Solar cell and photovoltaic module

Abstract

The present application relates to the technical field of photovoltaics. Provided are a solar cell and a photovoltaic module. The solar cell comprises a silicon substrate, the surface of the silicon substrate being provided with a textured structure, the textured structure comprising a plurality of pyramid-like structures. Each pyramid-like structure comprises an apex, a conical surface and at least two side edges, wherein each side edge comprises a lower section far away from the apex, and a first section which is the remaining portion of said side edge other than the lower section, the degree of bending of the lower section being less than that of the first section. In the embodiments of the present application, each side edge comprises a lower section far away from the apex, and a first section, the degree of bending of the lower section being less than that of the first section; thus, the conical surface of each pyramid-like structure has a more irregular shape, such that the textured structure has a larger specific surface area, which leads to lower reflectivity and better light trapping effect, thereby increasing the short-circuit current and ultimately improving the photoelectric conversion efficiency of the solar cell; in addition, the solar cell has a uniform black appearance that is more aesthetically pleasing.

Description

Solar cell and photovoltaic module

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to a Chinese patent application filed with the Patent Office of China on February 7, 2024, with application number 202410175554.9 and titled “A Solar Cell and Photovoltaic Module,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of photovoltaic technology, and in particular to a solar cell and a photovoltaic module. Background Art

[0004] Solar cells can convert solar energy into electrical energy. They utilize clean energy and therefore have broad application prospects.

[0005] Solar cells are often equipped with a velvet structure to enhance light trapping. However, in existing solar cells, the velvet structure has a poor light trapping effect, which reduces the performance of the solar cell.

[0006] Summary of the Invention

[0007] The present application provides a solar cell and a photovoltaic module, aiming to solve the problem of poor light trapping effect of the velvet structure in existing solar cells.

[0008] In a first aspect of the present application, a solar cell is provided, comprising: a silicon substrate, wherein the surface of the silicon substrate has a velvet structure, the velvet structure comprises: a plurality of pyramid-like structures; the pyramid-like structures comprise: a cone top, a cone surface, and at least two side edges;

[0009] The side edge includes: a lower section away from the cone top, and a first section. The first section is the rest of the side edge except the lower section. The bending degree of the lower section is smaller than that of the first section.

[0010] In an embodiment of the present application, the side edge includes: a lower section away from the top of the cone, and a first section. The bending degree of the lower section is smaller than that of the first section. The first section is the remaining part of the side edge except the lower section. The first section is closer to the top of the cone than the lower section. In this way, the cone surface shape of this type of pyramid structure is more irregular, so that the velvet structure has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. The appearance of the solar cell is uniform black, which is more beautiful.

[0011] Optionally, the conical surface has a branched texture, and the conical surface of the pyramid-like structure includes: a first sub-conical surface away from the top of the cone, and a second sub-conical surface, the second sub-conical surface being the remaining part of the conical surface of the pyramid-like structure except the first sub-conical surface; the number of branched textures in the second sub-conical surface is more than the number of branched textures in the first sub-conical surface.

[0012] Optionally, in the velvet structure, at least the lower portions of at least two pyramid-like structures away from the cone tops are fused into one, and the cone tops of the fused pyramid-like structures are separated.

[0013] Optionally, the cone tops of the integrated pyramid-like structures have height differences or are evenly distributed.

[0014] Optionally, in each integrated pyramid-like structure, a height difference between cone tops of two pyramid-like structures is greater than 0 and less than or equal to 1.6 micrometers.

[0015] Optionally, in the same type of pyramid structure, of the two side edges located on both sides of the pyramid top, along the direction of the thickness of the silicon substrate, the size of one side edge is larger than the size of the other side edge.

[0016] Optionally, the lower segment is a straight line segment, or a line segment with at most two inflection points; and the first segment is a broken line segment and / or a curved line segment.

[0017] Optionally, the length of the lower section is at least 1 / 10 of the length of the side edge.

[0018] Optionally, the angle between the lower section and the first plane is smaller than the angle between the first section and the first plane; the first plane is a plane perpendicular to the thickness direction of the silicon substrate.

[0019] Optionally, the first section consists of an upper section and a middle section, the upper section is adjacent to the top of the cone, and the middle section is located between the lower section and the upper section; the length of the upper section is at least 1 / 10 of the length of the side edge, and the length of the middle section is at least 2 / 5 of the length of the side edge.

[0020] Optionally, the angle between the lower section and the first plane is 50° to 55°, the angle between the upper section and the first plane is 55° to 80°, and the angle between the middle section and the first plane is 55° to 85°.

[0021] Optionally, the light-facing surface and / or the backlight surface of the silicon substrate has a suede structure.

[0022] In a second aspect of the present application, a solar cell is provided, comprising a silicon substrate having a velvet structure on its surface, the velvet structure comprising: a plurality of pyramid-like structures; the pyramid-like structures comprising: a cone surface and a cone top; the cone surface of the pyramid-like structure comprising: a first sub-cone surface away from the cone top, and a second sub-cone surface, the second sub-cone surface being the remaining portion of the cone surface of the pyramid-like structure excluding the first sub-cone surface;

[0023] The cone top of the pyramid-like structure and the second sub-cone surface of the cone surface of the pyramid-like structure have a cluster of nested ring-like textures.

[0024] In this application, the ring-like texture can increase the specific surface area, so that the velvet structure has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. The appearance of the solar cell is uniform black, which is more beautiful.

[0025] Optionally, in the velvet structure, at least first sub-cone surfaces of at least two pyramid-like structures are fused into one, and the cone tops of the fused pyramid-like structures are separated.

[0026] Optionally, in each integrated pyramid-like structure, the annular-like textures in the cone surfaces of different pyramid-like structures are distributed separately;

[0027] Alternatively, in the integrated pyramid-like structures, the annular textures in the cone surfaces of different pyramid-like structures partially overlap.

[0028] Optionally, in a cluster of quasi-annular textures, the quasi-annular textures at different positions are distributed overlappingly along the height direction of the quasi-pyramid structure.

[0029] Optionally, in the cone surface of the pyramid-like structure, the ring-like texture extends from a position adjacent to the cone top to a cone surface position corresponding to a portion of the pyramid-like structure whose height difference from the cone top is 2 / 3 of the height of the pyramid-like structure.

[0030] Optionally, the portion of the pyramid-like structure away from the top of the pyramid is the lower portion of the pyramid-like structure, and the height of the lower portion accounts for at least 1 / 10 of the height of the pyramid-like structure;

[0031] The first sub-cone surface is: the area corresponding to the lower part of the cone surface of the pyramid-like structure;

[0032] The second sub-cone surface is an area of ​​the cone surface of the pyramid-like structure that is closer to the cone top than the first sub-cone surface.

[0033] A third aspect of the present application provides a solar cell, comprising: a silicon substrate, wherein the surface of the silicon substrate has a velvet structure, the velvet structure comprises: a plurality of pyramid-like structures; the pyramid-like structures comprise: a cone surface and a cone top;

[0034] The cone top and the cone surface of the pyramid-like structure have: a skirt-like texture and / or a rose-like texture.

[0035] In the present application, the skirt-shaped texture and / or rose-shaped texture can increase the specific surface area, so that the velvet structure has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. The appearance of the solar cell is uniform black, which is more beautiful.

[0036] Optionally, the cone surface of the pyramid-like structure includes: a first sub-cone surface away from the cone top, and a second sub-cone surface, wherein the second sub-cone surface is the remaining portion of the cone surface of the pyramid-like structure except the first sub-cone surface;

[0037] The skirt-shaped texture and / or the rose-shaped texture are located in the cone top and the second sub-cone surface of the pyramid-like structure.

[0038] Optionally, the portion of the pyramid-like structure away from the top of the pyramid is the lower portion of the pyramid-like structure, and the height of the lower portion accounts for at least 1 / 10 of the height of the pyramid-like structure;

[0039] The first sub-cone surface is: the area corresponding to the lower part of the cone surface of the pyramid-like structure;

[0040] The second sub-cone surface is an area of ​​the cone surface of the pyramid-like structure that is closer to the cone top than the first sub-cone surface.

[0041] In a fourth aspect of the present application, a photovoltaic assembly is provided, comprising: a plurality of any of the aforementioned solar cells.

[0042] The above-mentioned solar cells and photovoltaic modules have the same or similar beneficial effects, and will not be described again here to avoid repetition. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0044] FIG1 shows a scanning electron microscope image of a first silicon substrate in an embodiment of the present application;

[0045] FIG2 shows a scanning electron microscope image of a second silicon substrate in an embodiment of the present application;

[0046] FIG3 shows a schematic diagram of a partial structure of a solar cell in an embodiment of the present application;

[0047] FIG4 shows a scanning electron microscope image of a third silicon substrate in an embodiment of the present application;

[0048] FIG5 shows a scanning electron microscope image of a fourth silicon substrate in an embodiment of the present application;

[0049] FIG6 shows a comparison of the reflectivity of the solar cell in the embodiment of the present application and the solar cell in the comparative example.

[0050] Explanation of reference numerals: 1-silicon substrate, 2-passivation anti-reflection layer, 11-cone top, 12-branched texture, 13-quasi-ring texture, 131-spike, 14-bottom contour line, 15-integrated pyramid-like structures. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0052] Figures 1, 2, and 5 are all SEM images obtained by scanning from the front of the velvet structure. Figure 4 is a SEM image obtained by scanning from the top of the pyramid-like structure of the velvet structure to the bottom contour line.

[0053] 1 to 5 , the present application provides a solar cell comprising: a silicon substrate 1. The silicon substrate 1 may have doped elements or be intrinsic, which is not specifically limited. The silicon substrate 1 may be a single crystal silicon substrate, etc., which is also not specifically limited. In FIG3 , the dotted lines L1 to L6 do not actually exist in the solar cell, but are merely markings used to distinguish between the first sub-cone surface and the second sub-cone surface, or to distinguish between the lower section and the first section described below.

[0054] 1 to 5 , the surface of the silicon substrate 1 has a velvet structure, and the velvet structure includes: a plurality of pyramid-like structures. For example, in FIG1 , the black lines outline the three pyramid-like structures in the velvet structure. The pyramid-like structure includes: a cone surface, a cone top 11 and at least two side edges. The cone top 11 is the highest point in the pyramid-like structure. In the case where the highest part of the pyramid-like structure is a plane formed by a plurality of points of equal height, the cone top here can be the geometric center of the plane. In the pyramid-like structure, the cone surface of the pyramid-like structure is the set of all side surfaces of the pyramid-like structure, that is, all surfaces of the pyramid-like structure except the bottom surface and the cone top. The cone surface of the pyramid-like structure connects the cone top and the bottom contour line, and the bottom contour line is the lowest contour line of the pyramid-like structure. The side edges of the pyramid-like structure are the common edges of adjacent side surfaces in the pyramid-like structure.

[0055] The side edge includes: a lower segment away from the cone top 11, and a first segment, which is the portion of the side edge excluding the lower segment. Here, the bending degree of the lower segment is smaller than that of the first segment. The bending degree of a sub-segment of the side edge refers to the degree of bending of the sub-segment; in one case, "the bending degree of the lower segment is smaller than that of the first segment" may mean that the number of inflection points of the lower segment is smaller than that of the first segment, and the inflection points are the turning points of different line segments; in another case, "the bending degree of the lower segment is smaller than that of the first segment" may mean that the angle between the two line segments in the lower segment is larger than the minimum angle between two adjacent line segments in the first segment; in another case, "the bending degree of the lower segment is smaller than that of the first segment" may mean that the angle between the two line segments in the lower segment is closer to 180 degrees than the angle between two adjacent line segments in the first segment. The irregular shapes of the side edges make the velvet structure have a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. In addition, the appearance of the solar cell is uniformly black, which is more beautiful. The bending degree of the lower section is relatively small, which facilitates the formation of the passivation anti-reflection layer on the lower part of the velvet structure, so that the lower part of the velvet structure obtains a better passivation effect. For example, in Figure 3, in the leftmost side edge of the leftmost pyramid-like structure: the bending degree of the lower section located on the left side of L1 is smaller than the bending degree of the first section located on the right side of L1. In the rightmost side edge of the leftmost pyramid-like structure: the bending degree of the lower section located on the right side of L2 is smaller than the bending degree of the first section located on the left side of L2.

[0056] The cone surface of the pyramid-like structure includes: a first sub-cone surface away from the cone apex, and a second sub-cone surface. That is, the first sub-cone surface is the portion of the cone surface farthest from the cone apex 11, that is, the portion of the cone surface close to the silicon substrate, and the second sub-cone surface is the remaining portion of the cone surface except the second sub-cone surface. For example, in Figure 3, for the leftmost pyramid-like structure, the portion of the cone surface between the right side of the dotted line L1 and the left side of the cone apex of the leftmost pyramid-like structure, and the portion between the left side of the dotted line L2 and the right side of the cone apex of the leftmost pyramid-like structure are the second sub-cone surface, and the portion to the left of L1 and the portion to the right of L2 are the first sub-cone surface. For the middle pyramid-like structure, the portion of the cone surface between the right side of the dotted line L3 and the left side of the cone apex of the middle pyramid-like structure, and the portion between the left side of the dotted line L4 and the right side of the cone apex of the middle pyramid-like structure are the second sub-cone surface, and the portion to the left of L3 and the portion to the right of L4 are the first sub-cone surface. For the rightmost pyramid-like structure, the part of the cone surface between the right side of the dotted line L5 and the left side of the cone top of the rightmost pyramid-like structure, and the part between the left side of the dotted line L6 and the right side of the cone top of the rightmost pyramid-like structure are the second sub-cone surface, and the part on the left side of L5 and the part on the right side of L6 are the first sub-cone surface.

[0057] Optionally, referring to FIG2 , the pyramid-like surface has a branched texture 12. The shape of the branched texture 12 is similar to that of a tree branch, i.e., a forked pattern on the main trunk. The number of branched textures 12 on the second sub-surface of the pyramid-like surface is greater than the number of branched textures 12 on the first sub-surface, farther from the apex. There is a correspondence between the branched textures 12 and the protrusions or depressions on the pyramid-like surface: the branched textures 12 are typically located at the intersection of the protrusions and depressions on the pyramid-like surface. That is, the greater the number of branched textures 12, the greater the number of protrusions and depressions on the pyramid-like surface. Therefore, the more textures there are, the larger the specific surface area of ​​the velvet structure. The more irregular the distribution of the branched textures, the larger the specific surface area of ​​the velvet structure, lower reflectivity, and better light trapping, thereby increasing the short-circuit current and ultimately improving the photoelectric conversion efficiency of the solar cell. Furthermore, the solar cell has a uniform black appearance, which is more aesthetically pleasing. For example, in FIG2 , in the cone surface of the pyramid-like structure on the far right, there is basically no branched texture in the first sub-cone surface away from the cone top, and there are more branched textures in the second sub-cone surface.

[0058] Optionally, referring to FIG4 , in the velvet structure, at least the lower portions of at least two pyramid-like structures away from the cone top 11 are fused into one, and the cone tops of the fused pyramid-like structures 15 are separated. In this way, the shape of the velvet structure is flexible and diverse, and easy to prepare. The cone tops of the fused pyramid-like structures 15 are separated, so that the velvet structure has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. The appearance of the solar cell is uniform black and more beautiful. For example, in FIG4 , in the velvet structure, at least the lower portions of the two pyramid-like structures enclosed in the curly brackets on the left, away from the cone top 11, are fused into one, and the cone tops of the fused pyramid-like structures 15 are separated.

[0059] Optionally, in the direction perpendicular to the height of the pyramid-like structure, the distance between the apexes of adjacent integrated pyramid-like structures 15 is greater than 0.2 μm, and can also be greater than 0.5 μm. For example, it can be: 0.21 μm, or 0.31 μm, or 0.47 μm, or 0.5 μm, or 0.61 μm, or 0.77 μm, or 0.8 μm, or 0.88 μm, or 0.91 μm, or 1 μm, or 1.23 μm, or 1.34 μm, or 1.5 μm, or 1.6 μm.

[0060] Optionally, referring to FIG4 , in the velvet structure, at least the lower portions of at least two pyramid-like structures away from the apex 11 are fused into one, and the apex of each fused pyramid-like structure 15 has a height difference or is evenly distributed, making the shape of the velvet structure flexible and diverse, easy to prepare, and the velvet structure has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current, and ultimately improve the photoelectric conversion efficiency of the solar cell, and the appearance of the solar cell is uniform black, which is more beautiful. For example, in FIG4 , in the velvet structure, at least the lower portions of the two pyramid-like structures enclosed in the left curly brackets away from the apex 11 are fused into one, and the apex of each fused pyramid-like structure 15 has a height difference. For another example, in FIG4 , in the velvet structure, at least the lower portions of the two pyramid-like structures enclosed in the right curly brackets away from the apex 11 are fused into one, and the apex of each fused pyramid-like structure 15 is roughly even.

[0061] Optionally, referring to Figure 4, in the velvet structure, at least the lower parts of at least two pyramid-like structures away from the cone top 11 are fused into one, and the cone tops of each integrated pyramid-like structure 15 have a height difference, which is greater than 0 and less than or equal to 1.6 microns; the height difference is set more reasonably, so that the velvet structure has a more reasonable specific surface area. On the one hand, the reflectivity is lower and the light trapping effect is better. On the other hand, the passivation anti-reflection layer formed in different parts has a thickness difference, which makes the incident light have a longer optical path and increases the absorption of light.

[0062] For example, in the velvet structure, at least the lower parts of at least two pyramid-like structures away from the cone top 11 are fused into one, and the cone tops of each integrated pyramid-like structure 15 have a height difference, and the height difference can be: 0.1μm, or 0.17μm, or 0.2μm, or 0.31μm, or 0.47μm, or 0.5μm, or 0.61μm, or 0.77μm, or 0.8μm, or 0.88μm, or 0.91μm, or 1μm, or 1.21μm, or 1.34μm, or 1.5μm, or 1.6μm.

[0063] Optionally, referring to Figure 4, in the velvet structure, at least the lower parts of at least two pyramid-like structures away from the cone top 11 are fused into one, and the cone tops of each integrated pyramid-like structure 15 have a height difference, which is greater than 0 and less than or equal to 0.8 microns; the height difference is smaller, so that the velvet structure has a more reasonable specific surface area. On the one hand, the reflectivity is lower and the light trapping effect is better. On the other hand, the passivation anti-reflection layer formed in different parts has a thickness difference, which makes the incident light have a longer optical path and increases the absorption of light.

[0064] For example, in the velvet structure, at least the lower parts of at least two pyramid-like structures away from the cone top 11 are fused into one, and the cone tops of each integrated pyramid-like structure 15 have a height difference, which can be: 0.1μm, or 0.13μm, or 0.2μm, or 0.33μm, or 0.4μm, or 0.47μm, or 0.5μm, or 0.61μm, or 0.77μm, or 0.8μm.

[0065] Optionally, referring to Figures 1 to 5, in the same type of pyramid structure, among the two side edges located on both sides of the cone top 11, the size of one side edge is larger than the size of the other side edge along the direction of the thickness of the silicon substrate, so that the shape of the pyramid-like structure is more irregular, the velvet structure has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell, and the appearance of the solar cell is uniform black, which is more beautiful.

[0066] Optionally, referring to Figures 1 to 4, for two adjacent pyramid-like structures, the smaller side edges of one pyramid-like structure are closely distributed with the smaller side edges of the other pyramid-like structure, so that the shape of the velvet structure is more irregular. The velvet structure has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. The appearance of the solar cell is uniform black, which is more beautiful.

[0067] Optionally, referring to Figures 1 to 4, in a side edge, the lower segment away from the cone top 11 is a straight segment, or a segment with at most two inflection points. Specifically, for example, the lower segment is a straight segment or an approximate straight segment with only one slope, in which case the lower segment has no inflection point; or, the lower segment is composed of two line segments, the two line segments can be a straight segment and a curved segment, the straight segment and the curved segment intersecting at a position having an inflection point, or the two line segments can be two straight segments, the two straight segments have different slopes, and the two straight segments intersecting at a position having an inflection point; or, the lower segment is composed of three line segments, which can be a straight segment, another straight segment, and a curved segment, the two straight segments have different slopes, and the three intersecting positions each have an inflection point; or, the lower segment can be composed of three straight segments, the three straight segments have different slopes, and the position where two adjacent straight lines intersect has an inflection point. The lower segment here can be prepared using existing velveting methods and parameters, with better process compatibility. The trend of the lower section is gentle, which facilitates the formation of the passivation anti-reflection layer on the lower part of the suede structure, so that the lower part of the suede structure obtains a better passivation effect.

[0068] Optionally, referring to Figures 1 to 4, in a side edge, the first segment other than the lower segment is a broken line segment and / or a curved line segment. The number of broken line segments and the number of curved line segments contained in the first segment are not specifically limited. In this way, the shape of the velvet structure is more irregular, the velvet structure has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. The appearance of the solar cell is uniform black, which is more beautiful.

[0069] For example, in Figure 3, in the left side edge of the leftmost pyramid-like structure, the lower segment to the left of L1 consists of two straight line segments with one inflection point, while the first segment to the right of L1 consists of multiple broken line segments and multiple curved line segments. In the right side edge of the leftmost pyramid-like structure, the lower segment to the right of L2 consists of one straight line segment with no inflection point, while the first segment to the left of L2 consists of multiple broken line segments and multiple curved line segments. In the left side edge of the middle pyramid-like structure, the lower segment to the left of L3 consists of two straight line segments with one inflection point, while the first segment to the right of L3 consists of multiple broken line segments and multiple curved line segments. In the right side edge of the middle pyramid-like structure, the lower segment to the right of L4 consists of three straight line segments with two inflection points, while the first segment to the left of L4 consists of multiple broken line segments and multiple curved line segments. In the left side edge of the rightmost pyramid-like structure: the lower segment located on the left side of L5 is two straight line segments with an inflection point, while the first segment located on the right side of L5 is composed of multiple broken line segments and multiple curved line segments; in the right side edge of the rightmost pyramid-like structure: the lower segment located on the right side of L6 is composed of a straight line segment without an inflection point, while the first segment located on the left side of L6 is composed of multiple broken line segments and multiple curved line segments.

[0070] Optionally, the length of the lower segment of a side edge accounts for at least 1 / 10 of the length of the side edge. Here, the division between the lower segment and the first segment of a side edge is relatively accurate, which not only facilitates the preparation of a suede structure, but also has lower reflectivity and better light trapping, which can increase short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. The solar cell also has a uniform black appearance and is more aesthetically pleasing. Regarding the proportion of the length of the lower segment of the pyramid-like structure herein, it should be understood that as long as the length of the lower segment of the majority of the pyramid-like structures in the suede structure meets the aforementioned proportion, the aforementioned effect can be achieved.

[0071] For example, the length of the lower section of a side edge is 1 / 10, or 2 / 15, or 3 / 20, or 1 / 9, or 1 / 8, or 1 / 7, or 1 / 6, or 1 / 5, or 1 / 4 of the length of the side edge.

[0072] The first plane perpendicular to the thickness direction of the silicon substrate 1 refers to a plane defined by the length and width directions of the silicon substrate 1. In other words, when a solar cell is placed on a horizontal plane, with the light-facing or light-backward side of the silicon substrate 1 facing away from the horizontal plane, the first plane is parallel to the horizontal plane. For example, in FIG3 , the horizontal dashed lines extending left and right are schematic representations of the first plane. For another example, in FIG5 , the horizontal dashed lines extending left and right are schematic representations of the first plane. Optionally, the angle between the lower segment of a side edge and the first plane perpendicular to the thickness direction of the silicon substrate 1 is smaller than the angle between the first segment of the side edge and the first plane. Specifically, by using a corrosive additive to adjust the etching rate of the chemical solution on each crystal orientation of the silicon substrate, the side edges are subjected to irregular etching, resulting in a more irregular shape of the velvet structure. The velvet structure has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. The solar cell also has a uniform black appearance and is more aesthetically pleasing. Herein, the angle between the first segment of a lateral edge and the first plane may be the angle between the line connecting the upper endpoint and the lower endpoint of the first segment and the first plane. Regarding the angle between the lower segment of a lateral edge and the first plane: if the lower segment of a lateral edge is a single straight segment, the angle between the lower segment of the lateral edge and the first plane may be the angle between the straight segment and the first plane; if the lower segment of a lateral edge is not a single straight segment, the angle between the lower segment of the lateral edge and the first plane may be the angle between the straight segment in the lower segment of the lateral edge to which the lower endpoint of the lower segment belongs and the first plane.

[0073] Optionally, the first section of a side edge is composed of an upper section and a middle section, wherein the upper section is adjacent to the cone top 11, and the middle section is located between the lower section and the upper section. The length of the upper section accounts for at least 1 / 10 of the length of the side edge, and the length of the middle section accounts for at least 2 / 5 of the length of the side edge. Specifically, the lower section is the portion of the side edge that is farthest from the cone top 11, or the lower section is the lowermost portion of the side edge; the upper section is the portion of the side edge that is closest to the cone top 11, or the upper section is the uppermost portion of the side edge; and the middle section is the portion located in the middle of the side edge. The aforementioned accurate division of the positions of the lower section, upper section, and middle section is not only conducive to the preparation of the velvet structure, but also has lower reflectivity and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. In addition, the appearance of the solar cell is uniformly black, which is more beautiful.

[0074] For example, the length of the upper section of a side edge is 1 / 10, 2 / 15, 3 / 20, 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, or 1 / 4 of the length of the side edge. The portion of a side edge excluding the lower section and the upper section is the middle section. For example, the length of the middle section of a side edge is 2 / 5, 13 / 30, 7 / 15, 1 / 2, 8 / 15, 17 / 30, or 3 / 5 of the length of the side edge.

[0075] Optionally, referring to FIG3 , the angle b between the lower segment of a side edge and the aforementioned first plane is 50° to 55°. Referring to FIG5 , the angle c between the upper segment and the first plane is 55° to 80°, and the angle between the middle segment and the first plane is 55° to 85°. In FIG5 , the white solid line is the reverse extension of the upper segment. The angles between the three sub-segments and the aforementioned first plane are reasonably set, making it easy to manufacture. Furthermore, the portion of the pyramid-like structure near the apex 11 is sharper, with lower reflectivity and better light trapping, which can increase short-circuit current and ultimately improve the photovoltaic conversion efficiency of the solar cell. Furthermore, the solar cell has a uniform black appearance, making it more aesthetically pleasing. As previously mentioned, if the lower segment of a side edge is a single straight segment, the angle b between the lower segment of the side edge and the first plane can be the angle between the straight segment and the first plane. For example, in FIG3 , if the lower segment of the right side edge of the leftmost pyramid-like structure, located to the right of L2, is a single straight segment, then the angle b between the lower segment of the right side edge and the first plane can be the angle between the straight segment and the first plane. If the lower segment of a side edge is not a single straight line segment, the angle b between the lower segment of the side edge and the first plane can be the angle between the straight line segment to which the lower endpoint of the lower segment belongs and the first plane. For example, in Figure 3, the lower segment of the left side edge of the leftmost pyramid-like structure, located to the left of L1, is composed of two straight lines and has a single inflection point. In other words, the lower segment of the side edge is composed of a first straight line segment and a second straight line segment connected from top to bottom. In this case, the angle b between the lower segment of the side edge and the first plane can be the angle between the straight line segment to which the lower endpoint of the lower segment belongs, i.e., the second straight line segment, i.e., the line connecting the lower endpoint of the lower segment and the inflection point closest to the lower endpoint of the lower segment, and the first plane. If the upper segment of a side edge is a single straight line segment, the angle c between the upper segment of the side edge and the first plane can be the angle between the straight line segment and the first plane. If the upper segment of a lateral edge is not a single straight segment, the angle c between the upper segment of the lateral edge and the first plane may be the angle between the line connecting the upper and lower endpoints of the upper segment and the first plane. Similarly, the angle between the middle segment of a lateral edge and the first plane may be the angle between the line connecting the upper and lower endpoints of the middle segment and the first plane.

[0076] The present application also provides another solar cell, comprising: a silicon substrate having a surface having a velvet structure, the velvet structure comprising: a plurality of pyramid-like structures; the pyramid-like structures comprising: a cone surface and a cone apex; the cone surface of the pyramid-like structure comprising: a first sub-cone surface distal from the cone apex, and a second sub-cone surface. Reference may be made to the aforementioned related descriptions, and to avoid repetition, they will not be repeated here. Referring to FIG. 4 , the cone apex 11 of the pyramid-like structure and the second sub-cone surface of the cone surface of the pyramid-like structure have a cluster of nested quasi-annular textures 13. Here, the quasi-annular textures 13 may be open, annular-like patterns, and / or closed, annular-like patterns. For example, in FIG. 4 , the cluster of nested quasi-annular textures 13 in the middle, labeled 13, contains both open and closed patterns. The number of quasi-annular textures 13 in a cluster of nested quasi-annular textures 13 is not specifically limited, and the quasi-annular textures 13 are nested within one another. The first sub-cone surface of the pyramid-like structure is substantially free of quasi-annular textures. There is a corresponding relationship between the above-mentioned annular texture 13 and the protrusions or depressions on the cone surface of the pyramid-like structure: the annular texture 13 is usually located at the junction of the protrusions and depressions on the cone surface of the pyramid-like structure, that is, the more annular textures 13 there are, the more protrusions and depressions there are on the cone surface of the pyramid-like structure. Therefore, the more textures there are, the larger the specific surface area of ​​the velvet structure can be increased. The more irregular the distribution position of the above-mentioned annular texture is, the velvet structure can have a larger specific surface area, lower reflectivity, better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. The appearance of the solar cell is uniform black, which is more beautiful.

[0077] Referring to FIG. 4 , the quasi-annular texture 13 herein can be a skirt-like texture, i.e., an irregularly stacked texture similar to a skirt-like texture visible under electron microscopy, and / or a rose-like texture, i.e., an irregularly stacked texture similar to the stacked layers of rose petals within a rose flower visible under electron microscopy. In this manner, the quasi-annular texture 13 has an aesthetically pleasing shape, lower reflectivity, and better light trapping. The quasi-annular texture 13 is located on the conical surface and the apex, or, further, is located within the second sub-conical surface of the conical surface and on the apex.

[0078] Optionally, in a velvet structure, at least the first sub-cone surfaces of at least two pyramid-like structures are fused together, and the apexes of the fused pyramid-like structures are separated. This allows the velvet structure to have a larger specific surface area, lower reflectivity, and better light trapping, thereby increasing short-circuit current and ultimately improving the photoelectric conversion efficiency of the solar cell. Furthermore, the solar cell has a uniform black appearance, which is more aesthetically pleasing. For example, in FIG4 , in the velvet structure, at least the first sub-cone surfaces of the two pyramid-like structures enclosed in curly brackets, which are away from the apex 11, are fused together, and the apexes of the fused pyramid-like structures 15 are separated.

[0079] Optionally, in a direction perpendicular to the height of the pyramid-like structures, the distance between the apexes of adjacent integrated pyramid-like structures 15 is greater than 0.2 μm, or greater than 0.5 μm, for example, it can be: 0.21 μm, or 0.31 μm, or 0.47 μm, or 0.5 μm, or 0.61 μm, or 0.77 μm, or 0.8 μm, or 0.88 μm, or 0.91 μm, or 1 μm, or 1.23 μm, or 1.34 μm, or 1.5 μm, or 1.6 μm.

[0080] Optionally, in the integrated pyramid-like structures, the annular textures in the cone surfaces of different pyramid-like structures are separated, so that the velvet structure has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current, and ultimately improve the photoelectric conversion efficiency of the solar cell, and the appearance of the solar cell is uniform black, which is more beautiful. For example, in Figure 4, in the velvet structure, at least the lower part away from the cone top 11 of the two pyramid-like structures enclosed in the curly brackets on the left is fused into one, and the cone tops of the integrated pyramid-like structures 15 are separated. Alternatively, in the integrated pyramid-like structures, the annular textures in the cone surfaces of different pyramid-like structures partially overlap, making the velvet structure flexible and diverse, and the velvet structure has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current, and ultimately improve the photoelectric conversion efficiency of the solar cell, and the appearance of the solar cell is uniform black, which is more beautiful. For example, in Figure 4, in the velvet structure, at least the lower part away from the cone top 11 of the two pyramid-like structures enclosed in the right brackets are fused into one, and the annular texture parts in the cone surfaces of different pyramid-like structures of the integrated pyramid-like structures 15 overlap. Here, the outermost annular texture parts in the cone surfaces of different pyramid-like structures of the integrated pyramid-like structures 15 may overlap.

[0081] Optionally, within a cluster of quasi-annular textures, the quasi-annular textures at different locations along the height direction of the quasi-pyramid structure overlap, making the velvet structure flexible and diverse. The velvet structure also has a larger specific surface area, lower reflectivity, and better light trapping, which can increase short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. Furthermore, the solar cell has a uniform black appearance, which is more aesthetically pleasing. For example, in Figure 4, within the cluster of quasi-annular textures labeled 13 at the bottom, the quasi-annular textures 13 at different locations along the height direction of the quasi-pyramid structure overlap.

[0082] Optionally, in the conical surface of the pyramid-like structure, the annular texture 13 extends from a position adjacent to the top of the cone 11 at most to a position on the conical surface corresponding to a portion of the pyramid-like structure whose height difference from the top of the cone 11 is 2 / 3, or, the annular texture 13 can also extend from a position adjacent to the top of the cone 11 at most to a position on the conical surface corresponding to a portion of the pyramid-like structure whose height difference from the top of the cone 11 is 1 / 2; by adjusting the distribution position of the annular texture 13, the position where the protrusions and depressions of the conical surface are concentrated can be adjusted, so that the velvet structure, especially the upper half of the velvet structure, has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell, and the appearance of the solar cell is uniformly black, which is more beautiful.

[0083] Optionally, the maximum dimension d1 inside the quasi-annular texture 13 is 0.5 μm to 2 μm. The maximum dimension d1 inside the quasi-annular texture 13 is set more reasonably. It is not only easy to prepare, but also the velvet structure has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. The appearance of the solar cell is uniform black, which is more beautiful.

[0084] For example, the maximum dimension d1 within the ring-like texture 13 may be 0.5 μm, 0.56 μm, 0.61 μm, 0.72 μm, 0.93 μm, 1 μm, 1.12 μm, 1.25 μm, 1.31 μm, 1.42 μm, 1.53 μm, 1.61 μm, 1.77 μm, 1.83 μm, 1.92 μm, or 2 μm. For another example, the maximum dimension d1 within the ring-like texture 13 may be 0.55 μm to 1.8 μm, or the maximum dimension d1 within the ring-like texture 13 may be 0.6 μm to 1.6 μm.

[0085] Optionally, referring to Figure 4, in the same type of annular texture, the maximum dimensions inside the annular texture are not equal in at least two directions perpendicular to each other, that is, in the same type of annular texture, the maximum dimension inside the annular texture in a first direction is not equal to the maximum dimension inside the annular texture in a second direction perpendicular to the first direction, which makes the shape of the velvet structure more irregular, the reflectivity is lower, and the light trapping effect is better, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell, and the appearance of the solar cell is uniformly black, which is more beautiful.

[0086] Optionally, referring to Figure 4, in the same cluster of annular textures, at least one annular texture 13 has spikes 131 facing the outside of the annular texture 13. The spikes 131 can increase the specific surface area, so that the velvet structure has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. The appearance of the solar cell is uniform black, which is more beautiful.

[0087] Optionally, referring to Figure 4, in a cluster of annular textures 13, along the height direction of the pyramid-like structure, the closer to the top of the cone 11, the smaller the outline of the annular texture 13, and the farther away from the top of the cone 11, the larger the outline of the annular texture 13. The distribution position of the above-mentioned annular textures 13 is irregular. At the same time, the annular texture 13 can increase the specific surface area, so that the velvet structure has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. The appearance of the solar cell is uniform black, which is more beautiful.

[0088] Optionally, referring to Figures 1 to 5, the portion of the pyramid-like structure away from the apex 11 is the lower portion of the pyramid-like structure, and the height of the lower portion accounts for at least 1 / 10 of the height of the pyramid-like structure; in the cone surface of the pyramid-like structure, the first sub-cone surface away from the apex 11 is: the area corresponding to the lower portion of the cone surface of the pyramid-like structure, and the second sub-cone surface is: the area of ​​the cone surface of the pyramid-like structure that is closer to the apex 11 than the first sub-cone surface. Specifically, the division of the second sub-cone surface and the first sub-cone surface here is more accurate, which is not only conducive to the preparation of the velvet structure, but also has lower reflectivity and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell, and the appearance of the solar cell is uniform black and more beautiful. In this article, with respect to the proportion of the height of the lower portion of the pyramid-like structure, it should be understood that as long as the height of the lower portion of most of the pyramid-like structures in the velvet structure meets the aforementioned proportion, the aforementioned effect can be achieved.

[0089] For example, the portion of the pyramid-like structure away from the apex 11 is the lower portion of the pyramid-like structure, and the height of the lower portion accounts for 1 / 10, 2 / 15, 3 / 20, 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, or 1 / 4 of the height of the pyramid-like structure. In the conical surface of the pyramid-like structure, the first sub-conical surface away from the apex 11 is the area corresponding to the lower portion of the conical surface of the pyramid-like structure, and the second sub-conical surface is the area of ​​the conical surface of the pyramid-like structure that is closer to the apex 11 than the first sub-conical surface.

[0090] Optionally, the portion of the pyramid-like structure away from the apex 11 is the lower portion of the pyramid-like structure, and the height of the lower portion accounts for at least 1 / 5 of the height of the pyramid-like structure; the portion of the pyramid-like structure adjacent to the apex 11 is the upper portion of the pyramid-like structure, and the height of the upper portion accounts for at most 1 / 5 of the height of the pyramid-like structure; the portion of the pyramid-like structure located between the lower portion and the upper portion is the middle portion, and the height of the middle portion accounts for at least 2 / 5 of the height of the pyramid-like structure. In the cone surface of the pyramid-like structure, the first sub-cone surface away from the apex 11 is: the area corresponding to the lower portion of the cone surface of the pyramid-like structure. The second sub-cone surface is further divided into a second sub-cone surface and a third sub-cone surface. In the cone surface of the pyramid-like structure, the second sub-cone surface is: the area corresponding to the upper portion of the cone surface of the pyramid-like structure. In the cone surface of the pyramid-like structure, the third sub-cone surface is: the area corresponding to the middle portion of the cone surface of the pyramid-like structure. The division of the three sub-cones is more accurate, which is not only conducive to the preparation of the velvet structure, but also has lower reflectivity and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. In addition, the appearance of the solar cell is uniformly black and more beautiful. In this article, with respect to the proportion of the height of the upper part of the pyramid-like structure, it should be understood that as long as the height of the upper part of the most pyramid-like structures in the velvet structure meets the aforementioned proportion, the aforementioned effect can be achieved. Similarly, in this article, with respect to the proportion of the height of the middle part of the pyramid-like structure, it should be understood that as long as the height of the middle part of the most pyramid-like structures in the velvet structure meets the aforementioned proportion, the aforementioned effect can be achieved.

[0091] For example, the portion of the pyramid-like structure adjacent to the apex 11 is the upper portion of the pyramid-like structure, and the height of the upper portion accounts for 1 / 10, 2 / 15, 3 / 20, 1 / 9, 1 / 8, 1 / 7, 1 / 6, or 1 / 5 of the height of the pyramid-like structure. For another example, the portion of the pyramid-like structure between the upper portion and the lower portion is the middle portion, and the height of the middle portion accounts for 2 / 5, 13 / 30, 7 / 15, 1 / 2, 8 / 15, 17 / 30, or 3 / 5 of the height of the pyramid-like structure.

[0092] Optionally, referring to Figures 3 and 4, the pyramid-like structure further includes: a bottom contour line 14 away from the cone top 11, wherein at least two points in the same bottom contour line 14 have a height difference. As shown in Figure 3, for the leftmost pyramid-like structure, the middle pyramid-like structure, and the rightmost pyramid-like structure, the bottom contour lines of the three have a height difference between the left and right endpoints. The shapes of these pyramid-like structures are more irregular, resulting in a velvet structure with a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. The solar cell also has a uniform black appearance and is more aesthetically pleasing.

[0093] Optionally, referring to Figure 1, the suede structure has a vertex angle a of 55° to 90°. The vertex angle of the suede structure is the angle between two opposing side edges passing through the apex of a pyramid-like structure. A suede structure with a vertex angle a of 55° to 90° provides a larger specific surface area, lower reflectivity, and better light trapping, thereby increasing short-circuit current and ultimately improving the photovoltaic conversion efficiency of the solar cell. Furthermore, the solar cell has a uniform black appearance, which is more aesthetically pleasing.

[0094] For example, the top angle a of the velvet structure may be 55°, or 56°, or 59.3°, or 62°, or 70°, or 73.5°, or 78.6°, or 80.2°, or 84°, or 89.3°, or 90°.

[0095] Optionally, the height of the pyramid-like structure is 0.2μm (micrometer) to 3μm. The height of the pyramid-like structure is more appropriate, so that the velvet structure has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. The appearance of the solar cell is uniform black, which is more beautiful.

[0096] For example, the height of the pyramid-like structure can be 0.5μm to 3μm, or the height of the pyramid-like structure can be 0.2μm, or 0.31μm, or 0.37μm, or 0.42μm, or 0.6μm, or 0.73μm, or 0.88μm, or 0.95μm, or 1.2μm, or 1.24μm, or 1.7μm, or 1.99μm, or 2.21μm, or 2.7μm, or 2.79μm, or 3μm.

[0097] The present application also provides a solar cell, comprising: a silicon substrate, the surface of the silicon substrate having a velvet structure, the velvet structure comprising: a plurality of pyramid-like structures; the pyramid-like structures comprising: a cone surface and a cone top. Reference may be made to the aforementioned relevant records herein, and in order to avoid repetition, no further details will be given here. The cone top of the pyramid-like structure and the cone surface of the pyramid-like structure have: a skirt-like texture, and / or a rose-like texture. The skirt-like texture and / or the rose-like texture make the annular-like texture 13 beautiful in shape, with lower reflectivity and better light trapping effect.

[0098] Optionally, the cone surface of the pyramid-like structure includes: a first sub-cone surface away from the cone top, and a second sub-cone surface. The skirt-like texture and / or rose-like texture are located in the cone top and the second sub-cone surface of the pyramid-like structure. The distribution position of the skirt-like texture and / or the rose-like texture is irregular. At the same time, the skirt-like texture and / or the rose-like texture can increase the specific surface area, so that the velvet structure has a larger specific surface area, lower reflectivity, better light trapping effect, can increase short-circuit current, and ultimately improve the photoelectric conversion efficiency of the solar cell. The appearance of the solar cell is uniform black, which is more beautiful.

[0099] Optionally, the portion of the pyramid-like structure away from the apex is the lower portion of the pyramid-like structure, and the height of the lower portion accounts for at least 1 / 10 of the height of the pyramid-like structure; the first sub-cone surface is the area corresponding to the lower portion of the pyramid-like structure, and the second sub-cone surface is the area of ​​the pyramid-like structure closer to the apex than the first sub-cone surface. Specifically, the division between the second sub-cone surface and the first sub-cone surface is more accurate, which not only facilitates the preparation of the velvet structure, but also has lower reflectivity and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. The solar cell also has a uniform black appearance and is more aesthetically pleasing.

[0100] For example, the portion of the pyramid-like structure away from the apex 11 is the lower portion of the pyramid-like structure, and the height of the lower portion accounts for 1 / 10, 2 / 15, 3 / 20, 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, or 1 / 4 of the height of the pyramid-like structure. In the conical surface of the pyramid-like structure, the first sub-conical surface away from the apex 11 is the area corresponding to the lower portion of the conical surface of the pyramid-like structure, and the second sub-conical surface is the area of ​​the conical surface of the pyramid-like structure that is closer to the apex 11 than the first sub-conical surface.

[0101] Optionally, the light-facing surface and / or backlight surface of the silicon substrate 1 have any of the aforementioned velvet structures. This allows for flexible placement of the velvet structure of the silicon substrate 1, and the velvet structure has a larger specific surface area, lower reflectivity, and better light trapping, which can increase short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. Furthermore, the solar cell has a uniform black appearance, making it more aesthetically pleasing. For example, at least the light-facing surface of the solar cell has any of the aforementioned velvet structures. For another example, the solar cell is a bifacial solar cell, and the light-facing surface of the silicon substrate 1 has any of the aforementioned velvet structures, or the backlight surface of the silicon substrate 1 has any of the aforementioned velvet structures, or both the light-facing and backlight surfaces of the silicon substrate 1 have any of the aforementioned velvet structures. For another example, the solar cell is a back-contact solar cell, and the light-facing surface of the silicon substrate 1 has any of the aforementioned velvet structures. For another example, the solar cell is a back-contact solar cell, and the backlight surface of the silicon substrate 1 has any of the aforementioned velvet structures. For another example, the solar cell is a back-contact solar cell, and both the light-facing and backlight surfaces of the silicon substrate 1 have any of the aforementioned velvet structures. For another example, the solar cell is a back-contact solar cell. Whether the light-facing surface of the silicon substrate 1 has the aforementioned velvet structure is not limited. The back-light surface of the silicon substrate 1 includes: alternating first and second regions, wherein the first region is doped with a first conductive element, or a first conductive layer is provided on the first region and doped with the first conductive element, and at least a portion of the second region is doped with the second conductive element, or a second conductive layer is provided on at least a portion of the second region and doped with the second conductive element. Here, the first conductive element corresponds to a first conductivity type, and the second conductive element corresponds to a second conductivity type, and the first and second conductivity types are different. The first region has any of the aforementioned velvet structures, or both the second region have any of the aforementioned velvet structures, or both the first and second regions have any of the aforementioned velvet structures. Alternatively, the portion of the second region other than the portion doped with the second conductive element is provided with any of the aforementioned velvet structures. Alternatively, the portion of the second region other than the portion provided with the second conductive layer is provided with any of the aforementioned velvet structures. For another example, the solar cell is a back-contact solar cell, and whether the light-facing surface of the silicon substrate 1 has the aforementioned velvet structure is not limited. The backlight surface of the silicon substrate 1 includes: alternating first areas and second areas, where a first conductive layer is prepared on the first area, and a second conductive layer is prepared on the second area. The conductivity types of the first conductive layer and the second conductive layer are different, and there may be an isolation area between the first area and the second area, wherein the isolation area may have any of the aforementioned velvet structures, or at least one of the first area, the second area, and the isolation area may have any of the aforementioned velvet structures.For another example, the solar cell is a back-contact solar cell. Whether the light-facing surface of the silicon substrate 1 has the aforementioned textured structure is not limited. The back-facing surface of the silicon substrate 1 includes alternating first and second regions. A first conductive layer is formed on the first region, and a second conductive layer is formed on the second region. The first and second conductive layers have different conductivity types and at least partially overlap. An insulating structure is provided between the overlapping portions of the first and second conductive layers. At least one of the first and second regions may have any of the aforementioned textured structures. The different conductivity types may, in some cases, be p-type doped or n-type doped, respectively. For another example, the solar cell is a back-contact solar cell. The back-facing surface of the silicon substrate 1 includes alternating n-type and p-type regions. The p-type regions are used to collect and conduct holes, and the n-type regions are used to collect and conduct electrons. An isolation region is provided between adjacent n-type and p-type regions. The light-facing surface of the silicon substrate 1 has any of the aforementioned textured structures, and / or the isolation region has any of the aforementioned textured structures. Both the n-type and p-type regions are relatively flat, resulting in high-quality conductive and passivation layers. No conductive layer is required in the isolation region. Providing a velvet structure can lower reflectivity, enhance light trapping, and improve the electrical performance of the back-contact solar cell. For another example, the solar cell is a back-contact solar cell, where the backlight surface of the silicon substrate 1 includes alternating n-type and p-type regions, the p-type regions having any of the aforementioned velvet structures, and the light-facing surface of the silicon substrate 1 also having any of the aforementioned velvet structures.

[0102] Optionally, two or three of the three aforementioned velvet structural features appear in the same type of pyramid structure. Specifically:

[0103] In some embodiments, the same pyramid-like structure has both the aforementioned first and second velvet structure characteristics, and the specific characteristics and effects are described above. For example, the pyramid-like structure includes: a cone surface, a cone top 11 and at least two side edges; the side edges include: a lower section away from the cone top 11, and a first section, the first section being the portion of the side edge excluding the lower section; the bending degree of the lower section here is less than the bending degree of the first section. At the same time, the cone surface of the pyramid-like structure includes: a first sub-cone surface away from the cone top, and a second sub-cone surface, and the cone top 11 of the pyramid-like structure and the second sub-cone surface of the cone surface of the pyramid-like structure have a cluster of nested annular textures 13. Here, the annular texture 13 can be an open shape, a ring-like texture, and / or, the annular texture 13 can be a closed shape, a ring-like texture.

[0104] In other embodiments, the same pyramid-like structure has both the first and third velvet structure characteristics described above. The specific characteristics and effects are described above. For example, the pyramid-like structure includes: a cone surface, a cone top 11, and at least two side edges; the side edges include: a lower segment away from the cone top 11, and a first segment, which is the portion of the side edge excluding the lower segment. The bending degree of the lower segment is smaller than that of the first segment. At the same time, the cone top and the cone surface of the pyramid-like structure have: a skirt-like texture, and / or a rose-like texture.

[0105] In some other embodiments, the same pyramid-like structure has both the aforementioned second and third velvet structure characteristics, and the specific characteristics and effects are described above. For example, the pyramid-like structure includes: a cone surface and a cone top; the cone surface of the pyramid-like structure includes: a first sub-cone surface away from the cone top, and a second sub-cone surface; the cone top 11 of the pyramid-like structure and the second sub-cone surface of the cone surface of the pyramid-like structure have a cluster of nested ring-like textures 13. At the same time, the cone top and the cone surface of the pyramid-like structure have: a skirt-like texture, and / or a rose-like texture. Here, the skirt-like texture and / or the rose-like texture are composed of the ring-like texture 13.

[0106] In yet other embodiments, the same pyramid-like structure exhibits the aforementioned first, second, and third velvet structure characteristics. The specific characteristics are described above. For example, the pyramid-like structure includes a conical surface, a apex 11, and at least two side edges. The side edges include a lower segment distal to the apex 11 and a first segment, which is the portion of the side edge excluding the lower segment. The lower segment is less curved than the first segment. Furthermore, the pyramid-like structure includes a first sub-conical surface distal to the apex, and a second sub-conical surface. The apex 11 and the second sub-conical surface of the pyramid-like structure have a cluster of nested annular-like textures 13. Furthermore, the apex and the pyramid-like surface have a skirt-like texture and / or a rosette-like texture. The skirt-like texture and / or the rosette-like texture are formed from the annular-like texture 13.

[0107] It should be noted that, referring to Figure 3, the solar cell may further include: a passivation anti-reflection layer 2 located on the silicon substrate 1. The passivation anti-reflection layer 2 here can play a passivation role and can also play an anti-reflection role. The material of the passivation anti-reflection layer 2 can be selected from: silicon oxide, and / or silicon oxynitride, and the specific material of the passivation anti-reflection layer is not limited. The passivation anti-reflection layer can be prepared by PECVD (Plasma Enhanced Chemical Vapor Deposition) and other methods, and the specific preparation method of the passivation anti-reflection layer is not specifically limited.

[0108] The passivation anti-reflection layer 2 includes: a first portion located on the first sub-cone surface, and a second portion located on the second sub-cone surface. In the passivation anti-reflection layer 2, the thickness of the first portion along the same direction near the cone top 11 is greater than the thickness of the second portion. That is, here, when comparing the thickness of the first portion and the thickness of the second portion, the first portion and the second portion are limited to the same direction near the cone top 11. Throughout this article, the first portion and the second portion along the same direction near the cone top 11 can be understood as: the first portion and the second portion arranged in sequence in the direction from the bottom or bottom contour line of the pyramid-like structure to the cone top 11. The direction of the thickness here is perpendicular to the tangent line at the corresponding position of the outer surface of the passivation anti-reflection layer 2. Specifically, in the silicon substrate 1, the situation of the part adjacent to the pyramid-like structure is more complicated, and usually there are more gaps; the situation of the position adjacent to the adjacent pyramid-like structures is also more complicated, and usually there are more gaps; therefore, these positions require a thicker passivation anti-reflection layer to achieve a better passivation effect, so the first sub-cone surface adjacent to these positions also requires a thicker passivation anti-reflection layer to achieve a better passivation effect, and the gaps at the top of the cone are usually smaller, and only a thinner passivation anti-reflection layer is required to achieve a better passivation effect, so the second sub-cone surface adjacent to the top of the cone also requires a relatively thin passivation anti-reflection layer to achieve a better passivation effect. Therefore, in the present application, the thickness of the first part along the same direction close to the top of the cone is greater than the thickness of the second part. On the one hand, it can ensure that each position has an excellent passivation effect, and the present application sets the thickness of the passivation anti-reflection layer according to the passivation requirements, which can reduce the waste of materials used in the passivation anti-reflection layer 2. At the same time, in this application, after the light enters the passivation anti-reflection layer of different thicknesses, the optical path of the light will change more times, which can increase the optical distance. Combined with the suede structure of this application, it can further increase the absorption of light, and the light trapping effect is better, which can further increase the short-circuit current and further improve the photoelectric conversion efficiency of the solar cell. The appearance of the solar cell is uniform black, which is more beautiful. In summary, this application not only ensures the excellent passivation effect of all parts of the solar cell, but also greatly improves the anti-reflection effect, while also reducing waste.

[0109] As shown in Figure 3, for the leftmost pyramid-like structure, the portion of the passivation anti-reflection layer 2 between dashed lines L1 and L2, excluding the apex 11, is the second portion, while the portion to the left of L1 and the portion to the right of L2 are the first portion. For the first and second portions along the same direction L7 near the apex 11, the thickness of the first portion is greater than the thickness of the second portion. For the first and second portions along the same direction L8 near the apex 11, the thickness of the first portion is greater than the thickness of the second portion. For the middle pyramid-like structure, the portion of the passivation anti-reflection layer 2 between dashed lines L3 and L4, excluding the apex 11, is the second portion, while the portion to the left of L3 and the portion to the right of L4 are the first portion. For the first and second portions along the same direction L9 near the apex, the thickness of the first portion is greater than the thickness of the second portion. For the first and second portions along the same direction L10 near the apex, the thickness of the first portion is greater than the thickness of the second portion. For the pyramid-like structure on the far right, in the passivation anti-reflection layer 2, the portion excluding the cone top and located between the dotted line L5 and the dotted line L6 is the second portion, and the portion located to the left of L5 and the portion located to the right of L6 are the first portion; for the first portion and the second portion along the same direction L11 close to the cone top, the thickness of the first portion is greater than the thickness of the second portion; for the first portion and the second portion along the same direction L12 close to the cone top, the thickness of the first portion is greater than the thickness of the second portion.

[0110] It should be noted that the thickness of a certain part of the passivation anti-reflection layer 2 can be measured by an instrument such as a transmission electron microscope. The thickness of a certain part can be the thickness of the part measured directly, or the thickness of a certain part can be the average thickness obtained by measuring multiple points selected in the part, etc. The measurement method is selected according to the measurability of the actual measurement target and is not specifically limited to this.

[0111] Optionally, referring to Figures 1 to 3 and Figure 5, in the cone surface of the pyramid-like structure, the undulation of the first sub-cone surface is smaller than the undulation of the second sub-cone surface, or the roughness of the first sub-cone surface is smaller than the roughness of the second sub-cone surface. The undulation mainly refers to the degree of undulation caused by the relatively large high and low structures on the surface, and the roughness refers to the degree of unevenness caused by the micro-protrusions / micro-depressions on the surface. In this way, the shape of the cone surface of the pyramid-like structure is more irregular, so that the velvet structure has a larger specific surface area, lower reflectivity, and better light trapping effect, which can increase the short-circuit current and ultimately improve the photoelectric conversion efficiency of the solar cell. In addition, the appearance of the solar cell is uniform black, which is more beautiful. As shown in Figure 3, for the leftmost pyramid-like structure, in the cone surface, the undulation of the first sub-cone surface located on the left side of the dotted line L1 and the first sub-cone surface located on the right side of the dotted line L2 is smaller than the undulation of the second sub-cone surface located between the right side of the dotted line L1 and the left side of the cone top of the leftmost pyramid-like structure, and the undulation of the second sub-cone surface between the left side of the dotted line L2 and the right side of the cone top of the leftmost pyramid-like structure; or, the roughness of the first sub-cone surface located on the left side of the dotted line L1 and the first sub-cone surface located on the right side of the dotted line L2 is smaller than the roughness of the second sub-cone surface located between the right side of the dotted line L1 and the left side of the cone top of the leftmost pyramid-like structure, and the second sub-cone surface between the left side of the dotted line L2 and the right side of the cone top of the leftmost pyramid-like structure. For the middle pyramid-like structure, in the cone surface, the undulation of the first sub-cone surface located on the left side of the dotted line L3 and the first sub-cone surface located on the right side of the dotted line L4 is smaller than the undulation of the second sub-cone surface located between the right side of the dotted line L3 and the left side of the cone top of the middle pyramid-like structure, and the undulation of the second sub-cone surface between the left side of the dotted line L4 and the right side of the cone top of the middle pyramid-like structure; or, the roughness of the first sub-cone surface located on the left side of the dotted line L3 and the first sub-cone surface located on the right side of the dotted line L4 is smaller than the roughness of the second sub-cone surface located between the right side of the dotted line L3 and the left side of the cone top of the middle pyramid-like structure, and the second sub-cone surface between the left side of the dotted line L4 and the right side of the cone top of the middle pyramid-like structure. For the rightmost pyramid-like structure, in the cone surface, the undulation of the first sub-cone surface located on the left side of the dotted line L5 and the first sub-cone surface located on the right side of the dotted line L6 is smaller than the undulation of the second sub-cone surface located between the right side of the dotted line L5 and the left side of the cone top of the rightmost pyramid-like structure, and the undulation of the second sub-cone surface between the left side of the dotted line L6 and the right side of the cone top of the rightmost pyramid-like structure; or, the roughness of the first sub-cone surface located on the left side of the dotted line L5 and the first sub-cone surface located on the right side of the dotted line L6 is smaller than the roughness of the second sub-cone surface located between the right side of the dotted line L5 and the left side of the cone top of the rightmost pyramid-like structure, and the second sub-cone surface between the left side of the dotted line L6 and the right side of the cone top of the rightmost pyramid-like structure.

[0112] Optionally, referring to Figure 3, in the passivation anti-reflection layer 2, the thickness of the first part is greater than the thickness of the passivation anti-reflection layer 2 located at the cone top 11; specifically, in the silicon substrate 1, the situation of the part adjacent to the pyramid-like structure is more complicated, and usually there are more gaps; the situation of the position adjacent to the adjacent pyramid-like structures is also more complicated, and usually there are more gaps; therefore, these positions require a thicker passivation anti-reflection layer to achieve a better passivation effect, so the first sub-cone surface adjacent to these positions also requires a thicker passivation anti-reflection layer to achieve a better passivation effect, and the gaps at the cone top are usually less, and only a thinner passivation anti-reflection layer is required to achieve a better passivation effect. Therefore, in the present application, the thickness of the first part of the passivation anti-reflection layer 2 is greater than the thickness of the passivation anti-reflection layer 2 located at the cone top 11. On the one hand, it can ensure that each position has an excellent passivation effect, and the present application sets the thickness of the passivation anti-reflection layer according to the passivation requirements, which can reduce waste. At the same time, in the present application, after the light enters the passivation anti-reflection layer of different thicknesses, the optical path of the light will change more times, which can increase the optical distance. Combined with the velvet structure of the present application, the absorption of light can be further increased, the light trapping effect is better, the short-circuit current can be further increased, and the photoelectric conversion efficiency of the solar cell can be further improved. The appearance of the solar cell is uniformly black, which is more beautiful.

[0113] For example, as shown in FIG3 , for the leftmost pyramid-like structure, the thickness of the first portion of the passivation anti-reflection layer 2 located to the left of the dotted line L1 and the first portion to the right of the dotted line L2 is greater than the thickness of the apex 11 of the leftmost pyramid-like structure in the passivation anti-reflection layer 2. For the middle pyramid-like structure, the thickness of the first portion of the passivation anti-reflection layer 2 located to the left of the dotted line L3 and the first portion to the right of the dotted line L4 is greater than the thickness of the apex 11 of the middle pyramid-like structure in the passivation anti-reflection layer 2. For the rightmost pyramid-like structure, the thickness of the first portion of the passivation anti-reflection layer 2 located to the left of the dotted line L5 and the first portion to the right of the dotted line L6 is greater than the thickness of the apex 11 of the rightmost pyramid-like structure in the passivation anti-reflection layer 2.

[0114] 3 , the portion between the dotted line L2 and the dotted line L3 is where the leftmost pyramid-like structure and the middle pyramid-like structure are adjacent, and the portion between the dotted line L4 and the dotted line L5 is where the rightmost pyramid-like structure and the middle pyramid-like structure are adjacent. Optionally, referring to Figure 3, the thickness of the portion of the passivation anti-reflection layer 2 located at the position adjacent to the adjacent pyramid-like structures is greater than the thickness of the portion of the passivation anti-reflection layer 2 located at the cone top 11; specifically, in the silicon substrate 1, the position where the adjacent pyramid-like structures are adjacent is relatively complicated, and usually has more gaps. Therefore, these positions require a thicker passivation anti-reflection layer to achieve a better passivation effect, while the gaps at the cone top are usually smaller, and only a thinner passivation anti-reflection layer is required to achieve a better passivation effect. Therefore, in the present application, the thickness of the portion of the passivation anti-reflection layer 2 located at the position adjacent to the adjacent pyramid-like structures is greater than the thickness of the portion of the passivation anti-reflection layer 2 located at the cone top 11. On the one hand, it can ensure that each position has an excellent passivation effect, and the present application sets the thickness of the passivation anti-reflection layer according to the passivation requirements, which can reduce waste. At the same time, in the present application, after light enters the passivation anti-reflection layer of different thicknesses, the light's optical path undergoes more changes, which can increase the optical path. Combined with the velvet structure of the present application, this can further increase light absorption, resulting in a better light trapping effect, further increasing the short-circuit current, and further improving the photoelectric conversion efficiency of the solar cell. Furthermore, the solar cell has a uniform black appearance, which is more aesthetically pleasing. As shown in FIG3 , the thickness of the portion of the passivation anti-reflection layer 2 between the dotted lines L2 and L3 is greater than the thickness of the pyramid-like structure apex 11 located on the leftmost side of the passivation anti-reflection layer 2, and is also greater than the thickness of the pyramid-like structure apex 11 located in the middle of the passivation anti-reflection layer 2. In FIG3 , the thickness of the portion of the passivation anti-reflection layer 2 between the dotted lines L4 and L5 is greater than the thickness of the pyramid-like structure apex located on the rightmost side of the passivation anti-reflection layer 2, and is also greater than the thickness of the pyramid-like structure apex located in the middle of the passivation anti-reflection layer 2.

[0115] Optionally, referring to Figure 3, in the passivation anti-reflection layer 2, the thickness of the portion located at the position adjacent to the adjacent pyramid-like structures is greater than the thickness of the second portion of the passivation anti-reflection layer 2; specifically, in the silicon substrate 1, the position where the adjacent pyramid-like structures are adjacent is relatively complicated, and usually there are more gaps. Therefore, these positions require a thicker passivation anti-reflection layer to achieve a better passivation effect, while the gaps at the top of the cone are usually fewer, and only a thinner passivation anti-reflection layer is required to achieve a better passivation effect. Therefore, a relatively thin passivation anti-reflection layer is also required on the second sub-cone surface adjacent to the top of the cone to achieve a better passivation effect. Therefore, in the present application, the thickness of the portion of the passivation anti-reflection layer 2 located at the position adjacent to the adjacent pyramid-like structures is greater than the thickness of the second portion of the passivation anti-reflection layer 2. On the one hand, it can ensure that each position has an excellent passivation effect, and the present application sets the thickness of the passivation anti-reflection layer according to the passivation requirements, which can reduce waste. At the same time, in the present application, after the light enters the passivation anti-reflection layer of different thicknesses, the optical path of the light will change more times, which can increase the optical distance. Combined with the velvet structure of the present application, the absorption of light can be further increased, the light trapping effect is better, the short-circuit current can be further increased, and the photoelectric conversion efficiency of the solar cell can be further improved. The appearance of the solar cell is uniformly black, which is more beautiful.

[0116] For example, in Figure 3, the thickness of the portion of the passivation anti-reflection layer 2 between the dotted lines L2 and L3 is greater than the thickness of the second portion of the passivation anti-reflection layer 2 between the dotted lines L1 and L2, excluding the cone apex, and is also greater than the thickness of the second portion of the passivation anti-reflection layer 2 between the dotted lines L3 and L4, excluding the cone apex. In Figure 3, the thickness of the portion of the passivation anti-reflection layer 2 between the dotted lines L4 and L5 is greater than the thickness of the second portion of the passivation anti-reflection layer 2 between the dotted lines L5 and L6, excluding the cone apex, and is also greater than the thickness of the second portion of the passivation anti-reflection layer 2 between the dotted lines L3 and L4, excluding the cone apex.

[0117] Optionally, in the passivation anti-reflection layer 2, the thickness non-uniformity between the first part and the second part is greater than 4%, and the thickness non-uniformity is: the absolute value of the difference between the first thickness at the first position in the first part and the second thickness at the second position in the second part along the same direction close to the top of the cone, divided by the sum of the first thickness and the second thickness, wherein the first position in the first part is any position in the first part, and the second position in the second part is any position in the second part. That is to say, here, the first part and the second part are limited to the same direction near the top of the cone 11, and the thickness non-uniformity of the first part and the second part in the passivation anti-reflection layer 2 is greater than 4%; specifically, in the silicon substrate 1, the situation at the adjacent positions of adjacent pyramid-like structures is more complicated, and usually there are more gaps. Therefore, these positions require a thicker passivation anti-reflection layer to achieve a better passivation effect, while the gaps at the top of the cone are usually less, and only a thinner passivation anti-reflection layer is required to achieve a better passivation effect. Therefore, a relatively thin passivation anti-reflection layer is also required on the second sub-cone surface adjacent to the top of the cone to achieve a better passivation effect. Therefore, in the present application, the thickness non-uniformity of the first part and the second part in the passivation anti-reflection layer 2 is greater than 4%. On the one hand, it can ensure that each position has an excellent passivation effect, and the present application sets the thickness of the passivation anti-reflection layer according to the passivation requirements, which can reduce waste. At the same time, in the present application, after the light enters the passivation anti-reflection layer of different thicknesses, the optical path of the light will change more times, which can increase the optical distance. Combined with the velvet structure of the present application, the absorption of light can be further increased, the light trapping effect is better, the short-circuit current can be further increased, and the photoelectric conversion efficiency of the solar cell can be further improved. The appearance of the solar cell is uniformly black, which is more beautiful.

[0118] For example, in the passivation anti-reflection layer 2, the thickness unevenness of the first part and the second part along the same direction close to the top of the cone can be: 4.001%, or 4.03%, or 4.09%, or 4.2%, or 4.31%, or 4.5%, or 4.9%, or 5%, or 5.2%, or 6%, or 7.23%, or 8%, or 9.2%, or 10.3%, or 11.2%, or 13.46%, or 15%, or 18%, or 20%, or 22%, or 25%.

[0119] Optionally, the solar cell may further include: an aluminum oxide layer (not shown) located between the silicon substrate 1 and the passivation anti-reflection layer 2. The thickness fluctuation of the aluminum oxide layer is less than the thickness fluctuation of the passivation anti-reflection layer 2; wherein the thickness fluctuation refers to the degree of thickness variation; the thickness fluctuation of the aluminum oxide layer can specifically be the absolute value of the difference between the thickness of the aluminum oxide layer at the fifth position and the thickness of the aluminum oxide layer at the sixth position; the thickness fluctuation of the passivation anti-reflection layer 2 can specifically be the absolute value of the difference between the thickness of the passivation anti-reflection layer 2 at the seventh position and the thickness of the passivation anti-reflection layer 2 at the eighth position. In the thickness direction of the silicon substrate, the projections of the fifth position and the seventh position coincide, and the projections of the sixth position and the eighth position coincide. The fifth position and the sixth position are any two different positions in the aluminum oxide layer. Specifically, the aluminum oxide layer is typically obtained by atomic layer deposition, and the surface morphology has little effect on atomic layer deposition. The thickness of the aluminum oxide layer is relatively uniform, and the aluminum oxide layer has better passivation performance.

[0120] It should be noted that the thickness of the aluminum oxide layer may be 3 nm (nanometers) to 7 nm. The thickness of the aluminum oxide layer may also be measured by a transmission electron microscope, etc., and is not specifically limited thereto. For example, the thickness fluctuation of the aluminum oxide layer can be 0.0001nm-3nm, for example, it can be 0.001nm, 0.005nm, 0.008nm, 0.01nm, 0.02nm, 0.03nm, 0.04nm, 0.05nm, 0.06nm, 0.07nm, 0.08nm, 0.1nm, 0.2nm, 0.3nm, 0.4nm, 0.5nm, 0.6nm, 0.7nm, 0.8nm, 1nm, 2nm, 2.3nm, 3nm, and the thickness fluctuation of the passivation anti-reflection layer 2 can be 3.5nm-50nm, for example, it can be 3.5nm, 4nm, 4.8nm, 6nm, 7nm, 8nm, 9nm, 10nm, 12nm, 12.5nm, 13nm. 14nm, 15nm, 16nm, 17nm, 18nm, 20nm, 25nm, 30nm, 36nm, 40nm, 45nm, 50nm.

[0121] Optionally, the aluminum oxide layer includes: a third portion located on the first sub-cone surface, and a fourth portion located on the second sub-cone surface. The thickness non-uniformity between the first portion and the second portion in the passivation anti-reflection layer 2 is greater than the thickness non-uniformity between the third portion and the fourth portion in the aluminum oxide layer. The thickness non-uniformity between the first portion and the second portion in the passivation anti-reflection layer 2 refers to the above description and will not be repeated here. The thickness non-uniformity between the third portion and the fourth portion in the aluminum oxide layer is: the absolute value of the difference between the third thickness at the third position in the third portion and the fourth thickness at the fourth position in the fourth portion in the same direction close to the top of the cone, divided by the sum of the third thickness and the fourth thickness. Here, the third portion and the fourth portion are both limited to the same direction close to the top of the cone. Here, the third position in the third portion is: any position in the third portion, and the fourth position in the fourth portion is: any position in the fourth portion. The thickness unevenness between the first and second parts of the passivation anti-reflection layer 2 is greater than the thickness unevenness between the third and fourth parts of the aluminum oxide layer, that is, the thickness unevenness of the passivation anti-reflection layer 2 is greater. The thickness of the passivation anti-reflection layer 2 matches the passivation requirements, which can ensure that each position has an excellent passivation effect. In addition, the thickness of the passivation anti-reflection layer is set according to the passivation requirements, which can reduce waste. At the same time, in the present application, after the light enters the passivation anti-reflection layer of different thicknesses, the optical path of the light will change more times, which can increase the optical path. In combination with the velvet structure of the present application, the absorption of light can be further increased, the light trapping effect is better, the short-circuit current can be further increased, and the photoelectric conversion efficiency of the solar cell can be further improved. The appearance of the solar cell is uniform black, which is more beautiful. It should be noted that the specific difference between the two thickness unevennesses is not specifically limited.

[0122] Optionally, the passivation anti-reflection layer 2 includes: a front passivation anti-reflection layer located on the light-facing side of the silicon substrate 1, and a back passivation anti-reflection layer located on the backlight side of the silicon substrate 1. At two opposing locations along the thickness direction of the silicon substrate 1, the back passivation anti-reflection layer has a greater thickness than the front passivation anti-reflection layer. Specifically, as the thickness of the passivation anti-reflection layer increases, its passivation effect improves, while its anti-reflection effect decreases appropriately. For the passivation anti-reflection layer, the anti-reflection requirement on the backlight side is lower than that on the light-facing side. Therefore, appropriately increasing the thickness of the back passivation anti-reflection layer ensures excellent passivation performance on the backlight side, while appropriately reducing the thickness of the front passivation anti-reflection layer can achieve a balanced passivation performance and anti-reflection effect.

[0123] Optionally, at two opposite locations in the thickness direction of the silicon substrate 1, the difference between the thickness of the back passivation anti-reflection layer and the thickness of the front passivation anti-reflection layer is greater than or equal to 15 nm and less than or equal to 40 nm. The appropriate setting of the difference between the two fully ensures excellent passivation performance on the backlight side, while simultaneously achieving good passivation performance and anti-reflection effects on the light-facing side, and avoids waste. For example, the thickness of the back passivation anti-reflection layer can be 85 nm to 100 nm, or approximately 95 nm, and the thickness of the front passivation anti-reflection layer can be 60 nm to 70 nm, or approximately 65 nm. Here, in the thickness direction of the silicon substrate 1, at two relative positions, the difference between the thickness of the back passivation anti-reflection layer and the thickness of the front passivation anti-reflection layer can be: 15nm, or 16.3nm, or 17.9nm, or 19.4nm, or 20.94nm, or 22.6nm, or 24.92nm, or 27.5nm, or 30.3nm, or 32.6nm, or 33.9nm, or 35.7nm, or 36.9nm, or 18.34nm, or 40nm.

[0124] This application also provides a photovoltaic module, comprising: a plurality of any of the aforementioned solar cells; the number of solar cells in the photovoltaic module is not specifically limited. The photovoltaic module may also include an encapsulating film located on both sides of the solar cells. Other structures of the photovoltaic module are not specifically limited.

[0125] The present application also provides a method for preparing a solar cell, which is used to prepare any of the aforementioned solar cells. The method comprises: performing a first texturing on a silicon substrate 1, cleaning the silicon substrate 1 after the first texturing, and performing a second texturing on the cleaned silicon substrate 1. The second texturing is performed by irregularly etching the textured surface structure obtained by the first texturing. The second texturing can reduce the inner dimension of the bottom contour line of the pyramid-like structure away from the top of the cone, making the cone surface rougher, etc., thereby forming a sharper pyramid-like structure.

[0126] Optionally, during the second texturing process: the components of the additives in the texturing liquid may include: sodium benzoate, defoaming agent, surfactant; and / or, the mass content of the additives in the texturing liquid is 0.01% to 5%; and / or, the temperature of the texturing liquid is 50°C to 85°C; and / or, the duration of the second texturing is 30s (seconds) to 400s, and the process parameters for the second texturing are relatively suitable, and it is easy to prepare any of the aforementioned velvet structures. The velvet structure of the present application can be obtained by adjusting the process conditions of the second texturing, or by selecting different additives for the second texturing than for the first texturing. The aforementioned texturing method can also be referred to as wet texturing. The actual structure of the velvet structure obtained by wet texturing is relatively complex, and it is difficult to ensure the consistency of the morphology of each pyramid-like structure in the velvet structure. It should be understood that as long as the morphology of most of the pyramid-like structures in the velvet structure meets the characteristics of the morphological structure described above, the effect described in the present application can be achieved.

[0127] The present application is further explained below with reference to specific embodiments.

[0128] Example

[0129] In the first step, the single crystal silicon wafer is subjected to preliminary alkali texturing to form a pyramid structure on the surface. The specific type of alkaline solution is not specifically limited, and can be selected from at least one of sodium hydroxide (NaOH) solution and potassium hydroxide (KOH) solution, and the height of the pyramid formed is 0.5μm to 3μm. More specifically, the texturing solution in the first step can be: a NaOH solution or KOH solution with a mass concentration of 1% to 9% is mixed with additive A to form a first reaction liquid; the first texturing is completed within a temperature range of 60°C to 85°C and for 150s to 600s. Specifically, the cleaned single crystal silicon wafer is placed in the above-mentioned first reaction liquid, and the first texturing is carried out within the aforementioned temperature range and time range to form a pyramid structure. The height of the pyramid structure is between 0.5μm and 3μm. The main components of additive A include surfactants, dispersants, and emulsifiers. In the first texturing process, the added mass ratio of additive A is 0.01% to 5%.

[0130] In the second step, the single crystal silicon wafer that has been texturized with alkali in the first step is washed with DI (deionized water) to remove the residual chemical solution.

[0131] In a third step, the pyramid surface after the DI water wash is subjected to auxiliary polishing and a second texturing etching using a polishing and texturing solution. An additive is used to adjust the etching rate of the solution on various crystal directions of the crystalline silicon. Irregular etching is performed on the conical surface of the pyramid surface, and the pyramid is further etched inward, gradually reducing the width of the pyramid and increasing the angle between the side edges and the first plane, thereby forming a suede structure with a pyramid-like structure having a lower reflectivity. During the second texturing process, the additives in the texturing solution may include sodium benzoate, a defoaming agent, and a surfactant. The weight content of the additives in the texturing solution is 0.01% to 5%. The texturing solution in the second step may be a mixture of a 1% to 15% NaOH solution or a KOH solution with sodium benzoate, a defoaming agent, and a surfactant. The temperature of the texturing solution is 50° C. to 85° C., such as 60° C. to 85° C., and the duration of the second texturing process is 30 seconds to 400 seconds, such as 30 seconds to 240 seconds. The NaOH solution or KOH solution here can also be replaced by an organic base, and the organic base can be one of tetramethylammonium hydroxide, ethylenediamine, ethylenetriamine, methylenediamine and tetrabutylammonium hydroxide.

[0132] In the fourth step, the single crystal silicon wafers treated in the third step are washed with DI water, alkali and hydrogen peroxide mixture to remove surface chemical residues. In the fourth step, the total cleaning time is 60s to 150s, and the cleaning temperature is 50℃ to 70℃.

[0133] In the fifth step, the structure obtained in the fourth step is subjected to ozone washing, acid washing, etc. to form a hydrophobic surface to facilitate subsequent production processes.

[0134] In the fifth step, in the final pyramid-like structure, the angle between the side edge and the first surface ranges from 50° to 85°. More specifically, the side edge is divided into an upper section adjacent to the top of the cone, a lower section farthest from the top of the cone, and a middle section located between the lower section and the upper section. The length of the lower section accounts for 1 / 4 of the length of the side edge, the length of the middle section accounts for 1 / 2 of the length of the side edge, and the length of the upper section accounts for 1 / 4 of the length of the side edge. In other words, the portion of the pyramid-like structure that is away from the top of the cone is the lower portion of the pyramid-like structure, the height of the lower portion accounts for 1 / 4 of the height of the pyramid-like structure, and the lower section is the portion corresponding to the lower portion of the side edge. The portion of the pyramid-like structure that is adjacent to the top of the cone is the upper portion of the pyramid-like structure, the height of the upper portion accounts for 1 / 4 of the height of the pyramid-like structure, and the upper section is the portion corresponding to the upper portion of the side edge. The portion of the pyramid-like structure located between the upper and lower portions is the middle portion, and its height accounts for half the height of the pyramid-like structure. The middle section is the portion of the side edge corresponding to the middle portion. The angle between the lower section and the aforementioned first plane is 50° to 55°, the angle c between the upper section and the first plane is 55° to 80°, and the angle between the middle section and the first plane is 55° to 85°. The velvet structure of the silicon substrate of the solar cell finally prepared in this embodiment is shown in Figures 1 to 3 and 5. The maximum internal dimension of the bottom contour line of the pyramid-like structure is 10nm to 200nm.

[0135] The sixth step is to continue preparing a passivation anti-reflection layer and other structures on the single crystal silicon wafer obtained in the fifth step to obtain a solar cell.

[0136] Comparative Example

[0137] The comparative example only includes the first step, fourth step, fifth step and sixth step in the aforementioned embodiment, and the first step, fourth step, fifth step and sixth step are performed in sequence, and the first step, fourth step, fifth step and sixth step correspond to the first step, fourth step, fifth step and sixth step in the embodiment respectively.

[0138] Under the same test environment, the reflectivity of the side with the suede structure in the solar cells of the embodiment and the comparative example was tested. The test results are shown in Figure 6. In Figure 6, the horizontal axis is the wavelength (Wavelength) of the light irradiating the solar cell, in nm, and the vertical axis is the reflectivity (Reflectance). The blue curve (the curve at the bottom) in Figure 6 is used to characterize the corresponding reflectivity in the embodiment, and the red curve (the curve at the top) is used to characterize the corresponding reflectivity in the comparative example. It can be concluded that within most of the wavelength range that can be used by the solar cell, the reflectivity of the suede structure in the solar cell of the embodiment is lower.

[0139] Under the same test environment, the electrical properties of the solar cells of the embodiment and the comparative example were tested. The test results are shown in the table below.

[0140] Comparative table of electrical properties of solar cells of test examples and comparative examples

[0141] In the above table, Eta refers to the photoelectric conversion efficiency, Voc refers to the open-circuit voltage, Isc refers to the short-circuit current, and FF refers to the conversion factor. As can be seen from the above table, the photoelectric conversion efficiency, open-circuit voltage, short-circuit current, and conversion factor of the solar cell of the embodiment are all higher than those of the solar cell of the comparative example. This is mainly due to the fact that, by improving the velvet structure in the embodiment, the reflectivity is reduced, the light trapping effect is enhanced, the short-circuit current is increased, and ultimately the photoelectric conversion efficiency of the solar cell is improved.

[0142] It should be noted that throughout the text, contents with the same name can refer to each other. In order to avoid repetition, the relevant parts will not be repeated.

[0143] It should be noted that, for the sake of simplicity, the method embodiments are described as a series of action combinations, but those skilled in the art should be aware that the embodiments of the present application are not limited by the order of the actions described, because according to the embodiments of the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of the present application.

[0144] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0145] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose of this application and the scope of protection of the claims, all of which are protected by this application.

Claims

1. A solar cell comprising: A silicon substrate, wherein the surface of the silicon substrate has a velvet structure, wherein the velvet structure comprises: a plurality of pyramid-like structures; the pyramid-like structures comprise: a cone top, a cone surface, and at least two side edges; The side edge includes: a lower section away from the cone top, and a first section, wherein the first section is the remaining portion of the side edge except the lower section, and the bending degree of the lower section is smaller than that of the first section.

2. The solar cell according to claim 1, wherein the conical surface has a branched texture, and the conical surface of the pyramid-like structure comprises: A first sub-cone surface away from the top of the cone, and a second sub-cone surface, wherein the second sub-cone surface is the remaining part of the cone surface of the pyramid-like structure except the first sub-cone surface; the number of the branched texture in the second sub-cone surface is greater than the number of the branched texture in the first sub-cone surface.

3. The solar cell according to claim 1, wherein in the velvet structure, at least two of the pyramid-like structures are fused together at least at their lower portions away from the cone tops, and the cone tops of the fused pyramid-like structures are separated. 4 . The solar cell according to claim 3 , wherein the cone tops of the integrated pyramid-like structures have height differences or are evenly distributed. 5 . The solar cell according to claim 4 , wherein in each of the integrated pyramid-like structures, a height difference between the cone tops of two of the pyramid-like structures is greater than 0 and less than or equal to 1.6 microns.

6. The solar cell according to claim 1, wherein in the same pyramid-like structure, of the two side edges located on both sides of the pyramid top, along the direction of the thickness of the silicon substrate, the size of one side edge is larger than the size of the other side edge. 7 . The solar cell according to claim 1 , wherein the lower segment is a straight line segment or a line segment with at most two inflection points; and the first segment is a broken line segment and / or a curved line segment. The solar cell according to claim 1 , wherein the length of the lower segment is at least 1 / 10 of the length of the side edge. 9 . The solar cell according to claim 8 , wherein the angle between the lower segment and the first plane is smaller than the angle between the first segment and the first plane; and the first plane is a plane perpendicular to the thickness direction of the silicon substrate.

10. The solar cell according to claim 9, wherein the first section consists of an upper section and a middle section, the upper section is adjacent to the cone top, and the middle section is located between the lower section and the upper section; the length of the upper section accounts for at least 1 / 10 of the length of the side edge, and the length of the middle section accounts for at least 2 / 5 of the length of the side edge.

11. The solar cell according to claim 10, wherein the angle between the lower section and the first plane is 50° to 55°, the angle between the upper section and the first plane is 55° to 80°, and the angle between the middle section and the first plane is 55° to 85°. 12 . The solar cell according to claim 1 , wherein the light-facing surface and / or the backlight surface of the silicon substrate has the textured structure.

13. A solar cell comprising: A silicon substrate having a surface having a velvet structure, the velvet structure comprising: a plurality of pyramid-like structures; the pyramid-like structures comprising: a cone surface and a cone apex; the cone surface of the pyramid-like structure comprising: a first sub-cone surface away from the cone apex, and a second sub-cone surface, the second sub-cone surface being the remaining portion of the cone surface of the pyramid-like structure excluding the first sub-cone surface; The cone top of the pyramid-like structure and the second sub-cone surface of the cone surface of the pyramid-like structure have a cluster of nested ring-like textures. 14 . The solar cell according to claim 13 , wherein in the textured structure, at least the first sub-cone surfaces of at least two of the pyramid-like structures are fused into one, and the cone tops of the fused pyramid-like structures are separated.

15. The solar cell according to claim 14, wherein in each of the integrated pyramid-like structures, the annular-like textures on the cone surfaces of different pyramid-like structures are distributed separately; Alternatively, in the integrated pyramid-like structures, the annular-like textures in the cone surfaces of different pyramid-like structures partially overlap. 16 . The solar cell according to claim 13 , wherein in a cluster of the quasi-annular textures, the quasi-annular textures at different positions along the height direction of the quasi-pyramid structure are distributed in an overlapping manner.

17. According to the solar cell according to any one of claims 13 to 15, in the conical surface of the pyramid-like structure, the ring-like texture extends from a position adjacent to the top of the cone to at most a position on the conical surface corresponding to a portion of the pyramid-like structure whose height difference from the top of the cone is 2 / 3 of the height of the pyramid-like structure.

18. The solar cell according to any one of claims 13 to 15, wherein the portion of the pyramid-like structure away from the top is a lower portion of the pyramid-like structure, and a height of the lower portion accounts for at least 1 / 10 of a height of the pyramid-like structure; The first sub-cone surface is: an area corresponding to the lower portion of the conical surface of the pyramid-like structure; The second sub-conical surface is: a region of the conical surface of the pyramid-like structure that is closer to the cone top than the first sub-conical surface.

19. A solar cell comprising: A silicon substrate, wherein the surface of the silicon substrate has a velvet structure, wherein the velvet structure includes: a plurality of pyramid-like structures; the pyramid-like structures include: a cone surface and a cone top; The cone top of the pyramid-like structure and the cone surface of the pyramid-like structure have: a skirt-like texture and / or a rose-like texture.

20. The solar cell according to claim 19, wherein the conical surface of the pyramid-like structure comprises: a first sub-conical surface away from the cone top, and a second sub-conical surface, wherein the second sub-conical surface is the remaining portion of the cone surface of the pyramid-like structure except the first sub-conical surface; The skirt-shaped texture and / or the rose-shaped texture are located in the cone top and the second sub-cone surface of the pyramid-like structure.

21. The solar cell according to claim 20, wherein a portion of the pyramid-like structure away from the top is a lower portion of the pyramid-like structure, and a height of the lower portion accounts for at least 1 / 10 of a height of the pyramid-like structure; The first sub-cone surface is: an area corresponding to the lower portion of the conical surface of the pyramid-like structure; The second sub-conical surface is: a region of the conical surface of the pyramid-like structure that is closer to the cone top than the first sub-conical surface.

22. A photovoltaic module comprising: A plurality of solar cells according to any one of claims 1 to 21.

Images