Back contact battery piece and preparation method thereof, back contact laminated battery and photovoltaic module
By designing a main grid with varying width and length and doped regions, the fabrication cost of back-contact solar cells was reduced, the collection area of the fine grid was increased, the photoelectric conversion efficiency was improved, and the problem of high fabrication cost of the main grid was solved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG JINKO SOLAR CO LTD
- Filing Date
- 2025-09-23
- Publication Date
- 2026-05-01
AI Technical Summary
The fabrication cost of the back contact cell main grid in the existing technology is relatively high, mainly due to the large amount of paste consumed during screen printing.
Design a back-contact solar cell with multiple pads spaced apart on the main grid. The width of the doped region and the main grid varies along the extension direction, and the length of the fine grid increases. Doped regions and grid lines with different widths and lengths are formed by laser grooving, and screen printing is used to reduce paste consumption.
This reduces the fabrication cost of the main gate, increases the collection area of the fine gate, improves photoelectric conversion efficiency, and reduces carrier loss.
Smart Images
Figure CN121968798A_ABST
Abstract
Description
A back-contact solar cell and its preparation method, a back-contact tandem solar cell and a photovoltaic module
[0001] This application is a divisional application of the patent application filed on September 23, 2025, with application number 2025113706641 and invention title "A back contact solar cell and its preparation method, a back contact tandem solar cell and a photovoltaic module". Technical Field
[0002] This application relates to the field of photovoltaic module technology, specifically to a back-contact solar cell and its preparation method, a back-contact tandem solar cell, and a photovoltaic module. Background Technology
[0003] Photovoltaic modules convert solar energy into electrical energy, offering advantages such as being pollution-free, geographically unrestricted, and inexhaustible, making them a major direction for the development of new energy sources. Photovoltaic modules mainly consist of photovoltaic cells, photovoltaic glass, a backsheet, and encapsulating film. Back-contact cells, a type of photovoltaic cell, place both the positive and negative electrodes on the back side of the cell, reducing light shading by the grid lines, increasing the light-receiving area, and improving performance. The electrode structure generally includes a main grid, fine grids, and pads on the main grid. The fine grids collect charge carriers, and the main grid collects these carriers. The main grid is typically fabricated using screen printing, which consumes a large amount of paste, resulting in higher production costs. Summary of the Invention
[0004] In view of this, the present application provides a back-contact solar cell and its preparation method, a back-contact tandem solar cell and a photovoltaic module, so as to solve the technical problem of high preparation cost of back-contact solar cell main busbar in the prior art.
[0005] In a first aspect, embodiments of this application provide a back-contact solar cell, the back-contact solar cell comprising a silicon substrate, a main gate disposed on the back side of the silicon substrate, and a plurality of pads spaced apart on the main gate; the back side of the silicon substrate further comprises a doped region, the main gate being located within the projection range of the doped region; the silicon substrate further comprises a fine gate, one end of the fine gate being connected to the main gate; wherein, along the extending direction of the main gate, the width of the area corresponding to the doped region and the main gate near the pad is greater than the width of the area corresponding to the doped region and the main gate away from the pad, and the length of the fine gate away from the pad is greater than the length of the fine gate near the pad.
[0006] In this embodiment, the width of the doped region varies, which provides more space for the arrangement of the fine gate, thereby allowing the fine gate to vary in length to increase the overall length of the fine gate, thereby increasing the carrier collection area and improving the photoelectric conversion efficiency of the back contact cell.
[0007] In one specific embodiment, the main gate includes a first segment and a second segment, the second segment being located between two adjacent pads, and the first segment being the area other than the second segment; along the direction away from the pads, the width of the first segment near the pads is greater than the width away from the pads, and / or, along the extension direction of the main gate, the width of the second segment near the pads is greater than the width at the center of the second segment.
[0008] In one specific embodiment, the width of the end of the first segment away from the pad and the width W1 of the center of the second segment satisfy 10um≤W1<200um, and / or, the width W2 of the first segment and the end of the second segment near the pad satisfies 200um≤W2≤800um.
[0009] In one specific embodiment, along the direction away from the pad, the width of the doped region corresponding to the first segment near the pad is greater than the width of the doped region corresponding to the first segment away from the pad, and / or, along the extension direction of the main gate, the width of the doped region corresponding to the second segment near the pad is greater than the width of the doped region corresponding to the center position of the second segment.
[0010] In one specific embodiment, within the range corresponding to the main gate, the minimum width W3 of the doped region satisfies 100um≤W3≤300um, and the maximum width W4 of the doped region satisfies 300um<W4≤850um.
[0011] In one specific embodiment, along the extension direction of the main gate, the length of the fine gate farther from the pad is L1, and the length of the fine gate closer to the pad is L2, where L1 ≤ L2 + 400 μm.
[0012] In one specific embodiment, the end of the doped region corresponding to the main gate has an angle along the extension direction of the main gate; the end of the doped region corresponding to the pad is parallel to the extension direction of the main gate.
[0013] In one specific embodiment, the doped region includes a first doped region and a second doped region, the main gate includes a first main gate and a second main gate, and the fine gate includes a first fine gate and a second fine gate. The first main gate and the first fine gate are located within the projection range of the first doped region, and the second main gate and the second fine gate are located within the projection range of the second doped region. The first doped region and the second doped region are distributed in a finger-like pattern. Along the extension direction of the main gate, the width of the region corresponding to the first doped region and the first main gate is proportional to the width of the first main gate. The width of the region corresponding to the second doped region and the second main gate is proportional to the width of the second main gate.
[0014] Secondly, embodiments of this application provide a method for fabricating a back-contact solar cell, the method comprising: fabricating a silicon substrate; forming a tunneling oxide layer and a doped polycrystalline silicon layer on the back side of the silicon substrate; depositing a passivation layer and an anti-reflection layer on the front side of the silicon substrate; depositing a transparent conductive oxide layer on the back side of the silicon substrate; and fabricating gate lines on the back side of the silicon substrate; wherein the doped polycrystalline silicon layer includes a doped region, and the gate lines include a main gate and a fine gate; along the extension direction of the main gate, the doped region has a width variation, and the fine gate has a length variation.
[0015] In one specific embodiment, the method for fabricating the back contact solar cell in the step of forming a tunneling oxide layer and a doped polycrystalline silicon layer on the back side of the silicon substrate specifically includes: depositing a tunneling oxide layer and an intrinsic polycrystalline silicon layer on the back side of the silicon substrate; depositing a mask layer on the intrinsic polycrystalline silicon layer; performing laser grooving on the mask layer to form a first groove with varying width; doping the intrinsic polycrystalline silicon layer in the region corresponding to the first groove to form a first doped region; performing laser grooving on the mask layer to form a second groove with varying width; and doping the intrinsic polycrystalline silicon layer in the region corresponding to the second groove to form a second doped region.
[0016] In one specific embodiment, in the step of fabricating grid lines on the back side of the silicon substrate, the method for fabricating the back contact cell further includes: screen printing grid lines on the back side of the silicon substrate using a screen printing plate; wherein the screen printing plate includes a first mesh and a second mesh, the first mesh being used to print the main grid and the second mesh being used to print the fine grid; along the extension direction of the main grid, the first mesh has a width variation and the second mesh has a length variation.
[0017] Thirdly, embodiments of this application provide a back-contact solar tandem cell, which includes a back-contact bottom cell and a perovskite top cell. The perovskite top cell is electrically connected to the front side of the back-contact bottom cell, and the back-contact bottom cell is the back-contact cell.
[0018] Fourthly, embodiments of this application provide a photovoltaic module, the photovoltaic module including the back contact solar cell. Attached Figure Description
[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the 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.
[0020] Figure 1 is a schematic diagram of the back contact solar cell provided in this application in a specific embodiment; Figure 2 is a partial enlarged view of part I in Figure 1; Figure 3 is a schematic diagram of the structure of the doped region in Figure 1; Figure 4 is a schematic diagram of the back contact stacked solar cell provided in this application in a specific embodiment.
[0021] Reference numerals: 1-Back contact tandem solar cell; 11-Back contact cell; 111-Silicon substrate; 112-Main grid; 112a-First section; 112b-Second section; 112c-Center position; 112d-First main grid; 112e-Second main grid; 113-Pad; 114-Fine grid; 114a-First fine grid; 114b-Second fine grid; 115-Doped region; 115a-First doped region; 115b-Second doped region; 12-Perovskite top cell. Detailed Implementation
[0022] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.
[0023] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.
[0024] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.
[0025] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.
[0026] Photovoltaic modules convert solar energy into electrical energy, offering advantages such as being pollution-free, not geographically limited, and inexhaustible, making them a major direction for the development of new energy sources. Photovoltaic modules mainly consist of photovoltaic cells, photovoltaic glass, a backsheet, and encapsulating film. Back-contact cells, a type of photovoltaic cell, place both the positive and negative electrodes on the back side of the cell, reducing light shading by the grid lines, increasing the light-receiving area, and improving performance. The electrode structure generally includes a main grid, fine grids, and pads on the main grid. The fine grids collect charge carriers, and the main grid collects these carriers. The main grid is typically fabricated using screen printing, which consumes a large amount of paste, resulting in higher production costs.
[0027] To address the aforementioned technical problems, as shown in Figures 1 to 3, this application provides a back-contact solar cell 11. The back-contact solar cell 11 may include a silicon substrate 111, with a main gate 112 disposed on the back side of the silicon substrate 111. Multiple pads 113 are spaced apart on the main gate 112. The back side of the silicon substrate 111 also includes a doped region 115, and the main gate 112 is located within the projection range of the doped region 115. Specifically, along the extending direction of the main gate 112, at least a portion of the main gate 112 structure has a width greater than the width at the end furthest from the pads 113, and / or, the width of the doped region 115 corresponding to the area of the main gate 112 near the pads 113 is greater than the width of the area of the doped region 115 corresponding to the area of the main gate 112 furthest from the pads 113.
[0028] In this embodiment, along the extending direction of the main gate 112, at least a portion of the main gate 112 structure is wider at the end near the pad 113 than at the end away from the pad 113. Even with a larger width at the end of the main gate 112 near the pad 113, the connection area between the main gate 112 and the pad 113 is increased, thereby increasing the cross-sectional area of the carrier transport path and reducing contact resistance. This reduces carrier losses between the main gate 112 and the pad 113. Furthermore, a smaller width at the end of the main gate 112 away from the pad 113 reduces the area occupied by the main gate 112 in that region, providing more space for the subsequent arrangement of the fine gate 114. This increases the length of the fine gate 114, thereby increasing the carrier collection area and improving the photoelectric conversion efficiency of the back contact cell 11. In addition, by making the main gate 112 have a width variation along the extension direction of the main gate 112, the overall area of the main gate 112 can be reduced, thereby reducing the total amount of slurry required in the preparation process of the main gate 112 and reducing the overall preparation cost of the main gate 112.
[0029] At the same time, the width of the area corresponding to the doped region 115 and the main gate 112 near the pad 113 is greater than the width of the area corresponding to the doped region 115 and the main gate 112 away from the pad 113. Even if the width of the area corresponding to the doped region 115 changes with the width of the main gate 112, it can be ensured that the main gate 112 is arranged within the projection range of the doped region 115.
[0030] In one specific embodiment, as shown in Figures 1 and 2, the main gate 112 may include a first segment 112a and a second segment 112b, the second segment 112b being located between two adjacent pads 113, and the first segment 112a being the area excluding the second segment 112b. Along the direction away from the pads 113, the width of the first segment 112a at the end near the pads 113 is greater than the width at the end away from the pads 113, and / or, along the extension direction of the main gate 112, the width of the second segment 112b at the end near the pads 113 is greater than the width at the center position 112c of the second segment 112b.
[0031] In this embodiment, multiple pads 113 are spaced apart on the main gate 112. Therefore, the main gate 112 is divided into a first segment 112a and a second segment 112b by the pads 113. The second segment 112b is located between two adjacent pads 113, and the first segment 112a is the area outside the second segment 112b. Along the direction away from the pads 113, the width of the end of the first segment 112a near the pads 113 is greater than the width of the end away from the pads 113. And along the extension direction of the main gate 112, the width of the end of the second segment 112b near the pads 113 is greater than the width of the center position 112c of the second segment 112b. This ensures the connection area between the first segment 112a and the second segment 112b and the pads 113, while also reducing the overall paste consumption during the fabrication of the main gate 112. In addition, it provides more space for the arrangement of the fine grid 114, thereby increasing the carrier collection area and improving the photoelectric conversion efficiency of the back contact cell 11.
[0032] In another specific embodiment, as shown in Figures 1 and 2, the width of the first segment 112a can be gradually reduced along the direction away from the pad 113, and the width of the second segment 112b in the region from one end near the pad 113 to the center position 112c of the second segment 112b can also be gradually reduced along the extension direction of the main gate 112, thereby further reducing the overall area of the main gate 112 and significantly reducing the manufacturing cost of the main gate 112.
[0033] In one specific embodiment, as shown in Figures 1 and 2, the width W1 of the end of the first segment 112a away from the pad 113 and the width W1 of the center position 112c of the second segment 112b satisfy 10um≤W1<200um, and / or, the width W2 of the end of the first segment 112a and the second segment 112b close to the pad 113 satisfies 200um≤W2≤800um.
[0034] In this embodiment, the end of the first segment 112a away from the pad 113 and the center position 112c of the second segment 112b can be the corresponding position of the minimum width in the overall structure of the main gate 112. The width W1 of the two segments can satisfy 10um≤W1<200um. For example, W1 can be 10um, 50um, 100um, 150um, 180um, etc. This can ensure the normal transport of charge carriers at the end of the first segment 112a away from the pad 113 and the center position 112c of the second segment 112b, avoiding the impact on the normal use of the back contact cell 11. It can also avoid the effect of excessive width on reducing the manufacturing cost of the main gate 112.
[0035] Meanwhile, the ends of the first segment 112a and the second segment 112b closest to the pad 113 can be located at the corresponding positions of the maximum width in the main gate 112 structure. The width W2 of the two segments can satisfy 200um≤W2≤800um. For example, W2 can be 200um, 400um, 600um, 800um, etc. This ensures the contact area between the ends of the first segment 112a and the second segment 112b closest to the pad 113 and the pad 113, avoiding increased carrier loss due to high contact resistance during transmission, which would affect the photoelectric conversion efficiency of the back contact cell 11.
[0036] In other embodiments, W1 and W2 may also be other specific values. In the embodiments of this application, the specific values of W1 and W2 are not limited and can be adjusted adaptively according to the actual situation.
[0037] In one specific embodiment, as shown in Figures 1 and 3, along the direction away from the pad 113, the width of the region corresponding to the doped region 115 and the first segment 112a near the pad 113 is greater than the width of the region corresponding to the doped region 115 and the first segment 112a away from the pad 113, and / or, along the extension direction of the main gate 112, the width of the region corresponding to the doped region 115 and the second segment 112b near the pad 113 is greater than the width of the region corresponding to the center position 112c of the doped region 115 and the second segment 112b.
[0038] In this embodiment, the doped region 115 is adapted to the width variations of the first segment 112a and the second segment 112b, respectively, so that both the first segment 112a and the second segment 112b can be located within the projection range of the doped region 115. Furthermore, the width variation of the doped region 115 provides more space for the arrangement of the fine grid 114, thereby increasing the carrier collection area and improving the photoelectric conversion efficiency of the back contact solar cell 11.
[0039] In a specific embodiment, as shown in Figures 1 and 3, within the corresponding position range of the doped region 115 and the main gate 112, the minimum width W3 of the doped region 115 satisfies 100um≤W3≤300um, and the maximum width W4 of the doped region 115 satisfies 300um<W4≤850um.
[0040] In this embodiment, within the range corresponding to the position of the doped region 115 and the main gate 112, the minimum width of the doped region 115 is the position corresponding to the end of the first segment 112a away from the pad 113 and the center position 112c of the second segment 112b. Therefore, the minimum width W3 of the doped region 115 is made to satisfy 100um≤W3≤300um. For example, W3 can be 100um, 150um, 200um, 250um, 300um, etc., so that the end of the first segment 112a away from the pad 113 and the center position 112c of the second segment 112b can both be located within the projection range of the doped region 115.
[0041] Meanwhile, the maximum width of the doped region 115 is the position corresponding to the end of the first segment 112a and the second segment 112b near the pad 113. Therefore, the maximum width W4 of the doped region 115 is made to satisfy 300um < W4 ≤ 850um. For example, W4 can be 350um, 500um, 650um, 700um, 850um, etc., so that the corresponding positions of the first segment 112a and the second segment 112b near the pad 113 can be located within the projection range of the doped region 115.
[0042] In other embodiments, W3 and W4 may also be other specific values. In this embodiment, the specific values of W3 and W4 are not limited, and can be adjusted adaptively according to specific circumstances.
[0043] In one specific embodiment, as shown in Figures 1 and 2, the silicon substrate 111 is further provided with a fine gate 114, one end of which is connected to the main gate 112. Along the extending direction of the main gate 112, the length of the fine gate 114 away from the pad 113 is greater than the length of the fine gate 114 near the pad 113.
[0044] In this embodiment, along the direction away from the pad 113, the width of the first segment 112a at the end near the pad 113 is greater than the width at the end away from the pad 113. Therefore, the area of the doped region 115 occupied by the end of the first segment 112a away from the pad 113 is smaller, allowing more space for the fine gate 114 away from the pad 113, thus enabling the length of the fine gate 114 away from the pad 113 to be greater than the length of the fine gate 114 near the pad 113. Simultaneously, along the extension direction of the main gate 112, the width of the second segment 112b at the end near the pad 113 is greater than the width of the center position 112c of the second segment 112b. Therefore, the area of the doped region 115 occupied by the center position 112c of the second segment 112b is smaller, allowing more space for the fine gate 114 away from the pad 113, thus enabling the length of the fine gate 114 away from the pad 113 to be greater than the length of the fine gate 114 near the pad 113. Within the corresponding range of the first segment 112a and the second segment 112b, by setting a fine grid 114 with a larger length, the collection area for charge carriers can be increased, thereby improving the photoelectric conversion efficiency of the back contact cell 11.
[0045] In one specific embodiment, as shown in FIG1, along the extension direction of the main gate 112, the length of the fine gate 114 away from the pad 113 is L1, and the length of the fine gate 114 close to the pad 113 is L2, where L1≤L2+400um.
[0046] In this embodiment, along the extension direction of the main gate 112, the length of the fine gate 114 away from the pad 113 is L1, that is, the maximum length of the fine gate 114 is L1, and the length of the fine gate 114 close to the pad 113 is L2, that is, the minimum length of the fine gate 114 is L2. Among them, L1 and L2 can satisfy L1≤L2+400um, that is, the difference between L1 and L2 can be 100um, 200um, 300um, 400um, etc., to increase the overall length of the fine gate 114, increase the carrier collection area, and thus improve the photoelectric conversion efficiency of the back contact cell 11.
[0047] In other embodiments, as shown in FIG1, the length of the fine gate 114 can be gradually increased along the direction away from the pad 113, thereby further increasing the overall length of the fine gate 114 to further increase the carrier collection area.
[0048] In one specific embodiment, as shown in Figures 1 and 3, the end of the doped region 115 corresponding to the main gate 112 has an angle along the extension direction of the main gate 112, and the end of the doped region 115 corresponding to the pad 113 is parallel to the extension direction of the main gate 112.
[0049] In this embodiment, by making the ends of the doped region 115 and the corresponding region of the main gate 112 tilted, the arrangement space of the fine gate 114 can be further increased to increase the carrier collection area, thereby further improving the photoelectric conversion efficiency of the back contact cell 11.
[0050] In one specific embodiment, as shown in Figures 1 to 3, the doped region 115 may include a first doped region 115a and a second doped region 115b, the main gate 112 may include a first main gate 112d and a second main gate 112e, and the fine gate 114 may include a first fine gate 114a and a second fine gate 114b. The first main gate 112d and the first fine gate 114a are located within the projection range of the first doped region 115a, and the second main gate 112e and the second fine gate 114b are located within the projection range of the second doped region 115b. The first doped region 115a and the second doped region 115b are arranged in a finger-like pattern. Along the extending direction of the main gate 112, the width of the corresponding region of the first doped region 115a and the first main gate 112d is proportional to the width of the first main gate 112d, and the width of the second doped region 115b and the second main gate 112e is proportional to the width of the second main gate 112e.
[0051] In this embodiment, the back side of the back contact solar cell 11 has a first doped region 115a and a second doped region 115b with opposite polarities, and the first doped region 115a and the second doped region 115b are distributed in a finger-like pattern, that is, along the extension direction of the main gate 112, the first fine gate 114a and the second fine gate 114b are alternately distributed. Therefore, along the direction away from the pad 113, the width of the first doped region 115a is gradually reduced, thereby increasing the area of a portion of the second doped region 115b corresponding to the second fine gate 114b, thus increasing the usable space of the second fine gate 114b, and consequently increasing the length of the second fine gate 114b. At the same time, the width of the second doped region 115b is gradually reduced, thereby increasing the area of a portion of the first doped region 115a corresponding to the first fine gate 114a, thus increasing the usable space of the first fine gate 114a, and consequently increasing the length of the first fine gate 114a. By increasing the length of the first fine gate 114a and the second fine gate 114b, the photoelectric conversion efficiency of the back contact solar cell 11 can be significantly increased.
[0052] This application embodiment also provides a method for fabricating a back contact solar cell 11, as shown in Figures 1 to 3, for fabricating the back contact solar cell 11 in the above embodiments. The fabrication method may include, but is not limited to, the following steps: S11: fabricating a silicon substrate 111; S12: forming a tunneling oxide layer and a doped polysilicon layer on the back side of the silicon substrate 111; S13: depositing a passivation layer and an antireflection layer on the front side of the silicon substrate 111; S14: depositing a transparent conductive oxide layer on the back side of the silicon substrate 111; S15: fabricating gate lines on the back side of the silicon substrate 111; wherein, the doped polysilicon layer includes a doped region 115, the gate lines include a main gate 112 and a fine gate 114, the main gate 112 has a width variation along the extension direction of the main gate 112, the doped region 115 has a width variation, and the fine gate 114 has a length variation.
[0053] In this embodiment, by providing a main grid 112 with varying width on the back side of the back contact cell 11, the amount of paste required during the fabrication of the main grid 112 can be reduced, thereby lowering the overall production cost of the main grid 112 and providing more space for the arrangement of the fine grid 114. Simultaneously, providing a fine grid 114 with varying length on the back side of the back contact cell 11 increases the overall length of the fine grid 114, thereby increasing the carrier collection area and improving the photoelectric conversion efficiency of the back contact cell 11. Furthermore, by providing a doped region 115 with varying width on the back side of the back contact cell 11, the available space for arranging the fine grid 114 can be further increased, thereby further enhancing the carrier collection area.
[0054] Among them, the width of the main gate 112 away from the pad 113 is smaller than the width of the end close to the pad 113, the length of the fine gate 114 away from the pad 113 is greater than the length of the fine gate 114 close to the pad 113, and the width of the doped region 115 corresponding to the end of the main gate 112 close to the pad 113 is greater than the width of the doped region 115 corresponding to the end of the main gate 112 away from the pad.
[0055] In a specific embodiment, as shown in Figures 1 to 3, step S12 may further include, but is not limited to, the following steps: S121: depositing a tunneling oxide layer and an intrinsic polysilicon layer on the back side of the silicon substrate 111; S122: depositing a mask layer on the intrinsic polysilicon layer; S123: performing laser grooving on the mask layer to form a first groove with varying width; S124: doping the intrinsic polysilicon layer in the region corresponding to the first groove to form a first doped region 115a; S125: performing laser grooving on the mask layer to form a second groove with varying width; S126: doping the intrinsic polysilicon layer in the region corresponding to the second groove to form a second doped region 115b.
[0056] In this embodiment, a first doped region 115a with varying width is generated by forming a first groove with varying width on the mask layer, and a second doped region 115b with varying width is generated by forming a second groove with varying width on the mask layer. The first doped region 115a and the second doped region 115b are arranged in a finger-like pattern, which allows them to have varying widths, further increasing the usable space of the first fine gate 114a and the second fine gate 114b, and improving the photoelectric conversion efficiency of the back contact solar cell 11.
[0057] In one specific embodiment, as shown in Figures 1 to 3, step S15 may further include, but is not limited to, the following step: S151: Printing gate lines on the back side of the silicon substrate 111 using a screen printing plate; wherein, the screen printing plate may include a first mesh and a second mesh, the first mesh being used to print the main gate 112, and the second mesh being used to print the fine gate 114. Along the extending direction of the main gate 112, the first mesh has a varying width, and the second mesh has a varying length.
[0058] In this embodiment, by setting a first mesh and a second mesh on the screen printing plate, and making the first mesh have a width variation and the second mesh have a length variation along the extension direction of the main grid 112, the fabricated main grid 112 and fine grid 114 can have width and length variations respectively, thereby reducing the fabrication cost of the main grid 112, increasing the carrier collection area, and improving the photoelectric conversion efficiency of the back contact cell 11.
[0059] This application embodiment also provides a back-contact solar tandem cell 1, as shown in Figures 1 and 4. The back-contact solar tandem cell 1 may include a back-contact bottom cell and a perovskite top cell 12. The perovskite top cell 12 is electrically connected to the front side of the back-contact bottom cell, and the back-contact bottom cell is the back-contact cell 11 described in the above embodiment.
[0060] In this embodiment, by setting the back contact cell 11 described in the above embodiment as the back contact bottom cell in the back contact solar tandem cell 1, the photoelectric conversion efficiency of the back contact solar tandem cell 1 can be improved and the manufacturing cost can be reduced.
[0061] This application also provides a photovoltaic module (not shown in the figure), which can be composed of the back contact solar cell, photovoltaic glass, encapsulant film, backsheet, and frame described in the above embodiments. By using the back contact solar cell prepared by the method described in the above embodiments, the overall working efficiency of the photovoltaic module can be improved by increasing the photoelectric conversion efficiency of the back contact solar cell.
[0062] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A back contact battery cell, characterized in that, The back contact solar cell includes a silicon substrate, a main gate is disposed on the back side of the silicon substrate, and a plurality of pads are spaced apart on the main gate; the back side of the silicon substrate also includes a doped region, and the main gate is located within the projection range of the doped region; the silicon substrate also has a fine gate, one end of which is connected to the main gate; wherein, along the extension direction of the main gate, the width of the area corresponding to the doped region and the main gate near the pad is greater than the width of the area corresponding to the doped region and the main gate away from the pad, and the length of the fine gate away from the pad is greater than the length of the fine gate near the pad.
2. The back contact battery cell according to claim 1, characterized in that, The main gate includes a first segment and a second segment, the second segment being located between two adjacent pads, and the first segment being the area outside the second segment; along the direction away from the pads, the width of the first segment near the pads is greater than the width away from the pads, and / or, along the extension direction of the main gate, the width of the second segment near the pads is greater than the width at the center of the second segment.
3. The back contact battery cell according to claim 2, characterized in that, The width of the first segment at the end furthest from the pad and the width W1 at the center of the second segment satisfy 10um≤W1<200um, and / or the width W2 of the first segment and the second segment at the end closest to the pad satisfies 200um≤W2≤800um.
4. The back contact battery cell according to claim 2, characterized in that, Along the direction away from the pad, the width of the doped region corresponding to the first segment near the pad is greater than the width of the doped region corresponding to the first segment away from the pad, and / or, along the extension direction of the main gate, the width of the doped region corresponding to the second segment near the pad is greater than the width of the doped region corresponding to the center position of the second segment.
5. The back contact battery cell according to claim 4, characterized in that, Within the range corresponding to the main gate, the minimum width W3 of the doped region satisfies 100um≤W3≤300um, and the maximum width W4 of the doped region satisfies 300um<W4≤850um.
6. The back contact battery cell according to claim 1, characterized in that, Along the extension direction of the main gate, the length of the fine gate farther from the pad is L1, and the length of the fine gate closer to the pad is L2, where L1 ≤ L2 + 400 μm.
7. The back contact battery cell according to claim 1, characterized in that, The end of the doped region corresponding to the main gate has an angle along the extension direction of the main gate; the end of the doped region corresponding to the pad is parallel to the extension direction of the main gate.
8. The back contact battery cell according to claim 2, characterized in that, The doped region includes a first doped region and a second doped region; the main gate includes a first main gate and a second main gate; the fine gate includes a first fine gate and a second fine gate; the first main gate and the first fine gate are located within the projection range of the first doped region; the second main gate and the second fine gate are located within the projection range of the second doped region; the first doped region and the second doped region are distributed in a finger-like pattern; along the extension direction of the main gate, the width of the region corresponding to the first doped region and the first main gate is proportional to the width of the first main gate; the width of the region corresponding to the second doped region and the second main gate is proportional to the width of the second main gate.
9. A method for preparing a back contact solar cell, characterized in that, The method for fabricating the back contact solar cell includes: fabricating a silicon substrate; forming a tunneling oxide layer and a doped polycrystalline silicon layer on the back side of the silicon substrate; depositing a passivation layer and an antireflection layer on the front side of the silicon substrate; depositing a transparent conductive oxide layer on the back side of the silicon substrate; and fabricating gate lines on the back side of the silicon substrate. The doped polycrystalline silicon layer includes a doped region, and the gate lines include a main gate and fine gates. Along the extension direction of the main gate, the doped region has a varying width, and the fine gates have varying lengths. Multiple pads are spaced apart on the main gate, and the length of the fine gates furthest from the pads is greater than the length of the fine gates closest to the pads. The width of the doped region corresponding to the end of the main gate closest to the pads is greater than the width of the doped region corresponding to the end of the main gate furthest from the pads.
10. The method for preparing a back contact battery cell according to claim 9, characterized in that, In the step of forming a tunneling oxide layer and a doped polycrystalline silicon layer on the back side of the silicon substrate, the method for fabricating the back contact solar cell specifically includes: depositing a tunneling oxide layer and an intrinsic polycrystalline silicon layer on the back side of the silicon substrate; depositing a mask layer on the intrinsic polycrystalline silicon layer; performing laser grooving on the mask layer to form a first groove with varying width; doping the intrinsic polycrystalline silicon layer in the region corresponding to the first groove to form a first doped region; performing laser grooving on the mask layer to form a second groove with varying width; and doping the intrinsic polycrystalline silicon layer in the region corresponding to the second groove to form a second doped region.
11. The method for preparing a back contact battery cell according to claim 9, characterized in that, In the step of fabricating grid lines on the back side of the silicon substrate, the method for fabricating the back contact solar cell further includes: screen printing grid lines on the back side of the silicon substrate using a screen printing plate; wherein the screen printing plate includes a first mesh and a second mesh, the first mesh being used to print the main grid and the second mesh being used to print the fine grid; along the extension direction of the main grid, the first mesh has a width variation and the second mesh has a length variation.
12. A back-contact solar tandem cell, characterized in that, The back-contact solar tandem cell includes a back-contact bottom cell and a perovskite top cell, wherein the perovskite top cell is electrically connected to the front side of the back-contact bottom cell, and the back-contact bottom cell is a back-contact cell as described in any one of claims 1-8.
13. A photovoltaic module, characterized in that, The photovoltaic module includes the back-contact solar cell as described in any one of claims 1-8.