Solar cells, sliced cells, stacked cells, and photovoltaic modules

Abstract

This application relates to solar cells, sliced ​​solar cells, tandem solar cells, and photovoltaic modules. The solar cell includes: a substrate having a first surface and a second surface disposed opposite each other in the thickness direction; a groove structure formed on the first surface, the groove structure including a bottom surface recessed inward relative to the first surface, a side surface extending from the first surface toward the bottom surface in the thickness direction, and an inclined surface extending obliquely from one end of the side surface away from the first surface and connected to the bottom surface, the side surface being perpendicular to the bottom surface, the angle between the inclined surface and the bottom surface being 32° to 48°, and the ratio of the height of the side surface to the height of the inclined surface in the thickness direction being 2:1 to 11:1; and a textured region formed on the first surface, the textured region including a first protrusion located at the edge of the groove structure, the first protrusion being a truncated pyramid. This application can improve photoelectric conversion efficiency.

Description

Technical Field

[0001] This application relates to the field of solar cells, and in particular to a solar cell, a sliced ​​cell, a tandem cell, and a photovoltaic module. Background Technology

[0002] Solar cells, as a clean and renewable energy technology, are increasingly becoming an important component of the energy system. Essentially, a solar cell is a semiconductor device that directly converts solar energy into electrical energy. Its working principle is based on the photovoltaic effect: when sunlight shines on the cell, photon energy excites electron-hole pairs (i.e., charge carriers) to be generated inside the semiconductor. These charge carriers then separate under the influence of a built-in electric field, forming a potential difference. By effectively extracting these charge carriers through the metal electrodes on the front and back of the cell, direct current can be generated and used by external circuits, thus achieving the efficient conversion and utilization of solar energy into electrical energy.

[0003] In related technologies, it is often necessary to use laser cutting to cut complete solar cells into slices, and then connect multiple slices in series to form a sliced ​​solar cell module, thereby improving the overall output performance of the module. However, in these technologies, carrier recombination in the cutting edge region increases significantly, reducing the photoelectric conversion efficiency of the sliced ​​solar cells. Summary of the Invention

[0004] This application provides a solar cell, a sliced ​​cell, a tandem cell, and a photovoltaic module that can improve photoelectric conversion efficiency.

[0005] In a first aspect, the solar cell provided in the embodiments of this application includes: The substrate has a first surface and a second surface disposed opposite to each other in the thickness direction; A groove structure is formed on the first surface. The groove structure includes a bottom surface recessed inward relative to the first surface, a side surface extending from the first surface toward the bottom surface along the thickness direction, and an inclined surface extending obliquely from the end of the side surface away from the first surface and connecting to the bottom surface. The side surface is perpendicular to the bottom surface, and the angle between the inclined surface and the bottom surface is 32° to 48°. In the thickness direction, the ratio of the height of the side surface to the height of the inclined surface is 2:1 to 11:1. A velvety area is formed on the first surface, the velvety area including a first protrusion located at the edge of the groove structure, the first protrusion being a truncated pyramid.

[0006] In some embodiments, the velvet area further includes a second protrusion, which is a pyramid.

[0007] In some embodiments, the second protrusion is used to reflect light rays having a first incident angle onto the surface of the second protrusion, the first incident angle satisfying the formula: ,in, The length of the lower bottom edge of the second protrusion. The length of the upper bottom edge of the first protrusion. The angle of inclination of the side edge of the second protrusion. The angle is the first incident angle.

[0008] In some embodiments, the velvet area includes a first velvet area and a second velvet area, the first velvet area being located at the edge of the groove structure, and the second velvet area being disposed on the side of the first velvet area away from the groove structure. The first velvet area includes a first protrusion or a first protrusion and a second protrusion, and the second velvet area includes a second protrusion.

[0009] In some embodiments, the inclined plane is a plane.

[0010] In some embodiments, the bottom surface, the side surface, and the inclined surface of the groove structure are flat surfaces.

[0011] In some embodiments, the solar cell further includes a first passivation layer that covers the groove structure and the textured area.

[0012] In some embodiments, the maximum distance between the bottom surface of the groove structure and the first surface in the thickness direction is 4 μm to 5 μm.

[0013] In some embodiments, the bottom surface of the groove structure has no emitter.

[0014] In some embodiments, a tower base is provided on the bottom surface of the groove structure.

[0015] In some embodiments, the tower base includes a recessed surface that is recessed inward relative to the bottom surface of the groove structure, and a sidewall that connects the bottom surface of the groove structure and the recessed surface and extends obliquely relative to the thickness direction.

[0016] In some embodiments, the side of the sidewall that connects to the bottom surface has a side length of 17 μm to 24 μm; and / or, In the thickness direction, the distance between the recessed surface and the bottom surface of the groove structure is 0.32 μm to 0.58 μm; and / or, The angle between the recessed surface and the sidewall is 137° to 142°.

[0017] Secondly, the sliced ​​battery provided in this application embodiment is obtained by cutting the solar cell provided in any of the above embodiments along the groove structure, and the cut edge of the sliced ​​battery has a stepped morphology formed by the residual groove structure.

[0018] Thirdly, the stacked battery provided in the embodiments of this application includes: Top cell, which can be a perovskite cell, cadmium telluride solar cell, copper indium gallium selenide solar cell, or gallium arsenide solar cell; Intermediate connecting layer; and The bottom battery is a solar cell or a sliced ​​battery provided in any of the above embodiments; The top battery, the intermediate connecting layer, and the bottom battery are stacked and connected.

[0019] Fourthly, the photovoltaic module provided in the embodiments of this application includes the solar cell provided in any of the above embodiments, or the sliced ​​cell provided in any of the above embodiments, or the stacked cell provided in any of the above embodiments.

[0020] Compared with the prior art, the beneficial effects of the embodiments of this application are as follows: The solar cell, sliced ​​cell, tandem cell, and photovoltaic module are provided with a groove structure as a pre-set cutting groove. When cutting the solar cell to form a sliced ​​cell, the groove structure can increase the distance that the laser reaches the cell surface during cutting, thereby reducing the damage of laser energy to the cell. The side of the groove structure extends along the thickness direction, effectively shortening the carrier transport path, reducing recombination loss, and improving photoelectric conversion efficiency. At the same time, the groove structure extending along the thickness direction can also reduce the reflection and escape of incident light, forming an optical trap within the groove structure, enhancing the capture of short-wavelength light, and thus increasing the short-circuit current. The groove edge is provided with a first protrusion in the shape of a truncated pyramid, which can capture light rays with a wide incident angle, maximizing optical benefits. In addition, the side extending along the thickness, the inclined surface connecting the bottom surface and the first surface, and the truncated pyramid protrusion together promote the uniform and dense formation of the subsequent passivation film layer, improve passivation performance, and further reduce the surface recombination rate. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the solar cell structure according to an embodiment of this application.

[0022] Figure 2 for Figure 1 A magnified schematic diagram of a portion of the A structure, where the first passivation layer and the first antireflection layer are not shown.

[0023] Figure 3 This is a partial structural diagram of the first textured region in a solar cell according to an embodiment of this application.

[0024] Figure 4 for Figure 3 Top view.

[0025] Figure 5 This is a scanning electron microscope image of a solar cell according to an embodiment of this application.

[0026] Figure 6 This is a schematic diagram of the tower base structure in the solar cell of this application embodiment.

[0027] Figure 7 for Figure 6 BB cross-sectional view.

[0028] Figure 8 This is a schematic diagram of the solar cell structure for Comparative Example 1.

[0029] Figure 9 for Figure 8 A magnified schematic diagram of the local C structure, where the first passivation layer and the first antireflection layer are not shown.

[0030] Figure 10 This is a schematic diagram of the solar cell structure for Comparative Example 2.

[0031] Figure 11 This is a schematic diagram of the sliced ​​battery structure according to an embodiment of this application. Detailed Implementation

[0032] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0033] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0035] Please refer to Figure 1 and Figure 2This application embodiment of the solar cell 100 includes a substrate 11, a groove structure 12, and a textured region 13. The substrate 11 has a first surface 111 and a second surface 112 disposed opposite to each other in the thickness direction. The groove structure 12 is formed on the first surface 111 and includes a bottom surface 121, a side surface 122, and an inclined surface 123. The bottom surface 121 is recessed inward relative to the first surface 111. The side surface 122 extends from the first surface 111 toward the bottom surface 121 in the thickness direction. The inclined surface 123 extends obliquely from the end of the side surface 122 away from the first surface 111 and connects to the bottom surface 121. The textured region 13 is formed on the first surface 111 and includes a first protrusion 131 located at the edge of the groove structure 12. The first protrusion 131 is a truncated pyramid.

[0036] In this embodiment, a groove structure 12 is provided as a preset cutting groove. When cutting the solar cell 100 to form a sliced ​​cell 1000, the groove structure 12 increases the distance that the laser travels to the cell surface during cutting, thereby reducing the damage to the cell caused by laser energy. The side surface 122 of the groove structure 12 extends along the thickness direction, effectively shortening the carrier transport path, reducing recombination loss, and improving photoelectric conversion efficiency. It also makes the subsequent deposition of the first passivation layer 20 and the first antireflection layer 30 more uniform and dense. At the same time, the groove structure 12 extending along the thickness direction of the side surface 122 can also reduce the reflection and escape of incident light, forming an optical trap within the groove structure 12, enhancing the capture of short-wavelength light, and thus increasing the short-circuit current. The inclined surface 123 connecting the side surface 122 and the bottom surface 121 not only reduces stress concentration and ensures the strength of the solar cell 100, but also makes the subsequent deposition of the first passivation layer 20 and the first antireflection layer 30 more uniform and dense. The groove edge is provided with a first truncated pyramidal protrusion 131, which can capture light rays with a wide incident angle and maximize optical benefits. Moreover, the first truncated pyramidal protrusion 131 further reduces surface dangling bonds and makes the subsequent deposition of the first passivation layer 20 and the first antireflection layer 30 more dense, reducing the surface recombination rate and the surface defect density to 10. 8 cm -2 This improves the open-circuit voltage. In this embodiment, the side surface 122 extending along the thickness, the inclined surface 123 connecting the bottom surface 121 and the first surface 111, and the first truncated pyramid-shaped protrusion 131 together promote the uniform and dense formation of the subsequent first passivation layer 20 and the first antireflection layer 30, improve the passivation performance and further reduce the surface recombination rate, thereby improving the conversion efficiency of the solar cell 100.

[0037] As an example, the first surface 111 can be the front side of the base 11, and the second surface 112 can be the back side of the base 11.

[0038] In some implementation methods, please refer to Figure 1,as well as Figures 3 to 5 The velvet area 13 also includes a second protrusion 132, which is a pyramid, wherein at least a portion of the second protrusion 132 is disposed adjacent to the first protrusion 131.

[0039] As an example, please refer to Figure 1 ,as well as Figures 3 to 5 The first protrusion 131 is the structure of a pyramid after removing the top apex. The difference between the first protrusion 131 and the second protrusion 132 is that the first protrusion 131 has a planar or near-planar upper surface, while the second protrusion 132 is a pointed pyramid. In this embodiment, please refer to... Figure 1 ,as well as Figures 3 to 5 The first protrusion 131 (truncated pyramid) is adjacent to the second protrusion 132 (pointed pyramid, i.e. conventional pyramid). The truncated pyramid can reflect more wide incident angle light to the adjacent pointed pyramid, thereby capturing more wide incident angle light. In this embodiment, the photoelectric conversion efficiency of the solar cell 100 is further improved through the coupling effect of the conventional pointed pyramid, the truncated pyramid and the groove structure 12 extending along the thickness direction of the side 122.

[0040] In some examples, please refer to Figure 4 The first protrusion 131 has a planar top surface 1311. The planar top surface 1311 of the first protrusion 131 has better surface flatness than the pointed pyramid structure and lower roughness, which makes the deposition of the first passivation layer 20 and the first antireflection layer 30 more dense and uniform, with fewer surface composite centers and lower defect density.

[0041] In one embodiment, the second protrusion 132 is used to reflect light rays having a first incident angle onto the surface of the second protrusion 132, the first incident angle satisfying the formula: For reference, please see below. Figure 3 , The length of the lower bottom edge of the second protrusion 132. The length of the upper bottom edge of the first protrusion 131. The angle of the side edge inclination of the second protrusion 132. The angle is the first incident angle.

[0042] As one implementation method, please refer to Figure 5The velvet area 13 includes a first velvet area 13a and a second velvet area 13b. The first velvet area 13a is located at the edge of the groove structure 12, and the second velvet area 13b is located on the side of the first velvet area 13a away from the groove structure 12. The first velvet area 13a includes a first protrusion 131 or a first protrusion 131 and a second protrusion 132, and the second velvet area 13b includes a second protrusion 132. In this embodiment, the first protrusion 131 can be formed simultaneously during the processing of the groove structure 12. First, a laser is used to pre-open the film in the target area, and then a wet process is used to thoroughly remove the residual oxide layer and damaged layer in the target area to form the groove structure 12. During the pre-opening process, the laser can simultaneously remove at least part of the tip of the second protrusion 132 at the edge of the groove, so that at least part of the second protrusion 132 is transformed into the first protrusion 131 in the shape of a truncated pyramid. In this embodiment, the pre-forming of the groove structure 12 and the forming of the truncated pyramid are realized simultaneously through only one laser pre-opening process. While simplifying the steps and reducing costs, it ensures the natural connection between the groove structure 12 and the first protrusion 131. This not only optimizes the capture and reuse of wide-angle incident light, but also promotes the uniform coverage of the subsequent passivation film due to the truncated pyramid, thereby synergistically improving the light trapping performance and surface passivation effect of the battery.

[0043] As an example, the first velvet area 13a may include only the first protrusion 131, that is, all the second protrusions 132 located at the edge of the groove structure 12 are laser-removed from their tips and transformed into the first protrusion 131; or, the first velvet area 13a may include the first protrusion 131 and the second protrusion 132, that is, some of the second protrusions 132 located at the edge of the groove structure 12 are laser-removed from their tips and transformed into the first protrusion 131, while some of the second protrusions 132 are not laser-removed from their tips and still retain the shape of a pyramid with a pointed top. The second velvet area 13b may exclude the first protrusion 131 and include only the second protrusion 132; or, the second velvet area 13b may mainly include the first protrusion 131 and include a small number of second protrusions 132, that is, the number of first protrusions 131 is much greater than the number of second protrusions 132; or, the second velvet area 13b may include both the first protrusion 131 and the second protrusion 132, and the number of first protrusions 131 and second protrusions 132 can be set as needed, which will not be elaborated here.

[0044] In some implementation methods, please refer to Figure 2 In the thickness direction, the height of side 122 Height of inclined plane 123 The ratio is 2:1 to 11:1. As an example, the height of side 122... Height of inclined plane 123 The ratio can be, but is not limited to, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or 11:1, etc.

[0045] In this embodiment, the height of side 122 Height of inclined plane 123 The ratio is controlled within the range of 2:1 to 11:1, which synergistically improves carrier transport and optical trapping capabilities. This embodiment also forms a relatively smooth transition geometric contour on the inner wall of the groove structure 12, which is conducive to the uniform coverage and dense growth of the first passivation layer 20 and the first antireflection layer 30, thereby enhancing the surface passivation effect while improving light absorption and improving the photoelectric conversion efficiency of the battery.

[0046] In some implementation methods, please refer to Figure 2 The angle between inclined plane 123 and base 121 The angle is 32° to 48°. As an example, the included angle between the inclined plane 123 and the bottom surface 121... It can be, but is not limited to, 32°, 33°, 34°, 35°, 36°, 37°, 38°, 39°, 40°, 41°, 42°, 43°, 44°, 45°, 46°, 47°, or 48°, etc.

[0047] In some implementation methods, please refer to Figure 1 and Figure 2 The side surface 122 is perpendicular to the bottom surface 121; in other words, the side surface 122 is completely parallel to the thickness direction, making the carrier extraction path along the thickness direction the shortest and most direct, reducing recombination losses caused by lateral diffusion. Simultaneously, the perpendicular side surface 122 maximizes the depth effect of the groove structure 12, enhancing the ability to capture vertical and small-angle incident light, and forming optical synergy with the inclined surface 123 and the first protrusion 131, improving the overall light-trapping efficiency. It should be noted that in other embodiments, the side surface 122 can also have a small angle with the thickness direction; for example, the angle between the sidewall 142 and the thickness direction is less than or equal to 10°. Even within the allowable small angle range (e.g., ≤10°), the side surface 122 can still maintain the near-vertical photoelectric performance advantage, providing flexible space for process tolerance and balancing structural ideality and manufacturing feasibility.

[0048] In some implementation methods, please refer to Figure 1 and Figure 2The inclined surface 123 is planar, giving the inner wall of the groove structure 12 a clear and continuous geometric interface. This facilitates the formation of a uniform energy distribution during laser pre-cutting, reduces local thermal stress concentration, and thus reduces lattice damage. Simultaneously, the planar inclined surface 123 can more stably and directionally reflect incident light to the bottom surface 121 of the groove structure 12, improving not only optical reflection and trapping capabilities but also promoting the uniform and dense growth of the passivation film on the inclined surface 123, enhancing the passivation effect, and thereby synergistically optimizing the photoelectric conversion performance and process reliability of the battery.

[0049] In some implementation methods, please refer to Figure 1 and Figure 2 The bottom surface 121, side surface 122 and inclined surface 123 of the groove structure 12 are flat surfaces. That is to say, the bottom surface 121, side surface 122 and inclined surface 123 of the groove structure 12 are not textured surfaces. The flat inner wall surface of the groove structure 12 can provide a uniform and continuous deposition substrate 11 for the subsequent first passivation layer 20 and first antireflection layer 30, which is more conducive to the dense growth and good coverage of the first passivation layer 20.

[0050] In some embodiments, the maximum distance between the bottom surface 121 of the groove structure 12 and the first surface 111 in the thickness direction is 4μm to 5μm, that is, the depth of the groove structure 12. The depth is 4μm to 5μm. As an example, the maximum distance between the bottom surface 121 of the groove structure 12 and the first surface 111 refers to the distance between the bottom surface 121 of the groove structure 12 and the top of the pyramid structure (second protrusion 132) on the first surface 111. For example, the maximum distance between the bottom surface 121 of the groove structure 12 and the first surface 111 (the depth of the groove structure 12) The depth can be, but is not limited to, 4μm, 4.1μm, 4.2μm, 4.3μm, 4.4μm, 4.5μm, 4.6μm, 4.7μm, 4.8μm, 4.9μm, or 5μm, etc. In this embodiment, the maximum distance between the bottom surface 121 of the groove structure 12 and the first surface 111 (the depth of the groove structure 12) is... The depth of the groove structure 12 is 4μm to 5μm, which can provide sufficient vertical height to shorten the lateral transport distance of charge carriers and reduce recombination loss, while ensuring that the groove structure 12 forms a stable structural morphology during the laser pre-cutting process. This avoids the decrease in mechanical strength caused by the groove structure 12 being too deep, or the difficulty in covering the first passivation layer 20 and the first anti-reflection layer 30.

[0051] In some embodiments, the bottom surface 121 of the groove structure 12 has no emitter, that is, the bottom surface 121 of the groove structure 12 and the PN junction below it are completely removed, thereby further reducing the cutting loss during slicing.

[0052] In some implementation methods, please refer to Figure 5 A tower base 14 is provided on the bottom surface 121 of the groove structure 12. Functional thin films such as the first passivation layer 20 and the first antireflection layer 30 are also covered within the tower base 14. The tower base 14 facilitates the more dense and firm deposition of functional thin films such as the first passivation layer 20 and the first antireflection layer 30, thereby further enhancing the passivation effect and reducing surface recombination. At the same time, the tower base 14 can also further improve the light trapping capability of the battery.

[0053] As an example, please refer to Figure 7 The base 14 includes a recessed surface 141 and a sidewall 142. The recessed surface 141 is recessed inward relative to the bottom surface 121 of the groove structure 12. The sidewall 142 connects the bottom surface 121 of the groove structure 12 and the recessed surface 141. The sidewall 142 extends obliquely relative to the thickness direction.

[0054] As one implementation method, please refer to Figure 6 and Figure 7 The side length of the side wall 142 connected to the bottom surface 121 The diameter is 17μm to 24μm. As an example, the side length of the side where the sidewall 142 connects to the bottom surface 121 is... The thickness can be, but is not limited to, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, or 24μm. In this embodiment, the inclined sidewall 142 can guide light to undergo multiple reflections inside the groove structure 12, enhancing the capture and absorption of incident light. Simultaneously, the tower base 14 increases the bottom surface area of ​​the groove structure 12 and forms a gradually changing geometric transition, which facilitates a more uniform and dense coverage of the passivation film, reduces interface defects, and thus further suppresses carrier recombination while enhancing light-trapping capability, thereby improving the overall photoelectric conversion efficiency of the battery.

[0055] As one implementation method, please refer to Figure 7 In the thickness direction, the distance between the recessed surface 141 and the bottom surface 121 of the groove structure 12 (i.e., the depth of the tower base 14) The height of the sidewall 142 in the thickness direction is 0.32 μm to 0.58 μm. As an example, the distance between the recessed surface 141 and the bottom surface 121 of the groove structure 12 in the thickness direction (the depth of the tower base 14) is... The aperture value can be, but is not limited to, 0.32μm, 0.33μm, 0.34μm, 0.35μm, 0.36μm, 0.37μm, 0.38μm, 0.39μm, 0.40μm, 0.41μm, 0.42μm, 0.43μm, 0.44μm, 0.45μm, 0.46μm, 0.47μm, 0.48μm, 0.49μm, 0.50μm, 0.51μm, 0.52μm, 0.53μm, 0.54μm, 0.55μm, 0.56μm, 0.57μm, or 0.58μm, etc. This embodiment can form a sufficient optical resonant cavity effect, enhance the light trapping effect, and at the same time avoid excessively long optical path or difficulty in carrier collection caused by excessively deep concavity. Furthermore, the inclined sidewalls 142 within this height range can provide a more ideal morphological transition for the subsequent passivation film, which is more conducive to the uniform and dense deposition of the first passivation layer 20, thereby simultaneously improving light absorption capacity and passivation effect, and thus improving the performance of the battery.

[0056] As one implementation method, please refer to Figure 7 The included angle between the concave surface 141 and the side wall 142 The angle is 137° to 142°. As an example, the included angle between the recessed surface 141 and the sidewall 142... The angle can be, but is not limited to, 137°, 138°, 139°, 140°, 141°, or 142°, etc. This embodiment can enhance the ability to capture short-wavelength light and reduce direct reflection loss. Meanwhile, the angle between the recessed surface 141 and the sidewall 142... The angle of 137° to 142° can provide a smoother and more continuous surface transition for the subsequent deposition of the first passivation layer 20 and the first antireflection layer 30, promote the uniform and dense coverage of the first passivation layer 20, effectively reduce interface defects and suppress carrier recombination, thereby improving the light trapping ability and passivation effect, and further improving the performance of the battery.

[0057] In some implementation methods, please refer to Figure 1 The solar cell 100 also includes a first passivation layer 20, which covers the groove structure 12 and the textured region 13. In this embodiment, the first passivation layer 20 is uniformly and continuously deposited on the inner wall of the flat groove structure 12 and the textured region 13, forming a dense and complete coating with low defect density. As an example, the first passivation layer 20 can be an aluminum oxide layer.

[0058] Please refer to Figure 8 and Figure 9The comparative solar cell 200 shown is basically the same as the solar cell 100 of the present application embodiment. The difference between the comparative solar cell 200 and the solar cell 100 of the present application embodiment is that the groove structure 22 in the comparative example only includes a bottom surface 221 that is recessed inward relative to the first surface 211 of the substrate 21, and a side surface 222 that connects the bottom surface 221 and the first surface 211 and extends obliquely relative to the thickness direction. In addition, the textured area 23 only includes a second protrusion 232 and has no first protrusion. Please refer to Figure 8 , Figure 8 The middle line S81 is used to illustrate the carrier transport path in the comparative example. In the comparative example, the ramp structure (side 222) causes carriers to transport along the ramp direction, resulting in a longer transport path. During migration, there is some recombination loss, and the ramp is prone to defects due to uneven etching, exacerbating carrier recombination. Furthermore, the relatively rough surface of the ramp structure contains more defects, leading to uneven deposition of functional films such as the first passivation layer and the first antireflection layer, resulting in a high surface state density and poor passivation performance. In addition, Figure 9 The middle line S91 is used to illustrate the optical escape path in the comparative example. Figure 9 The middle line S92 is used to illustrate the optical capture path in the comparative example, by Figure 9 It can be seen that the slope also tends to exacerbate the reflection and escape of incident light, and the optical capture path is also relatively long.

[0059] And in Figures 1 to 7 In the embodiment shown in this application, the side surface 122 is a vertical surface with a short-distance inclined surface 123, and the velvet area 13 includes a first protrusion 131 disposed at the edge of the groove structure 12 and a second protrusion 132 disposed adjacent to the first protrusion 131. Please refer to... Figure 1 , Figure 1 The line S11 in the middle is used to illustrate the optical capture path of the light illuminating the groove structure 12 in this embodiment. Figure 1 The middle line S12 is used to illustrate the carrier transport path in this embodiment. Please refer to... Figure 2 , Figure 2 The middle line S21 is used to illustrate the optical capture path of the light illuminating the side 122 in this embodiment. Figure 2 The middle line S22 is used to illustrate the optical capture path of the light rays illuminating the inclined plane 123 in this embodiment. Please refer to... Figure 3 , Figure 3 The middle line S31 is used to illustrate the optical acquisition path in this embodiment. Figures 1 to 3As can be seen, in this embodiment, the carrier transport path is shorter, reducing recombination loss. Furthermore, the groove structure 12 reduces incident light escape diffuse scattering loss, improves short-wavelength optical absorption, and brings short-circuit current gains. Additionally, the first protrusion 131 and the second protrusion 132 work together to capture light rays with wide incident angles, maximizing optical gains. Moreover, the truncated pyramidal first protrusion 131 further reduces surface dangling bonds. The side 122 extending along the thickness, the inclined surface 123 connecting the bottom surface 121 and the first surface 111, and the truncated pyramidal first protrusion 131 together make the subsequent deposition of the first passivation layer 20 and the first antireflection layer 30 more dense, reducing the surface recombination rate and surface defect density to 10. 8 cm -2 .

[0060] The solar cell 100 in this embodiment can be a TOPCon (Tunnel Oxide Passivated Contact) solar cell. In other embodiments, the solar cell 100 can also be a BC (Back Contact) solar cell, or an HJT (Heterojunction with Intrinsic Thin-layer) solar cell, etc., and the specific configuration can be determined according to the actual situation, which will not be elaborated here.

[0061] As an example, the structure of the solar cell 100 will be described in detail using a TOPCon cell as an example. Please refer to [link / reference]. Figure 1 As shown, the solar cell 100 includes a substrate 11, a first passivation layer 20 disposed on a first surface 111 of the substrate 11, a first antireflection layer 30 disposed on the first passivation layer 20, a first electrode 40 disposed on the first surface 111 of the substrate 11, a tunneling oxide layer 50 disposed on a second surface 112 of the substrate 11, a doped polycrystalline silicon layer 60 disposed on the tunneling oxide layer 50, a second antireflection layer 70 disposed on the doped polycrystalline silicon layer 60, and a second electrode (not shown) disposed on the second surface 112 of the substrate 11.

[0062] The first surface 111 of the substrate 11 is the front surface, the emitter is located below the textured area 13, the first passivation layer 20 covers the textured area 13 and the groove structure 12, the first antireflection layer 30 covers the first passivation layer 20, and the first electrode 40 is disposed in the area where the textured area 13 is located. The first electrode 40 passes through the first antireflection layer 30 and the first passivation layer 20 in sequence in the thickness direction of the substrate 11 and is connected to the emitter.

[0063] The second side 112 of the substrate 11 is the back side, where a tunneling oxide layer 50, a doped polysilicon layer 60 and a second antireflection layer 70 are deposited sequentially. The second electrode corresponds to the textured region 13 in the thickness direction and extends through the second antireflection layer 70 to connect with the doped polysilicon layer 60.

[0064] In some embodiments, the substrate 11 can be an N-type semiconductor substrate 11 or a P-type semiconductor substrate 11. The N-type semiconductor substrate 11 is doped with an N-type dopant element, which can be any one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate 11 is doped with a P-type dopant element, which can be any one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0065] In some embodiments, the emitter can be formed by doping an initial substrate. The emitter and substrate 11 have the same base material, but the dopant type in the emitter is different from the dopant type in substrate 11. For example, if substrate 11 is an N-type silicon substrate, the emitter is formed by P-type doping of a portion of the N-type silicon substrate. As an example, a portion of the N-type initial substrate corresponding to the textured region 13 can be boron-doped. The boron-doped portion of the initial substrate serves as the emitter, and the remaining undoped initial substrate serves as substrate 11.

[0066] In some embodiments, the first passivation layer 20 can be a single-layer structure or a stacked structure, and the material used to prepare the first passivation layer 20 can be one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0067] In some embodiments, the material used to prepare the first antireflection layer 30 may be one or more of silicon nitride or silicon oxynitride.

[0068] In some embodiments, the tunneling oxide layer 50 may be a silicon dioxide layer.

[0069] In some embodiments, the doping type of the doped polysilicon layer 60 is the same as the doping type of the substrate 11. For example, if the substrate 11 is doped with an N-type dopant, then the doped polysilicon layer 60 is doped with an N-type dopant. The tunneling oxide layer 50 and the doped polysilicon layer 60 together form a passivation contact structure.

[0070] In some embodiments, the material used to prepare the second antireflection layer 70 may be one or more of silicon nitride or silicon oxynitride.

[0071] In some embodiments, the first electrode 40 has the opposite polarity to the second electrode.

[0072] As an example, the method for preparing the solar cell 100 includes steps S10 to S80: Step S10, providing an initial base, the front of the initial base having an initial velvet area 13, the initial velvet area 13 including a pointed pyramid covering the front of the initial base.

[0073] In one implementation, the initial substrate is an N-type monocrystalline silicon wafer.

[0074] In one implementation, the initial substrate has a resistivity of 1 Ω·cm to 5 Ω·cm and a thickness of 130 μm.

[0075] In one implementation, the average size of the pointed pyramid is 2μm to 5μm.

[0076] Step S20: Perform a first doping treatment on the initial substrate to form an emitter and a mask layer covering the emitter on the front side of the initial substrate, thereby obtaining a first intermediate.

[0077] In one implementation, the initial substrate is an N-type single-crystal silicon wafer. Step S20 specifically includes: performing a boron diffusion treatment on the initial substrate to form a boron-doped layer and a borosilicate glass layer covering the boron-doped layer on the front side of the initial substrate, thereby obtaining a first intermediate. The boron-doped layer serves as the emitter, the undoped initial substrate serves as the substrate 11 of the solar cell 100, and the borosilicate glass layer serves as a mask layer.

[0078] As an example, the temperature of the boron diffusion treatment is 600℃~1100℃, the sheet resistance after boron diffusion is 50 Ohm / sq~800 Ohm / sq, and the thickness of the borosilicate glass layer is 80nm~200nm.

[0079] Step S30: Perform laser pre-filming treatment on the first intermediate body to remove the mask layer of a preset area or remove the mask layer of the preset area and at least part of the emitter, and remove at least part of the apex of the pointed pyramid at the edge of the groove to form a truncated pyramid, thereby obtaining the second intermediate body. The truncated pyramid serves as the first protrusion 131, and the pointed pyramid that retains its apex shape without having its apex removed serves as the second protrusion 132.

[0080] In one implementation, in step S30, a laser beam is used for laser pre-filming treatment. The laser beam type includes ultraviolet nanosecond, green picosecond, green nanosecond or infrared continuous laser beam, with a laser power of 1W to 2000W, a frequency of 100kHz to 5000kHz, and a laser marking speed of 2000mm / s to 10000mm / s.

[0081] Step S40: Perform a first wet process on the second intermediate to remove the residual mask layer and at least part of the emitter in the preset area, forming an initial groove structure to obtain the third intermediate.

[0082] In one implementation, step S40 involves performing a first wet treatment on the second intermediate using an alkaline solution, which includes NaOH or KOH and contains polishing additives. This process initially etches the PN junction (emitter) in a predetermined area to form a polished surface. For example, the temperature of the first wet treatment is 65°C to 80°C, the reaction time is 200s to 300s, and the depth of the initial groove structure formed by the first wet treatment is 1μm to 3μm.

[0083] In step S50, a tunneling oxide layer 50 and a doped polysilicon layer 60 covering the tunneling oxide layer 50 are formed on the back side of the third intermediate to obtain the fourth intermediate.

[0084] In one implementation, step S50 specifically includes: sequentially forming a tunneling oxide layer 50 and an intrinsic amorphous silicon layer on the back side of the third intermediate; performing phosphorus doping and high-temperature crystallization treatment on the intrinsic amorphous silicon layer to transform it into a phosphorus-doped polycrystalline silicon layer 60. In some examples, during the phosphorus doping and high-temperature crystallization treatment of the intrinsic amorphous silicon layer, a phosphorus-silicon glass layer is also formed on the surface of the phosphorus-doped polycrystalline silicon layer 60.

[0085] As an example, when a boron-doped layer and a borosilicate glass layer are formed on the front side of the initial substrate in step S20, a boron-doped layer and a borosilicate glass layer covering the surface of the boron-doped layer are also formed on the back side of the initial substrate. Therefore, in step S50, before forming the tunneling oxide layer 50 on the back side of the third intermediate, it is necessary to remove the borosilicate glass layer and the boron-doped layer on the back side of the third intermediate to form a polished surface on the back side.

[0086] Step S60: Perform a second wet process on the fourth intermediate to remove the phosphosilicate glass layer on the front and back sides and the borosilicate glass layer on the front side, and further etch the initial groove structure to form groove structure 12, thereby obtaining the fifth intermediate.

[0087] It is understood that in step S50, a phosphonium-doped polysilicon layer 60 and a phosphosilicate glass layer are formed on the back side of the third intermediate, and a phosphonium-doped layer and a phosphosilicate glass layer are also formed on the front side of the third intermediate. Therefore, as one embodiment, step S60 specifically includes: removing the phosphosilicate glass layer on the front side of the fourth intermediate using an acid solution, then etching the fourth intermediate in an alkaline solution to remove the front side plating (phosphorus-doped layer) while further etching the initial groove structure on the front side into the substrate 11 to form a groove structure 12, and then removing the phosphosilicate glass layer on the back side and the remaining borosilicate glass layer on the front side using an acid solution.

[0088] As an example, the depth of the groove structure 12 is 4μm to 5μm. In step S60, the bottom surface 121 of the groove structure 12 and the PN junction (emitter) below it are completely removed, thereby reducing the cutting loss during subsequent slicing.

[0089] In step S70, a first passivation layer 20 is deposited on the front side of the fifth intermediate, and a first antireflection layer 30 and a second antireflection layer 70 are deposited on the front and back sides of the fifth intermediate to obtain the sixth intermediate.

[0090] As an example, the first passivation layer 20 is an aluminum oxide layer. The thickness of the aluminum oxide layer is 5nm to 6nm, and the first antireflection layer 30 and the second antireflection layer 70 are silicon nitride layers with a thickness of 50nm to 120nm.

[0091] In step S80, a first electrode 40 is formed on the front side of the sixth intermediate and a second electrode is formed on the back side of the sixth intermediate to obtain a solar cell 100.

[0092] Please refer to Figure 11 The sliced ​​battery 1000 provided in this application embodiment is obtained by cutting the solar cell 100 provided in any of the above embodiments along the groove structure 12. The structure of the solar cell 100 is as follows: Figure 1 Please refer to this. Figure 11 The cut edge of the sliced ​​solar cell 1000 has a stepped morphology 1001, which is formed by the residue of the groove structure 12. As an example, the solar cell 100 is cut into sliced ​​solar cells 1000 by a laser along the length direction of the groove structure 12 (the length direction of the groove structure 12 is perpendicular to the thickness direction and transverse direction of the substrate 11). Please refer to... Figure 11 , Figure 11 The line S111 in the middle is used to illustrate the optical capture path of the light illuminating the step topography 1001 in this embodiment. Figure 11 The middle line S112 is used to illustrate the carrier transport path in this embodiment.

[0093] In this embodiment, a groove structure 12 is provided as a preset cutting groove. When cutting the solar cell 100 to form a sliced ​​cell 1000, the groove structure 12 increases the distance that the laser travels to the cell surface during cutting, thereby reducing the damage to the cell caused by laser energy. The side surface 122 of the groove structure 12 extends along the thickness direction, effectively shortening the carrier transport path, reducing recombination loss, and improving photoelectric conversion efficiency. It also makes the subsequent deposition of the first passivation layer 20 and the first antireflection layer 30 more uniform and dense. At the same time, the groove structure 12 extending along the thickness direction of the side surface 122 can also reduce the reflection and escape of incident light, forming an optical trap within the groove structure 12, enhancing the capture of short-wavelength light, and thus increasing the short-circuit current. The inclined surface 123 connecting the side surface 122 and the bottom surface 121 not only reduces stress concentration and ensures the strength of the solar cell 100, but also makes the subsequent deposition of the first passivation layer 20 and the first antireflection layer 30 more uniform and dense. The groove edge is provided with a first truncated pyramidal protrusion 131, which can capture light rays with a wide incident angle and maximize optical benefits. Moreover, the first truncated pyramidal protrusion 131 further reduces surface dangling bonds and makes the subsequent deposition of the first passivation layer 20 and the first antireflection layer 30 more dense, reducing the surface recombination rate and the surface defect density to 10. 8 cm -2 This improves the open-circuit voltage. In this embodiment, the side surface 122 extending along the thickness, the inclined surface 123 connecting the bottom surface 121 and the first surface 111, and the first truncated pyramid-shaped protrusion 131 together promote the uniform and dense formation of the subsequent first passivation layer 20 and the first anti-reflection layer 30, improve the passivation performance and further reduce the surface recombination rate, thereby improving the conversion efficiency of the sliced ​​battery 1000.

[0094] In some embodiments, the sliced ​​solar cell 1000 further includes a second passivation layer 1003 formed on the cut surface 1002. The second passivation layer 1003 can passivate the exposed cut surface 1002, effectively suppressing edge carrier recombination, thereby further improving the photoelectric conversion efficiency of the sliced ​​solar cell 1000. As an example, the second passivation layer 1003 may include one or more layers selected from aluminum oxide layer, silicon nitride layer and polycrystalline silicon layer.

[0095] The tandem solar cell provided in this application includes a top cell, an intermediate connecting layer, and a bottom cell, which are stacked together. The top cell is a perovskite solar cell, a cadmium telluride solar cell, a copper indium gallium selenide solar cell, or a gallium arsenide solar cell. The bottom cell is either the solar cell 100 provided in any of the above embodiments or the sliced ​​cell 1000 provided in any of the above embodiments.

[0096] In this embodiment, a groove structure 12 is provided as a preset cutting groove. When cutting the solar cell 100 to form a sliced ​​cell 1000, the groove structure 12 increases the distance that the laser travels to the cell surface during cutting, thereby reducing the damage to the cell caused by laser energy. The side surface 122 of the groove structure 12 extends along the thickness direction, effectively shortening the carrier transport path, reducing recombination loss, and improving photoelectric conversion efficiency. It also makes the subsequent deposition of the first passivation layer 20 and the first antireflection layer 30 more uniform and dense. At the same time, the groove structure 12 extending along the thickness direction of the side surface 122 can also reduce the reflection and escape of incident light, forming an optical trap within the groove structure 12, enhancing the capture of short-wavelength light, and thus increasing the short-circuit current. The inclined surface 123 connecting the side surface 122 and the bottom surface 121 not only reduces stress concentration and ensures the strength of the solar cell 100, but also makes the subsequent deposition of the first passivation layer 20 and the first antireflection layer 30 more uniform and dense. The groove edge is provided with a first truncated pyramidal protrusion 131, which can capture light rays with a wide incident angle and maximize optical benefits. Moreover, the first truncated pyramidal protrusion 131 further reduces surface dangling bonds and makes the subsequent deposition of the first passivation layer 20 and the first antireflection layer 30 more dense, reducing the surface recombination rate and the surface defect density to 10. 8 cm -2 This improves the open-circuit voltage. In this embodiment, the side surface 122 extending along the thickness, the inclined surface 123 connecting the bottom surface 121 and the first surface 111, and the first truncated pyramid-shaped protrusion 131 together promote the uniform and dense formation of the subsequent first passivation layer 20 and the first anti-reflection layer 30, improve the passivation performance and further reduce the surface recombination rate, thereby improving the conversion efficiency of the tandem battery.

[0097] The photovoltaic modules provided in this application include the solar cell 100 provided in any of the above embodiments, or the sliced ​​cell 1000 provided in any of the above embodiments, or the stacked cell provided in any of the above embodiments.

[0098] In this embodiment, a groove structure 12 is provided as a preset cutting groove. When cutting the solar cell 100 to form a sliced ​​cell 1000, the groove structure 12 increases the distance that the laser travels to the cell surface during cutting, thereby reducing the damage to the cell caused by laser energy. The side surface 122 of the groove structure 12 extends along the thickness direction, effectively shortening the carrier transport path, reducing recombination loss, and improving photoelectric conversion efficiency. It also makes the subsequent deposition of the first passivation layer 20 and the first antireflection layer 30 more uniform and dense. At the same time, the groove structure 12 extending along the thickness direction of the side surface 122 can also reduce the reflection and escape of incident light, forming an optical trap within the groove structure 12, enhancing the capture of short-wavelength light, and thus increasing the short-circuit current. The inclined surface 123 connecting the side surface 122 and the bottom surface 121 not only reduces stress concentration and ensures the strength of the solar cell 100, but also makes the subsequent deposition of the first passivation layer 20 and the first antireflection layer 30 more uniform and dense. The groove edge is provided with a first truncated pyramidal protrusion 131, which can capture light rays with a wide incident angle and maximize optical benefits. Moreover, the first truncated pyramidal protrusion 131 further reduces surface dangling bonds and makes the subsequent deposition of the first passivation layer 20 and the first antireflection layer 30 more dense, reducing the surface recombination rate and the surface defect density to 10. 8 cm -2 This improves the open-circuit voltage. In this embodiment, the side surface 122 extending along the thickness, the inclined surface 123 connecting the bottom surface 121 and the first surface 111, and the first truncated pyramid-shaped protrusion 131 together promote the uniform and dense formation of the subsequent first passivation layer 20 and the first anti-reflection layer 30, improve the passivation performance and further reduce the surface recombination rate, thereby improving the conversion efficiency of the photovoltaic module.

[0099] Example 1 The structure of the solar cell 100 in this embodiment 1 is as follows: Figures 1 to 7 As shown, the height of side 122 Height of inclined plane 123 The ratio is 2:1.

[0100] As an example, the method for preparing the solar cell 100 in this embodiment 1 includes steps S10 to S80: Step S10, providing an initial base, the front of the initial base having an initial velvet area 13, the initial velvet area 13 including a pointed pyramid covering the front of the initial base.

[0101] In one implementation, the initial substrate is an N-type monocrystalline silicon wafer.

[0102] In one implementation, the initial substrate has a resistivity of 1 Ω·cm to 5 Ω·cm and a thickness of 130 μm.

[0103] In one implementation, the average size of the pointed pyramid is 2μm to 5μm.

[0104] Step S20: Perform a first doping treatment on the initial substrate to form an emitter and a mask layer covering the emitter on the front side of the initial substrate, thereby obtaining a first intermediate.

[0105] In one implementation, the initial substrate is an N-type single-crystal silicon wafer. Step S20 specifically includes: performing a boron diffusion treatment on the initial substrate to form a boron-doped layer and a borosilicate glass layer covering the boron-doped layer on the front side of the initial substrate, thereby obtaining a first intermediate. The boron-doped layer serves as the emitter, the undoped initial substrate serves as the substrate 11 of the solar cell 100, and the borosilicate glass layer serves as a mask layer.

[0106] As an example, step S20 specifically includes: passing boron trichloride (BCl3) into a quartz tube at 1030°C, where boron trichloride reacts with oxygen to generate gaseous boron trioxide (B2O3), and nitrogen is used as a carrier gas to transport and deposit the gaseous boron trioxide onto the silicon wafer surface. The boron trioxide reacts with silicon to form a borosilicate glass layer, forming a boron-rich borosilicate glass layer (SiO2–B2O3). Then, the layer is kept at 1030°C for 15 minutes, and the boron atoms in the borosilicate glass diffuse into the silicon substrate through the interface to complete boron doping. Finally, a boron doped layer with a thickness of 650 nm and a borosilicate glass layer with a thickness of 85 nm are formed on the front side of the initial substrate.

[0107] Step S30: Perform laser pre-filming treatment on the first intermediate body to remove the mask layer of a preset area or remove the mask layer of the preset area and at least part of the emitter, and remove at least part of the apex of the pointed pyramid at the edge of the groove to form a truncated pyramid, thereby obtaining the second intermediate body. The truncated pyramid serves as the first protrusion 131, and the pointed pyramid that retains its apex shape without having its apex removed serves as the second protrusion 132.

[0108] In one implementation, in step S30, a green picosecond laser is used for laser pre-film opening processing, with a laser power of 72W, a frequency of 350kHz, and a laser marking speed of 3000mm / s.

[0109] Step S40: The second intermediate is subjected to a first wet process to remove the residual mask layer and at least part of the emitter in the preset area, forming an initial groove structure with an initial side surface and an initial slope, thus obtaining a third intermediate. The initial side surface is perpendicular to the bottom surface, and the initial slope has a preliminary inclined profile.

[0110] In one implementation, step S40 involves using an alkaline solution to perform a first wet treatment on the second intermediate, thereby initially etching the PN junction (emitter) in a predetermined region to form a polished surface. For example, the alkaline solution includes NaOH with a mass concentration of 8 wt%, and also contains a polishing additive with a mass concentration of 0.8 wt%. The polishing additive comprises persulfate, polyol, and siloxane coupling agent (such as APTES (3-Aminopropyltriethoxysilane)). The temperature of the first wet treatment (alkaline solution temperature) is 75°C, the treatment time is 280 s, and the depth of the initial groove structure formed by the first wet treatment is 1.4 μm.

[0111] In step S50, a tunneling oxide layer 50 and a doped polysilicon layer 60 covering the tunneling oxide layer 50 are formed on the back side of the third intermediate to obtain the fourth intermediate.

[0112] In one implementation, step S50 specifically includes: firstly, using a low-pressure chemical vapor deposition process, oxygen is introduced and a high temperature of 500°C is maintained, and a tunneling oxide layer 50 is continuously deposited on the silicon surface on the back side of the third intermediate for 5 minutes to form a tunneling oxide layer 50, the tunneling oxide layer 50 comprising a SiO layer with a thickness of 1.5 nm. x Next, a low-pressure chemical vapor deposition process is used to generate silicon and hydrogen through the thermal decomposition of silane (SiH4) at a high temperature of 600℃. This generates silicon and hydrogen, which are then deposited on the surface of the tunneling oxide layer 50 to form an intrinsic amorphous silicon (a-Si) layer with a thickness of 140nm. Intrinsic amorphous silicon refers to pure silicon without any impurities. Then, a deposition process is performed at 800℃ for 13 minutes using a mixed atmosphere of phosphorus oxychloride (POCl3), oxygen (O2), and nitrogen (N2), followed by a high-temperature crystallization process at 870℃ for 20 minutes. This achieves a phosphorus doping depth of 400nm, transforming the intrinsic amorphous silicon layer into a phosphorus-doped polycrystalline silicon layer 60. During the phosphorus doping and high-temperature crystallization processes, a 40nm thick phosphorosilicate glass layer is also simultaneously formed on the surface of the phosphorus-doped polycrystalline silicon layer 60.

[0113] As an example, when a boron-doped layer and a borosilicate glass layer are formed on the front side of the initial substrate in step S20, a boron-doped layer and a borosilicate glass layer covering the surface of the boron-doped layer are also formed on the back side of the initial substrate. Therefore, in step S50, before forming the tunneling oxide layer 50 on the back side of the third intermediate, it is necessary to remove the borosilicate glass layer and the boron-doped layer on the back side of the third intermediate to form a polished surface on the back side.

[0114] Step S60: Perform a second wet process on the fourth intermediate to remove the phosphosilicate glass layer on the front and back sides and the borosilicate glass layer on the front side, and further etch the initial groove structure to form groove structure 12, thereby obtaining the fifth intermediate.

[0115] It is understood that in step S50, a phosphate-doped polysilicon layer 60 and a phosphosilicate glass layer are formed on the back side of the third intermediate, and a phosphate-doped layer and a phosphosilicate glass layer are also formed on the front side of the third intermediate. Therefore, as one embodiment, step S60 specifically includes: firstly, removing the phosphosilicate glass layer on the front side of the fourth intermediate using a hydrofluoric acid solution, wherein the hydrofluoric acid solution is prepared by mixing 49wt% hydrofluoric acid (HF) with deionized water at a volume ratio of 1:50, the treatment temperature is 35°C, and the treatment time is 45s. Subsequently, the fourth intermediate is placed in a potassium hydroxide solution for etching treatment, the potassium hydroxide solution having a mass concentration of 13wt%, the treatment temperature is 65°C, and the treatment time is 300s. This step removes the phosphorus-doped layer around the front side while further etching the initial groove structure on the front side into the substrate, thereby forming a groove structure. Finally, the remaining phosphosilicate glass layer on the back side and the remaining borosilicate glass layer on the front side are removed again using a hydrofluoric acid solution. After the above processing, a final groove structure 12 with a significant inclined surface 123 can be formed on the substrate, wherein the depth of the groove structure 12 is 4.5 μm and the height of the side surface 122 is [missing information]. Height of inclined plane 123 The ratio is 2:1, and the angle between the inclined plane 123 and the base 121 is... The angle is 48°. In step S60, the bottom surface 121 of the groove structure 12 and the PN junction (emitter) below it are completely removed, thereby reducing the cutting loss during subsequent slicing.

[0116] In step S70, a first passivation layer 20 is sequentially deposited on the front side of the fifth intermediate, and a first antireflection layer 30 and a second antireflection layer 70 are deposited on both the front and back sides of the fifth intermediate to obtain the sixth intermediate. As an example, step S70 specifically includes: firstly, using atomic layer deposition (ALD) to deposit aluminum oxide (Al2O3) at 230°C for 20 minutes via the self-limiting reaction of trimethylaluminum (TMA) and water (H2O), thereby forming an aluminum oxide layer with a thickness of 6 nm (first passivation layer 20) and a negatively charged surface to achieve a field passivation effect on the front side of the fifth intermediate. Subsequently, using plasma-enhanced chemical vapor deposition (PECVD) to introduce silane (SiH4) and ammonia (NH3) at a high temperature of 400°C for 30 minutes, an 80 nm thick silicon nitride layer (first antireflection layer 30) is formed on the front side of the fifth intermediate, and an 80 nm thick silicon nitride layer (second antireflection layer 70) is formed on the back side of the fifth intermediate, thus obtaining the sixth intermediate.

[0117] In step S80, a first electrode 40 is formed on the front side of the sixth intermediate and a second electrode is formed on the back side of the sixth intermediate to obtain a solar cell 100.

[0118] As an example, step S80 specifically includes: forming a first electrode 40 on the front side of the sixth intermediate using a screen printing process with conductive silver paste, and forming a second electrode on the back side of the sixth intermediate, wherein the first electrode 40 has a height of 6.3 μm, a width of 13.7 μm, and an aspect ratio of 0.46, and the second electrode has a height of 6.2 μm, a width of 20.1 μm, and an aspect ratio of 0.31.

[0119] Example 2 The structure of the solar cell 100 in this embodiment 2 is basically the same as that in embodiment 1, except that the height of the side 122 is different. Height of inclined plane 123 The ratio is 8:1.

[0120] The fabrication method of the solar cell 100 in Example 2 is basically the same as that in Example 1, except for the specific process parameters of step S60. As one embodiment, in the fabrication method of the solar cell 100 in Example 2, step S60 specifically includes: using an acid solution prepared by mixing 49wt% hydrofluoric acid and deionized water at a volume ratio of 1:50, and treating at 35°C for 55 seconds to remove the phosphosilicate glass layer on the front side of the fourth intermediate. Subsequently, it is etched at 68°C for 350 seconds in a 13wt% potassium hydroxide solution. The depth of the groove structure 12 formed in step S60 of the fabrication method of the solar cell 100 in Example 2 and the lateral width of the bottom surface 121 of the groove structure 12 are basically the same as in Example 1, but the height of the side surface 122 of the groove structure 12 formed in step S60 of the fabrication method of Example 2 is different. Height of inclined plane 123 The ratio is 8:1, and the angle between the inclined plane 123 and the base 121 is... It is 39°.

[0121] Example 3 The structure of the solar cell 100 in this embodiment 3 is basically the same as that in embodiment 1, except that the height of the side 122 is different. Height of inclined plane 123 The ratio is 11:1.

[0122] The fabrication method of the solar cell 100 in Example 3 is basically the same as that in Example 1, except for the specific process parameters of step S60. As one embodiment, in the fabrication method of the solar cell 100 in Example 3, step S60 specifically includes: using an acid solution prepared by mixing 49wt% hydrofluoric acid and deionized water at a volume ratio of 1:50, and treating at 35°C for 60 seconds to remove the phosphosilicate glass layer on the front side of the fourth intermediate. Subsequently, etching is performed in a 13wt% potassium hydroxide solution at 78°C for 380 seconds. The depth of the groove structure 12 formed in step S60 of the fabrication method of the solar cell 100 in Example 3 and the lateral width of the bottom surface 121 of the groove structure 12 are basically the same as in Example 1, but the height of the side surface 122 of the groove structure 12 formed in step S60 of the fabrication method of Example 3 is different. Height of inclined plane 123 The ratio is 11:1, and the angle between the inclined plane 123 and the base 121 is... It is 32°.

[0123] Comparative Example 1 The structure of the solar cell 200 in Comparative Example 1 is as follows: Figure 8 and Figure 9As shown, the solar cell 200 of Comparative Example 1 is basically the same as the solar cell 100 of Embodiment 1 of this application. The difference between the solar cell 200 of Comparative Example 1 and the solar cell 100 of Embodiment 1 of this application is that the groove structure 22 in Comparative Example 1 only includes a bottom surface 221 that is recessed inward relative to the first surface 211 of the substrate 21, and a side surface 222 that connects the bottom surface 221 and the first surface 211 and extends obliquely relative to the thickness direction. In addition, the textured area 23 only includes the second protrusion 232 and has no first protrusion.

[0124] The preparation method of the solar cell 200 in Comparative Example 1 is basically the same as that in Example 1. The difference is that the preparation method of the solar cell 200 does not include step S30, and the temperature of the first wet treatment in step S40 is 70°C and the treatment time of the first wet treatment is 200s, so that the initial side of the initial groove formed in step S40 is a slope with an inclined profile.

[0125] Comparative Example 2 The structure of the solar cell 300 in Comparative Example 2 is as follows: Figure 10 As shown, the solar cell of Comparative Example 2 is basically the same as the solar cell 100 of Embodiment 1 of this application. The difference between the solar cell 300 of Comparative Example 2 and the solar cell 100 of Embodiment 1 of this application is that the groove structure 32 in Comparative Example 2 only includes a bottom surface 321 that is recessed inward relative to the first surface 311 of the substrate 31, and a side surface 322 that connects the bottom surface 321 and the first surface 311 and is perpendicular to the bottom surface 321. In addition, the textured area 33 only includes the second protrusion 332 and has no first protrusion.

[0126] The fabrication method of the solar cell 300 in Comparative Example 2 is basically the same as that in Example 1, except for the specific process parameters in step S30. As one embodiment, in the fabrication method of the solar cell 300 in Comparative Example 2, step S30 uses a continuous infrared laser beam for laser pre-filming treatment. The laser power is 100W, the frequency is 100kHz, and the laser marking speed is 2000mm / s. Due to the effect of the continuous infrared laser beam, the initial side surface of the initial groove formed in the first wet treatment in step S40 is perpendicular to the bottom surface.

[0127] Performance testing The solar cells of Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2 were subjected to performance comparison tests. The test conditions were as follows: using a pulsed solar simulator, under an ambient temperature of 25°C, AM1.5 atmospheric mass, and a solar irradiance of 1000 W / m², the electrical performance parameters of the cells, including open-circuit voltage (Voc), short-circuit current (Isc), fill factor (FF), and photoelectric conversion efficiency (Eta), were measured. The results are shown in Table 1. Table 1. Performance Test Comparison Table of Examples and Comparative Examples As can be seen from the above comparison, compared with Comparative Example 1 and Comparative Example 2, the open-circuit voltage, short-circuit current, fill factor and conversion efficiency of Embodiments 1 to 3 of this application are all higher.

[0128] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0129] The above embodiments merely illustrate preferred implementations of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this patent application should be determined by the appended claims.

Claims

1. A solar cell, characterized in that, include: The substrate has a first surface and a second surface disposed opposite to each other in the thickness direction; A groove structure is formed on the first surface. The groove structure includes a bottom surface recessed inward relative to the first surface, a side surface extending from the first surface toward the bottom surface along the thickness direction, and an inclined surface extending obliquely from the end of the side surface away from the first surface and connecting to the bottom surface. The side surface is perpendicular to the bottom surface, and the angle between the inclined surface and the bottom surface is 32° to 48°. In the thickness direction, the ratio of the height of the side surface to the height of the inclined surface is 2:1 to 11:

1. A velvety area is formed on the first surface. The velvety area includes a first velvety area and a second velvety area. The first velvety area is located at the edge of the groove structure, and the second velvety area is located on the side of the first velvety area away from the groove structure. The first velvety area includes a first protrusion or a first protrusion and a second protrusion, and the second velvety area includes a second protrusion. The first protrusion is located at the edge of the groove structure. The first protrusion is a truncated pyramid, and the second protrusion is a pyramid.

2. The solar cell as described in claim 1, characterized in that, The second protrusion is used to reflect light rays with a first incident angle onto the surface of the second protrusion, the first incident angle satisfying the formula: ,in, The length of the lower bottom edge of the second protrusion. The length of the upper bottom edge of the first protrusion. The angle of inclination of the side edge of the second protrusion. The angle is the first incident angle.

3. The solar cell as described in claim 1, characterized in that, The inclined plane is a plane.

4. The solar cell as described in claim 1, characterized in that, The bottom surface, the side surface, and the inclined surface of the groove structure are flat surfaces.

5. The solar cell as described in claim 1, characterized in that, The solar cell further includes a first passivation layer that covers the groove structure and the textured area.

6. The solar cell as claimed in claim 1, characterized in that, In the thickness direction, the maximum distance between the bottom surface of the groove structure and the first surface is 4μm to 5μm.

7. The solar cell according to claim 1, characterized in that, The bottom surface of the groove structure has no emitter.

8. The solar cell as claimed in claim 1, characterized in that, The bottom surface of the groove structure is provided with a tower base.

9. The solar cell as claimed in claim 8, characterized in that, The tower base includes a recessed surface that is recessed inward relative to the bottom surface of the groove structure, and a sidewall that connects the bottom surface of the groove structure and the recessed surface and extends obliquely relative to the thickness direction.

10. The solar cell as claimed in claim 9, characterized in that, The side of the sidewall that connects to the bottom surface has a side length of 17μm to 24μm; and / or, In the thickness direction, the distance between the recessed surface and the bottom surface of the groove structure is 0.32 μm to 0.58 μm; and / or, The angle between the recessed surface and the sidewall is 137° to 142°.

11. A sliced ​​battery, characterized in that, The solar cell according to any one of claims 1 to 10 is cut along the groove structure, and the cut edge of the sliced ​​cell has a stepped morphology formed by the residual groove structure.

12. A stacked battery, characterized in that, include: Top cell, which can be a perovskite cell, cadmium telluride solar cell, copper indium gallium selenide solar cell, or gallium arsenide solar cell; Intermediate connection layer; and The bottom cell is a solar cell according to any one of claims 1-10 or a sliced ​​cell according to claim 11; The top battery, the intermediate connecting layer, and the bottom battery are stacked and connected.

13. A photovoltaic module, characterized in that, This includes the solar cell according to any one of claims 1-10, the sliced ​​cell according to claim 11, or the stacked cell according to claim 12.

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