Solar cell, preparation method thereof and photovoltaic module

Abstract

The invention provides a solar cell, a preparation method thereof and a photovoltaic module, and relates to the field of photovoltaic technology. The solar cell includes: a cell body including a first surface and a second surface opposite to each other in a thickness direction thereof, and a plurality of side surfaces connecting the first surface and the second surface; at least one side surface of the plurality of side surfaces is provided with one or more concave pits which are concave towards the interior of the battery body, and the one or more concave pits surround the at least one side surface. Compared with a flat surface, the pits have obvious recesses, so that the pits can prevent the corrosive liquid in the chain type equipment from continuously moving towards the first surface or the second surface which is not immersed in the corrosive liquid, and the damage to the surface edge film layer of the solar cell which is not immersed in the corrosive liquid is further avoided.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and in particular to a solar cell, its preparation method, and a photovoltaic module. Background Technology

[0002] Solar cells are devices that directly convert light energy into electrical energy through the photoelectric effect or photochemical effect. Because they utilize clean energy, they have broad application prospects.

[0003] In solar cells, the quality of each film layer directly affects the performance of the solar cell. In existing solar cells, the quality of each film layer is not ideal, especially the quality of the film layer edges, which has a significant impact on the performance of the solar cell. Summary of the Invention

[0004] This invention provides a solar cell, its preparation method, and a photovoltaic module, aiming to solve the problem of poor quality of various film layers in existing solar cells.

[0005] A first aspect of the present invention provides a solar cell comprising:

[0006] The battery body includes: a first surface and a second surface opposite to each other along its thickness direction, and a plurality of side surfaces connecting the first surface and the second surface;

[0007] At least one of the plurality of sides is provided with one or more recesses that are recessed toward the interior of the battery body, the one or more recesses surrounding the at least one side.

[0008] In this application, the aforementioned recesses surrounding at least one side achieve effective isolation between the first and second surfaces of the battery body during the chain-processing. Specifically, during the chain-processing of cleaning one of the first and second surfaces of the battery body, the location of the recesses prevents the corrosive liquid within the chain-processing equipment from continuing to move towards the other surface of the first and second surfaces that is not immersed in the corrosive liquid. This prevents damage to the other surface of the first and second surfaces by the corrosive liquid within the chain-processing equipment, thus avoiding film thinning or localized perforation on the other surface. Therefore, the fabrication process of the film layer on the first surface of the battery body has minimal impact on the fabrication process of the film layer on the second surface of the battery body, improving the quality of the film layers on the first and second surfaces, especially the film layer quality at the edges of the first and second surfaces. For example, it can improve the passivation effect and reduce metal recombination, thereby improving the performance of the solar cell.

[0009] In some alternative embodiments, adjacent pits are spaced apart or arranged continuously in the direction surrounding the battery body.

[0010] The continuous arrangement of adjacent pits without gaps provides better isolation between the first and second surfaces, further improving the quality of the film layer on both surfaces and thus enhancing the performance of the solar cell. The spacing between adjacent pits allows for a larger processing window for the pits.

[0011] In some alternative embodiments, one or more recesses are located on the edge of the at least one side near the first surface, which is either the front or the back side.

[0012] This solar cell can be a bifacial solar cell or a back-contact solar cell. The aforementioned pits improve the quality of the film layer on both the first and second surfaces, further enhancing the performance of the solar cell. The pits are spaced apart, providing a relatively large processing window.

[0013] In some alternative embodiments, one or more pits are located on the edge of the at least one side near the first surface, and the one or more pits are located on the edge of the at least one side near the second surface.

[0014] This solar cell can be a bifacial solar cell. The aforementioned pits improve the quality of the film layers on both the first and second surfaces, further enhancing the performance of the solar cell. The pits are spaced apart, providing a relatively large processing window.

[0015] In some optional embodiments, the at least one side is further provided with one or more first steps in a direction perpendicular to the side, the one or more first steps surround the at least one side, and at least one surface of the first step is connected to a first boundary edge, the bottom wall of the first step and near the side wall are provided with one or more recesses, the first boundary edge is the boundary edge between the side and the first face, and the first face is the front or the back.

[0016] The first step located on the side, and the aforementioned recess located on the bottom wall of the first step and near the side wall, can further enhance the isolation effect on the first and second surfaces. This achieves good isolation between the first and second surfaces in the cell body along its thickness direction. Therefore, the fabrication processes of the film layer on the first surface of the cell body and the film layer on the second surface of the cell body will not interfere with each other, improving the quality of the film layers on the first and second surfaces and further enhancing the performance of the solar cell. In addition, the side with the recess and the first step provides more refractive surfaces, allowing incident light from the side or reflected / refracted light from inside the solar cell to undergo more refractions or reflections on the side, increasing the absorption and utilization rate of light by the solar cell, thereby further improving the photoelectric conversion efficiency of the cell.

[0017] In some optional embodiments, the at least one side is further provided with one or more first steps and one or more second steps in a direction perpendicular to the side. The one or more first steps surround the at least one side, and at least one surface of the first step is connected to a first boundary edge, which is the boundary edge between the side and the first surface. The one or more second steps surround the at least one side, and at least one surface of the second step is connected to a second boundary edge, which is the boundary edge between the side and the second surface. The first step has a recess near its side wall at the bottom wall, and the second step has a recess near its side wall at the bottom wall.

[0018] The solar cell features a first step, a recess located on the bottom wall of the first step near the side wall, and a second step, also with the aforementioned recess located on the bottom wall of the second step near the side wall. The recess near the side wall of the first step protects the film layer at the edge of the first surface from corrosion. Similarly, the recess near the side wall of the second step protects the film layer at the edge of the second surface from corrosion. Therefore, by providing two step structures and two recesses, the quality of the film layer on both the first and second surfaces can be improved simultaneously, further enhancing the performance of the solar cell. Furthermore, the side surface with the recesses, the first step, and the second step provides more refractive surfaces, allowing incident light or reflected / refracted light from within the solar cell to undergo more refractions or reflections on the side surface, increasing the solar cell's light absorption and utilization rate, thereby further improving the photoelectric conversion efficiency of the cell.

[0019] In some optional embodiments, along the thickness direction of the battery body, the bottom walls of the first step and the second step are located on the same plane, and the depth of the pit provided on the bottom wall of the first step is greater than the depth of the pit provided on the bottom wall of the second step.

[0020] In some optional embodiments, the first side is the front side and the second side is the back side; the battery body includes: a silicon substrate, a first doped layer and a second doped layer; the doping types of the first doped layer and the second doped layer are opposite;

[0021] The first doped layer is a monolithic structure, or the first doped layer includes: a plurality of first doped regions, with adjacent first doped regions spaced apart;

[0022] The second doped layer is a solid layer structure, or the second doped layer includes: a plurality of second doped regions, adjacent second doped regions are spaced apart, a first texture structure is provided in the spaced regions between adjacent second doped regions, the first texture structure is provided in the pit, and the first texture structure is a tower base structure or a pyramid-like structure.

[0023] In some optional embodiments, the first side is the back side and the second side is the front side; the battery body includes: a silicon substrate, a first doped layer and a second doped layer disposed on the second side; the first doped layer and the second doped layer have opposite doping types, the first doped layer includes a plurality of first doped regions, and the second doped layer includes a plurality of second doped regions; the first doped regions and the second doped regions are spaced apart and alternately distributed, and a second texture structure is disposed in the space between the first doped regions and the second doped regions, and the second texture structure is disposed in the pit, the second texture structure being a tower base structure or a pyramid-like structure.

[0024] This solar cell can be a bifacial solar cell or a back-contact solar cell. The aforementioned pits improve the quality of the film layer on both the first and second surfaces, further enhancing the performance of the solar cell. The pits are spaced apart, providing a relatively large processing window.

[0025] In some alternative embodiments, adjacent first steps are spaced apart or arranged continuously in the direction surrounding the battery body.

[0026] The continuous arrangement of adjacent first steps without gaps provides better isolation between the first and second surfaces, further improving the quality of the film layers on both surfaces and thus enhancing the performance of the solar cell. The spacing between adjacent first steps allows for a larger processing window for the first step.

[0027] In some optional embodiments, the pits and the first steps are arranged in an intersecting manner, with adjacent pits spaced apart and adjacent first steps spaced apart. This allows the corrosive liquid in areas not blocked by the pits to be blocked by the first steps, thereby preventing corrosion of the process surface (e.g., the first surface) by the corrosive liquid during the chain cleaning process.

[0028] In some optional embodiments, the width of the pit along the thickness direction is from 1 μm to 140 μm; and / or,

[0029] In a direction perpendicular to the side, the depth of the indentation facing inward is 0.2 μm to 10 μm.

[0030] If the width of the pit is too small, the isolation effect on the first and second surfaces will be poor. If the width of the pit is too large, the damage to the side of the battery body may be too great. Therefore, the width of the pit is 1μm to 140μm, which not only provides a good isolation effect on the first and second surfaces, but also keeps the damage to the side of the battery body within an acceptable range, and the mechanical properties of the side of the battery body are better.

[0031] The greater the depth of the pit, the better the isolation effect on the first and second surfaces. If the pit depth is too small, the isolation effect on the first and second surfaces is poor. If the pit depth is too large, the damage to the side of the battery body may be too great. Therefore, a pit depth of 0.2μm to 10μm not only provides a good isolation effect on the first and second surfaces, but also keeps the damage to the side of the battery body within an acceptable range, resulting in better mechanical properties of the side of the battery body.

[0032] In some alternative embodiments, the width of the first step along the thickness direction is 0.1 μm to 20 μm; and / or,

[0033] In the direction perpendicular to the side, the height of the first step is 0.1 μm to 10 μm.

[0034] The wider the first step, the better the isolation effect on the first and second surfaces. However, if the width of the first step is too large, it will make it difficult to move or transport the battery body or battery. The first step is also prone to bumps and knocks, which may cause it to break or crack. Therefore, the width of the first step is 0.1μm to 20μm. This not only provides good isolation between the first and second surfaces, but also does not affect the movement or transport of the battery or battery. The first step is also less prone to breakage or cracking.

[0035] The greater the height of the first step, the better the isolation effect on the first and second surfaces. However, if the height of the first step is too large, it will make it difficult to move or transport the battery body or battery. The first step is also prone to being bumped or knocked, which may cause it to break or crack. Therefore, the height of the first step is 0.1μm to 10μm. This not only provides good isolation between the first and second surfaces, but also has virtually no impact on the movement or transport of the battery or battery. The first step is also less likely to break or crack.

[0036] In some optional embodiments, the distance of the indentation from the boundary edge along the thickness direction of the battery body is less than or equal to 1 / 3 of the thickness of the battery body, and the boundary edge is the boundary edge between the plurality of side surfaces and the first surface.

[0037] In some optional embodiments, the recess is provided on two of the plurality of sides, and the two sides are disposed opposite to each other; or,

[0038] The recesses are provided on three of the plurality of sides.

[0039] A second aspect of the present invention provides a method for preparing a solar cell, comprising:

[0040] A semiconductor is provided; the semiconductor includes: two surfaces opposite each other along its thickness direction, and a plurality of side surfaces connecting the two surfaces;

[0041] A laser irradiates local areas of multiple sides of the semiconductor and cleans the multiple sides to form one or more pits that are recessed inward on at least one of the multiple sides, the one or more pits surrounding at least one side of the semiconductor.

[0042] In this preparation method, the laser disperses the irradiated local area of ​​at least one of the multiple sides. During the etching and cleaning process, the dispersed areas are more easily cleaned, while the areas not irradiated by the laser are irradiated more slowly. Therefore, pits are easily formed at and around the laser-irradiated area on at least one of the multiple sides. Here, the laser can surround at least one of the multiple sides of the semiconductor, so the pits are also formed around at least one side of the semiconductor. In the subsequent cleaning process, the pits can prevent liquid creep, thereby reducing co-doping and recombination.

[0043] In some optional embodiments, the step of providing the semiconductor includes: providing a silicon substrate; sequentially distributing a full-surface first doped layer and a full-surface first mask layer on one side of the silicon substrate along the thickness direction of the silicon substrate; the first mask layer covering at least a portion of the plurality of sides;

[0044] The laser process includes:

[0045] The first doped layer and the first mask layer are patterned using a laser, and local areas of multiple sides of the semiconductor are irradiated using a laser.

[0046] The patterning laser step of the first doped layer and the laser step of forming pits on the side are performed in the same step, which can simplify the process and improve production efficiency.

[0047] In some optional embodiments, the step of providing the semiconductor further includes: sequentially distributing a full-surface second doped layer and a full-surface first mask layer along the thickness direction of the silicon substrate on another side of the silicon substrate; the first mask layer covers at least a portion of the plurality of side surfaces; the second doped layer and the first doped layer have different doping types;

[0048] The laser process also includes:

[0049] The second doped layer and the first mask layer are patterned using a laser, and local areas of multiple sides of the semiconductor are irradiated using a laser.

[0050] The patterning laser step for the second doped layer and the laser step for forming pits on the side are performed in the same step, which can simplify the process and improve production efficiency.

[0051] In some optional embodiments, the cleaning step includes:

[0052] A second mask layer is disposed outside the first mask layer along the thickness direction of the semiconductor; the silicon substrate is more hydrophobic than the first mask layer;

[0053] Under the protection of the second mask layer, the plurality of sides are etched and cleaned using a chain equipment; during the cleaning process, the second mask layer is located outside the etching solution inside the chain equipment, and of the two sides of the semiconductor, the side without the second mask layer is located in the etching solution of the chain equipment;

[0054] Wherein, the thickness of the first mask layer is 50nm to 100nm, and the conveying speed of the chain device to the semiconductor is 1m / min to 3.5m / min; when the semiconductor is placed on the conveyor belt of the chain device, the height of the etching solution covering the semiconductor in the chain device is less than or equal to 2 / 3 of the thickness of the semiconductor.

[0055] During the cleaning process, the first mask layer in the laser-irradiated area on the side and its vicinity is easily washed away due to laser dispersion, forming pits that expose the more hydrophobic side of the silicon substrate. As the etching solution in the chain-connector climbs to the exposed side of the silicon substrate, the silicon substrate, being more hydrophobic than the first mask layer, prevents the etching solution from continuing to move towards the location of the second mask layer. This avoids damage and dilution of the second mask layer by the etching solution within the chain-connector. The second mask layer can then be filled... The first mask layer and the first doped layer are protected by the second mask layer, preventing thinning or local perforation of the first mask layer. Consequently, during the subsequent formation of the second doped layer, the first mask layer effectively prevents co-doping between the second and first doped layers. Because this application prevents co-doping, the leakage risk of the solar cell is very low. Furthermore, since the second mask layer effectively protects the first mask layer and the first doped layer, preventing thinning or local perforation of the first mask layer, the quality of the first doped layer beneath the second mask layer is better, and the passivation effect is also better. In addition, if the first mask layer is thinned or locally perforated, metal elements can enter the silicon substrate through the thinned or perforated sites during electrode metallization, forming severe metal recombination. Therefore, in this application, the first mask layer remains essentially unchanged during the etching and cleaning process, without thinning or perforation, and metal elements cannot enter the silicon substrate through the thinned or perforated sites. Thus, this application reduces metal recombination.

[0056] The thickness of the first mask layer, the transmission speed of the chain equipment to the semiconductor, and the height of the etchant covering the semiconductor in the chain equipment are all related to the degree of liquid turnover of the etchant in the chain equipment and the cleaning efficiency. In this application, by controlling the thickness of the first mask layer, the transmission speed of the chain equipment to the semiconductor, and the height of the etchant covering the semiconductor in the chain equipment within the corresponding ranges, not only can the degree of liquid turnover of the etchant in the chain equipment be controlled to avoid co-doping, but the cleaning efficiency is also higher.

[0057] In some optional embodiments, when the semiconductor is a single solar cell, the second mask layer is a liquid mask with a capacity of 20 ml to 60 ml; and / or,

[0058] The etching solution in the chain device covers the semiconductor to a height of 30 μm to 100 μm.

[0059] In this application, the height of the etchant covering the semiconductor within the chain equipment is within a corresponding range, which not only controls the degree of liquid turbulence within the chain equipment and avoids co-doping, but also achieves high cleaning efficiency.

[0060] A third aspect of the present invention provides a photovoltaic module comprising: a plurality of battery strings connected in series and / or in parallel, the battery strings comprising: a solar cell prepared by any of the foregoing solar cells or by any of the preparation methods, and an electrical connector electrically connecting at least two of the solar cells.

[0061] The aforementioned solar cells and their preparation methods, as well as photovoltaic modules, have the same or similar beneficial effects, and will not be repeated here to avoid repetition. Attached Figure Description

[0062] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0063] Figure 1 A partial structural schematic diagram of a first type of solar cell in an embodiment of the present invention is shown;

[0064] Figures 2 to 3 Several partial SEM images of the side of the solar cell in an embodiment of the present invention are shown;

[0065] Figure 4 A partial structural schematic diagram of a chain-type equipment cleaning method is shown in an embodiment of the present invention;

[0066] Figure 5A schematic diagram of the semiconductor structure before cleaning is shown in an embodiment of the present invention;

[0067] Figure 6 A schematic diagram showing the performance comparison between the solar cell in the embodiment of the present invention and the solar cell in the comparative example is provided.

[0068] Explanation of the attached drawing numbers:

[0069] 1-Pit, 2-Silicon substrate, 3-First step, 31-Sidewall of the first step, 32-Bottom wall of the first step, 4-First doped layer, 5-Second doped layer, 6-First passivation and antireflection layer, 7-Tunneling layer, 8-Second passivation and antireflection layer, 9-First electrode, 10-Second electrode, 11-Semiconductor, 12-Second mask layer, 13-Etching solution, 14-Conveyor belt, 15-Drive roller, 16-First mask layer, 17-Third mask layer, 18-Second step, 181-Sidewall of the second step, 182-Bottom wall of the second step. Detailed Implementation

[0070] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0071] One important reason for the poor quality of the various film layers in the existing solar cells is that, along their thickness direction, the first and second film layers may be subject to certain process interferences during the preparation and cleaning process, especially in chain processes. In other words, the preparation processes of the first and second film layers of the solar cell may influence each other, affecting the quality of the first and second film layers and reducing the performance of the solar cell. To address the aforementioned technical problems, one technical concept of this application is as follows: a recess is provided on at least one side of the battery body connecting the first and second sides, and the recess surrounds at least one side of the battery body. Compared to a flat surface, the recess 1 has a significant depression. The location of the recess 1 increases the degree of isolation between the first and second sides during the chain process. Specifically, during the cleaning of one of the first and second sides of the battery body using a chain equipment, the location of the recess can prevent the corrosive liquid in the chain equipment from continuing to move to the other side of the first and second sides. Therefore, the corrosive liquid in the chain equipment can be prevented from damaging and diluting the other side of the first and second sides, thus preventing the film layer of the other side of the first and second sides from thinning or locally perforating. In this application, by providing the aforementioned recesses 1 surrounding at least one side of the battery body, good isolation is achieved in the thickness direction E during the chain-processing of the first and second sides of the battery body. This reduces the mutual influence between the fabrication processes of the film layer on the first side and the film layer on the second side of the battery body. For example, it can improve the passivation effect and reduce metal recombination, thereby improving the quality of the film layers on the first and second sides, especially the film layer quality at the periphery of the first or second side, and thus improving the performance of the solar cell. For example, during the chain cleaning process, the recesses surrounding the battery body can help prevent the corrosion liquid from creeping up, thereby reducing the impact on the film layer on the upper surface during the chain cleaning process.

[0072] It is understood that, in the solar cell provided in this application, everything except the electrode structure can be considered the cell body. The cell body includes a first surface and a second surface opposite to each other along its thickness direction E, and multiple side surfaces connecting the first surface and the second surface. Of the first surface and the second surface, one is the front side and the other is the back side. For example... Figure 1 The bottom of the solar cell is the back, the top is the front, and the side facing it is a side surface. During solar cell operation, the front surface is the main surface of the cell that receives sunlight, while the back surface is opposite the front. The side surface is any surface of the cell other than the first and second sides, and it connects the front and back surfaces.

[0073] In this application, SEM images refer to scanning electron microscope images. (See reference...) Figure 1 and Figure 2At least one of the multiple sides is provided with one or more recesses 1 that are recessed toward the interior of the battery body, and the recesses 1 surround at least one side of the battery body. The recesses 1 have a tendency to be recessed toward the interior of the battery body, and the specific degree of recess is not limited. Figure 2 The red dashed lines in the middle show the partial outlines of the two pits. Figure 1 The dashed ellipse with an arrow indicates the direction F around the battery body. (Refer to...) Figure 1 The direction F of the circumference is parallel to the first and second surfaces and perpendicular to the thickness direction E of the battery body. This circumference includes, but is not limited to, the following situations: first, a continuous pit 1 is formed around at least one side of the battery body; second, multiple pits 1 intermittently form a pit ring around at least one side of the battery body. Whether it is a single pit 1 surrounding at least one side of the battery body or multiple pits 1 surrounding at least one side of the battery body, the number of pit rings can be greater than or equal to one.

[0074] Compared to a flat surface, pit 1 has a noticeable depression. The location of pit 1 increases the isolation between the first and second surfaces. In this application, by setting the pit 1 around the battery body, good isolation between the first and second surfaces in the chain process of the battery body is achieved in the thickness direction E. Specifically, during the process of cleaning one of the first and second surfaces of the battery body using a chain equipment, the location of the pit can prevent the corrosive liquid in the chain equipment from continuing to move to the other side of the first and second surfaces. Therefore, the corrosive liquid in the chain equipment can be avoided from damaging and diluting the other side of the first and second surfaces, and the thinning or local perforation of the film layer on the other side of the first and second surfaces can be avoided. Therefore, the preparation process of the film layer on the first surface of the battery body has little impact on the preparation process of the film layer on the second surface of the battery body, improving the quality of the film layer on the first and second surfaces. For example, it can improve the passivation effect and reduce metal recombination, thereby improving the performance of the solar cell. In addition, the recessed side provides more refractive surfaces, allowing incident light or reflected / refracted light from inside the solar cell to undergo more refractions or reflections on the side, increasing the absorption and utilization rate of light by the solar cell, thereby further improving the photoelectric conversion efficiency of the cell.

[0075] It should be noted that when there are multiple pits 1 on the side, the specific number of pits 1 is not limited. If the battery body includes a silicon substrate, the pits can be located on the side of the silicon substrate 2. The silicon substrate provides support for the various film layers in the solar cell and has functions such as light absorption, conductivity, and current collection. The type of silicon substrate is not limited here. The doping type of the silicon substrate is also not limited; it can have N-type or P-type doping. The crystal type of the silicon substrate is also not limited; for example, the crystal type of the silicon substrate can be single crystal, microcrystalline, amorphous, polycrystalline, etc.

[0076] Understandably, the pits can be created using lasers. For example, the laser can be directed at the edge, or directed at the outer side of the front or back, but the affected area on the side will form a pit.

[0077] It is also understandable that, in the case where only one of the multiple sides has a recess 1, the extension direction of the recess 1 can be parallel to the boundary edge where the first side intersects with the first surface.

[0078] In some possible embodiments, a pit 1 is provided on at least one of the multiple sides, which may include the side with the pit 1 located furthest forward in the forward direction of the chain device. Specifically, during the process of cleaning one of the first and second surfaces of the battery body using the chain device, the side furthest forward in the forward direction of the chain device experiences a relatively greater impact from the corrosive liquid. Therefore, the corrosion liquid tends to spread more severely on this side, resulting in greater damage and dilution to the other surface between the first and second surfaces. Thus, the pit 1 located on the furthest forward side in the forward direction of the chain device effectively prevents the corrosion liquid inside the chain device from continuing to move towards the other surface between the first and second surfaces, further improving the performance of the solar cell.

[0079] In some possible embodiments, recesses 1 are provided on two of the multiple sides, which are arranged opposite each other. This arrangement significantly prevents liquid seepage from the opposite sides, further improving the performance of the solar cell. For example, the two opposite sides may include two sides facing each other in a direction perpendicular to the forward direction of the chain device.

[0080] In some possible embodiments, recesses 1 are provided on three of the multiple sides. These three sides may include the side furthest forward in the forward direction of the chain device, which can further improve the performance of the solar cell. For example, the three sides here may include the side furthest forward in the forward direction of the chain device, and two opposite sides in a direction perpendicular to the forward direction of the chain device. That is, recesses 1 are provided on the side furthest forward in the forward direction of the chain device, and recesses 1 are provided on the two opposite sides in a direction perpendicular to the forward direction of the chain device.

[0081] In some possible embodiments, pits 1 are provided on all of the multiple sides, and the pits 1 on all sides surround the battery body. During the process of cleaning one of the first and second surfaces of the battery body using a chain-type device, the pits on all the aforementioned sides provide stronger resistance to liquid seepage, further improving the performance of the solar cell. For example, if the multiple sides include four sides in total, then pits 1 are provided on all four sides, and the pits 1 on the four sides surround the battery body.

[0082] In some possible embodiments, adjacent recesses 1 are arranged continuously or spaced apart in a direction surrounding the battery body or surrounding at least one side. For example, Figure 2 In this configuration, adjacent pits 1 are spaced apart. "Continuously arranged adjacent pits 1" means that at least two adjacent pits 1 are connected as a single unit in the direction surrounding the battery body or at least one side. "Spaced apart" means that at least two adjacent pits 1 are spaced apart in the direction surrounding the battery body or at least one side. For example, Figure 1 The pits 1 shown are mostly spaced apart, with some adjacent pits 1 continuously connected as a single unit. Compared to the case where adjacent pits 1 are spaced apart, the continuous arrangement of adjacent pits 1 without gaps provides better isolation between the first and second surfaces, further improving the film quality on the first and second surfaces and thus enhancing the performance of the solar cell. The spaced-apart pit arrangement allows for a larger processing window. For continuously arranged pits, the degree of connectivity between adjacent pits 1 is not limited.

[0083] In some possible embodiments, along the thickness direction E of the battery body, the width H1 of the pit 1 is from 1 μm to 140 μm. A larger width H1 provides better isolation between the first and second surfaces, while a smaller width H1 results in poorer isolation. Conversely, a larger width H1 may cause excessive damage to the sides of the battery body. Therefore, a width H1 of 1 μm to 140 μm not only provides effective isolation between the first and second surfaces but also keeps the damage to the sides of the battery body within acceptable limits, resulting in better mechanical properties of the sides of the battery body. Further, the width H1 of the pit 1 is from 2 μm to 20 μm.

[0084] For example, the width H1 of the pit 1 can be 1μm, 1.3μm, 1.5μm, 2μm, 2.5μm, 3μm, 5μm, 8μm, 10μm, 13μm, 15μm, 20μm, 25μm, 30μm, 33μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 63μm, 65μm, 69μm, 70μm, 75μm, 80μm, 83μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, or 140μm.

[0085] The width of pit 1 can be determined in ways including but not limited to the following: the distance between the two farthest boundaries of a pit along the thickness direction E of the battery body on the side; or the arithmetic mean of the widths of multiple pits, where multiple refers to two or more.

[0086] In some possible embodiments, the depth D1 of the indentation 1 towards the inward recess in the direction perpendicular to the side is 0.2 μm to 10 μm. A larger depth D1 of the indentation 1 provides better isolation between the first and second surfaces; a smaller depth D1 results in poor isolation between the first and second surfaces; and a larger depth D1 may cause excessive damage to the side of the battery body. Therefore, a depth D1 of 0.5 μm to 10 μm not only provides effective isolation between the first and second surfaces but also keeps the damage to the side of the battery body within an acceptable range, resulting in better mechanical properties of the side of the battery body. It is understood that since the side is non-planar, the direction perpendicular to the side can refer to the direction perpendicular to the base plane of the side. Further, the depth D1 of the indentation 1 towards the inward recess is 0.5 μm to 3 μm.

[0087] For example, the depth D1 of pit 1 can be 0.2μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.55μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, 5μm, 8μm, or 10μm.

[0088] The depth D1 of pit 1 can be determined in ways including but not limited to the following: the vertical distance between the lowest point of a pit and the plane containing the non-pit area in the direction towards the interior of the battery body or towards the geometric center of the battery body; or the arithmetic mean of the depths of multiple pits, where multiple refers to two or more.

[0089] In some possible embodiments, one or more first steps 3 are further provided on at least one side of the battery body in a direction perpendicular to the side. The one or more first steps 3 surround at least one side of the battery body, and at least one surface of the first step 3 is connected to a first boundary edge. This at least one surface may include: a surface of the first step 3 away from the bottom wall 32 near the first step; and one or more of the aforementioned recesses 1 are provided on the bottom wall 32 of the first step and near the side wall 31 of the first step. The first boundary edge is the boundary edge between at least one of the multiple sides and the first surface. This first surface is either a front or a back surface. The solar cell is a bifacial solar cell or a back-contact solar cell. For example, in the case of a bifacial solar cell, the first surface can be the front surface. In the case of a back-contact solar cell, the first surface can be the back surface. The first boundary edge is a shared edge line or outline line between the side surface and the first surface. Near the first surface on the side, the first step 3 and the aforementioned recess 1 located on the bottom wall 32 of the first step 3 and near the side wall 31 of the first step further enhance the isolation effect between the first and second surfaces. Furthermore, the combination of the first step 3 and the recess 1 near the first surface on the side further enhances the isolation effect during film cleaning of the first and second surfaces, achieving good isolation between the first and second surfaces in the cell body along its thickness direction E. Therefore, the fabrication processes of the film layer on the first surface and the film layer on the second surface of the cell body do not interfere with each other, improving the quality of the film layers on the first and second surfaces and further enhancing the performance of the solar cell. In addition, the height difference at the first step provides more refractive surfaces on the side, allowing incident light or reflected / refracted light from inside the solar cell to undergo more refractions or reflections on the side, increasing the absorption and utilization rate of light by the solar cell, thereby further improving the photoelectric conversion efficiency of the cell.

[0090] The first step 3 surrounds at least one side of the battery body. The first step 3 is uneven, but the specific degree of unevenness is not limited. Figure 1The dashed ellipse with an arrow indicates the direction F surrounding the battery body. This surrounding includes, but is not limited to, the following situations: first, a single first step 3 surrounds the battery body or at least one side; second, multiple first steps 3 form a first step ring surrounding the battery body or at least one side. Whether a single first step 3 surrounds the battery body or at least one side, or multiple first steps 3 surround the battery body or at least one side, the number of first step rings can be greater than or equal to 1. When a single first step 3 forms a first step ring surrounding the battery body or at least one side, the first step ring can be continuous or continuous. When multiple first steps 3 form a first step ring surrounding the battery body or at least one side: if adjacent first steps 3 are continuous along the direction surrounding the battery body or at least one side, the first step ring is continuous; if adjacent first steps 3 have at least one gap along the direction surrounding the battery body or at least one side, the first step ring is discontinuous or intermittent. All of the above situations are within the scope of protection of this application.

[0091] In some possible embodiments, adjacent first steps 3 are arranged continuously or spaced apart in the direction surrounding the battery body or at least one side. For example, Figure 2 In this configuration, adjacent first steps 3 are spaced apart. Continuous arrangement of adjacent first steps 3 means that at least two adjacent first steps 3 are connected as a single unit in the direction surrounding the cell body or at least one side. Spaced arrangement means that at least two adjacent first steps 3 are spaced apart in the direction surrounding the cell body or at least one side. For example, most of the first steps 3 are spaced apart, while some adjacent first steps 3 are continuously connected as a single unit. Compared to the case of spaced arrangement of adjacent first steps 3, since there is no gap between continuously arranged adjacent first steps 3, the isolation effect on the first and second surfaces is better, further improving the film quality on the first and second surfaces, and thus further enhancing the performance of the solar cell. The processing window for the first steps 3 is larger when adjacent first steps 3 are spaced apart. For continuously arranged first steps 3, the degree of connectivity between adjacent first steps 3 is not limited.

[0092] In some possible embodiments, refer to Figure 1At least one side of the battery body is provided with one or more first steps 3 and one or more second steps 18 in a direction perpendicular to the side. The one or more first steps 3 surround at least one side of the battery body, and the one or more second steps 18 surround at least one side of the battery body. At least one surface of the first step 3 is connected to a first boundary edge. This at least one surface may include: a surface of the first step 3 away from the bottom wall 32; one or more of the aforementioned recesses 1 are provided on the bottom wall 32 of the first step near the side wall 31. The first boundary edge is the boundary edge between at least one of the multiple sides and the first surface. At least one surface of the second step 18 is connected to a second boundary edge. This at least one surface may include: a surface of the second step 18 away from the bottom wall 182 of the second step; one or more of the aforementioned recesses 1 are provided on the bottom wall 182 of the second step near the side wall 181 of the second step. The second boundary edge is the boundary edge between at least one of the multiple sides and the second surface. The first surface is one of a front side and a back side, and the second surface is the other. The first surface may be a front side or a back side. This solar cell can be a bifacial solar cell. For example, in the case of a bifacial solar cell, the first side can be the front side and the second side can be the back side. The second boundary edge here is the edge or outline shared by the side and the second side. Near the first side on the side, the first step 3 and the aforementioned recess 1 located on the bottom wall 32 of the first step 3 and near the side wall 31 of the first step, and near the second side on the side, the second step 18 and the aforementioned recess 1 located on the bottom wall 182 of the second step 18 and near the side wall 181 of the second step 18, further enhance the isolation effect between the first and second sides. Furthermore, the cooperation between the first step 3 and the recess 1 near the first side on the side, and the cooperation between the second step 18 and the recess 1 near the second side on the side, can further enhance the isolation effect for cleaning the film layers of the first and second sides, achieving good isolation between the first and second sides in the cell body along its thickness direction E. The recess near the side wall of the first step can be used to protect the film layer at the edge of the first side from corrosion. The recess near the side wall of the second step can be used to protect the film layer at the edge of the second side from corrosion. Therefore, by setting two stepped structures and two recesses, the quality of the film layer on the first and second sides can be improved simultaneously, further enhancing the performance of the solar cell.

[0093] In addition, the height difference at the first step and the height difference at the second step provide more refractive surfaces on the side, allowing incident light or reflected / refracted light from inside the solar cell to be refracted or reflected more times on the side, increasing the absorption and utilization rate of light by the solar cell, thereby further improving the photoelectric conversion efficiency of the cell.

[0094] In some possible embodiments, along the thickness direction E of the battery body, the bottom wall 32 of the first step 3 and the bottom wall 182 of the second step 18 are located on the same plane, or in other words, the bottom wall 31 of the first step 3 and the bottom wall 182 of the second step 18 are in the same side area. The pit depth D1 of the bottom wall 32 of the first step 3 is greater than the pit depth D3 of the bottom wall of the second step. By using the difference in the depth of the two pits, different surface film layers can be protected respectively. This can improve the quality of the film layers on the first and second surfaces without causing too much damage to the side surfaces, further improving the performance of the solar cell. The specific difference between D1 and D3 is not limited here.

[0095] It should be noted that the intervals or continuity, width, height, etc. of the second step 18 are similar or the same as those of the first step 3, and can achieve similar effects. To avoid repetition, they will not be described again.

[0096] In some possible embodiments, refer to Figure 2 The first step 3 and the pit 1 are arranged at intervals and intersected. In this way, the corrosive liquid in the area not blocked by the pit 1 is blocked by the first step 3, thereby avoiding corrosion of the process surface (e.g., the first surface) by the corrosive liquid during the chain cleaning process.

[0097] It should be noted that some of the first steps 3 and some of the pits 1 can be arranged in an overlapping manner, and the correspondence between other first steps 3 and pits 1 is not limited. For example, some of the first steps 3 can be set inside the pits 1, so that the corrosive liquid that is not blocked by the pits 1 can be blocked again by the first steps 3, thereby further avoiding the corrosion of the process surface (e.g., the first surface) by the corrosive liquid during the chain cleaning process.

[0098] In some possible embodiments, along the thickness direction E of the battery body, the width H2 of the first step 3 is from 0.1 μm to 20 μm. A larger width H2 provides better isolation between the first and second surfaces. However, if the width H2 is too large, the presence of the first step 3 can make it difficult to move or transport the battery body or battery, and the first step 3 is also prone to impacts, leading to breakage or microcracks. Therefore, a width H2 of 0.1 μm to 20 μm not only provides good isolation between the first and second surfaces but also has minimal impact on the movement or transport of the battery, and the first step is less prone to breakage or microcracks. Further, the width H2 of the first step 3 can be 0.1 μm-5 μm, further still 0.1 μm-3 μm, and even further still 0.5 μm-3 μm.

[0099] For example, the width H2 of the first step 3 can be 0.1μm, 0.2μm, 0.3μm, 0.45μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.55μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, 5μm, 8μm, 10μm, 12μm, 15μm, 18μm, or 20μm.

[0100] In some embodiments, the height D2 of the first step 3 in the direction perpendicular to the side is 0.1 μm to 10 μm. A larger height D2 provides better isolation between the first and second surfaces. However, if the height D2 is too large, the presence of the first step 3 can make it difficult to move or transport the battery body or battery, and the first step 3 is also more susceptible to impacts, leading to breakage or microcracks. Therefore, a height D2 of 0.1 μm to 10 μm not only provides good isolation between the first and second surfaces but also has minimal impact on the movement or transport of the battery, and the first step is less prone to breakage or microcracks. Further, the height D2 of the first step 3 can be 0.1 μm to 2 μm, and even further, it can be 0.1 μm to 1 μm.

[0101] For example, the height D2 of the first step 3 can be 0.1μm, 0.2μm, 0.3μm, 0.45μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 3μm, 5μm, 8μm, or 10μm.

[0102] In some possible embodiments, along the thickness direction E of the battery body, the side surface includes a first edge region near the first surface, which can be a front or back surface. The size of the first edge region is not limited. The aforementioned pit 1 and first step 3 are located in this first edge region, meaning that the pit 1, or the pit 1 and the first step 3, are mainly distributed in the first edge region of the side surface. In other words, the pit 1 and the first step 3 are located in the edge region near the first surface, which can be used to protect the film layer of the first surface during the chain cleaning process. Furthermore, the pit, or the pit and the first step, can be prepared together during the preparation of the morphology or film layer of the first and second surfaces, simplifying the process.

[0103] In some possible embodiments, the recess 1 is located near the edge of the first surface. Specifically, the recess 1 can be located at a distance from the boundary edge along the thickness direction of the battery body that is less than or equal to 1 / 3 of the thickness of the battery body. The boundary edge is the boundary between the first surface and the side surface.

[0104] It is understood that the distance of pit 1 from the boundary edge can be calculated from the position closest to the boundary edge, or it can be the average distance of multiple pits 1 from the boundary edge. This application does not limit this.

[0105] For example, when the first side is the front side, that is, one or more pits 1 are located in the first edge region of the front side of the battery body on multiple sides; or, one or more pits 1 and one or more first steps 3 are both located in the first edge region of the front side of the battery body on multiple sides, and in the first edge region, the first steps 3 are closer to the front side of the battery body than the pits. The solar cell can be a bifacial solar cell with electrodes on both sides (such as a TOPcon passivated contact cell).

[0106] For example, when the first side is the back side, one or more pits 1 are located in the first edge region of the back side of the battery body near multiple sides; or, one or more pits 1 and one or more first steps 3 are both located in the first edge region of the back side of the battery body near multiple sides, and in the first edge region, the first steps 3 are closer to the back side of the battery body than the pits. This solar cell can be a bifacial solar cell with electrodes on both sides, or a back-contact solar cell with electrodes only on the back side.

[0107] It should be noted that the presence or absence of a pit, or a first step, in the area outside the first edge region of the side is not limited. If a pit exists in the area outside the first edge region of the side, the area proportion of the pit in the first edge region is greater than the area proportion of the pit in the area outside the first edge region of the side. If a first step exists in the area outside the first edge region of the side, the area proportion of the first step in the first edge region is greater than the area proportion of the first step in the area outside the first edge region of the side. In this application, the area proportion can be determined by illuminating the pit and the first step with light perpendicular to the side. The ratio of the sum of the areas of the projections of the first step and the pit onto the side within the first edge region to the area of ​​the projection of the first edge region is the area proportion of the first step and the area proportion of the pit in the first edge region. The method for determining the area proportion of the pit and the first step in the area outside the first edge region of the side is similar and will not be repeated here.

[0108] In some possible embodiments, one or more pits 1 are located in the first edge region of multiple sides near the first surface, and one or more pits are located in the second edge region of multiple sides near the second surface. That is, along the thickness direction E of the battery body, the sides include: a first edge region near the first surface and a second edge region near the second surface, wherein the first surface is the front or back surface, and the second surface is the back or front surface. The relative sizes of the first edge region and the second edge region are not limited. The aforementioned pits 1 are located in the first edge region and the second edge region, that is, pits 1, or pits 1 and the first step 3 are mainly distributed in the first edge region of the side, and pits 1, or pits 1 and the second step 18 are mainly distributed in the second edge region of the side. The pits, or pits and the first step, or pits, pits and the second step can be prepared together during the preparation of the morphology or film layer of the first and second surfaces, which simplifies the process. That is, one or more pits 1 are located in the first edge region of the front side of the battery body and the second edge region of the back side of the battery body; or, one or more pits 1 and one or more first steps 3 are both located in the first edge region of the front side of the battery body and the second edge region of the back side of the battery body, and one or more pits 1 and one or more second steps 18 are both located in the second edge region of the back side of the battery body, and in the first edge region, the first step 3 is closer to the edge of the side than the pit, and in the second edge region, the second step 18 is closer to the edge of the side than the pit. The solar cell can be a bifacial solar cell with electrodes on both sides.

[0109] It should be noted that, for bifacial solar cells: the recess 1 and the first step 3 can be located on the side edge region near the front of the cell body; or, the recess 1 and the first step 3 can be located on the side edge region near the back of the cell body. Alternatively, the recess 1 and the first step 3 can be located on the side edge region near the front of the cell body, while the recess 1 and the second step 18 can be located on the side edge region near the back of the cell body. In other words, in bifacial solar cells: the recess 1 and the first step 3 can be mainly located on the side edge region near the front, with the first step 3 closer to the front than the recess; or the recess 1 and the first step 3 can be mainly located on the side edge region near the back, with the first step 3 closer to the back than the recess. For back-contact solar cells: the recess 1 and the first step 3 can be located on the side edge region near the back of the cell body; in other words, in back-contact solar cells: the recess 1 and the first step 3 can be mainly located on the side edge region near the back, with the first step 3 closer to the back than the recess.

[0110] In some possible embodiments, the first side is the front side of the battery body, and the second side is the back side of the battery body. The battery body includes a silicon substrate 2, a first doped layer 4, and a second doped layer 5. The first doped layer 4 and the second doped layer 5 have opposite doping types; one is N-type doped and the other is P-type doped. It is not limited which is specifically N-type or P-type doped. For example, the first doped layer 4 is a P-type doped layer and the second doped layer 5 is an N-type doped layer, or vice versa. Along the thickness direction of the battery body, the first doped layer 4 can be close to the first side of the battery body, and the second doped layer 5 can be close to the second side of the battery body. In other words, if the first doped layer 4 is located on the light-facing side of the silicon substrate 2 and the second doped layer 5 is located on the back-facing side of the silicon substrate, then the solar cell is a bifacial solar cell.

[0111] In a bifacial solar cell, the side surface includes a first edge region near the first surface and a second edge region near the second surface. The surface may contain a pit, or a pit and a first step that together constitute a large portion of the area in the second edge region; or a pit, or a pit and a first step that together constitute a large portion of the area in the first edge region near the first surface; or a pit, or a pit and a first step that together constitute a large portion of the area in the second edge region near the first surface, where both the pit and the second step constitute a large portion of the area in the second edge region near the second surface. This provides protection for the film layer on the first surface in the first edge region and for the film layer on the second surface in the second edge region. Furthermore, the pit, first step, and second step on the side surface can also improve the light-trapping effect.

[0112] In bifacial solar cells, the first doped layer 4 is a monolithic structure, or the first doped layer 4 includes several first doped regions, with adjacent first doped regions spaced apart. The pits in the edge regions can be formed in the same process as forming the first doped regions, simplifying the cell manufacturing process. For example, the spacer regions of the first doped layer are formed on the cell using laser and wet processing, while simultaneously forming pits on the edge regions of the sides using laser and wet processing. The second doped layer 5 is a monolithic structure, or the second doped layer 5 includes several second doped regions, with adjacent second doped regions spaced apart. The pits in the edge regions can be formed in the same process as forming the second doped regions, simplifying the cell manufacturing process.

[0113] In some possible embodiments, the first surface has a velvety texture. The velvety texture mentioned in this application can be a regular pyramid structure, an inverted pyramid structure, etc., and is not limited thereto. A velvety texture on the first surface can enhance the light-trapping effect. The second surface can be a polished surface, or in other words, the second surface can be flatter than the first surface, or the second surface can be a velvety texture.

[0114] In a bifacial solar cell, the first side is the front side, and the second side is the back side. The second doped layer includes several second doped regions, which can be located on the back side of the cell body. Adjacent second doped regions are spaced apart, and a first textured structure is provided in the spacer region between adjacent second doped regions. A first textured structure is also provided within the aforementioned pits. This first textured structure is a tower-based structure or a pyramid-like structure. (Refer to...) Figure 3 The surface of the pyramid-shaped structure can be polygonal, and the polygonal plane can be at least one of rhombus, square, trapezoid, approximate rhombus, approximate square, or approximate trapezoid. The pyramid-like structure can be an upright pyramid or an inverted pyramid, etc. That is, the texture structure of the spacer region of the second doped region is the same as the texture structure on the pit. The texture structure on the pit can be formed in the same fabrication process as the texture structure of the spacer region of the second doped region, simplifying the process. Furthermore, the texture structure on the pit can further enhance the light-trapping effect.

[0115] It should be noted that the surface undulation of the area where the base structure is located can be less than that of the area where the pyramid-like structure is located. The base structure here can be a partial or complete base structure; there are no limitations on this. Alternatively, the base structure can be a polished structure, for example, a recessed structure.

[0116] In some possible embodiments, in a back-contact solar cell, the first side is the front side of the cell body, and the second side is the back side of the cell body. The cell body includes a silicon substrate 2, a first doped layer, and a second doped layer. The first doped layer includes a plurality of first doped regions, and the second doped layer includes a plurality of second doped regions. The first and second doped regions are spaced apart and alternately distributed. The first and second doped regions have opposite doping types, one being N-type doped and the other P-type doped. Along the thickness direction of the cell body, both the first and second doped regions are close to the second side of the cell body; in other words, both the first doped layer region and the second doped region are located on the back side of the silicon substrate 2. This solar cell is a back-contact solar cell. The pits in the edge region near the back side of the aforementioned side can be formed in the same process as forming the first and second doped regions, simplifying the cell manufacturing process. The spacing here reduces the probability of short circuits, and the alternation here refers to a distribution of one first doped region followed by one second doped region, and then another first doped region.

[0117] It should be noted that in back-contact solar cells, since there are no electrodes blocking the front of the silicon substrate, the external light is more aesthetically pleasing, and the cells can have higher performance.

[0118] In a back-contact solar cell, a second textured structure is provided in the spacer region between the first doped region and the second doped layer. The aforementioned pits also have a second textured structure, which is a tower-based structure or a pyramid-like structure. (Refer to...) Figure 3 The surface of the pyramid-shaped structure can be polygonal, and the polygonal plane can be at least one of rhombus, square, trapezoid, approximate rhombus, approximate square, or approximate trapezoid. The pyramid-like structure can be an upright pyramid or an inverted pyramid, etc. That is, the texture structure of the spacer region between the first and second doped regions is the same as the texture structure on the pit. The texture structure on the pit can be formed in the same fabrication process as the texture structure of the spacer region between the first and second doped regions, simplifying the process. Furthermore, the texture structure on the pit can further enhance the light-trapping effect.

[0119] The solar cell further includes a first passivation antireflection layer 6 and a first electrode 9 sequentially located on the side of the first doped layer 4 or the first doped region away from the silicon substrate, and a second passivation antireflection layer 8 and a second electrode 10 sequentially located on the side of the second doped layer 5 or the second doped region away from the silicon substrate. The passivation antireflection layer here can be silicon nitride, aluminum oxide, etc. In some possible embodiments, the solar cell may also include a tunneling layer 7 located between the doped layer or the doped region and the silicon substrate. The tunneling layer can be a tunneling oxide layer, etc., and is not specifically limited thereto. For example, both the P-region and the N-region may have tunneling layers between the doped region and the silicon substrate, or only the P-region or only the N-region may have tunneling layers between the doped region and the silicon substrate.

[0120] This application also provides a method for preparing a solar cell, comprising the following steps.

[0121] Step S1, providing a semiconductor; the semiconductor includes: two surfaces opposite each other along its thickness direction, and a plurality of side surfaces connecting the two surfaces.

[0122] Here, there are two surfaces: one is the light-facing surface of the semiconductor, and the other is the back-light-facing surface. Multiple side surfaces connect the light-facing and back-light-facing surfaces of the semiconductor.

[0123] Step S2, a laser irradiates a local area of ​​a plurality of sides of the semiconductor to form one or more recesses that are recessed inward on at least one of the plurality of sides, the one or more recesses surrounding at least one side of the semiconductor.

[0124] In this preparation method, the laser breaks down the irradiated area on the side. During the etching and cleaning process, the broken-down areas are more easily cleaned, while the areas not irradiated by the laser are irradiated more slowly. Therefore, pits are easily formed in and around the laser-irradiated area on the side. Alternatively, the laser can directly form pits by irradiating the side. Here, the laser can surround the side of the semiconductor, so the pits formed also surround the semiconductor. In the subsequent chain cleaning process, the pits can prevent liquid from creeping, thereby reducing the impact on the film layer on the upper surface during the chain cleaning process.

[0125] In some possible embodiments, the aforementioned step S1 may include: providing a silicon substrate 2; sequentially forming a full-surface first doped layer and a full-surface first mask layer 16 on one side of the silicon substrate 2 along the thickness direction E, wherein the first mask layer 16 covers at least a portion of multiple sides, specifically, the first mask layer 16 covers at least the area of ​​the side closest to the first doped layer; the laser step in the aforementioned step S2 may include: patterning the first doped layer and the first mask layer 16 using a laser, forming a plurality of first doped regions in the first doped layer after cleaning, and irradiating local areas of multiple sides of the semiconductor using a laser. The laser step of patterning the first doped layer and the laser step of forming pits on the side are performed in the same step, which can simplify the process and improve production efficiency.

[0126] In some possible embodiments, step S1 may further include: sequentially depositing a full-surface second doped layer and a full-surface third mask layer 17 on the other side of the silicon substrate 2 along the thickness direction E. Here, the third mask layer 17 covers at least a portion of multiple sides; specifically, the third mask layer 17 covers at least the region of the multiple sides closest to the second doped layer. The laser step in step S2 may include: patterning the second doped layer and the third mask layer using a laser; forming several second doped regions on the second doped layer after cleaning; and irradiating local areas of multiple sides of the semiconductor using a laser. The laser step of patterning the second doped layer and the laser step of forming pits on the sides are performed in the same step, which can simplify the process and improve production efficiency.

[0127] It should be noted that the second doped layer and the first doped layer have different doping types; one is an N-type doped layer and the other is a P-type doped layer.

[0128] In some possible embodiments, refer to Figure 4 Taking the first surface as the process surface as an example, the cleaning step in step S2 includes: along the thickness direction of the semiconductor, a second mask layer 12 is formed outside the first mask layer 16 on the first surface of the semiconductor 11, wherein the silicon substrate 2 is more hydrophobic than the first mask layer 16; refer to Figure 4 and Figure 5Under the protection of the second mask layer 12, a chain-type equipment is used to etch and clean multiple sides of the semiconductor 11. During the cleaning process, the second mask layer 12 is located outside the etching solution 13 of the chain-type equipment. Of the two sides of the semiconductor 11, the second side is located in the etching solution 13 within the chain-type equipment. The etching solution can clean the sides of the semiconductor 11 and the second side. During the cleaning process, the laser-irradiated areas on the sides are easily cleaned due to laser dispersion, forming pits that expose the more hydrophobic side of the silicon substrate 2. When the etching solution 13 in the chain-type equipment climbs to the exposed side of the silicon substrate 2, since the silicon substrate 2 is more hydrophobic than the first mask layer 16, the exposed side of the silicon substrate 2 can prevent the etching solution 13 in the chain-type equipment from continuing to move towards the location where the second mask layer 12 is set. Therefore, the etching solution 13 in the chain-type equipment can avoid damage to the second mask layer 12. The second mask layer 12 can be fully utilized. The first mask layer 16 and the first doped layer are protected by the second mask layer 12, preventing the first mask layer 16 from thinning or undergoing local perforation. Consequently, during the subsequent formation of the second doped layer, the first mask layer 16 can effectively prevent the second doped layer from contacting the first doped layer and forming co-doping. Because this application prevents co-doping, the leakage risk of the solar cell is very small. Furthermore, since the second mask layer 12 can effectively protect the first mask layer 16 and the first doped layer, preventing the first mask layer from thinning or undergoing local perforation, the film quality of the first doped layer below the second mask layer 12 is better. In addition, after the first mask layer is thinned or partially perforated, during the electrode metallization process, metal elements can enter the silicon substrate through the thinned or perforated locations, forming severe metal recombination. In this application, during the etching and cleaning process, the first mask layer 16 remains essentially unchanged, without thinning or perforation, and metal elements will not enter the silicon substrate through the thinned or perforated locations. Therefore, this application reduces metal recombination.

[0129] The first mask layer 16 has a thickness of 50 nm to 100 nm, and the conveying speed of the chain device for the semiconductor 11 is 1 m / min to 3.5 m / min, which is along the forward direction M of the semiconductor 11. When the semiconductor 11 is stationary on the conveyor belt 14 of the chain device, the height of the etching solution 13 covering the semiconductor 11 inside the chain device is less than or equal to 2 / 3 of the thickness of the semiconductor 11.

[0130] Specifically, the greater the thickness of the first mask layer 16, the better the protection of the underlying first doped layer 4. However, the thickness of the first mask layer 16 located on the side may also be greater, making it more difficult to remove. Therefore, the thickness of the first mask layer 16 is 50nm to 100nm, which not only fully protects the first doped layer and prevents co-doping, but also makes the first mask layer 16 on the side easier to remove. For example, the thickness of the first mask layer 16 can be 50nm, 55nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm, or 100nm.

[0131] The transmission speed of the chain equipment to the semiconductor 11 and the height of the etchant 13 covering the semiconductor 11 within the chain equipment are both related to the degree of liquid turnover of the etchant 13 within the chain equipment and the cleaning efficiency. The higher the transmission speed of the chain equipment to the semiconductor 11 and the higher the height of the etchant 13 covering the semiconductor 11 within the chain equipment, the greater the degree of liquid turnover of the etchant 13 within the chain equipment, and the easier it is for the etchant 13 within the chain equipment to contact the second mask layer 12, which is more likely to cause co-doping, etc. However, if the transmission speed of the chain equipment to the semiconductor 11 is too low and the height of the etchant 13 covering the semiconductor 11 within the chain equipment is too small, the cleaning speed may be too slow, affecting the cleaning efficiency. Therefore, in this application, by controlling the transmission speed of the chain equipment to the semiconductor 11 and the height of the etchant 13 covering the semiconductor 11 within the chain equipment to be within the corresponding range, not only can the degree of liquid turnover of the etchant 13 within the chain equipment be controlled to avoid co-doping, but the cleaning efficiency is also higher.

[0132] For example, the conveying speed of the chain equipment for semiconductor 11 can be 1 m / min, 1.2 m / min, 1.5 m / min, 1.8 m / min, 2 m / min, 2.2 m / min, 2.5 m / min, 2.9 m / min, 3 m / min, 3.1 m / min, or 3.5 m / min. For example, when semiconductor 11 is stationary on the conveyor belt 14 of the chain equipment, the height of the etching solution 13 covering semiconductor 11 inside the chain equipment can be 2 / 3, 19 / 30, 3 / 5, 1 / 2, 7 / 15, 2 / 5, 1 / 5, 1 / 6, 1 / 7, 1 / 8, 1 / 9, or 1 / 10 of the thickness of semiconductor 11.

[0133] The specific type of etching solution 13 is not limited; for example, etching solution 13 can be an acidic etching solution. The etching cleaning process ends when semiconductor 11 is removed from the conveyor belt 14 of the chain equipment.

[0134] In some possible embodiments, the second mask layer 12 is a liquid mask, such as a water film, with a capacity of 20 ml to 60 ml. If the capacity of the second mask layer 12 is too small, the protection of the underlying first mask layer 16 and the first doped layer will be inadequate. If the capacity of the second mask layer 12 is too large, the setup of the second mask layer 12 will be more difficult. Therefore, a capacity of 20 ml to 60 ml for the second mask layer 12 not only provides sufficient protection for the underlying first mask layer 16 and the first doped layer with a low co-doping probability, but also makes the second mask layer 12 easier to set up. Further, the capacity of the second mask layer 12 can be 30 ml to 50 ml. For example, the capacity of the second mask layer 12 can be 20 ml, 25 ml, 30 ml, 33 ml, 35 ml, 40 ml, 45 ml, 47 ml, 50 ml, 55 ml, 54 ml, or 60 ml.

[0135] It should be noted that the capacity range of 20m³ to 60ml for the second mask layer 12 refers to the entire solar cell. For example, the long side dimension of the entire solar cell is 180mm-220mm.

[0136] In some possible embodiments, the height of the etchant 13 covering the semiconductor 11 within the chain device is from 30 μm to 100 μm. The greater the height of the etchant 13 covering the semiconductor 11 within the chain device, the greater the degree of liquid turnover of the etchant 13 within the chain device, making it easier for the etchant 13 to contact the second mask layer 12 and more likely to cause co-doping, etc. However, if the height of the etchant 13 covering the semiconductor 11 within the chain device is too small, the cleaning speed may be too slow, affecting the cleaning efficiency. Therefore, in this application, the height of the etchant 13 covering the semiconductor 11 within the corresponding range can not only control the degree of liquid turnover of the etchant 13 within the chain device and avoid co-doping, but also achieve higher cleaning efficiency.

[0137] For example, the height at which the etchant 13 covers the semiconductor in the chain device can be 30μm, 33μm, 35μm, 39μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, or 100μm.

[0138] It should be noted that any of the aforementioned solar cells can be obtained by processing and preparing the aforementioned semiconductors. The relevant content of the preparation method of solar cells can be referred to the relevant content of any of the aforementioned solar cells. In order to avoid repetition, it will not be repeated here.

[0139] This application also provides a photovoltaic module, comprising: a plurality of battery strings connected in series and / or in parallel, each battery string comprising: a plurality of solar cells prepared by any of the aforementioned solar cells or by any of the aforementioned solar cells, and an electrical connector electrically connected to an electrode in the solar cell.

[0140] There is no limitation on whether the photovoltaic module includes other structures. For example, the photovoltaic module may also include encapsulating films located on the surface of the solar cells.

[0141] It should be noted that the manufacturing methods of photovoltaic modules and solar cells mentioned here can refer to any of the aforementioned solar cells. To avoid repetition, the relevant details will not be repeated.

[0142] The following specific examples will further explain this application.

[0143] Example 1

[0144] The first step is to clean and texturize the silicon substrate, forming a textured surface on the front side of the substrate. The length of either the long or short side of the front side of the silicon substrate is approximately 180mm.

[0145] The second step involves forming a P-type doped layer on the front side of the silicon substrate, and then forming borosilicate glass (BSG) on the P-type doped layer. The borosilicate glass serves as the first mask layer for the subsequent formation of the tunneling oxide layer and N-type doped layer on the back side of the silicon substrate. BSG is formed on both the side and back sides of the silicon substrate. The BSG is the first mask layer on the P-type doped layer, and its thickness is approximately 70 nm. This first doped layer is the P-type doped layer.

[0146] The third step is to place a water film on the BSG on the front side of the silicon substrate. The water film is the second mask layer and has a capacity of about 45ml.

[0147] The fourth step involves irradiating the P-type doped layer and BSG with a laser, and also irradiating the side of the silicon substrate with a laser. For example, the area near the front side can be irradiated with a laser to disperse the BSG at the location where the laser is irradiated and in the vicinity.

[0148] In the fifth step, the back side of the silicon substrate is placed on the conveyor belt 14 of the chain equipment. The drive roller 15 rotates, causing the silicon substrate to move along the M direction at a speed of 2.2 m / min. When the silicon substrate is stationary on the conveyor belt 14, the etching solution 13 inside the chain equipment covers the silicon substrate to a height of 2 / 5 of its thickness. Both the conveyor belt 14 and the drive roller 15 are resistant to the etching solution, which can be an acidic etching solution. During the cleaning process, the water film on the front side of the silicon substrate is outside the etching solution 13 inside the chain equipment, while the back side of the silicon substrate is immersed in the etching solution 13. The etching solution can clean both the sides and the back side of the silicon substrate. During the cleaning process, the laser-irradiated area and nearby BSG on the side of the silicon substrate are easily cleaned away due to laser dispersion, forming pits. This exposes the more hydrophobic side of the silicon substrate 2. When the etching solution 13 in the chain-connector climbs to the exposed side of the silicon substrate 2, the more hydrophobic silicon substrate 2 prevents the etching solution 13 from continuing to move towards the water film on the front of the silicon substrate. Therefore, the etching solution 13 in the chain-connector avoids damaging and diluting the water film on the front of the silicon substrate. The water film on the front side effectively protects the underlying BSG and P-type doped layer, preventing BSG thinning or localized perforation. Consequently, during the subsequent formation of the N-type doped layer, the BSG on the front side of the silicon substrate effectively prevents the N-type and P-type doped layers from contacting and forming co-doping. Because this application prevents co-doping, the leakage risk of the solar cell is very low. Furthermore, since the water film on the front side of the silicon substrate effectively protects the underlying BSG and P-type doped layer, preventing BSG thinning or localized perforation, the P-type doped layer beneath the water film on the front side of the silicon substrate has better film quality and passivation effect. On the sides of the silicon substrate, BSG residues that were not reached by the laser may remain. Since the BSG is not thinned or locally perforated during the cleaning process, metal elements will essentially not enter the silicon substrate during subsequent metallization processes, resulting in less metal recombination.

[0149] Step 6: A tunneling layer 7, an N-type polycrystalline silicon layer, and a phosphosilicate glass (PSG) are sequentially formed on the second surface of the silicon substrate. The phosphosilicate glass serves as the first mask layer for subsequent processing of the N-type polycrystalline silicon layer. The aforementioned second doped layer is the N-type polycrystalline silicon layer.

[0150] Step 7: Irradiate the N-type polysilicon layer and PSG with a laser, and irradiate the side of the silicon substrate with a laser. For example, the area near the back side of the side can be irradiated with a laser to break up the PSG at the location where the laser is irradiated on the side and the area near it.

[0151] Step 8: The front side of the silicon substrate is near the conveyor belt 14 of the chain equipment. The PSG, N-type polysilicon layer, and BSG on the sides and front side of the silicon substrate are removed. Because the etchant 13 covers the front side of the silicon substrate more comprehensively, the etching speed is faster in the front side. However, the back side of the side is not covered by the etchant 13 as comprehensively, and the etching speed is slower due to the pit structure blocking the etchant and the water film diluting the etchant. This will form the first step 3.

[0152] An N-type electrode is formed on the N-type polycrystalline silicon region, and a P-type electrode is formed on the P-type doped layer.

[0153] In the solar cell formed in Example 1, along the thickness direction E of the cell body, the side surface of the cell body includes: a first edge region near the front side and a second edge region near the back side, as well as a central region located in the middle of the side surface of the cell body. The pit and the first step are mainly distributed in the first edge region, and the pit and the second step are mainly distributed in the second edge region. Furthermore, in the same side edge region, the step is closer to the edge than the pit. The aforementioned pit is provided on the bottom wall of the first step and near the side wall, and the aforementioned pit is provided on the bottom wall of the second step and near the side wall. The solar cell formed in Example 1 can be referred to... Figure 1 .

[0154] Example 2

[0155] The difference between Example 2 and Example 1 is only in the seventh step. In the seventh step of Example 2, the N-type polycrystalline silicon layer and PSG are irradiated with a laser. In the seventh step of Example 2, the laser does not irradiate the side area near the back. Therefore, in the solar cell formed in Example 2, there are almost no pits in the second edge region. The pits and the first step are mainly distributed in the first edge region. Moreover, in the first edge region, the first step is closer to the edge than the pit.

[0156] Comparative Example

[0157] The main difference between the comparative example and Example 1 lies in steps four and seven. In steps four and seven of the comparative example, the laser does not irradiate the side of the silicon substrate. Therefore, the cleaning results in steps five and eight are also different. As a result, the solar cell formed in the comparative example has no pits on the side.

[0158] Examples 1 and 2 sacrifice some side morphology to achieve no co-doping in the P-type doped layer on the front side of the silicon substrate, reducing the phenomenon of co-doping at the edge of the P-type doped layer, reducing the risk of leakage current, and reducing metal recombination, thus ensuring minimal damage to the P-type doped layer.

[0159] Meanwhile, for the solar cells of Example 2 and the comparative example, under different boron diffusion conditions and the same test conditions, the photoluminescence (PL) values ​​of the solar cells of Example 2 and the comparative example were measured, and the measurement results were referenced. Figure 6 . Figure 6 In the graph, the horizontal axis represents the boron diffusion process parameters in the comparative example and Example 2, and the vertical axis represents the measured photoluminescence (PL) brightness. High and low implantation are both relative to boron diffusion. The high implantation process parameters in the comparative example correspond to the same parameters in Example 2. The low implantation process parameters in the comparative example correspond to the same parameters in Example 2. For the comparative example's solar cell, the measured PL brightness is approximately 31,000 under high implantation and approximately 2,600 under low implantation. For the Example 2's solar cell, the measured PL brightness is approximately 33,000 under high implantation and approximately 2,900 under low implantation. The comparison between Example 2 and the comparative example shows that, regardless of whether it's high or low implantation, the PL brightness of Example 2 is higher than that of the comparative example. Moreover, in Example 2, the improvement with high implantation is smaller, while the improvement with low implantation is more significant, indicating that recombination under low implantation is effectively improved. The reduction in recombination is mainly due to the reduction of co-doping on the front side of the silicon substrate, meaning the front film layer is better protected during the chain process. Therefore, the embodiments of this application can effectively improve the performance of the boron diffusion surface, thereby effectively improving the fill factor (FF) of the battery.

[0160] It should be noted that high and low injection intensity refer to the amount of light injected. High light intensity can be used to indicate surface passivation, while low light intensity can be used to indicate recombination. Furthermore, the higher the PL (light injection intensity) of low light intensity, the less recombination occurs.

[0161] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0162] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A solar cell, characterized in that, include: The battery body includes: a first surface and a second surface opposite to each other along its thickness direction, and a plurality of side surfaces connecting the first surface and the second surface; At least one of the plurality of sides is provided with one or more recesses that are recessed toward the interior of the battery body, the one or more recesses surrounding the at least one side.

2. The solar cell according to claim 1, characterized in that, Adjacent pits are spaced apart or arranged continuously in the direction surrounding the battery body.

3. The solar cell according to claim 1 or 2, characterized in that, The one or more pits are located on the edge of the at least one side near the first surface, which is either the front or the back.

4. The solar cell according to claim 1 or 2, characterized in that, The one or more pits are located on the edge of the at least one side near the first surface, and the one or more pits are located on the edge of the at least one side near the second surface.

5. The solar cell according to any one of claims 1 to 3, characterized in that, The at least one side is further provided with one or more first steps in a direction perpendicular to the side, the one or more first steps surround the at least one side, and at least one surface of the first step is connected to a first boundary edge, the bottom wall of the first step and near the side wall are provided with one or more pits, the first boundary edge is the boundary edge between the side and the first face, the first face is the front or the back.

6. The solar cell according to any one of claims 1 to 4, characterized in that, The at least one side is further provided with one or more first steps and one or more second steps in a direction perpendicular to the side. The one or more first steps surround the at least one side, and at least one surface of the first step is connected to a first boundary edge, which is the boundary edge between the side and the first surface. The one or more second steps surround the at least one side, and at least one surface of the second step is connected to a second boundary edge, which is the boundary edge between the side and the second surface. The bottom wall of the first step and near the side wall are provided with the recess, and the bottom wall of the second step and near the side wall are also provided with the recess.

7. The solar cell according to claim 6, characterized in that, Along the thickness direction of the battery body, the bottom wall of the first step and the bottom wall of the second step are located on the same plane, and the depth of the pit provided on the bottom wall of the first step is greater than the depth of the pit provided on the bottom wall of the second step.

8. The solar cell according to any one of claims 5 to 7, characterized in that, In the direction surrounding the battery body, adjacent first steps are arranged at intervals or continuously.

9. The solar cell according to claim 3 or 4, characterized in that, The at least one side is further provided with one or more first steps in a direction perpendicular to the side, and the pits and the first steps are intersecting when adjacent pits are spaced apart and adjacent first steps are spaced apart.

10. The solar cell according to any one of claims 3 to 9, characterized in that, The first side is the front side, and the second side is the back side; the battery body includes: a silicon substrate, a first doped layer, and a second doped layer; the doping types of the first doped layer and the second doped layer are opposite; The first doped layer is a monolithic structure, or the first doped layer includes a plurality of first doped regions, with adjacent first doped regions spaced apart. The second doped layer is a solid layer structure, or the second doped layer includes a plurality of second doped regions, adjacent second doped regions are spaced apart, and a first texture structure is provided in the spaced area between adjacent second doped regions. The first texture structure is provided in the pit, and the first texture structure is a tower base structure or a pyramid-like structure.

11. The solar cell according to claim 3 or 5, characterized in that, The first side is the back side, and the second side is the front side; the battery body includes: a silicon substrate, a first doped layer and a second doped layer disposed on the first side; the first doped layer and the second doped layer have opposite doping types, the first doped layer includes a plurality of first doped regions, and the second doped layer includes a plurality of second doped regions; the first doped regions and the second doped regions are spaced apart and alternately distributed, and a second texture structure is disposed in the space between the first doped regions and the second doped regions, and the second texture structure is disposed in the pit, the second texture structure being a tower base structure or a pyramid-like structure.

12. The solar cell according to any one of claims 5 to 9, characterized in that, Along the thickness direction, the width of the first step is 0.1 μm to 20 μm; and / or, In the direction perpendicular to the side, the height of the first step is 0.1 μm to 10 μm.

13. The solar cell according to claim 3 or 5, characterized in that, The distance of the indentation from the boundary edge along the thickness direction of the battery body is less than or equal to 1 / 3 of the thickness of the battery body, and the boundary edge is the boundary edge between the plurality of side surfaces and the first surface.

14. The solar cell according to any one of claims 1 to 13, characterized in that, The recess is provided on two of the plurality of sides, and the two sides are arranged opposite to each other; or... The recesses are provided on three of the plurality of sides.

15. The solar cell according to any one of claims 1 to 14, characterized in that, Along the thickness direction, the width of the pit is from 1 μm to 140 μm; and / or, In a direction perpendicular to the side, the depth of the indentation facing inward is 0.2 μm to 10 μm.

16. A method for preparing a solar cell, characterized in that, include: Provide semiconductors; The semiconductor includes: two surfaces opposite each other along its thickness direction, and a plurality of side surfaces connecting the two surfaces; A laser irradiates local areas of multiple sides of the semiconductor to form one or more recesses that are recessed inward on at least one of the multiple sides, the one or more recesses surrounding at least one side of the semiconductor.

17. The method for preparing a solar cell according to claim 16, characterized in that, The cleaning steps include: A second mask layer is disposed outside the first mask layer along the thickness direction of the semiconductor; the silicon substrate is more hydrophobic than the first mask layer; Under the protection of the second mask layer, the plurality of sides are etched and cleaned using a chain equipment; during the cleaning process, the second mask layer is located outside the etching solution inside the chain equipment, and of the two sides of the semiconductor, the side without the second mask layer is located in the etching solution of the chain equipment; Wherein, the thickness of the first mask layer is 50nm to 100nm, and the conveying speed of the chain device to the semiconductor is 1m / min to 3.5m / min; when the semiconductor is placed on the conveyor belt of the chain device, the height of the etching solution covering the semiconductor in the chain device is less than or equal to 2 / 3 of the thickness of the semiconductor.

18. A photovoltaic module, characterized in that, include: Multiple battery strings connected in series and / or in parallel, the battery strings comprising: a solar cell according to any one of claims 1 to 15 or a solar cell prepared by the preparation method according to claim 16 or 17, and an electrical connector electrically connecting at least two of the solar cells.

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