Mechanical stacking method of perovskite-silicon laminated cell

Abstract

The invention relates to the technical field of solar cells, and discloses a mechanical stacking method of a perovskite-silicon laminated cell, and the mechanical stacking method comprises the steps: enabling a top perovskite cell and a bottom crystal silicon cell to be respectively adsorbed on the two surfaces of a flexible material through electrostatic adsorption, so as to complete the stacking of the top cell and the bottom cell; the adsorption surface of the perovskite cell is the surface of a transparent conductive substrate layer of the perovskite cell, the adsorption surface of the crystalline silicon cell is the surface of crystalline silicon cell packaging glass, and the adsorption surface of the crystalline silicon cell is provided with a hollow metal grid line electrode; and the thickness of the flexible material is 15-40 [mu] m. According to the mechanical stacking method provided by the invention, the problems that the optical cement affects the performance and stability of the perovskite cell, the replacement difficulty of the sub-module in the laminated cell is high, the maintenance cost is high and the optical cement layer causes optical energy loss in the existing optical cement mechanical stacking method are solved.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and more specifically to a mechanical stacking method for perovskite-silicon tandem solar cells. Background Technology

[0002] Tandem solar cells, also known as multi-junction solar cells, are a technology that stacks solar cells made of two or more different materials like a sandwich to more efficiently capture and utilize the energy of the solar spectrum, thus significantly breaking through the theoretical efficiency limit of traditional single-junction solar cells. For crystalline silicon solar cells, which dominate photovoltaic power generation, the absorption of high-energy photons in the blue-violet light band results in severe pyroelectric energy loss, greatly limiting the improvement of the cell's photoelectric conversion efficiency. The high technical difficulty and cost of further improving the efficiency of crystalline silicon solar cells pose a significant challenge to the large-scale application of Si cells. To address this issue, researchers have proposed perovskite-silicon tandem solar cell technology. This technology utilizes a wide-bandgap perovskite top cell to absorb short-wavelength photons and a Si bottom cell to absorb long-wavelength photons, thereby significantly improving the utilization rate of the solar spectrum and is an important means to break through the theoretical efficiency limit of Si cells. The perovskite-silicon tandem solar cell has a perovskite top cell and a crystalline silicon bottom cell; the combination of the two perfectly covers the solar spectrum and is currently the most promising tandem solar cell technology.

[0003] There are currently two main types of stacking methods for tandem solar cells: monolithic integration and mechanical stacking. Mechanical stacking can treat the top cell and bottom cell as two independent "sub-modules" and manufacture them separately. Therefore, it has advantages such as process decoupling (the top and bottom cells can be produced independently under their respective optimal conditions), high flexibility (free combination of different types of top and bottom cells), and utilization of mature production lines. Thus, it provides a pragmatic and highly promising technical path for perovskite-silicon tandem solar cells.

[0004] Currently, the main mechanical stacking method for perovskite-silicon tandem solar cells is to connect the perovskite top cell and the silicon bottom cell using transparent optical adhesives. Commonly used transparent optical adhesives are made from acrylate or modified acrylate-based resins, which require heating and curing at temperatures between 60℃ and 150℃. This temperature range can easily damage the fabricated perovskite solar cell (especially the internal perovskite transport layer), reducing its stability. Furthermore, due to the inherent brittleness of perovskite solar cells, stress may be generated during curing. The adhesive's curing shrinkage can generate upward tensile stress, or excessive stress due to temperature changes can easily lead to microcracks in the perovskite film. These cracks provide direct channels for moisture and oxygen intrusion, rapidly causing the decomposition and failure of the perovskite material. Simultaneously, heating and curing also produces small molecules, the release of which can poison the perovskite layer, causing irreversible performance degradation and damaging the charge transport layer interface, forming defect layers or air gaps. Therefore, in existing mechanically stacked perovskite-silicon tandem solar cells, the perovskite cells have poor performance stability and are prone to hydrolysis and oxidation, requiring periodic replacement. During this process, the connecting resin layer can damage the silicon cells, resulting in excessively high maintenance costs and making replacement impractical. Furthermore, the adhesive layer between the cells is only 1-2 cm thick, and this thick layer contains numerous air bubbles. When sunlight passes through the perovskite cells and enters the silicon cells, the presence of the resin layer causes severe scattering and Fresnel reflection of the incident light, preventing it from reaching the underlying silicon cells and resulting in significant energy loss. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a mechanical stacking method for perovskite-silicon tandem solar cells, which solves the problems of optical adhesive affecting the performance and stability of perovskite solar cells, the difficulty in replacing "sub-modules" in tandem solar cells, the high maintenance cost, and the light energy loss caused by the optical adhesive layer in existing optical adhesive mechanical stacking methods.

[0006] To achieve the above objectives, this invention provides a mechanical stacking method for perovskite-silicon tandem solar cells. The mechanical stacking method involves electrostatically adsorbing the top perovskite solar cell and the bottom crystalline silicon solar cell onto two sides of a flexible material, thereby completing the stacking of the top and bottom cells. The adsorption surface of the perovskite solar cell is the surface of its transparent conductive substrate, and the adsorption surface of the crystalline silicon solar cell is the surface of its encapsulation glass. The adsorption surface of the crystalline silicon solar cell is provided with perforated metal grid electrodes. The thickness of the flexible material is 15-40 μm.

[0007] This invention utilizes a flexible material of a certain thickness placed between a perovskite solar cell and a crystalline silicon solar cell to achieve mechanical stacking of the top and bottom cells via electrostatic adsorption. By controlling the charge on the adsorption surface, a tight, seamless stacking between the perovskite and crystalline silicon cells is achieved. This ensures that all sunlight passing through the perovskite cell enters the silicon cell without loss, achieving the highest photo-to-electric conversion efficiency. More photons enter the semiconductor, generating more electron-hole pairs and increasing circuit current. The mechanical stacking method provided by this invention eliminates the need for resin adhesive bonding, overcoming the influence of resin adhesive on the performance and stability of the perovskite cell. Furthermore, since the perovskite and silicon cells are connected by electrostatic adsorption, peeling off the perovskite only requires eliminating the static electricity between the perovskite and silicon cells, making peeling very convenient and without damaging the silicon cell. Therefore, this application significantly reduces the subsequent maintenance costs of perovskite-silicon tandem solar cells.

[0008] In some embodiments of this application, the flexible material is selected from at least one of PEN (polyethylene naphthalate) and its copolymers, PET (polyethylene terephthalate resin), PBT (polybutylene terephthalate), COP (cyclic olefin polymer), PI (polyimide, specifically transparent grade), and PC (polycarbonate).

[0009] In some embodiments of this application, the perovskite-silicon tandem solar cell's packaging structure, from top to bottom, includes a perovskite solar cell device, a flexible material layer, and a crystalline silicon solar cell device. The electrical connection method of the perovskite-silicon tandem solar cell is a four-terminal tandem solar cell. In the four-terminal tandem solar cell, the perovskite cell and the silicon cell are two completely independent units physically and electrically, with no current matching limitations, and the bandgap matching of the perovskite cell and the silicon cell does not need to be considered.

[0010] In some embodiments of this application, the perovskite solar cell device has a structure including a formal nip structure and an inverted pin structure. The formal nip structure includes a transparent conductive substrate layer → electron transport layer → perovskite light-absorbing layer → hole transport layer → metal electrode → cover glass. The inverted nip structure includes a transparent conductive substrate layer → hole transport layer → perovskite light-absorbing layer → electron transport layer → metal electrode → cover glass.

[0011] In some embodiments of this application, the structure of the crystalline silicon solar cell device includes encapsulation glass → encapsulation film → crystalline silicon solar cell → encapsulation film → encapsulation glass.

[0012] In some embodiments of this application, the grid line height of the hollow metal grid line electrode is 2±1μm, and the electrode hollowing rate is ≥80%.

[0013] In some embodiments of this application, the mechanical stacking method includes the following steps: Step 1: Pre-treatment of battery components: Clean the adsorption surfaces of perovskite and crystalline silicon batteries, and prepare hollow metal grid electrodes on the adsorption surface of the crystalline silicon battery. Step 2: The perovskite solar cell pretreated in Step 1 is electrostatically adsorbed onto the upper surface of the PEN film using an electrostatic generation device. Step 3: The crystalline silicon cell pretreated in Step 1 is electrostatically adsorbed onto the lower surface of the PEN film using an electrostatic generation device. Step 4: After eliminating residual static electricity using an electrostatic eliminator, the battery is packaged to obtain the perovskite-silicon tandem solar cell. Furthermore, the peel force between the perovskite solar cell or crystalline silicon solar cell and the PEN film is 0.1-20N. Specifically, for a 10cm layer... 2 The peel force for the following small-area batteries is 0.1-5N, 10cm. 2 The peel force of the above large-area batteries is 5-20N.

[0014] Furthermore, the output voltage of the electrostatic generating device is 5-30KV, with the specific value adjusted according to the battery size. The upper limit is used for large-area batteries, and the lower limit is used for small-area batteries. The general principle is to ensure stable voltage output without pulse fluctuations.

[0015] Furthermore, the electrostatic adsorption time is 10-20 seconds, and the adsorption force is 0.1-20N.

[0016] Compared with the prior art, the mechanical stacking method provided by the present invention has the following advantages: (1) Simplified process: Traditional adhesive bonding solutions require complex processes such as coating and curing, and are prone to introducing impurities such as dust and bubbles. Bubbles will expand during subsequent heating, leading to film deformation and making the stability of the entire production process worse. In contrast, electrostatic adsorption bonding does not require coating with adhesive or high-temperature bonding, avoiding the contamination of bubbles and impurities that may be generated during the curing process of the adhesive layer, as well as the damage of high temperature to the perovskite active layer.

[0017] (2) Reversible process: Electrostatic adsorption is a non-contact physical connection, which can achieve non-destructive separation of two batteries by eliminating static electricity, making it easy to replace or maintain individual batteries and greatly reducing the maintenance cost of stacked batteries. In contrast, traditional adhesive bonding is usually an irreversible chemical bond, which is difficult to separate without damage once it has cured. (3) Minimal interface impact: This invention does not require the application of adhesives such as epoxy glue and UV glue, thus avoiding contamination from bubbles or impurities generated during the curing process of the adhesive layer, and at the same time eliminating the reflection / refractive loss of the adhesive layer to light.

[0018] (4) Excellent efficiency: The interface is tightly bonded and there is no adhesive layer to block it, which helps to improve the carrier transport efficiency and improve the conversion efficiency of the tandem battery. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of the perovskite-silicon tandem solar cell prepared in Example 3 of the present invention; Figure 2 This is a schematic diagram of the circuit connection of the perovskite-silicon tandem solar cell prepared in Example 3 of the present invention; Figure 3 This is a schematic diagram of the process for preparing a flexible perovskite solar cell in Example 1 of the present invention; Figure 4 This is a schematic diagram of the perovskite-silicon tandem solar cell prepared in Comparative Example 1 of the present invention. Figure 5 The JV curve of the stacked battery device prepared in Example 3 of this invention; Figure 6 The JV curve of the stacked battery device prepared in Example 4 of this invention; Figure 7 The JV curve of the stacked battery device prepared in Comparative Example 1 of this invention; Figure 8 The JV curve is shown for the tandem battery device prepared in Comparative Example 2 of this invention.

[0021] Legend: 1-Perovskite solar cell device; 2-Flexible material; 3-Crystal silicon solar cell device; 4-UV-curable resin adhesive; 5-Power optimizer; 6-Capacitor cell; 11-Transparent conductive substrate; 12-Hole transport layer; 13-Perovskite light-absorbing layer; 14-Electron transport layer; 15-Metal electrode; 16-Cover glass; 31 / 35-Encapsulation glass; 32 / 34-Encapsulation film; 33-Crystal silicon solar cell. Specific implementation methods The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the raw materials used in the following embodiments can all be obtained through commercial channels.

[0022] This invention provides a mechanical stacking method for perovskite-silicon tandem solar cells. The mechanical stacking method involves electrostatically adsorbing the top perovskite solar cell and the bottom crystalline silicon solar cell onto two sides of a flexible material, thereby completing the stacking of the top and bottom cells. The adsorption surface of the perovskite solar cell is the surface of the transparent conductive substrate layer of the perovskite solar cell, and the adsorption surface of the crystalline silicon solar cell is the surface of the crystalline silicon solar cell encapsulation glass. The adsorption surface of the crystalline silicon solar cell is provided with perforated metal grid electrodes. The thickness of the flexible material is 15-40 μm.

[0023] Furthermore, the flexible material is selected from at least one of PEN (polyethylene naphthalate) and its copolymers, PET (polyethylene terephthalate resin), PBT (polybutylene terephthalate), COP (cyclic olefin polymer), PI (polyimide, specifically transparent grade), and PC (polycarbonate).

[0024] Further, see Figure 1 The perovskite-silicon tandem solar cell's encapsulation structure, from top to bottom, includes a perovskite solar cell device 1, a flexible material 2, and a crystalline silicon solar cell device 3. The perovskite solar cell device 1, from top to bottom, includes a cover glass 16, a metal electrode 15, an electron transport layer 14, a perovskite light-absorbing layer 13, a hole transport layer 12, and a transparent conductive substrate layer 11. The crystalline silicon solar cell device 3, from top to bottom, includes an encapsulation glass 31, an encapsulation film 32, a crystalline silicon solar cell 33, an encapsulation film 34, and an encapsulation glass 35.

[0025] The perovskite-silicon tandem solar cell is electrically connected as a four-terminal tandem cell. Specifically, the positive and negative electrodes are led out from the perovskite top cell and the silicon bottom cell, respectively. See also... Figure 2 The circuit diagram shown is for a perovskite-silicon tandem solar cell. It employs a four-terminal tandem output configuration, with perovskite cell device 1 and crystalline silicon cell device 3 connected in parallel. Their respective output currents pass through a power optimizer 5, where they are converted to the same magnitude before finally flowing into a capacitor cell 6 for storage. In this four-terminal tandem solar cell, the perovskite and crystalline silicon cells are physically and electrically completely independent units, with no current matching limitations, and the bandgap matching between the perovskite and crystalline silicon cells does not need to be considered.

[0026] In some embodiments of this application, the grid line height of the hollow metal grid line electrode is 2±1μm, and the electrode hollowing rate is ≥80%.

[0027] In some embodiments of this application, the mechanical stacking method includes the following steps: Step 1: Pre-treatment of battery components: Clean the adsorption surfaces of perovskite and crystalline silicon batteries, and prepare hollow metal grid electrodes on the adsorption surface of the crystalline silicon battery. Step 2: The perovskite solar cell pretreated in Step 1 is electrostatically adsorbed onto the upper surface of the PEN film using an electrostatic generation device. Step 3: The crystalline silicon cell pretreated in Step 1 is electrostatically adsorbed onto the lower surface of the PEN film using an electrostatic generation device. Step 4: After eliminating residual static electricity using an electrostatic eliminator, the battery is packaged to obtain the perovskite-silicon tandem battery.

[0028] Furthermore, the peel force between the perovskite solar cell or crystalline silicon solar cell and the PEN film is 0.1-20N. Specifically, the peel force is 10cm. 2 The peel force for the following small-area batteries is 0.1-5N, 10cm. 2 The peel force for the above large-area batteries is 5-20N.

[0029] Furthermore, the output voltage of the electrostatic generating device is 5-30KV, with the specific value adjusted according to the battery size. The upper limit is used for large-area batteries, and the lower limit is used for small-area batteries. The general principle is to ensure stable voltage output without pulse fluctuations.

[0030] Furthermore, the electrostatic adsorption time is 10-20 seconds, and the adsorption force is 0.1-20N.

[0031] It is understood that this application does not impose specific restrictions on the type, model, or manufacturer of the static electricity generating device and the static electricity eliminating device, as long as they can achieve the purpose of this application.

[0032] The following specific embodiments and comparative examples are provided to illustrate the implementation of this application in more detail.

[0033] Example 1: Fabrication of Flexible Perovskite Solar Cells For the process of fabricating flexible perovskite solar cells, please refer to [link / reference]. Figure 3 As shown: ① Flexible PEN material is attached to the surface of ITO glass using high-temperature resistant double-sided adhesive; ② A 100nm thick indium tin oxide layer is deposited on the PEN material; ③ A perovskite hole transport layer is fabricated; ④ A perovskite layer (PVK) is fabricated; ⑤ A complete perovskite device is fabricated; ⑥ The ITO glass is removed, finally obtaining a semi-transparent flexible perovskite solar cell. The specific operation method is as follows: (1) Clean the flexible PEN material (polyethylene naphthalate) and ITO glass with glass cleaner, deionized water and isopropanol for 5 minutes, and then dry them for later use.

[0034] (2) Apply the flexible PEN material to the surface of the ITO glass with high temperature resistant double-sided tape to fix the PEN material in place. This will prevent the PEN material from deforming in subsequent experiments.

[0035] (3) After treating the PEN material on the ITO glass surface with ultraviolet ozone for 15 minutes, magnetron sputtering is performed on the flexible PEN material attached to the ITO glass surface to deposit a 100nm thick indium tin oxide layer on the PEN material.

[0036] (4) 20 mg of nickel oxide (NiO) nanoparticles were dispersed in 1 mL of deionized water and spin-coated onto the surface of PEN material at 2000 rpm / s for 30 s, followed by annealing on a hot plate at 100 ℃ for 40 min. After the substrate cooled to room temperature, it was cleaned again with ultraviolet ozone for 15 min.

[0037] (5) Dissolve 0.5 mg of MeO-2PACz "[2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid" in 1 mL of ethanol, spin coat it onto the NiO substrate at 3500 rpm / s for 30 s, and then anneal it on a hot plate at 100 ℃ for 10 min.

[0038] (6) Preparation of mixed perovskite precursor solution: Lead iodide (PbI2-621.8mg), formamidinium iodide (FAI-289.2mg), cesium iodide (CsI-25.2mg), methylammonium bromide (MABr-15.8mg) and lead bromide (PbBr2-64.3mg) were dissolved in 1mL of mixed solvent of N,N-dimethylformamide / N-methylpyrrolidone / dimethyl sulfoxide (DMF / NMP / DMSO, volume ratio 82:16:2) and stirred for 5h.

[0039] (7) Take 50 μL of mixed perovskite precursor solution with a pipette and spin coat it onto the MeO-2PACz substrate at 4000 rpm, 3000 rpm / s acceleration, and 10 s spin coating time. After spin coating, transfer it to a vacuum container (30*30 cm), evacuate for 30 s, and then anneal it on a hot stage at 100 ℃ for 50 min to obtain the PVK layer (perovskite layer).

[0040] (8) Dissolve 60 μL of 1 mg PDADI (1,3-diaminopropane dihydroiodate) in 1 mL of IPA (isopropanol) solution, spin-coat it onto the perovskite film surface at 4000 rpm, 3000 rpm / s, and 30 s spin-coating time, and anneal it on a 100°C hot plate for 10 min. Then, sequentially thermally evaporate and deposit a 30 nm thick C film at a rate of 0.3 Å / s. 60 A fullerene layer and a 6 nm thick BCP (bisphenol fluorene polycarbonate) layer were then deposited. Finally, a 120 nm thick silver (Ag) film was deposited using thermal evaporation with a mask as the metal electrode of the device.

[0041] (9) Finally, the bottom ITO glass is removed, and the metal electrode surface is encapsulated with POE film and cover glass to isolate water and oxygen and obtain a flexible semi-transparent perovskite solar cell.

[0042] Example 2: Fabrication of a rigid perovskite solar cell For detailed steps, please refer to the following: (1) Clean the indium tin oxide (ITO) glass with glass cleaner, deionized water and isopropanol for 5 minutes, then dry it and set it aside for use, and then perform ultraviolet ozone treatment for 15 minutes.

[0043] (2) 20 mg of nickel oxide (NiO) nanoparticles were dispersed in 1 mL of deionized water and spin-coated onto the surface of PEN material at 2000 rpm / s for 30 s, followed by annealing on a hot plate at 100 ℃ for 40 min. After the substrate cooled to room temperature, it was cleaned again with ultraviolet ozone for 15 min.

[0044] (3) Dissolve 0.5 mg of MeO-2PACz "[2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid" in 1 mL of ethanol, spin coat it onto the NiO substrate at 3500 rpm / s for 30 s, and then anneal it on a hot plate at 100 ℃ for 10 min.

[0045] (4) Preparation of mixed perovskite precursor solution: lead iodide (PbI2-621.8mg), formamidinium iodide (FAI-289.2mg), cesium iodide (CsI-25.2mg), methylammonium bromide (MABr-15.8mg) and lead bromide (PbBr2-64.3mg) were dissolved in 1mL of mixed solvent of N,N-dimethylformamide / N-methylpyrrolidone / dimethyl sulfoxide (DMF / NMP / DMSO, volume ratio 82:16:2) and stirred for 5h.

[0046] (5) Take 50 μL of mixed perovskite precursor solution with a pipette and spin coat it onto the MeO-2PACz substrate at 4000 rpm, 3000 rpm / s acceleration, and 10s spin coating time. After spin coating, transfer it to a vacuum container (30*30cm), evacuate for 30s, and then anneal it on a hot stage at 100 ℃ for 50 min to obtain the PVK layer (perovskite layer).

[0047] (6) Dissolve 60 μL of 1 mg PDADI (1,3-diaminopropane dihydroiodate) in 1 mL of IPA (isopropanol) solution, spin-coat it onto the perovskite film surface at 4000 rpm, 3000 rpm / s, and 30 s spin-coating time, and anneal it on a 100°C hot plate for 10 min. Then, thermally evaporate and deposit a 30 nm thick C film at a rate of 0.3 Å / s. 60 A fullerene layer and a 6 nm thick BCP (bisphenol fluorene polycarbonate) layer were then deposited. Finally, a 120 nm thick silver (Ag) film was deposited using thermal evaporation with a mask as the metal electrode of the device.

[0048] (7) On the back electrode surface, POE film and cover glass are used for encapsulation to isolate water and oxygen and obtain rigid perovskite solar cell devices.

[0049] Example 3: Preparation of perovskite-silicon four-terminal tandem solar cells by electrostatic adsorption method The perovskite solar cell uses the rigid perovskite solar cell prepared in Example 2. The crystalline silicon solar cell is commercially available. Its structure includes front tempered glass → upper EVA film → crystalline silicon solar cell → lower EVA film → back tempered glass.

[0050] The specific operation method for preparing perovskite-silicon four-terminal tandem solar cells by electrostatic adsorption is as follows: I. Pretreatment of Battery Components and Flexible Materials 1. Pretreatment of perovskite solar cells: (1) Surface cleaning: Use organic solvents (such as anhydrous ethanol, isopropanol) to ultrasonically clean the flexible substrate of the cell to remove oil, dust and other impurities, and then blow dry with nitrogen to avoid residual moisture or contaminants affecting the electrostatic adsorption effect; (2) Performance verification: Confirm that the perovskite layer is crystallized and free of pinholes or cracks, and the transport layer (such as NiO) is intact. x TiO2) adheres firmly to the electrode layer (such as ITO, Ag).

[0051] 2. Pretreatment of crystalline silicon cells: (1) Surface cleaning: Wet chemical cleaning (such as HF dilute solution to remove oxide layer) + ultrasonic cleaning (deionized water) is used to remove oxide film, residual silicon powder and oil stains on the surface of silicon cells. After drying, ensure that there are no hydrophilic / hydrophobic uneven areas on the surface; (2) Electrode adaptation: Hollow metal grid line electrodes (preferably Ag or Al material, grid line height 2μm±1μm) are prepared on the bonding surface (upper surface) of crystalline silicon cells to ensure that the electrode hollowing rate is ≥80%, which ensures charge transmission and does not block light.

[0052] 3. Pretreatment of PEN flexible material: Material selection and size matching: Select PEN film with a thickness of 15-40μm, requiring a surface flatness of ≤5μm, light transmittance ≥92% (300-1200nm spectral range), and dielectric constant of 3.0-3.5 (for electrostatic adsorption); cut PEN according to the size of perovskite and silicon cells, with the edge size 2-5mm larger than the cell, leaving a repositioning allowance.

[0053] Surface activation and cleaning: ① Activation treatment: Use plasma activation (oxygen atmosphere, power 100-150W, time 60-120 seconds) or ultraviolet ozone activation (time 10-15 minutes) to enhance the surface polarity and adsorption activity of PEN and strengthen electrostatic adsorption force; ② Cleaning treatment: Immediately after activation, use the process of "wiping with anhydrous ethanol → rinsing with deionized water → purging and drying with nitrogen" to remove residual activation products and impurities on the surface. After drying, avoid prolonged exposure to air (≤30 minutes) to prevent recontamination.

[0054] Electrostatic performance verification: The electrostatic adsorption capacity of the PEN surface is tested using an electrostatic tester to ensure that the surface electrostatic voltage is ≥1kV and the decay rate is ≤50V / min under a voltage of 10-30kV, thus ensuring adsorption stability; if the decay is too fast, reactivation treatment is required.

[0055] II. Electrostatic Adsorption System Debugging 1. Equipment Composition: The core equipment includes an electrostatic generator, a rigid support platform, a spacing adjustment mechanism, and an electrostatic elimination device; the rigid support platform is used to place crystalline silicon cells.

[0056] Parameter presets: ① Electrostatic generator debugging: Set the output voltage to 5kV~30kV (adjust according to the battery size, use the upper limit for large-area batteries and the lower limit for small-area batteries) to ensure stable voltage output without pulse fluctuations; ② Spacing calibration: Adjust the spacing between the electrostatic generator and the rigid support platform to ≤20mm to ensure that the electric field uniformly covers the area to be bonded; ③ Adhesion force preset: Preset the adhesion force range to 0.1N~20N according to the battery area (0.1~5N for small-area batteries under 10cm², and 5~20N for large-area batteries over 10cm²) to avoid insufficient adhesion leading to poor adhesion, or excessive adhesion damaging the perovskite layer of the flexible perovskite battery.

[0057] III. Electrostatic Adsorption and Bonding This stage is crucial for achieving stable stacking. The core is to ensure precise alignment of the PEN with the two cells through visual alignment, and to use a gradient electric field to drive the PEN to electrostatically adhere to the silicon and perovskite cells respectively, relying on the PEN's flexibility to buffer interface stress. The specific steps are as follows: Step 1: Electrostatic adsorption bonding of PEN and silicon battery ① Fix the pre-treated silicon battery in the center of the ceramic electrostatic chuck, ensuring complete adhesion between the battery and the chuck with no suspended areas; ② Adjust the position of the flexible PEN using a visual alignment system, aligning the center of the PEN with the center of the silicon battery, with the edge extending 2-5mm beyond the battery, ensuring the PEN completely covers the silicon battery's bonding surface; ③ Adjust the initial distance between the PEN and the silicon battery to 2-4mm, ensuring the PEN is parallel to the silicon battery surface; ④ Activate the electrostatic generator (single-sided discharge mode, facing the PEN side), using a gradient voltage increase mode: first increase to 50% of the preset voltage and hold for 5 seconds, allowing the PEN and silicon battery surface to initially generate electrostatic induction charges, forming a weak attraction; ⑤ Slowly decrease the distance at a rate of 0.3-0.5mm / s until the PEN and silicon battery make slight contact, monitoring the adsorption force in real time to ensure the force value increases slowly without sudden changes; ⑥ Continue increasing to the preset voltage and hold for 25-35 seconds, allowing the PEN and silicon battery to adhere tightly, eliminating microscopic gaps.

[0058] Step 2: Electrostatic adsorption bonding of PEN with perovskite solar cells ① Maintain the electrostatic adsorption state between the silicon cell and the PEN. Use a visual alignment system to move the rigid perovskite cell directly above the PEN, adjusting its orientation to align the center of the perovskite cell with the center of the PEN, with the bonding surface (transfer layer) facing the PEN; ② Adjust the initial distance between the perovskite cell and the PEN to 2-4 mm to ensure they are parallel; ③ Switch the electrostatic generator to double-sided discharge mode (facing both sides of the PEN simultaneously), or activate the electrostatic generator on the perovskite cell side separately, using a gradient voltage ramp-up mode: first ramp up to 50% of the preset voltage and hold for 5 seconds; ④ Slowly decrease the distance at a rate of 0.2-0.4 mm / s until the perovskite cell and PEN are in slight contact, monitoring the total adsorption force (the resultant force between the PEN and the two cells) in real time, ensuring it is ≤20N (to avoid excessive pressure damaging the perovskite layer); ⑤ Rise to the preset voltage and hold for 25-35 seconds to ensure the PEN and perovskite cell are tightly bonded, forming a complete stacked structure of "perovskite cell / PEN / silicon cell".

[0059] Adsorption stability verification: After bonding, maintain a stable electrostatic field and verify the effect using the following methods: ① Visual inspection: Observe each interface (perovskite-PEN, PEN-silicon) with the naked eye or microscope to ensure there are no bubbles, gaps, or misalignments; rigid perovskite cells should have no chipping or cracks; and PEN should have no wrinkles or damage. ② Adhesion force test: Test the overall peel force using a tensile tester to ensure ≥6N / cm (≥4N / cm for small-area cells) and no delamination. ③ Preliminary electrical test: Test the open-circuit voltage (V) of the stacked cells. on ), short-circuit current (J) s c ), ensure V onNo significant decrease (≤5%), ruling out the problem of increased recombination of interfacial carriers; ④ Flatness retest: The overall flatness of the stacked layers is tested by a laser profilometer, with an error of ≤15μm, to ensure that there is no stress concentration caused by local protrusions.

[0060] IV. Post-processing stage: Static electricity elimination and encapsulation reinforcement The core of this stage is to eliminate residual static electricity, reinforce the stacked structure, protect the flexible PEN from environmental corrosion, and improve long-term stability.

[0061] 4.1 Elimination of residual static electricity After turning off the static electricity generating device, start the ion fan to blow on the surface of the stacked battery (blowing distance 10-20cm, time 3-5 minutes), focusing on blowing on the edge area of ​​PEN to eliminate residual static electricity and ensure that the residual voltage on the surface is ≤50V; avoid residual static electricity causing dust adsorption or electrostatic breakdown during subsequent packaging.

[0062] 4.2 Edge reinforcement and overall encapsulation Edge reinforcement: To improve the mechanical stability of the stacked structure, transparent epoxy adhesive is used to seal the edges of the stacked cells (the part exceeding PEN) (dispensing spacing 5-10mm, adhesive dot diameter 1-2mm), with an adhesive layer thickness ≤50μm, to prevent the adhesive from seeping into the middle bonding area and contaminating the PEN; after dispensing, it is cured at room temperature for 30 minutes, or UV cured (wavelength 365nm, light intensity 500mW / cm², time 60 seconds).

[0063] V. Performance Testing The photoelectric performance of the stacked perovskite-silicon tandem solar cell device was tested, and the results are shown in Table 1 and 2. Figure 5 As shown.

[0064] Table 1. Photoelectric performance parameters of electrostatically adsorbed rigid perovskite-silicon tandem solar cells

[0065] Note: In the table, JSC: short-circuit current density; VOC: open-circuit voltage; FF: fill factor; PCE: power conversion efficiency.

[0066] Example 4: Preparation of perovskite-silicon four-terminal tandem solar cells by electrostatic adsorption method Same as Example 3, except that the perovskite battery uses the flexible perovskite battery prepared in Example 1.

[0067] The photoelectric performance test results of the flexible perovskite-silicon tandem solar cell device prepared in this embodiment are shown in Table 2 and... Figure 6 As shown.

[0068] Table 2. Photoelectric performance parameters of electrostatically adsorbed flexible perovskite-silicon tandem solar cells

[0069] Comparative Example 1: Preparation of perovskite-silicon four-terminal tandem solar cells by resin adhesive bonding The perovskite and crystalline silicon solar cells used in this comparative example are the same as those in Example 3, and the specific preparation methods are as follows: I. Battery component pretreatment: Same as in Example 3.

[0070] II. Resin Adhesive Selection and Pretreatment: Key requirements for adhesive selection: ① Optical performance: transmittance ≥ 92% (300~1200nm spectral range), refractive index 1.45~1.55, matching the refractive index of the two battery substrates to reduce light reflection loss; ② Adhesion performance: shear strength ≥ 1.5MPa, glass transition temperature (Tg) ≥ 60℃, suitable for outdoor high and low temperature environments; ③ Stability: excellent resistance to damp heat (no yellowing or cracking after 1000 hours at 85℃ and 85%RH), no volatile small molecules, and does not chemically react with the perovskite layer or silicon materials; ④ Curing characteristics: UV-curable resin adhesives are preferred (short curing time and high efficiency). If the perovskite layer is sensitive to UV, visible light curing or low-temperature thermosetting resin adhesives (curing temperature ≤ 60℃) can be selected.

[0071] Pretreatment of adhesive materials: ① Stirring and degassing: Pour the resin adhesive into a clean container and stir at low speed (500~800r / min) for 5~10 minutes with a magnetic stirrer. Then place it in a vacuum drying oven for degassing (vacuum degree ≤-0.09MPa) for 10~15 minutes to completely remove air bubbles in the adhesive and avoid air bubble defects at the interface after bonding; ② Viscosity adjustment: Adjust the viscosity of the adhesive material according to the coating method. The suitable viscosity for spraying is 50~100mPa·s, and the suitable viscosity for dot / scrape coating is 200~500mPa·s. It can be adjusted by adding a special thinner (≤5%). Avoid excessive thinner from affecting the bonding strength.

[0072] III. Adhesion System Debugging Equipment composition: The core equipment includes an adhesive coating device (sprayer / dispenser / scraper), a vision alignment system, a pressure bonding platform, and a curing device (UV lamp / low temperature oven); the pressure bonding platform must have a constant temperature function (accuracy ±2℃) and an adjustable pressure range of 0.1~0.5MPa to ensure uniform bonding pressure.

[0073] Preset parameters: ① Coating parameters: Spraying / dispensing rate 5~10mm / s, coating amount controlled at 0.5~1.0mg / cm² (ensuring the final adhesive layer thickness is 10~50μm); ② Bonding parameters: Preset bonding pressure 0.2~0.3MPa, bonding time 30~60 seconds, platform temperature 25~30℃ (room temperature curing system); ③ Curing parameters: UV curing system preset wavelength 365~405nm, light intensity 500~1000mW / cm², curing time 30~120 seconds; low temperature thermosetting system preset temperature 50~60℃, curing time 30~60 minutes.

[0074] IV. Resin Adhesive Bonding Process This stage is crucial for achieving reliable bonding between the two batteries. The key involves precise adhesive application, alignment and bonding, pressure degassing, and controlled curing to ensure a uniform adhesive layer and a tight interface. The specific steps are as follows: 2.1 Precise application of resin adhesive ① Spray UV-curable resin adhesive onto the bonding surface of the crystalline silicon cell to form a uniform mist coating. Use a thickness scraper (10-50μm gap) to smooth the surface, ensuring that the adhesive covers the entire bonding surface without any missed areas; ② Allow the crystalline silicon cell to stand after applying the adhesive: After applying the adhesive, let the crystalline silicon cell stand for 2-5 minutes to allow the adhesive to flow naturally and further remove residual air bubbles. The standing environment must be kept clean (cleanliness level ≥1000) and free from airflow interference.

[0075] 2.2 Battery alignment and bonding, and pressurized degassing ① Adjust the position of the perovskite solar cell to ensure precise alignment of the bonding surfaces of both cells. The bottom of the perovskite solar cell should correspond to the bonding surface (or the hollowed-out electrode layer) of the crystalline silicon solar cell, with no intersecting or obstructing electrode grid lines to ensure a smooth light transmission path. ② Slow bonding: Control the perovskite solar cell to slowly lower itself in a direction parallel to the crystalline silicon solar cell, stopping after contact with the adhesive layer to avoid rapid bonding that could generate air bubbles. Allow the adhesive layer to spread evenly, removing any residual air bubbles at the interface, while ensuring the adhesive layer thickness is controlled between 10 and 50 μm (too thin a layer will affect the bonding strength, while too thick a layer will increase light loss).

[0076] 2.3 Resin Adhesive Curing Select the appropriate curing method based on the type of adhesive. The key is to control the curing parameters to avoid insufficient or excessive curing, which would affect the bonding performance and battery stability. Place the laminated battery under a UV curing lamp, adjust the lamp distance to 10-20cm, and cure according to the preset light intensity (500-1000mW / cm²) and time (30-120 seconds). During the curing process, the battery can be slightly rotated to ensure uniform curing. If the perovskite layer is sensitive to UV, a UV-blocking film (allowing only visible light to pass through) needs to be covered on the perovskite side, and a visible light curing adhesive should be selected. 2.4 Adhesion Reliability Verification After curing, the bonding effect was verified by the following methods: ① Visual inspection: The interface was observed with the naked eye or under a microscope to ensure there were no bubbles, gaps, adhesive overflow, or cell misalignment, and the flexible perovskite cell showed no deformation; ② Mechanical testing: The interface shear strength was tested using a tensile tester to ensure ≥1.5MPa, peel force ≥5N / cm (≥8N / cm for large-area cells), and no interface delamination. V. Post-processing stage The core of this stage is to remove excess adhesive residue, improve the environmental stability of the device, complete the final performance test, and ensure that the product meets the application requirements.

[0077] 3.1 Removal of excess adhesive residue If adhesive residue overflows from the edge of the battery after curing, gently wipe it away with a lint-free cloth dampened with a small amount of anhydrous ethanol, avoiding excessive force that could damage the battery edge; after wiping, blow it dry with nitrogen to ensure no ethanol residue remains.

[0078] 3.2 Final Performance Test See Figure 4 The structure of the perovskite-silicon tandem solar cell device stacked according to the above method includes a perovskite solar cell device 1, a UV-curable resin adhesive 4, and a crystalline silicon solar cell device 3.

[0079] The photoelectric performance test results of the tandem solar cell device prepared in this comparative example are shown in Table 3 and... Figure 7 As shown.

[0080] Table 3. Photoelectric performance parameters of resin-bonded tandem solar cells

[0081] Comparative Example 2: Directly stacked perovskite-silicon four-terminal tandem solar cells The perovskite and crystalline silicon cells used in this comparative example are the same as in Example 3. The difference is that the flexible perovskite and silicon cells are directly stacked together for encapsulation, without electrostatic adsorption or adhesive between them. The photoelectric performance test results are shown in Table 4 and... Figure 8 As shown.

[0082] Table 4. Photoelectric performance parameters of directly stacked tandem solar cells

[0083] Perovskite solar cells and silicon solar cells are directly stacked without any adhesive to hold them together. When the two layers of cells are subjected to vibration, impact or bending, they will experience relative displacement, friction or even collision. At the same time, they cannot be completely adsorbed and bonded together, resulting in air bubbles and refractive index mismatch at the interface, which leads to significant optical loss and a substantial reduction in transmittance.

[0084] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, any improvements and modifications made based on the core ideas of the present invention without departing from the spirit and scope of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A mechanical stacking method for perovskite-silicon tandem solar cells, characterized in that: The mechanical stacking method involves electrostatically adsorbing the top perovskite cell and the bottom crystalline silicon cell onto the two sides of a flexible material to complete the stacking of the top and bottom cells. The adsorption surface of the perovskite cell is the surface of the transparent conductive substrate layer of the perovskite cell, and the adsorption surface of the crystalline silicon cell is the surface of the crystalline silicon cell encapsulation glass. The adsorption surface of the crystalline silicon cell is provided with hollowed-out metal grid electrodes. The thickness of the flexible material is 15-40 μm.

2. The method according to claim 1, characterized in that: The flexible material is selected from at least one of PEN and its copolymers, PET, PBT, COP, PI, and PC.

3. The method according to claim 1, characterized in that: The perovskite-silicon tandem solar cell's packaging structure, from top to bottom, includes a perovskite solar cell device, a flexible material layer, and a crystalline silicon solar cell device. The electrical connection method of the perovskite-silicon tandem solar cell is a four-terminal tandem solar cell.

4. The method according to claim 3, characterized in that: The perovskite solar cell device has a structure including a formal nip structure and an inverted pin structure. The formal nip structure includes a transparent conductive substrate layer → electron transport layer → perovskite light-absorbing layer → hole transport layer → metal electrode → cover glass. The inverted nip structure includes a transparent conductive substrate layer → hole transport layer → perovskite light-absorbing layer → electron transport layer → metal electrode → cover glass.

5. The method according to claim 3, characterized in that: The structure of the crystalline silicon solar cell device includes encapsulation glass → encapsulation film → crystalline silicon solar cell → encapsulation film → encapsulation glass.

6. The method according to claim 1, characterized in that: The grid height of the hollow metal grid electrode is 2±1μm, and the electrode hollowness rate is ≥80%.

7. The method according to claim 1, characterized in that: The mechanical stacking method includes the following steps: Step 1: Pre-treatment of battery components: Clean the adsorption surfaces of perovskite and crystalline silicon batteries, and prepare hollow metal grid electrodes on the adsorption surface of the crystalline silicon battery. Step 2: The perovskite solar cell pretreated in Step 1 is electrostatically adsorbed onto the upper surface of the PEN film using an electrostatic generation device. Step 3: The crystalline silicon cell pretreated in Step 1 is electrostatically adsorbed onto the lower surface of the PEN film using an electrostatic generation device. Step 4: After eliminating residual static electricity using an electrostatic eliminator, the battery is packaged to obtain the perovskite-silicon tandem battery.

8. The method according to claim 7, characterized in that: The peel force between the perovskite cell or crystalline silicon cell and the PEN film is 0.1-20N.

9. The method according to claim 7, characterized in that: The output voltage of the electrostatic generator is 5-30KV.

10. The method according to claim 7, characterized in that: The electrostatic adsorption time is 10-20 seconds, and the adsorption force is 0.1-20N.

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