A four-terminal perovskite-crystalline silicon tandem solar cell module and a method of manufacturing the same

Abstract

The present application belongs to the technical field of laminated solar cell modules, and relates to a four-terminal perovskite-crystalline silicon laminated solar cell module and a preparation method thereof. The four-terminal peroviskite-crystalline silicon laminated solar cell module comprises, from top to bottom, a top photovoltaic glass, a top cell optical adhesive layer, a top peroviskite subcell, a fluorine-containing composite spacer layer, a bottom crystalline silicon subcell, a bottom cell optical adhesive layer and a bottom backboard. The fluorine-containing composite spacer layer comprises, from top to bottom, an end group modified fluorine-containing adhesive layer, a PCTFE core insulating layer and a low refractive porous anti-reflection layer. The preparation material of the end group modified fluorine-containing adhesive layer is an end group modified vinylidene fluoride copolymer, the preparation material of the PCTFE core insulating layer is poly chlorotrifluoroethylene (PCTFE), and the preparation material of the low refractive porous anti-reflection layer is a polyvinylidene fluoride (PVDF) containing a porogen. The present application improves the long-term reliability and photoelectric conversion efficiency of the four-terminal peroviskite-crystalline silicon laminated solar cell module.

Description

Technical Field

[0001] This invention belongs to the field of tandem solar cell module technology, and specifically relates to a four-terminal perovskite-crystalline silicon tandem solar cell module and its preparation method. Background Technology

[0002] To overcome the efficiency bottleneck of single-junction solar cells, tandem solar cells are formed by stacking wide-bandgap perovskite sub-cells (top cells) with narrow-bandgap crystalline silicon sub-cells (bottom cells), becoming a recognized next-generation high-efficiency technology in the photovoltaic industry. Tandem solar cells can be classified into two configurations based on their electrical connection method: two-terminal (2T) and four-terminal (4T). In the 4T tandem configuration, an intermediate spacer layer must be set between the top and bottom cells. This layer needs to meet the following requirements simultaneously: First, it should serve as an electrical insulation layer between the two independently operating sub-cells to prevent short circuits between the top and bottom electrodes; second, it should serve as a water-blocking layer to prevent external moisture from longitudinally penetrating the perovskite layer, as perovskite materials are extremely sensitive to moisture, and even trace amounts of moisture can induce their decomposition and failure; third, it should serve as an optical coupling layer to allow long-wavelength light transmitted through the top cell to enter the bottom cell with the lowest possible reflection loss.

[0003] Fluorinated polymers, such as polyvinyl chloride trifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), and their copolymers, are considered ideal candidates for this intermediate spacer layer due to their extremely low water vapor transmission rate (WVTR), excellent electrical insulation properties, and chemical inertness. Literature reports that orientation-optimized PCTFE films can achieve WVTRs as low as approximately 0.3–0.5 g / (m²·day), significantly superior to conventional polymer films such as PET (approximately 10–25 g / (m²·day)) and PVC (approximately 5–15 g / (m²·day)). Thin-film photovoltaic / perovskite water vapor-sensitive modules typically have even more stringent requirements for the barrier film (generally requiring values ​​in the 10⁻³ g / (m²·day) range or even lower). However, directly using single-layer fluorinated films as the spacer layer in 4T tandem cells presents serious and interconnected technical defects, making it difficult to meet the requirements for long-term reliable outdoor operation. Specifically, existing single-layer fluorinated films directly used as the spacer layer in 4T tandem cells have the following problems: (I) The Achilles' heel of interfacial adhesion in fluorinated materials Fluorinated polymers exhibit extremely low surface energy (both hydrophobic and oleophobic) due to the strong electronegativity of the CF bond. Their interfacial adhesion to the perovskite top electrode (typically ITO transparent conductive oxide or a thin metal) and to the conventional encapsulant (such as EVA or POE) on the silicon substrate side is extremely poor, with peel strength typically below 2 N / cm. Under outdoor diurnal temperature variations and seasonal thermal cycling, the cyclic shear stress generated by the mismatch in the thermal expansion coefficients of the various layers easily leads to physical delamination first at the fluorinated film interface, subsequently initiating moisture intrusion channels and ultimately causing module failure.

[0004] (ii) Aging induced by high-frequency parasitic capacitance and electrostatic coupling In a 4T stacked configuration, the top and bottom cells operate independently using MPPT (Multi-Pulse Test), with unequal operating voltages and high-frequency ripple. The two sub-electrodes at different potentials are placed opposite each other across an intermediate insulating layer, essentially forming a parallel-plate capacitor structure. Under high-frequency voltage fluctuations, this structure generates significant parasitic capacitance and displacement current, increasing leakage current losses and establishing an alternating electric field within the perovskite layer. This accelerates the migration of mobile ions (such as I⁻ and MA⁺) in the perovskite, inducing potential-induced degradation (PID) aging and shortening module lifespan.

[0005] (iii) Optical reflection loss caused by refractive index mismatch The refractive index of pure fluorine-containing materials is typically low (n≈1.35~1.40), while the refractive index of photovoltaic glass is about 1.52, that of ITO is about 1.8~2.0, and that of crystalline silicon is even higher. When long-wavelength light passing through the top cell passes through the "low-high" abrupt interface of "high refractive index electrode / low refractive index fluorine-containing film / high refractive index bottom cell", significant Fresnel reflection loss occurs at each interface, accumulating to 4%~8%, directly reducing the effective light intake of the bottom cell and the overall efficiency of the tandem module.

[0006] (iv) Chemical corrosion risk introduced by encapsulating adhesive If traditional encapsulating adhesives (such as EVA) are introduced on both sides of the fluorinated film to improve the aforementioned adhesion problem, the EVA will degrade under long-term photothermal effects and release acidic products such as acetic acid. These acidic substances will corrode the perovskite material and its electrodes, causing irreversible performance degradation. Therefore, simply "adding adhesive" cannot fundamentally solve the problem; instead, it introduces new failure factors.

[0007] In summary, when a single-layer fluorinated film is directly used as the spacer layer of a 4T stacked battery in the existing technology, there are irreconcilable contradictions between water-blocking insulation performance and interface adhesion performance, as well as between electrical insulation and optical coupling. There is an urgent need for a new spacer layer structure and its encapsulation process that can take into account the above multiple functions. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a four-terminal perovskite-crystalline silicon tandem solar cell module and its preparation method, which can simultaneously achieve: extremely low water vapor transmission rate and absolute electrical insulation, super strong interfacial adhesion and stress release capability, low-reflection optical coupling, and suppression of high-frequency parasitic capacitance, thereby improving the long-term outdoor reliability and photoelectric conversion efficiency of the four-terminal perovskite-crystalline silicon tandem solar cell module.

[0009] This invention is implemented as follows: a four-terminal perovskite-crystalline silicon tandem solar cell module is provided, the internal structure of which includes, from top to bottom, a top photovoltaic glass layer, a top cell optical adhesive layer, a top perovskite sub-cell, a bottom crystalline silicon sub-cell, a bottom cell optical adhesive layer, and a bottom backsheet, stacked sequentially. A fluorinated composite spacer layer is disposed between the top perovskite sub-cell and the bottom crystalline silicon sub-cell. The fluorinated composite spacer layer is composed of, from top to bottom, an end-modified fluorinated adhesive layer, a PCTFE core insulating layer, and a low-refractive-index porous anti-reflection layer; wherein, the end-modified... The modified fluorinated adhesive layer is made of end-group modified vinylidene fluoride copolymer, the PCTFE core insulating layer is made of polyvinyl chloride trifluoroethylene (PCTFE), and the low refractive index porous antireflection layer is made of polyvinylidene fluoride containing a pore-forming agent. Antireflection anchoring microstructures are provided on the upper and / or lower surfaces of the fluorinated composite spacer layer. The period of the antireflection anchoring microstructure is smaller than the response cutoff wavelength of the underlying crystalline silicon sub-cell, and its height is 150~600nm. The height-to-period ratio of the antireflection anchoring microstructure is 1.0~3.0.

[0010] Furthermore, the fluorinated composite spacer layer is prepared by the following method: a three-layer composite spacer film with a fluorinated adhesive layer, a PCTFE core insulating layer and a low refractive index porous antireflection layer is generated by extrusion molding, and then the fluorinated adhesive layer is modified by corona-assisted treatment to obtain an end-modified fluorinated adhesive layer, thereby obtaining the fluorinated composite spacer layer.

[0011] Furthermore, the shape of the anti-reflection anchoring microstructure can be any one of a pyramid array, a conical array, or a moth-eye array.

[0012] Furthermore, an effective power generation area and an edge blanking area are provided on the four-terminal perovskite-crystalline silicon tandem solar cell module. The edge blanking area is located at the four edges of the effective power generation area. The fluorine-containing composite spacer layer located in the edge blanking area is sealed and bonded to the top perovskite sub-cell and the bottom crystalline silicon sub-cell respectively by laser melting.

[0013] Furthermore, the width of the edge blank area is 100~300μm.

[0014] Furthermore, the pore-forming agent is ammonium carbonate or ammonium bicarbonate.

[0015] This invention is implemented as follows, and also provides a method for fabricating a four-terminal perovskite-crystalline silicon tandem solar cell module as described above, comprising the following steps: Step 1: Pre-fabricate the top-layer perovskite sub-cell and the bottom-layer crystalline silicon sub-cell separately; Step 2: A three-layer composite spacer film with a fluorinated adhesive layer, a PCTFE core insulating layer and a low-refractive-index porous antireflection layer is prepared by co-extrusion casting. Then, the fluorinated adhesive layer is modified by corona-assisted treatment to obtain an end-modified fluorinated adhesive layer, thereby obtaining a fluorinated composite spacer layer. Step 3: Stack the bottom backsheet, bottom cell optical adhesive layer, bottom crystalline silicon sub-cell, fluorine-containing composite spacer layer, top perovskite sub-cell, top cell optical adhesive layer, and top photovoltaic glass layer together in sequence, and then place them in a laminator for vacuum heating lamination; maintain a temperature of 110~140℃ and a pressure of 40~60kPa during the lamination process, and the lamination time is 15~30min; until the fabrication of the four-terminal perovskite-crystalline silicon tandem solar cell module is completed.

[0016] Furthermore, in step two, the surface of the prepared fluorinated composite spacer layer is texturized. The treatment method is as follows: according to the requirements, anti-reflection anchoring microstructures are prepared on the upper and / or lower surfaces of the fluorinated composite spacer layer. The period of the anti-reflection anchoring microstructure is less than the response cutoff wavelength of the underlying crystalline silicon sub-cell, its height is 150~600nm, and the height-to-period ratio of the anti-reflection anchoring microstructure is 1.0~3.0.

[0017] Furthermore, in step three, the laminated four-terminal perovskite-crystalline silicon tandem solar cell module is subjected to laser melting treatment. The laser melting treatment method is as follows: the edge blank area is scanned by laser melting, so that the surface of the fluorine-containing composite spacer layer is locally melted, so that it is sealed and bonded to the surface of the adjacent top perovskite sub-cell and bottom crystalline silicon sub-cell respectively.

[0018] Compared with the prior art, the four-terminal perovskite-crystalline silicon tandem solar cell module and its preparation method of the present invention include, from top to bottom, a top photovoltaic glass, a top cell optical adhesive layer, a top perovskite sub-cell, a fluorinated composite spacer layer, a bottom crystalline silicon sub-cell, a bottom cell optical adhesive layer, and a bottom backsheet. The fluorinated composite spacer layer is composed of, from top to bottom, an end-modified fluorinated adhesive layer, a PCTFE core insulating layer, and a low-refractive-index porous antireflection layer. The end-modified fluorinated adhesive layer is made of end-modified vinylidene fluoride copolymer, the PCTFE core insulating layer is made of polyvinyl chloride trifluoroethylene (PCTFE), and the low-refractive-index porous antireflection layer is made of polyvinylidene fluoride (PVDF) containing a pore-forming agent. This invention employs a fluorinated composite spacer layer. Through the polar grafting groups of the end-group modified fluorinated adhesive layer, chemical bonding is formed with the inorganic layer of the top battery. Mechanical anchoring is achieved through the anti-reflection anchoring micro / nano structure with adjacent optical adhesives / electrodes, increasing the interfacial peel strength from less than 2 N / cm in traditional pure fluorinated films to over 20 N / cm. The PCTFE core insulating layer provides extremely low water vapor permeability and absolute electrical insulation. The porous low-refractive-index design of the low-refractive-index porous anti-reflection layer and the construction of the anti-reflection anchoring micro / nano structure create a refractive index gradient layer, reducing interfacial reflection loss to below 0.5%. This invention simultaneously solves multiple problems associated with pure fluorinated materials, including non-stickiness, optical mismatch, high-frequency parasitic capacitance-induced degradation (PID), and acid corrosion of perovskite by the encapsulating adhesive. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the internal structure of the four-terminal perovskite-crystalline silicon tandem solar cell module of the present invention; Figure 2 for Figure 1 A schematic diagram illustrating the stacking principle of the middle and top perovskite sub-cells, the fluorine-containing composite spacer layer, and the bottom crystalline silicon sub-cells; Figure 3 for Figure 1 Schematic diagram of the anti-reflection anchoring microstructure on the upper and lower surfaces of the fluorine-containing composite spacer layer; Figure 4 A top view schematic diagram illustrating the laser self-fusion principle of the edge blank area of ​​the four-terminal perovskite-crystalline silicon tandem solar cell module. Figure 5 This is a comparison curve of the refractive index distribution along the thickness direction of the fluorinated composite spacer layer in Example 2 and Comparative Example 1 of the present invention; Figure 6 The bar chart shows the comparison of the interface peeling strength of the four-terminal perovskite-crystalline silicon tandem solar cell modules prepared in Examples 1-3 and Comparative Examples 1-2 of the present invention. Figure 7The graph shows a comparison of the interface reflectance spectra of the four-terminal perovskite-crystalline silicon tandem solar cell modules prepared in Example 2 and Comparative Example 1 of this invention.

[0020] The symbols in the image are as follows: 1. Top photovoltaic glass; 2. Top cell optical adhesive layer; 3. Top perovskite sub-cell; 4. Fluorine-containing composite spacer layer; 5. Bottom crystalline silicon sub-cell; 6. Bottom cell optical adhesive layer; 7. Bottom backsheet; 8. Anti-reflection anchoring microstructure; 9. Infrared laser; A. End-base modified fluorinated adhesive layer; B. PCTFE core insulation layer; C. Low refractive index porous anti-reflection layer; D. Effective power generation zone; E. Edge blanking zone; h, the height of the anti-anchoring microstructure; p, the period of the anti-anchoring microstructure.

[0021] The arrowed lines in the diagram indicate the path of light or the direction of the laser beam. Detailed Implementation

[0022] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0023] Please refer to the following at the same time Figures 1-3 As shown, a preferred embodiment of the four-terminal perovskite-crystalline silicon tandem solar cell module of the present invention has an internal structure comprising, from top to bottom, a top photovoltaic glass 1, a top cell optical adhesive layer 2, a top perovskite sub-cell 3, a fluorine-containing composite spacer layer 4, a bottom crystalline silicon sub-cell 5, a bottom cell optical adhesive layer 6, and a bottom backsheet 7.

[0024] The fluorinated composite spacer layer 4 consists of, from top to bottom, an end-modified fluorinated adhesive layer A, a PCTFE core insulating layer B, and a low-refractive-index porous antireflective layer C. The end-modified fluorinated adhesive layer A is made of end-modified ultrathin vinylidene fluoride copolymer; the PCTFE core insulating layer B is made of highly crystalline polyvinyl chloride (PCTFE); and the low-refractive-index porous antireflective layer C is made of polyvinylidene fluoride (PVDF) containing a porogen. The porogen is ammonium carbonate or ammonium bicarbonate.

[0025] The fluorinated composite spacer layer 4 is prepared by the following method: a three-layer composite spacer film with a fluorinated adhesive layer, a PCTFE core insulating layer B and a low refractive index porous antireflection layer C is generated by extrusion molding, and then the fluorinated adhesive layer is modified by corona-assisted treatment to obtain an end-modified fluorinated adhesive layer A, thereby obtaining the fluorinated composite spacer layer 4.

[0026] In this layer, the end-group modified fluorinated adhesive layer A faces the perovskite top cell and is made of an ultrathin vinylidene fluoride copolymer that has undergone end-group modification (e.g., maleic anhydride grafting). The polar groups (anhydrides, carboxyl groups, etc.) introduced into its molecular chain can chemically bond or strongly polarly interact with hydroxyl groups, oxygen vacancies, etc. on the surface of the inorganic transport layer / transparent electrode on one side of the top perovskite sub-cell 3, thereby significantly improving the interfacial adhesion. At the same time, this layer has a relatively high dielectric constant, which can, to a certain extent, regulate and weaken the interlayer electric field and suppress the influence of high-frequency parasitic capacitance on the perovskite.

[0027] The PCTFE core insulation layer B uses highly crystalline polyvinyl chloride (PCTFE) as the main membrane. The extremely low water vapor permeability of PCTFE provides longitudinal water barrier protection for the core and serves as an absolute electrical insulation layer, isolating the top and bottom battery electrodes.

[0028] Among them, the low-refractive-index porous antireflection layer C faces the bottom crystalline silicon sub-cell and is a submicron porous fluorinated polymer layer. By controlling its porosity (pore size and volume fraction) to adjust its equivalent refractive index, the refractive index of the fluorinated composite spacer layer 4 smoothly transitions from the PCTFE core insulating layer B to the bottom crystalline silicon sub-cell 5 side along the thickness direction, achieving refractive index matching with the substrate material, reducing reflection loss and enhancing light trapping.

[0029] Anti-reflection anchoring microstructures 8 are disposed on the upper and / or lower surfaces of the fluorine-containing composite spacer layer 4. The period p of the anti-reflection anchoring microstructure 8 is smaller than the response cutoff wavelength of the underlying crystalline silicon sub-cell 5, which is approximately 1100 nm for crystalline silicon, and the period p is 100~400 nm. The height h of the anti-reflection anchoring microstructure 8 is 150~600 nm, and the ratio of the height h of the anti-reflection anchoring microstructure 8 to the period p is 1.0~3.0. Figure 3 As shown.

[0030] Specifically, the shape of the anti-reflection anchoring microstructure 8 is any one of a pyramid array, a conical array, or a moth-eye array.

[0031] The anti-reflection anchoring microstructure 8 produces a dual effect: (1). Optical effect: The subwavelength microstructure is optically equivalent to forming a transition layer with a refractive index that gradually changes from air / adjacent medium to the spacer layer, which physically eliminates the abrupt interface, reduces the interface reflection loss to below 0.5%, and traps long-wavelength light.

[0032] (2). Mechanical effect: During the lamination process, the adjacent optical adhesive or electrode material fills the depressions of the micro-nano structure under the action of pressure and temperature. After curing, it forms a physical mechanical anchoring with the fluorine-containing composite spacer layer 4, which makes the interfacial peel strength jump from less than 2N / cm to more than 20N / cm, fundamentally suppressing the risk of delamination.

[0033] An effective power generation area D and an edge blanking area E are provided on the four-terminal perovskite-crystalline silicon tandem solar cell module. The edge blanking area E is located around the perimeter of the effective power generation area D. The fluorine-containing composite spacer layer 4 located in the edge blanking area E is sealed and bonded to the top perovskite sub-cell 3 and the bottom crystalline silicon sub-cell 5 respectively by laser melting. Please refer to [reference needed] for the setting of the effective power generation area D and the edge blanking area E. Figure 4 As shown.

[0034] Specifically, the width of the edge blank area E is 100~300μm.

[0035] In the edge blank area E, an infrared laser with a specific wavelength (e.g., the approximately 1.7 μm band) that has a specific absorption peak for the CF bond is used for in-situ scanning. The laser energy is precisely absorbed by the fluorine-containing composite spacer layer 4 and causes it to partially melt, achieving molecular-level in-situ homogeneous fusion bonding with the edge protective layers of the upper and lower adjacent layers. This forms a chemical bond-level, absolutely sealed ("dead seal") around the tandem solar cell module without any glue.

[0036] Please refer to again Figure 1 As shown, the present invention also discloses a method for preparing a four-terminal perovskite-crystalline silicon tandem solar cell module as described above, comprising the following steps: Step 1: Pre-fabricate the top perovskite sub-cell 3 and the bottom crystalline silicon sub-cell 5 separately.

[0037] Step 2: A three-layer composite spacer film with a fluorinated adhesive layer, a PCTFE core insulating layer B, and a low-refractive-index porous antireflection layer C is prepared by co-extrusion casting. Then, the fluorinated adhesive layer is modified by maleic anhydride grafting (or other polar groups) using a corona-assisted method to obtain end-group modified fluorinated adhesive layer A, thereby obtaining fluorinated composite spacer layer 4.

[0038] Step 3: Stack the following layers sequentially: bottom backsheet 7, bottom cell optical adhesive layer 6, bottom crystalline silicon sub-cell 5, fluorine-containing composite spacer layer 4, top perovskite sub-cell 3, top cell optical adhesive layer 2, and top photovoltaic glass 1. Then, place them in a laminator for vacuum heating lamination. During lamination, maintain a temperature of 110-140℃ and a pressure of 40-60 kPa for 15-30 minutes. Continue this process until the fabrication of the four-terminal perovskite-crystalline silicon tandem solar cell module is complete.

[0039] In step one, the top-layer perovskite sub-cell 3 is prepared as follows: The conductive substrate layer (FTO glass) is ultrasonically cleaned and treated with ultraviolet ozone to ensure surface cleanliness and high wettability. A hole transport layer material is deposited on the treated conductive substrate surface using a solution spin-coating or slot-coating method. This layer is typically formed from PTAA, PEDOT:PSS, or self-assembled monolayers (SAMs). A perovskite thin film layer is formed on the hole transport layer using a one-step solution method or a two-step sequential deposition method. An electron transport layer material (such as SnO2, PCBM, or fullerene derivatives) is deposited on the perovskite thin film layer using a spin-coating method, followed by low-temperature annealing. A semi-transparent composite electrode (ITO or FTO, etc.) is deposited by thermal evaporation. Electrode structures are respectively set at both ends of the perovskite thin film layer, serving as the positive and negative output terminals of the top-layer perovskite sub-cell 3. A top-cell optical adhesive layer 2 is covered on the surface of the top-layer perovskite sub-cell 3, and a 1-2 cm wide butyl encapsulating adhesive is coated around the perimeter, and the top-layer photovoltaic glass 1 is then stacked on top.

[0040] In step one, the bottom-layer crystalline silicon sub-cell 5 is fabricated as follows: an n-type silicon wafer is thinned; a boron emitter is fabricated on the back side using photolithography and diffusion processes, and a phosphorus diffusion layer is fabricated on the front side, followed by surface pyramid texturing, RCA cleaning, and ONO stack passivation deposition. A transparent conductive oxide layer (such as ITO or IZO) is deposited on the light-receiving side of the bottom-layer crystalline silicon sub-cell 5 as an optical coupling interface with the fluorine-containing composite spacer layer 4. A metal bottom electrode (such as a Cr / Pd / Ag stack) is fabricated on the back side of the bottom-layer crystalline silicon sub-cell 5, and electrode lead-out is completed.

[0041] Step two also includes texturing the surface of the prepared fluorinated composite spacer layer 4. The treatment method is as follows: according to the requirements, an anti-reflection anchoring microstructure 8 is prepared on the upper and / or lower surface of the fluorinated composite spacer layer 4. The period p of the anti-reflection anchoring microstructure 8 is less than the response cutoff wavelength of the underlying crystalline silicon sub-cell 5, which is about 1100 nm for crystalline silicon. The period p is 100~400 nm, and its height h is 150~600 nm. The ratio of the height h of the anti-reflection anchoring microstructure 8 to the period p is 1.0~3.0.

[0042] Step three also includes laser melting treatment of the laminated four-terminal perovskite-crystalline silicon tandem solar cell module. The laser melting treatment method is as follows: the edge blank area E is scanned by laser melting, so that the surface of the fluorine-containing composite spacer layer 4 is partially melted, so that it is sealed and bonded to the surfaces of the adjacent top perovskite sub-cell 3 and bottom crystalline silicon sub-cell 5 respectively.

[0043] Incident light (hv) enters from the top photovoltaic glass 1 side, and after short-wavelength light is absorbed by the top perovskite sub-cell 3, long-wavelength light passes through the fluorine-containing composite spacer layer 4 and enters the bottom crystalline silicon sub-cell 5 where it is absorbed.

[0044] The fluorinated composite spacer layer 4 comprises three functional sub-layers sequentially from the top cell side to the bottom cell side along its thickness direction: an end-modified fluorinated adhesive layer A, a PCTFE core insulating layer B, and a low-refractive-index porous anti-reflection layer C. The three layers are co-extruded integrally, and the adjacent sub-layers are interpenetrating at the molecular level rather than physically bonded, thus eliminating the risk of delamination between layers.

[0045] like Figure 2 As shown, the surface of the end-modified fluorinated adhesive layer A is distributed with an ultrathin vinylidene fluoride copolymer grafted with maleic anhydride, which can form a chemical bond with the inorganic layer of the top perovskite sub-cell 3; the PCTFE core insulating layer B is highly crystalline polyvinyl chloride trifluoroethylene (PCTFE), providing water resistance and insulation; the low-refractive-index porous antireflection layer C is PVDF containing a pore-forming agent, with submicron-level closed / open pores distributed inside to reduce its equivalent refractive index. "Y"-shaped symbols are distributed on the surface of the end-modified fluorinated adhesive layer A, indicating polar graft groups introduced through end-modification to form a chemical bond with the top perovskite sub-cell 3. Small circles indicate the submicron-sized micropores distributed inside the low-refractive-index porous antireflection layer C, used to reduce the equivalent refractive index. The serrated shape on the lower surface of the low-refractive-index porous antireflection layer C indicates the antireflection anchoring microstructure 8 obtained after texturing treatment.

[0046] like Figure 3As shown, the upper and lower surfaces of the fluorinated composite spacer layer 4 are provided with anti-reflection anchoring microstructures 8. The anti-reflection anchoring microstructures 8 are pyramidal, conical, or moth-eye arrays, with a period p smaller than the response cutoff wavelength of the underlying crystalline silicon sub-cell 5, approximately 1100 nm for crystalline silicon. Preferably, the period p is 100-400 nm, and the height h of the anti-reflection anchoring microstructures 8 is 150-600 nm. The ratio of the height h to the period p is preferably 1.0-3.0. During lamination, adjacent optical adhesives / electrodes are filled into the depressions of the anti-reflection anchoring microstructures 8 under temperature and pressure and then cured, forming a mechanical anchor. Optically, the anti-reflection anchoring microstructures 8 are equivalent to a continuously graded refractive index layer, significantly reducing the reflectivity of incident light at the interface; mechanically, they significantly improve the interface's anti-peeling ability through "tooth meshing."

[0047] like Figure 4 As shown, a ring of edge blanking zone E is set around the effective power generation area D of the four-terminal perovskite-crystalline silicon tandem solar cell module. An infrared laser 9 emits a laser beam with a specific wavelength λ, for example, about 1.7 μm, corresponding to the characteristic absorption peak of the CF bond, and scans along the edge blanking zone E. The laser energy is selectively absorbed by the fluorine-containing composite spacer layer 4, causing it to partially melt and fuse with the edge protective layers of the upper and lower adjacent layers. After cooling, a continuous closed edge self-fusion zone is formed. The width of the edge blanking zone E is 100~300 μm, thereby achieving absolute sealing around the four-terminal perovskite-crystalline silicon tandem solar cell module without introducing any glue. Since the fusion only occurs in the edge blanking zone E, it does not affect the optical and electrical performance of the central effective power generation area D. This figure is used to illustrate the method of achieving glue-free edge "dead seal".

[0048] In summary, the present invention relates to a four-terminal perovskite-silicon tandem solar cell module and its preparation method, comprising a fluorinated composite spacer layer 4, on at least one surface of which a micro / nano-imprinted anti-reflection anchoring microstructure 8 is provided. The polar graft groups of the end-modified fluorinated adhesive layer A form a chemical bond with the inorganic layer of the top perovskite sub-cell 3, and the anti-reflection anchoring microstructure 8 forms a mechanical anchor with adjacent optical adhesives / electrodes, thereby increasing the interface peel strength from less than 2 N / cm in traditional pure fluorinated films to over 20 N / cm. The PCTFE core insulating layer B provides extremely low water vapor transmission and absolute electrical insulation. The porous low-refractive-index design of the low-refractive-index porous anti-reflection layer C and the construction of a refractive index gradient layer using the anti-reflection anchoring microstructure 8 reduce interface reflection loss to below 0.5%. Furthermore, infrared laser in-situ self-fusion is performed in the edge blank area E around the four-terminal perovskite-silicon tandem solar cell module, forming a chemical bond-level edge "dead seal" without adhesive. This invention simultaneously solves multiple problems such as the non-stickiness of pure fluorine-containing materials, optical mismatch, high-frequency parasitic capacitance-induced degradation (PID), and acid corrosion of perovskite by encapsulating adhesives.

[0049] The following specific embodiments further illustrate the four-terminal perovskite-crystalline silicon tandem solar cell module and its preparation method of the present invention.

[0050] Example 1: A standard three-layer fluorinated composite spacer with maleic anhydride-grafted PVDF as the end-group modified fluorinated adhesive layer. Please refer to again Figure 1 As shown, the first embodiment of the method for fabricating a four-terminal perovskite-crystalline silicon tandem solar cell module of the present invention includes the following steps: Step 11: Fabrication of the top-layer perovskite sub-cell 3 The conductive substrate (FTO glass) is ultrasonically cleaned and treated with ultraviolet ozone to ensure surface cleanliness and high wettability. A hole transport layer material, PTAA, is then deposited on the treated conductive substrate surface using a solution spin-coating or slot-coating method. MAPbI is then formed on top of the hole transport layer using a one-step solution method or a two-step sequential deposition method. 1.05 Br 1.95 Perovskite thin film layer. SnO2, an electron transport layer material, is deposited on the perovskite thin film layer via spin coating, followed by low-temperature annealing. A semi-transparent composite electrode, ITO, is deposited via thermal evaporation. Electrode structures are positioned at both ends of the perovskite thin film layer, serving as the positive and negative output terminals of the top-layer perovskite sub-cell 3. A top-cell optical adhesive layer 2 is covered on the surface of the top-layer perovskite sub-cell 3, with a 1 cm wide butyl adhesive coating around the perimeter, and a top-layer photovoltaic glass layer 1 is then laminated.

[0051] Step 12: Fabrication of the underlying crystalline silicon sub-cell 5 The n-type silicon wafer is thinned; a boron emitter is fabricated on the back side using photolithography and diffusion processes, and a phosphorus diffusion layer is fabricated on the front side. Subsequent processes include surface pyramid texturing, RCA cleaning, and ONO stack passivation deposition. A transparent conductive oxide layer (ITO) is deposited on the light-receiving side of the bottom crystalline silicon sub-cell 5, serving as the optical coupling interface with the fluorine-containing composite spacer layer 4. A Cr / Pd / Ag metal bottom electrode stack is fabricated on the back side of the bottom crystalline silicon sub-cell 5, and electrode leads are established.

[0052] Step 13: Preparation of fluorine-containing composite spacer layer 4 The end-modified fluorinated adhesive layer A is made of polyvinylidene fluoride (PVDF-g-MAH) copolymer. After three-layer co-extrusion, the surface of the end-modified fluorinated adhesive layer A is then subjected to corona-assisted maleic anhydride grafting activation, resulting in a grafting rate of approximately 1.2 wt% and a thickness of approximately 8 μm. The maleic anhydride groups are used to form chemical bonds with the ITO electrode surface of the top perovskite sub-cell 3.

[0053] The PCTFE core insulation layer B is made of highly crystalline PCTFE with a crystallinity of approximately 45% and a thickness of approximately 25 μm, serving as the core water-blocking insulation layer.

[0054] The low-refractive-index porous antireflection layer C uses PVDF containing ammonium carbonate as a pore-forming agent. Through phase separation, it forms a submicron closed-pore structure with a porosity of about 30 vol%. The equivalent refractive index is reduced from about 1.43 of PCTFE to about 1.36, and the thickness is about 10 μm.

[0055] The three raw materials are extruded into a single unit to obtain a three-layer co-extruded fluorinated composite spacer layer 4. Then, the surface of the fluorinated adhesive layer is activated by corona-assisted maleic anhydride grafting to obtain an end-modified fluorinated adhesive layer A. Subsequently, the upper and lower surfaces of the fluorinated composite spacer layer 4 are hot-pressed together using a nickel die to form a pyramid array of anti-reflection anchoring microstructures 8 with a period p≈250nm and a height h≈350nm.

[0056] Step 14: Sub-cell mechanical stacking and packaging Two independently fabricated sub-cells were mechanically stacked using an optical adhesive layer and a fluorinated composite spacer layer 4. A bottom-cell optical adhesive layer 6 was coated onto the bottom backsheet 7, and then the bottom-cell crystalline silicon sub-cell 5 was placed on top of the bottom-cell optical adhesive layer 6. The prepared fluorinated composite spacer layer 4 was then laid on the light-receiving surface of the bottom-cell crystalline silicon sub-cell 5, ensuring no air bubbles remained between them. The top-cell perovskite sub-cell 3 was then placed on top and optically aligned. The stacked structure was then placed in a laminator for vacuum heating lamination. During lamination, a temperature of 110°C and a pressure of 40 kPa were maintained, and the lamination time was 15 minutes.

[0057] Step 15: A border blank area E is set around the effective power generation area D of the tandem solar cell module. The infrared laser 9 emits a laser beam with a specific wavelength of 1.7 μm and scans along the border blank area E. The laser energy is selectively absorbed by the fluorine-containing composite spacer layer 4, causing it to partially melt and fuse with the edge protection layers of the upper and lower adjacent layers. After cooling, a continuous closed edge self-fusion region with a width of 100 μm is formed. This process continues until the fabrication of the four-terminal perovskite-crystalline silicon tandem solar cell module is completed.

[0058] The prepared four-terminal perovskite-crystalline silicon tandem solar cell module was subjected to relevant tests, and the following test results were obtained: the peel strength of the interface between the fluorinated composite spacer layer 4 and the ITO top electrode reached 21.5 N / cm; the overall water vapor transmission rate (WVTR, 38℃ / 100%RH) of the fluorinated composite spacer layer 4 was about 8×10⁻³ g / (m²·day), which was more than an order of magnitude lower than that of the undensified pure PCTFE monolayer film (about 0.3 g / (m²·day)); the average reflectivity of the interface in the visible-near infrared band was less than 0.5%; after 1000 hours of DH85℃ / RH85% dual 85% damp heat aging, the power decay of the tandem solar cell module was less than 3%, and no delamination was observed.

[0059] Example 2: Spacer layer for enhanced anti-reflection structure using moth-eye microstructure The main differences between this embodiment and Embodiment 1 are: the morphology of the antireflective anchoring microstructure 8 and the porosity of the low-refractive-index porous antireflective layer C; and the increased thickness of the PCTFE core insulating layer B to 30 μm to further improve the water-blocking margin. The porosity of the low-refractive-index porous antireflective layer C is increased to approximately 38 vol%, and the equivalent refractive index is reduced to approximately 1.33. The antireflective anchoring microstructures 8 on the upper and lower surfaces are replaced with a moth-eye array, with a period p ≈ 100 nm, a height h ≈ 150 nm, and a height h to period p ratio of approximately 1.5. During lamination, a temperature of 130 °C and a pressure of 40 kPa are maintained, and the lamination time is 15 min. The width of the edge self-welding zone is 150 μm.

[0060] The other structures and steps are the same as in Example 1, and will not be described again.

[0061] The prepared four-terminal perovskite-crystalline silicon tandem solar cell module was subjected to relevant tests, and the following test results were obtained: Due to the smoothing of the refractive index gradient of the moth-eye array, the average reflectivity of the interface was further reduced to about 0.3% (400~1100nm sunlight weighted, compared to about 6% for the bare interface); the mechanical anchoring was stronger, and the peel strength reached 23.8 N / cm; the WVTR was about 3×10⁻³g / (m²·day). Example 2 showed the best overall performance in terms of antireflection and adhesion, but the mold processing cost of the moth-eye array was relatively high.

[0062] Example 3: Low-cost fluorinated composite spacer layer with PCTFE-co-PVDF as end-group modified fluorinated adhesive layer and conical array. This embodiment 3 focuses on reducing process costs and improving mass production compatibility. The main difference between this embodiment and embodiment 1 is that the end-modified fluorinated adhesive layer A is replaced with a maleic anhydride-grafted PCTFE-co-PVDF block copolymer, which has better compatibility with the PCTFE core insulation layer B and a stronger co-extrusion interface bond. The anti-reflection anchoring microstructure 8 is changed to a conical array with a period p≈400nm and a height h≈600nm, facilitating demolding and continuous roll-to-roll production. The porosity of the low-refractive-index porous anti-reflection layer C is approximately 28 vol%. The pore-forming agent is ammonium bicarbonate. The butyl rubber width is 2 cm. The surface of the end-modified fluorinated adhesive layer A is corona-assisted maleic anhydride grafting activation, resulting in a grafting rate of approximately 1.5 wt% and a thickness of approximately 10 μm. The thickness of the PCTFE core insulation layer B is approximately 30 μm.

[0063] The other structures and steps are the same as in Example 1, and will not be described again.

[0064] The prepared four-terminal perovskite-crystalline silicon tandem solar cell module was subjected to relevant tests, and the following test results were obtained: peel strength reached 22.6 N / cm; average interface reflectivity was approximately 0.45%; and WVTR was approximately 1×10⁻² g / (m²·day). This embodiment ensures that key performance targets are met while having a wider process window and higher demolding yield, making it most suitable for large-scale mass production.

[0065] Comparative Example 1 The difference between this comparative example and Example 1 is that a single-layer PCTFE membrane with a thickness of approximately 43 μm is used as the fluorinated composite spacer layer 4, and the surface of the fluorinated composite spacer layer 4 is smooth, unmodified, and without anti-reflection anchoring microstructures. During the lamination process, the temperature is maintained at 130°C and the pressure at 50 kPa, and the lamination time is 20 min.

[0066] The other structures and steps are the same as in Example 1, and will not be described again.

[0067] The prepared four-terminal perovskite-crystalline silicon tandem solar cell module was subjected to relevant tests, and the following test results were obtained: its peel strength at the ITO interface was only about 1.8 N / cm, which is lower than the delamination risk threshold of 2 N / cm, and the average reflectivity at the interface was about 5.5%; its WVTR was about 0.3 g / (m²·day), which is in the range of excellent barrier film, but is still significantly higher than the barrier level required for perovskite-crystalline silicon tandem solar cell modules; obvious delamination was observed at the interface after 400 hours of dual 85 aging.

[0068] Comparative Example 2 The difference between this comparative example and Example 1 is that the fluorinated composite spacer layer 4 only contains the end-modified fluorinated adhesive layer A and the PCTFE core insulating layer B, without the low-refractive-index porous antireflective layer C. The thickness of the PCTFE core insulating layer B is approximately 30 μm. There is no antireflective anchoring microstructure. During the lamination process, the temperature was maintained at 140°C and the pressure at 60 kPa, and the lamination time was 25 min.

[0069] The other structures and steps are the same as in Example 1, and will not be described again.

[0070] The prepared four-terminal perovskite-crystalline silicon tandem solar cell module was subjected to relevant tests, and the following test results were obtained: the peel strength was measured to be about 9.5 N / cm, which is significantly improved compared with pure PCTFE, but still insufficient to resist thermal cycling shear stress in the long term, and the reflectivity is still relatively high (about 4%).

[0071] The test results of the four-terminal perovskite-crystalline silicon tandem solar cell modules prepared in Examples 1-3 and Comparative Examples 1-2 were compared to obtain the comparison table shown in Table 1 below (the data in the table are exemplary measured values, used to illustrate the technical effects of the present invention).

[0072] Table 1 Comparison of Relevant Test Results

[0073] As shown in Table 1 above, the interfacial peel strength of the four-terminal perovskite-crystalline silicon tandem solar cell modules prepared in Examples 1-3 is more than an order of magnitude higher than that of the pure fluorine-containing film (Comparative Example 1), and is far higher than the delamination risk threshold of 2 N / cm; at the same time, the interfacial reflectivity is reduced by about an order of magnitude. Regarding water vapor barrier properties, the pure PCTFE monolayer film (Comparative Example 1) is already an excellent barrier film (approximately 0.3 g / (m²·day)), while this invention, through core layer densification, composite structure synergy, and edge laser self-fusion to eliminate edge penetration channels, further reduces the overall WVTR by about 1-2 orders of magnitude, bringing it closer to the barrier level required for the long-term reliable operation of perovskite tandem solar cell modules. This indicates that Examples 1-3 indeed achieve a synergistic balance of water blocking, insulation, adhesion, and anti-reflection.

[0074] Please refer to Figure 5 As shown, Figure 5The horizontal axis represents the normalized position along the thickness direction of the fluorinated composite spacer layer (i.e., the spacer layer), extending from the end-group modified fluorinated adhesive layer A on the top cell side through the PCTFE core insulating layer B to the low-refractive-index porous antireflective layer C on the bottom cell side. The vertical axis represents the refractive index n. The solid line represents the refractive index distribution of Example 2 of the present invention, where the refractive index smoothly decreases from a high value on the top cell side through the end-group modified fluorinated adhesive layer A and the PCTFE core insulating layer B, and then smoothly rises again through the porous structure of the low-refractive-index porous antireflective layer C to match the bottom cell side, forming a continuous gradient. The dashed line represents the refractive index distribution of Comparative Example 1, which exhibits a sharp abrupt change in refractive index at both the light-inlet and light-outlet interfaces, as shown in the figure, resembling a step. It can be seen that the present invention eliminates the abrupt interface through gradient design, thereby reducing Fresnel reflection loss. This figure is used to demonstrate the effectiveness of the present invention in optical matching.

[0075] Please refer to Figure 6 As shown, Figure 6 The vertical axis represents the interfacial peel strength (N / cm), and the horizontal axes represent, in order, Comparative Example 1 (pure PCTFE monolayer film, 1.8 N / cm, blank filling), Comparative Example 2 (end-group modified A layer only, 9.5 N / cm, single diagonal line filling), and Examples 1-3 of the present invention (21.5, 23.8, 22.6 N / cm, cross-grid filling). The horizontal dashed line in the figure indicates the delamination risk threshold of 2 N / cm. It can be seen that Comparative Example 1 is below this threshold, and there is a risk of delamination; while the peel strength of the three Examples 1-3 of the present invention is more than an order of magnitude higher than that of the pure fluorinated film in Comparative Example 1, and is far above the threshold. This figure is used to demonstrate the significant effect of the present invention in interfacial adhesion.

[0076] Please refer to Figure 7 As shown, Figure 7 The horizontal axis represents wavelength (nm, covering 400~1100nm), and the vertical axis represents interface reflectivity (%). The dashed line represents Comparative Example 1, where the reflectivity is as high as approximately 4%~8% due to the abrupt change in refractive index. The solid line represents Example 2 (refractive index gradient combined with a double-sided anti-reflection anchoring microstructure), where the reflectivity is below approximately 0.5% across the entire wavelength range. The comparison shows that this invention maintains extremely low reflectivity across a wide spectral range, which is beneficial for increasing the light intake of the bottom cell. This figure is used to demonstrate the effectiveness of this invention in reducing reflectivity.

[0077] It should be noted that the materials, thicknesses, microstructure dimensions, and process parameters of each layer in the above embodiments are illustrative and can be replaced and adjusted by those skilled in the art within the scope of the present invention. For example, the modifying groups of the end-group modified fluorinated adhesive layer A can be carboxyl groups, epoxy groups, silane coupling groups, or other polar / reactive groups; the pore-forming method of the low-refractive-index porous antireflection layer C can be phase separation, pore-forming agent extraction, stretching pore-forming, etc.; the laser wavelength for edge welding can be selected according to the absorption peak of the fluorinated material used. These modifications do not depart from the essence of the present invention.

[0078] Compared with the prior art, the four-terminal perovskite-crystalline silicon tandem solar cell module and its preparation method of the present invention have the following characteristics: 1. Balancing extreme water resistance with superior adhesion. This invention cleverly circumvents the inherent non-stickiness of pure fluorinated materials: while retaining the PCTFE core insulation layer B for water resistance and insulation, the end-modified fluorinated adhesive layer A provides chemical bonding, and the anti-reflection anchoring microstructure 8 provides mechanical anchoring. Thus, extremely low water vapor permeability and superior interfacial adhesion are achieved simultaneously in the same layer structure, resolving the contradiction of the two being difficult to achieve at the same time.

[0079] 2. Simultaneously addressing electrical and optical mismatches. The porous low-refractive-index design of the low-refractive-index porous antireflection layer C, together with the antireflection anchoring microstructure 8, constructs a refractive index gradient layer, significantly reducing optical reflection loss; the modification and dielectric adjustment of the end-substrate modified fluorinated adhesive layer A suppresses the parasitic capacitance effect under high-frequency operation, protecting the perovskite layer from electric field-induced degradation (PID).

[0080] 3. Eliminates the need for adhesive and prevents acid corrosion. The edge blank area E achieves zero-adhesive edge sealing, completely avoiding the risk of traditional encapsulating adhesives (such as EVA) degrading and producing acetic acid that corrodes perovskite materials, thus improving the chemical stability of tandem solar cell modules from the source.

[0081] 4. The process is mass-producible and readily implementable. The three-layer structure of the fluorinated composite spacer layer 4 is integrally formed through a mature co-extrusion process, the anti-reflection anchoring microstructure 8 is mass-produced through roll-to-roll imprinting, and the edge blanking area E is completed by automated laser scanning. The overall process is highly compatible with existing photovoltaic module production lines.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A four-terminal perovskite-crystalline silicon tandem solar cell module, the internal structure of which comprises, from top to bottom, a top photovoltaic glass layer, a top cell optical adhesive layer, a top perovskite sub-cell, a bottom crystalline silicon sub-cell, a bottom cell optical adhesive layer, and a bottom backsheet, stacked sequentially from top to bottom, characterized in that, A fluorinated composite spacer layer is disposed between the top perovskite sub-cell and the bottom crystalline silicon sub-cell. The fluorinated composite spacer layer consists of, from top to bottom, an end-group modified fluorinated adhesive layer, a PCTFE core insulating layer, and a low-refractive-index porous antireflection layer. The end-group modified fluorinated adhesive layer is made of end-group modified vinylidene fluoride copolymer, the PCTFE core insulating layer is made of polyvinyl chloride trifluoroethylene, and the low-refractive-index porous antireflection layer is made of polyvinylidene fluoride containing a porogen. Antireflection anchoring microstructures are disposed on the upper and / or lower surfaces of the fluorinated composite spacer layer. The period of the antireflection anchoring microstructures is smaller than the response cutoff wavelength of the bottom crystalline silicon sub-cell, and its height is 150~600nm. The height-to-period ratio of the antireflection anchoring microstructures is 1.0~3.

0.

2. The four-terminal perovskite-crystalline silicon tandem solar cell module as described in claim 1, characterized in that, The fluorinated composite spacer layer is prepared by the following method: a three-layer composite spacer film with a fluorinated adhesive layer, a PCTFE core insulating layer and a low refractive index porous antireflection layer is generated by extrusion molding, and then the fluorinated adhesive layer is modified by corona-assisted treatment to obtain an end-modified fluorinated adhesive layer, thereby obtaining the fluorinated composite spacer layer.

3. The four-terminal perovskite-crystalline silicon tandem solar cell module as described in claim 1, characterized in that, The shape of the anti-reflection anchoring microstructure can be any one of a pyramid array, a conical array, or a moth-eye array.

4. The four-terminal perovskite-crystalline silicon tandem solar cell module as described in claim 1, characterized in that, An effective power generation area and an edge blanking area are provided on the four-terminal perovskite-crystalline silicon tandem solar cell module. The edge blanking area is located at the four edges of the effective power generation area. The fluorine-containing composite spacer layer located in the edge blanking area is sealed and bonded to the top perovskite sub-cell and the bottom crystalline silicon sub-cell respectively by laser melting.

5. The four-terminal perovskite-crystalline silicon tandem solar cell module as described in claim 4, characterized in that, The width of the edge blank area is 100~300μm.

6. The four-terminal perovskite-crystalline silicon tandem solar cell module as described in claim 1, characterized in that, The pore-forming agent is ammonium carbonate or ammonium bicarbonate.

7. A method for preparing a four-terminal perovskite-crystalline silicon tandem solar cell module as described in any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1: Pre-fabricate the top-layer perovskite sub-cell and the bottom-layer crystalline silicon sub-cell separately; Step 2: A three-layer composite spacer film with a fluorinated adhesive layer, a PCTFE core insulating layer and a low-refractive-index porous antireflection layer is prepared by co-extrusion casting. Then, the fluorinated adhesive layer is modified by corona-assisted treatment to obtain an end-modified fluorinated adhesive layer, thereby obtaining a fluorinated composite spacer layer. Step 3: Stack the bottom backsheet, bottom cell optical adhesive layer, bottom crystalline silicon sub-cell, fluorine-containing composite spacer layer, top perovskite sub-cell, top cell optical adhesive layer, and top photovoltaic glass layer together in sequence, and then place them in a laminator for vacuum heating lamination; maintain a temperature of 110~140℃ and a pressure of 40~60kPa during the lamination process, and the lamination time is 15~30min; until the fabrication of the four-terminal perovskite-crystalline silicon tandem solar cell module is completed.

8. The method for preparing a four-terminal perovskite-crystalline silicon tandem solar cell module as described in claim 7, characterized in that, Step two also includes texturing the surface of the prepared fluorinated composite spacer layer. The treatment method is as follows: depending on the requirements, anti-reflection anchoring microstructures are prepared on the upper and / or lower surfaces of the fluorinated composite spacer layer. The period of the anti-reflection anchoring microstructure is less than the response cutoff wavelength of the underlying crystalline silicon sub-cell, its height is 150~600nm, and the height-to-period ratio of the anti-reflection anchoring microstructure is 1.0~3.

0.

9. The method for preparing a four-terminal perovskite-crystalline silicon tandem solar cell module as described in claim 7, characterized in that, Step three also includes laser melting treatment of the laminated four-terminal perovskite-crystalline silicon tandem solar cell module. The laser melting treatment method is as follows: the edge blank area is scanned by laser melting, so that the surface of the fluorine-containing composite spacer layer is locally melted, so that it is sealed and bonded to the surface of the adjacent top perovskite sub-cell and bottom crystalline silicon sub-cell respectively.

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