxide, and gallium oxide, typically N-type inorganic oxides, and inorganic sulfides such as tin sulfide, indium sulfide, and zinc sulfide, typically N-type inorganic sulfides.

[0025] (Dense Titanium Oxide Layer) The dense titanium oxide layer has a low porosity, and therefore, during the manufacture of the solar cell 100, the perovskite compound-containing coating liquid used to form the light absorbing layer 30 does not easily penetrate into the layer. Therefore, when the solar cell 100 includes a dense titanium oxide layer, contact between the perovskite compound and the transparent conductive film 12 is suppressed. Furthermore, when the solar cell 100 includes a dense titanium oxide layer, contact between the perovskite compound and the transparent conductive film 12 can be suppressed. The film thickness of the dense titanium oxide layer is preferably 5 nm or more and 200 nm or less, and more preferably 10 nm or more and 100 nm or less. Furthermore, the filling rate in terms of mass is desirably 90% or more.

[0026] (Porous Titanium Oxide Layer) The porous titanium oxide layer has a high porosity, and therefore the perovskite compound-containing coating liquid used to form the light absorbing layer 30 during the production of the solar cell 100 can easily penetrate into the pores within the layer. Therefore, by providing the solar cell 100 with a porous titanium oxide layer, it is possible to increase the contact area between the perovskite compound, in other words, the light absorbing layer 30, and the electron transport layer 20. This allows electrons generated by photoexcitation in the perovskite compound to be efficiently transferred to the hole blocking layer 4, and holes to be blocked.

[0027] [Light Absorbing Layer] The light absorbing layer 30 is a layer capable of absorbing light. The light absorbing layer 30 contains a perovskite compound that is a first perovskite layer. The perovskite compound contained in the first perovskite layer is sometimes referred to as the first perovskite compound. The thickness of the light absorbing layer 30 is preferably 500 nm or more and 2 μm or less, and more preferably 700 nm or more and 800 nm or less.

[0028] The perovskite compound contained in the light-absorbing layer 30 is composed of a compound represented by the general formula: ABX3 (1). While the composition ratio of each element is preferably 1:1:3, it does not necessarily have to be 1:1:3. The content of each element may vary as appropriate, and each element does not necessarily have to be a single type. As long as the light-absorbing layer has photoelectric conversion function, the degree of freedom in the configuration described above is maintained. In general formula (1), A represents an organic molecule (including an organic group or organic cation, as defined in the present disclosure) or an inorganic atom or molecule (including an inorganic group or inorganic cation, as defined in the present disclosure) or a combination thereof; B represents a metal atom or molecule (including a metal cation, as defined in the present disclosure); and X represents a halogen atom or molecule or a chalcogen atom or molecule (including a halogen anion or chalcogen anion, as defined in the present disclosure). In general formula (1), the three Xs may be the same or different from one another. As long as a solar cell has a photoelectric conversion function, the perovskite compound has the function of absorbing light and converting it into electricity by being contained in a light absorption layer, and this fact should also be taken into consideration. That is, as long as a solar cell has a photoelectric conversion function, it is possible to confirm that it is a perovskite compound, for example, by detecting organic molecules, metal atoms, and halogen atoms. Furthermore, as long as a solar cell has a photoelectric conversion function, it is possible to confirm that it is a perovskite compound, for example, by detecting elements corresponding to A, B, and X. For example, molecules containing carbon, nitrogen, and hydrogen are suitable as organic molecules, and therefore, it is possible to detect carbon, nitrogen, hydrogen, metal elements, and halogen or chalcogen elements. Alternatively, as long as a solar cell has a photoelectric conversion function, it is possible to confirm that it is a perovskite compound, for example, by detecting inorganic atoms, metal atoms, and halogen atoms. Furthermore, as long as a solar cell has a photoelectric conversion function, it is possible to confirm that it is a perovskite compound, for example, by detecting elements corresponding to A, B, and X. For example, cesium or rubidium is suitable as the inorganic atom, and therefore, it is sufficient if cesium or rubidium, a metal element, and a halogen or chalcogen are detected.Furthermore, the fact that the light absorbing layer 30 is a perovskite compound does not necessarily mean that it has a crystalline structure, since it is a natural consequence that the light absorbing layer must have a crystalline structure in order to have a photoelectric conversion function.The light absorbing layer 30 may contain compounds other than perovskite compounds.

[0029] The light-absorbing layer 30 may contain an organic-inorganic hybrid compound. An organic-inorganic hybrid compound refers to a compound containing both inorganic and organic elements. Solar cells using perovskite compounds, which are organic-inorganic hybrid compounds, are also called organic-inorganic hybrid solar cells. "Organic" typically refers to a material composed of multiple carbon atoms. Note that graphite, graphene, carbon nanowires, carbon nanofibers, carbon nanotubes, and carbon materials such as carbon and carbon black that function as electrodes are not considered organic. In other words, organic refers to a material that contains multiple carbon atoms as one of its constituent elements, excluding carbon materials such as graphite. "Inorganic" refers to a material that is not organic. In other words, an organic-inorganic hybrid compound refers to a material that contains multiple carbon atoms as one of its constituent elements, but also contains no carbon atoms, such as metal atoms, halogen atoms, or chalcogen atoms.

[0030] In general formula (1), examples of the organic molecule represented by A include alkylamine, alkylammonium, and nitrogen-containing heterocyclic compounds. In the perovskite compound (1), the organic molecule represented by A may be only one type of organic molecule, or may be two or more types of organic molecules.

[0031] 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.

[0032] The alkylammonium is an ionized product of the alkylamine. Examples of the alkylammonium 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.

[0033] Examples of the nitrogen-containing heterocyclic compound include imidazole, azole, pyrrole, aziridine, azirine, azetidine, azeto, azole, imidazoline, and carbazole. The nitrogen-containing heterocyclic compound may be an ionized compound. As the ionized nitrogen-containing heterocyclic compound, phenethylammonium is preferred.

[0034] 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.

[0035] In general formula (1), examples of the metal atom 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 the perovskite compound, the metal atom represented by B may be only one type of metal atom, or may be two or more types of metal atoms. From the viewpoint of improving the light absorption properties and charge generation properties of the perovskite compound, the metal atom represented by B is preferably a lead atom or a tin atom. From the viewpoint of reducing lead, a tin atom is preferred.

[0036] In general formula (1), examples of halogen atoms represented by X include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, and examples of chalcogen atoms include oxygen atoms, sulfur atoms, selenium atoms, and tellurium atoms. In the perovskite compound, the halogen atoms or chalcogen atoms represented by X may be one type or two or more types. As the halogen atom represented by X, an iodine atom is preferred from the viewpoint of enabling the perovskite compound to utilize light in a wide wavelength range. Specifically, of the three Xs, it is preferred that at least one X represents an iodine atom, and it is more preferred that all three Xs represent iodine atoms.

[0037] The perovskite compound may be a compound represented by the general formula "CH ３ NH ３ PbX ３ (wherein X represents a halogen atom)" is preferred, and ３ NH３ PbI ３ As the perovskite compound, the general formula "CH ３ NH ３ PbX ３ " (particularly, compounds represented by CH ３ NH ３ PbI ３ By using the above-mentioned compound, electrons and holes can be generated more efficiently in the perovskite compound, and as a result, the photoelectric conversion efficiency of the solar cell 100 can be further improved.

[0038] The first perovskite layer contains a perovskite material whose valence band upper edge level is in the range of −5.1 eV to −5.7 eV and whose conduction band lower edge level is in the range of −3.5 eV to −4.0 eV.

[0039] [Separator Layer] The separator layer 40 is characterized by including a spacer material 42. The spacer material 42 is, for example, an inorganic material. Examples of the spacer material include silica, alumina, titanium oxide, zirconia, nickel oxide, and Cu. ２ Preferably, the material contains at least one of silica, nickel oxide, or CuO. ２ The spacer material is preferably O. Examples of the spacer material include filler particles. The filler particles are, for example, inorganic material particles. Examples of the filler particles include silica particles, alumina particles, titanium oxide particles, zirconia particles, nickel oxide particles, Cu ２ Preferably, the composite material contains at least one of silica particles, nickel oxide particles, or CuO particles. ２O particles are more preferred. The spacer material is preferably an inorganic chalcogenide. Furthermore, an inorganic oxide is more preferred. By being an oxide, the reactivity of, for example, a metal material or a semiconductor material is reduced, resulting in a highly stable material. Note that the particles are not limited to a spherical three-dimensional shape (circular cross-sectional shape). For example, the particles may have a polygonal cross-sectional shape, a rod-like three-dimensional shape, a branch-like three-dimensional shape, or a three-dimensional shape with an uneven surface, or a combination thereof. The particles are preferably nanoparticles. Nanoparticles mean that the minimum width of the part is less than 100 nm. Furthermore, it is desirable for the nanoparticles to have a size of 50 nm or less.

[0040] The spacer material 42 may be dense or porous, and as shown in Fig. 2, it can prevent moisture, oxygen, and the like from penetrating into the light absorption layer 30 from the electrode 55 side, thereby improving the conversion efficiency and durability.

[0041] The separator layer 40 can transport holes generated in the light-absorbing layer 30 of the first perovskite layer or the second perovskite layer 41 to the hole-transport layer 50. Furthermore, it is even better if the separator layer 40 can block electrons generated in the light-absorbing layer 30 of the first perovskite layer. For this reason, it is preferable that the second perovskite layer 41 uses a perovskite material that easily transfers holes generated in the first perovskite layer to the hole-transport layer 50. In the solar cell 100, the separator layer 40 contains a layer in which a spacer material 42 is distributed and the second perovskite layer 41. Note that the perovskite compound contained in the second perovskite layer is sometimes referred to as the second perovskite compound. Furthermore, this does not exclude the first perovskite compound and the second perovskite compound being the same material.

[0042] FIG. 3A is a schematic diagram of a separator layer 40 in which a spacer material 42 is unevenly distributed in the lower layer of the separator layer 40. FIG. 3B is an enlarged view of the spacer material 42 shown in FIG. 3A in a closely packed state. As shown in FIGS. 3A and 3B, the separator layer 40 has a composite structure including an inorganic filler and a second perovskite layer 41. The spacer material 42 is closely packed. In this manner, the inorganic filler prevents the intrusion of moisture, oxygen, and the like, and the second perovskite layer 41 can further improve the conversion efficiency. Furthermore, forming the inorganic filler after forming the first perovskite layer has the effect of preventing significant damage to the film surface and crystals of the first perovskite layer. The second perovskite layer 41 can be made of the same or a different perovskite material as the first perovskite layer, which can adjust the energy levels, facilitate the transport of holes and electrons, and generate more electrons and holes.

[0043] Furthermore, the second perovskite layer 41 and the first perovskite layer are in contact with each other. In this way, holes generated from the light absorbing layer 30 can migrate and be injected into the hole transport layer 50. The use of the separator layer 40 containing the spacer material 42 provides better resistance to moisture intrusion and durability against device degradation than conventional single-layer photoactive layers, and the inclusion of the second perovskite layer 41 generates more holes than a single light absorbing layer.

[0044] By forming the separator layer 40 containing the spacer material 42, physical contact between the light absorbing layer 30 and the hole transport layer 50 is suppressed, and short circuits within the element are prevented.

[0045] Furthermore, although the spacer material 42 is unevenly distributed in the second perovskite layer 41, it may also be formed on the lower light absorbing layer 30 side, as shown in FIGS. 3A and 3B.

[0046] The thickness of the spacer material 42 is preferably 10 to 100 nm. If the thickness is less than 10 nm, the manufacturing cost may increase. On the other hand, if the thickness is more than 100 nm, the risk of moisture penetration is reduced, but the inorganic layer becomes thicker and the electrical resistance of the solar cell 100 may increase.

[0047] FIG. 4 is a cross-sectional view of a spacer material 42 having a core 43 and an intervening layer 44 formed on the core 43. As shown in FIG. 4, the spacer material 42 may have a core 43 and an intervening layer 44 formed on the core 43. It is preferable that the intervening layer 44 of the spacer material 42 covers the core 43. The core 43 can be the spacer material 42 described above. The intervening layer 44 may contain a perovskite compound, and may contain a compound that is the same as or different from the perovskite compound contained in the first perovskite layer and the second perovskite layer 41 described above. The intervening layer 44 may also be an electron blocking material. The electron blocking material is a material that blocks electrons generated in the perovskite compound and transports holes generated in the perovskite compound to the electron blocking layer. An example of the electron blocking material is Cu. ２ O, NiO, etc.

[0048] The thickness of the intervening layer 44 can be set to 5 nm or more and 20 nm or less. By using such a spacer material 42, it is possible to block the transfer of conduction electrons generated in the perovskite compound to the electrode 55, and it is also possible to efficiently propagate holes generated in the perovskite compound to the electrode 55.

[0049] This makes it possible to achieve high photoelectric conversion efficiency in the solar cell 100. Furthermore, the contact interface between the perovskite compound and the hole blocking material can be widened, allowing holes generated in the perovskite compound to efficiently propagate to the electrode 55. As a result, the conduction electrons and holes generated in the perovskite compound can be efficiently separated, and the photoelectric conversion efficiency of the solar cell 100 can be improved.

[0050] The spacer material 42 shown in Fig. 4 can be produced by an RF thermal plasma method, etc. The spacer material 42 shown in Fig. 4 can also be produced by preparing organic filler particles such as organic polystyrene, cellulose, polyacrylic acid, etc. by suspension polymerization, adjusting the pH of a solution in which the prepared organic filler is dispersed, and coating the surface of the organic filler with inorganic nanoparticles.

[0051] The average particle diameter D50 of the spacer material 42 contained in the separator layer 40 is preferably 10 nm or more and 50 nm or less, and more preferably 10 nm or more and 30 nm or less. This allows the spacer material 42 to be unevenly distributed on the surface when the perovskite compound is coated and dried, and allows the spacer material 42 to form a closely packed structure. This improves the durability of the perovskite compound against the penetration of water molecules. The average particle diameter D50 of the spacer material 42 is, for example, the average particle diameter obtained by averaging the particle diameter of 20 adjacent particles or the maximum number of particles observable in a cross-sectional image of a width of 400 nm using cross-sectional observation, whichever is smaller. Furthermore, the particle diameter can be defined as the diameter of a circle having an area equivalent to the cross-sectional area of ​​the inorganic substance in the cross-sectional image.

[0052] The separator layer 40 may be a layer in which the spacer material 42 accounts for 20 wt % or more. Furthermore, the separator layer 40 is preferably a region in which 50 wt % or more of the spacer material 42 is unevenly distributed, more preferably a region in which 70 wt % or more of the spacer material 42 is unevenly distributed, and even more preferably a region in which 90 wt % or more of the spacer material 42 is unevenly distributed. This provides a significant light reflection effect. Furthermore, in the separator layer 40, a perovskite compound is present between the particles of the spacer material 42.

[0053] Fig. 5A is a schematic diagram of a separator layer 40 in which a spacer material 42 having a core 43 and an intervening layer 44 coating the core 43 is unevenly distributed in the lower layer of the separator layer 40. Fig. 5B is an enlarged view of the spacer material 42 shown in Fig. 5A being closely packed. The separator layer 40 shown in Figs. 5A and 5B is a layer having a structure in which the spacer material 42 shown in Fig. 4 having a core 43 and an intervening layer 44 coating the core 43 is closely packed. As shown in Figs. 5A and 5B, the separator layer 40 has a structure in which the spacer material 42 having the intervening layer 44 is closely packed (face-centered cubic arrangement), which makes it possible to block electrons generated in the perovskite compound from propagating to the electrode 55 and to efficiently propagate holes generated in the perovskite compound to the electrode 55.

[0054] 6 is a diagram illustrating the conduction band level and the valence band level. ２ or Al ２ O ３ and preferably has a band gap wider than 5.0 eV. By having a band gap wider than 5.0 eV, the band gap between the perovskite compound and the organic material contained in the second perovskite layer 41 becomes approximately 2 to 4 eV, and by using a material with a band gap wider than this, it is possible to suppress recombination of holes transported from PVK1 to PVK2 with electrons generated in PVK1. In addition, it is possible to suppress recombination of holes generated in PVK1 with electrons transported from PVK2 to PVK1.

[0055] The second perovskite layer 41 preferably has the same or deeper conduction band level as the hole transport layer 50, and the same or deeper valence band level as the hole transport layer 50. This increases the hole extraction efficiency and promotes FF recombination. Furthermore, the separator layer 40 containing the spacer material 42 smoothly connects the valence band energy levels of the hole transport layer 50, improving hole extraction efficiency. The separator layer 40 has a shallower conduction band level than the light absorption layer 30, improving electron transport efficiency.

[0056] The second perovskite layer 41 preferably has a conduction band level that is the same as or shallower than that of the light absorbing layer 30, and a valence band level that is the same as or shallower than that of the light absorbing layer 30. This increases the hole extraction efficiency. It also has the effect of gently joining the valence band energy levels of the light absorbing layer 30 and the separator layer 40, improving the hole extraction efficiency. The separator layer 40 has a conduction band level that is shallower than that of the light absorbing layer 30, which has the effect of improving the electron transport efficiency.

[0057] [Hole Transport Layer] The hole transport layer 50 has the function of transporting holes generated in the light absorption layer 30. It is preferable that the hole transport layer 50 also has the function of blocking electrons generated in the light absorption layer 30. As long as the solar cell 100 has a photoelectric conversion function, it naturally has a hole transport function if it is disposed on the hole transport side of the light absorption layer or on the hole transport side of the light absorption layer, and there is no need to confirm this function. In other words, the hole transport layer means a layer disposed on the hole transport side of the light absorption layer or on the hole transport side of the light absorption layer. The material constituting the hole transport layer 50 is preferably a material whose conduction band minimum energy level (Eebc) is equal to or greater than Eopc + 0.5 eV, relative to the conduction band minimum energy level (Eopc) of the perovskite compound.

[0058] Specific examples of the material of the hole transport layer 50 include Cu. ２ Examples of the inorganic compounds include O, NiO, ZnS, etc. This makes it possible to efficiently block electrons generated by photoexcitation in the perovskite compound, thereby realizing a highly efficient solar cell 100.

[0059] Furthermore, the hole transport layer 50 is preferably disposed adjacent to the second perovskite layer 41. The thickness of the hole transport layer 50 is preferably 50 nm or more and 100 nm or less, and more preferably 70 nm or more and 80 nm or less. This makes it possible to efficiently block electrons from propagating toward the electrode 55, while allowing holes to propagate toward the electrode 55 efficiently. As a result, high efficiency of the solar cell 100 can be achieved.

[0060] [Electrode] The electrode 55 is either a counter electrode on the non-light-receiving side of the solar cell 100 or on the side opposite the light-receiving side, or a transparent electrode on the light-receiving side, which is also a light-receiving surface that is transparent to incident light like a transparent conductive film. When used as a counter electrode, it is preferable that it has a function of reflecting light as a reflective electrode, but it does not necessarily have to have a reflective function. Examples of materials that constitute the electrode 55 include metals, transparent conductive inorganic materials, conductive fine particles, and conductive polymers (particularly transparent conductive polymers). Examples of metals include nickel, gold, silver, and platinum. Examples of transparent conductive inorganic materials include copper iodide (CuI), indium tin oxide (ITO), and tin oxide (SnO ２ Examples of conductive fine particles include silver nanowires and carbon nanofibers. Examples of transparent conductive polymers include a polymer (PEDOT / PSS) containing poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid. The electrode 50 may also be made of a carbon material such as graphite. While it is desirable to provide an electrode and a hole transport layer or an electron transport layer, it is not necessary for all of them to be provided. As long as the solar cell 100 has a photoelectric conversion function, it is acceptable for one of them to be omitted.

[0061] In order to efficiently apply a built-in potential to the light absorption layer 30, it is desirable that the material of the electrode 55 be a metal having a work function Φ≧5.0 eV. This results in a structure in which electrons are extracted from the transparent conductive film 12 on the transparent substrate 11 side and holes are extracted from the electrode 55 side, and a smooth flow of holes can be achieved at the interface between the hole transport layer 50 on the hole extraction side and the electrode 55, resulting in a highly efficient solar cell 100.

[0062] Figure 7 is a schematic cross-sectional view of a solar cell 110 that is a modification of the solar cell 100 shown in Figure 1. As shown in Figure 7, the solar cell 110 of the modification includes a first electrode, a hole transport layer formed on the first electrode, a light absorbing layer formed on the hole transport layer and including a first perovskite layer, a separator layer formed on the light absorbing layer, an electron transport layer formed on the separator layer, and an electrode formed on the electron transport layer. Because the solar cell 110 of the modification has the separator layer, it is possible to improve conversion efficiency and durability.

[0063] The first electrode, hole transport layer, light absorbing layer, separator layer, electron transport layer, and electrode are as described above. The components of the solar cell 110 of the modified example do not need to be the same as the components of the solar cell 100 described above, but they may be the same. The CBM of the second perovskite layer is preferably deeper than the CBM of the light absorbing layer 30. The CBM of the hole transport layer 50 is preferably shallower than the CBM of the light absorbing layer 30. The CBM of the second perovskite layer is preferably shallower than the CBM of the electron transport layer 20. The VBM of the second perovskite layer is preferably deeper than the VBM of the light absorbing layer 30. The VBM of the second perovskite layer is preferably shallower than the VBM of the electron transport layer 20. The VBM of the second perovskite layer is preferably shallower than the VBM of the electron transport layer 20. The VBM of the hole transport layer 50 is preferably shallower than the VBM of the light absorbing layer 30. It is desirable that the CBM deepens in the order of the hole transport layer 50, the light absorption layer, the separator layer, and the electron transport layer.It is also desirable that the VBM deepens in the order of the hole transport layer 50, the light absorption layer, the separator layer, and the electron transport layer.

[0064] In this disclosure, the conduction band minimum may be referred to as CBM, and the valence band maximum may be referred to as VBM. For example, "deep" with respect to CBM or VBM means that "the corresponding electron affinity or ionization energy is large or far from the vacuum level," and "shallow" with respect to CBM or VBM means that "the corresponding electron affinity or ionization energy is small or close to the vacuum level." Here, the absolute value of the difference between the vacuum level and the conduction band minimum (CBM) can be rephrased as (the absolute value of) the electron affinity, and the absolute value of the difference between the vacuum level and the valence band maximum (VBM) can be rephrased as (the absolute value of) the ionization potential.

[0065] As described above, the solar cell 100 according to the present disclosure can improve conversion efficiency and durability.

[0066] 2. Solar Cell Module Fig. 8 is a schematic cross-sectional view of a solar cell module 1000 (series-connected solar cells) including solar cell 100 according to the present disclosure. As shown in Fig. 8, solar cell module 1000 according to the present disclosure is produced by integrating solar cell 100 described above.

[0067] 8 , a solar cell module 1000 according to the present disclosure includes a transparent substrate 11, a transparent conductive film 12 provided on the transparent substrate 11, an electron transport layer 20 provided on the transparent conductive film 12, a light absorbing layer 30 provided on the electron transport layer 20, a separator layer 40 provided on the light absorbing layer 30, a hole transport layer 50 provided on the separator layer 40, an electrode 55 provided on the hole transport layer 50, a second barrier layer 62 provided on the electrode 55, and a back substrate 64 provided on the second barrier layer 62. The solar cell module 1000 shown in FIG. 8 is a solar cell module 1000 in which the transparent substrate 11 is transparent glass.

[0068] FIG. 9 is a schematic cross-sectional view of a solar cell module 1100 including a modified solar cell 100 according to the present disclosure. This solar cell module has a transparent substrate 11 made of a transparent resin such as an organic film. As shown in FIG. 9 , the solar cell module 1100 according to the present disclosure includes a transparent substrate 11, a first barrier layer 61 provided on the transparent substrate 11, a transparent conductive film 12 provided on the first barrier layer 61, an electron transport layer 20 provided on the transparent conductive film 12, a light absorbing layer 30 provided on the electron transport layer 20, a separator layer 40 provided on the light absorbing layer 30, a hole transport layer 50 provided on the separator layer 40, an electrode 55 provided on the hole transport layer 50, a second barrier layer 62 provided on the electrode 55, a third barrier layer 63 provided on the second barrier layer 62, and a back substrate 64 provided on the third barrier layer 63. The first barrier layer 61 is a layer made of a material with high gas barrier properties. The second barrier layer 62 is a dense inorganic material layer, and the third barrier layer 63 is a layer made of a material with high gas barrier properties.

[0069] 9 , the second barrier layer 62 is provided so as to cover the side portions of the hole transport layer 50 and the electrode 55, and also to cover the upper portion of the electrode 55. The second barrier layer 62 covers the upper surface and side surfaces of each solar cell 100.

[0070] 8 and 9 , the hole transport layer 50 covers the top of the light absorbing layer 30 and the sides of the light absorbing layer 30 and the separator layer 40. The electrode 55 covers the top and one side of the hole transport layer 50. The electrode 55 extends from the top to the side of the hole transport layer 50 and is connected to the top of the transparent conductive film 12 of an adjacent solar cell 100, and in this way, the adjacent solar cell 100 is connected in series.

[0071] The solar cell modules 1000, 1100 of the present disclosure include a plurality of solar cells 100, a first terminal 71, and a second terminal 72. The plurality of solar cells 100 are connected in series, and the solar cell 100 at one end of the plurality of solar cells 100 connected in series is connected to the first terminal 71, and the solar cell 100 at the other end is connected to the second terminal 72. There is no particular limitation on the number of solar cells 100 connected in series, as long as there is more than one.

[0072] The transparent substrate 11 is the substrate of the solar cell modules 1000 and 1100. The transparent substrate 11 may be a glass substrate as shown in Fig. 8 or a transparent organic film as shown in Fig. 9. This allows light to enter the interior of the solar cell 100. When the transparent substrate 11 is a flexible organic film, the solar cell module 1100 becomes a flexible solar cell module.

[0073] Specific examples of materials for the organic film that will become the transparent substrate 11 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 satisfy the requirements. The thickness of the organic film that will become the transparent substrate 11 is preferably 50 to 100 μm.

[0074] When the transparent substrate 11 is a transparent organic film, a first barrier layer 61 may be provided on one of the +Y-direction major surfaces of the transparent substrate 11. The first barrier layer 61 is a layer made of a material with high gas barrier properties. This prevents internal deterioration of the solar cell 100 due to moisture and oxygen in the air. The first barrier layer 61 is also a layer made of an insulating material. This prevents leakage current. The film thickness of the first barrier layer 61 can be several tens to 100 nm. This allows the first barrier layer 61 to have light-transmitting properties. Furthermore, the solar cell 100 and the solar cell module 1100 can have flexibility. Specific examples of materials for the first barrier layer 61 include silicon oxide and aluminum oxide. As long as the first barrier layer 61 has gas barrier properties, insulating properties, and light-transmitting properties, other oxides and insulators can also be used as the material for the first barrier layer 61. Main methods for forming the first barrier layer 61 include sputtering and vacuum deposition.

[0075] The transparent conductive film 12 is provided on the transparent substrate 11 (or on the first barrier layer 61) and serves as an electrode 55 for extracting current generated by photovoltaic power of the solar cell 100. The transparent conductive film 12 is made of a conductive transparent material such as aluminum-doped zinc oxide (AZO), indium zinc oxide (IZO), gallium-doped zinc oxide (GZO), fluorine-doped tin oxide (FTO), or indium tin oxide (ITO). The sheet resistance of the transparent conductive film 12 is preferably 10 Ω / sq or less, and the light transmittance of the transparent conductive film 12 is preferably 30% or more. Examples of methods for forming the transparent conductive film 12 include sputtering and vacuum deposition.

[0076] When a plurality of solar cells 100 are provided on the transparent substrate 11, the transparent conductive film 12 formed on the transparent substrate 11 is divided for each solar cell 100. For example, the solar cell modules 1000 and 1100 shown in FIGS. 8 and 9 include five solar cells 100, and therefore the transparent conductive film 12 is divided into five transparent conductive films 12. The groove O separating two adjacent transparent conductive films 12 may be filled with a light absorbing layer 30 or the like. The transparent conductive film 12 spans two solar cells 100. That is, as shown in FIGS. 8 and 9, an electron transport layer 20 is formed on one transparent conductive film 12, and a light absorbing layer 30 is formed on the other transparent conductive film 12.

[0077] The transparent substrate 11 is formed with a first terminal 71 of the solar cell module 1000, 1100, with a portion of the first terminal 71 penetrating the transparent substrate 11 (and the first barrier layer 61) and in contact with or electrically connected to the transparent conductive film 12 of the solar cell 100 connected in series. This first terminal 71 can be used to extract current generated by the photovoltaic power of the solar cell module 1000, 1100. Examples of materials for the first terminal 71 include SnZn-based solder paste. Other conductive pastes and materials for the electrode 55 can also be used as long as they meet the requirements.

[0078] For example, a porous titanium oxide layer of TiO is formed on the transparent conductive film 12 as a seed layer to be the electron transport layer 20. ２ The surface of the TiO ２ A TiN (NaCl structure) layer with a thickness of 5 to 30 nm is formed on the surface of TiO ２ The lattice constants of TiN (rutile structure) and TiO (NaCl structure) are relatively well matched. ２ TiO ２ A good interface with few defects is formed between the TiN layer and the TiN layer. ２ The formation of -xNx allows the lattice constant to change continuously, suppressing the occurrence of interface defects. When the TiN layer is exposed to the atmosphere after surface modification treatment using nitrogen plasma, a re-oxidation layer of several nanometers thick is formed on the surface. ２Since the layer is thin, structural relaxation of the lattice constant does not occur, and the lattice constant of the underlying TiN layer is maintained.

[0079] After the transparent conductive film 12 is formed on the transparent substrate 11, incisions (L1) are made in the transparent conductive film 12 by laser scribing in order to separate and form the solar cell 100 on the transparent substrate 11. The wavelength of the laser used is preferably in the infrared region. The incisions (L1) are made in the transparent conductive film 12, and the transparent conductive film 12 having the incisions is formed. No incisions are made in the transparent substrate 11 or the first barrier layer 61. For example, a perovskite compound can be formed on the transparent substrate 11 and the transparent conductive film 12 in which the incisions (L1) have been made by laser scribing, to form the light absorbing layer 30.

[0080] Perovskite compounds have a tetragonal basic unit cell, which, as mentioned above, has an organic molecule or organic-inorganic mixed molecule A located at each vertex, a metal atom B located at the body center, and a halogen atom X located at each face center, and is represented by the general formula ABX ３ It consists of:

[0081] Examples of organic solvents (contained in the coating liquid) used in the coating method for forming the light absorbing layer 30 include aromatic hydrocarbons such as toluene, xylene, mesitylene, tetralin, diphenylmethane, dimethoxybenzene, and dichlorobenzene; halogenated hydrocarbons such as dichloromethane, dichloroethane, and tetrachloropropane; ethers such as tetrahydrofuran (THF), dioxane, dibenzyl ether, dimethoxymethyl ether, and 1,2-dimethoxyethane; ketones such as methyl ethyl ketone, cyclohexanone, acetophenone, and isophorone; esters such as methyl benzoate, ethyl acetate, and butyl acetate; sulfur-containing solvents such as diphenyl sulfide; fluorine-based solvents such as hexafluoroisopropanol; aprotic polar solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide; alcohols such as methanol, ethanol, and isopropanol; and glyme-based solvents such as ethylene glycol and diethylene glycol monomethyl ether. These can be used alone or as a mixed solvent. These solvents may contain water. Among these solvents, non-halogen organic solvents are preferably used in consideration of the global environment.

[0082] In addition, the coating liquid may contain additives such as an antioxidant, a viscoelasticity modifier, a preservative, a curing catalyst, etc. The coating method is not particularly limited, but preferred methods include, for example, a dip coating method, a spray coating method, and a slide hopper coating method.

[0083] After the light absorbing layer 30 is formed, a cut (L2) is made in a part of the light absorbing layer 30 by laser scribing in order to connect the transparent conductive film 12 of one of the two adjacent solar cell 100 to the hole transport layer 50 and electrode 55 of the other solar cell 100. The wavelength of the laser used is preferably in the visible light region. For example, the cut (L2) is made in the light absorbing layer 30, and the light absorbing layer 30 is formed. This laser scribing removes the light absorbing layer 30, but does not remove the transparent conductive film 12 (and the first barrier layer 61).

[0084] Thereafter, the separator layer 40 and the hole transport layer 50 are formed, and the electrode 55 is formed.

[0085] The electrode 55 is provided on the light absorbing layer 30 and serves to extract the current generated by the photovoltaic power of the light absorbing layer 30 of the solar cell 100. The electrode 55 is, for example, a metal film with a work function of 5 eV or more. When the electrode 55 is made of a metal with a deep work function (5 eV or more), a bending of the band structure occurs at the interface between the light absorbing layer 30 and the electrode 55, which allows for a smooth flow of holes. Examples of materials for the electrode 55 include metals such as Ni, Pt, and Pd. The film thickness of the electrode 55 is preferably 50 nm to 150 nm. The light absorbing layer 30 or the electrode 55 can be formed by a sputtering method, a vacuum deposition method, or the like.

[0086] After the electrode 55 is formed, a cut (L3) is made in a portion of the separator layer 40, the hole transport layer 50, and the electrode 55 by laser scribing to form a series-connected circuit of adjacent solar cells 100 on the transparent substrate 11. Furthermore, to allow the second barrier layer 62 to function as a varistor, cuts may be made in the electron transport layer 20, the light absorbing layer 30, the separator layer 40, the hole transport layer 50, and the electrode 55. The wavelength of the laser used is preferably in the ultraviolet region. For example, the cut (L3) is made in the separator layer 40, the hole transport layer 50, and the electrode 55, and the separator layer 40, the hole transport layer 50, and the electrode 55 are formed. Furthermore, a cut for forming a varistor can be made. If the portion with the cut (L3) functions as a varistor, the cut can be omitted.

[0087] The second barrier layer 62 is a dense inorganic material layer and is provided so as to cover the side portions of the light absorbing layer 30. The second barrier layer 62 can also be provided so as to cover the entire periphery of the light absorbing layer 30. The second barrier layer 62 can also be provided so as to cover the upper surface of the electrode 55. This second barrier layer 62 can prevent moisture (such as water vapor) from penetrating the light absorbing layer 30, thereby preventing deterioration of the solar cell 100. Furthermore, because the second barrier layer 62 is a dense inorganic material layer, it is possible to prevent the barrier function of the second barrier layer 62 from being reduced by ultraviolet rays, temperature changes, and the like. Furthermore, the barrier properties against water vapor can also be improved by completely coating the light absorbing layer 30 with the second barrier layer 62, the transparent conductive film 12, the transparent substrate 11, and the like.

[0088] The second barrier layer 62 may also be made of a material that exhibits varistor characteristics. The second barrier layer 62 can be provided so as to be connected to the transparent conductive film 12 and the electrode 55 so that the second barrier layer 62 and the light absorbing layer 30 are connected in parallel. The varistor characteristics are voltage-current characteristics (current nonlinearity) in which current suddenly begins to flow at a certain constant voltage. There are no particular restrictions on the material that exhibits varistor characteristics, as long as it is a material that can be used in a varistor element.

[0089] The thickness of the second barrier layer 62 can be, for example, 30 nm or more and 100 nm or less. The second barrier layer 62 is formed on the electrode 55 after laser scribing. The second barrier layer 62 can be formed so as to fill the notch (L3). This allows the periphery and upper surface of the light absorbing layer 30 to be covered with the second barrier layer 62. The second barrier layer 62 can be formed so as to fill the notch. This allows the second barrier layer 62 to be connected to the transparent conductive film 12 and the electrode 55 so that the second barrier layer 62 and the light absorbing layer 30 are connected in parallel.

[0090] By connecting a part of the second barrier layer 62 in parallel to the light absorbing layer 30 as a varistor element structure, it is possible to realize a solar cell 100 that is integrally provided with a bypass diode (varistor of the second barrier layer 62). This makes it possible to prevent a decrease in power generation efficiency due to shadowing on the module at low cost.

[0091] The second barrier layer 62 may contain, for example, zinc oxide (ZnO) as a main material, and may contain, as additive materials, silicon oxide, aluminum oxide, titanium oxide, etc. The varistor characteristics (I=KVα, K: element-specific constant, α: voltage nonlinearity coefficient) of the second barrier layer 62 between the transparent conductive film 12 and the electrode 55 are preferably such that α=20 to 60 and the bending point voltage is 2 V or more.

[0092] The rear substrate 64 is a substrate disposed on top of the second barrier layer 62, and the light absorbing layer 30 is located between the transparent base 11 and the rear substrate 64. The rear substrate 64 may be a substrate of the solar cell module 1000 or 1100. The rear substrate 64 may be a glass substrate, a transparent organic film, or an opaque organic film.

[0093] When the rear substrate 64 is an organic film, a third barrier layer 63 may be provided on one of the main surfaces of the rear substrate 64. The third barrier layer 63 is a layer made of a material with high gas barrier properties. This makes it possible to prevent deterioration inside the solar cell 100 due to moisture, oxygen, and the like in the air. The third barrier layer 63 is also a layer made of an insulating material. This makes it possible to suppress the flow of leakage current. The film thickness of the third barrier layer 63 can be several tens to 100 nm. Specific examples of materials for the third barrier layer 63 include silicon oxide and aluminum oxide.

[0094] A second terminal 72 of the solar cell module 1000, 1100 is formed on the organic film that serves as the rear substrate 64, and a portion of the second terminal 72 penetrates the organic film (rear substrate 64) and the third barrier layer 63, and is in contact with the electrode 55 at the end of the series-connected solar cell 100 or is connected via the second barrier layer 62. The first terminal 71 and the second terminal 72 can be used to extract current generated by photovoltaic power from the solar cell module 1000, 1100. An example of a material for the second terminal 72 is a SnZn-based solder paste. Other conductive pastes and materials for the electrode 55 can also be used as long as they meet the requirements.

[0095] After forming the second barrier layer 62 on the electrode 55, etc., a back substrate 64 on which a second terminal 72 is formed is attached to the second barrier layer 62 via a laminate sheet, followed by heat lamination to complete a solar cell module 1000 in which multiple solar cells 100 are connected in series. Holes are drilled in the laminate sheet sandwiched between the second barrier layer 62 and the back substrate 64 at the locations where the second terminals 72 will be located. This ensures good connection between the second terminals 72 and the second barrier layer 62 during lamination. This forms a varistor between the electrode 55 and the second terminal 72. Because a high voltage is applied between the electrode 55 and the second terminal 72 during power generation, the varistor characteristics do not interfere with current extraction. The electrode 55 and the second terminal 72 may also be in contact.

[0096] The laminate sheet may be a general laminate material, and is preferably a resin film that has high waterproof properties and can be laminated at a temperature of 130° C. or less.

[0097] Fig. 10 is a diagram in which a schematic cross-sectional view of one solar cell 100 included in the solar cell modules 1000, 1100 is superimposed with an equivalent circuit of the solar cell 100, and Fig. 11 is an equivalent circuit of the solar cell module 1000. As shown in Fig. 10 and Fig. 11, the electron transport layer 20, the light absorption layer 30, and the hole transport layer 50 can be represented by a current source 82 and a diode 83. In addition, the varistor 81 is connected to the transparent conductive film 12 and the electrode 55 so as to be connected in parallel with the light absorption layer 30.

[0098] As described above, the solar cell modules 1000 and 1100 according to the present disclosure include the solar cell 100 described above, and therefore can improve conversion efficiency and durability.

[0099] 3. Method for Manufacturing Solar Cell Fig. 12 is a process diagram of a method for manufacturing a solar cell according to the present disclosure. As shown in Fig. 12, the method for manufacturing a solar cell according to the present disclosure includes a step (S1) of forming an electron transport layer on a first electrode, a step (S2) of forming a light absorbing layer including a first perovskite layer on the electron transport layer, a step (S3) of forming a separator layer on the light absorbing layer, a step (S4) of forming a hole transport layer on the separator layer, and a step (S5) of forming an electrode on the hole transport layer.

[0100] First, an electron transport layer is formed on a first electrode (S1). The first electrode and the electron transport layer used are as described above. For example, fluorine-doped SnO ２ A solution for an electron transport layer (coating liquid) is prepared and applied to the glass substrate on which the conductive film has been deposited by spin coating. The applied layer is then heated at 150°C for 30 minutes to form an electron transport layer on the first electrode.

[0101] Then, a light absorbing layer including a first perovskite layer is formed on the electron transport layer (S2). Figure 13 is an explanatory diagram of a manufacturing method for forming a light absorbing layer by applying and drying a perovskite compound solution. The light absorbing layer forming step in the manufacturing method for a solar cell further includes a step of applying a coating liquid including a perovskite compound onto the electron transport layer provided on a transparent substrate, and a drying step of drying the coating film thus formed.

[0102] A coating film is formed by applying the coating liquid onto the electron transport layer. The coating method is not particularly limited, but can be screen printing, dip coating, inkjet printing, slit die coating, or the like. The coating environment is preferably maintained in a low-humidity environment, and may be sealed with an inert gas such as nitrogen gas. A laminate of a transparent substrate, a transparent conductive film, and an electron transport layer may be arranged so that the transparent substrate is located on the ground side (-Y) and the electron transport layer is located on the top side (+Y), and the coating liquid is applied onto the electron transport layer from the top side of the laminate. This prevents dripping from the slit die. Furthermore, the coffee ring effect can be suppressed during the drying step.

[0103] In the drying process, the solvent contained in the coating film evaporates, which increases the concentration of the perovskite compound in the coating film and promotes crystallization of the perovskite compound from the electron transport layer side.

[0104] Next, a separator layer is formed on the light absorbing layer (S3). The separator layer forming step involves forming a spacer material and then forming a second perovskite layer. The separator layer forming step involves adding a solution containing the spacer material to a solution containing the perovskite. This allows the separator layer to be formed in a single addition.

[0105] The separator layer is a layer of spacer material with a thickness of 10 to 100 nm formed on the surface of the light absorbing layer. At this time, the spacer material is closely packed (face-centered cubic arrangement) within the plane. A dispersion of the spacer material at 0.5 to 5 wt % in the organic solvent of the coating liquid is preferred. The oxide particles of the spacer material are preferably SiO ２ Fine particles with a particle size of 10 to 50 nm are desirable. This allows the inorganic filler oxide particles to form a uniform, closely packed structure when coated and dried. This has the effect of improving the durability of the perovskite compound against the penetration of water molecules.

[0106] Fig. 14 is an explanatory diagram for forming the second perovskite layer. As shown in Fig. 14, the second perovskite layer may be formed by vacuum deposition or sputtering.

[0107] Next, a hole transport layer is formed on the separator layer (S4). A coating solution is prepared and applied to the separator layer by spin coating, and the applied layer is heated at 70° C. for 30 minutes to form a hole transport layer.

[0108] Then, an electrode is formed on the hybrid hole transport layer (S5). For example, a gold vapor deposition film is formed as an anode by vacuum deposition, thereby obtaining a solar cell according to the present disclosure. The electrode used is as described above.

[0109] As described above, according to the solar cell manufacturing method of the present disclosure, since a solution containing a spacer material is added to a solution containing a perovskite, a separator layer can be formed by adding the spacer material in a single step. This makes it possible to easily manufacture solar cells with improved conversion efficiency and durability, and to simplify conventional processes.

[0110] The solar cell manufacturing method, solar cell module manufacturing method, solar cell, and solar cell module according to the present disclosure will be specifically explained below using examples and comparative examples, but the present disclosure is not limited to the examples described here.

[0111] (Example 1) (1) Transparent conductive substrate: Fluorine-doped SnO ２ A glass substrate (thickness: X mm) on which a conductive film is vapor-deposited is prepared and cut into a size of 25 mm x 25 mm. The substrate is subjected to ultrasonic cleaning with ethanol for 15 minutes, dried with nitrogen gas, and then irradiated with UV light for 30 minutes to obtain a transparent conductive substrate.

[0112] (2) Electron transport layer First, tin (IV) oxide, 15% in H ２ A 15% by mass aqueous solution of O colloidal dispersion (manufactured by Alfa Aesar) is diluted with ultrapure water to prepare a solution (coating liquid) for the electron transport layer, which is a 7.5% by mass aqueous solution of tin(IV) oxide. Next, the solution for the electron transport layer is applied by spin coating to the transparent conductive substrate prepared in "(1) Transparent conductive substrate," and the applied layer is heated at 150°C for 30 minutes to form a tin oxide electron transport layer with a thickness of 50 to 100 nm.

[0113] (3) Light-Absorbing Layer (Perovskite Light-Absorbing Layer) First, 18.3 mg of CsI (Cesium Iodide) (manufactured by Tokyo Chemical Industry Co., Ltd.), 22.7 mg of MABr (Methylamine Hydrobromide, chemical formula: CHNHBr) (manufactured by Tokyo Chemical Industry Co., Ltd.), 25.7 mg of PbBr (manufactured by Tokyo Chemical Industry Co., Ltd.), and PbI ２ 596.2 mg of FAI (Formamidine Hydroiodide, chemical formula: CHNHI) (Tokyo Chemical Industry Co., Ltd.) and 187.5 mg of FAI (Formamidine Hydroiodide, chemical formula: CHNO) (Tokyo Chemical Industry Co., Ltd.) were dissolved by heating in a mixed solution of 0.8 ml of DMF (N,N-Dimethylformamide, chemical formula: CHNO) (Tokyo Chemical Industry Co., Ltd.) and 0.24 ml of DMSO (Tokyo Chemical Industry Co., Ltd.). ０．８５ MA ０．１５ PbI ２．７５ Br ０．２５ A coating solution is prepared. This coating solution is applied by spin coating onto the tin oxide layer prepared in "(2) Electron transport layer," and chlorobenzene is added dropwise during the spinning process to prepare a coating film. The coating layer is heated at 150°C for 10 minutes to form a light absorbing layer containing a first perovskite layer with a film thickness of 500 to 1,000 nm.

[0114] (4) Separator layer (4-1) Spacer material layer SiO ２ 5.6 mg of the powder (particle size: 10-50 nm) was dissolved in 1 ml of chlorobenzene (Tokyo Chemical Industry Co., Ltd.) by heating, and 0.5 wt % SiO ２ A coating solution is prepared. This coating solution is applied by spin coating onto the light absorbing layer prepared in "(3) Light absorbing layer" to prepare a coating film. The coating layer is heated at 150°C for 5 minutes to form a spacer material layer with a thickness of 10 to 1000 nm.

[0115] (4-2) Second perovskite layer PbI ２ (Tokyo Chemical Industry Co., Ltd.) and MAI (Tokyo Chemical Industry Co., Ltd.) were placed in a tungsten boat, and PbI ２ and MAI (manufactured by Tokyo Chemical Industry Co., Ltd.) were vapor-deposited together to form a second perovskite layer MAPbI with a film thickness of 200 to 300 nm. ３ (CH ３ NH ３ PbI ３ ) is formed.

[0116] (5) Hole transport layer First, 73.5 mg of Spiro-OMeTAD (manufactured by Tokyo Chemical Industry Co., Ltd.), Co(III)TFSI (Tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)-cobalt(III)tris(bis(trifluoromethylsulfonyl)imide)), chemical formula: C 42 H 45 CoF 18 N 12 O 12 S6) 13.5 mg of complex (FK209) (Tokyo Chemical Industry Co., Ltd.), 27 μl of TBP (Tokyo Chemical Industry Co., Ltd.), 8.6 mg of LiTSFI (Bis(trifluoromethane)-sulfonimide lithium salt, chemical formula: CF3SO2NLiSO2CF3) (Tokyo Chemical Industry Co., Ltd.), and 14.3 mg of NiO (particle size 30 nm) (Tokyo Chemical Industry Co., Ltd.) were heated and dissolved in 1 ml of chlorobenzene (Tokyo Chemical Industry Co., Ltd.) to prepare a hole transport layer coating solution. This coating solution was applied by spin coating to the perovskite light absorption layer prepared in "Light Absorption Layer (Perovskite Light Absorption Layer)." The coating layer was then heated at 70°C for 30 minutes to form a hole transport layer containing organic and inorganic materials with a thickness of 250 to 300 nm. The thickness of the p-type inorganic layer (inorganic material) of the light absorption layer with uneven deposition was set to 40 to 100 nm.

[0117] (6) Electrode (Anode) On the hole transport layer prepared in "(5) Hole transport layer", a gold vapor-deposited film having an area of ​​3 mm × 20 mm and a thickness of 80 nm was formed as an anode by vacuum deposition to obtain the solar cell of Example 1.

[0118] Example 2: SiO as spacer material for separator layer ２ Instead of Al oxide ２ O ３ A solar cell of Example 2 is obtained in the same manner as in Example 1, except that the above-mentioned was used.

[0119] Example 3: MAPbI in the second perovskite layer ３ Instead of FAPbI3 (CH ８ N ２ PbI ３ A solar cell of Example 3 is obtained in the same manner as in Example 1, except that the above-mentioned cellulose ester is used.

[0120] Example 4: SiO as spacer material for separator layer ２ Instead of the oxide TiO ２ A solar cell of Example 4 is obtained in the same manner as in Example 1, except that the above-mentioned was used.

[0121] Example 5 First perovskite layer FA of light absorbing layer ０．８５ MA ０．１５ PbI ２．７５ Br ０．２５ Instead of MASn ３ I ３ A solar cell of Example 5 is obtained in the same manner as in Example 1, except that the above-mentioned was used.

[0122] Comparative Example 1 On the other hand, a solar cell of Comparative Example 1 was obtained in the same manner as in Example 1, except that the separator layer was not formed.

[0123] The results of the above examples and comparative examples are shown in Table 1. In Table 1, Ec1 indicates the conduction band level of the first perovskite layer, and Ev1 indicates the valence band level of the first perovskite layer. Ec2 indicates the conduction band level of the p-type inorganic particles, and Ev2 indicates the valence band level of the p-type inorganic particles. Ec3 indicates the conduction band level of the p-type organic material, and Ev3 indicates the valence band level of the p-type organic material.

[0124]

[0125] As shown in Table 1, all of the solar cells having the separator layer formed thereon exhibited very good or excellent results in terms of conversion efficiency and durability.

[0126] Among them, the oxide particles of the spacer material are SiO ２ , Al ２ O ３ , SiO ２ Solar cells with spacer material particle sizes of 30 nm tend to show very good results.

[0127] On the other hand, Comparative Example 1, in which no separator layer is formed, shows poor results in terms of conversion efficiency and durability.

[0128] As described above, it is possible to provide a method for manufacturing a solar cell, a method for manufacturing a solar cell module, a solar cell, and a solar cell module with improved conversion efficiency and durability. Furthermore, the solar cell and the method for manufacturing a solar cell according to the present disclosure can be suitably used and applied to large-area solar power generation systems (mega solar) and power sources for small portable devices.

[0129] Although each embodiment and each example of the present disclosure have been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel features and effects of the present disclosure. Therefore, all such modifications are intended to be included within the scope of the present disclosure.

[0130] For example, a term described at least once in the specification or drawings together with a different term having a broader or similar meaning can be replaced with that different term anywhere in the specification or drawings. Furthermore, the manufacturing method of a solar cell, the manufacturing method of a solar cell module, the configurations and operations of the solar cell and the solar cell module are not limited to those described in the embodiments and examples of the present disclosure, and various modifications are possible.

Claims

1. A step of forming an electron transport layer on the first electrode, A step of forming a light-absorbing layer including a first perovskite layer on the electron transport layer, The steps include forming a separator layer on the light-absorbing layer, The process of forming a hole transport layer on the separator layer, The process of forming a second electrode on the separator layer, Includes, The separator layer includes a spacer material, The spacer material is an inorganic filler, A method for manufacturing a solar cell, characterized in that the separator layer has a composite structure including the inorganic filler and a second perovskite layer.

2. The method for manufacturing a solar cell according to claim 1, characterized in that the first perovskite layer comprises a perovskite material having a valence band upper level in the range of -5.1 eV to -5.7 eV and a conduction band lower level in the range of -3.5 eV to -4.0 eV.

3. The first perovskite layer is based on the general formula ABX ３ Composed of, The method for manufacturing a solar cell according to claim 1, characterized in that A is an organic molecule or an organic-inorganic mixed molecule, B is a metal atom, and X is a halogen atom.

4. The spacer material is SiO ２ or Al ２ O ３ It also has a band gap wider than 5.0 eV, The method for manufacturing a solar cell according to claim 1, characterized in that the film thickness of the spacer material is 10 to 100 nm.

5. The spacer material is an inorganic filler, The separator layer has a composite structure including the inorganic filler and a second perovskite layer. The method for manufacturing a solar cell according to claim 1, characterized in that the second perovskite layer has the same or deeper conduction band level as the hole transport layer and also has the same or deeper valence band level as the hole transport layer.

6. The spacer material is an inorganic filler, The separator layer has a composite structure including the inorganic filler and a second perovskite layer. The method for manufacturing a solar cell according to claim 1, characterized in that the second perovskite layer has the same or shallower conduction band level as the light-absorbing layer and also has the same or shallower valence band level as the light-absorbing layer.

7. A method for manufacturing a solar cell module, characterized by integrating and modularizing solar cells manufactured by the method for manufacturing solar cells described in any one of claims 1 to 6.

8. A first type of transport layer, A light-absorbing layer containing a perovskite compound, Separator layer, The second type of transport layer, They are provided in this order, The separator layer includes a spacer material, The spacer material is an inorganic material. The solar cell is characterized in that the separator layer contains the inorganic material and a perovskite compound.

9. The perovskite compound contained in the light-absorbing layer is a first perovskite compound, The perovskite compound contained in the separator layer is a second perovskite compound, The solar cell according to claim 8, characterized in that the first perovskite compound and the second perovskite compound contain different materials.

10. The first type of transport layer is an electron transport layer, The solar cell according to claim 8, wherein the second type of transport layer is a hole transport layer.

11. The solar cell according to claim 10, characterized in that the perovskite compound contained in the light-absorbing layer has a valence band upper level in the range of -5.1 eV to -5.7 eV and a conduction band lower level in the range of -3.5 eV to -4.0 eV.

12. The perovskite compound contained in the light-absorbing layer has the general formula ABX ３ Composed of, The solar cell according to claim 8, characterized in that A is an organic molecule or an organic-inorganic mixed molecule, B is a metal atom, and X is a halogen atom.

13. The spacer material is SiO ２ or Al ２ O ３ It also has a band gap wider than 5.0 eV, The solar cell according to claim 8, characterized in that the film thickness of the spacer material is 10 to 100 nm.

14. The spacer material is an inorganic filler, The solar cell according to claim 10, characterized in that the perovskite compound contained in the separator layer has the same or deeper conduction band level as the hole transport layer and also has the same or deeper valence band level as the hole transport layer.

15. The spacer material is an inorganic filler, The separator layer has a composite structure comprising the inorganic filler and the perovskite compound. The solar cell according to claim 8, characterized in that the perovskite compound contained in the separator tank has the same or shallower conduction band level as the light-absorbing layer and also has the same or shallower valence band level as the light-absorbing layer.

16. A solar cell module comprising solar cells as described in any one of claims 8 to 15, A solar cell module characterized in that the first electrode is a transparent conductive substrate.