Solar cell, photovoltaic module and preparation method of solar cell

Abstract

The invention relates to the field of photovoltaic technology, in particular to a solar cell, a photovoltaic module and a preparation method of the solar cell, the solar cell comprises a substrate, the substrate comprises a first surface and a second surface, the first surface comprises a first area and a second area, and the second surface comprises a third area and a fourth area, the first diffusion layer is located on the first area or located in the substrate corresponding to the first area, the first diffusion layer is opposite to the substrate in conductive type, the second diffusion layer is located in the substrate corresponding to the third area, the second diffusion layer is opposite to the first diffusion layer in conductive type, and the first passivation layer is located on the third area and the fourth area. The first passivation layer covers the second diffusion layer and is in contact with the substrate, the first electrode electrically connected with the first diffusion layer is arranged on the first area, the second electrode electrically connected with the second diffusion layer is arranged on the third area, and the open-circuit voltage and the short-circuit current of the solar cell are improved through the design, and the photoelectric conversion efficiency is improved.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular to a solar cell, a photovoltaic module, and a method for preparing a solar cell. Background Art

[0002] In today's energy shortage situation, solar cells, as a renewable resource, have attracted widespread attention. Solar cells are used to convert solar energy into electrical energy. Currently, solar cells have the problem of low photoelectric conversion efficiency, which affects the reliability of solar cells. Summary of the Invention

[0003] In view of this, the present application provides a solar cell, a photovoltaic module and a method for preparing a solar cell, so as to solve the problem of low photoelectric conversion efficiency of solar cells in the prior art.

[0004] In a first aspect, embodiments of the present application provide a solar cell, comprising a substrate, a first diffusion layer, a second diffusion layer, a first passivation layer, a first electrode, and a second electrode. The substrate comprises a first surface facing light and a second surface facing away from light, the first surface comprising alternating first and second regions, the second surface comprising alternating third and fourth regions, the first diffusion layer being located on the first region or within the substrate corresponding to the first region, the first diffusion layer having an opposite conductivity type to that of the substrate, the second diffusion layer being located within the substrate corresponding to the third region, the second diffusion layer having an opposite conductivity type to that of the first diffusion layer, the first passivation layer being located on the third region and the fourth region, the first passivation layer covering the second diffusion layer and contacting the substrate, the first electrodes being disposed one-to-one on the first regions and electrically connected to the first diffusion layers, the second electrodes being disposed one-to-one on the third regions, at least a portion of the first electrode penetrating the first passivation layer and electrically connected to the second diffusion layer.

[0005] In a second aspect, an embodiment of the present application provides a photovoltaic module, which includes an encapsulation layer, a cover plate and at least one battery string, wherein the battery string includes a plurality of the above-mentioned solar cells, the encapsulation layer covers the surface of the battery string, and the cover plate covers the surface of the encapsulation layer facing away from the battery string.

[0006] In a third aspect, an embodiment of the present application provides a method for preparing a solar cell, wherein the substrate of the solar cell includes a first surface facing the light and a second surface facing away from the light, the first surface includes first and second areas arranged alternately, and the second surface includes third and fourth areas arranged alternately, and the method for preparing the solar cell includes: performing boron diffusion on the textured substrate to form a first diffusion layer and a borosilicate glass layer on the first surface of the substrate, performing laser treatment on the second area of the first surface, performing phosphorus diffusion on the substrate from which the borosilicate glass layer on the second surface is removed to form a second diffusion layer and a phosphosilicate glass layer on the second surface of the substrate, performing laser treatment on the fourth area of the second surface, performing a first etching treatment on the substrate from which the phosphosilicate glass layer on the first surface is removed to remove the first diffusion layer and the borosilicate glass layer on the second area, and remove the second diffusion layer and the phosphosilicate glass layer on the fourth area, performing a second etching treatment on the substrate to remove the borosilicate glass layer on the first area and the phosphosilicate glass layer on the third area, forming a first passivation layer on the second surface of the substrate, and performing laser-assisted sintering treatment on the second surface of the substrate.

[0007] The beneficial effects of the present application are: reducing the Auger recombination and surface recombination on the front side of the substrate, increasing the lifetime of minority carriers, and at the same time reducing the Auger recombination on the back side of the substrate, reducing the recombination rate on the back side of the substrate, and improving the passivation effect, thereby increasing the open circuit voltage and short-circuit current of the solar cell, and thus improving the photoelectric conversion efficiency of the solar cell. The first passivation layer has better stability, and its passivation effect will not be affected by factors such as the diffusion of doping elements, thereby improving the overall stability and reliability of the solar cell while improving the electrical performance of the solar cell. The first passivation layer can reduce the recombination rate on the surface of the substrate, increase the minority carrier lifetime, and increase the open circuit voltage and short-circuit current. The preparation of the first passivation layer is relatively simple, and there is no need to perform steps such as the deposition of polysilicon and the introduction of doping elements, thereby simplifying the production process of solar cells and reducing the difficulty and cost of preparing solar cells.

[0008] It should be understood that the foregoing general description and the following detailed description are merely illustrative and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0010] Figure 1A schematic structural diagram of a solar cell provided in one embodiment of the present application;

[0011] Figure 2 A schematic structural diagram of a first anti-reflection layer and a first passivation layer provided in one embodiment of the present application;

[0012] Figure 3 A schematic structural diagram of a photovoltaic module provided in one embodiment of the present application;

[0013] Figure 4 This is a schematic diagram of a texturized substrate in one embodiment of the present application;

[0014] Figure 5 This is a schematic diagram of a substrate after boron diffusion in one embodiment of the present application;

[0015] Figure 6 This is a schematic diagram of the positions of the first region and the second region on the substrate in one embodiment of the present application;

[0016] Figure 7 This is a schematic diagram of a substrate after the borosilicate glass layer on the second surface is removed in one embodiment of the present application;

[0017] Figure 8 This is a schematic diagram of a substrate after phosphorus diffusion in one embodiment of the present application;

[0018] Figure 9 This is a schematic diagram of the positions of the third region and the fourth region on the substrate in one embodiment of the present application;

[0019] Figure 10 This is a schematic diagram of a substrate after the phosphosilicate glass layer on the first surface is removed in one embodiment of the present application;

[0020] Figure 11 A schematic diagram of a substrate after a first etching process in an embodiment of the present application;

[0021] Figure 12 is a schematic diagram of a substrate after a second etching process in one embodiment of the present application;

[0022] Figure 13 is a schematic diagram of forming a second passivation layer on the first surface of a substrate in one embodiment of the present application;

[0023] Figure 14 is a schematic diagram of forming a first passivation layer on the second surface of the substrate in one embodiment of the present application;

[0024] Figure 15 A schematic diagram of forming a second anti-reflection layer on one side of the second passivation layer in one embodiment of the present application;

[0025] Figure 16A schematic diagram of forming a first anti-reflection layer on one side of the first passivation layer in one embodiment of the present application;

[0026] Figure 17 This is a schematic structural diagram of a solar cell in one embodiment of the present application;

[0027] Figure 18 This is a flow chart of a method for preparing a solar cell provided in one embodiment of the present application.

[0028] Reference numerals:

[0029] 1000-photovoltaic module; 100-cell string; 10-solar cell; 11-substrate; 111-first surface; 1111-first region; 1112-second region; 112-second surface; 1121-third region; 1122-fourth region; 121-first diffusion layer; 122-borosilicate glass layer; 131-second diffusion layer; 132-phosphosilicate glass layer 14-first passivation layer; 15-first anti-reflection layer; 151-silicon oxynitride layer; 152-silicon nitride layer; 153-silicon oxide layer; 16-second passivation layer; 17-second anti-reflection layer; 18-first electrode; 19-second electrode; 200-first cover plate; 300-second cover plate; 400-first encapsulation layer; 500-second encapsulation layer. DETAILED DESCRIPTION

[0030] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0031] It should be clear that the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0032] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "an", "the" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0033] It should be understood that the term "and / or" as used herein simply describes a relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A alone, A and B together, or B alone. Furthermore, the character " / " in this document generally indicates an "or" relationship between the associated objects.

[0034] like Figure 1As shown, an embodiment of the present application provides a solar cell 10 , including a substrate 11 , a first diffusion layer 121 , a second diffusion layer 131 , a first passivation layer 14 , a first electrode 18 , and a second electrode 19 .

[0035] The substrate 11 can be an N-type substrate or a P-type substrate. The N-type substrate can be a silicon substrate doped with an N-type element. Specifically, the N-type element can be one or a combination of pentavalent elements such as phosphorus, arsenic, or antimony. The P-type substrate can be a silicon substrate doped with a P-type element. Specifically, the P-type element can be one or a combination of trivalent elements such as boron, indium, or gallium. The structure of a solar cell is described below using an N-type silicon substrate as an example.

[0036] The substrate 11 includes a first surface 111 facing the light and a second surface 112 facing away from the light. The first surface 111 is the surface that is directly exposed to sunlight (i.e., the light-facing surface) and can be considered the front of the substrate 11. The second surface 112 is the surface that is not directly exposed to sunlight (i.e., the light-facing surface) and can be considered the back of the substrate 11. Both the first surface 111 and the second surface 112 can receive sunlight and convert the light energy into electrical energy.

[0037] The first surface 111 includes alternating first regions 1111 and second regions 1112. The first regions 1111 are metallized regions, i.e., the regions where the metal grid lines (i.e., first electrodes 18) of the first surface 111 are located. The width of the first regions 1111 may be greater than the width of the first electrodes 18. The second regions 1112 may be non-metallized regions of the first surface 111, i.e., the regions on the first surface 111 other than the first regions 1111. The second surface 112 includes alternating third regions 1121 and fourth regions 1122. The third regions 1121 are metallized regions, i.e., the regions where the metal grid lines (i.e., second electrodes 19) of the second surface 112 are located. The width of the third regions 1121 may be greater than the width of the second electrodes 19. The fourth regions 1122 may be non-metallized regions of the second surface 112, i.e., the regions on the second surface 112 other than the third regions 1121.

[0038] The first diffusion layer 121 is located on the first region 1111 or within the substrate 11 corresponding to the first region 1111. The first diffusion layer 121 has an opposite conductivity type to that of the substrate 11. The first diffusion layer 121 can be of P-type conductivity and can form a PN junction with the substrate 11. When the solar cell 10 is exposed to light, the built-in electric field within the PN junction effectively separates photogenerated carriers (electron-hole pairs), causing electrons and holes to accumulate in different regions, thereby generating current. The first electrode 18 is disposed in a one-to-one correspondence on the first region 1111 and is electrically connected to the first diffusion layer 121 to form a current path.

[0039] The second diffusion layer 131 is located within the substrate 11 corresponding to the third region 1121. The second diffusion layer 131 has an opposite conductivity type to the first diffusion layer 121. The conductivity type of the third diffusion layer can be N-type. The first passivation layer 14 is located on the third region 1121 and the fourth region 1122, that is, the first passivation layer 14 is provided across the entire second surface 112. The first passivation layer 14 covers the second diffusion layer 131 and contacts the substrate 11. The second electrodes 19 are provided in a one-to-one correspondence on the third region 1121. At least a portion of the first electrode 18 penetrates the first passivation layer 14 and is electrically connected to the second diffusion layer 131 to form a current path.

[0040] In the related art, a first diffusion layer is provided on the entire front surface of the solar cell, and a second diffusion layer is provided on the front back surface of the solar cell, that is, the first diffusion layer is simultaneously formed in the first area and the second area of the first surface, and the second diffusion layer is simultaneously formed in the third area and the fourth area of the second surface, and a doped polysilicon layer is also provided on the side of the second diffusion away from the substrate, resulting in a large amount of Auger recombination and surface recombination on the front surface of the solar cell, thereby causing a loss in the open-circuit voltage of the solar cell. At the same time, there is a large amount of light parasitic absorption on the back surface of the solar cell, which causes a loss in the short-circuit current of the solar cell, thereby affecting the efficiency of the solar cell.

[0041] Compared to related art, in the embodiment of the present application, the first diffusion layer 121 is disposed on the first region 1111 (or disposed within the substrate 11 corresponding to the first region 1111), while the first diffusion layer 121 is not disposed in the second region 1112. This allows the first diffusion layer 121 to form a PN junction only with the substrate 11 corresponding to the first region 1111. This reduces Auger recombination and surface recombination on the front side of the substrate 11, increases the lifetime of minority carriers, and improves the open-circuit voltage and short-circuit current of the solar cell 10, thereby improving the electrical performance of the solar cell 10. The second diffusion layer 131 is disposed on the third region 1121, while the second diffusion layer 131 is not disposed in the fourth region 1122. This reduces Auger recombination on the back side of the substrate 11, reduces the recombination rate on the back side of the substrate 11, and improves the passivation effect.

[0042] The embodiment of the present application eliminates the doped polysilicon layer on the back of the substrate 11 and provides a first passivation layer 14 in contact with the substrate 11. The first passivation layer 14 implements field passivation on the surface of the substrate 11, thereby reducing the recombination rate on the surface of the substrate 11, increasing the minority carrier lifetime, and improving the open circuit voltage and short circuit current, thereby improving the efficiency of the solar cell 10 and further improving the reliability of the solar cell 10. Compared with the doped polysilicon layer, the first passivation layer 14 has better stability, and its passivation effect is not affected by factors such as the diffusion of doping elements, thereby improving the electrical performance of the solar cell 10 while improving the overall stability and reliability of the solar cell 10. At the same time, the preparation of the first passivation layer 14 is relatively simple, and there is no need to perform steps such as the deposition of polysilicon and the introduction of doping elements, thereby simplifying the production process of the solar cell 10 and reducing the difficulty and cost of preparing the solar cell 10. On the other hand, during the preparation of the solar cell 10, laser-assisted sintering technology is typically used to achieve good ohmic contact between the substrate 11 and the electrode, thereby reducing contact resistance and improving current collection. However, the effectiveness of laser-assisted sintering technology is limited when a doped polysilicon layer is provided on the back of the solar cell 10. In the embodiment of the present application, since there is no restriction of the doped polysilicon layer, the laser-assisted sintering technology can be fully utilized to process the surface of the substrate 11, thereby achieving good ohmic contact between the second electrode 19 and the substrate 11 and optimizing the electrical performance of the solar cell 10.

[0043] In summary, the solar cell 10 of the embodiment of the present application reduces the recombination and parasitic absorption on the surface of the substrate 11 , improves the open circuit voltage and short circuit current of the solar cell 10 , and thus realizes the design of a high-efficiency solar cell 10 .

[0044] In one possible embodiment, the first passivation layer 14 has a fixed negative charge. The negative charge of the first passivation layer 14 regulates the band structure and carrier distribution of the substrate 11 to form field passivation, thereby improving the passivation effect of the first passivation layer 14, increasing the open circuit voltage and short circuit current of the solar cell 10, and thus improving the photoelectric conversion efficiency of the solar cell 10.

[0045] like Figure 1 As shown, in a possible implementation, the first passivation layer 14 is one or more of aluminum oxide, silicon oxynitride, zirconium oxide, hafnium oxide, and arsenic oxide, and the thickness D1 of the first passivation layer 14 satisfies: 0.8 nm ≤ D1 ≤ 3 nm.

[0046] By selecting the above materials, the first passivation layer 14 has a good passivation effect and stable chemical properties, reducing the possibility of it being affected by external factors (such as temperature, humidity, etc.), thereby helping to increase the service life of the solar cell 10 and improve the reliability of the solar cell 10.

[0047] The thickness D1 of the first passivation layer 14 can be 0.8 nm, 0.9 nm, 1 nm, 1.2 nm, 1.4 nm, 1.6 nm, 1.8 nm, 2 nm, 2.2 nm, 2.4 nm, 2.6 nm, 2.8 nm, or 3 nm, and can also be other values within the above range. By limiting the thickness of the first passivation layer 14 to the above range, the first passivation layer 14 has higher reliability, thereby effectively reducing the recombination rate on the surface of the substrate 11, enhancing the field passivation effect, and at the same time helping to reduce the contact resistance between the substrate 11 and the electrode. In addition, it also helps to reduce parasitic absorption of light, thereby helping to improve the optical performance of the solar cell 10.

[0048] In some embodiments, the first passivation layer is an aluminum oxide layer. Aluminum oxide has a good passivation effect, reducing the carrier recombination rate on the substrate surface, effectively improving the open-circuit voltage and short-circuit current of the solar cell. Furthermore, aluminum oxide has excellent optical properties, which improves the light utilization efficiency of the solar cell, thereby enhancing the electrical performance of the solar cell.

[0049] In some embodiments, the first passivation layer is a zirconium oxide layer. Zirconium oxide has stable chemical properties and can withstand extreme conditions such as high voltage and high temperature, thereby improving the stability and reliability of the solar cell while achieving a good passivation effect.

[0050] In some embodiments, the first passivation layer is a hafnium oxide layer. Hafnium oxide effectively enhances the electric field effect, thereby better achieving field passivation, reducing carrier recombination on the back of the cell, increasing the lifetime of minority carriers, and improving the open-circuit voltage of the cell. Furthermore, hafnium oxide can reduce parasitic absorption, improve the solar cell's light utilization efficiency, and thus increase the cell's short-circuit current.

[0051] like Figure 1 As shown, in a possible embodiment, the solar cell 10 further includes a first anti-reflection layer 15 . The first anti-reflection layer 15 is located on a side of the first passivation layer 14 away from the substrate 11 . The thickness D2 of the first anti-reflection layer 15 satisfies: 60 nm ≤ D2 ≤ 100 nm.

[0052] The first anti-reflection layer 15 is used to reduce optical reflection and provide passivation, while also stabilizing and protecting the first passivation layer 14. At least a portion of the second electrode 19 penetrates the first anti-reflection layer 15 and the first passivation layer 14 and is electrically connected to the second diffusion layer 131.

[0053] The thickness D2 of the first anti-reflection layer 15 can be 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, or 100 nm, and can of course be other values within the above range. If the thickness of the first anti-reflection layer 15 is too thin or too thick, it will affect the optical properties and passivation effect of the first anti-reflection layer 15, resulting in an increase in the reflectivity of the substrate 11 surface and a weakening of the passivation effect, thereby affecting the electrical performance of the solar cell 10. On the other hand, if the first anti-reflection layer 15 is too thin, the mechanical properties of the first anti-reflection layer 15 itself will be poor, and it will be prone to cracking in subsequent steps such as screen printing, thereby reducing the yield of the solar cell 10. If the first anti-reflection layer 15 is too thick, it will reduce the adhesion of the metal paste, increase the risk of electrode breakage or delamination between the electrode and the substrate 11, thereby affecting the normal use of the solar cell 10. Therefore, the thickness of the first anti-reflection layer 15 is limited to the above range to ensure that the first anti-reflection layer 15 achieves good anti-reflection effect and passivation effect, while improving the mechanical strength of the first anti-reflection layer 15 and improving the stability and reliability of the second electrode 19, thereby ensuring the normal and stable operation of the solar cell 10.

[0054] like Figure 2 As shown, in one possible embodiment, the first anti-reflection layer 15 includes a silicon oxynitride layer 151, a silicon nitride layer 152, and a silicon oxide layer 153, which are arranged in a direction away from the substrate 11. That is, the first anti-reflection layer 15 has a stacked design, with the silicon oxynitride layer 151 located at the bottommost layer of the first anti-reflection layer 15. In other words, the silicon oxynitride layer 151 is located on the side of the silicon nitride layer 152 close to the substrate 11, and correspondingly, the silicon oxide layer 153 is located on the side of the silicon nitride layer 152 away from the substrate 11.

[0055] The stacked design of silicon oxynitride layer 151, silicon nitride layer 152, and silicon oxide layer 153 achieves a gradient design of the refractive index of the first anti-reflection layer 15, thereby optimizing the optical performance of the first anti-reflection layer 15, improving the anti-reflection effect of the first anti-reflection layer 15, and thereby improving the electrical performance of the solar cell 10. The silicon oxynitride layer 151 can contact the first passivation layer 14 and can also be negatively charged, thereby cooperating with the negatively charged first passivation layer 14 to enhance the passivation effect on the surface of the substrate 11, reduce the recombination rate on the surface of the substrate 11, and increase the open-circuit voltage of the solar cell 10. The silicon nitride layer 152 can act as a hydrogen passivator, repairing dangling bonds on the surface of the substrate 11 and reducing the recombination rate on the surface of the substrate 11. The silicon oxide layer 153 is located on the top of the first anti-reflection layer 15, which can effectively reduce parasitic absorption of light. The chemical properties of the silicon oxide layer 153 are relatively stable, and it has an isolation effect on the silicon nitride layer 152 and the silicon oxynitride layer 151, reducing the possibility of external water vapor penetrating into the silicon nitride layer 152 and the silicon oxynitride layer 151 and affecting the performance of the first anti-reflection layer 15. In addition, the silicon oxide layer 153 is located on the top of the first anti-reflection layer 15, which facilitates the adjustment of the color of the first anti-reflection layer 15 to improve the optical performance of the first anti-reflection layer 15.

[0056] The thickness D3 of the silicon oxide layer 153 satisfies the following condition: 10 nm ≤ D3 ≤ 30 nm. For example, D3 can be 10 nm, 13 nm, 15 nm, 16 nm, 19 nm, 20 nm, 22 nm, 25 nm, 28 nm, or 30 nm, and can also be other values within the above range. By limiting the thickness of the silicon oxide layer 153, it has a good anti-reflection effect to improve light transmittance, and has reliable mechanical properties to protect the silicon nitride layer 152 and the silicon oxynitride layer 151, thereby improving the stability and reliability of the first anti-reflection layer 15 and extending the service life of the solar cell 10.

[0057] The thickness D4 of the silicon nitride layer 152 satisfies the following: 20 nm ≤ D4 ≤ 30 nm. For example, D4 can be 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, or 30 nm, and can also be other values within the above range. By limiting the thickness of the silicon nitride layer 152, it can form a good optical match with the silicon oxide layer 153 and the silicon oxynitride layer 151, achieving a wide-spectrum anti-reflection effect and improving the hydrogen passivation effect of the silicon nitride layer 152.

[0058] The thickness D5 of the silicon oxynitride layer 151 satisfies the following conditions: 5nm≤D5≤15nm. For example, D5 can be 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 11nm, 12nm, 13nm, 14nm, or 15nm. Of course, it can also be other values within the above range. By limiting the thickness of the silicon nitride layer 152, it is ensured that it cooperates well with the first passivation layer 14, thereby improving the passivation effect on the substrate 11. At the same time, the silicon oxynitride layer 151 has good anti-reflection ability, reducing the reflection of light on the surface of the substrate 11, and improving the electrical performance of the solar cell 10.

[0059] like Figure 1 As shown, in a possible embodiment, the first diffusion layer 121 includes a first doping element, and the doping concentration of the first diffusion layer 121 is 1E19 cm -3 to 1E20cm -3 The second diffusion layer 131 includes a second doping element, and the doping concentration of the second diffusion layer 131 is 1E20cm -3 to 5E20cm -3 .

[0060] The first diffusion layer 121 can have a P-type conductivity, and the doping element in the first diffusion layer 121 can be a trivalent element such as boron, aluminum, or gallium. The second diffusion layer 131 can have an N-type conductivity, and the doping element in the second diffusion layer 131 can be a pentavalent element such as phosphorus, arsenic, or antimony. Limiting the doping concentrations of the first and second diffusion layers 121, 131 helps reduce the contact resistance between the substrate 11 and the electrode, lowering the series resistance of the battery. It also improves the passivation effect on the surface of the substrate 11, reduces carrier recombination, and increases the minority carrier lifetime, thereby increasing the open-circuit voltage and short-circuit current of the solar cell 10 and improving the photoelectric conversion efficiency of the solar cell 10.

[0061] In some other embodiments, the doping concentration of the first diffusion layer 121 is 1E19 cm -3 to 1E20cm -3 Alternatively, the doping concentration of the second diffusion layer 131 is 1E20 cm -3 ~5E20cm -3 .

[0062] like Figure 1 As shown, in a possible embodiment, the solar cell 10 further includes a second passivation layer 16 and a second anti-reflection layer 17. The second passivation layer 16 is located on the first region 1111 and the second region 1112. The second passivation layer 16 covers the first diffusion layer 121 and is in contact with the substrate 11. The second passivation layer 16 carries a positive charge, and the second anti-reflection layer 17 is located on the side of the second passivation layer 16 away from the substrate 11.

[0063] At least part of the structure of the first electrode 18 penetrates the second anti-reflection layer 17 and the second passivation layer 16, and is electrically connected to the first diffusion layer 121. The second passivation layer 16 has a fixed positive charge. Optionally, the second passivation layer 16 can be one or more of silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, and hydrogenated silicon nitride. It should be noted that aluminum oxide itself has a fixed negative charge. When aluminum oxide is provided as the second passivation layer 16 on the first surface 111 of the substrate 11, after a long period of high-temperature annealing, the density of the fixed negative charge of aluminum oxide will decrease, while the positive charge will increase, so that aluminum oxide has a positive charge, that is, it can be regarded as having a fixed positive charge. The second passivation layer 16 forms an electric field on the front side of the substrate 11, optimizes the surface electric field distribution through the electric field modulation effect, reduces the recombination of minority carriers, and increases the lifetime of minority carriers. The second passivation layer 16 can play a field passivation role and / or a hydrogen passivation role, thereby improving the open circuit voltage and short circuit current of the solar cell 10 and improving the photoelectric conversion efficiency of the solar cell 10.

[0064] The thickness D6 of the second passivation layer 16 satisfies the following: 0.8 nm ≤ D6 ≤ 3 nm. For example, D6 can be 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, 1 nm, 1.2 nm, 1.4 nm, 1.6 nm, 1.8 nm, 2 nm, 2.2 nm, 2.4 nm, 2.6 nm, 2.8 nm, or 3 nm. Of course, other values within the above range are also possible. By limiting the thickness of the second passivation layer 16 to the above range, the reliability of the second passivation layer 16 is improved, thereby effectively reducing the recombination rate on the surface of the substrate 11 and enhancing the passivation effect. At the same time, it is also beneficial to reduce parasitic absorption of light, thereby facilitating the improvement of the optical performance of the solar cell 10.

[0065] The second anti-reflection layer 17 can be a silicon oxide layer, a silicon nitride layer, or a silicon oxynitride layer. The second anti-reflection layer 17 can play a role in anti-reflection and passivate the surface of the substrate 11, thereby improving the electrical performance of the solar cell 10.

[0066] The thickness D7 of the second anti-reflection layer 17 satisfies 60 nm ≤ D7 ≤ 100 nm. For example, D7 can be 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, or 100 nm, and can also be other values within the above range. If the second anti-reflection layer 17 is too thin or too thick, it will affect the optical performance and passivation effect of the second anti-reflection layer 17, resulting in increased reflectivity on the surface of the substrate 11 and weakened passivation effect, thereby affecting the electrical performance of the solar cell 10. If the second anti-reflection layer 17 is too thin, it will lead to poor mechanical properties of the second anti-reflection layer 17 itself, making it prone to cracking during subsequent screen printing and other steps, reducing the yield of the solar cell 10. If the second anti-reflection layer 17 is too thick, it will reduce the adhesion of the electrode slurry, increase the risk of electrode breakage or delamination from the substrate 11, and thus affect the normal use of the solar cell 10. Therefore, the thickness of the second anti-reflection layer 17 is limited to the above range to ensure good anti-reflection effect and passivation effect of the second anti-reflection layer 17 while improving the mechanical strength of the second anti-reflection layer 17 and improving the stability and reliability of the setting of the first electrode 18, thereby ensuring the normal and stable operation of the solar cell 10.

[0067] In other embodiments, the thickness D6 of the second passivation layer 16 satisfies: 0.8 nm ≤ D6 ≤ 3 nm, or the thickness D7 of the second anti-reflection layer 17 satisfies: 60 nm ≤ D7 ≤ 100 nm.

[0068] like Figure 1 As shown, in some embodiments, the first area 1111 and the second area 1112 of the first surface 111 are both velvet, that is, the first area 1111 and the second area 1112 of the substrate 11 are both formed with a pyramid structure, thereby effectively reducing the reflectivity of the incident light, that is, reducing the reflected light loss of the first surface 111, allowing more photons to enter the interior of the substrate 11, thereby improving the efficiency of the solar cell 10.

[0069] In some embodiments, there is a height difference between the first region 1111 and the second region 1112, thereby achieving separation between the two, that is, the first region 1111 and the second region 1112 are no longer in the same horizontal plane, thereby facilitating the positioning of the first electrode 18 and further facilitating the printing of metal paste.

[0070] In some embodiments, the third area 1121 and the fourth area 1122 of the second surface 112 are both velvet, that is, the third area 1121 and the fourth area 1122 of the substrate 11 are both formed with a pyramid structure to reduce the reflected light loss of the second surface 112, allowing more photons to enter the interior of the substrate 11, thereby improving the efficiency of the solar cell 10.

[0071] In some embodiments, there is a height difference between the third region 1121 and the fourth region 1122, thereby achieving separation between the two, that is, the third region 1121 and the fourth region 1122 are no longer in the same horizontal plane, thereby facilitating the positioning of the second electrode 19 and further facilitating the printing of metal paste.

[0072] In some embodiments, the third region and the fourth region of the second surface are polished surfaces to reduce defects and contamination on the substrate surface and improve the stability and reliability of the solar cell.

[0073] In some embodiments, the third area of the second surface is a polished surface, and the fourth area of the second surface is a suede surface. Alternatively, the third area of the second surface is a suede surface, and the fourth area of the second surface is a polished surface.

[0074] like Figure 3 As shown, an embodiment of the present application provides a photovoltaic module 1000, which includes an encapsulation layer, a cover plate, and at least one cell string 100. The encapsulation layer covers the surface of the cell string 100, and the cover plate covers the surface of the encapsulation layer facing away from the cell string 100. Among them, the cover plate located at the top of the photovoltaic module 1000 is the first cover plate 200, the cover plate located at the bottom of the photovoltaic module 1000 is the second cover plate 300, the encapsulation layer located between the first cover plate 200 and the cell string 100 is the first encapsulation layer 400, and the encapsulation layer located between the second cover plate 300 and the cell string 100 is the second encapsulation layer 500. The first cover plate 200, the second cover plate 300, the first encapsulation layer 400, the second encapsulation layer 500, and the cell string 100, the cell string 100 includes a plurality of the above-mentioned solar cells 10.

[0075] The first cover plate 200, the first encapsulation layer 400, the battery string 100, the second encapsulation layer 500, and the second cover plate 300 can be arranged along the thickness direction of the photovoltaic module 1000 and laminated together. Among them, the first cover plate 200 can be a glass cover plate, and the first cover plate 200 has a high light transmittance. The first encapsulation layer 400 bonds the first cover plate 200 and the battery string 100 together to provide encapsulation and protection for the battery string 100. The material of the first encapsulation layer 400 can be one or more of ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), and polyvinyl butyral (PVB). The second encapsulation layer 500 connects the battery layer to the second cover plate 300, which also provides encapsulation and protection for the battery string 100. The material of the second encapsulation layer 500 can be one or more of the above-mentioned EVA, POE, and PVB. The material of the second cover plate 300 can be glass, or the second cover plate 300 can also be composed of multiple polymer film layers.

[0076] The preparation method of the above solar cell will be introduced in detail below.

[0077] An embodiment of the present application provides a method for preparing a solar cell, comprising:

[0078] S601: If Figure 4 As shown, a substrate 11 is provided, and the substrate 11 is cleaned and textured.

[0079] In step S601, the substrate 11 can be cleaned first to remove stains and impurities on the surface of the substrate 11, and then the first surface 111 and the second surface 112 of the substrate 11 are etched to make the first surface 111 and the second surface 112 become velvet, even if the first surface 111 and the second surface 112 have a pyramid structure.

[0080] S602: If Figure 5 As shown, boron is diffused into the textured substrate 11 to form a first diffusion layer 121 and a borosilicate glass layer 122 on the first surface 111 of the substrate 11 .

[0081] In step S602, the boron diffusion source can be borane bromide (e.g., BBr3) with a square resistance of 50Ω / sqr to 300Ω / sqr. Optionally, the thickness of the borosilicate glass layer 122 formed on the first surface 111 is 10nm to 30nm. Optionally, the doping concentration of the first diffusion layer 121 is 1E19cm -3 to 1E20cm -3 .

[0082] Continue as Figure 5 As shown, after step S602 , a borosilicate glass layer 122 is formed on the second surface 112 of the substrate 11 .

[0083] S603: If Figure 6 As shown, the second area 1112 of the first surface 111 is laser processed.

[0084] In step S603, the second region 1112 is laser-treated to modify the borosilicate glass layer 122 in the second region 1112, that is, the porosity of the laser-treated borosilicate glass layer 122 is higher than that of the non-laser-treated borosilicate glass layer 122, so that the borosilicate glass layer 122 and the first diffusion layer 121 on the second region 1112 can be removed in subsequent steps.

[0085] Optionally, the laser in step S603 may be a nanosecond laser, a picosecond laser or a femtosecond laser.

[0086] S604: Remove the borosilicate glass layer 122 on the second surface 112 to form Figure 7 The structure shown.

[0087] In step S604 , the substrate 11 may be pickled using a hydrofluoric acid solution to remove the borosilicate glass layer 122 on the second surface 112 of the substrate 11 .

[0088] S605: texturing or polishing the second surface 112 of the substrate 11.

[0089] S606: If Figure 8 As shown, phosphorus diffusion is performed on the substrate 11 with the borosilicate glass layer 122 on the second surface 112 removed, so as to form a second diffusion layer 131 and a phosphosilicate glass layer 132 on the second surface 112 of the substrate 11 .

[0090] In step S606, the phosphorus diffusion source may be phosphorus oxychloride (POCl3). Optionally, the doping concentration of the second diffusion layer 131 is 1E20 cm -3 to 5E20cm -3 .

[0091] After step S606, the first surface 111 of the substrate 11 also has a phosphosilicate glass layer 132, that is, Figure 8 The structure shown,

[0092] S607: If Figure 9 As shown, the fourth region 1122 of the second surface 112 is laser processed.

[0093] In step S607, the fourth region 1122 is laser-treated to modify the phosphosilicate glass layer 132 in the fourth region 1122, that is, the looseness and porosity of the laser-treated phosphosilicate glass layer 132 is higher than the looseness and porosity of the non-laser-treated phosphosilicate glass layer 132, so as to facilitate the removal of the phosphosilicate glass layer 132 and the second diffusion layer 131 on the fourth region 1122 in subsequent steps.

[0094] Optionally, the laser in step S607 may be a nanosecond laser, a picosecond laser, or a femtosecond laser.

[0095] S608: Remove the phosphosilicate glass layer 132 on the first surface 111 to form Figure 10 The structure shown.

[0096] In step S608 , the substrate 11 may be pickled using a hydrofluoric acid solution to remove the phosphosilicate glass layer 132 on the first surface 111 of the substrate 11 .

[0097] S609: performing a first etching process on the substrate 11 with the phosphosilicate glass layer 132 removed from the first surface 111, so as to remove the first diffusion layer 121 and the borosilicate glass layer 122 located on the second region 1112, and remove the second diffusion layer 131 and the phosphosilicate glass layer 132 located on the fourth region 1122, thereby forming Figure 11 The structure shown.

[0098] In step S609, the substrate 11 can be etched using a chemical solution. Since the second area 1112 of the first surface 111 and the fourth area 1122 of the second surface 112 have been laser-processed, the borosilicate glass layer 122 on the second area 1112 and the phosphosilicate glass layer 132 on the fourth area 1122 are modified, thereby increasing the etching rate of the etching solution on the borosilicate glass layer 122 on the second area 1112 and the phosphosilicate glass layer 132 on the fourth area 1122, thereby removing the borosilicate glass layer 122 on the second area 1112 and the first diffusion layer 121 opposite to the portion of the borosilicate glass layer 122, and removing the phosphosilicate glass layer 132 on the fourth area 1122 and the second diffusion layer 131 opposite to the portion of the phosphosilicate glass layer 132. The first area 1111 of the first surface 111 and the third area 1121 of the second surface 112 are not laser processed, so that the borosilicate glass layer 122 in the first area 1111 and the phosphosilicate glass layer 132 in the third area 1121 can both serve as protective layers, so that the first diffusion layer 121 in the first area 1111 and the second diffusion layer 131 in the second area 1112 are not etched and are retained.

[0099] like Figure 11 As shown, after step S609 , a height difference is formed between the first area 1111 and the second area 1112 of the first surface 111 , and a height difference is formed between the third area 1121 and the fourth area 1122 of the second surface 112 .

[0100] Optionally, after step S609 , the second region 1112 of the first surface 111 and the fourth region 1122 of the second surface 112 may be formed with a pyramid structure, that is, the second region 1112 and the fourth region 1122 may form a suede surface.

[0101] Optionally, after step S609 , the second region 1112 of the first surface 111 and the fourth region 1122 of the second surface 112 may form polished surfaces.

[0102] S610: Perform a second etching process on the substrate 11 to remove the borosilicate glass layer 122 on the first area 1111 and the phosphosilicate glass layer 132 on the third area 1121 to form Figure 12 The structure shown.

[0103] In step S610, the substrate 11 can be etched using a chemical solution to remove the borosilicate glass layer 122 on the first area 1111 and the phosphosilicate glass layer 132 on the third area 1121, while the first diffusion layer 121 opposite to the portion of the borosilicate glass layer 122 is retained, and the second diffusion layer 131 opposite to the portion of the phosphosilicate glass layer 132 is retained.

[0104] S611: If Figure 13 As shown, a second passivation layer 16 is formed on the first surface 111 of the substrate 11. Optionally, the second passivation layer has a fixed positive charge.

[0105] S612: If Figure 14 As shown, a first passivation layer 14 is formed on the second surface 112 of the substrate 11. Optionally, the first passivation layer has a fixed negative charge.

[0106] Optionally, step S612 may be performed first, and then step S611 may be performed.

[0107] The first passivation layer 14 and the second passivation layer 16 can be formed by chemical vapor deposition, physical vapor deposition, plasma enhanced chemical vapor deposition or atomic layer deposition.

[0108] S613: If Figure 15 As shown, a second anti-reflection layer 17 is formed on a side of the second passivation layer 16 away from the substrate 11 .

[0109] S614: If Figure 16 As shown, a first anti-reflection layer 15 is formed on a side of the first passivation layer 14 away from the substrate 11 .

[0110] Optionally, step S614 may be performed first, and then step S613.

[0111] The first anti-reflection layer 15 and the second anti-reflection layer 17 can be formed by chemical vapor deposition, physical vapor deposition, plasma enhanced chemical vapor deposition or atomic layer deposition.

[0112] S615: Screen printing.

[0113] In step S615 , metal paste may be printed on the first region of the first surface and the third region of the second surface of the substrate. The metal paste may be silver paste or silver-aluminum paste.

[0114] S616: sintering and light annealing, forming Figure 17 The structure shown.

[0115] After sintering, the metal paste forms the first electrode 18 and the second electrode 19. The photoannealing process can irradiate the solar cell with light of a specific wavelength and energy to repair defects and stress inside the substrate 11 and improve the electrical performance of the solar cell.

[0116] S617: If Figure 17 As shown, the second surface 112 of the substrate 11 is subjected to a laser-assisted sintering process.

[0117] The laser-assisted sintering (LECO) process utilizes the high energy and electric field of the laser to promote good contact between the metal second electrode 19 and the substrate 11, thereby reducing contact resistance. In step S617, the second surface 112 may be irradiated with a laser. The laser may use at least one of infrared, red, and green light.

[0118] Optionally, in step S617 , the first surface 111 and the second surface 112 of the substrate 11 may be subjected to laser-assisted sintering treatment simultaneously.

[0119] The solar cell manufacturing process in the embodiments of this application is relatively simple, eliminating the need for steps such as polysilicon deposition and the introduction of doping elements. This streamlines the solar cell production process and reduces the difficulty and cost of solar cell manufacturing. Furthermore, during the solar cell manufacturing process, laser-assisted sintering technology is used to treat the second surface of the substrate to achieve good ohmic contact between the second electrode and the substrate, thereby optimizing the electrical performance of the solar cell.

[0120] Through the above-mentioned solar cell preparation method, the first diffusion layer is located only in the first region, forming a PN junction only with the substrate corresponding to the first region. This reduces Auger recombination and surface recombination on the front side of the substrate, increases the minority carrier lifetime, and improves the open-circuit voltage and short-circuit current of the solar cell, thereby improving the electrical performance of the solar cell. The second diffusion layer is located only in the third region, reducing Auger recombination on the back side of the substrate, reducing the recombination rate on the back side of the substrate, and improving the passivation effect. By providing a first passivation layer with a fixed negative charge in contact with the substrate, the negative charge properties of the first passivation layer regulate the band structure and carrier distribution of the substrate, forming field passivation, thereby reducing the recombination rate on the substrate surface, increasing the minority carrier lifetime, and improving the open-circuit voltage and short-circuit current, thereby improving the efficiency of the solar cell and further improving the reliability of the solar cell.

[0121] In one possible embodiment, the step of forming a first passivation layer on the second surface of the substrate includes forming a first passivation layer on the second surface of the substrate with a thickness D1 satisfying: 0.8 nm ≤ D1 ≤ 3 nm. The effect of the first passivation layer has been described in detail above and will not be repeated here.

[0122] In one possible embodiment, the method for preparing a solar cell further includes: forming a first anti-reflection layer having a thickness D2 satisfying: 60nm≤D2≤100nm on a side of the first passivation layer away from the substrate, the first anti-reflection layer comprising a silicon oxide layer, a silicon nitride layer, and a silicon oxynitride layer arranged in a direction away from the substrate. A second passivation layer having a thickness D6 satisfying: 0.8nm≤D6≤3nm is formed on the first surface of the substrate. A second anti-reflection layer having a thickness D7 satisfying: 60nm≤D7≤100nm is formed on a side of the second passivation layer away from the substrate. The effects of the first anti-reflection layer, the second anti-reflection layer, and the second passivation layer have been described in detail above and will not be repeated here.

[0123] In one possible embodiment, during the step of performing laser-assisted sintering on the second surface of the substrate, a reverse bias of 8V to 16V is applied to the substrate, the laser power is 20W to 100W, and the laser scanning speed is 20,000 mm / s to 70,000 mm / s. By designing the parameters of the laser-assisted sintering process, the contact resistance is reduced, the ohmic contact quality is improved, and the photoelectric conversion efficiency of the solar cell is thereby increased.

[0124] like Figure 18 As shown, another embodiment of the present application provides a method 700 for preparing a solar cell, comprising:

[0125] Step S701: Diffuse boron into the textured substrate to form a first diffusion layer and a borosilicate glass layer on the first surface of the substrate. Step S701 is the same as step S602 above and will not be described again.

[0126] Step S702: Laser processing is performed on the second area of the first surface. Step S702 is the same as the above-mentioned step 603 and will not be described again here.

[0127] Step S703: Phosphorus diffusion is performed on the substrate with the borosilicate glass layer removed from the second surface to form a second diffusion layer and a phosphosilicate glass layer on the second surface of the substrate. Step S203 is the same as step S606 above and will not be repeated here.

[0128] Step S704: laser processing is performed on the fourth area of the second surface. Step S704 is the same as the above-mentioned step S607 and will not be described again here.

[0129] Step S705: The substrate, from which the phosphosilicate glass layer on the first surface has been removed, is subjected to a first etching process to remove the first diffusion layer and borosilicate glass layer on the second region, and the second diffusion layer and phosphosilicate glass layer on the fourth region. Step S705 is identical to step S609 and is not further described here.

[0130] Step S706: Perform a second etching process on the substrate to remove the borosilicate glass layer on the first region and the phosphosilicate glass layer on the third region. Step S706 is the same as the above step S610 and will not be described again here.

[0131] Step S707: forming a first passivation layer on the second surface of the substrate. Step S207 is the same as the above-mentioned step S612 and will not be described again here.

[0132] Step S708: Performing laser-assisted sintering on the second surface of the substrate. Step S208 is the same as the above-mentioned step S617 and will not be described again here.

[0133] The above are merely optional embodiments of the present application and are not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A solar cell, characterized in that: include: A substrate comprising a first surface facing the light and a second surface facing away from the light, wherein the first surface comprises first and second areas arranged alternately, and the second surface comprises third and fourth areas arranged alternately; a first diffusion layer, the first diffusion layer being located on the first region or inside the substrate corresponding to the first region, the first diffusion layer having a conductivity type opposite to that of the substrate; a second diffusion layer, the second diffusion layer being located inside the substrate corresponding to the third region, and having a conductivity type opposite to that of the first diffusion layer; a first passivation layer, the first passivation layer being located on the third region and the fourth region, the first passivation layer covering the second diffusion layer and contacting the substrate; first electrodes, the first electrodes being disposed on the first regions in a one-to-one correspondence and electrically connected to the first diffusion layer; The second electrodes are disposed on the third regions in a one-to-one correspondence, and at least a portion of the structure of the first electrode penetrates the first passivation layer and is electrically connected to the second diffusion layer.

2. The solar cell according to claim 1, wherein The first passivation layer has a fixed negative charge.

3. The solar cell according to claim 2, wherein The first passivation layer is one or more of aluminum oxide, silicon oxynitride, zirconium oxide, hafnium oxide, and arsenic oxide; The thickness D1 of the first passivation layer satisfies: 0.8 nm ≤ D1 ≤ 3 nm.

4. The solar cell according to claim 1, wherein The solar cell further includes a first anti-reflection layer, wherein the first anti-reflection layer is located on a side of the first passivation layer away from the substrate; The thickness D2 of the first anti-reflection layer satisfies: 60nm≤D2≤100nm.

5. The solar cell according to claim 4, wherein The first anti-reflection layer includes a silicon oxynitride layer, a silicon nitride layer and a silicon oxide layer arranged in a direction away from the substrate; Wherein, the thickness D3 of the silicon oxide layer satisfies: 10nm≤D3≤30nm; The thickness D4 of the silicon nitride layer satisfies: 20nm≤D4≤30nm; The thickness D5 of the silicon oxynitride layer satisfies: 5nm≤D5≤15nm.

6. The solar cell according to any one of claims 1 to 5, characterized in that The first diffusion layer includes a first doping element, and the doping concentration of the first diffusion layer is 1E19cm -3 to 1E20cm -3 , and / or; The second diffusion layer includes a second doping element, and the doping concentration of the second diffusion layer is 1E20cm -3 to 5E20cm -3 .

7. The solar cell according to any one of claims 1 to 5, characterized in that The solar cell further includes a second passivation layer and a second anti-reflection layer; The second passivation layer is located on the first region and the second region, covers the first diffusion layer, and contacts the substrate, has a fixed positive charge, and the second anti-reflection layer is located on a side of the second passivation layer away from the substrate; The thickness D6 of the second passivation layer satisfies: 0.8 nm ≤ D6 ≤ 3 nm, and / or the thickness D7 of the second anti-reflection layer satisfies: 60 nm ≤ D7 ≤ 100 nm.

8. A photovoltaic module, characterized in that: The photovoltaic module comprises: at least one cell string, the cell string comprising a plurality of solar cells according to any one of claims 1 to 7; an encapsulation layer, the encapsulation layer covering the surface of the battery string; A cover plate covers a surface of the packaging layer facing away from the battery string.

9. A method for preparing a solar cell, characterized in that: The substrate of the solar cell includes a first surface facing light and a second surface facing away from light, the first surface includes first and second areas arranged alternately, and the second surface includes third and fourth areas arranged alternately. The method for preparing the solar cell includes: Performing boron diffusion on the textured substrate to form a first diffusion layer and a borosilicate glass layer on the first surface of the substrate; performing laser processing on a second area of the first surface; performing phosphorus diffusion on the substrate after the borosilicate glass layer on the second surface is removed, so as to form a second diffusion layer and a phosphorus silicate glass layer on the second surface of the substrate; performing laser processing on a fourth area of the second surface; performing a first etching process on the substrate with the phosphosilicate glass layer on the first surface removed, so as to remove the first diffusion layer and the borosilicate glass layer on the second region, and remove the second diffusion layer and the phosphosilicate glass layer on the fourth region; performing a second etching process on the substrate to remove the borosilicate glass layer on the first area and the phosphosilicate glass layer on the third area; forming a first passivation layer on the second surface of the substrate; The second surface of the substrate is subjected to a laser-assisted sintering process.

10. The method for preparing a solar cell according to claim 9, wherein: The step of forming a first passivation layer on the second surface of the substrate comprises: A first passivation layer having a thickness D1 satisfying the following conditions: 0.8 nm ≤ D1 ≤ 3 nm is formed on the second surface of the substrate.

11. The method for preparing a solar cell according to claim 9, wherein: The method for preparing the solar cell further includes: A first anti-reflection layer having a thickness D2 satisfying 60nm≤D2≤100nm is formed on a side of the first passivation layer away from the substrate, wherein the first anti-reflection layer includes a silicon oxide layer, a silicon nitride layer, and a silicon oxynitride layer arranged in a direction away from the substrate. forming a second passivation layer on the first surface of the substrate with a thickness D6 satisfying the following conditions: 0.8 nm ≤ D6 ≤ 3 nm; A second anti-reflection layer is formed on a side of the second passivation layer away from the substrate with a thickness D7 satisfying the following: 60 nm ≤ D7 ≤ 100 nm.

12. The method for preparing a solar cell according to any one of claims 9 to 11, characterized in that: In the step of performing laser-assisted sintering on the second surface of the substrate, a reverse bias of 8V to 16V is applied to the substrate, the laser power is 20W to 100W, and the laser scanning speed is 20000mm / s to 70000mm / s.

Images