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. The silicon substrate and the laminated structure contain the antimony element, and 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. 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 doping concentrations of antimony elements in the first tunneling oxide layer, the first doped polycrystalline silicon layer, the second tunneling oxide layer and the second doped polycrystalline silicon layer are different, so that the antimony elements among the structural layers of the laminated structure have concentration gradient characteristics, and the conductivity of carriers in the laminated structure is further improved.

Description

[0001] This application is a divisional application of a patent application with an application date of March 17, 2025, an application number of 202510316679.3, and an invention title of "A Solar Cell and a Preparation Method Thereof". Technical Field

[0002] This application relates to the technical field of photovoltaic cells, and particularly to a solar cell and a preparation method thereof. Background Art

[0003] With the continuous growth of the demand for renewable energy, solar cells, as an efficient and clean energy conversion method, have received extensive attention. As a new type of solar cell technology, TOPCon cells have advantages such as 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 a pure phosphorus-doped N-type silicon wafer substrate, resulting in limited carrier conductivity in the TOPCon cell structure, poor conductivity, and affecting the working efficiency of TOPCon cells. Summary of the Invention

[0004] This application provides a solar cell and a preparation method thereof to facilitate solving the technical problem of low carrier conductivity in the battery structure in the prior art.

[0005] In a first aspect, an embodiment of this application provides a solar cell, which includes a silicon substrate and a stacked structure; along the thickness direction of the solar cell, the stacked structure is disposed on the back surface of the silicon substrate; the silicon substrate and the stacked structure contain antimony elements; wherein, the stacked structure at least includes a first tunneling oxide layer, a first doped polysilicon layer, a second tunneling oxide layer, and a second doped polysilicon layer that are sequentially stacked along the thickness direction of the solar cell; 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.

[0006] In this embodiment, by doping antimony elements in the silicon substrate, the antimony elements in the silicon substrate can overflow into the stacked structure, significantly improving the passivation effect of the stacked structure, and enabling the antimony elements in the stacked structure to have a certain concentration gradient characteristic, and also capable of enhancing the carrier conductivity, thereby reducing the series resistance of the solar cell and improving the working efficiency of the solar cell.

[0007] Meanwhile, 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, so that there is a concentration gradient characteristic of antimony elements between the structural layers of the stacked structure, which can further increase the conductivity of carriers in the stacked structure, reduce the series resistance of the solar cell, and increase the fill factor of the solar cell and improve the open-circuit voltage, thereby improving the working efficiency of the solar cell. At the same time, since the first tunneling oxide layer, the first doped polysilicon layer, the second tunneling oxide layer, and the second doped polysilicon layer in the stacked structure are distributed along the thickness direction of the solar cell, during the process of antimony element overflow in the silicon substrate, the doping concentrations of antimony elements in the structural layers of the stacked structure can automatically form a gradually decreasing trend, so that the doping concentrations of antimony elements in the four structural layers of the stacked structure are all different.

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

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

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

[0012] 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 1 nm - 2 nm, the thickness L2 of the first doped polysilicon layer is 100 nm - 200 nm, the thickness L3 of the second tunneling oxide layer is 1 nm - 2 nm, and the thickness L4 of the second doped polysilicon layer is 100 nm - 200 nm.

[0013] In a specific embodiment, the solar cell satisfies at least one of the following conditions: the doping concentration of antimony element in the first tunneling oxide layer gradually increases from the side facing the silicon substrate to the side away from the silicon substrate, the doping concentration of antimony element in the first doped polysilicon layer first decreases and then increases from the side facing the silicon substrate to the side away from the silicon substrate, the doping concentration of antimony element 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 doping concentration of antimony element in the second doped polysilicon layer gradually decreases from the side facing the silicon substrate to the side away from the silicon substrate.

[0014] In a second aspect, an embodiment of the present application provides a method for manufacturing a solar cell, and the method for manufacturing the solar cell includes:

[0015] Preparing a silicon substrate containing antimony element;

[0016] Successively forming a first tunneling oxide layer, a first amorphous silicon layer, a second tunneling oxide layer, and a second amorphous silicon layer on the back surface of the silicon substrate;

[0017] Performing a phosphorus doping treatment 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 diffuses 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 concentrations of antimony element 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.

[0018] In this embodiment, by doping antimony elements into the silicon substrate, the antimony elements in the silicon substrate can overflow into the stacked structure, significantly improving the passivation effect of the stacked structure, and enabling the antimony elements in the stacked structure to have a certain concentration gradient characteristic. It can also improve the conductivity of carriers, thereby reducing the series resistance of the solar cell and enhancing the working efficiency of the solar cell. At the same time, 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, enabling the antimony elements between the structural layers of the stacked structure to all have a concentration gradient characteristic, so as to further increase the conductivity of carriers in the stacked structure. In addition, by doping antimony elements into the silicon substrate, during the subsequent phosphorus doping process, the antimony elements in the silicon substrate can automatically overflow into the stacked structure under the influence of high temperature during the phosphorus doping process and form a certain concentration gradient characteristic. While meeting the usage requirements, it can also simplify the preparation method of the solar cell and reduce the preparation difficulty.

[0019] In a specific embodiment, before the phosphorus doping process, the preparation method of the solar cell specifically includes:

[0020] Under a large nitrogen environment, perform a constant temperature treatment on the silicon substrate at a temperature of 800°C - 880°C for a time of 200s - 400s;

[0021] During the phosphorus doping process, the preparation method of the solar cell specifically includes: the temperature during the phosphorus doping process is 850°C - 900°C.

[0022] In a specific embodiment, when preparing the silicon substrate to make the silicon substrate contain antimony elements, the preparation method of the solar cell further includes: the doping concentration of antimony elements in the silicon substrate is 5.427×10 16 cm -3 to 2.042×10 18 cm -3 . BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 It is a schematic structural diagram of the solar cell provided by the present application in a specific embodiment;

[0025] Figure 2 It is a schematic structural diagram of the semi-finished solar cell generated during the preparation process of the solar cell provided by the present application;

[0026] Figure 3 is Figure 2 The schematic structural diagram of the solar cell after phosphorus doping treatment;

[0027] Figure 4 is Figure 1 The concentration gradient diagram of antimony element in the solar cell.

[0028] Reference numerals:

[0029] 1 - Solar cell;

[0030] 11 - Silicon substrate;

[0031] 12 - Stacked structure;

[0032] 121 - First tunneling oxide layer;

[0033] 122 - First doped polysilicon layer;

[0034] 123 - Second tunneling oxide layer;

[0035] 124 - Second doped polysilicon layer;

[0036] 13 - First amorphous silicon layer;

[0037] 14 - Second amorphous silicon layer;

[0038] 15 - Metal electrode;

[0039] 16 - Passivation layer;

[0040] 17 - Emitter. Detailed implementation manners

[0041] In order to better understand the technical solutions of the present application, the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0042] It should be clear that the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts belong to the scope of protection of the present application.

[0043] 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 of "a", "the" and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0044] It should be understood that the term "and / or" used herein is merely 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 simultaneously, 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.

[0045] With the continuous growth of the demand for renewable energy, solar cells, as an efficient and clean energy conversion method, have received extensive attention. As a new type of solar cell technology, TOPCon cells have advantages such as high conversion efficiency, low attenuation performance, and high mass production cost performance, and are widely used in the photovoltaic power generation industry. TOPCon cells effectively reduce the interface recombination loss and improve the open-circuit voltage and fill factor of the cells 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 a purely phosphorus-doped N-type silicon wafer, resulting in limited carrier conductivity, poor conductivity in the TOPCon cell structure, and effects of high series resistance and low fill factor, leading to a low working efficiency of TOPCon cells.

[0046] To solve the above technical problems, as Figure 1 shown, this application provides a solar cell 1 and a preparation method of the solar cell 1. The solar cell 1 may include a silicon substrate 11 and a stacked structure 12. Along the thickness direction of the solar cell 1, the stacked structure 12 is disposed on the back surface of the silicon substrate 11, and the silicon substrate 11 and the stacked structure 12 contain antimony elements. Among them, 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 that are sequentially stacked along the thickness direction of the solar cell 1. And the doping concentration of antimony elements in the second tunneling oxide layer 123 is higher than the doping concentration of antimony elements in the first doped polysilicon layer 122.

[0047] In this embodiment, when the silicon substrate 11 of the solar cell 1 contains antimony, the antimony can overflow to the stacked structure 12 to a certain extent. The antimony that overflows to the stacked structure 12 can bond with silicon, avoiding the formation of voids in the stacked structure 12, effectively improving the passivation effect, solving the problem of low carrier conductivity, and improving the working efficiency of the solar cell 1. Moreover, the antimony doping concentration in the second tunneling oxide layer 123 in the stacked structure 12 is higher than that in the first doped polysilicon layer 122, that is, the stacked structure 12 has a certain concentration gradient characteristic along the thickness direction of the solar cell 1, which can further improve the carrier conductivity in the stacked structure 12, 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 second tunneling oxide layer 123 has a stronger absorption and blocking effect on antimony than the first doped polysilicon layer 122, the second tunneling oxide layer 123 can also block most of the antimony from continuing to diffuse away from the silicon substrate 11 to maintain the passivation effect.

[0048] The solar cell 1 in the above embodiment can be a TOPCon cell. For example, Figure 1 As shown, for a TOPCon cell, along its thickness direction, the TOPCon cell can sequentially 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. The stacked structure 12 can at least include 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 surface of the solar cell 1 is composed of a tunneling oxide layer and a doped polysilicon layer, and the two can jointly form a passivated contact structure. This structure can block the recombination of minority carrier holes and improve the open circuit voltage of the solar cell 1.

[0049] Specifically, the tunneling oxide layer can enable majority carrier electrons to tunnel into the doped polysilicon layer while blocking the recombination of minority carrier holes, having a good passivation effect. The doped polysilicon layer can induce band bending, thereby forming a field passivation effect. The probability of electron tunneling increases significantly, the contact resistance decreases, the open circuit voltage of the solar cell 1 is improved, and thus the photoelectric conversion efficiency of the solar cell 1 is improved.

[0050] In addition, compared with the stacked structure of a solar cell in the related art that 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 improve the passivation effect of the solar cell 1, thereby further improving the working efficiency of the solar cell 1.

[0051] In other embodiments, three tunneling oxide layers and three polysilicon layers (not shown in the figure) may also be provided in the stacked structure of the solar cell, which can further improve the working efficiency of the solar cell. In the embodiments of the present application, the specific number of tunneling oxide layers and polysilicon layers provided in the stacked structure of the solar cell is not limited and can be adjusted according to actual situations.

[0052] In the above embodiments, as Figures 1 to 3 shown, the preparation method of the battery chip 1 may include but is not limited to the following steps:

[0053] S11: Prepare the silicon substrate 11, and the silicon substrate 11 contains antimony elements;

[0054] S12: Sequentially form 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 on the back surface of the silicon substrate 11;

[0055] S13: Perform phosphorus doping treatment 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, and part of the antimony elements in the silicon substrate 11 diffuse 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 antimony elements in the second tunneling oxide layer 123 is higher than the solubility of antimony elements in the first doped polysilicon layer 122.

[0056] In this embodiment, by doping antimony elements in the silicon substrate 11, the antimony elements in the silicon substrate 11 can overflow into the stacked structure 12, significantly improving the passivation effect of the stacked structure 12, and enabling the antimony elements in the stacked structure 12 to have a certain concentration gradient characteristic, and also improving 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 antimony elements in the silicon substrate 11, during the subsequent phosphorus doping treatment, the antimony elements in the silicon substrate 11 can automatically overflow into the stacked structure 12 under the influence of high temperature during the phosphorus doping treatment and form a certain concentration gradient characteristic, which can simplify the preparation method of the solar cell 1 and reduce the preparation difficulty while meeting the usage requirements.

[0057] In a specific embodiment, as Figure 1 and Figure 4 shown, 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 may all be different.

[0058] 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 there is a concentration gradient feature of antimony elements between the structural layers of the stacked structure 12, which can further increase the conductivity of carriers in the stacked structure 12, reduce the series resistance of the solar cell 1, and can increase the fill factor of the solar cell 1 and improve the open-circuit voltage, thereby improving 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, during the process of antimony element overflow in the silicon substrate 11, the doping concentrations of antimony elements in each structural layer of the stacked structure 12 can automatically form a gradually decreasing trend, so that the doping concentrations of antimony elements in the four structural layers of the stacked structure 12 are all different.

[0059] In a specific embodiment, as Figure 1 and Figure 4 shown, the doping concentration of antimony element in the first tunneling oxide layer 121 can be higher than that in the first doped polysilicon layer 122, and the doping concentration of antimony element in the second tunneling oxide layer 123 can be higher than that in the second doped polysilicon layer 124.

[0060] In this embodiment, the first tunneling oxide layer 121 and the second tunneling oxide layer 123 are used to provide high-quality chemical passivation to passivate the surface defects of the silicon substrate 11. Therefore, making the doping concentration of antimony element in the first tunneling oxide layer 121 higher than that in the first doped polysilicon layer 122, and making the doping concentration of antimony element in the second tunneling oxide layer 123 higher than that in the second doped polysilicon layer 124, even if the antimony element in the stacked structure 12 is mainly enriched in the first tunneling oxide layer 121 and the second tunneling oxide layer 123, so that the antimony element can occupy the vacancies in the first tunneling oxide layer 121 and the second tunneling oxide layer 123, reduce the cross-sectional defects of the first tunneling oxide layer 121 and the second tunneling oxide layer 123, and improve the passivation effect. At the same time, making the first tunneling oxide layer 121 and the second tunneling oxide layer 123 enrich more antimony elements can reduce the diffusion depth of the phosphorus element diffused into the stacked structure 12 during the subsequent phosphorus diffusion process and broaden the process window. At the same time, it can also make the doping concentration gradient feature of antimony element between the tunneling oxide layer and the doped polysilicon layer, and improve the conductivity of carriers.

[0061] In a specific embodiment, as Figure 1 and Figure 4As shown, the doping concentration of antimony in the first tunneling oxide layer 121 can be higher than that in the second tunneling oxide layer 123, and the doping concentration of antimony in the second tunneling oxide layer 123 can be higher than that in the silicon substrate 11.

[0062] In this embodiment, making the doping concentration of antimony in the second tunneling oxide layer 123 higher than that in the silicon substrate 11, that is, making the doping concentrations of antimony in the first tunneling oxide layer 121 and the second tunneling oxide layer 123 both higher than that in the silicon substrate 11, so that antimony is further enriched in the first tunneling oxide layer 121 and the second tunneling oxide layer 123, significantly improving the passivation effect of the first tunneling oxide layer 121 and the second tunneling oxide layer 123.

[0063] In the above embodiment, as Figure 1 and Figure 4 shown, the solar cell 1 can meet at least one of the following conditions: the doping concentration of antimony in the first tunneling oxide layer 121 is 5.0×10 16 -2.0×10 18 cm -3 , the doping concentration of antimony in the second tunneling oxide layer 123 is 5.0×10 16 -2.0×10 18 cm -3 , the doping concentration of antimony in the first doped polysilicon layer 122 is 2.0×10 16 -6.0×10 16 cm -3 , the doping concentration of antimony in the second doped polysilicon layer 124 is 1.0×10 16 -2.0×10 16 cm -3 .

[0064] In this embodiment, making the doping concentrations of antimony 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 meet the above requirements, while making each structural layer in the stacked structure 12 contain antimony, effectively improving the passivation effect of the stacked structure 12, and also enabling a certain concentration gradient characteristic 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, further improving the conductivity of carriers in the stacked structure 12 to improve the working efficiency of the solar cell 1.

[0065] In the above embodiment, as Figure 1 and Figure 4 shown, step S13 may further specifically include:

[0066] S131: Perform phosphorus doping treatment at a temperature of 850°C - 900°C.

[0067] In this embodiment, during the preparation of the solar cell 1, when performing phosphorus doping treatment, the high temperature can simultaneously cause the antimony element in the silicon substrate 11 to overflow into the stacked structure 12. Therefore, the temperature during phosphorus doping treatment is 850°C - 900°C. At the same time, when preparing the silicon substrate 11, 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 , so as to facilitate the control of the concentration of the antimony element overflowing into the stacked structure 12 to meet the usage requirements of the solar cell 1.

[0068] In addition, compared with the phosphorus doping treatment in the related art, when performing phosphorus impurity deposition treatment before the phosphorus doping treatment in the embodiment of the present application, a constant temperature treatment can be first performed at a temperature of 800°C - 880°C and a time of 200s - 400s in a large nitrogen environment (that is, an environment using pure nitrogen as a dilution gas), so as to give the driving force for the diffusion of the antimony element in the silicon substrate 11, so as to facilitate the subsequent diffusion of the antimony element in the silicon substrate 11 into the stacked structure 12, thereby improving the conductivity of the carriers in the stacked structure 12 and improving the working efficiency of the solar cell 1. In the above embodiment, as Figures 1 to 3 shown, step S12 may specifically include:

[0069] S121: Perform LPCVD treatment on the silicon substrate 11 using the water vapor method to form the first tunneling oxide layer 121;

[0070] S122: Perform LPCVD treatment on the first tunneling oxide layer 121 to form the first amorphous silicon layer 13;

[0071] S123: Perform LPCVD treatment on the first amorphous silicon layer 13 using the water vapor method to form the second tunneling oxide layer 123;

[0072] S124: Perform LPCVD treatment on the second tunneling oxide layer 123 to form the second amorphous silicon layer 14.

[0073] In this embodiment, the semi-finished solar cell prepared through 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 that are sequentially stacked along the thickness direction of the solar cell 1. During 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 polysilicon layer 122 and the second amorphous silicon layer 14 into a second doped polysilicon 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 passivation stacked structure with excellent passivation effect and good contact performance. And by setting two tunneling oxide layers and two doped polysilicon layers in the solar cell 1, the passivation effect can be further improved to significantly improve the working efficiency of the solar cell 1.

[0074] In the above embodiment, as Figure 1 shown, the first doped polysilicon layer 122 and the second doped polysilicon layer 124 may further include a phosphorus-containing layer.

[0075] In this embodiment, the silicon substrate 11 also contains phosphorus element. After the phosphorus doping process, the phosphorus element 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. While forming more effective doping and further improving the passivation effect, it can also reduce the diffusion depth of the phosphorus element during the phosphorus doping process, thereby reducing the time of phosphorus impurity propulsion and making the relative impurity level lower. And compared with the solar cell containing only phosphorus element in the related technology, the solar cell doped with both phosphorus element and antimony element can also increase the open circuit voltage to improve the working efficiency of the solar cell 1.

[0076] Among them, the phosphorus doping concentration in the first doped polysilicon layer 122 and the second doped polysilicon layer 124 can be 1.0×10 19 -5.0×10 20 cm -3 .

[0077] In the above embodiment, as Figure 1 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 1 nm - 2 nm, the thickness L2 of the first doped polysilicon layer 122 is 100 nm - 200 nm, the thickness L3 of the second tunneling oxide layer 123 is 1 nm - 2 nm, and the thickness L4 of the second doped polysilicon layer 124 is 100 nm - 200 nm.

[0078] In this 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 are made to satisfy the above thickness range. While improving the passivation effect of the stacked structure 12, it can also prevent the overall thickness of the stacked structure 12 from being too large, which may lead to an excessive thickness of the solar cell 1, affecting the normal installation or use of the solar cell 1 and resulting in poor portability of the solar cell 1.

[0079] In the above embodiment, as Figure 1 and Figure 4 shown, the solar cell 1 can satisfy at least one of the following conditions: the doping concentration of antimony 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 doping concentration of antimony 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 doping concentration of antimony 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; the doping concentration of antimony 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.

[0080] In this embodiment, the doping concentrations of antimony 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 antimony 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 change 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 carriers and thus further improving the working efficiency of the solar cell 1.

[0081] In a specific embodiment, as shown in Table 1 below, the solar cell A is the solar cell 1 provided in the embodiment of the present application, which is made of a silicon wafer doped with phosphorus and antimony as the silicon substrate 11, and the stacked structure 12 contains antimony. The solar cell B is a solar cell provided in the related art, which is made of a silicon wafer doped with pure phosphorus as the silicon substrate. The thickness and resistivity of the silicon substrates used in the solar cell A and the solar cell B are the same, and they are made by the same process.

[0082] 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 0.003 V, the short-circuit current decreases by 0.016 A, the fill factor increases by 0.26%, and the series resistance decreases by -0.00023 Ω. 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 the solar cell B using a silicon substrate doped with pure phosphorus 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.

[0083] Table 1

[0084]

[0085] The foregoing is only a 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 changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within 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 stacked in sequence along the thickness direction of the solar cell (1); 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.

2. The solar cell according to claim 1, 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).

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 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).

4. The solar cell according to any one of claims 1 to 3, 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 second doped polysilicon layer (124) is 1.0×10 16 -2.0×10 16 cm -3 .

5. The solar cell according to any one of claims 1 to 3, 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 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 3, characterized in that: The solar cell (1) satisfies at least one of the following conditions: the thickness L1 of the first tunneling oxide layer (121) is 1 nm-2 nm, the thickness L2 of the first doped polysilicon layer is 100 nm-200 nm, the thickness L3 of the second tunneling oxide layer (123) is 1 nm-2 nm, and the 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 3, 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 element; 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); 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); part 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 concentrations of the antimony element 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.

9. The method for preparing a solar cell according to claim 8, characterized in that: Before the phosphorus doping treatment is performed, the preparation method of the solar cell (1) specifically comprises: In a nitrogen atmosphere, the silicon substrate (11) is subjected to a constant temperature treatment at a temperature of 800° C. to 880° C. for a time of 200 seconds to 400 seconds; 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 and 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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