Solar cells and their manufacturing methods

Abstract

The solar cell (25) comprises a plurality of solar cell units (20-20). The plurality of solar cell units (20-20) are arranged sequentially on one side of a substrate (2) with a first electrode (3), a photoelectric conversion layer (4), and a second electrode (8). The layer formed on one side of the substrate (2) is divided by a plurality of separation grooves (P1-P3). The plurality of separation grooves (P1-P3) includes an electrode connection separation groove (P2) for electrically connecting the first electrode (3) and the second electrode (8). The electrode connection separation groove (P2) has at least two portions (T(1)-T(n)) of different depths.

Description

Technical Field

[0001] This disclosure relates to solar cells and methods for manufacturing the same. The solar cells have a plurality of solar cell units, wherein a first electrode, a photoelectric conversion layer, and a second electrode are sequentially disposed on one side of a substrate, and the layer formed on one side of the substrate is divided by a plurality of separation grooves. Prior Art

[0002] In the manufacture of solar cells, first, a first electrode is formed on one side of a substrate, and then a photoelectric conversion layer (for example, a photoelectric conversion layer including an electron transport layer, a light absorption layer, and a hole transport layer) is formed on the side of the substrate opposite to the first electrode. Furthermore, the photoelectric conversion layer is cut by machining (mechanical scribing), laser machining (laser scribing), or the like to form an electrode connection separation groove for electrically connecting the first electrode and the second electrode (for example, see Patent Documents 1 and 2). [Prior Art Literature] [Patent Document]

[0003] Patent Document 1: Japanese Patent Application Publication No. 2011-077104 Patent Document 2: Japanese Patent Application Laid-Open No. 2013-149698 Summary of the Invention

[0004] [Problems to be solved by the invention]

[0005] However, in conventional solar cell manufacturing, when cutting is used to form the electrode connection separation trench, the properties (film quality, thickness, and hardness, for example) of each layer (e.g., the photoelectric conversion layer) formed vary widely, making stable cutting difficult. Specifically, in order for solar cells to generate electricity efficiently, the electrode connection separation trench must be cut to a desired depth (e.g., to the point where the surface opposite the first electrode and the substrate contacts the substrate). However, even when the same cutting conditions (cutting strength) are used for each solar cell, the cutting strength may be too strong or too weak for each layer formed, preventing stable formation of the electrode connection separation trench to the desired depth and causing variations in cutting depth.

[0006] For example, if the cutting force is too strong, the first electrode may be severed, resulting in a loss of electrical connection between the first and second electrodes. Alternatively, if the cutting force is too weak, the electrode connection separation trench may not reach the first electrode (residual film forming the photoelectric conversion layer). This increases the resistance between the first and second electrodes. In either case, the variation in solar cell characteristics increases.

[0007] Thus, in conventional solar cell manufacturing, it is impossible to reliably electrically connect the first and second electrodes, resulting in a decrease in the solar cell's power generation efficiency. This is particularly significant when the photoelectric conversion layer includes a light-absorbing layer made of an organic material, and the organic material includes perovskite.

[0008] Therefore, an object of the present disclosure is to provide a solar cell capable of improving power generation efficiency and a method for manufacturing the same. [Technical means to solve the problem]

[0009] In order to solve the above problems, the following solar cell and its manufacturing method are provided.

[0010] (1) Solar cells The solar cell disclosed herein comprises a plurality of solar cell units, wherein a first electrode, a photoelectric conversion layer, and a second electrode are sequentially arranged on a surface of one side of a substrate, and the layers formed on the surface of the one side of the substrate are divided by a plurality of separation grooves, wherein the plurality of separation grooves include an electrode connection separation groove for electrically connecting the first electrode and the second electrode, and the electrode connection separation groove has at least two portions of different depths.

[0011] (2) Method for manufacturing solar cells The present disclosure relates to a method for manufacturing a solar cell of the above-mentioned invention, which comprises: a first step of configuring the photoelectric conversion layer on the surface of the first electrode formed on the surface of one side of the substrate opposite to the substrate; and a second step of forming an electrode connection separation groove by cutting the layer formed on the surface of the one side in the substrate, the electrode connection separation groove having at least two portions of different depths. [Effects of the Invention]

[0012] According to the present disclosure, the power generation efficiency of a solar cell can be improved. Simple diagram description

[0013] FIG1 is a cross-sectional view schematically showing an example of the general configuration of a solar cell according to an embodiment of the present invention. FIG2 is a process diagram of a method for manufacturing a solar cell. 3A is a cross-sectional view schematically showing an example of a step of forming a first covering layer in a manufacturing step (first step) common to the solar cell according to the present embodiment and a conventional solar cell. 3B is a cross-sectional view schematically showing an example of a step of forming a first electrode cutting separation groove in a manufacturing step (first step) common to the solar cell according to the present embodiment and a conventional solar cell. 3C is a cross-sectional view schematically showing an example of a step of forming a light absorbing layer and a second covering layer in a manufacturing step (first step) common to the solar cell according to the present embodiment and a conventional solar cell. FIG4A is a cross-sectional view schematically showing an example of a step of forming an electrode connection separation groove in a conventional solar cell manufacturing process (second step). FIG4B is a cross-sectional view schematically showing an example of a step of forming a second electrode in a conventional solar cell manufacturing process (second step). 4C is a cross-sectional view schematically showing an example of a step of forming a second electrode cutting separation groove in a conventional solar cell manufacturing process (third step). FIG5 is a cross-sectional view schematically showing a power generation state of a conventional solar cell in which an electrode connection isolation groove is formed at a desired depth. FIG6A is a cross-sectional view schematically showing a state in which an electrode connection separation trench is deeper than a desired depth in a conventional solar cell configuration example. 6B is a cross-sectional view schematically showing a state in which the electrode connection separation trench is shallower than a desired depth in a conventional solar cell configuration example. 7A is a cross-sectional view schematically showing an example of a step of forming an electrode connection separation groove in the manufacturing process (second step) of the solar cell according to the present embodiment. 7B is a cross-sectional view schematically showing an example of a step of forming a second electrode in the manufacturing process (second step) of the solar cell according to the present embodiment. 7C is a cross-sectional view schematically showing an example of a step of forming a second electrode cutting separation groove in the manufacturing process (third step) of the solar cell according to the present embodiment. FIG8A is an enlarged cross-sectional view showing a portion of the manufacturing process shown in FIG7A in an enlarged manner. FIG8B is an enlarged cross-sectional view showing a portion of an example of a solar cell manufactured through the manufacturing steps shown in FIG7A to FIG7C . FIG9 is a plan view of the solar cell manufactured through the manufacturing steps shown in FIG7A to FIG7C , viewed from the second electrode side. Implementation Method

[0014] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same reference numerals are given to the same components. Their names and functions are also the same. Therefore, detailed descriptions of them will not be repeated. As an example, the base side is shown as the lower side and the opposite side as the upper side, but this is only for convenience and does not refer to the orientation of the installation or a recommended orientation. As long as there is no contradiction, even if the top and bottom are reversed or the left and right are changed, it is still applicable.

[0015] (First embodiment) Figure 1 is a cross-sectional view schematically showing an example of the general configuration of the solar cell 25 of this embodiment.

[0016] As shown in Figure 1, the solar cell 25 includes: a substrate 2 (a substrate or a substrate identical to a base plate, or a substrate comprising a substrate or a base plate, which is also the case in this invention); a first electrode 3 (3a-3c in the example) disposed on one side of the substrate 2 (on the substrate 2); a photoelectric conversion layer 4 (4a-4c in the example) disposed on the side of the first electrode 3 opposite to the substrate 2 (on the first electrode 3); and a second electrode 8 (8a-8c in the example) disposed on the side of the photoelectric conversion layer 4 opposite to 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 sequentially on the substrate 2. Furthermore, the case where the first electrode 3, the photoelectric conversion layer 4, and the second electrode 8 are arranged sequentially to ground is described here, but they are not necessarily necessarily arranged to ground. Other cases are not excluded. That is, the first electrode 3, the photoelectric conversion layer 4, and the second electrode 8 can be arranged sequentially. In addition, not all three are required to be present.

[0017] The photoelectric conversion layer 4 is composed of a capping 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 capping layer include the electron transport layer 5 and the hole transport layer 7. In this example, the solar cell 25 comprises 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 a substrate 2. Alternatively, the solar cell 25 may comprise 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 a substrate 2.

[0018] The solar cell 25 has a plurality of solar cell units 20 to 20 (20a to 20c in the example shown in the figure). In the solar cell 25, the layer formed on the substrate 2 is divided by a plurality of separation grooves P to P (P1 to P3 in this example), thereby forming a plurality of solar cell units 20 to 20.

[0019] In 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. 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) form a plurality of solar cell units 20-20 (20a-20c). In solar cell 25, adjacent solar cell units 20, 20 are electrically connected in series. Therefore, solar cell 25 is a series-connected solar cell. In solar cell 25, the number of solar cell units 20-20 connected in series is not particularly limited, as long as there are a plurality of solar cell units 20-20.

[0020] Examples of materials that can be used for the substrate 2 include glass substrates and organic thin films. Specifically, materials constituting the organic film include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyetherimide (PEI), polytetrafluoroethylene (PTFE), polyamide imide (PAI), polyethylene naphthalate (PEN), and organosilicon. However, other resins may also be used as long as they meet the requirements. The thickness of the organic thin film forming the substrate 2 is preferably 50 μm to 100 μm.

[0021] The first electrode 3 is disposed on the substrate 2 and is used to extract the current generated by the photoelectromotive force of the photoelectric conversion layer 4 of the solar cell 20. When the substrate 2 is on the light-incident side, the first electrode 3 can be a transparent conductive film. Transparent conductive films can be made of, for example, conductive transparent materials such as aluminum-doped zinc oxide (AZO), indium zinc oxide (IZO), gallium-doped zinc oxide (GZO), fluorine-doped tin oxide (FTO), and indium tin oxide (ITO). Alternatively, the first electrode 3 can be formed by patterning fine lines of a conductive metal such as silver onto an oxide of a conductive transparent material. Transparent means transmitting light, but, except in cases where there is slight reflection or absorption, it also means being disposed on the light-receiving side of the solar cell (including the area where light is incident, which applies to this disclosure). Therefore, it can be transparent at least on the light-receiving side. In other words, a transparent conductive film refers to a conductive film disposed on the light-receiving side of the solar cell. The term "film" is not limited to thickness or width and also includes patterned or island-shaped films, as well as films with portions of varying thickness. The term "film" preferably refers to a component having a generally constant thickness. Furthermore, unless otherwise specified, "approximately" or "to an extent" refers to the margin of manufacturing error, preferably indicating that a deviation of plus or minus 15% of the numerical value is permitted.

[0022] Preferably, the thin-film resistance of the first electrode 3 is 10 Ω / sq or less. More preferably, the light transmittance of the first electrode 3 is 80% or more. Examples of methods for forming the first electrode 3 include sputtering, vacuum evaporation, coating / printing of conductive paste, and low-temperature sintering.

[0023] When a transparent conductive film is formed on the substrate 2, the transparent conductive film formed on the substrate 2 is divided into sections for each solar cell unit 20. For example, the solar cell 25 shown in FIG1 contains three solar cell units 20 (20a~20c), therefore, the transparent conductive film is divided by a first electrode cutting separation groove P1 to form three first electrodes 3 (3a~3c). The first electrode cutting separation groove P1 may also be filled with a light-absorbing layer 6 or the like.

[0024] The photoelectric conversion layer 4 is a layer that converts light energy into electrical energy. Specifically, the photoelectric conversion layer 4 receives light and generates a photoelectromotive force. The photoelectric conversion layer 4 is disposed on the first electrode 3. In this example, the photoelectric conversion layer 4 has an electron transport layer 5, a light absorption layer 6 disposed on the electron transport layer 5, and a hole transport layer 7 disposed on the light absorption layer 6.

[0025] 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. Furthermore, as long as the solar cell functions as a solar cell, the electron transport layer, located closer to the electron transport side than the light-absorbing layer or on the electron transport side of the light-absorbing layer, has the function of transporting electrons, which is obvious and does not require confirmation. That is, as long as the solar cell functions as a solar cell, the layer closer to the electron transport side than the light-absorbing layer or on the electron transport side of the light-absorbing layer is referred to as the electron transport layer. The electron transport layer 5 is composed of a material that allows electrons generated in the light-absorbing layer 6 to easily transfer to the electron transport layer 5, and electrons in the electron transport layer 5 to easily transfer to the first electrode 3. Alternatively, the electron transport layer 5 can serve as a seed layer for the orientation growth of the light-absorbing layer 6. This improves the crystal quality of the perovskite compound that constitutes the light-absorbing layer 6. The electron transport layer 5 is, for example, a titanium oxide (TiO2) layer. Furthermore, a TiN layer or a TiO2-xNx layer may be formed on the surface of the titanium oxide contained in this titanium oxide layer. The thickness of the electron transport layer 5 can be, for example, approximately 100 nm to 250 nm.

[0026] For example, a titanium oxide (TiO2) layer constituting the electron transport layer 5 can be formed as a first covering layer with a film thickness of about 100 nm to 250 nm on the transparent conductive film that becomes the first electrode 3. Examples of methods for forming the covering layer include sputtering film forming methods, vacuum evaporation methods, conductive paste coating / printing techniques, and formation methods based on low-temperature firing techniques. For example, a titanium oxide (TiO2) paste for low-temperature firing can be applied to the transparent conductive film and fired at a temperature below 150°C to form a seed layer. The crystal structure of the TiO2 contained in the TiO2 layer 12 is preferably a rutile structure. In addition, the surface of the TiO2 is subjected to a surface modification treatment to form a TiN (NaCl structure) layer with a film thickness of about 5 to 30 nm on the surface of the TiO2.

[0027] The lattice constants of TiO₂ (rutile structure) and TiN (NaCl structure) are well matched, allowing a good interface with few defects to be formed between the TiO₂ layer and the TiN layer. The formation of a mixed crystal material, TiO₂-xNx, near the interface continuously changes the lattice constant, suppressing the generation of interface defects. When the TiN layer is exposed to air after surface modification with nitrogen plasma, a reoxidation layer several nanometers thick forms on the surface. However, the thinness of the formed TiO₂ layer prevents structural relaxation of the lattice constant, maintaining the lattice constant of the underlying TiN layer.

[0028] The light absorption layer 6 (6a~6c) is a layer that absorbs light incident on the photoelectric conversion layer 4 (4a~4c) to generate electrons and holes. The electrons move to the electron transport layer 5, and the holes move to the hole transport layer 7.

[0029] The light absorbing layer 6 includes a perovskite compound or an organic-inorganic hybrid compound. This compound can generate electrons and holes in the light absorbing layer 6. The thickness of the light absorbing layer 6 is preferably within a range of approximately 500 nm to 1000 nm.

[0030] For example, as shown in FIG. 3B described later, after cutting a cut (first electrode separation groove P1 ) by machining, laser machining, or the like, a perovskite compound is formed on the first cover layer (electron transport layer 5 ) to form the light absorption layer 6 .

[0031] The perovskite compound is composed of compounds represented by the general formula: ABX 3···(1). However, the preferred composition ratio is 1:1:3, but it is not necessarily 1:1:3. The content of each element can also be adjusted appropriately. Each constituent element does not need to be the same. As long as the light absorption layer has photoelectric conversion function, it can have the freedom of the described composition. In the general formula (1), A is an organic molecule (containing an organic group or an organic cation, which is the same in this disclosure) or an inorganic atom or molecule (containing an inorganic group or an inorganic cation, which is the same in this disclosure) or a combination thereof, B is a metal atom or molecule (containing a metal cation, which is the same in this disclosure), and X is a halogen atom or molecule, a chalcogenide atom or molecule (containing a halogen anion or a chalcogenide anion, which is the same in this disclosure). In the general formula (1), the three Xs can be the same or different from each other. Since the perovskite compound is contained in the light absorption layer, it can absorb light and convert it into electricity. This should be taken into consideration. That is, as a perovskite compound, it can be known, for example, to have organic molecules, metal atoms and halogen atoms. Furthermore, for perovskite compounds, as long as the light-absorbing layer has photoelectric conversion functionality, it is sufficient to detect elements equivalent to A, B, and X. For example, as an organic molecule, molecules containing carbon, nitrogen, and hydrogen are preferred; therefore, detecting carbon, nitrogen, hydrogen, metallic elements, and halogen or chalcogenide elements is sufficient. Alternatively, as a perovskite compound, the presence of A, B, and X is sufficient; for example, the presence of inorganic atoms, metallic atoms, and halogen atoms is sufficient. Moreover, for perovskite compounds, as long as the light-absorbing layer has photoelectric conversion functionality, it is sufficient to confirm the presence of elements equivalent to A, B, and X by detecting them. For example, cesium or rubidium is preferred as inorganic atoms; therefore, detecting cesium or rubidium, metallic elements, and halogen or chalcogenide elements is sufficient. In addition, since the light-absorbing layer has photoelectric conversion functionality, it is naturally necessary to confirm the presence of a crystal structure, based on the presence of a crystal structure. The inclusion of substances other than perovskite compounds in the light-absorbing layer is not excluded.

[0032] In addition, the light-absorbing layer can contain organic-inorganic hybrid compounds. Organic-inorganic hybrid compounds refer to compounds containing both inorganic and organic components. Solar cell units using perovskite compounds, which are included in organic-inorganic hybrid compounds, are also called organic-inorganic hybrid solar cell units. Typically, "organic" refers to materials composed of multiple carbon atoms as constituent elements. It should be noted that graphite, graphene, carbon nanowires, carbon nanofibers, carbon nanotubes, carbon used as electrodes, carbon black, and other carbon materials are not specifically considered organic. That is, organic refers to substances that, excluding the aforementioned carbon materials such as graphite, contain multiple carbon atoms as one of their constituent elements. "Inorganic" refers to substances that are not organic.

[0033] In the general formula (1), the organic molecule represented by A includes, for example, alkylamine, alkylammonium and nitrogen-containing heterocyclic compounds. In the perovskite compound (1), the organic molecule represented by A may be only one organic molecule or two or more organic molecules.

[0034] The alkylamines include, for example, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, ethylmethylamine, methylpropylamine, butylmethylamine, methylpentylamine, hexylmethylamine, ethylpropylamine, ethylbutylamine, and the like.

[0035] Alkylammonium is the ionization product of the above-mentioned alkylamines. Alkylamines include, for example, methylammonium (CH3NH3), 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, etc.

[0036] Nitrogen-containing heterocyclic compounds include, for example, imidazole, oxazole, pyrrole, aziridine, aziridine, azetidine, azetadiene, oxazole, imidazoline and oxazole. The nitrogen-containing heterocyclic compound may also be an ionized product. As the nitrogen-containing heterocyclic compound of the ionized product, phenylethylammonium is preferred.

[0037] In the general formula (1), as the organic molecule represented by A, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, methylammonium, ethylammonium, propylammonium, butylammonium, pentylammonium, hexylammonium or phenylethylammonium is preferred, amine, ethylamine, propylamine, methylammonium, ethylammonium or propylammonium is more preferred, and methylammonium is more preferred.

[0038] In general formula (1), the metal atom represented by B includes, for example, lead, tin, zinc, titanium, antimony, bismuth, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, and europium. In perovskite compounds, the metal atom represented by B can be a single metal atom or two or more metal atoms. From the viewpoint of improving the light absorption and charge generation properties of perovskite compounds, the metal atom represented by B is preferably a lead atom or a tin atom. From the viewpoint of reducing lead content, a tin atom is preferred.

[0039] In the general formula (1), examples of the halogen atom represented by X include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and examples of the chalcogen atom include an oxygen atom, a sulfur atom, a selenium atom, and a tellurium atom. In the perovskite compound, the halogen atom or chalcogen atom represented by X may be one or more. From the perspective of the perovskite compound being able to utilize light in a wide wavelength range, the halogen atom represented by X is preferably an iodine atom. Specifically, among 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.

[0040] The perovskite structure compound contained in the light-absorbing layer 6 is preferably a compound represented by CH 3NH 3PbX 3 (where X is a halogen atom), more preferably a compound in which X is an iodine atom in the formula CH 3NH 3PbX 3 (i.e., a compound represented by CH 3NH 3PbI 3).

[0041] The perovskite compound that can be used to form the light absorbing layer 6 can be synthesized by using the compound represented by AX and the compound represented by BX2 as raw materials. Specifically, the perovskite compound can be synthesized by mixing the AX solution and the BX2 solution and heating and stirring (one-step method). In addition, the perovskite compound can be synthesized by applying the BX2 solution, for example, on the first covering layer (electron transport layer 5) to form a coating film, applying the AX solution on the coating film, and reacting BX2 with AX (two-step method). Either the one-step method or the two-step method can be used in the formation of the light absorbing layer 6 (layer of the perovskite compound). As a coating method, there is no particular limitation, and examples thereof include screen printing, dip coating, inkjet printing, etc.

[0042] Examples of organic solvents used in the coating method for forming the light-absorbing layer 6 (included in the coating solution) include aromatic hydrocarbons such as toluene, xylene, 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; fluorinated solvents such as hexafluoroisopropanol; nonpolar solvents such as N,N-dimethylformamide and N,N-dimethylsulfoxide; alcohols such as methanol, ethanol, and isopropyl alcohol; and ethanol ether solvents such as ethylene glycol and diethylene glycol methyl ether. These solvents can be used alone or as a mixture. Water can also be mixed with these solvents. Among these solvents, non-halogen organic solvents can also be appropriately used, considering the Earth's environment.

[0043] In addition, the coating liquid may contain additives such as an antioxidant, a viscoelasticity regulator, a preservative, and a curing catalyst.

[0044] When forming the perovskite compound film that constitutes the light-absorbing layer 6, if the substrate 2 temperature during film formation is low, the perovskite compound may form needle-shaped crystals. Needle-shaped crystals are approximately 10 to 20 μm long and preferably 1 to 5 μm wide, with a bamboo-leaf-like shape being particularly preferred. An organic binder resin may be applied as a filler in the spaces between the needle-shaped crystals. The organic binder resin is preferably transparent, amorphous, and highly insulating. Examples of organic binder resins include vinyl resins such as polymethyl methacrylate, polystyrene, and polyvinyl chloride; thermoplastic resins such as polycarbonate, polyester, polymethylethylene carbonate, polysulfone, polyarylate, polyamide, methacrylic resin, acrylic resin, polyether, polyacrylamide, and polyphenylene ether; thermosetting resins such as epoxy resin, silicone resin, polyurethane, phenolic resin, alkyd resin, melamine resin, phenoxy resin, polyvinyl butyral, and polyvinyl formal; partially cross-linked products of these resins; and copolymer resins containing two or more of the structural units present in these resins (insulating resins such as vinyl chloride-vinyl acetate copolymer resins, vinyl chloride-vinyl acetate-maleic anhydride copolymer resins, and acrylonitrile-styrene copolymer resins). These film-forming resins may be used alone or in combination of two or more. However, other resins may also be used as long as the requirements are met.

[0045] In addition, a hole transport material may also be included in the organic binder resin. As hole transport materials, pyrazoline compounds, aromatic amine compounds, stilbene compounds, enamine compounds, polypyrrole compounds, polyvinyl azole compounds, polysilane compounds, butadiene compounds, polysiloxane compounds with aromatic amines on the side chain or main chain, polyaniline compounds, polystyrene compounds, polyvinyl alcohol compounds, polythiophene compounds, etc. can be used. Butadiene compounds and bisbutadiene compounds are particularly preferred. In addition, conductive microparticles such as carbon nanofibers and conductive polymers such as PEDOT / PSS can be mentioned. The hole transport material is preferably a compound that is difficult to crystallize. However, in order to reliably prevent the crystallization of the hole transport material, it can also be a composition containing an organic binder resin or a plasticizer to prevent crystallization. In addition, the organic solvent used when coating on the needle-shaped crystals is preferably a solvent that does not disturb the needle-shaped crystals. Specifically, solvents such as chlorobenzene and toluene can be preferably used. In addition, the coating method is not particularly limited, and preferably uses, for example, a dip coating method, a spray coating method, a slide hopper coating method, etc.

[0046] By coating the surfaces of the needle-shaped perovskite compound crystals and the exposed surface of the first capping layer (electron transport layer 5) with the aforementioned filler, current leakage between the first electrode 3 and the second electrode 8 can be prevented. Furthermore, since the needle-shaped crystals are fixed by the filler, the rigidity of the perovskite crystals is improved. Furthermore, since the needle-shaped crystals are coated with the filler, light incident on the photoelectric conversion layer 4 undergoes multiple scattering, thereby improving light absorption efficiency. This increases the carrier extraction capacity (short-circuit current) of the solar cell 20. Furthermore, by reducing the thickness of the photoelectric conversion layer 4, a higher open-circuit voltage can be achieved.

[0047] The second covering layer (hole transport layer 7) is a layer that has the function of transferring holes generated in the light-absorbing layer 6 to the second electrode 8. Furthermore, as long as the solar cell functions as a solar cell, the hole transport function of the hole transport layer, which is closer to the hole transport side of the light-absorbing layer or located on the hole transport side of the light-absorbing layer, is obvious and does not require confirmation. In other words, as long as the solar cell functions as a solar cell, the layer closer to the hole transport side of the light-absorbing layer or located on the hole transport side of the light-absorbing layer is referred to as the hole transport layer. The hole transport layer 7 is formed on the light-absorbing layer 6 (6a-6c). The hole transport layer 7 is composed of, for example, an inorganic material with a band gap of 2 eV or greater and an ionization potential greater than (shallower than) -5.3 eV. The thickness of the hole transport layer 7 can be, for example, between 30 nm and 100 nm. Specific materials constituting the hole transport layer 7 include oxides and sulfides such as copper oxide (Cu2O) and zinc sulfide (ZnS).

[0048] After forming the second covering layer (hole transport layer 7), in order to connect the first electrode 3 of one solar cell 20 (20a or 20b) of two adjacent solar cells 20 (20a, 20b), (20b, 20c) to the hole transport layer 7 and second electrode 8 of the other solar cell 20 (20b or 20c), a cutout (electrode connection separation groove P2) is made in the layers (first electrode 3, photoelectric conversion layer 4 (electron transport layer 5, light absorption layer 6, hole transport layer 7)) formed on the substrate 2 by machining, laser processing, or other cutting processes (see Figures 4A, 6A, 6B, and 7A described later). Electrode connection separation groove P2 ensures electrical connection between the first electrode 3 and the second electrode 8. Preferably, the first electrode 3 is directly electrically connected to the second electrode 8 embedded in the electrode connection separation groove P2. The electrode connection separation groove P2 will be described in detail later. Furthermore, the term "layer" is not limited to thickness or width; it also includes patterned or island-shaped layers, and layers with portions of varying thickness. A layer preferably refers to a component with approximately a certain thickness.

[0049] The second electrode 8 (8a-8c) is provided on the second covering layer (hole transport layer 7) and is an electrode for extracting the current generated by the photoelectromotive force of the photoelectric conversion layer 4 (4a-4c) of the solar cell unit 20 (20a-20c). As an example of the second electrode 8, a metal film with a work function of 5 eV or greater can be cited. Since the second electrode 8 is composed of a metal with a deep work function (5 eV or greater), a bending of the energy band structure occurs at the interface between the hole transport layer 7 and the second electrode 8, which smoothes the flow of holes. Examples of the material of the second electrode 8 include metals such as Ni, Pt, and Pd. The film thickness of the second electrode 8 is preferably 50 nm to 150 nm. The hole transport layer 7 or the second electrode 8 can be formed, for example, by sputtering or vacuum evaporation.

[0050] At the interface between the hole transport layer 7 and the light absorbing layer 6, holes generated in the light absorbing layer 6 flow through the hole transport layer 7 toward the second electrode 8, allowing holes to be extracted. Regarding electrons, the hole transport layer 7 blocks the flow of electrons toward the second electrode 8, thereby suppressing carrier recombination at the interface between the hole transport layer 7 and the light absorbing layer 6.

[0051] After forming the second electrode 8, in order to form a series connection circuit of adjacent solar cell units 20 (20a~20c) on the substrate 2, an incision (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, second electrode 8) formed on the substrate 2 by cutting (refer to Figures 4C, 7C and 8B described later).

[0052] [Method for manufacturing solar cell] Figure 2 is a process diagram of an example of the manufacturing method of solar cells 25 and 25X.

[0053] As shown in Figure 2, the manufacturing methods of the solar cell 25 in this embodiment and the existing solar cell 25X include a first process S1 to a third process S3.

[0054] (The solar cell of this embodiment and the common manufacturing method of existing solar cells) Figures 3A to 3C are cross-sectional views schematically showing an example of a process for forming a first covering layer (electron transport layer 5), an example of a process for forming a separation groove P1 for cutting a first electrode, and an example of a process for forming a light absorption layer 6 and a second covering layer (hole transport layer 7) in a common manufacturing process (first process S1) of the solar cell 25 involved in this embodiment and the existing solar cell 25X.

[0055] <First Step> As shown in FIG. 3A to FIG. 3C , in the first step S1 (see FIG. 2 ), the photoelectric conversion layer 4 is arranged (laminated) on the surface of the first electrode 3 formed on one side of the substrate 2 (on the substrate 2 ) opposite to the substrate 2 (on the first electrode 3 ).

[0056] 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 covering film on the first electrode 3 [transparent conductive film: TCO (Transparent Conductive Oxide)] on the substrate 2 (S1-1: refer to Figure 3A).

[0057] Next, the first electrode-cutting separation groove P1 is formed in the first capping layer (electron transport layer 5) by cutting processes such as machining and laser processing (S1-2: see Figure 3B). Machining and laser processing are conventionally known processing methods, using a cutting blade and a cutting laser, respectively. This cutting process is also used when forming the electrode connection separation groove P2 and the second electrode-cutting separation groove P3, which will be described later.

[0058] Next, a light absorption layer 6 (PVSK: PeroVSKite) containing perovskite is formed in the first electrode cutting separation groove P1 and on the first covering layer (electron transport layer 5), and then a hole transport layer 7 or an electron transport layer 5 (in this example, the hole transport layer 7) is formed on the light absorption layer 6 as a second covering layer (S1-3: refer to Figure 3C).

[0059] (Existing methods for manufacturing solar cells) Figure 4A is a cross-sectional view schematically showing an example of the process of forming the electrode connection separation groove P2 in the manufacturing process (second process S2) of a conventional solar cell 25X. Figure 4B is a cross-sectional view schematically showing an example of the process of forming the second electrode 8 in the manufacturing process (second process S2) of a conventional solar cell 25X. Figure 4C is a cross-sectional view schematically showing an example of the process of forming the second electrode cutting separation groove P3 in the manufacturing process (third process S3) of a conventional solar cell 25X. Figure 5 is a cross-sectional view schematically showing the power generation state of a conventional solar cell 25X with the electrode connection separation groove P2X formed at the desired depth.

[0060] (Second process) In the second process S2 (refer to Figure 2), as shown in Figure 4A, the layers (electron transport layer 5, light absorption layer 6, hole transport layer 7) formed on the substrate 2 are processed by cutting such as machining and laser processing to form a separation groove P2X (S2-1) for electrode connection.

[0061] Furthermore, in the second process S2 (refer to Figure 2), as shown in Figure 4B, a second electrode 8 is formed in the electrode connection separation groove P2X and on the hole transport layer 7 (S2-2).

[0062] <Third Step> In the third process S3 (refer to Figure 2), as shown in Figure 4C, the layers (electron transport layer 5, light absorption layer 6, hole transport layer 7, and second electrode 8) formed on the substrate 2 are processed by cutting such as machining and laser processing to form a separation groove P3 for cutting the second electrode.

[0063] Figure 6A is a schematic cross-sectional view showing a state in which the electrode connection separation groove P2X is deeper than desired in a conventional solar cell 25X configuration example. Furthermore, Figure 6B is a schematic cross-sectional view showing a state in which the electrode connection separation groove P2X is shallower than desired in a conventional solar cell 25X configuration example.

[0064] However, in the existing manufacturing of solar cells, when the photoelectric conversion layer 4 is machined or laser-cut to form the electrode connection separation groove P2X, the properties (film quality, film thickness, hardness, etc.) of each layer formed are greatly varied, making it difficult to stably perform the cutting process. That is, in order for the solar cell to generate electricity efficiently (see Figure 5), the electrode connection separation groove needs to be cut to the desired depth (e.g., the position in contact with the upper surface of the first electrode 3). Even when the same cutting conditions (cutting intensity) are applied to each solar cell between 25X and 25X, the cutting intensity relative to each layer formed on the substrate 2 (electron transport layer 5, light absorption layer 6, hole transport layer 7, second electrode 8) will be too strong or too weak, and the electrode connection separation groove P2X cannot be stably formed to the desired depth, resulting in a deviation in the cutting depth (see Figures 6A and 6B).

[0065] For example, if the cutting strength is too high (see Figure 6A), the first electrode 3 is easily severed by the electrode connection separation groove P2X, and there is easily no electrical connection with the second electrode 8. On the other hand, if the cutting strength is too weak (see Figure 6B), the electrode connection separation groove P2X has difficulty reaching the first electrode 3 (easily resulting in film residue of the so-called photoelectric conversion layer 4), and the resistance value between the first electrode 3 and the second electrode 8 easily becomes high. In any case, the deviation of the characteristics of the solar cell 25X becomes larger.

[0066] Thus, in conventional solar cell 25X manufacturing, it is impossible to reliably electrically connect first electrode 3 and second electrode 8, resulting in a decrease in the power generation efficiency of solar cell 25X. This is particularly true when photoelectric conversion layer 4 includes light-absorbing layer 6 composed of an organic material, and even more so when the organic material comprises perovskite.

[0067] (Method for manufacturing a solar cell according to this embodiment) Regarding this, in the manufacturing method of the solar cell 25 according to this embodiment, the solar cell 25 is manufactured as follows.

[0068] 7A to 9, the manufacturing method of the solar cell 25 according to this embodiment will be described. Note that the first step S1 is the same as the manufacturing step of the conventional solar cell 25X as described above, and its description is omitted here.

[0069] FIG7A is a cross-sectional view schematically illustrating an example of a step of forming an electrode connection separation groove P2 in the manufacturing process (second step S2) of the solar cell 25 according to this embodiment. FIG7B is a cross-sectional view schematically illustrating an example of a step of forming a second electrode 8 in the manufacturing process (second step S2) of the solar cell 25 according to this embodiment. FIG7C is a cross-sectional view schematically illustrating an example of a step of forming a second electrode cutting separation groove P3 in the manufacturing process (third step S3) of the solar cell 25 according to this embodiment.

[0070] FIG8A is an enlarged cross-sectional view showing a portion of the manufacturing process shown in FIG7A . FIG8B is an enlarged cross-sectional view showing a portion of an example of a solar cell 25 manufactured by the manufacturing process shown in FIG7A to FIG7C . Furthermore, FIG9 is a plan view of the solar cell 25 manufactured by the manufacturing process shown in FIG7A to FIG7C as viewed from the side of the second electrode 8 .

[0071] <Second step> In the second step S2 (refer to FIG2 ), as shown in FIG7A and FIG8A , for the layers (electron transport layer 5, light absorption layer 6, hole transport layer 7) formed on one side surface (on substrate 2) of substrate 2, a cutting process such as machining and laser machining is performed to form a separation groove P2 (S2-1) for electrode connection having at least two portions T(1) to T(n) (n is an integer greater than or equal to 2, in this example, n=7) with different depths (refer to FIG8A ).

[0072] Thus, the electrode connection separation groove P2 can be reliably formed with respect to the photoelectric conversion layer 4 .

[0073] Furthermore, in the second step S2 (see FIG. 2 ), as shown in FIG. 7B , the second electrode 8 is formed in the electrode connection separation groove P2 and on the hole transport layer 7 ( S2 - 2 ).

[0074] <Third Step> In the third step S3 (see FIG2 ), as shown in FIG7C , the layers formed on the substrate 2 (electron transport layer 5, light absorption layer 6, hole transport layer 7, second electrode 8) are cut by machining, laser processing, or other cutting processes to form second electrode cutting separation grooves P3. Here, second electrode cutting separation grooves P3 are grooves that cut through the second electrode 8 without cutting through the first electrode 3.

[0075] In the manufacturing method of the solar cell 25 according to the present embodiment, in the second step S2, as shown in FIG7A and FIG8A, the layers (electron transport layer 5, light absorption layer 6, hole transport layer 7) formed on one side of the substrate 2 (on the substrate 2) are subjected to multiple cutting processes (multiple digging with a cutting blade E or multiple irradiation with laser F), and a plurality of grooves Q(1) to Q(n) (n=7) are arranged and formed in sequence in the surface direction W of the substrate 2, thereby forming the electrode connection separation groove P2. The plurality of grooves Q(1) to Q(n) are deep in the direction V perpendicular or substantially perpendicular to the surface of the substrate 2.

[0076] Thus, the electrode connection separation groove P2 can be reliably formed in the solar cell 25 .

[0077] Alternatively, the plurality of grooves Q(1) to Q(n) may be formed so that at least one pair of adjacent grooves [Q(i), Q(i+1)] (i is an integer from 1 to n-1) among the plurality of grooves Q(1) to Q(n) is separated from each other. However, in this case, the light-receiving area of ​​the photoelectric conversion layer 4 is reduced by an amount corresponding to the total width of the grooves Q(1) to Q(n). This reduces the power generation efficiency of the solar cell 25.

[0078] In this regard, in the manufacturing method of the solar cell 25 involved in this embodiment, in the second step S2, as shown in Figures 7A and 8A, a plurality of grooves Q(1)~Q(n) (n=7) are connected without gaps in the surface direction W and [the boundaries between adjacent grooves [Q(i), Q(i+1)] are reduced or eliminated] and formed in sequence.

[0079] As a result, the width of the plurality of grooves Q(1) to Q(n) in the surface direction W can be reduced as a whole, thereby ensuring the light receiving area of ​​the photoelectric conversion layer 4 and correspondingly improving the power generation efficiency of the solar cell 25.

[0080] In the manufacturing method of the solar cell 25 involved in this embodiment, in the second step S2, the cutting conditions (cutting intensity) of the cutting process are changed each time the cutting process is performed so that the depths of at least two grooves among the multiple grooves Q(1)~Q(n) (n=7 in this example) are different (the depths of all the grooves are different in this example).

[0081] For example, in machining or laser machining, when the cutting strength is greater than the reference strength, the relative position of the cutting tool E relative to the workpiece is set (a position where the relative distance is smaller than the reference distance), and the laser output is set (an output larger than the reference output), so that the cutting dimension (depth of cut) of the cutting tool E relative to the workpiece is increased. Conversely, when the cutting strength is weaker than the reference strength, the relative position of the cutting tool relative to the workpiece is set (a position where the relative distance is larger than the reference distance), and the laser output is set (an output smaller than the reference output), so that the cutting dimension (depth of cut) of the cutting edge relative to the workpiece is decreased.

[0082] Therefore, at least two portions T(1) to T(n) of different depths can be easily formed in the electrode connection separation groove P2.

[0083] The manufacturing method of the solar cell 25 involved in this embodiment, as shown in Figure 7C, also includes a third step S3 of cutting the layers (electron transport layer 5, light absorption layer 6, hole transport layer 7, second electrode 8) formed on the surface of one side of the substrate 2 (on the substrate 2) to form a second electrode cutting separation groove P3 for cutting the second electrode 8.

[0084] However, as described above, since the first electrode 3 is cut off by the first electrode cutting separation groove P1, even if the first electrode 3 is cut off in one or more parts of the first electrode cutting separation groove P1 side of the electrode connection separation groove P2 (e.g., T(n) (n=7 in this example) (refer to the α side of Figures 8A, 8B, and 9)), the first electrode 3 can be reached in at least one of the other parts (e.g., T(1) to T(n-1) (refer to the β side of Figures 8A, 8B, and 9) (T(4) to T(6) in this example) as long as the first electrode 3 is not cut off, and no obstacle will be caused.

[0085] In this regard, in the second step S2, the cutting conditions (cutting intensity) of the cutting process are changed in stages in such a manner that at least two (all in this example) groove portions Q(1) to Q(n) gradually become deeper as they move from the side of the second electrode cutting separation groove P3 to the side of the first electrode cutting separation groove P1.

[0086] For example, in the case of cutting processing by mechanical processing or laser processing, when the cutting strength is gradually increased, the relative position of the cutting knife E with respect to the cutting object and the output of the laser F are set in such a way that the cutting size (deep cut) of the cutting knife E on the cutting object is gradually increased each time the cutting processing is performed.

[0087] Furthermore, in the second step S2, the cutting conditions (cutting intensity) of the cutting process are changed in stages in such a manner that at least two (all in this example) groove portions Q(1) to Q(n) gradually become shallower as they move from the first electrode cutting separation groove P1 side toward the second electrode cutting separation groove P3 side.

[0088] For example, when cutting is performed by machining or laser processing, in order to gradually reduce the cutting intensity, each time the cutting process is performed, the relative position of the cutting blade E with respect to the object to be cut and the output of the laser F are set so that the cutting size (deep cut) of the object to be cut by the cutting blade E gradually decreases.

[0089] Thus, it is easy to 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.

[0090] In addition, in the electrode connection separation groove P2, each of at least two portions T(1) to T(n) of different depths does not necessarily have a flat bottom surface. The shape of the bottom surface is deformed according to the cutting conditions of the cutting process such as mechanical processing or laser processing, so it is of course not necessary to have a flat bottom surface. FIG7A conceptually shows that the bottom surface of the electrode connection separation groove P2 has a series of inclined surfaces, but in reality, the bottom surface of the electrode connection separation groove P2 can also have a series of inclined surfaces. In addition, the shape of the inclined surface can be different in each cutting groove portion, so that the electrode connection separation groove P2 can have a concave-convex bottom surface as a whole. It is preferable that the electrode connection separation groove P2 as a whole or a part thereof has a portion that gradually deepens as it moves toward the first electrode cutting separation groove P1 side, or has a portion that gradually shallows as it moves from the first electrode cutting separation groove P1 side to the second electrode cutting separation groove P3 side.

[0091] In the examples shown in Figures 7A and 8A, n (n=7) cutting operations are performed in a continuous (or adjacent) manner on a plurality of grooves Q(1) to Q(n). Furthermore, the plurality of grooves Q(1) to Q(n) are connected or adjacent to adjacent grooves, thereby forming a series of large grooves on the upper side of the grooves. However, the plurality of grooves Q(1) to Q(n) do not necessarily have to be connected or adjacent; they can also be spaced apart from each adjacent groove. That is, adjacent grooves do not need to be connected to the upper side of the groove; they can be separated. Regarding the cutting operation, as shown in Figure 8A, the cutting intensity is increased sequentially from groove Q(1) toward groove Q(n). In the solar cell 25 shown in Figures 7C and 8B, which is completed through the manufacturing process shown in Figures 7A and 8B, the first electrode 3 and the second electrode 8 can reliably contact each other through the oblique portions γ~γ (refer to Figure 8B) of the grooves Q(4), Q(5), and Q(6). This reduces the contact resistance between the first electrode 3 and the second electrode 8.

[0092] Here, since the grooves Q(1) to Q(n) become deeper in sequence, assuming that the photoelectric conversion layer 4 becomes softer than the reference hardness due to the finished product of the photoelectric conversion layer 4, and the electrode connection separation groove P2 is easy to deepen, when the plurality of grooves Q(1) to Q(n) become deeper in stages in the same cutting conditions (cutting intensity), they become deeper in stages in a uniform manner compared to the case of reference hardness. Even if the oblique part γ to γ ​​that contacts the first electrode 3 and the second electrode 8 is offset towards the second electrode cutting separation groove P3 side (right side in FIG8B), the conduction between the first electrode 3 and the second electrode 8 can be ensured by any one of the plurality of grooves Q(1) to Q(n). On the other hand, when the photoelectric conversion layer 4 is harder than the reference hardness due to the finished product of the photoelectric conversion layer 4 and the electrode connection separation groove P2 is easy to become shallow, when the plurality of grooves Q(1) to Q(n) gradually become deeper in stages under the same cutting conditions (cutting intensity), they become shallower in stages compared to the case of reference hardness. Even if the oblique part γ to γ ​​that contacts the first electrode 3 and the second electrode 8 is offset towards the first electrode cutting separation groove P1 side (left side in FIG8B), the conduction between the first electrode 3 and the second electrode 8 can be ensured by any of the plurality of grooves Q(1) to Q(n).

[0093] Therefore, regardless of the final product of the photoelectric conversion layer 4, stable conduction between the first electrode 3 and the second electrode 8 can be ensured, enabling the fabrication of solar cells 25 with minimal characteristic deviations.

[0094] (Regarding the solar cells involved in this embodiment) In the solar cell 25 according to this embodiment, as shown in FIG1 , FIG7C , and FIG8B , the plurality of separation grooves P to P include an electrode-connecting separation groove P2 for electrically connecting the first electrode 3 and the second electrode 8. As shown in FIG8B , the electrode-connecting separation groove P2 has at least two portions T(1) to T(n) (n=7 in this example) having different depths (scribed structure).

[0095] According to this 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 or film thickness, such as hardness) of each layer (such as the photoelectric conversion layer 4) formed between the individual solar cells 25 to 25, the first electrode 3 can be reached without being cut off in any of the at least two portions T(1) to T(n) of the electrode connection separation groove P2 of different depths. For example, even if the first portion T(1) of the electrode connection separation groove P2 does not reach the first electrode 3, even if the other portion T(7) of the electrode connection separation groove P2 cuts off the first electrode 3, the first electrode 3 can be reached through another portion T(4) to T(6) of the electrode connection separation groove P2. Thus, the first electrode 3 and the second electrode 8 can be reliably electrically connected, and the power generation efficiency of the solar cell 25 can be improved accordingly. This is particularly effective when the photoelectric conversion layer 4 has a light absorption layer 6 containing an organic material, and even more effective when the organic material contains perovskite.

[0096] [First embodiment] In the present embodiment, the plurality of separation grooves P to P include a first electrode cutting separation groove P1 for cutting the first electrode 3 .

[0097] However, since the first electrode 3 is cut off by the first electrode cutting separation groove P1, even if the first electrode 3 is cut off 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, there is no obstacle in reaching the first electrode 3 without cutting the first electrode 3 at the other one or more portions [for example, T(1) to T(n-1)].

[0098] In this regard, in the present embodiment, the electrode connection separation groove P2 is deepest on the first electrode cutting separation groove P1 side.

[0099] Thus, since the electrode connection separation groove P2 is deepest on the side of the first electrode cutting separation groove P1, even if the first electrode 3 is cut at one or more portions (e.g., T(n) (n=7)) on the side of the first electrode cutting separation groove P1 in the electrode connection separation groove P2, the first electrode 3 can be reliably reached without being cut at another or more portions (e.g., T(1) to T(n-1)) on the side of the second electrode cutting separation groove P3. Thus, the first electrode 3 and the second electrode 8 can be more reliably electrically connected, and the power generation efficiency of the solar cell 25 can be improved accordingly.

[0100] [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 gradually or stepwise (in this example, stepwise) deepens from the second electrode cutting separation groove P3 side toward the first electrode cutting separation groove P1 side.

[0101] Thus, even if the first electrode 3 is cut at one or more portions (e.g., T(n) (n=7)) on the first electrode cutting separation groove P1 side in the electrode connection separation groove P2, the first electrode 3 can be more reliably reached without being cut at another or more portions (e.g., T(1) to T(n-1)) on the second electrode cutting separation groove P3 side. This allows for more reliable electrical connection between the first electrode 3 and the second electrode 8, and accordingly improves the power generation efficiency of the solar cell 25.

[0102] [Third embodiment] In this embodiment, at least two portions T(1) to T(n) (n=7) of different depths include one or more portions reaching the interior of the substrate 2 [T(n) in this example] and / or one or more portions located within the first electrode 3 [T(5) to T(6) in this example].

[0103] Therefore, the more parts that reach the inside of the substrate 2 and / or are located inside the first electrode 3, the lower the resistance value between the first electrode 3 and the second electrode 8 can be, and the power generation efficiency of the solar cell 25 can be improved accordingly.

[0104] In this embodiment, the depths of one or more portions [T(n)] within the substrate 2 and / or one or more portions [T(5) to T(6)] within the first electrode 3 are different.

[0105] This can further reduce the resistance between the first electrode 3 and the second electrode 8 , thereby further improving the power generation efficiency of the solar cell 25 .

[0106] [Fourth embodiment] In this embodiment, at least two portions T(1) to T(n) of different depths include one or more portions located within the photoelectric conversion layer 4 [in this example, T(1) to T(4)].

[0107] Thus, between each solar cell 25 to 25, when there is a deviation in the properties of each layer (photoelectric conversion layer 4) on the side where it is difficult to reach the first electrode 3 (the side where the light absorption layer 6 is harder than the reference hardness), the first electrode 3 and the second electrode 8 are reliably electrically connected in the other deep side portion [in this example, T(4) to T(6)], and the power generation efficiency of the solar cell 25 can be improved accordingly.

[0108] In this embodiment, one or more portions [T(1)~T(4)] located within the photoelectric conversion layer 4 have different depths.

[0109] Therefore, there is sufficient margin for electrically connecting the first electrode 3 and the second electrode 8. This makes it easy to electrically connect the first electrode 3 and the second electrode 8, thereby improving the power generation efficiency of the solar cell 25.

[0110] [Fifth embodiment] In this embodiment, the electrode connection separation groove P2 is composed of a plurality of groove portions Q( 1 ) to Q(n) arranged in parallel in the surface direction W of the substrate 2 .

[0111] In this way, the depth of each groove portion Q(1) to Q(n) can be changed, thereby reliably forming at least two portions T(1) to T(n) having different depths.

[0112] At least one set of adjacent groove portions [Q(i), Q(i+1)] among the adjacent groove portions [Q(1), Q(2)] to [Q(n-1), Q(n)] of the plurality of groove portions Q(1) to Q(n) may be separated, but in this embodiment, the plurality of groove portions Q(1) to Q(n) are connected to the surface direction W of the base 2. Specifically, the plurality of groove portions Q(1) to Q(n) are configured so that there are few or no boundaries between the adjacent groove portions [Q(1), Q(2)] to [Q(n-1), Q(n)].

[0113] 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 improving the power generation efficiency of the solar cell 25 .

[0114] However, in order to improve the power generation efficiency of the solar cell 25, it is preferred that the light receiving area of ​​the photoelectric conversion layer 4 in the surface direction W of the substrate 2 is large. In other words, the width of the separation groove P2 for electrode connection, that is, the number of multiple groove portions Q(1) to Q(n), is small.

[0115] In this regard, in this embodiment, the number of the plurality of grooves Q(1) to Q(n) is 10 or less (7 in this example). This ensures that the light-receiving area of ​​the photoelectric conversion layer 4 is sufficient in the plane direction W of the substrate 2, thereby improving the power generation efficiency of the solar cell 25.

[0116] In addition, the number of the plurality of grooves Q(1) to Q(n) is preferably 5 or less. This can further ensure the light receiving area of ​​the photoelectric conversion layer 4 in the surface direction W of the substrate 2, thereby further improving the power generation efficiency of the solar cell 25.

[0117] On the other hand, the larger the number of the plurality of grooves Q( 1 ) to Q(n), the easier it is to electrically connect the first electrode 3 and the second electrode 8 .

[0118] In this regard, in the present embodiment, the number of the plurality of grooves Q(1) to Q(n) is four or more.

[0119] This ensures that the light receiving area of ​​the photoelectric conversion layer 4 is sufficient and that the first electrode 3 and the second electrode 8 are reliably electrically connected.

[0120] Furthermore, the possibility of having portions of different depths in each of the plurality of grooves Q(1) to Q(n) is not excluded. That is, by having portions of different depths in each of the plurality of grooves Q(1) to Q(n), a large number of variations in the depth direction can be obtained. Even when the depth deviation of the grooves is shifted in different directions due to manufacturing deviations of each layer, the effect of the grooves can still be utilized, thereby further improving the power generation efficiency of the solar cell 25.

[0121] The present disclosure is not limited to the embodiments described above and can be implemented in various other forms. Therefore, the embodiments described are in all respects merely illustrative and should not be construed as limiting. The scope of the present disclosure is defined by the patent claims and is not limited in any way by the text of the specification. Furthermore, variations and modifications falling within the scope of the patent claims are also within the scope of the present disclosure.

[0122] This application claims priority based on Japanese Patent Application No. 2023-138095 filed in Japan on August 28, 2018. All the above descriptions are incorporated herein by reference. [Industrial Applicability]

[0123] The present disclosure is applicable to the purpose of improving power generation efficiency.

[0124] 2: Matrix 20: Solar cell 25: Solar Cells 3: First electrode 4: Photoelectric conversion layer 5: Electron transport layer 6: Light Absorption Layer 7: Hole transport layer 8: Second electrode P~P: Multiple separation tanks P1: Separation groove for cutting the first electrode P2: Separation groove for electrode connection P3: Separation groove for cutting the second electrode Q(1)~Q(n): a complex number of slots S1: First process S2: Second process S3: The third process T(1)~T(n): at least two parts with different depths V: vertical or approximately vertical direction W: face direction γ: oblique part

Claims

1. A solar cell, wherein, The device has a plurality of solar cell units, on which a first electrode, a photoelectric conversion layer and a second electrode are sequentially disposed on one side of a substrate. The layer formed on the side of the substrate by the plurality of solar cell units is divided by a plurality of separation grooves. The plurality of separation grooves includes electrode connection separation grooves for electrically connecting the first electrode and the second electrode. The electrode connection separation grooves have more than two portions of different depths.

2. The solar cell as claimed in claim 1, wherein, The plurality of separation grooves includes a first electrode cutting separation groove for cutting off the first electrode, and the plurality of separation grooves includes a second electrode cutting separation groove for cutting off the second electrode. The electrode connection separation groove gradually or in stages deepens from the second electrode cutting separation groove side to the first electrode cutting separation groove side.

3. A solar cell, wherein, The device has a plurality of solar cell units, on which a first electrode, a photoelectric conversion layer and a second electrode are sequentially disposed on one side of a substrate. The layer formed on the side of the substrate by the plurality of solar cell units is divided by a plurality of separation grooves. The plurality of separation grooves include an electrode connection separation groove for electrically connecting the first electrode and the second electrode, a first electrode cutting separation groove for cutting the first electrode, and a second electrode cutting separation groove for cutting the second electrode. The electrode connection separation groove has portions of different depths. If each portion of different depths is sequentially designated as T(1) to T(n) from the side of the second electrode cutting separation groove to the side of the first electrode cutting separation groove, where n is an integer greater than or equal to 2, then the separation groove has T(1), T(2), and T(3).

4. The solar cell as claimed in claim 3, wherein, The depth of T(1) < the depth of T(2) < the depth of T(3).

5. A solar cell, wherein, The device comprises a plurality of solar cell units, wherein a first electrode, a photoelectric conversion layer, and a second electrode are sequentially disposed on one side of a substrate. The layer formed by the plurality of solar cell units on the side of the substrate is divided by a plurality of separation grooves. The plurality of separation grooves includes electrode connection separation grooves for electrically connecting the first electrode and the second electrode. Each electrode connection separation groove has at least two portions of different depths, and at least one set of adjacent portions of different depths is connected. The photoelectric conversion layer is not present between the connected set of portions of different depths.

6. The solar cell as claimed in any one of claims 1 to 5, wherein, The bottom surface of the separation tank used for electrode connection is uneven.

7. The solar cell as claimed in claim 6, wherein, The material of the second electrode is Ni, Pt, or Pd.

8. A solar cell, wherein, The device has a plurality of solar cell units, on which a first electrode, a photoelectric conversion layer and a second electrode are sequentially disposed on one side of a substrate. The layer formed on the side of the substrate by the plurality of solar cell units is divided by a plurality of separation grooves. The plurality of separation grooves includes an electrode connection separation groove for electrically connecting the first electrode and the second electrode. Each electrode connection separation groove has at least two portions of different depths.

9. The solar cell according to claim 8, wherein, The single electrode connection uses a separation groove to cut the photoelectric conversion layer through a shared groove.

10. The solar cell according to claim 8, wherein, A single electrode connection separation groove is formed by connecting multiple groove sections.

11. A solar cell, wherein, The device comprises a plurality of solar cell units, wherein a first electrode, a photoelectric conversion layer, and a second electrode are sequentially disposed on one side of a substrate. The layer formed by the plurality of solar cell units on the side of the substrate is divided by a plurality of separation grooves. The plurality of separation grooves includes electrode connection separation grooves for electrically connecting the first electrode and the second electrode. Each electrode connection separation groove has at least two portions of different depths, including one or more portions extending into the substrate and / or one or more portions located within the first electrode.

12. A solar cell, wherein, The device comprises a plurality of solar cell units, wherein a first electrode, a photoelectric conversion layer, and a second electrode are sequentially disposed on one side of a substrate. The layer formed by the plurality of solar cell units on the same side of the substrate is divided by a plurality of separation grooves. The plurality of separation grooves includes an electrode connection separation groove for electrically connecting the first electrode and the second electrode. The electrode connection separation groove has at least two portions of different depths and is composed of a plurality of groove portions arranged side by side in the surface direction of the substrate, and the plurality of groove portions are connected in the surface direction of the substrate.

13. The solar cell as claimed in any one of claims 1, 3, 5, 8 to 12, wherein, The plurality of separation grooves includes a first electrode cutting separation groove for cutting off the first electrode, and the electrode connection separation groove is the deepest on the side of the first electrode cutting separation groove.

14. The solar cell as claimed in claim 13, wherein, The plurality of separation grooves includes a second electrode cutting separation groove for cutting off the second electrode, and the electrode connection separation groove gradually or in stages deepens from the second electrode cutting separation groove side to the first electrode cutting separation groove side.

15. The solar cell as claimed in any one of claims 1, 2, 5, 8 to 12, wherein, When the electrode connection separation groove has more than two portions of different depths, the bottom of the more than two portions of different depths includes one or more portions that reach into the substrate and / or one or more portions that are located within the first electrode; or when the electrode connection separation groove has at least two portions of different depths, the bottom of the at least two portions of different depths includes one or more portions that reach into the substrate and / or one or more portions that are located within the first electrode.

16. The solar cell as claimed in claim 15, wherein, One or more portions reaching the matrix and / or one or more portions located within the first electrode have different depths.

17. The solar cell as claimed in any one of claims 1, 2, 5, 8 to 12, wherein, When the electrode connection separation groove has more than two portions of different depths, the bottom of the more than two portions of different depths includes one or more portions located within the photoelectric conversion layer; or when the electrode connection separation groove has at least two portions of different depths, the bottom of the at least two portions of different depths includes one or more portions located within the photoelectric conversion layer.

18. The solar cell as claimed in claim 17, wherein, One or more portions located within the photoelectric conversion layer have different depths.

19. The solar cell as claimed in any one of claims 1 to 5, 8 to 11, wherein, The electrode connection separation groove is composed of a plurality of grooves arranged side by side in the surface direction of the substrate.

20. The solar cell as claimed in claim 19, wherein, The plurality of grooves are connected in the surface direction of the substrate.

21. The solar cell as claimed in claim 19, wherein, The number of these multiple slots is less than 10.

22. The solar cell as claimed in any one of claims 1 to 5, 8 to 12, wherein, The photoelectric conversion layer has a light-absorbing layer containing organic materials.

23. The solar cell as claimed in claim 22, wherein, This organic material contains perovskite.

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