A silicon substrate, solar cell and photovoltaic module

Abstract

This utility model discloses a silicon substrate, a solar cell, and a photovoltaic module, relating to the field of solar cell technology, to solve the problem that after initial silicon wafers are treated with laser thermal cracking, excessive edge stress leads to a high breakage rate and significant performance degradation during subsequent solar cell fabrication. The silicon substrate includes a first surface and a second surface opposite to each other, and a plurality of side surfaces connecting the first and second surfaces; the side surfaces include a first side surface, wherein at least a portion of the first side surface has a first protrusion, one end of the first protrusion being close to the first surface, and the other end of the first protrusion being close to the second surface; along the direction from the first surface to the second surface, the distance between any point on the first protrusion and the first side surface first increases and then decreases.

Description

Technical Field

[0001] This utility model relates to the field of solar cell technology, and in particular to a silicon substrate, a solar cell, and a photovoltaic module. Background Technology

[0002] Solar cells, as a new type of clean energy, have received widespread attention and development in recent years. They directly convert light energy into electrical energy through the photoelectric effect or photochemical effect. The fabrication process of solar cells requires cutting a whole silicon wafer into slab solar cells. Slab solar cells typically fall into two categories: one is to directly cut silicon rods into slab wafers, and the other is to laser-heat the initial silicon wafer and then thermally crack it to divide the entire wafer into at least two slab wafers, for example, two individual wafers. These slab wafers are then used to fabricate solar cells.

[0003] In existing technologies, after laser thermal cracking of the initial silicon wafer, the excessive stress at the edge of the silicon wafer leads to a high breakage rate and a significant decrease in cell performance during subsequent solar cell fabrication. Utility Model Content

[0004] The purpose of this invention is to provide a silicon substrate, a solar cell, and a photovoltaic module to reduce the breakage rate of solar cells and improve their performance.

[0005] To achieve the above objectives, the present invention provides a silicon substrate, which includes a first surface and a second surface opposite to each other, and a plurality of side surfaces connecting the first surface and the second surface; the side surfaces include a first side surface, wherein at least a portion of the first side surface has a first protrusion, one end of the first protrusion is close to the first surface, and the other end of the first protrusion is close to the second surface; along the direction from the first surface to the second surface, the distance between any point on the first protrusion and the first side surface first increases and then decreases.

[0006] In the silicon substrate provided in this application, at least a portion of the first side surface has a first protrusion. Furthermore, along the direction from the first surface to the second surface, the distance between any point on the first protrusion and the first side surface first increases and then decreases, thereby increasing the surface area of ​​the first side surface and improving the power generation of the photovoltaic module. On the other hand, during the cell fabrication process, the first protrusion can identify the orientation of the cell, preventing an increase in the breakage rate of the cell due to incorrect orientation when the silicon substrate is placed in the basket. Simultaneously, the first protrusion on the first side surface of the silicon substrate effectively disperses the stress at the side surface, thereby reducing the probability of edge chipping or fragmentation on that side surface, and thus reducing the breakage rate of the solar cell.

[0007] In one implementation, the distance between any point on the first protrusion and the first side surface is greater than or equal to 1 μm and less than or equal to 15 μm.

[0008] With the above technical solution, the distance between any point on the first protrusion and the first side surface is within the aforementioned range. During the fabrication of solar cells, if the distance between any point on the first protrusion and the first side surface is too large, the blank area between the cells increases, affecting the power generation of the photovoltaic module. Conversely, if the distance between the first side surface and the first protrusion is too small, insufficient stress release in the edge transition region will increase the cell breakage rate. Therefore, this application controls the distance between any point on the first protrusion and the first side surface within the aforementioned range, releasing stress in the edge transition region while avoiding excessive blank area between the cells, thus preventing an impact on the power generation of the photovoltaic module.

[0009] In one implementation, the silicon substrate has multiple chamfers, each chamfer having a chamfered surface, and a first side surface connecting two adjacent chamfered surfaces; of the two chamfered surfaces, at least a portion of at least one chamfered surface has a second protrusion, and the distance between any point on the second protrusion and the chamfered surface first increases and then decreases along the direction from the first surface to the second surface.

[0010] When the above technical solution is adopted, on the one hand, the chamfer can effectively avoid excessive stress concentration at the side of the silicon substrate and effectively improve the structural strength of the silicon substrate edge. On the other hand, since at least a portion of at least one chamfered surface has a second protrusion, the surface area of ​​the chamfered surface including the second protrusion is increased, further increasing the surface area of ​​the solar cell and improving the power generation of the photovoltaic module.

[0011] In one implementation, the distance between any point on the second protrusion and the chamfered surface is greater than or equal to 2 μm and less than or equal to 25 μm.

[0012] With the above technical solution, the distance between any point on the second protrusion and the chamfered surface is within the above range. On the one hand, this avoids increasing the breakage rate of the silicon substrate during handling due to the excessive size of the second protrusion. At the same time, using such a silicon substrate to prepare solar cells results in a large blank area between solar cells, which affects the power generation of the photovoltaic module. On the other hand, this avoids the stress at the chamfer of the silicon substrate not being released in time due to the excessive size of the second protrusion, which would increase the breakage rate of the solar cells.

[0013] In one implementation, the lateral outer contours of the first protrusion and / or the second protrusion include straight lines and / or arcs.

[0014] When the above technical solution is adopted, if the lateral outer contour of the first protrusion and / or the second protrusion includes an arc, when applying force to the printing screen with a squeegee during the fabrication of some solar cells, the first protrusion and / or the second protrusion can be prevented from damaging the printing screen and affecting its lifespan.

[0015] In one implementation, the silicon substrate has at least a first extension, at least partially connected to a first surface, and the width of the first extension is less than or equal to 15 μm.

[0016] By adopting the above technical solution, and by controlling the width of the first extension within the aforementioned range, the probability of the silicon substrate scratching the basket within the width range of the first extension during the process of the silicon substrate entering the basket, as well as the probability of the silicon substrate becoming stuck or broken, are reduced. Furthermore, when a solar cell is formed using the silicon substrate of this application, the first surface of the solar cell is connected to the first extension, and the width of the first extension is less than or equal to 15 μm. Therefore, when sunlight passes through the first extension, the first extension can reflect some of the light back to the first surface, and the reflected light is then absorbed and utilized again by the silicon substrate, improving the light utilization rate of the solar cell.

[0017] In one implementation, the silicon substrate has at least a second extension, at least partially connected to a second surface, and the width of the second extension is less than or equal to 25 μm.

[0018] When the above technical solution is adopted, by controlling the width of the second extension within the aforementioned range, when a solar cell is formed using the silicon substrate of this application, the solar cell includes the aforementioned second extension. The width of the second extension is less than or equal to 25 μm, which allows it to reflect some of the sunlight to the side including the first protrusion after passing through the second extension without increasing the edge stress of the silicon substrate. The reflected light is then absorbed and reused by the silicon substrate, further improving the light utilization rate of the solar cell.

[0019] In one implementation, the silicon substrate has at least a third extension, at least partially connected to a chamfer on the first surface, and the width of the third extension is less than or equal to 25 μm.

[0020] In one implementation, the silicon substrate has at least a fourth extension, at least partially connected to a chamfer on the second surface, and the width of the fourth extension is less than or equal to 25 μm.

[0021] In one implementation, the silicon substrate includes a sputtered silicon region, in which silicon slag particles are present, the width of which is less than 0.1 μm, and / or the height of which is less than 0.1 μm.

[0022] Secondly, the present invention also provides a solar cell. The solar cell includes: an antireflection layer, a passivation layer, and the silicon substrate described in the first aspect. The antireflection layer is formed on a first surface and a second surface, and the passivation layer is formed at least on the side surface connecting the first surface and the second surface.

[0023] The beneficial effects of the solar cell provided in this application are the same as those of the silicon substrate described in the above technical solutions, and will not be repeated here.

[0024] Thirdly, this utility model also provides a photovoltaic module. The photovoltaic module includes: a plurality of solar cells as described in the second aspect, an encapsulation layer covering the surfaces of the plurality of solar cells, and a cover plate covering the surface of the encapsulation layer away from the solar cells.

[0025] The beneficial effects of the photovoltaic modules provided in this application are the same as those of the solar cells described in the above technical solutions, and will not be repeated here. Attached Figure Description

[0026] The accompanying drawings, which are included to provide a further understanding of the present invention and constitute a part of this invention, illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the present invention and do not constitute an undue limitation thereof. In the drawings:

[0027] Figure 1 This is a schematic diagram of the silicon substrate structure in an embodiment of the present invention;

[0028] Figure 2 This is a SEM image of the silicon substrate in this embodiment of the present invention, showing the first protrusion on one side.

[0029] Figure 3 This is a side view of the side portion of the silicon substrate in an embodiment of the present invention;

[0030] Figure 4 This is a side view of the chamfered portion of the silicon substrate in an embodiment of this utility model;

[0031] Figure 5 This is a SEM image of the first surface and the first extension of the silicon substrate in an embodiment of the present invention;

[0032] Figure 6 This is an embodiment of the present utility model. Figure 5 Enlarged view of region B in the middle;

[0033] Figure 7 This is a SEM image of the second surface and the second extension of the silicon substrate in an embodiment of this utility model;

[0034] Figure 8 This is an embodiment of the present utility model. Figure 7Enlarged view of region C in the middle;

[0035] Figure 9 These are SEM images of the first surface and the third extension of the silicon substrate in this embodiment of the present invention.

[0036] Figure 10 This is an embodiment of the present utility model. Figure 9 Enlarged view of region D in the middle;

[0037] Figure 11 These are SEM images of the second surface and the fourth extension of the silicon substrate in this embodiment of the present invention.

[0038] Figure 12 This is an embodiment of the present utility model. Figure 11 A magnified view of region E in the middle.

[0039] Figure label:

[0040] 1-Silicon substrate, 10-First surface, 11-Second surface, 12-Side surface, 122-First side surface, 13-First protrusion, 14-Chamfered surface, 15-Second protrusion, 16-First extension, 17-Second extension, 18-Fourth extension, 19-Silicon slag particles, 20-Third extension. Detailed Implementation

[0041] To make the technical problem to be solved, the technical solution, and the beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0042] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0043] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified. "Several" means one or more, unless otherwise explicitly specified.

[0044] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0045] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0046] In existing technologies, dry laser cutting of the initial silicon substrate is generally used when preparing slab solar cells. This cutting method relies on laser ablation, which inevitably causes damage to the surface and sides of the silicon wafer during the cutting process, affecting the fragmentation rate and photoelectric conversion efficiency of the solar cells in the subsequent photovoltaic module manufacturing process.

[0047] This application uses water-guided laser to cut an initial silicon substrate to obtain a sliced ​​silicon substrate. Since the water-guided laser generates a fine water jet by coupling high-pressure water, the laser is focused at the outlet of the nozzle. The laser propagates in the water column after reflection and performs ablation cutting. During cutting, a thin layer of water is generated on the cutting surface, and the heat is immediately cooled by the water flow. The surface and side morphology of the prepared sliced ​​silicon substrate are better, which improves the efficiency of solar cells and reduces the fragmentation rate of the sliced ​​silicon substrate.

[0048] In a first aspect, embodiments of this utility model provide a silicon substrate. See also... Figure 1 The silicon substrate 1 includes a first surface 10 and a second surface 11 opposite to each other, and a plurality of side surfaces 12 connecting the first surface 10 and the second surface 11.

[0049] In terms of conductivity type, the silicon substrate can be an intrinsically conductive substrate, an N-type conductive substrate, or a P-type conductive substrate. In terms of the photovoltaic cell fabrication process, in the embodiments of the first aspect of this application, the silicon substrate is the raw material for the photovoltaic cell, i.e., the bare silicon wafer, which is the initial silicon wafer after being squared, cut, cleaned, and inspected from a Czochralski-grown single-crystal silicon rod.

[0050] For example, when a whole silicon substrate is divided into multiple wafer silicon substrates (i.e., the silicon substrates described in this application), the side surface of the wafer silicon substrate is divided into the side surface that is not cut during the dicing process and the side surface formed after dicing. Further, in some embodiments, the first surface may be a light-facing surface and the second surface may be a backlighting surface.

[0051] Among them, see Figures 1 to 3 The side surface includes a first side surface 122, wherein at least a portion of the first side surface 122 has a first protrusion 13, one end of the first protrusion 13 is close to the first surface 10, and the other end of the first protrusion 13 is close to the second surface 11; along the direction M from the first surface 10 to the second surface 11, the distance between any point on the first protrusion 13 and the first side surface 122 first increases and then decreases. Here, the first side surface can refer to the "side surface formed after dicing a whole silicon substrate into wafers" mentioned earlier. It should be noted that the first side surface having at least a portion of the first protrusion can be understood as the entire area of ​​the first side surface having the first protrusion, or the first protrusion being located at any position in the upper, middle, or lower part of the first side surface.

[0052] It should be noted that the phrase "the distance between any point on the first protrusion and the first side surface first increases and then decreases along the direction from the first surface to the second surface" refers to the direction along the thickness of the silicon wafer. Specifically, it refers to the horizontal distance between any point on the first protrusion along the thickness of the silicon wafer and the first side surface. The statement that this horizontal distance first increases and then decreases includes the case where the size of a certain area within the first protrusion 13 remains constant. For example, Figure 3 The lateral outer contour of the first protrusion includes an arc, a straight line, and another arc. For the "straight line" portion, the distance between it and the side including the first protrusion remains unchanged. It is understood that the "straight line" portion also includes a diagonal line, and the distance should also satisfy the rule of first increasing and then decreasing.

[0053] Furthermore, one end of the first protrusion 13 is close to the first surface 10, meaning the side of the first protrusion that is close to or near the first surface, including the end connected to the first surface; correspondingly, the other end of the first protrusion 13 is close to the second surface 11, meaning the side of the first protrusion that is close to or near the second surface, including the end connected to the second surface. It can be understood that the first protrusion 13 extends along the thickness direction of the silicon substrate, connecting the first surface 10 and the second surface 11, and the distance between any point on the first protrusion 13 and the first side surface varies. The first protrusion can be an arc-shaped surface, a linear surface, or a planar structure combining arc-shaped and linear shapes.

[0054] See Figures 1 to 3In the silicon substrate 1 provided in this application, the surface area of ​​the first side surface 122, including the first protrusion 13, is increased, thereby increasing the surface area of ​​the silicon wafer and improving the power generation of the photovoltaic module. Simultaneously, the first protrusion on the side surface of the silicon substrate effectively disperses the stress on the side surface, reducing the probability of edge chipping or fragmentation, and thus reducing the breakage rate of the solar cell. Furthermore, along the direction M from the first surface 10 to the second surface 11, the distance between any point on the first protrusion 13 and the first side surface 122 first increases and then decreases, i.e., it has a gradual structure. When using this silicon substrate 1 to fabricate solar cells, the orientation of the solar cells can be identified, preventing increased breakage rates when the solar cells are placed in the basket due to incorrect orientation.

[0055] As one possible implementation, see Figure 2 and Figure 3 The distance L1 between any point on the first protrusion 13 and the first side surface 122 is greater than or equal to 1 μm and less than or equal to 15 μm. For example, the distance L1 can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm or 15 μm, etc.

[0056] See Figure 2 and Figure 3 The distance L1 between any point on the first protrusion 13 and the first side surface 122 is within the aforementioned range. During the fabrication of solar cells, if the distance between any point on the first protrusion 13 and the first side surface 122 is too large, the blank area between the cells increases, affecting the power generation of the photovoltaic module. Conversely, if the distance between any point on the first protrusion 13 and the first side surface 122 is too small, insufficient stress release in the edge transition area will also increase the cell breakage rate. Therefore, in this application, the distance between the side surface 12 (including the first protrusion 13) and the first protrusion 13 is controlled within the aforementioned range. This releases stress in the edge transition area while avoiding excessive blank area between the cells, thus preventing an impact on the power generation of the photovoltaic module.

[0057] As one possible implementation, see Figure 1 The silicon substrate 1 has multiple chamfers, each chamfer has a chamfered surface 14, and a first side surface 122 is connected between two adjacent chamfered surfaces 14.

[0058] For example, the silicon substrate can have one, two, three, or four chamfers, preferably two or four, selected according to specific needs. As one implementation, the silicon substrate is roughly rectangular, reducing the blank space when multiple solar cells are tiled together, thus increasing the power generation of the photovoltaic module. Further, the silicon substrate includes four chamfers, where the two chamfers connected to the first side are re-processed after water-guided laser slicing, and the other two chamfers are obtained after the initial silicon substrate preparation. The chamfers connected to the first side effectively disperse the stress on the sides of the silicon substrate after laser cutting, effectively improving the structural strength of the silicon substrate edges. It should be noted that... Figure 1 This is only used to show the relative positional relationship between side 12, first side 122, chamfered surface 14, first surface 10 and second surface 11, and is not used to limit the specific structure, shape and size of the silicon substrate 1 in this embodiment.

[0059] As one possible implementation, see Figure 4 In the two chamfered surfaces 14, at least a portion of at least one chamfered surface 14 has a second protrusion 15. At this time, the surface area of ​​the chamfered surface 14 with the second protrusion 15 is increased, that is, the force-bearing area of ​​the chamfered surface 14 is increased, which further increases the surface area of ​​the solar cell and increases the power generation of the photovoltaic module.

[0060] As one possible implementation, along the direction from the first surface 10 to the second surface 11, the distance between any point on the second protrusion 15 and the chamfered surface 14 first increases and then decreases.

[0061] It should be noted that the distance between any point on the second protrusion and the chamfered surface refers to the plane where the chamfer is located, i.e., the plane where the outermost edge of the chamfer is located. The distance between any point on the second protrusion 15 and the plane where the outermost edge of the chamfer is located first increases and then decreases. It should be noted that at least a portion of the chamfer on the second surface has the second protrusion 15. This can be understood as the entire area of ​​the chamfer having the second protrusion, or the second protrusion 15 being located at any position in the upper, middle, or lower part of the chamfer.

[0062] It should be noted that the phrase "the distance between any point on the second protrusion and the chamfered surface first increases and then decreases along the direction from the first surface to the second surface" refers to the direction along the thickness of the silicon wafer. Specifically, it refers to the horizontal distance between any point on the second protrusion along the thickness of the silicon wafer and the plane containing the chamfered edge. The statement that this horizontal distance first increases and then decreases includes the case where the size of a certain area within the second protrusion remains constant. For example, Figure 4The lateral outer contour of the second protrusion includes an arc, a straight line, and another arc. For the "straight line" portion, the distance between it and the side including the second protrusion remains unchanged. It is understood that the "straight line" portion also includes a diagonal line, and the distance should also satisfy the rule of first increasing and then decreasing.

[0063] It is understood that the second protrusion 15 extends along the thickness direction of the silicon substrate to connect the first surface 10 and the first side surface 122, and the distance between any point on the second protrusion 15 and the first side surface varies. The second protrusion can be an arc-shaped surface, a linear surface, or a planar structure combining arc-shaped and linear shapes.

[0064] In one alternative approach, see Figure 4 The distance L2 between any point on the second protrusion 15 and the chamfered surface 14 is greater than or equal to 2 μm and less than or equal to 25 μm. For example, the distance L2 can be 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, or 25 μm, etc.

[0065] See Figure 4 The distance L2 between any point on the second protrusion 15 and the chamfered surface is within the range mentioned above. On the one hand, this can avoid increasing the breakage rate of the silicon substrate during transportation due to the excessive size of the second protrusion 15. At the same time, using such a silicon substrate to prepare solar cells results in a large blank area between solar cells, which affects the power generation of the photovoltaic module. On the other hand, this can avoid the stress at the chamfer of the silicon substrate not being released in time due to the excessive size of the second protrusion 15, which would increase the breakage rate of the solar cells.

[0066] As one possible implementation, see Figures 2 to 4 The lateral outer contours of the first protrusion 13 and / or the second protrusion 15 include straight lines and / or arcs.

[0067] For example, only the lateral outer contour of the first protrusion 13 may include straight lines and / or curves. Alternatively, only the lateral outer contour of the second protrusion 15 may include straight lines and / or curves. Or, the lateral outer contours of both the first protrusion 13 and the second protrusion 15 may include straight lines and / or curves.

[0068] Furthermore, taking the example that only the lateral outer contour of the first protrusion 13 includes straight lines and / or arcs, the lateral outer contour of the first protrusion 13 may be composed only of straight lines; or, the lateral outer contour of the first protrusion 13 may be composed only of arcs; or, the lateral outer contour of the first protrusion 13 may include arcs and multiple straight lines.

[0069] When the lateral outer contour of the first protrusion 13 and / or the second protrusion 15 includes an arc, when applying force to the printing screen with a squeegee during the fabrication of some solar cells, the first protrusion 13 and / or the second protrusion 15 can be prevented from damaging the printing screen and affecting its lifespan.

[0070] As one possible implementation, see Figure 5 and Figure 6 The silicon substrate has at least a first extension 16, at least a portion of which is connected to the first surface 10. And / or, see [link to relevant documentation]. Figure 7 and Figure 8 The silicon substrate has at least a second extension 17, at least a portion of which is connected to the second surface.

[0071] It is understood that the first extension 16 is a portion extending outward along the edge of the first surface on the silicon substrate. The first extension 16 is connected to the first side 122 and the first surface 10, and the height of the first extension 16 is approximately the same as that of the first surface 10. The first extension 16 is higher or lower than the first surface 10, or flush with the first surface 10, and its width is the width of the outward expansion along the first surface, or the width of the extension.

[0072] When this application uses water-guided laser technology to divide a whole silicon substrate into multiple wafer silicon substrates (i.e., the silicon substrates described in this application), the first surface of the silicon substrate is selected as the incident surface of the laser. By controlling the laser cutting parameters (e.g., controlling the laser power and speed), the melting silicon regions of the laser on the first and second surfaces are controlled. The melting silicon regions are the first extension and the second extension. In some embodiments, see Figure 6 and Figure 8 The area of ​​the first extension 16 is smaller than the area of ​​the second extension 17, and the width of the first extension 16 is smaller than the width of the second extension 17. It is understood that this application employs water-guided laser technology to generate a micro-water jet beam from high-pressure water during silicon substrate dicing. The laser is focused at the nozzle exit position, and after reflection, it propagates in the water column to perform ablation cutting. During cutting, a thin layer of water is generated on the cutting surface, and the heat is immediately cooled by the water flow, exhibiting characteristics such as no thermal effect, no deformation, and no pollution.

[0073] As one possible implementation, see Figure 6The width W1 of the first extension 16 is less than or equal to 15 μm, and the width direction of the first extension 16 is perpendicular to the direction M from the first surface 10 to the second surface 11. For example, the width W1 of the first extension 16 can be 15 μm, 14 μm, 13 μm, 12 μm, 11 μm, 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2 μm, or 1 μm, etc.

[0074] See Figure 6 By controlling the width of the first extension 16 within the aforementioned range, the probability of the first extension 16 scratching the basket during the process of the silicon substrate entering the basket, as well as the probability of the silicon substrate becoming stuck or broken, are reduced. Furthermore, when the silicon substrate of this application is used to fabricate a solar cell, the substrate of the solar cell includes the aforementioned first extension 16, the width of which is less than or equal to 15 μm. Therefore, when sunlight passes through the first extension 16, the first extension 16 can reflect some of the light back to the first surface. The reflected light is then absorbed and reused by the silicon substrate, improving the light utilization rate of the solar cell.

[0075] As one possible implementation, see Figure 8 The width W2 of the second extension 17 is less than or equal to 25 μm, and the width direction of the second extension 17 is perpendicular to the direction M from the first surface 10 to the second surface 11. For example, the width W2 of the second extension 17 can be 0.1μm, 0.3μm, 0.5μm, 0.8μm, 1μm, 1.3μm, 1.5μm, 1.8μm, 2μm, 2.3μm, 2.5μm, 2.8μm, 3μm, 3.3μm, 3.5μm, 3.8μm, 4μm, 4.3μm, 4.5μm, 4.8μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 25μm, 24μm, 23μm, 22μm, 21μm, 20μm, 19μm, 18μm, 17μm, or 16μm, etc.

[0076] See Figure 8 By controlling the width of the second extension 17 within the aforementioned range, when a solar cell is formed using the silicon substrate of this application, the solar cell includes the aforementioned second extension 17. The width of the second extension 17 is less than or equal to 25 μm. This allows, without increasing the edge stress of the silicon substrate, during the fabrication of a bifacial cell, when sunlight passes through the second extension 17, the second extension 17 can reflect a portion of the light to the side including the first protrusion. The reflected light is then absorbed and reused by the silicon substrate, further improving the light utilization efficiency of the solar cell.

[0077] As one possible implementation, see Figure 9 and Figure 10 The silicon substrate 1 has at least a third extension 20, at least a portion of which is connected to a chamfer on the first surface 10; and / or, see Figure 11 and Figure 12 The silicon substrate has at least a fourth extension 18, at least a portion of which is connected to a chamfer on the second surface 11.

[0078] As described above, when using water-guided laser technology to chamfer a sliced ​​silicon substrate (i.e., the silicon substrate described in this application), the first surface of the silicon substrate is selected as the incident surface of the laser. By controlling the laser cutting parameters (e.g., controlling the laser power and speed), a molten silicon region is formed on the surface of the silicon substrate during chamfering. This molten silicon region at the chamfer is the third extension and the fourth extension. In some embodiments, the area of ​​the third extension is smaller than the area of ​​the fourth extension, and the width of the third extension is smaller than the width of the fourth extension.

[0079] As one possible implementation, see Figure 10 The width W3 of the third extension 20 is less than or equal to 25 μm, and the width direction of the third extension 20 is perpendicular to the direction from the first surface to the second surface. For example, the width W3 of the third extension can be 25 μm, 24 μm, 23 μm, 22 μm, 21 μm, 20 μm, 19 μm, 18 μm, 17 μm, 16 μm, 15 μm, 14 μm, 13 μm, 12 μm, 11 μm, 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2 μm, or 1 μm, etc.

[0080] As one possible implementation, see Figure 12 The width W4 of the fourth extension 18 is less than or equal to 25 μm, and the width direction of the fourth extension 18 is perpendicular to the direction from the first surface 10 to the second surface 11. For example, the width W4 of the fourth extension 18 can be 25 μm, 24 μm, 23 μm, 22 μm, 21 μm, 20 μm, 19 μm, 18 μm, 17 μm, 16 μm, 15 μm, 14 μm, 13 μm, 12 μm, 11 μm, 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2 μm, or 1 μm, etc.

[0081] See Figure 9In the process of segmenting a whole silicon substrate to form multiple silicon substrate slices (i.e., silicon substrate 1 described in this application) using water-guided laser technology, the first surface 10 of silicon substrate 1 is selected as the incident surface of the laser. When segmenting to form a chamfer, the chamfer position is cut twice. Through process adjustment, the chamfer is cut twice. During the second cutting of the chamfer position, the third extension and the fourth extension are modified. The modified chamfer is significantly smoother, reducing damage to the printing screen during solar cell fabrication.

[0082] As one possible implementation, see Figures 1 to 12 Compared to the first side surface formed by one cut, the chamfered surface after two cuts has a maximum distance L3 between any point on the second protrusion 15 and the chamfered surface that is greater than the first side surface that is greater than the first protrusion that is greater than the first side surface that is greater than the first side surface that is greater than the first side surface that is greater than the chamfered surface that is greater than the first side ...

[0083] During the laser process, the silicon substrate is vaporized and melted under the action of the laser, and some of the melted silicon particles are sputtered to the nearby area to form a sputtered silicon region.

[0084] In some embodiments, see Figure 8 and Figure 12 The sputtered silicon region includes spaced silicon slag particles 19; at least some of the silicon slag particles have a width of less than 0.1 μm and a height of less than 0.1 μm. For example, the width or height of the silicon slag particles can be 0.09 μm, 0.08 μm, 0.07 μm, 0.06 μm, 0.05 μm, or 0.04 μm, etc. In this embodiment of the invention, the height and width of the silicon slag particles are obtained by optical microscopy or scanning electron microscopy (SEM).

[0085] In this embodiment, silicon slag particles are inevitably introduced during laser cutting. In this embodiment, when the width and height of the silicon slag particles are within the aforementioned range, they are easier to clean and remove during the manufacture of some solar cells, reducing the impact of the silicon slag particles on the performance of the solar cells. Furthermore, even if silicon slag particles remain on the first surface of the solar cells manufactured later, the risk of the printing screen being damaged due to the presence of silicon slag particles and the impact of the silicon slag particles on the performance of the solar cells can be reduced.

[0086] In this application, under the action of water-guided laser water flow, silicon slag particles are carried away by the water flow. Except for some remaining on the first and second surfaces, the number of silicon slag particles on the second surface is greater than that on the first surface, and the height of the silicon slag particles on the second surface is also greater than that on the first surface. As a result, the number and height of silicon slag particles on the entire silicon wafer surface are less than those in other laser processing methods, which improves the uniformity of the film layer when preparing solar cells on the silicon substrate surface and improves the photoelectric conversion efficiency of solar cells.

[0087] Secondly, this utility model embodiment also provides a solar cell. This utility model embodiment does not specifically limit the type of solar cell; it can be any type of solar cell capable of converting light energy into electrical energy. For example, the solar cell provided in this utility model embodiment can be a solar cell including only a tunneling passivation contact structure, a solar cell including only a heterostructure, or a hybrid solar cell including both a tunneling passivation contact structure and a heterostructure, etc. Alternatively, the solar cell provided in this utility model embodiment can be a bifacial solar cell or a back-contact solar cell. For example, the solar cell provided in this utility model embodiment can be a PERC cell, a TOPcon cell, a TBC cell, or a heterojunction solar cell.

[0088] In the second aspect of this invention, the silicon substrate is a silicon substrate prepared from a raw wafer through a passivation layer process. It can be a silicon substrate immediately after the passivation layer is prepared, or a silicon substrate after the passivation layer is prepared and the battery is printed. This invention does not limit the stage of the silicon substrate after the passivation layer preparation. It is understood that the silicon substrate provided in the second aspect of this invention and the silicon substrate provided in the first aspect of this invention have the same original structural framework, except for the different preparation stages.

[0089] The solar cell includes an antireflection layer, a passivation layer, and the silicon substrate described in the first aspect. The antireflection layer is formed on a first surface and a second surface, and the passivation layer is formed at least on the side surface connecting the first surface and the second surface.

[0090] The beneficial effects of the solar cell provided in this application are the same as those of the silicon substrate described in the above technical solutions, and will not be repeated here.

[0091] As one possible implementation, the passivation layer includes at least one of a silicon nitride layer, an aluminum oxide layer, or a silicon nitride layer.

[0092] As one possible implementation, the passivation layer can be a single-layer film, such as a single layer of silicon nitride; or it can be a stack of multiple films, such as a stack of aluminum oxide and silicon nitride layers, or a stack of silicon nitride alone.

[0093] Thirdly, this utility model embodiment also provides a photovoltaic module. The photovoltaic module includes: a plurality of solar cells as described in the second aspect, an encapsulation layer covering the surfaces of the plurality of solar cells, and a cover plate covering the surface of the encapsulation layer away from the solar cells.

[0094] The beneficial effects of the photovoltaic modules provided in this application are the same as those of the solar cells described in the above technical solutions, and will not be repeated here.

[0095] The following describes the structure and effects of the silicon substrate of the first aspect and the solar cell of the second aspect of this utility model using several specific embodiments. It should be noted that this is only for explaining the utility model and does not limit the utility model.

[0096] Example 1

[0097] 10,000 N-type silicon substrates, each 110*182mm in length and width and 130μm in thickness, were selected after laser cutting. Each silicon substrate includes a first surface and a second surface opposite to each other, and multiple side surfaces connecting the first and second surfaces. Each side surface includes a first side surface, at least a portion of which has a first protrusion. One end of the first protrusion is close to the first surface, and the other end is close to the second surface. Along the direction from the first surface to the second surface, the distance between any point on the first protrusion and the first side surface first increases and then decreases. The distance between any point on the first protrusion and the first side surface is greater than or equal to 1μm and less than or equal to 6μm. The silicon substrate has multiple chamfers, each chamfer having a chamfered surface. The first side surface connects two adjacent chamfered surfaces. At least one of the two chamfered surfaces has at least a second protrusion. Along the direction from the first surface to the second surface, the distance between any point on the second protrusion and the chamfered surface first increases and then decreases. The distance between any point on the second protrusion and the chamfered surface is greater than or equal to 2μm and less than or equal to 9μm.

[0098] Solar cells were fabricated from the aforementioned 10,000 silicon substrates, and the substrate breakage rate, cell manufacturing process breakage rate, and cell efficiency were statistically analyzed. The substrate breakage rate was calculated as follows: substrate breakage rate (from unpacking the original silicon substrates into the loading basket) = (Number of original silicon substrates - Number of silicon substrates in the loading basket) / (Number of original silicon substrates) × 100%; cell manufacturing process breakage rate was calculated as the breakage rate of the entire cell manufacturing process = (Number of original silicon substrates - Number of final cells) / (Number of original silicon substrates) × 100%; and cell efficiency was the average efficiency value of the entire batch of cells obtained using a solar cell efficiency tester.

[0099] Example 2

[0100] The difference from Example 1 is as follows:

[0101] The distance between any point on the first protrusion and the first side surface is greater than or equal to 5 μm and less than or equal to 12 μm, and the distance between any point on the second protrusion and the chamfered surface is greater than or equal to 4 μm and less than or equal to 15 μm.

[0102] Example 3

[0103] The difference from Example 2 is that:

[0104] The distance between any point on the first protrusion and the first side surface is greater than or equal to 8 μm and less than or equal to 15 μm, and the distance between any point on the second protrusion and the chamfered surface is greater than or equal to 10 μm and less than or equal to 25 μm.

[0105] Comparative Example 1

[0106] The difference from Example 1 is that:

[0107] The distance between any point on the first protrusion and the first side surface is greater than 15μm and less than or equal to 25μm, and the distance between any point on the second protrusion and the chamfered surface is greater than 25μm and less than or equal to 45μm.

[0108] Comparative Example 2

[0109] The difference from Example 2 is that:

[0110] The distance between any point on the first protrusion and the first side surface is greater than or equal to 0.1 μm and less than or equal to 0.9 μm, and the distance between any point on the second protrusion and the chamfered surface is greater than or equal to 0.1 μm and less than or equal to 1.5 μm.

[0111] Table 1. Fragmentation rate and battery efficiency data for Examples 1-3 and Comparative Examples 1-2

[0112] project Silicon substrate process breakage rate Battery manufacturing process breakage rate Battery efficiency Example 1 0.4％ 0.5％ 26.89％ Example 2 0.6％ 0.8％ 26.86％ Example 3 0.9％ 1.2％ 26.85％ Comparative Example 1 5％ 8％ 26.6％ Comparative Example 2 3％ 6％ 26.7％

[0113] As can be seen from the test data of the above embodiments, by controlling the distance between any point on the first protrusion and the first side surface and the distance between any point on the second protrusion and the chamfered surface within the ideal range, the breakage rate of the silicon substrate and the breakage rate in the battery manufacturing process can be guaranteed, and the battery efficiency of the photovoltaic cell can be further improved.

[0114] In Comparative Example 1, the distance between any point on the first protrusion and the first side surface is too large, and the distance between any point on the second protrusion and the chamfered surface is too large. When photovoltaic cells are prepared using a silicon substrate with the above parameters, compared with a silicon substrate where the distance between any point on the first protrusion and the first side surface and the distance between any point on the second protrusion and the chamfered surface are controlled within the ideal range, the breakage rate in the cell manufacturing process increases, and the photovoltaic cell efficiency is greatly reduced.

[0115] In Comparative Example 2, the distance between any point on the first protrusion and the first side surface is too small, and the distance between any point on the second protrusion and the chamfered surface is too small. When photovoltaic cells are prepared using a silicon substrate with the above parameters, compared with a silicon substrate where the distance between any point on the first protrusion and the first side surface and the distance between any point on the second protrusion and the chamfered surface are controlled within the ideal range, the breakage rate in the cell manufacturing process increases, and the photovoltaic cell efficiency is greatly reduced.

[0116] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0117] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A silicon substrate, characterized in that, The silicon substrate includes a first surface and a second surface opposite to each other, and a plurality of side surfaces connecting the first surface and the second surface; the side surfaces include a first side surface, wherein at least a portion of the first side surface has a first protrusion, one end of the first protrusion is close to the first surface, and the other end of the first protrusion is close to the second surface; along the direction from the first surface to the second surface, the distance between any point on the first protrusion and the first side surface first increases and then decreases.

2. The silicon substrate according to claim 1, characterized in that, The distance between any point on the first protrusion and the first side surface is greater than or equal to 1 μm and less than or equal to 15 μm.

3. The silicon substrate according to claim 1, characterized in that, The silicon substrate has multiple chamfers, each chamfer having a chamfered surface, the first side being connected between two adjacent chamfered surfaces; of the two chamfered surfaces, at least a portion of at least one chamfered surface has a second protrusion, and along the direction from the first surface to the second surface, the distance between any point on the second protrusion and the chamfered surface first increases and then decreases.

4. The silicon substrate according to claim 3, characterized in that, The distance between any point on the second protrusion and the chamfered surface is greater than or equal to 2 μm and less than or equal to 25 μm.

5. The silicon substrate according to claim 3, characterized in that, The lateral outer contours of the first protrusion and / or the second protrusion include straight lines and / or arcs.

6. The silicon substrate according to claim 1 or 2, characterized in that, The silicon substrate has at least a first extension, at least a portion of which is connected to the first surface, and the width of the first extension is less than or equal to 15 μm. And / or, the silicon substrate has at least a second extension, at least partially connected to the second surface, the width of the second extension being less than or equal to 25 μm.

7. The silicon substrate according to claim 3, characterized in that, The silicon substrate has at least a third extension, at least a portion of which is connected to a chamfer on the first surface, and the width of the third extension is less than or equal to 25 μm. And / or, the silicon substrate has at least a fourth extension, at least a portion of which is connected to a chamfer on the second surface, and the width of the fourth extension is less than or equal to 25 μm.

8. The silicon substrate according to claim 3, characterized in that, The silicon substrate includes a sputtered silicon region, in which silicon slag particles are present, the width of which is less than 0.1 μm, and / or the height of which is less than 0.1 μm.

9. A solar cell, characterized in that, include: The silicon substrate according to any one of claims 1 to 8; An anti-reflection layer is formed on the first surface and the second surface; A passivation layer is formed, at least partially, on the side surface connecting the first and second surfaces.

10. A photovoltaic module, characterized in that, include: Multiple solar cells as described in claim 9; An encapsulation layer covers the surfaces of the plurality of solar cells; A cover plate that covers the surface of the encapsulation layer away from the solar cell.

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