Solar cells and photovoltaic modules

Abstract

The application provides a solar cell and a photovoltaic module, and relates to the technical field of photovoltaics. The solar cell comprises a cell body, the cell body comprising: a first surface and a second surface opposite in the thickness direction thereof, and a side surface connecting the first surface and the second surface, the side surface comprising: a cut surface and a non-cut surface; a cut surface passivation layer formed on the cut surface, the cut surface passivation layer having a plurality of first microstructures protruding in a direction away from the cell body. In the application, firstly, the hydrogen content in the cut surface passivation layer is relatively high, and the hydrogen passivation effect and the field passivation effect are both good; secondly, the protruding first microstructures have uneven surfaces, which can improve the light trapping effect of the cut surface passivation layer; and thirdly, the protruding first microstructures can also play a role in dispersing stress, avoiding stress concentration and reducing the risk of cracking or breaking.

Description

Technical Field

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

[0002] Currently, solar cells are typically sliced ​​after the entire cell is fabricated to obtain multiple sliced ​​solar cells, such as two-slice, three-slice, four-slice, eight-slice, and sixteen-slice cells. Alternatively, the semiconductor substrate can be cut before fabricating sliced ​​solar cells. Interconnecting these slices helps reduce power loss. However, the cut surfaces of sliced ​​solar cells contain numerous broken bonds and severe recombination, resulting in a loss of photoelectric conversion efficiency.

[0003] To address the impact of dicing on efficiency, a passivation layer is deposited on the diced surface of solar cells to suppress carrier recombination and reduce efficiency loss. However, the passivation effect of the diced surface in existing solar cells is unsatisfactory, affecting the performance of the solar cells. Summary of the Invention

[0004] This invention provides a solar cell and a photovoltaic module, which aims to solve the problem of poor passivation effect of the cut surface in existing solar cells.

[0005] In a first aspect, the present invention provides a solar cell, comprising: a cell body, the cell body including: a first surface and a second surface opposite to each other along its thickness direction, and a side surface connecting the first surface and the second surface, the side surface including: a cut surface and a non-cut surface;

[0006] A passivation layer is formed on the cut surface, the passivation layer having a plurality of first microstructures protruding in a direction away from the battery body.

[0007] In this application, the passivation layer of the cut surface has multiple first microstructures protruding in a direction away from the battery body. These first microstructures can protrude in a direction away from the passivation layer and the battery body. The reason for the formation of these first microstructures is that the passivation layer of the cut surface has a large thickness, high film quality, and high hydrogen content. When heated, the passivation layer easily forms first microstructures due to hydrogen accumulation or escape, indicating that the passivation layer of the cut surface has a high hydrogen content, good film quality, and a large thickness. Therefore, firstly, the passivation layer of the cut surface has a high hydrogen content, resulting in good hydrogen passivation and field passivation effects; secondly, the aforementioned protruding first microstructures have an uneven surface, which can improve the light-trapping effect of the passivation layer of the cut surface; and thirdly, the aforementioned protruding first microstructures can also disperse stress, avoiding stress concentration and reducing the risk of cracking or breakage.

[0008] In some possible embodiments, the cutting surface includes: a first region adjacent to the first surface and a second region away from the first surface, wherein the distribution density of the first microstructure located at least partially in the first region is greater than the distribution density of the first microstructure located at least partially in the second region.

[0009] In some possible embodiments, the one-dimensional average size of the first microstructure located at least partially in the first region is greater than the one-dimensional average size of the first microstructure located at least partially in the second region; the direction of the one-dimensional average size is perpendicular to the direction of the height of the first microstructure.

[0010] In some possible embodiments, the area ratio of the first microstructure in the first region is greater than the area ratio of the first microstructure in the second region.

[0011] In some possible embodiments, the cut surface has a groove structure, and at least a portion of the first microstructure is arranged along the extension direction of the groove structure.

[0012] In some possible embodiments, the cut surface passivation layer further includes: an extension portion extending to the edge region of the first surface near the cut surface and / or the edge region of the second surface near the cut surface;

[0013] Along the direction from the edge of the first surface to the center of the first surface, the edge region of the first surface includes: a third region close to the cut surface and a fourth region away from the cut surface; a first sub-extension located in the third region of the extension has a plurality of second microstructures protruding in a direction opposite to the battery body; and / or,

[0014] Along the direction from the edge of the second surface to the center of the second surface, the edge region of the second surface includes: a fifth region close to the cut surface and a sixth region away from the cut surface, and the second sub-extension located in the fifth region of the extension has a plurality of second microstructures protruding in a direction away from the battery body.

[0015] In some possible embodiments, the third sub-extension of the extension located in the fourth region has a plurality of second microstructures protruding in a direction away from the battery body, and / or, the fourth sub-extension of the extension located in the sixth region has a plurality of second microstructures protruding in a direction away from the battery body.

[0016] The distribution density of the second microstructure in the third sub-extension is less than the distribution density of the second microstructure in the first sub-extension; and / or,

[0017] The distribution density of the second microstructure in the fourth sub-extension is less than the distribution density of the second microstructure in the second sub-extension.

[0018] In some possible embodiments, the one-dimensional size of the first microstructure is 0.1-10 μm.

[0019] In some possible embodiments, the height of the first microstructure is 20-500 nm in the direction perpendicular to the cut surface.

[0020] In some possible embodiments, an uneven anti-reflection structure is formed on the cut surface at a position corresponding to the first microstructure.

[0021] In some possible embodiments, along the width direction of the solar cell, the width of the extension is W1, the width of the solar cell is W2, 0 < W1 ≤ 5%W2; and / or, 0 < W1 ≤ 5mm; and / or,

[0022] The solar cell further includes a plurality of current-collecting electrodes disposed on the first surface and / or the second surface. The plurality of current-collecting electrodes are spaced apart along the width direction and extend along the length direction of the solar cell, the length direction being perpendicular to the width direction. The extended portion covers 0-5 of the current-collecting electrodes; and / or,

[0023] The solar cell further includes a plurality of interconnects, which are arrayed on at least one of the first surface and the second surface. The plurality of interconnects include a plurality of first edge interconnects near the cut surface. The distance between the extended portion and any one of the plurality of first edge interconnects along the width direction is greater than or equal to 0.1 mm.

[0024] In some possible embodiments, the first microstructure is a bulge structure that protrudes in a direction away from the battery body; and / or, the first microstructure is an opening structure that protrudes in a direction away from the battery body; and / or, the first microstructure is a microstructure that protrudes in a direction away from the battery body and has cyclone-shaped edges.

[0025] In some possible embodiments, the battery body includes:

[0026] Semiconductor substrate,

[0027] A first doped layer and a second doped layer are disposed on the back surface of the semiconductor substrate, and the first doped layer and the second doped layer have opposite conductivity.

[0028] Two surface passivation layers, one of which is disposed on the light-facing surface of the semiconductor substrate, and the other of which is disposed on the first doped layer and the second doped layer;

[0029] Two antireflection layers, one of which is disposed on the surface passivation layer of the light-facing side of the semiconductor substrate, and the other of which is disposed on the surface passivation layers of the first doped layer and the second doped layer;

[0030] The passivation layer on the light-facing side of the semiconductor substrate has a third microstructure protruding in a direction perpendicular to and away from the semiconductor substrate, and the passivation layer on the back-light-facing side of the semiconductor substrate has a fourth microstructure protruding in a direction perpendicular to and away from the semiconductor substrate.

[0031] In some possible embodiments, the first surface is the backlight surface of the battery body; along the direction from the edge of the first surface to the center of the first surface, the edge region of the first surface includes: a third region close to the cut surface and a fourth region away from the cut surface;

[0032] The third region includes a first step structure recessed into the battery body along the thickness direction; neither the first doped layer nor the second doped layer extends into the third region.

[0033] In some possible embodiments, of the first doped layer and the second doped layer, one is a P-type doped layer and the other is an N-type doped layer;

[0034] In the surface passivation layer on the backlight side of the semiconductor substrate: the maximum one-dimensional dimension of the fourth microstructure at the position corresponding to the P-type doped layer is greater than the maximum one-dimensional dimension of the fourth microstructure at the position corresponding to the N-type doped layer; and / or,

[0035] In the surface passivation layer on the backlight side of the semiconductor substrate: the maximum one-dimensional dimension of the fourth microstructure at the position corresponding to the P-type doped layer is greater than the maximum one-dimensional dimension of the first microstructure, and / or

[0036] The maximum average size of the fourth microstructure is greater than the maximum one-dimensional size of the third microstructure.

[0037] In some possible embodiments, the battery body includes: a semiconductor substrate;

[0038] A first doped layer and a second doped layer are disposed on opposite surfaces of the semiconductor substrate along the thickness direction of the semiconductor substrate, and the first doped layer and the second doped layer have opposite conductivity.

[0039] Two surface passivation layers, one of which is disposed on the first doped layer and the other of which is disposed on the second doped layer;

[0040] Two antireflection layers, one of which is disposed on a surface passivation layer on the first doped layer, and the other of which is disposed on a surface passivation layer on the second doped layer;

[0041] The surface passivation layer located on the first doped layer has a third microstructure protruding in a direction perpendicular to and away from the semiconductor substrate, and the surface passivation layer located on the second doped layer has a fourth microstructure protruding in a direction perpendicular to and away from the semiconductor substrate.

[0042] In some possible embodiments, the first surface is the light-facing surface of the battery body, the first doped layer is located on the light-facing side of the semiconductor substrate, and the second doped layer is located on the back-light side of the semiconductor substrate.

[0043] Along the direction from the edge of the second surface to the center of the second surface, the edge region of the second surface includes: a fifth region close to the cut surface and a sixth region away from the cut surface; the fifth region includes a second stepped structure recessed into the battery body along the thickness direction of the battery body, and the second doped layer does not extend into the fifth region; and / or,

[0044] Along the direction from the edge of the first surface to the center of the first surface, the edge region of the first surface includes: a third region close to the cut surface and a fourth region away from the cut surface; the third region includes a third step structure recessed into the battery body along the thickness direction of the battery body, and the first doped layer does not extend into the third region.

[0045] In some possible embodiments, the first surface is the light-facing surface of the battery body, the first doped layer is located on the light-facing side of the semiconductor substrate, and the second doped layer is located on the back-light side of the semiconductor substrate.

[0046] The maximum one-dimensional dimension of the third microstructure is greater than the maximum one-dimensional dimension of the fourth microstructure; and / or,

[0047] The maximum one-dimensional dimension of the third microstructure is greater than that of the maximum one-dimensional dimension of the first microstructure.

[0048] In some possible embodiments, the battery body further includes: a surface passivation layer located on the first surface and / or the second surface and a hydrogen-containing antireflection layer disposed on the surface passivation layer; the extended portion, the hydrogen-containing antireflection layer, and the surface passivation layer constitute an edge passivation stack; and / or,

[0049] The surface passivation layer and the cut surface passivation layer are both combinations of one or more of the following: aluminum oxide layer, silicon nitride layer, silicon oxide layer, silicon oxynitride layer, intrinsic amorphous silicon layer, intrinsic microcrystalline silicon layer, doped amorphous silicon layer, or doped microcrystalline silicon layer.

[0050] A second aspect of the present invention provides a photovoltaic module, comprising:

[0051] A battery string, wherein the battery string is formed by connecting a plurality of solar cells as described above;

[0052] An encapsulation layer is used to cover the surface of the battery string;

[0053] A cover plate is used to cover the surface of the encapsulation layer away from the battery string.

[0054] The aforementioned solar cells and photovoltaic modules have the same or similar beneficial effects, and will not be repeated here to avoid repetition. Attached Figure Description

[0055] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figures 1 to 4 The following are schematic diagrams illustrating the structures of four types of solar cells in embodiments of the present invention;

[0057] Figure 5 A perspective structural diagram of the cut surface in an embodiment of the present invention is shown;

[0058] Figure 6 Several structural schematic diagrams of the first microstructure in embodiments of the present invention are shown;

[0059] Figure 7 A front view of the structure on the cut surface in an embodiment of the present invention is shown;

[0060] Figure 8 A schematic diagram of the first or second side in an embodiment of the present invention is shown.

[0061] Explanation of the attached drawing numbers:

[0062] 1-Semiconductor substrate, 10-Solar cell, 11-First surface, 111-Edge region of the first and second surfaces near the cut surface, 1111-Third region, 1112-Fourth region, 12-Second surface, 13-Cut surface, 131-First region, 132-Second region, 133-Trench structure, 14-Uncut surface, 15-Interconnect, 2-Cut surface passivation layer, 21-First microstructure, 22-Extension, 221-First sub-extension, 222-Second microstructure, 223-Second sub-extension, 224-Third sub-extension, 225-Fourth sub-extension, 3-Antireflection structure, 4-Collector electrode, 5-First doped layer, 6-Second doped layer, 7-Surface passivation layer, 71-Third microstructure, 72-Fourth microstructure, 8-Antireflection layer. Detailed Implementation

[0063] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] This invention provides a solar cell, with reference to... Figure 1The solar cell includes a first surface 11 and a second surface 12 opposite to each other along its thickness direction L1, and a side surface connecting the first surface 11 and the second surface 12. The side surface includes a cut surface 13 and a non-cut surface 14. Of the first surface 11 and the second surface 12, one is the light-facing surface of the solar cell, and the other is the back-facing surface. For example, the first surface 11 can be the light-facing surface of the solar cell, and the second surface 12 can be the back-facing surface, or the first surface 11 can be the back-facing surface, and the second surface 12 can be the light-facing surface. During normal operation of the solar cell, the surface that primarily receives light is its light-facing surface, and the back-facing surface is opposite to the light-facing surface. The solar cell contains a PN junction, which can generate, separate, and collect charge carriers or current. The side surface connects the light-facing surface and the back-facing surface of the solar cell. A cut surface refers to a newly generated surface during the process of cutting a whole solar cell or a whole semiconductor substrate into sliced ​​solar cells or sliced ​​semiconductor substrates using methods such as laser cutting. A non-cut surface is an existing side surface in the whole solar cell or the whole semiconductor substrate. The non-cut surface here can also be a surface formed by cutting a silicon rod or similar material with diamond wire. It should be noted that the solar cells mentioned in this application are either solar cells formed by cutting the entire semiconductor substrate, or solar cells formed from a single sheet of solar cells and then sliced; both are within the scope of protection of this application. The degree of defects or cutting damage on the non-cut surface is significantly less than that on the cut surface.

[0065] In this application, a cut surface passivation layer 2 is formed on the cut surface 13. The cut surface passivation layer 2 can passivate defects generated by cutting on the cut surface, such as recombination centers, and prevent charge carriers generated by the semiconductor substrate near the cut surface from recombining with the recombination centers nearby.

[0066] This application does not limit the type of solar cell; see reference. Figure 2 and Figure 3 This could be a bifacial solar cell with electrode structures on both sides, such as a TOPCon cell. Or refer to... Figure 4 It can be a back-contact solar cell with all electrode structures located on the back surface, without specific limitations. The solar cell can be divided into two, three, or four sections, etc., without limitation on the specific sectioning method of the cell.

[0067] Reference Figures 1 to 5 The passivation layer 2 of the cut surface has a plurality of first microstructures 21 protruding in a direction away from the battery body. The first microstructures 21 may protrude in a direction L2 away from the passivation layer 2 of the cut surface and in a direction away from the battery body, or refer to Figures 1 to 4The formation of the first microstructure 21 here is due to the large thickness of the passivation layer 2, the high quality of the passivation layer 2, and the high hydrogen content in the passivation layer 2. When heated, the passivation layer 2 easily forms the first microstructure 21 due to hydrogen accumulation or escape, indicating a high hydrogen content, good film quality, and large thickness. Therefore, firstly, the high hydrogen content in the passivation layer 2 results in good hydrogen passivation and field passivation effects; secondly, the uneven surface of the protruding first microstructure 21 enhances the light-trapping effect of the passivation layer 2; and thirdly, the protruding first microstructure 21 also disperses stress, preventing stress concentration and reducing the risk of cracking or breakage.

[0068] It should be noted that the first microstructure 21 of the cut surface passivation layer 2 on the cut surface of the solar cell can be observed by 3D microscope or SEM, and other detection and determination methods are not limited.

[0069] In some possible embodiments, refer to Figure 7 The cut surface 13 includes a first region 131 adjacent to the first surface 11 and a second region 132 away from the first surface 11. The distribution density of the first microstructure 21, at least partially located in the first region 131, is greater than the distribution density of the first microstructure 21, at least partially located in the second region 132. Specifically, the greater the thickness of the passivation layer 2, the higher the quality of the film layer, and the higher the hydrogen content in the passivation layer 2, the easier it is for hydrogen to accumulate or escape after being heated, thus forming the first microstructure 21. This indicates that within at least a portion of the first region 131 adjacent to the first surface 11, the passivation layer 2 has a greater thickness, higher film quality, and higher hydrogen content. The passivation and hydrogen passivation effects within this region are both better, and the light trapping and stress dispersion effects are also superior. In contrast, the passivation effect of at least a portion of the second region 132, located further from the first surface 11, is slightly weaker. This can be applied to scenarios where different regions of the cut surface have different passivation requirements, or in other words, to scenarios where the first region of the cut surface has a better passivation requirement.

[0070] It should be noted that the relative sizes of the first region 131 and the second region 132 are not limited here. The difference between the two distribution densities is also not specifically limited. The distribution density of the first microstructure 21 within the first region can be determined as follows: within a predetermined area of ​​the first region 131, count the number of first microstructures 21 within that predetermined area, and divide that number by the area of ​​the predetermined area to obtain the distribution density of the first microstructure 21 within the first region; or, within a predetermined area of ​​the first region 131, count the total area of ​​the projections of the first microstructures 21 within that predetermined area, and divide that total area by the area of ​​the predetermined area to obtain the distribution density of the first microstructure 21 within the first region. Here, "projection" refers to the projection of the first microstructure 21 when illuminated by light perpendicular to the cutting surface 13. The method for determining the distribution density of the first microstructure 21 within the second region is similar. In determining the distribution density in both cases, the areas of the selected regions can be the same or different, and this is not specifically limited. The size of this region is not limited; for example, it can be 5×5μm, 10×10μm, etc.

[0071] In some possible embodiments, refer to Figure 7 The cut surface 13 includes a first region 131 adjacent to the first surface 11 and a second region 132 away from the first surface 11. The area ratio of the first microstructure 21 located in the first region 131 is greater than the area ratio of the first microstructure 21 located in the second region 132. Specifically, the greater the thickness of the passivation layer 2, the higher the quality of the film layer, and the higher the hydrogen content in the passivation layer 2, the easier it is for hydrogen to accumulate or escape after being heated, thus forming the first microstructure 21. This indicates that within at least a portion of the first region 131 adjacent to the first surface 11, the passivation layer 2 has a greater thickness, higher film quality, and higher hydrogen content. The passivation and hydrogen passivation effects within this region are both better, and the light trapping and stress dispersion effects are also superior. In contrast, the passivation effect of at least a portion of the second region 132, located further from the first surface 11, is slightly weaker. This can be applied to scenarios where different regions of the cut surface have different passivation requirements, or in other words, to scenarios where the first region of the cut surface has a better passivation requirement.

[0072] It should be noted that the area ratio of the first microstructure 21 in the first region here can refer to the area ratio of the projection of the first microstructure 21 in the first region. The first region can be illuminated with light perpendicular to the cutting surface 13, and the area of ​​the projection of the first microstructure 21 in the first region is the area of ​​the first microstructure 21 in the first region. The area ratio of the first microstructure 21 in the first region can be determined by summing the areas of the projections of the first microstructure 21 within a predetermined area in the first region, and then dividing this sum by the predetermined area of ​​the region. The method for determining the area ratio of the first microstructure 21 in the second region is similar. The areas of the selected regions can be the same or different, and there is no specific limitation on this. The difference between the two area ratios is also not specifically limited. The size of the region is not limited; for example, it can be 5×5μm, 10×10μm, etc.

[0073] In some possible embodiments, of the first surface 11 and the second surface 12, one is a light-facing surface and the other is a backlighting surface; the first region here can be the region of the cut surface immediately adjacent to the light-facing surface, and the second region here can be the second region of the cut surface far from the light-facing surface. That is, the cut surface 13 includes: a first region immediately adjacent to the light-facing surface and a second region far from the light-facing surface; the one-dimensional average size of the first microstructure 21 at least partially located in the first region is larger than the one-dimensional average size of the first microstructure 21 at least partially located in the second region; the direction of the one-dimensional average size is perpendicular to the direction of the height of the first microstructure 21. Specifically, the one-dimensional average size of the first microstructure 21 in the first region is larger, and the light-trapping effect of the first region is better; at the same time, the first region is closer to the light-facing surface, and during the normal operation of the solar cell, its light mainly comes from the light-facing surface. Therefore, this application can further improve the light-trapping effect.

[0074] It should be noted that the relative sizes of the first and second regions are not limited here. The difference between the two one-dimensional average dimensions is also not specifically limited. The first region can be illuminated with light perpendicular to the cutting plane 13. The dimensions of the projection of the first microstructure 21 within the first region in two mutually perpendicular directions are the one-dimensional dimensions of the first microstructure 21 within the first region. This one-dimensional dimension is defined as the maximum dimension on the projection plane, and may include, for example, the length and width of the projection, where the length is the maximum dimension of the projection, and the direction of the width is perpendicular to the direction of the length. The one-dimensional average size of the first microstructure 21 within the first region can be determined as follows: Within a predetermined area within the first region, the sum of the projected lengths of the first microstructure 21 within that predetermined area is calculated. The sum of these lengths is then divided by the predetermined area of ​​the region to obtain the one-dimensional average size of the first microstructure 21 within the first region. Alternatively, the one-dimensional average size of the first microstructure 21 within the first region can be determined as follows: Within a predetermined area within the first region, the sum of the projected widths of the first microstructure 21 within that predetermined area is calculated. The sum of these widths is then divided by the predetermined area of ​​the region to obtain the one-dimensional average size of the first microstructure 21 within the first region. Alternatively, the one-dimensional average size of the first microstructure 21 within the first region can be determined as follows: Within a predetermined area within the first region, the sum of the projected length and width of the first microstructure 21 within that predetermined area is calculated. The sum of these lengths and widths is then divided by the predetermined area of ​​the region to obtain the one-dimensional average size of the first microstructure 21 within the first region. The method for determining the one-dimensional average size of the first microstructure 21 in the second region is similar. In the process of determining the one-dimensional average size, the area of ​​the selected region can be the same or different, and there is no specific limitation on this. The size of the region is not limited; for example, it can be 5×5μm, 10×10μm, etc.

[0075] In some possible embodiments, refer to Figure 7The cut surface 13 has a trench structure 133, and at least a portion of the first microstructure 21 is arranged along the extension direction of the trench structure 133. The trench structure 133 here can be a line mark attached to the surface of the semiconductor substrate, or it can be a location where stress is concentrated during the dicing process; no specific limitation is made. The distribution location of the first microstructure 21 results in a thicker, higher-quality, and higher hydrogen content in the passivation layer 2 on the cut surface. Therefore, the passivation and hydrogen passivation effects along the extension direction of the trench structure 133 are better, and the light-trapping and stress-dispersing effects are also better. The location of the trench structure 133 usually has many defects and stress concentration. Therefore, the arrangement of some of the first microstructures 21 along the extension direction of the trench structure 133 can fully passivate the defects at the location of the trench structure 133, significantly disperse the stress at the location of the trench structure 133, significantly improve the passivation effect at the location of the trench structure 133, and significantly reduce the risk of microcracks at the location of the trench structure 133, further improving the performance of the solar cell.

[0076] It should be noted that the above-mentioned groove structure 133 extends in a certain direction as a whole, but its local parts are allowed to bend in other directions.

[0077] In some possible embodiments, refer to Figure 6 The one-dimensional dimension d1 of the first microstructure 21 is 0.1-10 μm. If the one-dimensional dimension d1 of the first microstructure 21 is too small, it indicates that the hydrogen content in the passivation layer 2 of the cut surface is low, resulting in poor hydrogen passivation effect. If the one-dimensional dimension d1 of the first microstructure 21 is too large, it may cause excessive damage to the passivation layer 2 of the cut surface, thus affecting the passivation effect. Therefore, if the one-dimensional dimension d1 of the first microstructure 21 is within the above range, it can not only ensure a good hydrogen passivation effect of the passivation layer 2 of the cut surface, but also minimize the damage to the passivation layer 2 of the cut surface. The one-dimensional dimension d1 of the first microstructure 21 can be further 1-4 μm, which can further ensure a good hydrogen passivation effect of the passivation layer 2 of the cut surface, and minimize the damage to the passivation layer 2 of the cut surface.

[0078] For example, the one-dimensional size d1 of the first microstructure 21 can be 0.1μm, 0.5μm, 0.8μm, 1μm, 1.1μm, 1.2μm, 1.5μm, 1.9μm, 2μm, 2.1μm, 2.5μm, 2.7μm, 3μm, 3.3μm, 3.5μm, 3.7μm, 4μm, 4.3μm, 4.5μm, 4.8μm, 5μm, 5.3μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, or 10μm.

[0079] The first microstructure 21 can be illuminated by light perpendicular to the cut surface 13, and the size of the projection of the first microstructure 21 is the one-dimensional dimension here. The size of the projection of the first microstructure 21 can include length and width, with the length being greater than or equal to the width. The one-dimensional dimension of the first microstructure can be the length or width of the projection, or the average of the lengths of two or more projections, or the average of the widths of two or more projections; there is no limitation in this regard. For example, Figure 6 In the diagram, the one-dimensional dimension d1 of the first microstructure 21 can be the length of the projection of the first microstructure 21.

[0080] In some possible embodiments, refer to Figure 5 In the direction perpendicular to the cut surface 13 (as shown in L2), the height h1 of the first microstructure 21 is 20-500 nm. If the height h1 of the first microstructure 21 is too small, it indicates that the hydrogen content in the passivation layer 2 of the cut surface is low, resulting in poor hydrogen passivation effect of the passivation layer 2. If the height h1 of the first microstructure 21 is too large, it may cause too much damage to the passivation layer 2 of the cut surface, thus affecting the passivation effect of the passivation layer 2. Therefore, the height h1 of the first microstructure 21 within the above range can not only ensure a good hydrogen passivation effect of the passivation layer 2 of the cut surface, but also minimize the damage to the passivation layer 2 of the cut surface. The height h1 of the first microstructure 21 can be further 180-280 nm, which can further ensure a good hydrogen passivation effect of the passivation layer 2 of the cut surface, and minimize the damage to the passivation layer 2 of the cut surface.

[0081] For example, the height h1 of the first microstructure 21 can be 20nm, 50nm, 90nm, 100nm, 120nm, 150nm, 180nm, 200nm, 230nm, 250nm, 280nm, 300nm, 320nm, 350nm, 400nm, 450nm, or 500nm.

[0082] The height h1 of the first microstructure 21 refers to the distance from the surface of the passivation layer 2 away from the cutting surface 13 to the point in the first microstructure 21 furthest from the cutting surface 13, or the average of two or more such distances of the first microstructure 21. This application does not make a specific limitation on this.

[0083] In some possible embodiments, refer to Figure 5On the cut surface 13, an uneven anti-reflection structure 3 is formed at the position corresponding to the first microstructure 21, thereby providing a good light-trapping effect for the cut surface. It should be noted that if the first microstructure 21 is not open at the position furthest from the cut surface 13, the anti-reflection structure 3 may or may not be open at that position; conversely, if the first microstructure 21 is open at the position furthest from the cut surface 13, the anti-reflection structure 3 may or may not be open at that position, without limitation. When the anti-reflection structure 3 is not open at the position furthest from the cut surface 13, it can accommodate escaping hydrogen. This hydrogen can passivate defects within the solar cell along the gaps within the solar cell, further improving the passivation effect.

[0084] The specific material of the antireflection structure 3 is not limited. For example, it can be silicon nitride, silicon oxynitride, etc.

[0085] In some possible embodiments, refer to Figure 6 In (a), the first microstructure 21 is a bulge structure that protrudes along a direction away from the battery body (as shown in L2) or along a direction away from the cut surface. In this case, the surface of the bulge structure may have microcracks or no microcracks. These microcracks can provide a channel for hydrogen to escape. When the surface of the bulge structure may have no microcracks or few microcracks, most of the escaped hydrogen remains within the bulge structure. This portion of hydrogen can passivate defects in the solar cell along the gaps within the solar cell, further improving the passivation effect. The aforementioned bulge structure can also optimize light trapping and reduce the risk of microcracks.

[0086] In some possible embodiments, refer to Figure 6 (b) The first microstructure 21 is an opening structure that protrudes along the direction away from the battery body or along the direction away from the cut surface, indicating that the hydrogen content in the passivation layer 2 of the cut surface is relatively high, which can play a good hydrogen passivation effect on the cut surface, and can improve the light trapping effect and reduce the risk of microcracks.

[0087] In some possible embodiments, refer to Figure 6 (c) The first microstructure 21 is a microstructure that protrudes along the direction away from the battery body or along the direction away from the cut surface and has a cyclone-like edge. At this time, the first microstructure 21 presents a morphology like that of a fluid rotating around a straight or curved axis in a certain direction, indicating that the hydrogen content in the passivation layer 2 of the cut surface is relatively high, which can play a good hydrogen passivation effect on the cut surface, and can improve the light trapping effect and reduce the risk of microcracks.

[0088] It should be noted that the above-mentioned open structure and cyclone-type microstructure are both structures formed by the high hydrogen content in the cut surface passivation layer 2, where the hydrogen ion content is sufficient to escape from the cut surface passivation layer 2 without hydrogen passivation, resulting in a burst film formation.

[0089] In some possible embodiments, refer to Figures 1 to 4 The passivation layer 2 further includes an extension portion 22 extending to the edge region of the first surface 11 near the cut surface 13 and / or the edge region of the second surface 12 near the cut surface 13. The extension portion 22 can provide good passivation supplementation for the first surface 11 and the second surface 12.

[0090] In some possible embodiments, refer to Figures 2 to 4 Along the direction from the edge of the first surface 11 to its center, the edge region 111 of the first surface 11 includes a third region 1111 near the cut surface 13 and a fourth region 1112 away from the cut surface 13. The first sub-extension 221 of the extension 22, located in the third region 1111, has multiple second microstructures 222 protruding in a direction opposite to the battery body or in a direction opposite to the first surface 11. The formation reason and morphology of these second microstructures 222 are the same as or similar to those of the first microstructure 21; therefore, to avoid repetition, they will not be described further. Specifically, the third region 1111 is closer to the cutting surface 13, and the risk of defects and microcracks in the third region 1111 is greater than that in the fourth region 1112. Therefore, in this application, the first sub-extension 221 located in the third region 1111 of the extension portion 22 has a greater thickness, higher film quality, and higher hydrogen content. The first sub-extension 221 located in the third region 1111 has a better field passivation and hydrogen passivation effect on the third region 1111, and also has a better light trapping effect and stress dispersion effect.

[0091] It should be noted that the relative sizes of the third region 1111 and the fourth region 1112 are not limited here. The aforementioned second microstructure 222 can be observed and detected using methods such as 3D microscopy or SEM.

[0092] It should be noted that the second microstructure 222 in the extension portion 22 may be only the microstructure formed by hydrogen accumulation or escape after the extension portion is heated; or it may be the microstructure formed by hydrogen accumulation or escape after the surface passivation layer inside is heated; or it may be a combination of both, without limitation.

[0093] In some possible embodiments, refer to Figures 1 to 4 The passivation layer 2 further includes an extension portion 22 extending to the edge region of the first surface 11 near the cut surface 13 and / or the edge region of the second surface 12 near the cut surface 13. (See reference...) Figures 3 to 4Along the direction from the edge of the second surface 12 to its center, the edge region 111 of the second surface 12 includes a fifth region 1113 near the cut surface 13 and a sixth region 1114 away from the cut surface 13. The second sub-extension 223 located in the fifth region 1113 of the extension 22 has multiple second microstructures 222 protruding in a direction away from the battery body or away from the second surface 12. The formation reason and morphology of these second microstructures 222 are the same as or similar to those of the first microstructure 21, and will not be described again to avoid repetition. Specifically, the fifth region 1113 is closer to the cutting surface 13, and the risk of defects and microcracks in the fifth region 1113 is greater than that in the sixth region 1114. Therefore, in this application, the second sub-extension 223 located in the fifth region 1113 of the extension portion 22 has a greater thickness, higher film quality, and higher hydrogen content. The second sub-extension 223 located in the fifth region 1113 has a better field passivation and hydrogen passivation effect on the fifth region 1113, and also has a better light trapping effect and stress dispersion effect.

[0094] It should be noted that the relative sizes of the fifth region 1113 and the sixth region 1114 are not limited here.

[0095] In some possible embodiments, refer to Figure 2 The third sub-extension 224 located in the fourth region 1112 of the extension portion 22 has multiple second microstructures 222 protruding in a direction opposite to the battery body or in a direction opposite to the first surface 11. The formation reason and morphology of the second microstructure 222 are the same as or similar to the first microstructure 21, and will not be described again to avoid repetition. In this application, the third sub-extension 224 located in the fourth region 1112 of the extension portion 22 can also provide good field passivation and hydrogen passivation effects to the fourth region 1112, and the light trapping effect and stress dispersion effect are also better.

[0096] In some possible embodiments, the distribution density of the second microstructure 222 of the third sub-extension 224 located in the fourth region 1112 of the extension portion 22 is less than the distribution density of the second microstructure 222 of the first sub-extension 221. Specifically, the third region 1111 is closer to the cutting surface 13, and the risk of defects and microcracks in the third region 1111 is greater than that in the fourth region 1112. Therefore, in this application, the distribution density of the second microstructure 222 of the first sub-extension 221 located in the third region 1111 of the extension portion 22 is greater, resulting in a greater thickness, higher film quality, and higher hydrogen content in the first sub-extension 221. The first sub-extension 221 located in the third region 1111 has better field passivation and hydrogen passivation effects on the third region 1111, and also better light trapping and stress dispersion effects.

[0097] The distribution density of the second microstructure 222 in the third sub-extension 224 located in the fourth region 1112 of extension 22 can be determined by: taking a predetermined area region in the third sub-extension 224, counting the number of second microstructures 222 within this area region, and dividing the number by the area of ​​this area region; or, taking a predetermined area region in the third sub-extension 224, counting the sum of the projected areas of the second microstructures 222 within this area region, and dividing the sum of the projected areas by the area of ​​this area region. The size of this area region is not limited; for example, it can be 5μm × 5μm or 10μm × 10μm. The method for determining the distribution density of the second microstructure 222 in the first sub-extension 221 located in the third region 1111 of extension 22 is similar or the same, and will not be repeated here to avoid repetition. It should be noted that the size of the selected area region can be the same or different during the determination of the distribution density of both methods, and this is not limited. The specific difference in distribution density between the two methods is not limited.

[0098] In some possible embodiments, the distribution density of the second microstructure 222 of the fourth sub-extension 225 located in the sixth region 1114 of the extension portion 22 is less than the distribution density of the second microstructure 222 of the second sub-extension 223. Specifically, the fifth region 1113 is closer to the cutting surface 13, and the risk of defects and microcracks in the fifth region 1113 is greater than that in the sixth region 1114. Therefore, in this application, the distribution density of the second microstructure 222 of the second sub-extension 223 located in the fifth region 1113 of the extension portion 22 is greater, resulting in a greater thickness, higher film quality, and higher hydrogen content in the second sub-extension 223. The second sub-extension 223 located in the fifth region 1113 has better field passivation and hydrogen passivation effects on the fifth region 1113, and also better light trapping and stress dispersion effects.

[0099] The method for determining the distribution density of the second microstructure 222 of the fourth sub-extension 225 located in the sixth region 1114 of extension 22 is similar to or the same as the method for determining the distribution density of the second microstructure 222 of the third sub-extension 224 located in the fourth region 1112 of extension 22. To avoid repetition, it will not be described again here. The specific difference between the two distribution densities is not limited.

[0100] In some possible embodiments, refer to Figure 1The width of the extension portion 22 is less than or equal to 5 mm. An excessively large W1 may interfere with other structures on the first surface 11 and the second surface 12, for example, it may affect current collection and conductive interconnection. Therefore, the width W1 of the extension portion 22 on the first surface 11 and the second surface 12 is less than or equal to 5 mm. This not only provides good passivation for the first surface 11 and the second surface 12, but also does not interfere with the structures on the first surface 11 and the second surface 12. Further, W1 can be from 1 mm to 3 mm. The conductive interconnection here can refer to welding or conductive backplane interconnection, etc., and is not limited thereto.

[0101] For example, the width W1 of the extension portion 22 on the first surface 11 and the second surface 12 can be 5mm, 4.8mm, 4.5mm, 4.2mm, 4mm, 3.9mm, 3.8mm, 3.5mm, 3.2mm, 3mm, 2.8mm, 2.5mm, 2.2mm, 2mm, 1.8mm, 1.5mm, 1.2mm, 1mm, 0.9mm, 0.8mm, 0.5mm, 0.2mm, or 0.05mm.

[0102] The width W1 of the extension portion 22 on the first surface 11 and the second surface 12 is perpendicular to the thickness direction of the battery (e.g., L1) and perpendicular to the length direction of the extension portion 22 on the first surface 11 and the second surface 12. The length of the extension portion 22 on the first surface 11 and the second surface 12 can be greater than or equal to the width of the extension portion 22 on the first surface 11 and the second surface 12. For example, Figure 1 In the paper, the length of the extension portion 22 on the first surface 11 and the second surface 12 is perpendicular to the paper. The width W1 of the extension portion 22 on the first surface 11 and the second surface 12 can be: the distance between the two farthest boundaries along the direction of its width at any position of the extension portion 22 on the first surface 11 and the second surface 12, or the average of the distances at two or more positions, without specific limitation.

[0103] In some possible embodiments, Figure 8 In the diagram, X represents the length of the solar cell 10, and Y represents its width. The length of the solar cell 10 is greater than or equal to its width. (Refer to...) Figure 8 Along the width direction Y of the solar cell, the width of the extension portion 22 is W1, and the width of the solar cell is W2, 0 < W1 ≤ 5% W2. The width of the extension portion 22 is not too large, which not only plays a good passivation supplement role for the first surface 11 and the second surface 12, but also does not interfere with the current collection and conduction on the first surface 11 and the second surface 12. Figure 8 The two wavy lines in the text indicate omission.

[0104] For example, W1 can be 5%W2, 4.5%W2, 4%W2, 3.5%W2, 3%W2, 2.5%W2, 2%W2, 1.5%W2, 1%W2, 0.8%W2, 0.55%W2, or 0.1%W2.

[0105] Reference Figures 2 to 4 and Figure 8 The solar cell also includes a plurality of current-collecting electrodes 4 disposed on at least one of the first surface 11 and / or the second surface 12. In some possible embodiments, refer to Figure 8 Multiple collector electrodes 4 are spaced apart along the width direction Y and extend along the length direction X of the solar cell. The length direction X is perpendicular to the width direction Y. The extension portion 22 covers 0-5 collector electrodes 4. To avoid the extension portion 22 being too large and affecting the current collection and conductive interconnection of the collector electrodes, the extension portion 22 contacts a maximum of 5 collector electrodes 4. This not only provides a good passivation supplement to the first surface 11 and the second surface 12, but also does not interfere with the current collection and conduction on the first surface 11 and the second surface 12. The further extension portion 22 contacts a maximum of 1 collector electrode 4.

[0106] In some possible embodiments, refer to Figure 8 The solar cell also includes a plurality of interconnecting portions 15, which are arrayed on at least one of the first and second surfaces. The plurality of interconnecting portions 15 include a plurality of first edge interconnecting portions (e.g., near the cut surface) Figure 8 The part marked 15 is a first edge interconnection part. The distance W3 between the extension part 22 and any one of the multiple first edge interconnections along the width direction is greater than or equal to 0.1 mm. The width of the extension part 22 is not too large, which not only plays a good passivation supplement role for the first surface 11 and the second surface 12, but also does not interfere with the current collection and conduction on the first surface 11 and the second surface 12.

[0107] For example, W3 can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, or 1mm.

[0108] It should be noted that W3 here can be the distance between the boundary of the extension portion 22 closest to the inner side of the solar cell and the geometric center of the first edge interconnection portion, or W3 here can be the distance between the boundary of the extension portion 22 closest to the inner side of the solar cell and the boundary of the first edge interconnection portion closest to the outer side of the solar cell.

[0109] In some possible embodiments, refer to Figure 4The battery body includes: a semiconductor substrate 1, a first doped layer 5 and a second doped layer 6 located on the same side of the semiconductor substrate 1 and having different doping types. This solar cell is a back-contact solar cell, which is more aesthetically pleasing and has better performance because its light-facing surface is not blocked by electrodes. The specific type of back-contact solar cell is not limited; for example, it can be a BC cell.

[0110] In this application, the semiconductor substrate 1 can be N-type single-crystal silicon or P-type single-crystal silicon, providing long-lived charge carriers. For example, the semiconductor substrate 1 is N-type single-crystal silicon. Of the first doped layer 5 and the second doped layer 6, one is a P-type doped layer and the other is an N-type doped layer. The P-type doped layer can contain one or more elements from Group IIIA (e.g., boron). The N-type doped layer can contain one or more elements from Group VA (e.g., phosphorus). The materials of the N-type and P-type doped layers can include any semiconductor material such as silicon, germanium silicon, germanium, or gallium arsenide. In terms of the arrangement of matter, the crystal phase of the doped layer can be amorphous, microcrystalline, nanocrystalline, single-crystal, or polycrystalline. The materials of the N-type and P-type doped layers can be the same or different. For example, the materials of both the N-type and P-type doped layers can include doped polycrystalline silicon. Another example: the material of the P-type doped layer can include doped polycrystalline silicon, and the material of the N-type doped layer can include at least one of doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon. P-type doped layers can be obtained by in-situ doping on the surface of a silicon substrate or by deposition on the surface of a silicon substrate. Similarly, N-type doped layers can be obtained by in-situ doping on the surface of a silicon substrate or by deposition on the surface of a silicon substrate. For example, a P-type doped layer can be formed on a silicon substrate by in-situ doping. As another example, a P-type doped layer can be deposited on the surface of a silicon substrate (e.g., it can be an epitaxial doped layer).

[0111] In some possible embodiments, refer to Figure 4 In a back-contact solar cell, the first surface 11 can be the back surface of the cell body, and the second surface 12 is the light-facing surface of the cell body. (Refer to...) Figure 7The cut surface 13 includes a first region 131 adjacent to the backlight surface and a second region away from the backlight surface. The distribution density of the first microstructure 21 at least partially located in the first region 131 is greater than the distribution density of the first microstructure 21 at least partially located in the second region 132. That is, the distribution density of the first microstructure 21 is greater in the region of the cut surface 13 closer to the backlight surface. Therefore, the passivation layer of the cut surface in the region of the cut surface 13 closer to the backlight surface has a larger thickness, better film quality, and higher hydrogen content. Specifically, for back contact solar cells, the cutting start position is usually located on the backlight surface. The closer to the cutting start position, the greater the thermal damage, the more defects, and the greater the risk of microcracks. In other words, for back contact solar cells, the region of the cut surface closer to the backlight surface has more defects and a greater risk of microcracks. Therefore, in this application, the passivation layer of the cut surface in the region of the cut surface 13 closer to the backlight surface has a larger thickness, better film quality, and higher hydrogen content, resulting in a better passivation effect on defects at that location and greatly reducing the risk of microcracks at that location.

[0112] In some possible embodiments, refer to Figure 4 In a back-contact solar cell, the first surface 11 can be the back surface of the cell body, and the second surface 12 is the light-facing surface of the cell body. (Refer to...) Figure 7 The cut surface 13 includes a first region 131 adjacent to the backlight surface and a second region away from the backlight surface. The area proportion of the first microstructure 21 located at least partially in the first region 131 is greater than the area proportion of the first microstructure 21 located at least partially in the second region 132. That is, the area proportion of the first microstructure 21 in the region closer to the backlight surface in the cut surface 13 is larger. Therefore, the passivation layer thickness of the cut surface in the region closer to the backlight surface in the cut surface 13 is larger, the film quality is better, and the hydrogen content is higher. Specifically, for back contact solar cells, the cutting start position is usually located on the backlight surface. The closer to the cutting start position, the greater the thermal damage, the more defects, and the greater the risk of microcracks. In other words, for back contact solar cells, the region closer to the backlight surface on the cut surface has more defects and a greater risk of microcracks. Therefore, in this application, the greater the thickness of the passivation layer in the region closer to the backlight surface in the cut surface 13, the better the film quality, and the higher the hydrogen content, the better the passivation effect on defects at this position, and the greater the risk of microcracks at this position.

[0113] In some possible embodiments, refer to Figure 4In a back-contact solar cell, the first surface 11 can be the back surface of the cell body. Along the direction from the edge of the first surface 11 to the center of the first surface 11, the edge region 111 of the first surface 11 includes a third region 1111 near the cut surface 13 and a fourth region 1112 away from the cut surface. The third region 1111 includes a first step structure recessed into the cell body along the thickness direction of the cell body (i.e., shown by L1). Neither the first doped layer 5 nor the second doped layer 6 extends into the third region 1111. Specifically, during the normal operation of the back contact solar cell, the first doped layer 5 and the second doped layer 6 will form a PN junction. Both are also heavily doped layers. In the edge region 111 of the back light surface near the cut surface, the third region 1111 and the fourth region 1112 have a height difference, and the fourth region 1112 is further away from the inside of the cell body than the third region 1111. Neither the first doped layer 5 nor the second doped layer 6 extends into the third region 1111. Therefore, the first doped layer 5 and the second doped layer 6 are far away from the cut surface 13, which avoids the recombination of charge carriers at the dangling bonds formed on the cut surface.

[0114] It should be noted that the height of the first step structure here is not limited, no heavily doped layer is set at the location of the first step structure, and a PN junction may not be set at the location of the first step structure, thereby further reducing recombination on the cutting surface 13.

[0115] In some possible embodiments, refer to Figure 4 In a back-contact solar cell, one of the two surface passivation layers 7 is disposed on the light-facing side (upper surface of the semiconductor substrate), and the other surface passivation layer 7 is disposed on the first doped layer and the second doped layer, or in other words, the other surface passivation layer 7 is disposed on the back-light side (lower side of the semiconductor substrate). Two antireflection layers 8 are also present, one of which is disposed on the surface passivation layer on the light-facing side of the semiconductor substrate, and the other is disposed on the surface passivation layer on the first doped layer and the second doped layer.

[0116] In some possible embodiments, refer to Figure 4 A third microstructure 71 protrudes in a direction perpendicular to and away from the semiconductor substrate on the back passivation layer on the light-facing side. The formation reason and morphology of the third microstructure 71 can be referred to the relevant description of the first microstructure 21 mentioned above, and will not be repeated here to avoid repetition. The third microstructure 71 is located on the light-facing side, which can further improve the light trapping effect.

[0117] In some possible embodiments, refer to Figure 4In the back-contact solar cell, of the first doped layer 5 and the second doped layer 6, one is a P-type doped layer and the other is an N-type doped layer. The cell body also includes a back passivation layer located on the side of the first doped layer 5 and the second doped layer 6 away from the semiconductor substrate 1. Figure 4 The back passivation layer 7 is located on the side of the first doped layer 5 and the second doped layer 6 away from the semiconductor substrate 1. This back passivation layer has a fourth microstructure 72 protruding in a direction perpendicular to and away from the semiconductor substrate. The formation and morphology of the fourth microstructure 72 can be referred to the aforementioned description of the first microstructure 21; to avoid repetition, it will not be repeated here. In the back passivation layer, the maximum one-dimensional dimension of the fourth microstructure 72 corresponding to the P-type doped layer is larger than the maximum one-dimensional dimension of the third microstructure corresponding to the N-type doped layer. Specifically, in back-contact solar cells, the doping concentration of the P-type doped layer is usually lower than that of the N-type doped layer. In this application, the larger maximum one-dimensional dimension of the fourth microstructure 72 corresponding to the P-type doped layer results in a thicker passivation layer, better film quality, and higher hydrogen content at the P-type doped layer position. This leads to better passivation and light-trapping effects at the P-type doped layer position, compensating for the performance difference caused by the lower doping concentration of the P-type doped layer, thereby improving the performance of the back-contact solar cell.

[0118] It should be noted that the one-dimensional dimension here can also refer to the projected dimension of the fourth microstructure. The maximum one-dimensional dimension here refers to the maximum length of the projections of two or more of the fourth microstructures when illuminated with light parallel to the thickness of the back-contact solar cell. In the case where the fourth microstructure 72 exists in the surface passivation layer on the back side of the semiconductor substrate at the position corresponding to the P-type doped layer, one possibility is that the fourth microstructure 72 also exists in the surface passivation layer on the back side of the semiconductor substrate at the position corresponding to the N-type doped layer, and the maximum one-dimensional dimension of the fourth microstructure 72 in the surface passivation layer on the back side of the semiconductor substrate corresponding to the N-type doped layer is smaller. Another possibility is that the fourth microstructure 72 does not exist in the surface passivation layer on the back side of the semiconductor substrate corresponding to the N-type doped layer, or in other words, the maximum one-dimensional dimension of the fourth microstructure 72 in the back passivation layer corresponding to the N-type doped layer is 0. The meaning of the surface on the back side of the semiconductor substrate is consistent with that of the back passivation layer mentioned in this application.

[0119] In some possible embodiments, refer to Figure 4In a back-contact solar cell, the maximum one-dimensional dimension of the fourth microstructure 72, located on the back-light side of the semiconductor substrate and corresponding to the P-type doped layer, is greater than the maximum one-dimensional dimension of the aforementioned first microstructure 21. Therefore, in this application, the larger maximum one-dimensional dimension of the fourth microstructure 72 corresponding to the P-type doped layer results in a thicker passivation layer, better film quality, and higher hydrogen content at the corresponding position. This leads to better passivation and light-trapping effects, further compensating for the performance difference caused by the lower doping concentration of the P-type doped layer, thereby improving the performance of the back-contact solar cell. The magnitude of the difference in the maximum one-dimensional dimensions is not limited.

[0120] It should be noted that in a back-contact solar cell, when a fourth microstructure 72 also exists at the position corresponding to the N-type doped layer in the surface passivation layer on the back side of the semiconductor substrate, the relative size relationship between the maximum one-dimensional size of the fourth microstructure 72 at the position corresponding to the N-type doped layer in the back passivation layer and the maximum one-dimensional size of the aforementioned first microstructure 21 is not limited. For example, the maximum one-dimensional size of the first microstructure 21 may be larger than the maximum one-dimensional size of the fourth microstructure 72 at the position corresponding to the N-type doped layer in the back passivation layer.

[0121] In some possible embodiments, in a back-contact solar cell, the maximum average size of the fourth microstructure 72 of the back-side surface passivation layer is larger than the maximum one-dimensional size of the third microstructure of the front-side surface passivation layer. Specifically, for back-contact solar cells, the doped layers are all located on the back side of the semiconductor substrate; therefore, the passivation effect on the back side of the semiconductor substrate is particularly important for the performance of the solar cell. A larger maximum average size of the fourth microstructure 72 of the back-side surface passivation layer indicates a greater thickness, better film quality, and higher hydrogen content in the surface passivation layer located on the semiconductor substrate. This results in a better passivation effect on defects in the semiconductor substrate and significantly reduces the risk of microcracks at that location, further improving the performance of the back-contact solar cell.

[0122] In some possible embodiments, refer to Figure 2 and Figure 3 The battery body includes: a semiconductor substrate 1, a first doped layer 5 and a second doped layer 6 located on different sides of the semiconductor substrate 1 and having different doping types. This solar cell is a bifacial solar cell, such as a TOPCon cell.

[0123] In some possible embodiments, refer to Figure 2 and Figure 3In a bifacial solar cell, the first surface 11 can be the light-facing surface of the cell body, and the second surface 12 is the back-facing surface of the cell body. The cut surface 13 includes a first region adjacent to the light-facing surface and a second region away from the light-facing surface. The distribution density of the first microstructure 21 at least partially located in the first region is greater than the distribution density of the first microstructure 21 at least partially located in the second region. That is to say, the distribution density of the first microstructure 21 in the region of the cut surface 13 closer to the light-facing surface is greater. Therefore, the passivation layer of the cut surface in the region of the cut surface 13 closer to the light-facing surface is thicker, the film quality is better, and the hydrogen content is higher. Specifically, for bifacial solar cells, the cutting start point is usually located on the light-facing side. The closer to the cutting start point, the greater the thermal damage, the more defects, and the greater the risk of microcracks. In other words, for bifacial solar cells, the area closer to the light-facing side on the cut surface has more defects and a greater risk of microcracks. Therefore, in this application, the passivation layer of the cut surface 13 in the area closer to the light-facing side has a greater thickness, better film quality, and higher hydrogen content, resulting in a better passivation effect on defects at this location and greatly reducing the risk of microcracks at this location.

[0124] In some possible embodiments, refer to Figure 2 , Figure 3 In a bifacial solar cell, the first surface 11 can be the light-facing surface of the cell body, and the second surface 12 is the back-facing surface of the cell body. The cut surface 13 includes a first region adjacent to the light-facing surface and a second region away from the light-facing surface. The area ratio of the first microstructure 21 located at least partially in the first region is greater than the area ratio of the first microstructure 21 located at least partially in the second region. That is to say, the area ratio of the first microstructure 21 in the region closer to the light-facing surface in the cut surface 13 is larger. Therefore, the passivation layer of the cut surface in the region closer to the light-facing surface in the cut surface 13 has a larger thickness, better film quality, and higher hydrogen content. Specifically, for bifacial solar cells, the cutting start point is usually located on the light-facing side. The closer to the cutting start point, the greater the thermal damage, the more defects, and the greater the risk of microcracks. In other words, for bifacial solar cells, the area closer to the light-facing side on the cut surface has more defects and a greater risk of microcracks. Therefore, in this application, the passivation layer of the cut surface 13 in the area closer to the light-facing side has a greater thickness, better film quality, and higher hydrogen content, resulting in a better passivation effect on defects at this location and greatly reducing the risk of microcracks at this location.

[0125] In some possible embodiments, refer to Figure 2 , Figure 3In a bifacial solar cell, the first surface 11 can be the light-facing surface of the cell body, and the second surface 12 is the back-light-facing surface of the cell body. The first doped layer 5 is located on the light-facing side of the semiconductor substrate 1, and the second doped layer 6 is located on the back-light-facing side of the semiconductor substrate 1. Of the first doped layer 5 and the second doped layer 6, one is a P-type doped layer and the other is an N-type doped layer. Details regarding the first doped layer 5 and the second doped layer 6 can be found in the preceding description; to avoid repetition, they will not be repeated here. (Refer to...) Figure 2 , Figure 3 Along the direction from the edge of the first surface 11 to its center, the edge region 111 of the first surface 11 includes a third region 1111 near the cut surface 13 and a fourth region 1112 away from the cut surface. The third region 1111 includes a third step structure recessed into the cell body along the thickness direction of the cell body, and the first doped layer 5 does not extend into the third region 1111. Specifically, during normal operation of the bifacial solar cell, the first doped layer 5 and the semiconductor substrate 1 may form a PN junction. In the edge region 111 of the light-facing surface near the cut surface, the third region 1111 and the fourth region 1112 have a height difference, and the fourth region 1112 is farther away from the inside of the cell body than the third region 1111. Since the first doped layer 5 does not extend into the third region 1111, the distance between the first doped layer 5 and the cut surface 13 is greater, avoiding recombination of charge carriers at the dangling bonds formed on the cut surface.

[0126] It should be noted that the height of the third step structure here is not limited, no heavily doped layer is set at the location of the third step structure, and no PN junction is set at the location of the third step structure, thereby further reducing recombination on the cutting surface 13.

[0127] In some possible embodiments, refer to Figure 3 In a bifacial solar cell, the first surface 11 can be the light-facing surface of the cell body, and the second surface 12 is the back-light-facing surface of the cell body. The first doped layer 5 is located on the light-facing side of the semiconductor substrate 1, and the second doped layer 6 is located on the back-light-facing side of the semiconductor substrate 1. Of the first doped layer 5 and the second doped layer 6, one is a P-type doped layer and the other is an N-type doped layer. Details regarding the first doped layer 5 and the second doped layer 6 can be found in the preceding description; to avoid repetition, they will not be repeated here. (Refer to...) Figure 3Along the direction from the edge of the second surface 12 to its center, the edge region 111 of the second surface 12 includes a fifth region 1113 near the cut surface 13 and a sixth region 1114 away from the cut surface. The fifth region 1113 includes a second stepped structure recessed into the battery body along the thickness direction of the battery body, and the second doped layer 6 does not extend into the fifth region 1113. Specifically, the fifth region 1113 and the sixth region 1114 have a height difference, and the sixth region 1114 and the fifth region 1113 are further away from the interior of the battery body. Since the second doped layer 6 does not extend into the fifth region 1113, the distance between the second doped layer 6 and the cut surface 13 is greater, avoiding recombination of charge carriers at the dangling bonds formed on the cut surface.

[0128] It should be noted that the height of the second step structure here is not limited, no heavily doped layer is set at the location of the second step structure, and no PN junction is set at the location of the second step structure, thereby further reducing recombination on the cutting surface 13.

[0129] In some possible embodiments, refer to Figure 3 For a bifacial solar cell, it includes two surface passivation layers, one of which is disposed on a first doped layer and the other on a second doped layer; and two antireflection layers, one of which is disposed on the surface passivation layer on the first doped layer and the other on the surface passivation layer on the second doped layer. The surface passivation layer on the first doped layer has a third microstructure 71 protruding in a direction perpendicular to and away from the semiconductor substrate, and the surface passivation layer on the second doped layer has a fourth microstructure 72 protruding in a direction perpendicular to and away from the semiconductor substrate. The reasons for the formation, effects, and maximum one-dimensional dimensions of the third and fourth microstructures are described above; to avoid repetition, they will not be repeated here.

[0130] In some possible embodiments, refer to Figure 3 For bifacial solar cells, the maximum one-dimensional dimension of the third microstructure on the light-facing side of the semiconductor substrate is greater than the maximum one-dimensional dimension of the fourth microstructure on the back-light-facing side of the semiconductor substrate. Consequently, the size of the third microstructure on the light-facing side of the semiconductor substrate is larger, which can bring better light trapping effect.

[0131] In some possible embodiments, for bifacial solar cells, the maximum one-dimensional dimension of the third microstructure on the light-facing side of the semiconductor substrate is greater than the maximum one-dimensional dimension of the first microstructure. As a result, the size of the third microstructure on the light-facing side of the semiconductor substrate is larger, which can lead to a better light-trapping effect.

[0132] It should be noted that in the comparison of the dimensions of the microstructures mentioned in this application, the specific size of the difference between the two is not limited.

[0133] In some possible embodiments, refer to Figures 2 to 4 The battery body also includes: a surface passivation layer 7 located on the first surface 11 and / or the second surface 12 and an anti-reflection layer 8 disposed on the surface passivation layer 7; the surface passivation layer is: a silicon nitride layer and / or an aluminum oxide layer. The surface passivation layer 7 can provide good passivation effect and are all materials commonly used in the field and easy to prepare, so the cost of production line modification and related testing is low.

[0134] In some possible embodiments, the cut surface passivation layer 2 and the surface passivation layer can both be combinations of one or more of the following: an aluminum oxide layer, a silicon nitride layer, a silicon oxide layer, a silicon oxynitride layer, an intrinsic amorphous silicon layer, an intrinsic microcrystalline silicon layer, a doped amorphous silicon layer, or a doped microcrystalline silicon layer. For example, the cut surface passivation layer 2 can be an aluminum oxide layer, which has excellent passivation properties and can effectively reduce dangling bonds and defects on and near the cut surface 13. Alternatively, the cut surface passivation layer 2 can be a stack of an aluminum oxide layer and a silicon oxide layer, wherein the silicon oxide layer is located between the aluminum oxide layer and the cut surface 13. Since the cut surface 13 typically has too many defects, the thickness of the cut surface passivation layer 2 is greater than the thickness of the surface passivation layer 7. Whether the materials of the cut surface passivation layer 2 and the surface passivation layer are the same is not limited; for example, they can be the same or different.

[0135] In some possible embodiments, refer to Figures 2 to 4 The battery body also includes: a surface passivation layer 7 located on the first surface 11 and / or the second surface 12 and an anti-reflection layer 8 disposed on the surface passivation layer 7; the aforementioned extension portion 22 covers the anti-reflection layer 8, so in the process of manufacturing, the anti-reflection layer 8 is prepared first and then the cut surface passivation layer 2 is prepared, which has good compatibility with existing processes and lower costs for production line modification and related testing.

[0136] In some possible embodiments, the antireflection layer 8 mentioned in this application is a hydrogen-containing antireflection layer, which further enhances the passivation layer effect.

[0137] In some possible embodiments, the extension portion 22, the hydrogen-containing anti-reflection layer, and the surface passivation layer constitute an edge passivation stack, which further enhances the passivation and anti-reflection effect at the edges of the first and second surfaces and reduces the risk of microcracks.

[0138] It should be noted that in this application, the slicing process can be as follows: first, grooves are formed at opposite ends of the semiconductor substrate or the entire solar cell to be cut, and then mechanical stress is used to cleave the substrate. Alternatively, the slicing process can be as follows: along the cutting position, a cutting force is applied from one end of the semiconductor substrate or the entire solar cell to be cut to the other end to cleave the substrate. Laser slicing can be used, and the specific slicing process is not limited. This application does not specifically limit the specific slicing method. The semiconductor substrate can be cut first and then the solar cell can be fabricated, or the entire solar cell can be fabricated first and then sliced. It should be noted that the passivation layer 2 on the cut surface is prepared after slicing.

[0139] It should be noted that the various embodiments described above in this application can be implemented individually or in combination without logical conflict, and this application does not limit them in this regard.

[0140] This application also provides a photovoltaic module, including: a cell string, which is formed by connecting multiple of the aforementioned solar cells, which may be connected by interconnecting components. Because the passivation effect of the cut surfaces in the solar cells is better, the resulting photovoltaic module has better performance. The photovoltaic module may further include: an encapsulation layer covering the surface of the cell string, which may include an encapsulating film, etc., and a cover plate covering the surface of the encapsulation layer away from the cell string. The interconnecting components here may refer to solder ribbons, conductive backsheets, etc., and are not specifically limited thereto. The cover plate may be glass, etc., and the specific material is not limited.

[0141] It should be noted that the photovoltaic modules mentioned here can refer to any of the aforementioned solar cells. To avoid repetition, the relevant details will not be repeated.

[0142] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0143] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A solar cell, characterized in that, The solar cell includes: a cell body, the cell body including: a first surface and a second surface opposite to each other along its thickness direction, and a side surface connecting the first surface and the second surface, the side surface including: a cut surface and a non-cut surface; A passivation layer is formed on the cut surface, the passivation layer having a plurality of first microstructures protruding in a direction away from the battery body; the first microstructures are formed by hydrogen accumulation or escape after the passivation layer is heated.

2. The solar cell according to claim 1, characterized in that, The cut surface includes: a first region adjacent to the first surface and a second region away from the first surface; the distribution density of the first microstructure at least partially located in the first region is greater than the distribution density of the first microstructure at least partially located in the second region; and / or, The one-dimensional average size of the first microstructure, which is at least partially located in the first region, is greater than the one-dimensional average size of the first microstructure, which is at least partially located in the second region; the direction of the one-dimensional average size is perpendicular to the direction of the height of the first microstructure, and / or; The ratio of the total area of ​​the first microstructure in the first region to the area of ​​the first region is greater than the ratio of the total area of ​​the first microstructure in the second region to the area of ​​the second region.

3. The solar cell according to claim 1, characterized in that, The cut surface has a groove structure, and at least a portion of the first microstructure is arranged along the extension direction of the groove structure.

4. The solar cell according to claim 1, characterized in that, The passivation layer for the cut surface further includes: an extension portion extending to the edge region of the first surface near the cut surface and / or the edge region of the second surface near the cut surface; Along the direction from the edge of the first surface to the center of the first surface, the edge region of the first surface includes: a third region close to the cut surface and a fourth region away from the cut surface; a first sub-extension located in the third region of the extension has a plurality of second microstructures protruding in a direction opposite to the battery body; and / or, Along the direction from the edge of the second surface to the center of the second surface, the edge region of the second surface includes: a fifth region close to the cut surface and a sixth region away from the cut surface, and the second sub-extension located in the fifth region of the extension has a plurality of second microstructures protruding in a direction away from the battery body.

5. The solar cell according to claim 4, characterized in that, The third sub-extension of the extension portion located in the fourth region has a plurality of second microstructures protruding in a direction away from the battery body, and / or the fourth sub-extension of the extension portion located in the sixth region has a plurality of second microstructures protruding in a direction away from the battery body. The distribution density of the second microstructure in the third sub-extension is less than the distribution density of the second microstructure in the first sub-extension; and / or, The distribution density of the second microstructure in the fourth sub-extension is less than the distribution density of the second microstructure in the second sub-extension.

6. The solar cell according to claim 1, characterized in that, The one-dimensional size of the first microstructure is 0.1-10 μm.

7. The solar cell according to claim 1, characterized in that, In the direction perpendicular to the cut surface, the height of the first microstructure is 20-500 nm.

8. The solar cell according to claim 1, characterized in that, On the cut surface, an uneven anti-reflection structure is formed at the position corresponding to the first microstructure.

9. The solar cell according to claim 4, characterized in that, Along the width direction of the solar cell, the width of the extension is W1, the width of the solar cell is W2, 0 < W1 ≤ 5%W2; and / or, 0 < W1 ≤ 5mm; and / or, The solar cell further includes a plurality of current-collecting electrodes disposed on the first surface and / or the second surface. The plurality of current-collecting electrodes are spaced apart along the width direction and extend along the length direction of the solar cell, the length direction being perpendicular to the width direction. The extended portion covers 0-5 of the current-collecting electrodes; and / or, The solar cell further includes a plurality of interconnects, which are arrayed on at least one of the first surface and the second surface. The plurality of interconnects include a plurality of first edge interconnects near the cut surface. The distance between the extended portion and any one of the plurality of first edge interconnects along the width direction is greater than or equal to 0.1 mm.

10. The solar cell according to claim 1, characterized in that, The first microstructure is a bulge structure that protrudes in a direction away from the battery body; and / or, the first microstructure is an opening structure that protrudes in a direction away from the battery body; and / or, the first microstructure is a microstructure that protrudes in a direction away from the battery body and has a cyclone-shaped edge.

11. The solar cell according to any one of claims 1 to 10, wherein the cell body comprises: Semiconductor substrate, A first doped layer and a second doped layer are disposed on the back surface of the semiconductor substrate, and the first doped layer and the second doped layer have opposite conductivity. Two surface passivation layers, one of which is disposed on the light-facing surface of the semiconductor substrate, and the other of which is disposed on the first doped layer and the second doped layer; Two antireflection layers, one of which is disposed on the surface passivation layer of the light-facing surface of the semiconductor substrate, and the other of which is disposed on the surface passivation layers of the first doped layer and the second doped layer; The passivation layer on the light-facing side of the semiconductor substrate has a third microstructure protruding in a direction perpendicular to and away from the semiconductor substrate, and the passivation layer on the back-light-facing side of the semiconductor substrate has a fourth microstructure protruding in a direction perpendicular to and away from the semiconductor substrate.

12. The solar cell according to claim 11, characterized in that, The first surface is the backlight surface of the battery body; along the direction from the edge of the first surface to the center of the first surface, the edge region of the first surface includes: a third region close to the cut surface and a fourth region away from the cut surface; The third region includes a first step structure recessed into the battery body along the thickness direction; neither the first doped layer nor the second doped layer extends into the third region.

13. The solar cell according to claim 11, characterized in that, Of the first doped layer and the second doped layer, one is a P-type doped layer and the other is an N-type doped layer; In the surface passivation layer on the backlight side of the semiconductor substrate: the maximum one-dimensional dimension of the fourth microstructure at the position corresponding to the P-type doped layer is greater than the maximum one-dimensional dimension of the fourth microstructure at the position corresponding to the N-type doped layer. And / or, In the surface passivation layer on the backlight side of the semiconductor substrate: the maximum one-dimensional dimension of the fourth microstructure at the position corresponding to the P-type doped layer is greater than the maximum one-dimensional dimension of the first microstructure, and / or, The maximum average size of the fourth microstructure is greater than the maximum one-dimensional size of the third microstructure.

14. The solar cell according to any one of claims 1 to 10, wherein the cell body comprises: Semiconductor substrate, A first doped layer and a second doped layer are disposed on opposite surfaces of the semiconductor substrate along the thickness direction of the semiconductor substrate, and the first doped layer and the second doped layer have opposite conductivity. Two surface passivation layers, one of which is disposed on the first doped layer and the other of which is disposed on the second doped layer; Two antireflection layers, one of which is disposed on a surface passivation layer on the first doped layer, and the other of which is disposed on a surface passivation layer on the second doped layer; The surface passivation layer located on the first doped layer has a third microstructure protruding in a direction perpendicular to and away from the semiconductor substrate, and the surface passivation layer located on the second doped layer has a fourth microstructure protruding in a direction perpendicular to and away from the semiconductor substrate.

15. The solar cell according to claim 14, characterized in that, The first surface is the light-facing surface of the battery body, the first doped layer is located on the light-facing side of the semiconductor substrate, and the second doped layer is located on the back-light side of the semiconductor substrate. Along the direction from the edge of the second surface to the center of the second surface, the edge region of the second surface includes: a fifth region close to the cut surface and a sixth region away from the cut surface; the fifth region includes a second stepped structure recessed into the battery body along the thickness direction of the battery body, and the second doped layer does not extend into the fifth region; and / or, Along the direction from the edge of the first surface to the center of the first surface, the edge region of the first surface includes: a third region close to the cut surface and a fourth region away from the cut surface; the third region includes a third step structure recessed into the battery body along the thickness direction of the battery body, and the first doped layer does not extend into the third region.

16. The solar cell according to claim 14, characterized in that, The first surface is the light-facing surface of the battery body, the first doped layer is located on the light-facing side of the semiconductor substrate, and the second doped layer is located on the back-light side of the semiconductor substrate. The maximum one-dimensional dimension of the third microstructure is greater than the maximum one-dimensional dimension of the fourth microstructure. And / or, The maximum one-dimensional dimension of the third microstructure is greater than that of the maximum one-dimensional dimension of the first microstructure.

17. The solar cell according to any one of claims 1 to 10, characterized in that, The battery body further includes: a surface passivation layer located on the first surface and / or the second surface and a hydrogen-containing anti-reflection layer disposed on the surface passivation layer, wherein the extended portion, the hydrogen-containing anti-reflection layer and the surface passivation layer constitute an edge passivation stack; The surface passivation layer and the cut surface passivation layer are both combinations of one or more of the following: aluminum oxide layer, silicon nitride layer, silicon oxide layer, silicon oxynitride layer, intrinsic amorphous silicon layer, intrinsic microcrystalline silicon layer, doped amorphous silicon layer, or doped microcrystalline silicon layer.

18. A photovoltaic module, characterized in that, include: A battery string, wherein the battery string is formed by connecting a plurality of solar cells as described in any one of claims 1-17; An encapsulation layer is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulation layer away from the battery string.

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