Solar cell and method of manufacturing the same, photovoltaic module

Abstract

This application discloses a solar cell and its fabrication method, as well as a photovoltaic module. The solar cell includes a silicon substrate. The back surface of the silicon substrate has a flat structure and several groove structures recessed relative to the flat structure. Several raised microstructures are provided on the surfaces of the flat structure and the groove structures. The area ratio of the raised microstructures on the surface of the groove structures is higher than the area ratio of the raised microstructures on the surface of the flat structure. This application not only improves the light absorption capacity of the back surface but also enhances the deposition quality of the functional film layer disposed on the back surface of the silicon substrate.

Description

Technical Field

[0001] This application relates to the technical field of solar cells, and more particularly to a solar cell and its preparation method, and a photovoltaic module. Background Technology

[0002] In solar cells, the back surface of the silicon substrate is usually a polished surface. This polished surface not only has insufficient light absorption and utilization capabilities, but also is prone to structural defects such as trenches, which affect the deposition quality of functional films such as dielectric layers or doped polycrystalline silicon layers on the back surface of the silicon substrate, thereby limiting the further improvement of the photoelectric conversion efficiency of solar cells. Summary of the Invention

[0003] In order to improve the light absorption capacity of the back surface, while also improving the deposition quality of the functional film layer disposed on the back surface of the silicon substrate, this application provides a solar cell and its preparation method, as well as a photovoltaic module.

[0004] In a first aspect, embodiments of this application provide a solar cell.

[0005] A solar cell includes a silicon substrate. The back surface of the silicon substrate has a flat structure and a plurality of groove structures recessed relative to the flat structure. The surfaces of the flat structure and the groove structures are provided with a plurality of protruding microstructures. The area ratio of the protruding microstructures on the surface of the groove structures is higher than the area ratio of the protruding microstructures on the surface of the flat structure.

[0006] As an optional implementation, in an embodiment of this application, the groove structure includes a groove bottom and a groove sidewall extending from the periphery of the groove bottom toward the flat structure, wherein the groove sidewall intersects with the groove bottom to form the inner edge of the groove;

[0007] Along the sidewall surface of the groove, from the direction away from the inner edge of the groove to the direction closer to the inner edge of the groove, the bottom dimension of the protruding microstructure tends to increase;

[0008] Along the bottom of the groove, from the direction away from the inner edge of the groove to the direction closer to the inner edge of the groove, the bottom dimension of the protruding microstructure tends to increase;

[0009] The bottom dimension of the protruding microstructure is w, where w is the maximum width dimension of the bottom of the protruding microstructure in contact with the silicon substrate.

[0010] As an optional implementation, in the embodiments of this application, in the protruding microstructure, w is 0.01 μm to 5 μm and the height h is 0.01 μm to 3 μm;

[0011] In a cross-section along the thickness direction of the silicon substrate and passing through the center of the protruding microstructure, the angle e between the bottom and the side is 20°~70°.

[0012] As an optional implementation, in the embodiments of this application, the protruding microstructure includes a first protruding microstructure, a second protruding microstructure, and a third protruding microstructure, wherein the bottom dimensions of the first protruding microstructure, the second protruding microstructure, and the third protruding microstructure increase sequentially, wherein:

[0013] The first protruding microstructures are distributed on the bottom of the groove in the flat structure and the groove structure.

[0014] The groove sidewall of the groove structure is provided with the second protruding microstructure;

[0015] The third protruding microstructure is distributed in the region of the sidewall of the groove near the inner edge of the groove and in the region of the bottom of the groove near the inner edge of the groove.

[0016] As an optional implementation, in the embodiments of this application, in the first protruding microstructure, the bottom dimension is w1, w1 is 0.1 μm~3 μm, and the height h1 is 0.01 μm~2 μm;

[0017] In the second protruding microstructure, the bottom dimension is w2, which is 0.1 μm to 4 μm, and the height h2 is 0.01 μm to 2 μm;

[0018] In the third protruding microstructure, the bottom dimension is w3, which is 0.2 μm to 5 μm, and the height h3 is 0.02 μm to 3 μm.

[0019] As an optional implementation, in the embodiments of this application, the protruding microstructure is in the shape of a cone or a cone-like structure.

[0020] As an optional implementation, in the embodiments of this application, the protruding microstructure includes at least one of the following types:

[0021] The cone-shaped structure has a smooth curve on the side profile of its cross-section along the thickness direction of the silicon substrate. The surface of the cone-shaped structure is distributed with several nanoscale protrusions, and the nanoscale protrusions have a size of 10 nm to 100 nm near the bottom of the cone-shaped structure.

[0022] A multifaceted cone, wherein the multifaceted cone is a cone having multiple sides and one vertex, the number of sides n of the multifaceted cone being a positive integer greater than or equal to 4, the multifaceted cone including a first multifaceted cone and a second multifaceted cone; along the thickness direction of the silicon substrate, the angle between the side and the bottom of the first multifaceted cone is e1, wherein e1 is 20°~40°, and the angle between the side and the bottom of the second multifaceted cone is e2, wherein e2 is greater than 40° and less than or equal to 70°;

[0023] A multi-peak cone, comprising a main peak and several sub-peaks, wherein the sub-peaks are disposed on the side of the main peak, and the apex of the sub-peaks facing away from the silicon substrate faces the apex of the main peak facing away from the silicon substrate.

[0024] As an optional implementation, in the embodiments of this application, on the backlight surface of the silicon substrate, the groove structures having the protruding microstructures are distributed in an isolated manner or partially overlapped.

[0025] When the groove structures are partially overlapping, the groove structures extend along a line or are distributed in a cluster.

[0026] As an optional implementation, in the embodiments of this application, the backlight surface of the silicon substrate has a dielectric layer, a first doped semiconductor layer and a backlight passivation layer stacked sequentially.

[0027] The back surface of the silicon substrate also has a first electrode, which forms an ohmic contact with the first doped semiconductor through the passivation layer of the back surface.

[0028] The light-receiving surface of the silicon substrate has a second doped semiconductor layer, a light-receiving surface passivation layer disposed on the second doped semiconductor layer, and a second electrode, wherein the second electrode passes through the light-receiving surface passivation layer and forms an ohmic contact with the second doped semiconductor layer.

[0029] As an optional implementation, in an embodiment of this application, the backlight surface of the silicon substrate includes a first region and a second region, and the flat structure having the raised microstructure and the groove structure are distributed in the first region;

[0030] The dielectric layer and the first doped semiconductor layer cover the first region, and the backlight passivation layer covers the surface of the first doped semiconductor layer away from the silicon substrate and the second region.

[0031] Secondly, embodiments of this application provide a method for preparing a solar cell.

[0032] A method for fabricating a solar cell includes the following steps:

[0033] Provide a texturized silicon substrate;

[0034] The backlight surface of the silicon substrate is characterized by etching, including: using a first etching solution containing an inorganic alkali and a texturing additive to perform a first etching process on the backlight surface of the silicon substrate, forming a groove structure and a flat structure located between adjacent groove structures on the backlight surface of the silicon substrate, and forming raised microstructures on the groove structure and the flat structure.

[0035] As an optional implementation, in the embodiments of this application, the characteristic etching process further includes performing a second etching process before performing the first etching process. The second etching process includes: performing the second etching process on the back surface of the silicon substrate using a second etching solution containing the inorganic alkali and polishing additives.

[0036] And / or,

[0037] After the first etching process, a third etching process is performed, which includes: using a third etching solution containing the inorganic alkali and texture modification additives to perform the third etching process on the back surface of the silicon substrate.

[0038] As an optional implementation, in the embodiments of this application, the inorganic base includes one or both of sodium hydroxide or potassium hydroxide; the texturing additive includes any one or more combinations of lignin, cellulose, or polysaccharides; the polishing additive includes any one or more combinations of quaternary ammonium salts, hydroxyethylidene phosphates, or sulfates; and the texture modification additive includes any one or more combinations of sodium benzoate, sodium acetate, polyquaternary ammonium salts, cationic guar gum, sorbic acid, or citrate.

[0039] As an optional implementation, in the embodiments of this application, the volume concentration of the inorganic alkali in the first etching solution is 0.3 vol%~4 vol%, the volume concentration of the texturing additive is 0.001 vol%~0.8 vol%, the reaction time of the first etching treatment is 50 s~200 s, and the reaction temperature is 55℃~75℃.

[0040] In the second etching solution, the volume concentration of the inorganic alkali is 0.5 vol%~10 vol%, the volume concentration of the polishing additive is 0.002 vol%~5 vol%, the reaction temperature of the second etching treatment is 45℃~75℃, and the reaction time is 50 s~400 s;

[0041] In the third etching solution, the volume concentration of the inorganic alkali is 0.1 vol% to 6 vol%, the volume concentration of the texture modification additive is 0.004 vol% to 5 vol%, the reaction temperature of the third etching treatment is 60℃ to 80℃, and the reaction time of the third etching treatment is 50 s to 200 s.

[0042] Thirdly, embodiments of this application provide a photovoltaic module.

[0043] A photovoltaic module includes a solar cell as described in the first aspect, or a solar cell prepared by the method described in the second aspect.

[0044] Compared with the prior art, the beneficial effects of this application are as follows:

[0045] The solar cell of this application has several raised microstructures on the surfaces of the aforementioned grooved and flat structures, with the area of ​​the raised microstructures on the surface of the grooved structure being higher than that on the surface of the flat structure. This not only improves the light absorption and utilization capacity of the backlight surface by utilizing the raised microstructures, but also effectively intervenes in and suppresses the formation of sharp structural defects such as trenches and microcracks by forming dense and relatively gentle raised microstructures in the groove region, which is more prone to defects. This allows for targeted repair of structural defects on the backlight surface, thereby helping to ensure the uniformity and coverage integrity of the functional film layers (such as dielectric layers, doped polycrystalline silicon layers, or backlight passivation layers) deposited on the backlight surface, thus improving the deposition quality of the functional film layers. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This is a SEM (scanning electron microscope) image of the back surface of a silicon substrate with grooves and microcracks.

[0048] Figure 2 It is used for illustration Figure 1 SEM images of the specific morphology of medium-groove and microcrack structural defects;

[0049] Figure 3 This is a schematic diagram of the structure of the first type of solar cell disclosed in the embodiments of this application;

[0050] Figure 4 This is disclosed in the embodiments of this application. Figure 3 Enlarged structural diagram of section A in the middle;

[0051] Figure 5 This is a SEM image showing the distribution of the protruding microstructures on the groove structure and the flat structure disclosed in the embodiments of this application;

[0052] Figure 6 This is a SEM image of the distribution of the protruding microstructures in the groove structure disclosed in the embodiments of this application;

[0053] Figure 7 This is a cross-sectional SEM image of the protruding microstructure disclosed in the embodiments of this application;

[0054] Figure 8 This is a SEM image of the first type of cone-shaped protrusion microstructure disclosed in the embodiments of this application;

[0055] Figure 9 This is a SEM image of the second type of cone-shaped protrusion microstructure disclosed in the embodiments of this application;

[0056] Figure 10 This is a SEM image of the first type of multifaceted cone-shaped protrusion microstructure disclosed in the embodiments of this application;

[0057] Figure 11 This is a SEM image of the second type of multifaceted cone-shaped protrusion microstructure disclosed in the embodiments of this application;

[0058] Figure 12 This is a SEM image of the multi-peaked cone-shaped protrusion microstructure disclosed in the embodiments of this application;

[0059] Figure 13 This is a schematic diagram of the cone-shaped protruding microstructure disclosed in the embodiments of this application;

[0060] Figure 14 This is a SEM image of an isolated distribution of a groove structure with protruding microstructures disclosed in an embodiment of this application;

[0061] Figure 15 This is a SEM image of a groove structure with protruding microstructures that overlaps and extends along a line, as disclosed in an embodiment of this application.

[0062] Figure 16 This is a SEM image of the groove structure with protruding microstructures partially overlapping and distributed in a cluster, as disclosed in the embodiments of this application;

[0063] Figure 17 This is a schematic diagram of the structure of the second type of solar cell disclosed in the embodiments of this application;

[0064] Figure 18 This is a schematic diagram of the fabrication steps of the solar cell disclosed in the embodiments of this application.

[0065] Icons: 1. Silicon substrate; 1a. First region; 1b. Second region; 11. Flat structure; 12. Groove structure; 121. Groove bottom; 122. Groove sidewall; 123. Groove inner edge; 13. Protruding microstructure; 131. First protruding microstructure; 132. Second protruding microstructure; 133. Third protruding microstructure; 13a. Cross section; 13b. Cone-like structure; 13b1. Nanoscale protrusion; 13c. Multifaceted cone; 13c1. First multifaceted cone; 13c2. Second multifaceted cone; 13d. Multipeaked cone; 2. Dielectric layer; 3. First doped semiconductor layer; 41. Backlight passivation layer; 42. Light-receiving passivation layer; 5. First electrode; 6. Second doped semiconductor layer; 7. Second electrode. Detailed Implementation

[0066] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0067] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0068] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0069] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0070] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0071] like Figure 1 As shown, flat and grooved structures are surface structures formed on the backlight surface after polishing and other processes. During polishing, due to factors such as inconsistent crystal orientation of the silicon substrate or uneven stress release, the location of the grooved structure often becomes a weak area on the backlight surface, making it more prone to residual or induced structural defects such as steep-edged grooves and microcracks. Figure 2 The morphology of structural defects such as grooves and microcracks within the dashed box shows that these defects typically exhibit a large depth-to-width ratio, sharp edges, and significant geometric abrupt changes. They are prone to causing local stress concentration and forming dead zones, which is detrimental to the deposition of subsequent functional films.

[0072] Therefore, this application provides a solar cell and its fabrication method, as well as a photovoltaic module, to reduce structural defects on the back side of the silicon substrate, improve the deposition quality of subsequent functional films, and enhance the photoelectric conversion efficiency of the solar cell. The technical solution of this application will be further described below with reference to embodiments and accompanying drawings.

[0073] In a first aspect, embodiments of this application provide a solar cell.

[0074] Reference Figure 3 A solar cell, comprising a silicon substrate 1, and a silicon substrate 2, wherein the substrate is bonded to the solar cell. Figure 4 As shown, the back surface of the silicon substrate 1 has a flat structure 11 and a plurality of groove structures 12 that are recessed relative to the flat structure 11. The surfaces of the flat structure 11 and the groove structures 12 are provided with a plurality of raised microstructures 13. Figure 4 The dashed lines in the groove structure 12 are used to more clearly illustrate the outline of the groove structure 12;

[0075] SEM image of the distribution of the protruding microstructure 13 on the back surface of the silicon substrate 1 is shown below. Figure 5 As shown, from Figure 5 It can be seen that the area ratio of the protruding microstructure 13 on the surface of the groove structure 12 is higher than that of the protruding microstructure 13 on the surface of the flat structure 11.

[0076] The solar cell of this application optimizes and improves the surface structure of the back surface of the silicon substrate 1, thereby improving the light absorption and utilization capacity of the back surface and specifically repairing the structural defects of the back surface. This helps to ensure the uniformity and coverage integrity of the functional film layers (such as dielectric layer 2, doped polycrystalline silicon layer, back surface passivation layer 41, etc.) deposited on the back surface, thus achieving the purpose of improving the deposition quality of the functional film layers.

[0077] This application provides a plurality of raised microstructures 13 on the surface of the aforementioned groove structure 12 and flat structure 11, and specifically sets the area ratio of the raised microstructures 13 on the surface of the groove structure 12 to be higher than that on the surface of the flat structure 11. Firstly, these raised microstructures 13 can significantly increase the surface roughness and specific surface area of ​​the backlight surface, effectively extend the optical path of the incident light within the backlight surface, and enhance the light-capturing ability through multiple reflections and scattering, thereby enhancing the absorption and utilization efficiency of long-wavelength photons; secondly, and more importantly, because these raised microstructures 13 are more densely distributed on the surface of the groove structure 12, that is, in the locations where structural defects such as grooves are easily generated after the backlight surface is polished, there are more raised microstructures 13. This achieves effective intervention in the growth of defects such as grooves, transforming the locations where structural defects such as grooves are grown (i.e., the locations of the groove structure 12) into locations where smaller and more concentrated raised microstructures 13 are grown. Compared to structural defects such as grooves, the raised microstructures 13 on the surface of the groove structure 12 are smaller and have gentler undulations, thereby reducing the degree of geometric abrupt changes caused by structural defects such as grooves. This allows the material of the functional film to spread more continuously and uniformly along the contour of the raised microstructures 13 during the deposition of the functional film, effectively avoiding problems such as film discontinuity, uneven thickness, and dead corners caused by structural defects such as grooves.

[0078] It can be seen that by setting denser protruding microstructures 13 in the groove structure 12 to replace the defective structures such as trenches, not only are the inherent structural defects of the back surface modified, but they are also transformed into an optimized morphology that is conducive to light absorption and functional film coverage. Thus, while improving the light absorption capacity, the deposition quality of the functional film on the back surface is significantly improved, and the efficiency of the solar cell is effectively improved.

[0079] It should be noted that in this application, the flat structure 11 of the backlight surface refers to the fact that the shape of the flat structure 11 is relatively flat compared to the groove structure 12, but it does not mean that the shape is absolutely flat. The flat structure 11 may still have a certain degree of surface roughness.

[0080] Furthermore, the area ratio in this application specifically refers to the ratio of the sum of the projected areas of the protruding microstructures on the silicon substrate 1 per unit area to the unit area. The area ratio of the protruding microstructure 13 on the surface of the groove structure 12 is higher than the area ratio of the protruding microstructure 13 on the surface of the flat structure 11, which means that the coverage of the protruding microstructure on the surface of the groove structure 12 is higher than the coverage of the protruding microstructure 13 on the surface of the flat structure 11.

[0081] Reference Figure 5 In some embodiments, the groove structure 12 includes a groove bottom 121 and a groove sidewall 122 extending from the periphery of the groove bottom 121 toward the flat structure 11. The groove sidewall 122 intersects with the groove bottom 121 to form an inner edge 123 of the groove. The boundary of the inner edge 123 of the groove is as follows: Figure 5 The black dashed box in the image is shown.

[0082] Reference Figure 6 Along the surface of the groove sidewall 122, from the direction away from the inner edge 123 of the groove to the direction closer to the inner edge 123 of the groove, the bottom size of the protruding microstructure 13 tends to increase.

[0083] Along the bottom 121 of the groove, from the direction away from the inner edge 123 of the groove to the direction closer to the inner edge 123 of the groove, the bottom size of the protruding microstructure 13 tends to increase;

[0084] The bottom dimension w of the protruding microstructure 13 is the maximum width dimension of the bottom of the protruding microstructure 13 in contact with the silicon substrate 1.

[0085] On the sidewalls 122 and bottom 121 of the groove, by gradually increasing the bottom size of the protruding microstructures 13 from the area away from the inner edge 123 of the groove towards the area closer to the inner edge 123, a synergistic optimization effect of optics and passivation can be achieved. Specifically, placing protruding microstructures 13 with smaller bottom sizes in the area away from the inner edge 123 helps reduce surface reflection and enhance light absorption; while placing protruding microstructures 13 with larger bottom sizes in the area closer to the inner edge 123 helps improve the interface passivation quality and suppress the generation of lattice defects. This size gradient design allows the solar cell to achieve better passivation effects while improving light-harvesting capabilities, thereby comprehensively improving cell performance.

[0086] It should be noted that, as Figure 5 In the SEM image shown, the bottom dimension w of the contact point between the protruding microstructure 13 and the silicon substrate 1 is: the length of the line segment connecting the two farthest points on the polygonal outline projected onto the surface of the silicon substrate 1 (the black dashed line in the figure). Furthermore, to reduce the measurement error of the bottom dimension w of the contact point between the protruding microstructure 13 and the silicon substrate 1, 2-5 measurements can be performed, and the average value of the test results for the maximum width can be taken.

[0087] In this application, the direction along the surface of the groove sidewall 122 from away from the inner edge 123 of the groove to near the inner edge 123 of the groove is... Figure 6 The direction indicated by the middle arrow, along the sidewall 122 from the upper left to the lower right, and along the bottom 121 from away from the inner edge 123 of the groove to closer to the inner edge 123 of the groove, is... Figure 6 The middle arrow indicates the direction from right to left.

[0088] In some embodiments, the bottom dimension w of the protruding microstructure 13 is 0.1 μm to 5 μm, and the height h of the protruding microstructure 13 is 0.01 μm to 3 μm; for example, w can be 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, or 5 μm; h can be 0.01 μm, 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, or 3 μm;

[0089] In the cross section 13a along the thickness direction of the silicon substrate and passing through the center of the protruding microstructure, the angle e between the bottom and the side is 20° to 70°; for example, e can be 20°, 30°, 40°, 50°, 60° or 70°, etc.

[0090] By controlling the size and angle of the protruding microstructure 13 within the aforementioned range, a smooth contour morphology can be obtained, avoiding sharp edges or near-right angles in the protruding microstructure 13. This morphological feature facilitates a more uniform and complete coverage of the functional film layer on the surface of the protruding microstructure 13 in subsequent processes, improving the adhesion and density of the functional film layer, thereby enhancing the overall quality and reliability of the deposited functional film layer.

[0091] It should be noted that in this application, the height h and included angle e of the protruding microstructure 13 can both be as follows: Figure 7 As shown, measurements were taken at a cross section 13a along the thickness direction of the silicon substrate 1 and passing through the center of the protruding microstructure 13.

[0092] Refer to the return Figure 5 and Figure 6 In some embodiments, the protruding microstructure 13 includes a first protruding microstructure 131, a second protruding microstructure 132, and a third protruding microstructure 133, wherein the bottom dimensions of the first protruding microstructure 131, the second protruding microstructure 132, and the third protruding microstructure 133 increase sequentially, wherein:

[0093] The bottom 121 of the flat structure 11 and the groove structure 12 has a first protruding microstructure 131 distributed thereon;

[0094] The groove sidewall 122 of the groove structure 12 is provided with second protruding microstructures 132;

[0095] The area of ​​the sidewall 122 near the inner edge 123 of the groove and the area of ​​the bottom 121 near the inner edge 123 of the groove are provided with third protruding microstructures 133.

[0096] By setting raised microstructures 13 with specific bottom dimensions in different regions, the backlight surface can be optimized in a zoned manner: while improving light-harvesting ability and reducing surface reflection, defects in corresponding regions are specifically suppressed, and the interface passivation effect is enhanced. This design enables the solar cell to improve both light absorption efficiency and passivation performance simultaneously, thereby comprehensively improving the photoelectric conversion efficiency and long-term reliability of the cell.

[0097] In some embodiments, the bottom dimension w1 of the first protruding microstructure 131 is 0.1 μm to 3 μm, and the height h1 is 0.01 μm to 2 μm; for example, w1 can be 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm, and h1 can be 0.01 μm, 0.05 μm, 0.1 μm, 0.5 μm, 1 μm, 1.5 μm or 2 μm.

[0098] In the second protruding microstructure 132, the bottom dimension w2 is 0.1 μm to 4 μm, and the height h2 is 0.01 μm to 2 μm. For example, w2 can be 0.1 μm, 0.5 μm, 1 μm, 2 μm, 3 μm or 4 μm, and h2 can be 0.01 μm, 0.1 μm, 0.3 μm, 0.5 μm, 1 μm or 2 μm.

[0099] In the third protrusion microstructure 133, the bottom dimension w3 is 0.2 μm to 5 μm, and the height h3 is 0.02 μm to 3 μm; for example, w3 can be 0.2 μm, 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, and h3 can be 0.02 μm, 0.3 μm, 0.5 μm, 0.8 μm, 1 μm, 1.5 μm, 2 μm or 3 μm.

[0100] By setting appropriate size ranges for the raised microstructures 13 in different regions such as the flat structure 11 and the groove structure 12, the formation and expansion of defects in different regions can be better suppressed, thereby improving the interface quality of the back surface of the silicon substrate 1 and helping to improve the passivation performance and long-term stability of the solar cell.

[0101] It should be noted that the dimensions h1 of the first protruding microstructure 131, h2 of the second protruding microstructure 132, and h3 of the third protruding microstructure 133 are measured by taking a section 13a along the thickness direction of the silicon substrate 1 and passing through the center of the corresponding protruding microstructure 13.

[0102] Reference Figures 8-12 In some embodiments, the protruding microstructure 13 is cone-shaped or cone-like.

[0103] The protruding microstructures 13 of the cone or cone-like structure 13b can effectively extend the propagation path of light within the silicon substrate and enhance light absorption efficiency. At the same time, this shape significantly increases the specific surface area of ​​the back surface, providing more interface areas for subsequent deposition of functional films, thereby improving the coverage uniformity and adhesion strength of the functional films.

[0104] Furthermore, the protruding microstructure 13 includes at least one of the following types:

[0105] Conical 13b, such as Figure 8 or Figure 9 As shown in the morphology of the cone-like structure 13b, along the thickness direction of the silicon substrate 1, the side profile of the cross section 13a of the cone-like structure 13b is a smooth curve, and the surface of the cone-like structure is distributed with a number of nanoscale protrusions 13b1. The size d of the nanoscale protrusions 13b1 near the bottom of the cone-like structure 13b is 10 nm to 100 nm; for example, d can be 10 nm, 30 nm, 50 nm, 80 nm or 100 nm.

[0106] Polyhedral pyramid 13c, such as Figure 10 and Figure 11 The polyhedral pyramid 13c is shown in the figure. Polyhedral pyramid 13c is a pyramid with multiple lateral faces and one vertex. The number of lateral faces n of polyhedral pyramid 13c is a positive integer greater than or equal to 4. Polyhedral pyramid 13c includes, as shown in the figure... Figure 10 The first polyhedral cone 13c1 shown and as... Figure 11 The second polyhedral cone 13c2 shown; along the thickness direction of the silicon substrate 1, the angle e1 between the side and the bottom of the first polyhedral cone 13c1 is 20°~40°, and the angle e2 between the side and the bottom of the second polyhedral cone 13c2 is greater than 40° and less than or equal to 70°; for example, e1 can be 20°, 25°, 30°, 35° or 40°, and e2 can be 41°, 51°, 61° or 70°.

[0107] Multi-peaked cone 13d, such as Figure 12 As shown in the morphology of the multifaceted cone 13c, the multi-peaked cone 13d includes a main peak and several sub-peaks. The sub-peaks are located on the side of the main peak, and the sub-peaks face away from the vertex of the silicon substrate 1 and face away from the vertex of the main peak.

[0108] The aforementioned cone-shaped 13b, multifaceted cone 13c, and multi-peaked cone 13d have a larger specific surface area, which is more conducive to increasing the contact area between the silicon substrate 1 and the functional film layer, increasing the carrier transport efficiency, and also more conducive to the deposition and adhesion of the functional film layer in subsequent processes, thus improving the deposition quality of the functional film layer. Furthermore, light is more easily refracted and reflected multiple times in the cone-shaped 13b, multifaceted cone 13c, and multi-peaked cone 13d, thereby better extending the optical path.

[0109] It should be noted that, as Figure 13 As shown, the dimension d of the nanoscale protrusion 13b1 near the bottom of the cone-like body 13b is the projection dimension of the nanoscale protrusion 13b1 onto the cone-like body 13b.

[0110] In some embodiments, on the backlight surface of the silicon substrate 1, the groove structures 12 with raised microstructures 13 are distributed in an isolated manner or partially overlapped.

[0111] The groove structure 12 with protruding microstructure 13 is distributed in an isolated manner, as shown in the example. Figure 14 The groove structure 12 is shown in the black box in the middle;

[0112] When the groove structures 12 are partially overlapping, the groove structures 12 extend and are arranged along a linear pattern, specifically as follows: Figure 15 The black areas shown extend directly in the direction of the grooves, or the groove structures 12 are distributed in clusters, specifically as follows: Figure 16 The groove structure 12 is shown in the black box in the middle.

[0113] The distribution pattern of the groove structure 12 with protruding microstructure 13 corresponds to the common morphology and distribution characteristics of structural defects on the backlight surface. In conventional silicon wafer processing, structural defects tend to present as linear trenches extending along a specific direction or discretely distributed deep pits. By setting the groove structure 12 with protruding microstructure 13 to be linearly extended, clustered, or isolated, and arranging the groove structure 12 with protruding microstructure 13 in a form that adapts to defects such as linear trenches or discretely distributed deep pits, the concentrated growth of defect structures such as trenches and microcracks in defect-prone areas can be more precisely intervened. This allows for effective morphological modification of defect locations and stress concentration areas, suppressing the generation or further development of sharp, geometrically abrupt defect structures, thereby significantly improving the uniformity of passivation and the reliability of defect suppression, and optimizing the overall passivation effect.

[0114] Refer to the return Figure 3 In some embodiments, the back surface of the silicon substrate 1 has a dielectric layer 2, a first doped semiconductor layer 3 and a back surface passivation layer 41 stacked sequentially.

[0115] The backlight surface of the silicon substrate 1 also has a first electrode 5, which passes through the backlight passivation layer 41 to form an ohmic contact with the first doped semiconductor.

[0116] The light-receiving surface of the silicon substrate 1 has a second doped semiconductor layer 6, a light-receiving surface passivation layer 42 disposed on the second doped semiconductor layer 6, and a second electrode 7. The second electrode 7 passes through the light-receiving surface passivation layer 42 and forms an ohmic contact with the second doped semiconductor layer 6.

[0117] The backlight surface of this application suppresses the formation of defects such as trenches by setting protruding microstructures 13. As a result, this application provides a high-quality growth substrate for the dielectric layer 2 and the doped polysilicon layer backlight surface passivation layer 41, so that the dielectric layer 2 and the doped polysilicon layer backlight surface passivation layer can be more uniformly and densely covered on the backlight surface, thereby improving the quality of the film layer and thus exerting a better passivation effect.

[0118] Furthermore, the silicon substrate 1 can be an N-type silicon wafer or a P-type silicon wafer, which can be selected according to the battery type. The material of the dielectric layer 2 can include a variety of dielectric materials, such as at least one of silicon oxide, magnesium fluoride, amorphous silicon, polycrystalline silicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide, or titanium oxide. Specifically, the dielectric layer 2 can be composed of a silicon oxide layer containing silicon oxide. This is because the silicon oxide layer has excellent passivation properties, which can minimize the recombination loss of minority carriers on the surface of the silicon substrate 1. The first doped semiconductor layer 3 can be a doped polycrystalline silicon layer, a doped amorphous silicon layer, or a doped microcrystalline silicon layer, etc. The second doped semiconductor layer 6 is obtained by the diffusion of conductive dopant atoms from the surface of the silicon substrate 1 into the bulk of the silicon substrate 1, and can be a boron diffusion layer, a phosphorus diffusion layer, etc. The second doped semiconductor layer 6 has the opposite conductivity type to the silicon substrate 1, thereby forming a PN junction between them. For example, when the conductivity type of the second doped semiconductor layer 6 is N-type, the conductive dopant atoms of the second doped semiconductor layer 6 are selected from pentavalent atoms such as phosphorus atoms and arsenic atoms. When the conductivity type of the second doped semiconductor layer 6 is P-type, the conductive doping atoms of the second doped semiconductor layer 6 are selected from trivalent atoms such as boron atoms or gallium atoms.

[0119] The materials of the backlight passivation layer 41 and the light-receiving passivation layer 42 include at least one of aluminum oxide, silicon nitride, silicon oxynitride, or silicon oxide. For example, the backlight passivation layer 41 can be an aluminum oxide layer and a silicon nitride layer stacked on the side of the first doped semiconductor layer 3 facing away from the silicon substrate 1. The light-receiving passivation layer 42 can be an aluminum oxide layer, a silicon nitride layer, a silicon oxynitride layer, and a silicon oxide layer stacked on the side of the second doped semiconductor layer 6 facing away from the silicon substrate 1. Further, a side edge passivation layer 43 is also formed on the side surface of the silicon substrate, which can provide a passivation effect to the side surface of the silicon substrate. The side edge passivation layer 43 connects the backlight passivation layer 41 and the light-receiving passivation layer 42, and the material of the side edge passivation layer 43 also includes at least one of aluminum oxide, silicon nitride, silicon oxynitride, or silicon oxide.

[0120] Reference Figure 17 In some embodiments, the backlight surface of the silicon substrate 1 includes a first region 1a and a second region 1b, and a flat structure 11 with a raised microstructure 13 and a groove structure 12 are distributed in the first region 1a.

[0121] The dielectric layer 2 and the first doped semiconductor layer 3 cover the first region 1a, and the backlight passivation layer 41 covers the surface of the first doped semiconductor layer 3 away from the silicon substrate 1 and the second region 1b.

[0122] By patterning the first doped semiconductor layer 3 so that it only covers the first region 1a, the quality of the first doped semiconductor layer 3 can be improved. Meanwhile, the first doped semiconductor layer 3 is not set in the second region 1b. Therefore, compared with the film layer setting method of setting the entire first doped semiconductor layer 3 on the back surface, the above-mentioned setting method of this application embodiment can reduce the optical parasitic absorption caused by the first doped semiconductor layer 3 and effectively improve the performance of the solar cell.

[0123] Secondly, embodiments of this application provide a method for preparing a solar cell.

[0124] A method for fabricating a solar cell, referring to... Figure 18 This includes the following steps:

[0125] like Figure 18 As shown in (a), a silicon substrate 1 with a textured surface on at least the back surface is provided;

[0126] The backlight surface of the silicon substrate 1 is characterized by etching, including: performing a first etching process on the backlight surface of the silicon substrate 1 using a first etching solution containing an inorganic alkali and a texturing additive, forming a groove structure 12 and a flat structure 11 located between adjacent groove structures 12 on the backlight surface of the silicon substrate 1, and forming raised microstructures 13 on the groove structure 12 and the flat structure 11, resulting in... Figure 18 The structure shown in (b) is shown in the image.

[0127] By texturing the silicon substrate 1, a pyramid-shaped textured structure can be formed on both the light-receiving and back-light-receiving surfaces. The textured structure on the light-receiving surface of the silicon substrate 1 can achieve better light absorption. The back-light-receiving surface typically requires polishing to form a relatively flat structure, thereby improving the deposition quality of subsequent functional films (such as dielectric layer 2, doped polysilicon layer, etc.) on the back-light-receiving surface. This application uses a characteristic etching process instead of polishing, specifically using an etching solution with inorganic alkali and texturing additives as the main components to etch the textured back-light-receiving surface of the silicon substrate 1, thereby forming a groove structure 12 with raised microstructures 13 and a flat structure 11 on the back-light-receiving surface. The formation of these raised microstructures 13 effectively improves the quality of the back-light-receiving surface and reduces the generation of defects such as trenches. This also helps to further improve the deposition quality of subsequent functional films grown on the back-light-receiving surface of the silicon substrate 1, achieving further improvement in the passivation performance of the solar cell.

[0128] In some embodiments, the characterization etching process further includes performing a second etching process before performing the first etching process. The second etching process includes performing a second etching process on the back surface of the silicon substrate 1 using a second etching solution containing an inorganic alkali and a polishing additive.

[0129] And / or,

[0130] After the first etching process, a third etching process is performed, which includes: using a third etching solution containing inorganic alkali and texture modification additives to perform a third etching process on the back surface of the silicon substrate 1.

[0131] This application can select different etching process combinations based on the different morphologies of the protruding microstructures 13. When the characteristic etching only performs the first etching process, the formed protruding microstructure 13 is in the shape of a cone 13b, and the overall outline of the cone 13b is relatively smooth. When the characteristic etching process involves performing the second etching process first, followed by the first etching process, the formed protruding microstructure 13 is also in the shape of a cone 13b, and the smoothness of the overall outline of the cone 13b is relatively low. Based on any of the protruding microstructures 13 formed by the first two processes, a third etching process can be performed to modify the surface of the protruding microstructure 13, forming protruding microstructures 13 in shapes such as multifaceted cones 13c and multi-peaked cones 13d.

[0132] Furthermore, the inorganic base includes one or both of sodium hydroxide or potassium hydroxide; the texturing additive includes any one or more combinations of lignin, cellulose or polysaccharides; the polishing additive includes any one or more combinations of quaternary ammonium salts, hydroxyethylidene phosphates or sulfates; and the texture-modifying additive includes any one or more combinations of sodium benzoate, sodium acetate, polyquaternary ammonium salts, cationic guar gum, sorbic acid or citrate.

[0133] Inorganic bases can react with the surface of silicon substrate 1. With the use of texturing additives, polishing additives and texture modification additives, the overall reaction process can be better controlled, thereby forming a specific backlight surface morphology of silicon substrate 1.

[0134] The texturing additive promotes the etching of the

[100] crystal plane of the silicon substrate 1, provides a nucleation center, polishes the back surface of the silicon substrate 1, and promotes the formation of an irregular cone-shaped protruding microstructure 13; the polishing additive promotes the synchronous reaction of different crystal orientations, forms a polished structure on the second surface, and then, in conjunction with the first etching process, can form a protruding microstructure 13 with an arc cone shape; the texture modification additive can slow down the etching rate, regulate the reaction rate ratio of different crystal orientations, and further regulate the morphology of the protruding microstructure 13. After use, it can form a protruding microstructure 13 such as a flat cone, a three-dimensional cone, or a multi-peak cone 13d.

[0135] In some embodiments, the volume concentration of inorganic base in the first etching solution is 0.3 vol%~4 vol%, the volume concentration of texturing additive is 0.001 vol%~0.8 vol%, the reaction time of the first etching treatment is 50 s~200 s, and the reaction temperature is 55℃~75℃.

[0136] In the second etching solution, the volume concentration of inorganic alkali is 0.5 vol%~10 vol%, the volume concentration of polishing additive is 0.002 vol%~5 vol%, the reaction temperature of the second etching treatment is 45℃~75℃, and the reaction time is 50 s~400 s;

[0137] In the third etching solution, the volume concentration of inorganic alkali is 0.1 vol%~6 vol%, the volume concentration of texture modification additive is 0.004 vol%~5 vol%, the reaction temperature of the third etching treatment is 60℃~80℃, and the reaction time of the third etching treatment is 50 s~200 s.

[0138] By controlling the concentration, reaction time, and reaction temperature of each component in the first, second, and third etching solutions respectively, the morphology of the protruding microstructure 13 can be better regulated. Furthermore, the content of the texturing additive used in the first etching solution is in a low range, and the reaction time and reaction temperature are also set at a low level. This can effectively control the density of the protruding microstructure 13 and avoid the excessive density of the protruding microstructure 13 from affecting the deposition quality of the subsequent functional film layer.

[0139] Thirdly, embodiments of this application provide a photovoltaic module.

[0140] A photovoltaic module includes a solar cell as mentioned in the first aspect, or a solar cell prepared by the preparation method mentioned in the second aspect.

[0141] The technical solution of this application will be further described below with reference to more detailed embodiments.

[0142] Example 1

[0143] This application provides a solar cell, the preparation method of which includes the following steps:

[0144] Provide N-type monocrystalline silicon wafers and perform texturing treatment on the N-type monocrystalline silicon wafers to form a pyramid-shaped texturing structure on the entire surface of the N-type monocrystalline silicon wafers;

[0145] Boron diffusion is performed, boron atoms are incorporated into the light-receiving surface of the N-type single-crystal silicon wafer to form a boron diffusion layer, and borosilicate glass layers are formed on the light-receiving surface, backlight surface, and side surface of the N-type single-crystal silicon wafer.

[0146] The first step is to remove the borosilicate glass layer that was coated on the back and sides using a 5% HF solution.

[0147] Characterized etching processes include:

[0148] The first etching process involves etching the back surface and side surface of an N-type single-crystal silicon wafer using a first etching solution. The etching reaction temperature is 75°C, and the time is 150 s. The first etching solution contains sodium hydroxide with a volume concentration of 2 vol% and sodium hydroxide with a volume concentration of 0.003... After the first etching process, vol% lignin forms a flat structure and a groove structure with a relatively flat depression on the back and side surfaces of an N-type single-crystal silicon wafer. Both the flat and groove structures contain raised microstructures, which are pyramidal in shape. The density of these raised microstructures on the surface of the groove structure is greater than that on the surface of the flat structure. The groove structure includes a groove sidewall and a groove bottom, with the boundary between the sidewall and the bottom forming the inner edge of the groove. From the direction away from the inner edge of the groove towards the inner edge, the bottom size of the raised microstructures increases. The raised microstructures include a first raised microstructure, a second raised microstructure, and a third raised microstructure, with the bottom size increasing sequentially. The bottom size w1 of the first raised microstructure is 0.1 μm to 3 μm, and the height h1 is 0.01 μm to 2 μm. The first raised microstructure is distributed on the bottom of both the flat and groove structures. The bottom size w2 of the second raised microstructure is 0.1 μm to 4 μm, and the height h2 is 0.01 μm. The second protruding microstructure is distributed on the sidewall of the groove structure, and the bottom size w3 of the third protruding microstructure is 0.2 μm to 5 μm, and the height h3 is 0.02 μm to 3 μm. The third protruding microstructure is distributed in the area of ​​the sidewall of the groove near the inner edge of the groove and the area of ​​the bottom of the groove near the inner edge of the groove.

[0149] A silicon oxide dielectric layer and an N-type doped polycrystalline silicon layer with phosphorus atoms were prepared by plasma chemical vapor deposition. A phosphosilicate glass layer was also formed on the side of the doped polycrystalline silicon layer away from the N-type single crystal silicon wafer. When forming the silicon oxide dielectric layer, the N-type doped polycrystalline silicon layer and the phosphosilicate glass layer, a silicon oxide dielectric layer, an N-type doped polycrystalline silicon layer and a phosphosilicate glass layer were also formed on the side and the light-receiving side of the N-type single crystal silicon wafer.

[0150] The second process involves removing the borosilicate glass layer that is coated around the light-receiving surface and side of the N-type monocrystalline silicon wafer using a 5% HF solution. Then, a 1% sodium hydroxide solution is used to remove the silicon oxide dielectric layer and the N-type doped polycrystalline silicon layer that are coated around the light-receiving surface and side of the N-type monocrystalline silicon wafer. Finally, a 5% HF solution is used to remove the remaining borosilicate glass layer on one side of the light-receiving surface.

[0151] A passivation layer is prepared by plasma chemical vapor deposition. The passivation layer is made of silicon nitride. The passivation layer simultaneously covers the surface of the N-type doped polycrystalline silicon layer away from the N-type single crystal silicon wafer, the side of the N-type single crystal silicon wafer, and the surface of the boron diffusion layer away from the N-type single crystal silicon wafer. The passivation layer covering the surface of the N-type doped polycrystalline silicon layer away from the N-type single crystal silicon wafer is the backlight passivation layer, and the passivation layer of the boron diffusion layer away from the surface of the N-type single crystal silicon wafer is the light-receiving passivation layer.

[0152] A first electrode and a second electrode are fabricated such that the first electrode passes through the passivation layer on the backlight side and forms an ohmic contact with the N-type doped polycrystalline silicon layer, and the second electrode passes through the passivation layer on the light-receiving side and forms an ohmic contact with the boron diffusion layer.

[0153] Example 2

[0154] This application provides a solar cell, which differs from Embodiment 1 in that the shape of the protruding microstructure is different, and the characteristic etching process includes:

[0155] First, a second etching process is performed: the back surface and side surface of the N-type single crystal silicon wafer are etched using a second etching solution. The etching reaction temperature is 60℃ and the time is 150 s. The first etching solution contains sodium hydroxide with a volume concentration of 1 vol% and hydroxyethylidene diphosphate with a volume concentration of 0.05 vol%. Then, the first etching process is performed.

[0156] Everything else remains the same as in Example 1.

[0157] Example 3

[0158] This application provides a solar cell, which differs from Embodiment 2 in that the shape of the protruding microstructure is different, and the characteristic etching process includes:

[0159] First, a second etching process is performed: the back surface and side surface of the N-type single crystal silicon wafer are etched using a second etching solution. The etching reaction temperature is 60℃ and the time is 150 s. The first etching solution contains sodium hydroxide with a volume concentration of 1 vol% and hydroxyethylidene diphosphate with a volume concentration of 0.05 vol%.

[0160] Next, the first etching process is performed;

[0161] Then, a third etching process is performed: the back surface and side surface of the N-type single crystal silicon wafer are etched using a third etching solution. The etching reaction temperature is 70℃ and the time is 90 s. The first etching solution contains sodium hydroxide with a volume concentration of 0.5 vol% and sodium benzoate with a volume concentration of 0.02 vol%.

[0162] Everything else remains the same as in Example 2.

[0163] Comparative Example 1

[0164] This application provides a solar cell, which differs from Embodiment 1 in that: the back surface of the silicon substrate has a groove structure with the planar structure being recessed relative to the planar structure, and no protruding microstructures are provided on the planar structure and the groove structure. Specifically, in the solar cell manufacturing process, a second etching process is used instead of the first etching process, and the rest is consistent with Embodiment 1.

[0165] experiment

[0166] Solar cell performance testing

[0167] The performance of solar cells was tested using an IV tester under standard test conditions: AM1.5, 1000 W / m. 2 The test environment temperature was 25℃. Before the test, the simulated sunlight intensity was calibrated using a standard silicon solar cell. The differences in open-circuit voltage (Voc), short-circuit current (Jsc), fill factor (FF), photoelectric conversion efficiency (EFF), and bifaciality of the corresponding solar cells relative to their corresponding control groups were recorded. Photoelectric conversion efficiency refers to the test result of the photoelectric conversion efficiency of the solar cell's light-receiving side, and bifaciality refers to the ratio of the efficiency of the back-lighting side to the efficiency of the light-receiving side.

[0168] Table 1

[0169]

[0170] As can be seen from the comparison of the data of Examples 1 to 3 and Comparative Example 1 in Table 1, the electrical performance of the solar cell in Example 1, such as photoelectric conversion efficiency, fill factor and bifaciality, is improved. This proves that by setting the protruding microstructure on the back surface, it is possible to improve light absorption and reduce carrier recombination loss on the back surface, thereby effectively improving the performance of the solar cell.

[0171] The technical solutions disclosed in the embodiments of this application have been described in detail above. Specific examples have been used in this article to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core inventive points of the embodiments of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A solar cell, characterized by, The solar cell includes a silicon substrate. The back surface of the silicon substrate has a flat structure and a plurality of groove structures that are recessed relative to the flat structure. The surfaces of the flat structure and the groove structures are provided with a plurality of protruding microstructures. The area ratio of the protruding microstructures on the surface of the groove structure is higher than the area ratio of the protruding microstructures on the surface of the flat structure.

2. The solar cell according to claim 1, characterized in that, The groove structure includes a groove bottom and a groove sidewall extending from the periphery of the groove bottom toward the flat structure, wherein the groove sidewall intersects with the groove bottom to form the inner edge of the groove; Along the sidewall surface of the groove, from the direction away from the inner edge of the groove to the direction closer to the inner edge of the groove, the bottom dimension of the protruding microstructure tends to increase; Along the bottom of the groove, from the direction away from the inner edge of the groove to the direction closer to the inner edge of the groove, the bottom dimension of the protruding microstructure tends to increase; The bottom dimension of the protruding microstructure is w, where w is the maximum width dimension of the bottom of the protruding microstructure in contact with the silicon substrate.

3. The solar cell according to claim 2, characterized in that, In the protruding microstructure, w is 0.01 μm to 5 μm and the height h is 0.01 μm to 3 μm; In a cross-section along the thickness direction of the silicon substrate and passing through the center of the protruding microstructure, the angle e between the bottom and the side is 20°~70°.

4. The solar cell according to claim 2, characterized in that, The protruding microstructure includes a first protruding microstructure, a second protruding microstructure, and a third protruding microstructure, wherein the bottom dimensions of the first protruding microstructure, the second protruding microstructure, and the third protruding microstructure increase sequentially, wherein: The first protruding microstructures are distributed on the bottom of the groove in the flat structure and the groove structure. The groove sidewall of the groove structure is provided with the second protruding microstructure; The third protruding microstructure is distributed in the region of the sidewall of the groove near the inner edge of the groove and in the region of the bottom of the groove near the inner edge of the groove.

5. The solar cell according to claim 4, characterized in that, In the first protruding microstructure, the bottom dimension is w1, where w1 is 0.1 μm to 3 μm, and the height h1 is 0.01 μm to 2 μm; In the second protruding microstructure, the bottom dimension is w2, which is 0.1 μm to 4 μm, and the height h2 is 0.01 μm to 2 μm; In the third protruding microstructure, the bottom dimension is w3, which is 0.2 μm to 5 μm, and the height h3 is 0.02 μm to 3 μm.

6. The solar cell according to claim 1, characterized in that, The protruding microstructures are cone-shaped or cone-like.

7. The solar cell according to claim 6, characterized in that The protruding microstructures include at least one of the following types: The cone-shaped structure has a smooth curve on the side profile of its cross-section along the thickness direction of the silicon substrate. The surface of the cone-shaped structure is distributed with several nanoscale protrusions, and the nanoscale protrusions have a size of 10 nm to 100 nm near the bottom of the cone-shaped structure. A multifaceted cone, wherein the multifaceted cone is a cone having multiple sides and one vertex, the number of sides n of the multifaceted cone being a positive integer greater than or equal to 4, the multifaceted cone including a first multifaceted cone and a second multifaceted cone; along the thickness direction of the silicon substrate, the angle between the side and the bottom of the first multifaceted cone is e1, wherein e1 is 20°~40°, and the angle between the side and the bottom of the second multifaceted cone is e2, wherein e2 is greater than 40° and less than or equal to 70°; A multi-peak cone, comprising a main peak and several sub-peaks, wherein the sub-peaks are disposed on the side of the main peak, and the apex of the sub-peaks facing away from the silicon substrate faces the apex of the main peak facing away from the silicon substrate.

8. The solar cell according to claim 1, characterized in that, On the backlight surface of the silicon substrate, the groove structures with the protruding microstructures are distributed in an isolated or partially overlapping manner; When the groove structures are partially overlapping, the groove structures extend along a line or are distributed in a cluster.

9. The solar cell according to claim 1, characterized in that, The back surface of the silicon substrate has a dielectric layer, a first doped semiconductor layer and a back surface passivation layer stacked sequentially. The backlight surface of the silicon substrate also has a first electrode, which forms an ohmic contact with the first doped semiconductor layer through the passivation layer of the backlight surface. The light-receiving surface of the silicon substrate has a second doped semiconductor layer, a light-receiving surface passivation layer disposed on the second doped semiconductor layer, and a second electrode, wherein the second electrode passes through the light-receiving surface passivation layer and forms an ohmic contact with the second doped semiconductor layer.

10. The solar cell according to claim 9, characterized in that, The backlight surface of the silicon substrate includes a first region and a second region, and the flat structure and the groove structure having the protruding microstructure are distributed in the first region; The dielectric layer and the first doped semiconductor layer cover the first region, and the backlight passivation layer covers the surface of the first doped semiconductor layer away from the silicon substrate and the second region.

11. A method of producing a solar cell, characterized by, Includes the following steps: Provide a silicon substrate with at least a textured back surface; The backlight surface of the silicon substrate is characterized by etching, including: performing a first etching process on the backlight surface of the silicon substrate using a first etching solution containing an inorganic alkali and a texturing additive, forming a groove structure and a flat structure located between adjacent groove structures on the backlight surface of the silicon substrate, and forming raised microstructures on the groove structure and the flat structure, wherein the area ratio of the raised microstructure on the surface of the groove structure is higher than the area ratio of the raised microstructure on the surface of the flat structure.

12. The method for manufacturing a solar cell according to claim 11, wherein The characterization etching process further includes performing a second etching process before performing the first etching process. The second etching process includes performing the second etching process on the back surface of the silicon substrate using a second etching solution containing the inorganic alkali and polishing additives. And / or, After the first etching process, a third etching process is performed, which includes: using a third etching solution containing the inorganic alkali and texture modification additives to perform the third etching process on the back surface of the silicon substrate.

13. The method of producing a solar cell according to claim 12, wherein The inorganic base includes one or both of sodium hydroxide and potassium hydroxide; the texturing additive includes any one or more combinations of lignin, cellulose, or polysaccharides; the polishing additive includes any one or more combinations of quaternary ammonium salts, hydroxyethylidene phosphates, or sulfates; and the texture modification additive includes any one or more combinations of sodium benzoate, sodium acetate, polyquaternary ammonium salts, cationic guar gum, sorbic acid, or citrate.

14. The method of producing a solar cell according to claim 12, wherein In the first etching solution, the volume concentration of the inorganic alkali is 0.3 vol%~4 vol%, the volume concentration of the texturing additive is 0.001 vol%~0.8 vol%, the reaction time of the first etching treatment is 50 s~200 s, and the reaction temperature is 55℃~75℃. In the second etching solution, the volume concentration of the inorganic alkali is 0.5 vol%~10 vol%, the volume concentration of the polishing additive is 0.002 vol%~5 vol%, the reaction temperature of the second etching treatment is 45℃~75℃, and the reaction time is 50 s~400 s; In the third etching solution, the volume concentration of the inorganic alkali is 0.1 vol% to 6 vol%, the volume concentration of the texture modification additive is 0.004 vol% to 5 vol%, the reaction temperature of the third etching treatment is 60℃ to 80℃, and the reaction time of the third etching treatment is 50 s to 200 s.

15. A photovoltaic module, characterized by This includes solar cells as described in any one of claims 1-10, or solar cells prepared by the method described in any one of claims 11-14.

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