Solar cell, preparation method and photovoltaic module

Abstract

The invention provides a solar cell, a preparation method and a photovoltaic module, and can be widely applied to the technical field of cells. The first carrier transport layer is arranged on the bottom battery; the two-dimensional perovskite layer is arranged on the first carrier transport layer; the number of the inorganic layers between every two adjacent organic layers in the two-dimensional perovskite layer is 1; the three-dimensional perovskite layer is arranged on the two-dimensional perovskite layer; the second carrier transport layer is arranged on the three-dimensional perovskite layer; the type of carriers transmitted by the second carrier transmission layer is different from that of carriers transmitted by the first carrier transmission layer; and the metal electrode layer is arranged on the second carrier transmission layer. According to the invention, the surface microstructure of the silicon substrate can be matched under the condition that the passivation effect is not changed, and uniform coverage of the microstructure is realized, so that the overall performance of the battery is improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a solar cell, a preparation method thereof, and a photovoltaic module. Background Technology

[0002] In the current field of solar cell technology, especially in the development of two-sided perovskite / crystalline silicon tandem cells, the double-textured light-trapping structure has become a key design for improving the photoelectric conversion efficiency of cells. This structure, by fabricating submicron or micron-level random pyramidal textures on both sides of the silicon wafer, not only maintains process compatibility with existing crystalline silicon cell production lines, but also significantly enhances light-trapping efficiency, thereby improving the current density and overall conversion efficiency of the device.

[0003] However, the introduction of the double-textured structure also brings significant technical challenges, especially in the deposition process of perovskite thin films. The random pyramidal texture on the silicon wafer surface has sharp geometric edges, which makes it impossible to achieve uniform coverage of the passivation material at the buried interface. Related deposition methods often fail to form a continuous and uniform passivation interface in these complex microstructures, especially in the buried recessed areas of the pyramidal structure. During the film formation process, these areas are prone to pinhole defects and incomplete coverage, leading to an increase in carrier recombination centers and a decrease in shunt resistance. Ultimately, this severely limits the open-circuit voltage and fill factor of the device, thus affecting the overall performance of the tandem solar cell. Summary of the Invention

[0004] The main purpose of this application is to provide solar cells, preparation methods and photovoltaic modules to at least solve the problem that the buried interface of solar cells in the prior art cannot uniformly cover the pyramid structure.

[0005] To achieve the above objectives, according to one aspect of this application, a solar cell is provided, comprising: a base cell; a first carrier transport layer disposed on the base cell; a two-dimensional perovskite layer disposed on the first carrier transport layer; wherein the number of inorganic layers between every two adjacent organic layers in the two-dimensional perovskite layer is one; a three-dimensional perovskite layer disposed on the two-dimensional perovskite layer; a second carrier transport layer disposed on the three-dimensional perovskite layer; wherein the type of carriers transported by the second carrier transport layer is different from the type of carriers transported by the first carrier transport layer; and a metal electrode layer disposed on the second carrier transport layer. The buried interface prepared by the two-dimensional perovskite layer with one inorganic layer in the solar cell provided by this application has conformal properties, enabling it to match the surface microstructure of the silicon substrate without changing the passivation effect, achieving uniform coverage of the microstructure to improve the overall performance of the cell.

[0006] Optionally, the two-dimensional perovskite layer is prepared by a two-step method using inorganic and organic salts, and the two-dimensional perovskite layer includes compounds represented by the general formula (A')2BX4.

[0007] Optionally, the thickness of the two-dimensional perovskite layer is 1 to 15 nm, the two-dimensional perovskite layer includes a Rudsden-Bopper layered structure, the interlayer spacing of the Rudsden-Bopper layered structure is 1.45 to 1.60 nm, and the optical band gap is 2.3 to 2.5 eV.

[0008] Optionally, the thickness of the two-dimensional perovskite layer is 3 to 8 nm.

[0009] Optionally, a conductive oxide layer is provided between the first carrier transport layer and the bottom cell, and between the second carrier transport layer and the metal electrode layer. The material of the conductive oxide layer includes any one or more of indium tin oxide, fluorine-doped tin oxide, indium zinc oxide, and aluminum-doped zinc oxide.

[0010] To achieve the above objectives, according to another aspect of this application, a method for preparing a solar cell is provided, the method comprising:

[0011] A bottom cell is provided, and a first carrier transport layer is formed on the bottom cell;

[0012] A two-dimensional perovskite layer is formed on the first carrier transport layer, and the number of inorganic layers between every two adjacent organic layers in the two-dimensional perovskite layer is 1.

[0013] A three-dimensional perovskite layer is formed on the two-dimensional perovskite layer;

[0014] A second carrier transport layer is formed on top of the three-dimensional perovskite layer; the type of carriers transported by the second carrier transport layer is different from the type of carriers transported by the first carrier transport layer.

[0015] A metal electrode layer is formed on top of the second carrier transport layer.

[0016] Optionally, forming a two-dimensional perovskite layer on top of the first carrier transport layer includes:

[0017] The two-dimensional perovskite layer is formed by depositing inorganic and organic salts on the first carrier transport layer in a two-step process, including:

[0018] An inorganic salt of a predetermined thickness is deposited on the first carrier transport layer; wherein the predetermined thickness is 1 to 30 nm.

[0019] An organic ammonium salt is spin-coated onto the inorganic salt using a first solvent of a preset concentration, and the organic ammonium salt is then annealed to form the two-dimensional perovskite layer; wherein the preset concentration is 10 to 30 mg / mL.

[0020] Optionally, before spin-coating the organic ammonium salt onto the inorganic salt, the method further includes:

[0021] The organic ammonium salt is dropped onto the inorganic salt and left to stand for a preset time, wherein the preset time is 5 to 30 seconds.

[0022] Optionally, forming a three-dimensional perovskite layer on the two-dimensional perovskite layer includes:

[0023] The perovskite precursor solution is deposited onto the two-dimensional perovskite layer, and the perovskite precursor solution is subjected to a first-duration vacuum pumping treatment and a second-duration annealing treatment to obtain the three-dimensional perovskite layer.

[0024] According to another aspect of this application, a buried interface passivation structure for a solar cell is provided for the aforementioned solar cell. The buried interface passivation structure includes a two-dimensional perovskite layer between a first carrier transport layer and a perovskite light-absorbing layer; wherein the number of inorganic layers between every two adjacent organic layers in the two-dimensional perovskite layer is 1.

[0025] According to another aspect of this application, a photovoltaic module is provided, including the aforementioned solar cell.

[0026] By applying the technical solution of this application, the buried interface prepared by the two-dimensional perovskite layer with one inorganic layer in the solar cell provided by this application has conformal properties. It can match the surface microstructure of the silicon substrate without changing the passivation effect, so as to achieve uniform coverage of the microstructure and improve the overall performance of the cell.

[0027] Specifically, the conformal deposition characteristics of the two-dimensional perovskite layer ensure that it can uniformly cover the complex surface structure of the bottom cell, effectively eliminate defects such as pores at the perovskite bottom interface, optimize the energy level arrangement, and enhance the carrier extraction efficiency.

[0028] Furthermore, by precisely controlling the thickness of the two-dimensional perovskite layer and the spin-coating and settling time of the organic salt, the open-circuit voltage and fill factor of the cell were further improved, thereby significantly enhancing the overall conversion efficiency of the solar cell.

[0029] This innovative solution not only solves the problem of incomplete passivation of the buried interface in existing technologies, but also is highly compatible with existing crystalline silicon cell production line processes, paving the way for the industrial production of perovskite / crystalline silicon tandem cells. Attached Figure Description

[0030] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0031] Figure 1 A schematic diagram of the structure of a solar cell provided in an embodiment of this application is shown;

[0032] Figure 2 A schematic flowchart illustrating the fabrication process of a solar cell according to an embodiment of this application is shown.

[0033] Figure 3 A schematic diagram showing a comparison of the effects of solar cells provided according to embodiments of this application is illustrated.

[0034] The above figures include the following reference numerals:

[0035] 11, Second metal electrode; 12, Anti-reflection layer; 13, Second conductive oxide; 14, Buffer layer; 15, Second carrier transport layer; 16, Three-dimensional perovskite layer; 17, Two-dimensional perovskite layer; 18, First carrier transport layer; 19, First conductive oxide; 20, Crystalline silicon substrate; 21, Third conductive oxide; 22, First metal electrode. Detailed Implementation

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0039] As described in the background section, in related technologies:

[0040] In the current field of solar cell technology, especially in the development of two-sided perovskite / crystalline silicon tandem cells, the double-textured light-trapping structure has become a key design for improving the photoelectric conversion efficiency of cells. This structure, by fabricating submicron or micron-level random pyramidal textures on both sides of the silicon wafer, not only maintains process compatibility with existing crystalline silicon cell production lines, but also significantly enhances light-trapping efficiency, thereby improving the current density and overall conversion efficiency of the device.

[0041] However, the introduction of the double-textured structure also brings significant technical challenges, especially in the deposition process of perovskite thin films. The random pyramidal texture on the silicon wafer surface has sharp geometric edges, which makes it impossible to achieve uniform coverage of the passivation material at the buried interface. Traditional deposition methods often fail to form a continuous and uniform passivation interface in these complex microstructures, especially in the buried recessed areas of the pyramidal structure. During the film formation process, these areas are prone to pinhole defects and incomplete coverage, leading to an increase in carrier recombination centers and a decrease in shunt resistance. Ultimately, this severely limits the open-circuit voltage (Voc) and fill factor (FF) of the device, thus affecting the overall performance of the tandem solar cell.

[0042] Furthermore, most passivation techniques currently struggle to achieve uniform coverage of all surface areas when dealing with these complex buried interfaces, especially in hard-to-reach micro-recesses, which further exacerbates the interface defect problem. Therefore, finding an effective solution to address the incomplete passivation of buried interfaces in perovskite / crystalline silicon tandem solar cells has become a research hotspot and a critical issue urgently needing resolution in this field.

[0043] In summary, existing technologies have significant shortcomings and limitations in the fabrication of perovskite / crystalline silicon tandem solar cells, particularly in ensuring uniform coverage of the passivation layer at the buried interface, eliminating interface defects, and optimizing energy level matching. These technical issues directly affect the photoelectric conversion efficiency and stability of the tandem solar cells, representing a critical technical barrier that researchers in this field urgently need to overcome.

[0044] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0045] Figure 1 This is a schematic diagram of the structure of a solar cell according to an embodiment of this application. The solar cell includes:

[0046] 20-cell battery;

[0047] A first carrier transport layer 18 is disposed on the bottom battery;

[0048] A two-dimensional perovskite layer 17 is disposed above the first carrier transport layer; the number of inorganic layers between every two adjacent organic layers in the two-dimensional perovskite layer is 1.

[0049] A three-dimensional perovskite layer 16 is disposed on the two-dimensional perovskite layer;

[0050] A second carrier transport layer 15 is disposed on the three-dimensional perovskite layer; the type of carriers transported by the second carrier transport layer is different from the type of carriers transported by the first carrier transport layer.

[0051] A metal electrode layer is disposed on the second carrier transport layer.

[0052] In some embodiments, a first conductive oxide layer 19 is further disposed between the first carrier transport layer and the bottom cell, and the first conductive oxide layer is disposed on the bottom cell. A second conductive oxide layer 13 is further disposed between the second carrier transport layer and the metal electrode layer, and the second conductive oxide layer 13 is disposed on the second carrier transport layer. (Refer to...) Figure 1 As shown, the second metal electrode layer 11 is disposed above the second carrier transport layer. A third conductive oxide layer 21 and a first metal electrode layer 22 are fabricated beneath the bottom cell in this application. An anti-reflection layer 12 is disposed between the second metal electrode and the second conductive oxide layer, and a buffer layer 14 is disposed on the second carrier transport layer.

[0053] In some embodiments, the solar cell provided in this application includes a bottom cell, a perovskite cell, and an intermediate layer between the bottom cell and the perovskite cell; the intermediate layer includes a two-dimensional perovskite layer. The intermediate layer is a buried interface. In this application, the buried interface is the critical connection interface located between the bottom of the perovskite sub-cell and the top of the crystalline silicon sub-cell in a perovskite / crystalline silicon tandem solar cell.

[0054] Understandably, n represents the number of inorganic layers in each structural unit of a two-dimensional perovskite. The value of n directly determines the photoelectric properties and stability of the material. Specifically, regarding stability: generally, the smaller the value of n, the higher the proportion of organic cations, and the better the material stability.

[0055] By applying the technical solution of this application, the conformal buried interface passivation structure of solar cells can effectively solve the problem of buried interface defects in perovskite / crystalline silicon tandem cells at both ends, as well as the incomplete interface passivation caused by the inability of existing passivation technologies to uniformly cover the pyramid structure. By setting a two-dimensional perovskite layer on the first carrier transport layer, wherein the number of inorganic layers between every two adjacent organic layers in the two-dimensional perovskite layer is 1, forming an n=1 two-dimensional perovskite layer, it can uniformly cover the textured surface of the bottom cell and eliminate defects such as pores at the perovskite bottom interface. Next, a three-dimensional perovskite layer is set on the two-dimensional perovskite layer to construct a 2D / 3D heterojunction, optimize the energy level arrangement, promote the effective separation and transport of carriers, and thus improve the photoelectric conversion efficiency of the cell. Finally, a second carrier transport layer is set on the three-dimensional perovskite layer to transport carriers different from those in the first carrier transport layer, further enhancing the carrier extraction and transport capabilities. A metal electrode layer is fabricated on the second carrier transport layer to complete the cell structure. The conformal passivation structure of this invention fundamentally eliminates the interface passivation blind zone caused by the textured structure, improves the open-circuit voltage and fill factor of the battery, and enhances the overall performance of the perovskite / crystalline silicon tandem battery at both ends.

[0056] Optionally, the two-dimensional perovskite layer is prepared by a two-step method using inorganic and organic salts, and the two-dimensional perovskite layer includes compounds represented by the general formula (A')2BX4.

[0057] In this application, A' is a monovalent organic ammonium cation, B is a divalent metal cation, and X is a halide anion. In one specific embodiment, the chemical composition of the two-dimensional perovskite layer is n=1 PEA2PbX4, where X represents I, Br, or Cl. This design overcomes the problem of uniformly covering the buried interface with passivating agents in traditional processes, significantly improves the passivation effect in the pyramid texture region, eliminates the resulting pinhole defects, enhances the carrier extraction efficiency, optimizes the energy level arrangement, and thus improves the open-circuit voltage Voc and fill factor FF of the cell, ultimately significantly enhancing the overall performance of the two-sided perovskite / crystalline silicon tandem solar cell.

[0058] The introduction of a conformal 2D-PVSK structure in this application improves the short-circuit current, open-circuit voltage, and fill factor of the battery, indicating that this structure can effectively passivate the buried interface, reduce carrier recombination, and improve photoelectric conversion efficiency. The technical solution of this invention not only solves the problem of incomplete passivation of the buried interface but also demonstrates excellent adaptability and conformal performance on complex surface structures, providing a new approach for performance optimization of two-terminal perovskite / crystalline silicon tandem batteries. In subsequent implementations, the thickness of the two-dimensional perovskite layer, the selection of inorganic and organic salts, and the adjustment of annealing conditions are all optimizable parameters to adapt to different application scenarios and battery design requirements. Furthermore, the fabrication process of this invention is simple and efficient, easily integrated with existing production lines, and shows good industrialization prospects. In summary, this invention, through its unique conformal buried interface passivation structure, effectively improves the photoelectric conversion efficiency of two-terminal perovskite tandem batteries, injecting new impetus into the research and development of high-efficiency tandem batteries.

[0059] Optionally, the thickness of the two-dimensional perovskite layer is 1 to 15 nm, and the two-dimensional perovskite layer includes a Rudsden-Bopper layered structure with an interlayer spacing of 1.45 to 1.60 nm and an optical band gap of 2.3 to 2.5 eV.

[0060] In this embodiment, the thickness of the two-dimensional perovskite layer is set to 1 to 15 nm. This layer adopts a Ruddlesden-Popper layered structure, with the interlayer spacing precisely controlled within the range of 1.45 to 1.60 nm, and the optical bandgap optimized to 2.3 to 2.5 eV. It is understood that the Ruddlesden–Popper (RP) layered structure is a type of two-dimensional / quasi-two-dimensional perovskite structure formed by alternating organic and inorganic layers, which can be widely used in superconductors, photovoltaics, and other fields. The interlayer spacing in this application can be the distance between organic or inorganic layers. By optimizing the thickness and structural parameters of the two-dimensional perovskite layer, it is possible to ensure efficient passivation at the buried interface between the perovskite light-absorbing layer and the hole transport layer, eliminating defects such as voids, while maintaining good energy level matching, which is beneficial for efficient carrier transport. The key to this design lies in the two-step fabrication of an n=1 two-dimensional perovskite layer. This layer not only completely covers the random pyramidal textured surface of the silicon substrate, including the buried depressions that are difficult to reach with traditional processes, but also achieves effective absorption of incident light and efficient extraction of charge carriers by adjusting the interlayer spacing and optical band gap, significantly improving the photoelectric conversion efficiency of the battery. During the fabrication process, the combination of inorganic salt evaporation and organic salt spin coating, as well as the settling time before organic salt spin coating, are crucial for forming a uniform and continuous passivation interface. This ensures complete passivation of the pyramidal textured surface, eliminates charge carrier recombination centers, improves open-circuit voltage and fill factor, and ultimately achieves a significant improvement in the performance of the tandem battery. Figure 2The IV curve comparison shown clearly demonstrates the improvement in device performance before and after implementing the present invention, confirming the effectiveness and superiority of the conformal stacked battery buried interface passivation structure.

[0061] Optionally, the thickness of the two-dimensional perovskite layer is 3 to 8 nm.

[0062] In this embodiment, the thickness of the two-dimensional perovskite layer is optimized to 3 to 8 nm. This thickness range is chosen to enhance its passivation effect at the perovskite buried interface while ensuring the conformability of the material, allowing it to uniformly cover the pyramidal textured surface of the silicon substrate, including buried recessed areas that are difficult to reach using conventional processes. By controlling the thickness of the two-dimensional perovskite layer, carrier recombination centers can be effectively reduced, shunt resistance can be improved, thereby improving the open-circuit voltage and fill factor of the perovskite / crystalline silicon tandem solar cell as a whole. The key to implementing this technical solution is ensuring the continuity and integrity of the film, eliminating interface defects caused by morphology mismatch, thereby optimizing energy level matching, promoting the effective transport and extraction of carriers, and significantly improving the photoelectric conversion efficiency of the tandem solar cell. In other embodiments not shown, the thickness of the two-dimensional perovskite layer can be further fine-tuned by adjusting the preparation process parameters of the inorganic salt and organic ammonium salt, such as evaporation rate, spin coating concentration, and settling time, to explore its numerical impact on cell performance.

[0063] Optionally, a conductive oxide layer is disposed between the first carrier transport layer and the bottom cell, and between the second carrier transport layer and the metal electrode layer. The material of the conductive oxide layer includes any one or more of indium tin oxide, fluorine-doped tin oxide, indium zinc oxide, and aluminum-doped zinc oxide.

[0064] Conductive oxide layers are provided between the first carrier transport layer and the bottom cell, and between the second carrier transport layer and the metal electrode layer. Indium tin oxide, fluorine-doped tin oxide, indium zinc oxide, or aluminum-doped zinc oxide are used as the conductive oxide layer materials. This configuration aims to optimize the charge transport path of the entire tandem cell, ensuring efficient charge transfer between layers while providing good physical contact and mechanical stability. The conductive oxide layers not only enhance the robustness of the overall cell structure but also effectively reduce contact resistance, promoting rapid charge extraction and thus improving the overall performance of the cell. In particular, the selection of these materials takes into account their compatibility with perovskite materials and other components, as well as their conformal deposition capabilities in complex structures, ensuring uniform coverage even in pyramidal textured structures, further enhancing charge collection efficiency and cell reliability.

[0065] In one embodiment, a buffer layer is disposed on the second carrier transport layer. The buffer layer is prepared by atomic layer deposition (ALD) technology. In this application, a conductive oxide layer can be prepared by PVD technology.

[0066] Figure 3 The changes in IV curves before and after the implementation of the present invention are shown. The buried interface passivation layer was prepared by using a combination of 20 nm PbI2 and 25 mg / mL PEAI. The comparative results show that the conformal passivation structure proposed in this invention significantly improves the quality of the perovskite buried interface, reduces non-radiative recombination loss caused by interface defects, and thus improves the open circuit voltage (Voc) and fill factor (FF), ultimately achieving an effective improvement in battery performance.

[0067] To achieve the above objectives, in accordance with another aspect of this application, referring to Figure 2 A method for preparing a solar cell is provided, the method comprising:

[0068] Step S100: Provide a bottom cell and form a first carrier transport layer on top of the bottom cell;

[0069] Step S200: A two-dimensional perovskite layer is formed on the first carrier transport layer, and the number of inorganic layers between every two adjacent organic layers in the two-dimensional perovskite layer is 1.

[0070] Step S300: A three-dimensional perovskite layer is formed on top of the two-dimensional perovskite layer;

[0071] Step S400: A second carrier transport layer is formed on top of the three-dimensional perovskite layer; the type of carriers transported by the second carrier transport layer is different from the type of carriers transported by the first carrier transport layer.

[0072] In step S500, a metal electrode layer is formed on the second carrier transport layer.

[0073] This application provides a method for fabricating a solar cell. The method involves sequentially depositing a first carrier transport layer, a conformal two-dimensional perovskite layer (n=1), a three-dimensional perovskite layer, and a second carrier transport layer on a base cell, and finally fabricating a metal electrode layer to construct a complete cell structure. The deposition of the two-dimensional perovskite layer achieves precise matching and coverage of the base cell surface structure, particularly forming a continuous and uniform passivation interface in the recessed areas of the pyramidal texture. This effectively solves the defects of the perovskite buried interface in traditional technologies, such as voids and incomplete coverage, thereby optimizing the energy level arrangement and enhancing carrier extraction efficiency. The different carriers transported by the second and first carrier transport layers ensure efficient separation and transport of carriers within the cell, improving the open-circuit voltage (Voc) and fill factor (FF), thus significantly improving the photoelectric conversion efficiency of the two-terminal perovskite / crystalline silicon tandem cell and solving the performance limitation problem caused by incomplete passivation in existing technologies.

[0074] Optionally, a two-dimensional perovskite layer is formed on top of the first carrier transport layer, including:

[0075] The two-dimensional perovskite layer is formed by depositing inorganic and organic salts on the first carrier transport layer in a two-step process, including:

[0076] An inorganic salt of a predetermined thickness is deposited on the first carrier transport layer; wherein the predetermined thickness is 1 to 30 nm.

[0077] An organic ammonium salt is spin-coated onto an inorganic salt using a first solvent of a preset concentration, and the organic ammonium salt is then annealed to form a two-dimensional perovskite layer; wherein the preset concentration is 10 to 30 mg / mL.

[0078] In this embodiment, a two-step process consisting of inorganic and organic salts is employed when forming a two-dimensional perovskite layer on top of the first carrier transport layer. First, an inorganic salt of a predetermined thickness, ranging from 1 to 30 nm, is vapor-deposited onto the first carrier transport layer. This step aims to provide a uniform base layer for subsequent organic salt deposition. In this application, the inorganic salts include lead(II) iodide (PbI2), lead(II) bromide (PbBr2), or lead(II) chloride (PbCl2). Next, an organic ammonium salt is spin-coated onto the inorganic salt layer using a first solvent of a predetermined concentration, followed by annealing. The concentration of the organic ammonium salt is controlled between 10 and 30 mg / mL. In this application, the first solvent can be isopropyl alcohol (IPA), and the organic ammonium salt includes PEAI, PEABr, or PEACl. This process generates a two-dimensional perovskite layer with n=1, which adheres tightly to the pyramidal textured surface of the silicon substrate, including buried interface regions that are difficult to reach with conventional processes, thus achieving a conformal passivation layer. The implementation of the two-step process, especially the setting time before organic salt spin coating and the selection of subsequent annealing temperature and time, is crucial to ensuring the quality of the two-dimensional perovskite layer. This conformal passivation structure eliminates defects such as pores at the perovskite buried interface, optimizes energy level matching, and thus enhances carrier extraction efficiency, improves the open-circuit voltage and fill factor of the cell, ultimately achieving the goal of improving the overall performance of the tandem cell. In specific implementation, the preset thickness of the inorganic salt and the preset concentration of the organic ammonium salt are key parameters, directly affecting the uniformity and integrity of the final passivation layer, and therefore require precise control. Furthermore, this process has wide applicability, not limited to specific inorganic or organic salts; the type of material and parameters can be adjusted according to actual needs to adapt to different types of silicon substrates and perovskite materials. Figure 3 The comparison of IV curves before and after implementation of the present invention shows that the performance of the battery is significantly improved after processing with 20nm PbI2+ and 25mg / mL PEAI, demonstrating the effectiveness and superiority of the technical solution of the present invention. Overall, the conformal tandem battery buried interface passivation structure and its preparation method proposed in this invention provide a new solution to the buried interface problem in perovskite-silicon tandem batteries, exhibiting significant innovation and practicality.

[0079] Optionally, before spin-coating the organic ammonium salt onto the inorganic salt, the method further includes:

[0080] The organic ammonium salt is dropped onto the inorganic salt and left to stand for a preset time, wherein the preset time is 5 to 30 seconds.

[0081] In this embodiment, an optimized two-step process is employed to prepare the perovskite buried interface passivation layer. First, an inorganic salt, such as PbI2, is deposited on the charge carrier transport layer using vapor deposition. Then, an organic ammonium salt, such as PEAI, dissolved in IPA solvent at a specific concentration, is spin-coated onto this inorganic salt layer. A settling process is introduced as a crucial step: the organic ammonium salt is dropped onto the inorganic salt and allowed to stand for a certain period before spin-coating. This design ensures sufficient reaction between the organic and inorganic salts, resulting in a uniform and continuous n=1 two-dimensional perovskite layer. The settling time, controlled between 5 and 30 seconds, is critical to the quality of the final passivation layer, directly affecting the coverage of the passivation material on complex surface structures. After meeting the required settling time, spin coating is performed. Then, the composite layer of inorganic and organic salts is placed on a hot plate for annealing at 100-150°C for 5-30 minutes. This process helps enhance the bonding between materials, forming a highly conformable passivation layer that covers the entire surface area, including the pyramidal-structured recessed bottom. Through this process, the present invention eliminates defects such as voids at the recessed bottom interface, optimizes energy level alignment, significantly improves the open-circuit voltage and fill factor of the battery, and thus improves the overall photoelectric conversion efficiency.

[0082] Optionally, a three-dimensional perovskite layer is formed on top of the two-dimensional perovskite layer, including:

[0083] The perovskite precursor solution was deposited onto a two-dimensional perovskite layer, and the perovskite precursor solution was subjected to a first-duration vacuum pumping treatment and a second-duration annealing treatment to obtain a three-dimensional perovskite layer.

[0084] In this embodiment, a three-dimensional perovskite layer is further deposited on top of the two-dimensional perovskite layer. Specifically, the perovskite precursor solution is deposited onto the formed two-dimensional perovskite layer. Then, a first-duration vacuum degassing process is performed on the precursor solution to remove air bubbles and improve film quality. Following this, a second-duration annealing process is performed to promote the crystallization of the three-dimensional perovskite layer, ultimately yielding the three-dimensional perovskite layer. This approach not only ensures the integrity of the perovskite material but also optimizes its photoelectric properties. By constructing a three-dimensional perovskite layer on top of the two-dimensional perovskite layer, an effective heterojunction structure is formed, improving band alignment and promoting efficient carrier transport and separation, thereby enhancing the overall photoelectric conversion efficiency of the device. This two-step fabrication strategy effectively solves the passivation problem of the perovskite buried interface, providing key technical support for the fabrication of high-performance perovskite-silicon tandem solar cells. In subsequent process steps, the stability and efficiency of the device were further enhanced by depositing an interface layer and a carrier transport layer. Finally, a buffer layer, a transparent conductive oxide layer, a metal electrode and an anti-reflection layer were prepared using advanced deposition technology to complete the construction of the entire battery and achieve a significant improvement in photoelectric conversion performance.

[0085] According to another aspect of this application, a buried interface passivation structure for a solar cell is provided for the aforementioned solar cell. The buried interface passivation structure includes a two-dimensional perovskite layer between a first carrier transport layer and a perovskite light-absorbing layer; wherein the number of inorganic layers between every two adjacent organic layers in the two-dimensional perovskite layer is 1.

[0086] According to another aspect of this application, a photovoltaic module is provided, including the aforementioned solar cell.

[0087] By applying the technical solution of this application, the buried interface prepared by the two-dimensional perovskite layer with one inorganic layer in the solar cell provided by this application has conformal properties. It can match the surface microstructure of the silicon substrate without changing the passivation effect, so as to achieve uniform coverage of the microstructure and improve the overall performance of the cell.

[0088] The solar cell and its fabrication method provided in this application will be described in detail below with specific embodiments:

[0089] Currently, perovskite / crystalline silicon tandem solar cells mainly employ a double-textured light-trapping structure, which involves simultaneously fabricating submicron or micron-scale random pyramidal textures on both the front and back sides of the silicon wafer. This double-sided optical microstructure design not only maintains high compatibility with existing crystalline silicon solar cell production lines but also significantly improves the current density of the tandem cell, thereby enhancing the overall conversion efficiency. However, the double-textured light-trapping structure introduces significant morphology compatibility challenges during perovskite thin film deposition. Due to the sharp geometric edges of the random pyramidal texture on the silicon wafer surface, it is difficult to uniformly cover the passivation material at the buried interface. This easily leads to pinhole defects and incomplete coverage during the perovskite precursor solution film deposition process. These defects directly increase carrier recombination centers and reduce shunt resistance, severely limiting the open-circuit voltage and fill factor of the device. Perovskite-crystalline silicon tandem solar cells suffer from poor buried interface conditions, and current passivation techniques cannot uniformly cover the pyramids.

[0090] In related technologies, in perovskite tandem solar cells at both ends, the presence of textured surface structure leads to numerous defects at the perovskite buried interface. At the same time, current processes cannot uniformly deposit passivating agent at the buried interface, making it difficult to passivate the defects at the buried interface.

[0091] This invention proposes a buried interface passivation structure, which involves inserting a two-dimensional perovskite layer (n=1) between the hole transport layer and the perovskite light-absorbing layer. This eliminates defects such as pores at the buried interface of the perovskite, while simultaneously forming a 2D / 3D heterojunction to optimize energy level matching and thus improve the photoelectric conversion efficiency of the perovskite solar cell. The conformal buried interface passivation structure of this invention possesses conformal properties, enabling complete matching of the surface microstructure of the silicon substrate without altering the passivation effect. Specifically, this passivation structure, through conformal deposition or conformal processing, establishes a continuous and uniform passivation interface across the entire surface area of ​​the pyramid texture—including buried depressions that are difficult to reach with traditional processes—thus fundamentally eliminating the interface passivation blind zone problem caused by the textured surface structure.

[0092] The method for preparing the buried interface in this invention is as follows:

[0093] Step 1: Treat the silicon-based solar cell with ultraviolet ozone for 15 minutes;

[0094] Step 2: Deposit the carrier transport layer onto the transparent conductive oxide layer;

[0095] Step 3 (Invention): Deposit 2D-PVSK material onto the carrier transport layer. The 2D-PVSK layer of this invention is prepared using a two-step method. First, an inorganic salt (PbI2, PbBr2, PbCl2, etc., thickness 1~30nm) is deposited on the carrier transport layer. Then, an organic ammonium salt (PEAI, PEACl, etc., solvent IPA, concentration 10~30mg / mL, standing for 5~30s before spin coating) is spin-coated onto the inorganic salt. After that, it is placed on a hot plate and annealed at 100~150℃ for 5~30min.

[0096] Step 4: Deposit the perovskite precursor solution onto the 2D-PVSK layer, place it in a vacuum pump to evacuate for 30 seconds, and then transfer it to a hot stage to anneal at 120°C for 10 minutes.

[0097] Step 4: Deposit the interface layer onto the perovskite layer;

[0098] Step 5: Deposit the charge carrier transport layer onto the interface layer;

[0099] Step Six: Prepare a buffer layer using atomic layer deposition (ALD) technology;

[0100] Step 7: Prepare a transparent conductive oxide layer using PVD technology;

[0101] Step 8: Prepare metal electrodes using vapor deposition technology;

[0102] Step 9: Prepare the antireflection layer using vapor deposition technology.

[0103] The film materials used in the structure of this device:

[0104] Transparent conductive layers include, but are not limited to, indium tin oxide (ITO), fluorine-doped tin oxide (FTO), indium zinc oxide (IZO), and aluminum-doped zinc oxide (AZO).

[0105] Carrier transport layer: Hole transport layer, including but not limited to NiOx, 2PACz, MeO-2PACz, Me-4PACz, 4PADCB, etc.;

[0106] Interface layer: including but not limited to LiF, MgF2, PEAI, PDAI, PI, PDI, etc.;

[0107] Carrier transport layer: Electron transport layer, including but not limited to PCBM, C60, etc.;

[0108] Antireflective layers: including but not limited to LiF, MgF2, PDMS, etc.

[0109] There are defects at the buried interface of the perovskite layer in the existing two-end stacked battery, and the existing passivation technology cannot uniformly cover the textured surface structure, resulting in incomplete passivation of the buried interface.

[0110] This invention proposes a conformally deposited 2D-PVSK structure as a passivation layer for the perovskite buried interface. The process involves first depositing an inorganic salt (PbI2, PbBr2, PbCl2, etc.), followed by spin-coating an organic salt (PEAI, PEABr, PEACl, etc.). This two-step reaction generates an n=1 two-dimensional perovskite layer that uniformly covers the pyramid structure, eliminating defects such as pores at the perovskite bottom interface and optimizing energy level arrangement to improve battery performance. In this application, the organic salt cation can also be BA+. The key to this invention is that the buried interface layer has a conformally deposited structure, suitable for textured pyramids, achieving complete passivation. Furthermore, the two-step process for preparing this passivation layer, along with the requirement for sufficient settling during organic salt spin-coating, ensures complete reaction between the organic and inorganic salts. Passivating the buried interface, eliminating interface defects, enhancing carrier extraction, and optimizing energy level arrangement improve Voc and FF, thereby enhancing the performance of the tandem battery.

[0111] It should be noted that the above are merely illustrative examples and do not specifically limit the structure or fabrication method of this solar cell.

[0112] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0113] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0114] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A solar cell, characterized in that, The solar cell includes: Bottom battery; A first carrier transport layer is disposed on top of the bottom battery; A two-dimensional perovskite layer is disposed above the first carrier transport layer; the number of inorganic layers between every two adjacent organic layers in the two-dimensional perovskite layer is 1. A three-dimensional perovskite layer is disposed on the two-dimensional perovskite layer; A second carrier transport layer is disposed on the three-dimensional perovskite layer; the type of carriers transported by the second carrier transport layer is different from the type of carriers transported by the first carrier transport layer. A metal electrode layer is disposed on the second carrier transport layer.

2. The solar cell according to claim 1, characterized in that, The two-dimensional perovskite layer comprises a compound represented by the general formula (A`)2BX4.

3. The solar cell according to claim 1, characterized in that, The thickness of the two-dimensional perovskite layer is 1 to 15 nm, and the two-dimensional perovskite layer includes a Rudsden-Bopper layered structure with an interlayer spacing of 1.45 to 1.60 nm and an optical band gap of 2.3 to 2.5 eV.

4. The solar cell according to claim 3, characterized in that, The thickness of the two-dimensional perovskite layer is 3 to 8 nm.

5. The solar cell according to claim 1, characterized in that, A conductive oxide layer is disposed between the first carrier transport layer and the bottom cell, and between the second carrier transport layer and the metal electrode layer. The material of the conductive oxide layer includes any one or more of indium tin oxide, fluorine-doped tin oxide, indium zinc oxide, and aluminum-doped zinc oxide.

6. A method for preparing a solar cell, characterized in that, The method includes: A bottom cell is provided, and a first carrier transport layer is formed on the bottom cell; A two-dimensional perovskite layer is formed on the first carrier transport layer, and the number of inorganic layers between every two adjacent organic layers in the two-dimensional perovskite layer is 1. A three-dimensional perovskite layer is formed on the two-dimensional perovskite layer; A second carrier transport layer is formed on top of the three-dimensional perovskite layer; the type of carriers transported by the second carrier transport layer is different from the type of carriers transported by the first carrier transport layer. A metal electrode layer is formed on top of the second carrier transport layer.

7. The method according to claim 6, characterized in that, The formation of a two-dimensional perovskite layer on top of the first carrier transport layer includes: The two-dimensional perovskite layer is formed by depositing inorganic and organic salts on the first carrier transport layer in a two-step process, including: An inorganic salt of a predetermined thickness is deposited on the first carrier transport layer; wherein the predetermined thickness is 1 to 30 nm. An organic ammonium salt is spin-coated onto the inorganic salt using a first solvent of a preset concentration, and the organic ammonium salt is then annealed to form the two-dimensional perovskite layer; wherein the preset concentration is 10 to 30 mg / mL.

8. The method according to claim 7, characterized in that, Before spin-coating the organic ammonium salt onto the inorganic salt, the method further includes: The organic ammonium salt is dropped onto the inorganic salt and left to stand for a preset time, wherein the preset time is 5 to 30 seconds.

9. The method according to claim 8, characterized in that, The formation of a three-dimensional perovskite layer on the two-dimensional perovskite layer includes: The perovskite precursor solution is deposited onto the two-dimensional perovskite layer, and the perovskite precursor solution is subjected to a first-duration vacuum pumping treatment and a second-duration annealing treatment to obtain the three-dimensional perovskite layer.

10. A photovoltaic module, characterized in that, The photovoltaic module includes a solar cell as described in any one of claims 1 to 5, or includes a solar cell prepared by the method described in any one of claims 6 to 9.

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