solar cells

Abstract

A solar cell is provided in which warping that may occur during manufacturing using a sheet-fed method is suppressed. [Solution] A solar cell (1) comprising a solar cell (100) having a first electrode (10), a photoelectric conversion layer (30), and a second electrode (50) in that order, and a transparent substrate (2) that holds the solar cell (100) from the first electrode (10) side and forms the light-receiving surface, with a first barrier layer (3) and an intervening layer (4) between the solar cell (100) and the transparent substrate (2).

Description

[Technical Field]

[0001] The present disclosure relates to a solar cell including a solar cell having a first electrode, a photoelectric conversion layer, and a second electrode in this order, and a substrate that supports the solar cell from the first electrode side and forms a light-receiving surface. [Background technology]

[0002] In recent years, solar cells have become increasingly popular as a way to utilize renewable energy.

[0003] BACKGROUND ART As solar cells, in addition to silicon solar cells that use a crystalline silicon substrate in a photoelectric conversion section, perovskite solar cells that contain a perovskite compound in a photoelectric conversion layer are known.

[0004] The solar cell 1 disclosed in Patent Document 1 is obtained by laminating a substrate 10, a first electrode layer 21, a first carrier transport layer 31, a perovskite thin film 40, a second electrode layer 22, etc. on a film-deposited plate 100, and then performing, for example, mechanical peeling or thermal peeling between the film-deposited plate 100 and the substrate 10. The relevant terms and symbols are those in Patent Document 1.

[0005] However, because the solar cell 1 has an extremely thin structure, when the solar cell 1 formed on the film-formed plate 100 in a sheet-by-sheet manufacturing process is peeled off from the film-formed plate 100, warping may occur in the substrate 10 of the solar cell 1. If warping occurs in the substrate 10, the moisture resistance of the substrate 10 decreases. Note that warping also includes bending and folding. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2023 / 190007 Summary of the Invention [Problem to be solved by the invention]

[0007] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a solar cell in which warping that can occur during manufacturing using a single-wafer method is suppressed. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the solar cell according to the present disclosure is a solar cell comprising a solar cell having a first electrode, a photoelectric conversion layer, and a second electrode in that order, and a substrate that holds the solar cell from the first electrode side and forms a light-receiving surface, and is characterized by having a barrier layer and an intervening layer between the solar cell and the substrate.

[0009] According to the above-described configuration, even when the solar cell is peeled off from the glass substrate in a sheet-by-sheet process, the intervening layer is provided between the solar cell and the substrate, so that warping of the solar cell can be suppressed.

[0010] The barrier layer is a layer that can prevent moisture in the atmosphere from passing from the substrate side to the solar cell side, and the intervening layer is a layer that is interposed between the substrate and the solar cell.

[0011] In the present disclosure, the intermediate layer may be a stress relaxation layer that relieves residual stress in the barrier layer.

[0012] According to the above-described configuration, the presence of the intervening layer can reduce warpage of the barrier layer.

[0013] In the present disclosure, the intermediate layer may be interposed between the solar cell and the barrier layer.

[0014] In the present disclosure, the intermediate layer may be interposed between the substrate and the barrier layer.

[0015] In the present disclosure, the photoelectric conversion layer may be characterized by including a perovskite compound.

[0016] The barrier layer may include silicon nitride or silicon oxynitride, and the intermediate layer may include silicon oxide.

[0017] In the present disclosure, the device may be characterized in that a hole transport layer is provided between the first electrode and the photoelectric conversion layer, and an electron transport layer is provided between the photoelectric conversion layer and the second electrode.

[0018] In the present disclosure, the device may be characterized in that an electron transport layer is provided between the first electrode and the photoelectric conversion layer, and a hole transport layer is provided between the photoelectric conversion layer and the second electrode.

[0019] In the present disclosure, the photoelectric conversion layer may have a porous layer adjacent to the hole transport layer or the electron transport layer.

[0020] In the present disclosure, the substrate may be characterized in that it is made of a resin substrate having a thickness in the range of 5 to 35 μm.

[0021] In the present disclosure, the substrate may be characterized in that it is made of a resin substrate having a thickness in the range of 5 to 20 μm.

[0022] In the present disclosure, the substrate may be characterized in that it is made of a resin substrate having a thickness in the range of 10 to 15 μm. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic cross-sectional view of a solar cell according to the present disclosure. [Figure 2] FIG. 2 is a schematic cross-sectional view of a solar cell according to the present disclosure fabricated on a glass substrate. [Figure 3] FIG. 3 is a schematic explanatory diagram showing how the edge of the glass substrate is scribed. [Figure 4] FIG. 4 is a schematic explanatory diagram of a glass substrate with its edge separated. [Figure 5]FIG. 5 is a schematic cross-sectional view of a solar cell according to the present disclosure being peeled off from a glass substrate. [Figure 6] FIG. 6 is a schematic cross-sectional view of a solar cell according to the present disclosure peeled off from a glass substrate. [Figure 7] FIG. 7 is a schematic cross-sectional view of a conventional solar cell fabricated on a glass substrate. [Figure 8] FIG. 8 is a schematic diagram of a conventional solar cell peeled off from a glass substrate. [Figure 9] FIG. 9 is a schematic diagram illustrating warpage of a conventional solar cell. [Figure 10] Figure 10 is an enlarged image of a transparent substrate with a thickness of 15 μm. [Figure 11] Figure 11 is an enlarged image of a transparent substrate with a thickness of 38 μm. DETAILED DESCRIPTION OF THE INVENTION

[0024] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. The embodiments described below do not unnecessarily limit the content of the present disclosure as defined in the claims, and not all of the configurations described in the following embodiments are necessarily essential to the solutions of the present disclosure. Furthermore, for illustrative purposes, the light incident side (i.e., the light receiving surface side of the solar cell) is expressed as the lower side, and the side opposite the light incident side as the upper side. However, this is for convenience and does not affect the installation orientation or the recommended installation orientation. The above-mentioned configurations can be reversed as long as there is no contradiction. In other words, the present disclosure is valid even if the light incident side and the side opposite the light incident side are interchanged as long as there is no contradiction. In the following description, as a general rule, the same components are denoted by the same reference numerals, and their names and functions are the same unless otherwise specified. Therefore, in such cases, detailed descriptions thereof will not be repeated.

[0025] First Embodiment 1. Solar cells FIG. 1 is a schematic cross-sectional view of a solar cell 1 including a solar cell 100 according to this embodiment.

[0026] The solar cell 1 is configured by providing solar cells 100 on a transparent substrate 2. When there is no need to distinguish between the solar cell 1 and the solar cell 100, they may be simply referred to as solar cell 1.

[0027] 1, the solar cell 100 is configured by stacking a first electrode 10, a hole transport layer 20, a photoelectric conversion layer 30 containing a perovskite compound, an electron transport layer 40, and a second electrode 50 in this order. In the solar cell 1, a first barrier layer 3 and an intervening layer 4 are provided between a transparent substrate 2 and the solar cell 100, and a second barrier layer 5 is provided so as to cover the solar cell 100.

[0028] Each component is described in detail below. In the solar cell 100 of the first embodiment, the first electrode 10 is in contact with the hole transport layer 20, the hole transport layer 20 is in contact with the photoelectric conversion layer 30, the photoelectric conversion layer 30 is in contact with the electron transport layer 40, and the electron transport layer 40 is in contact with the second electrode 50. However, this does not exclude the case where the first electrode 10 and the second electrode 50 are not in contact with each other and another layer is interposed between them. In any case, adjacent layers from the first electrode 10 to the second electrode 50 are electrically connected to each other. Furthermore, the hole transport layer 20 and the electron transport layer 40 are not necessarily required. Naturally, if the first electrode 10 or the second electrode 50 can also fulfill the roles of the hole transport layer 20 and the electron transport layer 40, the hole transport layer 20 and the electron transport layer 40 are unnecessary. Similarly, it goes without saying that if other layers can fulfill the roles of the other layers, the other layers are unnecessary.

[0029] [Transparent base] The transparent substrate 2 is disposed on the light-receiving surface side of the solar cell 1. The transparent substrate 2 supports the solar cell 100 and is made of a transparent resin material. Note that "transparent" means that it transmits light, but does not exclude materials that reflect or absorb light even slightly. It is sufficient that it is disposed on the light-receiving surface side of the solar cell 1 and transmits light appropriately, and it can be considered synonymous with being disposed on the light-receiving surface side of the solar cell 1. Therefore, being disposed at least on the light-receiving surface side can be considered transparent. In other words, the transparent substrate 2 refers to a substrate disposed on the light-receiving surface side of the solar cell 1. In this disclosure, unless otherwise specified, simply referring to a substrate means the transparent substrate 2.

[0030] A transparent resin material such as an organic film is preferably used as the material for the transparent substrate 2. Specific examples of the transparent resin material include polyimide (PI), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyetherimide (PEI), polytetrafluoroethylene (PTFE), polyamideimide (PAI), and polyethylene naphthalate (PEN), but other resins can also be used as long as they meet the requirements.

[0031] However, the transparent substrate 2 does not have a very high moisture resistance. Therefore, in order to ensure moisture resistance for the solar cell 100, a first barrier layer 3 is provided between the transparent substrate 2 and the solar cell 100.

[0032] Since the transparent substrate 2 supports the solar cell 100, it is conceivable to increase the thickness of the transparent substrate 2 in order to stabilize the shape against the in-plane stress (e.g., in-plane stress in the compressive direction) of the first barrier layer 3, which will be described later. The in-plane stress (residual stress in the compressive direction) of the first barrier layer 3 is depicted by a pair of outward dashed arrows in Figures 1 to 8. The in-plane stress (residual stress in the tensile direction) of the intervening layer 4 is depicted by a pair of inward dashed arrows in Figures 1 to 6.

[0033] The first electrode 10 is processed into a desired pattern by photolithography or laser ablation from the transparent substrate 2 side so that the current generated by photoexcitation in the photoelectric conversion layer 30 can be extracted to the first electrode 10 without leakage loss. However, when laser light is irradiated onto the first electrode 10, the transparent substrate 2 also absorbs the laser light and applies thermal energy. Increasing the thickness of the transparent substrate 2 increases the amount of laser light absorbed and the amount of heat generated, which may proportionally cause partial deformation or deterioration. Areas of the transparent substrate 2 where deformation or deterioration has occurred may develop pinholes, which may cause moisture penetration into the solar cell 100.

[0034] Therefore, it is not preferable to increase the thickness of the transparent substrate 2. As a result of intensive research by the inventors, it has been found that the upper limit of the thickness of the transparent substrate 2 is approximately 35 μm in order to prevent the transparent substrate 2 from deforming or changing in quality due to heat absorption by the laser.

[0035] Figure 10 is a magnified observation image of a transparent substrate with a thickness of 15 μm. On the other hand, Figure 11 is a magnified observation image of a transparent substrate with a thickness of 38 μm. Both are magnified observation images after irradiation with laser light under the same conditions, and traces of deterioration were confirmed in the 38 μm thick transparent substrate shown in Figure 11.

[0036] As a result of further research by the inventors, it was found that the thickness of the transparent substrate 2 is preferably in the range of 5 to 35 μm, more preferably in the range of 5 to 20 μm, and even more preferably in the range of 10 to 15 μm. In this specification, unless otherwise specified, the range allows for errors during the production of the transparent substrate 2.

[0037] [First barrier layer] The first barrier layer 3 is provided between the transparent substrate 2 and the solar cell 100. The first barrier layer 3 is the barrier layer in the claims.

[0038] The first barrier layer 3 may be made of a highly gas and moisture-proof material, a dense inorganic material layer, or an insulating material, and may be made of, for example, silicon nitride (SiN), silicon oxynitride (SiON), or the like deposited by reactive sputtering or plasma CVD, or a film of a metal oxide such as silicon dioxide (SiO2), aluminum oxide (Al2O3), zirconium oxide (ZrO2), sodium oxide (Na2O), or boron oxide (BO3), or a film of a composite material (glass composition) thereof. In this way, it is possible to prevent moisture and the like from penetrating the photoelectric conversion layer 30.

[0039] In the reactive sputtering method, silicon atoms are sputtered from a silicon target onto the transparent substrate 2 and reacted with an inert gas such as nitrogen (N2) or oxygen (O2) to form a film on the surface of the transparent substrate 2. In the plasma CVD method, a gas containing silicon elements is sent to the surface of the transparent substrate 2, and a film is formed through chemical reaction and decomposition.

[0040] The highly moisture-resistant first barrier layer 3 tends to have a high film density and strong in-plane stress (e.g., compressive residual stress). In a conventional single-wafer manufacturing process, as shown in Figures 7 and 8, after forming a solar cell 1 on a glass substrate 7, the solar cell 1 is peeled off from the glass substrate 7. However, when the solar cell 1 is released from the support of the glass substrate 7, the in-plane stress (e.g., compressive residual stress) of the first barrier layer 3 can cause significant warping of the solar cell 1, as shown in Figure 9.

[0041] Warping of the first barrier layer 3 causes cracks and pinholes, significantly reducing moisture resistance. Furthermore, warping of the solar cell 1 causes problems such as unstable shape when a solar cell module is manufactured using multiple solar cells 1, making handling in later processes inconvenient.

[0042] Therefore, the solar cell 1 according to the present disclosure is intended to reduce warpage of the first barrier layer 3 by including the intermediate layer 4. In other words, the intermediate layer 4 is a stress relaxation layer that relieves the residual stress of the first barrier layer 3.

[0043] [Intervening layer] The intermediate layer 4 is disposed between the first barrier layer 3 and the first electrode 10 and adjacent to the first barrier layer 3. The intermediate layer 4 may be formed of silicon oxide (SiO2) deposited by reactive sputtering or plasma CVD, for example, as long as it has an in-plane stress (e.g., residual stress in a tensile direction) capable of countering the in-plane stress (e.g., residual stress in a compressive direction) of the first barrier layer 3. The in-plane stress of the intermediate layer 4 can be controlled by adjusting the film density, for example, by adjusting parameters such as the film formation rate and gas concentration during film formation. Therefore, even if the first barrier layer 3 and the intermediate layer 4 are formed of the same material, the film density of the intermediate layer 4 can be controlled to have an in-plane stress capable of countering the in-plane stress of the first barrier layer 3. In this disclosure, the chemical formulas in parentheses after the compound names are representative examples. Although the composition ratios described in the chemical formulas are preferably stoichiometric, they are not necessarily stoichiometric.

[0044] The film density can be measured by X-ray reflectivity (XRR). If the measurement results show that, for example, the first barrier layer 3 and the intermediate layer 4 are made of the same material, at least the intermediate layer 4 has an in-plane stress (tensile residual stress) that is capable of countering the compressive residual stress of the first barrier layer 3, then it can be said that the intermediate layer 4 relieves the residual stress of the first barrier layer 3.

[0045] For example, the film used as first barrier layer 3 tends to have a high film density due to its high barrier performance, and in this case, it has compressive residual stress. In contrast, intermediate layer 4 has a low film density and therefore has tensile residual stress. Therefore, it can be said that intermediate layer 4 relieves the residual stress of first barrier layer 3.

[0046] It is desirable that the first barrier layer 3 be made of silicon nitride or silicon oxynitride, while the intermediate layer 4 be made of silicon oxide, for example. This allows the intermediate layer 4 to relieve residual stress in the first barrier layer 3.

[0047] As shown in Figure 1, by providing such an intervening layer 4, the in-plane stress (e.g., residual stress in the compressive direction) of the first barrier layer 3 can be alleviated, and therefore, even if the solar cell 1 is peeled off from the glass substrate 7, warping of the solar cell 1 can be suppressed.

[0048] The specific configuration of the intermediate layer 4, such as its thickness and material, is designed depending on the in-plane stress (direction and magnitude of residual stress) of the first barrier layer 3. Therefore, when the in-plane stress of the first barrier layer 3 is a tensile residual stress, the intermediate layer 4 is designed to have a compressive residual stress.

[0049] [First electrode] The first electrode 10 corresponds to the anode of the solar cell 1. The thickness of the first electrode 10 may be, for example, 30 nm or more and 1000 nm or less. Examples of materials constituting the first electrode 10 include transparent conductive materials (particularly, transparent conductive oxides (TCOs)) and non-transparent conductive materials. Examples of transparent conductive materials include copper iodide (CuI), indium tin oxide (ITO), tin(IV) oxide (SnO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), indium zinc oxide (IZO), and gallium-doped zinc oxide (GZO). Non-transparent conductive materials can also have transparency depending on the thickness of the material, and therefore can be used as an electrode on the light-receiving surface of a photoelectric conversion element.

[0050] [Hole transport layer] The hole transport layer 20 is a layer containing a material that facilitates the transfer of holes generated in the photoelectric conversion layer 30 to the first electrode 10. As long as the solar cell 1 has a photoelectric conversion function, it is self-evident that the hole transport layer 20 has a hole transport function as long as it is located on the hole transport side of the photoelectric conversion layer 30, and no further confirmation is required. In other words, the hole transport layer 20 refers to a layer located on the hole transport side of the photoelectric conversion layer 30. The thickness of the hole transport layer 20 may be, for example, 40 nm to 600 nm. In this disclosure, unless otherwise specified, the term "layer" or "film" does not necessarily mean a layer or film having a uniform thickness or width, and includes layers having portions of varying thickness, or layers having a patterned or island-like structure. Preferably, the term "layer" or "film" refers to a layer or film having a substantially uniform thickness. Unless otherwise specified, the terms "approximately" and "approximately" refer to the manufacturing error, i.e., the margin of error during fabrication, and preferably allow for a variation of plus or minus 15% of the numerical value.

[0051] The hole transport layer 20 can be formed by, for example, sputtering, die coating, screen printing, or the like.

[0052] By covering the front and back of the photoelectric conversion layer 30 with the first electrode 10 and the second electrode 50, holes and electrons can move in the first electrode 10 and the second electrode 50 in a direction along the layers of the hole transport layer 20, the photoelectric conversion layer 30, and the electron transport layer 40, thereby avoiding a decrease in efficiency.

[0053] Examples of the hole transport material constituting the hole transport layer 20 include organic hole transport materials and inorganic hole transport materials.

[0054] In this specification, "organic (organic substance)" typically refers to a substance composed of multiple carbon elements. Carbon materials such as graphite, graphene, carbon nanowires, carbon nanofibers, carbon nanotubes, and carbon or carbon black that function as electrodes are not considered to be organic (organic substance). In other words, "organic" refers to a substance that has multiple carbon elements as one of its constituent elements, excluding carbon materials such as graphite.

[0055] Furthermore, "inorganic" refers to something that is not organic. That is, the hole transport layer 20 refers to a layer that contains a plurality of carbon atoms as one of its constituent elements, and also contains a plurality of non-carbon atoms, such as metal atoms, halogen atoms, chalcogen atoms, or metal chalcogenides. The same applies to the electron transport layer 40.

[0056] Examples of organic hole transport materials that can be suitably used in the hole transport layer 20 include Spiro-TTB (2,2',7,7'-tetra(N,N-di-tolyl)amino-spiro-bifluorene), Spiro-OMeTAD (2,2',7,7'-tetrakis(N,N-di-p-methoxyphenilamine)-9,9' -spirobifluorene), PTAA(Polytriarylamine), P3CT-N(Poly[3-(4-carboxylatebutyl)thiophene]-CH3NH2), Poly-TPD(Poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine] ), P3HT(Poly(3-hexylthiophene)), PEDOT:PSS(Poly(3,4-EthyleneDiOxyThiophene) / Poly(4-StyreneSulfonate)), 2PACz([2-(9H-Carbazol-9-yl)ethyl]phosphonic-Acid), 4PACz([4-( 9H-Carbazol-9-yl)butyl]phosphonic-Acid), MeO-2PACz([2-(3,6-Dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic-Acid), MeO-4PACz((4-(3,6-Dimethoxy-9H-carbazol-9-yl)butyl) Me-2PACz ((2-(3,6-Dimethyl-9H-carbazol-9-yl)ethyl)phosphonic-acid), Me-4PACz ([4-(3,6-Dimethyl-9H-carbazol-9-yl)butyl]phosphonic-acid), and the like.

[0057] Examples of inorganic hole transport materials that can be suitably used for the hole transport layer 20 include nickel (II) oxide (NiO), molybdenum dioxide (MoO), tin (II) oxide (SnO), molybdenum disulfide (MoS), copper oxide (CuO), Li ion and Mg ion doped nickel oxide (NiMgLiO), Mg ion doped nickel oxide (NiMgO), Li ion doped nickel oxide (NiLiO), and the like.

[0058] The above hole transport materials are merely examples, and materials other than those exemplified above can also be used as long as they can exhibit the same function.

[0059] [Photoelectric conversion layer] The photoelectric conversion layer 30 is a layer capable of absorbing light and generating holes and electrons. It preferably contains a perovskite compound. The photoelectric conversion layer 30 can be formed by a predetermined coating method (including, but not limited to, slit coating, spraying, and other methods) or vacuum deposition (co-deposition, in which multiple materials are heated with a heater to perform vapor phase synthesis; layered deposition, in which layers are layered and heated to crystallize; laser heating of a single material, and other methods). While any coating method is acceptable, it is preferable that the method be capable of coating and forming within a predetermined range. The thickness of the photoelectric conversion layer 30 may be, for example, 100 nm or more and 1000 nm or less.

[0060] The perovskite compound contained in the photoelectric conversion layer 30 is preferably composed of a compound (perovskite compound) represented by the general formula: ABX3 (1). However, although the composition ratio of each element is preferably 1:1:3, it is not necessarily 1:1:3, the content of each element may be increased or decreased as appropriate, and each constituent element does not necessarily have to be of one type, and as long as the photoelectric conversion layer 30 has a photoelectric conversion function, there is a degree of freedom in the configuration as described above.

[0061] In general formula (1), A is an organic molecule (including an organic group or an organic cation), an inorganic atom or molecule (including an inorganic group or an inorganic cation), or a combination thereof, B is a metal atom or molecule (including a metal cation), and X is a halogen atom or molecule or a chalcogen atom or molecule (including a halogen anion or a chalcogen anion). In general formula (1), the three Xs may be the same or different.

[0062] When contained in the photoelectric conversion layer 30, the perovskite compound is capable of absorbing light and converting it into electricity, and this fact should also be taken into consideration. That is, a perovskite compound can be determined, for example, by containing organic molecules, metal atoms, and halogen atoms.

[0063] Furthermore, a perovskite compound can be determined by detecting elements corresponding to A, B, and X, so long as the photoelectric conversion layer 30 has a photoelectric conversion function. For example, organic molecules are preferably molecules containing carbon, nitrogen, and hydrogen, and therefore, it is sufficient to detect carbon, nitrogen, hydrogen, a metal element, and a halogen element or a chalcogen element. Alternatively, a perovskite compound can be determined by having A, B, and X, for example, by detecting an inorganic atom, a metal atom, and a halogen atom.

[0064] Furthermore, as long as the photoelectric conversion layer 30 has a photoelectric conversion function, the presence of a perovskite compound can be confirmed by detecting elements corresponding to A, B, and X. For example, cesium or rubidium is suitable as the inorganic atom, and therefore, it is sufficient if cesium or rubidium, a metal element, and a halogen or chalcogen are detected.

[0065] Furthermore, the presence of a perovskite compound is not necessarily required, since it is a natural consequence that the photoelectric conversion layer 30 must have a crystalline structure in order to have a photoelectric conversion function. The photoelectric conversion layer 30 may also contain compounds other than perovskite compounds.

[0066] The photoelectric conversion layer 30 may contain an organic-inorganic hybrid compound. The organic-inorganic hybrid compound refers to a compound containing an inorganic material and an organic material.

[0067] Solar cells using perovskite compounds, which are organic-inorganic hybrid compounds, are also called organic-inorganic hybrid solar cells. The term "organic-inorganic hybrid compound" refers to a compound that contains multiple carbon atoms as one of its constituent elements, and also contains compounds that do not contain multiple carbon atoms as constituent elements, such as metal atoms, halogen atoms, or chalcogen atoms.

[0068] [Electron transport layer] The electron transport layer 40 is a layer containing a material that easily transfers electrons generated in the photoelectric conversion layer 30 to the second electrode 50. As long as the solar cell 1 has a photoelectric conversion function, it is self-evident that the electron transport layer 40 has the function of transporting electrons as long as the electron transport layer 40 is located on the electron transport side of the photoelectric conversion layer 30, and no confirmation is required. In other words, the electron transport layer 40 refers to a layer that is located on the electron transport side of the photoelectric conversion layer 30. The thickness of the electron transport layer 40 may be, for example, 10 nm to 200 nm.

[0069] The electron transport layer 40 can be formed by, for example, sputtering, die coating, screen printing, or the like.

[0070] Examples of the electron transport material constituting the electron transport layer 40 include organic electron transport materials and inorganic electron transport materials.

[0071] Examples of organic electron transport materials that can be suitably used for the electron transport layer 40 include PCBM ([6,6]-Phenyl-C 61 -Butyric Acid Methyl Ester), C 60 (Fullerene), BCP (1-Bromo-3-chloropropane), NBphen ([2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline]), etc.

[0072] Examples of inorganic electron transport materials that can be suitably used for the electron transport layer 40 include tin(IV) oxide (SnO), zinc tin composite oxide (ZTO), indium tin oxide (IZO), titanium(IV) oxide (TiO), zinc oxide (ZnO), lithium fluoride (LiF), sodium fluoride (NaF), magnesium fluoride (MgF), and calcium fluoride (CaF).

[0073] The above electron transport materials are merely examples, and materials other than those listed above can also be used as long as they can exhibit the same functions.

[0074] [Second electrode] The second electrode 50 corresponds to the cathode of the solar cell 1. The thickness of the second electrode 50 may be, for example, 50 nm or more and 300 nm or less. Examples of materials that can form the second electrode 50 include metals, transparent conductive inorganic materials, conductive fine particles, and conductive polymers (particularly, transparent conductive polymers).

[0075] Examples of metals include nickel (Ni), gold (Au), silver (Ag), platinum (Pt), and palladium (Pd). Examples of transparent conductive inorganic materials include copper iodide (CuI), indium tin oxide (ITO), tin(IV) oxide (SnO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), indium zinc oxide (IZO), and gallium-doped zinc oxide (GZO). Examples of conductive particles include silver nanowires and carbon nanofibers. Examples of transparent conductive polymers include PEDOT:PSS (Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate). Furthermore, carbon materials such as graphite can also be used for the second electrode 50.

[0076] It is not necessary to use an opaque material for the second electrode 50. When the second electrode 50 is a transparent electrode, the same material as that of the first electrode 10 described above may be used.

[0077] [Second barrier layer] The second barrier layer 5 is provided on the second electrode 50. The second barrier layer 5 may be made of a highly gas and moisture-proof material, a dense inorganic material layer, or an insulating material, and may be made of, for example, silicon nitride (SiN), silicon oxynitride (SiON), or the like deposited by reactive sputtering or plasma CVD, or a film of a metal oxide such as silicon dioxide (SiO), aluminum oxide (AlO), zirconium oxide (ZrO), sodium oxide (NaO), or boron oxide (BO), or a film of a composite material (glass composition) thereof. In this way, it is possible to prevent moisture and the like from penetrating the photoelectric conversion layer 30.

[0078] In the reactive sputtering method, silicon atoms are sputtered onto the second electrode 50 from a silicon target and reacted with an inert gas such as nitrogen (N2) or oxygen (O2), thereby forming a film on the surface of the second electrode 50. In the plasma CVD method, a gas containing silicon elements is sent to the surface of the second electrode 50, and a film is formed through chemical reaction and decomposition. Note that, like the first barrier layer 3, the second barrier layer 5 may also have in-plane stress (e.g., compressive residual stress), and therefore, an intermediate layer having in-plane stress (e.g., tensile residual stress) capable of resisting the in-plane stress may be provided adjacent to the second barrier layer 5. Note that the intermediate layer may also be configured in the same manner as the intermediate layer 4 described above.

[0079] The solar cell 1 configured as above is manufactured on a glass substrate 7 as shown in FIG. 2 in the following procedure.

[0080] First, the surface of the glass substrate 7 is washed with pure water or an organic solvent. A polyimide resin is applied to the clean glass substrate 7, free from dust or other adhesions, by spin coating or the like, and is then baked in a nitrogen gas atmosphere at about 350°C for about 2 hours (1 hour for temperature increase and 1 hour for temperature retention) to cause imidization. This forms the transparent substrate 2. At this time, the thickness of the transparent substrate 2 is, as described above, in the range of 5 to 35 μm, preferably in the range of 5 to 20 μm, and more preferably in the range of 10 to 15 μm.

[0081] Before applying the polyimide resin that constitutes the transparent substrate 2, if a release agent (such as a silane coupling agent) is applied to the surface of the glass substrate 7 and allowed to dry, the transparent substrate 2 can be easily peeled off from the glass substrate 7.

[0082] Since the transparent substrate 2 has low moisture resistance, a first barrier layer 3 for moisture prevention is laminated on the transparent substrate 2. The first barrier layer 3 is formed by coating the transparent substrate 2 with silicon nitride (SiN), silicon oxide (SiO), or silicon oxynitride (SiON). The method for coating the first barrier layer 3 is not particularly limited.

[0083] Next, the intervening layer 4 is coated on the first barrier layer 3. The intervening layer 4 is formed, for example, by depositing silicon oxide (SiO2) using a reactive sputtering method or a plasma CVD method. The intervening layer 4 may have an in-plane stress (e.g., a tensile residual stress) that can counter the in-plane stress (e.g., a compressive residual stress) of the first barrier layer 3. The provision of the intervening layer 4 can alleviate the in-plane stress (e.g., a compressive residual stress) of the first barrier layer 3, thereby preventing warping of the solar cell 1 even when the solar cell 1 is peeled off from the glass substrate 7, as described below.

[0084] Thereafter, the first electrode 10 of the solar cell 100 is formed by sputtering on the intervening layer 4. At this time, the first electrode 10 is preferably formed to a thickness such that the surface resistance of the first electrode 10 is 15 Ω / sq. or less.

[0085] The first electrode 10 is processed into a desired pattern by photolithography or laser ablation so that a current generated by photoexcitation in the photoelectric conversion layer 30 can be extracted to the first electrode 10 without leakage loss.

[0086] After the first electrode 10 is formed, a hole transport layer 20 is formed on the first electrode 10. The hole transport layer 20 is formed, for example, by forming a nickel (II) oxide (NiO) film by a sputtering method. In order to form the film in a desired area, photolithography or laser patterning is performed.

[0087] After the hole transport layer 20 is formed, the photoelectric conversion layer 30 is formed on the hole transport layer 20. The photoelectric conversion layer 30 is formed by applying a lead iodide compound having a perovskite crystal structure, such as methylammonium lead iodide (MAPbI3) or cesium lead triiodide (CsPbI3), using a predetermined coating method (including, but not limited to, slit coating, spraying, and other methods) or vacuum deposition (co-deposition, in which multiple materials are heated with a heater to perform vapor phase synthesis, layered deposition, in which layers are layered and heated to crystallize, or laser heating of a single material, etc.).

[0088] After the photoelectric conversion layer 30 is formed, the electron transport layer 40 is formed on the photoelectric conversion layer 30. The electron transport layer 40 is made of C 60 The electron transport layer 40 is formed by vacuum-depositing a layer of fullerene (BCP) to a thickness of about 10 to 100 nm, and then vacuum-depositing a layer of 1-bromo-3-chloropropane (BCP), which functions as a hole-blocking layer, to a thickness of about 1 to 50 nm (preferably 2 to 20 nm) on top of the layer. Attaching a deposition mask to the glass substrate 7 during vacuum deposition allows the electron transport layer 40 to be formed in the desired location.

[0089] After the electron transport layer 40 is formed, the second electrode 50 is formed on the electron transport layer 40. The second electrode 50 is formed by vacuum deposition of aluminum (Ag). Note that, by attaching a deposition mask to the glass substrate 7 during the vacuum deposition, the second electrode 50 can be formed in a desired location.

[0090] After the second electrode 50 is formed, a second barrier layer 5 for moisture prevention is deposited on the second electrode 50. The second barrier layer 5 is formed by coating silicon oxide (SiO2) on the second electrode 50. The method for coating the second barrier layer 5 is not particularly limited.

[0091] As described above, the transparent substrate 2, first barrier layer 3, intervening layer 4, first electrode 10, hole transport layer 20, photoelectric conversion layer 30, electron transport layer 40, second electrode 50, and second barrier layer 5 are laminated in this order on the glass substrate 7. Furthermore, the second barrier layer 5 side is covered and protected by a laminate film (not shown).

[0092] Thereafter, as shown in FIG. 3, a scribe line 9 is made on the rear surface of the glass substrate 7 at a position 10 to 50 mm from the edge of the glass substrate 7 using a scribing tool 8, and pressure is applied to the scribe line 9 to separate the edge of the glass substrate 7. This exposes the edge of the transparent substrate 2 as shown in FIG. 4, and the edge is then grasped to peel the solar cell 1 from the glass substrate 7 as shown in FIG. 5. Alternatively, the edge of the transparent substrate 2 may be left exposed without being covered with a laminate film, and the edge protruding from the laminate film may be cut with a cutter or the like to form an edge surface, and the solar cell 1 may be peeled from the glass substrate 7 by grasping the edge surface.

[0093] 1, the solar cell 1 is provided with the intervening layer 4 that relieves the stress of the first barrier layer 3, which prevents the solar cell 1 from warping even after it is peeled off from the glass substrate 7. After peeling off the solar cell 1 from the glass substrate 7, the solar cell 1 is protected by being covered with a laminate film (not shown) from the transparent substrate 2 side.

[0094] Terminal leads such as bus bars are then attached to the solar cell 1, and the entire solar cell is coated with various materials while leaving the terminals exposed, thereby achieving a solar cell 1 that is flexible while ensuring reliability.

[0095] Second Embodiment 6, the solar cell 1 of the second embodiment has an intervening layer 4 and a first barrier layer 3 provided in this order on a transparent substrate 2. Even with this configuration, warping is suppressed, similar to the solar cell 1 of the first embodiment.

[0096] <Other embodiments> Both the solar cell 100 according to the first embodiment and the solar cell 100 according to the second embodiment described above have a configuration in which a first electrode 10, a hole transport layer 20, a photoelectric conversion layer 30 containing a perovskite compound, an electron transport layer 40, and a second electrode 50 are stacked in this order on a transparent substrate 2, but the configuration is not limited to this.

[0097] For example, a second electrode 50, an electron transport layer 40, a photoelectric conversion layer 30 containing a perovskite compound, a hole transport layer 20, and a first electrode 10 may be laminated in this order on a transparent substrate 2, with a first barrier layer 3 and an intervening layer 4 interposed therebetween. In this case, the first electrode 10 is in contact with the electron transport layer 40, the electron transport layer 40 is in contact with the photoelectric conversion layer 30, the photoelectric conversion layer 30 is in contact with the hole transport layer 20, and the hole transport layer 20 is in contact with the second electrode 50.

[0098] This embodiment can also be modified such that the intervening layer 4 and the first barrier layer 3 are provided in this order on the transparent substrate 2. Even with this configuration, warping is suppressed in the same way as in the solar cell 1 according to the first embodiment.

[0099] Furthermore, the photoelectric conversion layer 30 may have a porous layer adjacent to the electron transport layer 40, that is, a so-called mesoporous structure.

[0100] (Addendum) [Aspect 1] A solar cell comprising a solar cell having a first electrode, a photoelectric conversion layer, and a second electrode in this order, and a substrate that supports the solar cell from the first electrode side and forms a light-receiving surface, A solar cell comprising a barrier layer and an intervening layer between the solar cell and the substrate. [Aspect 2] 2. The solar cell according to aspect 1, wherein the intermediate layer is a stress relaxation layer that relieves residual stress in the barrier layer. [Aspect 3] 3. The solar cell according to aspect 1 or 2, wherein the intervening layer is interposed between the solar cell and the barrier layer. [Aspect 4] 3. The solar cell according to aspect 1 or 2, wherein the intermediate layer is interposed between the substrate and the barrier layer. [Aspect 5] 5. The solar cell according to any one of aspects 1 to 4, wherein the photoelectric conversion layer contains a perovskite compound. [Aspect 6] the barrier layer comprises silicon nitride or silicon oxynitride; 6. The solar cell of any one of aspects 1 to 5, wherein the intervening layer comprises silicon oxide. [Aspect 7] a hole transport layer between the first electrode and the photoelectric conversion layer; 7. The solar cell according to any one of aspects 1 to 6, further comprising an electron transport layer between the photoelectric conversion layer and the second electrode. [Aspect 8] an electron transport layer between the first electrode and the photoelectric conversion layer; 7. The solar cell according to any one of aspects 1 to 6, further comprising a hole transport layer between the photoelectric conversion layer and the second electrode. [Aspect 9] 9. The solar cell according to aspect 8, wherein the photoelectric conversion layer has a porous layer adjacent to the hole transport layer or the electron transport layer. [Aspect 10] 10. The solar cell according to any one of aspects 1 to 9, wherein the base is made of a resin base having a thickness in the range of 5 to 35 μm. [Aspect 11] 10. The solar cell according to any one of aspects 1 to 9, wherein the base is made of a resin base having a thickness in the range of 5 to 20 μm. [Aspect 12] 10. The solar cell according to any one of aspects 1 to 9, wherein the base is made of a resin base having a thickness in the range of 10 to 15 μm.

[0101] The configuration disclosed in any of the above-described embodiments can be applied in combination with the configuration disclosed in other embodiments, as long as no contradiction arises. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present disclosure are not limited thereto and can be modified as appropriate within the scope of the present disclosure. [Explanation of symbols]

[0102] 1: Solar cell 2: Transparent base 3: First barrier layer 4: Intervening layer 5: Second barrier layer 7: Glass base 8: Scribing tool 9: Scribe line 10:First electrode 20: Hole transport layer 30: Photoelectric conversion layer 40: Electron transport layer 50:Second electrode 100: Solar cell

Claims

1. A solar cell comprising a solar cell having a first electrode, a photoelectric conversion layer, and a second electrode in this order, and a substrate that supports the solar cell from the first electrode side and forms a light-receiving surface, A solar cell comprising a barrier layer and an intervening layer between the solar cell and the substrate.

2. 2. The solar cell according to claim 1, wherein the intermediate layer is a stress relaxation layer that relieves residual stress in the barrier layer.

3. 3. The solar cell according to claim 1, wherein the intermediate layer is interposed between the solar cell and the barrier layer.

4. 3. The solar cell according to claim 1, wherein the intermediate layer is interposed between the substrate and the barrier layer.

5. 3. The solar cell according to claim 1, wherein the photoelectric conversion layer contains a perovskite compound.

6. the barrier layer comprises silicon nitride or silicon oxynitride; 3. The solar cell according to claim 1, wherein the intermediate layer contains silicon oxide.

7. a hole transport layer between the first electrode and the photoelectric conversion layer; 3. The solar cell according to claim 1, further comprising an electron transport layer between the photoelectric conversion layer and the second electrode.

8. an electron transport layer between the first electrode and the photoelectric conversion layer; 3. The solar cell according to claim 1, further comprising a hole transport layer between the photoelectric conversion layer and the second electrode.

9. 9. The solar cell according to claim 8, wherein the photoelectric conversion layer has a porous layer adjacent to the hole transport layer or the electron transport layer.

10. 3. The solar cell according to claim 1, wherein the substrate is made of a resin substrate having a thickness in the range of 5 to 35 μm.

11. 3. The solar cell according to claim 1, wherein the substrate is made of a resin substrate having a thickness in the range of 5 to 20 μm.

12. 3. The solar cell according to claim 1, wherein the substrate is made of a resin substrate having a thickness in the range of 10 to 15 μm.

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