Solar cell contact structure, solar cell and preparation method

Abstract

The invention relates to a solar cell contact structure, a solar cell and a preparation method. The solar cell contact structure comprises a substrate, a first doping layer, a second doping layer and a third doping layer, the first doping layer and the second doping layer are arranged on the back surface of the substrate at an interval, and the doping type of the first doping layer is opposite to that of the second doping layer; the third doping layer is arranged on the surface, away from the substrate, of the first doping layer, and the doping type of the third doping layer is the same as that of the first doping layer; in the thickness direction of the substrate, the surface, away from the substrate, of the third doped layer protrudes out of the second doped layer. According to the solar cell contact structure, the risk that the doping layer is scratched in the conveying process can be reduced, and the production yield of the solar cell can be improved.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular, to a solar cell contact structure, a solar cell, and a preparation method. Background Art

[0002] In the structure of a solar cell, arranging the grid lines on the back of the cell can reduce the optical loss caused by grid line shading to the cell, and thus is beneficial to improving the photoelectric conversion efficiency of the solar cell. To match the arrangement of the grid lines on the back of the cell, doping layers of different doping types will correspondingly be arranged on the back of the cell substrate. At this time, when transporting the cell product, transport media such as conveyor belts, graphite boats, and suction cups may scratch the surface of the doping layer, thereby reducing the production yield of the solar cell. Summary of the Invention

[0003] Based on this, it is necessary to provide a solar cell contact structure, a solar cell, and a preparation method. The solar cell contact structure can reduce the risk of the doping layer being scratched during the transportation process, which is beneficial to improving the production yield of the solar cell.

[0004] A solar cell contact structure includes a substrate, a first doping layer, a second doping layer, and a third doping layer; the first doping layer and the second doping layer are spaced apart and arranged on the back of the substrate, and the doping type of the first doping layer is opposite to that of the second doping layer; the third doping layer is arranged on the surface of the first doping layer away from the substrate, and the doping type of the third doping layer is the same as that of the first doping layer; in the thickness direction of the substrate, the surface of the third doping layer away from the substrate protrudes from the second doping layer.

[0005] In the above solar cell contact structure, the first doping layer and the second doping layer with opposite doping types are spaced apart to form a basic structure for carrier transport. The third doping layer is located on the surface of the first doping layer away from the substrate, and in the thickness direction of the substrate, the surface of the third doping layer protrudes from the second doping layer. At this time, a height difference can be formed between the third doping layer and the second doping layer. During the transportation of the solar cell contact structure, the third doping layer can contact the transport medium so that the second doping layer can be in a suspended state, which can reduce the contact between the second doping layer and the transport medium, and thus can reduce the risk of the second doping layer being scratched by the transport medium. In addition, the third doping layer is located on the surface of the first doping layer, and the third doping layer can protect the first doping layer, reducing the risk of the first doping layer contacting the transport medium, and thus can reduce the risk of the first doping layer being scratched by the transport medium.

[0006] In some embodiments, the doping concentration of the doping element in the third doping layer is greater than that of the doping element in the first doping layer.

[0007] In some embodiments, the doping concentration of the doping element in the third doping layer ≥ 1×10 20 / cm 3 .

[0008] In some embodiments, the doping element in the first doping layer includes a P-type doping element, and the doping element in the second doping layer includes an N-type doping element.

[0009] In some embodiments, in the thickness direction of the substrate, the height of the surface of the third doping layer away from the substrate protruding from the second doping layer is 0.1 μm to 10 μm.

[0010] In some embodiments, isolation grooves are provided on the substrate, and the isolation grooves are located between the first doping layer and the second doping layer so that the first doping layer and the second doping layer are spaced apart.

[0011] In some embodiments, the height of the surface of the first doping layer away from the substrate from the bottom of the isolation groove is 0.1 μm to 10 μm.

[0012] In some embodiments, the height of the surface of the second doping layer away from the substrate from the bottom of the isolation groove is 0.1 μm to 10 μm.

[0013] In some embodiments, the solar cell contact structure further includes a first dielectric layer, and the first dielectric layer is located between the first doping layer and the substrate.

[0014] In some embodiments, the solar cell further includes a second dielectric layer, and the second dielectric layer is located between the second doping layer and the substrate.

[0015] A solar cell includes a first electrode, a second electrode, and the solar cell contact structure; the first electrode penetrates through the third doping layer and contacts the first doping layer, and the second electrode contacts the second doping layer.

[0016] A method for preparing a solar cell contact structure includes the following steps:

[0017] Prepare a first doping layer and a third doping layer on the back surface of the substrate, the third doping layer is disposed on the surface of the first doping layer away from the substrate, and the doping type of the third doping layer is the same as the doping type of the first doping layer, to prepare a battery preform;

[0018] Remove the first doping layer and the third doping layer in a preset area on the battery preform;

[0019] Prepare a second doped layer in the preset region, where the doping type of the second doped layer is opposite to that of the first doped layer. The second doped layer and the first doped layer are arranged at intervals, and in the thickness direction of the substrate, the surface of the third doped layer protrudes from the second doped layer.

[0020] A method for preparing a solar cell includes the following steps:

[0021] Prepare a solar cell contact structure by using the method for preparing the solar cell contact structure;

[0022] Prepare a first electrode and a second electrode on the solar cell contact structure. The first electrode penetrates through the third doped layer and contacts the first doped layer, and the second electrode contacts the second doped layer. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of a solar cell contact structure in an embodiment of the present application.

[0024] Figure 2 It is a schematic structural diagram of a solar cell contact structure in another embodiment of the present application.

[0025] Figure 3 It is a schematic structural diagram of a solar cell in an embodiment of the present application.

[0026] Figure 4 It is a schematic structural diagram of a solar cell in another embodiment of the present application.

[0027] Figures 5 to 8 It is a schematic structural diagram of a product corresponding to a corresponding step in the method for preparing a solar cell in an embodiment of the present application.

[0028] Marking description in the figure:

[0029] 10. Solar cell contact structure; 101. Substrate; 1011. Isolation groove; 102. First doped layer; 103. Second doped layer; 104. Third doped layer; 105. First dielectric layer; 106. Second dielectric layer; 107. Passivation layer; 20. Solar cell; 201. First electrode; 202. Second electrode; 203. Antireflection layer; 30. Borosilicate glass layer; 40. Phosphosilicate glass layer; 50. Oxide layer; 60. Textured surface. Detailed Embodiments

[0030] To make the above objects, features, and advantages of the present application more apparent and understandable, the following provides a detailed description of the specific implementation manners of the present application. Many specific details are set forth in the following description to facilitate a thorough understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0031] In the present application, unless otherwise clearly defined and limited, terms such as "installed", "connected", "coupled", "fixed", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0032] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" can explicitly or implicitly include at least one of such features. In the description of the present application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0034] Please refer to Figure 1 , an embodiment of the present application provides a solar cell contact structure 10. The solar cell contact structure 10 includes a substrate 101, a first doping layer 102, a second doping layer 103, and a third doping layer 104. The first doping layer 102 and the second doping layer 103 are disposed at intervals on the back surface of the substrate 101, and the doping types of the first doping layer 102 and the second doping layer 103 are opposite. The third doping layer 104 is disposed on the surface of the first doping layer 102 away from the substrate 101, and the doping type of the third doping layer 104 is the same as that of the first doping layer 102. In the thickness direction of the substrate 101, the surface of the third doping layer 104 protrudes from the second doping layer 103.

[0035] In the solar cell contact structure 10 of this embodiment, a first doped layer 102 and a second doped layer 103 with opposite doping types are arranged at intervals to form a basic structure for carrier transport. A third doped layer 104 is located on the surface of the first doped layer 102 away from the substrate 101, and in the thickness direction of the substrate 101, the surface of the third doped layer 104 protrudes from the second doped layer 103. At this time, a height difference can be formed between the third doped layer 104 and the second doped layer 103. During the transfer process of the solar cell contact structure 10, the third doped layer 104 can contact the transfer medium, enabling the second doped layer 103 to be in a suspended state. In this way, the contact between the second doped layer 103 and the transfer medium can be reduced, thereby reducing the risk of the second doped layer 103 being scratched by the transfer medium. In addition, since the third doped layer 104 is located on the surface of the first doped layer 102, the third doped layer 104 can protect the first doped layer 102, reducing the risk of the first doped layer 102 contacting the transfer medium and further reducing the risk of the first doped layer 102 being scratched by the transfer medium.

[0036] It can be understood that the substrate 101 has a front side facing the sun during normal operation and a back side opposite to the front side. That is, the front side of the substrate 101 is the light-receiving surface, and the surface opposite to the front side is the back side. By arranging both the first doped layer 102 and the second doped layer 103 on the back side of the substrate 101, a back contact structure can be obtained. In the subsequent structure of the solar cell 20, the grid lines can also be located on the back side of the substrate 101, thereby reducing the optical loss caused by grid line occlusion to the cell and being beneficial to improving the photoelectric conversion efficiency of the solar cell 20. Optionally, the substrate 101 includes a silicon substrate. Further, the substrate 101 can be a single-crystalline silicon substrate or a polycrystalline silicon substrate. Still further, the silicon substrate 101 can be an N-type silicon substrate or a P-type silicon substrate.

[0037] In some embodiments, the doping concentration of the doping element in the third doped layer 104 is greater than the doping concentration of the doping element in the first doped layer 102. When the doping concentration of the doping element in the third doped layer 104 is relatively high, the third doped layer 104 can have a good gettering effect, which is beneficial to further improving the photoelectric conversion efficiency of the solar cell 20. In addition, when the doping concentration of the doping element in the third doped layer 104 is relatively high, the loss of current transmission in the solar cell 20 can be further reduced, thereby improving the photoelectric conversion efficiency of the solar cell 20.

[0038] In some embodiments, the doping concentration of the doping element in the third doped layer 104 ≥ 1×10 20 / cm 3 . Optionally, the doping concentration of the doping element in the third doped layer 104 is 1.1×10 20 / cm 3 、1.2×1020 / cm 3 、1.3×10 20 / cm 3 、1.4×10 20 / cm 3 、1.5×10 20 / cm 3 、1.6×10 20 / cm 3 、1.7×10 20 / cm 3 、1.8×10 20 / cm 3 、1.9×10 20 / cm 3 、1×10 21 / cm 3 etc.

[0039] Optionally, the doping concentration of the doping element in the first doping layer 102 is 1×10 19 / cm 3 ~2×10 20 / cm 3 . For example, the doping concentration of the doping element in the first doping layer 102 can be 1×10 19 / cm 3 、2×10 19 / cm 3 、3×10 19 / cm 3 、4×10 19 / cm 3 、5×10 19 / cm 3 、6×10 19 / cm 3 、7×10 19 / cm 3 、8×10 19 / cm 3 、9×10 19 / cm 3 、1×10 20 / cm 3 、1.5×10 20 / cm 3 etc.

[0040] Optionally, the doping concentration of the doping element in the second doping layer 103 is 1×10 20 / cm 3 ~1×10 21 / cm 3 . For example, the doping concentration of the doping element in the second doping layer 103 can be 1×10 20 / cm3 , 2×10 20 / cm 3 , 3×10 20 / cm 3 , 4×10 20 / cm 3 , 5×10 20 / cm 3 , 6×10 20 / cm 3 , 7×10 20 / cm 3 , 8×10 20 / cm 3 , 9×10 20 / cm 3 , 1×10 21 / cm 3 etc.

[0041] Further optionally, the doping element in the first doping layer 102 includes a P-type doping element, and the doping element in the second doping layer 103 includes an N-type doping element. For example, the doping element in the first doping layer 102 includes an element of Group IIIA. The doping element in the second doping layer 103 includes an element of Group VA. Optionally, the doping element in the first doping layer 102 includes at least one of boron, aluminum, gallium, and indium. The doping element in the second doping layer 103 includes at least one of nitrogen, phosphorus, and arsenic.

[0042] In some embodiments, in the thickness direction of the substrate 101, the height by which the surface of the third doping layer 104 away from the substrate 101 protrudes from the second doping layer 103 is 0.1 μm to 10 μm. The height by which the surface of the third doping layer 104 away from the substrate 101 protrudes from the second doping layer 103 within this range can provide good protection for the second doping layer 103. Please refer to Figure 1 , in which the height H by which the surface of the third doping layer 104 away from the substrate 101 protrudes from the second doping layer 103 is schematically shown, and H is 0.1 μm to 10 μm. Optionally, the height by which the surface of the third doping layer 104 away from the substrate 101 protrudes from the second doping layer 103 can be 0.2 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, etc.

[0043] In some embodiments, the third doping layer 104 is disposed on the surface of the first doping layer 102 away from the substrate 101, and the third doping layer 104 is not provided on the surface of the second doping layer 103 away from the substrate 101.

[0044] In some embodiments, an isolation groove 1011 is provided on the substrate 101. The isolation groove 1011 is located between the first doped layer 102 and the second doped layer 103 so that the first doped layer 102 and the second doped layer 103 are arranged at intervals. By providing the isolation groove 1011, the first doped layer 102 and the second doped layer 103 can be better separated, reducing the risk of an increase in leakage current caused by the contact between the first doped layer 102 and the second doped layer 103. It can be understood that the isolation groove 1011 can be obtained on the substrate 101 by etching.

[0045] In some embodiments, the height from the surface of the first doped layer 102 away from the substrate 101 to the bottom of the isolation groove 1011 is 0.1 μm to 10 μm. Optionally, the height from the surface of the first doped layer 102 away from the substrate 101 to the bottom of the isolation groove 1011 can be 0.2 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, etc.

[0046] In some embodiments, the height from the surface of the second doped layer 103 away from the substrate 101 to the bottom of the isolation groove 1011 is 0.1 μm to 10 μm. Optionally, the height from the surface of the second doped layer 103 away from the substrate 101 to the bottom of the isolation groove 1011 can be 0.2 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, etc.

[0047] Optionally, the height from the surface of the first doped layer 102 away from the substrate 101 to the bottom of the isolation groove 1011 is greater than the height from the surface of the second doped layer 103 away from the substrate 101 to the bottom of the isolation groove 1011.

[0048] Please refer to Figure 2 , in some embodiments, the solar cell contact structure 10 further includes a first dielectric layer 105. The first dielectric layer 105 is located between the first doped layer 102 and the substrate 101. Optionally, the material of the first dielectric layer 105 includes at least one of silicon oxide, aluminum oxide, silicon carbide, silicon oxynitride, and silicon carbonitride. Optionally, the thickness of the first dielectric layer 105 is 0.5 nm to 3 nm. For example, the thickness of the first dielectric layer 105 can be 0.5 nm, 0.8 nm, 1 nm, 1.2 nm, 1.5 nm, 1.8 nm, 2 nm, 2.2 nm, 2.5 nm, 2.8 nm, 3 nm, etc.

[0049] In some embodiments, the solar cell contact structure 10 further includes a second dielectric layer 106, and the second dielectric layer 106 is located between the second doped layer 103 and the substrate 101. Optionally, the material of the second dielectric layer 106 includes at least one of silicon oxide, aluminum oxide, silicon carbide, silicon oxynitride, and silicon carbonitride. Optionally, the thickness of the second dielectric layer 106 is 0.5 nm to 3 nm. For example, the thickness of the second dielectric layer 106 can be 0.5 nm, 0.8 nm, 1 nm, 1.2 nm, 1.5 nm, 1.8 nm, 2 nm, 2.2 nm, 2.5 nm, 2.8 nm, 3 nm, etc.

[0050] Please refer to again Figure 2 , in some embodiments, the solar cell contact structure 10 further includes a passivation layer 107, and the passivation layer 107 covers the surfaces of the third doped layer 104, the isolation groove 1011, and the second doped layer 103. Optionally, the material of the passivation layer 107 includes at least one of silicon nitride, aluminum oxide, silicon oxynitride, and silicon oxide.

[0051] It can be understood that when the solar cell contact structure 10 includes the passivation layer 107, the height of the surface of the first doped layer 102 away from the substrate 101 from the bottom of the isolation groove 1011 represents the height of the surface of the first doped layer 102 away from the substrate 101 from the surface of the passivation layer 107 at the bottom of the isolation groove 1011. The height of the surface of the second doped layer 103 away from the substrate 101 from the bottom of the isolation groove 1011 represents the height of the surface of the second doped layer 103 away from the substrate 101 from the surface of the passivation layer 107 at the bottom of the isolation groove 1011.

[0052] Please refer to Figure 3 , an embodiment of the present application provides a solar cell 20. The solar cell 20 includes a first electrode 201, a second electrode 202, and the above-mentioned solar cell contact structure 10. The first electrode 201 penetrates through the third doped layer 104 and contacts the first doped layer 102, and the second electrode 202 contacts the second doped layer 103.

[0053] Optionally, the material of the first electrode 201 includes at least one of silver, aluminum, and copper. The material of the second electrode 202 includes at least one of silver, aluminum, and copper.

[0054] It can be understood that when the first electrode 201 contacts the first doped layer 102, the first electrode 201 can contact the first doped layer 102 on the surface of the first doped layer 102, or penetrate into the interior of the first doped layer 102 to contact the first doped layer 102. When the second electrode 202 contacts the second doped layer 103, the second electrode 202 can contact the second doped layer 103 on the surface of the second doped layer 103, or penetrate into the interior of the second doped layer 103 to contact the second doped layer 103.

[0055] It can be understood that Figure 3 in the solar cell 20 shown, the solar cell contact structure 10 has Figure 1 the structure shown. That is Figure 3 in the solar cell 20 shown, the solar cell contact structure 10 includes a substrate 101, a first doping layer 102, a second doping layer 103, and a third doping layer 104; the first doping layer 102 and the second doping layer 103 are disposed at intervals on the back surface of the substrate 101, and the doping type of the first doping layer 102 is opposite to that of the second doping layer 103. The third doping layer 104 is disposed on the surface of the first doping layer 102 away from the substrate 101, and the doping type of the third doping layer 104 is the same as that of the first doping layer 102. In the thickness direction of the substrate 101, the surface of the third doping layer 104 protrudes from the second doping layer 103.

[0056] It can also be understood that the first electrode 201 and the second electrode 202 can be obtained by screen printing.

[0057] It can also be understood that Figure 3 in the solar cell 20 shown, the textured surface 60 on the front surface of the substrate 101 can be obtained by a texturing process.

[0058] Please refer to Figure 4 , in some embodiments, the solar cell 20 further includes an antireflection layer 203, and the antireflection layer 203 is disposed on the front surface of the substrate 101. It can be understood that by providing the antireflection layer 203, the sunlight reflected by the battery can be reduced, so that the battery absorbs more sunlight, which is beneficial to improving the photoelectric conversion efficiency of the battery. Optionally, the material of the antireflection layer 203 includes at least one of silicon nitride, aluminum oxide, silicon oxynitride, and silicon oxide. It can also be understood that the antireflection layer 203 can be prepared by a coating method.

[0059] It can be understood that Figure 4In the solar cell 20 shown, the solar cell 20 includes a first electrode 201, a second electrode 202, and a solar cell contact structure 10. The solar cell contact structure 10 includes a substrate 101, a first doped layer 102, a second doped layer 103, a third doped layer 104, a first dielectric layer 105, a second dielectric layer 106, and a passivation layer 107. Among them, isolation grooves 1011 are provided on the substrate 101, and the isolation grooves 1011 are located between the first doped layer 102 and the second doped layer 103 so that the first doped layer 102 and the second doped layer 103 are spaced apart. The first doped layer 102 and the second doped layer 103 are spaced apart and disposed on the back surface of the substrate 101, and the doping type of the first doped layer 102 is opposite to the doping type of the second doped layer 103. The third doped layer 104 is disposed on the surface of the first doped layer 102 away from the substrate 101, and the doping type of the third doped layer 104 is the same as the doping type of the first doped layer 102. In the thickness direction of the substrate 101, the surface of the third doped layer 104 protrudes from the second doped layer 103. The first dielectric layer 105 is located between the first doped layer 102 and the substrate 101. The second dielectric layer 106 is located between the second doped layer 103 and the substrate 101. The passivation layer 107 covers the surfaces of the third doped layer 104, the isolation grooves 1011, and the second doped layer 103.

[0060] Another embodiment of the present application provides a method for manufacturing a solar cell contact structure 10. The method for manufacturing the solar cell contact structure 10 includes the following steps: preparing the first doped layer 102 and the third doped layer 104 on the back surface of the substrate 101, the third doped layer 104 being disposed on the surface of the first doped layer 102 away from the substrate 101, and the doping type of the third doped layer 104 being the same as the doping type of the first doped layer 102, to prepare a battery preform. Removing the first doped layer 102 and the third doped layer 104 in a preset area on the battery preform. Preparing the second doped layer 103 in the preset area, the doping type of the second doped layer 103 being opposite to the doping type of the first doped layer 102, the second doped layer 103 and the first doped layer 102 being spaced apart, and in the thickness direction of the substrate 101, the surface of the third doped layer 104 protruding from the second doped layer 103.

[0061] It can be understood that in the method for manufacturing the solar cell contact structure 10 of this embodiment, the preset area includes the area for forming the second doped layer 103.

[0062] It can also be understood that when isolation grooves 1011 are provided on the substrate 101, the preset area may further include the area for forming the isolation grooves 1011.

[0063] In some embodiments, before preparing the first doped layer 102 and the third doped layer 104 on the back surface of the substrate 101, it further includes: preparing a first dielectric layer 105 on the back surface of the substrate 101. Preparing the first doped layer 102 after preparing the first dielectric layer 105 can make the first dielectric layer 105 located between the substrate 101 and the first doped layer 102. Optionally, the first dielectric layer 105 can be prepared by low-pressure chemical vapor deposition (LPCVD).

[0064] In some embodiments, to remove the first doped layer 102 and the third doped layer 104 in a preset area on the battery preform, the first doped layer 102 and the third doped layer 104 in the preset area can be removed by etching.

[0065] In some embodiments, after preparing the second doped layer 103 in the preset area, it further includes: preparing a passivation layer 107, and the passivation layer 107 covers the surfaces of the third doped layer 104, the isolation groove 1011, and the second doped layer 103. Optionally, the passivation layer 107 can be prepared by coating.

[0066] Another embodiment of the present application provides a method for manufacturing a solar cell 20. The method for manufacturing the solar cell 20 includes the following steps: manufacturing a solar cell contact structure 10 by using the above manufacturing method. Preparing a first electrode 201 and a second electrode 202 on the solar cell contact structure 10, the first electrode 201 penetrates through the third doped layer 104 and contacts the first doped layer 102, and the second electrode 202 contacts the second doped layer 103.

[0067] In some embodiments, the method for manufacturing the solar cell 20 includes the following steps:

[0068] S01: Polishing the silicon substrate 101.

[0069] S02: Depositing a first dielectric layer 105 on the back surface of the substrate 101 by LPCVD, and the material of the first dielectric layer 105 is silicon oxide.

[0070] S03: Depositing a first intrinsic amorphous silicon layer on the surface of the first dielectric layer 105 by LPCVD.

[0071] S04: Performing boron doping treatment on the first intrinsic amorphous silicon layer. Different doping layers with different boron doping concentrations can be obtained through boron doping treatment. In the direction away from the first dielectric layer 105, a first doped layer 102, a third doped layer 104, and a borosilicate glass layer 30 are sequentially stacked by boron doping treatment, and the doping concentration of boron element in the third doped layer 104 is greater than that in the first doped layer 102. At this time, the structure shown in Figure 5 can be obtained.

[0072] S05: Etch the product obtained in S04 to remove the first doping layer 102 and the third doping layer 104 in a preset area on the product.

[0073] S06: Deposit a second dielectric layer 106 on the surface of the product obtained in S05 by LPCVD. The material of the second dielectric layer 106 is silicon oxide. The second dielectric layer 106 covers the surface of the borosilicate glass layer 30 and the silicon substrate 101 exposed after etching.

[0074] S07: Deposit a second intrinsic amorphous silicon layer on the surface of the second dielectric layer 106 by LPCVD.

[0075] S08: Perform phosphorus doping on the second intrinsic amorphous silicon layer. Through the phosphorus doping process, a second doping layer 103 and a phosphosilicate glass layer 40 stacked in sequence can be obtained in the direction away from the second dielectric layer 106. At this time, the Figure 6 shown structure can be obtained.

[0076] S09: Etch and texture the product obtained in S08 to form a textured surface 60 on the front of the product. After texturing, perform an alkali polishing treatment on the product to remove the phosphosilicate glass layer 40. Then perform an oxidation treatment on the product. Oxide layers 50 are formed on the front and back of the product. At this time, the Figure 7 shown structure can be obtained, Figure 7 and the oxide layer on the front in

[0077] S10: Perform a patterned etching treatment on the product obtained in S09. The oxide layer can be used as a mask layer to obtain a patterned isolation groove 1011. Then remove the redundant oxide layer, and remove the borosilicate glass layer 30, the second dielectric layer 106, and the second doping layer 103 on the third doping layer 104. At this time, the Figure 8 shown structure can be obtained.

[0078] S11: Perform coating and screen printing on the product obtained in S10 to obtain a passivation layer 107 on the back, an antireflection layer 203 on the textured surface 60, and a first electrode 201 and a second electrode 202. At this time, the Figure 4 shown solar cell 20 can be obtained.

[0079] Example 1

[0080] The preparation method of the solar cell in this example includes:

[0081] S101: Polish the silicon substrate.

[0082] S102: Deposit a first dielectric layer 105 on the back of the substrate 101 by LPCVD. The material of the first dielectric layer 105 is silicon oxide.

[0083] S103: Deposit a first intrinsic amorphous silicon layer on the surface of the first dielectric layer 105 by LPCVD.

[0084] S104: Perform boron doping treatment on the first intrinsic amorphous silicon layer. Different doping layers with different boron doping concentrations can be obtained through boron doping treatment. In the direction away from the first dielectric layer 105, a first doped layer 102, a third doped layer 104, and a borosilicate glass layer 30 are sequentially stacked through boron doping treatment, where the doping concentration of boron element in the third doped layer 104 is greater than that in the first doped layer 102.

[0085] S105: Etch the product obtained in S104 to remove the first doped layer 102 and the third doped layer 104 in a preset area on the product.

[0086] S106: Deposit a second dielectric layer 106 on the surface of the product obtained in S05 by LPCVD. The material of the second dielectric layer 106 is silicon oxide. The second dielectric layer 106 covers the surface of the borosilicate glass layer 30 and the silicon substrate 101 exposed after etching.

[0087] S107: Deposit a second intrinsic amorphous silicon layer on the surface of the second dielectric layer 106 by LPCVD.

[0088] S108: Perform phosphorus doping treatment on the second intrinsic amorphous silicon layer. Through phosphorus doping treatment, a second doped layer 103 and a phosphosilicate glass layer 40 are sequentially stacked in the direction away from the second dielectric layer 106.

[0089] S109: Etch and texture the product obtained in S108 to form a textured surface 60 on the front of the product. After texturing, perform alkali polishing treatment on the product to remove the phosphosilicate glass layer 40. Then perform oxidation treatment on the product. Oxide layers 50 are formed on the front and back of the product.

[0090] S110: Perform patterned etching treatment on the product obtained in S109. The oxide layer can be used as a mask layer to obtain a patterned isolation groove 1011. Then remove the excess oxide layer, and remove the borosilicate glass layer 30, the second dielectric layer 106, and the second doped layer 103 on the third doped layer 104.

[0091] S111: Perform coating and screen printing treatment on the product obtained in S110 to obtain a passivation layer 107 on the back, an antireflection layer 203 on the textured surface 60, and a first electrode 201 and a second electrode 202.

[0092] The structure of the solar cell 20 obtained in this embodiment is as Figure 4 shown.

[0093] Comparative Example 1

[0094] Compared with Example 1, the difference in Comparative Example 1 is that S110 is: etching the product obtained in S109 to remove the oxide layer 50, removing the borosilicate glass layer 30, the second dielectric layer 106, and the second doping layer 103 on the third doping layer 104, removing the third doping layer 104, and obtaining the isolation groove 1011.

[0095] Compared with Figure 4 the structure shown, the solar cell 20 structure obtained in this comparative example does not contain the third doping layer 104.

[0096] Comparative Example 2

[0097] Compared with Example 1, the difference in Comparative Example 2 is that the doping element in the third doping layer 104 is phosphorus.

[0098] The photoelectric conversion efficiency and yield of the solar cells obtained in Example 1 and the comparative examples are shown in Table 1.

[0099] Table 1

[0100]

[0101] In Table 1, the A-level rate means that the efficiency is not less than 25%, and there are no defects such as black spots, black dots, and belt prints in the EL appearance.

[0102] As can be seen from Table 1, compared with the comparative examples, the solar cell 20 obtained in Example 1 has a higher yield. At the same time, the solar cell 20 obtained in Example 1 has a higher photoelectric conversion efficiency.

[0103] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, 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, it should be considered as the scope described in this specification.

[0104] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims, and the specification and drawings can be used to explain the content of the claims.

Claims

1. A solar cell contact structure, characterized in that, It includes a substrate, a first doped layer, a second doped layer, and a third doped layer; the first doped layer and the second doped layer are disposed at intervals on the back surface of the substrate, and the doping type of the first doped layer is opposite to that of the second doped layer; the third doped layer is disposed on the surface of the first doped layer away from the substrate, and the doping type of the third doped layer is the same as that of the first doped layer; In the thickness direction of the substrate, the surface of the third doped layer away from the substrate protrudes from the second doped layer.

2. The solar cell contact structure according to claim 1, characterized in that, The doping concentration of the doping element in the third doped layer is greater than that of the doping element in the first doped layer; and / or, The doping concentration of the doping element in the third doping layer ≥ 1×10 20 / cm 3 .

3. The solar cell contact structure according to claim 1, wherein The doping element in the first doped layer includes a P-type doping element, and the doping element in the second doped layer includes an N-type doping element.

4. The solar cell contact structure according to claim 1, wherein In the thickness direction of the substrate, the height by which the surface of the third doped layer away from the substrate protrudes from the second doped layer is 0.1 μm to 10 μm.

5. The solar cell contact structure according to any one of claims 1 to 4, characterized in that, Isolation grooves are provided on the substrate, and the isolation grooves are located between the first doped layer and the second doped layer so that the first doped layer and the second doped layer are disposed at intervals.

6. The solar cell contact structure according to claim 5, characterized in that, The height from the surface of the first doped layer away from the substrate to the bottom of the isolation groove is 0.1 μm to 10 μm; and / or, The height from the surface of the second doped layer away from the substrate to the bottom of the isolation groove is 0.1 μm to 10 μm.

7. The solar cell contact structure according to any one of claims 1 to 4, characterized in that, The solar cell contact structure further includes a first dielectric layer, and the first dielectric layer is located between the first doped layer and the substrate; and / or, The solar cell further includes a second dielectric layer, and the second dielectric layer is located between the second doped layer and the substrate.

8. A solar cell, characterized in that, It includes a first electrode, a second electrode, and the solar cell contact structure according to any one of claims 1 to 7; the first electrode penetrates through the third doped layer and contacts the first doped layer, and the second electrode contacts the second doped layer.

9. A method for preparing a solar cell contact structure, characterized in that, It includes the following steps: Prepare a first doped layer and a third doped layer on the back surface of the substrate, the third doped layer is disposed on the surface of the first doped layer away from the substrate, the doping type of the third doped layer is the same as that of the first doped layer, and prepare a battery preform; Remove the first doped layer and the third doped layer in a preset area on the battery preform; Prepare a second doped layer in the preset area, the doping type of the second doped layer is opposite to that of the first doped layer, the second doped layer and the first doped layer are disposed at intervals, and in the thickness direction of the substrate, the surface of the third doped layer protrudes from the second doped layer.

10. A method for preparing a solar cell, characterized in that, It includes the following steps: Prepare a solar cell contact structure by using the preparation method according to claim 9; Prepare a first electrode and a second electrode on the solar cell contact structure, the first electrode penetrates through the third doped layer and contacts the first doped layer, and the second electrode contacts the second doped layer.

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