Fabrication method of back contact solar cell and back contact solar cell

Abstract

This application discloses a method for fabricating a back-contact solar cell and the back-contact solar cell itself, belonging to the field of solar cell technology. The method includes: forming a groove on one side of a silicon substrate; sequentially fabricating a tunneling oxide layer and an intrinsic polycrystalline silicon layer on one side of the silicon substrate; fabricating a first doped silicon oxide layer on the intrinsic polycrystalline silicon layer; removing the first doped silicon oxide layer located outside the groove to expose the intrinsic polycrystalline silicon layer; advancing a dopant source from the first doped silicon oxide layer located within the groove to the intrinsic polycrystalline silicon layer to form the first doped polycrystalline silicon layer; fabricating a second doped silicon oxide layer with a doping type opposite to that of the first doped silicon oxide layer on the intrinsic polycrystalline silicon layer located outside the groove; and advancing a dopant source from the second doped silicon oxide layer located outside the groove to the intrinsic polycrystalline silicon layer to form the second doped polycrystalline silicon layer. This method eliminates the need for multiple masking and paste printing steps, shortening the process, reducing fabrication costs, and improving production efficiency, thus facilitating mass production of solar cells.

Description

Technical Field

[0001] This application belongs to the field of solar cell technology, and particularly relates to a method for preparing a back-contact solar cell and the back-contact solar cell itself. Background Technology

[0002] In back-contact batteries, the metal electrode is located on the back side of the battery, and the light-receiving side is unobstructed by the metal electrode, resulting in high light utilization. However, the passivation contact performance is poor. By optimizing the passivation contact performance of back-contact batteries using TOPCon technology, tunnel oxide passivated back-contact batteries (TBCs) are obtained, which can improve the photoelectric conversion efficiency of the batteries.

[0003] Currently, the back-side fabrication process of TBC batteries mostly adopts a multi-step masking and paste printing method. After transferring phosphorus paste and boron paste onto the substrate, the n-region and p-region are separated by laser grooving. This method is complicated and costly, which affects the production efficiency of the battery and makes it difficult to achieve large-scale mass production of TBC batteries. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a method for fabricating a back-contact solar cell and a back-contact solar cell, which can shorten the process steps, reduce fabrication costs, effectively improve production efficiency, and contribute to the mass production of TBC cells.

[0005] In a first aspect, this application provides a method for fabricating a back-contact solar cell, comprising:

[0006] A groove is formed on one side of the silicon substrate;

[0007] A tunneling oxide layer and an intrinsic polycrystalline silicon layer are sequentially formed on one side of the silicon substrate;

[0008] A first doped silicon oxide layer is prepared on the intrinsic polycrystalline silicon layer;

[0009] Remove the first doped silicon oxide layer located outside the groove to expose the intrinsic polysilicon layer;

[0010] The doping source of the first doped silicon oxide layer located in the groove is pushed to the intrinsic polysilicon layer to form the first doped polysilicon layer;

[0011] A second doped silicon oxide layer with the opposite doping type to the first doped silicon oxide layer is prepared on the intrinsic polycrystalline silicon layer located outside the groove;

[0012] The doping source of the second doped silicon oxide layer located outside the groove is pushed into the intrinsic polysilicon layer to form the second doped polysilicon layer.

[0013] According to the back-contact solar cell fabrication method of this application, a tunneling oxide layer and an intrinsic polycrystalline silicon layer are sequentially fabricated by opening a groove in a silicon substrate. A first doped silicon oxide layer and a second doped silicon oxide layer with opposite doping types are used to fabricate a first doped polycrystalline silicon layer inside the groove and a second doped polycrystalline silicon layer outside the groove. The fabrication process involves opening a groove in one step, eliminating the need for multiple masking and paste printing steps. This can shorten the process, reduce the fabrication cost, effectively improve production efficiency, and facilitate the mass production of the cells.

[0014] According to one embodiment of this application, the intrinsic polysilicon layer on the sidewall of the groove forms an isolation layer that separates the first doped polysilicon layer and the second doped polysilicon layer.

[0015] According to one embodiment of this application, the thickness of the isolation layer along the width direction of the groove is 50μm-80μm.

[0016] According to one embodiment of this application, the depth of the groove is 400nm-600nm.

[0017] According to one embodiment of this application, the width of the groove is 700μm-800μm.

[0018] According to one embodiment of this application, the doping source of the first doped silicon oxide layer is boron, and the doping source of the second doped silicon oxide layer is phosphorus.

[0019] According to one embodiment of this application, advancing the dopant source of the first doped silicon oxide layer located in the groove to the intrinsic polysilicon layer includes:

[0020] Laser propulsion is performed on the first doped silicon oxide layer located in the groove to advance the dopant source of the first doped silicon oxide layer into the intrinsic polycrystalline silicon layer along the direction toward the intrinsic polycrystalline silicon layer.

[0021] According to one embodiment of this application, advancing the dopant source of the second doped silicon oxide layer located outside the groove to the intrinsic polysilicon layer includes:

[0022] The second doped silicon oxide layer located outside the groove is advanced at high temperature to diffuse the dopant source of the second doped silicon oxide layer into the intrinsic polycrystalline silicon layer.

[0023] According to one embodiment of this application, the fabrication of a first doped silicon oxide layer on the intrinsic polycrystalline silicon layer includes:

[0024] Preparation of the first doped silicon oxide solution;

[0025] The first doped silicon oxide solution is coated onto the side of the intrinsic polycrystalline silicon layer opposite to the tunneling oxide layer and cured to form the first doped silicon oxide layer.

[0026] According to one embodiment of this application, removing the first doped silicon oxide layer located outside the groove includes:

[0027] The first doped silicon oxide layer outside the groove is subjected to chain cleaning.

[0028] Secondly, this application provides a back-contact solar cell, the cell comprising:

[0029] A silicon substrate, wherein one side of the silicon substrate has a groove;

[0030] A tunneling oxide layer is disposed on one side of the silicon substrate;

[0031] A first doped polysilicon layer and a second doped polysilicon layer with opposite doping types are disposed on the side of the tunneling oxide layer facing away from the silicon substrate. The first doped polysilicon layer is located inside the groove, and the second doped polysilicon layer is located outside the groove.

[0032] According to the back-contact solar cell of this application, a groove is formed in the silicon substrate, a first doped silicon oxide layer is formed in the groove, and a second doped silicon oxide layer is formed outside the groove. The two doped polycrystalline silicon layers are separated by the height difference between the inside and outside of the groove. After the doped polycrystalline silicon layers are prepared, there is no need to use laser to separate the n-region and p-region, which can reduce laser damage to the back-contact solar cell and effectively improve the photoelectric conversion efficiency of the back-contact solar cell.

[0033] According to one embodiment of this application, the intrinsic polysilicon layer on the sidewall of the groove forms an isolation layer that separates the first doped polysilicon layer and the second doped polysilicon layer.

[0034] According to one embodiment of this application, the thickness of the isolation layer along the width direction of the groove is 50μm-80μm.

[0035] According to one embodiment of this application, the depth of the groove is 400nm-600nm.

[0036] According to one embodiment of this application, the width of the groove is 700μm-800μm.

[0037] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0038] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0039] Figure 1 This is a schematic flowchart of the method for fabricating a back-contact solar cell provided in the embodiments of this application;

[0040] Figure 2 This is a schematic diagram of the structure with grooves in the fabrication method of the back contact solar cell provided in the embodiments of this application;

[0041] Figure 3 This is a schematic diagram of the structure for preparing the tunneling oxide layer and the intrinsic polycrystalline silicon layer in the method for preparing a back contact solar cell provided in this application embodiment;

[0042] Figure 4 This is a schematic diagram of the structure for preparing the first doped silicon oxide layer in the method for preparing a back contact solar cell provided in this application embodiment;

[0043] Figure 5 This is a schematic diagram of the structure of the first doped silicon oxide layer outside the groove in the fabrication method of the back contact solar cell provided in the embodiments of this application;

[0044] Figure 6 This is a schematic diagram of the structure for forming the first doped polycrystalline silicon layer in the method for fabricating a back-contact solar cell provided in this application embodiment;

[0045] Figure 7 This is a schematic diagram of the structure for preparing the second doped silicon oxide layer in the method for preparing a back contact solar cell provided in this application embodiment;

[0046] Figure 8 This is a schematic diagram of the structure for forming the second doped polycrystalline silicon layer in the method for fabricating a back-contact solar cell provided in this application embodiment;

[0047] Figure 9 This is one of the structural schematic diagrams of a back-contact solar cell provided in the embodiments of this application;

[0048] Figure 10 This is the second schematic diagram of the back-contact solar cell provided in the embodiments of this application.

[0049] Figure label:

[0050] Silicon substrate 210, trench 211, tunneling oxide layer 220, intrinsic polysilicon layer 230, first doped polysilicon layer 231, second doped polysilicon layer 232, isolation layer 233.

[0051] First doped silicon oxide layer 241, second doped silicon oxide layer 242, antireflection layer 260. Detailed Implementation

[0052] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0053] The following is in conjunction with the appendix Figures 1 to 10 The preparation method of the back contact solar cell and the back contact solar cell provided in this application are described in detail through specific embodiments and application scenarios.

[0054] like Figure 1 As shown, the method for preparing a back-contact solar cell according to an embodiment of this application includes steps 110 to 170.

[0055] Step 110: A groove 211 is formed on one side of the silicon substrate 210.

[0056] The silicon substrate 210 can be an N-type silicon wafer or a P-type silicon wafer.

[0057] It is understandable that the electrodes of the back contact solar cell are located on the back surface, and a groove 211 is formed on one side of the silicon substrate 210, so the groove 211 can be formed on the back surface of the silicon substrate 210.

[0058] In actual implementation, grooves 211 can be formed on the back surface of silicon substrate 210 by laser grooving. One or more grooves 211 can be formed along a first direction parallel to the plane of silicon substrate 210, and there is a certain distance between the grooves 211.

[0059] like Figure 2 As shown, a groove 211 is formed on the back surface of the silicon substrate 210. The bottom of the groove 211 and the back surface of the silicon substrate 210 outside the groove 211 form a certain height difference, which facilitates the subsequent preparation of doped polycrystalline silicon of different doping types in the areas inside and outside the groove 211.

[0060] In this embodiment, before the groove 211 is formed on the back surface of the silicon substrate 210, the light-receiving surface of the silicon substrate 210 can be texturized to form a textured surface, thereby enhancing the absorption of sunlight and reducing reflection.

[0061] In practice, the original N-type silicon wafer can be immersed in a KOH or NaOH solution with a mass fraction of 1%-3% at a temperature of 60℃-80℃ for texturing, and the texturing time is controlled to be 15min-25min.

[0062] Step 120: A tunneling oxide layer 220 and an intrinsic polycrystalline silicon layer 230 are sequentially prepared on one side of the silicon substrate 210.

[0063] In this step, a tunneling oxide layer 220 and an intrinsic polysilicon layer 230 are prepared on one side of the silicon substrate 210 where the trenching operation is performed. The tunneling oxide layer 220 and the intrinsic polysilicon layer 230 are stacked in both the area inside and outside the trench 211.

[0064] For example, such as Figure 3 As shown, a tunneling oxide layer 220 and an intrinsic polycrystalline silicon layer 230 are sequentially prepared on the back surface of a silicon substrate 210, and the silicon substrate 210, the tunneling oxide layer 220 and the intrinsic polycrystalline silicon layer 230 are stacked sequentially from top to bottom.

[0065] In this embodiment, the intrinsic polysilicon layer 230 is used to form a doped polysilicon layer, and the tunneling oxide layer 220 and the doped polysilicon layer can form a passivated contact structure, which can effectively reduce carrier recombination.

[0066] It is understandable that the silicon substrate 210, the tunneling oxide layer 220 and the intrinsic polycrystalline silicon layer 230 are stacked in sequence to form a back contact solar cell (TBC).

[0067] Step 130: Prepare a first doped silicon oxide layer 241 on the intrinsic polycrystalline silicon layer 230.

[0068] In this step, a first doped silicon oxide layer 241 is prepared on the side of the intrinsic polysilicon layer 230 that is opposite to the tunneling oxide layer 220.

[0069] The first doped silicon oxide layer 241 is a silicon oxide layer with a doping source. The doping source of the first doped silicon oxide layer 241 can be pushed into the intrinsic polysilicon layer 230 to obtain a doped polysilicon layer.

[0070] For example, the first doped silicon oxide layer 241 can be borosilicate glass (BSG), that is, the first doped silicon oxide layer 241 is silicon dioxide with boron as the dopant source.

[0071] In this embodiment, such as Figure 4 As shown, a first doped silicon oxide layer 241 is prepared on the intrinsic polysilicon layer 230. The first doped silicon oxide layer 241 is prepared in both the area inside and outside the groove 211, and the first doped silicon oxide layer 241 fills the groove 211.

[0072] In actual implementation, the side of the first doped silicon oxide layer 241 that is away from the intrinsic polysilicon layer 230 can be a plane, and the thickness of the first doped silicon oxide layer 241 outside the groove 211 is less than the thickness inside the groove 211.

[0073] Step 140: Remove the first doped silicon oxide layer 241 located outside the groove 211 to expose the intrinsic polysilicon layer 230.

[0074] In this step, such as Figure 5 As shown, the first doped silicon oxide layer 241 located outside the groove 211 is removed, while the first doped silicon oxide layer 241 inside the groove 211 is retained.

[0075] In this embodiment, the first doped silicon oxide layer 241 is completely removed in the area outside the groove 211, exposing the intrinsic polysilicon layer 230 in the area outside the groove 211, so as to avoid affecting the area outside the groove 211 when the doping source of the first doped silicon oxide layer 241 is subsequently pushed into the intrinsic polysilicon layer 230.

[0076] It is understandable that the thickness of the first doped silicon oxide layer 241 outside the groove 211 is less than the thickness inside the groove 211. Based on the thickness distribution, the thickness value of the first doped silicon oxide layer 241 to be removed can be set, thereby removing the first doped silicon oxide layer 241 outside the groove 211 and retaining the first doped silicon oxide layer 241 inside the groove 211. The first doped silicon oxide layer 241 inside the groove 211 is used to dope the intrinsic polycrystalline silicon layer 230 inside the groove 211 to prepare the doped polycrystalline silicon layer.

[0077] Step 150: Push the doping source of the first doped silicon oxide layer 241 located in the groove 211 to the intrinsic polysilicon layer 230 to form the first doped polysilicon layer 231.

[0078] In this step, such as Figure 6 As shown, the doping source of the first doped silicon oxide layer 241 located in the groove 211 is pushed to the intrinsic polysilicon layer 230 for doping operation to obtain the first doped polysilicon layer 231.

[0079] It is understood that the first doped silicon oxide layer 241 outside the groove 211 has been removed. When the doping source of the first doped silicon oxide layer 241 is advanced, the intrinsic polysilicon layer 230 inside the groove 211 is doped, and the first doped polysilicon layer 231 is formed in the corresponding region inside the groove 211.

[0080] For example, the first doped silicon oxide layer 241 can be BSG, and the doping source is boron. The doping source of the first doped silicon oxide layer 241 located in the groove 211 is pushed to the intrinsic polycrystalline silicon layer 230 to obtain the first doped polycrystalline silicon layer 231 with boron as the doping source. The first doped polycrystalline silicon layer 231 in the groove 211 can be used as the p-region of the back contact solar cell.

[0081] Step 160: Prepare a second doped silicon oxide layer 242 on the intrinsic polysilicon layer 230 located outside the groove 211, which has a doping type opposite to that of the first doped silicon oxide layer 241.

[0082] It should be noted that after the intrinsic polysilicon layer 230 in the groove 211 is doped by the first doped silicon oxide layer 241 in the groove 211, the first doped silicon oxide layer 241 in the groove 211 is retained, and then the second doped silicon oxide layer 242 is prepared. The second doped silicon oxide layer 242 is formed on the polysilicon substrate. The first doped silicon oxide layer 241 in the groove 211 can make the second doped silicon oxide layer 242 form in the region outside the groove 211.

[0083] like Figure 7 As shown, a second doped silicon oxide layer 242 is prepared on the intrinsic polysilicon layer 230 outside the groove 211. The second doped silicon oxide layer 242 is used to prepare the second doped polysilicon layer 232 in the region outside the groove 211.

[0084] The first doped silicon oxide layer 241 and the second doped silicon oxide layer 242 have opposite doping types.

[0085] For example, the first doped silicon oxide layer 241 can be BSG, and the doping source of the first doped silicon oxide layer 241 is boron; the second doped silicon oxide layer 242 can be phosphosilicate glass (PSG), and the doping source of the second doped silicon oxide layer 242 is phosphorus.

[0086] Step 170: Push the doping source of the second doped silicon oxide layer 242 located outside the groove 211 to the intrinsic polysilicon layer 230 to form the second doped polysilicon layer 232.

[0087] It is understandable that the doping types of the first doped silicon oxide layer 241 and the second doped silicon oxide layer 242 are opposite, and the doping types of the first doped polysilicon layer 231 prepared by the first doped silicon oxide layer 241 and the second doped polysilicon layer 232 prepared by the second doped silicon oxide layer 242 are also opposite.

[0088] In this embodiment, such as Figure 8 As shown, the doping source of the second doped silicon oxide layer 242 located outside the groove 211 is pushed to the intrinsic polysilicon layer 230, forming the second doped polysilicon layer 232 outside the groove 211, and the first doped polysilicon layer 231 inside the groove 211.

[0089] For example, the first doped silicon oxide layer 241 can be BSG with boron as the doping source, the second doped silicon oxide layer 242 can be PSG with phosphorus as the doping source, the first doped polycrystalline silicon layer 231 inside the groove 211 can be used as the p region of the back contact solar cell, and the second doped polycrystalline silicon layer 232 outside the groove 211 can be used as the n region of the back contact solar cell.

[0090] The tunneling oxide layer 220 and the first doped polycrystalline silicon layer 231 inside the groove 211 form a passivated contact structure, and the tunneling oxide layer 220 and the second doped polycrystalline silicon layer 232 outside the groove 211 form a passivated contact structure, which can effectively reduce carrier recombination in the back contact solar cell and improve the photoelectric conversion efficiency of the cell.

[0091] In actual implementation, after preparing the first doped polycrystalline silicon layer 231 and the second doped polycrystalline silicon layer 232, as follows: Figure 9 As shown, the doped silicon oxide layer on the side of the doped polysilicon layer facing away from the tunneling oxide layer 220 can be removed, i.e., the first doped silicon oxide layer 241 and the second doped silicon oxide layer 242 can be removed, as shown. Figure 10 As shown, an antireflection layer 260 is prepared on the side of the doped polycrystalline silicon layer away from the tunneling oxide layer 220, and a cell is prepared on the side of the antireflection layer 260 away from the doped polycrystalline silicon layer to obtain a back contact solar cell.

[0092] It should be noted that when the dopant source of the second doped silicon oxide layer 242 located outside the groove 211 is pushed into the intrinsic polysilicon layer 230, the first doped silicon oxide layer 241 retained in the groove 211 acts as a mask, so that the dopant source of the second doped silicon oxide layer 242 will not enter the region where the first doped polysilicon layer 231 is located.

[0093] In related technologies, the back-side fabrication process of TBC batteries mostly adopts a multi-step masking and paste printing method. After transferring phosphorus paste and boron paste onto the substrate, the n-region and p-region are separated by laser grooving. This method is complicated and costly, which affects the production efficiency of the battery and makes it difficult to achieve large-scale mass production of TBC batteries.

[0094] In this embodiment, a first doped silicon oxide layer 241 is formed by creating a groove 211 in the silicon substrate 210. After removing the first doped silicon oxide layer 241 outside the groove 211, a doping source advancement operation is performed to form a first doped polycrystalline silicon layer 231 inside the groove 211. The first doped silicon oxide layer 241 inside the groove 211 acts as a barrier. A second doped silicon oxide layer 242 is formed outside the groove 211, and a doping source advancement operation is performed. The doping source of the second doped silicon oxide layer 242 cannot diffuse into the area inside the groove 211. The second doped polycrystalline silicon layer 232 is formed outside the groove 211, forming the p-region and n-region of the back contact solar cell. Only one groove is needed, reducing the risk of laser damage. The doped silicon oxide layer inside the groove 211 acts as a mask, eliminating the need for multiple masking steps and printing paste, which can shorten the process, reduce the manufacturing cost, and effectively improve production efficiency, thus facilitating the mass production of the battery. At the same time, the groove 211 is created before the preparation of the doped polycrystalline silicon, which can avoid damage to the doped polycrystalline silicon and other layered structures by laser operation.

[0095] According to the back-contact solar cell fabrication method provided in the embodiments of this application, a tunneling oxide layer 220 and an intrinsic polycrystalline silicon layer 230 are sequentially fabricated by forming a groove 211 in a silicon substrate 210. A first doped polycrystalline silicon layer 231 is fabricated in the groove 211 using a first doped silicon oxide layer 241 and a second doped silicon oxide layer 242 with opposite doping types, and a second doped polycrystalline silicon layer 232 is fabricated outside the groove 211. The fabrication process involves only one groove forming, eliminating the need for multiple masking and paste printing steps, which can shorten the process, reduce the fabrication cost, effectively improve production efficiency, and facilitate the mass production of the cell.

[0096] In some embodiments, the intrinsic polysilicon layer 230 on the sidewall of the groove 211 forms an isolation layer 233, which separates the first doped polysilicon layer 231 and the second doped polysilicon layer 232.

[0097] like Figure 8 As shown, the intrinsic polycrystalline silicon layer 230 on the sidewall of the groove 211 forms an isolation layer 233. The isolation layer 233 separates the two doped polycrystalline silicon layers with opposite doping types in a first direction from left to right and a second direction from top to bottom, so as to avoid the p-region and n-region of the back-contact solar cell from affecting each other.

[0098] In most related technologies, after laser transfer of phosphorus paste and boron paste onto the substrate, the n-region and p-region are isolated by laser grooving. However, the laser operation can damage the doped polysilicon in the n-region and p-region.

[0099] In this embodiment, an isolation layer 233 is formed by the intrinsic polycrystalline silicon layer 230 left on the sidewall of the groove 211 to isolate the p-region and n-region of the back-contact solar cell. The boundary between the n-region and the p-region is the intrinsic polycrystalline silicon layer 230, which avoids the p-region and the n-region from affecting each other and can also reduce the damage caused by laser grooving to isolate the n-region and the p-region.

[0100] It is understandable that when preparing the tunneling oxide layer 220 and the intrinsic polysilicon layer 230, the tunneling oxide layer 220 and the intrinsic polysilicon layer 230 are formed inside the groove 211, outside the groove 211, and on the sidewall of the groove 211.

[0101] like Figure 5 As shown, when the first doped silicon oxide layer 241 located outside the groove 211 is removed, the intrinsic polysilicon layer 230 outside the groove 211 and on the sidewalls of the groove 211 is exposed, as shown. Figure 6 As shown, the doping source of the first doped silicon oxide layer 241 advances into the intrinsic polysilicon layer 230 within the groove 211 without affecting the intrinsic polysilicon layer 230 on the sidewall of the groove 211.

[0102] like Figure 7As shown, the second doped silicon oxide layer 242 can be formed on the surface of the intrinsic polysilicon layer 230, and a second doped silicon oxide layer 242 is also prepared at the sidewall of the groove 211. During the doping source advancement of the second doped silicon oxide layer 242, as... Figure 8 As shown, the thickness of the dopant source is consistent at different positions of the intrinsic polysilicon layer 230. The thickness of the intrinsic polysilicon layer 230 on the sidewall of the groove 211 is greater than the thickness of the intrinsic polysilicon layer 230 outside the groove 211. When the second doped polysilicon layer 232 outside the groove 211 is formed, the dopant source of the second doped silicon oxide layer 242 will not advance to the bottom of the groove 211. The undoped intrinsic polysilicon layer 230 located on the sidewall of the groove 211 forms an isolation layer 233, which separates the first doped polysilicon layer 231 and the second doped polysilicon layer 232.

[0103] In some embodiments, the thickness of the isolation layer 233 along the width direction of the groove 211 is 50μm-80μm.

[0104] In this embodiment, the thickness of the isolation layer 233 is 50μm-80μm, which can ensure the spacing effect between the first doped polycrystalline silicon layer 231 and the second doped polycrystalline silicon layer 232, and avoid the mutual influence between the p-region and n-region of the back contact solar cell.

[0105] The thickness of the isolation layer 233 can be adjusted according to the width of the groove 211, the propagation method of the dopant source, etc.

[0106] In some embodiments, the depth of the groove 211 is 400nm-600nm.

[0107] In this embodiment, the groove 211 has a certain depth, which can form a height difference between the inside and outside of the groove 211, making it easier to remove the first doped silicon oxide layer 241 located outside the groove 211 and retain the first doped silicon oxide layer 241 located inside the groove 211.

[0108] The depth of the groove 211 can be the distance from the opening of the groove 211 to the bottom of the groove 211.

[0109] With a depth of 400nm-600nm, when removing the first doped silicon oxide layer 241 outside the groove 211, a first doped silicon oxide layer 241 of sufficient thickness can be retained in the groove 211, so that the first doped silicon oxide layer 241 in the groove 211 can complete the doping of the intrinsic polysilicon layer 230 at the corresponding position, and form the first doped polysilicon layer 231 in the groove 211.

[0110] In some embodiments, the width of the groove 211 is 700μm-800μm.

[0111] The width of the groove 211 can be the distance from one side of the groove 211 to the other side.

[0112] It is understandable that the width of the groove 211 can be adjusted according to the width settings of the p-region and n-region of the back-contact solar cell.

[0113] In this embodiment, the width of the groove 211 is 700μm-800μm. When multiple grooves 211 are formed on the back surface of the silicon substrate 210, the distance between the grooves 211 can also be 700μm-800μm, so that the p-region and n-region of the back contact solar cell are evenly distributed.

[0114] In actual implementation, the width of the groove 211 is 700μm-800μm, the thickness of the isolation layer 233 along the width direction of the groove 211 is 50μm-80μm, and the thickness of the isolation layer 233 retained on the sidewall of the groove 211 is 10%-15% of the width of the groove 211. The isolation layer 233 has a good spacing effect, the effective area of ​​the p-region and n-region of the back contact solar cell is large, and the carrier collection effect is good.

[0115] In some embodiments, the doping source of the first doped silicon oxide layer 241 is boron, and the doping source of the second doped silicon oxide layer 242 is phosphorus.

[0116] The first doped silicon oxide layer 241 can be BSG with boron as the doping source, and the second doped silicon oxide layer 242 can be PSG with phosphorus as the doping source.

[0117] In this embodiment, the boron doping source of the first doped silicon oxide layer 241 is first pushed into the intrinsic polycrystalline silicon layer 230 inside the groove 211 to form the first doped polycrystalline silicon layer 231. Then, the phosphorus doping source of the second doped silicon oxide layer 242 is pushed into the intrinsic polycrystalline silicon layer 230 outside the groove 211 to form the second doped polycrystalline silicon layer 232. The first doped polycrystalline silicon layer 231 inside the groove 211 can serve as the p-region of the back contact solar cell, and the second doped polycrystalline silicon layer 232 outside the groove 211 can serve as the n-region of the back contact solar cell.

[0118] It should be noted that the temperature for boron doping is higher than that for phosphorus doping. Performing boron doping source advancement first, followed by phosphorus doping source advancement, can avoid the situation where phosphorus doping is followed by boron doping, which would increase the phosphorus doping depth and prevent the doping source advancement from affecting the battery performance.

[0119] In some embodiments, step 150, advancing the dopant source of the first doped silicon oxide layer 241 located in the groove 211 to the intrinsic polysilicon layer 230, includes:

[0120] Laser propulsion is performed on the first doped silicon oxide layer 241 located in the groove 211 to advance the doping source of the first doped silicon oxide layer 241 into the intrinsic polysilicon layer 230 along the direction toward the intrinsic polysilicon layer 230.

[0121] In this embodiment, the dopant source of the first doped silicon oxide layer 241 is advanced by laser. The laser can achieve directional doping. The dopant source of the first doped silicon oxide layer 241 is advanced to the intrinsic polysilicon layer 230 in the direction toward the intrinsic polysilicon layer 230, so as to avoid the dopant source of the first doped silicon oxide layer 241 from entering the isolation layer 233 on the sidewall of the groove 211 or the area outside the groove 211.

[0122] For example, the first doped silicon oxide layer 241 can be BSG, and the doping source is boron. The boron source is directed by laser to form the first doped polycrystalline silicon layer 231 in the groove 211, forming the p-region of the back contact solar cell.

[0123] In some embodiments, step 170, advancing the dopant source of the second doped silicon oxide layer 242 located outside the groove 211 to the intrinsic polysilicon layer 230, may include:

[0124] The second doped silicon oxide layer 242 located outside the groove 211 is advanced at high temperature to diffuse the doping source of the second doped silicon oxide layer 242 to the intrinsic polysilicon layer 230.

[0125] In this embodiment, the dopant source of the second doped silicon oxide layer 242 is advanced by high temperature. The thickness of the intrinsic polysilicon layer 230 on the sidewall of the groove 211 is greater than the thickness of the intrinsic polysilicon layer 230 outside the groove 211. The high temperature advancement can allow the dopant source to enter the intrinsic polysilicon layer 230 outside the groove 211, and diffuse to the intrinsic polysilicon layer 230 on the sidewall of the groove 211 with very little or no diffusion. It will not extend into the end of the intrinsic polysilicon layer 230 near the bottom of the groove 211. That is, the second doped polysilicon layer 232 and the first doped polysilicon layer 231 are separated by the isolation layer 233.

[0126] For example, the second doped silicon oxide layer 242 can be PSG, with phosphorus as the dopant source. By advancing the phosphorus source at high temperature, a second doped polycrystalline silicon layer 232 is formed outside the groove 211, forming the n-region of the back contact solar cell. An isolation layer 233 exists at the boundary between the n-region and the p-region.

[0127] In some embodiments, step 130, preparing a first doped silicon oxide layer 241 on the intrinsic polysilicon layer 230, includes:

[0128] Preparation of the first doped silicon oxide solution;

[0129] A first doped silicon oxide solution is coated onto the side of the intrinsic polycrystalline silicon layer 230 that is away from the tunneling oxide layer 220 and then cured to form a first doped silicon oxide layer 241.

[0130] In this embodiment, the first doped silicon oxide solution can be uniformly coated on the side of the intrinsic polysilicon layer 230 away from the tunneling oxide layer 220, and the first doped silicon oxide layer 241 and the intrinsic polysilicon layer 230 are densely bonded, which is beneficial for subsequently pushing the doping source of the first doped silicon oxide layer 241 into the intrinsic polysilicon layer 230.

[0131] like Figure 4 As shown, the prepared first doped silicon oxide solution is uniformly coated on the surface of the intrinsic polycrystalline silicon layer 230, and the first doped silicon oxide solution fills the groove 211 and is cured to form the first doped silicon oxide layer 241.

[0132] Taking boron as an example, the doping source of the first doped silicon oxide layer 241 is boron.

[0133] In this embodiment, a sol-gel method can be used to mix a boron source (such as boric acid, borate ester, etc.) and a silica sol to prepare a first doped silica solution. The first doped silica solution is then uniformly coated on the surface of the intrinsic polycrystalline silicon layer 230 by immersion or spraying, and then cured in an oven to form BSG.

[0134] In some embodiments, step 140, removing the first doped silicon oxide layer 241 located outside the groove 211, includes:

[0135] The first doped silicon oxide layer 241 outside the groove 211 is subjected to chain cleaning.

[0136] Chain cleaning refers to etching and thinning the first doped silicon oxide layer 241 layer by layer from the outer surface of the first doped silicon oxide layer 241 away from the intrinsic polysilicon layer 230 inward.

[0137] It is understandable that the thickness of the first doped silicon oxide layer 241 inside the groove 211 is greater than the thickness outside the groove 211. By etching and thinning layer by layer from the outer surface inward and controlling the etching time of the chain cleaning, the first doped silicon oxide layer 241 outside the groove 211 can be removed, while the first doped silicon oxide layer 241 inside the groove 211 is retained.

[0138] In practice, after the first doped polysilicon and the second doped polysilicon are prepared, the outermost first doped silicon oxide layer 241 and the second doped silicon oxide layer 242 can also be removed by chain cleaning, which facilitates the subsequent preparation of the antireflection layer 260 and the electrode.

[0139] The method for fabricating a back-contact solar cell according to the embodiments of this application has a short fabrication process, low cost, and high production efficiency, which helps to realize the mass production of TBC cells.

[0140] The following is a specific example.

[0141] The texturing process involves immersing the original n-type silicon substrate 210 in a KOH or NaOH solution with a mass fraction of 1%-3% at a temperature of 60℃-80℃ for texturing, with the texturing time controlled at 15min-25min.

[0142] like Figure 2 As shown, a groove 211 is formed by laser grooving in the p-region of the backlight surface of the silicon substrate 210. The groove 211 is 400nm-600nm in size and 700μm-800μm in depth.

[0143] like Figure 3 As shown, a tunneling oxide layer 220 and an intrinsic polycrystalline silicon layer 230 are formed on the back surface of a silicon substrate 210 by low-pressure chemical vapor deposition (LPCVD).

[0144] like Figure 4 As shown, the first doped silicon oxide layer 241 is prepared by solution method. The first doped silicon oxide layer 241 is BSG. A boron source (such as boric acid, borate ester, etc.) and silicon dioxide sol are mixed and uniformly coated on the surface of the intrinsic polycrystalline silicon layer 230 by impregnation or spraying. Then, it is cured in an oven to form BSG.

[0145] like Figure 5 As shown, a chain cleaning method is used to remove the first doped silicon oxide layer 241 outside the groove 211, while retaining the first doped silicon oxide layer 241 inside the groove 211.

[0146] like Figure 6 As shown, a boron source is directed to the first doped silicon oxide layer 241 by laser to form a first doped polysilicon layer 231 in the groove 211. The laser directed propulsion can prevent the boron source from entering the side wall of the groove 211 or the intrinsic polysilicon layer 230 outside the groove 211.

[0147] like Figure 7 As shown, a second doped silicon oxide layer 242 is formed outside the groove 211 (i.e., the position corresponding to the preset n region) by phosphorus diffusion process. The second doped silicon oxide layer 242 is PSG. A first doped silicon oxide layer 241 exists in the p region. The second doped silicon oxide layer 242 is formed on the surface of the intrinsic polysilicon layer 230.

[0148] like Figure 8 As shown, by advancing the phosphorus source at high temperature, the second intrinsic polysilicon layer 230 outside the groove 211 is transformed into a second doped polysilicon layer 232.

[0149] like Figure 9As shown, a chain cleaning process removes the first doped silicon oxide layer 241 and the second doped silicon oxide layer 242 from the backlight surface, as follows: Figure 10 As shown, an antireflection layer 260 is then deposited on the backlight surface. The thickness of the antireflection layer 260 can be 40nm-80nm. The material of the antireflection layer 260 can be SiNx. The antireflection layer 260 can increase the passivation characteristics and light absorption characteristics of the surface.

[0150] In this embodiment, a groove 211 is formed on one side of the silicon substrate 210, a tunneling oxide layer 220 and an intrinsic polysilicon layer 230 are deposited, BSG is deposited on the surface of the intrinsic polysilicon layer 230 by solution method, and then the BSG outside the groove 211 is removed by wet method, while the BSG inside the groove 211 is retained. A boron source is laser-driven to form a p-poly (boron-doped polysilicon) inside the groove 211, and a PSG is formed on the back side. Due to the blockage of the BSG in the p region of the groove 211, phosphorus cannot diffuse into the p region and forms an n-poly (phosphorus-doped polysilicon) outside the groove 211. The boundary between the n region and the p region is separated by an isolation layer 233. The fabrication process only requires one laser grooving, which reduces the risk of laser damage, eliminates the need for multiple masks, shortens the process, reduces the fabrication cost, and facilitates mass production.

[0151] This application also provides a back-contact solar cell.

[0152] The back-contact solar cell of this application embodiment can be prepared by the above-described method for preparing a back-contact solar cell.

[0153] like Figure 9 As shown, the back-contact solar cell includes a silicon substrate 210, a tunneling oxide layer 220, and a first doped polycrystalline silicon layer 231 and a second doped polycrystalline silicon layer 232 with opposite doping types.

[0154] The tunneling oxide layer 220 is disposed on one side of the silicon substrate 210, and the first doped polysilicon layer 231 and the second doped polysilicon layer 232 are disposed on the side of the tunneling oxide layer 220 facing away from the silicon substrate 210.

[0155] In actual implementation, the tunneling oxide layer 220 and the doped polysilicon layer are stacked sequentially on the back side of the silicon substrate 210. The tunneling oxide layer 220 and the doped polysilicon layer can form a passivation contact structure, which can effectively reduce carrier recombination.

[0156] In this embodiment, a groove 211 is provided on one side of the silicon substrate 210, a first doped polycrystalline silicon layer 231 is located inside the groove 211, and a second doped polycrystalline silicon layer 232 is located outside the groove 211. The regions inside and outside the groove 211 correspond to the n-region and p-region of the back contact solar cell for collecting different charge carriers.

[0157] Wherein, when the area inside the groove 211 corresponds to the p region of the back-contact solar cell, the area outside the groove 211 corresponds to the n region of the back-contact solar cell.

[0158] Multiple grooves 211 can be formed on one side of the silicon substrate 210, with a certain distance between the grooves 211, forming n-regions and p-regions arranged at intervals on the back contact solar cell.

[0159] It is understandable that the groove 211 has a certain depth, which can create a height difference between the inside and outside of the groove 211, allowing the first doped polycrystalline silicon layer 231 and the second doped polycrystalline silicon layer 232 to be aligned in the thickness direction of the back contact solar cell. Figure 9 The p-regions and n-regions of the solar cell are spaced apart (as shown in the top-to-bottom direction) to avoid mutual interference between them.

[0160] like Figure 9 As shown, within the groove 211, from top to bottom, are a silicon substrate 210, a tunneling oxide layer 220, and a first doped polysilicon layer 231. Outside the groove 211, from top to bottom, are a silicon substrate 210, a tunneling oxide layer 220, and a second doped polysilicon layer 232. The tunneling oxide layer 220 is continuous, and the groove 211 is formed before the tunneling oxide layer 220 is formed.

[0161] In most related technologies, after laser transfer of phosphorus paste and boron paste onto the substrate, the n-region and p-region are isolated by laser grooving. However, the laser operation can damage the doped polysilicon in the n-region and p-region.

[0162] In this embodiment, the first doped polysilicon layer 231 and the second doped polysilicon layer 232 are separated by the height difference between the inside and outside of the groove 211. There is no need to use laser to separate the first doped polysilicon layer 231 and the second doped polysilicon layer 232, thus avoiding laser damage to the doped polysilicon layer of the back contact solar cell and helping to improve the photoelectric conversion efficiency of the back contact solar cell.

[0163] In practice, an intrinsic polycrystalline silicon layer 230 can be prepared on the side of the tunnel oxide layer 220 that is away from the silicon substrate 210, and then a first doped polycrystalline silicon layer 231 and a second doped polycrystalline silicon layer 232 can be prepared by doping.

[0164] The first doped polysilicon layer 231 can be fabricated by forming a first doped silicon oxide layer 241 in the groove 211 and pushing the doping source of the first doped silicon oxide layer 241 to the intrinsic polysilicon layer 230.

[0165] The second doped polysilicon layer 232 can be formed by forming a second doped silicon oxide layer 242 in the groove 211. The first doped silicon oxide layer 241 retained in the groove 211 acts as a mask, pushing the doping source of the second doped silicon oxide layer 242 outside the groove 211 to the intrinsic polysilicon layer 230, thus obtaining the second doped polysilicon layer 232.

[0166] According to the back-contact solar cell provided in the embodiments of this application, a groove 211 is formed in the silicon substrate 210, a first doped silicon oxide layer 241 is formed in the groove 211, and a second doped silicon oxide layer 242 is formed outside the groove 211. The two doped polycrystalline silicon layers are separated by the height difference between the inside and outside of the groove 211. After the doped polycrystalline silicon layer is prepared, there is no need to use laser to separate the n-region and p-region, which can reduce laser damage to the back-contact solar cell and effectively improve the photoelectric conversion efficiency of the back-contact solar cell.

[0167] In some embodiments, the intrinsic polysilicon layer 230 on the sidewall of the groove 211 forms an isolation layer 233, which separates the first doped polysilicon layer 231 and the second doped polysilicon layer 232.

[0168] like Figure 9 As shown, the intrinsic polycrystalline silicon layer 230 on the sidewall of the groove 211 forms an isolation layer 233. The isolation layer 233 separates the two doped polycrystalline silicon layers with opposite doping types in a first direction from left to right and a second direction from top to bottom, so as to avoid the p-region and n-region of the back-contact solar cell from affecting each other.

[0169] In this embodiment, the intrinsic polysilicon layer 230 on the sidewall of the groove 211 can be the same layer structure as the intrinsic polysilicon layer 230 used to prepare the doped polysilicon layer. When preparing the tunneling oxide layer 220 and the intrinsic polysilicon layer 230, the tunneling oxide layer 220 and the intrinsic polysilicon layer 230 are formed inside the groove 211, outside the groove 211, and on the sidewall of the groove 211.

[0170] In some embodiments, the thickness of the isolation layer 233 along the width direction of the groove 211 is 50μm-80μm.

[0171] In this embodiment, the thickness of the isolation layer 233 is 50μm-80μm, which can ensure the spacing effect between the first doped polycrystalline silicon layer 231 and the second doped polycrystalline silicon layer 232, and avoid the mutual influence between the p-region and n-region of the back contact solar cell.

[0172] The thickness of the isolation layer 233 can be adjusted according to the width of the groove 211, the propagation method of the dopant source, etc.

[0173] In some embodiments, the depth of the groove 211 is 400nm-600nm.

[0174] The depth of the groove 211 can be the distance from the opening of the groove 211 to the bottom of the groove 211.

[0175] A depth of 400nm-600nm can ensure the spacing between the first doped polycrystalline silicon layer 231 and the second doped polycrystalline silicon layer 232 in the thickness direction of the back contact solar cell, thus avoiding mutual interference between the p-region and n-region of the back contact solar cell.

[0176] In some embodiments, the width of the groove 211 is 700μm-800μm.

[0177] The width of the groove 211 can be the distance from one side of the groove 211 to the other side.

[0178] It is understandable that the width of the groove 211 can be adjusted according to the width settings of the p-region and n-region of the back-contact solar cell.

[0179] In this embodiment, the width of the groove 211 is 700μm-800μm. When multiple grooves 211 are formed on the back surface of the silicon substrate 210, the distance between the grooves 211 can also be 700μm-800μm, so that the p-region and n-region of the back contact solar cell are evenly distributed.

[0180] In actual implementation, the width of the groove 211 is 700μm-800μm, the thickness of the isolation layer 233 along the width direction of the groove 211 is 50μm-80μm, and the thickness of the isolation layer 233 retained on the sidewall of the groove 211 is 10%-15% of the width of the groove 211. The isolation layer 233 has a good spacing effect, the effective area of ​​the p-region and n-region of the back contact solar cell is large, and the carrier collection effect is good.

[0181] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0182] In the description of this application, it should be understood that the terms "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0183] In the description of this application, "first feature" and "second feature" may include one or more of the features.

[0184] In the description of this application, "multiple" means two or more.

[0185] In the description of this application, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or the first and second features being in contact through another feature between them.

[0186] In the description of this application, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicate that the first feature is at a higher horizontal level than the second feature.

[0187] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0188] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for fabricating a back-contact solar cell, characterized in that, include: A groove is formed on one side of the silicon substrate; A tunneling oxide layer and an intrinsic polycrystalline silicon layer are sequentially formed on one side of the silicon substrate; A first doped silicon oxide layer is formed on the intrinsic polycrystalline silicon layer, wherein the thickness of the first doped silicon oxide layer outside the groove is less than the thickness inside the groove; Remove the first doped silicon oxide layer located outside the groove to expose the intrinsic polysilicon layer; The doping source of the first doped silicon oxide layer located in the groove is pushed to the intrinsic polysilicon layer to form the first doped polysilicon layer; A second doped silicon oxide layer with the opposite doping type to the first doped silicon oxide layer is prepared on the intrinsic polycrystalline silicon layer located outside the groove; The doping source of the second doped silicon oxide layer located outside the groove is pushed into the intrinsic polysilicon layer to form the second doped polysilicon layer; The intrinsic polysilicon layer on the sidewall of the groove forms an isolation layer, which separates the first doped polysilicon layer and the second doped polysilicon layer; the thickness of the isolation layer is 10%-15% of the width of the groove.

2. The method for preparing a back-contact solar cell according to claim 1, characterized in that, The thickness of the isolation layer along the width direction of the groove is 50μm-80μm.

3. The method for preparing a back-contact solar cell according to claim 1, characterized in that, The depth of the groove is 400nm-600nm.

4. The method for fabricating a back-contact solar cell according to claim 1, characterized in that, The width of the groove is 700μm-800μm.

5. The method for preparing a back-contact solar cell according to claim 1, characterized in that, The doping source for the first doped silicon oxide layer is boron, and the doping source for the second doped silicon oxide layer is phosphorus.

6. The method for fabricating a back-contact solar cell according to claim 1, characterized in that, The step of advancing the dopant source of the first doped silicon oxide layer located in the groove to the intrinsic polysilicon layer includes: Laser propulsion is performed on the first doped silicon oxide layer located in the groove to advance the dopant source of the first doped silicon oxide layer into the intrinsic polycrystalline silicon layer along the direction toward the intrinsic polycrystalline silicon layer.

7. The method for preparing a back-contact solar cell according to claim 1, characterized in that, The step of advancing the dopant source of the second doped silicon oxide layer located outside the groove to the intrinsic polysilicon layer includes: The second doped silicon oxide layer located outside the groove is advanced at high temperature to diffuse the dopant source of the second doped silicon oxide layer into the intrinsic polycrystalline silicon layer.

8. The method for preparing a back-contact solar cell according to any one of claims 1-7, characterized in that, The fabrication of the first doped silicon oxide layer on the intrinsic polycrystalline silicon layer includes: Preparation of the first doped silicon oxide solution; The first doped silicon oxide solution is coated onto the side of the intrinsic polycrystalline silicon layer opposite to the tunneling oxide layer and cured to form the first doped silicon oxide layer.

9. The method for preparing a back-contact solar cell according to any one of claims 1-7, characterized in that, The removal of the first doped silicon oxide layer located outside the groove includes: The first doped silicon oxide layer outside the groove is subjected to chain cleaning.

10. A back-contact solar cell, characterized in that, include: A silicon substrate, wherein one side of the silicon substrate has a groove; A tunneling oxide layer is disposed on one side of the silicon substrate; A first doped polysilicon layer and a second doped polysilicon layer with opposite doping types are disposed on the side of the tunneling oxide layer facing away from the silicon substrate. The first doped polysilicon layer is located inside the groove, and the second doped polysilicon layer is located outside the groove. The back-contact solar cell is prepared by the method of any one of claims 1-9 for preparing a back-contact solar cell; The intrinsic polysilicon layer on the sidewall of the groove forms an isolation layer, which separates the first doped polysilicon layer and the second doped polysilicon layer; the thickness of the isolation layer is 10%-15% of the width of the groove.

11. The back-contact solar cell according to claim 10, characterized in that, The thickness of the isolation layer along the width direction of the groove is 50μm-80μm.

12. The back-contact solar cell according to claim 10 or 11, characterized in that, The depth of the groove is 400nm-600nm.

13. The back-contact solar cell according to claim 10 or 11, characterized in that, The width of the groove is 700μm-800μm.

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