A solar cell, a photovoltaic module and a method for manufacturing a solar cell

Abstract

The application discloses a solar cell, a photovoltaic module and a manufacturing method of the solar cell, and relates to the technical field of solar cells, and aims to improve the appearance of a cutting surface of a split solar cell, thereby improving the cell efficiency. The solar cell comprises a cell body with a first surface, a second surface and a side surface, and the side surface comprises a cutting surface. In a first direction, the cutting surface comprises a pre-cut region and a thermal cracking region located between two adjacent pre-cut regions. In the first direction, the cell body comprises opposite first and second ends, the pre-cut region comprises a first pre-cut region close to the first end of the cell body, a second pre-cut region close to the second end of the cell body, and at least one third pre-cut region located between the first and second pre-cut regions. In a second direction, the thickness of the pre-cut region is greater than that of the thermal cracking region.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and more particularly to a solar cell, a photovoltaic module, and a method for manufacturing a solar cell. Background Technology

[0002] A solar cell is a device that utilizes solar energy, directly converting light energy into electrical energy through the photoelectric effect or photochemical effect. Solar cells include slab solar cells. Currently, the production of slab solar cells typically involves cutting a solar cell that has already formed multiple film layers into at least two slabs, such as two half-cells. These slab solar cells are then used to manufacture photovoltaic modules.

[0003] In actual cutting, a guide groove is typically created on the surface of the original solar cell using a first laser process, with the guide grooves along a first direction. Then, a second laser process is used to heat-treat the surface along the first direction to form a heat treatment path located between the two guide grooves. Next, rapid cooling along the heat treatment path causes the original solar cell to crack along the path, resulting in segmented solar cells. However, due to the large length or width of the original solar cell, the guiding effect of the guide grooves gradually weakens with increasing distance from them, leading to a deterioration in the morphology of the middle region of the cut surface of the segmented solar cell.

[0004] Therefore, how to improve the morphology of the cut surfaces of slab solar cells to improve cell efficiency remains a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] The purpose of this application is to provide a solar cell, a photovoltaic module, and a method for manufacturing a solar cell, which improves the morphology of the cut surfaces of a sectional solar cell to improve cell efficiency.

[0006] To achieve the above objectives, in a first aspect, this application provides a solar cell. The solar cell includes a cell body, which includes opposing first and second surfaces, and a side surface connecting the first and second surfaces. The side surface includes a cut surface. Along a first direction, the cut surface includes a pre-cut region and a thermally cracked region, the thermally cracked region being located between two adjacent pre-cut regions. Along the first direction, the cell body includes opposing first and second ends, and the pre-cut region includes a first pre-cut region near the first end of the cell body, a second pre-cut region near the second end of the cell body, and at least one third pre-cut region located between the first and second pre-cut regions. Along a second direction, the thickness of the pre-cut region is greater than the thickness of the thermally cracked region. The first and second directions are parallel to the cut surface, and the third direction is perpendicular to the cut surface. The second direction is the thickness direction of the cell body, and the first direction is perpendicular to the second direction.

[0007] In actual solar cell manufacturing, the side surface of a solar cell typically includes an uncut "non-cut surface" and a cut surface formed after cutting. The non-cut surface generally does not have attached silicon slag or silicon oxide, and even if it does, the amount is negligible. Therefore, this discussion focuses on the silicon slag and silicon oxide on the cut surface. A significant source of this silicon slag and silicon oxide is the destructive laser used during cell cutting to irradiate the silicon substrate of the solar cell. The silicon substrate absorbs the laser energy, melts, and oxidizes to form the slag and silicon oxide. The portion of the silicon slag and silicon oxide that remains after processing is the molten silicon region described in this application.

[0008] In the solar cell provided in this application, the cut surface includes a pre-cut area and a thermally cracked area. The pre-cut area is a guide groove area opened by laser (i.e., a laser-destructive cutting area). The pre-cut area includes at least three pre-cut areas located at different positions, and the thermally cracked area is located between two adjacent pre-cut areas. In this case, the guiding effect of the pre-cut area will not be weakened due to the large length or width of the original solar cell, thus ensuring the morphology of the cut surface of the obtained sectional solar cell, thereby improving the cell efficiency. Furthermore, along the second direction, the thickness of the pre-cut area is greater than the thickness of the thermally cracked area. In this case, the guiding effect of the pre-cut area can be ensured to be greater, reducing or avoiding the pulling force of the guiding force and the thermal force, so as to avoid unevenness of the cut surface due to pulling.

[0009] In one implementation, the lengths of the first pre-cut region, the second pre-cut region, and the third pre-cut region are all in the range of 0.5mm-5mm; and / or, the ratio of the lengths of the first pre-cut region, the second pre-cut region, and the third pre-cut region to the length of the battery body in the first direction is 0.5% to 5%; and / or, the spacing between two adjacent pre-cut regions is 10mm-100mm; the length direction of the pre-cut region and the length direction of the thermal cracking region are consistent with the first direction.

[0010] By adopting the above technical solution, the morphology of the cut surface of the obtained sectional solar cells can be ensured while ensuring the guiding role of the pre-cut area and smoothly cutting the battery body, thereby improving the battery efficiency.

[0011] In one implementation, the number of third pre-cut regions is 1-10. The more third pre-cut regions there are, the stronger their guiding effect, thereby improving the morphology of the cut surface of the sectional solar cell. Furthermore, in this application, the third pre-cut regions are dispersed on the cut surface. Compared to a case where the total area or number of third pre-cut regions is the same, but the third pre-cut regions are concentrated, this application reduces the damage to the cut surface caused by concentrated distribution, further improving the morphology of the cut surface of the sectional solar cell, and thus further improving the cell efficiency.

[0012] In one implementation, along the second direction, the thickness of the pre-cut region ranges from 30 μm to 140 μm; and / or, the ratio of the thickness of the pre-cut region to the thickness of the battery body is 0.2 to 0.8; and / or, the thickness of the thermally cracked region ranges from 2 μm to 20 μm; and / or, the ratio of the thickness of the thermally cracked region to the thickness of the battery body is 0.01 to 0.15; and / or, the ratio of the thickness of the thermally cracked region to the thickness of the pre-cut region is 0.05 to 0.5.

[0013] By adopting the above technical solution, it can be ensured that the guiding effect of the pre-cut area is greater, and the pulling force of the guiding force and the intense force can be reduced or avoided, so as to avoid unevenness of the cut surface due to pulling.

[0014] In one implementation, along a first direction, the length of the pre-cut region is less than the length of the thermal cracking region; and / or, the length of the first pre-cut region is greater than the length of the third pre-cut region; and / or, along the first direction, the length of the third pre-cut region is greater than or equal to the length of the second pre-cut region. Wherein, the length directions of the first pre-cut region, the second pre-cut region, the third pre-cut region, and the thermal cracking region are consistent with the first direction.

[0015] With the above technical solution, as described above, the pre-cut area is the guiding groove area opened by the laser (i.e., the laser-damaged cutting area). When the length of the pre-cut area is less than the length of the thermal cracking area, the proportion of the laser-damaged cutting area can be reduced, thereby reducing the damaged area of ​​the cut surface. When the first pre-cut area is the first cutting area in the process of cutting the entire solar cell, since the length of the first pre-cut area is greater than the length of the third pre-cut area, the guiding effect of the first pre-cut area is greater, which can ensure that the extension path and morphology of the subsequent thermal cracking area meet the actual requirements. When the second pre-cut area is the last cutting area in the process of cutting the entire solar cell, since the length of the third pre-cut area is greater than or equal to the length of the second pre-cut area, not only can the guiding effect of the third pre-cut area on the thermal cracking area be ensured, but the damage of the second pre-cut area to the solar cell can also be reduced, thereby improving the cell efficiency.

[0016] In one implementation, both the first pre-cut region and the second pre-cut region include molten silicon regions, wherein the area ratio of the molten silicon region in the first pre-cut region is greater than the area ratio of the molten silicon region in the second pre-cut region.

[0017] At this point, compared to the fact that the area ratio of the molten silicon region in the second pre-cutting region is greater than or equal to the area ratio of the molten silicon region in the first pre-cutting region, this application controls the area ratio of the molten silicon region on the cutting surface so that the relative area of ​​the molten silicon region is within a reasonable range, thereby reducing the impact of the molten silicon region on the passivation characteristics and light absorption characteristics of the laser-damaged region and improving the photoelectric conversion efficiency of the solar cell.

[0018] In one implementation, the third pre-cut region includes a molten silicon region, and the area ratio of the molten silicon region in the first pre-cut region is greater than the area ratio of the molten silicon region in the third pre-cut region.

[0019] With the above technical solution, compared to the case where the area ratio of the molten silicon region in the third pre-cutting region is greater than or equal to the area ratio of the molten silicon region in the first pre-cutting region, this application further controls the area ratio of the molten silicon region on the cutting surface, so that the relative area of ​​the molten silicon region is within a reasonable range, further reducing the influence of the molten silicon region on the passivation characteristics and light absorption characteristics of the laser-damaged region, and further improving the photoelectric conversion efficiency of the solar cell.

[0020] In one implementation, the cutting surface includes a groove structure. The groove structure located in the first pre-cutting region has a first depth, the groove structure located in the second pre-cutting region has a second depth, the groove structure located in the third pre-cutting region has a third depth, and the groove structure located in the thermal cracking region has a fourth depth. Wherein, the first depth is greater than the second depth; and / or, the first depth is greater than the third depth; and / or, the first depth is greater than the fourth depth; and / or, the second depth is greater than the fourth depth; and / or, the third depth is greater than the fourth depth.

[0021] When the above technical solution is adopted, the trench structure located in the hot crack region has the shallowest depth. At this time, the surface roughness of the hot crack region is small, which provides a good foundation for the formation of the subsequent passivation layer. This results in a better quality of the passivation layer formed on the hot crack region, improving the passivation effect and thus ensuring the efficiency of the solar cell.

[0022] In one implementation, along the direction from the first end to the second end, the first pre-cut region sequentially includes a first sub-region, a second sub-region, and a third sub-region, wherein the first sub-region includes multiple first molten silicon regions. The cutting surface includes a first trench structure and a second trench structure, wherein the first trench structure is located in the third sub-region, and the second trench structure is located in the thermal cracking region. Along the third direction, the depth of the second trench structure is less than the depth of the first trench structure.

[0023] With the above technical solution, the depth of the second trench structure is less than the depth of the first trench structure along a third direction. In this case, the surface roughness of the thermally cracked region with the second trench structure is smaller, providing a good foundation for the formation of the subsequent passivation layer. This results in a better quality passivation layer formed on the thermally cracked region, improving the passivation effect and thus ensuring the efficiency of the solar cell.

[0024] In one implementation, the cut surface further includes a third trench structure located in the second sub-region. The second sub-region includes multiple second molten silicon regions distributed between the edge near the first surface and the third trench structure.

[0025] With the above technical solution, compared to the second sub-region being entirely composed of the second molten silicon region, the second sub-region of this application is only partially composed of the second molten silicon region. This reduces the impact of the molten silicon region on the passivation characteristics and light absorption characteristics of the laser-damaged region, thereby improving the photoelectric conversion efficiency of the solar cell.

[0026] In one implementation, along the second direction, the cut surface with the third trench structure sequentially includes a first region, a second region, and a third region, with the first region located between the second region and the second molten silicon region. Along the third direction, the depth of the third trench structure located in the first region and the depth of the third trench structure located in the third region are both greater than or equal to the depth of the third trench structure located in the second region.

[0027] With the above technical solution, the surface roughness of the first and third regions is greater than that of the second region, and the surface roughness of the passivation layer subsequently formed in the second region is less than that of the passivation layers subsequently formed in the first and third regions. This not only minimizes the escape of sunlight but also ensures the passivation effect. Simultaneously, by reducing the surface roughness of the passivation layer, the solar cell can reduce light scattering and reflection, improving the effective utilization of light. Furthermore, low surface roughness reduces surface defects and traps, decreasing carrier recombination and thus improving the electrical performance of the solar cell.

[0028] In one implementation, the cutting surface further includes a third groove structure located in the second sub-region. Along the third direction, the depth of the third groove structure is less than the depth of the first groove structure.

[0029] At this point, the surface roughness of the second sub-region with the third trench structure is less than that of the third sub-region with the first trench structure, and the surface roughness of the passivation layer subsequently formed in the second sub-region is less than that of the passivation layer subsequently formed in the third sub-region. Based on this, not only can the escape of sunlight be minimized, but the passivation effect can also be guaranteed. Simultaneously, by reducing the surface roughness of the passivation layer, the solar cell can reduce light scattering and reflection, improving the effective utilization of light. Furthermore, low surface roughness can reduce surface defects and traps, reduce carrier recombination, thereby improving the electrical performance of the solar cell.

[0030] In one implementation, the depth of the third trench structure is greater than the depth of the second trench structure.

[0031] At this point, the surface roughness of the thermally cracked region with the second trench structure is less than that of the second sub-region with the third trench structure, and the surface roughness of the passivation layer subsequently formed in the thermally cracked region is also less than that of the passivation layer subsequently formed in the second sub-region. This not only minimizes the escape of sunlight but also ensures the passivation effect. Simultaneously, by reducing the surface roughness of the passivation layer, the solar cell can reduce light scattering and reflection, improving the effective utilization of light. Furthermore, low surface roughness reduces surface defects and traps, decreasing carrier recombination and thus improving the electrical performance of the solar cell.

[0032] In one implementation, the slope of the third trench structure is less than that of the second trench structure. In this case, the inclination of the third trench structure relative to the second direction is greater than that of the second trench structure. This not only avoids creating more stress concentration points in the thermally cracked region with the second trench structure, reducing the probability of cracks appearing in the solar cell during subsequent processing (e.g., texturing, coating) and use, but also, compared to the third trench structure, the second trench structure better conforms to the internal stress distribution of the material, reducing the impact of surface defects caused by trench inclination on the overall performance of the solar cell. Furthermore, compared to the second sub-region with the third trench structure, the thermally cracked region with the second trench structure is more regular, allowing for more uniform application of the chemical solution to the thermally cracked region during subsequent cleaning, texturing, and other processes, improving the treatment effect. Additionally, the roughness of the thermally cracked region with the second trench structure can be less than that of the second sub-region with the third trench structure, which can improve the quality of the film layer formed in the thermally cracked region later, thereby improving cell efficiency.

[0033] In one implementation, the acute angle formed by the tangent line of the point in the first trench structure closest to the first surface and the first surface is α, and the acute angle formed by the tangent line of the intersection point of the second trench structure and the first surface and the first surface is β, where α < β.

[0034] With the above technical solution, since α < β, the tilt of the second trench structure relative to the second direction is less than that of the first trench structure relative to the second direction. This not only avoids more stress concentration points in the thermally cracked region with the second trench structure, reducing the probability of cracks appearing in the solar cell during subsequent processing (e.g., texturing, coating) and use, but also, compared to the first trench structure, the second trench structure better conforms to the internal stress distribution of the material, reducing the impact of surface defects caused by trench tilt on the overall performance of the solar cell. Furthermore, compared to the third sub-region with the first trench structure, the thermally cracked region with the second trench structure is more regular, allowing for more uniform application of the chemical solution to the thermally cracked region during subsequent cleaning, texturing, and other processes, improving the treatment effect. Additionally, the roughness of the thermally cracked region with the second trench structure can be less than that of the third sub-region with the first trench structure, which improves the quality of the film layer formed in the thermally cracked region later, thereby increasing the cell efficiency.

[0035] In one implementation, the acute angle formed by the tangent line of the point near the first surface in the first trench structure and the first surface is α, and the acute angle formed by the tangent line of the point near the first surface in the third trench structure and the first surface is γ, where α < γ.

[0036] At this point, the tilt of the third trench structure relative to the second direction is less than that of the first trench structure relative to the second direction. Based on this, not only can more stress concentration points be avoided in the second sub-region with the third trench structure, reducing the probability of cracks appearing in the solar cell during subsequent processing (e.g., texturing, coating) and use, but also, compared to the first trench structure, the third trench structure better conforms to the internal stress distribution law of the material, reducing the impact of surface defects caused by trench tilt on the overall performance of the solar cell. Furthermore, compared to the third sub-region with the first trench structure, the second sub-region with the third trench structure is more regular, allowing the chemical solution to act evenly on the second sub-region during subsequent cleaning, texturing, and other processes, improving the processing effect. Additionally, the roughness of the second sub-region with the third trench structure can be less than that of the third sub-region with the first trench structure, which can improve the quality of the film layer formed in the second sub-region later, thereby improving the cell efficiency.

[0037] In one implementation, along a first direction: the length of the first sub-region is 0.02% to 0.2% of the length of the battery body, the length of the second sub-region is 0.1% to 0.5% of the length of the battery body, and the length of the third sub-region is 0.2% to 1% of the length of the battery body.

[0038] By adopting the above technical solution, the ratio of the length of the three sub-regions to the length of the battery body is controlled within the aforementioned range. This not only enables the cutting of the battery body but also controls the losses after cutting, ensuring the quality of the passivation layer subsequently formed on the cut surface and improving the passivation effect. For example, the first sub-region is the area where the laser cutting begins, including the molten silicon region, i.e., the area directly damaged by the laser. When the length of the first sub-region is less than 0.02%, it affects the cutting process. When the length of the first sub-region is greater than 0.2%, too much silicon is melted by the laser, resulting in excessive cutting losses.

[0039] In one implementation, along a first direction: the length of the first sub-region ranges from 50 μm to 300 μm, the length of the second sub-region ranges from 200 μm to 800 μm, and the length of the third sub-region ranges from 400 μm to 2000 μm.

[0040] By adopting the above technical solution, controlling the lengths of the three sub-regions within the aforementioned ranges in this application not only enables the cutting of the battery body but also controls post-cutting losses, ensuring the quality of the passivation layer subsequently formed on the cut surface and improving the passivation effect. For example, the first sub-region is the area where laser cutting begins, including the molten silicon region, i.e., the region directly damaged by the laser. When the length of the first sub-region is less than 50 μm, it affects the cutting process. When the length of the first sub-region is greater than 300 μm, too much silicon is molten by the laser, resulting in excessive cutting losses.

[0041] In one implementation, along a first direction: the ratio of the length of the first sub-region to the length of the first pre-cut region is 5% to 20%, the ratio of the length of the second sub-region to the length of the first pre-cut region is 10% to 40%, and the ratio of the length of the third sub-region to the length of the first pre-cut region is 30% to 80%. The length directions of the first, second, and third sub-regions are consistent with the first direction.

[0042] By employing the above technical solution, in this application, the ratios of the lengths of the three sub-regions to the length of the first pre-cut region are controlled within the aforementioned ranges. This not only enables the cutting of the battery body but also controls post-cutting losses, ensuring the quality of the passivation layer subsequently formed on the cut surface and improving the passivation effect. For example, the first sub-region is the area where laser cutting begins, including the molten silicon region, i.e., the area directly damaged by the laser. When the ratio of the length of the first sub-region to the length of the first pre-cut region is less than 5%, it affects the cutting process. When the ratio of the length of the first sub-region to the length of the first pre-cut region is greater than 20%, too much silicon is molten by the laser, resulting in excessive cutting losses.

[0043] In one implementation, along the second direction, the third sub-region includes a fourth region adjacent to the first surface and a fifth region further away from the first surface than the fourth region. The cut surface also includes a crack structure located in the fourth region and a first groove structure located in the fifth region.

[0044] With the above technical solution, the crack structure can be understood as a burr or step structure generated by the breakage of the battery body, which has a relatively large roughness. In this application, the crack structure is only located near the cutting edge (i.e., the crack structure is located in the fourth region), which can minimize the proportion of poor cutting morphology. Based on this, not only can the impact on the passivation layer subsequently formed on the cutting surface be reduced, but also, when fabricating some solar cells, the force applied to the printing screen by the doctor blade can be reduced, thus extending the life of the printing screen.

[0045] In one implementation, along a third direction, the depth of the crack structure is greater than the depth of the first groove structure.

[0046] At this point, the surface roughness of the region containing the first trench structure is less than that of the region containing the crack structure, and the surface roughness of the passivation layer subsequently formed in the region containing the first trench structure is also less than that in the region containing the crack structure. This not only minimizes the escape of sunlight but also ensures the passivation effect. Simultaneously, by reducing the surface roughness of the passivation layer, the solar cell can reduce light scattering and reflection, improving the effective utilization of light. Furthermore, low surface roughness reduces surface defects and traps, decreasing carrier recombination and thus improving the electrical performance of the solar cell.

[0047] In one implementation, the cut surface includes a second groove structure located in the thermal crack region. Along a second direction, the cut surface with the second groove structure sequentially includes an edge region and a middle region, with the middle region located between the edge regions. Along a third direction, the depth of the second groove structure located in the edge region is greater than or equal to the depth of the second groove structure located in the middle region.

[0048] With the above technical solution, the surface roughness of the edge region is greater than that of the middle region, while the surface roughness of the passivation layer subsequently formed in the middle region is less than that of the passivation layer subsequently formed in the edge region. This not only minimizes the escape of sunlight but also ensures the passivation effect. Simultaneously, by reducing the surface roughness of the passivation layer, the solar cell can reduce light scattering and reflection, improving the effective utilization of light. Furthermore, low surface roughness reduces surface defects and traps, decreasing carrier recombination and thus improving the electrical performance of the solar cell.

[0049] In one implementation, the hot-cracked region includes a molten silicon region, and the ratio of the area of ​​the molten silicon region to the area of ​​the hot-cracked region is 0.01%-5%.

[0050] This application controls the area ratio of the molten silicon region within the hot-cracked region, ensuring that the relative area of ​​the molten silicon region is within a reasonable range. This reduces the impact of the molten silicon region on the passivation characteristics and light absorption characteristics of the hot-cracked region, thereby improving the photoelectric conversion efficiency of the solar cell.

[0051] In one implementation, along the direction from the first end to the second end, the hot-crack region sequentially includes a first sub-hot-crack region and a second sub-hot-crack region. The cutting surface includes a second groove structure located within the hot-crack region. The second groove structure located within the first sub-hot-crack region has two different inclination directions, and the second groove structures with the two different inclination directions intersect each other.

[0052] In one implementation, the thermal cracking region sequentially includes a first sub-thermal cracking region and a second sub-thermal cracking region along the direction from the first end to the second end. The acute angle formed by the tangent line at the intersection of the second groove structure located in the first sub-thermal cracking region and the first surface with the first surface is β1, and the acute angle formed by the tangent line at the intersection of the second groove structure located in the second sub-thermal cracking region and the first surface with the first surface is β2, where β1 > β2.

[0053] With the above technical solution, the inclination of the second trench structure located within the first sub-thermal crack region relative to the second direction is less than that of the second trench structure located within the second sub-thermal crack region. Based on this, not only can more stress concentration points be avoided in the first sub-thermal crack region, reducing the probability of cracks appearing in the solar cell during subsequent processing (e.g., texturing, coating) and use, but also, compared to the second trench structure located within the second sub-thermal crack region, the second trench structure located within the first sub-thermal crack region better conforms to the internal stress distribution law of the material, reducing the impact of surface defects caused by trench inclination on the overall performance of the solar cell. Furthermore, compared to the second trench structure located within the second sub-thermal crack region, the second trench structure located within the first sub-thermal crack region is more regular, allowing the chemical solution to act uniformly on the first sub-thermal crack region during subsequent cleaning, texturing, and other processes, improving the processing effect. Additionally, the roughness of the first sub-thermal crack region can be less than that of the second sub-thermal crack region, which can improve the quality of the film layer formed in the first sub-thermal crack region later, thereby improving the cell efficiency.

[0054] In one implementation, along a third direction, the depth of the second groove structure located within the first sub-thermal crack region is less than the depth of the second groove structure located within the second sub-thermal crack region.

[0055] At this point, the surface roughness of the first sub-thermal crack region is less than that of the second sub-thermal crack region, and the surface roughness of the passivation layer subsequently formed in the first sub-thermal crack region is also less than that of the passivation layer subsequently formed in the second sub-thermal crack region. This not only minimizes the escape of sunlight but also ensures the passivation effect. Simultaneously, by reducing the surface roughness of the passivation layer, the solar cell can reduce light scattering and reflection, improving the effective utilization of light. Furthermore, low surface roughness can reduce surface defects and traps, reducing carrier recombination, thereby improving the electrical performance of the solar cell.

[0056] In one implementation, the cutting surface includes a fourth trench structure located within the third pre-cut region. The third pre-cut region also includes multiple third molten silicon regions distributed between the first surface and the fourth trench structure.

[0057] With the above technical solution, compared to the third pre-cutting region being entirely composed of the third molten silicon region, the third pre-cutting region of this application is only partially composed of the third molten silicon region. This reduces the impact of the molten silicon region on the passivation characteristics and light absorption characteristics of the laser-damaged region, thereby improving the photoelectric conversion efficiency of the solar cell.

[0058] In one implementation, the depth of the fourth trench structure is greater than the depth of the third trench structure.

[0059] With the above technical solution, the surface roughness of the second sub-region with the third trench structure is less than the surface roughness of the third pre-cut region with the fourth trench structure, and the surface roughness of the passivation layer subsequently formed in the second sub-region is less than the surface roughness of the passivation layer subsequently formed in the third pre-cut region. This not only minimizes sunlight escape but also ensures the passivation effect. Simultaneously, by reducing the surface roughness of the passivation layer, the solar cell can reduce light scattering and reflection, improving the effective utilization rate of light. Furthermore, low surface roughness can reduce surface defects and traps, reduce carrier recombination, thereby improving the electrical performance of the solar cell.

[0060] In one implementation, the acute angle between the tangent line of the point in the third trench structure closest to the first surface and the first surface is γ, and the acute angle between the tangent line of the fourth trench structure at the intersection with the first surface and the first surface is θ, where γ < θ.

[0061] With the above technical solution, the tilt of the fourth trench structure relative to the second direction is less than the tilt of the third trench structure relative to the second direction. Based on this, it not only avoids generating more stress concentration points in the third pre-cut region with the fourth trench structure, reducing the probability of cracks appearing in the solar cell during subsequent processing (e.g., texturing, coating) and use, but also, compared to the third trench structure, the fourth trench structure better conforms to the internal stress distribution law of the material, reducing the impact of surface defects caused by trench tilt on the overall performance of the solar cell. Furthermore, compared to the second sub-region with the third trench structure, the third pre-cut region with the fourth trench structure is more regular, allowing the chemical solution to act evenly on the third pre-cut region during subsequent cleaning, texturing, and other processes, improving the processing effect. Additionally, the roughness of the third pre-cut region with the fourth trench structure can be less than the roughness of the second sub-region with the third trench structure, which can improve the quality of the film layer formed in the third pre-cut region later, thereby improving the cell efficiency.

[0062] In one implementation, the cutting surface includes a fifth trench structure located in the second pre-cut region. The second pre-cut region also includes multiple fourth molten silicon regions distributed between the first surface and the fifth trench structure.

[0063] With the above technical solution, compared to the second pre-cutting region being entirely composed of the fourth molten silicon region, the second pre-cutting region of this application is only partially composed of the fourth molten silicon region. This reduces the impact of the molten silicon region on the passivation characteristics and light absorption characteristics of the laser-damaged region, thereby improving the photoelectric conversion efficiency of the solar cell.

[0064] In one implementation, the depth of the fifth trench structure is greater than the depth of the third trench structure.

[0065] At this point, the surface roughness of the second sub-region with the third trench structure is less than that of the second pre-cut region with the fifth trench structure, and the surface roughness of the passivation layer subsequently formed in the second sub-region is less than that of the passivation layer subsequently formed in the second pre-cut region. This not only minimizes sunlight escape but also ensures effective passivation. Simultaneously, by reducing the surface roughness of the passivation layer, the solar cell can reduce light scattering and reflection, improving light utilization efficiency. Furthermore, low surface roughness reduces surface defects and traps, decreasing carrier recombination and thus improving the electrical performance of the solar cell.

[0066] In one implementation, the acute angle between the tangent line of the point in the third trench structure closest to the first surface and the first surface is γ, and the acute angle between the tangent line of the fifth trench structure at the intersection with the first surface and the first surface is η, where γ < η.

[0067] At this point, the tilt of the fifth trench structure relative to the second direction is less than that of the third trench structure relative to the second direction. Based on this, not only can more stress concentration points be avoided in the second pre-cut region with the fifth trench structure, reducing the probability of cracks appearing in the solar cell during subsequent processing (e.g., texturing, coating) and use, but also, compared to the third trench structure, the fifth trench structure better conforms to the internal stress distribution law of the material, reducing the impact of surface defects caused by trench tilt on the overall performance of the solar cell. Furthermore, compared to the second sub-region with the third trench structure, the second pre-cut region with the fifth trench structure is more regular, allowing the chemical solution to act evenly on the second sub-region during subsequent cleaning, texturing, and other processes, improving the processing effect. Additionally, the roughness of the second pre-cut region with the fifth trench structure can be less than that of the second sub-region with the third trench structure, which can improve the quality of the film layer formed in the second pre-cut region later, thereby improving cell efficiency.

[0068] In one implementation, the solar cell further includes a passivation layer, which is formed at least on the cut surface, and the average thickness of the passivation layer ranges from 10 nm to 120 nm.

[0069] With the above technical solution, the passivation layer can saturate the surface dangling bonds generated by the cut surfaces of the cell body being directly exposed to the air, thereby reducing recombination current and improving the conversion efficiency and module power of the solar cell. Furthermore, the average thickness of the passivation layer ranges from 10 nm to 120 nm. With this technical solution, the passivation effect of the solar cell increases progressively, and the conversion efficiency of the solar cell increases with the increase of the thickness of the first passivation layer. When the average thickness of the passivation layer is less than 10 nm, the passivation effect is not ideal; when the average thickness of the passivation layer is greater than 120 nm, it will result in material waste and excessively long deposition time, affecting the process cycle time.

[0070] In one implementation, the material of the passivation layer includes at least one or more of aluminum oxide, silicon nitride, silicon oxide, silicon oxynitride, intrinsic amorphous silicon, intrinsic microcrystalline silicon, doped amorphous silicon, or doped microcrystalline silicon.

[0071] In one implementation, along the second direction, the cutting surface includes a cutting edge and a fracture edge, with a pre-cutting region and a thermal cracking region located near the cutting edge. The thickness of the passivation layer near the cutting edge is greater than the thickness of the passivation layer near the fracture edge.

[0072] Secondly, this application also provides a photovoltaic module. The photovoltaic module includes a cell string and an encapsulation layer. The cell string includes multiple interconnects and multiple solar cells as described in the above technical solutions. The interconnects are used to electrically connect the multiple solar cells together to form the cell string, and the encapsulation layer is used to cover the surface of the cell string.

[0073] The beneficial effects of the photovoltaic modules provided in this application are the same as those of the solar cells described in the above technical solutions, and will not be repeated here.

[0074] Thirdly, this application also provides a method for manufacturing a solar cell. The method for manufacturing the solar cell includes: First, a battery body is provided, the battery body including opposing first and second surfaces; Next, the first surface is processed using a first laser process to create a plurality of guide grooves on the first surface; the guide grooves extend along a first direction, and the plurality of guide grooves are spaced apart along the first direction; Next, a second laser process is used to heat-treat the first surface along the first direction, forming a heat treatment path; Next, along the heat treatment path, the first laser process and the second laser process are alternately used to divide the battery body into at least two segmented battery bodies. The segmented battery body includes a first surface and a second surface opposite to each other, and a side surface connecting the first surface and the second surface, the side surface including a cut surface. Along a first direction, the cut surface includes a pre-cut region and a thermally cracked region, the thermally cracked region being located between two adjacent pre-cut regions; the pre-cut region corresponds to a guide groove, and the thermally cracked region is located in the heat treatment path. Along the first direction, the battery body includes a first end and a second end opposite to each other, the pre-cut region including a first pre-cut region near the first end of the battery body, a second pre-cut region near the second end of the battery body, and at least one third pre-cut region located between the first and second pre-cut regions. Along a second direction, the thickness of the pre-cut region is greater than the thickness of the thermally cracked region. The first direction and the second direction are parallel to the cut surface, the third direction is perpendicular to the cut surface, the second direction is the thickness direction of the battery body, and the first direction is perpendicular to the second direction.

[0075] In the method for manufacturing a solar cell provided in this application, the cutting surface includes a pre-cut area and a thermally cracked area. The pre-cut area corresponds to a guide groove opened by a laser (i.e., a laser-destructive cutting area). The pre-cut area includes at least three pre-cut areas located at different positions, and the thermally cracked area is located between two adjacent pre-cut areas. In this application, the guiding effect of the pre-cut area is not weakened due to the large length or width of the original solar cell, thus ensuring the morphology of the cut surface of the obtained sectional solar cells, thereby improving cell efficiency. Furthermore, along the second direction, the thickness of the pre-cut area is greater than the thickness of the thermally cracked area. This ensures a greater guiding effect of the pre-cut area, reducing or avoiding the pulling force of the guiding force and the thermal force, thus preventing unevenness of the cut surface due to pulling.

[0076] In one implementation, the width of the guide groove ranges from 10 μm to 50 μm along a third direction.

[0077] When using the above technical solution, a guide groove width of 10 μm or more facilitates the cutting of the fragments. A guide groove width of 50 μm or less can prevent excessive cutting damage.

[0078] In one implementation, the width of the heat treatment path ranges from 500 μm to 2000 μm along a third direction. Attached Figure Description

[0079] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram showing the relationship between the battery body, the thermal cracking area, and the first type of pre-cut area in an embodiment of this application; Figure 2This is a schematic diagram showing the relationship between the battery body, the thermal cracking region, and the second type of pre-cut region in an embodiment of this application. Figure 3 This is a SEM image of the first pre-cut region in this embodiment of the application; Figure 4 This is a schematic diagram of the first pre-cut region in an embodiment of this application; Figure 5 Examples of embodiments in this application Figure 4 Enlarged view of a portion of the area; Figure 6 This is a SEM image of the second pre-cut region in the embodiments of this application; Figure 7 This is a schematic diagram of the second pre-cut region in an embodiment of this application; Figure 8 SEM image of the third pre-cut region in the embodiments of this application. Figure 9 This is a schematic diagram of the third pre-cut region in an embodiment of this application; Figure 10 This is a SEM image of the thermal crack region in an embodiment of this application; Figure 11 This is a schematic diagram of the third trench structure in an embodiment of this application; Figure 12 This is a schematic diagram illustrating the relationship between light and solar cells in an embodiment of this application.

[0080] Figure label: 1-Battery body, 10-First surface, 11-Cut surface; 2-Pre-cut area, 20-First pre-cut area, 200-First sub-area, 201-Second sub-area, 2010-First area, 2011-Second area, 2012-Third area; 202-Third sub-area, 21-Second pre-cut area, 22-Third pre-cut area; 3-Hot crack area, 30-First sub-hot crack area, 31-Second sub-hot crack area; 40-First molten silicon area, 41-First trench structure, 42-Second trench structure, 43-Third trench structure, 44-Second molten silicon area, 45-Fourth trench structure, 46-Third molten silicon area, 47-Fifth trench structure, 48-Fourth molten silicon area, 49-Crack structure, 5-Segmented battery body. Detailed Implementation

[0081] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit the scope of this application. It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on or indirectly on that other element. When an element is referred to as being "connected to" another element, it can be directly connected to or indirectly connected to that other element.

[0082] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise expressly specified. "Several" means one or more, unless otherwise expressly specified.

[0083] In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0084] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0085] Firstly, this application provides a solar cell. See [link to application]. Figures 1 to 12 The solar cell includes a cell body 1, which includes a first surface 10 and a second surface opposite to each other, and a side surface connecting the first surface 10 and the second surface. The side surface includes a cut surface 11.

[0086] The battery body may consist of only a semiconductor substrate, or it may consist of a semiconductor substrate and a film layer formed on the semiconductor substrate.

[0087] For example, the semiconductor substrate described above can be a silicon substrate. In terms of conductivity type, the semiconductor substrate can be an intrinsically conductive substrate, an N-type conductive substrate, or a P-type conductive substrate. Preferably, the semiconductor substrate is an N-type conductive substrate or a P-type conductive substrate. Compared to an intrinsically conductive substrate, an N-type conductive substrate or a P-type conductive substrate has higher conductivity, which helps to reduce the series resistance of the solar cell and improve its efficiency. Structurally, the first surface of the solar cell can be textured to improve the light-trapping effect of the light-receiving surface, thereby improving the utilization rate of light by the solar cell. Of course, the first surface of the solar cell can also be planar. As for the second surface of the solar cell, it can be polished or textured; no specific limitation is made here. In terms of light reception, the first surface can be a light-receiving surface, in which case the second surface is a backlighting surface. Alternatively, the first surface can be a backlighting surface, in which case the second surface is a light-receiving surface.

[0088] The aforementioned film can be a doped layer, a passivation layer, an antireflection layer, etc.

[0089] See Figures 1 to 4 Along the first direction A, the cutting surface 11 includes a pre-cut region 2 and a thermally cracked region 3, with the thermally cracked region 3 located between two adjacent pre-cut regions 2. Along the first direction A, the battery body 1 includes a first end and a second end opposite to each other. The pre-cut region 2 includes a first pre-cut region 20 near the first end of the battery body 1, a second pre-cut region 21 near the second end of the battery body 1, and at least one third pre-cut region 22 located between the first pre-cut region 20 and the second pre-cut region 21. Along the second direction B, the thickness of the pre-cut region 2 is greater than the thickness of the thermally cracked region 3. The first direction A and the second direction B are parallel to the cutting surface 11, and the third direction is perpendicular to the cutting surface 11. The second direction B is the thickness direction of the battery body 1, and the first direction A is perpendicular to the second direction B. It should be noted that the "thickness of the pre-cut region" and the "thickness of the thermally cracked region" can be understood as the maximum depth of direct laser action.

[0090] In actual solar cell manufacturing, the side surface of a solar cell typically includes an uncut "non-cut surface" and a cut surface formed after cutting. The non-cut surface generally does not have attached silicon slag or silicon oxide, and even if it does, the amount is negligible. Therefore, this discussion focuses on the silicon slag and silicon oxide on the cut surface. A significant source of this silicon slag and silicon oxide is the destructive laser used during cell cutting to irradiate the silicon substrate of the solar cell. The silicon substrate absorbs the laser energy, melts, and oxidizes to form the slag and silicon oxide. The portion of the silicon slag and silicon oxide that remains after processing is the molten silicon region described in this application.

[0091] In the solar cell provided in this application, the cut surface 11 includes a pre-cut region 2 and a thermally cracked region 3. The pre-cut region 2 is a guide groove region opened by laser (i.e., a laser-destructive cutting region). The pre-cut region 2 includes at least three pre-cut regions 2 located at different positions, and the thermally cracked region 3 is located between two adjacent pre-cut regions 2. In this application, the guiding effect of the pre-cut region 2 will not be weakened due to the large length or width of the original solar cell, thus ensuring the morphology of the cut surface 11 of the obtained diced solar cell, thereby improving the cell efficiency. Furthermore, along the second direction B, the thickness of the pre-cut region 2 is greater than the thickness of the thermally cracked region 3. In this case, the guiding effect of the pre-cut region 2 can be ensured to be greater, reducing or avoiding the pulling force of the guiding force and the thermal force, so as to avoid unevenness of the cut surface 11 due to pulling.

[0092] As one possible implementation, see Figure 1 and Figure 2 The lengths of the first pre-cut region 20, the second pre-cut region 21, and the third pre-cut region 22 are all between 0.5 mm and 5 mm. And / or, the ratio of the lengths of the first pre-cut region 20, the second pre-cut region 21, and the third pre-cut region 22 to the length of the battery body 1 in the first direction A is 0.5% to 5%. And / or, the spacing between two adjacent pre-cut regions 2 is 10 mm to 100 mm. The length direction of the pre-cut region 2 and the length direction of the thermal cracking region 3 are consistent with the first direction A.

[0093] At this point, while ensuring the guiding role of the pre-cutting area 2 and smoothly cutting the battery body 1, the shape of the cut surface 11 of the obtained sectional solar cell can be ensured, thereby improving the battery efficiency.

[0094] For example, the lengths of the first pre-cut area 20, the second pre-cut area 21, and the third pre-cut area 22 can be 0.5mm, 0.8mm, 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, 2.2mm, 2.5mm, 2.8mm, 3mm, 3.2mm, 3.5mm, 3.8mm, 4mm, 4.2mm, 4.5mm, 4.8mm, or 5mm, etc.

[0095] The ratio of the lengths of the first pre-cut region 20, the second pre-cut region 21, and the third pre-cut region 22 to the length of the battery body 1 in the first direction A can be 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, or 5%, etc.

[0096] The spacing between two adjacent pre-cut areas 2 can be 10mm, 12mm, 15mm, 18mm, 20mm, 22mm, 25mm, 28mm, 30mm, 32mm, 35mm, 38mm, 40mm, 42mm, 45mm, 48mm, 50mm, 52mm, 55mm, 58mm, 60mm, 62mm, 65mm, 68mm, 70mm, 72mm, 75mm, 78mm, 80mm, 82mm, 85mm, 88mm, 90mm, 92mm, 95mm, 98mm or 100mm, etc.

[0097] It should be noted that the lengths of the first pre-cut region 20, the second pre-cut region 21, and the third pre-cut region 22 may be equal or unequal, depending on the specific circumstances. The ratio of the lengths of the first pre-cut region 20, the second pre-cut region 21, and the third pre-cut region 22 to the length of the cell body 1 in the first direction A may also be equal or unequal, depending on the specific circumstances. When the solar cell includes multiple "spacings between adjacent pre-cut regions 2", these multiple "spacings between adjacent pre-cut regions 2" may be equal or unequal, depending on the specific circumstances.

[0098] As one possible implementation, see Figure 1 and Figure 2 The length of the first pre-cut region 20 is greater than the length of the third pre-cut region 22. The length directions of both the first pre-cut region 20 and the third pre-cut region 22 are aligned with the first direction A.

[0099] When the first pre-cut region 20 is the first cutting region in the process of cutting the whole solar cell, since the length of the first pre-cut region 20 is greater than the length of the third pre-cut region 22, the guiding effect of the first pre-cut region 20 is greater, which can ensure that the extension path and morphology of the subsequent hot region meet the actual requirements.

[0100] See Figure 1 and Figure 2 Along the first direction A, the length of the third pre-cut region 22 is greater than or equal to the length of the second pre-cut region 21. The length directions of the second pre-cut region 21 and the third pre-cut region 22 are consistent with the first direction A.

[0101] When the second pre-cut region 21 is the last cut region in the process of cutting the entire solar cell, since the length of the third pre-cut region 22 is greater than or equal to the length of the second pre-cut region 21, it can not only ensure the guiding effect of the third pre-cut region 22 on the hot region, but also reduce the damage of the second pre-cut region 21 to the solar cell and improve the cell efficiency.

[0102] See Figure 1and Figure 2 Along the first direction A, the length of the pre-cut region 2 is less than the length of the hot crack region 3, and the length direction of the hot crack region 3 is consistent with the first direction A.

[0103] As described above, the pre-cutting area 2 is the guide groove area opened by the laser (i.e., the laser-damaged cutting area). When the length of the pre-cutting area 2 is less than the length of the thermal cracking area 3, the proportion of the laser-damaged cutting area can be reduced, thereby reducing the damage area of ​​the cutting surface 11.

[0104] As one possible implementation, see Figures 1 to 12 Along the second direction B, the thickness of the pre-cut region 2 ranges from 30μm to 140μm. And / or, the ratio of the thickness of the pre-cut region 2 to the thickness of the battery body 1 is 0.2-0.8. And / or, the thickness of the thermal cracking region 3 ranges from 2μm to 20μm. And / or, the ratio of the thickness of the thermal cracking region 3 to the thickness of the battery body 1 is 0.01-0.15. And / or, the ratio of the thickness of the thermal cracking region 3 to the thickness of the pre-cut region 2 is 0.05-0.5. In this case, the guiding effect of the pre-cut region 2 can be ensured to be greater, reducing or avoiding the pulling effect of the guiding force and the thermal force, thus preventing unevenness of the cut surface 11 due to pulling.

[0105] For example, along the second direction B, the thickness of the pre-cut region 2 can be 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, or 140μm, etc. The ratio of the thickness of the pre-cut region 2 to the thickness of the battery body 1 can be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, or 0.8, etc. The thickness of the thermal crack region 3 can be 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, or 20μm, etc. The ratio of the thickness of the thermal crack region 3 to the thickness of the battery body 1 can be 0.01, 0.03, 0.05, 0.08, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15, etc. The ratio of the thickness of the hot-cracked region 3 to the thickness of the pre-cut region 2 can be 0.05, 0.08, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45 or 0.5, etc.

[0106] As one possible implementation, see Figure 1 and Figure 2 The number of third pre-cut regions 22 is 1-10. For example, the number of third pre-cut regions 22 can be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. The more third pre-cut regions 22 there are, the stronger their guiding effect, which can improve the morphology of the cut surface 11 of the sectional solar cell. Furthermore, in this application, the third pre-cut regions 22 are dispersed on the cut surface 11. Compared with the case where the total area of ​​the third pre-cut regions 22 is the same but the third pre-cut regions 22 are concentrated, this application reduces the damage to the cut surface 11 caused by the concentrated distribution, further improves the morphology of the cut surface 11 of the sectional solar cell, and thus further improves the cell efficiency.

[0107] As one possible implementation, see Figures 3 to 7 Both the first pre-cut region 20 and the second pre-cut region 21 include molten silicon regions, wherein the area ratio of the molten silicon region in the first pre-cut region 20 is greater than the area ratio of the molten silicon region in the second pre-cut region 21.

[0108] At this time, compared with the area ratio of the molten silicon region in the second pre-cut region 21 being greater than or equal to the area ratio of the molten silicon region in the first pre-cut region 20, this application controls the area ratio of the molten silicon region on the cutting surface 11 to keep the relative area of ​​the molten silicon region within a reasonable range, thereby reducing the influence of the molten silicon region on the passivation characteristics and light absorption characteristics of the laser-damaged region and improving the photoelectric conversion efficiency of the solar cell.

[0109] As one possible implementation, see Figures 3 to 9 The third pre-cut region 22 includes a molten silicon region, and the area ratio of the molten silicon region in the first pre-cut region 20 is greater than that in the third pre-cut region 22. Compared to the situation where the area ratio of the molten silicon region in the third pre-cut region 22 is greater than or equal to that in the first pre-cut region 20, this application further controls the area ratio of the molten silicon region on the cutting surface 11, ensuring that the relative area of ​​the molten silicon region is within a reasonable range. This further reduces the impact of the molten silicon region on the passivation characteristics and light absorption characteristics of the laser-damaged region, and further improves the photoelectric conversion efficiency of the solar cell.

[0110] In some embodiments, the area ratio of the molten silicon region in the first pre-cut region 20 ranges from 10% to 40%, such as 10%, 15%, 20%, 25%, 30%, or 40%.

[0111] The area ratio of the molten silicon region in the second pre-cut region 21 ranges from 5% to 30%, for example, 5%, 10%, 15%, 20%, 25%, or 30%.

[0112] The area ratio of the molten silicon region in the third pre-cut region 22 ranges from 1% to 20%, such as 1%, 5%, 10%, 15%, or 20%.

[0113] As one possible implementation, see Figures 3 to 11 The cutting surface 11 includes a groove structure. The groove structure located in the first pre-cutting region 20 has a first depth, the groove structure located in the second pre-cutting region 21 has a second depth, the groove structure located in the third pre-cutting region 22 has a third depth, and the groove structure located in the hot cracking region 3 has a fourth depth. Wherein, the first depth is greater than the second depth; and / or, the first depth is greater than the third depth; and / or, the first depth is greater than the fourth depth; and / or, the second depth is greater than the fourth depth; and / or, the third depth is greater than the fourth depth.

[0114] With the above technical solution, the trench structure located in the hot crack region 3 has the shallowest depth. At this time, the surface roughness of the hot crack region 3 is small, which provides a good foundation for the formation of the subsequent passivation layer. This results in a better quality of the passivation layer formed on the hot crack region 3, improving the passivation effect and thus ensuring the efficiency of the solar cell.

[0115] As one possible implementation, see Figures 5 to 6 ,as well as Figure 11 Along the direction from the first end to the second end, the first pre-cut region 20 sequentially includes a first sub-region 200, a second sub-region 201, and a third sub-region 202. The first sub-region 200 includes multiple first molten silicon regions 40. The cut surface 11 includes a first trench structure 41 and a second trench structure 42. The first trench structure 41 is located in the third sub-region 202, and the second trench structure 42 is located in the hot-cracked region 3. Along the third direction, the depth of the second trench structure 42 is less than the depth of the first trench structure 41. At this time, the surface roughness of the hot-cracked region 3 with the second trench structure 42 is small, which provides a good foundation for the formation of the subsequent passivation layer. This results in a better quality passivation layer formed on the hot-cracked region 3, improving the passivation effect and thus ensuring the efficiency of the solar cell.

[0116] In one alternative approach, see Figure 6 and Figure 11 The acute angle formed by the tangent of the point in the first groove structure 41 closest to the first surface 10 and the first surface 10 is α, and the acute angle formed by the tangent of the second groove structure 42 at the intersection with the first surface 10 and the first surface 10 is β, where α < β.

[0117] Since α < β, the inclination of the second trench structure 42 relative to the second direction B is less than that of the first trench structure 41 relative to the second direction B. This not only avoids more stress concentration points in the thermally cracked region 3 with the second trench structure 42, reducing the probability of cracks appearing in the solar cell during subsequent processing (e.g., texturing, coating) and use, but also, compared to the first trench structure 41, the second trench structure 42 better conforms to the internal stress distribution of the material, reducing the impact of surface defects caused by trench inclination on the overall performance of the solar cell. Furthermore, compared to the third sub-region 202 with the first trench structure 41, the thermally cracked region 3 with the second trench structure 42 is more regular, allowing the chemical solution to act evenly on the thermally cracked region 3 during subsequent cleaning, texturing, and other processes, improving the processing effect. Additionally, the roughness of the thermally cracked region 3 with the second trench structure 42 can be less than that of the third sub-region 202 with the first trench structure 41, which can improve the quality of the film layer formed in the thermally cracked region 3, thereby improving the cell efficiency.

[0118] In some embodiments, the difference between β and α ranges from 5° to 60°. For example, the difference can be 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, or 60°.

[0119] Preferably, the difference between β and α ranges from 10° to 45°. For example, the difference can be 10°, 15°, 20°, 25°, 30°, 35°, 40°, or 45°.

[0120] In some embodiments, α can be 25°-60° and β can be 70°-90°.

[0121] Preferably, α can be 45°-60°, and β can be 80°-90°.

[0122] In one alternative approach, see Figure 4 and Figure 11 The cut surface 11 also includes a third trench structure 43, which is located in the second sub-region 201. The second sub-region 201 includes multiple second molten silicon regions 44, which are distributed between the edge near the first surface 10 and the third trench structure 43. Compared to the second sub-region 201 being entirely composed of second molten silicon regions 44, in this application, only a portion of the second sub-region 201 is composed of second molten silicon regions 44, reducing the impact of the molten silicon regions on the passivation characteristics and light absorption characteristics of the laser-damaged areas, and improving the photoelectric conversion efficiency of the solar cell.

[0123] In some embodiments, see Figure 11Along the second direction B, the cut surface 11 with the third trench structure 43 sequentially includes a first region 2010, a second region 2011, and a third region 2012, with the first region 2010 located between the second region 2011 and the second molten silicon region 44. Along the third direction, the depths of the third trench structure 43 in the first region 2010 and the third trench structure 43 in the third region 2012 are both greater than or equal to the depth of the third trench structure 43 in the second region 2011. At this point, the surface roughness of the first region 2010 and the third region 2012 is greater than the surface roughness of the second region 2011. Consequently, the surface roughness of the passivation layer subsequently formed in the second region 2011 is less than the surface roughness of the passivation layers subsequently formed in the first region 2010 and the third region 2012. Based on this, not only can the escape of sunlight be minimized, but the passivation effect can also be guaranteed. Simultaneously, by reducing the surface roughness of the passivation layer, the solar cell can reduce light scattering and reflection, improving the effective utilization rate of light. Furthermore, low surface roughness can reduce surface defects and traps, reduce carrier recombination, and thus improve the electrical performance of solar cells.

[0124] In some embodiments, see Figure 11 Along the third direction, the depth of the third trench structure 43 is less than the depth of the first trench structure 41. At this time, the surface roughness of the second sub-region 201 with the third trench structure 43 is less than the surface roughness of the third sub-region 202 with the first trench structure 41, and the surface roughness of the passivation layer subsequently formed in the second sub-region 201 is less than the surface roughness of the passivation layer subsequently formed in the third sub-region 202. Based on this, not only can the escape of sunlight be minimized, but the passivation effect can also be guaranteed. Simultaneously, by reducing the surface roughness of the passivation layer, the solar cell can reduce light scattering and reflection, improving the effective utilization rate of light. Furthermore, low surface roughness can reduce surface defects and traps, reduce carrier recombination, thereby improving the electrical performance of the solar cell.

[0125] In some embodiments, see Figure 10 The depth of the third trench structure 43 is greater than the depth of the second trench structure 42. At this point, the surface roughness of the hot-cracked region 3 with the second trench structure 42 is less than the surface roughness of the second sub-region 201 with the third trench structure 43, and the surface roughness of the passivation layer subsequently formed in the hot-cracked region 3 is less than the surface roughness of the passivation layer subsequently formed in the second sub-region 201. This not only minimizes the escape of sunlight but also ensures the passivation effect. Simultaneously, by reducing the surface roughness of the passivation layer, the solar cell can reduce light scattering and reflection, improving the effective utilization rate of light. Furthermore, low surface roughness can reduce surface defects and traps, reduce carrier recombination, thereby improving the electrical performance of the solar cell.

[0126] In some embodiments, see Figure 10 The slope of the third trench structure 43 is less than that of the second trench structure 42. Therefore, the inclination of the third trench structure 43 relative to the second direction B is greater than that of the second trench structure 42 relative to the second direction B. Based on this, not only can more stress concentration points be avoided in the hot-cracked region 3 with the second trench structure 42, reducing the probability of cracks appearing in the solar cell during subsequent processing (e.g., texturing, coating) and use, but also, compared to the third trench structure 43, the second trench structure 42 better conforms to the internal stress distribution law of the material, reducing the impact of surface defects caused by trench inclination on the overall performance of the solar cell. Furthermore, compared to the second sub-region 201 with the third trench structure 43, the hot-cracked region 3 with the second trench structure 42 is more regular, allowing the chemical solution to act evenly on the hot-cracked region 3 during subsequent cleaning, texturing, and other processes, improving the processing effect. In addition, the roughness of the hot-cracked region 3 with the second trench structure 42 can be made smaller than the roughness of the second sub-region 201 with the third trench structure 43. This can improve the quality of the film layer formed in the hot-cracked region 3 later, thereby improving the battery efficiency.

[0127] In some embodiments, see Figure 5 In the first groove structure 41, the acute angle formed by the tangent line of the point near the first surface 10 and the first surface 10 is α, and in the third groove structure 43, the acute angle formed by the tangent line of the point near the first surface 10 and the first surface 10 is γ, where α < γ.

[0128] At this point, the inclination of the third trench structure 43 relative to the second direction B is less than the inclination of the first trench structure 41 relative to the second direction B. Based on this, not only can more stress concentration points be avoided in the second sub-region 201 with the third trench structure 43, reducing the probability of cracks appearing in the solar cell during subsequent processing (e.g., texturing, coating) and use, but also, compared to the first trench structure 41, the third trench structure 43 better conforms to the internal stress distribution law of the material, reducing the impact of surface defects caused by trench inclination on the overall performance of the solar cell. Furthermore, compared to the third sub-region 202 with the first trench structure 41, the second sub-region 201 with the third trench structure 43 is more regular, allowing the chemical solution to act evenly on the second sub-region 201 during subsequent cleaning, texturing, and other processes, improving the processing effect. Additionally, the roughness of the second sub-region 201 with the third trench structure 43 can be less than that of the third sub-region 202 with the first trench structure 41, which can improve the quality of the film layer formed in the second sub-region 201 later, thereby improving the cell efficiency.

[0129] In one alternative approach, see Figure 3Along the first direction A: the ratio of the length L1 of the first sub-region 200 to the length of the battery body 1 is 0.02% to 0.2%, the ratio of the length L2 of the second sub-region 201 to the length of the battery body 1 is 0.1% to 0.5%, and the ratio of the length L3 of the third sub-region 202 to the length of the battery body 1 is 0.2% to 1%. The length directions of the first sub-region 200, the second sub-region 201, and the third sub-region 202 are consistent with the first direction A.

[0130] In this application, the ratios of the lengths of the three sub-regions to the length of the battery body 1 are controlled within the aforementioned ranges. This not only enables the cutting of the battery body 1 but also controls the losses after cutting, ensuring the quality of the passivation layer subsequently formed on the cut surface 11 and improving the passivation effect. For example, the first sub-region 200 is the area where the laser cutting begins, including the molten silicon region, i.e., the area directly damaged by the laser. When the length of the first sub-region 200 is less than 0.02%, it affects the cutting process. When the length of the first sub-region 200 is greater than 0.2%, too much silicon is melted by the laser, resulting in excessive cutting losses.

[0131] For example, the ratio of the length of the first sub-region 200 to the length of the battery body 1 can be 0.02%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.18%, or 0.2%, etc. The ratio of the length of the second sub-region 201 to the length of the battery body 1 can be 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%, etc. The ratio of the length of the third sub-region 202 to the length of the battery body 1 can be 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, or 1%, etc.

[0132] Preferably, along the first direction A: the ratio of the length of the first sub-region 200 to the length of the battery body 1 is 0.02% to 0.1%, the ratio of the length of the second sub-region 201 to the length of the battery body 1 is 0.2% to 0.4%, and the ratio of the length of the third sub-region 202 to the length of the battery body 1 is 0.2% to 0.5%.

[0133] In one alternative embodiment, along the first direction A: the ratio of the length L1 of the first sub-region 200 to the length of the first pre-cut region 20 is 5% to 20%, the ratio of the length L2 of the second sub-region 201 to the length of the first pre-cut region 20 is 10% to 40%, and the ratio of the length L3 of the third sub-region 202 to the length of the first pre-cut region 20 is 30% to 80%. The length directions of the first sub-region 200, the second sub-region 201, and the third sub-region 202 are consistent with the first direction A.

[0134] In this application, the ratios of the lengths of the three sub-regions to the length of the first pre-cut region 20 are controlled within the aforementioned ranges. This not only enables the cutting of the battery body 1 but also controls the losses after cutting, ensuring the quality of the passivation layer subsequently formed on the cut surface 11 and improving the passivation effect. For example, the first sub-region 200 is the region where laser cutting begins, including the molten silicon region, i.e., the region directly damaged by the laser. When the ratio of the length of the first sub-region 200 to the length of the first pre-cut region 20 is less than 5%, it affects the cutting process. When the ratio of the length of the first sub-region 200 to the length of the first pre-cut region 20 is greater than 20%, too much silicon is melted by the laser, resulting in excessive cutting losses.

[0135] For example, the ratio of the length of the first sub-region 200 to the length of the first pre-cut region 20 can be 5%, 5.5%, 6%, 6.5%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, etc.

[0136] The ratio of the length of the second sub-region 201 to the length of the first pre-cut region 20 can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%, etc.

[0137] The ratio of the length of the third sub-region 202 to the length of the first pre-cut region 20 can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, or 80%, etc.

[0138] Preferably, along the first direction A: the ratio of the length of the first sub-region 200 to the length of the first pre-cut region 20 is 5% to 10%, the ratio of the length of the second sub-region 201 to the length of the first pre-cut region 20 is 10% to 20%, and the ratio of the length of the third sub-region 202 to the length of the first pre-cut region 20 is 30% to 50%.

[0139] In some embodiments, along the first direction A: the length L1 of the first sub-region 200 ranges from 50 μm to 300 μm, the length L2 of the second sub-region 201 ranges from 200 μm to 800 μm, and the length L3 of the third sub-region 202 ranges from 400 μm to 2000 μm.

[0140] In this application, the lengths of the three sub-regions are controlled within the aforementioned ranges. This not only enables the cutting of the battery body 1 but also controls the losses after cutting, ensuring the quality of the passivation layer subsequently formed on the cut surface 11 and improving the passivation effect. For example, the first sub-region 200 is the region where laser cutting begins, including the molten silicon region, i.e., the region directly damaged by the laser. When the length of the first sub-region 200 is less than 50 μm, it affects the cutting process. When the length of the first sub-region 200 is greater than 300 μm, too much silicon is molten by the laser, resulting in excessive cutting losses.

[0141] For example, the length L1 of the first sub-region 200 can be 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, 210μm, 220μm, 230μm, 240μm, 250μm, 260μm, 270μm, 280μm, 290μm, or 300μm, etc.

[0142] The length L2 of the second sub-region 201 may be 200 μm, 210 μm, 220 μm, 230 μm, 240 μm, 250 μm, 260 μm, 270 μm, 280 μm, 290 μm, 300 μm, 310 μm, 320 μm, 330 μm, 340 μm, 350 μm, 360 μm, 3 70μm, 380μm, 390μm, 400μm, 430μm, 450μm, 480μm, 500μm, 530μm, 550μm, 5 80μm, 600μm, 630μm, 650μm, 680μm, 700μm, 730μm, 750μm, 780μm or 800μm, etc.

[0143] The length L3 of the third sub-region 202 may be 400 μm, 430 μm, 450 μm, 480 μm, 500 μm, 530 μm, 550 μm, 580 μm , 600μm, 630μm, 650μm, 680μm, 700μm, 730μm, 750μm, 780μm, 800μm, 830μm, 85 0μm, 880μm, 900μm, 930μm, 950μm, 980μm, 1000μm, 1030μm, 1100μm, 1150μm, 1 200μm, 1300μm, 1400μm, 1500μm, 1600μm, 1700μm, 1800μm, 1900μm or 2000μm, etc.

[0144] Preferably, along the first direction A: the length of the first sub-region 200 ranges from 50 μm to 100 μm, the length of the second sub-region 201 ranges from 200 μm to 400 μm, and the length of the third sub-region 202 ranges from 400 μm to 800 μm.

[0145] As one possible implementation, see Figure 4 Along the second direction B, the third sub-region 202 includes a fourth region adjacent to the first surface 10 and a fifth region further away from the first surface 10 than the fourth region. The cut surface 11 also includes a crack structure 49 located in the fourth region and a first groove structure 41 located in the fifth region.

[0146] The crack structure 49 can be understood as a burr or step structure generated by the breakage of the battery body 1, which has a relatively large roughness. In this application, the crack structure 49 is only located near the cutting edge (i.e., the crack structure 49 is located in the fourth region), which can minimize the proportion of poor cutting morphology. Based on this, not only can the impact on the passivation layer subsequently formed on the cutting surface 11 be reduced, but also when some solar cells are fabricated and a doctor blade is used to apply force to the printing screen, the damage caused by the crack structure 49 to the printing screen can be reduced, thus extending the life of the printing screen.

[0147] In one alternative approach, see Figure 4Along the third direction, the depth of the crack structure 49 is greater than the depth of the first trench structure 41. At this point, the surface roughness of the region where the first trench structure 41 is located is less than the surface roughness of the region where the crack structure 49 is located, and the surface roughness of the passivation layer subsequently formed in the region where the first trench structure 41 is located is less than the surface roughness of the passivation layer subsequently formed in the region where the crack structure 49 is located. This not only minimizes the escape of sunlight but also ensures the passivation effect. Simultaneously, by reducing the surface roughness of the passivation layer, the solar cell can reduce light scattering and reflection, improving the effective utilization rate of light. Furthermore, low surface roughness can reduce surface defects and traps, reduce carrier recombination, thereby improving the electrical performance of the solar cell.

[0148] As one possible implementation, see Figure 10 The cut surface 11 includes a second groove structure 42 located in the hot crack region 3. Along the second direction B, the cut surface 11 with the second groove structure 42 sequentially includes an edge region and a middle region, with the middle region located between the edge regions. Along the third direction, the depth of the second groove structure 42 located in the edge region is greater than or equal to the depth of the second groove structure 42 located in the middle region.

[0149] At this point, the surface roughness of the edge region is greater than that of the middle region, while the surface roughness of the passivation layer subsequently formed in the middle region is less than that of the passivation layer subsequently formed in the edge region. Based on this, not only can sunlight escape be minimized, but the passivation effect can also be guaranteed. Simultaneously, by reducing the surface roughness of the passivation layer, the solar cell can reduce light scattering and reflection, improving the effective utilization of light. Furthermore, low surface roughness can reduce surface defects and traps, reducing carrier recombination, thereby improving the electrical performance of the solar cell.

[0150] As one possible implementation, the hot-cracked region also includes a molten silicon region, with the area of ​​the molten silicon region to the area of ​​the hot-cracked region being 0.01%-5%. For example, the ratio could be 0.01%, 0.05%, 0.08%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%, etc.

[0151] This application controls the area ratio of the molten silicon region within the hot-cracked region, ensuring that the relative area of ​​the molten silicon region is within a reasonable range. This reduces the impact of the molten silicon region on the passivation characteristics and light absorption characteristics of the hot-cracked region, thereby improving the photoelectric conversion efficiency of the solar cell.

[0152] As one possible implementation, see Figure 10Along the direction from the first end to the second end, the hot cracking region sequentially includes a first sub-hot cracking region 30 and a second sub-hot cracking region 31. The cutting surface 11 includes a second groove structure 42, which is located in the hot cracking region. The second groove structure 42 located in the first sub-hot cracking region 30 has two different inclination directions, and the two different inclination directions of the second groove structure 42 intersect each other.

[0153] As one possible implementation, see Figure 10 The acute angle formed by the tangent of the second groove structure 42 located in the first sub-thermal crack region 30 and the first surface 10 and the first surface 10 is β1, and the acute angle formed by the tangent of the second groove structure 42 located in the second sub-thermal crack region 31 and the first surface 10 and the first surface 10 is β2, where β1 > β2.

[0154] With the above technical solution, the inclination of the second trench structure 42 located in the first sub-thermal crack region 30 relative to the second direction B is less than that of the second trench structure 42 located in the second sub-thermal crack region 31 relative to the second direction B. Based on this, not only can more stress concentration points be avoided in the first sub-thermal crack region 30, reducing the probability of cracks appearing in the solar cell during subsequent processing (e.g., texturing, coating) and use, but also, compared to the second trench structure 42 located in the second sub-thermal crack region 31, the second trench structure 42 located in the first sub-thermal crack region 30 better conforms to the internal stress distribution law of the material, reducing the impact of surface defects caused by trench inclination on the overall performance of the solar cell. Furthermore, compared to the second trench structure 42 located in the second sub-thermal crack region 31, the second trench structure 42 located in the first sub-thermal crack region 30 is more regular, allowing the chemical solution to act evenly on the first sub-thermal crack region 30 during subsequent cleaning, texturing, and other processes, improving the processing effect. In addition, the roughness of the first sub-thermal crack region 30 can be made smaller than that of the second sub-thermal crack region 31. This can improve the quality of the film layer formed in the first sub-thermal crack region 30 later, thereby improving the battery efficiency.

[0155] In some embodiments, the difference between β1 and β2 ranges from 0.1° to 20°. For example, 0.1°, 1°, 5°, 10°, 15°, or 20°.

[0156] Preferably, the difference between β1 and β2 ranges from 0.1° to 10°. For example, 0.1°, 1°, 5°, or 10°.

[0157] In some embodiments, β1 ranges from 70° to 80°. For example, 70°, 71°, 72°, 73°, 74°, 75°, 76°, 77°, 78°, 79°, or 80°, etc.

[0158] The range of β2 is from 80° to 90°. For example, 80°, 81°, 82°, 83°, 84°, 85°, 86°, 87°, 88°, 89°, or 90°, etc.

[0159] As one possible implementation, see Figure 10 Along the third direction, the depth of the second groove structure 42 located in the first sub-thermal crack region 30 is less than the depth of the second groove structure 42 located in the second sub-thermal crack region 31.

[0160] At this point, the surface roughness of the first sub-thermal crack region 30 is less than that of the second sub-thermal crack region 31, and the surface roughness of the passivation layer subsequently formed in the first sub-thermal crack region 30 is also less than that of the passivation layer subsequently formed in the second sub-thermal crack region 31. This not only minimizes the escape of sunlight but also ensures the passivation effect. Simultaneously, by reducing the surface roughness of the passivation layer, the solar cell can reduce light scattering and reflection, improving the effective utilization of light. Furthermore, low surface roughness can reduce surface defects and traps, reducing carrier recombination, thereby improving the electrical performance of the solar cell.

[0161] In one alternative approach, see Figure 10 The depth of the second groove structure 42 located within the first sub-thermal crack region 30 ranges from 0.5 μm to 2 μm. For example, 0.5 μm, 1 μm, 1.5 μm, or 2 μm.

[0162] In some embodiments, the depth of the second groove structure 42 located within the first sub-thermal crack region 30 ranges from 0.2 μm to 1 μm. For example, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, or 1 μm.

[0163] In one alternative embodiment, the depth of the second groove structure 42 located within the second sub-thermal crack region 31 ranges from 0.3 μm to 1 μm. For example, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, or 1 μm.

[0164] In some embodiments, the depth of the second groove structure 42 located within the second sub-thermal crack region 31 ranges from 0.3 μm to 0.7 μm. For example, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, or 0.7 μm.

[0165] As one possible implementation, see Figure 10Along the direction from the first end to the second end, the length of the first sub-thermal crack region 30 ranges from 1 cm to 3 cm. For example, the length range can be 1 cm, 1.5 cm, 1.8 cm, 2 cm, 2.1 cm, 2.2 cm, 2.3 cm, 2.4 cm, 2.5 cm, 2.6 cm, 2.7 cm, 2.8 cm, 2.9 cm, or 3 cm, etc. Preferably, along the direction from the first end to the second end, the length of the first sub-thermal crack region 30 ranges from 1 cm to 1.8 cm.

[0166] As one possible implementation, see Figure 8 and Figure 9 The cut surface 11 includes a fourth trench structure 45, which is located in the third pre-cut region 22. The third pre-cut region 22 also includes multiple third molten silicon regions 46, which are distributed between the first surface 10 and the fourth trench structure 45. Compared to the third pre-cut region 22 being entirely composed of third molten silicon regions 46, the third pre-cut region 22 of this application has only a portion of third molten silicon regions 46, reducing the impact of the molten silicon regions on the passivation characteristics and light absorption characteristics of the laser-damaged areas, and improving the photoelectric conversion efficiency of the solar cell.

[0167] In one alternative approach, see Figure 4 , Figure 8 and Figure 9 The depth of the fourth trench structure 45 is greater than the depth of the third trench structure 43. Therefore, the surface roughness of the second sub-region 201 with the third trench structure 43 is less than the surface roughness of the third pre-cut region 22 with the fourth trench structure 45. Consequently, the surface roughness of the passivation layer subsequently formed in the second sub-region 201 is less than the surface roughness of the passivation layer subsequently formed in the third pre-cut region 22. Based on this, not only can the escape of sunlight be minimized, but the passivation effect can also be guaranteed. Simultaneously, by reducing the surface roughness of the passivation layer, the solar cell can reduce light scattering and reflection, improving the effective utilization rate of light. Furthermore, low surface roughness can reduce surface defects and traps, reduce carrier recombination, thereby improving the electrical performance of the solar cell.

[0168] In one alternative approach, see Figure 5 and Figure 9In the third trench structure 43, the acute angle formed by the tangent at the point closest to the first surface 10 and the first surface 10 is γ, and the acute angle formed by the tangent at the intersection of the fourth trench structure 45 and the first surface 10 and the first surface 10 is θ, where γ < θ. At this point, the tilt of the fourth trench structure 45 relative to the second direction B is less than the tilt of the third trench structure 43 relative to the second direction B. Based on this, not only can more stress concentration points be avoided in the third pre-cut region 22 with the fourth trench structure 45, reducing the probability of cracks appearing in the solar cell during subsequent processing (e.g., texturing, coating) and use, but also, compared to the third trench structure 43, the fourth trench structure 45 better conforms to the internal stress distribution law of the material, reducing the impact of surface defects caused by trench tilt on the overall performance of the solar cell. Furthermore, compared to the second sub-region 201 with the third trench structure 43, the third pre-cut region 22 with the fourth trench structure 45 is more regular. In subsequent processes such as cleaning and texturing, this allows the chemical solution to act evenly on the third pre-cut region 22, improving the processing effect. Additionally, the roughness of the third pre-cut region 22 with the fourth trench structure 45 can be made less than the roughness of the second sub-region 201 with the third trench structure 43. This improves the quality of the film layer formed in the third pre-cut region 22, thereby increasing battery efficiency.

[0169] As one possible implementation, see Figure 6 and Figure 7 The cut surface 11 includes a fifth trench structure 47, which is located in the second pre-cut region 21. The second pre-cut region 21 also includes multiple fourth molten silicon regions 48, which are distributed between the first surface 10 and the fifth trench structure 47. Compared to the second pre-cut region 21 being entirely composed of fourth molten silicon regions 48, the second pre-cut region 21 of this application has only a portion of fourth molten silicon regions 48, reducing the impact of the molten silicon regions on the passivation characteristics and light absorption characteristics of the laser-damaged areas, and improving the photoelectric conversion efficiency of the solar cell.

[0170] In one alternative approach, see Figure 4 , Figure 6 and Figure 7The depth of the fifth trench structure 47 is greater than the depth of the third trench structure 43. At this point, the surface roughness of the second sub-region 201 with the third trench structure 43 is less than the surface roughness of the second pre-cut region 21 with the fifth trench structure 47, and the surface roughness of the passivation layer subsequently formed in the second sub-region 201 is less than the surface roughness of the passivation layer subsequently formed in the second pre-cut region 21. Based on this, not only can the escape of sunlight be minimized, but the passivation effect can also be guaranteed. Simultaneously, by reducing the surface roughness of the passivation layer, the solar cell can reduce light scattering and reflection, improving the effective utilization rate of light. Furthermore, low surface roughness can reduce surface defects and traps, reduce carrier recombination, thereby improving the electrical performance of the solar cell.

[0171] In one alternative approach, see Figure 5 and Figure 7 In the third trench structure 43, the acute angle formed by the tangent at the point closest to the first surface 10 and the first surface 10 is γ, and the acute angle formed by the tangent at the intersection of the fifth trench structure 47 and the first surface 10 and the first surface 10 is η, where γ < η. At this time, the inclination of the fifth trench structure 47 relative to the second direction B is less than that of the third trench structure 43 relative to the second direction B. Based on this, not only can more stress concentration points be avoided in the second pre-cut region 21 with the fifth trench structure 47, reducing the probability of cracks appearing in the solar cell during subsequent processing (e.g., texturing, coating) and use, but also, compared to the third trench structure 43, the fifth trench structure 47 better conforms to the internal stress distribution law of the material, reducing the impact of surface defects caused by trench inclination on the overall performance of the solar cell. Furthermore, compared to the second sub-region 201 with the third trench structure 43, the second pre-cut region 21 with the fifth trench structure 47 is more regular, allowing the chemical solution to act evenly on the second sub-region 201 in subsequent cleaning, texturing, and other processes, improving the processing effect. In addition, the roughness of the second pre-cut region 21 with the fifth trench structure 47 can be made smaller than the roughness of the second sub-region 201 with the third trench structure 43. This can improve the quality of the film layer formed in the second pre-cut region 21 later, thereby improving the battery efficiency.

[0172] In one alternative approach, see Figures 3 to 12The ratio of the total area of ​​the first molten silicon region 40 to the first sub-region 200 is a first value; the ratio of the total area of ​​the second molten silicon region 44 to the second sub-region 201 is a second value; the ratio of the total area of ​​the third molten silicon region 46 to the third pre-cut region 22 is a third value; and the ratio of the total area of ​​the fourth molten silicon region 48 to the second pre-cut region 21 is a fourth value. Wherein, the first value is greater than the second value, the first value is greater than the third value, the first value is greater than the fourth value, the second value is less than the third value, the second value is less than the fourth value, and the third value is less than the fourth value.

[0173] In some embodiments, the ratio of the total area of ​​the first molten silicon region 40 to the first sub-region 200 ranges from 50% to 90%. That is, the first value ranges from 50% to 90%. For example, the first value can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 88%, or 90%, etc. Preferably, the ratio of the total area of ​​the first molten silicon region 40 to the first sub-region 200 ranges from 60% to 80%.

[0174] The ratio of the total area of ​​the second molten silicon region 44 to the second sub-region 201 ranges from 20% to 50%. That is, the second value ranges from 20% to 50%. For example, the second value can be 20%, 25%, 30%, 35%, 40%, 45%, or 50%, etc. Preferably, the ratio of the total area of ​​the second molten silicon region 44 to the second sub-region 201 ranges from 20% to 30%.

[0175] The ratio of the total area of ​​the third molten silicon region 46 to the third pre-cut region 22 ranges from 30% to 50%. That is, the third value ranges from 30% to 50%. For example, the third value can be 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, or 50%, etc. Preferably, the ratio of the total area of ​​the third molten silicon region 46 to the third pre-cut region 22 ranges from 30% to 40%.

[0176] The ratio of the total area of ​​the fourth molten silicon region 48 to the second pre-cut region 21 ranges from 30% to 50%. That is, the fourth value ranges from 30% to 50%. For example, the fourth value can be 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, or 50%, etc. Preferably, the ratio of the total area of ​​the fourth molten silicon region 48 to the second pre-cut region 21 ranges from 30% to 40%.

[0177] As one possible implementation, see Figure 4 Multiple first molten silicon regions 40 are dispersedly distributed in the first sub-region 200.

[0178] In one alternative approach, see Figure 4Multiple first molten silicon regions 40 are distributed in an isolated island-like manner within the first sub-region 200. This island-like distribution of the first molten silicon regions 40 facilitates the reflection of more light through their sidewalls to other areas of the cut surface 11, thereby improving the light-trapping effect of the cut surface 11 of the solar cell, increasing the light absorption rate, and thus improving the utilization rate of light on the side surface of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell. Preferably, the first molten silicon regions 40 are irregular polygons and are uniformly distributed within the first sub-region 200.

[0179] In one alternative approach, see Figure 4 The maximum width distribution of the first molten silicon region 40 is relatively wide, including both smaller and larger regions. The maximum width of a single first molten silicon region 40 is less than 150 μm. This allows for further limitation of the size of the first molten silicon region 40, optimizing light trapping and light absorption efficiency. Preferably, the average maximum width of the first molten silicon region 40 ranges from 10 μm to 150 μm. For example, the average maximum width is 10 μm, 20 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, or 150 μm. The maximum width of the first molten silicon region 40 is the maximum line segment length passing through the first molten silicon region 40.

[0180] See Figure 12 As described above, the battery body 1 includes a first surface 10 and a second surface. When the first surface 10 is the light-receiving surface and the second surface is the backlighting surface, the incident angle of the first surface 10 is made as close to 0 as possible to better utilize light. However, this results in a large incident angle of the incident light on the side surface, for example, close to 90°, leading to low light utilization on the side surface. In this application, the first sub-region 200 includes multiple first molten silicon regions 40, which are irregularly shaped polygons and distributed as isolated islands, resulting in a relatively uniform distribution. This is beneficial for improving the light utilization rate of the side surface of the solar cell. For example, Figure 12 After incident rays F and E pass through the first molten silicon region 40, more light can be reflected to other areas of the first sub-region 200, thereby improving the light utilization efficiency of the side surface of the solar cell. Furthermore, the maximum width of a single first molten silicon region 40 is less than 100 micrometers, and the average maximum width of the first molten silicon regions 40 within the first sub-region 200 is preferably greater than or equal to 10 micrometers and less than or equal to 80 micrometers, which can balance the absorption and trapping effects of light.

[0181] As one possible implementation, see Figure 6 and Figure 8Multiple second molten silicon regions 44 are continuously distributed in the second sub-region 201, multiple third molten silicon regions 46 are continuously distributed in the third pre-cut region 22, and multiple fourth molten silicon regions 48 are continuously distributed in the second pre-cut region 21.

[0182] As one possible implementation, see Figure 4 , Figure 7 and Figure 9 Multiple second molten silicon regions 44 are dispersed in the second sub-region 201, multiple third molten silicon regions 46 are dispersed in the third pre-cut region 22, and multiple fourth molten silicon regions 48 are dispersed in the second pre-cut region 21.

[0183] In one alternative approach, see Figure 4 , Figure 7 and Figure 9 Multiple second molten silicon regions 44 are distributed in an island-like manner in the second sub-region 201. And / or, multiple third molten silicon regions 46 are distributed in an island-like manner in the third pre-cut region 22. And / or, multiple fourth molten silicon regions 48 are distributed in an island-like manner in the second pre-cut region 21.

[0184] For ease of description, the second molten silicon region 44, the third molten silicon region 46, and the fourth molten silicon region 48 are collectively referred to as the molten silicon region, and the second sub-region 201, the third pre-cut region 22, and the second pre-cut region 21 are collectively referred to as the processing region. Multiple molten silicon regions are distributed in an isolated island-like pattern within the processing region. This island-like distribution of molten silicon regions facilitates the reflection of more light through their sidewalls to other areas of the cut surface 11, thereby improving the light-trapping effect of the cut surface 11 of the solar cell, increasing the light absorption rate, and thus improving the light utilization rate of the side surface of the solar cell.

[0185] As one possible implementation, along the thickness direction of the battery body 1, the width of the first molten silicon region 40 is greater than the width of the second molten silicon region 44.

[0186] In one alternative embodiment, the width of the second molten silicon region 44 is 5 μm to 100 μm. Preferably, the average width of the second molten silicon region 44 ranges from 5 μm to 50 μm. For example, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, or 50 μm.

[0187] The width of the third molten silicon region 46 is 3 μm to 60 μm. Preferably, the average width of the third molten silicon region 46 ranges from 5 μm to 40 μm. For example, 3 μm, 5 μm, 10 μm, 20 μm, 30 μm, or 40 μm.

[0188] The width of the fourth molten silicon region 48 is 3 μm to 50 μm. Preferably, the average width of the fourth molten silicon region 48 ranges from 3 μm to 30 μm. For example, 3 μm, 5 μm, 10 μm, 20 μm, or 30 μm.

[0189] As one possible implementation, see Figures 3 to 11 At least one or more of the first molten silicon region 40, the second molten silicon region 44, the third molten silicon region 46, or the fourth molten silicon region 48 have a thickness perpendicular to the cut surface 11.

[0190] In one alternative approach, see Figures 3 to 11 The thickness of the first molten silicon region 40, the second molten silicon region 44, the third molten silicon region 46, and the fourth molten silicon region 48 on the side surface ranges from 20 nm to 300 nm. The thickness of the first molten silicon region 40, the second molten silicon region 44, the third molten silicon region 46, and the fourth molten silicon region 48 is the height difference between the top surface and the cut surface 11.

[0191] As one possible implementation, see Figures 3 to 11 At least one or more of the first molten silicon region 40, the second molten silicon region 44, the third molten silicon region 46, or the fourth molten silicon region 48 include a multilayer structure arranged in a stacked manner. This stacked multilayer structure is beneficial for increasing the scattering of light at the edges of the molten silicon regions. Furthermore, the layers at the edges of at least one or more of the first molten silicon region 40, the second molten silicon region 44, the third molten silicon region 46, or the fourth molten silicon region 48 are staggered.

[0192] As one possible implementation, see Figures 3 to 11 At least one or more of the first molten silicon region 40, the second molten silicon region 44, the third molten silicon region 46, or the fourth molten silicon region 48 include a porous structure. The inclusion of a porous structure in the molten silicon region is more conducive to enhancing the utilization of light.

[0193] As one possible implementation, see Figures 3 to 11 At least one or more of the first molten silicon region 40, the second molten silicon region 44, the third molten silicon region 46, or the fourth molten silicon region 48 include silicon and silicon oxide.

[0194] As one possible implementation, at least one or more of the first trench structure 41, the second trench structure 42, the third trench structure 43, the fourth trench structure 45, or the fifth trench structure 47 extend in any one or more of the following manner: dendritic, straight, zigzag, or curved. The aforementioned trench structures facilitate deeper penetration of light into the side surface of the solar cell and into the cell body 1, thereby improving light utilization efficiency.

[0195] As one possible implementation, the cross-section of at least one or more of the first groove structure 41, the second groove structure 42, the third groove structure 43, the fourth groove structure 45, or the fifth groove structure 47 is any one or more of V-shaped or U-shaped. Further, the bottom and sidewalls of at least one or more of the first groove structure 41, the second groove structure 42, the third groove structure 43, the fourth groove structure 45, or the fifth groove structure 47 can be either relatively flat planar structures or textured surfaces.

[0196] As one possible implementation, the depth of the third trench structure 43 ranges from 0.5 μm to 1.5 μm. Preferably, the depth of the third trench structure 43 ranges from 0.5 μm to 1.2 μm. For example, the depth of the third trench structure 43 is 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, or 1.2 μm.

[0197] The depth of the fourth trench structure 45 ranges from 0.3 μm to 1 μm. Preferably, the depth of the fourth trench structure 45 ranges from 0.3 μm to 0.7 μm. For example, the depth of the fourth trench structure 45 is 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, or 0.7 μm.

[0198] The depth of the fifth trench structure 47 ranges from 0.3 μm to 1 μm. Preferably, the depth of the fifth trench structure 47 ranges from 0.3 μm to 0.7 μm. For example, the depth of the fifth trench structure 47 is 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, or 0.7 μm.

[0199] As one possible implementation, the solar cell also includes a passivation layer, which can be located on the cut surface, the uncut surface, the first surface, and the second surface. Several possible scenarios are described below as examples; it should be understood that these descriptions are for illustrative purposes only and not for specific limitations.

[0200] Example 1: A passivation layer is formed on the cut surface. The passivation layer can saturate the surface dangling bonds generated when the cut surface of the cell body is directly exposed to the air, thereby reducing recombination current and improving the conversion efficiency of the solar cell and the module power.

[0201] Example 2: The passivation layer is formed on the side surface of the battery body (the side surface includes cut surfaces and non-cut surfaces).

[0202] Example 3: Passivation layers are formed on the side surface, the first surface, and the second surface of the battery body, and passivation layers at different locations are formed in the same process. That is, the passivation layer on the side surface is integrally formed with the passivation layers on the first surface and the passivation layer on the second surface and is continuously distributed. When the first surface is the light-receiving surface and the second surface is the backlight surface, the passivation layer on the second surface may only be located within a certain range of the edge of the second surface, for example, within 5 micrometers of the edge of the second surface. At the same time, the average thickness of the passivation layer located on the side surface is less than the average thickness of the passivation layer located on the first surface.

[0203] Example 3: The passivation layer of the above-mentioned solar cell includes a first passivation layer and a second passivation layer. The first passivation layer includes a portion located on a first surface or a second surface, and the second passivation layer includes a portion located on a cut surface. The average thickness of the second passivation layer located on the cut surface is greater than the average thickness of the first passivation layer located on the first surface or the second surface.

[0204] Example 4: The passivation layer of the aforementioned solar cell includes a first passivation layer and a second passivation layer. The first passivation layer includes portions located on a first surface and / or a second surface, and the second passivation layer includes portions located on a cut surface, wherein the average thickness of the second passivation layer located on the cut surface is greater than the average thickness of the first passivation layer located on the first surface or the second surface. The second passivation layer also includes portions located at the edge of the first surface and above the first passivation layer, with the edge of the first surface close to the cut surface. And / or, the second passivation layer also includes portions located at the edge of the second surface and above the first passivation layer, with the edge of the second surface close to the cut surface.

[0205] For example, the passivation layer of the aforementioned solar cell includes a first passivation layer and a second passivation layer. The first passivation layer includes portions located on a first surface and / or a second surface. The second passivation layer includes portions located on a cut surface and portions located within a certain range on the first surface and / or the second surface near the edge of the cut surface. Within a certain range on the first surface and / or the second surface near the edge of the cut surface, the second passivation layer covers the first passivation layer to achieve a stacked structure of the first and second passivation layers. The first and second passivation layers can be formed in different process steps. Since the cut surface includes a molten silicon region, the second passivation layer covering the cut surface can be formed in a separate step, thereby better meeting the passivation requirements of the cut surface. Preferably, the average thickness of the second passivation layer located on the cut surface is greater than the average thickness of the first passivation layer located on the first surface or the second surface. Further, the average thickness of the second passivation layer located at the edge of the first surface is less than the average thickness of the second passivation layer located on the cut surface. And / or, the average thickness of the second passivation layer located at the edge of the second surface is less than the average thickness of the second passivation layer located on the cut surface.

[0206] In some embodiments, for at least one or more of the four examples described above, along the second direction, the cutting surface includes a cutting edge and a fracture edge, and the pre-cut region and the thermal crack region are disposed near the cutting edge. The thickness of the passivation layer near the cutting edge is greater than the thickness of the passivation layer near the fracture edge.

[0207] In some embodiments, for at least one or more of the four examples described above, the average thickness of the passivation layer ranges from 10 nm to 120 nm. For example, the average thickness of the passivation layer may be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, or 120 nm, etc.

[0208] The passivation layer is made of at least one or more of the following materials: aluminum oxide, silicon nitride, silicon oxide, silicon oxynitride, intrinsic amorphous silicon, intrinsic microcrystalline silicon, doped amorphous silicon, or doped microcrystalline silicon.

[0209] The passivation layer can be a single-layer film or a stack of multiple films. For example, the passivation layer can be a stack of aluminum oxide and silicon nitride layers, or a stack of silicon nitride and silicon oxide layers, or a stack of silicon oxynitride and intrinsic amorphous silicon layers, or the passivation layer can be an aluminum oxide layer, or the passivation layer can be a silicon oxynitride layer. It should be noted that the materials and structures of the first passivation layer and the second passivation layer can be the same or different.

[0210] Secondly, this application also provides a photovoltaic module. The photovoltaic module includes a cell string and an encapsulation layer. The cell string includes multiple interconnects and multiple solar cells as described in the above technical solutions. The interconnects are used to electrically connect the multiple solar cells together to form the cell string, and the encapsulation layer is used to cover the surface of the cell string.

[0211] The beneficial effects of the photovoltaic modules provided in this application are the same as those of the solar cells described in the above technical solutions, and will not be repeated here.

[0212] The interconnecting element described above can be a solder ribbon or other connector used to connect solar cells. When the interconnecting element is a solder ribbon, the solder ribbon can have a circular, triangular, or rectangular cross-section. Preferably, a solder ribbon with a circular cross-section is used. This can help cope with the mechanical stress at the solar cell connection, eliminate the microcrack problem in high-density solar modules, and improve the reliability of the solar modules.

[0213] The solar cells provided in this application may be solar cells that only include tunneling passivation contact structures, solar cells that only include heterostructures, or hybrid solar cells that include both tunneling passivation contact structures and heterostructures. For example, the solar cells provided in this application may be Topcon cells, BC cells, TBC cells, or heterojunction solar cells.

[0214] Thirdly, this application also provides a method for manufacturing a solar cell. See [link to application]. Figures 1 to 12 The method for manufacturing this solar cell includes: First, a battery body 1 is provided, which includes a first surface 10 and a second surface. A description of the battery body 1 can be found in the first aspect and will not be repeated here.

[0215] Next, the first surface 10 is processed using a first laser process to create a plurality of guide grooves on the first surface 10; the guide grooves extend along a first direction A, and the plurality of guide grooves are spaced apart along the first direction A.

[0216] For example, the first laser process described above uses a destructive laser. The groove formed on the battery body 1 by the destructive laser cutting is used as a guide groove, which is beneficial for the subsequent segmentation of the battery body 5 along the guide groove, so as to ensure that the shape of the segmented battery body 5 meets the actual requirements.

[0217] For example, the first laser process uses a nanosecond laser. The pulse width of a nanosecond laser is 1 nanosecond (10^6 Hz). -9 The time interval is between several nanoseconds and several hundred nanoseconds. For example, a nanosecond laser is used in the laser, and the laser is applied to the battery body 1 in a pulsed manner to create a guide groove by vaporizing part of the battery body 1.

[0218] In some embodiments, the width of the guide groove along a third direction ranges from 10 μm to 50 μm. For example, the width of the guide groove can be 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm, 28 μm, 30 μm, 32 μm, 35 μm, 38 μm, 40 μm, 42 μm, 45 μm, 48 μm, or 50 μm, etc. A guide groove width greater than or equal to 10 μm facilitates the cutting of the dicing fragment. A guide groove width less than or equal to 50 μm can prevent excessive cutting damage.

[0219] For details regarding the length and depth of the guide groove, please refer to the first aspect; they will not be repeated here.

[0220] In some embodiments, the cross-sectional shape of the guide groove can be rectangular, circular, or elliptical, etc. Multiple guide grooves may have the same shape and different dimensions.

[0221] Next, the first surface 10 is heat-treated along the first direction A using a second laser process, forming a heat treatment path.

[0222] For example, the second laser process employs a non-destructive thermal cracking laser. This non-destructive thermal cracking laser acts on the portion of the battery body 1 located in the middle of the guide groove, reducing damage to the battery body 1. For the non-destructive thermal cracking laser, a nanosecond continuous laser is used to heat the battery body 1.

[0223] In some embodiments, the laser intensity of the first laser process is greater than that of the second laser process. In this application, no molten silicon region is formed on the cut surface 11 of the slab battery body 5 formed after processing with the second laser process.

[0224] Next, along the heat treatment path, the first laser process and the second laser process are alternately used to divide the battery body 1 into at least two segmented battery bodies 5. For example, after heat treatment paths and multiple guide grooves are formed on the first surface 10 of the battery body 1, water is sprayed onto the battery body 1. At this time, the battery body 1 naturally cracks or cracks with the help of physical and mechanical means to form at least two segmented battery bodies 5.

[0225] In some embodiments, the width of the heat treatment path along a third direction ranges from 500 μm to 2000 μm. For example, the width of the heat treatment path can be 500 μm, 560 μm, 570 μm, 580 μm, 590 μm, 600 μm, 620 μm, 650 μm, 680 μm, 700 μm, 720 μm, 750 μm, 780 μm, 800 μm, 820 μm, 850 μm, 880 μm, 900 μm, 920 μm, 950 μm, 980 μm, 1000 μm, 1100 μm, 1200 μm, 1300 μm, 1400 μm, 1500 μm, 1600 μm, 1700 μm, 1800 μm, 1900 μm, or 2000 μm, etc.

[0226] In some embodiments, the segmented battery body 5 includes a first surface 10 and a second surface opposite to each other, and a side surface connecting the first surface 10 and the second surface, the side surface including a cutting surface 11. Along a first direction A, the cutting surface 11 includes a pre-cut region and a thermally cracked region, the thermally cracked region being located between two adjacent pre-cut regions. The pre-cut region corresponds to a guide groove, and the thermally cracked region is located in the heat treatment path. Along the first direction A, the battery body 1 includes a first end and a second end opposite to each other, the pre-cut region including a first pre-cut region 20 near the first end of the battery body 1, a second pre-cut region 21 near the second end of the battery body 1, and at least one third pre-cut region 22 located between the first pre-cut region 20 and the second pre-cut region 21. Along a second direction B, the thickness of the pre-cut region is greater than the thickness of the thermally cracked region. The first direction A and the second direction B are parallel to the cutting surface 11, the third direction is perpendicular to the cutting surface 11, the second direction B is the thickness direction of the battery body 1, and the first direction A is perpendicular to the second direction B.

[0227] Based on the preceding description, the cross-sectional shape of the guide groove can be rectangular, circular, or elliptical, etc. Since the pre-cut areas correspond to the guide grooves, in some embodiments, the first pre-cut area 20 and the second pre-cut area 21 have rectangular cross-sectional shapes, and the third pre-cut area 22 has a circular cross-sectional shape. In other words, the first pre-cut area 20 and the second pre-cut area 21 are linear, and the third pre-cut area 22 is dot-shaped. Alternatively, the cross-sectional shapes of the first pre-cut area 20, the second pre-cut area 21, and the third pre-cut area 22 are all rectangular.

[0228] It should be noted that a detailed description of the pre-cut area and the thermal cracking area can be found in the first aspect, and will not be repeated here.

[0229] In the method for manufacturing a solar cell provided in this application, the cut surface 11 includes a pre-cut area and a thermally cracked area. The pre-cut area corresponds to a guide groove opened by a laser (i.e., a laser-destructive cutting area). The pre-cut area includes at least three pre-cut areas located at different positions, and the thermally cracked area is located between two adjacent pre-cut areas. In this application, the guiding effect of the pre-cut area is not weakened due to the large length or width of the original solar cell, thus ensuring the morphology of the cut surface 11 of the obtained diced solar cells, thereby improving cell efficiency. Furthermore, along the second direction B, the thickness of the pre-cut area is greater than the thickness of the thermally cracked area. This ensures a greater guiding effect of the pre-cut area, reducing or avoiding the pulling force of the guiding force and the thermal force, thus preventing unevenness of the cut surface 11 due to pulling.

[0230] As one possible implementation, the method for manufacturing solar cells also includes: cleaning the cut surfaces 11 of the cell body 5 to remove damage. This removes the laser-damaged layer caused by the first laser cutting process, thereby reducing lattice defects.

[0231] For example, in a chain cleaning machine, the slab-type cell body 5 is placed in an HF and HNO3 tank, and a cleaning mode using rollers carrying liquid or water floating is used to remove some of the silicon slag and silicon oxide from the cut surfaces 11 of the slab-type cell body 5. Since the cut surfaces 11 are not protected by a phosphosilicate glass layer, the concentration of HF and HNO3 is increased to enhance the corrosion of the cut surfaces 11, thereby increasing the cleaning of the cut surfaces 11. This makes the cut surfaces 11 smoother than those in the prior art, and the cleaning effect of the cut surfaces 11 is similar to that of other surfaces of the slab-type cell body 5. Next, during the tank cleaning process, the ratio of alkaline texturing to additives is adjusted to texturize and etch the cut surfaces 11, making the texturing effect similar on all surfaces of the slab-type cell body 5. This improves the passivation effect of the solar cell after the passivation layer is formed on the slab-type cell body 5.

[0232] After cleaning the damaged cut surface 11 of the cell body 5, the method for preparing the solar cell further includes forming at least a passivation layer on the cut surface 11.

[0233] This enhances the passivation effect of the solar cell, thereby improving its photoelectric conversion efficiency. Furthermore, since a passivation layer is formed on the cut surfaces 11 of the cell body 5 after cleaning, the surface dangling bonds generated when the cut surfaces 11 are directly exposed to air can be saturated. Based on this, the minority carrier lifetime of the cut surfaces 11 can be increased, reducing recombination current and thus improving the conversion efficiency and module power of the solar cell.

[0234] In some embodiments, the passivation layer is made of at least one or more of the following materials: aluminum oxide, silicon nitride, silicon oxide, silicon oxynitride, intrinsic amorphous silicon, intrinsic microcrystalline silicon, doped amorphous silicon, or doped microcrystalline silicon. Further, the passivation layer can be a single-layer film or a stack of multiple films.

[0235] For example, the passivation layer can be a stack of aluminum oxide and silicon nitride. The stacked aluminum oxide and silicon nitride layers can passivate the cut surface 11, reduce the recombination rate of charge carriers at the cut surface 11, and further improve the photoelectric conversion efficiency of the solar cell. Furthermore, the silicon nitride layer can play an anti-reflection role, which helps to refract more light from the cut surface 11 into the cell body 1, thereby further improving the light utilization rate of the solar cell.

[0236] The following description uses the fabrication process of two types of solar cells as examples to illustrate the position of the "slicing" step described above. It should be understood that the following description is for comprehension purposes only and is not intended to limit the specific application of the technology.

[0237] The first category concerns TOPCon batteries. The manufacturing process of TOPCon batteries includes: S1 provides a semiconductor substrate; S2, Cleaning and texturing the semiconductor substrate; S3, perform boron diffusion and etching processes on the textured semiconductor substrate to form a PN junction on the light-receiving side of the semiconductor substrate; S4, Polish the back surface of the semiconductor substrate to remove the diffusion layer on the back surface of the semiconductor substrate; S5, a tunneling oxide layer and a doped polysilicon layer are sequentially formed on the back surface of the semiconductor substrate; S6, perform a cleaning process on the semiconductor substrate to remove the PSG layer on the light-receiving surface and the side of the semiconductor substrate, as well as the BSG layer on the light-receiving surface and the PSG layer on the backlight surface. S7, A passivation and antireflection layer is formed on the surface of the structure formed in the above steps.

[0238] The "slicing" step described above can be located anywhere between S1 and S6, for example, after S1 and before S2, or after S2 and before S3, or after S3 and before S4, or after S4 and before S5, or after S5 and before S6. After the slicing is completed, the solar cell described in the first aspect of this application can be obtained by controlling the cleaning solution, process parameters, etc., in step S6. Alternatively, in another case, the semiconductor substrate provided in step S1 is already a pre-sliced ​​semiconductor substrate, for example, it has already undergone slicing before entering the cell production process.

[0239] The second category is for BC batteries. The manufacturing process of the first type of BC battery includes: S1, a semiconductor substrate is provided, the semiconductor substrate including opposing first and second surfaces; S2, Cleaning process for semiconductor substrate; S3, a first doped semiconductor material layer is formed on the second surface in an integral layer; S4, pattern the first doped semiconductor material layer to form the first doped semiconductor layer on a portion of the second surface; S5, a second doped semiconductor material layer is formed on the second surface in an integral layer; S6, pattern the second doped semiconductor material layer so that the first doped semiconductor layer and the second doped semiconductor layer are arranged alternately. S7, Cleaning and / or texturing the semiconductor substrate; S8, a passivation antireflection layer is formed on the first surface of the semiconductor substrate, the first doped semiconductor material layer, and the second doped semiconductor material layer.

[0240] The "slicing" step described above can be located anywhere between S1 and S7, for example, after S1 and before S2, or after S2 and before S3, or after S3 and before S4, or after S4 and before S5, or after S5 and before S6, or after S5 and before S6, or after S6 and before S7. After the slicing is completed, the solar cell described in the first aspect of this application can be obtained by controlling the chemical solution, process parameters, etc. in step S7. Alternatively, in another case, the semiconductor substrate provided in step S1 is already a pre-sliced ​​semiconductor substrate, for example, it has already been sliced ​​before entering the cell production process.

[0241] The manufacturing process of the second type of BC battery includes: S1, a semiconductor substrate is provided, the semiconductor substrate including opposing first and second surfaces; S2, Cleaning process for semiconductor substrate; S3, a first doped semiconductor material layer is formed on the second surface in an integral layer; S4, pattern the first doped semiconductor material layer to form the first doped semiconductor layer on a portion of the semiconductor substrate; S5, Cleaning and / or texturing the semiconductor substrate; S6, a passivation antireflection layer is formed on the first surface of the semiconductor substrate, the first doped semiconductor material layer, and the second surface of the semiconductor substrate in the region exposed outside the first doped semiconductor layer.

[0242] The "slicing" step described above can be located anywhere between S1 and S5, for example, after S1 and before S2, or after S2 and before S3, or after S3 and before S4, or after S4 and before S5. After the slicing is completed, the solar cell described in the first aspect of this application can be obtained by controlling the chemical solution, process parameters, etc. in step S5. Alternatively, in another case, the semiconductor substrate provided in step S1 is already a pre-sliced ​​semiconductor substrate, for example, it has already undergone slicing before entering the cell production process.

[0243] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0244] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A solar cell, characterized in that, The solar cell includes a cell body, the cell body includes opposing first and second surfaces, and a side surface connecting the first and second surfaces, the side surface including a cut surface; Along the first direction, the cutting surface includes a pre-cut area and a thermal cracking area, the thermal cracking area being located between two adjacent pre-cut areas; along the first direction, the battery body includes a first end and a second end opposite to each other, the pre-cut area including a first pre-cut area near the first end of the battery body, a second pre-cut area near the second end of the battery body, and at least one third pre-cut area located between the first pre-cut area and the second pre-cut area; Wherein, along the second direction, the thickness of the pre-cut region is greater than the thickness of the thermally cracked region; the first direction and the second direction are parallel to the cutting surface, the third direction is perpendicular to the cutting surface, the second direction is the thickness direction of the battery body, and the first direction is perpendicular to the second direction; The ratio of the thickness of the pre-cut region to the thickness of the battery body is 0.2-0.8; The ratio of the thickness of the thermally cracked region to the thickness of the battery body is 0.01-0.15; Both the first pre-cutting area and the second pre-cutting area include molten silicon areas, wherein the area ratio of the molten silicon area in the first pre-cutting area is greater than the area ratio of the molten silicon area in the second pre-cutting area; The third pre-cut region includes a molten silicon region, and the area ratio of the molten silicon region in the first pre-cut region is greater than the area ratio of the molten silicon region in the third pre-cut region; The cutting surface includes a groove structure, the groove structure located in the first pre-cutting area has a first depth, the groove structure located in the second pre-cutting area has a second depth, the groove structure located in the third pre-cutting area has a third depth, and the groove structure located in the hot cracking area has a fourth depth. Wherein, the first depth is greater than the second depth; And / or, the first depth is greater than the third depth; And / or, the first depth is greater than the fourth depth; And / or, the second depth is greater than the fourth depth; And / or, the third depth is greater than the fourth depth.

2. The solar cell according to claim 1, characterized in that, The lengths of the first pre-cut area, the second pre-cut area, and the third pre-cut area are all in the range of 0.5mm-5mm; And / or, the ratio of the length of the first pre-cut region, the second pre-cut region, and the third pre-cut region to the length of the battery body in the first direction is 0.5% to 5%; And / or, the distance between two adjacent pre-cut areas is 10mm-100mm; And / or, the number of the third pre-cut regions is 1-10; The length direction of the pre-cut region and the length direction of the thermal cracking region are consistent with the first direction.

3. The solar cell according to claim 1, characterized in that, Along the second direction, The thickness of the pre-cut area ranges from 30μm to 140μm; And / or, the thickness of the hot-cracked region ranges from 2 μm to 20 μm; And / or, the ratio of the thickness of the hot-cracked region to the thickness of the pre-cut region is 0.05-0.

5.

4. The solar cell according to claim 1, characterized in that, Along the first direction, The length of the pre-cut region is less than the length of the thermal cracking region; And / or, the length of the first pre-cut region is greater than the length of the third pre-cut region; And / or, along the first direction, the length of the third pre-cut region is greater than or equal to the length of the second pre-cut region; The length directions of the first pre-cut region, the second pre-cut region, the third pre-cut region, and the thermal cracking region are consistent with the first direction.

5. The solar cell according to claim 1, characterized in that, Along the direction from the first end to the second end, the first pre-cut area sequentially includes a first sub-region, a second sub-region, and a third sub-region; the first sub-region includes multiple first molten silicon regions; the cutting surface includes a first trench structure and a second trench structure, the first trench structure is located in the third sub-region, and the second trench structure is located in the thermal cracking region; Along the third direction, the depth of the second trench structure is less than the depth of the first trench structure.

6. The solar cell according to claim 5, characterized in that, The cut surface also includes a third groove structure, which is located in the second sub-region; The second sub-region includes a plurality of second molten silicon regions; the second molten silicon regions are distributed between the edge near the first surface and the third trench structure.

7. The solar cell according to claim 6, characterized in that, Along the second direction, the cut surface having the third trench structure sequentially includes a first region, a second region, and a third region, wherein the first region is located between the second region and the second molten silicon region; Along the third direction, the depth of the third trench structure located in the first region and the depth of the third trench structure located in the third region are both greater than or equal to the depth of the third trench structure located in the second region.

8. The solar cell according to claim 5, characterized in that, The cut surface also includes a third groove structure, which is located in the second sub-region; Along the third direction, the depth of the third trench structure is less than the depth of the first trench structure; And / or, the depth of the third trench structure is greater than the depth of the second trench structure; And / or, the slope of the third trench structure is less than the slope of the second trench structure; And / or, the acute angle formed by the tangent of the point in the first trench structure closest to the first surface and the first surface is α, and the acute angle formed by the tangent of the intersection of the second trench structure and the first surface and the first surface is β, where α < β. And / or, the acute angle formed by the tangent of the point near the first surface in the first trench structure and the first surface is α, and the acute angle formed by the tangent of the point near the first surface in the third trench structure and the first surface is γ, where α < γ.

9. The solar cell according to claim 5, characterized in that, Along the first direction: the ratio of the length of the first sub-region to the length of the battery body is 0.02% to 0.2%, the ratio of the length of the second sub-region to the length of the battery body is 0.1% to 0.5%, and the ratio of the length of the third sub-region to the length of the battery body is 0.2% to 1%. And / or, along the first direction: the length of the first sub-region ranges from 50 μm to 300 μm, the length of the second sub-region ranges from 200 μm to 800 μm, and the length of the third sub-region ranges from 400 μm to 2000 μm; And / or, along the first direction: the ratio of the length of the first sub-region to the length of the first pre-cut region is 5% to 20%, the ratio of the length of the second sub-region to the length of the first pre-cut region is 10% to 40%, and the ratio of the length of the third sub-region to the length of the first pre-cut region is 30% to 80%; The length directions of the first sub-region, the second sub-region, and the third sub-region are consistent with the first direction.

10. The solar cell according to claim 5, characterized in that, Along the second direction, the third sub-region includes a fourth region adjacent to the first surface and a fifth region further away from the first surface than the fourth region; The cut surface also includes a crack structure located in the fourth region; the first groove structure is located in the fifth region.

11. The solar cell according to claim 10, characterized in that, Along the third direction, the depth of the crack structure is greater than the depth of the first groove structure.

12. The solar cell according to claim 1, characterized in that, The cutting surface includes a second groove structure, which is located in the hot crack region; Along the second direction, the cut surface having the second groove structure sequentially includes an edge region and a middle region, with the middle region located between the edge regions; Along the third direction, the depth of the second trench structure located in the edge region is greater than or equal to the depth of the second trench structure located in the middle region.

13. The solar cell according to claim 1, characterized in that, The hot-cracked region includes a molten silicon region, and the ratio of the area of ​​the molten silicon region to the area of ​​the hot-cracked region is 0.01%-5%.

14. The solar cell according to claim 1, characterized in that, Along the direction from the first end to the second end, the thermal cracking region sequentially includes a first sub-thermal cracking region and a second sub-thermal cracking region; The cutting surface includes a second groove structure located in the hot cracking region. The second groove structure located in the first sub-hot cracking region has two different tilt directions, and the second groove structures with the two different tilt directions intersect each other.

15. The solar cell according to claim 5, characterized in that, Along the direction from the first end to the second end, the thermal cracking region sequentially includes a first sub-thermal cracking region and a second sub-thermal cracking region; The acute angle formed by the tangent at the intersection of the second groove structure and the first surface within the first sub-thermal cracking region and the first surface is β1, and the acute angle formed by the tangent at the intersection of the second groove structure and the first surface within the second sub-thermal cracking region and the first surface is β2, where β1 > β2. And / or, along the third direction, the depth of the second groove structure located within the first sub-thermal cracking region is less than the depth of the second groove structure located within the second sub-thermal cracking region.

16. The solar cell according to claim 6, characterized in that, The cutting surface includes a fourth groove structure, which is located in the third pre-cut area; The third pre-cut region also includes multiple third molten silicon regions, which are distributed between the first surface and the fourth trench structure.

17. The solar cell according to claim 16, characterized in that, The depth of the fourth trench structure is greater than the depth of the third trench structure; The acute angle between the tangent line at the point closest to the first surface in the third groove structure and the first surface is γ, and the acute angle between the tangent line at the intersection of the fourth groove structure and the first surface and the first surface is θ, where γ < θ.

18. The solar cell according to claim 6, characterized in that, The cutting surface includes a fifth groove structure, which is located in the second pre-cut area; The second pre-cut area also includes a plurality of fourth molten silicon regions; the fourth molten silicon regions are distributed between the first surface and the fifth trench structure.

19. The solar cell according to claim 18, characterized in that, The depth of the fifth trench structure is greater than the depth of the third trench structure; The acute angle between the tangent line at the point closest to the first surface in the third groove structure and the first surface is γ, and the acute angle between the tangent line at the intersection of the fifth groove structure and the first surface and the first surface is η, where γ < η.

20. The solar cell according to claim 1, characterized in that, The solar cell further includes a passivation layer; the passivation layer is formed at least on the cut surface; The average thickness of the passivation layer ranges from 10 nm to 120 nm.

21. The solar cell according to claim 20, characterized in that, The passivation layer is made of at least one or more of the following materials: aluminum oxide, silicon nitride, silicon oxide, silicon oxynitride, intrinsic amorphous silicon, intrinsic microcrystalline silicon, doped amorphous silicon, or doped microcrystalline silicon.

22. The solar cell according to claim 20, characterized in that, Along the second direction, the cutting surface includes a cutting edge and a fracture edge, and the pre-cut area and the hot cracking area are disposed close to the cutting edge; The thickness of the passivation layer near the cutting edge is greater than the thickness of the passivation layer near the fracture edge.

23. A photovoltaic module, characterized in that, include: A battery string, the battery string comprising a plurality of interconnecting elements and a plurality of solar cells as described in any one of claims 1 to 22; The interconnecting element is used to electrically connect multiple solar cells together to form the battery string; An encapsulation layer is used to cover the surface of the battery string.

Images