A solar cell, a photovoltaic module, and a method for manufacturing a solar cell

Abstract

The application discloses a solar cell, a photovoltaic module and a preparation method of the solar cell, and relates to the technical field of solar cells, and aims to solve the problem that the color difference between two areas with and without a passivation layer in the light-receiving surface (or the back light-receiving surface) of a split solar cell is relatively large, which leads to a relatively large difference in vision and low aesthetic degree. The solar cell comprises opposite first and second surfaces and a side surface connecting the first and second surfaces; and the side surface comprises a cutting surface. The solar cell comprises: a first passivation layer formed on the cutting surface; and a plurality of second passivation layers which are spaced apart and formed on an edge area adjacent to the cutting surface in the first and / or second surface.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and more particularly to a solar cell, a photovoltaic module, and a method for preparing a solar cell. Background Technology

[0002] A solar cell is a device that utilizes solar energy, directly converting light energy into electrical energy through the photoelectric effect or photochemical effect. Solar cells include slab solar cells. Currently, the production of slab solar cells typically involves cutting a solar cell that has already formed multiple film layers into at least two slab solar cells, such as two half-cells. Then, a passivation layer is formed on the cut surfaces of the slab solar cells.

[0003] During this process, a continuously distributed passivation layer is also deposited around the edge areas of the light-facing and back-facing sides of the slab solar cell, adjacent to the cut surface. At this time, the two areas with and without passivation layers on the light-facing (or back-facing) side of the slab solar cell have a significant color difference, resulting in a large visual difference in the solar cell, low aesthetics, and potentially affecting poor connection of the module's solder ribbons. Summary of the Invention

[0004] The purpose of this invention is to provide a solar cell, a photovoltaic module, and a method for manufacturing a solar cell, which reduces visual differences in solar cells, improves the aesthetics of solar cells, and eliminates poor connections such as solder strips.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a solar cell. The solar cell includes opposing first and second surfaces, and a side surface connecting the first and second surfaces; the side surface includes a cut surface. The solar cell includes: a first passivation layer formed on the cut surface; and a plurality of spaced-apart second passivation layers formed on an edge region adjacent to the cut surface in the first and / or second surfaces.

[0006] In the solar cell provided by this invention, multiple second passivation layers are spaced apart on the edge region, meaning the second passivation layers formed on the first surface and / or the second surface are discontinuous. Compared to the continuous passivation layers formed on the edge regions adjacent to the cut surfaces of the light-facing and back-facing surfaces of sectional solar cells in the prior art, the proportion of the second passivation layers formed on the first surface and / or the second surface is reduced when the areas of the edge regions involved in this invention and the prior art are completely or substantially equal, or when the edge regions in this invention are smaller than those in the prior art. Based on this, the first surface and / or the second surface appear to have a more uniform color, reducing color differences between different areas of the first surface and / or the second surface compared to solar cells in the prior art, thus reducing visual differences and improving the aesthetics of the solar cell. Furthermore, the spaced-apart multiple second passivation layers in this invention can also reduce the influence on the surface refractive index of the first surface and / or the second surface, and increase PL (photoluminescence) brightness, thereby improving the cell efficiency of the solar cell. Furthermore, electrode structures are formed on the first and / or second surfaces of the solar cell. In the prior art, electrode structures closer to the edge of the solar cell are easily covered by continuously distributed second passivation layers, affecting the connection between connectors such as solder ribbons and the electrode structures, thus affecting the quality of the final module. However, since the multiple second passivation layers in this invention are spaced apart, the probability of electrode structures near the edge of the solar cell being completely covered can be reduced or eliminated, thereby improving the connection stability between connectors such as solder ribbons and the electrode structures, and thus improving the quality of the final photovoltaic module. In addition, since a first passivation layer is formed on the cut surface, the first passivation layer can passivate the cut surface, reduce the recombination rate of photogenerated carriers at the cut surface, and improve the photoelectric conversion efficiency of the solar cell.

[0007] In one implementation, multiple second passivation layers are distributed in an island-like pattern in the edge region.

[0008] With the above technical solution, the multiple island-shaped distribution of the second passivation layers facilitates the reflection of more light through the sidewalls of the second passivation layers onto the textured structure between the two spaced second passivation layers, thereby improving the light trapping effect of the first and / or second surfaces of the solar cell, increasing the light absorption rate, and thus improving the utilization rate of light on the first and / or second surfaces of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell.

[0009] In one implementation, along the thickness direction of the solar cell, the planar shape of the second passivation layer is a closed figure composed of triangles, quadrilaterals, pentagons, or arcs and line segments.

[0010] In one implementation, the second passivation layer includes an end near the center region of the first surface and / or the second surface, and the end boundaries of the plurality of second passivation layers are wavy or serrated.

[0011] By employing the above technical solution, compared to having straight-line end boundaries for multiple second passivation layers, the proportion of the second passivation layers in the first and / or second surfaces can be further reduced. Based on this, the visual differences of the solar cell can be further reduced, improving its aesthetics.

[0012] In one implementation, the side surface also includes a non-cutting side surface adjacent to the cutting surface, and a plurality of spaced second passivation layers are also formed on the edge region of the non-cutting side surface adjacent to the cutting surface.

[0013] By employing the above technical solution, compared to the existing technology which forms a continuously distributed passivation layer on the non-cut side surface, the multiple spaced second passivation layers in this invention can further reduce the impact on the surface refractive index of the non-cut side surface, thereby improving the cell efficiency of the solar cell. Furthermore, the multiple spaced second passivation layers facilitate the reflection of more light through their sidewalls onto the textured structure between the two spaced second passivation layers, thereby enhancing the light-trapping effect of the non-cut side surface of the solar cell, increasing the light absorption rate, and thus improving the utilization rate of light on the non-cut side surface of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell.

[0014] In one implementation, the plurality of second passivation layers includes at least one second passivation layer that is spaced apart from the first passivation layer.

[0015] In one implementation, the width of the second passivation layer on the first surface is greater than or equal to 0 mm and less than or equal to 1 mm in the vertical direction from the edge region of the first surface to the center region of the first surface; and / or, the width of the second passivation layer on the second surface is greater than or equal to 0 mm and less than or equal to 1 mm in the vertical direction from the edge region of the second surface to the center region of the second surface.

[0016] By adopting the above technical solution, not only can the aesthetics, surface refractive index, and PL brightness of solar cells be significantly improved, thereby increasing the cell efficiency of solar cells; at the same time, it will not affect the connection between connectors such as solder ribbons and electrode structures, thereby improving the quality of the final module.

[0017] In one implementation, the thickness of the first passivation layer is greater than the thickness of the second passivation layer.

[0018] By adopting the above technical solution, the passivation effect of the first passivation layer on the cut surface can be improved, further reducing the recombination rate of photogenerated carriers at the cut surface and improving the photoelectric conversion efficiency of the solar cell. Furthermore, since the thickness of the second passivation layer is relatively thin, it can not only reduce the influence of the second passivation layer on the surface refractive index and improve the cell efficiency of the solar cell, but also reduce the visual difference of the solar cell and improve its aesthetics.

[0019] In one implementation, the thickness of the first passivation layer is greater than or equal to 10 nm and less than or equal to 300 nm.

[0020] Secondly, the present invention also provides a photovoltaic module. The photovoltaic module includes a cell string and an encapsulation layer. The cell string is formed by connecting multiple solar cells as described in the above technical solution, and the encapsulation layer is used to cover the surface of the cell string.

[0021] Compared with the prior art, the photovoltaic module provided by the present invention has the same beneficial effects as the solar cell described in the above technical solution, and will not be repeated here.

[0022] Thirdly, the present invention also provides a method for preparing a solar cell. The method for preparing the solar cell includes:

[0023] Provide a semiconductor substrate;

[0024] A semiconductor substrate is divided into at least two sliced ​​semiconductor substrates; each sliced ​​semiconductor substrate includes a first surface and a second surface opposite to each other, and a side surface connecting the first surface and the second surface; the side surface includes a cut surface.

[0025] A first passivation layer is formed on the cut surface;

[0026] Multiple spaced second passivation layers are formed on the edge regions adjacent to the cutting surface in the first and / or second surfaces.

[0027] Compared with the prior art, the beneficial effects of the solar cell preparation method provided by the present invention are the same as those of the solar cells described in the above technical solutions, and will not be repeated here.

[0028] In one implementation, the temperature at which the first passivation layer and the second passivation layer are formed is less than or equal to 100°C.

[0029] For ease of subsequent description, the first passivation layer and the second passivation layer will be collectively referred to as passivation layers. Compared to the high-temperature process used in the prior art to form the passivation layer, the present invention forms the passivation layer at a lower temperature than in the prior art. This reduces or avoids damage to the film layer already formed on the semiconductor substrate during the passivation layer formation process. For example, it avoids damaging the surface protective film already formed on the semiconductor substrate, thus preventing the release of organic matter and avoiding damage to the edge passivation effect, thereby ensuring the yield and module power of the solar cell.

[0030] In one implementation, the method for fabricating a solar cell further includes heat treatment of the first passivation layer and / or the second passivation layer. Attached Figure Description

[0031] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0032] Figure 1 This is a schematic diagram of the distribution of the passivation layer on the light-facing surface in the prior art;

[0033] Figure 2 This is a photograph of five stacked solar cells in the prior art.

[0034] Figure 3 This is a schematic diagram of the structure of the solar cell in an embodiment of the present invention. Figure 1 ;

[0035] Figure 4 As described in the embodiments of the present invention Figure 3 A schematic diagram of the structure of the first surface;

[0036] Figure 5 This is a schematic diagram of the structure of the solar cell in an embodiment of the present invention. Figure 2 ;

[0037] Figure 6 This is a schematic diagram illustrating the relationship between light and solar cells in an embodiment of the present invention;

[0038] Figure 7 This is a SEM image of the solar cell in an embodiment of the present invention.

[0039] Figure label:

[0040] 1-First surface, 2-First passivation layer, 3-Second passivation layer, 4-Non-cutting side surface, 5-Light-facing surface, 6-Passivation layer, 7-Normal area. Detailed Implementation

[0041] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention 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 for explaining the present invention and are not intended to limit the present invention.

[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 invention, "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 invention, 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 invention 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 invention.

[0045] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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 invention according to the specific circumstances.

[0046] The use of half-cell solar cells in photovoltaic (PV) modules dates back decades, when solar energy technology was not yet mature, and the production cost of full-cell PV modules (i.e., PV modules made with a single solar cell) was high. Therefore, in order to reduce costs and improve the efficiency of PV modules, half-cell PV modules (i.e., PV modules made with half-cell solar cells) were introduced and gradually gained widespread use.

[0047] Half-cell photovoltaic (PV) modules are made by cutting standard-sized silicon wafers into two halves using a specific method, and then processing each half into a PV module. This makes full use of the silicon wafer raw material and reduces material waste. In addition, half-cell PV modules have better photoelectric conversion efficiency and a lower temperature coefficient than full-cell PV modules, thus providing higher power generation under partial sunlight conditions.

[0048] With the continuous advancement of solar energy technology, the production cost of half-cell photovoltaic modules has gradually decreased, while their performance and reliability have been further improved. Therefore, half-cell photovoltaic modules have become the preferred choice for many solar energy projects, especially in the construction of large-scale photovoltaic power plants.

[0049] Cutting a full-cell solar cell in half reduces current density and resistance loss, thereby improving the power generation efficiency and reliability of photovoltaic modules. Furthermore, half-cell photovoltaic modules offer better shading resistance, maintaining high power generation efficiency even under shading conditions. In addition, half-cell technology helps reduce connection complexity and improve production efficiency during manufacturing.

[0050] However, the manufacturing of half-cell photovoltaic modules also generates some derivative problems. Specifically, the current conventional method is to directly laser-cut a whole solar cell that has already formed multiple film layers into at least two slab solar cells, such as two half-cells. Then, a passivation layer is formed on the cut surfaces of the slab solar cells.

[0051] See Figure 1 and Figure 2 During this process, a continuously distributed passivation layer 6 will also be deposited around the edge regions of the light-facing side 5 and the back-facing side of the segmented solar cell that are adjacent to the cut surface (see details). Figure 2 (The "white line" in the image). At this point, the two areas with and without passivation layer 6 on the light-facing side 5 (or back-facing side) of the segmented solar cell show a significant color difference (specifically, the normal area 7 without a continuous passivation layer 6 is light blue, while the area with a continuous passivation layer 6 is white). The comparison shows that the solar cell has a significant visual difference and low aesthetic appeal.

[0052] To address the aforementioned technical problems, in a first aspect, embodiments of the present invention provide a solar cell. See also... Figure 3 and Figure 4The solar cell includes a first surface 1 and a second surface opposite to each other, and a side surface connecting the first surface 1 and the second surface, the side surface including a cut surface. The solar cell includes: a first passivation layer 2 formed on the cut surface, and a plurality of spaced-apart second passivation layers 3 formed on edge regions adjacent to the cut surface in the first surface 1 and / or the second surface. It should be understood that the edge regions of both the first surface 1 and the second surface have a boundary line with the cut surface.

[0053] See Figures 1 to 4 In the solar cell provided by this embodiment of the invention, multiple second passivation layers 3 are spaced apart on the edge region, that is, the second passivation layers 3 formed on the first surface 1 and / or the second surface are discontinuous. Compared with the continuous distribution of passivation layers 6 formed on the edge region adjacent to the cut surface in the light-facing surface 5 and the back-facing surface of the segmented solar cell in the prior art, when the area of ​​the edge region involved in the embodiments of the present invention and the prior art is completely equal or substantially equal, or when the edge region in the present invention is smaller than the edge region in the prior art, the proportion of the second passivation layer 3 formed in the first surface 1 and / or the second surface is reduced. Based on this, the first surface 1 and / or the second surface appears to have a more uniform color, reducing the color difference between different areas of the first surface 1 and / or the second surface compared with the solar cells in the prior art, reducing the visual difference of the solar cell, and improving the aesthetics of the solar cell. Furthermore, the multiple second passivation layers 3 spaced apart in the present invention can also reduce the influence on the surface refractive index of the first surface 1 and / or the second surface, and increase the PL brightness, thereby improving the cell efficiency of the solar cell. Furthermore, electrode structures are formed on the first surface 1 and / or the second surface of the solar cell. In the prior art, the electrode structures closer to the edge of the solar cell are covered by continuously distributed second passivation layers 3, which may affect the connection between the connectors such as solder ribbons and the electrode structures of the solar cell. However, since the multiple second passivation layers 3 in the embodiments of the present invention are spaced apart, the probability of the electrode structures near the edge of the solar cell being completely covered can be reduced or eliminated, thereby improving the connection stability between the connectors such as solder ribbons and the electrode structures, and thus improving the quality of the final photovoltaic module. In addition, since a first passivation layer 2 is formed on the cut surface, the first passivation layer 2 can passivate the cut surface, reduce the recombination rate of photogenerated carriers at the cut surface, and improve the photoelectric conversion efficiency of the solar cell. It can be understood that the multiple spaced second passivation layers in this application are not interconnected to form a whole in the edge regions of the first surface and / or the second surface, but there are no interconnected parts in the edge regions of the first surface and / or the second surface. Specifically, see Figure 3 and Figure 4There is no connection between any two adjacent spaced second passivation layers, and any two adjacent spaced second passivation layers are in a completely separated state.

[0054] As one possible implementation, the solar cell described above may include a semiconductor substrate, a doped layer formed on a first or second surface of the semiconductor substrate, and a first passivation layer and a second passivation layer formed on the semiconductor substrate and the doped layer. Of course, the solar cell may also include other film layer structures, which are not specifically limited here.

[0055] In one alternative embodiment, the semiconductor substrate can be a substrate made of semiconductor materials such as silicon, germanium-silicon, or germanium. In terms of conductivity type, the semiconductor substrate can be an intrinsically conductive substrate, an N-type conductive substrate, or a P-type conductive substrate. Preferably, the semiconductor substrate is an N-type or P-type conductive substrate. Compared to an intrinsically conductive substrate, an N-type or P-type conductive substrate has higher conductivity, which helps to reduce the series resistance of the solar cell and improve its efficiency. Structurally, the first surface of the solar cell can be textured to improve the light-trapping effect of the solar cell's light-facing surface, thereby improving the solar cell's light utilization rate. Of course, the first surface of the solar cell can also be a flat, polished surface. As for the second surface of the solar cell, it can be polished or textured; no specific limitation is made here.

[0056] In terms of materials, the doped layer can be any semiconductor material such as silicon, germanium-silicon, or germanium. In terms of the arrangement of matter, the crystal phase of the doped layer can be amorphous, microcrystalline, nanocrystalline, single-crystal, or polycrystalline. For example, the doped layer can be composed of one or more of polycrystalline silicon, amorphous silicon, microcrystalline silicon, and nanocrystalline silicon.

[0057] In terms of the number of layers, the first passivation layer can be a single-layer structure or a stacked structure. The second passivation layer can also be a single-layer structure or a stacked structure. In terms of materials, the materials of the first or second passivation layer can include one or more of silicon oxide, aluminum oxide, titanium oxide, hafnium dioxide, gallium oxide, tantalum pentoxide, niobium pentoxide, silicon nitride, silicon carbonitride, aluminum nitride, titanium nitride, titanium carbonitride, and amorphous silicon. The materials of the first and second passivation layers can be the same or different. In the embodiments of the present invention, both the first and second passivation layers are stacked structures. For example, the material of the first passivation layer includes an aluminum oxide passivation layer (or a silicon dioxide passivation layer) formed on the cut surface, and a silicon nitride passivation layer formed on the aluminum oxide passivation layer (or silicon dioxide passivation layer). The second passivation layer is similar and will not be described in detail here.

[0058] In terms of distribution, see Figures 3 to 7 Multiple second passivation layers 3 are distributed in an island-like pattern in the edge region. In this case, the multiple island-like distribution of the second passivation layers 3 facilitates the reflection of more light through the sidewalls of the second passivation layers 3 onto the textured structure between the two spaced second passivation layers 3, thereby improving the light-trapping effect of the first surface 1 and / or the second surface of the solar cell, increasing the light absorption rate, and thus improving the utilization rate of light on the first surface 1 and / or the second surface of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell.

[0059] From a shape perspective, see Figures 3 to 7 Along the thickness direction of the solar cell, the planar shape of the second passivation layer 3 is a closed shape composed of triangles, quadrilaterals, pentagons, or arcs and line segments. In this embodiment of the invention, the planar shape of the second passivation layer 3 is an irregular polygon.

[0060] As one possible implementation, see Figures 3 to 5 The second passivation layer 3 includes an end near the center region of the first surface 1 and / or the second surface, and the end boundaries of the plurality of second passivation layers 3 are wavy or serrated.

[0061] For example, the second passivation layer 3 located on the first surface 1 includes an end near the central region of the first surface 1, and the end boundaries of all second passivation layers 3 are wavy or serrated. And / or, the second passivation layer 3 located on the second surface includes an end near the central region of the second surface, and the end boundaries of all second passivation layers 3 are wavy or serrated. Alternatively, the second passivation layer 3 located on the first surface 1 includes an end near the central region of the first surface 1, and the end boundaries of two or more adjacent second passivation layers 3 are wavy or serrated. And / or, the second passivation layer 3 located on the second surface includes an end near the central region of the second surface, and the end boundaries of two or more adjacent second passivation layers 3 are wavy or serrated.

[0062] By employing the above technical solution, compared to having straight-line end boundaries for multiple second passivation layers, the proportion of the second passivation layers in the first and / or second surfaces can be further reduced. Based on this, the visual differences of the solar cell can be further reduced, improving its aesthetics.

[0063] As one possible implementation, see Figure 6 The side surface also includes a non-cutting side surface 4 adjacent to the cutting surface, and multiple spaced second passivation layers 3 are also formed on the edge region of the non-cutting side surface 4 adjacent to the cutting surface.

[0064] With the above technical solution, compared to the existing technology of forming a continuously distributed passivation layer on the non-cut side surface, the spaced-apart second passivation layers 3 in this embodiment of the invention can further reduce the influence on the surface refractive index of the non-cut side surface 4, thereby improving the cell efficiency of the solar cell. Furthermore, the spaced-apart second passivation layers 3 facilitate the reflection of more light through their sidewalls onto the textured structure between the two spaced-apart second passivation layers 3, thereby improving the light-trapping effect of the non-cut side surface 4 of the solar cell, increasing the light absorption rate, and thus improving the utilization rate of light on the non-cut side surface 4 of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell.

[0065] Based on the preceding description, multiple second passivation layers are distributed in an island-like pattern in the edge region of the non-cutting side surface adjacent to the cutting surface, and the planar shape of the second passivation layers is an irregular polygon.

[0066] As described above, a solar cell includes a first surface 1 and a second surface. When the first surface 1 is the light-facing surface and the second surface is the backlighting surface, the incident angle of the first surface 1 of the solar cell is made as close to 0 as possible to better utilize light. However, this results in a large incident angle of the incident light on the side surface, for example, close to 90°, leading to low light utilization on the side surface. In this embodiment of the invention, the second passivation layer 3 has an irregular polygonal shape and is distributed as isolated islands. This is beneficial for improving the light utilization of the non-cut side surface 4 adjacent to the cut surface in the solar cell. For example, see attached... Figure 6 After incident light rays L1 and L2 pass through the second passivation layer 3, more light can be reflected onto the textured structure between the two spaced second passivation layers 3, thereby improving the utilization rate of light on the non-cut side surface 4 adjacent to the cut surface in the solar cell.

[0067] In one alternative embodiment, the area of ​​the edge region in this application is equal to the area of ​​the edge region in the prior art. In this application, the ratio of the total area of ​​the second passivation layer to the area of ​​the edge region is less than or equal to 1%. For example, the ratio can be 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1%, 0.05%, etc.

[0068] Compared to existing technologies, the area of ​​the second passivation layer formed on the first surface and / or the second surface and / or the non-cut side surface adjacent to the cut surface in the embodiments of the present invention is greatly reduced. This not only significantly improves the aesthetics, surface refractive index, and PL brightness of the solar cell, thereby improving the cell efficiency of the solar cell, but also does not affect the connection between the connectors such as solder ribbons and the electrode structure, thereby improving the quality of the final formed module.

[0069] As one possible implementation, see Figure 5 The plurality of second passivation layers 3 include at least one second passivation layer 3 distributed at intervals from the first passivation layer 2, and the spacing between the first passivation layer 2 and the second passivation layer 3 is not specifically limited here.

[0070] As one possible implementation, see Figure 3 and Figure 5 The width W of the second passivation layer 3 on the first surface 1 is greater than or equal to 0 mm and less than or equal to 1 mm in the vertical direction from the edge region of the first surface 1 to the center region of the first surface 1. For example, the width W of the second passivation layer 3 can be 0 mm, 0.05 mm, 0.1 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.8 mm, 0.85 mm, 0.9 mm, or 1 mm, etc.

[0071] Preferably, the width W of the second passivation layer 3 on the first surface 1 is greater than or equal to 0 mm and less than or equal to 20 μm in the vertical direction from the edge region to the center region of the first surface 1. For example, the width W of the second passivation layer 3 can be 0 mm, 1 μm, 3 μm, 5 μm, 8 μm, 10 μm, 12 μm, 13 μm, 15 μm, 17 μm, 18 μm, or 20 μm, etc. In this case, not only can color differences in different regions of the first surface be completely avoided, thus further reducing the visual differences of the solar cell, but also the probability of the electrode structure near the edge of the solar cell in the first surface being completely covered can be eliminated, ensuring that the connection between the connectors such as solder ribbons and the electrode structure is not affected, thereby improving the quality of the final formed module.

[0072] For example, see Figure 7 The width W of the second passivation layer 3 on the first surface 1 is 3.473 μm in the vertical direction from the edge region of the first surface 1 to the center region of the first surface 1.

[0073] The width of the second passivation layer on the second surface is greater than or equal to 0 mm and less than or equal to 1 mm in the vertical direction from the edge region to the center region of the second surface. For example, the width of the second passivation layer can be 0 mm, 0.05 mm, 0.1 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.8 mm, 0.85 mm, 0.9 mm, or 1 mm, etc.

[0074] Preferably, the width of the second passivation layer on the second surface is greater than or equal to 0 mm and less than or equal to 20 μm in the vertical direction from the edge region to the center region of the second surface. For example, the width W of the second passivation layer 3 can be 0 mm, 1 μm, 3 μm, 5 μm, 8 μm, 10 μm, 12 μm, 13 μm, 15 μm, 17 μm, 18 μm, or 20 μm, etc. In this case, not only can color differences between different regions of the second surface be completely avoided, thus further reducing the visual differences of the solar cell, but also the probability of the electrode structure near the edge of the solar cell on the second surface being completely covered can be eliminated, ensuring that the connection between the connectors such as solder ribbons and the electrode structure is not affected, thereby improving the quality of the final module.

[0075] In summary, by adopting the above technical solutions, the aesthetics, surface refractive index, and PL brightness of solar cells can be significantly improved, thereby increasing the cell efficiency. Furthermore, when the width W of the second passivation layer 3 on the first surface 1 is greater than or equal to 0 mm and less than or equal to 20 μm in the vertical direction from the edge region to the center region of the first surface 1; and when the width of the second passivation layer on the second surface is greater than or equal to 0 mm and less than or equal to 20 μm in the vertical direction from the edge region to the center region of the second surface, not only can the solar cells be made visually identical, but the connection between connectors such as solder ribbons and the electrode structure will not be affected, thereby improving the quality of the final module.

[0076] As one possible implementation, see Figure 5 and Figure 6 The thickness of the first passivation layer is greater than the thickness of the second passivation layer.

[0077] By adopting the above technical solution, the passivation effect of the first passivation layer on the cut surface can be improved, further reducing the recombination rate of photogenerated carriers at the cut surface and improving the photoelectric conversion efficiency of the solar cell. Furthermore, since the thickness of the second passivation layer is relatively thin, it can not only reduce the influence of the second passivation layer on the surface refractive index and improve the cell efficiency of the solar cell, but also reduce the visual difference of the solar cell and improve its aesthetics.

[0078] In one alternative approach, the thickness of the first passivation layer is greater than or equal to 10 nm and less than or equal to 300 nm. For example, the thickness of the first passivation layer can be 10 nm, 30 nm, 50 nm, 85 nm, 100 nm, 130 nm, 150 nm, 170 nm, 190 nm, 200 nm, 220 nm, 250 nm, 280 nm, 290 nm, or 300 nm, etc.

[0079] Secondly, embodiments of the present invention also provide a photovoltaic module. The photovoltaic module includes a cell string and an encapsulation layer. The cell string is formed by connecting multiple solar cells as described in the above technical solutions, and the encapsulation layer is used to cover the surface of the cell string.

[0080] In another aspect of the present invention, heat treatment of the formed passivation layer can effectively improve its passivation performance. This improvement in passivation performance after heat treatment is independent of the distribution and morphology of the passivation layer. Whether the passivation layer on the first or second surface is spaced out or continuously distributed, heat treatment can improve its passivation performance. In particular, heat treatment significantly improves the passivation performance of the sidewall passivation layer and the passivation layers on the first and second surfaces formed by low-temperature processes. The heat treatment can take various forms, such as laser annealing or heat treatment in a relatively enclosed region with a temperature field. The heat treatment temperature is preferably greater than 200 degrees Celsius. For example, the aforementioned passivation layer can be the first passivation layer and / or the second passivation layer in this application.

[0081] The beneficial effects of the photovoltaic modules provided in the embodiments of the present invention are the same as those of the solar cells described in the above technical solutions, and will not be repeated here.

[0082] Thirdly, embodiments of the present invention also provide a method for fabricating a solar cell. The method for fabricating this solar cell includes:

[0083] First, a semiconductor substrate is provided;

[0084] For example, the semiconductor substrate can be a substrate made of semiconductor materials such as silicon, germanium-silicon, or germanium. In terms of conductivity type, the semiconductor substrate can be an intrinsically conductive substrate, an N-type conductive substrate, or a P-type conductive substrate. Preferably, the semiconductor substrate is an N-type conductive substrate or a P-type conductive substrate. Compared to intrinsically conductive substrates, N-type or P-type conductive substrates have higher conductivity, which helps reduce the series resistance of the solar cell and improve its efficiency. Structurally, the specific structure of the semiconductor substrate can be set according to the actual application scenario. For example, the semiconductor substrate can be a semiconductor substrate without any film layer formed on it, and both the backlight surface and the light-receiving surface are polished. Alternatively, the semiconductor substrate can be a semiconductor substrate without any film layer formed on it, and the light-receiving surface is textured. Compared to a polished surface, the textured structure has a good light-trapping effect; therefore, when the light-receiving surface of the semiconductor substrate is textured, more light can be refracted from the light-receiving surface into the semiconductor substrate, thereby improving the photoelectric conversion efficiency of the solar cell.

[0085] In practical applications, the semiconductor substrate is first polished and cleaned. Specific polishing and cleaning steps can be found in existing technologies and are not limited here.

[0086] Next, the semiconductor substrate is divided into at least two sliced ​​semiconductor substrates; the sliced ​​semiconductor substrates include opposing first and second surfaces, and a side surface connecting the first and second surfaces; the side surface includes a cut surface;

[0087] For example, a semiconductor substrate can be divided into at least two sliced ​​semiconductor substrates using laser technology or other non-destructive cutting methods.

[0088] Next, the cut surfaces of the slab semiconductor substrate are cleaned to remove the laser damage layer caused by the laser cutting process, thereby reducing lattice defects.

[0089] For example, in a chain cleaning machine, the wafer semiconductor substrate is placed in an HF and HNO3 bath, and cleaned using either a roller-carrying method or a water-floating method to remove some of the silicon slag and silicon oxide from the cut surfaces of the wafer semiconductor substrate. Since the cut surfaces lack the protection of a phosphosilicate glass layer, increasing the concentration of HF and HNO3 enhances the etching of the cut surfaces, thereby increasing the cleaning effect and making the cut surfaces smoother than those in existing technologies. Furthermore, the cleaning effect of the cut surfaces is made similar to that of other surfaces of the wafer semiconductor substrate. Next, during the tank cleaning process, the ratio of alkaline texturing to additives is adjusted to texturize and etch the cut surfaces, ensuring similar texturing results on all surfaces of the wafer semiconductor substrate. This improves the passivation effect of the solar cell after the formation of the first passivation layer on the wafer semiconductor substrate.

[0090] Next, a first passivation layer is formed on the cut surface.

[0091] For example, stacked sectional solar cells are placed in a tooling box that is closed on four sides and open on two sides. Then, one open side of the tooling box is closed to ensure that only the cut surface is exposed outside the tooling box. Preferably, a first passivation layer is formed on the cut surface using a PVD device in a vacuum environment through methods such as electron beam, resistance thermal evaporation, or magnetron sputtering. This improves the passivation effect of the solar cell, thereby increasing its photoelectric conversion efficiency. Furthermore, since the first passivation layer is formed on the cut surface of the cleaned sectional semiconductor substrate, the surface dangling bonds generated when the cut surface of the sectional semiconductor substrate is directly exposed to air can be saturated by the first passivation layer. Based on this, the minority carrier lifetime of the cut surface can be improved, reducing recombination current and thus improving the conversion efficiency of the solar cell and the module power.

[0092] In one alternative embodiment, the first passivation layer comprises a multilayer structure, such as a laminated film of aluminum oxide and silicon nitride, located on a diced surface of the semiconductor substrate to enhance protection of the diced surface. Aluminum oxide possesses excellent insulation and chemical stability, effectively preventing charge recombination. The silicon nitride passivation layer acts as an anti-reflection agent, allowing more light to be refracted from the diced surface into the semiconductor substrate, thereby further improving the light utilization efficiency of the solar cell. Furthermore, silicon nitride exhibits high light transmittance and excellent passivation effect; effective passivation can be achieved by forming a silicon nitride passivation layer on the surface of the solar cell.

[0093] By controlling the state of the stacked solar cells within the tooling box, such as the clamped state, or the spacing between the deposition source and the cell stack, multiple spaced-apart second passivation layers are formed on the edge regions adjacent to the cut surface on the first and / or second surfaces during the formation of the first passivation layer. A detailed description of the second passivation layers can be found in the first aspect and will not be repeated here.

[0094] The beneficial effects of the solar cell preparation method provided in this embodiment of the invention are the same as those of the solar cell described in the above technical solution, and will not be repeated here.

[0095] In one implementation, the temperature at which the first passivation layer and the second passivation layer are formed is less than or equal to 100°C.

[0096] For ease of subsequent description, the first passivation layer and the second passivation layer will be collectively referred to as passivation layers. Compared to the high-temperature process used in the prior art to form the passivation layer, the present invention forms the passivation layer at a lower temperature than in the prior art. This reduces or avoids damage to the film layer already formed on the semiconductor substrate during the passivation layer formation process. For example, when the solar cell is a BC (back-contact) type solar cell, it avoids damaging the surface protective film already formed on the semiconductor substrate, thus preventing the release of organic matter and avoiding damage to the edge passivation effect, ensuring the yield of the solar cell and the module power. For example, the photovoltaic module made from the solar cell obtained using the preparation method provided in the embodiments of the present invention has a module power increased by more than 3W compared to the 72-cell module.

[0097] Optionally, the first passivation layer and / or the second passivation layer may be subjected to heat treatment, such as laser annealing.

[0098] In another aspect of the present invention, heat treatment of the formed passivation layer can effectively improve its passivation performance. This improvement in passivation performance after heat treatment is independent of the distribution and morphology of the passivation layer. Whether the passivation layer on the first or second surface is spaced out or continuously distributed, heat treatment can improve its passivation performance. In particular, heat treatment significantly improves the passivation performance of the sidewall passivation layer and the passivation layers on the first and second surfaces formed by low-temperature processes. The heat treatment can take various forms, such as laser annealing or heat treatment in a relatively enclosed region with a temperature field. The heat treatment temperature is preferably greater than 200 degrees Celsius. For example, the aforementioned passivation layer can be the first passivation layer and / or the second passivation layer in this application.

[0099] 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. The above descriptions are merely specific embodiments of the present invention, but the scope of protection of the present invention 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 the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A solar cell, characterized in that, The solar cell includes opposing first and second surfaces, and a side surface connecting the first and second surfaces; the side surface includes a cut surface. The solar cell includes: A first passivation layer is formed on the cut surface; And a plurality of spaced second passivation layers formed on the edge regions adjacent to the cut surface in the first surface and / or the second surface; Multiple second passivation layers are distributed in an island-like pattern in the edge region; The width of the second passivation layer on the first surface is greater than or equal to 0 mm and less than or equal to 1 mm in the vertical direction from the edge region of the first surface to the center region of the first surface. And / or, in the vertical direction from the edge region of the second surface to the center region of the second surface, the width of the second passivation layer on the second surface is greater than or equal to 0 mm and less than or equal to 1 mm.

2. The solar cell according to claim 1, characterized in that, Along the thickness direction of the solar cell, the planar shape of the second passivation layer is a closed shape consisting of a triangle, quadrilateral, pentagon, or arc and line segment.

3. The solar cell according to claim 1, characterized in that, The second passivation layer includes an end near the center region of the first surface and / or the second surface, and the end boundaries of the plurality of second passivation layers are wavy or serrated.

4. The solar cell according to claim 1, characterized in that, The side surface also includes a non-cutting side surface adjacent to the cutting surface; Multiple spaced-apart second passivation layers are also formed on the edge region adjacent to the cut surface on the non-cut side surface.

5. The solar cell according to claim 1, characterized in that, The plurality of second passivation layers include at least one second passivation layer that is spaced apart from the first passivation layer.

6. The solar cell according to claim 1, characterized in that, The thickness of the first passivation layer is greater than the thickness of the second passivation layer.

7. The solar cell according to claim 1, characterized in that, The thickness of the first passivation layer is greater than or equal to 10 nm and less than or equal to 300 nm.

8. A photovoltaic module, characterized in that, The photovoltaic module includes: A battery string, wherein the battery string is formed by connecting a plurality of solar cells as described in any one of claims 1 to 7; An encapsulation layer is used to cover the surface of the battery string.

9. A method for preparing a solar cell, comprising: Provide a semiconductor substrate; The semiconductor substrate is divided into at least two sliced ​​semiconductor substrates; The sliced ​​semiconductor substrate includes opposing first and second surfaces, and a side surface connecting the first and second surfaces; the side surface includes a cut surface. A first passivation layer is formed on the cut surface; Multiple spaced second passivation layers are formed on the edge regions adjacent to the cutting surface in the first surface and / or the second surface; Multiple second passivation layers are distributed in an island-like pattern in the edge region; The width of the second passivation layer on the first surface is greater than or equal to 0 mm and less than or equal to 1 mm in the vertical direction from the edge region of the first surface to the center region of the first surface. And / or, in the vertical direction from the edge region of the second surface to the center region of the second surface, the width of the second passivation layer on the second surface is greater than or equal to 0 mm and less than or equal to 1 mm.

10. The method for preparing a solar cell according to claim 9, characterized in that, The temperature at which the first passivation layer and the second passivation layer are formed is less than or equal to 100°C.

11. The method for preparing a solar cell according to claim 9 or 10, characterized in that, It also includes heat treatment of the first passivation layer and / or the second passivation layer.

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