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] This application relates to the technical field of solar power generation, and more particularly to solar cells and solar modules.

[0002] (Cross-reference to related applications) This application claims the priority of a Chinese patent application with an application number of 202410175427.9 and an invention title of "Solar Cell and Solar Module", which was filed with the Chinese Patent Office on February 7, 2024, and all of its contents are incorporated herein by reference.

Background Art

[0003] Solar cells that convert light energy into electrical energy by the photovoltaic effect have broad application prospects by utilizing clean energy.

[0004] In solar cells, functional film layers such as a passivation antireflection layer are provided on the surface of the cell, particularly for the purpose of inactivating defects, obtaining a good antireflection effect, and increasing the short-circuit current. However, in conventional solar cells, the required passivation effect and antireflection effect vary depending on the position of the texture structure, and this has not been considered. As a result, a thick passivation film affects light absorption, or a thin passivation film affects the passivation effect, further affecting the performance of the cell.

Summary of the Invention

Problems to be Solved by the Invention

[0005] This application provides a solar cell and a solar module, and intends to solve the problem in solar cells that it is difficult to achieve both a passivation effect and an antireflection effect from the texture structure.

Means for Solving the Problems

[0006] In a first aspect of this application, A solar cell comprising a silicon substrate and a passivation anti-reflective layer on the silicon substrate, The surface of the silicon substrate has a textured structure, which includes a plurality of approximately pyramidal structures, each consisting of a pyramidal surface and a vertex, and the pyramidal surface of the approximately pyramidal structure includes a first sub-pyramidal surface and a second sub-pyramidal surface located away from the vertex, the second sub-pyramidal surface being the remaining part of the pyramidal surface of the approximately pyramidal structure other than the first sub-pyramidal surface, and the surface morphology of the first sub-pyramidal surface and the second sub-pyramidal surface differs within the pyramidal surface of the approximately pyramidal structure. The passivation anti-reflective layer includes a first portion on a first sub-pyramid and a second portion on a second sub-pyramid, and the passivation anti-reflective layer provides a solar cell in which the thickness of the first portion is greater than the thickness of the second portion along the same direction approaching the apex.

[0007] In this application, the first and second sub-conical surfaces of the pyramidal structure have different surface morphologies. By making the shape of the pyramidal surfaces of this pyramidal structure more irregular, the textured structure has a larger specific surface area, lower reflectivity, a better light confinement effect, an increase in short-circuit current, and ultimately an improved photoelectric conversion efficiency of the solar cell. Furthermore, the appearance of the solar cell becomes uniformly black, improving its aesthetics. In a silicon substrate, the conditions of the areas adjacent to the pyramidal structure are complex, often containing many voids, and the conditions of adjacent areas between adjacent pyramidal structures are also complex, often containing many voids. Therefore, a thick passivation anti-reflective layer is required at these locations to achieve a good passivation effect. Consequently, a thick passivation anti-reflective layer is also required on the first sub-conical surface adjacent to these locations to achieve a good passivation effect. On the other hand, at the vertices, there are often fewer voids, so a good passivation effect can be achieved even with a thin passivation anti-reflective layer. As a result, a good passivation effect can be achieved even on the second sub-pyramid surface adjacent to the vertex, even if the passivation anti-reflective layer is relatively thin. Therefore, in this application, by making the thickness of the first portion greater than the thickness of the second portion along the same direction approaching the vertex, it is possible to ensure that an excellent passivation effect can be obtained at any position. At the same time, in this application, since the thickness of the passivation anti-reflective layer is set according to the passivation demand, waste can be reduced. Furthermore, in this application, after the light rays are incident on passivation anti-reflective layers of different thicknesses, the optical path changes more times, the optical path length can be increased, and in cooperation with the texture structure of this application, absorption of light can be further improved, the light confinement effect can be improved, the short-circuit current can be further increased, the photoelectric conversion efficiency of the solar cell can be further increased, and the appearance of the solar cell becomes uniformly black, improving its appearance. In summary, this application not only ensures an excellent passivation effect at each position of the solar cell, but also significantly improves the anti-reflective effect and reduces waste.

[0008] Selectively, the undulation of the first sub-cone is smaller than the undulation of the second sub-cone. Alternatively, the roughness of the first sub-cone is less than the roughness of the second sub-cone.

[0009] Selectively, the thickness of the first portion is greater than the thickness of the apex portion in the passivation anti-reflective layer. and / or, in a passivation anti-reflective layer, the thickness of the portion on adjacent points of adjacent approximately pyramidal structures is greater than the thickness of the portion at the apex of the passivation anti-reflective layer. And / or, in the passivation anti-reflective layer, the thickness of the portion located on adjacent points of adjacent approximately pyramidal structures is greater than the thickness of the second portion.

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

[0011] Selectively, the solar cell further includes 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-pyramidal surface and a fourth portion on the second sub-pyramidal surface. The thickness variation between the first and second parts of the passivation anti-reflective layer is greater than the thickness variation between the third and fourth parts of the aluminum oxide layer. The thickness variation between the first and second parts of the passivation anti-reflective layer is calculated by dividing the absolute value of the difference between the first thickness at the first position in the first part and the second thickness at the second position in the second part, along the same direction approaching the apex, by the sum of the first and second thicknesses. The thickness variation between the third and fourth parts of the aluminum oxide layer is calculated by dividing the absolute value of the difference between the third thickness at the third position in the third part and the fourth thickness at the fourth position in the fourth part, along the same direction approaching the apex, by the sum of the third and fourth thicknesses.

[0012] Selectively, the passivation anti-reflective layer includes a 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 opposing positions in the thickness direction of the silicon substrate, the thickness of the backside passivation anti-reflective layer is greater than the thickness of the frontside passivation anti-reflective layer.

[0013] Selectively, at two opposing positions in the thickness direction of the silicon substrate, the difference in thickness between the backside passivation anti-reflective layer and the frontside passivation anti-reflective layer is 15 nm or more and 40 nm or less.

[0014] Selectively, the pyramidal faces of a roughly pyramidal structure have branched textures, and the number of branched textures in the second sub-pyramid face is greater than the number of branched textures in the first sub-pyramid face.

[0015] Selectively, the vertices of the approximately pyramidal structure and the second sub-pyramid faces of the pyramidal structures have a set of nested, approximately ring-shaped textures.

[0016] Selectively, in a set of roughly ring-shaped textures, the contour of the roughly ring-shaped texture becomes smaller as it approaches the vertices along the height direction of the roughly pyramidal structure.

[0017] Selectively, the portion of the pyramidal structure furthest from the vertex is the base of the pyramidal structure, and the height of the base accounts for at least 1 / 10 of the height of the pyramidal structure. The first sub-pyramidal surface is the region corresponding to the lower part of the pyramidal surface of the approximately pyramidal structure. The second sub-pyramidal surface is the region closer to the apex than the first sub-pyramidal surface in a pyramidal structure.

[0018] Selectively, the approximately pyramidal structure further includes a base contour line away from the vertex, and along the same base contour line, there is a difference in height at at least two points.

[0019] Optionally, the apex angle of the texture structure is from 55° to 90°.

[0020] Optionally, the height of the substantially pyramidal structure is from 0.2 μm to 3 μm.

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

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

Advantages of the Invention

[0023] The above solar cell and solar module have the same or similar beneficial effects, and for the sake of avoiding duplication, the description is omitted here.

Brief Description of the Drawings

[0024] In order to more clearly explain the technical solution means of the embodiments of the present application, hereinafter, the drawings used in the description of the embodiments of the present application will be briefly described. 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 creative effort.

[0025] [Figure 1] Shows a scanning electron microscope image of a first type of silicon substrate in an embodiment of the present application. [Figure 2] Shows a scanning electron microscope image of a second type of silicon substrate in an embodiment of the present application. [Figure 3] Shows a partial structural schematic diagram of a solar cell in an embodiment of the present application. [Figure 4] Shows a scanning electron microscope image of a third type of silicon substrate in an embodiment of the present application. [Figure 5] Shows a scanning electron microscope image of a fourth type of silicon substrate in an embodiment of the present application. [Figure 6] Shows a comparison diagram of the reflectance of a solar cell in an embodiment of the present application and a solar cell in a comparative example. [Modes for carrying out the invention]

[0026] The following describes the technical solutions in the embodiments of this application clearly and completely, with reference to the drawings of the embodiments. Naturally, the embodiments described are only a part of the embodiments of this application, not all of them. All other embodiments that a person skilled in the art could obtain based on the embodiments of this application without requiring any creative effort are all within the scope of protection of this application.

[0027] Conventional solar cells struggle to achieve both passivation and anti-reflective effects simultaneously, impacting battery performance. The main reason for this is that increasing the thickness of the passivation anti-reflective layer improves the passivation effect, but the anti-reflective effect decreases accordingly. This makes it difficult to achieve both effects simultaneously. The main concept of this application is to improve the anti-reflective effect by making the shape of the pyramidal surfaces of the approximately pyramidal structure more irregular, thereby increasing the specific surface area of ​​the textured structure. Based on this textured structure, the thickness of the passivation anti-reflective layer at each location can be set according to the passivation requirements at different locations, ensuring excellent passivation at all locations and reducing material waste in the passivation anti-reflective layer 2. Furthermore, after light rays enter the passivation anti-reflective layers of varying thicknesses, the optical path changes more frequently, increasing the optical path length. In conjunction with the textured structure of this application, this further improves light absorption and enhances the light confinement effect. In short, this application improves both the anti-reflective and passivation effects through the cooperation of a textured structure and a passivation anti-reflective layer.

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

[0029] Referring to Figures 1 to 5, this application provides a solar cell comprising a silicon substrate 1 and a passivation anti-reflective layer 2 on the silicon substrate 1. The silicon substrate 1 may have doping elements or may be intrinsic, and is not specifically limited. The silicon substrate 1 may be a single-crystal silicon substrate or the like, and is not specifically limited. The passivation anti-reflective layer 2 here can perform not only passivation but also anti-reflective functions. The material of the passivation anti-reflective layer 2 may be selected from silicon oxide and / or silicon oxynitride, and the specific material of the passivation anti-reflective layer 2 is not limited. The passivation anti-reflective layer 2 can be fabricated by methods such as plasma-enhanced chemical vapor deposition (PECVD), and the specific method of fabricating the passivation anti-reflective layer 2 is not specifically limited.

[0030] Referring to Figures 1 to 5, the surface of the silicon substrate 1 has a textured structure, which includes a plurality of approximately pyramidal structures. For example, in Figure 1, three approximately pyramidal structures in the textured structure are drawn with black lines. Each approximately pyramidal structure includes a pyramidal face and a vertex 11. The vertex 11 is the highest point in 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 vertex here may be the geometric center of this plane. In an approximately pyramidal structure, the pyramidal face of the approximately pyramidal structure is the set of all sides of the approximately pyramidal structure, i.e., all surfaces in the approximately pyramidal structure other than the base and the vertex. The vertex and the base contour line are connected by the pyramidal face of the approximately pyramidal structure, and the base contour line is the lowest contour line of the approximately pyramidal structure. The pyramidal face of the approximately pyramidal structure includes a first sub-pyramidal face and a second sub-pyramidal face, which are separated from the vertex. In other words, the first sub-pyramid is the part of the pyramidal surface furthest from vertex 11, i.e., the part of the pyramidal surface closest to the silicon substrate, and the second sub-pyramid is the remaining part of the pyramidal surface other than the first sub-pyramid. In Figure 3, the dashed lines L1 to L6 do not actually exist in the solar cell, but are merely notations to distinguish the first sub-pyramid and the second sub-pyramid, or to distinguish the lower segment and the first segment, which will be described later. For example, in Figure 3, in the case of the leftmost approximate pyramidal structure, the part of the pyramidal surface between the right side of dashed line L1 and the left side of the vertex of this leftmost approximate pyramidal structure, and the part between the left side of dashed line L2 and the right side of the vertex of this leftmost approximate pyramidal structure are the second sub-pyramid, and the part to the left of L1 and the part to the right of L2 are the first sub-pyramid. In the case of an intermediate pyramidal structure, the portion of the pyramidal surface between the right side of dashed line L3 and the left side of the vertex of this intermediate pyramidal structure, and the portion between the left side of dashed line L4 and the right side of the vertex of this intermediate pyramidal structure, is the second sub-pyramidal surface, while the portion to the left of L3 and the portion to the right of L4 are the first sub-pyramidal surfaces. In the case of the rightmost pyramidal structure, the portion of the pyramidal surface between the right side of dashed line L5 and the left side of the vertex of this rightmost pyramidal structure, and the portion between the left side of dashed line L6 and the right side of the vertex of this rightmost pyramidal structure, is the second sub-pyramidal surface, while the portion to the left of L5 and the portion to the right of L6 are the first sub-pyramidal surfaces.

[0031] The surface morphology of a sub-pyramid surface may include the undulation or roughness of the sub-pyramid surface. Undulation mainly refers to the degree of undulation due to relatively large height and depth structures on the surface, and roughness refers to the degree of unevenness due to minute protrusions and depressions on the surface. Referring to Figures 1 to 5, in a pyramidal surface with a roughly pyramidal structure, the first sub-pyramid surface and the second sub-pyramid surface, which are far from the vertex 11, have different surface morphologies, meaning that the first sub-pyramid surface and the second sub-pyramid surface differ in terms of undulation or roughness. In some cases, the number of protrusions and / or depressions on the second sub-pyramid surface may be greater than the number of protrusions and / or depressions on the first sub-tapered surface. In other cases, the degree of protrusions and / or depressions on the second sub-pyramid surface may be greater than the degree of protrusions and / or depressions on the first sub-pyramid surface. In other cases, the distribution of protrusions and / or depressions on the second sub-pyramid surface may be more non-uniform than the distribution of protrusions and / or depressions on the first sub-pyramid surface. In other cases, the height of the protrusions and / or depth of the depressions on the second sub-pyramid face may be greater than the height of the protrusions and / or depth of the depressions on the first sub-pyramid face. By making the shape of the pyramidal faces of the approximately pyramidal structure more irregular in this way, the textured structure has a larger specific surface area, lower reflectivity, a better light confinement effect, allows for an increase in short-circuit current, ultimately improves the photoelectric conversion efficiency of the solar cell, and also gives the solar cell a uniform black appearance, making it more aesthetically pleasing.

[0032] Referring to Figure 3, the passivation anti-reflective layer 2 includes a first portion on a first sub-pyramidal surface and a second portion on a second sub-pyramidal surface. In the passivation anti-reflective 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 magnitudes of the thickness of the first portion and the thickness of the second portion, the first and second portions are limited to being along the same direction approaching the vertex 11. In this specification, the first and second portions along the same direction approaching the vertex 11 can be understood as the first and second portions aligned sequentially in the direction from the base or base contour of a substantially pyramidal structure toward the vertex 11. Here, the direction of thickness is perpendicular to the tangent at the corresponding position on the outer surface of the passivation anti-reflective layer 2. Specifically, in the silicon substrate 1, the conditions of the areas adjacent to the approximately pyramidal structure are complex, often containing many voids. Similarly, the conditions of the areas adjacent to adjacent approximately pyramidal structures are also complex, often containing many voids. Therefore, a thick passivation anti-reflective layer is required at these locations to achieve a good passivation effect. Consequently, a thick passivation anti-reflective layer is also required on the first sub-pyramidal surface adjacent to these locations to achieve a good passivation effect. On the other hand, at the apex, there are often fewer voids, so a good passivation effect can be achieved even with a thin passivation anti-reflective layer. Consequently, a good passivation effect can be achieved even on the second sub-pyramidal surface adjacent to the apex, even with a relatively thin passivation anti-reflective layer. Therefore, in this application, by making the thickness of the first portion greater than the thickness of the second portion along the same direction approaching the apex, it is possible to ensure that an excellent passivation effect can be obtained at any location. Furthermore, in this application, since the thickness of the passivation anti-reflective layer is set according to the passivation demand, waste can be reduced.Furthermore, in this application, after the light rays enter the passivation anti-reflective layers of varying thicknesses, the optical path changes more frequently, increasing the optical path length. In cooperation with the texture structure of this application, absorption of light can be further improved, the light confinement effect is better, the short-circuit current can be further increased, the photoelectric conversion efficiency of the solar cell can be further enhanced, and the appearance of the solar cell becomes uniformly black, improving its aesthetics. Thus, this application not only ensures excellent passivation effects at each position of the solar cell, but also significantly improves the anti-reflective effect and reduces waste.

[0033] As shown in Figure 3, in the leftmost approximately pyramidal structure, the passivation anti-reflective layer 2 consists of a second portion, with the area between dashed lines L1 and L2 (excluding the vertex 11) being the second portion, and the area to the left of L1 and the area to the right of L2 being the first portion. Along the same direction L7 approaching the vertex 11, the thickness of the first portion is greater than that of the second portion. Along the same direction L8 approaching the vertex 11, the thickness of the first portion is greater than that of the second portion. In the intermediate approximately pyramidal structure, the passivation anti-reflective layer 2 consists of a second portion, with the area between dashed lines L3 and L4 (excluding the vertex 11) being the second portion, and the area to the left of L3 and the area to the right of L4 being the first portion. Along the same direction L9 approaching the vertex, the thickness of the first portion is greater than that of the second portion. In the first and second parts along the same direction L10 approaching the vertex, the thickness of the first part is greater than the thickness of the second part. In the rightmost approximately pyramidal structure, in the passivation anti-reflective layer 2, the part other than the vertex between dashed lines L5 and L6 is the second part, and the part to the left of L5 and the part to the right of L6 are the first part. In the first and second parts along the same direction L11 approaching the vertex, the thickness of the first part is greater than the thickness of the second part. In the first and second parts along the same direction L12 approaching the vertex, the thickness of the first part is greater than the thickness of the second part.

[0034] It should be explained that the thickness of a certain portion of the passivation anti-reflective layer 2 can be measured using instruments such as a transmission electron microscope. The thickness of a certain portion may be the thickness of that portion measured directly, or it may be the average of the thicknesses measured at multiple points selected within that portion. The measurement method is selected according to the actual measurability of the object being measured and is not specifically limited.

[0035] Selectively, referring to Figures 1 to 3 and Figure 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 be found in the correspondences described 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, a better light confinement effect, allows for an increase in short-circuit current, ultimately improves the photoelectric conversion efficiency of the solar cell, and the appearance of the solar cell becomes uniformly black, improving its aesthetics. As shown in Figure 3, in the case of the leftmost approximately pyramidal structure, the undulation of the first sub-pyramidal surface to the left of dashed line L1 and the first sub-pyramidal surface to the right of dashed line L2 is smaller than the undulation of the second sub-pyramidal surface between the right side of dashed line L1 and the left side of the vertex of this leftmost approximately pyramidal structure, and the undulation of the second sub-pyramidal surface between the left side of dashed line L2 and the right side of the vertex of this leftmost approximately pyramidal structure. Alternatively, the roughness of the first sub-pyramidal surface to the left of dashed line L1 and the first sub-pyramidal surface to the right of dashed line L2 is smaller than the roughness of the second sub-pyramidal surface between the right side of dashed line L1 and the left side of the vertex of this leftmost approximately pyramidal structure, and the roughness of the second sub-pyramidal surface between the left side of dashed line L2 and the right side of the vertex of this leftmost approximately pyramidal structure. In the case of an intermediate pyramidal structure, the undulation of the first sub-pyramidal surface to the left of dashed line L3 and the first sub-pyramidal surface to the right of dashed line L4 is smaller than the undulation of the second sub-pyramidal surface between the right side of dashed line L3 and the left side of the vertex of this intermediate pyramidal structure, and the undulation of the second sub-pyramidal surface between the left side of dashed line L4 and the right side of the vertex of this intermediate pyramidal structure. Alternatively, the roughness of the first sub-pyramidal surface to the left of dashed line L3 and the first sub-pyramidal surface to the right of dashed line L4 is smaller than the roughness of the second sub-pyramidal surface between the right side of dashed line L3 and the left side of the vertex of this intermediate pyramidal structure, and the roughness of the second sub-pyramidal surface between the left side of dashed line L4 and the right side of the vertex of this intermediate pyramidal structure.In the case of the rightmost approximately pyramidal structure, the undulation 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 undulation of the second sub-pyramidal surface between the right side of dashed line L5 and the left side of the vertex of this rightmost approximately pyramidal structure, and the undulation of the second sub-pyramidal surface between the left side of dashed line L6 and the right side of the vertex of this rightmost approximately pyramidal structure. Alternatively, 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 vertex of this rightmost approximately pyramidal structure, and the roughness of the second sub-pyramidal surface between the left side of dashed line L6 and the right side of the vertex of this rightmost approximately pyramidal structure.

[0036] Selectively, referring to Figure 3, in the passivation anti-reflective layer 2, the thickness of the first portion is greater than the thickness of the portion at the vertex 11 in the passivation anti-reflective layer 2. Specifically, in the silicon substrate 1, the conditions of the approximately pyramidal structure and the adjacent portions are complex, often containing many voids, and the conditions of the adjacent portions of adjacent approximately pyramidal structures are also complex, often containing many voids. Therefore, a thick passivation anti-reflective layer is required at these locations to achieve a good passivation effect. Consequently, a thick passivation anti-reflective layer is also required on the first sub-pyramidal surface adjacent to these locations to achieve a good passivation effect. On the other hand, at the vertices, there are often fewer voids, so a good passivation effect can be achieved even with a thin passivation anti-reflective layer. Therefore, in this application, by making the thickness of the first portion of the passivation anti-reflective layer 2 greater than the thickness of the portion at the vertex 11 of the passivation anti-reflective layer 2, it is possible to ensure that an excellent passivation effect can be obtained at any position. Furthermore, in this application, since the thickness of the passivation anti-reflective layer is set according to the passivation demand, waste can be reduced.In addition, in this application, after the light rays are incident on passivation anti-reflective layers of different thicknesses, the optical path changes more times, the optical path length can be increased, and in cooperation with the texture structure of this application, absorption of light can be further improved, the light confinement effect can be improved, the short-circuit current can be further increased, the photoelectric conversion efficiency of the solar cell can be further increased, and the appearance of the solar cell becomes uniformly black, which is aesthetically pleasing.

[0037] For example, as shown in Figure 3, in the case of the leftmost approximately pyramidal structure, the thickness of the first portion to the left of dashed line L1 and the first portion to the right of dashed line L2 in the passivation anti-reflective layer 2 is greater than the thickness of the portion at the vertex 11 of this leftmost approximately pyramidal structure in the passivation anti-reflective layer 2. In the case of the intermediate approximately pyramidal structure, the thickness of the first portion to the left of dashed line L3 and the first portion to the right of dashed line L4 in the passivation anti-reflective layer 2 is greater than the thickness of the portion at the vertex 11 of this intermediate approximately pyramidal structure in the passivation anti-reflective layer 2. In the case of the rightmost approximately pyramidal structure, the thickness of the first portion to the left of dashed line L5 and the first portion to the right of dashed line L6 in the passivation anti-reflective layer 2 is greater than the thickness of the portion at the vertex 11 of this rightmost approximately pyramidal structure in the passivation anti-reflective layer 2.

[0038] Referring to Figure 3, the area between dashed lines L2 and L3 is the adjacent area between the leftmost approximately pyramidal structure and the intermediate approximately pyramidal structure, and the area between dashed lines L4 and L5 is the adjacent area between the rightmost approximately pyramidal structure and the intermediate approximately pyramidal structure. Selectively, referring to Figure 3, the thickness of the portion of the passivation anti-reflective layer 2 that is located on the adjacent area of ​​adjacent approximately pyramidal structures is greater than the thickness of the portion of the passivation anti-reflective layer 2 that is located at the vertex 11. Specifically, in the silicon substrate 1, the situation at the adjacent areas of adjacent approximately pyramidal structures is complex and often contains many voids, so a thick passivation anti-reflective layer is required at these locations to achieve a good passivation effect. On the other hand, at the vertices, there are often fewer voids, so a good passivation effect can be achieved even with a thin passivation anti-reflective layer. Therefore, in this application, by making the thickness of the portion on adjacent substantially pyramidal structures in the passivation anti-reflective layer 2 greater than the thickness of the portion at the vertex 11 in the passivation anti-reflective layer 2, it is possible to ensure that an excellent passivation effect can be obtained at any position. At the same time, in this application, since the thickness of the passivation anti-reflective layer is set according to the passivation demand, waste can be reduced. Furthermore, in this application, after the light rays are incident on passivation anti-reflective layers of different thicknesses, the optical path changes more times, the optical path length can be increased, and in cooperation with the texture structure of this application, absorption of light can be further improved, the light confinement effect is better, the short-circuit current can be further increased, the photoelectric conversion efficiency of the solar cell can be further increased, and the appearance of the solar cell becomes uniformly black, which is aesthetically pleasing. As shown in Figure 3, the thickness of the portion between dashed lines L2 and L3 in the passivation anti-reflective layer 2 is greater than the thickness of the portion at the vertex 11 of the leftmost approximately pyramidal structure in the passivation anti-reflective layer 2, and also greater than the thickness of the portion at the vertex 11 of the intermediate approximately pyramidal structure in the passivation anti-reflective layer 2.In Figure 3, the thickness of the portion between dashed lines L4 and L5 in the passivation anti-reflective layer 2 is greater than the thickness of the portion at the apex of the rightmost approximately pyramidal structure in the passivation anti-reflective layer 2, and also greater than the thickness of the portion at the apex of the intermediate approximately pyramidal structure in the passivation anti-reflective layer 2.

[0039] Selectively, referring to Figure 3, the thickness of the portion of the passivation anti-reflective layer 2 located on adjacent areas of adjacent approximately pyramidal structures is greater than the thickness of the second portion of the passivation anti-reflective layer 2. Specifically, in the silicon substrate 1, the conditions at the adjacent areas of adjacent approximately pyramidal structures are complex and often contain many voids; therefore, a thick passivation anti-reflective layer is required at these locations to achieve a good passivation effect. On the other hand, at the vertices, there are often fewer voids, so a good passivation effect can be achieved even with a thin passivation anti-reflective layer. As a result, a good passivation effect can also be achieved at the second sub-pyramidal surface adjacent to the vertices, even with a relatively thin passivation anti-reflective layer. Therefore, in this application, by making the thickness of the portion on adjacent substantially pyramidal structures in the passivation anti-reflective layer 2 greater than the thickness of the second portion in the passivation anti-reflective layer 2, it is possible to ensure that an excellent passivation effect can be obtained at any position. At the same time, in this application, since the thickness of the passivation anti-reflective layer is set according to the passivation demand, waste can be reduced. Furthermore, in this application, after the light rays are incident on passivation anti-reflective layers of different thicknesses, the optical path changes more times, the optical path length can be increased, and in cooperation with the texture structure of this application, absorption of light can be further improved, the light confinement effect can be improved, the short-circuit current can be further increased, the photoelectric conversion efficiency of the solar cell can be further increased, and the appearance of the solar cell becomes uniformly black, which is aesthetically pleasing.

[0040] As shown in Figure 3, the thickness of the portion of the passivation anti-reflective layer 2 between dashed lines L2 and L3 is greater than the thickness of the second portion of the passivation anti-reflective layer 2 excluding the vertices between dashed lines L1 and L2, and is also greater than the thickness of the second portion of the passivation anti-reflective layer 2 excluding the vertices between dashed lines L3 and L4. In Figure 3, the thickness of the portion of the passivation anti-reflective layer 2 between dashed lines L4 and L5 is greater than the thickness of the second portion of the passivation anti-reflective layer 2 excluding the vertices between dashed lines L5 and L6, and is also greater than the thickness of the second portion of the passivation anti-reflective layer 2 excluding the vertices between dashed lines L3 and L4.

[0041] Selectively, in the passivation anti-reflective layer 2, the thickness variation between the first and second parts is greater than 4%. This thickness variation is calculated by dividing the absolute difference between the first thickness at the first position in the first part and the second thickness at the second position in the second part, along the same direction approaching the vertex, by the sum of the first and second thicknesses. Here, the first position in the first part is any position in the first part, and the second position in the second part is any position in the second part. In other words, here, the first and second parts are limited to being along the same direction approaching the vertex 11, and in the passivation anti-reflective layer 2, the thickness variation between the first and second parts is greater than 4%. Specifically, in the silicon substrate 1, the situation at adjacent locations of adjacent approximately pyramidal structures is complex, and there are often many voids; therefore, a thick passivation anti-reflective layer is required at these locations to achieve a good passivation effect. On the other hand, at the vertices, there are often fewer voids, so a good passivation effect can be achieved even with a thin passivation anti-reflective layer. As a result, a good passivation effect can also be achieved at the second sub-pyramid adjacent to the vertices, even with a relatively thin passivation anti-reflective layer. Therefore, in this application, by making the thickness variation between the first and second parts of the passivation anti-reflective layer 2 greater than 4%, it is possible to ensure that an excellent passivation effect can be obtained at any position. Furthermore, in this application, since the thickness of the passivation anti-reflective layer is set according to the passivation demand, waste can be reduced. Moreover, in this application, after the light rays are incident on passivation anti-reflective layers of different thicknesses, the optical path changes more times, the optical path length can be increased, and in cooperation with the texture structure of this application, absorption of light can be further improved, the light confinement effect can be improved, the short-circuit current can be further increased, the photoelectric conversion efficiency of the solar cell can be further increased, and the appearance of the solar cell becomes uniformly black, improving its appearance.

[0042] For example, in the passivation anti-reflective layer 2, the thickness variation between the first and second portions 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] Selectively, the solar cell may further include an aluminum oxide layer (not shown) between the silicon substrate 1 and the passivation anti-reflective layer 2. The thickness variation of the aluminum oxide layer is smaller than the thickness variation of the passivation anti-reflective layer 2. Here, thickness variation refers to the range of thickness variation. Specifically, the thickness variation of the aluminum oxide layer may be the absolute value of the difference between the thickness of the aluminum oxide layer at position 5 and the thickness of the aluminum oxide layer at position 6. Specifically, the thickness variation of the passivation anti-reflective layer 2 may be the absolute value of the difference between the thickness of the passivation anti-reflective layer 2 at position 7 and the thickness of the passivation anti-reflective layer 2 at position 8. Here, in the thickness direction of the silicon substrate, the projections of position 5 and position 7 overlap, and the projections of position 6 and position 8 overlap. Positions 5 and 6 are two different arbitrary positions in the aluminum oxide layer. Specifically, the aluminum oxide layer is usually obtained by atomic layer deposition, and the influence of surface morphology on atomic layer deposition is minimal. Therefore, 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 range from 3 nm (nanometers) to 7 nm. The thickness of the aluminum oxide layer can also be measured using a transmission electron microscope, but is not specifically limited. For example, the thickness variation of the aluminum oxide layer may be 0.0001 nm to 3 nm, and may be, for example, 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 anti-reflective layer 2 may be between 3.5 nm and 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, and 50 nm.

[0045] Selectively, the aluminum oxide layer includes a third portion on the first sub-pyramidal surface and a fourth portion on the second sub-pyramidal surface. The thickness variation of the first and second portions in the passivation anti-reflective layer 2 is greater than the thickness variation of the third and fourth portions in the aluminum oxide layer. For details on the thickness variation of the first and second portions in the passivation anti-reflective layer 2, please refer to the above description, and the explanation will be omitted here. The thickness variation of the third and fourth portions in the aluminum oxide layer is obtained by dividing 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 vertex, by the sum of the third and fourth thicknesses. Here, both the third and fourth portions are limited to aligning along the same direction approaching the vertex. Here, the third position in the third portion is any position in the third portion, and the fourth position in the fourth portion is any position in the fourth portion. The thickness variation between the first and second portions of the passivation anti-reflective layer 2 is greater than the thickness variation between the third and fourth portions of the aluminum oxide layer. In other words, the thickness variation of the passivation anti-reflective layer 2 is greater, and since the thickness of the passivation anti-reflective layer 2 is adjusted to the passivation requirements, it is possible to ensure that an excellent passivation effect is obtained at any position. Furthermore, in this application, since the thickness of the passivation anti-reflective layer is set according to the passivation requirements, waste can be reduced. In addition, in this application, after the light rays are incident on the passivation anti-reflective layers of different thicknesses, the optical path changes more times, and the optical path length can be increased. In cooperation with the texture structure of this application, absorption of light can be further improved, the light confinement effect is better, the short-circuit current can be further increased, the photoelectric conversion efficiency of the solar cell can be further increased, and the appearance of the solar cell becomes uniformly black, improving its appearance. It should be noted that the specific difference between the two thickness variations is not specifically limited.

[0046] Selectively, the passivation anti-reflective layer 2 includes a surface passivation anti-reflective layer on the light-receiving side of the silicon substrate 1 and a back surface passivation anti-reflective 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 surface passivation anti-reflective layer is greater than the thickness of the surface passivation anti-reflective layer. Specifically, as the thickness of the passivation anti-reflective layer increases, its passivation effect improves, but its anti-reflective effect decreases accordingly. Since the demand for anti-reflective properties on the non-light-receiving side is lower than on the light-receiving side, the passivation anti-reflective layer can achieve both passivation performance and anti-reflective properties by appropriately increasing the thickness of the back surface passivation anti-reflective layer to ensure excellent passivation performance on the non-light-receiving side and appropriately decreasing the thickness of the surface passivation anti-reflective layer.

[0047] Selectively, at two opposing positions in the thickness direction of the silicon substrate 1, the difference between the thickness of the back-side passivation anti-reflective layer and the thickness of the front-side passivation anti-reflective layer 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 is sufficiently ensured, while good passivation performance and anti-reflective effect are obtained on the light-receiving side, thus avoiding waste. For example, the thickness of the back-side passivation anti-reflective layer may be 85 nm to 100 nm, or about 95 nm. The thickness of the front-side passivation anti-reflective layer may be 60 nm to 70 nm, or about 65 nm. Here, at two opposing positions in the thickness direction of the silicon substrate 1, the difference between the thickness of the back surface passivation anti-reflective layer and the thickness of the front surface passivation anti-reflective layer 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] Selectively, referring to Figure 2, the pyramidal faces of the roughly pyramidal structure have a branched texture 12. The shape of the branched texture 12 resembles the shape of tree branches, and the branched texture 12 is a pattern that looks like it is branching out from the main trunk. The number of branched textures 12 on the second sub-pyramidal faces of the roughly pyramidal structure is greater than the number of branched textures 12 on the first sub-pyramidal faces that are farther from the vertex. There is a correspondence between the branched texture 12 and the projections or depressions on the pyramidal faces of the roughly pyramidal structure, and the branched texture 12 is usually located at the boundary between projections and depressions on the pyramidal faces of the roughly pyramidal structure, that is, the more branched textures 12 there are, the more projections and depressions there are on the pyramidal faces of the roughly pyramidal structure. Therefore, the more textures there are, the larger the specific surface area of ​​the texture structure becomes. The more irregular the distribution of the branched textures, the larger the specific surface area the texture structure can have, resulting in lower reflectivity, better light confinement, increased short-circuit current, and ultimately higher photoelectric conversion efficiency of the solar cell. Furthermore, the appearance of the solar cell becomes uniformly black, improving its aesthetic appeal. For example, in Figure 2, in the rightmost pyramidal structure, the first sub-pyramidal surface, far from the vertex, has almost no branched textures, but the second sub-pyramidal surface has a large number of branched textures.

[0049] Selectively, referring to Figure 4, the vertices 11 of the approximately pyramidal structure and the second sub-pyramidal faces of the pyramidal structures have a pair of nested approximately annular textures 13. Here, the approximately annular textures 13 may be open-shaped and / or closed-shaped. For example, in Figure 4, the pair of nested approximately annular textures 13 located in the center and attached to 13 have both open-shaped and closed-shaped patterns. In a pair of nested approximately annular textures 13, the number of approximately annular textures 13 is not specifically limited, and each approximately annular texture 13 is arranged in a nested manner with respect to the others. The first sub-pyramidal faces of the approximately pyramidal structure have almost no approximately annular textures. There is a correspondence between the roughly annular texture 13 and the protrusions or depressions on the pyramidal surface of the roughly pyramidal structure. The roughly annular texture 13 is usually located at the boundary between the protrusions and depressions on the pyramidal surface of the roughly pyramidal structure. That is, the more roughly annular textures 13 there are, the more protrusions and depressions there are on the pyramidal surface of the roughly 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 of the roughly annular textures, the larger the specific surface area of ​​the texture structure can be, resulting in lower reflectivity, better light confinement effect, increased short-circuit current, and ultimately higher photoelectric conversion efficiency of the solar cell. In addition, the appearance of the solar cell becomes uniformly black, improving its aesthetic appeal.

[0050] Referring to Figure 4, the roughly annular texture 13 here may be a wavy texture, i.e., a texture that appears to be irregularly stacked in a wavy manner under electron microscope detection, and / or the roughly annular texture 13 may be a rose-like texture, i.e., a texture that appears to be irregularly stacked like the multiple petals of a rose under electron microscope detection. In this way, the roughly annular texture 13 has an aesthetically pleasing shape, low reflectivity, and good light confinement effect. The roughly annular texture 13 is located on the pyramidal faces and vertices, or furthermore, the roughly annular texture 13 is located within the second sub-pyramidal face and on the vertices of the pyramidal face.

[0051] Selectively, referring to Figure 4, in a set of roughly annular textures 13, along the height direction of the roughly pyramidal structure, the contour of the roughly annular texture 13 becomes smaller as it approaches the vertex 11, and larger as it moves away from the vertex 11. This results in an irregular distribution of the roughly annular textures 13, and the specific surface area can be increased by the roughly annular textures 13. As a result, the texture structure has a larger specific surface area, lower reflectivity, a better light confinement effect, an increase in short-circuit current, and ultimately an improved photoelectric conversion efficiency of the solar cell. Furthermore, the appearance of the solar cell becomes uniformly black, improving its aesthetic appeal.

[0052] Selectively, referring to Figures 1 to 5, the portion of the roughly pyramidal structure away from the vertex 11 is the lower part of the roughly pyramidal structure, and the height of the lower part accounts for at least 1 / 10 of the height of the roughly pyramidal structure. In the pyramidal surface of the roughly pyramidal structure, the first sub-pyramidal surface away from the vertex 11 corresponds to the lower part of this pyramidal surface, and the second sub-pyramidal surface is the region of this pyramidal surface closer to the vertex 11 than the first sub-pyramidal surface. Specifically, by precisely distinguishing between the second and first sub-pyramidal surfaces here, it is not only advantageous for fabricating textured structures, but also results in lower reflectivity, better light confinement effect, increased short-circuit current, ultimately higher photoelectric conversion efficiency of the solar cell, and a uniform black appearance of the solar cell, improving its aesthetics. In this specification, regarding the ratio of the height of the lower part of the roughly pyramidal structure, it should be understood that the above effects can be achieved if the majority of the roughly pyramidal structures in the textured structure have a lower height that satisfies the above ratio.

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

[0054] Selectively, the portion of the roughly pyramidal structure away from the vertex 11 is the lower part of the roughly pyramidal structure, and the height of this lower part accounts for at least 1 / 5 of the height of the roughly pyramidal structure; the portion of the roughly pyramidal structure close to the vertex 11 is the upper part of the roughly pyramidal structure, and the height of this upper part accounts for at most 1 / 5 of the height of the roughly pyramidal structure; and the portion between the lower and upper parts of the roughly pyramidal structure is the middle part, and the height of this middle part accounts for at least 2 / 5 of the height of the roughly pyramidal structure. In the pyramidal surface of the roughly pyramidal structure, the first sub-pyramidal surface away from the vertex 11 is the region corresponding to the lower part of the pyramidal surface of the roughly pyramidal structure. The second sub-pyramidal surface is further divided into an upper sub-pyramidal surface and a middle sub-pyramidal surface. In the pyramidal surface of the roughly pyramidal structure, the upper sub-pyramidal surface is the region corresponding to the upper part of the pyramidal surface of the roughly pyramidal structure. In the pyramidal surface of the roughly pyramidal structure, the middle sub-pyramidal surface is the region corresponding to the middle part of the pyramidal surface of the roughly pyramidal structure. Precisely defining the three sub-pyramidal surfaces is advantageous not only for creating textured structures but also for reducing reflectivity, improving light confinement, increasing short-circuit current, ultimately enhancing the photoelectric conversion efficiency of solar cells, and resulting in a uniform black appearance for the solar cells, improving their aesthetics. In this specification, regarding the ratio of the upper height of the approximately pyramidal structure, it should be understood that the above effects can be achieved if the majority of the approximately pyramidal structures in the textured structure have an upper height that satisfies the aforementioned ratio. Similarly, in this specification, regarding the ratio of the middle height of the approximately pyramidal structure, it should be understood that the above effects can be achieved if the majority of the approximately pyramidal structures in the textured structure have a middle height that satisfies the aforementioned ratio.

[0055] For example, in a roughly pyramidal structure, the portion adjacent to vertex 11 is the upper part of the roughly pyramidal structure, and the height of the upper part occupies 1 / 10, 2 / 15, 3 / 20, 1 / 9, 1 / 8, 1 / 7, 1 / 6, or 1 / 5 of the height of the roughly pyramidal structure. Also, for example, in a roughly pyramidal structure, the portion between the upper and lower parts is the middle part, and the height of the middle part occupies 2 / 5, 13 / 30, 7 / 15, 1 / 2, 8 / 15, 17 / 30, or 3 / 5 of the height of this roughly pyramidal structure.

[0056] Selectively, referring to Figures 3 and 4, the approximately pyramidal structure further includes a base contour line 14 separated from the vertex 11, and there is a height difference at at least two points along the same base contour line 14. As shown in Figure 3, the leftmost, middle, and rightmost approximately pyramidal structures have a height difference between the left and right endpoints along their respective base contour lines, making the shape of the above-mentioned approximately pyramidal structures more irregular. As a result, the textured structure has a larger specific surface area, lower reflectivity, a better light confinement effect, allows for an increase in short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell, and the appearance of the solar cell becomes a uniform black color, improving its aesthetics.

[0057] Selectively, referring to Figure 1, the apex angle a of the textured structure is between 55° and 90°, where the apex angle of the textured structure is the angle between two opposing side edges passing through the vertex in a roughly pyramidal structure. Because the apex angle a of the textured structure is between 55° and 90°, the textured structure has a larger specific surface area, lower reflectivity, a better light confinement effect, allows for an increase in short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell, and the appearance of the solar cell becomes uniformly black, improving its aesthetics.

[0058] For example, the vertex 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] Selectively, the height of the approximately pyramidal structure is between 0.2 μm (microns) and 3 μm. Having an appropriate height for the approximately pyramidal structure results in a larger specific surface area for the textured structure, lower reflectivity, better light confinement, increased short-circuit current, and ultimately higher photoelectric conversion efficiency of the solar cell. Furthermore, the solar cell's appearance becomes uniformly black, improving its aesthetic appeal.

[0060] For example, the height of the approximately pyramidal structure may be between 0.5 μm and 3 μm, or the height of the approximately pyramidal structure 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] Selectively, the approximately pyramidal structure includes a vertex 11, a pyramidal face, and at least two lateral edges. The lateral edges of the approximately pyramidal structure are the common edges of adjacent faces in the approximately pyramidal structure. The lateral edge includes a lower segment away from the vertex 11 and a first segment, where the degree of bending of the lower segment is less than that of the first segment. The degree of bending of a subsegment of a lateral edge refers to the degree to which this subsegment is bent. Due to the irregular shape of each lateral edge, the textured structure has a larger specific surface area, lower reflectivity, a better light confinement effect, allows for an increase in short-circuit current, ultimately improves the photoelectric conversion efficiency of the solar cell, and also results in a uniform black appearance of the solar cell, making it more aesthetically pleasing. For example, in Figure 3, in the leftmost lateral edge of the leftmost approximately pyramidal structure, the degree of bending of the lower segment to the left of L1 is less than that of the first segment to the right of L1. In the leftmost pyramidal structure, at the rightmost lateral ridge, the degree of bending of the lower segment to the right of L2 is less than that of the first segment to the left of L2.

[0062] Selectively, referring to Figure 4, in the textured structure, the lower parts of at least two roughly pyramidal structures, away from at least vertices 11, are integrated, while the vertices of each integrated roughly pyramidal structure 15 are separated. This makes the textured structure more flexible and diverse in shape, and easier to manufacture. Because the vertices of each integrated roughly pyramidal structure 15 are separated, the textured structure has a larger specific surface area, lower reflectivity, a better light confinement effect, allows for an increase in short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell, and the appearance of the solar cell becomes uniformly black, improving its aesthetics. For example, in Figure 4, the lower parts of at least two roughly pyramidal structures enclosed in left-hand curly braces in the textured structure, away from at least vertices 11, are integrated, while the vertices of each integrated roughly pyramidal structure 15 are separated.

[0063] Selectively, the distance between the vertices of adjacent, integrated pyramidal structures 15 in a direction perpendicular to the height of the pyramidal structure may be greater than 0.2 μm and 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] Selectively, referring to Figure 4, in the textured structure, the lower parts of at least two roughly pyramidal structures, away from at least vertex 11, are integrated, and the vertices of each integrated roughly pyramidal structure 15 have height differences or are uniformly distributed. This makes the textured structure more flexible and diverse in shape, easier to manufacture, has a larger specific surface area, lower reflectivity, better light confinement effect, allows for increased short-circuit current, ultimately improves the photoelectric conversion efficiency of the solar cell, and results in a uniform black appearance for the solar cell, improving its aesthetics. For example, in Figure 4, the lower parts of the two roughly pyramidal structures enclosed in the left curly braces in the textured structure, away from at least vertex 11, are integrated, and the vertices of each integrated roughly pyramidal structure 15 have height differences. Also, for example, in Figure 4, the lower parts of the two roughly pyramidal structures enclosed in the right curly braces in the textured structure, away from at least vertex 11, are integrated, and the vertices of each integrated roughly pyramidal structure 15 are uniformly distributed.

[0065] Selectively, referring to Figure 4, in the textured structure, the lower parts of at least two approximately pyramidal structures, away from at least one vertex 11, are integrated, and the vertices of each integrated approximately pyramidal structure 15 have a height difference, which is greater than 0 and less than or equal to 1.6 microns. By rationally setting the height difference, the textured structure has a more rational specific surface area, lower reflectivity, and a better light confinement effect, while the passivation anti-reflective layers formed in different parts have different thicknesses, resulting in a longer optical path length for incident light and improved absorption of light rays.

[0066] For example, in a texture structure, the lower parts of at least two roughly pyramidal structures, away from at least one vertex 11, are integrated, and the vertices of each integrated roughly pyramidal structure 15 have a height difference, which may be 0.1 μm, 0.17 μm, 0.2 μm, 0.31 μm, 0.47 μm, 0.5 μm, 0.61 μm, 0.77 μm, 0.8 μm, 0.88 μm, 0.91 μm, 1 μm, 1.21 μm, 1.34 μm, 1.5 μm, or 1.6 μm.

[0067] Selectively, referring to Figure 4, in the textured structure, the lower parts of at least two approximately pyramidal structures, away from at least one vertex 11, are integrated, and the vertices of each integrated approximately pyramidal structure 15 have a height difference, which is greater than 0 and less than or equal to 0.8 microns. By making the height difference smaller, the textured structure has a more rational specific surface area, lower reflectivity, and a better light confinement effect, while the passivation anti-reflective layers formed in different parts have different thicknesses, which increases the optical path length of incident light and improves absorption of light rays.

[0068] For example, in a texture structure, the lower parts of at least two roughly pyramidal structures, away from at least one vertex 11, are integrated, and the vertices of each integrated roughly pyramidal structure 15 have a height difference, which may be 0.1 μm, 0.13 μm, 0.2 μm, 0.33 μm, 0.4 μm, 0.47 μm, 0.5 μm, 0.61 μm, 0.77 μm, or 0.8 μm.

[0069] Selectively, in the textured structure, at least the first sub-pyramidal surfaces of at least two approximately pyramidal structures are integrated, and the vertices of each integrated approximately pyramidal structure are separated. This results in a textured structure with a larger specific surface area, lower reflectivity, better light confinement effect, increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell, and also giving the solar cell a uniform black appearance, which is aesthetically pleasing. For example, in Figure 4, at least the first sub-pyramidal surfaces away from the vertices 11 of the two approximately pyramidal structures enclosed in curly braces in the textured structure are integrated, and the vertices of each integrated approximately pyramidal structure 15 are separated.

[0070] Selectively, within each integrated pyramidal structure, the annular textures on the pyramidal faces of different pyramidal structures are distributed separately. This results in a textured structure with a larger specific surface area, lower reflectivity, better light confinement, increased short-circuit current, ultimately higher photoelectric conversion efficiency of the solar cell, and a more aesthetically pleasing, uniformly black appearance of the solar cell. For example, in Figure 4, the lower parts of the two pyramidal structures enclosed in left-hand curly braces, at least away from vertex 11, are integrated, while the vertices of each integrated pyramidal structure 15 are separated. Alternatively, within each integrated pyramidal structure, the annular textures on the pyramidal faces of different pyramidal structures partially overlap. This results in a more flexible and diverse textured structure, a larger specific surface area, lower reflectivity, better light confinement, increased short-circuit current, ultimately higher photoelectric conversion efficiency of the solar cell, and a more aesthetically pleasing, uniformly black appearance of the solar cell. For example, in Figure 4, the lower parts of the two roughly pyramidal structures enclosed in the right-hand curly braces in the texture structure, at least away from the vertex 11, are integrated, and the roughly annular textures on the pyramidal faces of the different roughly pyramidal structures of each integrated roughly pyramidal structure 15 partially overlap. Here, the outermost roughly annular textures on the pyramidal faces of the different roughly pyramidal structures of each integrated roughly pyramidal structure 15 may also partially overlap.

[0071] Selectively, in a set of roughly annular textures, roughly annular textures are distributed in an overlapping manner at different positions along the height direction of the roughly pyramidal structure. This makes the texture structure flexible and diverse, resulting in a larger specific surface area, lower reflectivity, better light confinement effect, increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell, and also giving the solar cell a uniform black appearance, which is aesthetically pleasing. For example, in Figure 4, in the lowest set of roughly annular textures labeled 13, roughly annular textures 13 are distributed in an overlapping manner at different positions along the height direction of the roughly pyramidal structure.

[0072] Selectively, on the pyramidal surface of the approximately pyramidal structure, the approximately annular texture 13 may extend from a position close to the vertex 11 to at least a pyramidal surface position corresponding to a portion of the approximately pyramidal structure where the height difference from the vertex 11 is 2 / 3 of the height of the approximately pyramidal structure, or the approximately annular texture 13 may extend from a position close to the vertex 11 to at least a lateral position (i.e., pyramidal surface position) corresponding to a portion of the approximately pyramidal structure where the height difference from the vertex 11 is 1 / 2 of the height of the approximately pyramidal structure. By adjusting the position of the approximately annular texture 13, the position where the lateral protrusions and depressions are densely distributed can be adjusted, resulting in a larger specific surface area for the texture structure, especially the upper half of the texture structure, lower reflectivity, better light confinement effect, increased short-circuit current, ultimately higher photoelectric conversion efficiency of the solar cell, and a uniform black appearance for the solar cell, improving its aesthetics.

[0073] Selectively, the maximum inner diameter d1 of the roughly annular texture 13 is between 0.5 μm and 2 μm. By rationally setting the maximum inner diameter d1 of the roughly annular texture 13, not only is fabrication easier, but the texture structure has a larger specific surface area, lower reflectivity, a better light confinement effect, allows for an increase in short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell, and the appearance of the solar cell becomes uniformly black, improving its aesthetics.

[0074] For example, the maximum inner diameter d1 of the roughly 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. Alternatively, for example, the maximum inner diameter d1 of the roughly annular texture 13 may be between 0.55 μm and 1.8 μm, or between 0.6 μm and 1.6 μm.

[0075] Selectively, referring to Figure 4, in the same substantially annular texture, the maximum inner diameter of the substantially annular texture in at least two directions perpendicular to each other is not equal; that is, in the same substantially annular texture, the maximum inner diameter of the substantially annular texture in the first direction is not equal to the maximum inner diameter of the substantially annular texture in the second direction perpendicular to this first direction. As a result, the texture structure becomes more irregular in shape, the reflectivity decreases, the light confinement effect improves, the short-circuit current increases, ultimately the photoelectric conversion efficiency of the solar cell is enhanced, and the appearance of the solar cell becomes uniformly black, improving its aesthetics.

[0076] Selectively, referring to Figure 4, in the same set of substantially annular textures, at least one substantially annular texture 13 has a pointed tip 131 facing outward from the substantially annular texture 13, and this pointed tip 131 can increase the specific surface area. As a result, the texture structure has a larger specific surface area, lower reflectivity, a better light confinement effect, allows for an increase in short-circuit current, ultimately improves the photoelectric conversion efficiency of the solar cell, and the appearance of the solar cell becomes uniformly black, improving its aesthetics.

[0077] Selectively, referring to Figures 1 to 5, in the same approximately pyramidal structure, the dimension in the thickness direction of one of the two side edges on either side of the vertex 11 is larger than the other. This makes the shape of the approximately pyramidal structure more irregular, the textured structure has a larger specific surface area, lower reflectivity, a better light confinement effect, allows for an increase in short-circuit current, and ultimately improves the photoelectric conversion efficiency of the solar cell. In addition, the appearance of the solar cell becomes uniformly black, improving its aesthetics.

[0078] Selectively, referring to Figures 1 to 4, two adjacent pyramidal structures are arranged such that the relatively small side edges of one pyramidal structure are distributed close to the relatively small side edges of the other pyramidal structure. This results in a more irregular shape for the textured structure, giving it a larger specific surface area, lower reflectivity, a better light confinement effect, an increased short-circuit current, and ultimately higher photoelectric conversion efficiency for the solar cell. Furthermore, the solar cell has a uniform black appearance, making it more aesthetically pleasing.

[0079] Selectively, referring to Figures 1 to 4, in one side edge, the lower segment away from vertex 11 is a straight segment or a line segment having up to two inflection points. Specifically, for example, this lower segment is a single straight segment with only one slope, in which case this lower segment has no inflection points. Alternatively, this lower segment consists of two line segments, which may be one straight segment and one curved segment with one inflection point at their intersection, or two straight segments with different slopes that intersect with one inflection point. Alternatively, this lower segment may consist of three line segments, which may be composed of one straight segment, another straight segment, and one curved segment, with two straight segments having different slopes and one inflection point at the intersection of the three segments. Alternatively, this lower segment may consist of three straight segments, with three straight segments having different slopes and one inflection point at the intersection of two adjacent straights. Here, the lower segment can be obtained by employing conventional texturing methods and parameters, improving process adaptability.

[0080] Selectively, referring to Figures 1 to 4, in one side edge, the first segment other than the lower segment is a polylinear segment and / or a curved segment. The number of polylinear segments and curved segments included in this first segment is not specifically limited. In this way, the shape of the textured structure becomes more irregular, the textured structure has a larger specific surface area, lower reflectivity, a better light confinement effect, allows for an increase in short-circuit current, ultimately increases the photoelectric conversion efficiency of the solar cell, and the appearance of the solar cell becomes a uniform black color, improving its aesthetics.

[0081] For example, in Figure 3, in the leftmost pyramidal structure, the lower segment to the left of L1 consists of two straight segments and has one inflection point, while the first segment to the right of L1 consists of multiple polylinear segments and multiple curved segments. In the rightmost pyramidal structure, the lower segment to the right of L2 consists of one straight segment and has no inflection point, while the first segment to the left of L2 consists of multiple polylinear segments and multiple curved segments. In the middle pyramidal structure, the lower segment to the left of L3 consists of two straight segments and has one inflection point, while the first segment to the right of L3 consists of multiple polylinear segments and multiple curved segments. In the middle pyramidal structure, the lower segment to the right of L4 consists of three straight segments and has two inflection points, while the first segment to the left of L4 consists of multiple polylinear segments and multiple curved segments. In the rightmost pyramidal structure, on the left lateral edge, the lower segment to the left of L5 consists of two straight segments and one inflection point, while the first segment to the right of L5 consists of multiple polylinear segments and multiple curved segments. In the rightmost pyramidal structure, on the right lateral edge, the lower segment to the right of L6 consists of one straight segment and no inflection point, while the first segment to the left of L6 consists of multiple polylinear segments and multiple curved segments.

[0082] Selectively, the length of the lower segment of one side edge is at least 1 / 10 of the length of that side edge. Here, by precisely defining the lower segment and the first segment on one side edge, it is not only advantageous for creating a textured structure, but it also results in lower reflectivity, a better light confinement effect, an increase in short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell, and the appearance of the solar cell becomes uniformly black, making it more aesthetically pleasing.

[0083] For example, the length of the lower segment of one side ridge accounts for 1 / 10, 2 / 15, 3 / 20, 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, or 1 / 4 of the length of that side ridge.

[0084] The first plane perpendicular to the thickness direction of the silicon substrate 1 refers to the 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 such that the light-receiving or non-light-receiving side of the silicon substrate 1 faces away from this horizontal plane, the first plane is parallel to this horizontal plane. For example, in Figure 3, the first plane is shown by horizontal dashed lines extending to the left and right, and also, for example, in Figure 5, the first plane is shown by horizontal dashed lines extending to the left and right. Selectively, the angle between the lower segment of a side edge and the first plane perpendicular to the thickness direction of the silicon substrate 1 is smaller than the angle between the first segment of that side edge and this first plane. Specifically, by adjusting the etching rate of the chemical solution in each crystal orientation of the silicon substrate using etching additives, and by irregularly etching the side edges, the shape of the texture structure becomes more irregular. This results in a texture structure with a larger specific surface area, lower reflectivity, better light confinement effect, increased short-circuit current, and ultimately, higher photoelectric conversion efficiency of the solar cell. Furthermore, the appearance of the solar cell becomes uniformly black, improving its aesthetic appeal.

[0085] Selectively, the first segment of a side edge consists of an upper segment and a middle segment, where the upper segment is close to vertex 11, and the middle segment lies 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 part of a side edge furthest from vertex 11. In other words, the lower segment is the lowest part of this side edge. The upper segment is the part of this side edge closest to vertex 11. In other words, the upper segment is the highest part of this side edge. The middle segment is the middle part of this side edge. Precisely separating the lower, upper, and middle segments as described above is advantageous not only for creating textured structures but also for lower reflectivity, better light confinement effect, increased short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell, and resulting in a uniform black appearance for the solar cell, which is aesthetically pleasing.

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

[0087] Selectively, referring to Figure 3, the angle b between the lower segment of one side edge and the first plane is 50° to 55°, and referring to Figure 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 Figure 5, the white solid line is the inverse extension of the upper segment. By rationally setting the angles between the three subsegments and the first plane, fabrication becomes easier, the part near the vertex 11 in the approximately pyramidal structure becomes sharper, the reflectivity is lower, the light confinement effect is better, the short-circuit current can be increased, and ultimately the photoelectric conversion efficiency of the solar cell is increased, as well as the appearance of the solar cell becoming a uniform black color, which is aesthetically pleasing. If the lower segment of one side edge is a single straight segment, the angle b between the lower segment of this side edge and the first plane may be the angle between this straight 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 roughly pyramidal structure is a single straight segment, so the angle b between this lower segment of the right side edge and the first plane may be the angle between this straight segment and the first plane. If the lower segment of a side edge is not a single straight segment, the angle b between this lower segment of the side edge and the first plane may be the angle between the straight 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 roughly pyramidal structure consists of two straight segments and has one inflection point; in other words, this lower segment of the side edge is composed of a first straight segment and a second straight segment connected from top to bottom. In this case, the angle b between the lower segment of the side ridge and the first plane may be the angle between the second straight segment, which is the straight segment to which the lower endpoint of the lower segment belongs, that is, the line connecting the lower endpoint of the lower segment and the inflection point closest to the lower endpoint of the lower segment, and the first plane. If the upper segment of one side ridge is a single straight segment, the angle c between the upper segment of the side ridge and the first plane may be the angle between this straight segment and the first plane.If the upper segment of a side ridge is not a single straight segment, the angle c between the upper segment of this side ridge and the first plane may be the angle between the line connecting the upper endpoint of this upper segment and the lower endpoint of this upper segment and the first plane. Similarly, the angle between the middle segment of a side ridge and the first plane may be the angle between the line connecting the upper endpoint of this middle segment and the lower endpoint of this middle segment and the first plane.

[0088] Selectively, the light-receiving surface and / or non-light-receiving surface of the silicon substrate 1 have one of the textured structures. In this way, the position of the textured structure on the silicon substrate 1 can be flexibly set, the textured structure has a larger specific surface area, lower reflectivity, a better light confinement effect, an increase in short-circuit current, ultimately improving the photoelectric conversion efficiency of the solar cell, and the appearance of the solar cell becomes uniformly black, improving its aesthetics. For example, at least the light-receiving surface of the solar cell has one of the textured structures. Alternatively, for example, this solar cell is a double-sided solar cell, and the light-receiving surface of the silicon substrate 1 has one of the textured structures, or the non-light-receiving surface of the silicon substrate 1 has one of the textured structures, or both the light-receiving and non-light-receiving surfaces of the silicon substrate 1 have one of the textured structures. Alternatively, for example, this solar cell is a back-contact solar cell, and the light-receiving surface of the silicon substrate 1 has one of the textured structures. Alternatively, for example, this solar cell is a back-contact solar cell, and the non-light-receiving surface of the silicon substrate 1 has one of the textured structures. Furthermore, for example, this solar cell is a back-contact solar cell, and both the light-receiving surface and the non-light-receiving surface of the silicon substrate 1 have one of the aforementioned texture structures. Furthermore, for example, this solar cell is a back-contact solar cell, and it is not limited whether or not the light-receiving surface of the silicon substrate 1 has the aforementioned texture structure. The non-light-receiving surface of the silicon substrate 1 includes alternately distributed first and second regions, wherein 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 a 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 a second conductive element. Here, the first conductive element corresponds to a first conductivity type, the second conductive element corresponds to a second conductivity type, and the first conductivity type and the second conductivity type have different conductivity types. This first region has any one of the texture structures, or this second region has any one of the texture structures, or both this first region and this second region have any one of the texture structures.Alternatively, in the second region, one of the texture structures is provided in the portion other than the portion doped with the second conductive element. Alternatively, in the second region, one of the texture structures is provided in the portion other than the portion where the second conductive layer is provided. Furthermore, for example, this solar cell is a back-contact type solar cell, and it is not limited whether or not the light-receiving surface of the silicon substrate 1 has the above-described texture structure. The non-light-receiving surface of the silicon substrate 1 includes a first region and a second region that are alternately distributed, a first conductive layer is fabricated in the first region, and a second conductive layer is fabricated in the second region. Here, the first conductive layer and the second conductive layer have different conductivity types, and there may be an isolation region between the first region and the second region, and here, this isolation region may have one of the texture structures, or at least one of the first region, the second region, and the isolation region may have one of the texture structures. Furthermore, for example, this solar cell is a back-contact type solar cell, and it is not limited whether or not the light-receiving surface of the silicon substrate 1 has the above-described texture structure. The non-light-receiving surface of the silicon substrate 1 includes alternately distributed first and second regions, with a first conductive layer fabricated in the first region and a second conductive layer fabricated in the second region. Here, the first and second conductive layers have different conductivity types, and the first and second conductive layers overlap at least partially. An insulating structure is provided in the overlapping portion of the first and second conductive layers, and at least one of the first and second regions may have one of the aforementioned texture structures. The conductivity types described above are different, and in some cases, they may have p-type doping and n-type doping, respectively. Furthermore, for example, this solar cell is a back-contact type solar cell, and the non-light-receiving surface of the silicon substrate 1 includes alternately distributed n-type and p-type regions, with the p-type regions used to collect and conduct holes, and the n-type regions used to collect and conduct electrons, and there is 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, the quality of the formed conductive layer and passivation layer is good, and by providing a textured structure without creating a conductive layer in the isolated region, the reflectivity can be reduced and the light confinement effect can be improved, thereby improving the electrical performance of the back-contact solar cell. For example, this solar cell is a back-contact solar cell, and the non-light-receiving surface of the silicon substrate 1 includes alternately distributed n-type and p-type regions, the p-type region has one of the aforementioned textured structures, and the light-receiving surface of the silicon substrate 1 has one of the aforementioned textured structures.

[0089] This application further provides a solar module comprising one or more of the aforementioned solar cells, the number of solar cells in the solar module is not specifically limited. This solar module may further include sealing adhesive films on both sides of the solar cells. Other components of the solar module are not specifically limited.

[0090] This application further provides a method for manufacturing a solar cell to produce one of the solar cells described above. This manufacturing method includes the steps of: performing a first texturing on a silicon substrate 1; cleaning the silicon substrate 1 after the first texturing; and performing a second texturing on the cleaned silicon substrate 1. Here, the second texturing involves irregularly etching the texture structure obtained in the first texturing. The second texturing makes it possible to reduce the inner diameter of the bottom contour line away from the apex in the substantially pyramidal structure, make the pyramidal surface rougher, and so on, thereby forming a sharper substantially pyramidal structure. The texture structure of this application can be obtained by adjusting the process conditions of the second texturing, or by selecting a different additive for the second texturing than that used in the first texturing.

[0091] Selectively, in the second texturing process, the additive components in the texturing solution may include sodium benzoate, a defoaming agent, and a surfactant, and / or the mass content of the additive in the texturing solution is 0.01% to 5%, and / or the temperature of the texturing solution is 50°C to 85°C, and / or the duration of the second texturing is 30 s (seconds) to 400 s. By appropriately setting the process parameters of the second texturing, it becomes easy to produce any one of the above-mentioned texture structures. The texture structures of this application can be obtained by adjusting the process conditions of the second texturing, or by selecting different additives for the second texturing than those used in the first texturing. The texturing method may be called wet texturing. The actual structure of the texture structure obtained by wet texturing is complex, and it is difficult to ensure consistency in all forms of the approximately pyramidal structure in the texture structure, but it should be understood that the effects described in this application can be achieved if most of the forms of the approximately pyramidal structure in the texture structure satisfy the structural characteristics of the forms described above.

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

[0093] In the first step, an initial alkaline texturing was performed on a single-crystal silicon wafer to form a pyramidal structure on its surface. The specific type of alkaline solution is not specifically limited and may be at least one selected from sodium hydroxide (NaOH) solution and potassium hydroxide (KOH) solution. The height of the formed pyramidal structures ranged from 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% mass concentration NaOH solution or KOH solution with additive A. The first texturing was completed over 150 to 600 seconds at a temperature range of 60°C to 85°C. Specifically, a cleaned single-crystal silicon wafer was immersed in the first reaction solution, and the first texturing was performed within the aforementioned temperature and time range to form a pyramidal structure. The height of this pyramidal structure ranged from 0.5 μm to 3 μm. The main components of additive A include surfactants, dispersants, and emulsifiers. In the first texturing process, the mass ratio of additive A was set to 0.01% to 5%.

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

[0095] In the third step, the pyramid texture washed with the DI described above underwent auxiliary polishing and a second texturing and etching using a polishing and texturing solution. The etching rate of the chemical solution in each crystal orientation of the crystalline silicon was adjusted with additives to irregularly etch the pyramidal faces of the pyramid texture, and the pyramids were further etched inward, gradually reducing the width of the pyramids and gradually increasing the angle between the side edges and the first plane, thereby forming a textured structure with a roughly pyramidal structure and lower reflectivity. During the second texturing process, the additive components in the texturing solution may include sodium benzoate, a defoaming agent, and a surfactant, and the mass content of the additives in the texturing solution ranged from 0.01% to 5%. The texturing solution in the second step may be a mixture of a 1% to 15% NaOH solution or KOH solution with a mass concentration of sodium benzoate, a defoaming agent, and a surfactant. The temperature of the texturing solution was 50°C to 85°C, for example, 60°C to 85°C, and the duration of the second texturing was 30 s to 400 s, for example, 30 s to 240 s. Here, an organic base may be used instead of the NaOH solution 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 wafer processed in the third step was subjected to DI-based water washing and mixed washing with alkali and hydrogen peroxide to remove chemical residues from the surface. In the fourth step, the total washing time was set to 60s to 150s, and the washing temperature was set to 50°C 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, thereby facilitating subsequent fabrication processes.

[0098] In step 5, in the ultimately formed pyramidal structure, the angle between the lateral edge and the first surface ranged from 50° to 85°. More specifically, the lateral edge can be divided into an upper segment close to the vertex, a lower segment furthest from the vertex, and a middle segment between the lower and upper segments. The length of the lower segment is 1 / 4 of the length of this lateral edge, the length of the middle segment is 1 / 2 of the length of this lateral edge, and the length of the upper segment is 1 / 4 of the length of this lateral edge. In other words, the part of the pyramidal structure furthest from the vertex is the lower part of the pyramidal structure, the height of this lower part is 1 / 4 of the height of this pyramidal structure, and the lower segment corresponds to the lower part of this lateral edge. The part of the pyramidal structure close to the vertex is the upper part of the pyramidal structure, the height of this upper part is 1 / 4 of the height of this pyramidal structure, and the upper segment corresponds to the upper part of this lateral edge. The portion between the upper and lower parts of the roughly pyramidal structure is the middle section, and the height of this middle section accounts for half the height of the roughly pyramidal structure. The middle segment corresponds to the middle section of this side edge. The angle between the lower segment and the first plane is 50° to 55°, the angle c between the upper segment and this first plane is 55° to 80°, and the angle between this middle segment and this first plane is 55° to 85°. The texture structure of the silicon substrate of the solar cell finally fabricated in the example is shown in Figures 1 to 3 and Figure 5. The maximum inner diameter of the bottom contour line of this roughly pyramidal structure is 10 nm to 200 nm.

[0099] In the sixth step, a structure such as a passivation anti-reflective layer was fabricated 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 of the above-described embodiment, with the first, fourth, fifth, and sixth steps performed in that order, and the first, fourth, fifth, and sixth steps being the same as the first, fourth, fifth, and sixth steps of the embodiment, respectively.

[0101] Under the same measurement environment, the reflectance of the side of the solar cell with the textured structure in the example and comparative example was measured, and the measurement results are shown in Figure 6. In Figure 6, the horizontal coordinate is the wavelength of the light irradiated onto the solar cell (wavelength) in nm, and the vertical coordinate is the 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. From this, it can be seen that the solar cell of the example has a lower reflectance of the textured structure in most of the wavelength range that the solar cell can use.

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

[0103] [Table 1]

[0104] In the table above, Eta represents the photoelectric conversion efficiency, Voc represents the open-circuit voltage, Isc represents the short-circuit current, and FF represents the curve factor. From the table above, it can be seen that the photoelectric conversion efficiency, open-circuit voltage, short-circuit current, and curve factor of the solar cell in the example are all higher than those of the solar cell in the comparative example. The main reason for this is that in the example, by improving the texture structure, the reflectivity is reduced, the light confinement effect is improved, the short-circuit current can be increased, and ultimately the photoelectric conversion efficiency of the solar cell is increased.

[0105] It should be explained that, within this specification, content with the same name can be referenced to one another, and to avoid duplication, explanations are omitted in each relevant section.

[0106] It should be noted that, for the sake of clarity, the embodiments of the method are presented as a combination of a series of operations. However, those skilled in the art should understand that, according to the embodiments of this application, any steps can be performed in a different order or simultaneously, and therefore the embodiments of this application are not limited by the described order of operations. Furthermore, those skilled in the art should understand that all embodiments described in the specification are preferred embodiments, and such operations are not necessarily essential to the embodiments of this application.

[0107] It should be noted that in this specification, the terms “include,” “compose,” or any other variations thereof are intended to encompass non-exclusive inclusion, thereby including not only those elements but also other elements not explicitly stated, or elements specific to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase “includes one…” does not preclude the existence of other identical elements in a process, method, article, or apparatus that includes that element.

[0108] From the above description of the embodiments, it will be clear to those skilled in the art 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 may 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 realized substantially or in part with respect to the prior art as a software product, said computer software product stored in a storage medium (e.g., ROM / RAM, magnetic disk, optical disk) and containing a plurality of instructions that cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods of each embodiment of the present application.

[0109] While embodiments of this application have been described above with reference to the drawings, this application is not limited to the above-described specific embodiments. The above-described specific embodiments are merely illustrative and not limiting. Many forms that a person skilled in the art could make under the influence of this application without departing from the spirit of this application and the scope of protection of the claims are all within the scope of protection of this application. [Explanation of symbols]

[0110] 1. Silicon substrate 2. Passivation anti-reflective layer 11 vertices 12 Branching Textures 13. A roughly circular texture 131 Pointed head 14. Bottom contour line 15. Each approximately pyramidal structure as a whole

Claims

1. A solar cell comprising a silicon substrate and a passivation anti-reflective layer on the silicon substrate, The surface of the silicon substrate has a textured structure, the textured structure includes a plurality of substantially pyramidal structures, each substantially pyramidal structure consists of a pyramidal surface and a vertex, the pyramidal surface of the substantially pyramidal structure includes a first sub-pyramidal surface and a second sub-pyramidal surface separated from the vertex, the second sub-pyramidal surface is the remaining portion of the pyramidal surface of the substantially pyramidal structure other than the first sub-pyramidal surface, the surface morphology of the pyramidal surface of the substantially pyramidal structure differs between the first sub-pyramidal surface and the second sub-pyramidal surface, the surface morphology of the first sub-pyramidal surface includes waviness or roughness, the surface morphology of the second sub-pyramidal surface includes waviness or roughness A solar cell in which the passivation anti-reflective layer includes a first portion on the first sub-pyramid and a second portion on the second sub-pyramid, wherein the thickness of the first portion is greater than the thickness of the second portion in the same direction approaching the apex.

2. The solar cell according to claim 1, wherein the waviness of the first sub-cone is smaller than the waviness of the second sub-cone, or the roughness of the first sub-cone is smaller than the roughness of the second sub-cone.

3. The solar cell according to claim 1, wherein the thickness of the first portion is greater than the thickness of the portion at the apex of the passivation anti-reflective layer, and / or, the thickness of the portion of the passivation anti-reflective layer located on adjacent portions of the substantially pyramidal structure is greater than the thickness of the portion at the apex of the passivation anti-reflective layer, and / or, the thickness of the portion of the passivation anti-reflective layer located on adjacent portions of the substantially pyramidal structure is greater than the thickness of the second portion.

4. The solar cell according to claim 1, wherein in the passivation anti-reflective layer, the thickness variation between the first portion and the second portion is greater than 4%, and the thickness variation is obtained 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 approaching the vertex by the sum of the first thickness and the second thickness.

5. The solar cell according to claim 1, further comprising an aluminum oxide layer between the silicon substrate and the passivation anti-reflective layer, wherein the aluminum oxide layer comprises a third portion on the first sub-pyramid and a fourth portion on the second sub-pyramid, the thickness unevenness of the first portion and the second portion in the passivation anti-reflective layer is greater than the thickness unevenness of the third portion and the fourth portion in the aluminum oxide layer, the thickness unevenness of the first portion and the second portion in the passivation anti-reflective layer is obtained 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 approaching the vertex by the sum of the first thickness and the second thickness, and the thickness unevenness of the third portion and the fourth portion in the aluminum oxide layer is obtained 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 approaching the vertex by the sum of the third thickness and the fourth thickness.

6. The solar cell according to claim 1, wherein the passivation anti-reflective layer includes a 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, and at two opposing positions in the thickness direction of the silicon substrate, the thickness of the back surface passivation anti-reflective layer is greater than the thickness of the surface passivation anti-reflective layer.

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

8. The solar cell according to claim 1, wherein the pyramidal surface of the substantially pyramidal structure has a branched texture, 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.

9. The portion of the approximate pyramidal structure that is away from the vertex is the lower part of the approximate pyramidal structure, and the height of the lower part accounts for at least 1 / 10 of the height of the approximate pyramidal structure. The first sub-pyramidal surface is a region corresponding to the lower part of the pyramidal surface of the substantially pyramidal structure, The solar cell according to any one of claims 1 to 8, wherein the second sub-pyramidal surface is a region of the pyramidal surface of the substantially pyramidal structure that is closer to the vertex than the first sub-pyramidal surface.

10. The solar cell according to any one of claims 1 to 8, wherein the substantially pyramidal structure further includes a bottom contour line away from the vertex, and there is a difference in height at at least two points along the same bottom contour line.

11. The solar cell according to any one of claims 1 to 8, wherein the apex angle of the texture structure is 55° to 90°.

12. The solar cell according to any one of claims 1 to 8, wherein the height of the substantially pyramidal structure is 0.2 μm to 3 μm.

13. The solar cell according to any one of claims 1 to 8, wherein the light-receiving surface and / or non-light-receiving surface of the silicon substrate has the textured structure.

14. A solar module comprising a plurality of solar cells according to any one of claims 1 to 8.

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