Solar cells and solar modules

Abstract

To provide a solar cell and a solar module that improves the photoelectric conversion efficiency of a solar cell by balancing the light confinement effect and passivation performance of the side surface of a silicon substrate. [Solution] A silicon substrate (10) includes opposing first and second surfaces (11 and 12) and a side surface (13) connecting the first and second surfaces (11 and 12), and at least one side surface (13) of the silicon substrate (10) includes a plurality of first texture regions (A11) and second texture regions (A12). Each of the first texture regions (A11) includes a plurality of first pyramid structures, and the second texture region (A12) includes a second pyramid structure. The structural dimensions of the second pyramid structures are larger than the structural dimensions of the first pyramid structures, and the second texture region (A12) is located between adjacent first texture regions (A11). A passivation layer (not shown) covers the first texture region (A11) and the second texture region (A12) on at least one side surface (13).

Description

[Technical Field]

[0001] This application relates to the technical field of photovoltaics, and in particular to solar cells and solar modules. [Background technology]

[0002] Solar cells can convert light energy into electrical energy and are of great significance for energy development and environmental protection. Monocrystalline silicon cells occupy a large share of the photovoltaic industry due to their advantages, such as high conversion efficiency and mature technology. Thinning silicon wafers is an inevitable trend to reduce production costs. However, thinner silicon wafers reduce the substrate's light absorption rate and the number of photogenerated carriers. As silicon wafers become thinner, how to further improve the light absorption of solar cells is an urgent issue that needs to be addressed. Conventional technologies use pyramidal textured surface structures on the side surfaces of solar cells to enhance the light trapping effect on the side surfaces and increase the light absorption of solar cells. However, such structures affect the coating quality of the passivation layer on the side surfaces of solar cells, reducing the passivation performance of solar cells and affecting their efficiency. Summary of the Invention [Problem to be solved by the invention]

[0003] The object of the present application is to provide a solar cell and a solar module that improves the photoelectric conversion efficiency of the solar cell by controlling the morphology of the side surface of the solar cell, thereby balancing the light trapping effect and passivation performance of the side surface. [Means for solving the problem]

[0004] To achieve the above object, in a first aspect, the present application provides a solar cell. The solar cell includes a silicon substrate and a passivation layer. The silicon substrate has opposing first and second surfaces and a plurality of side surfaces connecting the first and second surfaces. At least one side surface includes a plurality of first texture regions and a second texture region, each of the first texture regions including a plurality of first pyramid structures, and the second texture region including a plurality of second pyramid structures. The structural dimensions of the second pyramid structures are larger than the structural dimensions of the first pyramid structures. A second texture region is located between adjacent first texture regions. The passivation layer covers the first texture region and the second texture region on at least one of the side surfaces.

[0005] In some embodiments, the second texture regions extend between the first texture regions in any one or more of a straight line, a polygonal line, or a curved line.

[0006] In some embodiments, the extension direction of the second texture region is not parallel to the thickness direction of the solar cell, and / or the extension directions of at least two second texture regions are set parallel to the thickness direction of the solar cell.

[0007] In some embodiments, the second texture region comprises prismatic structures, the prismatic structures having a length range of 200 nm to 6 μm.

[0008] In some embodiments, the structural dimension of the first pyramid structure is in the range of 0.05 μm to 2 μm.

[0009] In some embodiments, the structural dimension of the second pyramid structure is in the range of 2 μm to 6 μm.

[0010] In some embodiments, the side surface includes a first region, the first region is connected to the first surface, the first texture region and the second texture region are both provided in the first region, and the width of the first region occupies more than 20% and less than 100% of the width of the side surface.

[0011] In some embodiments, the side surface includes a first region and a second region, the first texture region and the second texture region are both provided in the first region, the second region is connected to the second surface side, and the second region includes a plurality of base structures.

[0012] In some embodiments, the boundary between the first region and the second region is curved, and a depression is provided in the second region near the boundary.

[0013] In some embodiments, the width of the region where the recess is provided is 0% to 60% of the width of the second region in the thickness direction of the silicon substrate.

[0014] In some embodiments, the shape of the depression comprises one or more of an inverted pyramid, an inverted hemisphere, a stepped shape, and / or the cross-sectional area of ​​the depression gradually increases along a direction perpendicular to the side.

[0015] In some embodiments, the cross-sectional diameter of the depressions on the side is 0.1 μm to 5 μm and / or the depth of the depressions is 0.05 μm to 2 μm.

[0016] In some embodiments, in a direction away from the silicon substrate, the passivation layer comprises, in sequence, an aluminum oxide layer and a silicon nitride layer.

[0017] In the solar cell described above, the first pyramid structures in the first textured region enhance the light trapping effect on the side surfaces of the solar cell, improving the light utilization efficiency of the solar cell. While small first pyramid structures increase the surface roughness of the side surfaces, which is detrimental to the coating quality of the subsequent passivation layer on the side surfaces of the solar cell, the present application also designs second pyramid structures in the second textured region. The larger structural dimensions of the second pyramid structures provide a larger surface area than the first pyramid structures, providing a larger coating area for subsequent coating and improving coating quality. Therefore, the combined structure of multiple first pyramid structures and multiple second pyramid structures better balances the passivation and light trapping effects on the side surfaces of the solar cell, improving the photoelectric conversion efficiency of the solar cell.

[0018] In a second aspect, the present application provides a solar module, the solar module comprising a plurality of solar cells electrically connected to each other, the solar cells being the solar cells provided in the first aspect of the present application. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic diagram of the distribution of texture structures on the side surface of a solar cell according to an embodiment of the present application. [Figure 2] 1 is a structural schematic diagram of a solar cell according to an embodiment of the present application. [Figure 3] FIG. 3 is a structural schematic diagram of a silicon substrate of the solar cell in FIG. 2. [Figure 4] FIG. 3 is a schematic diagram showing the distribution of texture structures on the silicon substrate of the solar cell in FIG. 2. [Figure 5] 1 is a scanning electron microscope image of the side surface of a solar cell according to an embodiment of the present application. [Figure 6] 1 is another scanning electron microscope image of the side of a solar cell according to one embodiment of the present application. [Figure 7] 1 is a scanning electron microscope image of a first surface of a solar cell according to an embodiment of the present application. [Figure 8]2 is a schematic diagram showing the structural dimensions of a pyramid structure and a base structure in a solar cell according to an embodiment of the present application. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer and easier to understand, the present application will be described in more detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only for the purpose of illustrating the present invention and are not intended to limit the present application.

[0021] Hereinafter, the embodiments of the present application will be described in detail, and the embodiments are illustrated in the drawings, in which the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are merely illustrative and are intended to interpret the embodiments of the present application, and should not be understood as limiting the present application.

[0022] In describing the examples of the present application, orientations or positional relationships indicated by terms such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," etc. are based on the drawings and are merely for the convenience of explaining the embodiments of the present application and simplifying the description, and are not intended to indicate or suggest that the described devices or elements must have a specific orientation, be configured, or operate in a specific orientation, and therefore should not be understood as limiting the present application.

[0023] In describing the embodiments of the present application, the terms "first" and "second" are for descriptive purposes only and should not be understood as indicating or suggesting the relative importance or implicitly indicating the number of technical features indicated, whereby a feature qualified as "first" or "second" may explicitly or implicitly include one or more of said features.

[0024] In the description of the examples of this application, unless otherwise specified, "plurality" means two or more.

[0025] In describing the embodiments of the present application, unless otherwise specified, the terms "attached," "coupled," and "connected" should be understood broadly, and may refer to, for example, a fixed connection, a detachable connection or an integral connection, a mechanical connection, an electrical connection or a connection capable of communicating with each other, a direct connection, an indirect connection via an intermediate medium, an internal communication between two elements, or an interactive relationship between two elements.

[0026] Those skilled in the art will understand the specific meanings of the above terms in this application depending on the specific circumstances.

[0027] 1 and 2, the solar cell 100 includes a silicon substrate 10, which may be an N-type silicon substrate or a P-type silicon substrate.

[0028] Specifically, the silicon substrate 10 includes a first surface 11 and a second surface 12 that face each other, and a side surface 13 that connects the first surface 11 and the second surface 12 together.

[0029] The cell type of the solar cell 100 is not limited to that shown in FIG. 2 . Specifically, the cell type of the solar cell 100 may be a tunnel oxide passivated contact back contact (TBC) cell, a tunnel oxide passivated contact (TOPCon) cell, or a hybrid back contact cell. Here, a hybrid back contact cell refers to a back contact cell in which the N region and the P region correspond to a tunnel passivated contact structure and a heterojunction contact structure, respectively, or a back contact cell in which the N region and the P region correspond to a tunnel passivated contact structure and a passivated emitter structure, respectively. The silicon substrate of the solar cell 100 may be an N-type raw silicon wafer or a P-type raw silicon wafer.

[0030] The structure of the silicon substrate 10 will be described in detail below. Figure 3 is a structural schematic diagram of the silicon substrate 10 of the solar cell 100 in Figure 2. As shown in Figure 3, the silicon substrate 10 has a substantially rectangular parallelepiped shape. The side surface 13 includes a first side surface 131, a second side surface 132, a third side surface 133, and a fourth side surface 134 that are connected in sequence. The first side surface 131 and the third side surface 133 are disposed opposite each other. The second side surface 132 and the fourth side surface 134 are disposed opposite each other.

[0031] Fig. 4 is a schematic diagram showing the distribution of the texture structure of the silicon substrate 10 of the solar cell 100 in Fig. 2. Fig. 5 is a scanning electron microscope image of the side surface 13 of the solar cell 100 of one example of the present application.

[0032] 1 to 5, a plurality of pyramid structures T11 are provided on at least one side surface 13 of a silicon substrate 10. Specifically, the plurality of pyramid structures T11 includes a plurality of first pyramid structures and a plurality of second pyramid structures. More specifically, due to the distribution of the plurality of pyramid structures T11, at least one side surface 13 of the silicon substrate 10 includes a plurality of first texture regions A11 and a plurality of second texture regions A12. Each of the first texture regions A11 includes a plurality of first pyramid structures. The second texture region A12 includes a plurality of second pyramid structures. The structural dimensions of the second pyramid structures are larger than the structural dimensions of the first pyramid structures. The second texture region A12 is located between adjacent first texture regions A11. The solar cell 100 includes a passivation layer (not shown), which covers the first texture region A11 and the second texture region A12 on at least one side surface 13.

[0033] It should be noted that in the embodiments of the present application, the structural dimension of the first pyramid structure refers to any one of the length, width or diagonal length of the base of the first pyramid structure, and / or the height of the first pyramid structure, and the structural dimension of the second pyramid structure refers to any one of the length, width or diagonal length of the base of the second pyramid structure, and / or the height of the second pyramid structure.

[0034] In related art, a base texture structure is formed on the side surface of a silicon substrate of a solar cell, and although the base texture structure can improve the coating quality of the passivation layer on the side surface, it increases the light reflectance and reduces the light absorption performance of the solar cell. Alternatively, a pyramidal texture surface structure of a single size range is formed on the side surface of a silicon substrate of a solar cell, and although this texture surface structure can improve the light trapping effect of the side surface of the silicon substrate of a solar cell, it increases the roughness of the side surface of the silicon substrate, which is detrimental to improving the passivation performance of the side surface of the silicon substrate.

[0035] In contrast, in the embodiment of the present application, the side surface 13 of the solar cell 100 includes a plurality of pyramid structures T11. The first pyramid structures in the first texture region A11 can enhance the light trapping effect of the side surface of the solar cell 100 and improve the light utilization efficiency of the solar cell 100. Furthermore, in the embodiment of the present application, a second pyramid structure is further designed to be formed in the second texture region A12. The larger structural dimensions of the second pyramid structure provide a larger surface area than the first pyramid structure, providing a larger coating area for the subsequent coating of a passivation layer, improving the coating quality of the passivation layer and enhancing the passivation performance of the side surface 13. Therefore, compared to the base texture structure or pyramid structures with a single structural dimension in the related art, the combined structure of a plurality of first pyramid structures and a plurality of second pyramid structures can better balance the passivation and light trapping effects of the side surface of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell.

[0036] In some embodiments, the passivation layer further covers the side surface 13 in areas other than the first textured area A11 and the second textured area A12.

[0037] In some embodiments, referring to FIG. 2, the solar cell 100 further comprises a first dielectric layer 20, a first doped conductive layer 30, a second dielectric layer 40, and a second doped conductive layer 50.

[0038] The first dielectric layer 20 and the second dielectric layer 40 are alternately disposed on the second surface 12. The first doped conductive layer 30 is located on the side of the first dielectric layer 20 opposite the silicon substrate 10. The second doped conductive layer 50 is located on the side of the second dielectric layer 40 opposite the silicon substrate 10.

[0039] The first doped conductive layer 30 and the second doped conductive layer 50 have opposite conductivity types. The conductivity type of the first doped conductive layer 30 may be N-type and the conductivity type of the second doped conductive layer 50 may be P-type. Alternatively, the conductivity type of the first doped conductive layer 30 may be P-type and the conductivity type of the second doped conductive layer 50 may be N-type.

[0040] Space regions are formed between the first dielectric layer 20 and the second dielectric layer 40, and between the first doped conductive layer 30 and the second doped conductive layer 50, thereby electrically isolating the first doped conductive layer 30 and the second doped conductive layer 50. It should be noted that in practical situations, space regions can be arranged to achieve electrical isolation, but other methods can also be used without space regions as long as they can achieve electrical isolation between film layers or regions of different doping types.

[0041] The materials of the first dielectric layer 20 and the second dielectric layer 40 may be materials such as, but not limited to, silicon oxide, aluminum oxide, titanium oxide, or intrinsic amorphous silicon. The materials of the first doped conductive layer 30 and the second doped conductive layer 50 may be materials such as, but not limited to, doped polycrystalline silicon or doped amorphous silicon.

[0042] The passivation layer covers at least one side surface 13 as well as the first surface 11 and / or the second surface 12. Specifically, the passivation layer covers at least one side surface 13 and the first surface 11 of the solar cell 100, or the passivation layer covers at least one side surface 13 and the second surface 12 of the solar cell 100, or the passivation layer covers at least one side surface 13, the first surface 11 and the second surface 12 of the solar cell 100. When the passivation layer covers the second surface 12, the passivation layer covers the side of the first doped conductive layer 30 opposite the silicon substrate 10 and the side of the second doped conductive layer 50 opposite the silicon substrate 10.

[0043] The material of the passivation layer may be one or more of materials such as, but not limited to, aluminum oxide, silicon nitride, silicon oxynitride, etc., and is used to passivate the surface of the silicon substrate 10 or the functional layer and reduce or eliminate reflected light on the surface of the solar cell 100, thereby improving the utilization of sunlight by the solar cell 100 and improving the photoelectric conversion efficiency.

[0044] In some embodiments, the passivation layer includes an aluminum oxide layer and a silicon nitride layer, which are disposed in sequence. The aluminum oxide layer has a thickness ranging from 4 to 10 nm (e.g., from 4 to 6 nm, from 6 to 8 nm, from 8 to 10 nm, etc.). The silicon nitride layer can have a single layer structure or a multilayer structure with different refractive indices, and the silicon nitride layer has a thickness ranging from 50 to 100 nm (e.g., from 50 to 60 nm, from 60 to 70 nm, from 70 to 80 nm, from 80 to 90 nm, from 90 to 100 nm, etc.).

[0045] A passivation layer, through field passivation or chemical passivation, reduces recombination centers on the surface of the silicon substrate or other film layers, reducing carrier recombination on the cell surface and improving cell efficiency. The outermost passivation layer can also reduce solar light reflection and enhance the cell's light absorption capability. For example, an aluminum oxide layer saturates dangling bonds on the surface of the side surface 13, reducing the interface state density and passivating the side surface. A silicon nitride layer protects the aluminum oxide layer, achieving internal reflection and improving the light utilization efficiency of the solar cell.

[0046] In some embodiments, the thickness of the silicon nitride layer on the side surface 13 is greater than the thickness of the silicon nitride layer on the first surface 11 or the second surface 12. In comparison, the side surface 13 has a much smaller area than the first surface 11 or the second surface 12, and the coating quality of the passivation layer thereon is not as good as that of the first surface 11 or the second surface 12. Therefore, a thicker silicon nitride layer can maximize the continuity of the coating of the silicon nitride layer covering the side surface, providing protection and passivation for the aluminum oxide layer and the side surface 13, as well as light reflection.

[0047] In some embodiments, the second texture regions A12 extend between the first texture regions A11 in one or more of a linear, polygonal, and / or curved line. Furthermore, the extension direction of the second texture regions A12 is not parallel to the thickness direction of the solar cell 100, and / or the extension directions of at least two second texture regions A12 are parallel to each other.

[0048] This contributes to improving the regularity of the morphological changes on the side of the solar cell 100, and further improves the uniformity of the film layer formed based on the side of the solar cell 100, thereby improving the passivation effect on the side of the solar cell 100.

[0049] Specifically, the side surface 13 has a first region A1 connected to the first surface 11. The first texture region A11 and the second texture region A12 are both provided in the first region A1. The structural dimension of the first pyramid structure T11 is in the range of 0.05 μm to 2 μm. The structural dimension of the second pyramid structure T11 is in the range of 2 μm to 6 μm.

[0050] Illustratively, the dimensional range of the base of the first pyramid structure of the pyramid structure T11 and / or the dimensional range of the height of the first pyramid structure is 0.05 μm or more and 2 μm or less (e.g., 0.05 μm or more and 0.1 μm or less, 0.1 μm or more and 0.5 μm or less, 0.5 μm or more and 1.1 μm or less, 1.1 μm or more and 1.3 μm or less, 1.3 μm or more and 1.5 μm or less, 1.5 μm or more and 1.8 μm or less, 1.8 μm or more and 2 μm or less, etc.). The dimensional range of the base of the second pyramid structure of the pyramid structure T11 and / or the dimensional range of the height of the second pyramid structure is 2 μm or more and 6 μm or less (2 μm or more and 2.3 μm or less, 2.3 μm or more and 2.8 μm or less, 2.8 μm or more and 3.3 μm or less, 3.3 μm or more and 4 μm or less, 4 μm or more and 5 μm or less, 5 μm or more and 6 μm or less, etc.).

[0051] An embodiment of the present application will now be described in more detail with reference to FIG.

[0052] 5, the second texture regions A12 extend in a polygonal line between the first texture regions A11. Furthermore, the extension direction of the second texture regions A12 is not parallel to the thickness direction of the solar cell 100.

[0053] It should be noted that two second texture areas A12 are shown in solid line frames in FIG. 5, and only a portion of the second texture areas A12 is shown in FIG. 5. In actual applications, the number of second texture areas A12 on the side 13 includes, but is not limited to, the number of second texture areas A12 shown in black frames, and the size and extension direction of the second texture areas A12 are also not limited to the shape of the second texture areas A12 shown in solid line frames.

[0054] The angle between the extension direction of the second texture region A12 and the thickness direction D1 of the solar cell 100 is calculated using the same rule and refers to the angle between the extension direction of the second texture region A12 and the thickness direction D1 of the solar cell 100 in the counterclockwise direction (or clockwise direction).

[0055] In some embodiments, the orthogonal projections of the second pyramidal structures on the side surface 13 overlap.

[0056] The second textured region A12 further includes a plurality of prismatic structures T12 (as shown by the dotted oval region in FIG. 5 ). Compared to a pyramidal textured surface structure, the prismatic structures T12 can provide a flatter surface than the first pyramidal structures. Furthermore, the prismatic structures T12 have a larger surface area, providing a larger deposition area for the subsequent deposition of a passivation layer. Therefore, the combined structure of a plurality of first pyramidal structures, a plurality of second pyramidal structures, and a plurality of prismatic structures T12 can better achieve both passivation and light trapping effects on the side surface 13 of the solar cell 100 compared to a single textured surface structure or base structure in the related art.

[0057] In some embodiments, the length range of the prismatic structures T12 is 200 nm to 6 μm (e.g., 200 nm to 500 nm, 500 nm to 1 μm, 1 μm to 3 μm, 3 μm to 5 μm, 5 μm to 6 μm, etc.).

[0058] It should be noted that the length of the prismatic structure T12 refers to the distance from the bottom to the top of the prismatic structure T12 in the tilt direction of the prismatic structure T12.

[0059] In some embodiments, some prismatic structures T12 include a prismatic base and a generally pyramidal top connected to the base. Some prismatic structures T12 are generally prismatic in shape overall.

[0060] The side surface 13 further includes a second region A2. The second region A2 is connected to the side of the first region A1 closer to the second surface 12.

[0061] 6 is another scanning electron microscope image of the side surface 13 of the solar cell 100 according to one embodiment of the present application. As shown in FIG. 6, the second region A2 includes a plurality of base structures T13.

[0062] The second region A2 having a plurality of base structures T13 contributes to increasing the specific surface area of ​​the side of the solar cell 100, thereby increasing the specific surface area of ​​the subsequent coating film layer and improving the passivation effect of the passivation layer on the side of the solar cell 100. In addition, the passivation performance after the passivation layer is coated on the base structures T13 in the second region A2 is better, and the better passivation performance in the portion close to the second surface 12 reduces the possibility of carrier recombination at the edge of the solar cell 100, contributing to improving the performance of the solar cell 100.

[0063] By combining this with the process, the problem of excessive etching of the second surface 12 can be improved, and in the solar cell 100 of the embodiment of the present application, by providing a second region A2 on the side, the passivation performance of the solar cell 100 can be improved while reducing excessive etching of the functional layer of the second surface by the etching solution.

[0064] In some embodiments, the base structure may be a recessed structure recessed into the surface of the side surface 13, and the projection shape of the bottom or opening thereof exhibits a rectangular, rhombic, parallelogram, nearly rectangular, nearly rhombic, or nearly parallelogram structure. The shape of the base structure T13 includes one of a square or nearly square shape.

[0065] Illustratively, the range of the lateral dimension of the base structure T13 is 10 μm or more and 30 μm or less (e.g., 10 μm or more and 12 μm or less, 12 μm or more and 13 μm or less, 13 μm or more and 14.5 μm or less, 14.5 μm or more and 15 μm or less, 15 μm or more and 20 μm or less, 20 μm or more and 25 μm or more and 25 μm or more and 28 μm or less, 28 μm or more and 30 μm or less, etc.). Specifically, the lateral dimension of the base structure T13 is the maximum distance at the base bottom surface of the base structure T13.

[0066] Illustratively, the range of the vertical height of the base of the base structure T13 is 0.01 μm or more and 8 μm or less (e.g., 0.01 μm or more and 0.05 μm or less, 0.05 μm or more and 0.1 μm or less, 0.1 μm or more and 0.4 μm or more, 0.4 μm or more and 0.5 μm or less, 0.5 μm or more and 0.7 μm or less, 0.7 μm or more and 1 μm or less, 1 μm or more and 1.3 μm or less, 1.3 μm or more and 1.5 μm or less, 1.5 μm or more and 1.8 μm or less, 1.8 μm or more and 2.3 μm or less, 2.3 μm or more and 2.8 μm or less, 2.8 μm or more and 3.3 μm or less, 3.3 μm or more and 4 μm or less, 4 μm or more and 5 μm or less, 5 μm or more and 6 μm or less, 6 μm or more and 7 μm or less, 7 μm or more and 8 μm or less, etc.).

[0067] In some embodiments, the base structure T13 may not appear completely in the second region A2.

[0068] In some embodiments, the boundary line between the first region A1 and the second region A2 is curved, a recess R is provided in the second region A2 at a position close to the boundary line, and the width of the region where the recess R is provided in the thickness direction of the silicon substrate 10 is 0% or more and 60% or less of the width of the second region A2 (e.g., 0% or more and 10% or less, 10% or more and 20% or less, 20% or more and 30% or less, 30% or more and 40% or less, 40% or more and 50% or less, 50% or more and 60% or less, etc.).

[0069] In some embodiments, the shape of the depression R includes one or more of an inverted pyramid shape, an inverted hemisphere shape, and a stepped shape.

[0070] In some embodiments, the cross-sectional area of ​​the recess R gradually increases along a direction perpendicular to and away from the side surface 13 .

[0071] In some embodiments, the cross-sectional diameter of the depression R on the side surface 13 is 0.1 μm or more and 5 μm or less (e.g., 0.1 μm or more and 1 μm or less, 1 μm or more and 1.5 μm or less, 1.5 μm or more and 2 μm or less, 2 μm or more and 3.5 μm or less, 3.5 μm or more and 5 μm or less, etc.).

[0072] Specifically, the diameter of the cross section of the recess R on the side surface 13 is the diameter of the cross section farthest from the bottom surface of the recess R. In other words, it is the diameter of the cross section of the opening of the recess R.

[0073] The diameter of the recess R can be obtained by a three-dimensional microscope or a scanning electron microscope, and the depth of the recess R can be obtained by scanning with the three-dimensional microscope.

[0074] By providing the recess R at the boundary between the first region A1 and the second region A2, the shapes of the first region A1 and the second region A2 tend to change transitionally, reducing the pronounced undulations of the side surface 13 and contributing to improving the quality of the coating at the subsequent boundary line. In addition, the recess R located in the second region A2 can partially enhance the optical confinement effect of incident light.

[0075] In some embodiments, the depth of the recess R is 0.05 μm or more and 2 μm or less (e.g., 0.05 μm or more and 0.1 μm or less, 0.1 μm or more and 0.5 μm or more, 0.5 μm or more and 1 μm or less, 1 μm or more and 1.5 μm or more, 1.5 μm or more and 2 μm or less, etc.).

[0076] In some embodiments, the distribution ratio of the first region A1 to the side surface 13 in the direction extending from the first surface 11 to the second surface 12 is 20% or more and 100% or less. Specifically, the distribution ratio of the first region A1 to the side surface 13 in the direction extending from the first surface 11 to the second surface 12 refers to the ratio of the length of the first region A1 in the thickness direction of the solar cell 100 to the thickness of the solar cell 100. More specifically, the length of the first region A1 in the thickness direction of the solar cell 100 refers to the vertical distance from the intersection of the first surface 11 and the side surface 13 to the lowest point of the boundary line between the first region A1 and the second region A2 in the thickness direction of the solar cell 100.

[0077] In some embodiments, the first region A1 has a width X (shown in FIG. 4) in a direction extending from the first surface 11 to the second surface 12. The ratio of the width X of the first region A1 to the thickness L (shown in FIG. 4) of the silicon substrate 10 ranges from 20% to 100% (e.g., from 20% to 35%, from 35% to 40%, from 40% to 55%, from 55% to 70%, from 70% to 80%, from 80% to 85%, from 85% to 90%, from 90% to 95%, from 95% to 100%, etc.).

[0078] As a result, the minimum value of the proportion range of the first region A1 can ensure that the pyramidal structures T11 are distributed on the side surface 13, thereby enhancing the light confinement effect of the side surface 13; the maximum value of the proportion range can ensure that the pyramidal structures T11 satisfy the light confinement effect and also ensure that the second texture region A12 has a sufficient area to extend between the first texture regions A11, thereby increasing the surface area of ​​the side surface having the first texture region, and improving the coating quality of the passivation layer.

[0079] In some embodiments, in combination with the process, the proportion of the first region A1 can ensure that the film layer to be cleaned on the first surface 11 is completely removed during the chain etching process, providing a good surface base for subsequent processes such as texturing, coating, etc. At the same time, the proportion of the first region A1 can alleviate the problem of excessive etching of the film layer on the back surface (second surface 12) during the chain etching process.

[0080] In some embodiments, the ratio of the first region A1 to the side surface 13 is greater than or equal to 80% and less than or equal to 100%, so that the multiple pyramidal structures T11 and the multiple prism-like structures T12 are distributed over most of, or even the entire, side surface 13; further, the multiple pyramidal structures T11 and the multiple prism-like structures T12 on the side surface 13 contribute to improving the light trapping effect and passivation performance of the solar cell 100 and balancing the relationship between the two, ultimately improving the cell efficiency of the solar cell 100.

[0081] In some embodiments, the distribution ratio of the second region A2 to the side surface 13 in the direction extending from the second surface 12 to the first surface 11 is greater than 0 and less than or equal to 80%. Specifically, the ratio of the width (LX) of the second region A2 to the thickness L of the silicon substrate 10 in the direction extending from the second surface 12 to the first surface 11 is greater than or equal to 0 and less than or equal to 80% (e.g., 0% to 5%, 5% to 10%, 10% to 15%, 15% to 18%, 18% to 20%, 20% to 35%, 35% to 40%, 40% to 55%, 55% to 70%, 70% to 80%, etc.).

[0082] If the ratio of the width (LX) of the second region A2 to the thickness L of the silicon substrate 10 is too small, there is an increased risk of over-etching the functional layer on the second surface 12. If this ratio is too large, it becomes difficult to ensure the wraparound removal effect on the first surface 11. As a result, the possibility of micro-defects occurring between layers due to differences in the lateral etching efficiency of the functional layer and the silicon substrate 10 is reduced, and recombination problems in the final battery are alleviated, the battery passivation effect is enhanced, and battery efficiency can be improved.

[0083] In some embodiments, the side surface 13 is composed of a first region A1 and a second region A2. That is, in any side surface 13, the sum of the distribution ratio of the first region A1 to the side surface 13 and the distribution ratio of the second region A2 to the side surface 13 is 100% in the direction extending from the second surface 12 to the first surface 11.

[0084] In some embodiments, the second region A2 is formed on at least one of the first side surface 131, the second side surface 132, the third side surface 133, and the fourth side surface 134. That is, the second region A2 (in other words, the structure where the polishing surface and the base structure T13 coexist) may be formed on any one, any two, any three, or any four of the first side surface 131, the second side surface 132, the third side surface 133, and the fourth side surface 134.

[0085] In some embodiments, the first side 131, the second side 132, the third side 133, and the fourth side 134 may not have the second region A2.

[0086] 7 is a scanning electron microscope image of the first surface 11 of a solar cell 100 according to one embodiment of the present application. As shown in FIG. 7, the first surface 11 has a plurality of third pyramid structures T21, which enhance the light trapping effect on the side of the solar cell 100 where the first surface 11 is located.

[0087] It should be noted that the sizes of the third pyramidal structure T21 on the first surface 11 and the pyramidal structure T11 on the side surface 13 do not completely match, but there is a difference between them.

[0088] Illustratively, the dimension range of the base of the third pyramid structure T21 is 0.05 μm or more and 2 μm or less (e.g., 0.05 μm or more and 0.1 μm or less, 0.1 μm or more and 0.5 μm or less, 0.5 μm or more and 1.1 μm or less, 1.1 μm or more and 1.3 μm or less, 1.3 μm or more and 1.5 μm or less, 1.5 μm or more and 1.8 μm or less, 1.8 μm or more and 2 μm or less, etc.).

[0089] For example, the height of the third pyramid structures T21 is in the range of 0.1 μm to 2 μm (e.g., 0.1 μm to 0.5 μm, 0.5 μm to 1 μm, 1 μm to 1.3 μm, 1.3 μm to 1.5 μm, 1.5 μm to 1.8 μm, 1.8 μm to 2 μm, etc.). If the horizontal dimension and vertical height of the base of the third pyramid structures T21 are not appropriate, the secondary reflection of light by the third pyramid structures T21 will be insufficient, increasing the reflectivity of the textured surface and reducing the light absorption performance of the cell.

[0090] Specifically, the orthogonal projection shape of the base of the pyramid structure T11 on the side surface 13 and the orthogonal projection shape of the third pyramid structure T21 on the first surface 11 may be a regular rectangle or an irregular polygon. In the case of a regular rectangle, referring to FIG. 8(a), the structural dimensions of the bases of the pyramid structures T11 and T21 are the longest diagonal length d1 or the longest side length d2 of the bases of the pyramid structures. In the case of an irregular rectangle, the side lengths and diagonal lengths of the bases of the pyramid structures T11 and T21 are not absolute but are artificially defined to characterize the dimensions of the bases. For example, the side lengths of the bases of the pyramid structures T11 and T21 may be defined as the side length of the longest side of an irregular rectangle, and the diagonal lengths of the bases of the pyramid structures T11 and T21 may be defined as the longest diagonal length of an irregular rectangle. The heights of the pyramid structure T11 and the third pyramid structure T21 are the heights from the apex to the base of the pyramid structure. It is understood that the above is merely an exemplary description and can be flexibly defined according to actual needs.

[0091] It should be noted that the pyramid structures T11 and the third pyramid structures T21 are both distributed in various sizes, and the above dimensions are the structural dimensions of the pyramid structures T11 and / or the structural dimensions of the third pyramid structures T21 that are relatively uniformly distributed within the interface when the textured surface on the first surface 11 or the side surface 13 is observed under magnification. Also, (a) of Figure 8 is a schematic diagram of the measurement method, and does not have a direct correlation with the actual bottom shape of the pyramid structures T11 or the third pyramid structures T21.

[0092] Specifically, as shown in (b) of Figure 8, the method for measuring the bottom dimension of the base of the base structure T13 is to take the larger of the diagonal length d3 of the base and the diagonal length d4 of the base in a direction parallel to the bottom surface of the base structure T13, and the method for measuring the vertical height of the base of the base structure T13 is to take the difference in height between the bottom surface of the base structure T13 and the plane of the side surface 13.

[0093] It should be noted that the base structures T13 are distributed in various sizes, and the above dimensions are the sizes of the bases of the base structures T13 that are relatively uniformly distributed within the interface observed by enlarging the textured surface on the side surface 13. Also, (b) of Figure 8 is a schematic diagram of the measurement method and does not directly correlate with the actual base shape of the base structures T13.

[0094] An embodiment of the present application further provides a solar module, the solar module including a plurality of solar cells electrically connected to each other, the solar cells being the solar cells of any of the above embodiments.

[0095] In some embodiments, the method for manufacturing the solar cell of the above embodiment includes the following steps S10 to S60.

[0096] According to different needs, the order of some steps or sub-steps in the solar cell manufacturing method may be changed, and some steps or sub-steps may be omitted or combined.

[0097] In step S10, a silicon substrate including first and second opposing surfaces and a side surface connecting the first and second surfaces is provided, and a base structure is formed on the first surface, the second surface, and the side surface.

[0098] Specifically, the silicon substrate may be a P-type raw silicon wafer or an N-type raw silicon wafer. The silicon substrate is subjected to an alkaline polishing treatment using a slot machine to form a base structure on the surface of the silicon substrate. The base structure includes a structure in which a polished surface and a base structure coexist. In other words, the base structure is a base structure that has been subjected to a polishing treatment.

[0099] Illustratively, the lateral dimension range of the base of the base structure formed in step S10 is 10 μm or more and 30 μm or less (e.g., 10 μm or more and 12 μm or less, 12 μm or more and 13 μm or less, 13 μm or more and 14.5 μm or less, 14.5 μm or more and 15 μm or less, 15 μm or more and 20 μm or less, 20 μm or more and 25 μm or less, 25 μm or more and 28 μm or less, 28 μm or more and 30 μm or less, etc.).

[0100] Illustratively, the range of the vertical height of the base structure formed in step S10 is 0.01 μm or more and 8 μm or less (e.g., 0.01 μm or more and 0.05 μm or less, 0.05 μm or more and 0.1 μm or less, 0.1 μm or more and 0.4 μm or less, 0.4 μm or more and 0.5 μm or less, 0.5 μm or more and 0.7 μm or less, 0.7 μm or more and 1 μm or less, 1 μm or more and 1.3 μm or less, 1.3 μm or more and 1.5 μm or less, 1.5 μm or more and 1.8 μm or less, 1.8 μm or more and 2.3 μm or less, 2.3 μm or more and 2.8 μm or less, 2.8 μm or more and 3.3 μm or less, 3.3 μm or more and 4 μm or less, 4 μm or more and 5 μm or less, 5 μm or more and 6 μm or less, 6 μm or more and 7 μm or less, 7 μm or more and 8 μm or less, etc.).

[0101] Illustratively, the base of the base structure formed in step S10 is rectangular, the dimensions of the rectangle are 15 μm×14.5 μm, and the vertical dimension of the base of the base structure is 0.5 μm.

[0102] In step S20, a dielectric layer and a doped conductive layer are sequentially formed on at least a portion of the second surface, the side surface, and the first surface of the silicon substrate, the doped conductive layer being located on the opposite side of the dielectric layer from the silicon substrate, and the doped conductive layer may be a doped polycrystalline silicon layer.

[0103] Specifically, a passivation layer (e.g., silicon oxide or aluminum oxide) is formed by low-pressure chemical vapor deposition (LPCVD) or plasma-enhanced chemical vapor deposition (PECVD), and doping atoms are diffused to form a boron-doped polycrystalline silicon structure and / or a phosphorus-doped polycrystalline silicon structure. The dielectric layer and the doped polycrystalline silicon layer cover the second surface, the side surfaces, and a portion of the first surface.

[0104] The dielectric layers formed in step S20 are the first and second dielectric layers described above.

[0105] In step S20, the doping atom diffusion step is performed at least once, and in some embodiments, the doping atom diffusion step may be performed two or more times.

[0106] In step S30, the dielectric layer and the doped polycrystalline silicon layer located on the first surface are removed, and at least a part of the dielectric layer and the doped polycrystalline silicon layer located on the side in a first region close to the first surface are removed.

[0107] In step S30, the dielectric layer and the doped polycrystalline silicon layer are etched away from the entire first surface and all or part of the side surfaces using a chain etching device.

[0108] Specifically, a silicon substrate on which a dielectric layer and a doped polycrystalline silicon layer have been formed is set in a chain etching apparatus, and the silicon substrate is brought into contact with an etching solution used in the chain etching apparatus with its first surface facing downward, so that the etching solution covers at least a portion of the dielectric layer and the doped polycrystalline silicon layer on the side.

[0109] In some embodiments, the distribution ratio of the first region to the side surface in the direction extending from the first surface to the second surface is 20% or more and 100% or less.

[0110] Illustratively, 85% of the side surface (the side closer to the first surface) is fully in contact with the etching solution, and 15% of the side surface (the side closer to the second surface) is not in contact with the etching solution.

[0111] In step S40, a first region and / or a second region is formed on the side surface.

[0112] The pyramidal structures are formed by alkali texturing, and the size of the pyramidal structures can be controlled by controlling the type of additive and the reaction time to form first and second pyramidal structures, or the first and second pyramidal structures can be formed by stepwise texturing.

[0113] During the alkaline texturing process, the exposed side surface of the silicon substrate is corroded by the alkaline solution, forming a pyramidal structure on the textured surface. On the other hand, the unexposed surface of the silicon substrate is not textured during texturing because the dielectric layer (e.g., silicon oxide) and the alkaline solution hardly react with each other under the process conditions, and the surface of this silicon substrate remains as a base structure.

[0114] For example, during the alkali texturing process, the first surface where the silicon substrate is exposed and 85% of the side surface near the front surface are alkali etched, forming a combined structure of the first texture region and the second texture region. The 15% of the side surface near the back surface is protected by the dielectric layer and the doped polycrystalline silicon layer, so no pyramid structure is formed and the base structure can be observed.

[0115] In step S50, a passivation layer and a reflection reducing layer are formed.

[0116] Specifically, a passivation layer can be deposited on a first surface, a second surface, and multiple side surfaces of a silicon substrate using atomic layer deposition (ALD) to provide a passivation effect. A reflection-reducing layer can be deposited on a first surface, a second surface, and multiple side surfaces of a silicon substrate using plasma-enhanced chemical vapor deposition. The textured pyramid structure on the surface and the combined morphology of the textured pyramids and bases on the side surfaces can be observed after the passivation layer and reflection-reducing layer are formed.

[0117] In step S60, electrodes are formed.

[0118] Specifically, the electrodes can be formed by screen printing. The textured pyramidal structures on the surface and the combined textured pyramidal and base structures on the side can be observed after electrode printing.

[0119] In summary, the side surface of the solar cell in the embodiment of the present application includes a plurality of first pyramid structures, a plurality of second pyramid structures, and a plurality of prism-shaped structures. The first pyramid structures in the first textured region enhance the light trapping effect of the side surface of the solar cell, improving the light utilization efficiency of the solar cell. Furthermore, the second pyramid structures are designed to be formed in the second textured region. The larger structural dimensions of the second pyramid structures provide a larger surface area than the first pyramid structures, providing a larger coating area for subsequent coating and improving coating quality. Therefore, the combined structure of a plurality of first pyramid structures and a plurality of second pyramid structures better balances the passivation and light trapping effects of the side surface of the solar cell, improving the photoelectric conversion efficiency of the solar cell.

[0120] Furthermore, compared to the pyramidal textured surface structure, the prismatic structure of the second textured region has a larger surface area, providing a larger deposition area for the subsequent deposition of a passivation layer. As a result, compared to the single textured surface structure in the related art, the combined structure of the first pyramidal structure, the second pyramidal structure, and the prismatic structure can better achieve both the side passivation function and the light trapping function of the solar cell.

[0121] The above embodiments are only for illustrating the technical solutions of the present application, and are not intended to limit the present application. Although the present application has been described in detail with reference to the above preferred embodiments, it should be understood that those skilled in the art can make modifications or equivalent substitutions to the technical solutions of the present application without departing from the spirit and scope of the technical solutions of the present application. [Explanation of symbols]

[0122] 100 solar cells 10 Silicon substrate 11 Page 1 12 Side 2 13 Side 131 First aspect 132 Second aspect 133 Third aspect 134 Fourth aspect 20 First dielectric layer 30 First doped conductive layer 40 Second dielectric layer 50 second doped conductive layer A1 1st area A11 First texture area A12 Second texture area A2 2nd area T11 Pyramid Structure T12 Prismatic Structure T13 base structure T21 Third Pyramid Structure R recess D1 Thickness direction of silicon substrate

Claims

1. a silicon substrate and a passivation layer, the silicon substrate having opposing first and second surfaces and a plurality of side surfaces connecting the first and second surfaces; At least one of the side surfaces includes a plurality of first texture regions and a plurality of second texture regions, each of the first texture regions including a plurality of first pyramid structures, and each of the second texture regions including a plurality of second pyramid structures; the structural dimension of the second pyramid structure is greater than the structural dimension of the first pyramid structure; the second texture region is between adjacent first texture regions, The solar cell, wherein the passivation layer covers the first textured region and the second textured region on at least one of the side surfaces.

2. The solar cell of claim 1 , wherein the second textured region extends between the first textured regions in one or more of a straight line, a polygonal line, or a curved line.

3. The solar cell described in claim 2, characterized in that the extension direction of the second texture region is not parallel to the thickness direction of the solar cell, and / or the extension directions of at least two of the second texture regions are set parallel.

4. The solar cell according to claim 1 , wherein the structural dimension of the first pyramid structure is in the range of 0.05 μm to 2 μm.

5. The solar cell according to claim 1 , wherein the structural dimension of the second pyramid structure is in the range of 2 μm to 6 μm.

6. 2. The solar cell of claim 1, wherein the side includes a first region, the first region is connected to the first surface, the first texture region and the second texture region are both provided in the first region, and the width of the first region occupies 20% or more and 100% or less of the width of the side.

7. The solar cell of claim 1, characterized in that the side surface includes a first region and a second region, the first texture region and the second texture region are both provided in the first region, and the second region is connected to the second surface side.

8. 8. The solar cell according to claim 7, wherein the boundary between the first region and the second region is a curved line, and a depression is provided in the second region at a position close to the boundary line.

9. 9. The solar cell according to claim 8, wherein the width of the region where the recess is provided in the thickness direction of the silicon substrate is 0% to 60% of the width of the second region.

10. The solar cell of claim 8, wherein the shape of the depression includes one or more of an inverted pyramid shape, an inverted hemisphere shape, and a stepped shape, and / or the cross-sectional area of ​​the depression gradually increases along a direction perpendicular to the side surface.

11. 9. The solar cell according to claim 8, wherein the diameter of the cross section of the recess on the side surface is 0.1 μm or more and 5 μm or less, and / or the depth of the recess is 0.05 μm or more and 2 μm or less.

12. 2. The solar cell of claim 1, wherein, in a direction away from the silicon substrate, the passivation layer comprises, in sequence, an aluminum oxide layer and a silicon nitride layer.

13. A solar module comprising a plurality of solar cells electrically connected to each other, the solar cells being the solar cells according to any one of claims 1 to 12.

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