Solar cell, solar cell, and solar cell module

Abstract

The solar cell unit of the present invention comprises: a substrate; a first electrode disposed on the substrate; a photoelectric conversion layer disposed on the first electrode; a second electrode disposed on the photoelectric conversion layer; and a blocking layer disposed to cover the side portion of the photoelectric conversion layer. The photoelectric conversion layer has an electron transport layer, a light absorption layer disposed on the electron transport layer, and a hole transport layer disposed on the light absorption layer. The light absorption layer contains a compound having a perovskite crystal structure, and the blocking layer is a dense inorganic material layer.

Description

Technical Field

[0001] This invention relates to solar cell units, solar cells, solar cell modules, and solar cell arrays. Background Technology

[0002] Photoelectric conversion elements are used in various optical sensors, solar cells, etc. Particularly in terms of high photoelectric conversion efficiency and low manufacturing cost, there is a growing trend towards developing photoelectric conversion elements that stack a charge generation layer (light absorption layer) and a charge transfer layer. In recent years, perovskite solar cells using charge generation layers comprising compounds with organic-inorganic perovskite crystal structures have achieved photoelectric conversion efficiencies comparable to those of solar cells using inorganic materials and have attracted attention (see, for example, specification WO2017 / 1047921A1).

[0003] Furthermore, in this perovskite solar cell, a charge generation layer is formed on the surface of mesoporous TiO2, thereby improving the photoelectric conversion efficiency. The mesoporous TiO2 serves as a support for the charge generation layer and also functions as an electron transport layer. These charge generation layers can be manufactured using a coating process without vacuum processing, thus significantly reducing the manufacturing cost of the solar cell. This perovskite solar cell, which shows promise in terms of conversion efficiency and cost, and perovskite solar cell modules integrating multiple perovskite solar cells, are expected to serve as the foundation for independent power supply systems for mobile devices, including IoT and electric vehicles.

[0004] Furthermore, when a portion of a series-connected solar cell unit is shaded, heat generation sometimes occurs, a phenomenon known as a hotspot. To prevent this hotspot phenomenon, solar cell modules with bypass diodes are known (see, for example, Japanese Patent Application Publication No. 2020-048382). Additionally, to protect electronic components such as ICs and LSIs from overvoltages caused by electrostatic discharge, variable resistors are used (see, for example, Japanese Patent Application Publication No. 2011-216877). Summary of the Invention

[0005] In existing perovskite solar cells, moisture can seep into the charge generation layer under high temperature and humidity conditions, causing the perovskite solar cell to degrade. This invention addresses this issue by providing a solar cell unit capable of suppressing moisture-induced degradation.

[0006] The present invention provides a solar cell unit comprising: a substrate; a first electrode disposed on the substrate; a photoelectric conversion layer disposed on the first electrode; a second electrode disposed on the photoelectric conversion layer; and a blocking layer disposed to cover the side portion of the photoelectric conversion layer. The photoelectric conversion layer has an electron transport layer, a light absorption layer disposed on the electron transport layer, and a hole transport layer disposed on the light absorption layer. The light absorption layer contains a compound having a perovskite crystal structure, and the blocking layer is a dense inorganic material layer.

[0007] The solar cell unit of the present invention includes a barrier layer disposed on the side of the photoelectric conversion layer, the barrier layer being a dense inorganic material layer. Therefore, it is possible to prevent moisture from penetrating the light absorption layer from the side of the photoelectric conversion layer, thereby suppressing the degradation of the solar cell unit. Furthermore, since the barrier layer is a dense inorganic material layer, it is possible to prevent the barrier layer's blocking function from decreasing due to ultraviolet radiation, temperature changes, etc. Attached Figure Description

[0008] Figure 1 This is a schematic cross-sectional view of a series-connected solar cell according to one embodiment of the present invention.

[0009] Figure 2 This is a partial cross-sectional view of a series-connected solar cell according to one embodiment of the present invention.

[0010] Figure 3 This is an equivalent circuit of a series-connected solar cell according to one embodiment of the present invention.

[0011] Figure 4 (a) to (c) are illustrations of the manufacturing method of series-connected solar cells.

[0012] Figure 5 This is a schematic top view of a solar cell module according to one embodiment of the present invention.

[0013] Figure 6 This is a schematic top view of a solar cell module according to one embodiment of the present invention.

[0014] Figure 7 (a) is a schematic top view of a solar cell array according to one embodiment of the present invention, and (b) is a schematic cross-sectional view of the solar cell array.

[0015] Figure 8 This is a schematic top view of a solar cell array according to one embodiment of the present invention.

[0016] Figure 9(a) is a schematic top view of the solar cell module, (b) is a schematic cross-sectional view of the solar cells connected in series, and (c) is the equivalent circuit of the solar cells connected in series.

[0017] Figure 10 (a) is a partial top view of the solar cell module, and (b) is a schematic cross-sectional view of the solar cell module in the dashed line BB.

[0018] Figure 11 (a) is a partial top view of the solar cell module, and (b) is a schematic cross-sectional view of the solar cell module in the dashed line CC. Detailed Implementation

[0019] The solar cell unit of the present invention is characterized by comprising: a substrate; a first electrode disposed on the substrate; a photoelectric conversion layer disposed on the first electrode; a second electrode disposed on the photoelectric conversion layer; and a blocking layer disposed to cover the side portion of the photoelectric conversion layer, the photoelectric conversion layer having an electron transport layer, a light absorption layer disposed on the electron transport layer, and a hole transport layer disposed on the light absorption layer, the light absorption layer containing a compound having a perovskite crystal structure, and the blocking layer being a dense inorganic material layer.

[0020] Preferably, the aforementioned barrier layer is made of a material exhibiting the characteristics of a varistor, and is connected to the first and second electrodes in parallel with the photoelectric conversion layer. This allows the barrier layer to function as a bypass, protecting the photoelectric conversion layer from high voltage when the solar cell unit enters shadow. Furthermore, this barrier layer suppresses the reduction in power generation caused by shading. Additionally, the subsequent installation of a bypass diode on the solar cell unit can be omitted, reducing manufacturing costs. Moreover, the reliability of the solar cell unit is improved by reducing the number of junctions. The present invention also provides a series-connected solar cell comprising multiple solar cell units, a first terminal, and a second terminal. Multiple solar cell units are connected in series, with one end of the series-connected solar cell unit connected to the first terminal and the other end connected to the second terminal. The series-connected solar cell of the present invention improves the terminal voltage.

[0021] The present invention also provides a solar cell module comprising multiple series-connected solar cells of the present invention. A first terminal is disposed on the light-receiving surface, and a second terminal is disposed on the back side opposite to the light-receiving surface. This allows for the separation of terminal polarities on the light-receiving surface and the back side. Therefore, by simply overlapping two solar cell modules, series-connected solar cells in one solar cell module and series-connected solar cells in another solar cell module can be connected in series. Preferably, the solar cell module is rectangular, each series-connected solar cell has an elongated shape, a first terminal is disposed at one end of the elongated shape, a second terminal is disposed at the other end of the elongated shape, and multiple series-connected solar cells are arranged in a parallel column inclined relative to one side of the rectangle. This allows the first terminal of one series-connected solar cell and the second terminal of the other series-connected solar cell in two adjacent series-connected solar cells to be connected by a busbar arranged parallel to one side of the rectangular solar cell module. Thus, two adjacent series-connected solar cells can be connected in series.

[0022] The solar cell module of the present invention preferably includes a busbar, which preferably electrically connects two adjacent series-connected solar cells in a plurality of series-connected solar cells. Preferably, the first terminals of the solar cell module are arranged in one row, and the second terminals of the solar cell module are arranged in another row. This facilitates the connection of two solar cell modules, the connection of the first and second terminals, or the connection of the first or second terminal to the busbar. Furthermore, the number of series-connected solar cells connected in parallel can be easily adjusted, and high voltage can be suppressed and the current value increased when connecting the solar cell modules. The present invention also provides a solar cell array comprising a plurality of solar cell modules of the present invention. The plurality of solar cell modules includes a first solar cell module and a second solar cell module, wherein the first and second terminals of the first solar cell module are arranged in positions mirror-symmetrical to the positions of the first and second terminals of the second solar cell module. By overlapping the first and second solar cell modules, the first terminals of the first solar cell module and the second terminals of the second solar cell module can be easily brought into contact, and the series-connected solar cells in the first solar cell module and the series-connected solar cells in the second solar cell module can be easily connected in series.

[0023] The present invention will now be described in more detail with reference to several embodiments. The configurations shown in the accompanying drawings and the following description are illustrative, and the scope of the present invention is not limited to the contents shown in the drawings and the following description.

[0024] First Implementation Method

[0025] The first embodiment relates to a solar cell unit and solar cells connected in series. Figures 1-4 This diagram relates to the solar cell unit and the series-connected solar cells of this embodiment. The solar cell unit 20 (20a-20e) of this embodiment includes: a first substrate 2, a first electrode 3 (3a-3e) disposed on the first substrate 2, a photoelectric conversion layer 4 (4a-4e) disposed on the first electrode 3, a second electrode 8 (8a-8e) disposed on the photoelectric conversion layer 4, and a first barrier layer 9 disposed to cover the side portion of the photoelectric conversion layer 4. The photoelectric conversion layer 4 has an electron transport layer 5 (5a-5e), a light absorption layer 6 (6a-6e) disposed on the electron transport layer 5, and a hole transport layer 7 (7a-7e) disposed on the light absorption layer 6. The light absorption layer 6 contains a compound having a perovskite crystal structure. The first barrier layer 9 is characterized in that it is a dense inorganic material layer.

[0026] The series-connected solar cell 25 of this embodiment includes multiple solar cell units 20 (20a~20e), a first terminal 15, and a second terminal 16. The multiple solar cell units 20 are connected in series. One end of the series-connected solar cell units 20a is connected to the first terminal 15, and the other end of the series-connected solar cell units 20e is connected to the second terminal 16. The series-connected solar cell 25 can also be a solar cell module 30. The number of series-connected solar cell units 20 is not particularly limited as long as there are multiple units.

[0027] The first substrate 2 is used to form the photoelectric conversion layer 4. The first substrate 2 can be a substrate for connecting the solar cells 25 in series, or it can be a substrate for the solar cell module 30. When the solar cell module 30 has multiple solar cells 25 connected in series, the multiple solar cells 25 can also be disposed on one first substrate 2. When the first substrate 2 is the light incident side, it is made of a light-transmitting material. The first substrate 2 can be a glass substrate or a transparent organic film. Thus, light can enter the interior of the solar cell unit 20. When the first substrate 2 is a flexible organic thin film, the solar cell module 30 is a flexible solar cell module.

[0028] Specifically, materials used for the organic film serving as the first substrate 2 include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyetherimide (PEI), polytetrafluoroethylene (PTFE), polyamide-imide (PAI), and polyethylene naphthalate (PEN). Other resins may also be used, provided the requirements are met. The thickness of the organic film serving as the first substrate 2 is preferably 50 to 100 μm.

[0029] When the first substrate 2 is a transparent organic film, a second barrier layer 10 can be formed on one main surface of the first substrate 2. The second barrier layer 10 is a layer of material with high gas barrier properties. This prevents internal degradation of the solar cell unit 20 (20a-20e) caused by moisture, oxygen, etc., in the air. Furthermore, the second barrier layer 10 is a layer of insulating material. This suppresses leakage current flow. The film thickness of the second barrier layer 10 can be set to several tens to 100 nm. This allows the second barrier layer 10 to be transparent. Furthermore, it provides the flexibility of the solar cell unit 20. Specific examples of materials for the second barrier layer 10 include silicon oxide and aluminum oxide. If the second barrier layer 10 possesses gas barrier, insulation, and light transmittance, other oxides and insulators can also be used as materials for the second barrier layer 10. Examples of main film-forming methods for the second barrier layer 10 include sputtering and vacuum evaporation.

[0030] The first electrode 3 (3a-3e) is disposed on the first substrate 2 (or the second barrier layer 10) and is used to extract the current generated by the photoelectric conversion layer 4 of the solar cell unit 20 (20a-20e). When the first substrate 2 is the light incident side, the first electrode 3 can be a transparent conductive film. The transparent conductive film is, for example, made of 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). In addition, the first electrode 3 can also be formed by patterning fine lines of conductive metals such as silver on the oxide of the above-mentioned conductive transparent materials. Preferably, the thin film resistance of the first electrode 3 is 10Ω / sq or less, and preferably, the light transmittance of the first electrode 3 is 80% or more. Examples of methods for forming the first electrode 3 include sputtering film deposition, vacuum evaporation, coating / printing of conductive paste, and low-temperature sintering.

[0031] When multiple solar cell units 20 are disposed on the first substrate 2, the transparent conductive film formed on the first substrate 2 is divided according to each solar cell unit 20. For example, Figure 1 The series-connected solar cell 25 shown comprises five solar cell units 20a-20e, thus the transparent conductive film is divided to form five first electrodes 3a-3e. The grooves dividing two adjacent first electrodes 3 can also be filled with a light-absorbing layer 6 or the like.

[0032] A first terminal 15, connecting the series-connected solar cells 25, is formed on an organic film serving as the first substrate 2. A portion of the first terminal 15 penetrates the organic film (first substrate 2) and the second barrier layer 10, and is in contact or electrically connected to the first electrode 3a of the solar cell 20a at the end of the series-connected solar cell cells 20a-20e. Using the first terminal 15, the current generated by the photoelectromotive force of the series-connected solar cells 25 can be extracted. SnZn-based solder paste can be used as a material for the first terminal 15. Other conductive pastes and electrode materials can also be used, provided the requirements are met.

[0033] The photoelectric conversion layer 4 (4a-4e) is a layer in which light energy is converted into electrical energy. Specifically, the photoelectric conversion layer 4 receives light to generate a photoelectromotive force. The photoelectric conversion layer 4 is disposed on the first electrode 3 (3a-3e). In addition, the photoelectric conversion layer 4 has an electron transport layer 5 (5a-5e), a light absorption layer 6 (6a-6e) disposed on the electron transport layer 5, and a hole transport layer 7 (7a-7e) disposed on the light absorption layer 6.

[0034] The electron transport layer 5 is a layer that transports electrons generated by photoexcitation in the light absorption layer 6 to the first electrode 3. Therefore, the electron transport layer 5 is constructed of a material from which electrons generated in the light absorption layer 6 can easily move to the electron transport layer 5, and electrons in the electron transport layer 5 can easily move to the first electrode 3. Furthermore, the electron transport layer 5 can be a seed layer for oriented growth of the light absorption layer 6. This improves the crystal quality of the compound having the perovskite crystal structure constituting the light absorption layer 6. The electron transport layer 5 is, for example, a titanium oxide (TiO2) layer. Furthermore, a TiN layer or TiO2 layer can also be formed on the surface of the titanium oxide contained in this titanium oxide layer. 2-x N x The electron transport layer 5 has a film thickness of, for example, 100 nm or more and 250 nm or less.

[0035] For example, a titanium oxide (TiO2) layer with a thickness of 100-250 nm can be formed on the transparent conductive film serving as the first electrode 3, acting as the electron transport layer 5, i.e., the seed layer. Examples of methods for forming this seed layer include sputtering, vacuum evaporation, coating / printing of conductive pastes, and low-temperature sintering. For instance, a titanium oxide (TiO2) paste for low-temperature sintering can be coated onto the transparent conductive film, and the seed layer can be formed by sintering at 150°C or below. The crystal structure of the TiO2 contained in the TiO2 layer is preferably a rutile structure. Furthermore, by subjecting the surface of the TiO2 to nitrogen plasma surface modification treatment, a TiN (NaCl structure) layer with a thickness of 5-30 nm can be formed on the surface of the TiO2.

[0036] The lattice constants of TiO2 (rutile structure) and TiN (NaCl structure) are well matched, resulting in a well-formed interface with few defects between the TiO2 layer (composed of TiO2) and the TiN layer (composed of TiN). This is achieved by forming a mixed-crystal material, TiO2, near the interface. 2-x N x The lattice constant changes continuously, which can suppress the generation of interface defects. When the TiN layer is exposed to the atmosphere after surface modification treatment with nitrogen plasma, an oxide layer with a thickness of several nm is formed on the surface. However, the TiO2 layer formed is thin, so it does not cause structural lattice constant mitigation and maintains the lattice constant of the TiN layer on the substrate.

[0037] After forming a transparent conductive film (first electrode 3) and a seed layer (electron transport layer 5) on the organic film (first substrate 2) covered by the second barrier layer 10, in order to separate and form solar cell units 20a-20e on the organic film (first substrate 2), cuts (L1) are made in the transparent conductive film and seed layer by laser cutting. The wavelength of the laser used is preferably a wavelength in the infrared region. For example, such as... Figure 4 As shown in (a), cuts (L1) are added to the transparent conductive film to form the first electrodes 3a~3e. No cuts are formed on the second barrier layer 10.

[0038] The light absorption layer 6 (6a-6e) is a layer that absorbs light incident on the photoelectric conversion layer 4 (4a-4e) to generate electrons and holes. That is, in the light absorption layer 6, lower-energy electrons of the material constituting the light absorption layer 6 are excited by the incident light, generating higher-energy electrons and holes. The electrons move to the electron transport layer 5, and the holes move to the hole transport layer 7, thereby achieving charge separation.

[0039] The light-absorbing layer 6 contains a compound (an organic-inorganic mixed compound) with a perovskite crystal structure. When this compound is photoexcited, electrons and holes can be generated in the light-absorbing layer 6. The film thickness of the light-absorbing layer 6 is preferably in the range of 500~1000 nm.

[0040] For example, a compound with an organic-inorganic mixed perovskite crystal structure (hereinafter also referred to as "perovskite structure compound") can be formed on a seed layer (electron transport layer 5) with notches (L1) formed by laser cutting, forming a light-absorbing layer 6. The perovskite structure compound has a basic unit lattice of a tetragonal crystal system. This unit lattice has organic groups (organic molecules) A ​​arranged at each vertex, metal atoms B arranged at the body center, and halogen atoms X arranged at each face center, represented by the general formula AB-X3.

[0041] In the general formula AB-X3, specific examples of organic group A (alkylamine) 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, ethylbutylamine, imidazole, azoles, pyrrole, aziridine, azacyclic propene, acridine, azacyclic butadiene, imidazoline, carbazole and their ions (e.g., methylammonium (CH3NH3)), phenethylammonium, etc. These organic groups can be used alone or in combination of two or more. Wherein, the organic group A is preferably methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine and their ions or phenethylammonium, especially preferably methylamine, ethylamine, propylamine and their ions (e.g. methylammonium (CH3NH3) etc.).

[0042] Furthermore, specific examples of the metal atom B in the general formula AB-X3 include lead, tin, zinc, titanium, antimony, bismuth, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, and europium. These elements can be used individually or in combination of two or more. Among these, using lead as the metal atom B improves the properties of the photoelectric conversion layer 4.

[0043] Furthermore, in the general formula AB-X3, specific examples of halogen atom X include chlorine, bromine, and iodine. These elements can be used alone or in combination of two or more. Among them, since the band gap narrows, it is preferable that at least one of the halogen atom X is iodine.

[0044] The perovskite structure compound contained in the light-absorbing layer 6 is preferably a compound represented by CH3NH3PbX3 (where X is a halogen atom), and more preferably a compound in which X is an iodine atom in the formula CH3NH3PbX3 (i.e., a compound represented by CH3NH3PbI3).

[0045] The perovskite-structured compound used to form the light-absorbing layer 6 can be synthesized using the compound represented by AX and the compound represented by BX2 as raw materials. Specifically, the perovskite-structured compound can be synthesized by mixing an AX solution and a BX2 solution and heating and stirring (a one-stage method). Alternatively, the perovskite-structured compound can be synthesized by, for example, coating a BX2 solution onto a seed layer (electron transport layer 5) to form a coating film, coating an AX solution onto the coating film, and then reacting BX2 and AX (a two-stage method). Either the one-stage method or the two-stage method can be used to form the light-absorbing layer 6 (the layer of the perovskite-structured compound). The coating method is not particularly limited, and examples include screen printing, dip coating, and inkjet printing.

[0046] Organic solvents (included in the coating solution) used in the coating method for forming the light-absorbing layer 6 include, for example, aromatic hydrocarbons such as toluene, xylene, mesitylene, tetrahydronaphthalene, 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; aprotic polar solvents such as N,N-dimethylformamide and N,N-dimethylacetamide; alcohols such as methanol, ethanol, and isopropanol; and glycol diether solvents such as ethylene glycol and diethylene glycol monomethyl ether. These solvents can be used alone or as mixed solvents. Water can also be added to these solvents. Among these solvents, non-halogen organic solvents are preferred from an environmental perspective. In addition, the coating solution may also contain additives such as antioxidants, viscoelastic modifiers, preservatives, and curing catalysts.

[0047] When forming the perovskite-structured compound film as the light-absorbing layer 6, if the temperature of the first substrate 2 during film formation is low, the perovskite-structured compound may crystallize into needle-like forms. The length of the needle-like crystals is preferably 10-20 μm, and the width is preferably 1-5 μm; a bamboo leaf-like shape is particularly preferred. An organic binder resin can also be coated as a filler between the needle-like crystals. The organic binder resin is preferably a material that requires transparency, amorphous properties, and high insulation. Examples of organic adhesive resins include: vinyl resins such as polymethyl methacrylate, polystyrene, and polyvinyl chloride; thermoplastic resins such as polycarbonate, polyester, polyester carbonate, polysulfone, polyarylate, polyamide, methacrylic acid 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 crosslinked products of these resins; and copolymers containing two or more constituent units (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 may also be used as long as the requirements are met.

[0048] In addition, the organic adhesive resin may contain a hole-transporting material. Examples of hole-transporting materials 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 acetylene compounds, polythiophene ethylene compounds, and polythiophene compounds. Butadiene compounds and dibutadiene compounds are particularly preferred. Furthermore, conductive microparticles such as carbon nanofibers and conductive polymers such as PEDOT / PSS can also be used. The hole-transporting material is preferably a compound that is difficult to crystallize, but to reliably prevent crystallization of the hole-transporting material, it may also be configured to contain an organic adhesive resin or plasticizer. Furthermore, the organic solvent used when coating the needle-like crystals is preferably a solvent that does not disturb the needle-like crystals. Specifically, chlorobenzene and toluene are preferred. Furthermore, the coating method is not particularly limited; for example, dip coating, spray coating, and sliding funnel coating are preferred.

[0049] By coating the surface of the needle-like crystals of the perovskite structure compound and the exposed seed 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-like crystals are fixed together by the filler, the rigidity of the perovskite crystals is improved. Moreover, because the needle-like crystals are coated with the filler, the light incident on the photoelectric conversion layer 4 undergoes multiple scattering, thereby increasing the light absorption efficiency. As a result, the carrier extraction rate (short-circuit current) of the solar cell unit 20 increases. Furthermore, by thinning the film thickness of the photoelectric conversion layer 4, a high open-circuit voltage can also be obtained.

[0050] After forming the light-absorbing layer 6, in order to connect the first electrode 3 of one of the two adjacent solar cell units 20 (20a~20e) to the hole transport layer 7 and the second electrode 8 of the other solar cell unit 20, a cut (L2) is formed in a portion of the light-absorbing layer 6 by laser cutting. The wavelength of the laser used is preferably a wavelength in the visible light region. For example, such as... Figure 4 As shown in (b), a cut (L2) is formed in the light-absorbing layer 6 to form light-absorbing layers 6a-6e. In this laser cutting, a portion of the light-absorbing layer 6 and a portion of the electron transport layer 5 are removed, but the first electrode 3 and the second barrier layer 10 are not removed.

[0051] The hole transport layer 7 (7a-7e) is a layer that allows holes generated in the light absorption layer 6 to move towards the second electrode 8. The hole transport layer 7 is formed on the light absorption layers 6a-6e, which are segmented by laser cutting. The hole transport layer 7 is, for example, made of an inorganic material with a band gap of 2 eV or more and an ionization potential greater than (shallower than) -5.3 eV. The thickness of the hole transport layer 7 is, for example, 30 nm or more and 100 nm or less. Specific materials constituting the hole transport layer 7 include oxides and sulfides such as copper oxide (Cu₂O) and zinc sulfide (ZnS).

[0052] The second electrode 8 (8a-8e) is disposed on the hole transport layer 7 and is used to extract the current generated by the photoelectric conversion layer 4 of the solar cell unit 20 (20a-20e). The second electrode 8 is, for example, a metal film with a work function of 5 eV or higher. Because the second electrode 8 is made of a metal with a high work function (5 eV or higher), a band-shaped bend occurs at the interface between the hole transport layer 7 and the second electrode 8, allowing for smoother hole flow. Examples of materials for 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 by methods such as sputtering or vacuum evaporation.

[0053] At the interface between the hole transport layer 7 and the light absorption layer 6, holes generated by the light absorption layer 6 flow to the second electrode 8 via the hole transport layer 7 for hole extraction. Regarding electrons, since the hole transport layer 7 blocks the flow of electrons to the second electrode 8, it has the effect of suppressing carrier recombination at the interface between the hole transport layer 7 and the light absorption layer 6.

[0054] After the hole transport layer 7 and the second electrode 8 are formed, in order to form the hole transport layer 7 and the second electrode 8 in the series connection circuit of the solar cell cells 20a-20e adjacent to each other on the first substrate 2, a cut (L3) is formed in a portion of the hole transport layer 7 and the second electrode 8 by laser cutting. Furthermore, in order to enable the first blocking layer 9 (described later) to function as a variable resistor 17, a cut (L4) is formed in the electron transport layer 5, the light absorption layer 6, the hole transport layer 7, and the second electrode 8. The wavelength of the laser used is preferably in the ultraviolet region. For example, such as... Figure 4 As shown in (c), a cut (L3) is formed in the hole transport layer 7 and the second electrode 8 to form hole transport layers 7a-7e and second electrodes 8a-8e. Furthermore, as... Figure 4 As shown in (c), a cutout (L4) for forming the rheostat 17 can be formed. Alternatively, if the portion with the cutout (L3) functions as the rheostat 17, the cutout (L4) can be omitted.

[0055] The first barrier layer 9 is a dense inorganic material layer (inorganic materials have high density) and is provided to cover the sides of the photoelectric conversion layer 4 (4a~4e). Alternatively, the first barrier layer 9 can be provided to cover the entire periphery of the photoelectric conversion layer 4. Furthermore, the first barrier layer 9 can be provided to cover the upper surface of the second electrode 8. This first barrier layer 9 can suppress the intrusion of moisture (water vapor, etc.) into the light absorption layer 6, thus suppressing the degradation of the solar cell unit 20. Furthermore, since the first barrier layer 9 is a dense inorganic material layer, the barrier function of the first barrier layer 9 can be prevented from decreasing due to ultraviolet radiation, temperature changes, etc. Moreover, by completely coating the photoelectric conversion layer 4 with the first barrier layer 9, the first electrode 3, the first substrate 2, and the second barrier layer 10, the water vapor barrier characteristics can be improved.

[0056] Furthermore, the first barrier layer 9 can also be made of a material exhibiting the characteristics of a variable resistor. Additionally, the first barrier layer 9 can be configured to be connected to the first electrode 3 and the second electrode 8 in parallel with the photoelectric conversion layer 4. The variable resistor characteristics refer to the voltage-current characteristics (current nonlinearity) that cause a rapid current flow at a given voltage. The material exhibiting the variable resistor characteristics is not particularly limited as long as it can be used in a variable resistor element. The thickness of the first barrier layer 9 can, for example, be 30 nm or more and 100 nm or less.

[0057] A first barrier layer 9 is formed on the laser-cut second electrode 8. Furthermore, the first barrier layer 9 can be formed in a manner that satisfies a cut (L3). Thus, the first barrier layer 9 can cover the periphery and upper surface of the photoelectric conversion layer 4. Furthermore, the first barrier layer 9 can be formed in a manner that satisfies a cut (L4). Thus, the first barrier layer 9 can be connected to the first electrode 3 and the second electrode 8 in parallel with the photoelectric conversion layer 4. A portion of the first barrier layer 9 is connected in parallel with the photoelectric conversion layer 4 as a variable resistor element structure, thereby enabling a solar cell unit 20 that integrates a bypass diode (the variable resistor of the first barrier layer 9). This allows for the suppression of power generation efficiency reduction caused by shading on the module at low cost.

[0058] The first barrier layer 9 may, for example, contain zinc oxide (ZnO) as a matrix material (e.g., the zinc oxide content in the first barrier layer 9 is 95 wt% or more), and contain silicon oxide, aluminum oxide, titanium oxide, etc. as additives. Preferably, the rheostat characteristics (I=KVα, K: element intrinsic constant, α: voltage nonlinearity coefficient) of the first barrier layer 9 between the first electrode 3 and the second electrode 8 are α=20~60, and the bending point voltage is 2V or more.

[0059] The second substrate 12 is disposed on the upper part of the first barrier layer 9, and the photoelectric conversion layer 4 is located between the first substrate 2 and the second substrate 12. The second substrate 12 can be a substrate for connecting solar cells 25 in series, or it can be a substrate for solar cell module 30. The second substrate 12 can be a glass substrate, a transparent organic film, or an opaque organic film.

[0060] When the second substrate 12 is an organic film, a third barrier layer 11 can be formed on one main surface of the second substrate 12. The third barrier layer 11 is a layer of material with high gas barrier properties. This prevents degradation of the solar cell units 20 (20a-20e) caused by moisture, oxygen, etc., in the air. Furthermore, the third barrier layer 11 is a layer of insulating material. This suppresses leakage current flow. The thickness of the third barrier layer 11 can be several tens to 100 nm. Specific examples of materials for the third barrier layer 11 include silicon oxide and aluminum oxide.

[0061] A second terminal 16, connecting the series-connected solar cells 25, is formed on the organic film serving as the second substrate 12. A portion of the second terminal 16 penetrates the organic film (second substrate 12) and the third barrier layer 11, and is in contact with or connected via the first barrier layer 9 to the second electrode 8e of the solar cell 20e at the end of the series-connected solar cell cells 20a-20e. Using the first terminal 15 and the second terminal 16, the current generated by the photoelectromotive force of the series-connected solar cells 25 can be extracted. SnZn-based solder paste can be used as a material for the second terminal 16. Other conductive pastes and electrode materials can also be used, provided the requirements are met.

[0062] After the first barrier layer 9 is formed on the second electrode 8, an organic film (second substrate 12) with a second terminal 16 is bonded to the first barrier layer 9 with a laminate 13 in between, and then heated and laminated to complete the series connection of multiple solar cell units 20a-20e into a solar cell 25 or solar cell module 30. Furthermore, an opening is made at the location of the second terminal 16 of the laminate 13 sandwiched between the first barrier layer 9 and the second substrate 12. Therefore, the second terminal 16 is well connected to the first barrier layer 9 during lamination. Thus, a variable resistor is formed between the second electrode 8e and the second terminal 16. During power generation, a high voltage is applied between the second electrode 8e and the second terminal 16, so it does not become an obstacle to extracting current from its variable resistor characteristics. Furthermore, the second electrode 8e and the second terminal 16 can also be in contact. The laminate 13 can be a general lamination material, preferably a resin film with a lamination temperature of 180°C or lower and high water resistance.

[0063] Figure 2 The diagram is obtained by overlaying a schematic cross-sectional view of a solar cell unit 20 included in the series-connected solar cells 25 with the equivalent circuit of the solar cell unit 20. Figure 3 yes Figure 1 The equivalent circuit of the series-connected solar cells 25 is shown. (For example...) Figure 2 As shown, the photoelectric conversion layer 4 can be represented by a current source 18 and a diode 19. Furthermore, the first blocking layer 9 in the L4 cutout is represented by a variable resistor 17, which is connected to the first electrode 3 and the second electrode 8, thus being connected in parallel with the photoelectric conversion layer 4.

[0064] In addition, such as Figure 3As shown, in the series-connected solar cell 25, multiple solar cell units 20 are connected in series. Furthermore, of the multiple series-connected solar cell units 20a-20e, one end of solar cell unit 20a is connected to the first terminal 15, and the other end of solar cell unit 20e is connected to the second terminal 16. When all solar cell units 20a-20e receive light and perform photoelectric conversion, a current flowing in the direction of the arrow in the current source 18 is generated in all photoelectric conversion layers 4a-4e. Furthermore, the combined voltage of solar cell units 20a-20e can be output from the first terminal 15 and the second terminal 16.

[0065] For example, when solar cell 20c is in shadow and only solar cell 20c is not performing photoelectric conversion, no current is generated in solar cell 20c. Furthermore, it is difficult for current to flow in the reverse direction of diode 19 in solar cell 20c (the resistance becomes very high). Moreover, since solar cell cells 20a, 20b, 20d, and 20e perform photoelectric conversion, a large voltage is applied to solar cell 20c. If this voltage exceeds a predetermined voltage, it is possible to suppress the current flowing through the first electrode 3c → rheostat 17 → second electrode 8c → first electrode 3d, thus preventing excessive voltage from being applied to solar cell 20c. In other words, rheostat 17 functions as a bypass to protect photoelectric conversion layer 4c from high voltage. Furthermore, the rheostat 17 can suppress the reduction in power generation caused by shading.

[0066] Second Implementation Method

[0067] The second embodiment involves a solar cell module 30 and a solar cell array 40. Figure 5 This is a schematic top view of the α-type solar cell module 30a according to this embodiment. Figure 6 This is a schematic top view of the ω-type solar cell module 30b according to this embodiment. The solar cell module 30 (30a, 30b) has a plurality of solar cells 25 (25a~25t) connected in series. For example, Figure 5 The α-type solar cell module 30a shown is Figure 6 The ω-type solar cell module 30b shown has 20 solar cells 25a~25t connected in series. Each series-connected solar cell 25a~25t has... Figure 1 The cross-section shown. For example, Figure 5 The cross-section of the series-connected solar cell 25 in dashed line A, excluding the second terminal 16 (16a), becomes Figure 1The cross-section shown is illustrated. Furthermore, multiple solar cells 25 connected in series can be disposed between a first substrate 2 and a second substrate 12. The solar cell module 30 can be a thin-film perovskite solar cell module.

[0068] The major axis of the solar cell unit 20 can be 300 mm, and the minor axis can be 10 mm. Five series-connected solar cells 25 integrated in series within the solar cell unit 20 can also have a major axis of 300 mm and a minor axis of 50 mm. Furthermore, 20 series-connected solar cells 25 are arranged to form a solar cell module 30 (30a, 30b). Here, a minor axis of 10 mm is given as an example, but the minor axis can also range from 5 mm to 15 mm. Regarding the size of the solar cell module 30, this is just one example. In the case of smaller perovskite solar cell modules for IoT applications, if the size of the solar cell module is reduced while maintaining a similar shape, the voltage can be maintained even with a smaller area.

[0069] Figure 5 , Figure 6 The top view is a top view taken from the light-receiving surface side (first substrate 2 side) of the solar cell modules 30a and 30b. The first terminals 15a-15t located on the light-receiving surface side are shown with solid lines, and the second terminals 16a-16t located on the back side are shown with dashed lines. Thus, by placing the first terminals 15a-15t on the light-receiving surface and the second terminals 16a-16t on the back side, the terminal polarity can be separated on the light-receiving surface and the back side. Therefore, by simply overlapping the two solar cell modules 30, the series-connected solar cells 25 included in one solar cell module 30 can be connected in series with the series-connected solar cells 25 included in the other solar cell module 30. The first terminals 15a-15t are arranged in a row along the lower end of the light-receiving surface (the first side extending in the long side direction of the solar cell module 30). Furthermore, the second terminals 16a-16t are arranged in a row along the upper end of the back side (the second side extending in the long side direction of the solar cell module 30). Therefore, connecting the two solar cell modules, connecting the first terminal 15 and the second terminal 16, or connecting the first terminal 15 or the second terminal 16 to the busbar becomes easy.

[0070] exist Figure 5 In the α-type solar cell module 30a shown, the first terminals 15a-15t are disposed at the lower left end of the light-receiving surface of the series-connected solar cells 25a-25t, and the second terminals 16a-16t are disposed at the upper right end of the back surface of the series-connected solar cells 25a-25t. Furthermore, in Figure 6In the ω-type solar cell module 30b shown, the first terminals 15a-15t are located at the lower right end of the light-receiving surface of the series-connected solar cells 25a-25t, and the second terminals 16a-16t are located at the upper left end of the back surface of the series-connected solar cells 25a-25t. Therefore, the configuration of the first terminals 15a-15t and the second terminals 16a-16t in the α-type solar cell module 30a is mirror-symmetrical to that in the ω-type solar cell module 30b. By overlapping the α-type solar cell module 30a and the ω-type solar cell module 30b, the first terminal 15 of the α-type solar cell module 30a and the second terminal 16 of the ω-type solar cell module 30b can be easily brought into contact, allowing the series-connected solar cells 25 in both the α-type and ω-type solar cell modules to be connected in series. Therefore, by overlapping the front and back terminals of α-type and ω-type solar cell modules of different types, series connection can be easily achieved, resulting in a high-efficiency connection.

[0071] Figure 7 (a) and Figure 8 These are schematic top views of solar cell array 40. Figure 7 (b) is a schematic cross-sectional view of the solar cell array 40. In the solar cell array 40, α-type solar cell modules 30a and ω-type solar cell modules 30b are alternately connected, and four solar cell modules 30 are connected. In these solar cell modules 30, such as Figure 7 As shown in (b), the upper end of the ω-type solar cell module 30b overlaps the lower end of the α-type solar cell module 30a, and a second terminal 16 of the ω-type solar cell module 30b is connected to each of the first terminals 15 included in the α-type solar cell module 30a. Furthermore, the upper end of the α-type solar cell module 30a overlaps the lower end of the ω-type solar cell module 30b, and a second terminal 16 of the α-type solar cell module 30a is connected to each of the first terminals 15 included in the ω-type solar cell module 30b. Each series-connected solar cell 25 includes five solar cell units 20a~20e; therefore, in the solar cell array 40, 20 series-connected solar cell units 20 are arranged in 20 arrays.

[0072] Figure 7 In the solar cell array 40 shown in (a), all the second terminals 16 of the uppermost α-type solar cell module 30a are electrically connected through the first busbar 31a, and all the first terminals 15 of the lowermost ω-type solar cell module 30b are electrically connected through the first busbar 31b. Twenty series connectors are connected in parallel through the first busbars 31a and 31b.

[0073] exist Figure 8 In the solar cell array 40 shown, the ten second terminals 16 on the left side of the topmost α-type solar cell module 30a are electrically connected via a first busbar 31a, and the ten second terminals 16 on the right side of the topmost α-type solar cell module 30a are electrically connected via a first busbar 31b. Furthermore, the ten first terminals 15 on the left side of the bottommost ω-type solar cell module 30b are electrically connected via a first busbar 31c, and the ten first terminals 15 on the right side of the bottommost ω-type solar cell module 30b are electrically connected via a first busbar 31d. Therefore, the ten series-connected units on the left side are connected in parallel using the first busesbars 31a and 31c, and the ten series-connected units on the right side are connected in parallel using the first busesbars 31b and 31d. In this way, by changing the number of series connections constituting the parallel connections, the current can be easily adjusted according to the system requirements. In solar cell modules 30a and 30b, by arranging multiple first terminals 15a-15t on the light-receiving surface of the solar cell module in a row along the long side of the solar cell module, and multiple second terminals 16a-16t on the back side of the solar cell module in a row along the long side of the solar cell module, the number of series-connected solar cells 25 connected in parallel can be adjusted. When connecting the solar cell modules, high voltage can be suppressed, and the current value can be increased. In addition, the solar cell system can be easily adjusted to meet the voltage and current requirements of IoT and mobile devices, making it suitable as an independent power supply device.

[0074] Figure 9 (a) to (c) show schematic diagrams illustrating the operation of current bypass when shading occurs in the solar cell module 30. Regarding the solar cell module 30, by integrating elongated rectangular solar cell units 20a to 20e, even in the case of localized shading, the entire surface of the solar cell unit 20 is hardly hidden, thus enabling power generation without interruption of the photoexcitation current. Furthermore, even if shading is applied to the entire surface of the solar cell unit 20 and the photoexcitation current is interrupted, the first blocking layer 9, which functions as a varistor, allows the photoexcitation current from the unshaded area to bypass to the adjacent solar cell unit 20, suppressing the reduction in power generation caused by shading. Other configurations are the same as in the first embodiment. Furthermore, the description of the first embodiment applies to the second embodiment as long as there is no contradiction.

[0075] Third Implementation Method

[0076] Figure 10 (a) is a partial top view of the α-type solar cell module 30a. Figure 10 (b) is a schematic cross-sectional view of the solar cell module 30a in the dashed-dot line BB. Furthermore, Figure 11(a) is a partial top view of the ω-type solar cell module 30b. Figure 11 (b) is a schematic cross-sectional view of the solar cell module 30b in the dashed line CC.

[0077] In this embodiment, the solar cell module 30 (30a, 30b) is rectangular. Furthermore, each of the series-connected solar cells 25a-25c included in the solar cell module 30 has an elongated shape. The shape of the series-connected solar cells 25 can be rectangular or parallelogram-shaped. First terminals 15a-15c are disposed on the light-receiving surface and at one end of the elongated shape. Second terminals 16a-16c are disposed on the back surface and at the other end of the elongated shape. Furthermore, the plurality of series-connected solar cells 25a-25c are arranged in parallel columns inclined relative to one side of the rectangle. In addition, the solar cell module 30 of this embodiment includes a second busbar 26 (26a, 26b). The second busbar 26 electrically connects two adjacent series-connected solar cells 25 included in the plurality of series-connected solar cells 25a-25c.

[0078] exist Figure 10 , Figure 11 In the solar cell modules 30a and 30b shown, the series-connected solar cells 25a to 25c are formed at an angle relative to the ends of the solar cell modules 30a and 30b (for example, θ ≈ 9.5°). Therefore, the first terminal 15 of one of two adjacent series-connected solar cells 25 and the second terminal 16 of the other series-connected solar cell 25 can be connected via a second busbar 26 (26a, 26b), which is arranged parallel to one side of the rectangular solar cell module 30. This allows two adjacent series-connected solar cells 25 to be connected in series.

[0079] For example, such as Figure 10 (b) Figure 11 As shown in (b), the second busbar 26b can have an elongated shape extending in a direction parallel to one side of the solar cell module 30, and is mainly disposed on the back side of the solar cell module 30, contacting the second terminal 16. Furthermore, the end of the second busbar 26b is bent like a hook and wound around the light-receiving surface to contact the first terminal 15. Using such a second busbar 26b, series-connected solar cells 25b and series-connected solar cells 25c can be connected in series. Moreover, such a second busbar 26 can be provided for each pair of two adjacent series-connected solar cells 25.

[0080] A high-voltage transformer can also be formed, which has multiple second busbars 26 evenly spaced on an organic film. By attaching such a high-voltage transformer to the back side of the solar cell module 30, the first terminal 15 of one of two adjacent series-connected solar cells 25 and the second terminal 16 of the other can be connected using each second busbar 26. Thus, the second busbars 26 can connect the series-connected solar cells 25 without interference, easily resulting in a high-voltage solar cell module. Furthermore, since the α-type solar cell module 30a and the ω-type solar cell module 30b are mirror-symmetrical, a high-voltage solar cell module can be obtained by using the same high-voltage transformer.

[0081] As a backbone device for providing independent power supply systems to mobile devices, including IoT and electric vehicles, thin-film perovskite solar cell modules can be provided.

Claims

1. A solar cell unit, characterized in that, It possesses: substrate; A first electrode is disposed on the substrate; A photoelectric conversion layer is disposed on the first electrode; The second electrode is disposed on the photoelectric conversion layer; as well as A barrier layer is provided to cover the sides of the photoelectric conversion layer. The photoelectric conversion layer comprises an electron transport layer, a light absorption layer disposed on the electron transport layer, and a hole transport layer disposed on the light absorption layer. The light-absorbing layer contains a compound with a perovskite crystal structure. The barrier layer is an inorganic material layer. The barrier layer contains more than 95 wt% zinc oxide as a matrix material and contains at least one of silicon oxide, aluminum oxide and titanium oxide as additives, and the barrier layer is made of a material exhibiting the characteristics of a varistor.

2. The solar cell unit according to claim 1, characterized in that, The barrier layer is connected to the first electrode and the second electrode, such that the barrier layer and the photoelectric conversion layer are connected in parallel.

3. A solar cell, characterized in that, It possesses: The solar cell units as described in claims 1 or 2; First terminal; and Second terminal, The multiple solar cell units are connected in series. Of the plurality of solar cell units, one end of the solar cell unit is connected to the first terminal, and the other end of the solar cell unit is connected to the second terminal.

4. A solar cell module, characterized in that, The solar cell described in claim 3 has multiple features. The first terminal is positioned on the light-receiving surface. The second terminal is disposed on the back side opposite to the light-receiving surface.

5. The solar cell module according to claim 4, characterized in that, The solar cell module is rectangular. The plurality of solar cells each have an elongated shape. The first terminal is disposed at one end of the elongated shape, and the second terminal is disposed at the other end of the elongated shape. The plurality of solar cells are arranged in parallel columns that are tilted relative to one side of the rectangle.

6. The solar cell module according to claim 5, characterized in that, The solar cell module also includes a busbar. The bus electrically connects two adjacent solar cells included in the plurality of solar cells.

7. The solar cell module according to any one of claims 4 to 6, characterized in that, The first terminals included in the solar cell module are arranged in a row. The second terminals included in the solar cell module are arranged in a row.

8. A solar cell array, characterized in that, A solar cell module comprising any one of claims 4 to 7, The plurality of solar cell modules include a first solar cell module and a second solar cell module, wherein the second solar cell module is connected to the first solar cell module. The first terminal and the second terminal of the first solar cell module are configured in a position that is mirror-symmetrical to the positions of the first terminal and the second terminal of the second solar cell module.

9. A solar cell, characterized in that, The solar cell has multiple solar cell units. The solar cell unit includes: substrate; A first electrode is disposed on the substrate; A photoelectric conversion layer is disposed on the first electrode; The second electrode is disposed on the photoelectric conversion layer; as well as A barrier layer is provided to cover the sides of the photoelectric conversion layer. The photoelectric conversion layer comprises an electron transport layer, a light absorption layer disposed on the electron transport layer, and a hole transport layer disposed on the light absorption layer. The light-absorbing layer contains a compound with a perovskite crystal structure. The barrier layer is an inorganic material layer. The first electrode of one of the plurality of solar cell units is spaced apart from the first electrode of another adjacent solar cell unit. The second electrode of one solar cell unit is spaced apart from the second electrode of the other solar cell unit. The first electrode of one solar cell unit is electrically connected to the second electrode of another solar cell unit. One of the solar cell units is connected in series with the other solar cell unit. In the solar cell unit, the barrier layer is made of a material exhibiting varistor characteristics, and the barrier layer is connected to the first electrode and the second electrode, such that the barrier layer and the photoelectric conversion layer are connected in parallel.

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