Solar cells and solar modules

Abstract

The present application provides a solar cell and a solar module, which relate to the technical field of photovoltaic power generation. The solar cell includes a silicon substrate and a passivation anti-reflection layer on the silicon substrate. The surface of the silicon substrate has a textured structure, and the textured structure includes a plurality of approximately pyramidal structures, each of which has a pyramidal surface and an apex. The pyramidal surface of the approximately pyramidal structure includes a first sub-pyramid surface and a second sub-pyramid surface away from the apex. The first sub-pyramid surface and the second sub-pyramid surface of the approximately pyramidal structure have different surface morphologies. The passivation anti-reflection layer includes a first portion on the first sub-pyramid surface and a second portion on the second sub-pyramid surface. The thickness of the first portion of the passivation anti-reflection layer is greater than the thickness of the second portion along the same direction toward the apex. This application ensures excellent passivation effect at any position, reduces waste, improves light absorption, achieves good light trapping effect, and improves short-circuit current and photoelectric conversion efficiency.

Description

[Technical Field]

[0001] The present application relates to the technical field of photovoltaics, and in particular to solar cells and solar modules.

[0002] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority from a Chinese patent application bearing application number 202410175427.9 and entitled "Solar Cell and Solar Module" filed with the China Patent Office on February 7, 2024, the entire contents of which are incorporated herein by reference. [Background technology]

[0003] Solar cells, which convert light energy into electrical energy through the photovoltaic effect, have the prospect of widespread application by utilizing clean energy.

[0004] In solar cells, functional film layers such as passivation anti-reflection layers are provided, particularly on the surface of the cell, for the purposes of inactivating defects and achieving a good anti-reflection effect to increase short-circuit current, etc. However, conventional solar cells do not take into consideration that the required passivation effect and anti-reflection effect differ depending on the position of the texture structure, so a thick passivation film can affect light absorption, or a thin passivation film can affect the passivation effect, further affecting the performance of the cell. Summary of the Invention [Problem to be solved by the invention]

[0005] The present application provides a solar cell and a solar module, and aims to solve the problem that it is difficult to achieve both a passivation effect and an anti-reflection effect in a solar cell due to the texture structure. [Means for solving the problem]

[0006] In a first aspect of the present application, 1. A solar cell comprising: a silicon substrate; and a passivation anti-reflective layer overlying the silicon substrate, The surface of the silicon substrate has a textured structure, the textured structure includes a plurality of approximately pyramidal structures, each of which includes a pyramidal surface and an apex, the pyramidal surface of the approximately pyramidal structure including a first sub-pyramidal surface and a second sub-pyramidal surface that are spaced apart from the apex, the second sub-pyramidal surface being the remaining portion of the pyramidal surface of the approximately pyramidal structure other than the first sub-pyramidal surface, and the first sub-pyramidal surface and the second sub-pyramidal surface of the pyramidal surface of the approximately pyramidal structure have different surface forms; The solar cell includes a passivation anti-reflection layer having a first portion on a first sub-cone surface and a second portion on a second sub-cone surface, and the thickness of the first portion of the passivation anti-reflection layer is greater than the thickness of the second portion along the same direction approaching the apex.

[0007] In the present application, the first and second sub-conical surfaces of the approximately pyramidal structure have different surface morphologies. By making the shape of the pyramidal surfaces of this approximately pyramidal structure more irregular, the textured structure has a larger specific surface area, lower reflectivity, better light trapping effect, and increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. The solar cell also has a uniform black appearance and a more attractive appearance. The conditions adjacent to the approximately pyramidal structures on a silicon substrate are often complex and often contain many voids. The conditions adjacent to adjacent approximately pyramidal structures are also complex and often contain many voids. Therefore, a thick passivation anti-reflection layer is required at these locations to achieve a good passivation effect. Therefore, a thick passivation anti-reflection layer is also required on the first sub-conical surfaces adjacent to these locations to achieve a good passivation effect. On the other hand, the apex often has fewer voids, so a thin passivation anti-reflection layer can still achieve a good passivation effect. As a result, even on the second sub-conical surface adjacent to the apex, a good passivation effect can be achieved even with a relatively thin passivation anti-reflection layer. Therefore, in the present application, by making the thickness of the first portion greater than the thickness of the second portion along the same direction toward the apex, a good passivation effect can be achieved at any position. In addition, in the present application, the thickness of the passivation anti-reflection layer is set according to passivation needs, thereby reducing waste. Furthermore, in the present application, after light enters the passivation anti-reflection layer with different thicknesses, the optical path changes more times, thereby lengthening the optical path length. This, in cooperation with the textured structure of the present application, further improves light absorption, improves the light trapping effect, further increases the short-circuit current, further enhances the photoelectric conversion efficiency of the solar cell, and also gives the solar cell a uniform black appearance, making it more attractive. As a result, the present application not only ensures a good passivation effect at every position on the solar cell, but also significantly improves the anti-reflection effect and reduces waste.

[0008] Optionally, the waviness of the first sub-conical surface is smaller than the waviness of the second sub-conical surface; Alternatively, the roughness of the first sub-conical surface is smaller than the roughness of the second sub-conical surface.

[0009] Optionally, the thickness of the first portion is greater than the thickness of the apex portion of the passivation anti-reflective layer; and / or, the thickness of the portion of the passivation antireflection layer on the adjacent portions of the adjacent pyramidal structures is greater than the thickness of the portion of the passivation antireflection layer on the apex; And / or, the thickness of the portion of the passivation anti-reflection layer located on the adjacent portions of the adjacent generally pyramidal structures is greater than the thickness of the second portion.

[0010] Optionally, in the passivation anti-reflection layer, the thickness variation between the first portion and the second portion is greater than 4%, and the thickness variation is the absolute value of the difference between a first thickness at a first position in the first portion and a second thickness at a second position in the second portion along the same direction approaching the apex, divided by the sum of the first thickness and the second thickness.

[0011] Optionally, the solar cell further comprises an aluminum oxide layer between the silicon substrate and the passivation anti-reflective layer; the aluminum oxide layer includes a third portion on the first sub-conical surface and a fourth portion on the second sub-conical surface; the thickness variation of the first and second portions of the passivation anti-reflection layer is greater than the thickness variation of the third and fourth portions of the aluminum oxide layer; the thickness variation between the first portion and the second portion in the passivation anti-reflection layer is calculated by dividing the absolute value of the difference between a first thickness at a first position in the first portion and a second thickness at a second position in the second portion along the same direction approaching the apex by the sum of the first thickness and the second thickness; The thickness variation 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 along the same direction approaching the apex, divided by the sum of the third thickness and the fourth thickness.

[0012] Optionally, the passivation anti-reflective layer includes a front surface passivation anti-reflective layer on the light-receiving side of the silicon substrate and a back surface passivation anti-reflective layer on the non-light-receiving side of the silicon substrate; At two positions opposite to each other in the thickness direction of the silicon substrate, the thickness of the rear surface passivation antireflection layer is greater than the thickness of the front surface passivation antireflection layer.

[0013] Optionally, the difference between the thickness of the back passivation anti-reflection layer and the thickness of the front passivation anti-reflection layer at two opposite positions in the thickness direction of the silicon substrate is 15 nm or more and 40 nm or less.

[0014] Optionally, the pyramidal surface of the substantially pyramidal structure has branched textures, and the number of branched textures on the second sub-pyramidal surface is greater than the number of branched textures on the first sub-pyramidal surface.

[0015] Optionally, the apex of the generally pyramidal structure and a second sub-pyramidal surface of the pyramidal surface of the generally pyramidal structure have a set of nested generally annular textures.

[0016] Optionally, in the set of generally annular textures, the contour of the generally annular texture becomes smaller along the height direction of the generally pyramidal structure as it approaches the apex.

[0017] Optionally, the portion of the substantially pyramidal structure away from the apex is a lower portion of the substantially pyramidal structure, and the height of the lower portion is at least 1 / 10 of the height of the substantially pyramidal structure; The first sub-pyramidal surface is a region corresponding to a lower portion of the pyramidal surface of the substantially pyramidal structure, The second sub-pyramidal surface is a region of the pyramidal surface of the approximately pyramidal structure that is closer to the apex than the first sub-pyramidal surface.

[0018] Optionally, the generally pyramidal structure further comprises a base contour away from the apex, with at least two points on the same base contour having different heights.

[0019] Optionally, the apex angle of the textured structure is between 55° and 90°.

[0020] Optionally, the height of the generally pyramidal structures is between 0.2 μm and 3 μm.

[0021] Optionally, the light-receiving surface and / or the non-light-receiving surface of the silicon substrate has a textured structure.

[0022] In a second aspect of the present application, there is provided a solar module including a plurality of any one of the solar cells described above. [Effects of the Invention]

[0023] The above solar cells and solar modules have the same or similar beneficial effects, and to avoid duplication, the description will be omitted here. [Brief explanation of the drawings]

[0024] In order to more clearly describe the technical solutions of the embodiments of the present application, the following will briefly describe the drawings used in describing the embodiments of the present application. Of course, the drawings described below are only a part of the embodiments of the present application, and those skilled in the art can conceive of other drawings based on these drawings without any creative efforts.

[0025] [Figure 1] 1 shows a scanning electron microscope image of a first type silicon substrate in an example of the present application. [Figure 2] 1 shows a scanning electron microscope image of a second type of silicon substrate in an example of the present application. [Figure 3] 1 shows a partial structural schematic diagram of a solar cell in an example of the present application. [Figure 4] 1 shows a scanning electron microscope image of a third type of silicon substrate in an example of the present application. [Figure 5] 1 shows a scanning electron microscope image of a fourth type of silicon substrate in an example of the present application. [Figure 6] 1 is a graph showing a comparison of the reflectance of solar cells in Examples of the present application and solar cells in Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, the technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application, and it should be understood that the described embodiments are only a part of the embodiments of the present application, and are not all of the embodiments. Based on the embodiments of the present application, all other embodiments that can be obtained by those skilled in the art without any creative efforts fall within the scope of protection of the present application.

[0027] In conventional solar cells, it is difficult to achieve both passivation and anti-reflection effects, which affects cell performance. The main reason is that as the thickness of the passivation anti-reflection layer increases, its passivation effect improves, but its anti-reflection effect decreases accordingly. This makes it difficult to achieve both passivation and anti-reflection effects. The main concept of the present application is to make the shape of the conical surfaces of the approximately pyramidal structure more irregular, thereby providing a larger specific surface area for the textured structure and improving the anti-reflection effect. Based on this textured structure, the thickness of the passivation anti-reflection layer at each position can be adjusted according to the passivation needs of the corresponding position, ensuring excellent passivation effect at all positions and reducing waste of material used in the passivation anti-reflection layer 2. Furthermore, after light enters a passivation anti-reflection layer with different thicknesses, the optical path changes more times, thereby lengthening the optical path length. This, in combination with the textured structure of the present application, further improves light absorption and enhances the light trapping effect. In other words, the present application improves both the antireflection effect and the passivation effect through cooperation between the texture structure and the passivation antireflection layer.

[0028] Figures 1, 2, and 5 are all scanning electron microscope images obtained by scanning mainly from the surface of the textured structure, while Figure 4 is a scanning electron microscope image obtained by scanning mainly from the apex to the bottom contour of the approximately pyramidal structure of the textured structure.

[0029] 1 to 5 , the present application provides a solar cell including a silicon substrate 1 and a passivation anti-reflection layer 2 on the silicon substrate 1. The silicon substrate 1 may have a doping element or may be intrinsic, but is not specifically limited thereto. The silicon substrate 1 may be a single-crystal silicon substrate, but is not specifically limited thereto. The passivation anti-reflection layer 2 here functions not only as a passivation layer but also as an anti-reflection layer. The material of the passivation anti-reflection layer 2 may be selected from silicon oxide and / or silicon oxynitride, but the specific material of the passivation anti-reflection layer 2 is not specifically limited. The passivation anti-reflection layer 2 can be formed by a method such as plasma-enhanced chemical vapor deposition (PECVD), and the specific method of forming the passivation anti-reflection layer 2 is also not specifically limited.

[0030] 1 to 5, the surface of a silicon substrate 1 has a textured structure, and the textured structure includes a plurality of approximately pyramidal structures. For example, in FIG. 1, three approximately pyramidal structures in the textured structure are depicted with black lines. The approximately pyramidal structures include a pyramidal surface and an apex 11. The apex 11 is the highest point of the approximately pyramidal structure. If the highest part of the approximately pyramidal structure is a plane consisting of multiple points at the same height, the apex here may be the geometric center of this plane. In the approximately pyramidal structure, the pyramidal surface of the approximately pyramidal structure is the set of all side surfaces of the approximately pyramidal structure, i.e., all surfaces of the approximately pyramidal structure other than the base and apex. The pyramidal surface of the approximately pyramidal structure connects the apex and the bottom contour, and the bottom contour is the contour of the lowest part of the approximately pyramidal structure. The pyramidal surface of the approximately pyramidal structure includes a first sub-pyramid surface away from the apex and a second sub-pyramid surface. In other words, the first sub-pyramid surface is the portion of the pyramidal surface farthest from the apex 11, i.e., the portion of the pyramidal surface closest to the silicon substrate, and the second sub-pyramid surface is the remaining portion of the pyramidal surface other than the first sub-pyramid surface. In Figure 3, the dashed lines L1 to L6 do not actually exist in the solar cell, but are merely notations for distinguishing the first sub-pyramid surface from the second sub-pyramid surface, or for distinguishing the lower segment from the first segment, which will be described later. For example, in Figure 3, in the case of the leftmost approximately pyramidal structure, the portion of the pyramidal surface between the right side of dashed line L1 and the left side of the apex of the leftmost approximately pyramidal structure, and the portion between the left side of dashed line L2 and the right side of the apex of the leftmost approximately pyramidal structure, are the second sub-pyramid surface, and the portion to the left of L1 and the portion to the right of L2 are the first sub-pyramid surface. In the case of the intermediate approximately pyramidal structure, the portion of the pyramidal surface between the right side of dashed line L3 and the left side of the apex of the intermediate approximately pyramidal structure and the portion between the left side of dashed line L4 and the right side of the apex of the intermediate approximately pyramidal structure are the second sub-pyramidal surface, and the portion to the left of L3 and the portion to the right of L4 are the first sub-pyramidal surface. In the case of the rightmost approximately pyramidal structure, the portion of the pyramidal surface between the right side of dashed line L5 and the left side of the apex of the rightmost approximately pyramidal structure and the left side of dashed line L6 and the right side of the apex of the rightmost approximately pyramidal structure are the second sub-pyramidal surface, and the portion to the left of L5 and the portion to the right of L6 are the first sub-pyramidal surface.

[0031] The surface morphology of the sub-conical surface may include waviness of the sub-conical surface or roughness of the sub-conical surface. Waviness mainly refers to the degree of undulations due to relatively large elevational structures on the surface, while roughness refers to the degree of unevenness due to minute protrusions and depressions on the surface. Referring to FIGS. 1 to 5 , in a conical surface having a substantially pyramidal structure, the fact that the first sub-conical surface and the second sub-conical surface away from the apex 11 have different surface morphologies means that the first sub-conical surface and the second sub-conical surface differ in waviness or roughness. In some cases, the number of protrusions and / or depressions on the second sub-conical surface may be greater than the number of protrusions and / or depressions on the first sub-conical surface. In other cases, the degree of protrusions and / or depressions on the second sub-conical surface may be greater than the degree of protrusions and / or depressions on the first sub-conical surface. In other cases, the distribution of protrusions and / or depressions on the second sub-conical surface may be less uniform than the distribution of protrusions and / or depressions on the first sub-conical surface. Alternatively, the height of the protrusions and / or the depth of the depressions on the second sub-pyramidal surface may be greater than the height of the protrusions and / or the depth of the depressions on the first sub-pyramidal surface. In this way, by making the shape of the pyramidal surfaces of the approximately pyramidal structure more irregular, the textured structure has a larger specific surface area, lower reflectivity, better light trapping effect, and allows for an increase in short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell, and also giving the solar cell a uniform black appearance and a more attractive appearance.

[0032] Referring to FIG. 3 , the passivation anti-reflection layer 2 includes a first portion on a first sub-conical surface and a second portion on a second sub-conical surface. In the passivation anti-reflection layer 2, the thickness of the first portion is greater than the thickness of the second portion along the same direction approaching the vertex 11. That is, when comparing the thicknesses of the first portion and the second portion, the first portion and the second portion are limited to being along the same direction approaching the vertex 11. In this specification, the first portion and the second portion along the same direction approaching the vertex 11 can be understood as the first portion and the second portion aligned in order in a direction from the bottom or bottom contour of the approximately pyramidal structure toward the vertex 11. Here, the thickness direction is perpendicular to the tangent at the corresponding position on the outer surface of the passivation anti-reflection layer 2. Specifically, in the silicon substrate 1, the situation adjacent to the approximately pyramidal structure is complex and often contains many voids. The situation adjacent to adjacent approximately pyramidal structures is also complex and often contains many voids. Therefore, a thick passivation anti-reflection layer is required at these locations to achieve a good passivation effect. Therefore, a thick passivation anti-reflection layer is also required on the first sub-conical surface adjacent to these locations to achieve a good passivation effect. On the other hand, since there are often few voids at the apex, a good passivation effect can be achieved even with a thin passivation anti-reflection layer. Therefore, a good passivation effect can be achieved even with a relatively thin passivation anti-reflection layer on the second sub-conical surface adjacent to the apex. Therefore, in the present application, the thickness of the first portion is greater than the thickness of the second portion along the same direction approaching the apex, ensuring a good passivation effect at all locations. In the present application, the thickness of the passivation anti-reflection layer is set according to passivation needs, thereby reducing waste.Furthermore, in the present application, after light enters the passivation anti-reflection layer of different thicknesses, the optical path changes more times, allowing the optical path length to be longer, which in combination with the texture structure of the present application can further improve light absorption, resulting in a better light trapping effect, allowing for a further increase in short-circuit current, further improving the photoelectric conversion efficiency of the solar cell, and giving the solar cell a uniform black appearance that is more aesthetically pleasing. As a result, the present application not only ensures excellent passivation effect at every position on the solar cell, but also significantly improves the anti-reflection effect and reduces waste.

[0033] As shown in FIG. 3 , in the case of the leftmost approximately pyramidal structure, the portion of the passivation antireflection layer 2 other than the vertex 11 between dashed lines L1 and L2 is the second portion, and the portion to the left of L1 and the portion to the right of L2 is the first portion. In the first and second portions along the same direction L7 approaching the vertex 11, the thickness of the first portion is greater than the thickness of the second portion. In the first and second portions along the same direction L8 approaching the vertex 11, the thickness of the first portion is greater than the thickness of the second portion. In the case of the intermediate approximately pyramidal structure, the portion of the passivation antireflection layer 2 other than the vertex 11 between dashed lines L3 and L4 is the second portion, and the portion to the left of L3 and the portion to the right of L4 is the first portion. In the first and second portions along the same direction L9 approaching the vertex, the thickness of the first portion is greater than the thickness of the second portion. In the first and second portions along the same direction L10 approaching the apex, the thickness of the first portion is greater than the thickness of the second portion. In the case of the rightmost approximately pyramidal structure, in the passivation antireflection layer 2, the portion other than the apex between dashed lines L5 and L6 is the second portion, and the portion to the left of L5 and the portion to the right of L6 are the first portion. In the first and second portions along the same direction L11 approaching the apex, the thickness of the first portion is greater than the thickness of the second portion. In the first and second portions along the same direction L12 approaching the apex, the thickness of the first portion is greater than the thickness of the second portion.

[0034] It should be noted that the thickness of a portion of the passivation anti-reflection layer 2 can be measured using an instrument such as a transmission electron microscope. The thickness of a portion may be the thickness of the portion measured directly, or may be the average of thicknesses measured at multiple points selected in the portion. The measurement method is selected according to the measurability of the actual measurement target, and is not specifically limited.

[0035] Optionally, referring to Figures 1 to 3 and 5, in the pyramidal surface of the approximately pyramidal structure, the waviness of the first sub-pyramidal surface is smaller than the waviness of the second sub-pyramidal surface, or the roughness of the first sub-pyramidal surface is smaller than the roughness of the second sub-pyramidal surface. Here, the definitions of both waviness and roughness can refer to the corresponding descriptions above. By making the shape of the pyramidal surface of the approximately pyramidal structure more irregular, the textured structure has a larger specific surface area, lower reflectivity, better light trapping effect, and allows for an increase in short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. In addition, the solar cell has a uniform black appearance, making it more aesthetically pleasing. As shown in Figure 3, in the case of the leftmost approximately pyramidal structure, the waviness of the first sub-pyramid surface to the left of the dashed line L1 and the first sub-pyramid surface to the right of the dashed line L2 on the pyramidal surface is smaller than the waviness of the second sub-pyramid surface between the right side of the dashed line L1 and the left side of the apex of the leftmost approximately pyramidal structure and the second sub-pyramid surface between the left side of the dashed line L2 and the right side of the apex of the leftmost approximately pyramidal structure; alternatively, the roughness of the first sub-pyramid surface to the left of the dashed line L1 and the first sub-pyramid surface to the right of the dashed line L2 is smaller than the roughness of the second sub-pyramid surface between the right side of the dashed line L1 and the left side of the apex of the leftmost approximately pyramidal structure and the second sub-pyramid surface between the left side of the dashed line L2 and the right side of the apex of the leftmost approximately pyramidal structure. In the case of an intermediate approximately pyramidal structure, the waviness of the first sub-pyramid surface on the left side of dashed line L3 and the first sub-pyramid surface on the right side of dashed line L4 on the pyramidal surface is smaller than the waviness of the second sub-pyramid surface between the right side of dashed line L3 and the left side of the apex of this intermediate approximately pyramidal structure and the second sub-pyramid surface between the left side of dashed line L4 and the right side of the apex of this intermediate approximately pyramidal structure, or the roughness of the first sub-pyramid surface on the left side of dashed line L3 and the first sub-pyramid surface on the right side of dashed line L4 is smaller than the roughness of the second sub-pyramid surface between the right side of dashed line L3 and the left side of the apex of this intermediate approximately pyramidal structure and the second sub-pyramid surface between the left side of dashed line L4 and the right side of the apex of this intermediate approximately pyramidal structure.In the case of the rightmost approximately pyramidal structure, the waviness of the first sub-pyramidal surface to the left of dashed line L5 and the first sub-pyramidal surface to the right of dashed line L6 on the pyramidal surface is smaller than the waviness of the second sub-pyramidal surface between the right side of dashed line L5 and the left side of the apex of the rightmost approximately pyramidal structure and the second sub-pyramidal surface between the left side of dashed line L6 and the right side of the apex of the rightmost approximately pyramidal structure, or the roughness of the first sub-pyramidal surface to the left of dashed line L5 and the first sub-pyramidal surface to the right of dashed line L6 is smaller than the roughness of the second sub-pyramidal surface between the right side of dashed line L5 and the left side of the apex of the rightmost approximately pyramidal structure and the second sub-pyramidal surface between the left side of dashed line L6 and the right side of the apex of the rightmost approximately pyramidal structure.

[0036] Optionally, referring to FIG. 3 , the thickness of the first portion of the passivation anti-reflection layer 2 is greater than the thickness of the portion of the passivation anti-reflection layer 2 at the apex 11. Specifically, in the silicon substrate 1, the situation adjacent to the approximately pyramidal structure is complex and often contains many voids, and the situation adjacent to the adjacent approximately pyramidal structure is also complex and often contains many voids. Therefore, a thick passivation anti-reflection layer is required at these locations to achieve a good passivation effect. Therefore, a thick passivation anti-reflection layer is also required on the first sub-conical surface adjacent to these locations to achieve a good passivation effect. On the other hand, since there are often few voids at the apex, a good passivation effect can be achieved even with a thin passivation anti-reflection layer. Therefore, in the present application, the thickness of the first portion of the passivation antireflection layer 2 is made greater than the thickness of the portion of the passivation antireflection layer 2 at the apex 11, thereby ensuring excellent passivation effects at all positions, and the thickness of the passivation antireflection layer is set according to the passivation needs, thereby reducing waste. Furthermore, in the present application, after light enters the passivation antireflection layer with different thicknesses, the optical path changes more times, thereby increasing the optical path length. This, in cooperation with the texture structure of the present application, can further improve light absorption, improve the light trapping effect, further increase the short-circuit current, further improve the photoelectric conversion efficiency of the solar cell, and also give the solar cell a uniform black appearance, making it more attractive.

[0037] 3 , in the case of the leftmost approximately pyramidal structure, the thicknesses of the first portion of the passivation antireflection layer 2 on the left side of the dashed line L1 and the first portion of the passivation antireflection layer 2 on the right side of the dashed line L2 are greater than the thickness of the portion of the passivation antireflection layer 2 at the apex 11 of the leftmost approximately pyramidal structure. In the case of the intermediate approximately pyramidal structure, the thicknesses of the first portion of the passivation antireflection layer 2 on the left side of the dashed line L3 and the first portion of the passivation antireflection layer 2 on the right side of the dashed line L4 are greater than the thickness of the portion of the passivation antireflection layer 2 at the apex 11 of the intermediate approximately pyramidal structure. In the case of the rightmost approximately pyramidal structure, the thicknesses of the first portion of the passivation antireflection layer 2 on the left side of the dashed line L5 and the first portion of the passivation antireflection layer 2 on the right side of the dashed line L6 are greater than the thickness of the portion of the passivation antireflection layer 2 at the apex 11 of the rightmost approximately pyramidal structure.

[0038] Referring to FIG. 3 , the area between dashed lines L2 and L3 is the adjacent portion between the leftmost substantially pyramidal structure and the middle substantially pyramidal structure, and the area between dashed lines L4 and L5 is the adjacent portion between the rightmost substantially pyramidal structure and the middle substantially pyramidal structure. Alternatively, referring to FIG. 3 , the thickness of the portion of the passivation anti-reflection layer 2 located at the adjacent portion between adjacent substantially pyramidal structures is greater than the thickness of the portion of the passivation anti-reflection layer 2 located at the apex 11. Specifically, the situation at the adjacent portion between adjacent substantially pyramidal structures on the silicon substrate 1 is complex and often contains many voids, so a thick passivation anti-reflection layer is required at these locations to achieve a good passivation effect. On the other hand, at the apex, there are often few voids, so a good passivation effect can be achieved even with a thin passivation anti-reflection layer. Therefore, in the present application, the thickness of the portions of the passivation antireflection layer 2 located at adjacent points of adjacent pyramidal structures is made greater than the thickness of the portion of the passivation antireflection layer 2 located at the apex 11, thereby ensuring excellent passivation effects at all positions, while the thickness of the passivation antireflection layer is set according to the passivation needs, thereby reducing waste. Furthermore, in the present application, after light enters the passivation antireflection layer with different thicknesses, the optical path changes more times, thereby increasing the optical path length. This, in cooperation with the textured structure of the present application, can further improve light absorption, improve the light trapping effect, further increase the short-circuit current, further improve the photoelectric conversion efficiency of the solar cell, and give the solar cell a uniform black appearance, improving its appearance. As shown in Figure 3, the thickness of the portion of the passivation antireflection layer 2 between dashed lines L2 and L3 is greater than the thickness of the portion of the passivation antireflection layer 2 at the apex 11 of the leftmost approximately pyramidal structure, and is also greater than the thickness of the portion of the passivation antireflection layer 2 at the apex 11 of the middle approximately pyramidal structure.In Figure 3, the thickness of the portion of the passivation antireflection layer 2 between dashed lines L4 and L5 is greater than the thickness of the portion at the apex of the rightmost approximately pyramidal structure in the passivation antireflection layer 2, and is also greater than the thickness of the portion at the apex of the middle approximately pyramidal structure in the passivation antireflection layer 2.

[0039] Optionally, referring to FIG. 3 , the thickness of the portion of the passivation anti-reflection layer 2 located on the adjacent portion of the adjacent pyramidal structures is greater than the thickness of the second portion of the passivation anti-reflection layer 2. Specifically, the adjacent portions of the adjacent pyramidal structures on the silicon substrate 1 are complex and often contain many voids, so a thick passivation anti-reflection layer is required at these locations to achieve a good passivation effect. On the other hand, at the apex, there are often few voids, so a good passivation effect can be achieved even with a thin passivation anti-reflection layer. As a result, a good passivation effect can also be achieved at the second sub-conical surface adjacent to the apex, even with a relatively thin passivation anti-reflection layer. Therefore, in the present application, the thickness of the portion of the passivation antireflection layer 2 located adjacent to adjacent approximately pyramidal structures is made greater than the thickness of the second portion of the passivation antireflection layer 2, thereby ensuring excellent passivation effects at all positions, and the thickness of the passivation antireflection layer is set according to the passivation needs, thereby reducing waste. Furthermore, in the present application, after light enters the passivation antireflection layer with different thicknesses, the optical path changes more times, thereby increasing the optical path length. This, in cooperation with the textured structure of the present application, can further improve light absorption, improve the light trapping effect, further increase the short-circuit current, further improve the photoelectric conversion efficiency of the solar cell, and give the solar cell a uniform black appearance, improving its appearance.

[0040] 3, the thickness of the portion of the passivation antireflection layer 2 between the dashed lines L2 and L3 is greater than the thickness of the second portion of the passivation antireflection layer 2 other than the vertex between the dashed lines L1 and L2, and is also greater than the thickness of the second portion of the passivation antireflection layer 2 other than the vertex between the dashed lines L3 and L4. In FIG. 3, the thickness of the portion of the passivation antireflection layer 2 between the dashed lines L4 and L5 is greater than the thickness of the second portion of the passivation antireflection layer 2 other than the vertex between the dashed lines L5 and L6, and is also greater than the thickness of the second portion of the passivation antireflection layer 2 other than the vertex between the dashed lines L3 and L4.

[0041] Optionally, in the passivation anti-reflection layer 2, the thickness variation between the first portion and the second portion is greater than 4%. This thickness variation is calculated by dividing the absolute value of the difference between the first thickness at a first position in the first portion and the second thickness at a second position in the second portion along the same direction toward the apex by the sum of the first thickness and the second thickness. Here, the first position in the first portion is an arbitrary position in the first portion, and the second position in the second portion is an arbitrary position in the second portion. That is, here, the first portion and the second portion are limited to being along the same direction toward the apex 11, and in the passivation anti-reflection layer 2, the thickness variation between the first portion and the second portion is greater than 4%. Specifically, in the silicon substrate 1, the situation at the adjacent locations of adjacent approximately pyramidal structures is complex and often has many voids. Therefore, a thick passivation anti-reflection layer is required at these locations to achieve a good passivation effect. On the other hand, because there are often fewer voids at the vertex, a good passivation effect can be achieved even with a thin passivation anti-reflection layer. Therefore, a good passivation effect can also be achieved at the second sub-conical surface adjacent to the vertex, even with a relatively thin passivation anti-reflection layer. Therefore, in the present application, the thickness variation between the first and second portions of the passivation anti-reflection layer 2 is set to be greater than 4%, ensuring excellent passivation at all positions. Furthermore, in the present application, the thickness of the passivation anti-reflection layer is set according to passivation needs, thereby reducing waste. Furthermore, in the present application, after light enters the passivation anti-reflection layer with different thicknesses, the optical path changes more times, thereby lengthening the optical path length. This, in cooperation with the textured structure of the present application, further improves light absorption, improves the light trapping effect, further increases the short-circuit current, and further enhances the photoelectric conversion efficiency of the solar cell. Furthermore, the solar cell has a uniform black appearance, making it more attractive.

[0042] For example, in the passivation anti-reflection layer 2, the thickness variation between the first portion and the second portion along the same direction approaching the apex may 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%.

[0043] Optionally, the solar cell may further include an aluminum oxide layer (not shown) between the silicon substrate 1 and the passivation anti-reflection layer 2. The thickness variation of the aluminum oxide layer is smaller than the thickness variation of the passivation anti-reflection layer 2. Here, the thickness variation refers to the range of thickness fluctuation. The thickness variation of the aluminum oxide layer may 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 variation of the passivation anti-reflection layer 2 may 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. Here, in the thickness direction of the silicon substrate, the projections of the fifth position and the seventh position overlap, and the projections of the sixth position and the eighth position overlap. The fifth position and the sixth position are two different arbitrary positions in the aluminum oxide layer. Specifically, the aluminum oxide layer is usually obtained by atomic layer deposition, and the surface morphology has little effect on the atomic layer deposition, so the thickness of the aluminum oxide layer is relatively uniform and the passivation performance of the aluminum oxide layer is excellent.

[0044] 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 can be measured using a transmission electron microscope or the like, but is not specifically limited. For example, the thickness variation of the aluminum oxide layer may be 0.0001 nm to 3 nm, such as 0.001 nm, 0.005 nm, 0.008 nm, 0.01 nm, 0.02 nm, 0.03 nm, 0.04 nm, 0.05 nm, 0.06 nm, 0.07 nm, 0.08 nm, 0.1 nm, 0.2 nm, 0.3 nm, 0.4 nm, 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 1 nm, 2 nm, 2.3 nm, or 3 nm. The thickness variation of the passivation antireflection layer 2 may be 3.5 nm to 50 nm, for example, 3.5 nm, 4 nm, 4.8 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 12 nm, 12.5 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 20 nm, 25 nm, 30 nm, 36 nm, 40 nm, 45 nm, or 50 nm.

[0045] Optionally, the aluminum oxide layer includes a third portion located on the first sub-conical surface and a fourth portion located on the second sub-conical surface. The thickness variation of the first and second portions of the passivation anti-reflection layer 2 is greater than the thickness variation of the third and fourth portions of the aluminum oxide layer. The thickness variation of the first and second portions of the passivation anti-reflection layer 2 is described above, and will not be described here. The thickness variation of the third and fourth portions of the aluminum oxide layer is calculated by dividing the absolute value of the difference between the third thickness at a third position in the third portion and the fourth thickness at a fourth position in the fourth portion along the same direction toward the apex by the sum of the third and fourth thicknesses. Here, the third and fourth portions are both limited to the same direction toward the apex. Here, the third position in the third portion is an arbitrary position in the third portion, and the fourth position in the fourth portion is an arbitrary position in the fourth portion. The thickness variation of the first and second portions of the passivation anti-reflection layer 2 is greater than the thickness variation of the third and fourth portions of the aluminum oxide layer. Therefore, the thickness of the passivation anti-reflection layer 2 is tailored to the passivation needs, ensuring excellent passivation performance at all positions. Furthermore, the present application sets the thickness of the passivation anti-reflection layer according to the passivation needs, thereby reducing waste. Furthermore, in the present application, after light enters the passivation anti-reflection layer with different thicknesses, the optical path changes more times, increasing the optical path length. This, combined with the textured structure of the present application, further improves light absorption, resulting in a better light trapping effect, a further increase in short-circuit current, and a further increase in the photoelectric conversion efficiency of the solar cell. Furthermore, the solar cell has a uniform black appearance, making it more attractive. It should be noted that the specific difference between the two thickness variations is not limited.

[0046] Optionally, the passivation anti-reflection layer 2 includes a front passivation anti-reflection layer on the light-receiving side of the silicon substrate 1 and a back passivation anti-reflection layer on the non-light-receiving side of the silicon substrate 1. At two opposing positions in the thickness direction of the silicon substrate 1, the thickness of the back passivation anti-reflection layer is greater than the thickness of the front passivation anti-reflection layer. Specifically, as the thickness of the passivation anti-reflection layer increases, its passivation effect improves, but its anti-reflection effect decreases accordingly. Because the anti-reflection requirements for the non-light-receiving side are lower than those for the light-receiving side, the thickness of the back passivation anti-reflection layer can be appropriately increased to ensure excellent passivation performance on the non-light-receiving side, and the thickness of the front passivation anti-reflection layer can be appropriately decreased to achieve both passivation performance and anti-reflection effect.

[0047] Optionally, the difference in thickness between the back passivation anti-reflection layer and the front passivation anti-reflection layer at two opposing positions in the thickness direction of the silicon substrate 1 is 15 nm or more and 40 nm or less. By appropriately setting the difference between the two, excellent passivation performance on the non-light-receiving side can be sufficiently ensured, while good passivation performance and anti-reflection effect can be obtained on the light-receiving side, and waste can be avoided. For example, the thickness of the back passivation anti-reflection layer can be 85 nm to 100 nm, or approximately 95 nm. The thickness of the front passivation anti-reflection layer can be 60 nm to 70 nm, or approximately 65 nm. Here, the difference in thickness between the back passivation anti-reflection layer and the front passivation anti-reflection layer at two opposing positions in the thickness direction of the silicon substrate 1 may be 15 nm, or 16.3 nm, or 17.9 nm, or 19.4 nm, or 20.94 nm, or 22.6 nm, or 24.92 nm, or 27.5 nm, or 30.3 nm, or 32.6 nm, or 33.9 nm, or 35.7 nm, or 36.9 nm, or 18.34 nm, or 40 nm.

[0048] Optionally, referring to FIG. 2 , the conical surface of the approximately pyramidal structure has a branching texture 12. The shape of the branching texture 12 resembles the shape of tree branches, and the branching texture 12 has a pattern that looks like branches branching out from the main trunk. The number of branching textures 12 on the second sub-conical surface of the conical surface of the approximately pyramidal structure is greater than the number of branching textures 12 on the first sub-conical surface of the conical surface of the approximately pyramidal structure that is farther from the apex of the conical surface of the approximately pyramidal structure. There is a correspondence between the branching texture 12 and the protrusions or depressions on the conical surface of the approximately pyramidal structure, and the branching texture 12 is usually located at the boundary between the protrusions and depressions on the conical surface of the approximately pyramidal structure. That is, the greater the number of branching textures 12, the greater the number of protrusions and depressions on the conical surface of the approximately pyramidal structure. Therefore, the more textures there are, the larger the specific surface area of ​​the textured structure, and the more irregular the distribution of the branched textures, the larger the specific surface area the textured structure can have, resulting in lower reflectivity, better light trapping effect, and increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell and giving the solar cell a uniform black appearance and a more attractive appearance.For example, in Figure 2, in the conical surface of the approximately pyramidal structure on the farthest right, the first sub-conical surface far from the apex has almost no branched textures, but the second sub-conical surface has a large number of branched textures 12.

[0049] Optionally, referring to FIG. 4, the vertex 11 of the substantially pyramidal structure and the second sub-pyramidal surface of the substantially pyramidal structure have a set of nested substantially annular textures 13. Here, the substantially annular textures 13 may be open-shaped and substantially annular patterns, and / or the substantially annular textures 13 may be closed-shaped and substantially annular patterns. For example, in FIG. 4, the set of nested substantially annular textures 13 located in the center and labeled 13 has both open-shaped and closed-shaped patterns. In the set of nested substantially annular textures 13, the number of substantially annular textures 13 is not specifically limited, and each of the substantially annular textures 13 is nested with each other. The first sub-pyramidal surface of the substantially pyramidal structure has almost no substantially annular texture. There is a correspondence between the substantially annular texture 13 and the protrusions or depressions on the pyramidal surface of the substantially pyramidal structure, and the substantially annular texture 13 is usually located at the boundary between the protrusions and depressions on the pyramidal surface of the substantially pyramidal structure, i.e., the more substantially annular textures 13 there are, the more protrusions and depressions there are on the pyramidal surface of the substantially pyramidal structure. Therefore, the more textures there are, the larger the specific surface area of ​​the texture structure can be. The more irregular the distribution position of the substantially annular textures, the larger the specific surface area of ​​the texture structure can be, which reduces the reflectivity, improves the light trapping effect, and enables an increase in short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. In addition, the solar cell's appearance becomes uniformly black and more attractive.

[0050] 4, the substantially annular texture 13 here may be a wavy texture, i.e., a texture that appears to be irregularly stacked like waves under electron microscope observation, and / or the substantially annular texture 13 may be a rose-like texture, i.e., a texture that appears to be irregularly stacked like the stacked multiple petals of a rose under electron microscope observation. In this way, the substantially annular texture 13 has a beautiful shape, low reflectivity, and a good light trapping effect. The substantially annular texture 13 is on the conical surface and vertex, or further, the substantially annular texture 13 is on the second sub-conical surface of the conical surface and vertex.

[0051] 4, in a set of approximately annular textures 13, along the height direction of the approximately pyramidal structure, the contours of the approximately annular textures 13 become smaller as one approaches the apex 11, and become larger as one moves away from the apex 11. The distribution positions of the approximately annular textures 13 are irregular, and the approximately annular textures 13 can increase the specific surface area. This allows the texture structure to have a larger specific surface area, lower reflectivity, better light trapping effect, and increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. In addition, the solar cell has a uniform black appearance, making it more aesthetically pleasing.

[0052] Optionally, referring to FIGS. 1 to 5 , the portion of the approximately pyramidal structure away from the apex 11 is the lower portion of the approximately pyramidal structure, and the height of the lower portion accounts for at least 1 / 10 of the height of the approximately pyramidal structure. In the pyramidal surface of the approximately pyramidal structure, the first sub-pyramid surface away from the apex 11 corresponds to the lower portion of the pyramidal surface of the approximately pyramidal structure, and the second sub-pyramid surface corresponds to the lower portion of the pyramidal surface of the approximately pyramidal structure closer to the apex 11 than the first sub-pyramid surface. Specifically, accurately separating the second sub-pyramid surface from the first sub-pyramid surface not only benefits the fabrication of a textured structure, but also reduces reflectivity, improves light trapping, and allows for an increase in short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. Furthermore, the solar cell has a uniform black appearance, improving its appearance. In this specification, with regard to the ratio of the height of the lower portion of the approximately pyramidal structure, it should be understood that the above-mentioned effect can be achieved as long as the majority of the approximately pyramidal structures in the textured structure have a lower height that satisfies this ratio.

[0053] For example, the portion of the approximately pyramidal structure away from the apex 11 is the lower part of the approximately pyramidal structure, and the height of the lower part is 1 / 10, 2 / 15, 3 / 20, 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, or 1 / 4 of the height of the approximately pyramidal structure. In the pyramidal surface of the approximately pyramidal structure, the first sub-pyramidal surface away from the apex 11 is a region corresponding to the lower part of the pyramidal surface of the approximately pyramidal structure, and the second sub-pyramidal surface is a region of the pyramidal surface of the approximately pyramidal structure closer to the apex 11 than the first sub-pyramidal surface.

[0054] Optionally, the portion of the approximately pyramidal structure away from the apex 11 is the lower portion of the approximately pyramidal structure, the height of this lower portion accounting for at least 1 / 5 of the height of the approximately pyramidal structure; the portion of the approximately pyramidal structure close to the apex 11 is the upper portion of the approximately pyramidal structure, the height of this upper portion accounting for at most 1 / 5 of the height of the approximately pyramidal structure; and the portion of the approximately pyramidal structure between the lower and upper portions is the middle portion, the height of this middle portion accounting for at least 2 / 5 of the height of the approximately pyramidal structure. In the pyramidal surface of the approximately pyramidal structure, the first sub-pyramidal surface away from the apex 11 is a region corresponding to the lower portion of the pyramidal surface of the approximately pyramidal structure. The second sub-pyramidal surface is also divided into an upper sub-pyramidal surface and a middle sub-pyramidal surface. In the pyramidal surface of the approximately pyramidal structure, the upper sub-pyramidal surface is a region corresponding to the upper portion of the pyramidal surface of the approximately pyramidal structure. In the pyramidal surface of the approximately pyramidal structure, the middle sub-pyramidal surface is a region corresponding to the middle portion of the pyramidal surface of the approximately pyramidal structure. Accurately dividing the three sub-pyramidal surfaces is not only advantageous for fabricating a textured structure, but also leads to lower reflectivity, better light trapping, and increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. The solar cell also has a uniformly black exterior, improving its appearance. In this specification, it should be understood that the above-described effect can be achieved when the majority of the approximately pyramidal structures in the textured structure have an upper height that satisfies the above-described ratio. Similarly, in this specification, it should be understood that the above-described effect can be achieved when the majority of the approximately pyramidal structures in the textured structure have an upper height that satisfies the above-described ratio.

[0055] For example, the portion of the approximately pyramidal structure close to the apex 11 is the upper portion of the approximately pyramidal structure, and the height of the upper portion is 1 / 10, 2 / 15, 3 / 20, 1 / 9, 1 / 8, 1 / 7, 1 / 6, or 1 / 5 of the height of the approximately pyramidal structure. Also, for example, the portion between the upper and lower portions of the approximately pyramidal structure is the middle portion, and the height of the middle portion is 2 / 5, 13 / 30, 7 / 15, 1 / 2, 8 / 15, 17 / 30, or 3 / 5 of the height of the approximately pyramidal structure.

[0056] Optionally, referring to Figures 3 and 4, the approximately pyramidal structure further includes a bottom contour 14 spaced apart from the apex 11, with at least two points on the same bottom contour 14 having different heights. As shown in Figure 3, the leftmost, middle, and rightmost approximately pyramidal structures have height differences between the left and right endpoints of their respective bottom contours, making the shapes of the approximately pyramidal structures more irregular. This allows the textured structure to have a larger specific surface area, lower reflectivity, better light trapping effect, and increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. Furthermore, the solar cell has a uniform black appearance, making it more aesthetically pleasing.

[0057] Optionally, referring to Figure 1, the apex angle a of the textured structure is 55° to 90°, and the apex angle of the textured structure is the angle between two opposing side edges passing through the apex of the approximately pyramidal structure. Because the apex angle a of the textured structure is 55° to 90°, the textured structure has a larger specific surface area, a lower reflectance, a better light trapping effect, and an increased short-circuit current, which ultimately improves the photoelectric conversion efficiency of the solar cell. In addition, the solar cell has a uniform black appearance and a more attractive appearance.

[0058] For example, the apex angle a of the texture 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°.

[0059] Optionally, the height of the approximately pyramidal structure is 0.2 μm (microns) to 3 μm. When the approximately pyramidal structure has an appropriate height, the textured structure has a larger specific surface area, a lower reflectance, a better light trapping effect, and an increased short-circuit current, which ultimately improves the photoelectric conversion efficiency of the solar cell. In addition, the solar cell has a uniform black appearance, which improves its appearance.

[0060] For example, the height of the generally pyramidal structures may be 0.5 μm to 3 μm, or the height of the generally pyramidal structures may be 0.2 μm, or 0.31 μm, or 0.37 μm, or 0.42 μm, or 0.6 μm, or 0.73 μm, or 0.88 μm, or 0.95 μm, or 1.2 μm, or 1.24 μm, or 1.7 μm, or 1.99 μm, or 2.21 μm, or 2.7 μm, or 2.79 μm, or 3 μm.

[0061] Optionally, the approximately pyramidal structure includes an apex 11, a pyramidal surface, and at least two side edges. The side edges of the approximately pyramidal structure are the common edges of adjacent side surfaces of the approximately pyramidal structure. The side edges include a lower segment away from the apex 11 and a first segment, where the bending degree of the lower segment is smaller than that of the first segment. The bending degree of a subsegment of the side edge refers to the degree to which the subsegment is bent. The irregular shape of each side edge allows the textured structure to have a larger specific surface area, lower reflectivity, better light trapping effect, and increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. The solar cell also has a uniform black appearance, improving its appearance. For example, in FIG. 3, in the leftmost side edge of the approximately pyramidal structure on the left, the bending degree of the lower segment to the left of L1 is smaller than that of the first segment to the right of L1. At the rightmost lateral edge of the leftmost approximately pyramidal structure, the degree of bending of the lower segment on the right side of L2 is less than that of the first segment on the left side of L2.

[0062] Optionally, referring to FIG. 4 , in the textured structure, at least the lower portions of at least two approximately pyramidal structures 15 away from the apex 11 are integrated, and the apexes of each integrated approximately pyramidal structure 15 are separated, which allows the textured structure to have flexible and diverse shapes and is easy to fabricate. Because the apexes of each integrated approximately pyramidal structure 15 are separated, the textured structure has a larger specific surface area, lower reflectivity, a better light trapping effect, and an increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. The solar cell also has a uniform black appearance, improving its appearance. For example, in FIG. 4 , at least the lower portions of the two approximately pyramidal structures enclosed in curly brackets on the left side of the textured structure away from the apex 11 are integrated, and the apexes of each integrated approximately pyramidal structure 15 are separated.

[0063] Optionally, in a direction perpendicular to the height of the approximately pyramidal structures, the distance between the vertices of adjacent integral approximately pyramidal structures 15 may be greater than 0.2 μm or greater than 0.5 μm, for example, 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.

[0064] Optionally, referring to FIG. 4 , in the textured structure, at least the lower portions of at least two approximately pyramidal structures 15 away from the apex 11 are integrated, and the apexes of each integrated approximately pyramidal structure 15 have different heights or are uniformly distributed. This allows the textured structure to have flexible and diverse shapes, making it easier to fabricate, and the textured structure has a larger specific surface area, lower reflectivity, better light trapping effect, and increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. The solar cell also has a uniform black appearance and a more attractive appearance. For example, in FIG. 4 , at least the lower portions of the two approximately pyramidal structures enclosed by curly brackets on the left side of the textured structure away from the apex 11 are integrated, and the apexes of each integrated approximately pyramidal structure 15 have different heights. Also, for example, in FIG. 4 , at least the lower portions of the two approximately pyramidal structures enclosed by curly brackets on the right side of the textured structure away from the apex 11 are integrated, and the apexes of each integrated approximately pyramidal structure 15 are approximately uniform.

[0065] 4, in the textured structure, at least the lower portions of at least two approximately pyramidal structures away from the apexes 11 are integrated, and the apexes of each integrated approximately pyramidal structure 15 have a height difference that is greater than 0 and not greater than 1.6 microns. By rationally setting the height difference, the textured structure has a more reasonable specific surface area, lower reflectivity, and better light trapping effect, while the passivation anti-reflection layers formed in different parts have different thicknesses, which lengthens the optical path length of incident light and improves light absorption.

[0066] For example, in the texture structure, at least the lower portions of at least two approximately pyramidal structures 15 away from the apexes 11 are joined together, and the apexes of each joined approximately pyramidal structure 15 have a height difference, which may be 0.1 μm, or 0.17 μm, or 0.2 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 1.21 μm, or 1.34 μm, or 1.5 μm, or 1.6 μm.

[0067] 4, in the textured structure, at least the lower portions of at least two approximately pyramidal structures away from the apexes 11 are integrated, and the apexes of each integrated approximately pyramidal structure 15 have a height difference that is greater than 0 and not greater than 0.8 microns. By reducing the height difference, the textured structure has a more reasonable specific surface area, lower reflectivity, and better light trapping effect, while the passivation anti-reflection layers formed in different parts have different thicknesses, which increases the optical path length of incident light and improves light absorption.

[0068] For example, in the texture structure, at least the lower portions of at least two approximately pyramidal structures 15 away from the apex 11 are joined together, and the apexes of each joined approximately pyramidal structure 15 have a height difference, which may be 0.1 μm, or 0.13 μm, or 0.2 μm, or 0.33 μm, or 0.4 μm, or 0.47 μm, or 0.5 μm, or 0.61 μm, or 0.77 μm, or 0.8 μm.

[0069] Optionally, in the textured structure, at least the first sub-pyramidal surfaces of at least two approximately pyramidal structures are united, and the vertices of each united approximately pyramidal structure are separated. This allows the textured structure to have a larger specific surface area, lower reflectivity, better light trapping effect, and increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. The solar cell also has a uniform black appearance, improving its appearance. For example, in FIG. 4, at least the first sub-pyramidal surfaces of the two approximately pyramidal structures enclosed by curly brackets in the textured structure, which are distant from the vertices 11, are united, and the vertices of each united approximately pyramidal structure 15 are separated.

[0070] Alternatively, in each of the integrated substantially pyramidal structures, the substantially annular textures on the pyramidal surfaces of different substantially pyramidal structures are distributed separately. This allows the textured structure to have a larger specific surface area, lower reflectivity, better light trapping effect, and increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. The solar cell also has a uniform black appearance and a more attractive appearance. For example, in FIG. 4, at least the lower portions of the two substantially pyramidal structures enclosed by curly brackets on the left side of the textured structure, away from the apex 11, are integrated, and the apexes of each integrated substantially pyramidal structure 15 are separated. Alternatively, in each of the integrated substantially pyramidal structures, the substantially annular textures on the pyramidal surfaces of different substantially pyramidal structures are partially overlapped. This allows the textured structure to be flexible and diverse, allowing the textured structure to have a larger specific surface area, lower reflectivity, better light trapping effect, and increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. The solar cell also has a uniform black appearance and a more attractive appearance. For example, in Figure 4, at least the lower parts of the two approximately pyramidal structures enclosed in curly brackets on the right side of the texture structure, away from the vertex 11, are united, and the approximately annular textures on the pyramidal surfaces of the different approximately pyramidal structures of each united approximately pyramidal structure 15 partially overlap, and here the outermost approximately annular textures on the pyramidal surfaces of the different approximately pyramidal structures of each united approximately pyramidal structure 15 may also partially overlap.

[0071] Optionally, in a set of substantially annular textures, the substantially annular textures are distributed in a way that overlaps with each other at different positions along the height direction of the substantially pyramidal structure. This makes the texture structure flexible and diverse, and the texture structure has a larger specific surface area, lower reflectivity, a better light trapping effect, and an increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. The solar cell also has a uniform black appearance, making it more attractive. For example, in FIG. 4, in the set of substantially annular textures labeled 13 at the bottom, the substantially annular textures 13 are distributed in a way that overlaps with each other at different positions along the height direction of the substantially pyramidal structure.

[0072] Alternatively, on the pyramidal surface of the substantially pyramidal structure, the substantially annular texture 13 may extend from a position close to the apex 11 to a position on the pyramidal surface corresponding to a portion of the substantially pyramidal structure where the difference in height between the apex 11 and the substantially pyramidal structure is at most two-thirds of the height of the substantially pyramidal structure, or the substantially annular texture 13 may extend from a position close to the apex 11 to a side position (i.e., the pyramidal surface position) corresponding to a portion of the substantially pyramidal structure where the difference in height between the apex 11 and the substantially pyramidal structure is at most one-half of the height of the substantially pyramidal structure. By adjusting the position of the substantially annular texture 13, the positions where the protrusions and depressions on the side are densely distributed can be adjusted, and the texture structure, especially the upper half of the texture structure, has a larger specific surface area, lower reflectivity, better light trapping effect, and allows for an increase in short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell and providing a uniform black appearance and a more attractive solar cell.

[0073] Optionally, the maximum inner diameter d1 of the substantially annular texture 13 is 0.5 μm to 2 μm. By rationally setting the maximum inner diameter d1 of the substantially annular texture 13, not only is fabrication easier, but the texture structure also has a larger specific surface area, lower reflectivity, better light trapping effect, and increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. In addition, the solar cell has a uniform black exterior, making it more aesthetically pleasing.

[0074] For example, the maximum inner diameter d1 of the generally annular texture 13 may be 0.5 μm, or 0.56 μm, or 0.61 μm, or 0.72 μm, or 0.93 μm, or 1 μm, or 1.12 μm, or 1.25 μm, or 1.31 μm, or 1.42 μm, or 1.53 μm, or 1.61 μm, or 1.77 μm, or 1.83 μm, or 1.92 μm, or 2 μm. Also, for example, the maximum inner diameter d1 of the generally annular texture 13 may be 0.55 μm to 1.8 μm, or the maximum inner diameter d1 of the generally annular texture 13 may be 0.6 μm to 1.6 μm.

[0075] 4, for the same substantially annular texture, the maximum inner diameters of the substantially annular texture in at least two mutually perpendicular directions are unequal, i.e., for the same substantially annular texture, the maximum inner diameter of the substantially annular texture in a first direction is unequal to the maximum inner diameter of the substantially annular texture in a second direction perpendicular to the first direction, which makes the texture structure more irregular in shape, lowers the reflectivity, improves the light trapping effect, and allows for an increase in short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell and providing the solar cell with a uniform black appearance that is more aesthetically pleasing.

[0076] Optionally, referring to Fig. 4, in the same set of approximately annular textures, at least one of the approximately annular textures 13 has a peak 131 facing outward from the approximately annular texture 13, and the peak 131 can increase the specific surface area, so that the texture structure has a larger specific surface area, lower reflectivity, better light trapping effect, and increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell, and also making the solar cell appear uniformly black and more attractive.

[0077] 1 to 5, in the same substantially pyramidal structure, one of the two side edges on either side of the apex 11 has a larger dimension in the thickness direction of the silicon substrate than the other, which makes the shape of the substantially pyramidal structure more irregular, resulting in a textured structure with a larger specific surface area, a lower reflectivity, a better light trapping effect, and an increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell, and also making the solar cell appear uniformly black and more attractive.

[0078] 1 to 4, two adjacent substantially pyramidal structures may have a smaller lateral edge in one of the two substantially pyramidal structures disposed adjacent to a smaller lateral edge in the other substantially pyramidal structure, resulting in a more irregular textured structure, a larger specific surface area, a lower reflectance, a better light trapping effect, and an increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell, and providing a uniformly black, attractive appearance to the solar cell.

[0079] Optionally, referring to FIGS. 1 to 4, the lower segment of one side edge away from vertex 11 may be a straight line segment or a line segment with up to two inflection points. Specifically, for example, this lower segment may be a straight line segment with only one slope, in which case this lower segment has no inflection points. Alternatively, this lower segment may be composed of two line segments, which may be one straight line segment and one curved line segment with an inflection point at their intersection, or two straight line segments with different slopes and an inflection point at their intersection. Alternatively, this lower segment may be composed of three line segments, which may be composed of one straight line segment, another straight line segment, and one curved line segment, where the two straight line segments have different slopes and where each of the three segments intersects. Alternatively, this lower segment may be composed of three straight line segments, which have different slopes and where two adjacent lines intersect. Here, the lower segment can be obtained by adopting conventional texturing methods and parameters, which improves process adaptability.

[0080] Optionally, referring to Figures 1 to 4, in one side edge, the first segment other than the lower segment may be a broken line segment and / or a curved line segment. The number of broken line segments and the number of curved line segments included in this first segment are not specifically limited. In this way, the shape of the textured structure becomes more irregular, the textured structure has a larger specific surface area, a lower reflectivity, a better light trapping effect, and an increased short-circuit current. Ultimately, the photoelectric conversion efficiency of the solar cell is improved, and the solar cell has a uniform black appearance, improving its appearance.

[0081] For example, in FIG. 3, in the leftmost approximately pyramidal structure, the lower segment to the left of L1 is composed of two straight line segments and one inflection point, while the first segment to the right of L1 is composed of multiple broken line segments and multiple curved segments. In the rightmost approximately pyramidal structure, the lower segment to the right of L2 is composed of one straight line segment and no inflection point, while the first segment to the left of L2 is composed of multiple broken line segments and multiple curved segments. In the leftmost approximately pyramidal structure, the lower segment to the left of L3 is composed of two straight line segments and one inflection point, while the first segment to the right of L3 is composed of multiple broken line segments and multiple curved segments. In the rightmost approximately pyramidal structure, the lower segment to the right of L4 is composed of three straight line segments and two inflection points, while the first segment to the left of L4 is composed of multiple broken line segments and multiple curved segments. In the left lateral ridge of the rightmost approximately pyramidal structure, the lower segment to the left of L5 is two straight line segments with one inflection point, while the first segment to the right of L5 is made up of multiple broken line segments and multiple curved segments. In the right lateral ridge of the rightmost approximately pyramidal structure, the lower segment to the right of L6 is made up of one straight line segment with no inflection point, while the first segment to the left of L6 is made up of multiple broken line segments and multiple curved segments.

[0082] Optionally, the length of the lower segment of one side edge is at least 1 / 10 of the length of this side edge. Here, accurate division of the lower segment and the first segment of one side edge is not only advantageous for fabricating a textured structure, but also leads to lower reflectivity, better light trapping effect, and increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell, and also leads to a uniform black appearance of the solar cell, which is more aesthetically pleasing.

[0083] For example, the length of the lower segment of one lateral ridge 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 this lateral ridge.

[0084] 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-receiving side or non-light-receiving side of the silicon substrate 1 facing away from the horizontal plane, the first plane is parallel to the horizontal plane. For example, in FIG. 3, the first plane is indicated by a horizontal dashed line extending left and right, and in FIG. 5, the first plane is indicated by a horizontal dashed line extending left and right. Optionally, the angle between a lower segment of one 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, the etching rate of the chemical solution for each crystal orientation of the silicon substrate is adjusted by the etching additive, and the side edges are etched irregularly, resulting in a more irregular textured structure, which has a larger specific surface area, lower reflectivity, a better light trapping effect, and an increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. In addition, the solar cell has a uniform black exterior, making it look more attractive.

[0085] Optionally, the first segment of one side edge comprises an upper segment and a middle segment, where the upper segment is close to the vertex 11 and the middle segment is located between the lower segment and the upper segment. The length of the upper segment is at least 1 / 10 of the length of the side edge, and the length of the middle segment is at least 2 / 5 of the length of the side edge. Specifically, the lower segment is the portion of the side edge farthest from the vertex 11. In other words, the lower segment is the lowest portion of the side edge. The upper segment is the portion of the side edge closest to the vertex 11. In other words, the upper segment is the uppermost portion of the side edge. The middle segment is the middle portion of the side edge. Accurately dividing the lower segment, upper segment, and middle segment as described above is not only advantageous for creating a textured structure, but also leads to lower reflectivity, better light trapping effect, and increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. Furthermore, the solar cell has a uniform black appearance, improving its appearance.

[0086] For example, the length of the upper segment of a lateral ridge may be 1 / 10, 2 / 15, 3 / 20, 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, or 1 / 4 of the length of the lateral ridge. The portion of a lateral ridge other than the lower and upper segments is the middle segment. For example, the length of the middle segment of a lateral ridge may be 2 / 5, 13 / 30, 7 / 15, 1 / 2, 8 / 15, 17 / 30, or 3 / 5 of the length of the lateral ridge.

[0087] Optionally, referring to FIG. 3, the angle b between the lower segment of one side edge and the first plane is 50° to 55°. Referring to FIG. 5, 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 FIG. 5, the white solid line is a reverse extension of the upper segment. By rationally setting the angles between the three subsegments and the first plane, fabrication becomes easier, the portion near the apex 11 of the approximately pyramidal structure becomes sharper, the reflectivity is lowered, the light trapping effect is improved, and the short-circuit current can be increased. Ultimately, the photoelectric conversion efficiency of the solar cell is improved, and the solar cell's appearance is uniformly black, resulting in a more attractive appearance. If the lower segment of one side edge is a single straight line segment, the angle b between the lower segment of this side edge and the first plane may be the angle between this straight line segment and the first plane. For example, in Figure 3, the lower segment to the right of L2 on the right side edge of the leftmost approximately pyramidal structure is a single straight line segment, so angle b between this lower segment of this right side edge and the first plane may be the angle between this straight line segment and the first plane. If the lower segment of a side edge is not a single straight line segment, angle b between this lower segment of this side edge and the first plane may be the angle between the straight line segment to which the lower endpoint of this lower segment belongs and the first plane. For example, in Figure 3, the lower segment to the left of L1 on the left side edge of the leftmost approximately pyramidal structure is composed of two straight line segments and has one inflection point. In other words, the lower segment of this 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 this lateral edge and the first plane may be the angle between the second straight segment to which the lower endpoint of this lower segment belongs, i.e., the line connecting the lower endpoint of this lower segment and the inflection point closest to the lower endpoint of this lower segment, and the first plane.If the upper segment of one lateral edge is a single straight segment, the angle c between this upper segment of this lateral edge and the first plane may be the angle between this straight segment and the first plane.If the upper segment of a lateral ridge is not a single straight line segment, the angle c between the upper segment of the lateral ridge and the first plane may be the angle between the first plane and a line connecting the upper end point of the upper segment to the lower end point of the upper segment. Similarly, the angle between the middle segment of a lateral ridge and the first plane may be the angle between the first plane and a line connecting the upper end point of the middle segment to the lower end point of the middle segment.

[0088] Optionally, the light-receiving surface and / or the non-light-receiving surface of the silicon substrate 1 may have any one of the textured structures. In this way, the position of the textured structure on the silicon substrate 1 can be flexibly set, and the textured structure has a larger specific surface area, lower reflectivity, better light trapping effect, and increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell. The solar cell also has a uniform black appearance, improving its appearance. For example, at least the light-receiving surface of the solar cell may have any one of the textured structures. For example, the solar cell may be a bifacial solar cell, in which the light-receiving surface of the silicon substrate 1 has any one of the textured structures, or the non-light-receiving surface of the silicon substrate 1 has any one of the textured structures, or both the light-receiving surface and the non-light-receiving surface of the silicon substrate 1 have any one of the textured structures. For example, the solar cell may be a back-contact solar cell, in which the light-receiving surface of the silicon substrate 1 has any one of the textured structures. For example, the solar cell may be a back-contact solar cell, in which the non-light-receiving surface of the silicon substrate 1 has any one of the textured structures. Alternatively, for example, this solar cell may be a back-contact solar cell, and both the light-receiving surface and the non-light-receiving surface of the silicon substrate 1 may have one of the texture structures described above. Alternatively, for example, this solar cell may be a back-contact solar cell, and it is not limited whether the light-receiving surface of the silicon substrate 1 has the texture structure described above. The non-light-receiving surface of the silicon substrate 1 includes alternating first and second regions, and the first region is doped with a first conductive element, or a first conductive layer is provided in the first region and the first conductive layer is doped with the first conductive element, and at least a portion of the second region is doped with a second conductive element, or a second conductive layer is provided on at least a portion of the second region and the second conductive layer is 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 conductivity type and the second conductivity type are different conductivity types. The first region has any one of the texture structures, or the second region has any one of the texture structures, or both the first region and the second region have any one of the texture structures.Alternatively, any one of the texture structures is provided in the second region other than the portion doped with the second conductive element. Alternatively, any one of the texture structures is provided in the second region other than the portion where the second conductive layer is provided. Furthermore, for example, this solar cell is a back-contact solar cell, and there is no limitation on whether the light-receiving surface of silicon substrate 1 has the texture structure described above. The non-light-receiving surface of silicon substrate 1 includes alternating first and second regions, with a first conductive layer formed in the first region and a second conductive layer formed in the second region. Here, the first conductive layer and the second conductive layer have different conductivity types, and an isolation region may be present between the first and second regions, and this isolation region may have any one of the texture structures described above. Alternatively, at least one of the first region, the second region, and the isolation region may have any one of the texture structures described above. Furthermore, for example, this solar cell is a back-contact solar cell, and there is no limitation on whether the light-receiving surface of silicon substrate 1 has the texture structure described above. The non-light-receiving surface of the silicon substrate 1 includes alternating first and second regions, with a first conductive layer formed in the first region and a second conductive layer formed in the second region. The first and second conductive layers have different conductivity types, at least partially overlap, and an insulating structure is provided where the first and second conductive layers overlap. At least one of the first and second regions may have one of the textured structures described above. The conductivity types are different, and may be p-type doped or n-type doped, respectively. For example, the solar cell is a back-contact solar cell, with the non-light-receiving surface of the silicon substrate 1 including alternating n-type and p-type regions, with the p-type region used to collect and conduct holes and the n-type region used to collect and conduct electrons, and with an isolation region between adjacent n-type and p-type regions. The light-receiving surface of the silicon substrate 1 has one of the texture structures, and / or the isolation region has one of the texture structures.Both the n-type and p-type regions are flat, and the formed conductive layers, passivation layers, and other film layers are of good quality. By providing a textured structure without forming a conductive layer in the isolation region, the reflectivity can be reduced, the light trapping effect can be improved, and the electrical performance of the back-contact solar cell can be improved. For example, this solar cell is a back-contact solar cell, and the non-light-receiving surface of the silicon substrate 1 includes alternating n-type and p-type regions, the p-type region has one of the textured structures, and the light-receiving surface of the silicon substrate 1 has one of the textured structures.

[0089] The present application also provides a solar module including a plurality of any one of the solar cells described above, and the number of solar cells in the solar module is not specifically limited. The solar module may further include a sealing adhesive film on both sides of the solar cell. Other configurations of the solar module are not specifically limited.

[0090] The present application further provides a method for fabricating any one of the solar cells described above. This method includes the steps of: performing a first texturing process on a silicon substrate 1; cleaning the silicon substrate 1 that has been subjected to the first texturing process; and performing a second texturing process on the cleaned silicon substrate 1. Here, the second texturing process irregularly etches the textured structure obtained by the first texturing process. The second texturing process reduces the inner diameter of the bottom contour line away from the apex of the approximately pyramidal structure, making the pyramidal surface rougher, and forming a sharper approximately pyramidal structure. The textured structure of the present application can be obtained by adjusting the process conditions for the second texturing process or by selecting an additive for the second texturing process that is different from that for the first texturing process.

[0091] Optionally, during the second texturing process, the additive components in the texturing liquid may include sodium benzoate, a defoaming agent, and a surfactant; and / or the mass content of the additive in the texturing liquid may be 0.01% to 5%; and / or the temperature of the texturing liquid may be 50°C to 85°C; and / or the second texturing time may be 30 seconds to 400 seconds. By appropriately setting the process parameters for the second texturing, it is easy to create any one of the textured structures described above. The textured structure of the present application can be obtained by adjusting the process conditions for the second texturing or by selecting different additives for the second texturing than those used in the first texturing. This texturing method may also be referred to as wet texturing. The actual structure of the textured structure obtained by wet texturing is complex, and it is difficult to ensure consistency in the morphology of all of the approximately pyramidal structures in the textured structure. However, it should be understood that the effects described in the present application can be achieved as long as the morphology of most of the approximately pyramidal structures in the textured structure meets the structural characteristics of the morphology described above.

[0092] The present application will be further described below with reference to specific examples. Example

[0093] In the first step, initial alkaline texturing was performed on a single-crystal silicon wafer to form pyramidal structures on the surface. The specific type of alkaline solution is not particularly limited and may be at least one selected from a sodium hydroxide (NaOH) solution and a potassium hydroxide (KOH) solution. The height of the formed pyramids was 0.5 μm to 3 μm. More specifically, the texturing solution in the first step may be a first reaction solution formed by mixing a 1% to 9% NaOH or KOH solution with Additive A. The first texturing was completed at a temperature range of 60°C to 85°C for 150 to 600 seconds. Specifically, a cleaned single-crystal silicon wafer was immersed in the first reaction solution, and the first texturing was performed within the temperature and time ranges to form pyramidal structures. The height of the pyramidal structures was 0.5 μm to 3 μm. The main components of Additive A include a surfactant, a dispersant, and an emulsifier. In the first texturing process, the mass ratio of additive A was varied from 0.01% to 5%.

[0094] In the second step, the single crystal silicon wafer that had been subjected to alkaline texturing in the first step was rinsed with DI (deionized water) to remove any remaining chemicals.

[0095] In the third step, the pyramidal texture washed with DI water was subjected to auxiliary polishing and a second texturing / etching process using a polishing and texturing solution. The additives were used to adjust the etching rate of the solution for each crystal orientation of the crystalline silicon, resulting in irregular etching of the pyramidal surfaces of the pyramidal texture. The pyramids were then further etched inward, gradually decreasing their width and gradually increasing the angle between their side edges and the first plane, forming a textured structure with a roughly pyramidal structure and lower reflectivity. During the second texturing process, the additives in the texturing solution may include sodium benzoate, a defoaming agent, and a surfactant. The mass content of the additives in the texturing solution was 0.01% to 5%. The texturing liquid in the second step may be a mixture of a 1% to 15% NaOH or KOH solution by mass with sodium benzoate, a defoaming agent, and a surfactant, the temperature of the texturing liquid is 50°C to 85°C, for example, 60°C to 85°C, and the time of the second texturing is 30 seconds to 400 seconds, for example, 30 seconds to 240 seconds. Here, an organic base may be used instead of the NaOH or KOH solution, and the organic base may be one of tetramethylammonium hydroxide, ethylenediamine, triethylamine, methylenediamine, and tetrabutylammonium hydroxide.

[0096] In the fourth step, the single-crystal silicon wafers processed in the third step were washed with DI water and cleaned with a mixture of alkali and hydrogen peroxide to remove chemical residues from the surface. In the fourth step, the total cleaning time was 60 to 150 seconds, and the cleaning temperature was 50 to 70°C.

[0097] In the fifth step, the structure obtained in the fourth step was subjected to ozone cleaning, acid cleaning, etc. to form a hydrophobic surface, which facilitates subsequent fabrication processes.

[0098] In the fifth step, the angle between the side edge and the first surface of the finally formed approximately pyramidal structure ranged from 50° to 85°. More specifically, the side edge was divided into an upper segment closest to the apex, a lower segment farthest from the apex, and a middle segment located between the lower and upper segments. The length of the lower segment was 1 / 4 of the length of the side edge, the length of the middle segment was 1 / 2 of the length of the side edge, and the length of the upper segment was 1 / 4 of the length of the side edge. In other words, the portion of the approximately pyramidal structure far from the apex was the lower portion of the approximately pyramidal structure, the height of this lower portion was 1 / 4 of the height of the approximately pyramidal structure, and the lower segment was the portion of the side edge corresponding to the lower portion. The portion of the approximately pyramidal structure close to the apex was the upper portion of the approximately pyramidal structure, the height of this upper portion was 1 / 4 of the height of the approximately pyramidal structure, and the upper segment was the portion of the side edge corresponding to the upper portion. The portion between the upper and lower portions of the approximately pyramidal structure is the middle portion, and the height of this middle portion accounts for half of the height of the approximately pyramidal structure. The middle segment is the portion corresponding to the middle portion of the side edge. The angle between the lower segment and the first plane is 50° to 55°, 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°. The texture structure of the silicon substrate of the solar cell finally fabricated in this example is as shown in Figures 1 to 3 and 5. The maximum inner diameter of the bottom contour line of this approximately pyramidal structure is 10 nm to 200 nm.

[0099] In the sixth step, a structure such as a passivation anti-reflection layer was subsequently formed on the single crystal silicon wafer obtained in the fifth step to obtain a solar cell. Comparative Example

[0100] The comparative example included only the first, fourth, fifth and sixth steps in the above-described examples, and the first, fourth, fifth and sixth steps were performed in that order, and the first, fourth, fifth and sixth steps corresponded to and were similar to the first, fourth, fifth and sixth steps in the examples, respectively.

[0101] The reflectance of the textured side of the solar cells of the example and comparative example was measured under the same measurement environment, and the measurement results are shown in Figure 6. In Figure 6, the abscissa represents the wavelength of the light irradiated onto the solar cell (unit: nm), and the ordinate represents reflectance. In Figure 6, the blue curve (lower curve) represents the corresponding reflectance in the example, and the red curve (upper curve) represents the corresponding reflectance in the comparative example. This shows that the solar cell of the example has a lower reflectance from the textured structure over most of the wavelength range available to the solar cell.

[0102] The electrical performance of the solar cells of the example and comparative example was measured under the same measurement environment, and the measurement results are shown in the table below.

[0103] [Table 1]

[0104] In the above table, Eta refers to photoelectric conversion efficiency, Voc refers to open-circuit voltage, Isc refers to short-circuit current, and FF refers to fill factor. From the above table, it can be seen that the photoelectric conversion efficiency, open-circuit voltage, short-circuit current, and fill factor of the solar cell of the example are all higher than those of the solar cell of the comparative example. The main reason for this is that the improved texture structure in the example reduces reflectivity, improves the light trapping effect, and enables an increase in short-circuit current, ultimately increasing the photoelectric conversion efficiency of the solar cell.

[0105] It should be noted that in this specification, contents with the same name may refer to each other, and in order to avoid repetition, the description will be omitted in each relevant place.

[0106] It should be noted that, although the embodiments of the method are expressed as a combination of a series of operations for convenience of explanation, those skilled in the art should understand that the embodiments of the present application are not limited by the order of operations described, since any steps may be performed in other orders or simultaneously according to the embodiments of the present application. Furthermore, those skilled in the art should also understand that all embodiments described in the specification are preferred embodiments, and that such operations are not necessarily required for the embodiments of the present application.

[0107] It should be understood that, as used herein, the terms "comprises," "having," or any other variation thereof, are intended to encompass a non-exclusive inclusion, whereby a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not expressly stated or inherent in such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that comprises the element.

[0108] From the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be realized in the form of a combination of software and a necessary general-purpose hardware platform, and of course, they can also be realized by hardware, but in many cases the former is a more preferred embodiment. Based on this view, the technical solutions of the present application can be substantially embodied as a software product, or a part that contributes to the prior art can be embodied as a software product, and the computer software product is stored in a storage medium (e.g., ROM / RAM, magnetic disk, optical disk) and includes a plurality of instructions that cause a terminal (which may be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to execute the methods described in each embodiment of the present application.

[0109] Although examples of the present application have been described above with reference to the drawings, the present application is not limited to the specific embodiments described above, which are merely illustrative and not limiting. Many forms that a person skilled in the art can make under the guidance of the present application without departing from the spirit of the present application and the scope of protection of the claims are all within the scope of protection of the present application. [Explanation of symbols]

[0110] 1. Silicon substrate 2. Passivation anti-reflection layer 11 Vertex 12 Branching Textures 13 Roughly circular texture 131 Pointed head 14 Bottom Contour 15 Each integral pyramidal structure

Claims

1. 1. A solar cell comprising: a silicon substrate; and a passivation anti-reflective layer overlying the silicon substrate, the surface of the silicon substrate has a textured structure, the textured structure includes a plurality of approximately pyramidal structures, each of the approximately pyramidal structures includes a pyramidal surface and an apex, the pyramidal surface of the approximately pyramidal structure includes a first sub-pyramid surface away from the apex and a second sub-pyramid surface, the second sub-pyramid surface is a remaining portion of the pyramidal surface of the approximately pyramidal structure other than the first sub-pyramid surface, the first sub-pyramid surface and the second sub-pyramid surface of the pyramidal surface of the approximately pyramidal structure have different surface forms, and the surface form of the sub-pyramid surface includes a waviness of the sub-pyramid surface or a roughness of the sub-pyramid surface, A solar cell, wherein the passivation anti-reflection layer includes a first portion on the first sub-cone surface and a second portion on the second sub-cone surface, and the thickness of the first portion is greater than the thickness of the second portion along the same direction approaching the apex.

2. the waviness of the first sub-conical surface is smaller than the waviness of the second sub-conical surface; Alternatively, the roughness of the first sub-cone surface is smaller than the roughness of the second sub-cone surface.

3. the thickness of the first portion is greater than the thickness of a portion of the passivation anti-reflection layer at a vertex; and / or, the thickness of the portions of the passivation antireflection layer located on adjacent portions of the adjacent pyramidal structures is greater than the thickness of the portions of the passivation antireflection layer located on the apexes; And / or the thickness of the portion of the passivation anti-reflection layer located on adjacent portions of the adjacent substantially pyramidal structures is greater than the thickness of the second portion.

4. 2. The solar cell according to claim 1, wherein in the passivation anti-reflection layer, a thickness variation between the first portion and the second portion is greater than 4%, and the thickness variation is calculated by dividing an absolute value of a difference between a first thickness at a first position in the first portion and a second thickness at a second position in the second portion along the same direction approaching the apex by the sum of the first thickness and the second thickness.

5. further comprising an aluminum oxide layer between the silicon substrate and the passivation anti-reflective layer; the aluminum oxide layer includes a third portion on the first sub-conical surface and a fourth portion on the second sub-conical surface; a thickness variation between the first portion and the second portion of the passivation antireflection layer is greater than a thickness variation between the third portion and the fourth portion of the aluminum oxide layer; the thickness variation between the first portion and the second portion in the passivation anti-reflection layer is calculated by dividing an absolute value of a difference between a first thickness at a first position in the first portion and a second thickness at a second position in the second portion along the same direction approaching the apex by a sum of the first thickness and the second thickness; 2. The solar cell of claim 1, wherein the thickness variation between the third portion and the fourth portion in the aluminum oxide layer is calculated by dividing the absolute value of the difference between a third thickness at a third position in the third portion and a fourth thickness at a fourth position in the fourth portion along the same direction approaching the vertex by the sum of the third thickness and the fourth thickness.

6. the passivation anti-reflection layer includes a front passivation anti-reflection layer on a light-receiving side of the silicon substrate and a back passivation anti-reflection layer on a non-light-receiving side of the silicon substrate; The solar cell according to claim 1 , wherein the thickness of the rear surface passivation anti-reflection layer is greater than the thickness of the front surface passivation anti-reflection layer at two positions opposite to each other in the thickness direction of the silicon substrate.

7. 7. The solar cell according to claim 6, wherein the difference in thickness between the back surface passivation anti-reflection layer and the front surface passivation anti-reflection layer at two opposing positions in the thickness direction of the silicon substrate is 15 nm or more and 40 nm or less.

8. The solar cell of claim 1 , wherein the cone surface of the approximately pyramidal structure has a branched texture, and the number of the branched textures on the second sub-cone surface is greater than the number of the branched textures on the first sub-cone surface.

9. The solar cell of claim 1 , wherein the apex of the generally pyramidal structure and the second sub-pyramidal surface of the pyramidal surface of the generally pyramidal structure have a set of nested generally annular textures.

10. The solar cell according to claim 9 , wherein in the set of substantially annular textures, the contour of the substantially annular texture becomes smaller along the height direction of the substantially pyramidal structure as it approaches the apex.

11. a portion of the substantially pyramidal structure away from the apex is a lower portion of the substantially pyramidal structure, and the height of the lower portion is at least 1 / 10 of the height of the substantially pyramidal structure; the first sub-pyramidal surface is a region corresponding to the lower portion of the pyramidal surface of the approximately pyramidal structure, The solar cell according to claim 1 , wherein the second sub-cone surface is a region of the cone surface of the approximately pyramidal structure that is closer to the apex than the first sub-cone surface.

12. The solar cell according to claim 1 , wherein the substantially pyramidal structure further includes a bottom contour line spaced apart from the apex, and the bottom contour line has a height difference at at least two points.

13. The solar cell according to claim 1 , wherein the textured structure has an apex angle of 55° to 90°.

14. The solar cell according to claim 1 , wherein the height of the approximately pyramidal structure is 0.2 μm to 3 μm.

15. The solar cell according to claim 1 , wherein the light-receiving surface and / or the non-light-receiving surface of the silicon substrate has the textured structure.

16. A solar module comprising a plurality of solar cells according to any one of claims 1 to 15.

Images