Optically matched and sputter-damage tandem solar cells and their fabrication method

Abstract

This application relates to the field of solar cell fabrication technology, specifically disclosing an optically matched and sputter-damage-resistant tandem solar cell and its fabrication method. This optically matched and sputter-damage-resistant tandem solar cell includes a wide bandgap top cell, an intermediate connecting structure, and a narrow bandgap bottom cell stacked sequentially from the light-receiving side to the back-lighting side. The intermediate connecting structure includes a light-coupled buffer layer, a dense protective layer, and a transparent conductive tunneling layer stacked sequentially from the wide bandgap top cell side to the narrow bandgap bottom cell side. The light-coupled buffer layer is a composite material of an organic matrix doped with high-refractive-index nanoparticles. This application employs a three-layer intermediate connecting structure consisting of a light-coupled buffer layer, a dense protective layer, and a transparent conductive tunneling layer. By adjusting the refractive index of the light-coupled buffer layer to the range of 1.8-2.2 and ensuring that the absolute value of the refractive index difference between the buffer layer and the top cell's light-absorbing layer is ≤0.3, the open-circuit voltage and short-circuit current density of the tandem solar cell are improved.

Description

Technical Field

[0001] This application relates to the field of solar cell fabrication technology, and more specifically, to optically matched and sputter-damage-resistant tandem solar cells and their fabrication methods. Background Technology

[0002] With the accelerated pace of global energy structure transformation, photovoltaic technology has become a key research focus in the new energy field due to its clean and renewable advantages. Metal halide perovskite solar cells have attracted widespread attention due to their high photoelectric conversion efficiency, low manufacturing cost, and good process compatibility. To break through the theoretical efficiency limit of single-junction perovskite cells, constructing all-perovskite tandem cells with a wide bandgap top cell and a narrow bandgap bottom cell in series has become a key technical path to improve device performance.

[0003] In tandem solar cell technologies, the intermediate connection structure between the top and bottom cells plays a crucial role, requiring the simultaneous achievement of efficient carrier tunneling and recombination and high-transmittance long-wavelength light transmission. Existing technologies typically use transparent conductive oxide thin films prepared by magnetron sputtering as the core component. To mitigate the bombardment damage of high-energy sputtered particles to the perovskite layer of the top cell, an organic buffer layer is added between the two, with the thickness of this layer attempting to block particle penetration.

[0004] However, the organic buffer layer is formed by intermolecular van der Waals forces, resulting in low film density and pinhole defects. High-energy plasma ions can still penetrate the buffer layer, bombard the perovskite layer surface, break the crystal chemical bonds, introduce a large number of deep-level defects, increase the probability of nonradiative recombination, and cause the open-circuit voltage of the tandem cell to be significantly lower than the sum of the voltages of the single-junction cell. Summary of the Invention

[0005] To address the problem that the open-circuit voltage of existing tandem solar cells is significantly lower than the sum of the voltages of single-junction cells, this application provides an optically matched and sputter-damage-resistant tandem solar cell and its manufacturing method.

[0006] The optically matched and sputter-damage-resistant tandem solar cell and its fabrication method provided in this application adopt the following technical solution: In a first aspect, this application provides an optically matched and sputter-damage-resistant tandem solar cell, employing the following technical solution: An optically matched and sputter-damage tandem solar cell comprising a wide bandgap top cell, an intermediate connecting structure, and a narrow bandgap bottom cell stacked sequentially from the light-receiving side to the back-lighting side; The intermediate connection structure includes an optical coupling buffer layer, a dense protective layer, and a transparent conductive tunneling layer, which are stacked sequentially from the wide bandgap top cell side to the narrow bandgap bottom cell side. The optical coupling buffer layer is a composite material of organic matrix doped with high refractive index nanoparticles, with a refractive index of 1.8-2.2 and an absolute value of the refractive index difference with the top cell light-absorbing layer ≤0.3. The dense protective layer is a metal oxide thin film prepared by low-temperature atomic layer deposition, with a thickness of 5-30 nm and a density greater than 90%. The transparent conductive tunneling layer is a transparent conductive oxide thin film prepared by magnetron sputtering. In the intermediate connection structure, the refractive indices of the optical coupling buffer layer, the dense protective layer, and the transparent conductive tunneling layer satisfy a gradient decreasing relationship. ,in The refractive index of the top cell light-absorbing layer The refractive index of the optical coupling buffer layer, For the refractive index of the dense protective layer, The refractive index of the transparent conductive tunneling layer.

[0007] By adopting the above technical solution, a three-layer intermediate connection structure consisting of a light coupling buffer layer, a dense protective layer, and a transparent conductive tunneling layer is used. By adjusting the refractive index of the light coupling buffer layer to the range of 1.8-2.2 and ensuring that the absolute value of the refractive index difference between it and the light-absorbing layer of the top cell is ≤0.3, a distribution structure with decreasing refractive index gradients is constructed for each layer. Furthermore, a dense protective layer with a thickness of 5-30 nm and a density greater than 90% is prepared by low-temperature atomic layer deposition. Therefore, it can not only block high-energy ion bombardment during magnetron sputtering, reduce the chemical bond breakage and deep-level defect generation of the perovskite layer of the top cell, and reduce the probability of nonradiative recombination, but also reduce interlayer light reflection and improve the transmission efficiency of long-wavelength light. This results in an increase in the open-circuit voltage and short-circuit current density of the tandem solar cell, solving the problem that the open-circuit voltage of the tandem solar cell is significantly lower than the sum of the voltages of the single-junction cells in existing tandem solar cells.

[0008] Preferably, the organic matrix of the optical coupling buffer layer is selected from at least one of fullerene and its derivatives, polythiophene derivatives or long-chain organic ammonium salts, and the high refractive index nanoparticles are selected from at least one of titanium dioxide, zirconium dioxide, zinc sulfide or quantum dot materials and have an average particle size of less than 10 nm. The mass ratio of the organic matrix to the high refractive index nanoparticles is 0.5-2:1.

[0009] By adopting the above technical solution, the good compatibility between organic matrix and high refractive index nanoparticles can be utilized. The limited mass ratio can achieve uniform dispersion of nanoparticles in organic matrix, stably control the refractive index of the optical coupling buffer layer within the set range, improve the interface smoothness and physical buffering performance of the film, and enhance the synergistic effect of optical matching and damage resistance.

[0010] Preferably, the thickness of the optical coupling buffer layer satisfies the optical destructive interference condition. Where λ is the center wavelength of the transmission spectrum of the top cell, and k is a non-negative integer. The thickness of the optical coupling buffer layer is given.

[0011] By adopting the above technical solution, the interface light reflection loss is further offset by the optical destructive interference effect, the transmission efficiency of long wavelength light to the narrow bandgap bottom cell is improved, the optical matching performance of the intermediate connection structure is enhanced, and the short-circuit current density of the stacked cell is increased.

[0012] Preferably, the material of the dense protective layer is selected from at least one of tin dioxide, zinc oxide, or aluminum oxide.

[0013] By adopting the above technical solution and utilizing metal oxide materials adapted to low-temperature atomic layer deposition process, a high-density, pinhole-free protective film can be formed without damaging the underlying perovskite layer. This film effectively blocks the bombardment of high-energy ions from magnetron sputtering, improving resistance to sputtering damage while maintaining good light transmittance.

[0014] Preferably, the material of the transparent conductive tunneling layer is selected from at least one of indium tin oxide, indium zinc oxide, aluminum-doped zinc oxide, or fluorine-doped tin oxide.

[0015] By adopting the above technical solution, the transparent conductive oxide material has both high conductivity and high light transmittance, which is suitable for the preparation requirements of magnetron sputtering process. This can ensure efficient carrier tunneling recombination between the wide bandgap top cell and the narrow bandgap bottom cell, while not affecting the transmission efficiency of long wavelength light.

[0016] Preferably, the wide-bandgap top cell comprises a transparent electrode, an electron transport layer, a wide-bandgap perovskite light-absorbing layer, and a hole transport layer stacked sequentially. The transparent electrode is indium tin oxide or fluorine-doped tin oxide conductive glass, the electron transport layer is a tin dioxide thin film, the wide-bandgap perovskite light-absorbing layer is a lead bromide cesium iodide thin film, and the hole transport layer is a polytriarylamine thin film. The narrow bandgap bottom cell includes a hole transport layer, a narrow bandgap perovskite light-absorbing layer, an electron transport layer, and a back electrode stacked sequentially. The hole transport layer is a poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate film, the narrow bandgap perovskite light-absorbing layer is an iodine-tin-lead-cesium film, the electron transport layer is a fullerene derivative film, and the back electrode is a metallic silver electrode.

[0017] By adopting the above technical solution, the clear combination of top and bottom battery layered materials can optimize the photoelectric conversion performance of each sub-cell, form a highly efficient synergy with the intermediate connection structure, reduce the recombination loss of charge carriers at the interface, and improve the overall photoelectric performance of the tandem battery.

[0018] Secondly, this application provides a method for manufacturing an optically matched and sputter-damage-resistant tandem solar cell, employing the following technical solution: A method for fabricating an optically matched and sputter-damage-resistant tandem solar cell, applicable to the aforementioned optically matched and sputter-damage-resistant tandem solar cell, includes the following steps: S1. The conductive glass substrate is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 13-17 min each, dried at 110-130℃ for 25-35 min, and then surface activated by UV-ozone treatment for 25-35 min. Subsequently, a wide-bandgap top cell is prepared on the activated conductive glass substrate. S2. Prepare a composite precursor ink of organic matrix and high refractive index nanoparticles, and deposit an optical coupling buffer layer on the surface of wide bandgap top cell through a coating process. S3. A dense protective layer is grown on the surface of the optical coupling buffer layer using atomic layer deposition at a temperature ≤110℃. S4. A transparent conductive tunneling layer is deposited on the surface of a dense protective layer using a magnetron sputtering process; S5. Narrow bandgap bottom cells are fabricated on the surface of a transparent conductive tunneling layer; S6. The prepared tandem battery is encapsulated to complete the preparation.

[0019] By adopting the above technical solutions and coordinating the various process steps, the entire low-temperature process system avoids thermal damage to the perovskite layer. The combination of coating, atomic layer deposition and magnetron sputtering processes is well-suited to the needs of large-area fabrication, ensuring the performance consistency of the tandem solar cells.

[0020] Preferably, in step S2, the coating process of the composite precursor ink is a spin coating process, with a spin coating speed of 1500-2500 rpm, a spin coating time of 20-40 s, and annealing at 70-90℃ for 3-8 min after coating.

[0021] By adopting the above technical solution, the thickness and uniformity of the optical coupling buffer layer can be controlled by using spin coating parameters and annealing conditions, ensuring that its refractive index is stable within the design range, and ensuring the reliable realization of optical matching and physical buffering effects.

[0022] Preferably, in step S3, the precursor pulse time of the atomic layer deposition process is 0.05-0.2s, the purging time is 5-15s, and the deposition cycle number is 50-300 times.

[0023] By adopting the above technical solution, the thickness of the dense protective layer can be controlled and adjusted through process parameters, ensuring that the film density meets the design requirements. While playing an anti-sputtering protection role, it will not affect the light transmission and carrier transport efficiency.

[0024] Preferably, in step S4, the argon atmosphere pressure of the magnetron sputtering process is 0.3-0.8 Pa, the sputtering power is 80-120 W, and the deposition time is 3-10 min.

[0025] By adopting the above technical solution, using argon atmosphere pressure, sputtering power and deposition time, the film quality of the transparent conductive tunneling layer can be controlled, taking into account both high conductivity and high light transmittance. At the same time, it works synergistically with the dense protective layer to avoid damage to the perovskite layer of the top cell by high-energy ions during sputtering.

[0026] In summary, this application has the following beneficial effects: 1. This application employs a three-layer intermediate connection structure consisting of a light-coupled buffer layer, a dense protective layer, and a transparent conductive tunneling layer. By adjusting the refractive index of the light-coupled buffer layer to the range of 1.8-2.2 and ensuring that the absolute value of the refractive index difference between it and the top cell light-absorbing layer is ≤0.3, a distribution structure with decreasing refractive index gradients is constructed for each layer. Furthermore, a dense protective layer with a thickness of 5-30 nm and a density greater than 90% is prepared using low-temperature atomic layer deposition. Therefore, it can both block high-energy ion bombardment during magnetron sputtering, reduce the chemical bond breakage and deep-level defect generation of the perovskite layer of the top cell, and reduce the probability of non-radiative recombination, and reduce interlayer light reflection, thereby improving the transmission efficiency of long-wavelength light. This results in an increase in the open-circuit voltage and short-circuit current density of the tandem solar cell, solving the problem that the open-circuit voltage of the tandem solar cell is significantly lower than the sum of the voltages of the single-junction cells in existing tandem solar cells.

[0027] 2. This application adjusts the refractive index of the optical coupling buffer layer to the range of 1.8-2.2 and constructs a refractive index gradient decreasing structure consisting of a top cell light-absorbing layer, an optical coupling buffer layer, a dense protective layer, and a transparent conductive tunneling layer. This minimizes interlayer Fresnel reflection. At the same time, combined with the optical destructive interference thickness design of the optical coupling buffer layer, the transmission efficiency of long-wavelength light is further improved, allowing more long-wavelength light to be absorbed by the narrow bandgap bottom cell, thereby increasing the short-circuit current density of the tandem cell. This effectively improves the short-circuit current density of the tandem solar cell and achieves efficient utilization of the entire spectrum.

[0028] 3. The dense metal oxide protective layer prepared by the low-temperature atomic layer deposition process in this application has a density greater than 90% and a controllable thickness. It can block the high-energy ion bombardment generated during magnetron sputtering, avoid the chemical bond breakage and deep-level defect generation of the top cell perovskite layer, reduce the nonradiative recombination probability of charge carriers, maintain the lattice integrity of the top cell perovskite layer, thereby improving the open-circuit voltage of the tandem cell and narrowing the gap with the sum of the voltages of the single-junction cell. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall cross-sectional structure of the tandem solar cell of this application; Figure 2 This is a graph showing the refractive index gradient distribution of each functional layer in the intermediate connection structure of this application; Figure 3 This is a comparison curve of interface optical transmittance simulated based on the optical transfer matrix method in this application; Figure 4 This is a schematic diagram of the microscopic mechanism by which the double-layer buffer structure of this application blocks ion damage from magnetron sputtering; Figure 5 This is a flowchart of the fabrication method of the optically matched and sputter-damage-resistant tandem solar cell proposed in this application. Detailed Implementation

[0030] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0031] Technical Concept: Metal halide perovskite tandem solar cells are a key technology for improving photoelectric conversion efficiency. The core lies in the intermediate connection structure between the top and bottom cells. Related technologies typically employ an organic buffer layer combined with a magnetron-sputtered transparent conductive oxide film, attempting to simultaneously achieve carrier transport resistance against sputtering damage and optical matching. However, the organic buffer layer has low density and pinhole defects, failing to effectively block high-energy ion bombardment during magnetron sputtering. This leads to the breaking of chemical bonds in the top cell's perovskite layer, generating deep-level defects and causing non-radiative recombination, exacerbating open-circuit voltage loss. Simultaneously, the refractive index of the organic buffer layer mismatches with that of the perovskite layer and the transparent conductive oxide film, resulting in significant interfacial light reflection, reducing the transmission efficiency of long-wavelength light and limiting the improvement of short-circuit current density.

[0032] To address the aforementioned issues, this application proposes a three-layer intermediate connection structure consisting of an optical coupling buffer layer, a dense protective layer, and a transparent conductive tunneling layer. By controlling the refractive index of the optical coupling buffer layer and constructing a decreasing refractive index gradient distribution for each layer, the interlayer Fresnel reflection is minimized, thereby improving the transmission efficiency of long-wavelength light. Simultaneously, a high-density metal oxide dense protective layer is prepared using a low-temperature atomic layer deposition process to block the bombardment of the top perovskite layer by magnetron sputtering high-energy ions, maintaining the lattice integrity of the perovskite layer. The optical matching effect of the optical coupling buffer layer and the anti-sputtering damage effect of the dense protective layer form a synergistic effect, ultimately achieving a simultaneous increase in the open-circuit voltage and short-circuit current density of the tandem solar cell.

[0033] Unless otherwise specified, all experimental methods used below are conventional methods. All materials, reagents, methods, and instruments used, unless otherwise specified, are conventional materials, reagents, methods, and instruments in this field, which can be obtained commercially or prepared according to literature methods by those skilled in the art.

[0034] To better understand the above technical solutions, the technical solutions of the present invention will be clearly and completely described below in conjunction with embodiments.

[0035] The following is a further description with reference to the embodiments: Example 1: Please refer to the appendix Figure 1 - Appendix Figure 5 A tandem solar cell with optical matching and sputter damage resistance, comprising a wide bandgap top cell, an intermediate connection structure, and a narrow bandgap bottom cell stacked sequentially from the light-receiving side to the back-lighting side; The intermediate connection structure includes an optical coupling buffer layer, a dense protective layer, and a transparent conductive tunneling layer, which are stacked sequentially from the wide bandgap top cell side to the narrow bandgap bottom cell side. The optical coupling buffer layer is a composite material of organic matrix doped with high refractive index nanoparticles. Its refractive index is 2 and the absolute value of the refractive index difference with the top cell light-absorbing layer is ≤0.3. The dense protective layer is a metal oxide film prepared by low temperature atomic layer deposition with a thickness of 17.5 nm and a density greater than 90%. The transparent conductive tunneling layer is a transparent conductive oxide film prepared by magnetron sputtering. In the intermediate connection structure, the refractive indices of the optical coupling buffer layer, the dense protective layer, and the transparent conductive tunneling layer satisfy a gradient decreasing relationship. ,in The refractive index of the top cell light-absorbing layer The refractive index of the optical coupling buffer layer, For the refractive index of the dense protective layer, The refractive index of the transparent conductive tunneling layer.

[0036] The organic matrix of the optical coupling buffer layer is selected from at least one of fullerene and its derivatives, polythiophene derivatives or long-chain organic ammonium salts, and the high refractive index nanoparticles are selected from at least one of titanium dioxide, zirconium dioxide, zinc sulfide or quantum dot materials with an average particle size of less than 10 nm. The mass ratio of organic matrix to high refractive index nanoparticles is 1:1.

[0037] The thickness of the optical coupling buffer layer satisfies the optical destructive interference condition. , where λ is the center wavelength of the transmission spectrum of the top cell, k is a non-negative integer, and d is the thickness of the optical coupling buffer layer.

[0038] The material of the dense protective layer is selected from at least one of tin dioxide, zinc oxide, or aluminum oxide.

[0039] The material of the transparent conductive tunneling layer is selected from at least one of indium tin oxide, indium zinc oxide, aluminum-doped zinc oxide, or fluorine-doped tin oxide.

[0040] The wide-bandgap top solar cell comprises a transparent electrode, an electron transport layer, a wide-bandgap perovskite light-absorbing layer, and a hole transport layer stacked sequentially. The transparent electrode is indium tin oxide or fluorine-doped tin oxide conductive glass, the electron transport layer is a tin dioxide thin film, the wide-bandgap perovskite light-absorbing layer is a lead bromide cesium thin film, and the hole transport layer is a polytriarylamine thin film. The narrow bandgap bottom cell comprises a hole transport layer, a narrow bandgap perovskite light-absorbing layer, an electron transport layer, and a back electrode stacked sequentially. The hole transport layer is a poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate film, the narrow bandgap perovskite light-absorbing layer is an iodine-tin-lead-cesium film, the electron transport layer is a fullerene derivative film, and the back electrode is a metallic silver electrode.

[0041] A method for fabricating an optically matched and sputter-damage-resistant tandem solar cell, applicable to the aforementioned optically matched and sputter-damage-resistant tandem solar cell, includes the following steps: S1. The conductive glass substrate was ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 15 min each, dried at 120℃ for 30 min, and then surface activated by UV-ozone treatment for 30 min. Subsequently, a wide-bandgap top cell was prepared on the activated conductive glass substrate. S2. Prepare a composite precursor ink of organic matrix and high refractive index nanoparticles, and deposit an optical coupling buffer layer on the surface of wide bandgap top cell through a coating process. S3. A dense protective layer is grown on the surface of the optical coupling buffer layer using atomic layer deposition at a temperature ≤110℃. S4. A transparent conductive tunneling layer is deposited on the surface of a dense protective layer using a magnetron sputtering process; S5. Narrow bandgap bottom cells are fabricated on the surface of a transparent conductive tunneling layer; S6. The prepared tandem battery is encapsulated to complete the preparation.

[0042] In step S2, the coating process of the composite precursor ink is spin coating, with a spin coating speed of 2000 rpm and a spin coating time of 30 s. After coating, it is annealed at 80°C for 5.5 min.

[0043] In step S3, the precursor pulse time for the atomic layer deposition process is 0.125 s, the purging time is 10 s, and the deposition cycle number is 175.

[0044] In step S4, the argon atmosphere pressure of the magnetron sputtering process is 0.55 Pa, the sputtering power is 100 W, and the deposition time is 6.5 min.

[0045] Example 2: This example differs from Example 1 above in that: An optically matched and sputter-damage tandem solar cell comprising a wide bandgap top cell, an intermediate connecting structure, and a narrow bandgap bottom cell stacked sequentially from the light-receiving side to the back-lighting side; The intermediate connection structure includes an optical coupling buffer layer, a dense protective layer, and a transparent conductive tunneling layer, which are stacked sequentially from the wide bandgap top cell side to the narrow bandgap bottom cell side. The optical coupling buffer layer is a composite material of organic matrix doped with high refractive index nanoparticles. Its refractive index is 1.8 and the absolute value of the refractive index difference with the top cell light-absorbing layer is ≤0.3. The dense protective layer is a metal oxide film prepared by low temperature atomic layer deposition with a thickness of 5nm and a density greater than 90%. The transparent conductive tunneling layer is a transparent conductive oxide film prepared by magnetron sputtering. In the intermediate connection structure, the refractive indices of the optical coupling buffer layer, the dense protective layer, and the transparent conductive tunneling layer satisfy a gradient decreasing relationship. ,in The refractive index of the top cell light-absorbing layer The refractive index of the optical coupling buffer layer, For the refractive index of the dense protective layer, The refractive index of the transparent conductive tunneling layer.

[0046] Example 3: This example differs from Example 1 above in that: An optically matched and sputter-damage tandem solar cell comprising a wide bandgap top cell, an intermediate connecting structure, and a narrow bandgap bottom cell stacked sequentially from the light-receiving side to the back-lighting side; The intermediate connection structure includes an optical coupling buffer layer, a dense protective layer, and a transparent conductive tunneling layer, which are stacked sequentially from the wide bandgap top cell side to the narrow bandgap bottom cell side. The optical coupling buffer layer is a composite material of organic matrix doped with high refractive index nanoparticles, with a refractive index of 2.2 and an absolute value of the refractive index difference between it and the top cell light-absorbing layer ≤0.3. The dense protective layer is a metal oxide film prepared by low-temperature atomic layer deposition, with a thickness of 30 nm and a density greater than 90%. The transparent conductive tunneling layer is a transparent conductive oxide film prepared by magnetron sputtering. In the intermediate connection structure, the refractive indices of the optical coupling buffer layer, the dense protective layer, and the transparent conductive tunneling layer satisfy a gradient decreasing relationship. ,in The refractive index of the top cell light-absorbing layer The refractive index of the optical coupling buffer layer, For the refractive index of the dense protective layer, The refractive index of the transparent conductive tunneling layer.

[0047] Example 4: This example differs from Example 1 above in that: The high-refractive-index nanoparticles of the optical coupling buffer layer are zirconium dioxide quantum dots with an average particle size of 8 nm; the organic matrix is ​​PEDOT:PSS, and the mass ratio of the organic matrix to ZrO2 quantum dots is 1:1; the refractive index of the optical coupling buffer layer is controlled to 2.1, and the thickness satisfies the optical destructive interference condition, k=0, λ=850 nm, and the calculated thickness d=101 nm. The dense protective layer is a SnO2 thin film prepared by ALD with a thickness of 17.5 nm; the transparent conductive tunneling layer is an ITO thin film, with a magnetron sputtering power of 110 W and a deposition time of 6 min.

[0048] The rest is the same as in Example 1.

[0049] Example 5: This example differs from Example 1 above in that: The dense protective layer is made of aluminum oxide thin film, prepared by atomic layer deposition process. The precursor is trimethylaluminum and deionized water. The pulse time is 0.15s, the purge time is 12s, the deposition cycle is 200 times, the thickness is 20nm, and the density is 92%. The high-refractive-index nanoparticles of the optical coupling buffer layer are TiO2 quantum dots with a refractive index of 2.0; The transparent conductive tunneling layer is an AZO thin film, and the magnetron sputtering argon gas pressure is 0.6 Pa.

[0050] The rest is the same as in Example 1.

[0051] Comparative Example 1: A fully perovskite tandem solar cell, consisting of a wide bandgap top cell, an intermediate connecting layer, and a narrow bandgap bottom cell stacked sequentially from the light-receiving side to the back-lighting side. The intermediate connecting layer is composed of a pure fullerene buffer layer with a thickness of 40 nm and a refractive index of 1.65 and an ITO transparent conductive layer prepared by magnetron sputtering with a thickness of 100 nm.

[0052] The preparation method includes the following steps: S1, Same as in Example 1; S2: Spin-coating pure C at a concentration of 10 mg / mL 60 Chlorobenzene solution was applied to the surface of the top cell, and annealed at 80°C for 5 minutes at 2000 rpm for 30 seconds to form pure C. 60 Buffer layer; S3: In C 60 An ITO transparent conductive layer was deposited on the surface of the buffer layer using magnetron sputtering to form an intermediate connecting layer. The magnetron sputtering process used an argon gas pressure of 0.5 Pa, a power of 100 W, and a deposition time of 5 min. S4: Fabricate and encapsulate a narrow bandgap bottom cell on the intermediate interconnect layer.

[0053] Comparative Example 2: This comparative example differs from Example 1 above in that: The intermediate connection structure has no dense protective layer, and only contains an optical coupling buffer layer (C). 60 -TiO2 composite layer, refractive index 2) and transparent conductive tunneling layer (IZO thin film); During magnetron sputtering deposition of IZO, high-energy ions directly bombard the optically coupled buffer layer and the underlying perovskite layer.

[0054] The rest is the same as in Example 1.

[0055] Comparative Example 3: This comparative example differs from Example 1 above in that: The mass ratio of organic matrix to TiO2 quantum dots in the optical coupling buffer layer is 3:1, and the refractive index of the optical coupling buffer layer is 1.6. The refractive indices of the layers in the intermediate connecting structure cannot satisfy the gradient decreasing relationship: .

[0056] The remaining structure and preparation steps are the same as in Example 1.

[0057] Performance testing: Photovoltaic performance indicators: Using a solar cell testing system, at a light intensity of 100mW / cm² 2 Open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency were tested under standard AM1.5G illumination. Sputter damage resistance index: The binding energy of Pb4f orbitals on the surface of the perovskite layer of the top cell was measured by X-ray photoelectron spectroscopy, and the Pb-I bond breakage rate was calculated to characterize the degree of sputter damage. Optical matching index: The average transmittance in the 700-1000nm long-wavelength band was measured using a UV-Vis-NIR spectrophotometer to characterize the optical matching effect.

[0058] Table 1

[0059] As can be seen from Examples 1 to 5 and Comparative Example 1, and Table 1, the double-layer intermediate connection structure composed of the optical coupling buffer layer and the dense protective layer can achieve the synergistic effect of optical matching and sputter damage resistance. This structure reduces interlayer light reflection through refractive index gradient design, while using the dense protective layer to block sputtered high-energy ions, maintaining the structural integrity of the perovskite layer of the top cell, thereby improving the photoelectric conversion performance of the tandem cell.

[0060] As can be seen from Example 1 and Comparative Example 2, and Table 1, the dense protective layer is a key structure to resist damage from magnetron sputtering ions. This protective layer can form a dense barrier without pinholes, preventing high-energy ions from bombarding the perovskite layer of the top cell and reducing the generation of non-radiative recombination centers. Structures lacking this layer will show obvious interface damage, leading to a decrease in the open-circuit voltage and fill factor of the cell.

[0061] As can be seen from Example 1 and Comparative Example 3, and Table 1, the refractive index gradient distribution of the intermediate connecting structure is the core factor for achieving optical matching. The refractive index range of the optical coupling buffer layer defined in this application can construct a smooth refractive index transition, reduce the reflection loss of long-wavelength light, and improve the light absorption efficiency of the bottom cell.

[0062] As can be seen from Examples 1 to 3 and Table 1, when the refractive index of the optical coupling buffer layer is adjusted within the range defined in this application, the battery can maintain stable overall performance. This refractive index range can take into account both optical matching effect and interface buffering effect, avoiding the impact of light transmission and carrier transport due to excessively high or low refractive index, and ensuring the photoelectric conversion efficiency of the battery.

[0063] As can be seen from Examples 1, 4 and 5 and Table 1, when the material systems of the optical coupling buffer layer and the dense protective layer are replaced within the scope defined in this application, the battery performance can still remain stable. Different high refractive index nanoparticles and metal oxide materials can all adapt to the requirements of the double-layer intermediate connection structure.

[0064] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A tandem solar cell with optical matching and resistance to sputtering damage, characterized in that, It includes a wide bandgap top cell, an intermediate connecting structure, and a narrow bandgap bottom cell, which are stacked sequentially from the light-receiving side to the back-lighting side; The intermediate connection structure includes an optical coupling buffer layer, a dense protective layer, and a transparent conductive tunneling layer, which are stacked sequentially from the wide bandgap top cell side to the narrow bandgap bottom cell side. The optical coupling buffer layer is a composite material of organic matrix doped with high refractive index nanoparticles, with a refractive index of 1.8-2.2 and an absolute value of the refractive index difference with the top cell light-absorbing layer ≤0.

3. The dense protective layer is a metal oxide thin film prepared by low-temperature atomic layer deposition, with a thickness of 5-30 nm and a density greater than 90%. The transparent conductive tunneling layer is a transparent conductive oxide thin film prepared by magnetron sputtering. In the intermediate connection structure, the refractive indices of the optical coupling buffer layer, the dense protective layer, and the transparent conductive tunneling layer satisfy a gradient decreasing relationship. ,in The refractive index of the top cell light-absorbing layer The refractive index of the optical coupling buffer layer, For the refractive index of the dense protective layer, The refractive index of the transparent conductive tunneling layer.

2. The optically matched and sputter-damage-resistant tandem solar cell according to claim 1, characterized in that: The organic matrix of the optical coupling buffer layer is selected from at least one of fullerene and its derivatives, polythiophene derivatives or long-chain organic ammonium salts, and the high refractive index nanoparticles are selected from at least one of titanium dioxide, zirconium dioxide, zinc sulfide or quantum dot materials and have an average particle size of less than 10 nm. The mass ratio of the organic matrix to the high refractive index nanoparticles is 0.5-2:

1.

3. The optically matched and sputter-damage-resistant tandem solar cell and its manufacturing method according to claim 1, characterized in that: The thickness of the optical coupling buffer layer satisfies the optical destructive interference condition. Where λ is the center wavelength of the transmission spectrum of the top cell, and k is a non-negative integer. The thickness of the optical coupling buffer layer is given.

4. The optically matched and sputter-damage-resistant tandem solar cell and its manufacturing method according to claim 1, characterized in that: The material of the dense protective layer is selected from at least one of tin dioxide, zinc oxide, or aluminum oxide.

5. The optically matched and sputter-damage-resistant tandem solar cell and its manufacturing method according to claim 1, characterized in that: The material of the transparent conductive tunneling layer is selected from at least one of indium tin oxide, indium zinc oxide, aluminum-doped zinc oxide, or fluorine-doped tin oxide.

6. The optically matched and sputter-damage-resistant tandem solar cell and its manufacturing method according to claim 1, characterized in that: The wide-bandgap top cell comprises a transparent electrode, an electron transport layer, a wide-bandgap perovskite light-absorbing layer, and a hole transport layer stacked sequentially. The transparent electrode is indium tin oxide or fluorine-doped tin oxide conductive glass. The electron transport layer is a tin dioxide thin film. The wide-bandgap perovskite light-absorbing layer is a lead bromide cesium iodide thin film. The hole transport layer is a polytriarylamine thin film. The narrow bandgap bottom cell includes a hole transport layer, a narrow bandgap perovskite light-absorbing layer, an electron transport layer, and a back electrode stacked sequentially. The hole transport layer is a poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate film, the narrow bandgap perovskite light-absorbing layer is an iodine-tin-lead-cesium film, the electron transport layer is a fullerene derivative film, and the back electrode is a metallic silver electrode.

7. A method for manufacturing an optically matched and sputter-damage-resistant tandem solar cell, characterized in that: The application of the optically matched and sputter-damage-resistant tandem solar cell according to any one of claims 1-6 includes the following steps: S1. The conductive glass substrate is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 13-17 min each, dried at 110-130℃ for 25-35 min, and then surface activated by UV-ozone treatment for 25-35 min. Subsequently, a wide-bandgap top cell is prepared on the activated conductive glass substrate. S2. Prepare a composite precursor ink of organic matrix and high refractive index nanoparticles, and deposit an optical coupling buffer layer on the surface of wide bandgap top cell through a coating process. S3. A dense protective layer is grown on the surface of the optical coupling buffer layer using atomic layer deposition at a temperature ≤110℃. S4. A transparent conductive tunneling layer is deposited on the surface of a dense protective layer using a magnetron sputtering process; S5. Narrow bandgap bottom cells are fabricated on the surface of a transparent conductive tunneling layer; S6. The prepared tandem battery is encapsulated to complete the preparation.

8. The method for manufacturing an optically matched and sputter-damage-resistant tandem solar cell according to claim 7, characterized in that: In step S2, the coating process of the composite precursor ink is a spin coating process, with a spin coating speed of 1500-2500 rpm and a spin coating time of 20-40 s. After coating, it is annealed at 70-90℃ for 3-8 min.

9. The method for manufacturing an optically matched and sputter-damage-resistant tandem solar cell according to claim 7, characterized in that: In step S3, the precursor pulse time of the atomic layer deposition process is 0.05-0.2s, the purging time is 5-15s, and the number of deposition cycles is 50-300.

10. The method for manufacturing an optically matched and sputter-damage-resistant tandem solar cell according to claim 7, characterized in that: In step S4, the argon atmosphere pressure of the magnetron sputtering process is 0.3-0.8 Pa, the sputtering power is 80-120 W, and the deposition time is 3-10 min.

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