Tandem solar cell and manufacturing method therefor

Abstract

The present application relates to a tandem solar cell and a manufacturing method therefor. The tandem solar cell comprises: a first sub-cell (1) and a second sub-cell (2) which are arranged in a stacked mode, and a composite layer (3) disposed between the first sub-cell (1) and the second sub-cell (2), wherein the sheet resistance of the composite layer (3) is greater than or equal to 200 Ω / sq.

Description

Tandem solar cell and preparation method thereof

[0001] Related applications

[0002] This application claims priority to Chinese patent application number 202310948713.X, filed on July 31, 2023, entitled “Stacked Solar Cells and Methods for Making Them,” the entire text of which is hereby incorporated by reference. Technical Field

[0003] The present application relates to the technical field of solar cells, and in particular to a stacked solar cell and a preparation method thereof. Background Art

[0004] Perovskite materials are suitable as light-absorbing layers for solar cells due to their excellent photoelectric properties and low cost. At the same time, the band gap of perovskite materials is adjustable, and they can be stacked with other photovoltaic materials with different band gaps to form stacked solar cells, achieving extremely high photoelectric conversion efficiency.

[0005] When perovskite materials are stacked with other photovoltaic materials, in addition to optimizing the light absorption and electrical conductivity of the top and bottom cells, the interface characteristics of their connection are also very important. Usually, this interface layer is also called a recombination layer. The electrons and holes of the top and bottom cells recombine in the recombination layer to ensure the consistency of the current of the top and bottom cells. The recombination layer needs to have strong longitudinal conductivity to ensure charge transfer; secondly, the lateral conductivity of the recombination layer cannot be too strong to reduce the leakage behavior of the interface; at the same time, the light parasitic absorption of the recombination layer cannot be too strong to ensure the light absorption of the bottom cell and obtain a higher current. Therefore, how to reasonably select the recombination layer material and design and realize the photovoltaic performance of the recombination layer is very critical to the performance improvement of the stacked solar cells.

[0006] Summary of the Invention

[0007] According to various embodiments of the present application, a stacked solar cell and a method for manufacturing the same are provided.

[0008] In a first aspect, a stacked solar cell is provided, comprising: a first sub-cell and a second sub-cell arranged in a stacked manner, and a composite layer arranged between the first sub-cell and the second sub-cell;

[0009] The sheet resistance of the composite layer is greater than or equal to 200Ω / sq.

[0010] Optionally, the material of the composite layer includes one or more of ITO, IZO, IWO, FTO, ICO, AZO, BZO, nanocrystalline silicon, TiO2 and SnO2.

[0011] Optionally, the first sub-cell includes: a first absorption layer; the second sub-cell includes: a second absorption layer;

[0012] The materials of the first absorption layer include: perovskite;

[0013] The material of the second absorption layer includes one or more of crystalline silicon, perovskite, CdTe, CIGS and GaAs.

[0014] Optionally, the first absorption layer has a thickness of about 10 nm to about 100 μm;

[0015] Optionally, the band gap of the first absorption layer is about 0.9 to about 3.0 eV;

[0016] Optionally, the material of the first absorption layer includes a material with the general formula ABX3, wherein A includes: one or more monovalent cations, and the monovalent cations include: cesium ions, rubidium ions, methylamine groups and guanidine groups; B includes: one or more divalent cations, and the second cations include: lead ions, copper ions, zinc ions, gallium ions, tin ions and calcium ions; X includes: one or more monovalent anions, and the monovalent anions include: iodide ions, bromide ions, chloride ions, fluoride ions and thiocyanate ions.

[0017] Optionally, the first sub-cell further includes: at least one of a first hole transport layer and a first electron transport layer.

[0018] Optionally, the material of the first hole transport layer includes: p-type single crystal silicon, p-type polycrystalline silicon, p-type amorphous silicon, 2-(9H-carbazole-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid, benzoic acid, 4-[bis(2,4-dimethoxybiphenyl-4-yl)amino]-biphenyl-4-carboxylic acid, Spiro-OMeTAD, PTAA, P3HT, PEDOT:PSS, Spiro-TTB, F4-TCNQ, F6TCNNQ, TAPC, NiOx, CuSCN, CuAlO2, V2O5, CdS and CdSe. One or more.

[0019] Optionally, the first hole transport layer has a thickness of about 0 nm to about 100 μm.

[0020] Optionally, the material of the first electron transport layer includes: n-type single crystal silicon, n-type polycrystalline silicon, n-type amorphous silicon, TiO2, SnO2, ZnO, ZrO2, GZO, IZO, FTO, ITO, BaSnO3, TiSnO x 、SnZnO x , fullerene and its derivatives or one or more.

[0021] Optionally, the first electron transport layer has a thickness of about 0 nm to about 100 μm.

[0022] Optionally, the second sub-battery further includes: at least one of a second hole transport layer and a second electron transport layer.

[0023] Optionally, the materials of the second hole transport layer independently include: p-type single crystal silicon, p-type polycrystalline silicon, p-type amorphous silicon, 2-(9H-carbazole-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid, benzoic acid, 4-[bis(2,4-dimethoxybiphenyl-4-yl)amino]-biphenyl-4-carboxylic acid, Spiro-OMeTAD, PTAA, P3HT, PEDOT:PSS, Spiro-TTB, F4-TCNQ, F6TCNNQ, TAPC, NiO x , CuSCN, CuAlO2, V2O5, CdS and CdSe.

[0024] Optionally, the second hole transport layer has a thickness of about 0 nm to about 100 μm.

[0025] Optionally, the material of the second electron transport layer includes: n-type single crystal silicon, n-type polycrystalline silicon, n-type amorphous silicon, TiO2, SnO2, ZnO, ZrO2, GZO, IZO, FTO, ITO, BaSnO3, TiSnO x 、SnZnO x , fullerene and its derivatives or one or more.

[0026] Optionally, the second electron transport layer has a thickness of about 0 nm to about 100 μm.

[0027] Optionally, the tandem solar cell further comprises: a first TCO layer disposed on a side of the first sub-cell away from the second sub-cell, and a second TCO layer disposed on a side of the second sub-cell away from the first sub-cell;

[0028] Optionally, the material of the first TCO layer includes one or more of ITO, IZO, IWO, FTO, ICO, AZO and BZO.

[0029] Optionally, the material of the second TCO layer includes one or more of ITO, IZO, IWO, FTO, ICO, AZO and BZO.

[0030] Optionally, the stacked solar cell further includes a buffer layer, and the buffer layer is arranged between the first sub-cell and the first TCO layer.

[0031] Optionally, the material of the buffer layer includes: one or a combination of SnO2 and 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline.

[0032] In a second aspect, a method for preparing a stacked solar cell is provided, comprising:

[0033] preparing a second sub-cell;

[0034] forming a composite layer on the second subcell; the composite layer has a sheet resistance greater than or equal to 200Ω / sq; and

[0035] A first subcell is prepared on the composite layer.

[0036] Optionally, the method for preparing the composite layer includes: a sputtering method.

[0037] Optionally, the method of preparing the first absorption layer of the first sub-cell includes: one or more of spin coating, sputtering, doctor blade coating, evaporation, printing, spray coating, spray pyrolysis and slit coating.

[0038] Optionally, the method of preparing the first TCO layer and the second TCO layer of the tandem solar cell includes one or more of spin coating, sputtering, blade coating, evaporation, printing, spray coating, spray pyrolysis and slit coating.

[0039] The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the disclosed drawings without any creative work.

[0041] FIG1 is a schematic cross-sectional view of a stacked solar cell according to an embodiment of the present application.

[0042] Description of Figure Numbers:

[0043] 10. Tandem solar cell; 1. First subcell; 2. Second subcell; 3. Recombination layer; 11. First absorption layer; 21. Second absorption layer; 12. First hole transport layer; 13. First electron transport layer; 22. Second hole transport layer; 23. Second electron transport layer; 14. Interface modification layer; 24. First intrinsic amorphous silicon layer; 25. Second intrinsic amorphous silicon layer; 4. First TCO layer; 5. Second TCO layer; 6. First silver nanowire; 7. Second silver nanowire; 8. Buffer layer. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0045] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0046] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0047] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0048] In this application, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0049] In this application, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0050] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0052] In this article, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0053] In this document, "at least one" means more than one, such as one, two and more than two. "Multiple" or "several" means at least two, such as two, three, etc.

[0054] Herein, when referring to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​within the numerical interval is considered continuous and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when a numerical interval refers only to integers within the numerical interval, including the two endpoint integers of the numerical range, and each integer between the two endpoints, is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows for broad inclusion of numerical interval types such as percentage intervals, ratio intervals, and ratio intervals.

[0055] The fill factor (FF) used in this article refers to the ratio of the actual maximum achievable power (Pm or Vmp*Jmp) to the theoretical (not actually achievable) power (Jsc*Voc). Therefore, FF can be determined by the following formula: FF = (Vmp*Jmp) / (Jsc*Voc)

[0056] Where Jmp and Vmp represent the current density and voltage at the maximum power point (Pm), respectively. This point is achieved by varying the resistance in the circuit until J*V reaches its maximum value. Jsc and Voc represent the short-circuit current and open-circuit voltage, respectively. Fill factor is a key parameter for evaluating solar cells. Commercial solar cells typically have a fill factor of approximately 60% or higher.

[0057] As used herein, open circuit voltage (Voc) is the potential difference between the anode and cathode of a device with no external load connected.

[0058] The power conversion efficiency (PCE) of a solar cell used in this article refers to the percentage of power converted from absorbed light to electrical energy. The power conversion efficiency (PCE) of a solar cell can be measured by the incident light irradiance (E: W / m 2 ) and the surface area of ​​the solar cell (Ac:m 2 ) divided by the maximum power point (Pm). STC usually refers to the temperature of 25℃ and the irradiance of 1000W / m 2 , the spectrum of air mass 1.5 (AM1.5).

[0059] At present, in related technologies, the material of the composite layer is usually TCO (Transparent Conductive Oxide) material, such as ITO (Indium Tin Oxide), etc., and the literature related to the material selection of the composite layer only reports the thickness of the composite layer and the available materials, and does not elaborate on its electrical properties. Therefore, when the morphology and other characteristics of the bottom battery surface change, the material selection of the composite layer is not universal.

[0060] FIG1 is a schematic structural diagram of a stacked solar cell provided in an embodiment of the present application.

[0061] In a first aspect, an embodiment of the present application provides a stacked solar cell 10. Referring to FIG1 , the stacked solar cell 10 includes: a first sub-cell 1 and a second sub-cell 2 stacked together, and a composite layer 3 disposed between the first sub-cell 1 and the second sub-cell 2; wherein the square resistance of the composite layer 3 is greater than or equal to 200Ω / sq.

[0062] Among them, the above-mentioned first sub-cell 1 and second sub-cell 2 can be the top cell and the bottom cell, respectively. For example, when the first sub-cell 1 is the top cell, the second sub-cell 2 is the bottom cell; when the first sub-cell is the bottom cell, the second sub-cell is the top cell. Here, there is no specific limitation on whether the first sub-cell 1 and the second sub-cell 2 are the top cell or the bottom cell, respectively.

[0063] As shown in FIG1 , only an example is shown in which the first sub-cell 1 is a top cell and the second sub-cell 2 is a bottom cell. Those skilled in the art will appreciate that the first sub-cell 1 may also be a bottom cell, in which case the second sub-cell 2 is a top cell.

[0064] Among them, the stacked solar cell 10 can also be called a monolithically integrated 2-T series stacked cell; compared with the 4-T stacked cell, the 2-T series stacked cell omits the back electrode of the top cell and the upper electrode of the bottom cell, which means that the structure can reduce the material loss of the device, save costs, and reduce the photocurrent loss caused by electrode parasitic absorption.

[0065] The recombination layer 3 acts as a bridge between the top cell and the bottom cell, enabling electrons and holes to recombine effectively while minimizing voltage loss and light loss.

[0066] Sheet resistance, also known as sheet resistance, is defined as the resistance of a square semiconductor layer in the direction of current flow, measured in ohms per square. Simply put, sheet resistance refers to the resistance value per unit thickness per unit area of ​​a conductive material, referred to as sheet resistance. Ideally, it is equal to the resistivity of the material divided by the thickness.

[0067] Sheet resistance has a characteristic: the edge-to-edge resistance of a square of any size is the same, whether the side length is 1m or 0.1m. The formula for calculating sheet resistance is: R = ρL / S, where ρ is the resistivity of the material in ohm-meters (Ω.m), L is the length in meters (m), and S is the cross-sectional area in square meters (m²). When the length and width are equal, R = ρ / h, where h is the thickness of the film.

[0068] For a conductive film, when its resistivity and cross-sectional area are constant, the greater the thickness, the smaller the sheet resistance, and the smaller the thickness, the greater the sheet resistance.

[0069] In the related art, the material of the composite layer 3 is usually TCO (Transparent Conductive Oxide). For example, in the related art, some research units have disclosed the use of an ITO layer as the composite layer of a perovskite / crystalline silicon stacked solar cell. There are also related literature reports on the use of a silicon nanocrystal layer as the composite layer. However, in these related arts, only the thickness of the composite layer 3 is reported, and its electrical properties are not elaborated in detail. As a result, when the surface morphology and other characteristics of the bottom cell (such as a crystalline silicon cell) change, it is impossible to directly select the material for the composite layer 3. In other words, the material selection for the composite layer 3 is not universal, which limits the material selection and application of the composite layer 3.

[0070] In the tandem solar cell provided in the embodiments of the present application, the inventors discovered in their research that by setting requirements for the electrical properties of the composite layer 3, such as limiting the square resistance of the composite layer 3 to a range greater than or equal to 200Ω / sq, the interfacial transmission performance of the first sub-cell 1 and the second sub-cell 2 (i.e., the top cell and the bottom cell) can be optimized, thereby improving the efficiency of the tandem solar cell 10. Furthermore, the material selection for the composite layer 3 that meets this requirement can be universally applied. In other words, any material and process selection for the composite layer 3 that meets the aforementioned square resistance value can effectively improve the efficiency of the tandem solar cell 10.

[0071] Based on the above, those skilled in the art can set composite layers 3 of different thicknesses and different morphological structures according to the value of the sheet resistance and different material selections, which is conducive to the selection and application of the materials of the composite layer 3.

[0072] In some embodiments, the material of the composite layer 3 includes one or more of: ITO (Indium Tin Oxide), IZO (Indium-Zinc-Oxide), IWO (Tungsten-doped Indium Oxide), FTO (F-doped Tin Oxide), ICO (Cerium-doped Indium Oxide), AZO (Al-doped Zinc Oxide), BZO (Boron-doped Zinc Oxide), nanocrystalline silicon, TiO2 and SnO2.

[0073] Among them, the composite layer 3 can be a single-layer structure, and the material of the single-layer structure can include a combination of one or more of the above materials, or the composite layer 3 can be a stacked structure of two layers of material layers composed of different layers of the above materials, such as a stacked structure of an ITO layer and a SnO2 layer.

[0074] In these embodiments, by selecting the above materials, the composite layer 3 has low electrical and optical performance losses, thereby effectively improving the efficiency of the tandem solar cell 10. Furthermore, when the composite layer 3 includes a TCO layer, the top cell can be deposited directly on the sputtered TCO layer. The TCO layer can protect the bottom cell and has excellent electrical and optical properties.

[0075] For example, the material of the composite layer 3 may include: ITO.

[0076] In some embodiments, the first sub-cell 1 includes: a first absorption layer 11, and the second sub-cell 2 includes: a second absorption layer 21; the material of the first absorption layer 11 includes perovskite; the material of the second absorption layer 21 includes: one or more of crystalline silicon, perovskite, CdTe (cadmium telluride), CIGS (copper indium gallium selenide) and GaAs (gallium arsenide).

[0077] For perovskite materials, the band gap of organic-inorganic hybrid metal halide perovskite materials can be adjusted between 1.2eV and 2.2eV by adjusting the ratio of organic-inorganic cations and halogen elements. Perovskite materials have high absorption coefficients and steep absorption edges. These characteristics make them more suitable for the top cell of stacked solar cells.

[0078] Based on the above, in these embodiments, a multi-junction tandem cell is prepared by using a thin-film cell such as a silicon cell, CdTe, CIGS, and GaAs cell with a narrow bandgap as a bottom cell, combined with a wide-bandgap top cell. The tandem cell can better utilize short-wavelength photons in the solar spectrum and has a higher conversion efficiency than a single-junction solar cell. By using perovskite cells for both the top and bottom cells, i.e., a full perovskite cell, the light absorption of the top and bottom cells can be balanced by adjusting the bandgap of the perovskite absorption layer contained in the top and bottom cells, thereby improving the conversion efficiency of the tandem solar cell 10.

[0079] As shown in FIG1 , an example of a stacked solar cell 10 is shown in which the first subcell 1 is a top cell, the second subcell 2 is a bottom cell, the material of the first absorption layer 11 includes perovskite, and the material of the second absorption layer 21 includes crystalline silicon.

[0080] It should be noted that, for those skilled in the art, it can be understood that when the first sub-cell 1 is a bottom cell and the second sub-cell 2 is a top cell, the material of the first absorption layer 11 may also include: perovskite. At this time, the material of the second absorption layer 21 may include: one or more of: crystalline silicon, perovskite, CdTe, CIGS and GaAs.

[0081] In the following embodiments, the first sub-cell 1 is used as a top cell and the second sub-cell 2 is used as a bottom cell.

[0082] In some embodiments, the thickness of the first absorption layer 11 is about 10 nm to about 100 μm;

[0083] In other embodiments, the band gap of the first absorption layer 11 is about 0.9 eV to about 3.0 eV;

[0084] In some other embodiments, the material of the first absorption layer 11 includes a material with the general formula ABX3, wherein A includes: one or more monovalent cations, including: cesium ions, rubidium ions, methylamine groups and guanidine groups; B includes: one or more divalent cations, including: lead ions, copper ions, zinc ions, gallium ions, tin ions and calcium ions; X includes: one or more monovalent anions, including: iodide ions, bromide ions, chloride ions, fluoride ions and thiocyanate ions.

[0085] In some embodiments, the first sub-cell 1 further includes: at least one of a first hole transport layer 12 and a first electron transport layer 13 .

[0086] In some embodiments, the material of the first hole transport layer 12 includes: p-type single crystal silicon, p-type polycrystalline silicon, p-type amorphous silicon, [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz), [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz), [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz), benzoic acid, 4-[bis(2,4-dimethoxybiphenyl-4-yl)amino]-biphenyl-4-carboxylic acid [MC-43], Spiro-OMeTAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene) , PTAA (polyethylene terephthalate), P3HT (polymer of 3-hexylthiophene), PEDOT:PSS (poly(3,4-ethylenedioxythiophene:polystyrene sulfonate), Spiro-TTB (2,2',7,7'-tetrakis[N,N-di(4-methylphenyl)amino]-9,9'-spirobifluorene), F4-TCNQ (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane), F6TCNNQ, TAPC (4,4'-cyclohexylidenebis[N,N-bis(p-tolyl)aniline], 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline]), NiO x , CuSCN, CuAlO2, V2O5, CdS, CdSe.

[0087] In some embodiments, the first hole transport layer 12 has a thickness of about 0 nm to about 100 μm.

[0088] In some embodiments, the material of the first electron transport layer 13 includes: n-type single crystal silicon, n-type polycrystalline silicon, n-type amorphous silicon, TiO2, SnO2, ZnO, ZrO2, GZO, IZO, FTO, ITO, BaSnO3, TiSnO x 、SnZnO x , fullerene and its derivatives (such as C60, C70, PCBM, etc.) or one or more.

[0089] In some embodiments, the first electron transport layer 13 has a thickness of about 0 nm to about 100 μm.

[0090] In some embodiments, the second sub-battery 2 further includes: at least one of a second hole transport layer 22 and a second electron transport layer 23 .

[0091] In some embodiments, the material of the second hole transport layer 22 includes: p-type single crystal silicon, p-type polycrystalline silicon, p-type amorphous silicon, [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz), [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz), [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz), benzoic acid, 4-[bis(2,4-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (Me-4PACz), [Methoxybiphenyl-4-yl)amino]-biphenyl-4-carboxylic acid [MC-43], Spiro-OMeTAD (2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene), PTAA (polyethylene terephthalate), P3HT (polymer of 3-hexylthiophene), PEDOT:PSS, Spiro-TTB, F4-TCNQ, F6TCNNQ, TAPC, NiO x , CuSCN, CuAlO2, V2O5, CdS, CdSe.

[0092] In some embodiments, the second hole transport layer 22 has a thickness of about 0 nm to about 100 μm.

[0093] In some embodiments, the material of the second electron transport layer 23 includes: n-type single crystal silicon, n-type polycrystalline silicon, n-type amorphous silicon, TiO2, SnO2, ZnO, ZrO2, GZO, IZO, FTO, ITO, BaSnO3, TiSnO x 、SnZnO x , fullerene and its derivatives (such as C60, C70, PCBM, etc.) or one or more.

[0094] In some embodiments, the second electron transport layer 23 has a thickness of about 0 nm to about 100 μm.

[0095] For example, as shown in FIG1 , an example of a tandem solar cell 10 is shown in which the first sub-cell 1 is a perovskite cell and the second sub-cell 2 is a silicon cell. In this example, the material of the first hole transport layer 12 included in the first sub-cell 1 includes: NiO xThe material of the first electron transport layer 13 includes C60, and the first sub-cell 1 also includes an interface modification layer 14, and the material of the interface modification layer 14 includes LiF. The material of the second hole transport layer 22 included in the second sub-cell 2 includes p-type amorphous silicon, and the material of the second electron transport layer 23 includes n-type amorphous silicon. The second sub-cell 2 also includes a first intrinsic amorphous silicon layer 24 disposed between the second hole transport layer 22 and the second absorption layer 21, and a second intrinsic amorphous silicon layer 25 disposed between the second electron transport layer 23 and the second absorption layer 21. Therefore, the second sub-cell 2 has an HJT (Heterojunction with Intrinsic Thin Layer) structure.

[0096] In some embodiments, as shown in FIG1 , the tandem solar cell 10 further includes: a first TCO layer 4 disposed on a side of the first sub-cell 1 away from the second sub-cell 2 , and a second TCO layer 5 disposed on a side of the second sub-cell 2 away from the first sub-cell 1 .

[0097] In some embodiments, the material of the first TCO layer 4 includes one or more of ITO, IZO, IWO, FTO, ICO, AZO, and BZO.

[0098] In other embodiments, the material of the second TCO layer 5 includes one or more of ITO, IZO, IWO, FTO, ICO, AZO and BZO.

[0099] In some embodiments, as shown in FIG1 , the stacked solar cell 10 further includes: a first silver nanogate wire 6 disposed on a side of the first TCO layer 4 away from the first sub-cell 1 ; and a second silver nanogate wire 7 disposed on a side of the second TCO layer 5 away from the second sub-cell 2 .

[0100] In some embodiments, as shown in FIG1 , the stacked solar cell 10 further includes a buffer layer 8 disposed between the first sub-cell 1 and the first TCO layer 4 ; the material of the buffer layer 8 includes one or a combination of SnO 2 and 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline.

[0101] In these embodiments, the first sub-cell 1 may be a top cell. In this case, by preparing a buffer layer 8 on the first sub-cell 1 , the first electron transport layer 12 and / or the first absorption layer 11 included in the first sub-cell 1 can be protected when the first TCO layer 4 is sputtered.

[0102] For example, as shown in FIG1 , an example is shown in which the buffer layer 8 is disposed on the first electron transport layer 12 . In this way, when the first TCO layer 4 is sputtered, the buffer layer 8 can protect the first electron transport layer 12 .

[0103] The material of the first TCO layer 4 may be ITO.

[0104] In a second aspect, an embodiment of the present application further provides a method for preparing a stacked solar cell, as shown in FIG1 , the method comprising:

[0105] S1), preparing the second sub-battery 2;

[0106] Taking the second sub-cell 2 as a silicon cell as an example, preparing the second sub-cell 2 may include:

[0107] S11), preparing an N-type silicon base layer;

[0108] The preparation of the N-type silicon base layer may include: providing an N-type silicon wafer, which may be purchased commercially or prepared by doping, and polishing the N-type silicon wafer to form a velvet surface, wherein the velvet surface may have a velvet thickness of 300 nm;

[0109] S12), preparing an intrinsic amorphous silicon layer and a doped amorphous silicon layer;

[0110] Specifically, PECVD (Plasma Enhanced Chemical Vapor Deposition) can be used to form a second intrinsic amorphous silicon layer and an n-type amorphous silicon layer (i.e., the second electron transport layer) on the front surface of the N-type silicon wafer. The total thickness of the second intrinsic amorphous silicon layer and the n-type amorphous silicon layer can be 25 nm; and

[0111] Using PECVD, a first intrinsic amorphous silicon layer and a p-type amorphous silicon layer (i.e., the second hole transport layer) are formed on the back side of the N-type silicon wafer. The total thickness of the first intrinsic amorphous silicon layer and the p-type amorphous silicon layer can be 20 nm. Thus, a first sub-cell 1 is obtained.

[0112] S2), preparing a composite layer 3 on the second sub-cell 1, wherein the sheet resistance of the composite layer 3 is greater than 200Ω / sq;

[0113] The method for preparing the composite layer 3 may include: sputtering.

[0114] The material of the composite layer 3 may include, for example: ITO;

[0115] At this time, the preparation of the composite layer 3 may include:

[0116] An ITO layer is prepared on n-type amorphous silicon by sputtering, and the thickness of the ITO layer can be 50 nm; thus, a composite layer 3 is obtained;

[0117] In this process, by adjusting the process parameters during sputtering, a composite layer 3 with certain morphological characteristics and a thickness of 50 nm can be obtained, so that the sheet resistance of the composite layer 3 is greater than or equal to 200Ω / sq.

[0118] S3), preparing a first sub-cell 1 on the composite layer 3;

[0119] For example, taking the first sub-cell 1 as a perovskite cell, preparing the first sub-cell 1 on the composite layer 3 may include:

[0120] S31) A first hole transport layer may be prepared on the composite layer 3. The material of the first hole transport layer may include NiO. In this case, the first hole transport layer may be prepared on the composite layer 3, which may include:

[0121] A NiO layer is prepared on the composite layer 3 by magnetron sputtering, and the thickness of the NiO layer can be 30 nm;

[0122] S32), preparing a first absorption layer on the first hole transport layer, wherein the material of the first absorption layer may include: perovskite, and in this case, the method of preparing the first absorption layer may include: one or more of: spin coating, sputtering, doctor blade coating, evaporation, printing, spray coating, spray pyrolysis and slit coating;

[0123] Here, the materials of the first absorption layer include: Cs 0.25 FA 0.75 Pb(I 0.8 Br 0.2 )3 as an example, at this time, preparing the first absorption layer on the first hole transport layer may include:

[0124] The perovskite (Cs 0.25 FA 0.75 Pb(I 0.8 Br 0.2 )3) Light-absorbing layer, perovskite (Cs 0.25 FA 0.75 Pb(I 0.8 Br 0.2 3) The band gap of the light absorbing layer is about 1.68 eV and the thickness can be 500 nm;

[0125] S33), preparing an interface modification layer (or hole blocking layer) and a first electron transport layer on the first absorption layer, wherein the material of the interface modification layer may include: LiF, and the material of the first electron transport layer may include: C60. At this time, preparing the first electron transport layer on the first absorption layer may include:

[0126] The thermal evaporation method was used to deposit the perovskite (Cs 0.25 FA 0.75 Pb(I0.8 Br 0.2 3) preparing a C60 layer on the light absorbing layer, wherein the total thickness of the LiF layer and the C60 layer may be 10 nm;

[0127] In this way, the first sub-battery 1 is obtained;

[0128] S4), preparing a buffer layer 8 on the first sub-cell 1. The material of the buffer layer 8 may include: SnO2. At this time, preparing the buffer layer 8 on the first sub-cell 1 may include:

[0129] A SnO2 layer is prepared on the C60 layer by atomic layer deposition, and the thickness of the SnO2 layer can be 150nm;

[0130] S5), preparing a first TCO layer and a second TCO layer of a tandem solar cell;

[0131] For example, the materials of the first TCO layer and the second TCO layer may independently include: one or more of ITO, IZO, IWO, FTO, ICO, AZO and BZO.

[0132] Thus, the method of preparing the first TCO layer and the second TCO layer may include one or more of spin coating, sputtering, doctor blade coating, evaporation, printing, spray coating, spray pyrolysis and slot coating.

[0133] In some embodiments, the second TCO layer is disposed on a side of the second sub-cell away from the first sub-cell. In this case, the second TCO layer can be prepared on a side of the second sub-cell away from the first sub-cell before step S3).

[0134] The material of the second TCO layer may be ITO. In this case, preparing the second TCO layer on a side of the second sub-cell away from the first sub-cell may include:

[0135] An ITO layer is prepared on the p-type amorphous silicon layer by sputtering, and the thickness of the ITO layer can be 130 nm; thus, a second TCO layer is obtained;

[0136] In some other embodiments, the first TCO layer is disposed on a side of the first sub-cell away from the second sub-cell. In this case, preparing the first TCO layer may include:

[0137] A first TCO layer is formed on the buffer layer 8 .

[0138] For example, taking the material of the first TCO layer as ITO as an example, preparing the first TCO layer on the buffer layer 8 may include:

[0139] An ITO layer is prepared on the SnO2 layer by sputtering, and the thickness of the ITO layer can be 100 nm.

[0140] S6), forming a metal grid line layer on a side of the first TCO layer away from the first sub-cell 1 and a side of the second TCO layer away from the second sub-cell 2 respectively; this may include:

[0141] Prepare Ag metal gate line layers on the first TCO layer and the second TCO layer respectively by using a thermal evaporation method, wherein the thickness of the Ag metal gate line layers can be 100 nm;

[0142] In this way, the preparation of the stacked solar cell is completed.

[0143] In order to objectively evaluate the technical effects of the embodiments of the present application, the present application will be described in detail and exemplarily through the following examples and comparative examples.

[0144] In the following examples and comparative examples, all raw materials can be purchased commercially, and in order to maintain the reliability of the experiments, the raw materials used in the following examples and comparative examples have the same physical and chemical parameters or are prepared by the same processing method.

[0145] Example 1

[0146] The preparation method of the stacked solar cell in Example 1 is as follows:

[0147] (1) polishing an N-type silicon wafer and producing a velvet surface with a velvet thickness of 300 nm;

[0148] (2) preparing a front intrinsic amorphous silicon layer and an n-type amorphous silicon layer by PECVD, wherein the total thickness of the front intrinsic amorphous silicon layer and the n-type amorphous silicon layer is 25 nm;

[0149] (3) preparing a back intrinsic amorphous silicon layer and a p-type amorphous silicon layer by PECVD, wherein the total thickness of the back intrinsic amorphous silicon layer and the p-type amorphous silicon layer is 20 nm;

[0150] (4) a composite layer is prepared on the n-type amorphous silicon layer by sputtering. The composite layer is made of ITO, has a thickness of 20 nm, and a sheet resistance of 200 Ω / sq.

[0151] (5) a TCO layer is prepared on the p-type amorphous silicon layer by sputtering. The material of the TCO layer is ITO and the thickness is 130 nm.

[0152] (6) preparing a NiO layer on the composite layer by magnetron sputtering, wherein the thickness of the NiO layer is 30 nm;

[0153] (7) A one-step spin coating method is used to deposit the perovskite light absorbing layer Cs on the NiO layer. 0.25 FA 0.75 Pb(I 0.8 Br 0.2)3, the band gap of the perovskite light absorbing layer is about 1.68eV and the thickness is 500nm;

[0154] (8) LiF layer and C60 layer were prepared on the perovskite light absorbing layer by thermal evaporation method, and the total thickness of LiF layer and C60 layer was 10 nm;

[0155] (9) A SnO2 layer was prepared on the C60 layer by atomic layer deposition. The thickness of the SnO2 layer was 15 nm.

[0156] (10) A TCO layer is prepared on the SnO2 layer by sputtering. The material of the TCO layer is ITO and the thickness is 100 nm.

[0157] (11) A Ag metal grid line layer is prepared on the front and back sides using a thermal evaporation method. The thickness of the Ag metal grid line layer is 100 nm, and the battery preparation is completed.

[0158] Example 2

[0159] The method for preparing the tandem solar cell in Example 2 is substantially the same as the method for preparing the tandem solar cell in Example 1, except that:

[0160] The composite layer is made of ITO, has a thickness of 20 nm, and a sheet resistance of 700 Ω / sq.

[0161] Example 3

[0162] The method for preparing the tandem solar cell in Example 3 is substantially the same as the method for preparing the tandem solar cell in Example 1, except that:

[0163] The composite layer is made of ITO, has a thickness of 15 nm, and a sheet resistance of 1500 Ω / sq.

[0164] Comparative Example 1

[0165] The preparation method of the stacked solar cell in Comparative Example 1 is substantially the same as that in Example 1, except that:

[0166] The material of the composite layer is ITO, with a thickness of 15 nm and a sheet resistance of 70 Ω / sq.

[0167] Comparative Example 2

[0168] The preparation method of the stacked solar cell in Comparative Example 2 is substantially the same as that in Example 1, except that:

[0169] The material of the composite layer is ITO, with a thickness of 18 nm and a sheet resistance of 150 Ω / sq.

[0170] Test Case

[0171] The performance of the stacked solar cells prepared in Examples 1 to 3 and Comparative Examples 1 to 2 was tested, and the open circuit voltage, current density, photoelectric conversion efficiency and fill factor of the stacked solar cells were obtained as shown in Table 1 below.

[0172] Table 1

[0173] As can be seen from Table 1, the solar cell corresponding to the composite layer provided in the embodiment of the present application has a higher open circuit voltage, short circuit current, fill factor and photoelectric conversion efficiency, which can significantly increase the efficiency of the stacked solar cell.

[0174] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0175] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A stacked solar cell, characterized in that: include: A first sub-cell and a second sub-cell arranged in a stacked manner, and a composite layer arranged between the first sub-cell and the second sub-cell; Wherein, the sheet resistance of the composite layer is greater than or equal to 200Ω / sq.

2. The tandem solar cell according to claim 1, characterized in that: The material of the composite layer includes one or more of ITO, IZO, IWO, FTO, ICO, AZO, BZO, nanocrystalline silicon, TiO2 and SnO2.

3. The tandem solar cell according to claim 1 or 2, characterized in that: The first subcell comprises: a first absorption layer; the second subcell comprises: a second absorption layer; The material of the first absorption layer includes: perovskite; The material of the second absorption layer includes: one or more of crystalline silicon, perovskite, CdTe, CIGS and GaAs.

4. The stacked solar cell according to claim 3, characterized in that: The first absorption layer has a thickness of about 10 nm to about 100 μm.

5. The stacked solar cell according to claim 3 or 4, characterized in that: The first absorption layer has a band gap of about 0.9 eV to about 3.0 eV.

6. The tandem solar cell according to any one of claims 3 to 5, characterized in that: The material of the first absorption layer includes a material with a general formula of ABX3, wherein A includes: one or more monovalent cations, and the monovalent cations include: cesium ion, rubidium ion, methylamine and methylammonium; B includes: one or more divalent cations, and the divalent cations include: lead ion, copper ion, zinc ion, gallium ion, tin ion and calcium ion; X includes: one or more monovalent anions, and the monovalent anions include iodide ion, bromide ion, chloride ion, fluoride ion and thiocyanate ion.

7. The tandem solar cell according to any one of claims 1 to 6, characterized in that: The first sub-cell further includes: at least one of a first hole transport layer and a first electron transport layer.

8. The tandem solar cell according to claim 7, characterized in that: The material of the first hole transport layer includes: p-type single crystal silicon, p-type polycrystalline silicon, p-type amorphous silicon, 2-(9H-carbazole-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid, benzoic acid, 4-[bis(2,4-dimethoxybiphenyl-4-yl)amino]-biphenyl-4-carboxylic acid, Spiro-OMeTAD, PTAA, P3HT, PEDOT:PSS, Spiro-TTB, F4-TCNQ, F6TCNNQ, TAPC, NiO x , CuSCN, CuAlO2, V2O5, CdS and CdSe.

9. The tandem solar cell according to claim 7 or 8, characterized in that: The first hole transport layer has a thickness of about 0 nm to about 100 μm.

10. The tandem solar cell according to any one of claims 7 to 9, characterized in that: The material of the first electron transport layer includes: n-type single crystal silicon, n-type polycrystalline silicon, n-type amorphous silicon, TiO2, SnO2, ZnO, ZrO2, GZO, IZO, FTO, ITO, BaSnO3, TiSnO x SnZnO x , fullerenes and their derivatives or more.

11. The tandem solar cell according to any one of claims 7 to 10, characterized in that: The first electron transport layer has a thickness of about 0 nm to about 100 μm.

12. The tandem solar cell according to any one of claims 1 to 11, characterized in that: The second sub-cell further includes: at least one of a second hole transport layer and a second electron transport layer.

13. The tandem solar cell according to claim 12, characterized in that: The material of the second hole transport layer includes: p-type single crystal silicon, p-type polycrystalline silicon, p-type amorphous silicon, 2-(9H-carbazole-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid, benzoic acid, 4-[bis(2,4-dimethoxybiphenyl-4-yl)amino]-biphenyl-4-carboxylic acid, Spiro-OMeTAD, PTAA, P3HT, PEDOT:PSS, Spiro-TTB, F4-TCNQ, F6TCNNQ, TAPC, NiO x , CuSCN, CuAlO2, V2O5, CdS and CdSe.

14. The tandem solar cell according to claim 12 or 13, characterized in that: The second hole transport layer has a thickness of about 0 nm to about 100 μm.

15. The tandem solar cell according to any one of claims 12 to 14, characterized in that: The material of the second electron transport layer includes: n-type single crystal silicon, n-type polycrystalline silicon, n-type amorphous silicon, TiO2, SnO2, ZnO, ZrO2, GZO, IZO, FTO, ITO, BaSnO3, TiSnO x SnZnO x , fullerenes and their derivatives or more.

16. The tandem solar cell according to any one of claims 12 to 15, characterized in that: The second electron transport layer has a thickness of about 0 nm to about 100 μm.

17. The tandem solar cell according to any one of claims 1 to 16, characterized in that: The stacked solar cell further includes: a first TCO layer disposed on a side of the first sub-cell away from the second sub-cell, and a second TCO layer disposed on a side of the second sub-cell away from the first sub-cell.

18. The tandem solar cell according to claim 17, characterized in that: The material of the first TCO layer includes one or more of ITO, IZO, IWO, FTO, ICO, AZO and BZO.

19. The tandem solar cell according to claim 17 or 18, characterized in that: The material of the second TCO layer includes one of ITO, IZO, IWO, FTO, ICO, AZO and BZO or more.

20. The tandem solar cell according to any one of claims 17 to 19, characterized in that: The stacked solar cell further includes a buffer layer, and the buffer layer is disposed between the first sub-cell and the first TCO layer.

21. The tandem solar cell according to claim 20, characterized in that: The material of the buffer layer includes: one or a combination of SnO2 and 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline.

22. A method for preparing a stacked solar cell, characterized in that: include: preparing a second sub-battery; Preparing a composite layer on the second sub-cell; the sheet resistance of the composite layer is greater than or equal to 200Ω / sq; as well as A first sub-cell is prepared on the composite layer.

23. The method according to claim 22, characterized in that The method for preparing the composite layer includes: a sputtering method.

24. The method according to claim 22 or 23, characterized in that The method for preparing the first absorption layer of the first sub-cell includes: one or more of spin coating, sputtering, blade coating, evaporation, printing, spray coating, spray pyrolysis and slit coating.

25. The method according to any one of claims 22 to 24, characterized in that: The method for preparing the first TCO layer and the second TCO layer of the stacked solar cell comprises: one or more of spin coating, sputtering, blade coating, evaporation, printing, spray coating, spray pyrolysis and slit coating.

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