Perovskite / crystalline silicon laminated solar cell with novel composite layer and preparation method

Abstract

The invention discloses a perovskite / crystalline silicon laminated solar cell with a novel composite layer and a preparation method, the perovskite / crystalline silicon laminated solar cell comprises a perovskite top cell, a composite layer and a crystalline silicon bottom cell which are sequentially laminated, the composite layer is composed of an active metal layer and an active metal oxide layer, the active metal layer is in contact with the crystalline silicon bottom cell, the active metal oxide layer is in contact with the perovskite top cell, the active metal is selected from at least one of chromium, titanium, niobium and tantalum, and the thickness of the composite layer is less than 10nm. The novel middle composite layer is adopted and is composed of the specific active metal layer and the active metal oxide layer, the interface contact potential barrier and voltage loss are reduced and the open-circuit voltage is improved by optimizing energy band matching in the electrical level, and the optical parasitic absorption is remarkably reduced and the light current is improved by utilizing the ultrathin characteristic in the optical level; therefore, the photoelectric conversion efficiency of the cell is systematically improved.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a perovskite / crystalline silicon tandem solar cell with a novel composite layer and its preparation method. Background Technology

[0002] Perovskite / crystalline silicon tandem solar cells, by combining the high light absorption coefficient and tunable bandgap of perovskite materials with the mature process stability of crystalline silicon cells, hold promise for breaking the Shockley-Quiseur limit of single-junction cells and becoming an important direction for next-generation high-efficiency photovoltaic technology. Among these, the intermediate composite layer, as the key structure connecting the perovskite top cell and the crystalline silicon bottom cell, must simultaneously achieve efficient carrier recombination, high photon transmittance, and ohmic contact at the interface. Its performance directly determines the open-circuit voltage, fill factor, and overall efficiency of the tandem cell.

[0003] Currently, composite layer technology mainly relies on materials such as transparent conductive oxides (e.g., ITO, IZO) and doped polycrystalline silicon. While using TCO materials as composite layers offers high conductivity and light transmittance, it still faces several challenges: First, its refractive index mismatch with silicon solar cells results in light reflection losses in the near-infrared band above 800nm, limiting the absorption of long-wavelength light by the bottom cell. Second, the excessively high lateral conductivity of the TCO layer can exacerbate the lateral shunting effect of the top cell, hindering the fabrication of high-efficiency, large-area cells. Third, TCO materials, represented by ITO, rely on rare metals, which are scarce and expensive, severely restricting the large-scale industrialization of tandem solar cells. Fourth, in tandem structures based on TOPCon (tunneling oxide passivated contact) crystalline silicon bottom cells, using TCO as a composite layer may introduce reverse p / n junctions due to interface energy level mismatch, adversely affecting carrier transport.

[0004] On the other hand, doped polycrystalline silicon composite layers are another common approach, which utilizes heavily doped p-type silicon... + and n + Layer-based tunneling junctions theoretically solve the reverse p / n junction problem and achieve low-loss carrier tunneling recombination. However, this technology is complex and presents significant process challenges. For example, boron (B) and phosphorus (P) dopants readily interdiffusion at high temperatures, which not only disrupts the steep junction region, hindering the formation of high-quality ohmic contacts, but may also lead to increased interface defects. To address this issue, a complex two-step high-temperature annealing process is typically required. This significantly increases manufacturing costs and process uncertainty. Furthermore, the high-temperature process (up to 880°C) is completely incompatible with the processes used in perovskite materials and low-temperature sensitive bottom cells such as heterojunctions (HJTs), greatly limiting its application scope.

[0005] Therefore, developing a novel composite layer structure that combines high electrical performance, excellent optical properties, superior interface passivation effect, compatibility with low-temperature processes, and controllable cost has become a core issue that urgently needs to be addressed to promote the industrialization of perovskite / crystalline silicon tandem solar cells. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention aims to solve the technical problem of efficiency loss caused by large optical parasitic absorption, interface energy level mismatch and process damage in the intermediate composite layer of perovskite / crystalline silicon tandem solar cells.

[0007] To achieve the above objectives, the first aspect of the present invention provides a perovskite / crystalline silicon tandem solar cell with a novel composite layer, comprising a perovskite top cell, a composite layer, and a crystalline silicon bottom cell stacked sequentially. The composite layer is composed of an active metal layer and an active metal oxide layer. The active metal layer is in contact with the crystalline silicon bottom cell, and the active metal oxide layer is in contact with the perovskite top cell. The active metal is selected from at least one of chromium, titanium, niobium, and tantalum. The thickness of the composite layer is less than 10 nm.

[0008] The perovskite / crystalline silicon tandem solar cell of the present invention employs a novel intermediate composite layer, which is composed of a specific active metal layer and an active metal oxide layer. At the electrical level, the interface contact barrier and voltage loss are reduced by optimizing band matching, thereby increasing the open-circuit voltage. At the optical level, the ultra-thin characteristics are used to significantly reduce optical parasitic absorption and increase photocurrent, thereby systematically improving the photoelectric conversion efficiency of the cell.

[0009] Furthermore, the thickness of the active metal layer is 3-9 nm, and the thickness of the active metal oxide layer is 0.5-2 nm. The 3-9 nm active metal layer ensures both the continuity of the thin film and excellent conductivity, while minimizing light absorption loss; the 0.5-2 nm active metal oxide layer is sufficient to achieve effective surface passivation and ideal energy level adjustment, while ensuring efficient carrier tunneling. Too thick or too thin a layer will lead to degradation of electrical or optical performance.

[0010] Furthermore, the composite layer has a transmittance of over 80% in the 800-1200nm wavelength range. This ensures that most of the long-wavelength light used for power generation in crystalline silicon bottom cells can effectively penetrate the composite layer, greatly reducing optical losses common in tandem cells, thereby improving the short-circuit current density and photoelectric conversion efficiency of the cell.

[0011] Furthermore, the lateral resistivity of the composite layer is not less than 1×10⁻⁶. 3 Ω·cm. The composite layer has a high lateral resistivity, which effectively suppresses lateral leakage or shunting caused by local defects in the top cell, and is beneficial to improving the fill factor of the cell.

[0012] Furthermore, the perovskite top solar cell includes a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a buffer layer, and a transparent conductive oxide layer sequentially stacked on the active metal oxide layer. The hole transport layer is composed of a nickel oxide layer and a self-assembled monolayer sequentially stacked on the active metal oxide layer. The hole transport layer of the perovskite top solar cell adopts a stacked structure of nickel oxide and self-assembled monolayer. The nickel oxide, in conjunction with the novel composite layer, provides good hole injection and stability, while the self-assembled monolayer can finely control the interface energy levels, passivate surface defects, and improve the film quality of perovskite. The two work synergistically to significantly improve the open-circuit voltage and fill factor of the top solar cell.

[0013] Furthermore, the crystalline silicon bottom cell is a tunnel oxide passivated contact crystalline silicon cell. By combining the novel composite layer with the high-efficiency TOPCon crystalline silicon cell technology, the synergistic advantages of the two are fully utilized. The low-damage and high-transmittance characteristics of the composite layer perfectly match the extremely high requirements of TOPCon cells for surface passivation quality, thereby enabling the construction of stacked devices with higher conversion efficiency limits without compromising the excellent performance of the bottom cell.

[0014] A second aspect of the present invention provides a method for preparing the above-mentioned perovskite / crystalline silicon tandem solar cell with a novel composite layer, comprising the following steps: S1, providing a single-crystal silicon base cell; S2. An active metal layer is deposited on the crystalline silicon bottom cell using thermal evaporation or electron beam evaporation techniques; S3. By controlling oxidation, an active metal oxide layer is formed on the surface of the active metal layer to obtain a composite layer; S4. A perovskite top cell is fabricated on the composite layer.

[0015] This invention employs a low-damage evaporation deposition process to prepare the active metal layer, avoiding the damage to the bottom silicon cell, especially its delicate passivation layer, caused by high-energy particles during traditional magnetron sputtering TCO. This protects the intrinsic high performance of the bottom cell and provides a key process guarantee for obtaining high-efficiency stacked devices.

[0016] Furthermore, in step S2, the process conditions for depositing the active metal layer are: an evaporation rate of 0.1-0.5 Å / s and a vacuum degree below 5.0 × 10⁻⁶. -4 Controlling the evaporation rate and vacuum level is crucial for obtaining uniform, dense, and defect-free ultrathin metal films. This parameter range ensures good adhesion and an amorphous structure, laying the foundation for the subsequent formation of high-quality composite layers.

[0017] Furthermore, in step S3, the controlled oxidation is achieved through one of the following methods: exposure to a controlled oxygen-containing atmosphere for a predetermined time; thermal oxidation in an oxygen-containing atmosphere; plasma oxidation in a plasma environment containing oxygen or an oxygen-inert gas mixture; or ozone oxidation in an ozone atmosphere. Controlled oxidation can be achieved through various technical means. Whether it is mild natural oxidation, rapid thermal / plasma oxidation, or precise ozone oxidation, all can form an oxide layer with controllable thickness and stoichiometry and excellent performance on the metal surface while avoiding over-oxidation or damage.

[0018] Further, step S4 specifically includes: depositing a nickel oxide layer on the composite layer using magnetron sputtering technology; spin-coating a self-assembled monolayer solution onto the nickel oxide layer to obtain a hole transport layer; and sequentially depositing a perovskite light-absorbing layer, an electron transport layer, a buffer layer, and a top transparent conductive oxide layer on the hole transport layer. Combining the advantages of magnetron sputtering (for dense nickel oxide) and solution spin-coating (for self-assembled monolayers) ensures high-quality interfaces between functional layers and reproducible device structure fabrication. Simultaneously, the strong interaction between the composite layer and the crystalline silicon base cell and nickel oxide increases interfacial adhesion, ultimately improving the long-term stability of the perovskite / silicon tandem solar cell.

[0019] In summary, the present invention has the following beneficial effects: (1) Significantly reduce parasitic optical loss and increase current density: This invention uses an ultra-thin active metal / active metal oxide composite layer to replace the traditional transparent conductive oxide (TCO) composite layer, which greatly reduces the optical parasitic absorption of the intermediate composite layer in the near-infrared band, ensuring that a large number of long-wavelength photons can efficiently penetrate and reach the bottom crystalline silicon cell for full absorption and utilization, thereby significantly improving the short-circuit current density of the stacked cell and solving the core problem of photocurrent loss caused by light absorption of the composite layer.

[0020] (2) Achieving efficient carrier recombination and improving voltage and fill factor: The active metal and its oxide selected in this invention have suitable energy level structures, which can form excellent band matching with crystalline silicon bottom cells, effectively reducing the interface contact barrier; at the same time, the composite layer has a high lateral resistivity, which effectively suppresses lateral leakage and promotes efficient longitudinal tunneling and recombination of photogenerated carriers at the interface. This synergistic effect of electrical design directly translates into higher open-circuit voltage and fill factor, thereby improving the photoelectric conversion efficiency of the cell.

[0021] (3) Avoiding plasma damage and ensuring the performance and preparation yield of the bottom cell: This invention abandons the high-energy particle bombardment process of traditional magnetron sputtering TCO and innovatively adopts low-temperature and low-damage deposition technology such as thermal evaporation or electron beam evaporation to prepare the composite layer. This method fundamentally avoids plasma bombardment damage to the passivation layer of the crystalline silicon bottom cell and completely preserves the high intrinsic performance of the bottom cell. This mild process greatly improves the preparation yield and performance consistency of the stacked cell.

[0022] (4) Cost reduction and enhanced stability promote industrial application: This invention uses abundant and inexpensive active metals to replace scarce and expensive indium, which significantly reduces material costs and dependence on key resources, in line with the green and sustainable development strategy. At the same time, the strong interaction between the active metal and the upper and lower layer materials (silicon, nickel oxide) enhances the interfacial adhesion. Combined with the low-damage stable interface structure, it synergistically improves the long-term operational stability of perovskite / crystalline silicon tandem solar cells, laying the foundation for industrial application. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a perovskite / crystalline silicon tandem solar cell in a specific embodiment of the present invention.

[0024] Figure 2 The image shown is the XRD pattern of the composite layer in Embodiment 1 of the present invention. Figure 3 This is an XPS image of the composite layer in Embodiment 1 of the present invention.

[0025] Figure 4 The JV curves are for the perovskite / crystalline silicon tandem solar cells of Example 2 and Comparative Example 1 of the present invention.

[0026] Explanation of reference numerals in the attached figures: 1-Perovskite top cell, 11-Nickel oxide layer, 12-Self-assembled monolayer, 13-Perovskite light-absorbing layer, 14-Electron transport layer, 15-Buffer layer, 16-Transparent conductive oxide layer, 2-Composite layer, 21-Active metal layer, 22-Active metal oxide layer, 3-Crystalline silicon bottom cell, 31-Front-side passivation layer, 32-Silicon substrate, 33-Tunneling oxide layer, 34-Doped polycrystalline silicon layer, 35-Back-side passivation layer. Detailed Implementation

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0028] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0029] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art.

[0030] A specific embodiment of the present invention provides a perovskite / crystalline silicon tandem solar cell, the structure of which is as follows: Figure 1 As shown, the structure includes a perovskite top cell 1, a composite layer 2, and a crystalline silicon bottom cell 3, which are stacked sequentially. The composite layer 2 consists of an active metal layer 21 and an active metal oxide layer 22. The active metal layer 21 is in contact with the crystalline silicon bottom cell 3, and the active metal oxide layer 22 is in contact with the perovskite top cell 1.

[0031] This tandem solar cell inserts an ultrathin composite layer 2 composed of a specific active metal and its oxide between the perovskite top cell 1 and the crystalline silicon bottom cell 3. In specific implementations, the active metal is selected from at least one of chromium (Cr), titanium (Ti), niobium (Nb), and tantalum (Ta). The total thickness of the composite layer is less than 10 nm. This effectively solves the efficiency loss problem caused by large optical parasitic absorption, interface energy level mismatch, and process damage in traditional transparent conductive oxide composite layers, and achieves high photoelectric conversion efficiency.

[0032] Preferably, the thickness of the active metal layer 21 is 3-9 nm, and the thickness of the active metal oxide layer 22 is 0.5-2 nm. This thickness range is key to performance optimization: the 3-9 nm metal layer ensures film continuity and excellent conductivity while minimizing light absorption loss; the 0.5-2 nm oxide layer is sufficient to achieve effective surface passivation and energy level tuning, and ensures efficient carrier tunneling. This novel composite layer 2 has a transmittance of over 80% in the 800-1200 nm wavelength range, ensuring efficient utilization of near-infrared light by the crystalline silicon bottom cell; its lateral resistivity is not less than 1×10⁻⁶. 3 Ω·cm effectively suppresses lateral leakage current and improves the fill factor.

[0033] In some embodiments, the perovskite top solar cell 1 includes a hole transport layer, a perovskite light-absorbing layer 13, an electron transport layer 14, a buffer layer 15, and a transparent conductive oxide layer 16 sequentially stacked on a composite layer 2. The hole transport layer consists of a nickel oxide layer 11 directly deposited on the active metal oxide layer 22 and a self-assembled monolayer 12 (such as carbazole-based SAMs) spin-coated thereon. This stacked structure synergistically optimizes hole extraction, passivates interface defects, and improves the perovskite film quality. The transparent conductive oxide layer 16 needs to have high light transmittance and conductivity, and its front side has a metal positive electrode (not shown in the figure). The crystalline silicon bottom solar cell 3 has a metal back electrode (not shown in the figure) on its back side for collecting current and reflecting residual light waves.

[0034] In some embodiments, the crystalline silicon bottom cell 3 is a tunneling oxide passivated contact crystalline silicon cell, which includes, from the light-receiving surface to the back surface, a front passivation layer 31, a silicon substrate 32, a tunneling oxide layer 33, a doped polycrystalline silicon layer 34, and a back passivation layer 35. The silicon substrate 32 is n-type monocrystalline silicon; the front passivation layer 31 is a silicon oxide or aluminum oxide / silicon nitride stacked structure to reduce front surface recombination; the tunneling oxide layer 33 is a silicon oxide layer with a thickness of 1-2 nm, achieving excellent surface passivation; the doped polycrystalline silicon layer 34 is phosphorus / boron doped polycrystalline silicon, forming an ohmic contact with the metal back electrode; and the back passivation layer 35 is an aluminum oxide / silicon nitride stacked structure, providing passivation and anti-reflection functions.

[0035] The fabrication method of the above-mentioned perovskite / crystalline silicon tandem solar cell includes the following steps: S1, Provides a single-layer silicon base cell 3.

[0036] S2. An active metal layer 21 is deposited on the front passivation layer 31 using thermal evaporation or electron beam evaporation techniques. In a specific embodiment, the evaporation rate is controlled at 0.1-0.5 Å / s, and the vacuum level is below 5.0 × 10⁻⁶. -4 Pa.

[0037] S3. An active metal oxide layer 22 is formed on the surface of the active metal layer 21 by controlled oxidation, thus completing the preparation of the composite layer 2. In some embodiments, the controlled oxidation is performed by exposure to a controlled oxygen-containing atmosphere for a predetermined time; in other embodiments, the controlled oxidation is performed by thermal oxidation in an oxygen-containing atmosphere at 100°C to 300°C; in other embodiments, the controlled oxidation is performed by plasma oxidation in a plasma environment of oxygen or an oxygen-inert gas mixture; in other embodiments, the controlled oxidation is performed by ozone oxidation in an ozone atmosphere.

[0038] S4. On the composite layer 2, a nickel oxide layer 11, a self-assembled monolayer 12, a perovskite light-absorbing layer 13, an electron transport layer 14, a buffer layer 15, and a transparent conductive oxide layer 16 are deposited sequentially to complete the device fabrication.

[0039] This invention provides a reliable technical solution for preparing high-efficiency, stable, and low-cost perovskite / crystalline silicon tandem solar cells by introducing a novel composite layer structure and combining it with a low-damage fabrication process.

[0040] The technical solution and effects of the present invention will be illustrated below with specific embodiments.

[0041] Example 1 This embodiment describes the fabrication of a perovskite / crystalline silicon tandem solar cell based on a chromium / chromium oxide composite layer. The specific steps are as follows: (1) Preparation of crystalline silicon bottom cell: Provide an n-type TOPCon crystalline silicon bottom cell with a silicon oxide / silicon nitride stacked passivation anti-reflection structure on the front side.

[0042] (2) Deposition of the active metal layer: The cleaned crystalline silicon bottom cell is placed in the chamber of a high-vacuum electron beam evaporation coating machine. The vacuum level of the chamber is evacuated to below 5.0 × 10⁻⁶. -4 After Pa, an electron beam evaporation technique was used to deposit a 6 nm thick chromium (Cr) thin film on the front side of the crystalline silicon bottom cell at a rate of 0.3 Å / s to form an active metal layer.

[0043] (3) Controlled oxidation to form a composite layer: After chromium film deposition, high-purity oxygen was introduced into the chamber to maintain the pressure at 1.0 Pa for 100 minutes, allowing the chromium film surface to oxidize naturally, forming a chromium oxide (Cr2O3) film with a thickness of approximately 1 nm, thus obtaining a chromium / chromium oxide composite layer. The composite layer was characterized, and X-ray diffraction (XRD) results showed that ( Figure 2 The prepared chromium film has an amorphous structure; X-ray photoelectron spectroscopy (XPS) test results ( Figure 3 This confirms that the chromium film surface was successfully oxidized to chromium oxide.

[0044] (4) Preparation of hole transport layer: A 15 nm thick layer of nickel oxide (NiO) was deposited on the composite layer using magnetron sputtering technology. x The sample was then transferred to a glove box, and a 1 mg / mL carbazole-based self-assembled monolayer (SAMs) ethanol solution was spin-coated onto its surface. The mixture was then annealed at 100°C for 10 minutes to form a complete hole transport layer (NiO). x / SAMs).

[0045] (5) Preparation of perovskite light-absorbing layer: A perovskite precursor solution is spin-coated onto the hole transport layer, and after annealing and crystallization, a perovskite light-absorbing layer with a thickness of about 500 nm is formed.

[0046] (6) Preparation of electron transport layer and buffer layer: A 20 nm thick fullerene layer was sequentially deposited on the perovskite layer as an electron transport layer using thermal evaporation technology. Subsequently, a 20 nm thick tin oxide layer was prepared on the electron transport layer as a buffer layer using atomic layer deposition (ALD) technology.

[0047] (7) Preparation of transparent conductive oxide layer: A 40 nm thick layer of indium tin oxide (ITO) was deposited on the buffer layer as a transparent conductive oxide layer using magnetron sputtering technology.

[0048] (8) Electrode fabrication and packaging: Metal electrodes were fabricated on the front side of the perovskite top cell and the back side of the crystalline silicon bottom cell by thermal evaporation. Finally, the complete tandem cell device was packaged under a nitrogen atmosphere.

[0049] Example 2 This embodiment describes the fabrication of a perovskite / crystalline silicon tandem solar cell based on a chromium / chromium oxide composite layer. The specific steps are as follows: (1) Preparation of crystalline silicon bottom cell: Provide the same n-type TOPCon crystalline silicon bottom cell as in Example 1.

[0050] (2) Deposition of the active metal layer: The cleaned crystalline silicon bottom cell is placed in the chamber of a high-vacuum electron beam evaporation coating machine. The vacuum level of the chamber is evacuated to below 5.0 × 10⁻⁶. -4 After Pa, an 8 nm thick chromium film was deposited on the front side of the crystalline silicon bottom cell using electron beam evaporation technology at a rate of 0.2 Å / s to form an active metal layer.

[0051] (3) Controllable oxidation to form a composite layer: After the chromium film deposition is completed, without breaking the vacuum, the sample stage is heated to 150°C and high-purity oxygen is introduced into the chamber to maintain the pressure at 5.0 Pa for 10 minutes. Thermal oxidation treatment is then performed to form a chromium oxide film with a thickness of about 1.5 nm, thus obtaining a chromium / chromium oxide composite layer.

[0052] The subsequent steps are the same as steps (4)-(8) in Example 1, to obtain perovskite / crystalline silicon tandem solar cells.

[0053] Example 3 This embodiment describes the fabrication of a perovskite / crystalline silicon tandem solar cell based on a titanium / titanium oxide composite layer. The specific steps are as follows: (1) Preparation of crystalline silicon bottom cell: Provide the same n-type TOPCon crystalline silicon bottom cell as in Example 1.

[0054] (2) Deposition of the active metal layer: The cleaned crystalline silicon bottom cell is placed in the chamber of a high-vacuum electron beam evaporation coating machine. The vacuum level of the chamber is evacuated to below 5.0 × 10⁻⁶. -4After Pa, an electron beam evaporation technique was used to deposit a 4 nm thick titanium (Ti) thin film on the front side of the crystalline silicon bottom cell at a rate of 0.4 Å / s to form an active metal layer.

[0055] (3) Controllable oxidation to form a composite layer: After the titanium film deposition is completed, without breaking the vacuum, the sample stage is heated to 200°C and high-purity oxygen is introduced into the chamber to maintain the pressure at 2.0 Pa for 5 minutes. Thermal oxidation treatment is then performed to form a titanium dioxide (TiO2) film with a thickness of about 1 nm, thus obtaining a titanium / titanium oxide composite layer.

[0056] The subsequent steps are the same as steps (4)-(8) in Example 1, to obtain perovskite / crystalline silicon tandem solar cells.

[0057] Example 4 This embodiment describes the fabrication of a perovskite / crystalline silicon tandem solar cell based on a niobium / niobium oxide composite layer. The specific steps are as follows: (1) Preparation of crystalline silicon bottom cell: Provide the same n-type TOPCon crystalline silicon bottom cell as in Example 1.

[0058] (2) Deposition of active metal layer: The cleaned crystalline silicon bottom cell is placed in the chamber of a high-vacuum thermal evaporation coating machine, and the vacuum degree of the chamber is evacuated to below 5.0 × 10⁻⁶. -4 After Pa, a 6 nm thick niobium (Nb) thin film was deposited on the front side of the crystalline silicon bottom cell at a rate of 0.1 Å / s using thermal evaporation technology to form an active metal layer.

[0059] (3) Controllable oxidation to form a composite layer: After the niobium film deposition is completed, without breaking the vacuum, the sample stage is heated to 280°C and high-purity oxygen is introduced into the chamber to maintain the pressure at 3.0 Pa for 15 minutes. Thermal oxidation treatment is then performed to form a niobium pentoxide (Nb2O5) film with a thickness of about 1.2 nm, thus obtaining a niobium / niobium oxide composite layer.

[0060] The subsequent steps are the same as steps (4)-(8) in Example 1, to obtain perovskite / crystalline silicon tandem solar cells.

[0061] Example 5 This embodiment describes the fabrication of a perovskite / crystalline silicon tandem solar cell based on a tantalum / tantalum oxide composite layer. The specific steps are as follows: (1) Preparation of crystalline silicon bottom cell: Provide the same n-type TOPCon crystalline silicon bottom cell as in Example 1.

[0062] (2) Deposition of active metal layer: The cleaned crystalline silicon bottom cell is placed in the chamber of a high-vacuum electron beam evaporation coating machine. The vacuum level of the chamber is evacuated to below 8.0 × 10⁻⁶. -5After Pa, an electron beam evaporation technique was used to deposit a 5 nm thick tantalum (Ta) film on the front side of the crystalline silicon bottom cell at a rate of 0.15 Å / s to form an active metal layer.

[0063] (3) Controllable oxidation to form a composite layer: After the tantalum film deposition is completed, the sample is placed in an ozone generator and exposed to a high concentration of ozone environment at room temperature for 10 minutes to perform ozone oxidation treatment, forming a tantalum pentoxide (Ta2O5) film with a thickness of about 2nm, and obtaining a tantalum / tantalum oxide composite layer.

[0064] The subsequent steps are the same as steps (4)-(8) in Example 1, to obtain perovskite / crystalline silicon tandem solar cells.

[0065] Comparative Example 1 This comparative example demonstrates the fabrication of a perovskite / crystalline silicon tandem solar cell based on an indium oxide-doped zinc oxide (IZO) composite layer. The specific steps are as follows: (1) Preparation of crystalline silicon bottom cell: Provide the same n-type TOPCon crystalline silicon bottom cell as in Example 1.

[0066] (2) Deposition of IZO composite layer: The cleaned crystalline silicon bottom cell is placed in the chamber of the magnetron sputtering coating machine. The chamber is evacuated to 5.0 × 10⁻⁶. -3 After Pa, a mixture of argon and oxygen gas is introduced to maintain the working pressure at 0.5 Pa. Subsequently, at room temperature, using an IZO ceramic target, a 10 nm thick IZO thin film is deposited on the front side of the silicon wafer using radio frequency magnetron sputtering technology as a composite layer.

[0067] The subsequent steps are the same as steps (4)-(8) in Example 1, to obtain perovskite / crystalline silicon tandem solar cells.

[0068] Current density-voltage (JV) tests were performed on the perovskite / crystalline silicon tandem solar cells prepared in Example 2 and Comparative Example 1, and the results are as follows: Figure 4 As shown in Table 1, the perovskite / crystalline silicon tandem solar cells based on the chromium / chromium oxide composite layer exhibit higher photoelectric conversion efficiency, with significantly improved open-circuit voltage and fill factor.

[0069] Table 1 Performance parameters of perovskite / crystalline silicon tandem solar cells in Example 2 and Comparative Example 1 Comparative Example 2 This comparative example prepares a perovskite / crystalline silicon tandem solar cell based on a tantalum composite layer. The difference from Example 1 is that step (3) is omitted. After depositing the metallic chromium layer, no oxidation treatment is performed, and subsequent hole transport layer preparation is carried out directly. In the prepared perovskite / crystalline silicon tandem solar cell, the hole transport layer of the perovskite top cell is in direct contact with the metallic chromium layer.

[0070] Comparative Example 3 This comparative example prepares a perovskite / crystalline silicon tandem solar cell based on a chromium / chromium oxide composite layer. The difference from Example 1 is that the deposition of the nickel oxide layer in step (4) is omitted. After the composite layer is prepared, a self-assembled monolayer solution is directly spin-coated onto it, followed by the preparation of the perovskite light-absorbing layer, etc. In the resulting perovskite / crystalline silicon tandem solar cell, the hole transport layer of the perovskite top cell is only a single self-assembled monolayer, which is in direct contact with the active metal oxide layer of the composite layer.

[0071] Comparative Example 4 This comparative example prepares a perovskite / crystalline silicon tandem solar cell based on a chromium / chromium oxide composite layer. The difference from Example 1 is that the oxidation time in step (3) is extended, so that the thickness of the chromium oxide layer reaches about 6 nm.

[0072] Comparative Example 5 This comparative example prepares a perovskite / crystalline silicon tandem solar cell based on a chromium / chromium oxide composite layer. The difference from Example 1 is that the deposition parameters in step (2) are adjusted to deposit a chromium metal layer with a thickness of about 20 nm at a higher evaporation rate, followed by oxidation to form a chromium oxide layer of about 3 nm.

[0073] Performance tests were conducted on the perovskite / crystalline silicon tandem solar cells prepared in each embodiment and comparative example. The results are shown in Table 2. The results indicate that the perovskite / crystalline silicon tandem solar cells with novel composite layers prepared using the technology of this invention maintain a stable photoelectric conversion efficiency of 32.75% to 33.53%, significantly higher than Comparative Example 1 (IZO, 31.53%). This demonstrates that the core structure of the active metal / metal oxide composite layer proposed in this invention can systematically improve cell performance. The open-circuit voltage and fill factor of Comparative Example 1 are also significantly lower than all other embodiments, verifying the decisive advantages of this invention in avoiding plasma damage and suppressing lateral leakage. Comparative Example 2 demonstrates that the active metal oxide layer is crucial for forming good ohmic contacts and improving device performance. Comparative Example 3 demonstrates that the nickel oxide layer is an indispensable part of the efficient hole transport layer, and its absence leads to device malfunction. Comparative Example 4 demonstrates that controlling the oxide layer thickness within a limited range is key to ensuring low-resistance tunneling; excessive thickness leads to a significant decrease in the fill factor. Comparative Example 5 demonstrates that controlling the total thickness of the composite layer to below 10 nm is the basis for minimizing optical loss and ensuring current density.

[0074] Table 2 Performance parameters of perovskite / crystalline silicon tandem solar cells in Examples 1-5 and Comparative Examples 1-5 While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the scope of protection of this invention.

Claims

1. A perovskite / crystalline silicon tandem solar cell with a novel composite layer, characterized in that, The device includes a perovskite top cell, a composite layer, and a crystalline silicon bottom cell stacked sequentially. The composite layer consists of an active metal layer and an active metal oxide layer. The active metal layer is in contact with the crystalline silicon bottom cell, and the active metal oxide layer is in contact with the perovskite top cell. The active metal is selected from at least one of chromium, titanium, niobium, and tantalum. The thickness of the composite layer is less than 10 nm.

2. The perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that, The thickness of the active metal layer is 3-9 nm, and the thickness of the active metal oxide layer is 0.5-2 nm.

3. The perovskite / crystalline silicon tandem solar cell according to claim 2, characterized in that, The composite layer has a transmittance of over 80% in the wavelength range of 800-1200nm.

4. The perovskite / crystalline silicon tandem solar cell according to claim 2, characterized in that, The transverse resistivity of the composite layer is not less than 1×10⁻⁶. 3 Ω·cm.

5. The perovskite / crystalline silicon tandem solar cell according to any one of claims 1-4, characterized in that, The perovskite top solar cell includes a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a buffer layer, and a transparent conductive oxide layer sequentially stacked on the active metal oxide layer. The hole transport layer is composed of a nickel oxide layer and a self-assembled monolayer sequentially stacked on the active metal oxide layer.

6. The perovskite / crystalline silicon tandem solar cell according to claim 5, characterized in that, The crystalline silicon bottom cell is a tunnel oxide passivated contact crystalline silicon cell.

7. A method for preparing a perovskite / crystalline silicon tandem solar cell with a novel composite layer as described in any one of claims 1-6, characterized in that, Includes the following steps: S1, providing a single-crystal silicon base cell; S2. An active metal layer is deposited on the crystalline silicon bottom cell using thermal evaporation or electron beam evaporation techniques; S3. By controlling oxidation, an active metal oxide layer is formed on the surface of the active metal layer to obtain a composite layer; S4. A perovskite top cell is fabricated on the composite layer.

8. The preparation method according to claim 7, characterized in that, In step S2, the process conditions for depositing the active metal layer are: an evaporation rate of 0.1-0.5 Å / s and a vacuum level below 5.0 × 10⁻⁶. -4 Pa.

9. The preparation method according to claim 7, characterized in that, In step S3, the controllable oxidation is achieved by one of the following methods: exposure to a controlled oxygen-containing atmosphere for a predetermined time; thermal oxidation in an oxygen-containing atmosphere; plasma oxidation in a plasma environment of oxygen or an oxygen-inert gas mixture; or ozone oxidation in an ozone atmosphere.

10. The preparation method according to claim 7, characterized in that, Step S4 specifically includes: depositing a nickel oxide layer on the composite layer using magnetron sputtering technology, spin-coating a self-assembled monolayer solution on the nickel oxide layer to obtain a hole transport layer; and sequentially depositing a perovskite light-absorbing layer, an electron transport layer, a buffer layer, and a top transparent conductive oxide layer on the hole transport layer.

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