Solar cell and preparation method thereof

Abstract

The invention provides a solar cell and a preparation method thereof, the solar cell comprises a silicon substrate and a laminated structure, and the laminated structure is arranged on the back surface of the silicon substrate along the thickness direction of the solar cell. And the silicon substrate and the laminated structure contain an antimony element. Wherein the laminated structure at least comprises a first tunneling oxide layer, a first doped polycrystalline silicon layer, a second tunneling oxide layer and a second doped polycrystalline silicon layer which are sequentially stacked in the thickness direction of the solar cell. The antimony element doping concentration in the second tunneling oxide layer is higher than the antimony element doping concentration in the first doped polycrystalline silicon layer. The antimony element in the laminated structure can be bonded with the silicon element, so that the passivation effect is effectively improved, the problem of low carrier conductivity is solved, and the working efficiency of the solar cell is improved. And the laminated structure has a certain concentration gradient characteristic along the thickness direction of the solar cell, so that the conductivity of carriers in the laminated structure can be improved, and the series resistance of the solar cell can be reduced.

Description

Technical Field

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

[0002] With the growing demand for renewable energy, solar cells have attracted widespread attention as an efficient and clean way of energy conversion. As a new type of solar cell technology, TOPCon cells have the advantages of high conversion efficiency, low attenuation performance, and high mass production cost performance, and are widely used in the photovoltaic power generation industry. TOPCon cells are usually prepared on pure phosphorus-doped N-type silicon wafer substrates, resulting in limited carrier conductivity in the TOPCon cell structure, resulting in poor conductivity and affecting the working efficiency of the TOPCon cell. Summary of the invention

[0003] The present application provides a solar cell and a method for preparing the solar cell, so as to solve the technical problem of low carrier conductivity in the battery structure in the prior art.

[0004] In a first aspect, an embodiment of the present application provides a solar cell, comprising a silicon substrate and a stacked structure; the stacked structure is arranged on the back side of the silicon substrate along the thickness direction of the solar cell; the silicon substrate and the stacked structure contain antimony element; wherein the stacked structure at least comprises a first tunneling oxide layer, a first doped polysilicon layer, a second tunneling oxide layer and a second doped polysilicon layer stacked in sequence along the thickness direction of the solar cell; the antimony element doping concentration in the second tunneling oxide layer is higher than the antimony element doping concentration in the first doped polysilicon layer.

[0005] In this embodiment, when the silicon substrate of the solar cell contains antimony elements, the antimony elements can overflow into the laminated structure to a certain extent, and the antimony elements overflowing into the laminated structure can form bonds with the silicon elements to avoid the formation of voids in the laminated structure, which can effectively improve the passivation effect, solve the problem of low carrier conductivity, and improve the working efficiency of the solar cell. And the antimony element doping concentration of the second tunneling oxide layer in the laminated structure is higher than the antimony element doping concentration in the first doped polysilicon layer. Even if the laminated structure has a certain concentration gradient characteristic along the thickness direction of the solar cell, the conductivity of the carriers in the laminated structure can be further improved, thereby reducing the series resistance of the solar cell, improving the fill factor and open circuit voltage of the solar cell, and further improving the working efficiency of the solar cell. At the same time, since the absorption and blocking effect of the second tunneling oxide layer on the antimony element is stronger than that of the first doped polysilicon layer, the second tunneling oxide layer can also block most of the antimony elements from continuing to diffuse away from the silicon substrate, maintaining the passivation effect.

[0006] In addition, compared with the related art in which the stacked structure of the solar cell only includes one tunneling oxide layer and one doped polysilicon layer, the stacked structure of the solar cell in the embodiment of the present application can be provided with two tunneling oxide layers and two polysilicon layers, which can further enhance the passivation effect of the solar cell, thereby further enhancing the working efficiency of the solar cell.

[0007] In a specific embodiment, the doping concentrations of antimony elements in the first tunneling oxide layer, the first doped polysilicon layer, the second tunneling oxide layer, and the second doped polysilicon layer are all different.

[0008] In a specific embodiment, the antimony doping concentration in the first tunneling oxide layer is higher than the antimony doping concentration in the first doped polysilicon layer, and the antimony doping concentration in the second tunneling oxide layer is higher than the antimony doping concentration in the second doped polysilicon layer.

[0009] In a specific embodiment, the antimony doping concentration in the first tunneling oxide layer is higher than the antimony doping concentration in the second tunneling oxide layer, and the antimony doping concentration in the second tunneling oxide layer is higher than the antimony doping concentration in the silicon substrate.

[0010] In a specific embodiment, the solar cell satisfies at least one of the following conditions: the antimony doping concentration in the first tunnel oxide layer is 5.0×10 16 -2.0×10 18 cm -3 The antimony doping concentration in the second tunnel oxide layer is 5.0×10 16 -2.0×10 18 cm -3 The antimony doping concentration in the first doped polysilicon layer is 2.0×10 16 -6.0×10 16 cm -3 The antimony doping concentration in the second doped polysilicon layer is 1.0×10 16 -2.0×10 16 cm -3 .

[0011] In a specific embodiment, the solar cell satisfies at least one of the following conditions: the thickness L1 of the first tunneling oxide layer is 1nm-2nm, the thickness L2 of the first doped polysilicon layer is 100nm-200nm, the thickness L3 of the second tunneling oxide layer is 1nm-2nm, and the thickness L4 of the second doped polysilicon layer is 100nm-200nm.

[0012] In a specific embodiment, the solar cell satisfies at least one of the following conditions: the antimony doping concentration in the first tunneling oxide layer gradually increases from the side facing the silicon substrate to the side away from the silicon substrate, the antimony doping concentration in the first doped polycrystalline silicon layer first decreases and then increases from the side facing the silicon substrate to the side away from the silicon substrate, the antimony doping concentration in the second tunneling oxide layer gradually decreases from the side facing the silicon substrate to the side away from the silicon substrate, and the antimony doping concentration in the second doped polycrystalline silicon layer gradually decreases from the side facing the silicon substrate to the side away from the silicon substrate.

[0013] In a second aspect, an embodiment of the present application provides a method for preparing a solar cell, the method for preparing a solar cell comprising: preparing a silicon substrate, wherein the silicon substrate contains antimony element; forming a first tunneling oxide layer, a first amorphous silicon layer, a second tunneling oxide layer and a second amorphous silicon layer in sequence on the back side of the silicon substrate; A phosphorus doping treatment is performed to convert the first amorphous silicon layer into a first doped polysilicon layer, and the second amorphous silicon layer into a second doped polysilicon layer, and part of the antimony element in the silicon substrate is diffused into the first tunneling oxide layer, the first doped polysilicon layer, the second tunneling oxide layer and the second doped polysilicon layer, and the doping concentration of the antimony element in the second tunneling oxide layer is higher than the doping concentration of the antimony element in the first doped polysilicon layer.

[0014] In this embodiment, by doping the silicon substrate with antimony elements, the antimony elements in the silicon substrate can overflow into the laminated structure, significantly improving the passivation effect of the laminated structure, and making the antimony elements in the laminated structure have certain concentration gradient characteristics, and can also improve the conductivity of carriers, thereby reducing the series resistance of the solar cell and improving the working efficiency of the solar cell. At the same time, by doping the silicon substrate with antimony elements, when the phosphorus doping treatment is subsequently performed, the antimony elements in the silicon substrate can automatically overflow into the laminated structure under the influence of high temperature during the phosphorus doping treatment and form certain concentration gradient characteristics, which can not only meet the use requirements, but also simplify the preparation method of the solar cell and reduce the difficulty of preparation.

[0015] In a specific embodiment, during the phosphorus doping treatment, the method for preparing the solar cell specifically includes: the temperature during the phosphorus doping treatment is 850° C.-900° C.

[0016] In a specific embodiment, when a silicon substrate is prepared so that the silicon substrate contains antimony, the method for preparing a solar cell further comprises: the antimony doping concentration of the silicon substrate is 5.427×10 16 cm -3 to 2.042×10 18 cm -3 . BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. 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 paying creative labor.

[0018] Figure 1 A schematic diagram of the structure of a solar cell provided in this application in a specific embodiment; Figure 2 A schematic diagram of the structure of a semi-finished solar cell generated during the preparation process of the solar cell provided in this application; Figure 3 for Figure 2 Schematic diagram of the structure of a solar cell after phosphorus doping treatment; Figure 4 for Figure 1 Diagram of the antimony concentration gradient in the solar cell.

[0019] Reference numerals: 1- Solar cell; 11- silicon substrate; 12-Laminated structure; 121- a first tunnel oxide layer; 122-a first doped polysilicon layer; 123- a second tunneling oxide layer; 124-a second doped polysilicon layer; 13-a first amorphous silicon layer; 14- a second amorphous silicon layer; 15-metal electrode; 16- passivation layer; 17-Emitter. DETAILED DESCRIPTION

[0020] 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.

[0021] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0022] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" 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 other meanings.

[0023] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0024] With the growing demand for renewable energy, solar cells have received widespread attention as an efficient and clean way of energy conversion. As a new type of solar cell technology, TOPCon cells have the advantages of high conversion efficiency, low attenuation performance, and high mass production cost-effectiveness, and are widely used in the photovoltaic power generation industry. TOPCon cells effectively reduce interface recombination losses and improve the open circuit voltage and fill factor of the cell by introducing an ultra-thin tunneling oxide layer and a polysilicon layer on the back of the cell. However, TOPCon cells are usually prepared on pure phosphorus-doped N-type silicon wafers, which results in limited carrier conductivity and poor conductivity in the TOPCon cell structure, and will result in higher series resistance and lower fill factor, resulting in lower working efficiency of TOPCon cells.

[0025] To solve the above technical problems, Figure 1 As shown, the present application provides a solar cell 1 and a method for preparing the solar cell 1. The solar cell 1 may include a silicon substrate 11 and a stacked structure 12. The stacked structure 12 is arranged on the back of the silicon substrate 11 along the thickness direction of the solar cell 1. The silicon substrate 11 and the stacked structure 12 contain antimony elements. The stacked structure 12 at least includes a first tunneling oxide layer 121, a first doped polysilicon layer 122, a second tunneling oxide layer 123, and a second doped polysilicon layer 124 stacked in sequence along the thickness direction of the solar cell 1. The doping concentration of the antimony element in the second tunneling oxide layer 123 is higher than the doping concentration of the antimony element in the first doped polysilicon layer 122.

[0026] In this embodiment, when the silicon substrate 11 of the solar cell 1 contains antimony, the antimony can overflow into the laminated structure 12 to a certain extent, and the antimony overflowing into the laminated structure 12 can form a bond with the silicon element to avoid the formation of voids in the laminated structure 12, which can effectively improve the passivation effect, solve the problem of low carrier conductivity, and improve the working efficiency of the solar cell 1. And the antimony doping concentration of the second tunneling oxide layer 123 in the laminated structure 12 is higher than the antimony doping concentration of the first doped polysilicon layer 122, even if the laminated structure 12 has a certain concentration gradient characteristic along the thickness direction of the solar cell 1, the conductivity of the carriers in the laminated structure 12 can be further improved, thereby reducing the series resistance of the solar cell 1, improving the fill factor and open circuit voltage of the solar cell 1, and further improving the working efficiency of the solar cell 1. At the same time, since the absorption and blocking effect of the second tunneling oxide layer 123 on the antimony element is stronger than that of the first doped polysilicon layer 122, the second tunneling oxide layer 123 can also block most of the antimony elements from continuing to diffuse away from the silicon substrate 11 to maintain the passivation effect.

[0027] The solar cell 1 in the above embodiment may be a TOPCon cell, such as Figure 1 As shown, for a TOPCon cell, along its thickness direction, the TOPCon cell may include a metal electrode 15, a passivation layer 16, an emitter 17, a silicon substrate 11, a stacked structure 12, a passivation layer 16 and a metal electrode 15 in sequence. The stacked structure 12 may include at least a first tunneling oxide layer 121, a first doped polysilicon layer 122, a second tunneling oxide layer 123 and a second doped polysilicon layer 124, so that the back of the solar cell 1 is composed of a tunneling oxide layer and a doped polysilicon layer, and the two can form a passivation contact structure together. This structure can block the recombination of minority carriers and holes and increase the open circuit voltage of the solar cell 1.

[0028] Specifically, the tunneling oxide layer can allow majority electrons to tunnel into the doped polysilicon layer while blocking minority hole recombination, and has a good passivation effect. The doped polysilicon layer can induce band bending, thereby forming a field passivation effect. The probability of electron tunneling is greatly increased, the contact resistance is reduced, and the open circuit voltage of the solar cell 1 is improved, thereby improving the photoelectric conversion efficiency of the solar cell 1.

[0029] In addition, compared with the related art in which the stacked structure of the solar cell only includes one tunneling oxide layer and one doped polysilicon layer, the stacked structure of the solar cell 1 in the embodiment of the present application can be provided with two tunneling oxide layers and two polysilicon layers, which can further enhance the passivation effect of the solar cell 1, thereby further enhancing the working efficiency of the solar cell 1.

[0030] In other embodiments, three tunneling oxide layers and three polysilicon layers (not shown in the figure) may be provided in the stacked structure of the solar cell, which can further improve the working efficiency of the solar cell. In the embodiment of the present application, the specific number of tunneling oxide layers and polysilicon layers in the stacked structure of the solar cell is not limited and can be adjusted according to actual conditions.

[0031] In the above embodiment, Figures 1 to 3 As shown, the preparation method of the battery cell 1 may include but is not limited to the following steps: S11: preparing a silicon substrate 11, wherein the silicon substrate 11 contains antimony element; S12: forming a first tunneling oxide layer 121, a first amorphous silicon layer 13, a second tunneling oxide layer 123 and a second amorphous silicon layer 14 in sequence on the back side of the silicon substrate 11; S13: Perform phosphorus doping treatment to transform the first amorphous silicon layer 13 into a first doped polysilicon layer 122, and the second amorphous silicon layer 14 into a second doped polysilicon layer 124, and part of the antimony element in the silicon substrate 11 diffuses into the first tunneling oxide layer 121, the first doped polysilicon layer 122, the second tunneling oxide layer 123 and the second doped polysilicon layer 124, and the doping concentration of the antimony element in the second tunneling oxide layer 123 is higher than the doping solubility of the antimony element in the first doped polysilicon layer 122.

[0032] In this embodiment, by doping the silicon substrate 11 with antimony elements, the antimony elements in the silicon substrate 11 can overflow into the laminated structure 12, significantly improving the passivation effect of the laminated structure 12, and making the antimony elements in the laminated structure 12 have certain concentration gradient characteristics, and can also improve the conductivity of carriers, thereby reducing the series resistance of the solar cell 1 and improving the working efficiency of the solar cell 1. At the same time, by doping the silicon substrate 11 with antimony elements, when the phosphorus doping treatment is subsequently performed, the antimony elements in the silicon substrate 11 can automatically overflow into the laminated structure 12 under the influence of high temperature during the phosphorus doping treatment and form certain concentration gradient characteristics, which can not only meet the use requirements, but also simplify the preparation method of the solar cell 1 and reduce the difficulty of preparation.

[0033] In a specific embodiment, Figure 1 and Figure 4 As shown, the doping concentrations of antimony elements in the first tunnel oxide layer 121 , the first doped polysilicon layer 122 , the second tunnel oxide layer 123 and the second doped polysilicon layer 124 may be different.

[0034] In this embodiment, the doping concentrations of antimony elements in the first tunneling oxide layer 121, the first doped polysilicon layer 122, the second tunneling oxide layer 123, and the second doped polysilicon layer 124 are all different, so that the antimony elements between the various structural layers of the stacked structure 12 have concentration gradient characteristics, which can further increase the conductivity of carriers in the stacked structure 12, reduce the series resistance of the solar cell 1, and increase the fill factor of the solar cell 1, improve the open circuit voltage, and thus improve the working efficiency of the solar cell 1. At the same time, since the first tunneling oxide layer 121, the first doped polysilicon layer 122, the second tunneling oxide layer 123, and the second doped polysilicon layer 124 in the stacked structure 12 are distributed along the thickness direction of the solar cell 1, in the process of the antimony element in the silicon substrate 11 overflowing, the doping concentration of the antimony element in each structural layer in the stacked structure 12 can automatically form a trend of gradually decreasing, so that the doping concentrations of the antimony element in the four structural layers of the stacked structure 12 are all different.

[0035] In a specific embodiment, Figure 1 and Figure 4 As shown, the antimony doping concentration in the first tunnel oxide layer 121 may be higher than that in the first doped polysilicon layer 122 , and the antimony doping concentration in the second tunnel oxide layer 123 may be higher than that in the second doped polysilicon layer 124 .

[0036] In this embodiment, the first tunnel oxide layer 121 and the second tunnel oxide layer 123 are used to provide high-quality chemical passivation to passivate the surface defects of the silicon substrate 11. Therefore, the antimony doping concentration in the first tunnel oxide layer 121 is higher than the antimony doping concentration in the first doped polysilicon layer 122, and the antimony doping concentration in the second tunnel oxide layer 123 is higher than the antimony doping concentration in the second doped polysilicon layer 124. Even if the antimony element in the stacked structure 12 is mainly enriched in the first tunnel oxide layer 121 and the second tunnel oxide layer 123, the antimony element can occupy the vacancies in the first tunnel oxide layer 121 and the second tunnel oxide layer 123, reduce the cross-sectional defects of the first tunnel oxide layer 121 and the second tunnel oxide layer 123, and improve the passivation effect. At the same time, the first tunnel oxide layer 121 and the second tunnel oxide layer 123 are enriched with more antimony elements, which can reduce the diffusion depth of the phosphorus element diffused into the stacked structure 12 in the subsequent phosphorus diffusion process, and widen the process window. At the same time, the tunnel oxide layer and the doped polysilicon layer can have a doping concentration gradient characteristic of antimony element, thereby improving the conductivity of carriers.

[0037] In a specific embodiment, Figure 1 and Figure 4As shown, the antimony doping concentration in the first tunnel oxide layer 121 may be higher than the antimony doping concentration in the second tunnel oxide layer 123 , and the antimony doping concentration in the second tunnel oxide layer 123 may be higher than the antimony doping concentration in the silicon substrate 11 .

[0038] In this embodiment, the antimony element doping concentration in the second tunneling oxide layer 123 is made higher than the antimony element doping concentration in the silicon substrate 11, even if the antimony element doping concentrations in the first tunneling oxide layer 121 and the second tunneling oxide layer 123 are both higher than the antimony element doping concentration in the silicon substrate 11, thereby further enriching the antimony element in the first tunneling oxide layer 121 and the second tunneling oxide layer 123, thereby significantly improving the passivation effect of the first tunneling oxide layer 121 and the second tunneling oxide layer 123.

[0039] In the above embodiment, Figure 1 and Figure 4 As shown, the solar cell 1 can satisfy at least one of the following conditions: the antimony doping concentration in the first tunnel oxide layer 121 is 5.0×10 16 -2.0×10 18 cm -3 The doping concentration of antimony in the second tunnel oxide layer 123 is 5.0×10 16 -2.0×10 18 cm -3 The antimony doping concentration in the first doped polysilicon layer 122 is 2.0×10 16 -6.0×10 16 cm -3 The antimony doping concentration in the second doped polysilicon layer 124 is 1.0×10 16 -2.0×10 16 cm -3 .

[0040] In the present embodiment, the antimony doping concentration of the first tunneling oxide layer 121, the first doped polysilicon layer 122, the second tunneling oxide layer 123, and the second doped polysilicon layer 124 meets the above requirements. While each structural layer in the stacked structure 12 contains antimony elements, the passivation effect of the stacked structure 12 is effectively improved. At the same time, a certain concentration gradient characteristic can be provided between the first tunneling oxide layer 121, the first doped polysilicon layer 122, the second tunneling oxide layer 123, and the second doped polysilicon layer 124, thereby further improving the conductivity of carriers in the stacked structure 12 and improving the working efficiency of the solar cell 1.

[0041] In the above embodiment, Figure 1 and Figure 4 As shown, step S13 may further specifically include: S131: perform phosphorus doping treatment at a temperature of 850°C-900°C.

[0042] In this embodiment, during the phosphorus doping process of the solar cell 1, the high temperature can simultaneously cause the antimony element in the silicon substrate 11 to overflow into the laminated structure 12. Therefore, the temperature during the phosphorus doping process is set at 850°C-900°C. At the same time, when the silicon substrate 11 is prepared, the doping concentration of the antimony element in the silicon substrate 11 satisfies 5.427×10 16 cm -3 to 2.042×10 18 cm -3 , thereby facilitating the control of the concentration of the antimony element overflowing into the stacked structure 12 to meet the use requirements of the solar cell 1 .

[0043] In addition, compared with the phosphorus doping treatment in the related art, the phosphorus impurity deposition treatment before the phosphorus doping treatment in the embodiment of the present application can first be carried out in a large nitrogen environment (i.e., an environment using pure nitrogen as a diluent gas) at a temperature of 800°C-880°C and a time of 200s-400s, thereby providing a driving force for the antimony element in the silicon substrate 11 to diffuse, so that the antimony element in the silicon substrate 11 can be subsequently diffused into the laminated structure 12, thereby improving the conductivity of the carriers in the laminated structure 12, so as to improve the working efficiency of the solar cell 1. In the above embodiment, if Figures 1 to 3 As shown, step S12 may further specifically include: S121: performing LPCVD treatment on the silicon substrate 11 by using a water vapor method to form a first tunnel oxide layer 121; S122: performing LPCVD treatment on the first tunnel oxide layer 121 to form a first amorphous silicon layer 13; S123: performing LPCVD treatment on the first amorphous silicon layer 13 by using a water vapor method to form a second tunnel oxide layer 123; S124 : performing LPCVD treatment on the second tunnel oxide layer 123 to form a second amorphous silicon layer 14 .

[0044] In this embodiment, the semi-finished solar cell prepared by the above steps includes a silicon substrate 11, a first tunneling oxide layer 121, a first amorphous silicon layer 13, a second tunneling oxide layer 123, and a second amorphous silicon layer 14 stacked in sequence along the thickness direction of the solar cell 1. In the subsequent phosphorus doping process, the high temperature annealing effect of the phosphorus doping process will convert the first amorphous silicon layer 13 into a first doped polycrystalline silicon layer 122, and the second amorphous silicon layer 14 into a second doped polycrystalline silicon layer 124. At the same time, the antimony element in the silicon substrate 11 will also overflow into the stacked structure under the action of high temperature, thereby forming a passivated stacked structure with excellent passivation effect and good contact performance. And by setting two tunneling oxide layers and two doped polycrystalline silicon layers in the solar cell 1, the passivation effect can be further improved, so as to achieve the effect of significantly improving the working efficiency of the solar cell 1.

[0045] In the above embodiment, Figure 1 As shown, the first doped polysilicon layer 122 and the second doped polysilicon layer 124 may further include a phosphorus-containing layer.

[0046] In this embodiment, the silicon substrate 11 also contains phosphorus. After the phosphorus doping treatment, the phosphorus in the silicon substrate 11 can diffuse into the first doped polysilicon layer 122 and the second doped polysilicon layer 124, so that both of them also include a phosphorus-containing layer. At the same time, by setting the antimony element in the silicon substrate 11, during the phosphorus doping process, the antimony element in the silicon substrate 11 can also overflow into the stacked structure 12, forming more effective doping, further improving the passivation effect, and reducing the diffusion depth of the phosphorus element during the phosphorus doping process, thereby reducing the time for the phosphorus impurity to advance and making the relative impurity level lower. Compared with the solar cell containing phosphorus in the related art, the solar cell doped with phosphorus and antimony can also increase the open circuit voltage to improve the working efficiency of the solar cell 1.

[0047] The phosphorus doping concentration in the first doped polysilicon layer 122 and the second doped polysilicon layer 124 may be 1.0×10 19 -5.0×10 20 cm -3 .

[0048] In the above embodiment, Figure 1 As shown, the solar cell 1 can meet at least one of the following conditions: the thickness L1 of the first tunneling oxide layer 121 is 1nm-2nm, the thickness L2 of the first doped polysilicon layer 122 is 100nm-200nm, the thickness L3 of the second tunneling oxide layer 123 is 1nm-2nm, and the thickness L4 of the second doped polysilicon layer 124 is 100nm-200nm.

[0049] In the present embodiment, when the stacked structure 12 includes two tunneling oxide layers and two doped polysilicon layers, the first tunneling oxide layer 121, the first doped polysilicon layer 122, the second tunneling oxide layer 123 and the second doped polysilicon layer 124 meet the above-mentioned thickness range. While improving the passivation effect of the stacked structure 12, it can also avoid the overall thickness of the stacked structure 12 being too large, which leads to the thickness of the solar cell 1 being too large, affecting the normal installation or use of the solar cell 1, and causing the solar cell 1 to have poor portability.

[0050] In the above embodiment, Figure 1 and Figure 4 As shown, the solar cell 1 can meet at least one of the following conditions: the antimony element doping concentration in the first tunneling oxide layer 121 gradually increases from the side facing the silicon substrate 11 to the side away from the silicon substrate 11, the antimony element doping concentration in the first doped polysilicon layer 122 first decreases and then increases from the side facing the silicon substrate 11 to the side away from the silicon substrate 11, the antimony element doping concentration in the second tunneling oxide layer 123 gradually decreases from the side facing the silicon substrate 11 to the side away from the silicon substrate 11, and the antimony element doping concentration in the second doped polysilicon layer 124 gradually decreases from the side facing the silicon substrate 11 to the side away from the silicon substrate 11.

[0051] In this embodiment, the antimony doping concentrations in the first tunneling oxide layer 121, the first doped polysilicon layer 122, the second tunneling oxide layer 123 and the second doped polysilicon layer 124 are all different, so that a certain antimony element concentration gradient characteristic can be formed between different structural layers of the stacked structure 12. At the same time, the doping concentrations of the antimony element in the first tunneling oxide layer 121, the first doped polysilicon layer 122, the second doped oxide layer 123 and the second doped polysilicon layer 124 vary along the thickness direction of the solar cell 1, so that each structural layer in the stacked structure 12 itself has a certain antimony element concentration gradient characteristic, further improving the conductivity of the carriers, thereby further improving the working efficiency of the solar cell 1.

[0052] In a specific embodiment, as shown in Table 1 below, solar cell A is a solar cell 1 provided in the embodiment of the present application, which is made of a silicon wafer doped with phosphorus and antimony as a silicon substrate 11, and the laminated structure 12 contains antimony elements. Solar cell B is a solar cell provided in the related art, which is made of a silicon wafer of pure phosphorus as a silicon substrate. The silicon substrates used in solar cell A and solar cell B have the same thickness and resistivity, and are made by the same process.

[0053] In this embodiment, the test results of solar cell A and solar cell B are shown in Table 1 below. Compared with solar cell B, the open circuit voltage of solar cell A increases by 0.003V, the short circuit current decreases by 0.016A, the fill factor increases by 0.26%, and the series resistance decreases by -0.00023Ω. In summary, the overall working efficiency of solar cell A is improved by 0.157% compared with solar cell B. It can be seen that compared with solar cell B using a pure phosphorus-doped silicon substrate in the related art, the solar cell A (i.e., solar cell 1) provided in the embodiment of the present application has a higher working efficiency.

[0054] Table 1

[0055] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A solar cell, characterized in that: The solar cell (1) comprises a silicon substrate (11) and a laminated structure (12); along the thickness direction of the solar cell (1), the laminated structure (12) is arranged on the back side of the silicon substrate (11); the silicon substrate (11) and the laminated structure (12) contain antimony elements; The stacked structure (12) comprises at least a first tunneling oxide layer (121), a first doped polysilicon layer (122), a second tunneling oxide layer (123) and a second doped polysilicon layer (124) which are sequentially stacked along the thickness direction of the solar cell (1); the antimony doping concentration in the second tunneling oxide layer (123) is higher than the antimony doping concentration in the first doped polysilicon layer (122).

2. The solar cell according to claim 1, characterized in that The antimony doping concentrations in the first tunneling oxide layer (121), the first doped polysilicon layer (122), the second tunneling oxide layer (123) and the second doped polysilicon layer (124) are all different.

3. The solar cell according to claim 2, characterized in that: The antimony doping concentration in the first tunneling oxide layer (121) is higher than the antimony doping concentration in the first doped polysilicon layer (122), and the antimony doping concentration in the second tunneling oxide layer (123) is higher than the antimony doping concentration in the second doped polysilicon layer (124).

4. The solar cell according to claim 3, characterized in that: The antimony doping concentration in the first tunneling oxide layer (121) is higher than the antimony doping concentration in the second tunneling oxide layer (123), and the antimony doping concentration in the second tunneling oxide layer (123) is higher than the antimony doping concentration in the silicon substrate (11).

5. The solar cell according to any one of claims 1 to 4, characterized in that: The solar cell (1) satisfies at least one of the following conditions: the antimony doping concentration in the first tunnel oxide layer (121) is 5.0×10 16 -2.0×10 18 cm -3 The antimony doping concentration in the second tunnel oxide layer (123) is 5.0×10 16 -2.0×10 18 cm -3 The antimony doping concentration in the first doped polysilicon layer (122) is 2.0×10 16 -6.0×10 16 cm -3 The antimony doping concentration in the second doped polysilicon layer (124) is 1.0×10 16 -2.0×10 16 cm -3 .

6. The solar cell according to any one of claims 1 to 4, characterized in that: The solar cell (1) satisfies at least one of the following conditions: a thickness L1 of the first tunneling oxide layer (121) is 1 nm-2 nm, a thickness L2 of the first doped polysilicon layer is 100 nm-200 nm, a thickness L3 of the second tunneling oxide layer (123) is 1 nm-2 nm, and a thickness L4 of the second doped polysilicon layer is 100 nm-200 nm.

7. The solar cell according to any one of claims 1 to 4, characterized in that: The solar cell (1) satisfies at least one of the following conditions: the antimony doping concentration in the first tunneling oxide layer (121) gradually increases from the side facing the silicon substrate (11) to the side away from the silicon substrate (11); the antimony doping concentration in the first doped polysilicon layer (122) first decreases and then increases from the side facing the silicon substrate (11) to the side away from the silicon substrate (11); the antimony doping concentration in the second tunneling oxide layer (123) gradually decreases from the side facing the silicon substrate (11) to the side away from the silicon substrate (11); and the antimony doping concentration in the second doped polysilicon layer (124) gradually decreases from the side facing the silicon substrate (11) to the side away from the silicon substrate (11).

8. A method for preparing a solar cell, characterized in that: The method for preparing the solar cell (1) comprises: Preparing a silicon substrate (11), wherein the silicon substrate (11) contains antimony elements; A first tunneling oxide layer (121), a first amorphous silicon layer (13), a second tunneling oxide layer (123) and a second amorphous silicon layer (14) are sequentially formed on the back side of the silicon substrate (11); A phosphorus doping treatment is performed to convert the first amorphous silicon layer (13) into a first doped polysilicon layer (122), and the second amorphous silicon layer (14) into a second doped polysilicon layer (124); a portion of the antimony element in the silicon substrate (11) is diffused into the first tunneling oxide layer (121), the first doped polysilicon layer (122), the second tunneling oxide layer (123) and the second doped polysilicon layer (124); and the doping concentration of the antimony element in the second tunneling oxide layer (123) is higher than the doping concentration of the antimony element in the first doped polysilicon layer (122).

9. The method for preparing a solar cell according to claim 8, characterized in that: When the phosphorus doping treatment is performed, the method for preparing the solar cell (1) specifically comprises: The temperature during the phosphorus doping treatment is 850° C.-900° C.

10. The method for preparing a solar cell according to claim 9, characterized in that: When the silicon substrate (11) is prepared so that the silicon substrate (11) contains antimony, the method for preparing the solar cell (1) further comprises: the antimony doping concentration of the silicon substrate (11) is 5.427×10 16 cm -3 to 2.042×10 18 cm -3 .

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