Perovskite / crystalline silicon laminated solar cell module and preparation method thereof

Abstract

This invention provides a method for fabricating a perovskite / crystalline silicon tandem solar cell module, mainly comprising: firstly, fabricating several semi-finished crystalline silicon cells; then, back-mounting them to obtain a bottom crystalline silicon cell module; next, fabricating an intermediate connecting layer and a top layer of semi-finished perovskite cells on the bottom crystalline silicon cell module; etching and cutting from top to bottom to obtain several vertically independent and separated perovskite / crystalline silicon tandem cells; and finally, encapsulating the module to obtain the perovskite / crystalline silicon tandem solar cell module. Furthermore, this invention also discloses a perovskite / crystalline silicon tandem solar cell module fabricated using the above method. This invention integrates the fabrication processes of the bottom cell, the top cell, and the entire module, simplifying the fabrication process, significantly reducing the production cost of tandem modules, and making it suitable for industrialization.

Description

Technical Field

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

[0002] As research in the field of solar cells continues to deepen, the photoelectric conversion efficiency of single-junction solar cells (such as crystalline silicon cells, and thin-film cells made of cadmium telluride, copper indium gallium selenide, and perovskite) is constantly improving and approaching the Shockley-Queisser theoretical limit. By designing tandem solar cell structures using materials with different optical bandgap widths, the wavelength range of solar spectrum absorption and utilization by the cells can be comprehensively broadened, thereby enabling the cell efficiency to break through the Shockley-Queisser theoretical limit. In recent years, with the rapid development of the perovskite solar cell industry, crystalline silicon and perovskite have become the two most cost-effective materials for achieving high efficiency in single-junction cells, and the theoretical efficiency of tandem cells composed of these two materials can exceed 45%. Therefore, perovskite / crystalline silicon cells are the most promising technology route for next-generation industrialized photovoltaic cells. However, the current fabrication process of perovskite / crystalline silicon tandem cells is still relatively complex and costly, failing to meet the production cost requirements for industrialization. Further simplification of the fabrication process is needed to reduce its cost. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a perovskite / crystalline silicon tandem solar cell module and its fabrication method. The top layer of the perovskite / crystalline silicon tandem solar cell module (hereinafter referred to as "perovskite / crystalline silicon tandem cell module") has an optical bandgap (E) of [missing information]. g The perovskite solar cell with a relatively wide bandgap primarily utilizes high-energy (short wavelength) and medium-energy (medium wavelength) photons from the solar spectrum; the underlying layer is a crystalline silicon solar cell with a narrower bandgap (E... g =1.12eV), mainly utilizing photons in the low-to-medium energy range of the solar spectrum, including the medium and long wavelengths. This allows for more comprehensive and efficient utilization of photons across the short, medium, and long wavelength ranges of the solar spectrum, enabling cell efficiency to exceed the Shockley-Queisser theoretical limit and resulting in higher module power generation.

[0004] The fabrication process of the perovskite / crystalline silicon tandem solar cell module disclosed in this invention flexibly integrates the fabrication processes of crystalline silicon cells, perovskite cells, and modules, as summarized below: ① First, a semi-finished crystalline silicon cell is fabricated; then, the periphery of the semi-finished crystalline silicon cell is laser-edged to make its periphery electrically insulating; then, combined with the fabrication process of crystalline silicon modules, the back side of the semi-finished crystalline silicon cell is encapsulated, including the fabrication of electrode leads and a back substrate layer, thereby forming a "bottom-layer crystalline silicon cell module" composed of several semi-finished crystalline silicon cells. It can be understood that the periphery of the cell in this invention includes a ring around the front edge, a ring around the back edge, and each sidewall. ② Based on the fabricated bottom-layer crystalline silicon cell module, a large-area intermediate connecting layer and a top-layer semi-finished perovskite cell are fabricated, their area completely covering the bottom-layer crystalline silicon cell module. ③ The large-area top-layer semi-finished perovskite cell and intermediate connecting layer are etched and cut to form individual, independent, and separate small-area perovskite / crystalline silicon tandem solar cells in the vertical direction. ④ Finally, the tandem cells are interconnected and packaged to complete the fabrication of the perovskite / crystalline silicon tandem cell module.

[0005] It is understood that the semi-finished crystalline silicon solar cell described in this invention refers to a crystalline silicon solar cell without a front surface (i.e., front electrode) fabricated. In other words, except for the front electrode, the basic structure of the crystalline silicon solar cell, such as the charge transport layer and the back surface (i.e., back electrode), is complete. Similarly, the back electrode of the semi-finished perovskite solar cell described in this invention is not fabricated.

[0006] The perovskite / crystalline silicon tandem solar cell module provided by this invention is a series type, which can be a 2-terminal (2T) series type or a 3-terminal (3T) series type. For the 2T series tandem solar cell, the bottom semi-finished crystalline silicon cell only needs to export one of the photogenerated carriers, electrons and holes, while the other photogenerated carrier is exported from the top semi-finished perovskite cell. For the 3T series tandem solar cell, the bottom semi-finished crystalline silicon cell needs to export both electrons and holes simultaneously, and the top semi-finished perovskite cell will also export one of the electrons and holes simultaneously.

[0007] Understandably, perovskite solar cells can be fabricated at significantly lower temperatures compared to crystalline silicon solar cells. Therefore, the fabrication of perovskite / crystalline silicon tandem solar cells typically begins with the fabrication of the bottom semi-finished crystalline silicon cell. Thus, for tandem perovskite / crystalline silicon tandem solar cell modules, the polarity of the front and back surfaces of the top semi-finished perovskite cell (i.e., whether the photogenerated carriers drawn from the front and back surfaces are electrons or holes) needs to be determined based on the polarity of the front and back surfaces of the bottom semi-finished crystalline silicon cell, thereby forming a tandem solar cell.

[0008] Understandably, the fabrication process and corresponding material selection for the intermediate interconnect layer and the top semi-finished perovskite solar cell should be chosen and determined based on the materials of the already fabricated bottom crystalline silicon solar cell module. Specifically, it is essential not to affect or damage any part of the already fabricated bottom crystalline silicon solar cell module, primarily including the bottom semi-finished crystalline silicon solar cell, the metallized interconnect materials, and the back-side encapsulation materials. The fabrication processes here include high-temperature heat treatment, physical bombardment and chemical reactions of vacuum-phase deposited thin films, wet chemistry, laser or plasma dry etching, etc. Based on meeting this general principle, the material selection and fabrication process for the intermediate interconnect layer and the top semi-finished perovskite solar cell are not limited.

[0009] The bottom cell of the perovskite / crystalline silicon tandem solar module uses a crystalline silicon cell with a bandgap of 1.12 eV, primarily utilizing photons in the low-to-medium energy and long-wavelength bands of the solar spectrum. The silicon substrate can be monocrystalline or polycrystalline silicon, and the substrate doping type can be n-type (phosphorus-doped) or p-type (boron-doped or gallium-doped).

[0010] The specific structure of crystalline silicon solar cells is not limited, but it must be selected based on the overall terminal design of the tandem cell. For 2T series configurations, all-aluminum back surface field (SPF) cells, PERC (passivated emitter and rear cell) cells, passivated contact TOPCon (tunnel oxide and passivated contact) cells, silicon heterojunction (HJT) cells, etc., can be used, and they are not limited to these. For 3T series configurations, interdigitated back contact (IBC) cells, as well as MWT (Metal Wrap Through) or EWT (Emitter Wrap Through) cells, can be used.

[0011] There are no restrictions on the area size of crystalline silicon solar cells. They can adopt the currently popular industrial side lengths of 156mm, 182mm, or 210mm. The above area sizes can also be cut into smaller areas (depending on the application scenario), such as half a cell, one-third of a cell, ..., nth of a cell, etc.

[0012] The fabrication process of the underlying crystalline silicon solar cell module mainly includes the following steps: ① Fabricating the charge (electron or hole) transport layer of the semi-finished crystalline silicon solar cell; ② The front surface of the semi-finished crystalline silicon solar cell does not need to be metallized, but the back surface does need to be metallized, meaning that only the back electrode of the semi-finished crystalline silicon solar cell needs to be fabricated; ③ Back-side encapsulating several semi-finished crystalline silicon solar cells, including fabricating the back electrode leads and the back substrate layer.

[0013] It is important to note that in this application, the metallized interconnect material, i.e., the electrode leads, on the back of the bottom crystalline silicon cell module must be able to avoid oxidation during the subsequent fabrication of the intermediate interconnect layer and the top semi-finished perovskite cell, thereby ensuring the interconnect performance of the perovskite / crystalline silicon tandem cell module. Here, metal alloys with high conductivity and high-temperature oxidation resistance can be used, such as copper-chromium alloys, copper-chromium-zirconium alloys, copper-chromium-tellurium alloys, nickel-copper-silicon alloys, copper-nickel-chromium alloys, or nickel-chromium-iron alloys, copper-platinum alloys, etc. These alloys, which have good conductivity, also possess excellent high-temperature oxidation resistance.

[0014] This invention employs a two-layer encapsulation film for the back-side encapsulation of the underlying crystalline silicon battery module. The first encapsulation film, also known as the "back-side substrate layer," is formed after the back-side crystalline silicon semi-finished battery is manufactured. The material selection must possess good reliability, especially in terms of mechanical properties; however, the choice of material is not limited beyond this. Typically, it can be coated glass or TPT backsheet material (TPT is a three-layer composite film of PVDF / PET / PVDF, where PVDF is polyvinylidene fluoride and PET is polyethylene terephthalate), etc.

[0015] A certain number and pattern of vias need to be etched into the back substrate layer. These vias are divided into two categories based on their purpose: The first type is electrode lead vias, whose pattern is distributed within the lower vertical edge of the semi-finished crystalline silicon cell. The specific pattern distribution can be designed based on the electrode distribution on the back of the semi-finished crystalline silicon cell. The purpose of these electrode lead vias is to allow the electrode leads on the back of the semi-finished crystalline silicon cell to pass through them. The second type is interconnect vias, which are distributed in the area between two adjacent semi-finished crystalline silicon cells. These are used to interconnect cells of different unit areas in a tandem cell assembly. However, it is important to note that interconnect vias should avoid the centerline and adjacent sides of the area between two adjacent semi-finished crystalline silicon cells as much as possible. This is to prevent damage (etching) of these interconnect vias during the etching and cutting process after the top layer of the tandem cell is fabricated. The diameter range of electrode lead vias and interconnect vias is typically from 0.2 cm to 1 cm, but is not limited to this. The etching process for creating openings can be laser etching, plasma etching, or mechanical etching.

[0016] The bottom semi-finished crystalline silicon solar cell and the back substrate layer (with electrode lead vias and interconnect vias) are fixed together using encapsulation materials such as crosslinking agents to form a single unit. In this way, the electrode leads of the bottom crystalline silicon solar cell module that pass through the back substrate layer are "isolated" from the back substrate layer. The advantage of this design is that it protects the electrode leads of the bottom crystalline silicon solar cell module from the subsequent fabrication processes of the intermediate interconnect layer and the top semi-finished perovskite solar cell. The crosslinking agent used here can be a common crosslinking agent for battery module encapsulation, and the encapsulation process can use conventional lamination, with no specific limitations.

[0017] The second encapsulation layer on the back, also known as the "back encapsulation layer," is the outermost encapsulation layer on the back of the entire perovskite / crystalline silicon tandem solar cell module. It typically requires excellent resistance to degradation and aging, UV radiation, mechanical loads, water, moisture, and fire, as well as acid and alkali resistance. The specific encapsulation material is not limited and can be the same as the back substrate layer. The second back encapsulation layer is fabricated during the module encapsulation process after the top cell is manufactured, meaning it is produced together with the front encapsulation layer.

[0018] The intermediate connecting layer of the perovskite / crystalline silicon tandem solar cell module must be selected in terms of material to ensure good optical and electrical coupling between the bottom crystalline silicon cell and the top perovskite cell, and its fabrication process must not affect or damage the already fabricated bottom crystalline silicon cell module. Provided that the above conditions are met, the specific material and fabrication process of the intermediate connecting layer are not limited.

[0019] Typically, the material of the intermediate interconnect layer can be a transparent conductive oxide, such as tin-doped indium oxide (ITO), indium-doped zinc oxide (IZO), aluminum-doped zinc oxide (AZO), etc., and the preparation methods can include sputtering, atomic layer deposition (ALD), rapid plasma deposition, etc.

[0020] The top perovskite cell in a perovskite / crystalline silicon tandem solar module primarily utilizes high-energy (short wavelength) and medium-energy (medium wavelength) photons from the solar spectrum; therefore, the bandgap of the perovskite material must be designed to achieve this. The energy density (E) can be adjusted by modifying the chemical composition of the perovskite thin film. g The typical range is 1.5-2.0 eV, with a more optimized range of 1.6-1.8 eV. Furthermore, the polarity of the perovskite cell electrodes needs to be consistent with that of the underlying crystalline silicon cell to form a series-connected tandem cell module. Based on meeting the above requirements, the specific structure of the perovskite cell is not limited.

[0021] The top-layer perovskite solar cell mainly consists of a perovskite absorber layer, an electron transport layer, a hole transport layer, an interface modification layer, an optical antireflection film, and electrodes. The selection of materials and corresponding fabrication processes for each functional layer are not specifically limited in this invention; a brief description follows:

[0022] The perovskite absorber layer material can be either organic or inorganic halide perovskites, or it can be an inorganic perovskite material. Typically, organic perovskite thin film materials are used, specifically including methylamine lead halide perovskite (CH3NH3PbX3, abbreviated as MAPX), formamidinium lead halide perovskite (NH=CHNH3PbX3, abbreviated as FAPX), or a mixture of formamidinium and methylamine lead halides (chemical formula (NH=CHNH3)). t (CH3NH3) 1-t PbX3, abbreviated as FA t MA 1-t PbX3), etc. Where X is a halogen I, Br, or Cl. Eperovskite film g It can be adjusted according to its chemical composition.

[0023] The electron transport layer can be made of organic or inorganic materials. Typical organic electron transport materials include PCBMs (fullerenes and their derivatives), C... 60 (Fullerenes), BCP (bromocresol purple sodium salt), LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), etc., and not limited to these; typical inorganic electron transport materials include tin oxide (SnO2), zinc oxide (ZnO), titanium dioxide (TiO2), zirconium oxide (ZrO2), etc.; in addition, double or multilayer films of the above materials can also be used to form a composite, such as PCBM / C 60 C 60 / SnO2, ZnO / SnO2, etc.

[0024] The hole transport layer can be made of organic or inorganic materials. Typical organic hole transport materials include Spiro-OMETAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene), PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate), P3HT (polymer of 3-hexylthiophene), and DR3TBDTT (a conjugated small molecule oligothiophene derivative with benzothiophene as the core, dimer thiophene as the arm, and rhodin-terminated, chemical formula C). 102 H 128 N2O2S 14 Typical inorganic hole transport materials include nickel oxide (NiO). x ), molybdenum oxide (MoO) x ), Vanadium oxide (VO) x Copper oxides (CuO, Cu2O), cuprous iodide (CuI), cuprous thiocyanate (CuSCN), etc.

[0025] Sometimes, an interface modification layer is needed between the perovskite absorber layer and the charge (electron or hole) transport layer, or between the charge transport layer and the electrode that leads to the charge, in order to accelerate the extraction and transport of charge and reduce the recombination of photogenerated carriers.

[0026] The specific fabrication processes for the functional layers of semi-finished perovskite solar cells can employ low-temperature solution methods, such as spin-coating, slot-die coating, doctoral-blading, printing coating, spray-coating, meniscus-assisted solution printing, and inkjet printing. Vacuum deposition methods, such as sputtering, atomic layer deposition, and rapid plasma deposition, can also be used. For some functional layers (such as perovskite thin films), if annealing is required, laser annealing is preferred because it is a cold processing technique that will not affect or damage the already fabricated underlying semi-finished silicon module.

[0027] The front electrode (i.e., the front surface electrode) of the top-layer semi-finished perovskite solar cell can be made of metallic materials such as gold, silver, aluminum, or copper, or it can be made of graphene, carbon, or other materials. The electrode is typically fabricated using methods such as sputtering or screen printing.

[0028] After the aforementioned large-area intermediate connecting layer and top-layer semi-finished perovskite solar cell are fabricated, etching and cutting are required. During etching and cutting, care must be taken to preserve the underlying crystalline silicon module from being etched, especially avoiding damage to the back substrate layer. This process etches and cuts the large-area top-layer semi-finished perovskite solar cell and intermediate connecting layer into smaller perovskite solar cell units and intermediate connecting units. Vertically, the centerlines of the top-layer perovskite solar cell units, intermediate connecting units, and the bottom-layer semi-finished crystalline silicon solar cell are completely aligned, thus forming independent and separate small-area perovskite / crystalline silicon tandem solar cells. Therefore, in actual etching and cutting, from a vertical perspective, etching and cutting can be performed along the centerline between two adjacent semi-finished crystalline silicon solar cells in the crystalline silicon solar cell module; however, etching and cutting at an appropriate distance from the centerline is also permissible.

[0029] It should be noted that in this etching and cutting process, the various functional thin films (including charge transport layer, interface modification layer, perovskite absorber layer, etc.) and intermediate interconnecting layer materials of the top perovskite solar cell need to be selectively etched away, while the etching and cutting process does not etch or cut the back substrate layer of the bottom crystalline silicon solar cell. Therefore, it is necessary to ensure that the etching and cutting process has a clear etching selectivity ratio for the materials to be etched and the materials to be retained, while also minimizing the cutting damage to the various parts of the prepared tandem solar cell assembly. It is also important to note that the etching and cutting process must not etch or damage the previously prepared interconnecting vias. The etching and cutting process can employ techniques such as laser etching, plasma etching, or mechanical grooving.

[0030] Typically, laser etching technology can be used to achieve the selective etching described above by selecting appropriate laser etching parameters. Nd:YVO4 solid-state lasers are generally used, with wavelengths of 355nm, 532nm, or 1064nm, but not limited to these. Pulse widths are typically in the femtosecond, picosecond, or nanosecond range, but also not limited to these. To better achieve the selective etching described above, alternatively, two laser etching processes with identical patterns can be used. The first laser etching removes part of the functional layer of the perovskite solar cell, leaving another part of the functional layer and the intermediate interconnect layer unetched. The second laser etching removes the remaining functional layer and the intermediate interconnect layer, while leaving the back substrate layer of the crystalline silicon module unetched. Regarding the selection of the two laser parameters, the process parameters of the second laser etching should allow for a faster etching rate on the material to be etched, while leaving the back substrate layer unetched or with extremely weak etching capability.

[0031] After completing the fabrication of the bottom semi-finished crystalline silicon cells, the intermediate connecting layer, and the top semi-finished perovskite cells, the final step is to interconnect and encapsulate the tandem cells to complete the fabrication of the perovskite / crystalline silicon tandem cell module. It's important to note that this encapsulation can be referred to as "module encapsulation," typically including front-side encapsulation and back-side encapsulation to form front and back encapsulation layers. Front-side encapsulation, which is the encapsulation of the front surface of the top semi-finished perovskite cells, requires materials with good optical anti-reflective properties, as well as good resistance to degradation and aging, UV resistance, mechanical load performance, waterproofing, moisture resistance, fire resistance, and acid and alkali resistance. Specific encapsulation materials are not limited; typically, high-molecular polymers such as PDMA (pyromellitic dianhydride), PDMS (polydimethylsiloxane), polyethylene terephthalate (PET), polyethylene dinaphthalate (PEN), POE (polyolefin elastomer), and POB (polyphenylene oxide) can be used, or inorganic encapsulation films such as coated glass can be employed.

[0032] For the crosslinking agent used in the encapsulation of the top-layer semi-finished perovskite solar cell, this application primarily uses silicone rubber. Silicone rubber possesses excellent light transmittance, electrical insulation properties, UV radiation resistance, high and low temperature resistance, chemical corrosion resistance, chemical stability, mechanical properties, and reliability. Silicone rubber also exhibits good crosslinking and sealing properties. This invention uses silicone rubber instead of traditional EVA crosslinking agent to encapsulate solar cell modules, resulting in excellent crosslinking, sealing, plasticity, UV radiation resistance, durability, and electrical insulation properties. Therefore, the photovoltaic module exhibits superior reliability and stable, efficient operation.

[0033] More importantly, encapsulating photovoltaic modules with silicone does not necessarily require a lamination process at 140-150℃; it can be cured at room temperature and pressure. Therefore, it has no impact or damage on the already prepared perovskite cell portion and the "bottom semi-finished crystalline silicon module." The specific method is as follows: silicone is evenly laid between the encapsulation material on the front surface of the top semi-finished perovskite cell and the perovskite cell using methods such as dispensing, coating, spraying, or spin coating. Then, deep curing is performed at room temperature and pressure. The curing process can also be accelerated by increasing the pressure during curing. Due to the good insulation properties of silicone, the silicone filling between the individual perovskite / crystalline silicon tandem cells etched and cut as described above also provides good electrical isolation between them.

[0034] For perovskite / crystalline silicon tandem solar cells, the leads of the front and back electrodes of each cell are interconnected. Specifically, the electrode leads on the back of the tandem cell are first passed through interconnect vias in the back substrate layer before interconnection. The specific interconnection method is not limited and can be implemented in series or parallel within the module depending on the application requirements. Then, silicone is used to encapsulate the front encapsulation film of the top cell and the outermost encapsulation film on the back.

[0035] Finally, conventional techniques are used to install the frame, seal, and install the junction box to ultimately form the perovskite / crystalline silicon tandem solar cell module.

[0036] The present invention has the following beneficial effects:

[0037] 1) This invention integrates the fabrication processes of the bottom cell, the top cell, and the entire module, providing a new approach to the fabrication of tandem solar cell modules. The fabrication process is simple, greatly reducing the production cost of tandem modules and making it suitable for industrialization.

[0038] 2) The perovskite / crystalline silicon tandem solar cell module described above is composed of a top perovskite cell with a wide bandgap and a bottom crystalline silicon cell with a narrow bandgap. It can make more comprehensive and efficient use of photons in the short-wave, medium-wave and long-wave wavelength range of the solar spectrum, thereby achieving high cell conversion efficiency and module power generation.

[0039] 3) The structure and type of the top-layer perovskite solar cell are flexible. The bandgap width of the absorption layer can be designed to be optimized according to the needs of the application scenario. This bandgap width of the top-layer perovskite solar cell can be achieved by adjusting the composition of the perovskite thin film material of the absorption layer, so that it can be suitable for different application environments (climate, geography and environment, etc.).

[0040] 4) Perovskite / crystalline silicon tandem solar cell modules can be flexibly fabricated into 2-terminal or 3-terminal types according to the needs of the application scenario. This design is achieved through the specific structure of the underlying crystalline silicon cell, which flexibly broadens the applicability and compatibility of the application scenarios. Attached Figure Description

[0041] Figure 1 A schematic diagram of a perovskite / crystalline silicon tandem solar cell module is shown, illustrating the case where one crystalline silicon bottom cell is considered as one unit. In the diagram, 1 is the back encapsulation layer, 2 is the back substrate layer, 3 is the back electrode of the bottom crystalline silicon cell, 4 is the electrode lead via, 5 is the module electrode lead on the back of the bottom crystalline silicon cell, 6 is the electron (or hole) transport layer, 7 is the crystalline silicon substrate, 8 is the hole (or electron) transport layer, 9 is the intermediate connecting layer, 10 is the electron (or hole) transport layer, 11 is the perovskite absorber layer, 12 is the hole (or electron) transport layer, 13 is the front encapsulation layer, 14 is the front electrode of the top perovskite cell, and 15 is the module electrode lead on the front of the top perovskite cell.

[0042] Figure 2 Flowchart of the fabrication process for perovskite / crystalline silicon tandem solar cell modules.

[0043] Figure 3. Schematic diagrams before and after etching during the fabrication process of perovskite / crystalline silicon tandem solar cell modules, wherein: Figure 3-a This is a schematic diagram before etching and cutting. In it, 1 is the bottom semi-finished crystalline silicon cell, 2 is the large-area intermediate connecting layer, 3 is the large-area top perovskite cell, and 4 is the back substrate layer. Figure 3-bThis diagram illustrates the process of completing the front-side encapsulation of the module after etching and cutting. In the diagram, 1 is the bottom semi-finished crystalline silicon cell, 2 is the intermediate connecting unit after etching and cutting, 3 is the top semi-finished perovskite cell after etching and cutting, 4 is the back substrate layer, 5 is the front encapsulation layer, 6 is the back encapsulation layer, 7 is the electrode lead via, and 8 is the interconnect via. It should be noted that after the module encapsulation is completed, the space between adjacent cell sizes is filled with the front encapsulation material and cross-linking agent. Since both the front encapsulation material and the cross-linking agent have good electrical insulation properties, they effectively provide insulation between cell sizes in the stacked cells. Detailed Implementation

[0044] To better understand the present invention, it will be further described below with reference to specific embodiments and accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0045] Combination Figure 1 As shown in Figure 3, Example 1 provides a method for fabricating a perovskite / crystalline silicon tandem solar cell module. The bottom crystalline silicon cell uses a PERC cell, and the top perovskite cell absorber layer uses an E... g It is 1.75 eV. The specific preparation process mainly includes the following stages:

[0046] The first stage involves fabricating the underlying PERC battery module, and the specific fabrication method is as follows:

[0047] Step 1. Select a 182mm*182mm (100) crystal orientation p-type single crystal silicon wafer with a thickness of 170 micrometers and a resistivity of 1Ω·cm.

[0048] Step 2. A textured surface with a random pyramidal morphology is prepared on the surface of the p-type silicon wafer using an alkaline texturing method. The process conditions are: 2-3% potassium hydroxide by mass concentration, temperature of 70-75℃, and texturing time of 5-7 minutes.

[0049] Step 3. A uniform n-type emitter junction is prepared on the front side of the p-type silicon wafer by ion implantation of phosphorus combined with furnace tube annealing. The phosphorus implantation energy is 10 keV and the dose is 1.10. 15 cm 2 The furnace tube annealing temperature is 830-850℃, the time is 30-40 minutes, and the atmosphere is nitrogen. The phosphorus surface doping concentration is 1.10. 20 cm -3 The sheet resistance is 90-100Ω / □.

[0050] Step 4. Using a wet etching process combining a mixed solution of nitric acid and hydrofluoric acid with water-based etching, the trace amount of phosphorus-doped junctions that diffused to the back of the p-type silicon wafer in Step 3 are etched away. After this chemical etching step, the textured surface on the back of the silicon wafer is etched into an acid-polished surface. In the mixed solution of nitric acid and hydrofluoric acid, the mass concentration of nitric acid is 40%, the mass concentration of hydrofluoric acid is 4%, the solution temperature is 7°C, and the etching time is 10-20 seconds.

[0051] Step 5. Prepare a passivation film on the back side of the p-type silicon wafer. Deposit a multilayer film of alumina and silicon nitride using a PECVD process, wherein the alumina is 5 nm thick and has a refractive index of 1.65; the silicon nitride is approximately 100 nm thick and has a refractive index of 2.0.

[0052] Step 6. The aluminum oxide / silicon nitride stacked film on the back side of the p-type silicon wafer is etched away using a laser ablation process. The laser ablation process parameters are: Nd:YVO4 laser, wavelength 532nm, pulse width 15ps, pulse repetition frequency 200-1000kHz. The laser ablation pattern adopts a gate line distribution design with a linewidth of 25-30μm and a spacing of 1.6mm between two adjacent gate lines (between the center lines). This pattern is the pattern of the subsequent aluminum back field doping region.

[0053] Step 7. Aluminum paste is printed on the back side of the p-type silicon wafer using screen printing technology, and sintered in a rapid thermal sintering furnace to form a local aluminum back field and metal-semiconductor ohmic contact on the back side. The actual peak sintering temperature is 750°C, the time at the peak temperature is 2 to 4 seconds, and the atmosphere is compressed air.

[0054] Step 8. Laser edge isolation is applied to the perimeter of the semi-finished PERC cell to make the perimeter of the cell electrically insulating.

[0055] Step 9. Prepare the module electrode leads and back substrate layer on the back of the bottom semi-finished PERC cell.

[0056] 1) The back of the prepared semi-finished PERC cell is encapsulated using a standard 6*12 array of 72 cells. First, the back aluminum electrodes are soldered. The module leads for the aluminum electrodes are made of copper-chromium alloy, copper-chromium-tellurium alloy, or copper-nickel-chromium alloy, etc., which have good conductivity and excellent resistance to high-temperature oxidation. Therefore, oxidation can be avoided during the subsequent fabrication of the intermediate interconnect layer and the top perovskite cell, thus ensuring the interconnect performance of the tandem cell module.

[0057] 2) The back substrate layer uses coated glass with good mechanical properties, and the following two treatments are required: (1) A certain number and pattern distribution of electrode lead vias and interconnect vias are etched on the coated glass using low-damage laser etching technology. The diameter of the electrode lead vias and interconnect vias is 0.8 cm. Among them, the pattern distribution of the electrode lead vias is within the lower edge of the longitudinal direction of the semi-finished crystalline silicon cell. The specific pattern distribution can be designed according to the metal electrode distribution on the back of the semi-finished PERC cell; the pattern distribution of the interconnect vias is in the lower longitudinal direction of the area between two adjacent semi-finished PERC cells. It should be avoided as much as possible to distribute them on the center line and adjacent sides of the area between two adjacent semi-finished PERC cells. The via etching can be completed using 355 nm nanosecond laser technology. (2) After the via etching is completed, the back substrate layer, i.e., the coated glass, is cleaned with hydrofluoric acid. The HF mass fraction is 5%-10% and the time is 30-60 minutes. Then it is washed with water and dried. The purpose is to further enhance the blocking ability (not to be etched) of the laser etching cutting in step 15. Next, the back electrode leads of the semi-finished PERC cell are passed through the electrode lead through-holes on the back substrate layer. Then, the bottom semi-finished PERC cell, the back substrate encapsulation layer, and the crosslinking agent EVA (ethylene-vinyl acetate copolymer) are laid out and vacuum laminated. The lamination process is carried out at a temperature of 140°C, a pressure of 100 Pa, a time of 7-8 minutes, and a nitrogen atmosphere. This completes the bottom PERC crystalline silicon module.

[0058] The second stage involves the preparation of a large-area intermediate connecting layer.

[0059] Step 10. Fabricate the intermediate interconnect layer of the tandem solar cell on the bottom PERC crystalline silicon module. Its area is the same as that of the PERC module (Note: the fabrication process for the top perovskite solar cell is the same below). Tin-doped indium oxide (ITO) is used, fabricated by magnetron sputtering. The target material is an indium tin oxide (In₂O₃:SnO₂ = 90:10wt%) ceramic target with a purity higher than 99.99%. The target-substrate spacing is 70-100 mm. The sputtering atmosphere is a mixture of Ar and O₂ gases (purity higher than 99.99%), and the base vacuum is 1.5 × 10⁻⁶. -4 Pa, substrate temperature 25℃. Sputtering pressure 0.1 Pa, sputtering power 50 W. ITO thickness 150 nm, sheet resistance 30-70 Ω / □, average transmittance ~87%.

[0060] The third stage involves the fabrication of a large-area top-layer semi-finished perovskite solar cell.

[0061] Step 11. Prepare the hole transport layer of the top perovskite solar cell using PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate). Prepared by spin coating, the PEDOT:PSS precursor spin coating solution used was Heraeus 4083 solution, the spin coating speed was 6000 rpm, and after spin coating, it was annealed on a heating stage at 80°C for 30 min under nitrogen atmosphere, and then cooled to room temperature. The thickness of PEDOT:PSS was 30 nm.

[0062] Step 12. Prepare a perovskite absorber layer film using methylamine lead halide perovskite, i.e., CH3NH3Pb(I x Br 1-x )3, E g The perovskite film was prepared in the range of 1.6-1.9 eV. It was prepared using a spin-coating method with a perovskite precursor solution composed of PbI₂, PbBr₂, CH₃NH₃I, DMF (N,N-dimethylformamide), and DMSO (dimethyl sulfoxide). Chlorobenzene (as an anti-solvent to wash away DMF) was dropped onto the perovskite film during spin-coating at a speed of 3000 rpm. After spin-coating, the film was heated on a 70-80°C heating stage for 30 min in a nitrogen atmosphere. Annealing was then performed using a femtosecond Nd:YVO₄ solid-state laser with a wavelength of 800 nm, a pulse width of 140 fs, and a repetition rate of 80 MHz, under a nitrogen atmosphere. After laser annealing, the perovskite film underwent a phase transformation. It should be noted that due to the localized heat treatment characteristics of laser "cold working," only the perovskite film was subjected to laser heat treatment; the pre-prepared layers beneath the perovskite absorber layer remained unaffected. The prepared perovskite thin film CH3NH3Pb(Br 0.4 I 0.6 )3 of E g It has a voltage of 1.75 eV and a thickness of 500 nm.

[0063] Step 13. Prepare the electron transport layer / interface modification layer using PC. 61 BM / BCP. Among them, the electron transport layer PC... 61 BM consists of PCBM (fullerenes and their derivatives) and C 60 (Fullerene) composition; BCP (bromocresol purple sodium salt, C 21 H 15 Br2NaO5S) was used as an interface modification layer for electron transport. It was prepared using a spin-coating method, the specific process of which is as follows. PC... 61 The BM precursor solution was dissolved in chlorobenzene, stirred thoroughly at room temperature, and then allowed to stand for later use. PC... 61BM solution was spin-coated onto the sample at 5000-6000 rpm. After spin-coating, the sample was annealed at 40°C for 20 min under nitrogen purging. Then, a saturated IPA solution of BCP was spin-coated onto the sample at 2000 rpm. The resulting PC... 61 The thickness of BM is 20nm, and the thickness of BCP is 5nm.

[0064] Step 14. Metallize the front surface of the top-layer perovskite solar cell using magnetron sputtering of Ag to form grid-type Ag electrodes. A photomask sputtering process is used, with the photomask made of graphite. In the sputtering process, the solid portion of the photomask prevents sputtered Ag atoms from reaching the substrate, while the hollow portion allows sputtered Ag atoms to reach the substrate; therefore, the photomask pattern is the Ag grid pattern. The silver target purity is 99.99%, the substrate temperature is room temperature (25°C), the distance between the target and substrate is 50 mm, the sputtering gas is argon (99.99% purity), and the base vacuum is 5.10. -5 The sputtering power was 160W. The sputtered Ag layer thickness was 200nm, and the sheet resistance was 0.25Ω / □. Then, tin-plated silver or copper strips were used to bring out the front surface metal electrodes of the top perovskite cell. In this example, a two-terminal design was used, specifically, the electrodes of the top perovskite cell brought out photogenerated electrons, and the bottom PERC cell brought out photogenerated holes.

[0065] Step 15. Perform laser etching to cut the large-area top-layer perovskite solar cell and intermediate connection layer. Selectively etch away the functional thin films (including charge transport layer, interface modification layer, perovskite absorber layer, etc.) and intermediate layer materials of the top-layer perovskite solar cell, leaving only the back substrate layer of the "bottom PERC crystalline silicon module" unetched. This process etches and cuts the large-area top-layer perovskite solar cell and intermediate connection layer into small-area perovskite solar cell units and intermediate connection units, forming independent and separate small-area perovskite / crystalline silicon stacked solar cells vertically. It is important to note that the laser etching process must not etch or damage the previously prepared interconnecting vias; this can be achieved through precise scanning techniques in laser etching.

[0066] The specific laser etching process is as follows. Through flexible laser beam deflection, precise focusing, and a high-precision aligned camera system, the laser beam precisely scans and etches along a large area of ​​stacked solar cells. Specifically, the laser etching cutting pattern, viewed vertically, is etched along the center line between every two adjacent PERC cells in the "bottom-layer semi-finished PERC cell module," thereby etching and cutting the large-area top-layer perovskite cell and intermediate connecting layer into small patterns with an area roughly equal to that of the bottom-layer crystalline silicon cell, such as... Figure 3-bAs shown. Based on the laser etching pattern, two laser etching processes are employed. The first laser etching is used to etch away the top perovskite solar cell's electron transport layer / interface modification layer (PC). 61 The laser etching process consists of a BM / BCP (Boiler-Based Polymer), a perovskite absorber layer, and a hole transport layer (PEDOT:PSS). A second laser etching step is used to remove the intermediate ITO (Indium TO) interconnect layer. The process parameters for both laser etching steps are as follows: Step 1: An Nd:YVO4 solid-state laser is used with a wavelength of 532 nm, a pulse width of 15 ns, and a repetition frequency of 15-30 kHz. A nitrogen atmosphere is used during the laser process. Step 2: An Nd:YVO4 solid-state laser is used with a wavelength of 1064 nm, a pulse width of 8 ns, and a repetition frequency of 10-20 kHz. A nitrogen atmosphere is used during the laser process.

[0067] The fourth stage involves interconnecting and encapsulating the tandem solar cells to complete the fabrication of the perovskite / crystalline silicon tandem solar cell module.

[0068] Step 16. Interconnect the leads of the front and back electrodes of each unit area of ​​the tandem cell. Specifically, the electrode leads on the back of the tandem cell are first passed through the previously prepared interconnecting vias. Then, interconnection is performed between different small-area tandem cells. In this example, the bottom PERC cell module uses a 6*12 array of 72 cells. The interconnection method is that the small tandem cells in 12 rows are connected in series, and those in 6 columns are arranged in parallel. After interconnection, the front and back of the tandem cells are encapsulated, i.e., module encapsulation. The front encapsulation film uses PDMS (polydimethylsiloxane) and coated glass (outermost layer on the front), and the outermost encapsulation film on the back uses coated glass. The crosslinking agent is Dow Corning's silicone product series used in solar cell encapsulation. The specific encapsulation process involves uniformly laying the front coated glass, PDMS encapsulation film, the prepared perovskite silicon tandem cell, and the back coated glass, and then uniformly coating the silicone between the layers using a dispensing method. Then, deep curing is performed at 25-50℃ for 1-2 hours in a nitrogen atmosphere, allowing the silicone to bond the components tightly together and ensuring full cross-linking, fixation, and sealing of the encapsulation film, silicone, and tandem solar cells. Alternatively, a curing lamination method with slowly increasing pressure can be used to enhance the curing effect and accelerate the curing process. Because of its excellent insulating properties, the silicone filling the spaces between the discrete perovskite / crystalline silicon tandem solar cells, as defined by laser etching in step 15, also provides good electrical isolation between them.

[0069] Step 17. Install the frame, seal, and install the junction box using conventional technical methods to form the final perovskite / crystalline silicon tandem solar cell module.

[0070] Furthermore, Example 2 discloses a perovskite / crystalline silicon tandem solar cell module, which is prepared using the method described in Example 1. The specific structure will not be described here.

[0071] Finally, it should be noted that although the embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and guiding, used to help understand the method and core ideas of the present invention, and are not restrictive. Those skilled in the art, under the guidance of this specification, can make many changes, improvements, and equivalent implementations in specific embodiments and application scope without departing from the principles and scope of protection of the claims, and these should also be considered within the scope of protection of the present invention.

Claims

1. A method for fabricating a perovskite / crystalline silicon tandem solar cell module, characterized in that, Includes the following steps: Prepare several semi-finished crystalline silicon solar cells, wherein the semi-finished crystalline silicon solar cells only have a back electrode; Laser edge isolation is applied to the periphery of the semi-finished crystalline silicon cell to make the periphery electrically insulated. The semi-finished crystalline silicon cell is back-encapsulated to obtain a bottom crystalline silicon cell module. The back-encapsulation includes the preparation of back electrode leads and a back substrate layer. The back substrate layer has a number of electrode lead through holes located in the region below the longitudinal direction of the semi-finished crystalline silicon cell and a number of interconnecting through holes located in the region between adjacent semi-finished crystalline silicon cells. An intermediate connection layer is fabricated on the underlying crystalline silicon cell module. The intermediate connection layer is used for optical coupling and electrical coupling between the semi-finished crystalline silicon cell and the semi-finished perovskite cell. The intermediate connection layer completely covers the underlying crystalline silicon cell module. A top-layer semi-finished perovskite solar cell is prepared on the intermediate connecting layer. The semi-finished perovskite solar cell completely covers the intermediate connecting layer. The semi-finished perovskite solar cell has only a front electrode. The pattern and distribution of the front electrode match the back electrode of the bottom crystalline silicon solar cell module. The semi-finished perovskite solar cells and intermediate connecting layers are etched and cut from top to bottom to obtain several perovskite solar cell units and intermediate connecting units that are the same number of semi-finished crystalline silicon solar cells in the bottom crystalline silicon solar cell module. This forms several independent and separate perovskite / crystalline silicon stacked solar cells in the vertical direction. The perovskite / crystalline silicon tandem solar cell is encapsulated to obtain the perovskite / crystalline silicon tandem solar cell module. The module encapsulation includes the preparation of front electrode leads, a front encapsulation layer and a back encapsulation layer. Fabricating a top-layer semi-finished perovskite solar cell on the intermediate connecting layer includes: Hole transport layer of top perovskite solar cell was prepared using PEDOT:PSS via spin coating. Perovskite absorber layer films were prepared using methylamine lead halide perovskite via spin coating. The E0 of the perovskite absorber layer film... g Within the range of 1.6-1.9 eV; PC based on spin coating method 61 BM / BCP is used to prepare electron transport layers / interface modification layers; A grid-type Ag electrode is formed on the front surface of the top-layer semi-finished perovskite solar cell using magnetron sputtering.

2. The preparation method according to claim 1, characterized in that, The back electrode lead of the semi-finished crystalline silicon solar cell is any one of copper-chromium alloy, copper-chromium-zirconium alloy, copper-chromium-tellurium alloy, nickel-copper-silicon alloy, copper-nickel-chromium alloy, nickel-chromium-iron alloy, and copper-platinum alloy.

3. The preparation method according to claim 1, characterized in that, The back substrate layer is coated glass or TPT backplate.

4. The preparation method according to claim 1, characterized in that, The intermediate connecting layer is made of any one of tin-doped indium oxide, indium-doped zinc oxide, or aluminum-doped zinc oxide; the intermediate connecting layer is prepared by sputtering, atomic layer deposition, or rapid plasma deposition.

5. The preparation method according to claim 1, characterized in that, The preparation process of the semi-finished perovskite solar cell includes an annealing process, which is a laser annealing process.

6. The preparation method according to claim 1, characterized in that, When etching and cutting the semi-finished perovskite solar cells and intermediate interconnect layers from top to bottom, the etching and cutting are performed along the center line of the adjacent semi-finished crystalline silicon solar cells in the bottom crystalline silicon solar cell module; the interconnect vias are located in the area avoiding the center line position, and their diameter is 0.2 cm to 1 cm.

7. The preparation method according to claim 1, characterized in that, The etching and cutting process can be any one of laser etching, plasma etching, or mechanical grooving.

8. The preparation method according to claim 7, characterized in that, The etching and cutting process uses laser etching and cutting; the laser etching and cutting uses an Nd:YVO4 solid-state laser; the laser etching and cutting is completed in two stages, the first etching and cutting away part of the functional layer of the semi-finished perovskite solar cell, and the second etching and cutting away the remaining functional layer and intermediate connection layer of the semi-finished perovskite solar cell.

9. The preparation method according to claim 1, characterized in that, The front encapsulation layer is fixedly connected to the semi-finished perovskite battery via silicone rubber, which is cured at room temperature and pressure.

10. A perovskite / crystalline silicon tandem solar cell module, characterized in that, The perovskite / crystalline silicon tandem solar cell module is prepared by any one of the preparation methods described in claims 1 to 9; the perovskite / crystalline silicon tandem solar cell module is a 2-terminal series type or a 3-terminal series type module.

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