Solar battery and method for manufacturing same

Abstract

This solar battery (25) has a plurality of solar cells (20-20) in which a first electrode (3), a photoelectric conversion layer (4), and a second electrode (8) are disposed in said order on one surface of a substrate (2), and layers formed on the one surface of the substrate (2) are divided by a plurality of separation grooves (P1-P3). The plurality of separation grooves (P1-P3) include a separation groove (P2) for electrode connection which is for electrically connecting the first electrode (3) and the second electrode (8), and the separation groove (P2) for electrode connection has at least two portions (T(1)-T(n)) having different depths.

Description

Solar cell and its manufacturing method

[0001] The present disclosure relates to a solar cell having a plurality of solar cell cells in which a first electrode, a photoelectric conversion layer, and a second electrode are arranged in this order on one surface of a base, and the layer formed on one surface of the base is divided by a plurality of separation grooves, and a method for manufacturing the same.

[0002] When manufacturing a solar cell, first, a first electrode is formed on one surface of a substrate, then a photoelectric conversion layer (e.g., a photoelectric conversion layer including an electron transport layer, a light absorption layer, and a hole transport layer) is formed on the surface of the first electrode opposite the substrate, and further, an electrode connection separation groove for electrically connecting the first electrode and the second electrode is formed in the photoelectric conversion layer by cutting processing such as mechanical processing (mechanical scribing) or laser processing (laser scribing) (see, for example, Patent Documents 1 and 2).

[0003] JP 2011-077104 A JP 2013-149698 A

[0004] However, in the manufacture of such conventional solar cells, when forming electrode connection separation grooves by cutting, there is a large variation in the properties (film quality, film thickness, for example, hardness) of each deposited layer (e.g., photoelectric conversion layer), making it difficult to perform the cutting process stably. That is, in order to enable solar cells to efficiently generate electricity, the electrode connection separation grooves should be cut to a desired depth (e.g., a position contacting the surface of the first electrode opposite the substrate), but even if processing is performed under the same cutting conditions (cutting strength) between individual solar cells, the cutting strength may be too strong or too weak for each deposited layer, making it impossible to stably form the electrode connection separation grooves to the desired depth, resulting in variation in the cutting depth.

[0005] For example, if the cutting strength is too strong, the first electrode may be cut off. As a result, the first electrode and the second electrode are no longer electrically connected. Also, if the cutting strength is too weak, the electrode connection separation groove may not reach the first electrode (so-called film residue of the photoelectric conversion layer may occur). This results in a high resistance value between the first electrode and the second electrode. In either case, the characteristics of the solar cell will vary greatly.

[0006] As described above, in conventional solar cell manufacturing methods, it is not possible to reliably electrically connect the first electrode and the second electrode, which ultimately leads to a decrease in the power generation efficiency of the solar cell. This is particularly noticeable when the photoelectric conversion layer has a light absorption layer containing an organic material, and the organic material contains a perovskite.

[0007] Therefore, an object of the present disclosure is to provide a solar cell that can improve power generation efficiency and a method for manufacturing the same.

[0008] In order to solve the above problems, the following solar cell and method for manufacturing the same are provided.

[0009] (1) Solar Cell The solar cell according to the present disclosure is a solar cell having a plurality of solar cell cells in which a first electrode, a photoelectric conversion layer, and a second electrode are arranged in this order on one surface of a base, and the layer formed on the one surface of the base is divided by a plurality of separation grooves, wherein the plurality of separation grooves include electrode connection separation grooves for electrically connecting the first electrode and the second electrode, and the electrode connection separation grooves have at least two portions with different depths.

[0010] (2) Method for manufacturing solar cell The method for manufacturing a solar cell according to the present disclosure is a method for manufacturing a solar cell according to the present invention, characterized in that it includes a first step of arranging the photoelectric conversion layer on the surface opposite the substrate of the first electrode formed on one surface of the substrate, and a second step of forming the electrode connection separation groove having at least two portions with different depths by cutting the layer formed on the one surface of the substrate.

[0011] According to the present disclosure, it is possible to improve the power generation efficiency of solar cells.

[0012] FIG. 1 is a cross-sectional view schematically illustrating an example of a schematic configuration of a solar cell according to the present embodiment. FIG. 2 is a process diagram of an example of a method for manufacturing a solar cell. FIG. 3A is a cross-sectional view schematically illustrating an example of a step of forming a first overcoat layer in a manufacturing process (first step) common to the solar cell according to the present embodiment and a conventional solar cell. FIG. 3B is a cross-sectional view schematically illustrating an example of a step of forming a first electrode-cutting separation groove in a manufacturing process (first step) common to the solar cell according to the present embodiment and a conventional solar cell. FIG. 3C is a cross-sectional view schematically illustrating an example of a step of forming a light-absorbing layer and a second overcoat layer in a manufacturing process (first step) common to the solar cell according to the present embodiment and a conventional solar cell. FIG. 4A is a cross-sectional view schematically illustrating an example of a step of forming an electrode-connection separation groove in a manufacturing process (second step) of a conventional solar cell. FIG. 4B is a cross-sectional view schematically illustrating an example of a step of forming a second electrode in a manufacturing process (second step) of a conventional solar cell. FIG. 4C is a cross-sectional view schematically illustrating an example of a step of forming a second electrode-cutting separation groove in a manufacturing process (third step) of a conventional solar cell. FIG. 5 is a cross-sectional view schematically showing a power generation state of a conventional solar cell in which an electrode connection separation groove is formed to a desired depth. FIG. 6A is a cross-sectional view schematically showing a state in which an electrode connection separation groove is deeper than a desired depth in a configuration example of a conventional solar cell. FIG. 6B is a cross-sectional view schematically showing a state in which an electrode connection separation groove is shallower than a desired depth in a configuration example of a conventional solar cell. FIG. 7A is a cross-sectional view schematically showing an example of a step of forming an electrode connection separation groove in a manufacturing process (second step) of a solar cell according to the present embodiment. FIG. 7B is a cross-sectional view schematically showing an example of a step of forming a second electrode in a manufacturing process (second step) of a solar cell according to the present embodiment. FIG. 7C is a cross-sectional view schematically showing an example of a step of forming a second electrode cutting separation groove in a manufacturing process (third step) of a solar cell according to the present embodiment. FIG. 8A is an enlarged cross-sectional view showing a portion of the manufacturing process shown in FIG. 7A. FIG. 8B is an enlarged cross-sectional view showing a portion of an example of a solar cell manufactured by the manufacturing processes shown in FIGS. 7A to 7C. FIG. 9 is a plan view of a solar cell manufactured by the manufacturing steps shown in FIGS. 7A to 7C, viewed from the second electrode side.

[0013] Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. In the following description, identical components are assigned the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated. As an example, the base side is expressed as the lower side and the opposite side as the upper side, but this is for convenience and does not relate to the installation direction or the recommended installation direction. As long as there is no contradiction, it is applicable even if the top and bottom are reversed or the left and right are rephrased.

[0014] First Embodiment FIG. 1 is a cross-sectional view showing a schematic configuration example of a solar cell 25 according to this embodiment.

[0015] As shown in FIG. 1 , the solar cell 25 includes a base 2 (the same as or including a base material or substrate; the same applies in the present disclosure), a first electrode 3 (3a to 3c in the illustrated example) provided on one surface of the base 2 (on the base 2), a photoelectric conversion layer 4 (4a to 4c in the illustrated example) provided on the surface of the first electrode 3 opposite the base 2 (on the first electrode 3), and a second electrode 8 (8a to 8c in the illustrated example) provided on the surface of the photoelectric conversion layer 4 opposite the first electrode 3 (on the photoelectric conversion layer 4). That is, in this example, the solar cell 25 has the first electrode 3, the photoelectric conversion layer 4, and the second electrode 8 arranged or stacked in this order on the base 2. Note that, although the description here is given assuming that the first electrode 3, the photoelectric conversion layer 4, and the second electrode 8 are arranged in contact with each other in this order, they do not necessarily have to be arranged in contact with each other. The presence of other elements between the electrodes is not excluded. That is, the first electrode 3, the photoelectric conversion layer 4, and the second electrode 8 may be arranged in this order. Also, it is not necessary that all three of them be present.

[0016] The photoelectric conversion layer 4 is composed of an overcoat layer (intermediate layer) (electron transport layer 5, hole transport layer 7) and a light absorbing layer 6 (6a to 6c in the illustrated example) (light absorbing layer). Examples of the overcoat layer include the electron transport layer 5 and the hole transport layer 7. In this example, the solar cell 25 has a first electrode 3, an electron transport layer 5 (5a to 5c in the illustrated example), a light absorbing layer 6, a hole transport layer 7 (7a to 7c in the illustrated example), and a second electrode 8 stacked in this order on the base 2. Note that the solar cell 25 may also have a first electrode 3, a hole transport layer 7, a light absorbing layer 6, an electron transport layer 5, and a second electrode 8 stacked in this order on the base 2.

[0017] The solar cell 25 has a plurality of solar cell cells 20-20 (20a-20c in the illustrated example). The solar cell 25 has the plurality of solar cell cells 20-20 formed by dividing a layer formed on the base 2 by a plurality of separation grooves P-P (P1-P3 in this example).

[0018] In the solar cell 25, the photoelectric conversion layer 4 is composed of an electron transport layer 5, a light absorption layer 6, and a hole transport layer 7, and a plurality of first electrodes 3-3 (3a-3c), a plurality of photoelectric conversion layers 4-4 (4a-4c), and second electrodes 8-8 (8a-8c) constitute a plurality of solar cell cells 20-20 (20a-20c). In the solar cell 25, adjacent solar cell cells 20, 20 are electrically connected in series. Therefore, the solar cell 25 is a series-connected solar cell. In the solar cell 25, the number of solar cell cells 20-20 connected in series is not particularly limited as long as it is plural.

[0019] Examples of materials that can be used for the base 2 include a glass substrate and an organic film. Specific examples of materials for the organic film 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 will become the base 2 is preferably approximately 50 μm to 100 μm.

[0020] The first electrode 3 is disposed on the substrate 2 and serves to extract current generated by photovoltaic power of the photoelectric conversion layer 4 of the solar cell 20. When the substrate 2 is the light incident side, the first electrode 3 can be a transparent conductive film. The transparent conductive film can be 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 first electrode 3 may also be configured by patterning thin wires of a conductive metal such as silver on an oxide of a conductive transparent material. Note that "transparent" means that the electrode transmits light, but does not exclude materials that reflect or absorb light even slightly. It refers to the electrode being disposed on the light-receiving surface side of the solar cell (including the portion where light is incident, the same applies in the present disclosure). Therefore, a transparent conductive film can be defined as being transparent if it is disposed at least on the light-receiving surface side. In other words, a transparent conductive film refers to a conductive film disposed on the light-receiving surface side of the solar cell. The term "film" does not specify thickness or width, and includes patterned or island-shaped films and films with portions of different thicknesses. Preferably, the film has a substantially constant thickness. Unless otherwise specified, "substantially" or "approximately" refers to the range of manufacturing error, and preferably indicates that a variation of plus or minus 15% of the numerical value is allowed.

[0021] The sheet resistance of the first electrode 3 is preferably 10 Ω / sq or less. It is more preferable that the light transmittance of the first electrode 3 is 80% or more. Examples of methods for forming the first electrode 3 include a sputtering film formation method, a vacuum deposition method, and a formation method using a conductive paste coating / printing technique and a low-temperature firing technique.

[0022] When a transparent conductive film is formed on the base 2, the transparent conductive film formed on the base 2 is divided into individual solar cell units 20. For example, the solar cell 25 shown in Fig. 1 includes three solar cell units 20 (20a to 20c), and therefore the transparent conductive film is divided by first electrode cutting separation grooves P1, and three first electrodes 3 (3a to 3c) are formed. The first electrode cutting separation grooves P1 may be filled with a light absorbing layer 6 or the like.

[0023] The photoelectric conversion layer 4 is a layer in which light energy is converted into electrical energy. Specifically, photovoltaic power is generated when the photoelectric conversion layer 4 receives light. The photoelectric conversion layer 4 is provided on the first electrode 3. In this example, the photoelectric conversion layer 4 has an electron transport layer 5, a light absorption layer 6 provided on the electron transport layer 5, and a hole transport layer 7 provided on the light absorption layer 6.

[0024] The electron transport layer 5 is a layer that has the function of transporting electrons generated in the light absorbing layer 6 to the first electrode 3. It is self-evident that an electron transport layer located on the electron transport side of the light absorbing layer or on the electron transport side of the light absorbing layer has the function of transporting electrons, so long as the solar cell functions as a solar cell, and no confirmation is required. In other words, as long as the solar cell functions as a solar cell, a layer located on the electron transport side of the light absorbing layer or on the electron transport side of the light absorbing layer is called an electron transport layer. The electron transport layer 5 is made of a material that allows electrons generated in the light absorbing layer 6 to easily move to the electron transport layer 5 and that allows electrons in the electron transport layer 5 to easily move to the first electrode 3. The electron transport layer 5 may also serve as a seed layer for oriented growth of the light absorbing layer 6. This can improve the crystalline quality of the perovskite compound that constitutes the light absorbing layer 6. The electron transport layer 5 can be made of, for example, titanium oxide (TiO ２ The surface of the titanium oxide layer may be covered with a TiN layer or a TiO ２ A −xNx layer may be formed on the electron transport layer 5. The thickness of the electron transport layer 5 is, for example, about 100 nm to 250 nm.

[0025] For example, titanium oxide (TiO ２ The overcoat layer can be formed to a thickness of about 100 nm to 250 nm. Examples of methods for forming the overcoat layer include sputtering, vacuum deposition, and methods using conductive paste coating / printing techniques and low-temperature firing techniques. For example, titanium oxide (TiO ２ The seed layer can be formed by applying the paste onto the transparent conductive film and baking it at 150°C or less. ２TiO contained in the layer ２ The crystal structure of TiO is preferably a rutile structure. ２ The surface of the TiO ２ A TiN (NaCl structure) layer having a thickness of about 5 nm to 30 nm may be formed on the surface of the substrate.

[0026] 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, preventing 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. ２ Since the layer is thin, structural relaxation of the lattice constant does not occur, and the lattice constant of the underlying TiN layer is maintained.

[0027] The light absorption layers 6 (6a to 6c) absorb light incident on the photoelectric conversion layers 4 (4a to 4c) and generate electrons and holes. The electrons move to the electron transport layer 5, and the holes move to the hole transport layer 7.

[0028] The light absorbing layer 6 contains a perovskite compound or an organic-inorganic hybrid compound. This compound can generate electrons and holes in the light absorbing layer 6. The film thickness of the light absorbing layer 6 is preferably within a range of approximately 500 nm to 1000 nm.

[0029] For example, as shown in FIG. 3B described later, after forming a notch (separation groove P1 for cutting the first electrode) by cutting processing such as mechanical processing or laser processing, a perovskite compound can be formed on the first overcoat layer (electron transport layer 5), thereby forming the light absorption layer 6.

[0030] The perovskite compound has the general formula: ABX ３...(1). However, 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 constituent element does not necessarily have to be a single type. As long as the light-absorbing layer has photoelectric conversion function, there is a degree of freedom in the configuration as described above. In general formula (1), A is an organic molecule (including an organic group or an organic cation, the same applies in the present disclosure) or an inorganic atom or molecule (including an inorganic group or an inorganic cation, the same applies in the present disclosure), or a combination thereof; B is a metal atom or molecule (including a metal cation, the same applies in the present disclosure); and X is a halogen atom or molecule or a chalcogen atom or molecule (including a halogen anion or a chalcogen anion, the same applies in the present disclosure). In general formula (1), the three Xs may be the same or different from each other. When contained in a light absorbing layer, a perovskite compound can absorb light and convert it into electricity, and this fact should be taken into consideration. That is, a perovskite compound can be confirmed by, for example, detecting organic molecules, metal atoms, and halogen atoms. Furthermore, a perovskite compound can be confirmed by detecting elements corresponding to A, B, and X, as long as the light absorbing layer has a photoelectric conversion function. For example, molecules containing carbon, nitrogen, and hydrogen are suitable as organic molecules, and therefore, carbon, nitrogen, hydrogen, a metal element, and a halogen element or chalcogen element can be detected. Alternatively, a perovskite compound can be confirmed by detecting A, B, and X, for example, by detecting inorganic atoms, a metal atom, and a halogen atom. Furthermore, a perovskite compound can be confirmed by detecting elements corresponding to A, B, and X, as long as the light absorbing layer has a photoelectric conversion function. For example, cesium or rubidium is suitable as the inorganic atom, and therefore, cesium or rubidium, a metal element, and a halogen or chalcogen can be detected. Furthermore, the fact that the light absorbing layer 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 may also contain compounds other than perovskite compounds.

[0031] The light absorption layer may contain an organic-inorganic hybrid compound. An organic-inorganic hybrid compound refers to a compound containing both inorganic and organic elements. A solar cell using a perovskite compound contained in an organic-inorganic hybrid compound is also called an organic-inorganic hybrid solar cell. Organic typically refers to a material composed of multiple carbon elements. Carbon materials such as graphite, graphene, carbon nanowires, carbon nanofibers, carbon nanotubes, and carbon and carbon black that function as electrodes are not considered to be organic. In other words, organic refers to materials that contain multiple carbon elements, excluding carbon materials such as graphite. Inorganic refers to materials that are not organic.

[0032] 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.

[0033] 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.

[0034] Alkylammonium is an ionized product of the above-mentioned alkylamine. Examples of alkylammonium include methylammonium (CH ３ NH ３), 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.

[0035] 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. Phenethylammonium is preferred as the ionized nitrogen-containing heterocyclic compound.

[0036] 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.

[0037] 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.

[0038] In addition, 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.

[0039] The perovskite compound contained in the light absorbing layer 6 is CH ３ NH ３ PbX ３ (wherein X is a halogen atom), and ３ NH ３ PbX ３ In the compound, X is an iodine atom (i.e., CH ３ NH ３ PbI ３ It is more preferable that the compound is a compound represented by the formula:

[0040] The perovskite compounds that can be used to form the light absorbing layer 6 are compounds represented by AX and BX. ２Specifically, the perovskite compound can be synthesized by using an AX solution and a compound represented by the formula: ２ The perovskite compound can be synthesized by mixing the solution with BX and heating and stirring (one-step method). ２ The solution is applied, for example, onto the first overcoat layer (electron transport layer 5) to form a coating film, and the AX solution is applied onto the coating film, and then the BX ２ and AX (two-step method). Either the one-step method or the two-step method can be used to form the light-absorbing layer 6 (perovskite compound layer). The coating method is not particularly limited, but examples include screen printing, dip coating, and inkjet printing.

[0041] Examples of the organic solvent (contained in the coating liquid) used in the coating method for forming the light absorbing layer 6 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.

[0042] In addition to this, the coating liquid may contain additives such as an antioxidant, a viscoelasticity modifier, a preservative, and a curing catalyst.

[0043] When forming a film of the perovskite compound that constitutes the light absorption layer 6, if the temperature of the substrate 2 during film formation is low, the perovskite compound may become needle-like crystals. The needle-like crystals preferably have a length of approximately 10 μm to 20 μm and a width of approximately 1 μm to 5 μm, and are particularly preferably shaped like bamboo leaves. An organic binder resin may be applied as a filler to the spaces between the needle-like crystals. The organic binder resin is preferably a transparent, amorphous, and highly insulating material. Examples of organic binder resins include vinyl resins such as polymethyl methacrylate, polystyrene, and polyvinyl chloride; thermoplastic resins such as polycarbonate, polyester, polyester carbonate, polysulfone, polyarylate, polyamide, methacrylic resin, acrylic resin, polyether, polyacrylamide, and polyphenylene oxide; thermosetting resins such as epoxy resin, silicone resin, polyurethane, phenolic resin, alkyd resin, melamine resin, phenoxy resin, polyvinyl butyral, and polyvinyl formal; partially crosslinked products of these resins; and copolymer resins containing two or more of the structural units contained in these resins (insulating resins such as vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, and acrylonitrile-styrene copolymer resin). These film-forming resins can be used alone or in combination of two or more, but other resins can also be used as long as they meet the requirements.

[0044] A hole transport material may also be contained in the organic binder resin. Examples of hole transport materials that can be used include pyrazoline compounds, arylamine compounds, stilbene compounds, enamine compounds, polypyrrole compounds, polyvinylcarbazole compounds, polysilane compounds, butadiene compounds, polysiloxane compounds having aromatic amines in the side chain or main chain, polyaniline compounds, polyphenylene vinylene compounds, polythienene vinylene compounds, and polythiophene compounds. However, it is particularly preferable to use butadiene compounds and bisbutadiene compounds. Conductive particles such as carbon nanofibers and conductive polymers such as PEDOT / PSS can also be used. The hole transport material is preferably a compound that is resistant to crystallization, but may also contain a crystallization-preventing material such as an organic binder resin or a plasticizer to reliably prevent crystallization of the hole transport material. It is preferable that the organic solvent used when applying the material to the needle-shaped crystals is a solvent that does not disturb the needle-shaped crystals. Specifically, chlorobenzene, toluene, or the like may be preferably used. The coating method is not particularly limited, but it is preferable to employ, for example, a dip coating method, a spray coating method, a slide hopper coating method, or the like.

[0045] By coating the surfaces of the needle-like crystals of the perovskite compound and the exposed surface of the first overcoat layer (electron transport layer 5) with the aforementioned filler, current leakage between the first electrode 3 and the second electrode 8 can be prevented. In addition, the filler solidifies the spaces between the needle-like crystals, improving the rigidity of the perovskite crystals. Furthermore, because the needle-like crystals are coated with the filler, light incident on the photoelectric conversion layer 4 is multiple-scattered, improving the light absorption efficiency. This increases the amount of carrier extraction (short-circuit current) of the solar cell 20. Furthermore, by reducing the film thickness of the photoelectric conversion layer 4, a high open-circuit voltage can be obtained.

[0046] The second overcoat layer (hole transport layer 7) has the function of transporting holes generated in the light absorbing layer 6 to the second electrode 8. It is self-evident that the hole transport layer located on the hole transport side of the light absorbing layer or on the hole transport side of the light absorbing layer has the function of transporting holes, so confirmation is not required, as long as the solar cell functions as a solar cell. In other words, as long as the solar cell functions as a solar cell, any layer located on the hole transport side of the light absorbing layer or on the hole transport side of the light absorbing layer is called a hole transport layer. The hole transport layer 7 is formed on the light absorbing layer 6 (6a to 6c). The hole transport layer 7 is made of, for example, an inorganic material having a band gap of 2 eV or more and an ionization potential greater (shallower) than -5.3 eV. The thickness of the hole transport layer 7 can be, for example, approximately 30 nm to 100 nm. Specific materials for the hole transport layer 7 include copper oxide (Cu ２ Examples of the oxides include zinc oxide (ZnO), zinc sulfide (ZnS), and sulfides.

[0047] After the second overcoat layer (hole transport layer 7) is formed, a cut (electrode connection separation groove P2) is made in the layers formed on the substrate 2 (first electrode 3, photoelectric conversion layer 4 (electron transport layer 5, light absorption layer 6, hole transport layer 7)) by cutting, such as mechanical processing or laser processing, to connect the first electrode 3 of one solar cell 20 (20a or 20b) of two adjacent solar cells 20, 20 (20a, 20b), (20b, 20c) to the hole transport layer 7 and second electrode 8 of the other solar cell 20 (20b or 20c) (see Figures 4A, 6A, 6B, and 7A, described below). The electrode connection separation groove P2 is intended to ensure electrical connection between the first electrode 3 and the second electrode 8. It is desirable to electrically connect the first electrode 3 and the second electrode 8 embedded in the electrode connection separation groove P2 directly. The electrode connection separation groove P2 will be described in detail later. The term "layer" does not specify the thickness or width, and includes a pattern or island shape, or a layer having portions of different thickness. Preferably, the layer has a substantially constant thickness.

[0048] The second electrodes 8 (8a-8c) are provided on the second overcoat layer (hole transport layer 7) and are used to extract current generated by photovoltaic power generated in the photoelectric conversion layers 4 (4a-4c) of the solar cell 20 (20a-20c). Examples of the second electrodes 8 include metal films with a work function of 5 eV or greater. By using a metal with a high work function (5 eV or greater), the band structure at the interface between the hole transport layer 7 and the second electrode 8 is bent, allowing holes to flow more smoothly. Examples of materials for the second electrodes 8 include metals such as Ni, Pt, and Pd. The thickness of the second electrodes 8 is preferably approximately 50 nm to 150 nm. The hole transport layer 7 or the second electrodes 8 can be formed by, for example, sputtering or vacuum deposition.

[0049] At the interface between the hole transport layer 7 and the light absorption layer 6, holes generated in the light absorption layer 6 flow to the second electrode 8 via the hole transport layer 7, and are extracted. As for electrons, the hole transport layer 7 blocks the flow of electrons to the second electrode 8, which has the effect of suppressing carrier recombination at the interface between the hole transport layer 7 and the light absorption layer 6.

[0050] After the second electrode 8 is formed, in order to form a series-connected circuit of adjacent solar cells 20 (20a to 20c) on the base 2, a cutting process is performed to make a cut (separation groove P3 for cutting the second electrode) in the layers formed on the base 2 (electron transport layer 5, light absorption layer 6, hole transport layer 7, second electrode 8) (see Figures 4C, 7C, and 8B described below).

[0051] [Method of Manufacturing Solar Cell] FIG. 2 is a process diagram of an example of a method of manufacturing the solar cells 25, 25X.

[0052] As shown in FIG. 2, the method for manufacturing the solar cell 25 according to the present embodiment and the conventional solar cell 25X includes a first step S1 to a third step S3.

[0053] (Manufacturing Method Common to Solar Cell According to the Present Embodiment and Conventional Solar Cell) FIGS. 3A to 3C are cross-sectional views that schematically show an example of a step of forming a first overcoat layer (electron transport layer 5), an example of a step of forming a first electrode cutting separation groove P1, and an example of a step of forming a light absorption layer 6 and a second overcoat layer (hole transport layer 7), respectively, in the manufacturing process (first step S1) common to solar cell 25 according to the present embodiment and conventional solar cell 25X.

[0054] <First step> As shown in Figures 3A to 3C, in the first step S1 (see Figure 2), a photoelectric conversion layer 4 is disposed (laminated) on a surface (on the first electrode 3) opposite to the base 2 of the first electrode 3 formed on one surface (on the base 2) of the base 2.

[0055] Specifically, in the first step S1, first, an electron transport layer 5 (ETM: Electron Transport Material) or a hole transport layer 7 (HTM: Hole Transport Material) (in this example, the electron transport layer 5) is formed as a first overcoat film on a first electrode 3 [transparent conductive film: TCO (Transparent Conductive Oxide)] on a substrate 2 (S1-1: see FIG. 3A ).

[0056] Next, the first overcoat layer (electron transport layer 5) is subjected to cutting processing such as mechanical processing or laser processing to form first electrode cutting separation grooves P1 (S1-2: see FIG. 3B). Here, mechanical processing and laser processing are conventionally known processing techniques, and are processing using a cutting blade and cutting laser light, respectively. This cutting processing is also the same as the cutting processing when forming electrode connection separation grooves P2 and second electrode cutting separation grooves P3, which will be described later.

[0057] Next, a light absorbing layer 6 containing perovskite (PVSK: PeroVSKite) is formed in the first electrode cutting separation groove P1 and on the first overcoat layer (electron transport layer 5), and further, a hole transport layer 7 or an electron transport layer 5 (the hole transport layer 7 in this example) is formed on the light absorbing layer 6 as a second overcoat film (S1-3: see FIG. 3C ).

[0058] (Method of manufacturing conventional solar cell) Fig. 4A is a cross-sectional view schematically showing an example of a step of forming an electrode connection separation groove P2 in the manufacturing process (second step S2) of conventional solar cell 25X. Fig. 4B is a cross-sectional view schematically showing an example of a step of forming a second electrode 8 in the manufacturing process (second step S2) of conventional solar cell 25X. Fig. 4C is a cross-sectional view schematically showing an example of a step of forming a second electrode cutting separation groove P3 in the manufacturing process (third step S3) of conventional solar cell 25X. Fig. 5 is a cross-sectional view schematically showing a power generation state of conventional solar cell 25X in which electrode connection separation groove P2X is formed to a desired depth.

[0059] <Second Step> In the second step S2 (see FIG. 2), as shown in FIG. 4A, electrode connection separation grooves P2X are formed in the layers (electron transport layer 5, light absorption layer 6, hole transport layer 7) formed on the base 2 by cutting processing such as mechanical processing or laser processing (S2-1).

[0060] In the second step S2 (see FIG. 2), as shown in FIG. 4B, a second electrode 8 is formed in the electrode connection separation groove P2X and on the hole transport layer 7 (S2-2).

[0061] <Third Step> In the third step S3 (see FIG. 2), as shown in FIG. 4C , a separation groove P3 for cutting the second electrode is formed in the layers (electron transport layer 5, light absorption layer 6, hole transport layer 7, and second electrode 8) formed on the base 2 by cutting processing such as mechanical processing or laser processing.

[0062] Fig. 6A is a cross-sectional view schematically showing a state in which the electrode connection separation groove P2X is deeper than the desired depth in a configuration example of a conventional solar cell 25X. Fig. 6B is a cross-sectional view schematically showing a state in which the electrode connection separation groove P2X is shallower than the desired depth in a configuration example of a conventional solar cell 25X.

[0063] In the conventional manufacturing of solar cells 25X, when electrode connection separation grooves P2X are formed in photoelectric conversion layer 4 by cutting processing such as mechanical processing or laser processing, there is a large variation in the properties (film quality, film thickness, e.g., hardness) of each layer (e.g., photoelectric conversion layer 4) formed, making it difficult to perform the cutting processing stably. That is, in order to enable solar cell 25X to generate electricity efficiently (see FIG. 5), electrode connection separation grooves P2X should be cut to a desired depth (e.g., a position contacting the upper surface of first electrode 3) (see FIG. 4C). However, even if the same cutting conditions (cutting strength) are used for each solar cell 25X, the cutting strength may be too strong or too weak for each layer (electron transport layer 5, light absorption layer 6, hole transport layer 7, second electrode 8) formed on base 2, and the electrode connection separation grooves P2X cannot be stably formed to the desired depth, resulting in variation in the cutting depth (see FIGS. 6A and 6B).

[0064] For example, if the cutting strength is too strong (see FIG. 6A), the first electrode 3 is likely to be cut by the electrode connection separation groove P2X, and electrical connection with the second electrode 8 is likely to be lost. On the other hand, if the cutting strength is too weak (see FIG. 6B), the electrode connection separation groove P2X is unlikely to reach the first electrode 3 (so-called film residue of the photoelectric conversion layer 4 is likely to occur), and the resistance value between the first electrode 3 and the second electrode 8 is likely to increase. In either case, the characteristics of the solar cell 25X will vary greatly.

[0065] As described above, in the conventional manufacturing method of the solar cell 25X, it is not possible to reliably electrically connect the first electrode 3 and the second electrode 8, which ultimately reduces the power generation efficiency of the solar cell 25X. This is particularly noticeable when the photoelectric conversion layer 4 has a light absorption layer 6 containing an organic material, and is even more noticeable when the organic material contains a perovskite.

[0066] (Method for Manufacturing Solar Cell According to the Present Embodiment) In this regard, in the method for manufacturing solar cell 25 according to the present embodiment, solar cell 25 is manufactured as follows.

[0067] Next, a method for manufacturing solar cell 25 according to this embodiment will be described below with reference to Figures 7A to 9. As described above, the first step S1 is the same as the manufacturing process for conventional solar cell 25X, and therefore, a description thereof will be omitted here.

[0068] Fig. 7A is a cross-sectional view schematically showing an example of a step of forming electrode connection separation grooves P2 in the manufacturing process (second step S2) of solar cell 25 according to the present embodiment. Fig. 7B is a cross-sectional view schematically showing an example of a step of forming second electrodes 8 in the manufacturing process (second step S2) of solar cell 25 according to the present embodiment. Fig. 7C is a cross-sectional view schematically showing an example of a step of forming second electrode cutting separation grooves P3 in the manufacturing process (third step S3) of solar cell 25 according to the present embodiment.

[0069] Fig. 8A is an enlarged cross-sectional view showing a portion of the manufacturing process shown in Fig. 7A. Fig. 8B is an enlarged cross-sectional view showing a portion of an example of solar cell 25 manufactured by the manufacturing processes shown in Fig. 7A to Fig. 7C. Fig. 9 is a plan view of solar cell 25 manufactured by the manufacturing processes shown in Fig. 7A to Fig. 7C, viewed from the second electrode 8 side.

[0070] <Second Step> In the second step S2 (see FIG. 2), as shown in FIGS. 7A and 8A, the layers (electron transport layer 5, light absorption layer 6, hole transport layer 7) formed on one surface (on the base 2) of the base 2 are subjected to cutting processing such as mechanical processing or laser processing to form electrode connection separation grooves P2 having at least two portions T(1) to T(n) (n is an integer of 2 or more, n=7 in this example) (see FIG. 8A) with different depths (S2-1).

[0071] In this way, the electrode connection separation grooves P2 can be reliably formed in the photoelectric conversion layer 4.

[0072] In the second step S2 (see FIG. 2), as shown in FIG. 7B, a second electrode 8 is formed in the electrode connection separation groove P2 and on the hole transport layer 7 (S2-2).

[0073] 7C , in the third step S3 (see FIG. 2 ), a second electrode cutting separation groove P3 is formed by cutting, such as mechanical processing or laser processing, in the layers (electron transport layer 5, light absorption layer 6, hole transport layer 7, and second electrode 8) formed on the base 2. Here, the second electrode cutting separation groove P3 is a groove that cuts the second electrode 8 without cutting the first electrode 3.

[0074] 7A and 8A , in the manufacturing method of the solar cell 25 according to this embodiment, in the second step S2, the layers (electron transport layer 5, light absorption layer 6, hole transport layer 7) formed on one surface (on the base 2) of the base 2 are cut multiple times (by cutting multiple times with a cutting blade E or by irradiating multiple times with laser light F) to form multiple grooves Q(1) to Q(n) (n=7) arranged side by side in the plane direction W of the base 2, thereby forming electrode connection separation grooves P2. The multiple grooves Q(1) to Q(n) are deep in a direction V perpendicular or approximately perpendicular to the plane of the base 2.

[0075] In this way, the electrode connection separation grooves P2 can be reliably formed in the solar cell 25.

[0076] Incidentally, the multiple grooves Q(1) to Q(n) may be formed so that at least one pair of adjacent grooves [Q(i), Q(i+1)] (where i is an integer from 1 to n-1) among the multiple grooves Q(1) to Q(n) adjacent grooves [Q(1), Q(2)] to [Q(n-1), Q(n)] are spaced apart. In this case, however, the light receiving area of ​​the photoelectric conversion layer 4 is reduced by the total width of the grooves Q(1) to Q(n). This reduces the power generation efficiency of the solar cell 25.

[0077] In this regard, in the manufacturing method of solar cell 25 according to this embodiment, in second step S2, as shown in FIGS. 7A and 8A, a plurality of grooves Q(1) to Q(n) (n=7) are successively formed so as to be connected without gaps in the planar direction W [so as to reduce or eliminate boundaries between adjacent grooves [Q(i), Q(i+1)]].

[0078] By doing so, the width of the multiple groove portions Q(1) to Q(n) in the surface direction W can be reduced overall, thereby ensuring the light receiving area of ​​the photoelectric conversion layer 4 and thereby improving the power generation efficiency of the solar cell 25.

[0079] In the manufacturing method of the solar cell 25 according to this embodiment, in the second step S2, the cutting conditions (cutting strength) of the cutting process are changed each time cutting is performed so that the depths of at least two of the multiple grooves Q(1) to Q(n) (n=7 in this example) are different (so that the depths of all of the grooves are different from one another in this example).

[0080] For example, when performing cutting by mechanical processing or laser processing, when the cutting strength is made stronger than the reference strength, the relative position of the cutting blade E with respect to the workpiece (position where the relative distance is smaller than the reference distance) and the output of the laser light F (output larger than the reference output) are set so that the cutting dimension (digging amount) of the cutting blade E into the workpiece is increased. Also, when the cutting strength is made weaker than the reference strength, the relative position of the cutting blade E with respect to the workpiece (position where the relative distance is larger than the reference distance) and the output of the laser light F (output smaller than the reference output) are set so that the cutting dimension (digging amount) of the cutting blade into the workpiece is decreased.

[0081] By doing so, at least two portions T(1) to T(n) having different depths can be easily formed in the electrode connection separation groove P2.

[0082] As shown in FIG. 7C , the manufacturing method of the solar cell 25 according to this embodiment further includes a third step S3 of forming, by cutting, a separation groove P3 for cutting the second electrode 8 in the layers (electron transport layer 5, light absorption layer 6, hole transport layer 7, and second electrode 8) formed on one surface (on the base 2) of the base 2.

[0083] As described above, since the first electrode cutting separation groove P1 cuts the first electrode 3, even if the first electrode 3 is cut at one or more portions of the electrode connection separation groove P2 on the side of the first electrode cutting separation groove P1 [for example, T(n) (n=7 in this example) (see the α side in Figures 8A, 8B, and 9)], there will be no problem as long as at least one of the other portions [for example, T(1) to T(n-1) (see the β side in Figures 8A, 8B, and 9)] [for example, T(4) to T(6) in this example] reaches the first electrode 3 without cutting the first electrode 3.

[0084] In this regard, in the second step S2, the cutting conditions (cutting strength) of the cutting process are changed in stages so that at least two (in this example, all) groove portions Q(1) to Q(n) become gradually deeper as they move from the second electrode cutting separation groove P3 side toward the first electrode cutting separation groove P1 side.

[0085] For example, when performing cutting processing by mechanical processing or laser processing, when the cutting strength is increased in stages, the relative position of the cutting blade E with respect to the workpiece and the output of the laser light F are set each time cutting processing is performed so that the cutting dimension (digging amount) of the cutting blade E into the workpiece increases in stages.

[0086] In addition, in the second step S2, the cutting conditions (cutting strength) of the cutting process are changed in stages so that at least two (in this example, all) groove portions Q(1) to Q(n) become gradually shallower as they move from the first electrode cutting separation groove P1 side to the second electrode cutting separation groove P3 side.

[0087] For example, when performing cutting processing by mechanical processing or laser processing, when gradually weakening the cutting strength, the relative position of the cutting blade E with respect to the workpiece and the output of the laser light F are set each time cutting processing is performed so that the cutting dimension (digging amount) of the cutting blade E into the workpiece becomes gradually smaller.

[0088] By doing this, it is possible to easily form at least two groove portions that gradually become deeper as they move from the second electrode cutting separation groove P3 side to the first electrode cutting separation groove P1 side, or at least two groove portions that gradually become shallower as they move from the first electrode cutting separation groove P1 side to the second electrode cutting separation groove P3 side.

[0089] Note that each of the at least two portions T(1) to T(n) of different depths in the electrode connection separation groove P2 does not necessarily have a flat bottom. The shape of the bottom can be deformed in any way depending on the cutting conditions of the mechanical or laser cutting process, and therefore, of course, it does not have to be a flat bottom. While FIG. 7 conceptually illustrates the bottom of the electrode connection separation groove P2 as having a series of slopes, the bottom of the electrode connection separation groove P2 may actually have a series of slopes. Furthermore, the slopes may have different shapes in each cut groove portion, and therefore the electrode connection separation groove P2 may have an uneven bottom overall. The electrode connection separation groove P2 may, as a whole or in part, have a portion that gradually becomes deeper toward the first electrode cutting separation groove P1, or a portion that gradually becomes shallower from the first electrode cutting separation groove P1 toward the second electrode cutting separation groove P3.

[0090] In the example shown in Figures 7A and 8A, cutting is performed n times (n = 7) to form multiple grooves Q(1) to Q(n) that are connected (or adjacent). Note that each of the multiple grooves Q(1) to Q(n) is connected or adjacent to its neighbor, forming a continuous, large groove at the upper portion of the groove. However, the multiple grooves Q(1) to Q(n) do not necessarily need to be connected or adjacent, and may have a gap between them. In other words, adjacent grooves do not need to be connected to each other up to the upper portion of the groove, and may be separated. Regarding the cutting process in detail, as shown in Figure 8A, the cutting strength increases sequentially from groove Q(1) to groove Q(n). In the solar cell 25 shown in Figures 7C and 8B, which is manufactured using the manufacturing process shown in Figures 7A and 8B, the first electrode 3 and the second electrode 8 can be reliably contacted at the shaded areas γ to γ ​​(see Figure 8B) of grooves Q(4), Q(5), and Q(6). This makes it possible to reduce the contact resistance between the first electrode 3 and the second electrode 8 .

[0091] Here, since the grooves Q(1) to Q(n) become deeper in this order, even if the finishing of the photoelectric conversion layer 4 causes the photoelectric conversion layer 4 to become softer than the standard hardness, making it easier for the electrode connection separation groove P2 to become deeper, when the multiple grooves Q(1) to Q(n) become deeper in stages under the same cutting conditions (cutting strength), they will all become deeper in stages and uniformly deeper than in the case of the standard hardness, and the shaded areas γ to γ ​​where the first electrode 3 and second electrode 8 come into contact will shift toward the second electrode cutting separation groove P3 (to the right in Figure 8B), but conductivity between the first electrode 3 and the second electrode 8 can be ensured by any of the multiple grooves Q(1) to Q(n). On the other hand, if the finishing of the photoelectric conversion layer 4 makes the photoelectric conversion layer 4 harder than the standard hardness, making it easier for the electrode connection separation groove P2 to become shallower, and if the multiple grooves Q(1) to Q(n) become deeper in stages under the same cutting conditions (cutting strength), they will all become shallower in stages than in the case of the standard hardness, and even if the shaded areas γ to γ ​​where the first electrode 3 and the second electrode 8 come into contact shift toward the first electrode cutting separation groove P1 (to the left in Figure 8B), electrical continuity between the first electrode 3 and the second electrode 8 can be ensured by any of the multiple grooves Q(1) to Q(n).

[0092] This ensures stable conduction between the first electrode 3 and the second electrode 8 regardless of the finish of the photoelectric conversion layer 4, making it possible to manufacture solar cells 25 with little variation in characteristics.

[0093] 1, 7C, and 8B, in a solar cell 25 according to the present embodiment, the plurality of separation grooves P to P include an electrode connection separation groove P2 for electrically connecting the first electrode 3 and the second electrode 8. As shown in FIG. 8B, the electrode connection separation groove P2 has at least two portions T(1) to T(n) (n=7 in this example) of different depths (scribe structure).

[0094] According to the present embodiment, the electrode connection separation groove P2 has at least two portions T(1) to T(n) of different depths. Therefore, even if there is a large variation in the properties (film quality, film thickness, e.g., hardness) of each deposited layer (e.g., photoelectric conversion layer 4) among the individual solar cells 25, the first electrode 3 can be reached at any of the at least two portions T(1) to T(n) of the electrode connection separation groove P2 of different depths without cutting the first electrode 3. For example, even if the first electrode 3 is not reached at one portion T(1) of the electrode connection separation groove P2, or even if the first electrode 3 is cut at another portion T(7) of the electrode connection separation groove P2, the first electrode 3 can be reached at further portions T(4) to T(6) of the electrode connection separation groove P2. This ensures reliable electrical connection between the first electrode 3 and the second electrode 8, thereby improving the power generation efficiency of the solar cell 25. This is particularly effective when the photoelectric conversion layer 4 has a light absorption layer 6 containing an organic material, and is even more effective when the organic material contains a perovskite.

[0095] First Embodiment In this embodiment, the plurality of separation grooves P to P include a first electrode cutting separation groove P1 for cutting the first electrode 3.

[0096] Incidentally, since the first electrode cutting separation groove P1 cuts the first electrode 3, even if the first electrode 3 is cut at one or more portions [for example, T(n) (n=7)] of the electrode connection separation groove P2 on the side of the first electrode cutting separation groove P1, there will be no problem as long as the first electrode 3 is reached at one or more other portions [for example, T(1) to T(n-1)] without cutting the first electrode 3.

[0097] In this regard, in the present embodiment, the electrode connection separation groove P2 is deepest on the first electrode cutting separation groove P1 side.

[0098] In this way, because electrode connection separation groove P2 is deepest on the first electrode cutting separation groove P1 side, even if the first electrode 3 is cut at one or more portions [for example, T(n) (n=7)] on the first electrode cutting separation groove P1 side of electrode connection separation groove P2, one or more other portions [for example, T(1) to T(n-1)] on the second electrode cutting separation groove P3 side can reliably reach the first electrode 3 without cutting the first electrode 3. This makes it possible to more reliably electrically connect the first electrode 3 and the second electrode 8, and accordingly improves the power generation efficiency of solar cell 25.

[0099] Second Embodiment In this embodiment, the plurality of separation grooves P to P include a second electrode cutting separation groove P3 for cutting the second electrode 8. The electrode connection separation groove P2 becomes deeper gradually or in steps (in steps in this example) from the second electrode cutting separation groove P3 side toward the first electrode cutting separation groove P1 side.

[0100] By doing so, even if the first electrode 3 is cut at one or more portions [for example, T(n) (n=7)] on the first electrode cutting separation groove P1 side of the electrode connection separation groove P2, the first electrode 3 can be more reliably reached at one or more other portions [for example, T(1) to T(n-1)] on the second electrode cutting separation groove P3 side without being cut. This makes it possible to more reliably electrically connect the first electrode 3 and the second electrode 8, and accordingly improves the power generation efficiency of the solar cell 25.

[0101] [Third Embodiment] In this embodiment, at least two portions T(1) to T(n) (n=7) having different depths include one or more portions (T(n) in this example) that reach into the base 2, and / or one or more portions (T(5) to T(6) in this example) that are located in the first electrode 3.

[0102] By doing this, the more the portion that reaches into the base 2 and / or is located within the first electrode 3, the lower the resistance value between the first electrode 3 and the second electrode 8, and the more the power generation efficiency of the solar cell 25 can be improved.

[0103] In this embodiment, one or more portions [T(n)] that reach into the base 2 and / or one or more portions [T(5) to T(6)] that are located within the first electrode 3 have different depths.

[0104] By doing so, the resistance value between the first electrode 3 and the second electrode 8 can be further reduced, and as a result, the power generation efficiency of the solar cell 25 can be further improved.

[0105] [Fourth embodiment] In this embodiment, at least two portions T(1) to T(n) having different depths include one or more portions (T(1) to T(4) in this example) located within the photoelectric conversion layer 4.

[0106] By doing this, when the properties of each layer (photoelectric conversion layer 4) vary between individual solar cells 25-25 such that the electrode connection separation groove P2 is located on a side where it is difficult to reach the first electrode 3 (a side where the light absorption layer 6 is harder than the standard hardness), the first electrode 3 and the second electrode 8 can be reliably electrically connected in the other deeper parts (in this example, T(4) to T(6)) and the power generation efficiency of the solar cell 25 can be improved accordingly.

[0107] In this embodiment, one or more portions [T(1) to T(4)] located in the photoelectric conversion layer 4 have different depths.

[0108] This allows a margin for electrically connecting the first electrode 3 and the second electrode 8. This makes it easier to electrically connect the first electrode 3 and the second electrode 8, and accordingly improves the power generation efficiency of the solar cell 25.

[0109] Fifth Embodiment In this embodiment, the electrode connection separation groove P2 is composed of a plurality of grooves Q(1) to Q(n) arranged in parallel in the surface direction W of the base 2.

[0110] This allows the depth of each individual groove portion Q(1) to Q(n) to be changed, thereby ensuring the formation of at least two portions T(1) to T(n) with different depths.

[0111] Of the multiple groove portions Q(1) to Q(n), at least one pair of adjacent groove portions [Q(i), Q(i+1)] among the multiple groove portions [Q(1), Q(2)] to [Q(n-1), Q(n)] may be spaced apart, but in this embodiment, the multiple groove portions Q(1) to Q(n) are connected in the surface direction W of the base 2. Specifically, the multiple groove portions Q(1) to Q(n) are configured such that there are few or no boundaries between adjacent groove portions [Q(1), Q(2)] to [Q(n-1), Q(n)].

[0112] This makes it possible to further secure a light receiving area of ​​the photoelectric conversion layer 4 in the plane direction W of the base 2, and accordingly improve the power generation efficiency of the solar cell 25.

[0113] In order to improve the power generation efficiency of the solar cell 25, it is desirable that the light receiving area of ​​the photoelectric conversion layer 4 in the surface direction W of the base 2 is large, in other words, that the width of the electrode connection separation groove P2, i.e., the number of multiple groove portions Q(1) to Q(n), is small.

[0114] In this regard, in the present embodiment, the number Q(1) to Q(n) of the plurality of grooves is 10 or less (7 in this example). This makes it possible to ensure the light receiving area of ​​the photoelectric conversion layer 4 in the surface direction W of the base 2, thereby improving the power generation efficiency of the solar cell 25.

[0115] Furthermore, it is preferable that the number of the plurality of grooves Q(1) to Q(n) is 5 or less. This makes it possible to further ensure the light-receiving area of ​​the photoelectric conversion layer 4 in the surface direction W of the base 2, thereby further improving the power generation efficiency of the solar cell 25.

[0116] On the other hand, the greater the number of grooves Q(1) to Q(n), the easier it is to electrically connect the first electrode 3 and the second electrode 8.

[0117] In this regard, in this embodiment, the number of the plurality of grooves Q(1) to Q(n) is four or more.

[0118] This makes it possible to ensure a sufficient light receiving area of ​​the photoelectric conversion layer 4 while reliably connecting the first electrode 3 and the second electrode 8 electrically.

[0119] Furthermore, this does not exclude the possibility that each of the plurality of grooves Q(1) to Q(n) has portions with different depths. In other words, by having each of the plurality of grooves Q(1) to Q(n) have portions with different depths, it becomes possible to provide greater variety in the depth direction, and the effects of the grooves can be exerted even when the variation in groove depth due to manufacturing variations in each layer shifts in different directions, thereby further improving the power generation efficiency of solar cell 25.

[0120] The present disclosure is not limited to the above-described embodiments, but can be implemented in various other forms. Therefore, the embodiments are merely examples in all respects and should not be interpreted as being limiting. The scope of the present disclosure is defined by the claims and is not bound by the text of the specification. Furthermore, all modifications and variations within the equivalent scope of the claims are within the scope of the present disclosure.

[0121] This application claims priority from Japanese Patent Application No. 2023-138095, filed on August 28, 2023, the entire contents of which are incorporated herein by reference.

[0122] The present disclosure is applicable to applications for improving power generation efficiency.

[0123] 2 Base 20 Solar cell 25 Solar cell 3 First electrode 4 Photoelectric conversion layer 5 Electron transport layer 6 Light absorption layer 7 Hole transport layer 8 Second electrode P to P Multiple separation grooves P1 Separation groove for first electrode disconnection P2 Separation groove for electrode connection P3 Separation groove for second electrode disconnection Q(1) to Q(n) Multiple groove portions S1 First step S2 Second step S3 Third step T(1) to T(n) At least two portions with different depths V Vertical or approximately vertical direction W Planar direction

Claims

1. A solar cell having a plurality of solar cell cells in which a first electrode, a photoelectric conversion layer, and a second electrode are arranged in this order on one surface of a base, and the layer formed on the one surface of the base is divided by a plurality of separation grooves, wherein the plurality of separation grooves include electrode connection separation grooves for electrically connecting the first electrode and the second electrode, and the electrode connection separation groove has at least two portions with different depths.

2. A solar cell as described in claim 1, wherein the plurality of separation grooves include a first electrode cutting separation groove for cutting the first electrode, and the electrode connection separation groove is deepest on the side of the first electrode cutting separation groove.

3. A solar cell as described in claim 2, wherein the plurality of separation grooves include a second electrode cutting separation groove for cutting the second electrode, and the electrode connection separation groove becomes gradually or stepwise deeper from the second electrode cutting separation groove side toward the first electrode cutting separation groove side.

4. A solar cell according to any one of claims 1 to 3, characterized in that the at least two portions having different depths include one or more portions that reach into the base body and / or one or more portions that are located within the first electrode.

5. A solar cell according to claim 4, characterized in that the one or more portions extending into the base body and / or the one or more portions located within the first electrode have different depths.

6. A solar cell according to any one of claims 1 to 5, characterized in that the at least two portions having different depths include one or more portions located within the photoelectric conversion layer.

7. A solar cell according to claim 6, characterized in that the one or more portions located within the photoelectric conversion layer have different depths.

8. A solar cell according to any one of claims 1 to 7, characterized in that the electrode connection separation groove is composed of a plurality of groove portions arranged in parallel in the surface direction of the base body.

9. A solar cell according to claim 8, characterized in that the plurality of grooves are connected in the surface direction of the base body.

10. A solar cell according to claim 8 or 9, characterized in that the number of said plurality of grooves is 10 or less.

11. A solar cell according to any one of claims 1 to 10, characterized in that the photoelectric conversion layer has a light absorption layer containing an organic material.

12. The solar cell according to claim 11, characterized in that the organic material comprises a perovskite.

13. A method for manufacturing a solar cell as claimed in any one of claims 1 to 12, comprising: a first step of arranging the photoelectric conversion layer on a surface opposite the substrate of the first electrode formed on one surface of the substrate; and a second step of forming the electrode connection separation groove having at least two portions with different depths by cutting the layer formed on the one surface of the substrate.

14. A method for manufacturing a solar cell as described in claim 13, characterized in that in the second step, the electrode connection separation grooves are formed by performing cutting work multiple times on a layer formed on one surface of the base to form multiple groove portions arranged side by side in the surface direction of the base.

15. A method for manufacturing a solar cell according to claim 14, characterized in that in the second step, the plurality of grooves are formed so as to be connected in the surface direction of the base.

16. A method for manufacturing a solar cell as described in claim 14 or 15, characterized in that in the second step, the cutting conditions of the cutting process are changed each time the cutting process is performed so that the depths of at least two of the plurality of groove portions differ.

17. A method for manufacturing a solar cell as described in claim 16, further comprising a third step of forming a separation groove for cutting a second electrode by the cutting process in a layer formed on the one surface of the base, wherein in the second step, cutting conditions for the cutting process are changed in stages so that the at least two groove portions become gradually deeper as they move from the separation groove for cutting a second electrode side to the separation groove for cutting a first electrode side, or so that the at least two groove portions become gradually shallower as they move from the separation groove for cutting a first electrode side to the separation groove for cutting a second electrode side.

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