Back contact solar cell, manufacturing method thereof and photovoltaic module

Abstract

The invention relates to a back contact solar cell, a manufacturing method thereof and a photovoltaic module. The back contact solar cell includes: a substrate; the plurality of first polar structures are arranged on the first surface of the substrate; the plurality of second polar structures are arranged on the first surface of the substrate; the doping types of the first polar structures and the second polar structures are opposite, the first polar structures and the second polar structures are alternately arranged at intervals along a first preset direction, and an insulating isolation groove is defined between the adjacent first polar structure and second polar structure; and the marking structure is arranged in the insulating isolation groove and is spaced from the first polar structure and the second polar structure. According to the back contact solar cell and the manufacturing method thereof, the positioning precision of the photovoltaic module is relatively high, and the yield of solar cell production is also relatively high.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and in particular to a back-contact solar cell and its manufacturing method, as well as a photovoltaic module. Background Technology

[0002] Back-contact solar cells have finger-like, interlaced P-regions and N-regions formed on the back side of the cell. Both the positive and negative electrodes are located on the back, with no metal obstructing the front, significantly improving optical absorption. The manufacturing process for back-contact solar cells is more complex than that for bifacial cells, requiring higher precision in the back-side fabrication. Therefore, marking structures on the back side are used as positioning references to assist in patterning and wafer positioning. However, related technologies suffer from low precision in gripping these marking structures, which reduces the yield of solar cells. Summary of the Invention

[0003] Therefore, it is necessary to provide a back-contact solar cell with high positioning accuracy and high yield in solar cell production, as well as its manufacturing method and photovoltaic module.

[0004] One embodiment of this application provides a back-contact solar cell, comprising:

[0005] Substrate;

[0006] Multiple first polarity structures are disposed on the first surface of the substrate;

[0007] Multiple second polarity structures are disposed on a first surface of a substrate; the first polarity structures and the second polarity structures have opposite doping types, and the multiple first polarity structures and the second polarity structures are arranged alternately and at intervals along a first predetermined direction, with insulating isolation trenches defining adjacent first polarity structures and second polarity structures; and

[0008] The marking structure is located in the insulating isolation groove and is spaced apart from both the first polarity structure and the second polarity structure.

[0009] In one embodiment, the bottom of the insulating isolation trench includes a first portion and a second portion, the first portion extending along the thickness direction of the substrate to a first surface, and the second portion protruding along the thickness direction of the substrate in a direction away from the substrate relative to the first surface, the second portion forming a marking structure.

[0010] In one embodiment, the reflectivity of the surface of the marker structure facing away from the substrate is different from that of the surface of the first portion.

[0011] In one embodiment, the reflectivity of the surface of the marker structure facing away from the substrate is greater than the reflectivity of the surface of the first portion.

[0012] In one embodiment, the surface of the marker structure facing away from the substrate is configured as a polished surface;

[0013] At least a portion of the surface of the first part has a velvety texture.

[0014] In one embodiment, the average roughness of the surface of the marking structure away from the substrate is less than the average roughness of the surface of the first portion.

[0015] In one embodiment, the marker structure includes at least a doped layer identical to that of the first polar structure; or,

[0016] The marking structure includes at least the same doped layer as the second polar structure.

[0017] In one embodiment, the first polar structure includes a first tunneling oxide layer and a first doped polysilicon layer stacked on the first surface;

[0018] The marking structure includes a first film layer and a second film layer stacked on the first surface. The first film layer is made of the same material as the first tunneling oxide layer, and the second film layer is made of the same material as the first doped polysilicon layer.

[0019] In one embodiment, the second polar structure includes a second tunneling oxide layer and a second doped polysilicon layer stacked on the first surface;

[0020] The marking structure includes a first film layer and a second film layer stacked on the first surface. The first film layer is made of the same material as the second tunneling oxide layer, and the second film layer is made of the same material as the second doped polysilicon layer.

[0021] In one embodiment, the film structure of the marker structure is different from the film structure of the first polar structure or the second polar structure.

[0022] In one embodiment, the cross-sectional profile of the marker structure is circular, annular, or polygonal; or,

[0023] The cross-sectional profile of the marked structure includes at least two intersecting strip patterns.

[0024] In one embodiment, when the cross-sectional profile of the marker structure is a polygon, the side length of the cross-sectional profile is 50μm-950μm.

[0025] In one embodiment, the back contact solar cell further includes a first passivation layer;

[0026] The first passivation layer is disposed on the surface of the first polar structure and the second polar structure opposite to the substrate, and covers the marking structure.

[0027] In one embodiment, the spacing between the marker structure and the first polar structure is greater than 20 μm, and the spacing between the marker structure and the second polar structure is greater than 20 μm.

[0028] In one embodiment, a first inner diffusion layer and a second inner diffusion layer are provided on the first surface of the substrate. The doping element type of the first inner diffusion layer is the same as that of the first polar structure, and the doping element type of the second inner diffusion layer is the same as that of the second polar structure.

[0029] The first inner diffusion layer is located at the position corresponding to the first polar structure and the marker structure, and the second inner diffusion layer is located at the position corresponding to the second polar structure.

[0030] In one embodiment, the thickness of the first inner diffusion layer is greater than the thickness of the second inner diffusion layer.

[0031] In one embodiment, the thickness of the first inner diffusion layer is 50nm-200nm, and the thickness of the second inner diffusion layer is 20nm-100nm.

[0032] In one embodiment, the back-contact solar cell further includes a first electrode and a second electrode;

[0033] The first electrode is disposed on the side of the first polar structure away from the substrate and is electrically connected to the doped layer in the first polar structure.

[0034] The second electrode is located on the side of the second polar structure away from the substrate and is electrically connected to the doped layer in the second polar structure.

[0035] In one embodiment, the first polar structure includes a first main structure and a first finger structure, and the second polar structure includes a second main structure and a second finger structure.

[0036] The first main structure of the first polarity structure and the second main structure of the second polarity structure are arranged alternately and at intervals along the first preset direction;

[0037] Each first main structure is connected to at least two first finger structures spaced apart in a second preset direction, and each second main structure is connected to at least two second finger structures spaced apart in a second preset direction; wherein the first preset direction and the second preset direction intersect and are both perpendicular to the thickness direction of the back-contact solar cell.

[0038] The first finger-like structures and second finger-like structures located between two adjacent first main structures and second main structures are interlaced with each other in a forked manner along a first preset direction.

[0039] The marking structure is located in the region between the interlaced first and second finger structures.

[0040] In one embodiment, the marker structure is located between adjacent first and second finger structures in a second predetermined direction.

[0041] In one embodiment, the first finger structure and the second finger structure located between two adjacent first main structures and second main structures are arranged alternately along a second preset direction;

[0042] The marking structure is located on the side of the first finger structure away from the corresponding first main structure along a first preset direction; or

[0043] The marking structure is located on the side of the second finger structure away from the corresponding second main structure along the first preset direction.

[0044] In one embodiment, the marking structure is located on the side of the second finger structure away from the corresponding second main structure along a first preset direction;

[0045] The first polar structure also includes a first connecting structure, in which two adjacent first finger structures in the second preset direction are connected by the first connecting structure;

[0046] The marking structure is located between the second finger structure, which is inserted between two adjacent first finger structures along the second preset direction, and the corresponding first connecting structure.

[0047] In one embodiment, the marking structure is located on the side of the first finger structure away from the corresponding first main structure along a first preset direction; the second polar structure further includes a second connecting structure, in which two adjacent second finger structures in the second preset direction are connected by the second connecting structure;

[0048] The marking structure is located between the first finger structure, which is inserted between two adjacent second finger structures along the second preset direction, and the corresponding second connecting structure.

[0049] In one embodiment, the first electrode includes a plurality of first main gates and a first fine gate electrically connected to the first main gates, and the second electrode includes a plurality of second main gates and a second fine gate electrically connected to the second main gates;

[0050] The first main structure and the first finger structure are respectively provided with a first main gate and a first fine gate; the second main structure and the second finger structure are respectively provided with a second main gate and a second fine gate.

[0051] In one embodiment, the first electrode includes a plurality of first main gates and a first fine gate, and the second electrode includes a plurality of second main gates and a second fine gate;

[0052] Multiple first main gates and multiple second main gates are arranged alternately and at intervals along a first preset direction;

[0053] Each first main grid is connected to at least two first fine grids arranged at intervals in a second preset direction, and each second main grid is connected to at least two second fine grids arranged at intervals in a second preset direction; wherein, the first preset direction and the second preset direction intersect and are both perpendicular to the thickness direction of the back-contact solar cell;

[0054] The first and second fine grids located between two adjacent first and second main grids are arranged in an interlacing pattern along a first preset direction.

[0055] The marking structure is located in the area between the first and second fine grids arranged in an interleaved manner.

[0056] In one embodiment, the marker structure is located between a first fine gate and a second fine gate that are adjacent in a second preset direction.

[0057] In one embodiment, the first and second fine grids located between two adjacent first and second main grids are arranged alternately along a second preset direction;

[0058] The marking structure is located on the side of the first fine grid opposite to the corresponding first main grid along a first preset direction, and the distance between the center of the marking structure and the first main grid is greater than or equal to the distance between the marking structure and the second main grid; or

[0059] The marking structure is located on the side of the second fine grid away from the corresponding second main grid along the first preset direction, and the distance between the center of the marking structure and the second main grid is greater than or equal to the distance between the marking structure and the first main grid.

[0060] In one embodiment, both the first and second fine gates extend along a first preset direction;

[0061] The marking structure is located on the side of the second fine grid that is opposite to the corresponding second main grid along the first preset direction;

[0062] The first electrode also includes a first connecting grid line, which is located between two adjacent first fine grids. The marking structure is located between a second fine grid that passes through two adjacent first fine grids along a second preset direction and the corresponding first connecting grid line.

[0063] In one embodiment, the marking structure is located on the side of the first fine gate that is opposite to the corresponding first main gate along a first preset direction;

[0064] The second electrode also includes a second connecting grid line, which is located between two adjacent second fine grids. The marking structure is located between the first fine grid, which is inserted between two adjacent second fine grids along the second preset direction, and the corresponding second connecting grid line.

[0065] Another aspect of this application provides a method for manufacturing a back-contact solar cell, including:

[0066] A first polar structure and a marking structure are formed in a first region and a marking region on a first side of the substrate, respectively. A first mask pattern is stacked on the surface of the first polar structure and the marking structure facing away from the substrate. The first side is also constructed with a second region and an isolation region. The first region and the second region are arranged alternately along a first preset direction. The isolation region is isolated between adjacent first regions and second regions. The marking region is located in the isolation region, and the outer contour line of the marking region is spaced apart from the outer contour line of the isolation region.

[0067] A second polar material layer and a second mask material layer are stacked on the side of the first mask pattern away from the substrate to form at least a layer covering the entire first surface;

[0068] Using the marking structure and the first mask pattern, the second polar material layer and the second mask material layer stacked on the marking structure as positioning references, the second polar material layer is formed into a second polar structure located in the second region, and an insulating isolation groove corresponding to the isolation region is formed between the first polar structure and the second polar structure.

[0069] In one embodiment, the steps of forming the second polarity structure and the insulating isolation trench specifically include:

[0070] Using the marker structure and the first mask pattern, the second polar material layer and the second mask material layer stacked on the marker structure as positioning references, the portion of the second mask material layer covering the first region and the isolation region is removed;

[0071] The second mask material layer is further patterned, and the portion of the second mask material layer corresponding to the second region is retained to form the second mask pattern;

[0072] Using the second mask pattern as a mask, the second polar material layer is etched to form a second polar structure covering the second region, and an insulating isolation trench corresponding to the isolation region is formed between the first polar structure and the second polar structure.

[0073] In one embodiment, the step of removing the portion of the second mask material layer that covers the first region and the isolation region specifically includes:

[0074] By using the marking structure and the structure formed by the first mask pattern, the second polar material layer and the second mask material layer stacked on the marking structure as the positioning reference, the portion of the second mask material layer covering the first area and the isolation area is removed by laser.

[0075] In one embodiment, a second polar material layer and a second mask material layer are also formed on the second side and the side side of the substrate, wherein the second side is disposed opposite to the first side, and the side side is adjacent to the first side and the second side;

[0076] The step of further patterning the second mask material layer, retaining the portion of the second mask material layer corresponding to the second region to form the second mask pattern, specifically includes:

[0077] The second mask material layer covering the sides and second surface is partially removed by cleaning with an acidic solution.

[0078] In one embodiment, the steps of forming the second polarity structure and the insulating isolation trench specifically include:

[0079] Using the second mask pattern as a mask, the second polar material layer is wet-etched with an alkaline solution to form the second polar structure and the insulating isolation trench.

[0080] In one embodiment, the portion outside the marked area in the isolation region is defined as the target region; the step of using a second mask pattern as a mask and performing wet etching on the second polar material layer with an alkaline solution specifically includes:

[0081] The second polar material layer covering the first and isolation areas is partially removed by an alkaline solution, and a velvety structure is formed on the surface of the target area.

[0082] In one embodiment, the steps of forming the first polar structure and the marker structure specifically include:

[0083] A first polar material layer and a first mask material layer are stacked on at least the first surface of the substrate;

[0084] The first mask material layer is patterned into a first mask pattern, which covers the marking area and the first area.

[0085] The first polar material layer is etched using the first mask pattern as a mask to form the first polar structure and the marking structure.

[0086] In one embodiment, a first polar material layer and a first mask material layer are also formed on the second side and the side side of the substrate, wherein the second side is disposed opposite to the first side, and the side side is adjacent to the first side and the second side, and the portion outside the marked area in the isolation region is defined as the target area.

[0087] The specific steps of patterning the first mask material layer into the first mask pattern include:

[0088] A laser is used to remove the portion of the first mask material layer covering the second region and the target region;

[0089] The first mask material layer covering the sides and second side is partially removed by cleaning with an acidic solution.

[0090] In one embodiment, the step of using a laser to remove a portion of the first mask material layer covering the target area specifically includes:

[0091] The isolation area is scanned using a laser. When the marked area is scanned, the laser is turned off for a preset time until the target area is scanned, at which point the laser is turned on again.

[0092] In one embodiment, the step of stacking and forming at least a first polar material layer and a first mask material layer on a first surface of the substrate specifically includes:

[0093] A first tunneling material layer and a first doped polycrystalline silicon material layer are sequentially stacked on each surface of the substrate as a first polar material layer, and a first oxide material layer is formed on the surface of the first doped polycrystalline silicon material layer away from the substrate as a first mask material layer.

[0094] In one embodiment, the step of stacking a second polar material layer and a second mask material layer covering at least the entire first surface on the side of the first mask pattern opposite to the substrate specifically includes:

[0095] A second tunneling material layer and a second doped polysilicon material layer are sequentially stacked on each side of the substrate as a second polar material layer. A second oxide material layer is formed on the surface of the second doped polysilicon material layer away from the substrate as a second mask material layer.

[0096] In one embodiment, the portion of the isolation zone outside the marked area is defined as the target area, and the surface of the target area is formed with a velvety structure;

[0097] The steps following the formation of the second polarity structure and the insulating isolation groove also include:

[0098] Remove the second mask material layer covering the first mask pattern and the second polar structure layer;

[0099] A first passivation layer is formed on the side of the first polar structure, the second polar structure, and the marking structure away from the substrate, and the first passivation layer covers the entire first surface.

[0100] In one embodiment, the step of forming the first passivation layer is followed by:

[0101] Using the marking structure and the first passivation layer covering the marking structure as positioning references, a first electrode and a second electrode are formed on the first passivation layer at positions corresponding to the first polar structure and the second polar structure, respectively; wherein, the first electrode is electrically connected to the first polar structure, and the second electrode is electrically connected to the second polar structure.

[0102] In another aspect, this application provides a back-contact solar cell, which is manufactured using the aforementioned back-contact solar cell manufacturing method.

[0103] In another aspect, this application provides a photovoltaic module including at least one battery string, the battery string including at least two of the above-described back-contact solar cells.

[0104] The aforementioned back-contact solar cells, their fabrication methods, and the beneficial effects of photovoltaic modules are as follows:

[0105] By placing the marking structure within the insulating isolation trench and spacing it between both the first and second polarity structures—in other words, by spacing the marking structure between itself and the surrounding first and second polarity structures—the marking structure is also spaced from the sidewalls of the insulating isolation trench surrounding it. This creates an island-like structure within the insulating isolation trench. Compared to related technologies where the marking structure is formed in a P-doped or N-doped layer, and the outer contour of the marking structure is easily confused with the outer contour of the P-doped or N-doped layer, the marking structure avoids the problem of confusion with the first and second polarity structures. During positioning, it is not only easier to grasp but also has higher grasping accuracy, further improving the yield of back-contact solar cell production. Attached Figure Description

[0106] Figure 1 This is a schematic diagram showing the location of the marker structure in the related technology;

[0107] Figure 2a This is a schematic diagram of the structure of a back-contact solar cell provided in an embodiment of this application;

[0108] Figure 2b Another schematic diagram of a back-contact solar cell provided in an embodiment of this application;

[0109] Figure 2c Another schematic diagram of a back-contact solar cell provided in an embodiment of this application;

[0110] Figure 3 A top view of the first polarity structure and the second polarity structure in the back contact solar cell provided in the embodiments of this application;

[0111] Figure 4 This is a schematic diagram illustrating another placement of the marking structure in a back-contact solar cell provided in an embodiment of this application.

[0112] Figure 5 This is a schematic diagram illustrating another possible placement of the marking structure in a back-contact solar cell provided in an embodiment of this application.

[0113] Figure 6 A schematic diagram of another structure of the back-contact solar cell provided in the embodiments of this application;

[0114] Figure 7A schematic flowchart illustrating the fabrication method of a back-contact solar cell provided in an embodiment of this application;

[0115] Figure 8 A schematic diagram illustrating the formation of a first tunneling material layer, a first doped polycrystalline silicon material layer, and a first mask material layer in the fabrication method of a back contact solar cell provided in this application embodiment;

[0116] Figure 9 This is a schematic diagram of patterning on one side of the first surface of the substrate in the method for fabricating a back-contact solar cell provided in the embodiments of this application;

[0117] Figure 10 This is a schematic diagram illustrating the removal of the first mask material layer on the side and second side in the method for fabricating a back-contact solar cell provided in this application embodiment.

[0118] Figure 11 A schematic diagram of the first polarity structure and the marking structure in the method for fabricating a back-contact solar cell provided in the embodiments of this application;

[0119] Figure 12 A schematic diagram illustrating the formation of a second tunneling material layer, a second doped polycrystalline silicon material layer, and a second mask material layer in the fabrication method of a back contact solar cell provided in this application embodiment;

[0120] Figure 13 This is a schematic diagram showing the marked structural positions after the formation of the second tunneling material layer, the second doped polysilicon material layer, and the second mask material layer.

[0121] Figure 14 A schematic diagram of the three-dimensional structure at the marked structure position after the formation of the second tunneling material layer, the second doped polycrystalline silicon material layer and the second mask material layer;

[0122] Figure 15 A schematic diagram illustrating the formation of a second mask pattern in a method for fabricating a back-contact solar cell according to an embodiment of this application;

[0123] Figure 16 A schematic diagram illustrating the formation of a second polarity structure in the fabrication method of a back-contact solar cell provided in this application embodiment;

[0124] Figure 17 This is a schematic diagram showing the location of the marked structure after the second polar structure has been formed;

[0125] Figure 18 A schematic diagram of the three-dimensional structure at the marked structural position after the formation of the second polar structure;

[0126] Figure 19This is a schematic diagram illustrating the formation of a first passivation layer and a second passivation layer in the fabrication method of a back-contact solar cell provided in this application embodiment.

[0127] Explanation of icon numbers:

[0128] 100. Back-contact solar cell;

[0129] 10. Substrate; 20. First polar structure; 201. First main structure; 202. First finger structure; 203. First connection structure; 205. First inner diffusion layer; 21. First tunneling oxide layer; 22. First doped polysilicon layer; 30. Second polar structure; 301. Second main structure; 302. Second finger structure; 303. Second connection structure; 304. Second inner diffusion layer; 31. Second tunneling oxide layer; 32. Second doped polysilicon layer; 40. Insulating isolation trench; 41. Textured structure; 401. First portion; 402. Second portion; 50. 101. Marking structure; 51. First film layer; 52. Second film layer;

[0130] 61. First passivation layer; 62. Second passivation layer; 621. Passivation film layer; 622. Antireflection film layer;

[0131] 70. First polar material layer; 71. First tunneling material layer; 72. First doped polycrystalline silicon material layer; 73. First mask material layer; 730. First mask pattern;

[0132] 80. Second polar material layer; 81. Second tunneling material layer; 82. Second doped polysilicon material layer; 83. Second mask material layer; 830. Second mask pattern;

[0133] 91. First electrode; 911. First main gate; 912. First fine gate; 913. First connecting gate line; 92. Second electrode; 921. Second main gate; 922. Second fine gate; 923. Second connecting gate line;

[0134] 102. P-doped layer; 103. N-doped layer; 104. Fine gate;

[0135] F, First side; S, Second side; C, Side; Y, First zone; E, Second zone; G, Isolation zone; T, Target zone; B, Marking zone; F1, First preset direction; F2, Second preset direction. Detailed Implementation

[0136] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0137] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention 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. Therefore, they should not be construed as limitations on this invention.

[0138] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0139] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0140] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0141] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0142] The following description, in conjunction with the accompanying drawings, illustrates the back-contact solar cell, its fabrication method, and photovoltaic module according to embodiments of this application. It should be noted that this application uses a TBC (Total Cell Charge) back-contact solar cell as an example for illustration. However, the back-contact solar cell can also be configured as other types of cells, such as HBC (Hybrid Cell Charge) solar cells, depending on actual needs. The same principle applies to other types of back-contact solar cells, and will not be elaborated upon here.

[0143] Figure 1 This is a schematic diagram showing the location of the marker structure in the related technology; Figure 2a This is a schematic diagram of the structure of a back-contact solar cell provided in an embodiment of this application; Figure 2b Another schematic diagram of a back-contact solar cell provided in an embodiment of this application; Figure 2c Another schematic diagram of a back-contact solar cell provided in an embodiment of this application; Figure 3 A top view of the first polarity structure and the second polarity structure in the back contact solar cell provided in the embodiments of this application; Figure 4 This is a schematic diagram illustrating another placement of the marking structure in a back-contact solar cell provided in an embodiment of this application.

[0144] Figure 5 This is a schematic diagram illustrating another possible placement of the marking structure in a back-contact solar cell provided in an embodiment of this application. Figure 6 This is a schematic diagram of another structure of a back-contact solar cell provided in an embodiment of this application.

[0145] In related technologies, refer to Figure 1The marking structure 101 (also commonly referred to as a marking point) is a groove structure formed on the P-doped layer 102 or the N-doped layer 103. Here, we will take the formation on the N-doped layer 103 as an example. After the passivation layer is deposited on the P-doped layer 102 or the N-doped layer 103, electrode paste is printed on both layers. The marking structure 101 is located on the N-doped layer 103 at the position corresponding to the fine gate 104. It can serve as a positioning reference during the formation of the N-doped layer 103 or the printing of the electrode paste. However, when gripping and positioning the marking structure 101, it is easy to confuse it with the outer contour line of the P-doped layer 102 or the N-doped layer, resulting in low gripping accuracy.

[0146] Furthermore, during the printing of electrode paste on the P-doped layer 102 and the N-doped layer 103, the electrode paste is prone to burn through the passivation layer and come into contact with the substrate at the marking structure 101 of the trench structure. Taking the N-type substrate as an example, if the marking structure 101 is formed on the P-doped layer 102, the metal electrode on the P-doped layer 102 will come into contact with the N substrate, causing leakage of the PN junction. If the marking structure 101 is formed on the N-doped layer 103, the metal electrode on the N-doped layer 103 will come into contact with the N substrate, forming a large metal recombination. Both of these situations will affect the battery efficiency.

[0147] In this embodiment, the marking structure is placed in the insulating isolation groove to form an island-like structure, which can effectively improve the gripping accuracy. In addition, since the metal paste will not be printed onto the insulating isolation groove, the problems of leakage and metal composite can also be effectively avoided, thereby improving battery efficiency.

[0148] Reference Figure 2a and Figure 2b The back-contact solar cell 100 provided in this application embodiment includes: a substrate 10, a plurality of first polarity structures 20, a plurality of second polarity structures 30, and a marking structure 50.

[0149] Multiple first polarity structures 20 are disposed on the first surface F of the substrate 10. Multiple second polarity structures 30 are disposed on the first surface F of the substrate 10. The first polarity structures 20 and the second polarity structures 30 have opposite doping types, and the multiple first polarity structures 20 and the second polarity structures 30 are arranged alternately and spaced apart from each other along a first predetermined direction F1, with an insulating isolation trench 40 defining the space between adjacent first polarity structures 20 and second polarity structures 30. Figure 2a In the diagram, the location and setting range of the insulating isolation groove 40 are outlined by a single-dot dashed box. The marking structure 50 is located in the insulating isolation groove 40 and is spaced apart from both the first polarity structure 20 and the second polarity structure 30.

[0150] It is understood that an insulating isolation trench 40 is defined between adjacent first polarity structures 20 and second polarity structures 30. In some embodiments, the first polarity structures 20 and second polarity structures 30 constitute the sidewalls of the insulating isolation trench 40. By placing the marking structure 50 in the insulating isolation trench 40 and spacing it between it and both the first polarity structures 20 and 30, the marking structure 50 is spaced from the sidewalls of the adjacent insulating isolation trench 40, forming an island-like structure within the insulating isolation trench 40. Thus, compared to the related art where the marking structure 101 is formed on a P-doped layer 102 or an N-doped layer 103, and the outer contour of the marking structure 101 is easily confused with the outer contour of the P-doped layer 102 or N-doped layer 103, the marking structure 50 does not cause confusion with the first polarity structures 20 and 30. During positioning, it is not only easier for the camera to capture and identify, resulting in higher positioning accuracy, but it can also further improve the yield of the back contact solar cell 100 production.

[0151] In addition, as mentioned above, in the related technology, at the location of the marking structure 101, the electrode paste is prone to burn through the passivation layer and come into contact with the substrate, causing leakage of the PN junction, or forming a large metal composite with the substrate. Both of these situations will affect the battery efficiency.

[0152] In this embodiment, the marking structure 50 is disposed in the insulating isolation tank 40. When the first electrode 91 is fabricated on the first polarity structure 20 and the second electrode 92 is fabricated on the second polarity structure 30, the metal paste of the first electrode 91 and the second electrode 92 will not enter the insulating isolation tank 40. There is no leakage risk as in related technologies, nor is there a problem of increased metal recombination. Therefore, compared with related technologies, the efficiency of the back contact solar cell 100 in this embodiment will be further improved.

[0153] In this embodiment, the substrate 10 further includes a second surface S disposed opposite to the first surface F, and a side surface C adjacent to the first surface F and the second surface S. For ease of explanation, a first region Y, a second region E, and an isolation region G are defined on the first surface F. Referring to... Figure 2a The first zone Y and the second zone E are arranged alternately along the first preset direction F1, and the isolation zone G is isolated between the adjacent first zone Y and the second zone E. In addition, the isolation zone G is divided into two parts: the marking zone B and the target zone T. The target zone T surrounds the marking zone B, and at the same time, the target zone T also isolates the marking zone B from the surrounding first zone Y and second zone E.

[0154] It should be noted that both the first polar structure 20 and the second polar structure 30 include doped layers. The doping types of the first polar structure 20 and the second polar structure 30 are opposite, meaning that the doping elements in the doped layers of the first polar structure 20 and the second polar structure 30 have opposite doping types. For example, in some embodiments, the doped layer in the first polar structure 20 is P-type and the doped layer in the second polar structure 30 is N-type, or vice versa. In this embodiment, the example of the first polar structure 20 having a P-type doped layer and the second polar structure 30 having an N-type doped layer is used for illustration. The case where the first polar structure 20 has an N-type doped layer and the second polar structure 30 has a P-type doped layer is similar and will not be repeated here.

[0155] Multiple first polarity structures 20 are disposed on a first surface F of the substrate 10, and multiple second polarity structures 30 are also disposed on the first surface F of the substrate 10. For example, multiple first polarity structures 20 may be disposed in a first region Y of the first surface F of the substrate 10, and multiple second polarity structures 30 may be disposed in a second region E of the first surface F of the substrate 10. Here, the first polarity structures 20 may cover the entire region Y, and the second polarity structures 30 may cover the entire region E.

[0156] like Figure 3 As shown, multiple first polarity structures 20 and second polarity structures 30 are arranged alternately and at intervals along a first preset direction F1, and some structures of adjacent first polarity structures 20 and second polarity structures 30 can be interlaced with each other in an interdigitated manner.

[0157] The marking structure 50 is disposed in the insulating isolation groove 40 and is spaced apart from both the first polarity structure 20 and the second polarity structure 30. This means that when viewed from the first surface F and back-contacting the solar cell 100, there is a gap between the marking structure 50 and the first polarity structure 20, and also between the marking structure 50 and the second polarity structure 30, thus making the marking structure 50 easy to grasp.

[0158] In the embodiments of this application, reference is made to Figure 2a and Figure 2cThe bottom of the insulating isolation trench 40 includes a first portion 401 and a second portion 402. The first portion 401 extends along the thickness direction of the substrate 10 to a first surface F, and the second portion 402 protrudes along the thickness direction of the substrate 10 relative to the first surface F in a direction away from the substrate 10. That is, the second portion 402 defines a protruding structure relative to the first portion, thereby forming a marking structure 50. With this configuration, within the insulating isolation trench 40, when viewed in the thickness direction of the substrate 10, the film thickness at the location of the marking structure 50 (the second portion 402) is greater than the film thickness of the area surrounding the marking structure 50 (the first portion 401), making the marking structure 50 easier to distinguish from the surrounding area.

[0159] In this embodiment of the application, combined with Figure 2a and Figure 2b The area on the first surface F corresponding to the insulating isolation groove 40 is defined as the isolation area G. In other words, the area where the insulating isolation groove 40 is set is the isolation area G. The reflectivity of the surface of the marker structure 50 facing away from the substrate 10 is different from the reflectivity of the surface of the first part 401. When the marker structure 50 corresponds to the marker area B, the reflectivity of the surface of the marker structure 50 facing away from the substrate 10 is actually different from the reflectivity of the target area T surface. Thus, when the camera captures an image, due to the difference in reflectivity, the marker structure 50 and the surrounding target area T surface will be more clearly distinguishable in the captured image, making the capture more accurate.

[0160] In this embodiment, the reflectivity of the surface of the marker structure 50 facing away from the substrate 10 is greater than the reflectivity of the surface of the first portion 401 (target area T). This is configured as follows: Figure 13 , Figure 14 , Figure 17 , Figure 18 As shown, in the captured image, the brightness of the image at the location of the marker structure 50 is higher than that of the surrounding area. Furthermore, the average roughness of the surface of the marker structure 50 facing away from the substrate 10 is less than the average roughness of the surface of the first portion 401 (target area T). This setting allows the reflectivity of the surface of the marker structure 50 facing away from the substrate 10 to be greater than the reflectivity of the surface of the first portion 401 (target area T).

[0161] In some embodiments, refer to Figure 2a , Figure 2cThe surface of the marking structure 50 facing away from the substrate 10 may be polished, and at least a portion of the surface of the first portion 401 may be textured with a textured structure 41. For example, the entire target area T may be textured with a textured structure 41, or only a portion of the target area T may be textured with a textured structure 41. Furthermore, it is understood that when the cross-sectional outline of the marking structure 50 is a solid shape, the first portion 401 may be arranged around the marking structure 50; when the cross-sectional outline of the marking structure 50 is a hollow shape, such as a ring shape, one portion of the first portion 401 may be arranged around the marking structure 50, while another portion of the first portion 401 may be located inside the marking structure 50.

[0162] In this embodiment, the marker structure 50 includes at least the same doped layer as the first polar structure 20. Alternatively, the marker structure 50 includes at least the same doped layer as the second polar structure 30. This configuration allows the marker structure 50 to be formed simultaneously with the first polar structure 20 or the second polar structure 30 in the same process, resulting in lower costs.

[0163] In some embodiments, the film structure of the marking structure 50 is the same as that of the first polar structure 20, and the thickness of the marking structure 50 may be the same as that of the first polar structure 20. Alternatively, the film structure of the marking structure 50 is the same as that of the second polar structure 30, and the thickness of the marking structure 50 may be the same as that of the second polar structure 30.

[0164] In this embodiment of the application, as described above, both the first polar structure 20 and the second polar structure 30 include a doped layer. In some embodiments, combined with Figure 2a and Figure 2b The first polar structure 20 includes a first tunneling oxide layer 21 and a first doped polysilicon layer 22 stacked on the first surface F.

[0165] The marking structure 50 includes a first film layer 51 and a second film layer 52 stacked on the first surface F. The first film layer 51 is made of the same material as the first tunneling oxide layer 21, and the second film layer 52 is made of the same material as the first doped polysilicon layer 22.

[0166] Furthermore, the second polar structure 30 includes a second tunneling oxide layer 31 and a second doped polysilicon layer 32 stacked on the first surface F. The doping type of the second doped polysilicon layer 32 is opposite to that of the first doped polysilicon layer 22. The first film layer 51 is made of the same material as the second tunneling oxide layer 31, and the second film layer 52 is made of the same material as the second doped polysilicon layer 32.

[0167] In other embodiments, the film structure of the marker structure 50 may also be different from the film structure of the first polar structure 20 or the second polar structure 30.

[0168] In this embodiment, the back-contact solar cell 100 further includes a first passivation layer 61, which is disposed on the surface of the first polar structure 20 and the second polar structure 30 away from the substrate 10 and covers the marking structure 50, such as a second film layer 52 covering the marking structure 50.

[0169] Here, the material of the first passivation layer 61 can be a single or composite thin film of silicon nitride, aluminum oxide, titanium oxide, silicon oxide, silicon oxynitride, etc. It serves to passivate the first surface F (e.g., the back surface) of the back contact solar cell 100. In some embodiments, the first passivation layer 61 can also serve to reduce reflection.

[0170] Furthermore, the back-contact solar cell 100 also includes a second passivation layer 62, which is stacked on the second surface S of the substrate 10. The second passivation layer 62 includes a passivation film layer 621 and an anti-reflection film layer 622 sequentially stacked on the second surface S. The passivation film layer 621 can be a single or multiple composite thin film such as silicon nitride, aluminum oxide, titanium oxide, silicon oxide, and silicon oxynitride, and the anti-reflection film layer 622 can be a single or multiple composite thin film such as silicon nitride and silicon oxynitride.

[0171] In this embodiment, the cross-sectional outline of the marking structure 50 is circular, annular, or polygonal. Alternatively, the cross-sectional outline of the marking structure 50 may include at least two intersecting strip-shaped patterns, i.e., the marking structure 50 is constructed in a cross shape. Of course, the shape of the cross-sectional outline of the marking structure 50 is not limited to this and may also be other shapes. Here, the cross-section is perpendicular to the thickness direction of the substrate 10.

[0172] In this embodiment, when the cross-sectional outline of the marker structure 50 is a polygon, the side length of the cross-sectional outline is 50μm-950μm. This setting ensures that the marker structure 50 maintains sufficient spacing with the adjacent first polar structure 20 and second polar structure 30, facilitating camera capture.

[0173] In the embodiments of this application, reference is made to Figure 3 The spacing between the marker structure 50 and the first polar structure 20 is greater than 20 μm, and the spacing between the marker structure 50 and the second polar structure 30 is greater than 20 μm. For example, in Figure 3 In the schematic diagram of the back-contact solar cell 100 shown from the first surface F, the distance between the marking structure 50 and each side wall of the surrounding insulating isolation trench 40 is greater than 20 μm.

[0174] In this embodiment, the number of marker structures 50 is multiple, and the multiple marker structures 50 are used to locate the geometric center of the substrate 10. For example, the number of marker structures 50 can be four, and the four marker structures can be symmetrically arranged with respect to the geometric center of the substrate 10. Alternatively, the number of marker structures 50 can also be two, three, or more.

[0175] In this embodiment, reference continues to be made to... Figure 2c , Figure 2c exist Figure 2a Based on this, a first inner diffusion layer 205 and a second inner diffusion layer 304 are also formed in the substrate 10. Figure 2c In the back contact solar cell 100, the remaining part is with Figure 2a The same applies as shown, so it will not be repeated here.

[0176] For example, the first surface F of the substrate 10 is provided with a first inner diffusion layer 205 and a second inner diffusion layer 304. The doping element type of the first inner diffusion layer 205 is the same as that of the first polar structure 20, and the doping element type of the second inner diffusion layer 304 is the same as that of the second polar structure 30. For example, the first inner diffusion layer 205 is formed when the doping element enters the substrate 10 during the formation of the doped layer and the marker structure 50 in the first polar structure 20. The second inner diffusion layer 304 is formed when the doping element enters the substrate 10 during the formation of the doped layer in the second polar structure 30.

[0177] The first inner diffusion layer 205 is located at a position corresponding to the first polar structure 20 and the marker structure 50, and the second inner diffusion layer 304 is located at a position corresponding to the second polar structure 30.

[0178] Furthermore, the thickness of the first inner diffusion layer 205 is greater than the thickness of the second inner diffusion layer 304. For example, the thickness of the first inner diffusion layer 205 is 50nm-200nm, and the thickness of the second inner diffusion layer 304 is 20nm-100nm.

[0179] In this embodiment, the back-contact solar cell 100 further includes a first electrode 91 and a second electrode 92. The first electrode 91 is disposed on the side of the first polar structure 20 away from the substrate 10 and is electrically connected to the doped layer in the first polar structure 20. The second electrode 92 is disposed on the side of the second polar structure 30 away from the substrate 10 and is electrically connected to the doped layer in the second polar structure 30.

[0180] In this embodiment, the marker structure 50 is used for positioning during the formation of the second polarity structure 30. Furthermore, the marker structure 50 is also used as a positioning reference during the formation of the first electrode 91 and the second electrode 92.

[0181] In some embodiments, reference may be made to Figure 3 The first polar structure 20 includes a first main structure 201 and a first finger structure 202, and the second polar structure 30 includes a second main structure 301 and a second finger structure 302.

[0182] The first main structure 201 of the first polarity structure 20 and the second main structure 301 of the second polarity structure 30 are arranged alternately and at intervals along a first preset direction F1. Each first main structure 201 is connected to at least two first finger-like structures 202 arranged at intervals along a second preset direction F2, and each second main structure 301 is connected to at least two second finger-like structures 302 arranged at intervals along a second preset direction F2. The first preset direction F1 and the second preset direction F2 intersect and are both perpendicular to the thickness direction of the back-contact solar cell 100.

[0183] The first finger-like structures 202 and the second finger-like structures 302 located between two adjacent first main structures 201 and second main structures 301 are interlaced with each other in a cross-finger shape along a first preset direction F1. The marking structure 50 is located in the area between the interlaced first finger-like structures 202 and second finger-like structures 302, that is, in the interlaced arrangement area of ​​the first finger-like structures 202 and second finger-like structures 302.

[0184] Reference Figure 3 The first finger-like structures 202 and 302 located between two adjacent first main structures 201 and second main structures 301 are interlaced in a forked manner along a first preset direction F1. Specifically, the first finger-like structures 202 and 302 located between two adjacent first main structures 201 and second main structures 301 have intersecting portions along the first preset direction F1. For example, along the first preset direction F1, the first finger-like structure 202 on the right side of the first main structure 201 interlaces in a forked manner into the gap between the adjacent second finger-like structures 302 on the left side of the second main structure 301. The interlaced arrangement area refers to the area where the first finger-like structures 202 and second finger-like structures 302 are interlaced.

[0185] In this embodiment of the application, the first finger structure 202 and the second finger structure 302 located between two adjacent first main structures 201 and second main structures 301 can be arranged alternately along the second preset direction F2.

[0186] Furthermore, the specific location of the marker structure 50 can be, for example, a reference. Figure 3 , Figure 5 As shown, they are located on one side of the ends of the first finger structure 202 and the second finger structure 302, respectively. Alternatively, they can be... Figure 4 As shown, in the second preset direction F2, it is located between the adjacent first finger structure 202 and the second finger structure 302.

[0187] Specifically, refer to Figure 3 The marking structure 50 is located on the side of the second finger structure 302 away from the corresponding second main structure 301 along the first preset direction F1.

[0188] Furthermore, the first polarity structure 20 also includes a first connecting structure 203. Two adjacent first finger structures 202 along the second preset direction F2 are connected by the first connecting structure 203. The marking structure 50 is located between a second finger structure 302 that passes through the two adjacent first finger structures 202 along the second preset direction and the corresponding first connecting structure 203. With this configuration, along the first preset direction F1, the left and right sides of the marking structure 50 are respectively the first polarity structure 20 and the second polarity structure 30, which can fully collect current and increase the collection efficiency of charge carriers.

[0189] Reference Figure 5 In another possible implementation, the marking structure 50 is located on the side of the first finger structure 202 away from the corresponding first main structure 201 along the first preset direction F1.

[0190] Furthermore, the second polarity structure 30 also includes a second connecting structure 303. Two adjacent second finger structures 302 along the second preset direction F2 are connected by the second connecting structure 303. The marker structure 50 is located between the first finger structure 202, which is inserted between the two adjacent second finger structures 302 along the second preset direction, and the corresponding second connecting structure 303. With this configuration, along the first preset direction F1, the left and right sides of the marker structure 50 are also the first polarity structure 20 and the second polarity structure 30, respectively, which can fully collect current and increase the collection efficiency of charge carriers.

[0191] Reference Figure 4 In another possible implementation, the marker structure 50 is located between adjacent first finger structures 202 and second finger structures 302 in the second preset direction F2. Figure 4 In the example, the structure above the marker structure 50 is the first finger structure 202, and the structure below it is the second finger structure 302. Figure 4 Based on this, it is also possible that the upper part of the marker structure 50 is the second finger structure 302, and the lower part is the first finger structure 202.

[0192] In this embodiment, reference is continued. Figure 3 The first electrode 91 includes a plurality of first main gates 911 and a first fine gate 912 electrically connected to the first main gates 911, and the second electrode 92 includes a plurality of second main gates 921 and a second fine gate 922 electrically connected to the second main gates 921.

[0193] A first main gate 911 and a first fine gate 912 are respectively provided on the first main structure 201 and the first finger structure 202. A second main gate 921 and a second fine gate 922 are respectively provided on the second main structure 301 and the second finger structure 302. For example, the first main gate 911 is disposed on the side of the first main structure 201 facing away from the substrate 10, and the first fine gate 912 is disposed on the side of the first finger structure 202 facing away from the substrate 10. The second main gate 921 is disposed on the side of the second main structure 301 facing away from the substrate 10, and the second fine gate 922 is disposed on the side of the second finger structure 302 facing away from the substrate 10.

[0194] In this way, multiple first main gates 911 and multiple second main gates 921 are also arranged alternately and at intervals along the first preset direction F1. Each first main gate 911 is connected to at least two first fine gates 912 arranged at intervals along the second preset direction F2, and each second main gate 921 is also connected to at least two second fine gates 922 arranged at intervals along the second preset direction F2. The first fine gates 912 and second fine gates 922 located between two adjacent first main gates 911 and second main gates 921 are interlaced with each other in an interdigitated manner along the first preset direction F1, thereby marking the area of ​​the structure 50 located between the interlaced first fine gates 912 and second fine gates 922, that is, the interlaced arrangement area of ​​the first fine gates 912 and second fine gates 922.

[0195] Furthermore, the first fine grid 912 and the second fine grid 922 located between two adjacent first main grids 911 and second main grids 921 are alternately arranged along a second preset direction F2. And both the first fine grid 912 and the second fine grid 922 extend along the first preset direction F1.

[0196] Corresponding to the aforementioned first main structure 201, first finger structure 202, second main structure 301, and second finger structure 302 are:

[0197] like Figure 3 As shown, the marker structure 50 is located on the side of the second fine gate 922 opposite to the corresponding second main gate 921 along the first preset direction F1. The distance between the center of the marker structure 50 and the second main gate 921 is greater than or equal to the distance between the marker structure 50 and the first main gate 911. This is because the setting of the marker structure 50 shortens the length of the second fine gate 922 at the position corresponding to the marker structure 50, resulting in a weaker collection capability for N-type carriers at that position. However, by ensuring that the distance between the center of the marker structure 50 and the second main gate 921 is greater than or equal to the distance between the marker structure 50 and the first main gate 911, the shortening effect of the marker structure 50 on the length of the second fine gate 922 can be minimized.

[0198] Furthermore, the first electrode 91 also includes a first connecting gate line 913, which is located between two adjacent first fine gates 912 and connected to the first main gate 911. The marking structure 50 is located between a second fine gate 922 that passes through two adjacent first fine gates 912 along a second preset direction and the corresponding first connecting gate line 913. The first connecting gate line 913 is disposed on the first connecting structure 203.

[0199] like Figure 5 As shown, the marker structure 50 is located on the side of the first fine gate 912 opposite to the corresponding first main gate 911 along the first preset direction F1. The distance between the center of the marker structure 50 and the first main gate 911 is greater than or equal to the distance between the marker structure 50 and the second main gate 921. Similarly, due to the arrangement of the marker structure 50, the length of the first fine gate 912 at the position corresponding to the marker structure 50 will be shortened, resulting in a weakening of the collection capability for P-type carriers at that position. However, since the distance between the center of the marker structure 50 and the first main gate 911 is greater than or equal to the distance between the marker structure 50 and the second main gate 921, the shortening of the length of the first fine gate 912 due to the arrangement of the marker structure 50 can be minimized.

[0200] Furthermore, the second electrode 92 also includes a second connecting gate line 923, which is located between two adjacent second fine gates 922 and connected to the second main gate 921. The marking structure 50 is located between the first fine gate 912, which passes between two adjacent second fine gates 922 along the second preset direction, and the corresponding second connecting gate line 923. The second connecting gate line 923 is disposed on the second connecting structure 303.

[0201] like Figure 3 , Figure 5 The marker structure 50 is configured such that grid lines for collecting charge carriers are provided on both the left and right sides of the marker structure 50, which can fully collect current and increase the collection efficiency of charge carriers.

[0202] like Figure 4 As shown, in another possible implementation, the marker structure 50 is located between the first fine gate 912 and the second fine gate 922 adjacent to each other in the second preset direction F2. Figure 4 In the example, the first fine gate 912 is above the marker structure 50, and the second fine gate 922 is below it. Figure 4 Based on this, the marking structure 50 can also have a second fine gate 922 above it and a first fine gate 912 below it.

[0203] Additionally, the first connection structure 203 can be as follows: Figure 3 The first connecting gate line 913 can be set as shown, or as... Figure 6 As shown, no metal grid lines are provided. Similarly, on the second connection structure 303, as shown... Figure 5 The second connecting grid line 923 can be set as shown, or the metal grid line can be omitted.

[0204] In addition, this application embodiment also provides a method for manufacturing a back-contact solar cell. This method can be used to manufacture the back-contact solar cell 100 as described above. That is, the back-contact solar cell 100 provided in this application embodiment can be manufactured using the following method.

[0205] Figure 7 A schematic flowchart illustrating the fabrication method of a back-contact solar cell provided in an embodiment of this application; Figure 8 A schematic diagram illustrating the formation of a first tunneling material layer, a first doped polycrystalline silicon material layer, and a first mask material layer in the fabrication method of a back contact solar cell provided in this application embodiment; Figure 9 This is a schematic diagram of patterning on one side of the first surface of the substrate in the method for fabricating a back-contact solar cell provided in the embodiments of this application; Figure 10 This is a schematic diagram illustrating the removal of the first mask material layer on the side and second side in the method for fabricating a back-contact solar cell provided in this application embodiment. Figure 11 A schematic diagram of the first polarity structure and the marking structure in the method for fabricating a back-contact solar cell provided in the embodiments of this application; Figure 12 A schematic diagram illustrating the formation of a second tunneling material layer, a second doped polycrystalline silicon material layer, and a second mask material layer in the fabrication method of a back contact solar cell provided in this application embodiment; Figure 13 This is a schematic diagram showing the marked structural positions after the formation of the second tunneling material layer, the second doped polysilicon material layer, and the second mask material layer. Figure 14 A schematic diagram of the three-dimensional structure at the marked structure position after the formation of the second tunneling material layer, the second doped polycrystalline silicon material layer and the second mask material layer; Figure 15 A schematic diagram illustrating the formation of a second mask pattern in a method for fabricating a back-contact solar cell according to an embodiment of this application; Figure 16 A schematic diagram illustrating the formation of a second polarity structure in the fabrication method of a back-contact solar cell provided in this application embodiment; Figure 17 This is a schematic diagram showing the location of the marked structure after the second polar structure has been formed; Figure 18 A schematic diagram of the three-dimensional structure at the marked structural position after the formation of the second polar structure; Figure 19 This is a schematic diagram illustrating the formation of a first passivation layer and a second passivation layer in the fabrication method of a back-contact solar cell provided in this application embodiment. Figure 13 , Figure 14 , Figure 17 , Figure 18 The images shown in the examples were obtained using optical microscopes, such as 3D microscopes.

[0206] Combination Figures 7-19 As shown, the method for fabricating a back-contact solar cell according to an embodiment of this application includes:

[0207] S10. A first polar structure 20 and a marking structure 50 are formed in the first region Y and the marking region B of the first surface F of the substrate 10, respectively. The surfaces of the first polar structure 20 and the marking structure 50 facing away from the substrate 10 are both stacked with a first mask pattern 730. The first surface F is also constructed with a second region E and an isolation region G. The first region Y and the second region E are arranged alternately along the first preset direction F1. The isolation region G is isolated between adjacent first regions Y and second regions E. The marking region B is located in the isolation region G, and the outer contour line of the marking region B is spaced apart from the outer contour line of the isolation region G.

[0208] S20, a second polar material layer 80 and a second mask material layer 83 are stacked on the side of the first mask pattern 730 opposite to the substrate 10 to form at least a layer covering the entire first surface F.

[0209] S30. Using the marking structure 50 and the first mask pattern 730, the second polar material layer 80 and the second mask material layer 83 stacked on the marking structure 50 as positioning references, the second polar material layer 80 is formed into a second polar structure 30 located in the second region E, and an insulating isolation groove 40 corresponding to the isolation region G is formed between the first polar structure 20 and the second polar structure 30.

[0210] A first polar structure 20 and a marking structure 50 are formed in the first region Y and marking region B of the first surface F of the substrate 10, respectively. A second polar structure 30 is disposed in the second region E. An insulating isolation trench 40 corresponding to the isolation region G is formed between the first polar structure 20 and the second polar structure 30, such that the first polar structure 20 is formed in the first region Y, the second polar structure 30 is formed in the second region E, the marking structure 50 is formed in the marking region B, and the insulating isolation trench 40 is formed in the isolation region G. Since the isolation region G is isolated between the adjacent first region Y and second region E, the marking region B is located in the isolation region G. Within the isolation zone G, and with the outer contour line of the marking zone B being spaced apart from the outer contour line of the isolation zone G, the marking structure 50 is disposed in the insulating isolation groove 40, and is spaced apart from both the surrounding first polar structure 20 and second polar structure 30. The marking structure 50 will form an island-like structure in the insulating isolation groove 40. Using the marking structure 50 and the first mask pattern 730, the second polar material layer 80 and the second mask material layer 83 stacked on the marking structure 50 as positioning references, the second polar material layer 80 is formed into the second polar structure 30 disposed in the second zone E. Compared to related technologies where the marker structure is formed in a P-doped or N-doped layer, and the outer contour of the marker structure is easily confused with the outer contour of the P-doped or N-doped layer, the marker structure 50, which serves as a positioning reference, and the first mask pattern 730, the second polar material layer 80, and the second mask material layer 83 stacked on the marker structure 50 do not cause confusion with the first polar structure 20 and the second polar structure 30. During the positioning process, they are not only easier to grasp, but also have higher grasping accuracy, which can further improve the yield of the back contact solar cell 100 production.

[0211] In addition, as mentioned above, in the related technologies, at the location of the marking structure 101, the electrode paste is prone to burn through the passivation layer and come into contact with the substrate, causing leakage of the PN junction, or forming a large metal composite with the substrate. Both of these situations will affect the battery efficiency.

[0212] In this embodiment, the marking structure 50 is disposed in the insulating isolation tank 40. When the first electrode 91 is fabricated on the first polarity structure 20 and the second electrode 92 is fabricated on the second polarity structure 30, the metal paste of the first electrode 91 and the second electrode 92 will not enter the insulating isolation tank 40. There is no risk of leakage as in related technologies, nor is there a problem of increased metal recombination. Therefore, compared with related technologies, the efficiency of the back contact solar cell 100 in this embodiment will be further improved.

[0213] A second polar material layer 80 and a second mask material layer 83 are stacked on the side of the first mask pattern 730 away from the substrate 10, which at least covers the entire first surface F. This means that the second polar material layer 80 and the second mask material layer 83 at least cover the entire first surface F, and may also cover the side surface C and the second surface S.

[0214] Furthermore, a first polar structure 20 and a marking structure 50 are formed in the first region Y and the marking region B of the first surface F of the substrate 10, respectively. Therefore, in the first surface F, the first polar structure 20 is formed on the first region Y, and the marking structure is formed on the marking region B. No film layer is provided on the remaining areas of the first surface F. Therefore, when a second polar material layer 80 and a second mask material layer 83 covering at least the entire first surface F are stacked on the side of the first mask pattern 730 away from the substrate 10, the film layers covering the marking region B on the first surface F are: the marking structure 50 and the first mask pattern 730, the second polar material layer 80 and the second mask material layer 83 stacked on the marking structure 50. In the isolation region G, the target region T, excluding the marker region B, is covered by a second polar material layer 80 and a second mask material layer 83. Since the outer contour line of the marker region B is spaced from the outer contour line of the isolation region G, that is, the target region T is set around the marker region B, the thickness of the film layer of the marker region B is thicker than the thickness of the film layer on the target region T around it, making the marker structure 50 easy to grasp and with high grasping accuracy.

[0215] In this application, step S30, which involves forming the second polar structure 30 and the insulating isolation groove 40, specifically includes:

[0216] Reference Figure 12 Using the marker structure 50 and the first mask pattern 730, the second polar material layer 80 and the second mask material layer 83 stacked on the marker structure 50 as positioning references, the portion of the second mask material layer 83 covering the first region Y and the isolation region G is removed.

[0217] Reference Figure 15 The second mask material layer 83 is further patterned, retaining the portion of the second mask material layer 83 corresponding to the second region E to form a second mask pattern 830. This patterning process can be, for example, a wet chemical method.

[0218] Using the second mask pattern 830 as a mask, the second polar material layer 80 is etched to form a second polar structure 30 covering the second region E, and an insulating isolation trench 40 corresponding to the isolation region G is formed between the first polar structure 20 and the second polar structure 30. Figure 16 As shown.

[0219] Furthermore, the step of removing the portion of the second mask material layer 83 that covers the first region Y and the isolation region G specifically includes:

[0220] Using the marking structure 50 and the structure formed by the first mask pattern 730 and the second polar material layer 80 and the second mask material layer 83 stacked on the marking structure 50 as a positioning reference, a laser is used to remove the portion of the second mask material layer 83 covering the first region Y and the isolation region G. As mentioned above, since the film thickness of the marking region B is thicker than the film thickness of the surrounding target region T, the marking structure 50 and the structure formed by the first mask pattern 730 and the second polar material layer 80 and the second mask material layer 83 stacked on the marking structure 50 are easily grasped.

[0221] Furthermore, a second polar material layer 80 and a second mask material layer 83 are also formed on the second surface S and the side surface C of the substrate 10.

[0222] The step of further patterning the second mask material layer 83, retaining the portion of the second mask material layer 83 corresponding to the second region E to form the second mask pattern 830, specifically includes:

[0223] The second mask material layer 83 covering the side surface C and the second surface S is partially cleaned and removed using an acidic solution.

[0224] Furthermore, the steps of forming the second polarity structure 30 and the insulating isolation groove 40 specifically include:

[0225] Combination Figure 15 and Figure 16 Using the second mask pattern 830 as a mask, the second polar material layer 80 is wet-etched with an alkaline solution to form the second polar structure 30 and the insulating isolation trench 40.

[0226] Furthermore, the step of wet etching the second polar material layer 80 using an alkaline solution with the second mask pattern 830 as a mask specifically includes:

[0227] The second polar material layer 80 covering the first region Y and the isolation region G is partially removed by an alkaline solution, and a textured structure 41 is formed on the surface of the target region T. Thus, during the formation of the first electrode 91 and the second electrode (described later), the morphological difference between the marker structure 50 and the surrounding target region T becomes more pronounced, resulting in a clearer contrast in the captured image and improved positioning accuracy.

[0228] In this embodiment of the application, step S10, which involves forming the first polar structure 20 and the marker structure 50, specifically includes:

[0229] Reference Figure 8 At least a first polar material layer 70 and a first mask material layer 73 are stacked on the first surface F of the substrate 10.

[0230] Reference Figure 9 and Figure 10 The first mask material layer 73 is patterned into a first mask pattern 730, which covers the marking area B and the first area Y.

[0231] The first polar material layer 70 is etched using the first mask pattern 730 as a mask to form the first polar structure 20 and the marker structure 50.

[0232] Furthermore, a first polar material layer 70 and a first mask material layer 73 are also formed on the second surface S and the side surface C of the substrate 10. (Refer to...) Figure 9 , Figure 10 The specific steps of patterning the first mask material layer 73 into the first mask pattern 730 include:

[0233] The portion of the first mask material layer 73 covering the second region E and the target region T is removed using a laser. The portion of the first mask material layer 73 covering the side surface C and the second surface S is then cleaned and removed using an acidic solution.

[0234] In related technologies, after the first deposition of a P-doped material layer and a mask layer on the substrate, laser film is applied to the N-region and the isolation region to form a mask pattern covering the P-region. A preset area is then treated by laser in the N-region, followed by wet etching to form a P-doped layer in the P-region. A marking structure is formed in the preset area of ​​the N-region after multiple laser treatments. Unlike the single laser treatment of the N-region and the isolation region, the laser treatment of the preset area needs to be performed slowly and multiple times to ensure that the morphology of the marking structure is clear enough after wet etching. This results in a longer laser process time, which affects the production capacity.

[0235] In this embodiment, a laser is used to remove the portion of the first mask material layer 73 covering the second region E and the target region T. An acidic solution is then used to clean and remove the portion of the first mask material layer 73 covering the side surface C and the second surface S. This allows the first mask material layer 73 covering the marking region B and the first region Y to be retained, forming a first mask pattern 730. The first polar material layer 70 is then etched using a wet chemical etching method with the first mask pattern 730 to form the marking structure 50. In this process, the laser processing only involves opening the second region E and the target region T of the first mask material layer 73, requiring only ordinary laser processing without the need for slow, multiple processes. Therefore, the laser process time can be saved, costs reduced, and production capacity increased.

[0236] In some embodiments, the step of removing the portion of the first mask material layer 73 covering the target region T using a laser specifically includes:

[0237] The isolation area G is scanned with a laser. When the laser reaches the marked area B, it is turned off for a preset time until the target area T is reached, at which point the laser is turned on again.

[0238] Furthermore, the step of stacking and forming at least a first polar material layer 70 and a first mask material layer 73 on the first surface F of the substrate 10 specifically includes:

[0239] A first tunneling material layer 71 and a first doped polysilicon material layer 72 are sequentially stacked on each surface of the substrate 10 as a first polar material layer 70. A first oxide material layer is formed on the surface of the first doped polysilicon material layer 72 facing away from the substrate 10 as a first mask material layer 73. Here, when the first doped polysilicon material layer 72 is P-type, the first oxide material layer can be BSG.

[0240] Similarly, refer to Figure 12 In step S20, the step of stacking and forming a second polar material layer 80 and a second mask material layer 83 that at least cover the entire first surface F on the side of the first mask pattern 730 opposite to the substrate 10 specifically includes:

[0241] A second tunneling material layer 81 and a second doped polysilicon material layer 82 are sequentially stacked on each side of the substrate 10 as a second polar material layer 80. A second oxide material layer is formed on the surface of the second doped polysilicon material layer 82 facing away from the substrate 10 as a second mask material layer 83. Here, when the second doped polysilicon material layer 82 is N-type, the second oxide material layer can be PSG.

[0242] In this embodiment of the application, combined with Figure 16 and Figure 19 In step S30, after forming the second polarity structure 30 and the insulating isolation trench 40, the following is also included:

[0243] Remove the first mask pattern 730 and the second mask pattern 830.

[0244] A first passivation layer 61 is formed on the side of the first polar structure 20, the second polar structure 30, and the marking structure 50 that is away from the substrate 10. The first passivation layer 61 covers the entire first surface F.

[0245] Furthermore, after the step of forming the first passivation layer 61, the method further includes:

[0246] Using the marking structure 50 and the first passivation layer 61 covering the marking structure 50 as positioning references, a first electrode 91 and a second electrode 92 are formed on the first passivation layer 61 at positions corresponding to the first polar structure 20 and the second polar structure 30, respectively. The first electrode 91 is electrically connected to the first polar structure 20, and the second electrode 92 is electrically connected to the second polar structure 30.

[0247] The following describes a specific example of a method for manufacturing a solar cell according to an embodiment of this application. The method includes:

[0248] Step 1, refer to Figure 8 The substrate 10 is cleaned. The substrate 10 includes a first surface F and a second surface S disposed opposite to each other, and also includes a side surface C adjacent to the first surface F and the second surface S. The first surface F includes a first region Y and a second region E alternately arranged along a first preset direction F1, and also includes an isolation region G isolated between the first region Y and the second region E.

[0249] Step 2, refer to Figure 8 An ultrathin tunneling layer with a thickness of 1-5 nm is prepared on the first surface F of the substrate 10 as a first tunneling material layer 71. A first doped polysilicon material layer 72 with a thickness of 100-500 nm is deposited on the surface of the first tunneling material layer 71 away from the substrate 10. The first tunneling material layer 71 and the first doped polysilicon layer 72 are used as a first polar material layer 70. Then, a first mask material layer 73 is formed on the surface of the first doped polysilicon material layer 72 away from the substrate 10. At the same time, the first tunneling material layer 71, the first doped polysilicon layer 72, and the first mask material layer 73 are also formed on the second surface S and the side surface C of the substrate 10. Specifically, the doping type of the first doped polysilicon material layer 72 is opposite to the doping type of the substrate 10. When the first doped polysilicon material layer 72 is p-type doped, the first mask material layer 73 can be borosilicate glass (BSG) or silicon oxide, etc. It is understandable that during the formation of the first doped polycrystalline silicon material layer 72, an inner diffusion layer will also be formed at the corresponding position on the substrate 10.

[0250] Step 3, refer to Figure 9 A laser device is used to pattern the surface of the first mask material layer 73 away from the substrate 10. The laser-processed area includes the second region E (corresponding to the N-type region of the back-contact solar cell) and a portion of the isolation region G, namely the target region T in the isolation region G. The unprocessed areas include the first region Y (corresponding to the P-type region of the back-contact solar cell) and the marking region B in the isolation region G corresponding to the marking structure 50. The target region T is arranged around the marking region B. There are four marking regions B, located at the four corners of the substrate 10 and symmetrically arranged with respect to the center of the substrate 10. Figure 9 Only one marked area B is shown in the diagram; the schematic diagrams of the other marked areas B are similar and will not be repeated here. The top view shape of marked area B is rectangular, square, or circular, and the target area T surrounds marked area B. Then refer to... Figure 10The first mask material layer 73 on the side surface C and the second surface S is removed by HF acid cleaning. The first mask material layer 73 on the first region Y and the marking region B is retained, and the retained first mask material layer 73 forms the first mask pattern 730.

[0251] Then refer to Figure 11 A wet chemical process is performed to completely remove the laser-treated area (second area E + target area T) on the first surface F, the first tunneling material layer 71 and the first doped polycrystalline silicon material layer 72 deposited around the side surface C and the second surface S. Simultaneously with the formation of the first polar structure 20, the first tunneling material layer 71 and the first doped polycrystalline silicon material layer 72, stacked at the position corresponding to the marking area B, are also used to form the first film layer 51 and the second film layer 52 in the marking structure 50. During this process, while the first polar structure 20 is formed at the position corresponding to the first area Y, a first internal diffusion layer 205 (not shown) is also formed in the first area Y and the marking area B.

[0252] Step 4, refer to Figure 12 An ultrathin tunneling layer with a thickness of 1-5 nm is prepared on the first surface F of the substrate as a second tunneling material layer 81. A second doped polysilicon material layer 82 with a thickness of 100-500 nm is deposited on the surface of the second tunneling material layer 81 away from the substrate 10. The second tunneling material layer 81 and the second doped polysilicon material layer 82 are used as a second polar material layer 80. Then, a second mask material layer 83 is deposited on the surface of the second doped polysilicon material layer 82 away from the substrate 10. At the same time, the second tunneling material layer 81, the second doped polysilicon material layer 82, and the second mask material layer 83 are also formed on the side surface C and the second surface S. Specifically, the doping type of the second doped polysilicon material layer 82 is the same as the doping type of the substrate 10. At this time, at the location of the marking region B, the first mask material layer 73, the second tunneling material layer 81, the second doped polysilicon material layer 82, and the second mask material layer 83 are also stacked on the marking structure 50. The morphology of the marking region B and the surrounding target region T is shown in the figure. Figure 13 , Figure 14 As shown. It is understandable that during the formation of the second doped polycrystalline silicon material layer 82, an inner diffusion layer will also be formed at the corresponding position on the substrate 10.

[0253] Step 5, refer to Figure 15 The marking structure 50 and its stacked first mask material layer 73, second tunneling material layer 81, second doped polysilicon material layer 82, and second mask material layer 83 are used for four-point positioning. The surface of the second mask material layer 83 away from the substrate 10 is patterned using a laser device. The laser-processed area is the first region Y and the isolation region G, where the width of the isolation region G is approximately 20-500 μm.

[0254] The second mask material layer 83 on the side surface C and the second surface S is removed by HF acid cleaning, and the second mask material layer 83 on the second region E is retained. The second mask material layer 83 retained here forms the second mask pattern 830.

[0255] Step 6, refer to Figure 16 A wet chemical process is performed to completely remove the laser-treated area (first region Y + isolation region G), as well as the second tunneling material layer 81 and the second doped polysilicon material layer 82 deposited around the side surface C and the second surface S, forming a second polar structure 30 covering the second region E. An insulating isolation trench 40 is formed in the isolation region G, isolating the first polar structure 20 and the second polar structure 30. Additionally, a second inner diffusion layer 304 (not shown) is formed in the second region E. Figure 2c This process will also form a first part 401 and a second part 402 at the bottom of the insulating isolation groove 40.

[0256] The surface of the isolation region G and the second surface S are cleaned using an alkaline solution to form a texturized surface structure 41. This results in the surface morphology of the isolation region G being formed into a pyramidal textured surface with micron-level random distribution. The morphology at the marker structure 50 can then be referenced... Figure 17 and Figure 18 Since the surface of the marking structure 50 is a flat surface, compared with the textured surface 41 at the bottom (target area T) of the insulating isolation groove 40, the surface of the marking structure 50 has a higher reflectivity and the bottom of the insulating isolation groove 40 has a lower reflectivity. During positioning, a more obvious morphological distinction can be obtained, and the accuracy of making electrodes using the marking structure 50 as the positioning reference will also be higher.

[0257] Of course, the surface of the isolation region G can also be a polished surface, or an uneven surface with etched pits or no polishing. In particular, after this step, the second tunneling material layer 81, the second doped polysilicon material layer 82, and the second mask material layer 83 on the surface of the marking structure 50 are removed, and only the first tunneling material layer 71, the first doped polysilicon material layer 72, and the first mask material layer 73 remain at the location of the marking region B.

[0258] Then, the first mask material layer 73 on the surface of the first polar structure 20 and the second mask material layer 83 on the surface of the second polar structure 30 are removed by cleaning with HF acid solution.

[0259] Step 7, refer to Figure 19A first passivation layer 61 is formed on the first surface F of the substrate 10. The first passivation layer 61 can be a single or composite film layer of silicon nitride, aluminum oxide, titanium oxide, silicon oxide, silicon oxynitride, etc. The second passivation layer 62 is formed on the second surface S of the substrate 10. The second passivation layer 62 can include a passivation film layer 621 and an antireflection film layer 622. The passivation film layer 621 can be a single or composite film layer of silicon nitride, aluminum oxide, titanium oxide, silicon oxide, silicon oxynitride, etc. The antireflection film layer 622 can be a single or composite film layer of silicon nitride, silicon oxynitride, etc. After this step, the first passivation layer 61 is covered on the marking structure 50 formed in the marking region B. The film layers in the marking structure 50, including the first film layer 51 and the second film layer 52, are respectively a first tunneling material layer 71 and a first doped polycrystalline silicon material layer 72, which are the same as the film layer structure in the first polar structure 20.

[0260] Step 8, Combining Figure 19 and Figure 2a Using the marker structure 50 and the first passivation layer 61 covering it as positioning references, a first electrode 91 is formed on the first passivation layer 61 at a position corresponding to the first polarity structure 20, and a second electrode 92 is formed at a position corresponding to the second polarity structure 30. The first electrode 91 passes through the first passivation layer 61 and is electrically connected to the first doped polysilicon layer 22 in the first polarity structure 20, and the second electrode 92 passes through the first passivation layer 61 and is electrically connected to the second doped polysilicon layer 32 in the second polarity structure 30. The first electrode 91 and the second electrode 92 have opposite conductivity types. This forms a structure as shown in the diagram. Figure 2a The back-contact solar cell 100 is shown.

[0261] During this process, the screen printing of the electrode paste for the first electrode 91 and the second electrode 92 can be achieved by capturing and photographing the marking structure 50 formed in step 8 and the first passivation layer 61 covering it. Specifically, because the surface of the first passivation layer 61 on the marking structure 50 is a flat surface, compared to the textured surface of the bottom of the insulating isolation trench 40 (target area T), the surface of the first passivation layer 61 has a higher reflectivity, while the target area T has a lower reflectivity. Therefore, when the camera captures the image during the screen printing process, a clearer distinction in morphology can be obtained, resulting in higher positioning accuracy. Of course, the method for forming the first electrode 91 and the second electrode 92 is not limited to screen printing and can also be other methods.

[0262] This application also provides a back-contact solar cell 100, which is manufactured using the back-contact solar cell manufacturing method described above.

[0263] This application also provides a photovoltaic module and a photovoltaic system. The photovoltaic module includes at least one battery string, and the battery string includes at least two back-contact solar cells 100 as described above, which can be connected together by string welding.

[0264] A photovoltaic (PV) system includes the aforementioned PV modules. PV systems can be applied in PV power plants, such as ground-mounted, rooftop, and floating power plants, as well as in equipment or devices that utilize solar energy for power generation, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it's understood that the application scenarios for PV systems are not limited to these; that is, PV systems can be applied in all areas that require solar energy for power generation. Taking a PV power grid as an example, a PV system can include PV arrays, combiner boxes, and inverters. A PV array can be an array combination of multiple PV modules; for example, multiple PV modules can form multiple PV arrays. The PV arrays are connected to combiner boxes, which collect the current generated by the PV arrays. The collected current flows through an inverter, converts it into AC power required by the mains grid, and then connects to the mains grid to achieve solar power supply.

[0265] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0266] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A back-contact solar cell, characterized in that, include: Substrate; Multiple first polarity structures are disposed on the first surface of the substrate; Multiple second polarity structures are disposed on the first surface of the substrate; The first polar structure and the second polar structure have opposite doping types, and the plurality of first polar structures and second polar structures are arranged alternately and at intervals along a first preset direction, with an insulating isolation trench defining the adjacent first polar structure and second polar structure. as well as A marking structure is disposed in the insulating isolation groove and is spaced apart from both the first polarity structure and the second polarity structure.

2. The back-contact solar cell according to claim 1, characterized in that, The bottom of the insulating isolation trench includes a first part and a second part. The first part extends along the thickness direction of the substrate to the first surface, and the second part protrudes along the thickness direction of the substrate in a direction away from the substrate relative to the first surface. The second part forms the marking structure.

3. The back-contact solar cell according to claim 2, characterized in that, The reflectivity of the surface of the marking structure facing away from the substrate is different from the reflectivity of the surface of the first portion.

4. The back-contact solar cell according to claim 3, characterized in that, The reflectivity of the surface of the marking structure facing away from the substrate is greater than the reflectivity of the surface of the first portion.

5. The back-contact solar cell according to claim 4, characterized in that, The surface of the marking structure facing away from the substrate is constructed as a polished surface; At least a portion of the surface of the first part has a velvety texture.

6. The back-contact solar cell according to claim 3, characterized in that, The average roughness of the surface of the marking structure away from the substrate is less than the average roughness of the surface of the first portion.

7. The back-contact solar cell according to claim 2, characterized in that, The marking structure includes at least a doped layer identical to that of the first polar structure; or... The marking structure includes at least one doped layer identical to that of the second polar structure.

8. The back-contact solar cell according to claim 7, characterized in that, The first polar structure includes a first tunneling oxide layer and a first doped polysilicon layer stacked on the first surface; The marking structure includes a first film layer and a second film layer stacked on the first surface. The first film layer is made of the same material as the first tunneling oxide layer, and the second film layer is made of the same material as the first doped polysilicon layer.

9. The back-contact solar cell according to claim 7, characterized in that, The second polar structure includes a second tunneling oxide layer and a second doped polysilicon layer stacked on the first surface; The marking structure includes a first film layer and a second film layer stacked on the first surface. The first film layer is made of the same material as the second tunneling oxide layer, and the second film layer is made of the same material as the second doped polysilicon layer.

10. The back-contact solar cell according to claim 2, characterized in that, The membrane structure of the marker structure is different from the membrane structure of the first polar structure or the second polar structure.

11. The back-contact solar cell according to any one of claims 1-10, characterized in that, The cross-sectional profile of the marking structure is circular, annular, or polygonal; or... The cross-sectional profile of the marking structure includes at least two intersecting strip patterns.

12. The back-contact solar cell according to claim 11, characterized in that, When the cross-sectional outline of the marking structure is a polygon, the side length of the cross-sectional outline is 50μm-950μm.

13. The back-contact solar cell according to any one of claims 1-10, characterized in that, The back contact solar cell also includes a first passivation layer; The first passivation layer is disposed on the surfaces of the first polar structure and the second polar structure opposite to the substrate, and covers the marking structure.

14. The back-contact solar cell according to any one of claims 1-10, characterized in that, The interval between the marker structure and the first polar structure is greater than 20 μm, and the interval between the marker structure and the second polar structure is greater than 20 μm.

15. The back-contact solar cell according to any one of claims 1-10, characterized in that, The first surface of the substrate is provided with a first inner diffusion layer and a second inner diffusion layer. The doping element type of the first inner diffusion layer is the same as that of the first polar structure, and the doping element type of the second inner diffusion layer is the same as that of the second polar structure. The first inner diffusion layer is located at a position corresponding to the first polar structure and the marking structure, and the second inner diffusion layer is located at a position corresponding to the second polar structure.

16. The back-contact solar cell according to claim 15, characterized in that, The thickness of the first inner diffusion layer is greater than the thickness of the second inner diffusion layer.

17. The back-contact solar cell according to claim 15, characterized in that, The thickness of the first inner diffusion layer is 50nm-200nm, and the thickness of the second inner diffusion layer is 20nm-100nm.

18. The back-contact solar cell according to any one of claims 1-10, characterized in that, The back-contact solar cell further includes a first electrode and a second electrode; The first electrode is disposed on the side of the first polar structure opposite to the substrate and is electrically connected to the doped layer in the first polar structure. The second electrode is disposed on the side of the second polar structure opposite to the substrate and is electrically connected to the doped layer in the second polar structure.

19. The back-contact solar cell according to claim 18, characterized in that, The first polar structure includes a first main structure and a first finger structure, and the second polar structure includes a second main structure and a second finger structure; The first main structure of the first polarity structure and the second main structure of the second polarity structure are arranged alternately and at intervals along the first preset direction; Each first main structure is connected to at least two first finger-shaped structures spaced apart in a second preset direction, and each second main structure is connected to at least two second finger-shaped structures spaced apart in a second preset direction; wherein the first preset direction and the second preset direction intersect and are both perpendicular to the thickness direction of the back contact solar cell. The first finger-like structures and the second finger-like structures located between two adjacent first main structures and second main structures are interlaced with each other in a forked manner along the first preset direction. The marking structure is located in the region between the interleaved first and second finger structures.

20. The back-contact solar cell according to claim 19, characterized in that, The marking structure is located between the first finger structure and the second finger structure, which are adjacent to each other in the second preset direction.

21. The back-contact solar cell according to claim 19, characterized in that, The first finger structure and the second finger structure located between two adjacent first main structures and second main structures are arranged alternately along the second preset direction; The marking structure is located on the side of the first finger structure away from the corresponding first main structure along the first preset direction; or The marking structure is located on the side of the second finger structure away from the corresponding second main structure along the first preset direction.

22. The back-contact solar cell according to claim 21, characterized in that, The marking structure is located on the side of the second finger structure away from the corresponding second main structure along the first preset direction; The first polar structure further includes a first connecting structure, in which two adjacent first finger structures in the second preset direction are connected by the first connecting structure; The marking structure is located between the second finger structure, which is inserted between two adjacent first finger structures along the second preset direction, and the corresponding first connecting structure.

23. The back-contact solar cell according to claim 21, characterized in that, The marking structure is located on the side of the first finger structure away from the corresponding first main structure along the first preset direction; the second polar structure further includes a second connecting structure, in which two adjacent second finger structures in the second preset direction are connected by the second connecting structure; The marking structure is located between the first finger structure, which is inserted between two adjacent second finger structures along the second preset direction, and the corresponding second connecting structure.

24. The back-contact solar cell according to claim 22, characterized in that, The first electrode includes a plurality of first main gates and a first fine gate electrically connected to the first main gates; the second electrode includes a plurality of second main gates and a second fine gate electrically connected to the second main gates. The first main structure and the first finger structure are respectively provided with the first main gate and the first fine gate; the second main structure and the second finger structure are respectively provided with the second main gate and the second fine gate.

25. The back-contact solar cell according to claim 18, characterized in that, The first electrode includes a plurality of first main gates and a first fine gate, and the second electrode includes a plurality of second main gates and a second fine gate; Multiple first main gates and multiple second main gates are arranged alternately and at intervals along the first preset direction; Each first main grid is connected to at least two first fine grids arranged at intervals in a second preset direction, and each second main grid is connected to at least two second fine grids arranged at intervals in a second preset direction; wherein the first preset direction and the second preset direction intersect and are both perpendicular to the thickness direction of the back contact solar cell; The first and second fine grids located between two adjacent first and second main grids are arranged in an interlacing pattern along the first preset direction; The marking structure is located in the region between the interleaved first and second fine grids.

26. The back-contact solar cell according to claim 25, characterized in that, The marking structure is located between the first and second fine grids, which are adjacent to each other in the second preset direction.

27. The back-contact solar cell according to claim 25, characterized in that, The first and second fine grids located between two adjacent first and second main grids are arranged alternately along the second preset direction; The marking structure is located on the side of the first fine grid opposite to the corresponding first main grid along the first preset direction, and the distance between the center of the marking structure and the first main grid is greater than or equal to the distance between the marking structure and the second main grid. or The marking structure is located on the side of the second fine grid opposite to the corresponding second main grid along the first preset direction, and the distance between the center of the marking structure and the second main grid is greater than or equal to the distance between the marking structure and the first main grid.

28. The back-contact solar cell according to claim 27, characterized in that, Both the first fine grid and the second fine grid extend along a first preset direction; The marking structure is located on the side of the second fine grid that is opposite to the corresponding second main grid along the first preset direction; The first electrode further includes a first connecting gate line, which is located between two adjacent first fine gates. The marking structure is located between the second fine gate, which is inserted between two adjacent first fine gates along the second preset direction, and the corresponding first connecting gate line.

29. The back-contact solar cell according to claim 27, characterized in that, The marking structure is located on the side of the first fine grid that is opposite to the corresponding first main grid along the first preset direction; The second electrode further includes a second connecting gate line, which is located between two adjacent second fine gates. The marking structure is located between the first fine gate, which is inserted between two adjacent second fine gates along the second preset direction, and the corresponding second connecting gate line.

30. A method for manufacturing a back-contact solar cell, characterized in that, include: A first polar structure and a marking structure are formed in a first region and a marking region on a first side of a substrate, respectively. A first mask pattern is stacked on the surface of the first polar structure and the marking structure facing away from the substrate. The first side is also constructed with a second region and an isolation region. The first region and the second region are arranged alternately along a first preset direction. The isolation region is isolated between adjacent first regions and second regions. The marking region is located in the isolation region, and the outer contour line of the marking region is spaced apart from the outer contour line of the isolation region. A second polar material layer and a second mask material layer are stacked on the side of the first mask pattern opposite to the substrate to form at least a layer covering the entire first surface; Using the marking structure and the first mask pattern, the second polar material layer and the second mask material layer stacked on the marking structure as positioning references, the second polar material layer is formed into a second polar structure disposed in the second region, and an insulating isolation groove corresponding to the isolation region is formed between the first polar structure and the second polar structure.

31. The method for manufacturing a back-contact solar cell according to claim 30, characterized in that, The steps of forming the second polarity structure and the insulating isolation groove specifically include: Using the marking structure and the first mask pattern, the second polar material layer and the second mask material layer stacked on the marking structure as positioning references, the portion of the second mask material layer covering the first area and the isolation area is removed; The second mask material layer is further patterned, and the portion of the second mask material layer corresponding to the second region is retained to form a second mask pattern; Using the second mask pattern as a mask, the second polar material layer is etched to form a second polar structure covering the second region, and an insulating isolation trench corresponding to the isolation region is formed between the first polar structure and the second polar structure.

32. The method for manufacturing a back-contact solar cell according to claim 31, characterized in that, The step of removing the portion of the second mask material layer that covers the first region and the isolation region specifically includes: By using the marking structure and the structure formed by the first mask pattern, the second polar material layer and the second mask material layer stacked on the marking structure as a positioning reference, a laser is used to remove the portion of the second mask material layer that covers the first area and the isolation area.

33. The method for manufacturing a back-contact solar cell according to claim 31, characterized in that, The second polar material layer and the second mask material layer are also formed on the second side and the side surface of the substrate, wherein the second side is disposed opposite to the first side, and the side surface is adjacent to the first side and the second side; The step of further patterning the second mask material layer, retaining the portion of the second mask material layer corresponding to the second region to form the second mask pattern, specifically includes: The second mask material layer covering the side surface and the second face is partially removed by cleaning with an acidic solution.

34. The method for manufacturing a back-contact solar cell according to claim 31, characterized in that, The steps of forming the second polarity structure and the insulating isolation groove specifically include: Using the second mask pattern as a mask, the second polar material layer is wet-etched with an alkaline solution to form the second polar structure and the insulating isolation trench.

35. The method for manufacturing a back-contact solar cell according to claim 34, characterized in that, The portion of the isolation zone outside the marked area is defined as the target area; The step of using the second mask pattern as a mask to perform wet etching of the second polar material layer with an alkaline solution specifically includes: The alkaline solution is used to remove the portion of the second polar material layer covering the first region and the isolation region, and a velvety structure is formed on the surface of the target region.

36. The method for manufacturing a back-contact solar cell according to claim 30, characterized in that, The steps of forming the first polar structure and the marker structure specifically include: A first polar material layer and a first mask material layer are stacked on at least the first surface of the substrate; The first mask material layer is patterned into the first mask pattern, and the first mask pattern covers the marking area and the first area; The first polar material layer is etched using the first mask pattern as a mask to form the first polar structure and the marking structure.

37. The method for manufacturing a back-contact solar cell according to claim 36, characterized in that, The first polar material layer and the first mask material layer are also formed on the second side and the side surface of the substrate, wherein the second side is disposed opposite to the first side, and the side surface is adjacent to the first side and the second side, and the portion outside the marked area in the isolation area is defined as the target area; The step of patterning the first mask material layer into the first mask pattern specifically includes: The portion of the first mask material layer covering the second region and the target region is removed using a laser; The first mask material layer covering the side and the second surface is partially removed by cleaning with an acidic solution.

38. The method for manufacturing a back-contact solar cell according to claim 37, characterized in that, The step of using a laser to remove the portion of the first mask material layer covering the target area specifically includes: The isolation area is scanned using a laser. When the marked area is scanned, the laser is turned off for a preset time until the target area is scanned, at which point the laser is turned on.

39. The method for manufacturing a back-contact solar cell according to claim 36, characterized in that, The step of stacking at least a first polar material layer and a first mask material layer on the first surface of the substrate specifically includes: A first tunneling material layer and a first doped polycrystalline silicon material layer are sequentially stacked on each surface of the substrate as the first polar material layer, and a first oxide material layer is formed on the surface of the first doped polycrystalline silicon material layer opposite to the substrate as the first mask material layer.

40. The method for manufacturing a back-contact solar cell according to claim 30, characterized in that, The step of stacking a second polar material layer and a second mask material layer on the side of the first mask pattern opposite to the substrate specifically includes: A second tunneling material layer and a second doped polysilicon material layer are sequentially stacked on each side of the substrate as the second polar material layer, and a second oxide material layer is formed on the surface of the second doped polysilicon material layer opposite to the substrate as the second mask material layer.

41. The method for manufacturing a back-contact solar cell according to any one of claims 30-40, characterized in that, The portion of the isolation zone outside the marked area is defined as the target area, and the surface of the target area is formed with a velvety structure. The step of forming the second polar structure and the insulating isolation groove further includes: Remove the first mask pattern and the second mask material layer covering the second polar structure layer; A first passivation layer is formed on the side of the first polar structure, the second polar structure, and the marking structure opposite to the substrate, and the first passivation layer covers the entire first surface.

42. The method for manufacturing a back-contact solar cell according to claim 41, characterized in that, Following the step of forming the first passivation layer, the method further includes: Using the marking structure and the first passivation layer covering the marking structure as positioning references, a first electrode and a second electrode are formed on the first passivation layer at positions corresponding to the first polar structure and the second polar structure, respectively; wherein, the first electrode is electrically connected to the first polar structure, and the second electrode is electrically connected to the second polar structure.

43. A back-contact solar cell, characterized in that, It is manufactured using the method for manufacturing a back-contact solar cell as described in any one of claims 30-42.

44. A photovoltaic module, characterized in that, It includes at least one battery string, said battery string comprising at least two back-contact solar cells as described in any one of claims 1-29, 43.

Images