Photovoltaic cell and method of manufacturing the same, stacked cell, photovoltaic module

Abstract

The application relates to a photovoltaic cell and a preparation method thereof, a laminated cell and a photovoltaic module. The photovoltaic cell comprises a substrate, the substrate has a first surface and a second surface arranged oppositely; an amorphous silicon carbide layer is arranged on the first surface; the substrate further comprises a third surface connecting the first surface and the second surface, a monomolecular passivation layer is arranged on the third surface, and the monomolecular passivation layer comprises a bifunctional silane coupling agent; and the amorphous silicon carbide layer is arranged at the edge of the first surface close to the third surface. The photovoltaic cell has low edge recombination loss caused by cutting, and can effectively improve the conversion efficiency of the photovoltaic module.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to photovoltaic cells and their preparation methods, tandem cells, and photovoltaic modules. Background Technology

[0002] Cellular solar cells are a high-efficiency photovoltaic technology that uses high-precision laser cutting to evenly cut standard-sized solar cells into smaller pieces, which are then strung together and encapsulated to form modules. Two-cell and four-cell slicing reduce the cell current to 1 / 2 and 1 / 4 of that of traditional whole-cell cells, respectively, thus significantly reducing ohmic losses and improving the overall conversion efficiency of photovoltaic modules. However, traditional slicing cells suffer from significant edge recombination losses due to cutting, limiting the improvement of conversion efficiency. Summary of the Invention

[0003] Therefore, it is necessary to provide photovoltaic cells and their fabrication methods, tandem cells, and photovoltaic modules. The photovoltaic cells of this application exhibit lower edge recombination losses due to cutting, thereby effectively improving the conversion efficiency of photovoltaic modules.

[0004] In a first aspect, this application provides a photovoltaic cell, including a substrate having a first surface and a second surface disposed opposite to each other; an amorphous silicon carbide layer is disposed on the first surface; the substrate further includes a third surface connecting the first surface and the second surface, a monomolecular passivation layer is disposed on the third surface, the monomolecular passivation layer including a bifunctional silane coupling agent; the amorphous silicon carbide layer is disposed on the edge of the first surface near the third surface.

[0005] In some embodiments, the bifunctional silane coupling agent has at least one of -NH2, -SH, -CH=CH2 and -epoxy groups, and the bifunctional silane coupling agent also has at least one of -Si(OCH3)3 and -Si(OC2H5)3.

[0006] In some embodiments, the bifunctional silane coupling agent includes at least one of 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, and epoxysilane.

[0007] In some embodiments, the width of the amorphous silicon carbide layer is 0.1% to 0.3% of the width of the substrate along the width direction of the substrate.

[0008] In some embodiments, the thickness of the amorphous silicon carbide layer is 5 nm to 8 nm.

[0009] In some embodiments, the width of the amorphous silicon carbide layer is 90 μm to 110 μm.

[0010] Secondly, this application provides a method for preparing a photovoltaic cell, comprising the following steps:

[0011] A battery pre-product is provided, the battery pre-product including a substrate having a first surface and a second surface disposed opposite to each other;

[0012] An amorphous silicon carbide layer is formed on the first surface;

[0013] The battery pre-product is sliced ​​along the length of the amorphous silicon carbide layer to form a third surface, thus obtaining a sliced ​​pre-product.

[0014] A monomolecular passivation layer is formed on the third surface, the material of which includes a bifunctional silane coupling agent.

[0015] In some embodiments, forming a monomolecular passivation layer on the third surface includes:

[0016] The third surface is passivated using a passivation solution comprising a bifunctional silane coupling agent at a mass concentration of 0.2% to 1%.

[0017] In some embodiments, the passivation solution further includes a corrosion inhibitor at a mass concentration of 0.1% to 0.2%.

[0018] In some embodiments, the passivation solution further includes a surfactant at a mass concentration of 0.05% to 0.1%.

[0019] In some embodiments, the passivation treatment temperature is 25°C to 35°C.

[0020] In some embodiments, the passivation process takes 100s to 200s.

[0021] In some embodiments, after forming a monomolecular passivation layer on the third surface, the method further includes:

[0022] The monomolecular passivation layer is subjected to laser treatment.

[0023] In some embodiments, the pulse energy of the laser treatment is 10 μJ to 15 μJ.

[0024] In some embodiments, the pulse width of the laser processing is 200 fs to 400 fs.

[0025] In some embodiments, the frequency of the laser processing is 400kHz to 600kHz.

[0026] In some embodiments, the scanning rate of the laser processing is 100 mm / s to 150 mm / s.

[0027] In some embodiments, the laser processing spot overlap rate is 50% to 70%.

[0028] Thirdly, this application provides a tandem solar cell, including a composite layer and a top cell and a bottom cell respectively located on two opposite surfaces of the composite layer; at least one of the top cell and the bottom cell is a photovoltaic cell as described above, or a photovoltaic cell prepared by the method described above for preparing a photovoltaic cell.

[0029] Fourthly, this application provides a photovoltaic module, comprising:

[0030] Cover plate;

[0031] At least one battery string, the battery string comprising the photovoltaic cell described in any one of the above descriptions, or the photovoltaic cell prepared by the method described in any one of the above descriptions, or the above-described tandem battery;

[0032] And an encapsulation layer, which is located between the cover plate and the battery string, and the cover plate is connected to the battery string through the encapsulation layer.

[0033] In the aforementioned photovoltaic cells, the amorphous silicon carbide layer near the edge of the third surface serves as an edge pre-encapsulation layer. As a buffer layer, the amorphous silicon carbide layer is chemically stable and can strengthen the edge from the source, changing the traditional passive approach of repairing damage after initial damage. This reduces cutting damage to the photovoltaic cells during the slab-making process. Simultaneously, the amorphous silicon carbide layer can also serve as a bonding substrate for the monomolecular passivation layer. The monomolecular passivation layer, including a bifunctional silane coupling agent, enables selective passivation and precise repair of the edge regions of the photovoltaic cells. In this application, through source protection and edge passivation, a complete protective chain is formed, resulting in lower edge composite damage caused by cutting, thereby achieving higher conversion efficiency for the photovoltaic modules.

[0034] Furthermore, in the photovoltaic module preparation method of this application, the process steps of pre-encapsulation of an amorphous silicon carbide layer, slab cutting, and monomolecular passivation layer are not a simple superposition of steps, but rather a synergistic effect. The amorphous silicon carbide layer not only reduces cutting damage but also provides an ideal substrate for subsequent molecular passivation, improving the passivation and repair effect of the bifunctional silane coupling agent on the third surface. This forms a triple protection mechanism of physical isolation, chemical passivation, and repair, enabling the preparation of photovoltaic cells with lower edge recombination losses caused by cutting, thereby effectively improving the conversion efficiency of photovoltaic modules. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of a photovoltaic cell provided in one embodiment of this application;

[0036] Figure 2 A schematic diagram of the structure of a photovoltaic cell provided in yet another embodiment of this application;

[0037] Figure 3 A schematic diagram of the structure of a photovoltaic cell before slab division provided in one embodiment of this application;

[0038] Figure 4 A schematic diagram of the structure of a sliced ​​photovoltaic cell provided in one embodiment of this application;

[0039] Figure 5 This is a schematic diagram of the structure of a photovoltaic cell after forming a monomolecular passivation layer, provided in one embodiment of this application.

[0040] Explanation of reference numerals in the attached figures:

[0041] 10-Substrate; 20-Amorphous silicon carbide layer; 30-Monomer passivation layer; 40-Front passivation layer; 50-Doped region; 60-First electrode; 70-Tunneling oxide layer; 80-Doped conductive layer; 90-Second electrode; 100-Back passivation layer. Detailed Implementation

[0042] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0044] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0045] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0046] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0047] Reference Figure 1 As shown, one embodiment of this application provides a photovoltaic cell, including a substrate 10, the substrate 10 having a first surface and a second surface disposed opposite to each other; an amorphous silicon carbide layer 20 is disposed on the first surface; the substrate 10 further includes a third surface connecting the first surface and the second surface, a monomolecular passivation layer 30 is disposed on the third surface, the monomolecular passivation layer 30 includes a bifunctional silane coupling agent; the amorphous silicon carbide layer 20 is disposed at the edge of the first surface near the third surface.

[0048] In the aforementioned photovoltaic cell, the amorphous silicon carbide layer 20 near the edge of the third surface serves as an edge pre-encapsulation layer. As a buffer layer, the amorphous silicon carbide layer 20 is chemically stable and can strengthen the edge from the source, changing the traditional passive approach of repairing damage after initial damage. This reduces cutting damage to the photovoltaic cell during the slab-making process. Simultaneously, the amorphous silicon carbide layer 20 also serves as a connecting substrate for the monomolecular passivation layer 30. The monomolecular passivation layer 30, including a bifunctional silane coupling agent, enables selective passivation and precise repair of the edge region of the photovoltaic cell. In this application, through source protection and edge passivation, a complete protective chain is formed, reducing edge composite damage caused by cutting and thus effectively improving the conversion efficiency of the photovoltaic module.

[0049] In some embodiments, the bifunctional silane coupling agent has at least one of -NH2, -SH, -CH=CH2 and -epoxy groups, and the bifunctional silane coupling agent also has at least one of -Si(OCH3)3 and -Si(OC2H5)3.

[0050] In the aforementioned bifunctional silane coupling agent, the -NH2, -SH, and -CH=CH at one end of the molecule can selectively bond to the metal or polycrystalline silicon that may be plated, while the siloxane at the other end combines with the substrate 10 or the amorphous silicon carbide layer 20 to form a monomolecular passivation layer 30.

[0051] In some embodiments, the bifunctional silane coupling agent includes at least one of 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, and epoxysilane.

[0052] In some embodiments, the width of the amorphous silicon carbide layer 20 along the width direction of the substrate 10 is 0.1% to 0.3% of the width of the substrate 10.

[0053] When the width of the amorphous silicon carbide layer 20 is a small percentage of the width of the substrate 10, laser damage to the portion where the amorphous silicon carbide layer 20 was not fabricated is likely to occur during cutting. When the width of the amorphous silicon carbide layer 20 is a large percentage of the width of the substrate 10, the amorphous silicon carbide layer 20 occupies a large proportion of the effective area of ​​the photovoltaic cell, which may affect the conversion efficiency of the photovoltaic cell.

[0054] Refer again Figure 1 As shown, exemplarily, Figure 1 The X-direction is the width direction of the substrate 10. Figure 1 In the figure, 'a' represents the width of the amorphous silicon carbide layer 20. Figure 1 In the middle, the Y direction is the thickness direction of the substrate 10. Figure 1In this context, 'b' represents the thickness of the amorphous silicon carbide layer 20. Optionally, the percentage of the width of the amorphous silicon carbide layer 20 to the width of the substrate 10 along the width direction of the substrate 10 is 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.22%, 0.25%, 0.28%, or 0.3%, or the percentage of the width of the amorphous silicon carbide layer 20 to the width of the substrate 10 along the width direction of the substrate 10 can also be within any of the above percentages.

[0055] In some embodiments, the thickness of the amorphous silicon carbide layer 20 is 5 nm to 8 nm.

[0056] Within the aforementioned range of amorphous silicon carbide layer 20 thickness, it is convenient to balance the effect of cutting and protecting photovoltaic cells while maintaining a moderate cutting difficulty. Optionally, the thickness of amorphous silicon carbide layer 20 is 5nm, 5.5nm, 6nm, 6.5nm, 7nm, 7.5nm, or 8nm, or the thickness of amorphous silicon carbide layer 20 can also be within any two of the above-mentioned thicknesses.

[0057] In some embodiments, the width of the amorphous silicon carbide layer 20 is 90 μm to 110 μm.

[0058] Within the aforementioned width range of the amorphous silicon carbide layer 20, it is convenient to balance the effect of reducing cutting damage and a smaller proportion of the effective area of ​​the photovoltaic cell occupied by the amorphous silicon carbide layer 20, thereby effectively improving the conversion efficiency of the photovoltaic module. Optionally, the width of the amorphous silicon carbide layer 20 is 90μm, 92μm, 95μm, 98μm, 100μm, 102μm, 105μm, 108μm, or 110μm, or the width of the amorphous silicon carbide layer 20 can also be within the range of any two of the above widths.

[0059] In some implementations, there are two third surfaces.

[0060] It should be noted that, Figures 3-5 The images shown are top-view structural diagrams of the first surface of the photovoltaic cell. It is understood that the photovoltaic cell of this application can be either a two-cell or a four-cell structure. If it is a four-cell structure, there are two adjacent third surfaces. In this case, an amorphous silicon carbide layer 20 is disposed near the edges of both third surfaces, and a monomolecular passivation layer 30 is present on both third surfaces.

[0061] Refer again Figure 1 As shown, Figure 1This is a schematic diagram of a photovoltaic cell provided in one embodiment of this application. In some embodiments, a doped region 50 is provided in the first surface, and a front passivation layer 40 and an amorphous silicon carbide layer 20 are disposed on the first surface. The photovoltaic cell also includes a first electrode 60, which is electrically connected to the doped region 50.

[0062] In some embodiments, a tunneling oxide layer 70, a doped conductive layer 80, and a back passivation layer 100 are sequentially stacked on the second surface. The photovoltaic cell also includes a second electrode 90, which is electrically connected to the doped conductive layer 80.

[0063] In some embodiments, a monomolecular passivation layer 30 covers the third surface, as well as the amorphous silicon carbide layer 20, the tunneling oxide layer 70, the doped conductive layer 80, and the back passivation layer 100, which are flush with the third surface.

[0064] Reference Figure 2 As shown, Figure 2 This is a schematic diagram of a photovoltaic cell provided in another embodiment of this application. In some embodiments, the first surface includes a first region and a second region. The first region has a doped region 50. An amorphous silicon carbide layer 20 and a front passivation layer 40 are disposed on the second region. The front passivation layer 40 also covers the portion of the first surface in the first region where the doped region 50 is not disposed. The photovoltaic cell also includes a first electrode 60, which is electrically connected to the doped region 50.

[0065] In some embodiments, the second surface includes a third region and a fourth region. A tunneling oxide layer 70 and a doped conductive layer 80 are sequentially stacked on the third region. The doping type of the doped conductive layer 80 is different from that of the doped region 50. A back passivation layer 100 is disposed on the fourth region. The photovoltaic cell also includes a second electrode 90, which is electrically connected to the doped conductive layer 80.

[0066] In some embodiments, a monomolecular passivation layer 30 covers the third surface, as well as the amorphous silicon carbide layer 20 and the back passivation layer 100, which are flush with the third surface.

[0067] In some implementations, the photovoltaic cells are quarter-cell TOPCon cells.

[0068] Reference Figures 3-5 As shown, another embodiment of this application provides a method for preparing a photovoltaic cell, comprising the following steps:

[0069] A battery pre-product is provided, the battery pre-product including a substrate 10 having a first surface and a second surface disposed opposite to each other;

[0070] An amorphous silicon carbide layer 20 is formed on the first surface;

[0071] The battery pre-product is sliced ​​along the length of the amorphous silicon carbide layer 20 to form a third surface, thus obtaining the sliced ​​pre-product.

[0072] A monomolecular passivation layer 30 is formed on the third surface, and the material of the monomolecular passivation layer 30 includes a bifunctional silane coupling agent.

[0073] Furthermore, in the photovoltaic module preparation method of this application, the process steps of pre-encapsulation of amorphous silicon carbide layer 20, slab cutting, and monomolecular passivation layer 30 are not a simple superposition of steps, but rather a synergistic effect. The amorphous silicon carbide layer 20 can not only reduce cutting damage, but also provide an ideal substrate for subsequent molecular passivation, improve the passivation and repair effect of the bifunctional silane coupling agent on the third surface, and form a triple protection mechanism of physical isolation, chemical passivation, and repair. This enables the preparation of photovoltaic cells with lower edge recombination losses caused by cutting, thereby improving conversion efficiency.

[0074] In some embodiments, an amorphous silicon carbide layer 20 is prepared by atomic layer deposition using an aluminum source and a carbon source.

[0075] In some embodiments, forming a monomolecular passivation layer 30 on the third surface includes:

[0076] The third surface is passivated using a passivation solution, which includes a bifunctional silane coupling agent with a mass concentration of 0.2% to 1%.

[0077] For example, by passivating the third surface with a passivation solution, the pre-finished wafers after slicing can be transported by a specially designed roller conveyor, so that the front side is protected by a precisely controlled water film, while the third surface is exposed in a passivation solution containing a bifunctional silane coupling agent with a mass concentration of 0.2% to 1%. The -NH2, -SH, and -CH=CH at one end of the molecule can selectively bond to the metal or polycrystalline silicon that may be plated around it, while the siloxane at the other end combines with the substrate 10 or the amorphous silicon carbide layer 20 to form a monomolecular passivation layer 30.

[0078] Optionally, the mass concentration of the bifunctional silane coupling agent is 0.2%, 0.4%, 0.6%, 0.8%, or 1%, or the mass concentration of the bifunctional silane coupling agent may be within the range of any two of the above concentrations.

[0079] In some embodiments, the passivation solution is a solvent for deionized water.

[0080] In some embodiments, the passivation solution further includes a corrosion inhibitor at a mass concentration of 0.1% to 0.2%.

[0081] The corrosion inhibitor can protect non-target areas. Optionally, the mass concentration of the corrosion inhibitor is 0.1%, 0.12%, 0.14%, 0.16%, 0.18%, or 0.2%, or the mass concentration of the corrosion inhibitor may be within the range of any two of the above mass concentrations.

[0082] In some of these embodiments, the corrosion inhibitor includes polyvinylpyrrolidone.

[0083] In some embodiments, the passivation solution further includes a surfactant at a mass concentration of 0.05% to 0.1%.

[0084] Optionally, the mass concentration of the surfactant is 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%, or the mass concentration of the surfactant may be within the range of any two of the above concentrations.

[0085] In some embodiments, the passivation temperature is 25°C to 35°C.

[0086] Optionally, the passivation temperature is 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 34°C, or 35°C, or the passivation temperature can be within any two of the above temperatures.

[0087] In some embodiments, the passivation process takes 100s to 200s.

[0088] Optionally, the passivation treatment time is 100s, 120s, 140s, 160s, 180s, or 200s, or the passivation treatment time can be within any two of the above times.

[0089] For example, the passivation process can employ an overflow tank to ensure the freshness of the passivation solution, and the roller speed can be matched with the solution circulation speed to ensure uniform edge contact.

[0090] In some embodiments, after forming a monomolecular passivation layer 30 on the third surface, the method further includes:

[0091] The monomolecular passivation layer 30 is subjected to laser treatment.

[0092] For example, laser treatment of the monomolecular passivation layer 30 can be performed by scanning along the cut edge of the solar cell with specific low energy and high repetition frequency parameters. The laser treatment can achieve the following effects: (1) vaporization to remove the trace amount of plating residue not covered by the monomolecular passivation layer 30; (2) the instantaneous high energy field of the laser can activate the dehydration condensation reaction between the siloxane alkyl group and the silicon substrate, so that the monomolecular passivation layer 30 changes from physical adsorption to strong chemical bonding (Si-O-Si); (3) annealing the micro-area of ​​the cut surface to reduce the defect density.

[0093] In some embodiments, the pulse energy of the laser treatment is 10 μJ to 15 μJ.

[0094] Optionally, the pulse energy of the laser treatment is 10 μJ, 11 μJ, 12 μJ, 13 μJ, 14 μJ or 15 μJ, or the pulse energy of the laser treatment can be within the range of any two of the above energies.

[0095] In some embodiments, the pulse width of the laser processing is 200 fs to 400 fs.

[0096] Optionally, the pulse width of the laser processing is 200fs, 220fs, 250fs, 280fs, 300fs, 320fs, 350fs, 380fs or 400fs, or the pulse width of the laser processing can be within the range of any two of the above pulse widths.

[0097] In some embodiments, the laser processing frequency is 400kHz to 600kHz.

[0098] Optionally, the laser processing frequency is 400kHz, 420kHz, 450kHz, 480kHz, 500kHz, 520kHz, 550kHz, 580kHz or 600kHz, or the laser processing frequency may be within the range of any two of the above frequencies.

[0099] In some embodiments, the scanning rate of the laser processing is 100 mm / s to 150 mm / s.

[0100] Optionally, the scanning rate of the laser processing is 100 mm / s, 110 mm / s, 120 mm / s, 130 mm / s, 140 mm / s or 150 mm / s, or the scanning rate of the laser processing can be within the range of any two of the above rates.

[0101] In some embodiments, the laser processing spot overlap rate is 50% to 70%.

[0102] Optionally, the laser-processed spot overlap rate is 50%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, or 70%, or the laser-processed spot overlap rate can be within the range of any two of the above overlap rates.

[0103] Within the range of the parameters for each of the above laser processing methods, it is convenient to improve the accuracy of laser processing to achieve better activation and annealing effects on the edges of the segmented cutting.

[0104] Another embodiment of this application provides a method for preparing a photovoltaic cell, comprising the following steps:

[0105] A battery pre-product is provided, the battery pre-product including a substrate 10 having a first surface and a second surface disposed opposite to each other;

[0106] Boron diffusion is performed on the first surface to form a doped region 50;

[0107] A tunneling oxide layer 70 is prepared on the second surface;

[0108] An amorphous silicon carbide layer 20 is formed on the first surface;

[0109] A doped conductive layer 80, a back passivation layer 100, and a second electrode 90 are sequentially prepared on the tunneling oxide layer 70, and the second electrode 90 and the doped conductive layer 80 are electrically connected.

[0110] A front passivation layer 40 and a first electrode 60 are prepared on the first surface, and the first electrode 60 and the doped region 50 are electrically connected.

[0111] The battery pre-product is sliced ​​along the length of the amorphous silicon carbide layer 20 to form a third surface, thus obtaining the sliced ​​pre-product.

[0112] A monomolecular passivation layer 30 is formed on the third surface, and the material of the monomolecular passivation layer 30 includes a bifunctional silane coupling agent.

[0113] Another embodiment of this application provides a method for preparing a photovoltaic cell, comprising the following steps:

[0114] A battery pre-product is provided, the battery pre-product including a substrate 10 having a first surface and a second surface disposed opposite to each other;

[0115] Boron diffusion is performed on the first surface to form a doped region 50 in the first region;

[0116] A tunneling oxide layer 70 is prepared on the second surface;

[0117] An amorphous silicon carbide layer 20 is formed on the second region of the first surface;

[0118] A doped conductive layer 80 is sequentially prepared on the tunneling oxide layer 70, and the tunneling oxide layer 70 and the doped conductive layer 80 in the fourth region are removed.

[0119] A back passivation layer 100 and a second electrode 90 are prepared on the second surface, and the second electrode 90 and the doped conductive layer 80 are electrically connected.

[0120] A front passivation layer 40 and a first electrode 60 are prepared on the first surface, and the first electrode 60 and the doped region 50 are electrically connected.

[0121] The battery pre-product is sliced ​​along the length of the amorphous silicon carbide layer 20 to form a third surface, thus obtaining the sliced ​​pre-product.

[0122] A monomolecular passivation layer 30 is formed on the third surface, and the material of the monomolecular passivation layer 30 includes a bifunctional silane coupling agent.

[0123] It should be noted that in some embodiments of the photovoltaic cell preparation method of this application, after preparing the tunneling oxide layer 70 and before preparing the doped conductive layer 80, an amorphous silicon carbide layer 20 is formed on the first surface, which can have the following effects: (1) During the high-temperature deposition of the doped conductive layer 80, the amorphous silicon carbide layer 20 can be more densely and firmly bonded to the substrate 10 and become part of the edge structure; (2) During the subsequent high-temperature annealing / crystallization process of the doped conductive layer 80, the structure and hydrogen content of the amorphous silicon carbide layer 20 itself are also optimized, and its passivation performance and mechanical strength are simultaneously improved; (3) The amorphous silicon carbide layer 20 after the high-temperature process is more chemically stable, providing a more uniform and reliable reaction interface for the selective bonding of the monomolecular passivation layer 30.

[0124] Furthermore, one of the core aspects of the photovoltaic cell fabrication method in this application lies in "source protection, edge passivation, and energy activation." It abandons the chemical cleaning of the already formed coating, instead strengthening the edges before problems occur (i.e., pre-encapsulation), precisely passivating them after problems occur using SAMs molecules with chemical recognition capabilities, and finally using ultra-high precision femtosecond lasers for final repair and performance activation. This is a complete, closed-loop solution from macroscopic structural protection to microscopic chemical bonding. This forms a triple protection mechanism of physical isolation, chemical passivation, and repair, enabling the fabrication of photovoltaic cells with lower edge recombination losses due to cutting, thereby improving conversion efficiency.

[0125] Another embodiment of this application provides a tandem solar cell, including a composite layer and a top cell and a bottom cell respectively located on two opposite surfaces of the composite layer; at least one of the top cell and the bottom cell is a photovoltaic cell of any one of the above, or a photovoltaic cell prepared by any one of the above photovoltaic cell preparation methods.

[0126] In some embodiments, the tandem cell is a perovskite / crystalline silicon tandem cell.

[0127] In some embodiments, the tandem cell is a crystalline silicon / crystalline silicon tandem cell.

[0128] Another embodiment of this application provides a photovoltaic module, including:

[0129] Cover plate;

[0130] At least one battery string, the battery string comprising a photovoltaic cell of any one of the above, or a photovoltaic cell prepared by any one of the above methods, or a tandem battery as described above.

[0131] And the encapsulation layer, which is located between the cover plate and the battery string, with the cover plate connected to the battery string through the encapsulation layer.

[0132] The following are specific examples:

[0133] Example 1

[0134] Methods for preparing photovoltaic cells:

[0135] (1) After the boron diffusion on the front side and the tunneling oxide layer 70 on the back side of the silicon wafer are completed, before the polycrystalline silicon deposition on the back side, an amorphous silicon carbide layer 20 is selectively deposited in the pre-defined laser cutting area (approximately 200 μm wide) on the front side of the silicon wafer using a space ALD equipment. Precursors: trimethylaluminum (TMA) as the aluminum source, ethylene (C2H4) as the carbon source, and plasma-assisted deposition. Process parameters: temperature 200°C, pressure 150 mbar, and the number of cycles is precisely controlled to achieve a thickness of 6 nm.

[0136] (2) After the solar cell has been fully coated and metallized, laser scribing and splitting are performed to obtain quarter-sized pieces.

[0137] (3) Preparation and process of self-assembled molecule treatment solution: Deionized water as the main component, 0.5 wt% 3-mercaptopropyltrimethoxysilane, 0.15 wt% polyvinylpyrrolidone, and 0.08 wt% surfactant. Process: The treatment temperature is 30°C and the time is 150 s. The quartered pieces are transported through a specially designed roller conveyor so that the front side is protected by a precisely controlled water film. An overflow tank is used to ensure the freshness of the solution. The roller speed is matched with the solution circulation speed to ensure uniform edge contact. The thiol group at one end of the molecule selectively bonds to the metal or polycrystalline silicon that may be plated around it, while the siloxane group at the other end combines with the silicon body or pre-encapsulation layer to form a monomolecular passivation layer 30.

[0138] (4) After molecular layer treatment and drying, the cells are transferred to the laser processing station. Femtosecond laser repair parameters: Laser: wavelength 1030nm, pulse width 300 femtoseconds, repetition frequency 500kHz. Processing parameters: pulse energy 12μJ, scanning speed 120mm / s, spot overlap rate 60%. A coaxial vision positioning system is used to ensure that the alignment accuracy between the scanning path and the cutting edge is within ±5μm. A femtosecond laser is used with specific low energy and high repetition frequency parameters to scan along the four cutting edges of the solar cell.

[0139] Comparative Example 1

[0140] The preparation method of the photovoltaic cell in Comparative Example 1 is basically the same as that in Example 1, except that the amorphous silicon carbide layer 20 is not prepared.

[0141] Comparative Example 2

[0142] The preparation method of photovoltaic cells in Comparative Example 2 is basically the same as that in Example 1, except that steps (3) and (4) are not performed.

[0143] Comparative Example 3

[0144] In Comparative Example 3, the photovoltaic cell was prepared using a conventional slab method, without preparing an amorphous silicon carbide layer 20, and without performing steps (3) and (4).

[0145] The photovoltaic cells prepared in Example 1 and Comparative Examples 1 to 3 were tested, and the test results are shown in the table below:

[0146] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 <![CDATA[Composite current density (fA / cm 2 )]]> 1.2 1.8 3 4.5 Open-circuit voltage Uoc (V) 0.73 0.725 0.718 0.710 Short-circuit current Isv (A) 10.52 10.48 10.4 10.35 Fill factor (FF) 85.5 85 84 82.5 Conversion efficiency Eta (%) 26.3 25.8 25.1 24.8

[0147] The photovoltaic cell prepared in Example 1 of this application has lower edge recombination loss due to cutting compared with the photovoltaic cells prepared in Comparative Examples 1 to 3, thus achieving higher conversion efficiency.

[0148] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0149] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A photovoltaic cell, characterized in that, The substrate includes a first surface and a second surface disposed opposite to each other; an amorphous silicon carbide layer is disposed on the first surface; the substrate further includes a third surface connecting the first surface and the second surface, a monomolecular passivation layer is disposed on the third surface, the monomolecular passivation layer includes a bifunctional silane coupling agent; the amorphous silicon carbide layer is disposed at the edge of the first surface near the third surface.

2. The photovoltaic cell according to claim 1, characterized in that, The bifunctional silane coupling agent has at least one of -NH2, -SH, -CH=CH2 and -epoxy groups, and the bifunctional silane coupling agent also has at least one of -Si(OCH3)3 and -Si(OC2H5)3.

3. The photovoltaic cell according to claim 2, characterized in that, The bifunctional silane coupling agent includes at least one of 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, and epoxysilane.

4. The photovoltaic cell according to claim 1, characterized in that, Along the width direction of the substrate, the width of the amorphous silicon carbide layer accounts for 0.1% to 0.3% of the width of the substrate.

5. The photovoltaic cell according to claim 1, characterized in that, The amorphous silicon carbide layer satisfies at least one of the following characteristics: (1) The thickness of the amorphous silicon carbide layer is 5nm~8nm; (2) The width of the amorphous silicon carbide layer is 90μm~110μm.

6. A method for preparing a photovoltaic cell, characterized in that, Includes the following steps: A battery pre-product is provided, the battery pre-product including a substrate having a first surface and a second surface disposed opposite to each other; An amorphous silicon carbide layer is formed on the first surface; The battery pre-product is sliced ​​along the length of the amorphous silicon carbide layer to form a third surface, thus obtaining a sliced ​​pre-product. A monomolecular passivation layer is formed on the third surface, the material of which includes a bifunctional silane coupling agent.

7. The method for preparing a photovoltaic cell according to claim 6, characterized in that, Forming a monomolecular passivation layer on the third surface includes: The third surface is passivated using a passivation solution comprising a bifunctional silane coupling agent at a mass concentration of 0.2% to 1%.

8. The method for preparing a photovoltaic cell according to claim 7, characterized in that, The passivation treatment of the third surface using a passivation solution satisfies at least one of the following characteristics: (1) The passivation solution also includes a corrosion inhibitor with a mass concentration of 0.1% to 0.2%; (2) The passivation solution further includes a surfactant with a mass concentration of 0.05% to 0.1%; (3) The passivation treatment temperature is 25℃~35℃; (4) The passivation treatment time is 100s~200s.

9. The method for preparing a photovoltaic cell according to any one of claims 6 to 8, characterized in that, After forming a monomolecular passivation layer on the third surface, the process further includes: The monomolecular passivation layer is subjected to laser treatment.

10. The method for preparing a photovoltaic cell according to claim 9, characterized in that, The laser processing satisfies at least one of the following characteristics: (1) The pulse energy of the laser treatment is 10μJ~15μJ; (2) The pulse width of the laser processing is 200fs~400fs; (3) The frequency of the laser processing is 400kHz~600kHz; (4) The scanning rate of the laser processing is 100 mm / s to 150 mm / s; (5) The laser spot overlap rate is 50%~70%.

11. A stacked battery, characterized in that, It includes a composite layer, and a top cell and a bottom cell respectively located on two opposite surfaces of the composite layer; at least one of the top cell and the bottom cell is a photovoltaic cell according to any one of claims 1 to 5, or a photovoltaic cell prepared by the method of preparing a photovoltaic cell according to any one of claims 6 to 10.

12. A photovoltaic module, characterized in that, include: Cover plate; At least one battery string, the battery string comprising a photovoltaic cell according to any one of claims 1 to 5, or a photovoltaic cell prepared by the method of preparing a photovoltaic cell according to any one of claims 6 to 10, or a tandem cell according to claim 11; And an encapsulation layer, which is located between the cover plate and the battery string, and the cover plate is connected to the battery string through the encapsulation layer.

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