Solar cell and preparation method thereof, photovoltaic module

Abstract

The application discloses a solar cell and a preparation method and a photovoltaic module thereof. The solar cell comprises a silicon substrate, and a back light surface of the silicon substrate comprises a first region and a second region with different surface structures. The first region has a textured structure, and the textured structure comprises a plurality of pyramid-like protrusions. The second region has a flat structure. The first region comprises a textured region, and the textured region comprises a first sub-region and a second sub-region arranged around the first sub-region. The first sub-region is distributed with a plurality of cluster structures, and the cluster structures are formed by aggregation of the pyramid-like protrusions. The cluster structure comprises a middle pyramid-like protrusion and an edge pyramid-like protrusion arranged around the middle pyramid-like protrusion. The top of part of the edge pyramid-like protrusions is offset to the direction of the middle pyramid-like protrusion relative to the geometric center of the bottom of the edge pyramid-like protrusion. The application can effectively improve the double-side rate and photoelectric conversion efficiency of the solar cell.

Description

Technical Field

[0001] This application relates to the technical field of solar cells, and more particularly to a solar cell and its preparation method, and a photovoltaic module. Background Technology

[0002] In solar cells, polishing the back surface of a silicon substrate to create a flat structure can improve the deposition quality of functional films (such as dielectric layers, doped polycrystalline silicon layers, or back surface passivation layers) on the back surface. However, this back surface structure limits the absorption and utilization of light by the solar cell, making it difficult to further improve the bifaciality and photoelectric conversion efficiency of solar cells. Summary of the Invention

[0003] To improve the bifaciality and photoelectric conversion efficiency of solar cells, this application provides a solar cell, its fabrication method, and a photovoltaic module.

[0004] In a first aspect, embodiments of this application provide a solar cell.

[0005] A solar cell includes a silicon substrate, the back surface of the silicon substrate including a first region and a second region with different surface structures, the first region having a textured structure and the textured structure including a plurality of pyramid-like protrusions, and the second region having a flat structure. The first region includes a textured region, which includes a first sub-region located in the middle and a second sub-region surrounding the first sub-region. The first sub-region has a plurality of clustered structures, which are formed by the aggregation of multiple pyramid-shaped protrusions. The clustered structures include a central pyramid-shaped protrusion and edge pyramid-shaped protrusions surrounding the central pyramid-shaped protrusion. The tops of some of the edge pyramid-shaped protrusions are offset toward the central pyramid-shaped protrusion relative to the geometric center of the bottom of the edge pyramid-shaped protrusions.

[0006] As an optional implementation, in the embodiments of this application, in the cluster-like structure, the overlap of the edge pyramid-shaped protrusions is greater than the overlap of the middle pyramid-shaped protrusions; And / or, the number of clustered structures in the first sub-region is greater than the number of clustered structures in the second sub-region.

[0007] As an optional implementation, in the embodiments of this application, the texture regions are periodically spaced and distributed within the first region.

[0008] As an optional implementation, in an embodiment of this application, the first region further includes a third sub-region in addition to the textured region, and the third sub-region has a plurality of the clustered structures distributed near the edge of the second sub-region.

[0009] As an optional implementation, in the embodiments of this application, the proportion of the textured region to the area of ​​the first region is 10% to 60%.

[0010] As an optional implementation, in an embodiment of this application, there is a transition region between the first region and the second region. The transition region includes the velvety structure and the flat structure. The density of the pyramid-shaped protrusions near the first region in the transition region is greater than the density of the pyramid-shaped protrusions near the second region in the transition region.

[0011] As an optional implementation, in an embodiment of this application, the second region has a ramp structure near the edge of the transition region, and the width of the transition region is 10 μm to 30 μm, calculated from the boundary between the ramp structure and the transition region. In the transition region, the area of ​​the velvet structure accounts for 40% to 80%.

[0012] As an optional implementation, in an embodiment of this application, the average base size of the pyramid-like protrusions in the transition region is greater than the average base size of the pyramid-like protrusions in the first region near the transition region.

[0013] As an optional implementation, in the embodiments of this application, the first region and the second region are alternately arranged; The solar cell also includes: A dielectric layer and a first doped semiconductor layer are sequentially stacked on the second region; A backlight passivation layer, the backlight passivation layer covering the first region and the surface of the first doped semiconductor layer away from the silicon substrate; The first electrode passes through the backlight passivation layer and forms an ohmic contact with the first doped semiconductor layer; A second doped semiconductor layer is disposed on the light-receiving side of the silicon substrate; A light-receiving passivation layer is located on the side of the second doped semiconductor layer away from the silicon substrate; The second electrode passes through the passivation layer of the light-receiving surface and forms an ohmic contact with the second doped semiconductor layer.

[0014] Secondly, embodiments of this application provide a method for preparing a solar cell.

[0015] A method for fabricating a solar cell includes the following steps: A silicon substrate is provided, wherein the back surface of the silicon substrate has a flat structure, and a dielectric layer, a first doped semiconductor layer and a mask layer are sequentially stacked on the back surface of the silicon substrate. A portion of the mask layer is subjected to laser patterning and opening to form a laser-treated area and an untreated area, wherein the mask layer is partially removed in the laser-treated area. Remove the remaining mask layer in the laser-treated area, as well as the first doped semiconductor layer and the dielectric layer located below the laser-treated area; A first region with a textured structure is formed on the surface of the silicon substrate; in the region that has not been laser-treated, the mask layer, the first doped semiconductor layer, and the dielectric layer are retained, and the surface of the silicon substrate is a second region that maintains the flat structure. Remove the mask layer; The first region includes a textured region, which includes a first sub-region located in the middle and a second sub-region surrounding the first sub-region. The first sub-region has several clustered structures, which are formed by the aggregation of multiple pyramid-shaped protrusions. The clustered structures include a central pyramid-shaped protrusion and edge pyramid-shaped protrusions surrounding the central pyramid-shaped protrusion. The top of the edge pyramid-shaped protrusions is offset towards the central pyramid-shaped protrusion relative to the geometric center of the bottom of the edge pyramid-shaped protrusions.

[0016] As an optional implementation, in the embodiments of this application, the recess depth of the surface of the first region relative to the second region is 1 μm to 2 μm; And / or, In the laser patterning film-opening step, the lateral overlap rate of the laser spot is controlled to be 6%~8%, and the longitudinal overlap rate is controlled to be 15%~19%. And / or, In the step of removing the remaining mask layer in the laser-treated area and the first doped semiconductor layer and the dielectric layer located below the laser-treated area, alkaline etching is performed using an inorganic alkaline solution. The inorganic alkaline solution used for alkaline etching includes sodium hydroxide solution and potassium hydroxide solution. The volume fraction of the inorganic alkaline solution is 15%~20%. The alkaline etching temperature is 82℃~85℃. The alkaline etching time is 8 min~10 min. And / or, The step of preparing the first region having the textured surface structure involves texturing and etching using a texturing alkaline solution. The texturing alkaline solution used for texturing and etching includes the inorganic alkali and a texturing additive. In the texturing alkaline solution, the volume fraction of the inorganic alkali is 15%~20%, the volume fraction of the texturing additive is 0.7%~0.9%, the texturing etching temperature is 75℃~80℃, and the texturing etching time is 7 min~9 min.

[0017] Thirdly, embodiments of this application provide a photovoltaic module.

[0018] A photovoltaic module includes a solar cell as described in the first aspect, or a solar cell prepared by the method described in the second aspect.

[0019] Compared with the prior art, the beneficial effects of this application are as follows: This application effectively improves the light absorption and utilization rate of solar cells by setting a textured region formed by the combination of a first sub-region and a second sub-region, while also improving the quality of subsequently deposited functional films. Specifically, from the perspective of the geometric morphology of the cluster structure, the tops of some edge pyramid-shaped protrusions are offset relative to the geometric center of the bottom of the edge pyramid-shaped protrusions towards the top of the intermediate pyramid-shaped protrusions, causing these edge pyramid-shaped protrusions to tilt towards the intermediate pyramid-shaped protrusions. This results in a smoother surface profile for the edge pyramid-shaped protrusions, thereby improving the overall smoothness of the surface of the first sub-region. This smooth morphology provides a more suitable growth substrate for the deposition of functional films, which is conducive to forming high-quality films with uniform thickness and high density, thus significantly improving the surface passivation effect of the first sub-region and reducing carrier recombination. Furthermore, during the photovoltaic module encapsulation process, the smooth morphology of the first sub-region helps reduce the flow resistance of the encapsulating film (such as EVA or POE) during the lamination process, allowing the encapsulating film to fill the gaps in the backlight more fully and evenly. This effectively avoids the problems of voids or poor interface contact that may occur due to the steep structure and excessive aspect ratio of the textured surface, thus enhancing the reliability and long-term stability of the encapsulation.

[0020] Furthermore, this application also retains a second region with a flat structure on the back surface. This second region provides an excellent substrate for the deposition of subsequent functional films (such as dielectric layers, doped polycrystalline silicon layers, or back surface passivation layers), which is beneficial for forming high-quality functional films and thus significantly reduces the carrier surface recombination rate. Through the cooperation of the first and second regions, the light absorption and surface passivation effects of the silicon substrate back surface can be synergistically enhanced, ultimately achieving a further improvement in the photoelectric conversion efficiency of the solar cell. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of the solar cell disclosed in the embodiments of this application; Figure 2 This is a SEM (scanning electron microscope) image of the first and second regions of the backlight surface of a silicon substrate, as disclosed in the embodiments of this application. Figure 3 This is a SEM image disclosed in the embodiments of this application, used to illustrate the specific morphology of the first region; Figure 4 This is a SEM image disclosed in the embodiments of this application, used to illustrate the first sub-region, the second sub-region, and the third sub-region set around the texture region in the texture region; Figure 5 This is a SEM image disclosed in an embodiment of this application, used to illustrate the morphology of the clustered structure in the first sub-region; Figure 6 This is a SEM image used to illustrate the transition region disclosed in the embodiments of this application; Figure 7 This is a SEM image disclosed in an embodiment of the present application, used to illustrate the pyramid-shaped protrusion at the boundary between the transition region and the first sub-region; Figure 8 This is a schematic diagram of a silicon substrate having a dielectric layer, a first doped semiconductor layer, and a mask layer disposed on its surface, as disclosed in an embodiment of this application. Figure 9 This is a schematic diagram of the structure of the laser-treated area and the untreated area formed after laser patterning film opening process, as disclosed in the embodiments of this application. Figure 10 This is a schematic diagram of the structure after the texturing process disclosed in the embodiments of this application; Figure 11 This is a schematic diagram of the structure after removing the mask layer, as disclosed in the embodiments of this application; Figure 12 This is a SEM image disclosed in the embodiments of this application, used to illustrate the surface morphology of the mask layer after laser patterning film opening process; Figure 13 This is an example of an embodiment disclosed in this application for illustration. Figure 12 SEM image of the cross-sectional morphology corresponding to point ①; Figure 14 This is an example of an embodiment disclosed in this application for illustration. Figure 12SEM image of the cross-sectional morphology corresponding to point ② in the middle.

[0023] Icons: 1. Silicon substrate; 11. First region; 111. Textured region; 1111. First sub-region; 1112. Second sub-region; 112. Third sub-region; 12. Second region; 121. Sloping structure; 1a. Textured structure; 1a1. Pyramid-like protrusion; 1aa. Clustered structure; 1aa1. Middle pyramid-like protrusion; 1aa2. Edge pyramid-like protrusion; 1b. Flat structure; 13. Transition region; 2. Dielectric layer; 3. First doped semiconductor layer; 31. Mask layer; 32. Laser-treated region; 33. Untreated region; 4. Backlight passivation layer; 41. Backlight alumina layer; 42. Backlight silicon nitride layer; 5. First electrode; 6. Second doped semiconductor layer; 7. Light-receiving passivation layer; 71. Light-receiving alumina layer; 72. Light-receiving silicon nitride layer; 8. Second electrode. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0026] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0027] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0028] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0029] The technical solution of this application will be further described below with reference to the embodiments and accompanying drawings.

[0030] In a first aspect, embodiments of this application provide a solar cell.

[0031] Reference Figure 1 A solar cell includes a silicon substrate 1, the surface structure of the back surface of the silicon substrate 1 can be referred to as follows. Figures 2 to 5 .like Figure 2 As shown, the backlight surface of the silicon substrate 1 includes a first region 11 and a second region 12 with different surface structures; Figure 3 To further magnify the SEM image of the morphology of the first region 11, Figure 4 This is an SEM image used to illustrate the texture region 111 in the first region 11 (where dashed lines indicate the outlines of the first sub-region 1111 and the second sub-region 1112 within the texture region 111). From Figure 3 It can be seen that the first region 11 has a velvety structure 1a, and the second region 12 has a smooth structure 1b, and simultaneously... Figure 4 As shown, the velvet structure 1a of the first region 11 includes multiple pyramid-shaped protrusions 1a1. The first region 11 includes a textured region 111, from... Figure 4 As can be seen, the texture region 111 includes a first sub-region 1111 located in the middle and a second sub-region 1112 surrounding the first sub-region 1111. Figure 5 For the SEM image used to illustrate the first sub-region 1111 in the texture region 111 (where the dashed lines indicate the outline of the clustered structure 1aa), from Figure 5 It can be seen that the first sub-region 1111 contains several cluster-like structures 1aa, and the morphology of the cluster-like structures 1aa is as follows: Figure 5As shown within the black dashed box, the cluster-like structure 1aa is formed by multiple pyramid-like protrusions 1a1. The cluster-like structure 1aa includes a central pyramid-like protrusion 1aa1 and peripheral pyramid-like protrusions 1aa2 surrounding the central pyramid-like protrusion 1aa1. The tops of some of the peripheral pyramid-like protrusions 1aa2 are offset towards the central pyramid-like protrusion 1aa1 relative to the geometric center of the bottom of the peripheral pyramid-like protrusions 1aa2.

[0032] This application effectively improves the light absorption and utilization rate of solar cells by setting a textured region 111 formed by the combination of a first sub-region 1111 and a second sub-region 1112, while also improving the quality of subsequently deposited functional films. Specifically, from Figure 5 Looking at the geometry of the clustered structure 1aa shown, the tops of some of the edge pyramid-shaped protrusions 1aa2 are offset relative to the geometric center of their bottoms towards the top of the central pyramid-shaped protrusion 1aa1, causing these edge pyramid-shaped protrusions 1aa2 to tilt towards the central pyramid-shaped protrusion 1aa1 as a whole. This offset design geometrically results in a smoother contour on the surface of the edge pyramid-shaped protrusions 1aa2, thereby improving the overall surface smoothness of the first sub-region 1111.

[0033] This smooth morphology provides a more uniform and better-adhesive growth substrate for the deposition of functional films, which is conducive to the formation of high-quality films with uniform thickness and dense structure. This significantly improves the surface passivation effect of the first sub-region 1111 and reduces carrier recombination. Furthermore, during the photovoltaic module encapsulation process, the smooth morphology of the first sub-region 1111 can also reduce the flow resistance of the encapsulating film (such as EVA or POE) during the lamination process, allowing the encapsulating film to fill the gaps in the backlight surface more fully and uniformly. This effectively avoids the encapsulating film filling voids or poor interface contact problems that may occur due to the overly steep structure and excessive aspect ratio of the textured structure 1a, thereby improving the reliability of the encapsulation and the long-term stability of the module.

[0034] Furthermore, this application also retains a second region 12 with a flat structure 1b on the back surface. This second region 12 provides an excellent substrate for subsequent deposition of functional films, which is beneficial for forming high-quality functional films and thus significantly reduces the carrier surface recombination rate. Through the cooperation of the first region 11 and the second region 12, the light absorption effect and surface passivation effect of the silicon substrate 1 on the back surface can be synergistically enhanced, ultimately achieving a further improvement in the photoelectric conversion efficiency of the solar cell.

[0035] It should be noted that, in this application, the pyramid-shaped protrusion 1a1 refers to a protrusion structure with a pyramid-shaped morphology, meaning that the three-dimensional morphology of the protrusion is geometrically similar to a square pyramid, a square frustum, or other similar geometric structures with inclined sidewalls.

[0036] The second region 12 of this application has a flat structure 1b that is flatter than the textured structure 1a. That is, the surface flatness of the second region 12 is higher, and it does not have the pyramid-shaped protrusions 1a1 exhibited by the first region 11. The surface undulation of the second region 12 is significantly reduced, and the roughness is lower. The flat structure 1b can be obtained by treating the surface of the silicon substrate 1 on which the textured structure 1a has been formed through chemical polishing, mechanical polishing, or other planarization processes to improve the surface flatness of the second region 12.

[0037] Reference Figure 5 In some embodiments, within the clustered structure 1aa, the overlap of the edge pyramidal protrusions 1aa2 is greater than that of the intermediate pyramidal protrusions 1aa1. Within the clustered structure 1aa, the edge pyramidal protrusions 1a1 are more prone to fusion during growth, resulting in edge pyramidal protrusions 1aa2 with a higher degree of overlap and smoother surface undulations. Consequently, the surface passivation performance of the first sub-region 1111 is improved.

[0038] Refer to the return Figure 4 The second sub-region 1112 contains clustered structures 1aa, while the density of these clustered structures 1aa in the first sub-region 1111 is greater than that in the second sub-region 1112. The pyramid-shaped protrusions in the second sub-region 1112 are more uniformly distributed, but the number and density of the clustered structures 1aa are smaller. The clustered structures 1aa in the first sub-region 1111 are more concentrated. By controlling the distribution of clustered structures 1aa in the first and second sub-regions 1112, the morphology of the first region 11 can be better controlled, leading to a simultaneous improvement in the light absorption capacity and surface passivation performance of the first region 11.

[0039] Refer to the return Figure 3 In some embodiments, the textured regions 111 are periodically spaced and distributed within the first region 11. This arrangement of the textured regions 111 not only enhances the absorption and light trapping effect of the solar cell backlight surface on incident light, but also improves the uniformity and adhesion of the subsequently deposited functional film layers, thereby further enhancing the electrical performance of the solar cell.

[0040] Reference Figure 4In some embodiments, the first region 11 further includes a third sub-region 112 in addition to the texture region 111, and the third sub-region 112 has several clustered structures 1aa distributed near the edge of the second sub-region 1112.

[0041] The clustered structure 1aa of this application is formed not only in the first sub-region 1111, but also in the third sub-region 112 near the edge of the second sub-region 1112. This helps to improve the smoothness of the surface morphology at the edge of the third sub-region 112, and is beneficial to improving the adhesion and uniformity of the subsequent functional film layer in the third sub-region 112. At the same time, the clustered structure 1aa in the third sub-region 112, together with the clustered structure 1aa in the first sub-region 1111, can synergistically improve the deposition quality of the subsequent functional film layer, thereby enhancing the surface passivation performance of the entire first region 11.

[0042] In some embodiments, the textured region 111 accounts for 10% to 60% of the area of ​​the first region 11.

[0043] When the area ratio of the textured region 111 to the area ratio of the first region 11 is between 10% and 60%, the optical performance and surface passivation effect of the solar cell can be better optimized synergistically. When the area ratio of the textured region 111 to the area ratio of the first region 11 is too high, the laser damage caused by the laser patterning film-opening process that forms the textured region 111 increases, leading to an increase in defects in the silicon substrate 1. When the area ratio of the textured region 111 to the area ratio of the first region 11 is too low, the distribution of clustered structures 1aa in the first region 11 is too small, limiting the further improvement of the surface passivation performance of the first region 11.

[0044] It should be noted that the area ratio of texture region 111 to the area of ​​first region 11 can be calculated by scanning and measuring the areas of texture region 111 and first region 11 within the test area using a Zeta 3D scanning microscope. For example, using... Figure 4 The area shown is the test range. The texture area 111, indicated by the dashed line, has an irregular shape. The area of ​​this irregular shape is measured by scanning. Figure 4 The proportion of the displayed area is the area ratio of the texture region 111 to the first region 11. Furthermore, to reduce measurement errors, the arithmetic mean of multiple measurements can be taken as the area ratio of the texture region 111 to the first region 11.

[0045] Reference Figure 6 In some embodiments, there is a transition region 13 between the first region 11 and the second region 12. The transition region 13 includes a velvet structure 1a and a flat structure 1b. The density of the pyramid-shaped protrusions 1a1 near the first region 11 in the transition region 13 is greater than the density of the pyramid-shaped protrusions 1a1 near the second region 12 in the transition region 13.

[0046] The transition region 13 simultaneously includes a textured structure 1a with pyramid-shaped protrusions 1a1 and a flat structure 1b without pyramid-shaped protrusions 1a1, achieving a smooth transition in morphology and performance from the textured structure 1a to the flat structure 1b. The textured structure 1a within the transition region 13 maintains its ability to scatter incident light, which is beneficial for improving light absorption; while the simultaneously present flat structure 1b improves interface quality and passivation effect. By gradually decreasing the density of the pyramid-shaped protrusions 1a1 along the direction from the first region 11 to the second region 12, this arrangement avoids interface defects and recombination losses easily caused by abrupt changes in morphology, further enhancing the optical and electrical performance of the solar cell.

[0047] Reference Figure 7 In some embodiments, the average base size of the pyramid-shaped protrusions 1a1 in the transition region 13 is greater than the average base size of the pyramid-shaped protrusions 1a1 in the first region 11 near the transition region 13.

[0048] The pyramid-shaped protrusions 1a1 in the transition region 13 are designed with increasing base size from near the first region 11 to away from the first region 11. This design allows for better structural connection with the pyramid-shaped protrusions 1a1 in the first region 11, reducing the degradation of functional film deposition quality caused by structural abrupt changes, thereby improving the passivation effect of the transition region 13.

[0049] It should be noted that the average base size is used to quantify the width of the base of the pyramid-shaped protrusion 1a1. When measuring the average base size, the outline of the protrusion's base can be observed from a top-down perspective. The two points furthest apart within this outline can be identified, and a line segment can be drawn with these two points as endpoints within the outline. The length of this line segment can then be measured. To reduce measurement error, 3-5 pyramid-shaped protrusions 1a1 can be measured during the measurement process, and the arithmetic mean can be calculated.

[0050] In some embodiments, the second region 12 has a ramp structure 121 near the edge of the transition region 13. The width of the transition region 13 is 10 μm to 30 μm, measured from the boundary between the ramp structure 121 and the transition region 13. In the transition region 13, the area of ​​the velvet structure 1a accounts for 40% to 80%.

[0051] By controlling the area ratio of the velvet structure 1a in the transition region 13 to 40%~80%, it is beneficial to better balance the light absorption effect and passivation effect of the transition region 13.

[0052] It should be noted that, as Figure 6As shown, in the structure of this application, the size distribution of the pyramid-shaped protrusions 1a1 in the first region 11 is relatively uniform. However, the size of the pyramid-shaped protrusions 1a1 on the side adjacent to the first region 11 in the transition region 13 is significantly larger than that in the first region 11, thus forming a significant size gradient at the boundary between the transition region 13 and the first region 11. Based on this size gradient characteristic, the boundary between the transition region 13 and the first region 11 is defined as the starting point where the size of the pyramid-shaped protrusions 1a1 begins to increase. Since the pyramid-shaped protrusions 1a1 are not arranged in a straight line, this boundary line actually presents a tortuous distribution. The boundary feature between the transition region 13 and the slope structure 121 of the second region 12 in this application is clear. When measuring the width of the transition region 13, the boundary between the transition region 13 and the slope structure 121 of the second region 12 is first fitted along the extension direction of the boundary to obtain the dashed line A, which is used as the test boundary of the transition region 13 near the second region 12. Next, draw a dashed line B parallel to dashed line A, passing through any point on the aforementioned convoluted boundary line. Use dashed line B as the test boundary of transition region 13, which is close to the first region 11. The distance between dashed line A and dashed line B is the width of transition region 13.

[0053] When testing the area ratio of the velvet structure 1a relative to the transition region 13, the position between the dashed line A and the dashed line B is selected as the two sides of the test area. By measuring the area of ​​the velvet structure 1a and the transition region 13 within this test area, the area ratio of the velvet structure 1a in the transition region 13 is obtained.

[0054] Refer to the return Figure 1 In some embodiments, the first region 11 and the second region 12 are alternately arranged; Solar cells also include: Dielectric layer 2 and first doped semiconductor layer 3 are stacked sequentially on the second region 12; The backlight passivation layer 4 covers the first region 11 and the surface of the first doped semiconductor layer 3 away from the silicon substrate 1. The first electrode 5 passes through the backlight passivation layer 4 and forms an ohmic contact with the first doped semiconductor layer 3. The second doped semiconductor layer 6 is disposed on the light-receiving side of the silicon substrate 1; The light-receiving passivation layer 7 is located on the side of the second doped semiconductor layer 6 away from the silicon substrate 1. The second electrode 8 passes through the passivation layer 7 of the light-receiving surface and forms an ohmic contact with the second doped semiconductor layer 6.

[0055] On the backlight side, by placing the dielectric layer 2 and the first doped semiconductor layer 3 in the second region 12, it is beneficial to obtain dielectric layer 2 and the first doped semiconductor layer 3 with better deposition quality. This allows the dielectric layer 2 and the first doped semiconductor layer 3 to form better contact with the first electrode 5, which is conducive to carrier transport and reduces the interface contact resistivity. At the same time, covering the first region 11 with the backlight passivation layer 4 can leverage the light absorption function of the first region 11 while also improving the deposition quality of the backlight passivation layer 4. This partitioned arrangement can better improve the photoelectric conversion efficiency of the solar cell.

[0056] Furthermore, the material of the dielectric layer 2 may include at least one of various dielectric materials, such as silicon oxide, magnesium fluoride, amorphous silicon, polycrystalline silicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide, or titanium oxide. Specifically, the dielectric layer 2 may be composed of a silicon oxide layer containing silicon oxide. To better provide interface passivation for the silicon substrate 1, the thickness of the dielectric layer 2 may be 0.1 nm to 5 nm. For example, the thickness of the dielectric layer 2 may be 0.1 nm, 0.5 nm, 1 nm, 1.5 nm, 2 nm, 3 nm, or 4 nm, etc. However, this application is not limited to these values, and the thickness of the dielectric layer 2 may have various values.

[0057] The first doped semiconductor layer 3 can be a doped polycrystalline silicon layer, a doped amorphous silicon layer, or a doped microcrystalline silicon layer, etc. The thickness of the first doped semiconductor layer 3 is 75 nm to 125 nm. For example, the thickness of the first doped semiconductor layer 3 is 75 nm, 85 nm, 95 nm, 105 nm, 115 nm, or 125 nm. The second doped semiconductor layer 6 can be a boron emitter layer or a phosphorus emitter layer, etc., diffused from the surface of the silicon substrate 1 into the bulk. One of the second doped semiconductor layer 6 and the silicon substrate 1 has an N-type conductivity, and the other has a P-type conductivity. For example, when the silicon substrate 1 is an N-type silicon wafer, the second doped semiconductor layer 6 is a P-type emitter layer (such as a boron emitter layer); when the silicon substrate 1 is a P-type silicon wafer, the second doped semiconductor layer 6 is an N-type emitter layer (such as a phosphorus emitter layer).

[0058] The materials of the backlight passivation layer 4 and the light-receiving passivation layer 7 can be at least one of aluminum oxide, silicon oxide, silicon nitride, or silicon oxynitride. For example, as... Figure 1 As shown, the backlight passivation layer 4 can be a stack of a backlight aluminum oxide layer 41 and a backlight silicon nitride layer 42 that sequentially cover the surface of the first region 11 and the side of the first doped semiconductor layer 3 away from the silicon substrate 1. The light-receiving passivation layer 7 can be a stack of a light-receiving aluminum oxide layer 71 and a light-receiving silicon nitride layer 72 that cover the second doped semiconductor layer 6.

[0059] The materials for the first electrode 5 and the second electrode 8 can be silver, copper, or nickel, etc.

[0060] Secondly, embodiments of this application provide a method for preparing a solar cell.

[0061] A method for fabricating a solar cell, referring to... Figures 8-11 This includes the following steps: Provide such as Figure 8 The silicon substrate 1 shown has a flat structure 1b on its back surface, and a dielectric layer 2, a first doped semiconductor layer 3 and a mask layer 31 are stacked sequentially on the back surface of the silicon substrate 1. A portion of the mask layer 31 is subjected to laser patterning and opening process to form a shape such as Figure 9 The laser-treated region 32 and the untreated region 33 are shown. In the laser-treated region 32, the mask layer 31 is partially removed. Remove the remaining mask layer 31 in the laser-treated region 32, as well as the first doped semiconductor layer 3 and dielectric layer located below the laser-treated region 32; A first region 11 with a textured structure 1a is formed on the surface of a silicon substrate 1; in the untreated region 33, a mask layer 31, a first doped semiconductor layer 3, and a dielectric layer 2 are retained, and the surface of the silicon substrate 1 forms a second region 12 with a flat structure 1b, resulting in the following: Figure 10 The structure shown; After removing the mask layer 31, the following is obtained: Figure 11 The structure shown; Among them, see references Figure 4 As shown, the first region 11 includes a texture region 111, which includes a first sub-region 1111 located in the center and a second sub-region 1112 surrounding the first sub-region 1111. The first sub-region 1111 is distributed as follows: Figure 5 The diagram shows several cluster-like structures 1aa, each cluster-like structure 1aa being formed by a plurality of pyramid-like protrusions 1a1. Each cluster-like structure 1aa includes a central pyramid-like protrusion 1aa1 and peripheral pyramid-like protrusions 1aa2 surrounding the central pyramid-like protrusion 1aa1. The top of the peripheral pyramid-like protrusions 1aa2 is offset toward the central pyramid-like protrusion 1aa1 relative to the geometric center of the bottom of the peripheral pyramid-like protrusions 1aa2.

[0062] This application has discovered that after removing the remaining mask layer 31 in the laser-treated region 32 and the first doped semiconductor layer 3 and dielectric layer 2 located below the laser-treated region 32, directly performing texturing can form a textured structure 1a with a specific textured region 111 in the first region 11 of the silicon substrate 1 based on the difference in laser spot energy distribution.

[0063] Specifically, the energy of the laser spot typically exhibits a Gaussian distribution, with a strong energy at the center and a weak energy at the edges. This energy gradient results in varying laser intensity in different regions within the laser spot's range, leading to different degrees of modification or damage to the mask layer 31 and the underlying first doped semiconductor layer 3 and dielectric layer 2. For example... Figure 12 The SEM morphology of the surface of the middle mask layer 31 is shown. The damage in the central region of the laser spot (marked as ② in the figure) is more significant, while the damage in the edge region (marked as ① in the figure) is relatively lighter. Figure 13 The cross-sectional morphology at location ① is shown. Figure 14 The cross-sectional morphology at location ② is shown. From Figure 13 and Figure 14 The cross-sectional morphology shown further reveals that the structure of the mask layer 31 and the underlying film in the central region of the laser spot is significantly more damaged. In contrast, in regions with relatively low laser damage, while the structure of the mask layer 31 becomes looser, the degree of damage to the mask layer 31 and the underlying film is lower. After texturing, the central region of the laser spot with higher damage corresponds to the formation of the first sub-region 1111 on the surface of the silicon substrate 1. The first sub-region 1111 tends to generate a cluster-like structure 1aa composed of multiple pyramid-like protrusions 1a1 tightly aggregated, and the surface undulations of the pyramid-like protrusions 1a1 in the cluster-like structure 1aa are smoother. The silicon substrate 1 surface with relatively weaker laser damage compared to the first sub-region 1111 is the second sub-region 1112. The second sub-region 1112 tends to form more uniformly distributed pyramid-like protrusions 1a1, and the density of the cluster-like structure 1aa is significantly reduced. In summary, the first sub-region 1111 of this application is mainly composed of a gently sloping cluster-like structure 1aa, which is beneficial to improving the surface passivation performance of the first region 11. The second sub-region 1112 is mainly composed of relatively uniformly distributed pyramid-shaped protrusions, which is beneficial to ensuring good light absorption effect of the first region 11. The two work together to optimize the photoelectric conversion efficiency of the battery.

[0064] If polishing is performed before texturing, the polishing process can easily weaken the structural damage differences caused by the laser spot to the dielectric layer 2, the first doped semiconductor layer 3, and the silicon substrate 1. If texturing is performed after polishing, it will be difficult to form textured regions 111 in the textured surface structure 1a. Compared with the method of sequentially performing laser patterning, polishing, and texturing, this application performs texturing directly after laser patterning, which can reduce the polishing process steps and improve the bifaciality and surface passivation performance of the solar cell.

[0065] Furthermore, the edge region with lower laser spot damage compared to the second sub-region 1112 corresponds to the third sub-region 112 on the surface of the silicon substrate 1. The third sub-region 112 has numerous clustered structures 1aa near the edge of the second sub-region 1112, while more uniformly distributed pyramid-shaped protrusions 1a1 are formed further away from the second sub-region 1112. The combination of the first sub-region 1111, the second sub-region 1112, and the third sub-region 112 with the aforementioned morphology is more conducive to improving the light absorption capacity and surface passivation performance of the first region 11, thereby further improving the photoelectric conversion efficiency of the battery.

[0066] In some embodiments, during the laser patterning film-opening step, the lateral overlap rate of the laser spot is controlled to be 6% to 8%, and the longitudinal overlap rate is controlled to be 15% to 19%. Within this overlap rate range, it is beneficial to ensure that the spot action area is continuous and uniform, thereby ensuring that the mask layer 31 above the first region 11 is fully and coherently removed, laying the foundation for the subsequent texturing process.

[0067] The arrangement and shape of the laser spot directly affect the arrangement and shape of the textured region 111 ultimately formed in the first region 11. For example, when a square laser spot is used and periodically scanned and arranged according to the aforementioned overlap rate along a specific direction, a textured region 111 is formed accordingly in the first region 11. Figure 3 As shown, a textured region 111 has a shape resembling a small fish, and the periodic arrangement of this textured region 111 is consistent with the laser scanning arrangement. In addition to forming the textured region 111, a third sub-region 112 is also formed in the first region 11. Specifically, the first sub-region 1111 in the textured region 111 corresponds to the central region of the laser spot, the second sub-region 1112 in the textured region 111 corresponds to the secondary central region surrounding the central region of the laser spot, and the third sub-region 112 corresponds to the edge region surrounding the secondary central region of the laser spot.

[0068] In other embodiments, the laser spot may also be circular or other shapes, and the textured region 111 may also be circular, square, island-shaped, star-shaped or honeycomb-shaped, etc. This application does not specifically limit the shape of the laser spot and the textured region 111.

[0069] Furthermore, the mask layer 31 can be a silicon oxide mask layer 31 or a doped silicon oxide mask layer 31. The dopant atoms in the doped silicon oxide mask layer 31 are the same as the dopant atoms in the first doped semiconductor layer 3. For example, when the dopant atoms in the first doped semiconductor layer 3 are phosphorus atoms, the dopant atoms in the doped silicon oxide mask layer 31 will also be phosphorus atoms.

[0070] Preferably, the thickness of the mask layer 31 can be 10 nm to 35 nm. This thickness of mask layer 31 effectively protects the underlying first doped semiconductor layer 3, reducing the risk of contamination or damage from the external environment. Furthermore, this thickness of mask layer 31 can form a clearly defined laser-treated region 32 under laser irradiation, while avoiding excessive laser energy dissipation or severe thermal damage to the underlying structure due to an excessively thick film layer. This lays the foundation for the final formation of a textured region 111 in the first region 11 of the silicon substrate 1 in this application.

[0071] In some embodiments, the texturing process may employ a texturing solution comprising an inorganic alkali and a texturing additive. The inorganic alkali may be sodium hydroxide or potassium hydroxide, and the texturing additive may be any one or a combination of lignin, cellulose, and polysaccharides.

[0072] In some embodiments, after the texturing process, the recess depth of the surface of the first region 11 relative to the second region 12 is 1 μm to 2 μm.

[0073] By texturing the silicon substrate 1 so that the surface of the first region 11 is recessed to a depth of 1 μm to 2 μm relative to the second region 12, the structural damage caused by the laser patterning process to the silicon substrate 1 can be effectively removed, thereby reducing the defect state density of the silicon substrate 1, reducing carrier recombination, and further improving the performance of the solar cell. For example, the recess depth of the first region 11 relative to the second region 12 can be 1 μm, 1.5 μm, or 2 μm.

[0074] It should be noted that the recessed depth of the surface of the first region 11 relative to the second region 12 is the height from the top of the velvet structure 1a of the first region 11 to the surface of the second region 12.

[0075] In some embodiments, in the step of removing the remaining mask layer 31 in the laser-treated region 32 and the first doped semiconductor layer 3 and dielectric layer 2 located below the laser-treated region 32, alkaline etching is performed using an inorganic alkaline solution. Further, the inorganic alkaline solution used for alkaline etching includes sodium hydroxide solution and potassium hydroxide solution, with a volume fraction of 15% to 20%, an alkaline etching temperature of 82°C to 85°C, and an alkaline etching time of 8 min to 10 min.

[0076] In some embodiments, the step of preparing the first region 11 with the textured structure 1a involves texturing and etching using a texturing alkaline solution. Further, the texturing alkaline solution used for texturing and etching comprises an inorganic alkali and a texturing additive; the volume fraction of the inorganic alkali in the texturing alkaline solution is 15%–20%, the volume fraction of the texturing additive is 0.7%–0.9%, the texturing etching temperature is 75°C–80°C, and the texturing etching time is 7 min–9 min.

[0077] In this application, the alkaline etching and texturing etching of the back surface of the silicon substrate 1 do not use polishing additives, so as to avoid weakening the structural damage difference caused by the laser spot to the dielectric layer 2, the first doped semiconductor layer 3 and the silicon substrate 1, which is not conducive to the formation of the cluster structure 1aa.

[0078] Thirdly, embodiments of this application provide a photovoltaic module.

[0079] A photovoltaic module includes a solar cell as described in the first aspect, or a solar cell prepared by the method described in the second aspect.

[0080] The technical solution of this application will be further described below with reference to more specific embodiments.

[0081] Example 1 This application provides a solar cell, the preparation method of which includes the following steps: Provide N-type monocrystalline silicon wafers with a textured surface; Boron diffusion treatment: BCl3 is introduced as a boron source, and the temperature of the high-temperature diffusion furnace tube of the boron source is controlled at 850℃-1020℃. The N-type single crystal silicon wafer is placed in it for diffusion, and a B-doped P-type emitter layer and a borosilicate glass (BSG) layer stacked on the P-type emitter layer are formed on the light-receiving surface of the N-type single crystal silicon wafer. First removal of the wrap-around plating: Use an HF solution with a mass concentration of 8% to remove the BSG layer wrapped around the backlight; Alkaline polishing: The N-type monocrystalline silicon wafer after de-coating is polished using a polishing solution containing 2% sodium hydroxide and 0.8% polishing additive (the polishing additive in this embodiment is hydroxyethylidene diphosphate) to form a flat structure on the back surface of the N-type monocrystalline silicon wafer. Preparation of silicon oxide dielectric layer and phosphorus-doped polycrystalline silicon layer: The alkaline-polished N-type single crystal silicon wafer is placed in a PECVD device, and a 1 nm~2 nm silicon oxide dielectric layer, a 75 nm~125 nm phosphorus-doped amorphous silicon layer, and a 10 nm~35 nm silicon oxide mask layer are deposited sequentially on the back surface of the N-type single crystal silicon wafer. Annealing treatment at 850℃~950℃ transforms the phosphorus-doped amorphous silicon layer into a phosphorus-doped polycrystalline silicon layer and the silicon oxide mask layer into a doped silicon oxide mask layer. A portion of the mask layer is patterned using laser technology to create laser-processed and non-laser-processed areas. After laser patterning, the mask layer in the laser-processed areas is partially removed. Second removal of the silicon oxide mask layer: Use an HF solution with a mass concentration of 8% to remove the doped silicon oxide mask layer that was coated around the light-receiving surface; A 2% sodium hydroxide solution was used to etch the laser-treated area to a depth of 3 μm to 8 μm, thereby removing the remaining doped silicon oxide mask layer in the laser-treated area, as well as the phosphorus-doped polycrystalline silicon layer, silicon oxide dielectric layer, and part of the N-type single-crystal silicon wafer located below the laser-treated area. A texturing alkaline solution consisting of a 2% sodium hydroxide solution and a 0.8% texturing additive (lignin in this embodiment) was used to texture and etch the back surface of an N-type monocrystalline silicon wafer. The texturing and etching temperature was controlled at 75°C to 80°C, and the texturing and etching reaction time was 7 to 9 minutes. The first region with a textured structure is formed on the back surface of an N-type single-crystal silicon wafer below the laser-treated area; in the untreated area, a doped silicon oxide mask layer, a phosphorus-doped polycrystalline silicon layer, and a silicon oxide dielectric layer are retained, and the surface of the N-type single-crystal silicon wafer is a second region with a flat structure, and the first region is recessed relative to the second region; wherein, the first region includes a textured region, the textured region includes a first sub-region located in the middle and a second sub-region set around the first sub-region, the first sub-region is distributed with several cluster-like structures, the cluster-like structures are formed by multiple pyramid-like protrusions, the cluster-like structures include a central pyramid-like protrusion and an edge pyramid-like protrusion set around the central pyramid-like protrusion, the top of the edge pyramid-like protrusion is offset towards the central pyramid-like protrusion relative to the geometric center of the bottom of the edge pyramid-like protrusion; The third step of removing the coating: using an HF solution with a mass concentration of 8%, the remaining doped silicon oxide mask layer on the back side and the BSG layer on the light-receiving side are removed. Deposition of passivation layers on the light-receiving and back-light-receiving sides: Using atomic layer deposition (ALD), a 3 nm–7 nm light-receiving aluminum oxide layer and a 3 nm–7 nm back-light-receiving aluminum oxide layer are deposited on an N-type monocrystalline silicon wafer. The light-receiving aluminum oxide layer covers the P-type emitter layer, and the back-light-receiving aluminum oxide layer covers the first region and the surface of the phosphorus-doped polycrystalline silicon layer away from the N-type monocrystalline silicon wafer. Using plasma chemical vapor deposition (PCVDC), a stack of light-receiving silicon nitride, light-receiving silicon oxynitride, and light-receiving silicon oxide layers is deposited on the side of the light-receiving aluminum oxide layer away from the P-type emitter layer. The thicknesses of the light-receiving silicon nitride, light-receiving silicon oxynitride, and light-receiving silicon oxide layers are 50 nm–60 nm, 10 nm–20 nm, and 2 nm–6 nm, respectively. nm; Using a plasma chemical vapor deposition (PCVDC) device, a stack of backlight silicon nitride, backlight silicon oxynitride, and backlight silicon oxide layers is deposited on the side of the backlight alumina layer away from the N-type single crystal silicon wafer. The thicknesses of the backlight silicon nitride layer, backlight silicon oxynitride layer, and backlight silicon oxide layer are 90 nm~100 nm, 30 nm~40 nm, and 5 nm~10 nm, respectively. A first electrode is prepared, which is a silver electrode, and an ohmic contact is formed between the first electrode and the phosphorus-doped polycrystalline silicon layer through the passivation layer of the backlight surface. A second electrode, which is a silver electrode, is prepared so that it passes through the passivation layer of the light-receiving surface and forms an ohmic contact with the P-type emitter layer.

[0082] Comparative Example 1 This application provides a solar cell in a comparative example, which differs from Example 1 in that: the textured surface structure formed in the first region does not contain a cluster structure. Specifically, this application also performs a polishing process, including: using a polishing solution with a mass concentration of 2% sodium hydroxide and a mass concentration of 0.8% polishing additive (the polishing additive in the comparative example of this application is hydroxyethylidene diphosphate), controlling the polishing reaction temperature to be 75°C~80°C, and the polishing reaction time to be 7 min~9 min, removing the remaining mask layer in the laser-treated region, as well as the silicon oxide dielectric layer, phosphorus-doped polycrystalline silicon layer, and part of the N-type monocrystalline silicon wafer located in the laser-treated region; Next, a texturing solution with a mass concentration of 2% sodium hydroxide and a mass concentration of 0.8% lignin (the texturing additive in the comparative example of this application is lignin) was used to texture the back surface of the N-type monocrystalline silicon wafer. The temperature of the texturing reaction was controlled at 75℃~80℃ and the texturing reaction time was 7 min~9 min. Everything else remains the same as in Example 1.

[0083] Solar cell performance testing The performance of solar cells was tested using an IV tester under standard test conditions: AM1.5, 1000 W / m. 2The test environment temperature was 25℃. Before the test, the simulated sunlight intensity was calibrated using a standard silicon solar cell. The differences in open-circuit voltage (Voc), short-circuit current (Jsc), fill factor (FF), photoelectric conversion efficiency (PCE), and bifaciality of the corresponding solar cells relative to their corresponding control groups were recorded. Here, photoelectric conversion efficiency refers to the test result of the photoelectric conversion efficiency of the solar cell's light-receiving side, and bifaciality refers to the ratio of the efficiency of the back-lighting side to the efficiency of the light-receiving side.

[0084] Table 1

[0085] A comparison of the data in Table 1 between Example 1 and Comparative Example 1 shows that the photoelectric conversion efficiency, open-circuit voltage, short-circuit current, fill factor, and bifaciality of the solar cell in Example 1 are improved compared to the solar cell in Comparative Example 1. This proves that by setting a textured region in the first region of the backlight surface of the silicon substrate, the light absorption of the backlight surface can be effectively improved, while the surface passivation performance of the first region is enhanced, ultimately achieving a further improvement in the electrical performance of the solar cell.

[0086] The technical solutions disclosed in the embodiments of this application have been described in detail above. Specific examples have been used in this article to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core inventive points of the embodiments of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A solar cell, characterized by, The device includes a silicon substrate, wherein the backlight surface of the silicon substrate includes a first region and a second region with different surface structures, the first region having a textured structure and the textured structure including multiple pyramid-shaped protrusions, and the second region having a flatter structure that is relatively flatter than the textured structure. The first region includes a textured region, which includes a first sub-region located in the middle and a second sub-region surrounding the first sub-region. The first sub-region has a plurality of clustered structures, which are formed by the aggregation of multiple pyramid-shaped protrusions. The clustered structures include a central pyramid-shaped protrusion and edge pyramid-shaped protrusions surrounding the central pyramid-shaped protrusion. The tops of some of the edge pyramid-shaped protrusions are offset towards the central pyramid-shaped protrusion relative to the geometric center of the bottom of the edge pyramid-shaped protrusion.

2. The solar cell according to claim 1, characterized in that, In the clustered structure, the overlap of the edge pyramid-shaped protrusions is greater than that of the intermediate pyramid-shaped protrusions; And / or, the second sub-region has the clustered structure, and the density of the clustered structure in the first sub-region is greater than the density of the clustered structure in the second sub-region.

3. The solar cell according to claim 1, characterized in that, The texture regions are periodically spaced and distributed within the first region.

4. The solar cell according to claim 1, characterized in that, The first region also includes a third sub-region in addition to the textured region, and the third sub-region has a plurality of the clustered structures distributed near the edge of the second sub-region.

5. The solar cell according to claim 1, characterized in that, The textured region accounts for 10% to 60% of the area of ​​the first region.

6. The solar cell according to claim 1, characterized in that, There is a transition region between the first region and the second region. The transition region includes the velvet structure and the flat structure. The density of the pyramid-shaped protrusions near the first region in the transition region is greater than the density of the pyramid-shaped protrusions near the second region in the transition region.

7. The solar cell according to claim 6, characterized in that The average base size of the pyramid-like protrusions in the transition region is greater than the average base size of the pyramid-like protrusions in the first region near the transition region.

8. The solar cell according to claim 6, characterized in that, The second region has a sloping structure near the edge of the transition region, and the width of the transition region is 10 μm to 30 μm, measured from the boundary between the sloping structure and the transition region. In the transition region, the area of ​​the velvet structure accounts for 40% to 80%.

9. The solar cell according to any one of claims 1 to 8, characterized in that, The first region and the second region are set alternately; The solar cell also includes: A dielectric layer and a first doped semiconductor layer are sequentially stacked on the second region; A backlight passivation layer, the backlight passivation layer covering the first region and the surface of the first doped semiconductor layer away from the silicon substrate; The first electrode passes through the backlight passivation layer and forms an ohmic contact with the first doped semiconductor layer; A second doped semiconductor layer is disposed on the light-receiving side of the silicon substrate; A light-receiving passivation layer is located on the side of the second doped semiconductor layer away from the silicon substrate; The second electrode passes through the passivation layer of the light-receiving surface and forms an ohmic contact with the second doped semiconductor layer.

10. A method of producing a solar cell, characterized by, Includes the following steps: A silicon substrate is provided, wherein the back surface of the silicon substrate has a flat structure, and a dielectric layer, a first doped semiconductor layer and a mask layer are sequentially stacked on the back surface of the silicon substrate. A portion of the mask layer is subjected to laser patterning and opening to form a laser-treated area and an untreated area, wherein the mask layer is partially removed in the laser-treated area. Remove the remaining mask layer in the laser-treated area, as well as the first doped semiconductor layer and the dielectric layer located below the laser-treated area; A first region with a textured surface is prepared on the surface of the silicon substrate; In the untreated area, the mask layer, the first doped semiconductor layer, and the dielectric layer are retained, and the silicon substrate surface is a second region that maintains the flat structure. Remove the mask layer; The first region includes a textured region, which includes a first sub-region located in the middle and a second sub-region surrounding the first sub-region. The first sub-region has several clustered structures, which are formed by the aggregation of multiple pyramid-shaped protrusions. The clustered structures include a central pyramid-shaped protrusion and edge pyramid-shaped protrusions surrounding the central pyramid-shaped protrusion. The top of the edge pyramid-shaped protrusions is offset towards the central pyramid-shaped protrusion relative to the geometric center of the bottom of the edge pyramid-shaped protrusions.

11. The method of producing a solar cell according to claim 10, wherein The depth of the recess of the first region relative to the second region is 1 μm to 2 μm; And / or, In the laser patterning film-opening step, the lateral overlap rate of the laser spot is controlled to be 6%~8%, and the longitudinal overlap rate is controlled to be 15%~19%. In the step of removing the remaining mask layer in the laser-treated area and the first doped semiconductor layer and the dielectric layer located below the laser-treated area, alkaline etching is performed using an inorganic alkaline solution. The inorganic alkaline solution used for alkaline etching includes sodium hydroxide solution and potassium hydroxide solution. The volume fraction of the inorganic alkaline solution is 15%~20%. The alkaline etching temperature is 82℃~85℃. The alkaline etching time is 8 min~10 min. And / or, The step of preparing the first region having the textured surface structure involves texturing and etching using a texturing alkaline solution. The texturing alkaline solution used for texturing and etching includes the inorganic alkali and a texturing additive. In the texturing alkaline solution, the volume fraction of the inorganic alkali is 15%~20%, the volume fraction of the texturing additive is 0.7%~0.9%, the texturing etching temperature is 75℃~80℃, and the texturing etching time is 7 min~9 min.

12. A photovoltaic module, characterized by Includes the solar cell as described in any one of claims 1-9, or the solar cell prepared by the method described in any one of claims 10-11.

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