Solar cell, method of manufacturing the same, stacked cell, and photovoltaic module

Abstract

The embodiment of the present application relates to the photovoltaic field, and provides a solar cell, a preparation method thereof, a laminated cell and a photovoltaic module, and the preparation method of the solar cell comprises the following steps: providing a silicon substrate; performing boron doping on the silicon substrate at a first preset temperature to form a boron-doped layer, wherein the first preset temperature is 700-800 DEG C; and activating boron atoms in the boron-doped layer by using a plasma source at a second preset temperature to obtain a boron diffusion layer, wherein the second preset temperature is 850-900 DEG C. The preparation method of the solar cell provided by the embodiment of the present application can at least improve the yield of the solar cell.

Description

Technical Field

[0001] This application relates to the photovoltaic field, and in particular to a solar cell, a method for preparing a solar cell, a tandem cell, and a photovoltaic module. Background Technology

[0002] Traditional boron diffusion push-junction processes rely primarily on high-temperature thermal diffusion, which typically requires heating the silicon wafer to temperatures exceeding 950°C. At such high temperatures, the silicon wafer undergoes significant thermal stress changes, leading to warping and reduced cell yield.

[0003] Secondly, during the high-temperature diffusion process, the surface doping concentration is difficult to control precisely, easily leading to the formation of a high-concentration "dead layer" on the silicon wafer surface. The presence of this "dead layer" not only reduces the photoelectric conversion efficiency of the solar cell but also adversely affects the minority carrier lifetime. Minority carrier lifetime is an important parameter for measuring the quality of solar cells, directly affecting the open-circuit voltage and short-circuit current, and thus impacting the overall efficiency.

[0004] In addition, the boron source used in traditional boron diffusion push-junction processes is usually a liquid boron source such as boron tribromide (BBr3). Although it can provide the necessary boron atoms, its high toxicity and strong corrosiveness pose a serious threat to operators and equipment.

[0005] In summary, traditional boron diffusion push-junction processes have significant drawbacks in terms of high temperature, surface concentration control, and boron source selection. These drawbacks limit the development of solar cells, affect their photoelectric performance, and increase environmental and economic costs during manufacturing. Therefore, a new method for fabricating solar cells is urgently needed to at least address the technical problem that the high-temperature process of traditional boron diffusion push-junction processes causes silicon wafer warping, thereby reducing wafer yield. Summary of the Invention

[0006] This application provides a solar cell, a method for preparing a solar cell, a tandem cell, and a photovoltaic module, which at least helps to improve the yield of solar cells.

[0007] According to some embodiments of this application, one aspect of this application provides a method for preparing a solar cell, including providing a silicon substrate; doping the silicon substrate with boron at a first preset temperature to form a boron-doped layer, the first preset temperature being 700~800℃; and activating boron atoms in the boron-doped layer with a plasma source at a second preset temperature to obtain a boron diffusion layer, the second preset temperature being 850~900℃.

[0008] In some embodiments, after the step of boron doping the silicon substrate at a first preset temperature to form a boron-doped layer and before the step of activating the boron atoms in the boron-doped layer with a plasma source at a second preset temperature to obtain a boron diffusion layer, the method for preparing a solar cell further includes: raising the temperature from the first preset temperature to the second preset temperature at a fixed slope for a time of 5 to 10 minutes.

[0009] In some embodiments, the step of boron doping a silicon substrate to form a boron-doped layer at a first preset temperature includes: placing the silicon substrate in a plasma chamber; and injecting a boron source gas and a carrier gas into the plasma chamber at the first preset temperature to form a boron-doped layer.

[0010] In some embodiments, the method for fabricating a solar cell further includes: providing a boron nitride plate; heating the boron nitride plate to generate a boron source gas.

[0011] In some embodiments, the method for fabricating a solar cell further includes: after placing a silicon substrate into a plasma chamber and before injecting boron source gas and carrier gas into the plasma chamber at a first preset temperature to form a boron-doped layer, evacuating the plasma chamber to make the pressure inside the plasma chamber 100-500 mbar; after injecting boron source gas and carrier gas into the plasma chamber at the first preset temperature to form a boron-doped layer and before activating boron atoms in the boron-doped layer with a plasma source at a second preset temperature to obtain a boron diffusion layer, evacuating the plasma chamber again to make the pressure inside the plasma chamber 600-1000 mbar.

[0012] In some embodiments, the step of injecting boron source gas and carrier gas into a plasma chamber at a first preset temperature to form a boron-doped layer includes: an injection step, in which boron source gas at a first preset gas flow rate and carrier gas at a second preset gas flow rate are injected into the plasma chamber at the first preset temperature, the ratio of the first preset gas flow rate to the second preset gas flow rate being (1:5) to (1:10); a purging step, in which, after a first preset time of injection of boron source gas and carrier gas, an inert gas is introduced into the plasma chamber to purge the plasma chamber, the first preset time being 15 to 25 minutes; and the injection step and the purging step are repeated at least once until a boron-doped layer of a preset thickness is formed.

[0013] In some embodiments, the carrier gas includes nitrogen and oxygen, with oxygen accounting for 1% to 5% of the carrier gas.

[0014] In some embodiments, the flow rate of the boron source gas is 200-300 sccm, the flow rate of the nitrogen gas is 1500-2500 sccm, and the flow rate of the oxygen gas is 20-80 sccm.

[0015] In some embodiments, a boron diffusion layer is obtained by activating boron atoms in the doped layer with a plasma source at a second preset temperature, including: injecting working gas into a plasma chamber at a second preset temperature, a preset plasma power, and a preset excitation frequency; and obtaining the boron diffusion layer after a second preset time of injecting the working gas, wherein the preset plasma power is 200~400W, the preset excitation frequency is one of 13.56MHz, 27.12MHz, and 40.68MHz, and the second preset time is 10~15min.

[0016] In some embodiments, the working gas is nitrogen and silane, and the gas flow rate ratio of nitrogen to silane is (1:3) to (1:5).

[0017] In some embodiments, the total gas flow rate of the working gas is 500 sccm to 1000 sccm, the gas flow rate of nitrogen is 83 to 250 sccm, and the gas flow rate of silane is 375 to 833 sccm.

[0018] According to some embodiments of this application, another aspect of this application provides a solar cell including a boron diffusion layer, which is formed by any of the above-described methods for preparing a solar cell.

[0019] In some embodiments, the thickness of the silicon substrate of the solar cell is 100~150μm, the junction depth of the boron diffusion layer is 0.3~0.5μm, and the doping concentration of the boron diffusion layer is 1e19~1e20 atoms / cm³.

[0020] According to some embodiments of this application, another aspect of this application provides a tandem battery, including: a bottom battery, which includes a solar cell as described above; and a top battery located on one side of the bottom battery.

[0021] According to some embodiments of this application, another aspect of this application provides a photovoltaic module, including: a battery string, which is formed by connecting multiple solar cells as described above, or by connecting multiple stacked cells as described above; an encapsulating film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulating film facing away from the battery string.

[0022] The technical solution provided in this application has at least the following advantages:

[0023] This application provides a method for fabricating a solar cell, comprising: providing a silicon substrate; doping the silicon substrate with boron at a first preset temperature to form a boron-doped layer; and activating boron atoms in the boron-doped layer using a plasma source at a second preset temperature to obtain a boron diffusion layer. The first preset temperature is 700-800℃, and the second preset temperature is 850-900℃. It is evident that this application, by controlling the temperature in stages and utilizing a lower temperature for pre-diffusion, reduces the influence of hot carriers during the formation of the boron-doped layer. This not only forms a shallow junction (junction depth less than 0.5 μm) in the silicon substrate but also significantly reduces the thermal stress on the silicon substrate during boron diffusion, avoiding excessive thermal deformation. This effectively reduces the risk of silicon wafer warpage and improves the wafer processing yield. Subsequently, the boron atoms in the boron-doped layer are activated by the plasma source at a higher temperature. This allows for more uniform diffusion of boron atoms even at temperatures lower than those of traditional high-temperature diffusion processes, resulting in a boron diffusion layer with the required doping depth and concentration (a "shallow junction high concentration" boron diffusion layer). This improves the controllability of the boron doping process, effectively avoids the formation of "dead layers," thereby increasing minority carrier lifetime and improving the photoelectric performance of solar cells. Attached Figure Description

[0024] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the drawings in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart illustrating a method for fabricating a solar cell according to an embodiment of this application. Detailed Implementation

[0026] As is known from the background art, traditional boron diffusion push-junction processes have significant drawbacks in terms of high temperature, surface concentration control, and boron source selection. These drawbacks limit the development of solar cells, affect their photoelectric performance, and increase environmental and economic costs during manufacturing. Therefore, to at least address the technical problem that the high-temperature process of traditional boron diffusion push-junction processes causes silicon wafer warping in solar cells, thereby reducing wafer yield, this application provides a method for fabricating a solar cell, a solar cell, a tandem cell, and a photovoltaic module.

[0027] In some embodiments, such as Figure 1As shown, this application provides a method for fabricating a solar cell, the method comprising:

[0028] S1, Provides a silicon substrate;

[0029] S2. The silicon substrate is boron doped at a first preset temperature to form a boron doped layer. The first preset temperature is 700~800℃.

[0030] S3. At a second preset temperature, the boron atoms in the boron doped layer are activated by a plasma source to obtain a boron diffusion layer. The second preset temperature is 850~900℃.

[0031] In the above embodiments, the formation process of the boron diffusion layer includes a first stage of boron diffusion at a first preset temperature and a second stage of boron diffusion at a second preset temperature. The first preset temperature of the first stage is lower than the second preset temperature of the second stage, and both the first and second preset temperatures are lower than the high temperatures of conventional boron diffusion push-junction processes. Therefore, the technical solution provided by the embodiments of this application has at least the following advantages: by controlling the temperature in stages and using a lower temperature for pre-diffusion, the influence of hot carriers is reduced during the formation of the boron doped layer. This not only forms a shallow junction (junction depth less than 0.5 μm) in the silicon substrate but also significantly reduces the thermal stress on the silicon substrate during the boron diffusion process, avoiding excessive thermal deformation, thereby effectively reducing the risk of silicon wafer warpage and improving the wafer processing yield. Subsequently, the boron atoms in the boron-doped layer are activated by the plasma source at a higher temperature. This allows for more uniform diffusion of boron atoms even at temperatures lower than those of traditional high-temperature diffusion processes, resulting in a boron diffusion layer with the required doping depth and concentration (a "shallow junction high concentration" boron diffusion layer). This improves the controllability of the boron doping process, effectively avoids the formation of "dead layers," thereby increasing minority carrier lifetime and improving the photoelectric performance of solar cells.

[0032] Furthermore, in the above embodiments, setting the first preset temperature to greater than or equal to 700°C ensures that boron atoms can begin an effective diffusion process on the silicon substrate surface; setting the first preset temperature to less than or equal to 800°C reduces thermal stress and deformation caused by high temperature while forming the boron doped layer, and also helps to reduce the generation of hot carriers, avoid the formation of "dead layers," and improve minority carrier lifetime. Setting the second preset temperature to greater than or equal to 850°C ensures that the plasma activation process can proceed effectively, providing sufficient energy to boron atoms to activate them from the lattice position and further diffuse, optimizing the doping depth and concentration; setting the second preset temperature to less than or equal to 900°C balances the activation effect and material stability, promoting boron atom activation and sufficient diffusion while avoiding degradation of the silicon substrate or other materials caused by excessively high temperatures.

[0033] After employing the solar cell fabrication method described in this application, the warpage of the silicon wafer (silicon substrate) can be controlled within 50 μm to 70 μm. Specifically, after the first stage and before the second stage, the warpage of the silicon wafer can be 30 μm to 40 μm, and after the second stage, the warpage can be 10 μm to 30 μm. Since there is a positive correlation between silicon wafer warpage and silicon wafer fragmentation rate—that is, the smaller the silicon wafer warpage, the smaller the silicon wafer fragmentation rate—this application can reduce the silicon wafer fragmentation rate to within 0.5% to 1%, thus significantly improving the silicon wafer yield.

[0034] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0035] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0036] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0037] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0038] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0039] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0040] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0041] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on / located" on another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may be present therein. Moreover, when a component such as a layer, film, region, or plate is "directly located" on another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it indicates that no other components are located therein.

[0042] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "part" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0043] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0044] Optionally, the first preset temperature is selected from any temperature value between 700℃ and 800℃. For example, the first preset temperature is one of 700℃, 705℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, 780℃, 790℃, and 800℃.

[0045] Optionally, the second preset temperature is selected from any temperature value between 850 and 900°C. For example, the second preset concentration is one of 850°C, 855°C, 860°C, 865°C, 870°C, 880°C, 890°C, and 900°C.

[0046] In some optional embodiments, after the step of boron doping the silicon substrate at a first preset temperature to form a boron-doped layer and before the step of activating the boron atoms in the boron-doped layer with a plasma source at a second preset temperature to obtain a boron diffusion layer, the method for preparing the solar cell further includes: raising the temperature from the first preset temperature to the second preset temperature at a fixed slope for a time of 5 to 10 minutes.

[0047] In the above embodiments, during the process of raising the temperature from the first preset temperature to the second preset temperature at a fixed slope, on the one hand, the temperature change from the first preset temperature to the second preset temperature can be linear. This helps the silicon substrate gradually adapt to the temperature change, reduces thermal stress caused by rapid heating, further reduces the risk of silicon wafer warping, and thus further improves the wafer processing yield. On the other hand, it allows the diffusion rate of boron atoms in the silicon substrate to gradually increase, rather than suddenly accelerating at high temperatures. This helps to form a more uniform boron doped layer, avoiding the problem of uneven or excessively deep boron concentration distribution caused by instantaneous diffusion at high temperatures. This further controls the depth and surface concentration of the diffusion layer, avoiding the formation of a "dead layer." Furthermore, by controlling the heating time to be greater than or equal to 5 minutes, a temperature gradient is formed, promoting the smooth diffusion of boron atoms; by controlling the heating time to be less than or equal to 10 minutes, a stable thermal environment can be provided for the plasma source to activate boron atoms, and while ensuring entry into the plasma activation stage, the production cycle is shortened, and production costs and energy consumption are reduced.

[0048] Optionally, the heating time is selected from any time value between 5 min and 10 min. For example, the heating time is one of 5 min, 5.5 min, 6 min, 7 min, 8 min, 9 min, and 10 min.

[0049] For example, when the first preset temperature is 750°C, the second preset temperature is 880°C, and the heating time is 8 minutes, the heating rate from the first preset temperature to the second preset temperature is 16.25°C / min.

[0050] In some optional embodiments, the step of boron doping the silicon substrate at a first preset temperature to form a boron-doped layer includes: placing the silicon substrate in a plasma chamber; and injecting boron source gas and carrier gas into the plasma chamber at the first preset temperature to form the boron-doped layer.

[0051] In the above embodiments, the use of a plasma chamber provides a purer doping environment, which is beneficial for improving doping precision. Furthermore, after forming the boron-doped layer, the boron atoms in the layer can be activated within the same chamber. This allows for the pre-diffusion of boron atoms and subsequent high-temperature activation to be completed within the same chamber, achieving process integration, reducing the transfer of silicon wafers between different devices, lowering the risk of contamination and damage, simplifying production line layout, and improving processing efficiency and production flexibility.

[0052] In this process, the boron source gas is heated and decomposed in the plasma chamber, releasing boron atoms. The carrier gas can uniformly transport the boron atoms to the silicon substrate surface, thereby ensuring the uniformity and controllability of boron doping.

[0053] Optionally, the carrier gas is a mixture of nitrogen and oxygen. Nitrogen provides the primary inert protection and diffusion medium, while oxygen promotes the decomposition of the boron source gas, surface passivation, and participates in plasma formation.

[0054] Optionally, the raw material for the aforementioned boron source gas can be a solid boron source. Compared to traditional liquid boron sources, using solid boron sources can reduce toxicity and corrosiveness during operation, which is beneficial to the health of operators and the long-term stable operation of equipment.

[0055] For example, the solid boron source described above can be boron nitride. In some optional embodiments, the method for fabricating the solar cell further includes: providing a boron nitride plate; and heating the boron nitride plate to generate the boron source gas.

[0056] In the above embodiments, a boron nitride plate is used as a solid boron source, avoiding the safety and corrosion problems associated with liquid boron sources. Heating the boron nitride plate converts the solid boron nitride into a gaseous state, increasing the activity of the boron nitride molecules. This ensures that the boron nitride molecules are more easily and effectively decomposed into boron atoms in the plasma chamber. Consequently, the boron atoms are uniformly dispersed within the plasma chamber under the influence of the carrier gas, ensuring a more uniform distribution of boron atoms on the silicon wafer surface.

[0057] In some optional embodiments, the method for fabricating the solar cell further includes: after placing the silicon substrate into the plasma chamber and before injecting boron source gas and carrier gas into the plasma chamber at the first preset temperature to form the boron doped layer, evacuating the plasma chamber to make the pressure inside the plasma chamber 100~500 mbar; after injecting boron source gas and carrier gas into the plasma chamber at the first preset temperature to form the boron doped layer and before activating the boron atoms in the boron doped layer with a plasma source at a second preset temperature to obtain a boron diffusion layer, evacuating the plasma chamber again to make the pressure inside the plasma chamber 600~1000 mbar.

[0058] In the above embodiments, before forming the boron-doped layer, evacuating the plasma chamber removes impurity gases, providing a clean environment for subsequent boron diffusion and thus improving the quality of the boron-doped layer. After forming the boron-doped layer, evacuating the plasma chamber removes unreacted or diffused gases from the formation process. This optimizes the gas environment for the plasma activation step, preventing the generation of unnecessary byproducts at subsequent high temperatures and ensuring the accuracy of subsequent processes and product quality.

[0059] Specifically, the evacuation of the plasma chamber before the step of forming the boron-doped layer can be considered as the first evacuation; the evacuation of the plasma chamber after the step of forming the boron-doped layer and before the step of activating the boron atoms in the boron-doped layer with a plasma source at a second preset temperature can be considered as the second evacuation.

[0060] In the above embodiments, setting the pressure inside the plasma chamber after the first vacuum evacuation to greater than or equal to 100 mbar ensures the purity of the environment within the plasma chamber and reduces the impact of impurities on the subsequent boron diffusion process. Setting the pressure inside the plasma chamber after the first vacuum evacuation to less than or equal to 500 mbar facilitates uniform diffusion of boron atoms. Setting the pressure inside the plasma chamber after the second vacuum evacuation to greater than or equal to 600 mbar is beneficial for generating high-quality plasma and improving the activation efficiency of boron atoms. Setting the pressure inside the plasma chamber after the second vacuum evacuation to less than or equal to 1000 mbar helps to prevent over-excitation during the activation of boron atoms in the boron doped layer, which could lead to efficiency degradation or damage to the battery structure.

[0061] Optionally, the pressure inside the plasma chamber after the first vacuum is selected from any pressure value between 100 and 500 mbar. For example, the pressure inside the plasma chamber after the first vacuum is one of 100 mbar, 120 mbar, 150 mbar, 200 mbar, 300 mbar, 400 mbar, and 500 mbar.

[0062] Optionally, the pressure inside the plasma chamber after the second evacuation is selected from any pressure value between 600 and 1000 mbar. For example, the pressure inside the plasma chamber after the second evacuation is one of 600 mbar, 610 mbar, 620 mbar, 630 mbar, 650 mbar, 700 mbar, 800 mbar, 900 mbar, and 1000 mbar.

[0063] In some optional embodiments, the step of injecting boron source gas and carrier gas into the plasma chamber at the first preset temperature to form the boron-doped layer includes: an injection step, injecting boron source gas at a first preset gas flow rate and carrier gas at a second preset gas flow rate into the plasma chamber at the first preset temperature, wherein the ratio of the first preset gas flow rate to the second preset gas flow rate is (1:5) to (1:10); a purging step, after injecting the boron source gas and carrier gas for a first preset time, introducing an inert gas into the plasma chamber to purge the plasma chamber, wherein the first preset time is 15 to 25 minutes; repeating the injection step and the purging step at least once until the boron-doped layer of a preset thickness (preset junction depth) is formed.

[0064] The flow rate ratio of the boron source gas to the carrier directly affects the supply and diffusion rate of boron atoms on the silicon wafer surface. By setting the ratio of the first preset gas flow rate to the second preset gas flow rate, the deposition rate and depth of boron atoms on the silicon wafer surface can be controlled, achieving precise control over the thickness (junction depth) and surface concentration of the boron doped layer. In the above embodiment, setting the ratio of the first preset gas flow rate to the second preset gas flow rate to be greater than or equal to (1:5) ensures that the boron source gas can effectively contact the silicon substrate and undergo a diffusion reaction; setting the ratio of the first preset gas flow rate to the second preset gas flow rate to be less than or equal to (1:10) helps to maintain high production efficiency while ensuring the quality of the boron doped layer. Furthermore, setting the first preset duration to be greater than or equal to 15 minutes ensures that boron atoms have sufficient diffusion time to form the necessary doping concentration and depth; setting the first preset duration to be less than or equal to 25 minutes avoids excessive diffusion of boron atoms.

[0065] Furthermore, after injecting the boron source gas and carrier gas to form the boron-doped layer, some unreacted residual gases and byproducts may remain on the silicon wafer surface and within the plasma chamber. In this case, introducing an inert gas can completely remove these residual gases and byproducts through purging, ensuring that the plasma chamber is free of impurity gases and preventing residual gases and byproducts from reacting with silicon again during subsequent plasma activation, thus affecting the quality of the resulting boron-diffused layer. Additionally, considering one injection step and one purging step consecutively as a cycle, the purging operation provides a clean working environment within the plasma chamber before the injection step of the next cycle, thereby ensuring the quality of the boron-doped layer.

[0066] Optionally, the ratio of the first preset gas flow rate and the second preset gas flow rate is selected from any ratio between (1:5) and (1:10). For example, the ratio of the first preset gas flow rate and the second preset gas flow rate is one of (1:5), (1:5.5), (1:6), (1:7), (1:8), (1:9), and (1:10).

[0067] Optionally, the first preset duration is selected from any one of 15 to 25 minutes. For example, the first preset duration is one of 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes, 20 minutes, 21 minutes, 22 minutes, 23 minutes, 24 minutes, and 25 minutes.

[0068] In some alternative embodiments, the carrier gas includes nitrogen and oxygen, wherein the oxygen accounts for 1% to 5% of the carrier gas.

[0069] In the above embodiments, oxygen can react with the boron source gas, reducing the activation energy required for the decomposition of the boron source gas, thereby accelerating the conversion of the boron source gas into boron atoms and nitrogen, providing more boron atoms for subsequent diffusion and plasma activation. Nitrogen, as an inert gas, provides a relatively stable reaction environment for the formation of the boron diffusion layer, reducing silicon wafer oxidation at high temperatures, protecting the silicon wafer surface from external contamination, and maintaining the cleanliness and activity of the silicon wafer. In the above embodiments, by setting the oxygen content in the carrier to greater than or equal to 1%, slight oxidation of the silicon substrate surface can be promoted, helping to control the junction depth and uniformity of the boron doped layer, preventing excessive diffusion of boron atoms into the silicon substrate, and improving passivation efficiency through the slightly oxidized oxide layer, reducing surface recombination, and enhancing battery performance. By setting the oxygen content in the carrier to less than or equal to 5%, excessive oxide layer formation can be prevented, ensuring the doping efficiency and quality of the boron doping layer.

[0070] Optionally, the proportion of oxygen in the carrier gas is selected from any percentage between 1% and 5%. For example, the proportion of oxygen in the carrier gas is one of 1%, 2%, 3%, 4%, and 5%.

[0071] In some optional embodiments, the flow rate of the boron source gas is 200-300 sccm, the flow rate of the nitrogen gas is 1500-2500 sccm, and the flow rate of the oxygen gas is 20-80 sccm.

[0072] In the above embodiments, setting the boron source gas flow rate to greater than or equal to 200 sccm ensures that sufficient boron atoms are received on the silicon substrate surface during the pre-diffusion stage to achieve the required doping concentration. Setting the boron source gas flow rate to less than or equal to 300 sccm prevents excessive boron atom supply, avoiding the formation of an excessively thick boron diffusion layer and preventing uneven deposition of boron atoms on the silicon wafer surface, thus avoiding the formation of a "dead layer." Setting the nitrogen gas flow rate to greater than or equal to 1500 sccm provides a good transport medium for the uniform distribution of boron atoms, ensuring the uniform diffusion of boron atoms across the entire silicon wafer surface. Setting the nitrogen gas flow rate to less than or equal to 2500 sccm helps to optimize cost control and energy efficiency while ensuring the diffusion effect of boron atoms across the entire silicon wafer surface. By setting the oxygen gas flow rate to greater than or equal to 20 sccm, sufficient oxygen molecules are ensured to participate in the initial decomposition of the boron source gas during the pre-diffusion stage, generating boron atoms and nitrogen. By setting the oxygen gas flow rate to less than or equal to 80 sccm, excessive oxygen can be prevented from causing excessive oxidation of the silicon wafer surface, which would affect the diffusion efficiency and doping efficiency of boron atoms.

[0073] Specifically, the flow rate of the boron source gas is the first preset gas flow rate. The sum of the flow rates of the nitrogen gas and the oxygen gas is the second preset gas flow rate.

[0074] Optionally, the flow rate of the boron source gas is selected from any one of the values ​​between 200 sccm and 300 sccm. For example, the flow rate of the boron source gas is one of 200 sccm, 210 sccm, 220 sccm, 230 sccm, 240 sccm, 250 sccm, 260 sccm, 270 sccm, 280 sccm, 290 sccm, and 300 sccm.

[0075] Optionally, the nitrogen gas flow rate is selected from any one of the gas flow rates between 1500 and 2500 sccm. For example, the nitrogen gas flow rate is one of 1500 sccm, 1600 sccm, 1700 sccm, 1800 sccm, 1900 sccm, 2000 sccm, 2100 sccm, 2200 sccm, 2300 sccm, 2400 sccm, and 2500 sccm.

[0076] Optionally, the oxygen gas flow rate is selected from any gas flow rate value between 20 and 80 sccm. For example, the oxygen gas flow rate is one of 20 sccm, 30 sccm, 40 sccm, 50 sccm, 60 sccm, 70 sccm, and 80 sccm.

[0077] In some optional embodiments, the boron atoms in the doped layer are activated by a plasma source at a second preset temperature to obtain a boron diffusion layer, including: injecting a working gas into the plasma chamber at the second preset temperature, a preset plasma power, and a preset excitation frequency; and obtaining the boron diffusion layer after injecting the working gas for a second preset time, wherein the preset plasma power is 200~400W, the preset excitation frequency is one of 13.56MHz, 27.12MHz, and 40.68MHz, and the second preset time is 10~15min.

[0078] High-energy particles in the plasma can disrupt the binding energy threshold between boron and silicon atoms, making it easier for boron atoms to be incorporated into the silicon lattice and form an electrically active boron diffusion layer. In the above embodiment, the binding process of boron atoms with silicon crystals is faster and more efficient under the combined effects of a higher temperature (second preset temperature) and specific plasma conditions (preset plasma power and preset excitation frequency), thereby shortening the cycle of the entire boron diffusion process and improving production efficiency. Furthermore, maintaining the injection of the working gas for the second preset duration further ensures that, under plasma activation conditions, boron atoms have sufficient time to undergo deep diffusion and achieve the specified concentration distribution.

[0079] In the above embodiments, setting the preset plasma power to be greater than or equal to 200W ensures that the plasma can provide sufficient energy to activate boron atoms; setting the preset plasma power to be less than or equal to 400W prevents excessive plasma power from damaging the silicon substrate or the formed boron-doped layer. Setting the second preset duration to be greater than or equal to 10 minutes ensures that boron atoms are fully activated and diffused under sufficient energy; setting the second preset duration to be less than or equal to 15 minutes avoids over-activation or diffusion, preventing deterioration of battery performance.

[0080] Optionally, the preset plasma power is selected from any value between 200W and 400W. For example, the preset plasma power is one of 200W, 250W, 300W, 350W, and 400W.

[0081] Optionally, the second preset duration is selected from any duration between 10 min and 15 min. For example, the second preset duration is one of 10 min, 11 min, 12 min, 13 min, 14 min, and 15 min.

[0082] In some alternative embodiments, the working gas is nitrogen and silane, and the ratio of the flow rates of the nitrogen and silane is (1:3) to (1:5).

[0083] In the above embodiments, nitrogen and silane working gases create a plasma environment conducive to the activation and deep diffusion of boron atoms. Specifically, by setting the nitrogen to silane gas flow rate ratio to be greater than or equal to 1:3, the concentration of active species within the plasma chamber is ensured, thereby guaranteeing the opportunity for collisions between boron atoms and active species and improving the activation efficiency of boron atoms. By setting the nitrogen to silane gas flow rate ratio to be less than or equal to 1:5, the required silane concentration for the formation of the boron diffusion layer is ensured, while sufficient nitrogen is maintained to preserve the uniformity and stability of the plasma.

[0084] Optionally, the ratio of nitrogen to silane gas flow rates is any one of (1:3) to (1:5). For example, the ratio of nitrogen to silane gas flow rates is one of (1:3), (1:3.5), (1:4), (1:4.5), and (1:5).

[0085] Furthermore, the decomposition products of silane can form a passivation layer, thus protecting and optimizing the surface properties of the boron diffusion layer, improving its quality, and consequently enhancing the performance and reliability of the solar cell. Optionally, the passivation layer described above is a silicon nitride passivation layer.

[0086] In some optional embodiments, the total gas flow rate of the working gas is 500 sccm to 1000 sccm, the gas flow rate of the nitrogen is 83 to 250 sccm, and the gas flow rate of the silane is 375 to 833 sccm.

[0087] In the above embodiments, setting the total gas flow rate of the working gas to greater than or equal to 500 sccm ensures sufficient gas velocity in the plasma chamber, promoting uniform gas distribution and reaction, and forming a stable plasma, thus guaranteeing the quality of the boron doped layer. Setting the total gas flow rate of the working gas to less than or equal to 1000 sccm helps maintain the plasma within the plasma chamber, thereby helping to ensure the activation efficiency and doping depth of boron atoms. Setting the nitrogen gas flow rate in the working gas to greater than or equal to 83 sccm helps to uniformly diffuse silane gas onto the silicon wafer surface, ensuring the stability of the plasma environment. Setting the nitrogen gas flow rate in the working gas to less than or equal to 250 sccm maintains a high proportion of silane in the working gas, ensuring that enough silane decomposes to generate active substances to participate in the activation and diffusion reactions of boron atoms. By setting the silane gas flow rate in the working gas to be greater than or equal to 375 sccm, sufficient silicon source can be provided to generate enough active material for the activation of boron atoms. By setting the silane gas flow rate in the working gas to be less than or equal to 833 sccm, the gas flow rates of nitrogen and silane in the co-working gas can be balanced to optimize the plasma environment, improve the activation efficiency of boron atoms, and enhance the quality of the boron diffusion layer.

[0088] Optionally, the total gas flow rate of the working gas is selected from any gas flow rate value between 500 sccm and 1000 sccm. For example, the total gas flow rate of the working gas is one of 500 sccm, 600 sccm, 700 sccm, 800 sccm, 900 sccm, and 1000 sccm.

[0089] Optionally, the nitrogen gas flow rate is selected from any one of the gas flow rates from 83 sccm to 250 sccm. For example, the nitrogen gas flow rate is one of 83 sccm, 85 sccm, 90 sccm, 100 sccm, 120 sccm, 140 sccm, 160 sccm, 180 sccm, 200 sccm, 220 sccm, 240 sccm, and 250 sccm.

[0090] Optionally, the gas flow rate of the silane is selected from any gas flow rate value between 375 sccm and 833 sccm. For example, the gas flow rate of the silane is one of 375 sccm, 400 sccm, 450 sccm, 500 sccm, 550 sccm, 600 sccm, 650 sccm, 700 sccm, 750 sccm, 800 sccm, and 833 sccm.

[0091] For example, when the total gas flow rate of the working gas is 600 sccm, the gas flow rate of nitrogen in the working gas is 200 sccm and the gas flow rate of silane in the working gas is 400 sccm.

[0092] In some alternative embodiments, to further optimize the surface properties of the boron diffusion layer, the above-described solar cell fabrication method further includes forming a passivation layer on the surface of the boron diffusion layer using an in-situ deposition process. For example, the thickness of the passivation layer can be 80 nm.

[0093] In some optional embodiments, this application also provides a solar cell including a boron diffusion layer. The boron diffusion layer in this solar cell is formed using any of the solar cell fabrication methods described above.

[0094] It is understood that, since the solar cell in this embodiment includes a boron diffusion layer formed using any of the above-described solar cell fabrication methods, the silicon wafer of the solar cell in this embodiment has good quality, which improves the structural integrity and stability of the solar cell, thereby reducing the production cost of the solar cell. Furthermore, its boron diffusion layer is a shallow junction with a high doping concentration, which significantly improves the minority carrier lifetime compared to traditional solar cells, thereby improving the photoelectric conversion efficiency of the solar cell.

[0095] In some alternative embodiments, the thickness of the silicon substrate of the solar cell is 100~150μm, the junction depth of the boron diffusion layer is 0.3~0.5μm, and the doping concentration of the boron diffusion layer is 1e19~1e20 atoms / cm³.

[0096] In the above embodiments, this application can form a boron diffusion layer with a junction depth of 0.3 to 0.5 μm in a silicon substrate with a thickness of 100 to 150 μm, and make the doping concentration of the boron diffusion layer within 1e19 to 1e20 atoms / cm³. It can be seen that the thickness of the silicon substrate of the solar cell described in this application is thinner than that of conventional solar cells (above 180 μm). This application achieves "shallow junction, high concentration" doping in a thin silicon wafer. The shallow junction reduces light reflection and absorption loss, while the high concentration of boron doping optimizes carrier collection. The combination of these two factors enables the solar cell to maintain high photoelectric conversion efficiency over a wider spectral range.

[0097] In some alternative embodiments, this application also provides a tandem solar cell, which includes a bottom cell and a top cell located on one side of the bottom cell. The bottom cell includes any of the solar cells described above.

[0098] In the above embodiments, since the tandem battery includes any of the aforementioned solar cells, and each of the aforementioned solar cells includes a boron diffusion layer formed by the fabrication method of any of the aforementioned solar cells, this tandem battery, compared to conventional tandem batteries, ensures the structural integrity and stability of the tandem battery and improves the photoelectric conversion efficiency of the tandem battery, thereby improving the overall performance of the tandem battery.

[0099] Of course, in other alternative embodiments, the top cell may also include any of the solar cells described above.

[0100] In some optional embodiments, this application also provides a photovoltaic module, which includes a battery string, an encapsulating film for covering the surface of the battery string, and a cover plate for covering the surface of the encapsulating film facing away from the battery string. The battery string is formed by connecting multiple solar cells as described above, or by connecting multiple stacked cells as described above.

[0101] In the above embodiments, since the cell string of the photovoltaic module is made of any of the aforementioned solar cells, and each of the aforementioned solar cells includes a boron diffusion layer formed by the fabrication method of any of the aforementioned solar cells, this photovoltaic module, compared to conventional photovoltaic modules, has high-quality silicon wafers and cell layers. This means that the photovoltaic module has better durability under harsh environmental conditions. Furthermore, it includes solar cells with higher minority carrier lifetime and optimized photoelectric performance prepared using the above two-step method, thereby improving the conversion efficiency of the photovoltaic module.

[0102] Among them, the aforementioned solar cell can be a TOPCON cell.

[0103] Specifically, a TOPCON cell includes: a silicon substrate having opposing front and back sides; a boron diffusion layer, a front passivation layer, a front antireflection layer, and a front metal electrode located on the front side, wherein the front passivation layer is located on the side of the boron diffusion layer away from the silicon substrate, the front antireflection layer is located on the side of the front passivation layer away from the boron diffusion layer, and the front metal electrode penetrates through the front antireflection layer and the front passivation layer to the boron diffusion layer; the front passivation layer is an aluminum oxide layer, and the front antireflection layer is a silicon nitride layer; and a tunneling oxide layer, a doped polycrystalline silicon layer, a back antireflection layer, and a back metal electrode located on the back side, wherein the doped polycrystalline silicon layer is located on the side of the tunneling oxide layer away from the silicon substrate, the back antireflection layer is located on the side of the doped polycrystalline silicon layer away from the tunneling oxide layer, and the back metal electrode penetrates through the back antireflection layer to the doped polycrystalline silicon layer; the tunneling oxide layer is a silicon oxide layer, and the back passivation layer is a silicon nitride layer. Based on this TOPCON cell, the fabrication method of the solar cell of this application will be further described below with reference to embodiments and comparative examples.

[0104] Example 1

[0105] The fabrication method of the aforementioned TOPCON battery includes: providing a silicon substrate; doping the silicon substrate with boron at a first preset temperature to form a boron-doped layer; and activating the boron atoms in the boron-doped layer using a plasma source at a second preset temperature to obtain a boron diffusion layer. The first preset temperature is 700°C, and the second preset temperature is 880°C.

[0106] Example 2

[0107] The difference from Example 1 is that the first preset temperature is 750°C.

[0108] Example 3

[0109] The difference from Example 1 is that the first preset temperature is 800°C.

[0110] Example 4

[0111] The difference from Example 1 is that the second preset temperature is 850°C.

[0112] Example 5

[0113] The difference from Example 1 is that the second preset temperature is 900°C.

[0114] Example 6

[0115] The difference from Example 1 is that the heating time from the first preset temperature to the second preset temperature is 5 minutes.

[0116] Example 7

[0117] The difference from Example 1 is that the heating time from the first preset temperature to the second preset temperature is 8 minutes.

[0118] Example 8

[0119] The difference from Example 1 is that the heating time from the first preset temperature to the second preset temperature is 10 minutes.

[0120] Example 9

[0121] The difference from Example 1 is that: in the step of boron doping the silicon substrate at the first preset temperature to form a boron-doped layer, the pressure in the chamber where the silicon substrate is located before boron doping is 100 mbar; after the step of forming the boron-doped layer and before the step of activating the boron atoms in the boron-doped layer with a plasma source at the second preset temperature to obtain a boron diffusion layer, the pressure in the chamber where the silicon substrate is located is 800 mbar.

[0122] Example 10

[0123] The difference from Example 1 is that: in the step of boron doping the silicon substrate at the first preset temperature to form a boron-doped layer, the pressure in the chamber where the silicon substrate is located before boron doping is 300 mbar; after the step of forming the boron-doped layer and before the step of activating the boron atoms in the boron-doped layer with a plasma source at the second preset temperature to obtain a boron diffusion layer, the pressure in the chamber where the silicon substrate is located is 800 mbar.

[0124] Example 11

[0125] The difference from Example 1 is that: in the step of boron doping the silicon substrate at the first preset temperature to form a boron-doped layer, the pressure in the chamber where the silicon substrate is located before boron doping is 500 mbar; after the step of forming the boron-doped layer and before the step of activating the boron atoms in the boron-doped layer with a plasma source at the second preset temperature to obtain a boron diffusion layer, the pressure in the chamber where the silicon substrate is located is 800 mbar.

[0126] Example 12

[0127] The difference from Example 1 is that: in the step of boron doping the silicon substrate at the first preset temperature to form a boron-doped layer, the pressure in the chamber where the silicon substrate is located before boron doping is 500 mbar; after the step of forming the boron-doped layer and before the step of activating the boron atoms in the boron-doped layer with a plasma source at the second preset temperature to obtain a boron diffusion layer, the pressure in the chamber where the silicon substrate is located is 600 mbar.

[0128] Comparative Example

[0129] A method for fabricating a solar cell includes: providing a silicon substrate; and doping the silicon substrate with boron at a preset temperature to form a boron diffusion layer. The preset temperature is 950°C.

[0130] The electrical properties of the solar cells prepared by the methods described in the comparative examples and Examples 1 to 13 above were measured respectively, and Table 1 was obtained (wherein, the data in Table 1 is the average value after testing n cells for each example or comparative example):

[0131] Table 1

[0132]

[0133] As shown in Table 1, compared to the comparative solar cells, the solar cells fabricated using the method described in this application exhibit higher photoelectric conversion efficiency (Eta), higher open-circuit voltage (Uoc), larger short-circuit current (Isc), a fill factor closer to 1 (FF), lower series resistance (Rs), and larger parallel resistance (Rsh). Specifically, a higher Eta value means more light energy is converted into electrical energy, improving the solar cell's power generation efficiency; higher Uoc and Rsh values ​​indicate better potential and leakage current control, meaning the solar cell can maintain a more stable voltage output under different illumination conditions, enhancing system reliability and efficiency; a larger Isc and lower Rs value mean that under the same illumination, the solar cell can provide a stronger current output while reducing energy loss due to internal resistance, increasing the actual output power of the cell; and an FF value closer to 1 reflects the excellent performance of the solar cell at its maximum power point, resulting in more stable power output and improved overall power quality. In summary, this application improves the photoelectric performance of solar cells.

[0134] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0135] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A method for preparing a solar cell, characterized in that, include: Provide silicon substrate; The silicon substrate is placed in a plasma chamber, and boron doping and pre-diffusion are performed on the silicon substrate at a first preset temperature to form a boron doped layer. The first preset temperature is 700~800℃. The boron atoms in the boron-doped layer are activated by a plasma source at a second preset temperature of 850~900℃ to obtain a boron diffusion layer. The step of performing boron doping and pre-diffusion on the silicon substrate at a first preset temperature to form a boron-doped layer includes: Boron source gas and carrier gas are injected into the plasma chamber at a first preset temperature to form the boron doped layer; wherein, the raw material of the boron source gas includes a solid boron source; The step of activating boron atoms in the boron-doped layer with a plasma source at a second preset temperature to obtain a boron diffusion layer includes: Working gas is injected into the plasma chamber at the second preset temperature, preset plasma power, and preset excitation frequency. After the working gas is injected for a second preset time, the boron diffusion layer is obtained. The preset plasma power is 200~400W, the second preset time is 10~15min, and the preset excitation frequency is one of 13.56MHz, 27.12MHz, and 40.68MHz.

2. The method for preparing a solar cell according to claim 1, characterized in that, After the step of boron doping the silicon substrate at a first preset temperature to form a boron-doped layer, and before the step of activating the boron atoms in the boron-doped layer with a plasma source at a second preset temperature to obtain a boron diffusion layer, the method for fabricating the solar cell further includes: The first preset temperature is increased to the second preset temperature at a fixed slope, and the heating time is 5~10 minutes.

3. The method for preparing a solar cell according to claim 1, characterized in that, The method for preparing the solar cell further includes: Boron nitride plates are available. The boron nitride plate is heated to generate the boron source gas.

4. The method for preparing a solar cell according to claim 1, characterized in that, The method for preparing the solar cell further includes: After the step of placing the silicon substrate into the plasma chamber and before the step of injecting boron source gas and carrier gas into the plasma chamber at the first preset temperature to form the boron doped layer, the plasma chamber is evacuated so that the pressure inside the plasma chamber is 100~500mbar. After the step of injecting boron source gas and carrier gas into the plasma chamber at the first preset temperature to form the boron doped layer, and before the step of activating the boron atoms in the boron doped layer with a plasma source at the second preset temperature to obtain the boron diffusion layer, the plasma chamber is evacuated again to make the pressure inside the plasma chamber 600~1000mbar.

5. The method for preparing a solar cell according to claim 1, characterized in that, The step of injecting boron source gas and carrier gas into the plasma chamber at the first preset temperature to form the boron doped layer includes: In the injection step, at the first preset temperature, the boron source gas at a first preset gas flow rate and the carrier gas at a second preset gas flow rate are injected into the plasma chamber, wherein the ratio of the first preset gas flow rate to the second preset gas flow rate is (1:5) to (1:10). The purging step involves introducing an inert gas into the plasma chamber after injecting the boron source gas and the carrier gas for a first preset time, and purging the plasma chamber for a first preset time of 15 to 25 minutes. Repeat the infeeding step and the purging step at least once until the boron-doped layer of the predetermined thickness is formed.

6. The method for preparing a solar cell according to any one of claims 2 to 5, characterized in that, The carrier gas includes nitrogen and oxygen, with the oxygen accounting for 1% to 5% of the carrier gas.

7. The method of producing a solar cell according to claim 6, wherein The flow rate of the boron source gas is 200-300 sccm, the flow rate of the nitrogen gas is 1500-2500 sccm, and the flow rate of the oxygen gas is 20-80 sccm.

8. The method for preparing a solar cell according to claim 7, characterized in that, The working gas is nitrogen and silane, and the ratio of the flow rates of nitrogen and silane is (1:3) to (1:5).

9. The method for preparing a solar cell according to claim 8, characterized in that, The total gas flow rate of the working gas is 500 sccm to 1000 sccm, the gas flow rate of nitrogen is 83 to 250 sccm, and the gas flow rate of silane is 375 to 833 sccm.

10. A solar cell, characterized in that, It includes a boron diffusion layer, which is formed using the method for preparing a solar cell according to any one of claims 1 to 6.

11. The solar cell of claim 10, wherein, The thickness of the silicon substrate of the solar cell is 100~150μm, the junction depth of the boron diffusion layer is 0.3~0.5μm, and the doping concentration of the boron diffusion layer is 1e19~1e20atoms / cm³.

12. A stacked battery characterized by comprising: include: A bottom battery, said bottom battery comprising the solar cell as described in claim 10 or 11; The top battery is located on one side of the bottom battery.

13. A photovoltaic module, characterized in that, include: A battery string is formed by connecting multiple solar cells as described in claim 10 or 11, or by connecting multiple stacked cells as described in claim 12; An encapsulating film is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulating film that faces away from the battery string.

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