Solar cell, method of manufacturing the same, and photovoltaic module

Abstract

This application belongs to the field of solar cell technology and discloses solar cells, their fabrication methods, and photovoltaic modules. The solar cell includes a perovskite absorber layer, a first charge transport layer, and a top electrode stacked sequentially. The top electrode includes an interface layer, a main conductive layer, and a protective layer stacked sequentially. The main conductive layer is located on the side of the interface layer away from the first charge transport layer. The interface layer includes a first metal oxynitride with a work function of 4.0 eV–5.5 eV. The main conductive layer includes a second metal oxynitride. The protective layer includes one or more of aluminum-doped zinc oxide and indium oxynitride. The interface layer forms a good ohmic contact with the underlying first charge transport layer. The main conductive layer has high transmittance and low resistivity over a wide spectral range and can serve as the main conductive channel for the top electrode. The protective layer acts as an anti-reflection layer, reducing interface light loss and protecting the main conductive layer from subsequent processes or environmental factors.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, specifically to solar cells, methods for their fabrication, and photovoltaic modules. Background Technology

[0002] Photovoltaic technology has become central to the energy transition, but single-junction solar cells face efficiency bottlenecks. While monocrystalline silicon cells dominate the market, their efficiency is approaching the theoretical limit of 29.4%, exhibiting diminishing marginal returns. Against this backdrop, crystalline silicon / perovskite tandem cells have emerged, effectively breaking the Shockley-Queisser limit of single-junction cells. In recent years, LONGi Green Energy has achieved efficiencies of up to 35% for small-area tandem cells and over 31% for large-area cells, nearly 20% higher than single-junction silicon cells. However, tandem cells still face numerous challenges, including in materials, structure, and manufacturing processes. Regarding cell structure, silver is currently the primary electrode grid line for tandem cells. Although silver has good conductivity, it requires low-temperature processing (below 150°C) in tandem perovskite cells. This makes it difficult to melt and alloy silver powder, resulting in decreased conductivity of the prepared electrode grid lines. Furthermore, the organic binder in the silver paste is difficult to completely volatilize, making it difficult to maintain the stability of the tandem cell electrodes in the later stages. Furthermore, the silver electrode has a certain light-blocking effect on the top cell, reducing light utilization. Therefore, developing transparent electrodes with high transmittance, high conductivity, high stability, and energy level matching and process compatibility with the underlying perovskite devices has significant application value. Summary of the Invention

[0003] This application is based on the inventor's discoveries and understanding of the following facts and problems: Traditional single materials, such as ITO (which is brittle and has scarce indium resources) or ultrathin metals (which suffer from parasitic absorption, easy diffusion, and poor stability), are insufficient to fully meet the requirements. There is an urgent need to develop a new type of electrode to meet these needs.

[0004] Metal oxynitrides (such as titanium oxynitride (TiNO) and indium oxynitride (InON)) are a new class of functional materials. By controlling the ratio of nitrogen to oxygen, their work function, carrier concentration, and optical band gap can be precisely tuned over a wide range. For example, TiNO is known for its high metal-like conductivity and high transmittance in the near-infrared region. However, a mature solution remains elusive for how to systematically integrate it as a core component into the composite electrode structure of tandem perovskite solar cells, and for addressing issues related to interfaces, crystallization, and mass transport.

[0005] This application aims to at least partially alleviate or solve at least one of the aforementioned problems. To this end, one objective of this application is to provide a solar cell employing a multilayer composite top electrode structure. This top electrode exhibits good conductivity and light transmittance, a low interfacial barrier with the underlying charge transport layer, and can also resist water and oxygen erosion, extending the cell's lifespan. Furthermore, each layer of the top electrode can be fabricated at a relatively low temperature, without significantly adversely affecting the underlying heat-sensitive perovskite absorber layer and other layers.

[0006] In one aspect of this application, a solar cell is provided, comprising a perovskite absorber layer, a first charge transport layer, and a top electrode stacked sequentially. The top electrode comprises an interface layer, a main conductive layer, and a protective layer stacked sequentially. The main conductive layer is located on the side of the interface layer away from the first charge transport layer. The interface layer comprises a first metal oxynitride with a work function of 4.0 eV-5.5 eV. The main conductive layer comprises a second metal oxynitride, which comprises one or more of indium oxynitride, zinc oxynitride, tin oxynitride, doped indium oxynitride, doped zinc oxynitride, and doped tin oxynitride, wherein the doping element in the doped indium oxynitride, doped zinc oxynitride, and doped tin oxynitride comprises one or more of tantalum, zirconium, and chromium. The protective layer comprises one or more of aluminum-doped zinc oxide and indium oxynitride. Therefore, with the work function of the first metal nitride within the aforementioned range, the interface layer can achieve optimal energy level alignment with the first charge transport layer, reducing the interface barrier and forming a good ohmic contact with the underlying first charge transport layer; the main conductive layer has high transmittance and low resistivity over a wide spectral range, and can serve as the main conductive channel for the top electrode; the protective layer can act as an anti-reflection layer, reducing interface light loss, and at the same time protecting the main conductive layer from the influence of subsequent processes or environmental factors.

[0007] In some embodiments, the first metal oxynitride includes one or more of titanium oxynitride, niobium oxynitride, tantalum oxynitride, doped titanium oxynitride, doped niobium oxynitride, and doped tantalum oxynitride; the doping element in the doped titanium oxynitride includes one or more of niobium, tantalum, zirconium, and chromium; the doping element in the doped niobium oxynitride includes one or more of tantalum, zirconium, and chromium; and the doping element in the doped tantalum oxynitride includes one or more of zirconium and chromium. The above materials have a suitable work function and can form a good ohmic contact with the first charge transport layer.

[0008] In some embodiments, the top electrode satisfies at least one of the following conditions: the thickness of the interface layer is 10 nm-20 nm; the interface layer has a nanocrystalline / amorphous structure; the crystals in the interface layer include anatase and rutile crystals, and the number of anatase crystals is greater than the number of rutile crystals; the thickness of the main conductive layer is 80 nm-120 nm; the average transmittance of the main conductive layer in the wavelength range of 800-1200 nm is ≥85%; the sheet resistance of the main conductive layer is <50 Ω / sq; and the thickness of the protective layer is 30 nm-50 nm.

[0009] In some embodiments, the first charge transport layer is an electron transport layer, and the work function of the first metal nitride is 4.0 eV-4.7 eV. Therefore, the interface layer can achieve optimal energy level alignment with the electron transport layer, further reducing the interface barrier and enabling a better ohmic contact between the interface layer and the electron transport layer.

[0010] In some embodiments, the solar cell is a tandem cell; and / or, the top electrode is a grid line electrode or a full-surface electrode.

[0011] In another aspect of this application, a method for fabricating the aforementioned solar cell is proposed. In some embodiments, the method for fabricating the aforementioned solar cell includes: forming a first charge transport layer on one side of a perovskite absorber layer; forming a top electrode on the side of the first charge transport layer away from the perovskite absorber layer; forming the top electrode includes the following steps: forming an interface layer on the side of the first charge transport layer away from the perovskite absorber layer; forming a main conductive layer on the side of the interface layer away from the perovskite absorber layer; and forming a protective layer on the side of the main conductive layer away from the perovskite absorber layer. Thus, the solar cell fabricated using the above method possesses all the features and advantages of the aforementioned solar cell, which will not be repeated here.

[0012] In some embodiments, the top electrode is formed by magnetron sputtering at room temperature to 150°C. This allows for the formation of a top electrode with excellent performance, and the fabrication process of the top electrode does not significantly adversely affect the underlying perovskite absorber layer or other temperature-sensitive films, thus contributing to improved overall performance of the solar cell.

[0013] In some embodiments, the method for preparing the aforementioned solar cell satisfies at least one of the following conditions: an interface layer is formed by pulsed DC reactive magnetron sputtering, the target material is a single metal or alloy target material, and the atmosphere is a mixture of argon, nitrogen, and oxygen; after sputtering to form the interface layer, in-situ annealing is performed at 100°C-150°C for 15 min-30 min, during which the oxygen supply is cut off and the argon and nitrogen atmosphere is maintained; a main conductive layer is formed by pulsed DC reactive magnetron sputtering, the target material is a single metal or alloy target material; a protective layer is formed by radio frequency sputtering; after sputtering to form the protective layer, annealing is performed in air at 100°C-150°C for 15 min-30 min.

[0014] In some embodiments, forming the top electrode includes the following steps: forming a niobium-doped titanium oxynitride interface layer using pulsed DC reactive magnetron sputtering, with a niobium-doped titanium target as the target material and a mixed gas atmosphere of argon, nitrogen, and oxygen, where the volume ratio of nitrogen to oxygen is 5-27; after forming the interface layer, cutting off the oxygen supply and annealing in situ at 100℃-150℃ for 15-30 min; after forming the interface layer, replacing the target material with an indium target and forming an indium oxynitride main conductive layer using pulsed DC reactive magnetron sputtering; after forming the main conductive layer, forming an aluminum-doped zinc oxide protective layer using radio frequency sputtering. The above process is simple and controllable, easily scalable, and highly compatible with existing semiconductor processes.

[0015] In another aspect, this application proposes a photovoltaic module comprising the aforementioned solar cell. Thus, this photovoltaic module possesses all the features and advantages of the aforementioned solar cell, which will not be repeated here. Attached Figure Description

[0016] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Fig. 1 A schematic diagram of the structure of a solar cell according to an embodiment of this application is shown; Fig. 2 A schematic diagram of a solar cell according to another embodiment of this application is shown; Fig. 3 A schematic diagram of the structure of a solar cell according to yet another embodiment of this application is shown.

[0017] Explanation of reference numerals in the attached figures: 110: Perovskite absorber layer; 120: First charge transport layer; 130: Top electrode; 131: Interface layer; 132: Main conductive layer; 133: Protective layer; 140: Second charge transport layer; 100: Top cell; 200: Bottom cell; 300: Composite layer. Detailed Implementation

[0018] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0019] In one aspect of this application, a solar cell is provided. In some embodiments, reference is made to... Figs. 1 to 3 The solar cell includes a perovskite absorber layer 110, a first charge transport layer 120 and a top electrode 130 stacked in sequence. The top electrode 130 includes an interface layer 131, a main conductive layer 132 and a protective layer 133 stacked in sequence. The main conductive layer 132 is located on the side of the interface layer 131 away from the first charge transport layer 120.

[0020] The interface layer 131 includes a first metal nitride, the work function of which is 4.0 eV-5.5 eV. In some embodiments, the work function of the first metal nitride can be 4.0 eV, 4.3 eV, 4.5 eV, 4.7 eV, 5.0 eV, 5.2 eV, or 5.5 eV. Utilizing the tunable photoelectric properties of the metal nitride, energy level alignment between the interface layer and the underlying charge transport layer can be achieved. With the work function of the first metal nitride in the range of 4.0 eV-5.5 eV, optimal energy level alignment between the interface layer and the underlying first charge transport layer can be achieved, reducing the interface barrier, decreasing contact resistance, and enabling a good ohmic contact between the interface layer and the first charge transport layer. The work function is a physical property of the material surface and can be measured using conventional methods, such as ultraviolet photoelectron spectroscopy (UPS) after the material is fabricated into a thin film.

[0021] In some embodiments, the first metal oxynitride includes one or more of titanium oxynitride (TiNO), niobium oxynitride (NbNO), tantalum oxynitride (TaNO), doped titanium oxynitride, doped niobium oxynitride, and doped tantalum oxynitride. The doping element in the doped titanium oxynitride may include one or more of niobium (Nb), tantalum (Ta), zirconium (Zr), and chromium (Cr); the doping element in the doped niobium oxynitride may include one or more of tantalum, zirconium, and chromium; and the doping element in the doped tantalum oxynitride may include one or more of zirconium and chromium. The above materials have an adjustable work function, enabling the interface layer to form a good ohmic contact with the underlying first charge transport layer.

[0022] In some specific embodiments, the doped titanium oxynitride can be niobium, tantalum, zirconium and chromium doped titanium oxynitride, niobium, tantalum and zirconium doped titanium oxynitride, niobium, tantalum and chromium doped titanium oxynitride, niobium, zirconium and chromium doped titanium oxynitride, tantalum, zirconium and chromium doped titanium oxynitride, niobium and tantalum doped titanium oxynitride, niobium and zirconium doped titanium oxynitride, niobium and chromium doped titanium oxynitride, tantalum and zirconium doped titanium oxynitride, tantalum and chromium doped titanium oxynitride, zirconium and chromium doped titanium oxynitride, niobium doped titanium oxynitride, tantalum doped titanium oxynitride, zirconium doped titanium oxynitride or chromium doped titanium oxynitride.

[0023] In some specific embodiments, the doped niobium oxynitride can be tantalum, zirconium, or chromium-doped niobium oxynitride, tantalum and zirconium-doped niobium oxynitride, tantalum and chromium-doped niobium oxynitride, zirconium and chromium-doped niobium oxynitride, tantalum-doped niobium oxynitride, zirconium-doped niobium oxynitride, or chromium-doped niobium oxynitride.

[0024] In some specific embodiments, the doped tantalum oxynitride can be zirconium-doped, chromium-doped, zirconium-doped, or chromium-doped tantalum oxynitride.

[0025] It should be noted that in this paper, the mass content of the doped metal oxynitride is less than that of the main metal element. Taking niobium-doped titanium oxynitride as an example, the mass content of niobium is less than that of titanium.

[0026] In some embodiments, the first charge transport layer 120 can be an electron transport layer, and the work function of the first metal nitride can be 4.0 eV-4.7 eV. Therefore, the contact resistance between the interface layer and the electron transport layer is relatively low, allowing for a good ohmic contact, which is beneficial for improving the fill factor (FF) of the solar cell.

[0027] In other embodiments, the first charge transport layer 120 may be a hole transport layer.

[0028] In some embodiments, the thickness of the interface layer 131 is 10 nm-20 nm. For example, the thickness of the interface layer 131 can be 10 nm, 12 nm, 15 nm, 17 nm, or 20 nm. A thinner interface layer results in higher light transmittance, which is beneficial for improving the overall light transmittance performance of the top electrode. It should be noted that, in this document, the thickness of the film refers to the dimension of the film layer along the direction from the perovskite absorber layer 110 to the top electrode 130.

[0029] In some embodiments, the interface layer 131 may have a nanocrystalline / amorphous structure. This dense nanocrystalline / amorphous structure can effectively block the upward diffusion of components (such as iodine ions) from the perovskite absorber layer and the downward diffusion of metal atoms, thereby improving the overall stability of the solar cell. It should be noted that a nanocrystalline / amorphous structure refers to a structure in which some nanocrystalline particles are precipitated in an amorphous matrix.

[0030] In some embodiments, the interface layer 131 contains crystals, including anatase and rutile crystals, with the number of anatase crystals being greater than the number of rutile crystals. The predominance of anatase crystals and the smaller number of rutile crystals contribute to improved stability of the interface layer.

[0031] The main conductive layer 132 comprises a second metal oxynitride, which includes one or more of indium oxynitride (InON), zinc oxynitride (ZnON), tin oxynitride (SnON), doped indium oxynitride, doped zinc oxynitride, and doped tin oxynitride. The doping element in the doped indium oxynitride, doped zinc oxynitride, and doped tin oxynitride includes one or more of tantalum, zirconium, and chromium. For example, the doping element can be three elements: tantalum, zirconium, and chromium; two elements: tantalum and zirconium; two elements: tantalum and chromium; or one element: zirconium or chromium. Therefore, the main conductive layer has high conductivity and can serve as the main conductive channel for the top electrode. Its conductivity is comparable to that of ITO, and it exhibits superior bending resistance on flexible substrates. Furthermore, the main conductive layer can achieve high transmittance and low resistivity over a wide spectral range (especially in the near-infrared region).

[0032] In some embodiments, the thickness of the main conductive layer 132 can be 80nm-120nm, for example, the thickness of the main conductive layer 132 can be 80nm, 90nm, 100nm, 110nm or 120nm. Therefore, the main conductive layer has excellent conductivity and high light transmittance, which is beneficial for improving the photoelectric conversion efficiency of the solar cell.

[0033] In some embodiments, the main conductive layer 132 has an average transmittance of ≥85% in the wavelength range of 800-1200nm, thereby allowing more longer wavelength light to pass through. In the tandem battery, this can improve the utilization rate of light by the bottom battery, thereby improving the photoelectric conversion efficiency of both the bottom battery and the tandem battery.

[0034] In some embodiments, the sheet resistance of the main conductive layer 132 can be <50Ω / sq, for example, the sheet resistance of the main conductive layer 132 can be 20-48Ω / sq. In some embodiments, the sheet resistance of the main conductive layer 132 can be ≤30Ω / sq, for example, the sheet resistance of the main conductive layer 132 can be 30Ω / sq, 28Ω / sq, 26Ω / sq, 24Ω / sq, etc. Therefore, the main conductive layer has high conductivity, which is beneficial to improving the overall conductivity of the top electrode and the efficiency of the solar cell.

[0035] In some embodiments, by adjusting the nitrogen / oxygen / argon ratio during the sputtering process, the stoichiometric ratio of nitrogen and oxygen can be precisely controlled, thereby achieving high transmittance and low resistivity over a wide spectral range (especially in the near-infrared region).

[0036] In this application, the protective layer 133 comprises one or more of aluminum-doped zinc oxide (AZO) and indium oxynitride. Therefore, this film can serve as an anti-reflection layer, reducing interface light loss and thus improving light utilization. Simultaneously, this film can protect the main conductive layer from the effects of subsequent processes or environmental factors, thereby further enhancing the stability of the top electrode.

[0037] In some embodiments, the main conductive layer 132 and the protective layer 133 can both be indium oxynitride films, and the oxygen content in the protective layer 133 is higher than the oxygen content in the main conductive layer. That is, compared with the main conductive layer, the protective layer is an oxygen-rich InON film.

[0038] In some embodiments, the thickness of the protective layer 133 can be 30nm-50nm, for example, the thickness of the protective layer 133 can be 30nm, 35nm, 40nm, 45nm or 50nm. This is beneficial for further improving the stability of the top electrode.

[0039] The excellent ohmic contact performance of the interface layer 131 and the high conductivity of the main conductive layer 132 work together to significantly reduce series resistance, thereby improving the open-circuit (FF) of the solar cell. The optical loss of the main conductive layer 132 (indium oxynitride, zinc oxynitride, tin oxynitride, etc.) in the near-infrared region is much lower than that of ITO (indium tin oxide), allowing more long-wavelength light to pass through, thus improving the current and photoelectric conversion efficiency of the solar cell. The dense composite structure of the interface layer 131 and the main conductive layer 132, along with the high environmental stability of the protective layer, effectively blocks the intrusion of external water and oxygen and the migration of ions inside the solar cell, thereby significantly improving the operational and environmental stability of the device.

[0040] In some embodiments, reference Fig. 2 and Fig. 3The solar cell may further include a second charge transport layer 140, which is located on the side of the perovskite absorber layer 110 away from the top electrode 130. One of the first charge transport layer 120 and the second charge transport layer 140 is an electron transport layer, and the other is a hole transport layer.

[0041] In some embodiments, the perovskite absorber layer 110 can be made of ABX3, wherein A is a monovalent cation, including but not limited to one or a mixture of several monovalent cations selected from cesium (Cs), rubidium (Rb), methylamino (CH3NH3), and formamidinyl (CH2(NH2)2); B is a divalent cation, including but not limited to one or a mixture of several divalent cations selected from lead (Pb) and tin (Sn); and X is a monovalent anion, including but not limited to one or a mixture of several monovalent anions selected from iodine (I), bromine (Br), chloride (Cl), fluorine (F), and thiocyanate (SCN). In some specific embodiments, the perovskite absorber layer 110 can be made of Cs. x FA 1- x Pb(I y Br 1-y )3, where x and y are 0-1 respectively. In some specific embodiments, the material of the perovskite absorber layer 110 can be Cs 0.22 FA 0.78 Pb(I 0.85 Br 0.15 3.

[0042] In some embodiments, the material of the electron transport layer may include, but is not limited to, tin oxide, fullerenes and their derivatives, imide compounds, quinone compounds, etc. Exemplarily, the imide compounds include one or more of phthalimide, succinimide, N-bromosuccinimide, glutarimide, or maleimide; exemplarily, the quinone compounds include one or more of benzoquinone, naphthoquinone, phenanthrenequinone, or anthraquinone; exemplarily, the fullerenes and their derivatives include fullerene C 60 Fullerene C 70 PCBM([6,6]-phenyl-C 61 methyl butyrate), [6,6]-phenyl C 71 Methyl butyrate (PC) 71 At least one of BM). Further, the electron transport layer can be a single-layer structure, or a double-layer or triple-layer structure. In some specific embodiments, the electron transport layer may include a C layer with a thickness of 15-30 nm. 60 A layer of tin oxide with a thickness of 15-20 nm is added. The tin oxide layer can protect C in subsequent processes. 60 layer.

[0043] In some embodiments, the material of the hole transport layer may include nickel oxide (NiO). x , 1≤x≤2), cuprous iodide (CuI), cuprous oxide (Cu2O), cuprous thiocyanate (CuSCN), 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD), 2,2',7,7'-tetratetra(di-p-tolylamino)spiro-9,9'-difluorene (Spiro-TTB), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), and [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid (MeO-4PACz), (4-(3,6-dimethyl ... (4-(9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACz), [4-(9H-carbazole-9-yl)butyl]phosphonic acid (4PACz), (4-(3,6-dibromo-9H-carbazole-9-yl)butyl)phosphonic acid (Br-4PACz), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), (2-(3,6-dimethyl-9H-carbazole-9-yl)ethyl)phosphonic acid (Me-2PACz), (2-(9H-carbazole-9-yl)ethyl)phosphonic acid (2PACz), (2-(3,6-dibromo-9H-carbazole-9-yl)ethyl)phosphonic acid (Br-2PACz), etc.

[0044] In some embodiments, a SAM (self-assembled monolayer) modification layer may also be provided between the hole transport layer and the perovskite absorber layer.

[0045] In some embodiments, the solar cell can be a single-junction perovskite cell.

[0046] In other embodiments, the solar cell can be a tandem cell, such as a two-terminal tandem cell, a three-terminal tandem cell, etc. (See reference) Fig. 3 The solar cell includes a top cell 100 and a bottom cell 200. The top cell 100 is a perovskite cell, and the bottom cell 200 can be a crystalline silicon cell. A composite layer 300 is disposed between the top cell 100 and the bottom cell 200. In some embodiments, the composite layer 300 can be a transparent conductive composite layer, and the film material can be selected from at least one of ITO (indium tin oxide), IZO (indium zinc oxide), etc. In other embodiments, the composite layer 300 can be a P-type doped silicon layer or an N-type doped silicon layer. The specific structure of the crystalline silicon cell is not particularly limited in this application; those skilled in the art can select and configure it according to actual needs.

[0047] In some embodiments, the top electrode 130 can be a gate line electrode, that is, the top electrode 130 can be fabricated as a patterned gate line.

[0048] In other embodiments, the top electrode 130 can be a full-surface electrode, which helps to reduce the difficulty of fabricating the top electrode. Furthermore, a full-surface electrode can more effectively block water and oxygen, thereby further improving the stability of the solar cell.

[0049] In another aspect of this application, a method for preparing the aforementioned solar cell is proposed, the method comprising the following steps: S100: A first charge transport layer is formed on one side of the perovskite absorber layer.

[0050] In some embodiments, the perovskite absorber layer can be formed by the following steps: preparing a perovskite precursor solution of appropriate concentration, with a solution concentration of 1.3-1.8M, accurately coating it onto the substrate surface using inkjet printing, pre-crystallizing the film layer using a VCD (Vacuum Condensation Device), and then crystallizing it using a thermal annealing method to form the perovskite absorber layer. The annealing temperature can be 100-130℃, and the film layer thickness can be 500-1000nm.

[0051] In some embodiments, the first charge transport layer can be an electron transport layer, which can be formed by the following steps: Electron transport layer: depositing a layer of C on the surface of the perovskite layer by vacuum evaporation. 60 The film thickness can be 15-30 nm; atomic layer deposition is used on C 60 A SnO2 film is deposited on the surface of the film, and the film thickness can be 15-20 nm.

[0052] In some embodiments, before forming the perovskite absorber layer, a step of forming a second charge transport layer is included, the second charge transport layer being located on the side of the perovskite absorber layer away from the top electrode. In some specific embodiments, the first charge transport layer can be an electron transport layer, and the second charge transport layer can be a hole transport layer. Nickel oxide can be deposited as the hole transport layer using magnetron sputtering, and the sputtering pressure can be 4 × 10⁻⁶. -4 -6×10 -4 Pa, the sputtering oxygen partial pressure can be 0.2%-0.6%, and the sputtering film thickness can be 6-10 nm.

[0053] In some embodiments, the second charge transport layer is a hole transport layer, and a modification layer may be disposed between the second charge transport layer and the perovskite absorber layer. The modification layer may be formed by the following steps: preparing a SAM solution of appropriate concentration (0.5-1.5 mg / mL), forming a film on the effective area by inkjet printing or spin coating, and then annealing on a hot plate at 100°C for 10 min, resulting in a film thickness of 1-3 nm. In some embodiments, the modification layer may include one or more materials selected from 2PACz, 4PACz, Me-4PACz, MeO-4PACz, Me-2PACz, 4PADCB, and MeO-2PACz.

[0054] For tandem solar cells, the process includes preparing a base cell and a composite layer before forming the first charge transport layer. This application does not impose specific limitations on the steps for preparing the base cell; those skilled in the art can select and adjust them according to actual needs. For example, the base cell can be prepared using the conventional method for preparing a crystalline silicon base cell in tandem solar cells, and then the composite layer can be prepared on top of the base cell.

[0055] In some embodiments, a transparent conductive composite layer can be deposited above the bottom battery using magnetron sputtering, with a sputtering pressure of 4.5 × 10⁻⁶. -4 -6×10 -4 Pa, the film thickness can be 5-10 nm, and the film material can be ITO, IZO, etc.

[0056] S200: A top electrode is formed on the side of the first charge transport layer away from the perovskite absorption layer.

[0057] In some embodiments, the top electrode can be formed by magnetron sputtering at room temperature (20°C-30°C) to 150°C. Thus, the top electrode fabrication process does not have a significant adverse effect on the underlying heat-sensitive perovskite absorber layer or other films.

[0058] In some embodiments, forming the top electrode includes the following steps: S210: An interface layer is formed on the side of the first charge transport layer away from the perovskite absorption layer.

[0059] In some embodiments, pulsed DC reactive magnetron sputtering can be used to form the interface layer. The target material is a single metal (e.g., titanium, niobium, tantalum, etc.) or an alloy target (niobium-doped titanium target, zirconium-doped niobium target, chromium-doped tantalum target, zirconium and chromium-doped titanium target, etc.), and the atmosphere is a mixture of argon, nitrogen, and oxygen. The composition of the interface layer can be adjusted by the target material and the atmosphere, and its work function can be continuously adjusted in the range of 4.0 eV to 5.5 eV. Utilizing the tunability of its composition and performance, reactive sputtering can perfectly match perovskite solar cells with different structures (nip structure or pin structure perovskite solar cells).

[0060] In some embodiments, for perovskite solar cells with pin structures, the work function of the interface layer material can be adjusted to be in the range of 4.0-4.7 eV by adjusting the target material composition and atmosphere, thereby optimizing energy level matching and further reducing the contact resistance between the interface layer and the first charge transport layer.

[0061] In some embodiments, after sputtering to form the interface layer, it can be annealed in situ at 100°C-150°C for 15-30 minutes. During the annealing process, the oxygen supply is cut off, and an argon and nitrogen atmosphere is maintained. For example, after sputtering to form the interface layer, it can be annealed in situ at 100°C, 115°C, 125°C, 135°C, or 145°C for 15 minutes, 18 minutes, 20 minutes, 23 minutes, 25 minutes, 27 minutes, or 30 minutes, respectively. This can optimize the electrical properties and interfacial contact of the thin film while ensuring that the heat-sensitive perovskite substrate or other film layers are not damaged.

[0062] In some specific embodiments, a niobium-doped titanium oxynitride (TiNbON) interface layer is prepared using pulsed DC reactive magnetron sputtering. The target material is a niobium-doped titanium target (95% titanium by mass, 5% niobium by mass), and the sputtering atmosphere is a mixture of argon, nitrogen, and oxygen. During sputtering, the argon flow rate is controlled at 20-40 sccm, the nitrogen flow rate at 5-15 sccm, and the oxygen flow rate is finely adjusted in 0.05 sccm steps within the range of 0.1-1 sccm to stabilize the N2 / O2 volume ratio at 5-27, thereby adjusting the work function of the interface layer to 4.0-4.5 eV, and connecting it to the electron transport layer (e.g., SnO). x Energy level matching. In some embodiments, the thickness of the interface layer is controlled at 10-20 nm.

[0063] After sputtering, the oxygen supply is turned off, and the film is annealed in situ in an Ar / N2 mixed atmosphere at 100-150℃ for 15-30 minutes. Then, N2 is introduced into the same chamber and plasma is generated. The film is then subjected to plasma post-treatment at about 100℃ for 30 minutes. This treatment can promote the preferential formation of anatase phase nanocrystals in the film, obtain a nanocrystalline / amorphous composite structure, and significantly improve the chemical stability of the film.

[0064] S220: The main conductive layer is formed on the side of the interface layer away from the perovskite absorber layer.

[0065] In some embodiments, pulsed DC reactive magnetron sputtering can be used to form the main conductive layer, with the target being a single metal (e.g., indium target, zinc target, tin target, etc.) or an alloy target. After forming the interface layer, the target can be replaced in the same PVD equipment, and pulsed DC reactive magnetron sputtering can be performed again to prepare the main conductive layer.

[0066] In some embodiments, after the interface layer is formed, the target material can be replaced with an indium target, and an indium oxynitride main conductive layer can be formed using pulsed DC reactive magnetron sputtering. This conductive layer has excellent conductivity and good light transmittance, which is beneficial to improving the overall performance of the top electrode.

[0067] In some specific embodiments, after the interface layer is formed, an indium target is replaced within the same PVD equipment, and pulsed direct current (DC) reactive magnetron sputtering is continued. Atmosphere control: The N2 / O2 ratio is adjusted to ensure that the average transmittance of the deposited InON film is ≥85% and the sheet resistance is <50Ω / sq in the wavelength range of 800-1200nm. The specific process is as follows: Based on a fixed N2 flow rate of 10sccm, the O2 flow rate is finely adjusted within the range of 0 to 0.5sccm. The working pressure of the reaction chamber can be between 0.5Pa and 1.0Pa, the deposition time can be about 30 minutes, which can be adjusted as needed, and the deposition thickness is 80-120nm.

[0068] S230: A protective layer is formed on the side of the main conductive layer away from the perovskite absorber layer.

[0069] In some embodiments, a protective layer can be formed by radio frequency sputtering. After sputtering, the protective layer can be annealed in air at 100°C-150°C for 15-30 minutes. This results in a dense film with good compositional consistency, which can serve as an effective encapsulation layer to block water and oxygen corrosion, thereby helping to extend battery life.

[0070] In some embodiments, after the main conductive layer is formed, an aluminum-doped zinc oxide (AZO) protective layer can be formed by radio frequency (RF) sputtering.

[0071] In some specific embodiments, the cavity vacuum level should be better than 1.0 × 10⁻⁶ when preparing the protective layer. -4 The operating pressure is 0.3-0.6 Pa. The power supply frequency can be 13.56 MHz, the sputtering power can be 200-300 W, the Ar flow rate can be set to 20-40 sccm, and the O2 flow rate can be 0 sccm or twice the Ar flow rate (the specific requirement depends on the target material characteristics). The protective layer prepared under these conditions has certain conductivity and good density, providing anti-reflection and preventing water and oxygen erosion.

[0072] The entire composite electrode deposition can be completed in a single operation via magnetron sputtering at temperatures ranging from room temperature to 150°C. Different compositional films can be fabricated by switching the target material and reactive gas, offering strong process compatibility, high efficiency, and minimal thermal damage to the underlying perovskite absorber layer. By continuously depositing metal nitrides of different compositions within the same vacuum chamber, an "in-situ multilayer structure" with compositional gradients can be formed, achieving a smooth transition in energy levels and lattice from the bottom to the top layer, minimizing interface defects and contact resistance.

[0073] This application designs a multifunctional stacked electrode structure based on metal nitride oxides, constructing a composite structure that synergistically integrates electrical, optical, and mechanical aspects. This achieves a four-in-one integration of interface modification, current harvesting, optical modulation, and encapsulation protection, enabling low resistance, high transmittance, and highly stable current harvesting. Utilizing the density of the interface layer and main conductive layer, the density of the protective layer, and its high environmental stability, it serves as an effective encapsulation layer, blocking water and oxygen erosion and inhibiting internal ion migration, thereby improving the battery's operational and environmental stability and extending its lifespan. The optical loss of the main conductive layer in the near-infrared region is far lower than that of ITO, allowing more long-wavelength light to pass through. When the top electrode is used in a stacked battery, more long-wavelength light can be transmitted to the bottom cell, increasing the current in the bottom cell and thus improving the total current and photoelectric conversion efficiency of the stacked battery.

[0074] This application, for the first time, applies a metal oxynitride system with tunable photoelectric properties to the transparent top electrode of a perovskite tandem solar cell, replacing the traditional ITO / metal approach. Utilizing the tunable photoelectric properties of the metal oxynitride, optimal energy level alignment with the underlying charge transport layer is achieved, reducing the interface barrier. The excellent ohmic contact of the interface layer and the high conductivity of the main conductive layer work together to significantly reduce series resistance and improve the cell's fill factor. Using a composite transparent electrode material instead of a metal top electrode improves photon utilization, avoids the use of precious metals, and reduces material costs. The top electrode of this application employs a low-temperature, in-situ, reactive sputtering and low-temperature annealing fabrication process, which is simple, controllable, and easily scalable, with high compatibility with existing semiconductor processes. In summary, the solar cell proposed in this application demonstrates significant potential and comprehensive advantages in terms of efficiency, stability, cost (avoiding the use of precious metals), and flexibility.

[0075] In another aspect of this application, a photovoltaic module is provided, which includes the aforementioned solar cell.

[0076] In some embodiments of this application, the photovoltaic module may include a plurality of the aforementioned solar cells.

[0077] The present application will be described below through specific embodiments. Those skilled in the art will understand that the specific embodiments below are merely illustrative and do not limit the scope of the present application in any way. Furthermore, in the following embodiments, unless otherwise specified, the materials and equipment used are commercially available. If specific processing conditions and methods are not explicitly described in the later embodiments, conditions and methods known in the art can be used for processing.

[0078] Example 1 This embodiment describes the fabrication of a perovskite / crystalline silicon tandem solar cell based on a TiNbNO / InON / AZO composite electrode.

[0079] The following method is used to fabricate a perovskite top solar cell based on the provided crystalline silicon bottom solar cell: (1.1) Composite layer: A transparent conductive composite layer was deposited on the surface of N-Poly (the uppermost film layer of the crystalline silicon bottom cell) by magnetron sputtering at a sputtering pressure of 4.5 × 10⁻⁶. -4 -6×10 -4 Pa, film thickness is 5-10 nm, film material is ITO or IZO.

[0080] (1.2) Hole transport layer: Nickel oxide was deposited on the surface of the composite layer as a hole transport layer using magnetron sputtering at a sputtering pressure of 4 × 10⁻⁶. -4 -6×10 -4 Pa, sputtering oxygen partial pressure is 0.2%-0.6%, and sputtering film thickness is 6-10 nm.

[0081] (1.3) Modification layer: Prepare a SAM solution of appropriate concentration (including one or more of Me-4PACZ and related derivative materials) with a concentration of 0.5-1.5 mg / mL. Form a film in the effective area by inkjet printing or spin coating, and then anneal on a hot stage at 100℃ for 10 min. The film thickness is 1-3 nm.

[0082] (1.4) Perovskite absorber layer: Prepare a perovskite precursor solution of appropriate concentration, with a solution concentration of 1.3-1.8M. It is also precisely coated on the substrate surface by inkjet printing. The film is pre-crystallized by VCD equipment, and then crystallized by thermal annealing to form a perovskite absorber layer. The annealing temperature is 100-130℃, and the film thickness is 500-1000nm.

[0083] (1.5) Electron transport layer: A C layer is deposited on the surface of the perovskite absorber layer using vacuum evaporation. 60 The film thickness is 15-30nm.

[0084] (1.6) Tunneling layer: Atomic layer deposition is used in C60 A tin oxide film with a thickness of 15-20 nm is deposited on the surface of the film.

[0085] Subsequent film layers are prepared on a substrate on which crystalline silicon bottom cells, composite layers, and perovskite top cells (including hole transport layers, perovskite absorber layers, and electron transport layers) have already been completed.

[0086] (2) Depositional interface layer (TiNbNO): Process: Pulsed DC reactive magnetron sputtering (PVD).

[0087] Target material: Nb-doped titanium target, with a titanium mass content of 95% and an Nb mass content of 5%.

[0088] Atmosphere: A mixture of Ar, N2, and O2 gases.

[0089] The experiment began with an Ar flow rate of 30 sccm, an N2 flow rate of 12 sccm, an O2 flow rate of 0.45-0.5 sccm, and a sputtering power of 200 W. This stabilized the thin film work function at 4.0-4.5 eV, matching the energy level of tin oxide, and the thickness was 10-20 nm.

[0090] Post-processing: The device with deposited TiNbNO thin films is annealed in situ within the PVD equipment process chamber at 100-150°C for 15-30 minutes. During annealing, an argon and nitrogen atmosphere is maintained, and the oxygen supply is cut off to ensure no oxygen is present. This optimizes the electrical properties and interfacial contact of the film while preventing damage to the heat-sensitive perovskite substrate. Furthermore, it is necessary to ensure that the film is predominantly anatase with a small amount of rutile crystals to enhance stability. Specifically, the deposited TiNbNO thin film is treated at approximately 100°C under N2 plasma conditions for about 30 minutes.

[0091] (3) Deposition of the main conductive layer (InON): Process: In the same PVD equipment, the indium target is replaced and pulsed DC reactive magnetron sputtering is continued.

[0092] Atmosphere control: Adjust the N2 / O2 ratio to ensure that the deposited InON film has an average transmittance ≥85% and a sheet resistance <50Ω / sq between wavelengths of 800-1200nm. The specific process is as follows: Based on a fixed N2 flow rate of 10 sccm, the O2 flow rate is finely adjusted within the range of 0 to 0.5 sccm. The working pressure of the reaction chamber is between 0.5 Pa and 1.0 Pa. The deposition time is 30 minutes, and the deposition thickness is 80-120 nm.

[0093] (4) Protective deposition layer (AZO): Process: RF sputtering, AZO target (AZO ceramic target ZnO:Al2O3, using target with Al2O3 doping of 2 wt%).

[0094] Protective layer thickness: 30-50nm.

[0095] The cavity vacuum level is better than 1.0 × 10⁻⁶. -4 The operating pressure is 0.4 Pa, the power supply frequency is 13.56 MHz, the sputtering power is 250 W, the Ar flow rate is set to 30 sccm, the O2 flow rate is 0 sccm, and the working pressure is 0.4 Pa.

[0096] Post-annealing process: Anneal in air at 100°C for 15 minutes to further stabilize the electrode structure.

[0097] Comparative Example 1 Unlike Example 1, Comparative Example 1 uses an ITO / Ag electrode (composite electrode) as the top electrode, while the remaining steps and parameters are the same as in Example 1.

[0098] The fabrication steps for the top electrode (ITO / Ag) are as follows (after completing the tin oxide deposition of the tunneling layer): (1) Deposition of a transparent conductive oxide layer (ITO): Process: DC magnetron sputtering.

[0099] Target material: ITO ceramic target (In2O3:SnO2 mass ratio of 90:10, purity ≥99.99%).

[0100] Atmosphere: pure Ar atmosphere, O2 flow rate of 0 sccm (or very small amount, to avoid Ag oxidation).

[0101] Ar gas flow rate: 30 sccm, working pressure: 0.4 Pa, sputtering power: 250 W. Substrate temperature: room temperature (without heating). Deposition thickness: 40 ± 5 nm (controlled by deposition time, sputtering rate approximately 0.1-0.2 nm / s, time approximately 200-400 seconds).

[0102] (2) Deposited metallic silver layer (Ag): Process: Vacuum thermal evaporation (or DC magnetron sputtering, thermal evaporation is gentler).

[0103] Vacuum degree: better than 5×10 -4 Pa. Evaporation rate: Initial rate is 0.1-0.3 nm / s, which can be increased to 1.0-2.0 nm / s after stabilization (due to the large thickness). A crystal oscillator thickness gauge is used for control; Ag layer thickness: 600 ± 20 nm. The substrate is kept water-cooled or at room temperature during deposition to avoid overheating and damage to the underlying layer.

[0104] Example 2 Unlike Example 1, in Example 2 the interface layer is undoped titanium oxynitride, and the remaining steps and parameters are the same as in Example 1.

[0105] Deposition interface layer (TiON, after the completion of tin oxide deposition in the tunneling layer): Process: Pulsed DC reactive magnetron sputtering (PVD).

[0106] Target material: pure titanium target (Ti purity ≥ 99.99%).

[0107] Atmosphere: A mixture of Ar, N2, and O2 gases.

[0108] The Ar gas flow rate was set at 20-40 sccm, the N2 flow rate at 5-15 sccm, and the O2 flow rate adjusted in 0.05 sccm increments within the range of 0.1-1 sccm to stabilize the thin film work function at 4.0-4.5 eV, matching the energy level of the underlying tin oxide tunneling layer. The interface layer thickness was 10-20 nm.

[0109] Post-processing: The device with deposited TiON thin film is annealed in situ in the process chamber of the PVD equipment at 100-150°C for 15-30 minutes in an annealing atmosphere of Ar and N2 (oxygen-free) to optimize electrical performance and interfacial contact. Simultaneously, it is treated at approximately 100°C under N2 plasma conditions for about 30 minutes to ensure that the anatase crystal form is dominant in the film, with a small amount of rutile crystal form to improve stability.

[0110] Example 3 Unlike Example 1, in Example 3 the interface layer is zirconium and chromium-doped titanium oxynitride, and the preparation steps of the interface layer are as follows: Deposition interface layer (TiZrCrNO, after the tin oxide deposition of the tunneling layer is completed): Process: Pulsed DC reactive magnetron sputtering (PVD).

[0111] Target material: Titanium-zirconium-chromium alloy target, wherein the mass content of titanium is 90%, the mass content of zirconium is 6%, and the mass content of chromium is 4% (all with a purity ≥ 99.9%).

[0112] Atmosphere: A mixture of Ar, N2, and O2 gases.

[0113] The Ar gas flow rate was set at 20-40 sccm, the N2 flow rate was initially set at 5-15 sccm, and the O2 flow rate was finely adjusted in 0.05 sccm increments within the range of 0.1-1 sccm to stabilize the thin film work function at 4.0-4.5 eV, matching the energy level of the tin oxide tunneling layer. The interface layer thickness was 10-20 nm.

[0114] Post-processing: The device with the deposited TiZrCrNO thin film was annealed in situ in the process chamber of a PVD equipment at 100-150°C for 15-30 minutes in an annealing atmosphere of Ar and N2 (oxygen-free). Subsequently, it was treated at approximately 100°C under N2 plasma conditions for about 30 minutes to promote the formation of a structure dominated by anatase phase and a small amount of rutile phase, thereby optimizing interfacial contact and stability. The remaining steps and parameters were the same as in Example 1.

[0115] Example 4 Unlike Example 1, in Example 4 the main conductive layer is tantalum-doped indium oxynitride, and the preparation steps of the main conductive layer are as follows: Deposition of the main conductive layer (InTaON, after the interface layer deposition is completed): Process: In the same PVD equipment, the target is replaced with an indium-tantalum alloy target, and pulsed DC reactive magnetron sputtering is continued.

[0116] Target material: Indium-tantalum alloy target, wherein the mass content of indium is 95% and the mass content of tantalum is 5% (both have a purity ≥99.99%).

[0117] Atmosphere control: Adjust the N2 / O2 ratio to ensure that the average transmittance of the deposited InTaON film is ≥85% and the sheet resistance is <50Ω / sq in the wavelength range of 800-1200nm.

[0118] Specific process parameters: N2 flow rate is fixed at 10 sccm, O2 flow rate is finely adjusted in 0.05 sccm increments within the range of 0 to 0.5 sccm, working pressure of reaction chamber is 0.5-1.0 Pa, deposition time is about 30 minutes, and deposition thickness is 80-120 nm.

[0119] Post-treatment: After deposition, the film is annealed in situ in a PVD apparatus at a temperature of 100-150°C for 15-30 minutes in an atmosphere of Ar and N2 (oxygen-free) to stabilize the electrical properties and optical transmittance of the film. The remaining steps and parameters are the same as in Example 1.

[0120] Experimental Results and Performance Analysis The top electrodes and batteries prepared in the above embodiments and comparative examples were tested. The test results of the top electrodes are recorded in Table 1, and the test results of the batteries are recorded in Table 2.

[0121] Table 1

[0122] Table 2

[0123] In Table 2, Voc refers to open-circuit voltage, Jsc refers to short-circuit current, FF refers to fill factor, and PCE refers to photoelectric conversion efficiency.

[0124] As shown in Tables 1 and 2, compared with Comparative Example 1, the use of multilayer composite top electrodes in Examples 1-4 can reduce the contact resistance between the top electrode and the lower transmission layer and increase the light transmittance of the top electrode, thereby improving the photoelectric conversion efficiency of the tandem battery.

[0125] In the description of this application, the terms "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and do not require this application to be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this application.

[0126] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," and "other embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment is included in at least one embodiment of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples, without contradiction. Additionally, it should be noted that in this specification, 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 indicated technical features.

[0127] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A solar cell, characterized in that, It includes a perovskite absorber layer, a first charge transport layer and a top electrode stacked in sequence. The top electrode includes an interface layer, a main conductive layer and a protective layer stacked in sequence. The main conductive layer is located on the side of the interface layer away from the first charge transport layer. The interface layer includes a first metal nitride oxide, the work function of which is 4.0 eV-5.5 eV; The main conductive layer includes a second metal oxynitride, which includes one or more of indium oxynitride, zinc oxynitride, tin oxynitride, doped indium oxynitride, doped zinc oxynitride, and doped tin oxynitride. The doping element in the doped indium oxynitride, doped zinc oxynitride, and doped tin oxynitride includes one or more of tantalum, zirconium, and chromium. The protective layer comprises one or more of aluminum-doped zinc oxide and indium oxynitride.

2. The solar cell according to claim 1, characterized in that, The first metal nitride includes one or more of titanium nitride, niobium nitride, tantalum nitride, doped titanium nitride, doped niobium nitride, and doped tantalum nitride. The doping elements in doped titanium oxynitride include one or more of niobium, tantalum, zirconium, and chromium; The doping elements in doped niobium oxynitride include one or more of tantalum, zirconium, and chromium; The doping elements in doped tantalum oxynitride include one or more of zirconium and chromium.

3. The solar cell according to claim 1, characterized in that, The top electrode satisfies at least one of the following conditions: The thickness of the interface layer is 10nm-20nm; The interface layer has a nanocrystalline / amorphous structure; The crystals in the interface layer include anatase and rutile crystals, and the number of anatase crystals is greater than the number of rutile crystals. The thickness of the main conductive layer is 80nm-120nm; The main conductive layer has an average transmittance of ≥85% in the wavelength range of 800-1200nm; The sheet resistance of the main conductive layer is <50Ω / sq; The thickness of the protective layer is 30nm-50nm.

4. The solar cell according to any one of claims 1-3, characterized in that, The first charge transport layer is an electron transport layer, and the work function of the first metal nitride is 4.0 eV-4.7 eV.

5. The solar cell according to any one of claims 1-3, characterized in that, The solar cell is a tandem cell; and / or, the top electrode is a grid line electrode or a full-surface electrode.

6. A method for preparing a solar cell according to any one of claims 1-5, characterized in that, include: A first charge transport layer is formed on one side of the perovskite absorber layer; A top electrode is formed on the side of the first charge transport layer away from the perovskite absorber layer; Forming the top electrode includes the following steps: An interface layer is formed on the side of the first charge transport layer away from the perovskite absorber layer; A main conductive layer is formed on the side of the interface layer away from the perovskite absorber layer. A protective layer is formed on the side of the main conductive layer away from the perovskite absorber layer.

7. The method according to claim 6, characterized in that, The top electrode is formed by magnetron sputtering at room temperature to 150°C.

8. The method according to claim 6 or 7, characterized in that, At least one of the following conditions must be met: The interface layer is formed by pulsed DC reactive magnetron sputtering, with the target material being a single metal or alloy target material, and the atmosphere being a mixture of argon, nitrogen, and oxygen. After the sputtering forms the interface layer, it is annealed in situ at 100℃-150℃ for 15min-30min. During the annealing process, the oxygen supply is cut off and an argon and nitrogen atmosphere is maintained. The main conductive layer is formed by pulsed DC reactive magnetron sputtering, with the target material being a single metal or alloy target. The protective layer is formed by radio frequency sputtering; After the protective layer is formed by sputtering, it is annealed in air at 100℃-150℃ for 15min-30min.

9. The method according to claim 6 or 7, characterized in that, Forming the top electrode includes the following steps: Niobium-doped titanium oxynitride interface layer is formed by pulsed DC reactive magnetron sputtering. The target material is niobium-doped titanium target. The atmosphere is a mixture of argon, nitrogen and oxygen, with a nitrogen to oxygen volume ratio of 5-27. After the interface layer is formed, the oxygen supply is cut off and the mixture is annealed in situ at 100℃-150℃ for 15-30 min. After the interface layer is formed, the target material is replaced with an indium target, and pulsed DC reactive magnetron sputtering is used to form the indium oxynitride main conductive layer; After the main conductive layer is formed, an aluminum-doped zinc oxide protective layer is formed by radio frequency sputtering.

10. A photovoltaic module, characterized in that, The solar cell includes any one of claims 1-5.

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