Battery production method, solar cell, and photovoltaic module

Abstract

This application relates to the field of photovoltaic technology, disclosing a battery fabrication method, a solar cell, and a photovoltaic module. The battery fabrication method of this application includes: providing an initial battery cell; the initial battery cell is a battery cell after laser-enhanced contact optimization; the initial battery cell includes a substrate, a doped layer, and a passivation layer; the initial battery cell is placed in an inert gas environment; preheating the initial battery cell to allow free hydrogen ions in the doped layer and passivation layer to diffuse to the substrate; performing dynamic photothermal treatment on the preheated initial battery cell to break the hydrogen-silicon bonds in the doped layer and passivation layer to form active hydrogen ions, which repair defects in the initial battery cell, resulting in a repaired battery cell; and testing and sorting the repaired battery cell. This application's embodiment performs preheating and dynamic photothermal treatment between laser-enhanced contact optimization and testing and sorting to improve battery performance, thereby increasing battery conversion efficiency and yield.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a battery preparation method, a solar cell, and a photovoltaic module. Background Technology

[0002] Currently, during the production of solar cells (such as topcon cells and back-contact cells), defects can occur on the surface or within the cell due to factors such as materials and manufacturing processes. These defects can form recombination centers, accelerating electron-hole pair recombination and reducing the cell's conversion efficiency. Furthermore, because the defects within crystalline silicon cells vary and the degree of recombination differs, the efficiency of cells of the same grade can differ, leading to a decrease in the yield rate of module manufacturing.

[0003] Therefore, existing solar cell manufacturing processes suffer from technical problems such as low conversion efficiency and low yield. Summary of the Invention

[0004] The purpose of this application is to provide a battery manufacturing method, a solar cell, and a photovoltaic module, thereby improving the battery conversion efficiency and the battery yield.

[0005] To address the aforementioned technical problems, embodiments of this application provide a battery fabrication method, comprising: providing an initial battery cell; the initial battery cell being a battery cell optimized by laser-enhanced contact; the initial battery cell comprising a substrate, a doped layer, and a passivation layer; the initial battery cell being placed in an inert gas environment; preheating the initial battery cell to allow free hydrogen ions in the doped layer and the passivation layer to diffuse to the substrate; performing dynamic photothermal treatment on the preheated initial battery cell to break the hydrogen-silicon bonds in the doped layer and the passivation layer to form active hydrogen ions, the free hydrogen ions and the active hydrogen ions repairing defects in the initial battery cell to obtain a repaired battery cell; and testing and sorting the repaired battery cell.

[0006] An embodiment of this application also provides a solar cell, comprising: the solar cell being prepared by the above-described cell preparation method.

[0007] Embodiments of this application also provide a photovoltaic module, including: a solar cell as described above.

[0008] In some embodiments, the preheating treatment includes a stepped heating treatment and an isothermal diffusion treatment; the preheating treatment of the initial solar cell includes: performing a stepped heating treatment on the initial solar cell to activate the free hydrogen ions in the doped layer and the passivation layer; and performing an isothermal diffusion treatment on the initial solar cell to allow the activated free hydrogen ions to diffuse to the substrate.

[0009] In some embodiments, the stepped heating process includes multiple heating stages, each heating stage having a heating rate of 5°C / s and a duration of 20s; the isothermal diffusion process has a temperature of 250°C to 400°C and a duration of 60s to 360s.

[0010] In some embodiments, the stepped heating process and the isothermal diffusion process are performed in a nitrogen atmosphere; the nitrogen concentration corresponding to the stepped heating process is less than the nitrogen concentration corresponding to the isothermal diffusion process; the nitrogen concentration corresponding to the stepped heating process is 4000 sccm to 6000 sccm; and the nitrogen concentration corresponding to the isothermal diffusion process is 8000 sccm to 10000 sccm.

[0011] In some embodiments, the dynamic photothermal treatment includes a first photothermal treatment and a second photothermal treatment; the dynamic photothermal treatment of the preheated initial solar cell includes: performing a first photothermal treatment on the initial solar cell to cause free hydrogen ions to aggregate to surface defects of the substrate and surface defects of the doped layer, thereby repairing the surface defects of the substrate and the surface defects of the doped layer; performing a second photothermal treatment on the initial solar cell to cause the hydrogen-silicon bonds in the doped layer and the passivation layer to break and form active hydrogen ions, which are used to repair deep defects of the substrate and deep defects of the doped layer; wherein the light intensity of the first photothermal treatment is less than the light intensity of the second photothermal treatment, and the temperature of the first photothermal treatment is less than the temperature of the second photothermal treatment.

[0012] In some embodiments, the initial solar cell further includes electrodes; during the preheating process of the initial solar cell, free hydrogen ions in the doped layer and the passivation layer diffuse to the electrodes; during the first photothermal treatment of the initial solar cell, the free hydrogen ions also aggregate to the surface defects of the electrodes, repairing the surface defects of the electrodes.

[0013] In some embodiments, the light intensity of the first photothermal treatment is 10 to 15 suns, the temperature of the first photothermal treatment is 300°C to 350°C, and the duration of the first photothermal treatment is 10 to 300 s; the light intensity of the second photothermal treatment is 30 to 50 suns, the temperature of the second photothermal treatment is 350°C to 400°C, and the duration of the second photothermal treatment is 10 to 300 s.

[0014] In some embodiments, the first photothermal treatment and the second photothermal treatment are performed in an argon atmosphere; the argon concentration corresponding to the first photothermal treatment is the same as the argon concentration corresponding to the second photothermal treatment; the argon concentration corresponding to the first photothermal treatment and the argon concentration corresponding to the second photothermal treatment are both 8000 sccm to 10000 sccm.

[0015] The technical solution provided in this application has at least the following advantages: In this embodiment, between laser-enhanced contact optimization and testing and sorting, the initial solar cell is preheated in an inert gas environment to diffuse free hydrogen ions to the substrate. The initial solar cell is then subjected to dynamic photothermal treatment in an inert gas environment to break the hydrogen-silicon bonds in the doped layer and passivation layer to form active hydrogen ions. The free hydrogen ions and active hydrogen ions repair the defects of the initial solar cell, improve the performance of the cell, and thus improve the conversion efficiency and yield of the cell. Attached Figure Description

[0016] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0017] Figure 1 This is a schematic diagram of the structure of an initial battery cell according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure of an initial battery cell after preheating treatment according to an embodiment of this application; Figure 3 This is a schematic diagram of temperature changes during a stepped heating process and a constant-temperature diffusion process according to an embodiment of this application. Figure 4 This is a schematic diagram of the structure of an initial battery cell after undergoing a first photothermal treatment according to an embodiment of this application; Figure 5 This is a schematic diagram of the structure of an initial battery cell after undergoing a second photothermal treatment according to an embodiment of this application. Figure 6 This is another structural schematic diagram of an initial battery cell according to an embodiment of this application; Figure 7 This is a schematic diagram of another structure of the initial battery cell after preheating treatment according to an embodiment of this application; Figure 8 This is another structural schematic diagram of an initial battery cell after undergoing a first photothermal treatment according to an embodiment of this application; Figure 9 This is another structural schematic diagram of the initial battery cell after undergoing a second photothermal treatment according to an embodiment of this application; Figure 10 This is another structural schematic diagram of an initial battery cell according to an embodiment of this application; Figure 11 This is a schematic diagram of another structure of the initial battery cell after preheating treatment according to an embodiment of this application; Figure 12 This is a schematic diagram of the structure of an initial battery cell after undergoing a first photothermal treatment according to an embodiment of this application. Figure 13 This is another structural schematic diagram of the initial battery cell after undergoing a second photothermal treatment according to an embodiment of this application.

[0018] Figure Labels Substrate (10), doped layer (20), passivation layer (30), electrode (40), free hydrogen ions (51), hydrogen-silicon bond (52), first doped layer (21), second doped layer (22), first passivation layer (31), second passivation layer (32), first electrode (41), second electrode (42), aluminum oxide layer (60), first aluminum oxide layer (61), second aluminum oxide layer (62), tunneling layer (70), first tunneling layer (71), second tunneling layer (72). Detailed Implementation

[0019] As can be seen from the background technology, existing solar cell manufacturing processes suffer from technical problems such as low cell conversion efficiency and low yield.

[0020] In current solar cell manufacturing processes, in order to reduce costs, a process called "UV lamp irradiation" is usually used after sintering, light injection, and LECO (Laser Enhanced Contact Optimization) to improve efficiency.

[0021] Analysis revealed that the UV lamp irradiation process lacks dynamic control capabilities. Current UV lamp irradiation uses fixed light intensity parameters, which cannot match the energy requirements of hydrogen atoms at different stages of activation, migration, and defect binding. If the light intensity is too low, hydrogen atom activation is insufficient (especially in polycrystalline silicon layers where the hydrogen migration barrier cannot be overcome); if the light intensity is too high, excessive carrier recombination can easily occur, generating new interface defects and directly causing efficiency fluctuations. The UV lamp irradiation process also fails to consider the synergistic effect of temperature on hydrogen atom behavior. Current processes rely solely on residual temperature after sintering or room temperature, without establishing a targeted temperature gradient control mechanism. The migration rate and defect binding energy of hydrogen atoms in the TOPCon structure are strongly correlated with temperature. At constant temperatures, "activated hydrogen atoms cannot effectively migrate to defect sites" (at low temperatures) or "hydrogen atoms detach from the defect binding state due to disordered thermal motion" (at high temperatures), leading to uneven efficiency improvements. Furthermore, the UV lamp irradiation process lacks a protective atmosphere, resulting in hydrogen atom loss. The UV lamp irradiation process is conducted in an open or ordinary air environment, where oxygen and water vapor react with active hydrogen atoms to generate OH-. - Or H2O, which consumes the hydrogen source that can participate in defect repair; at the same time, oxygen can easily penetrate the tunnel oxide layer to form oxygen vacancy defects, further offsetting the efficiency improvement effect.

[0022] The aforementioned issues can lead to the easy loss or loss of hydrogen atoms at any stage, ultimately resulting in significant differences in efficiency within / between batches of solar cells (fluctuations often exceeding 0.3%), and some solar cells experiencing a decline in efficiency due to incomplete defect repair.

[0023] To address the aforementioned technical problems, this application provides a battery fabrication method, comprising: providing an initial battery cell; the initial battery cell being a battery cell optimized by laser-enhanced contact; the initial battery cell comprising a substrate, a doped layer, and a passivation layer; the initial battery cell being placed in an inert gas environment; preheating the initial battery cell to allow free hydrogen ions in the doped layer and passivation layer to diffuse to the substrate; performing dynamic photothermal treatment on the preheated initial battery cell to break hydrogen-silicon bonds in the doped layer and passivation layer to form active hydrogen ions, the free hydrogen ions and active hydrogen ions repairing defects in the initial battery cell to obtain a repaired battery cell; and testing and sorting the repaired battery cell.

[0024] In the battery fabrication process of this application embodiment, between laser-enhanced contact optimization and testing and sorting, the initial battery cell is preheated in an inert gas environment to diffuse free hydrogen ions to the substrate. The initial battery cell is then photothermally treated in an inert gas environment to allow free hydrogen ions to repair defects in the initial battery cell. This replaces the UV lamp irradiation process in existing battery fabrication processes, improves battery performance, and thus increases battery conversion efficiency and yield.

[0025] 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. Similarly, "multiple sets" refers to two or more sets (including two sets), and "multiple pieces" refers to two or more pieces (including two pieces).

[0026] 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.

[0027] 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 are in an "or" relationship.

[0028] 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," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not 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. For example, if the device or element in the illustration is inverted, then the element described as "below," "under," "below," or "bottom" of other elements or features will be oriented "above" or "top" of said other elements or features. Therefore, the term "below" may cover both above and below orientation depending on the context in which the term is used, which will be obvious to those skilled in the art. Materials may be oriented in other ways (e.g., rotated 90 degrees, inverted, flipped), and the spatial relative descriptive terms used herein may be interpreted accordingly.

[0029] In the description of the embodiments of this application, unless otherwise expressly specified and limited, 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.

[0030] 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. Furthermore, when describing a component as "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.

[0031] In the description of the embodiments of this application, when a component "includes" another component, it does not exclude other components unless otherwise stated, and other components may be further included. The formation or provision of a second component above or on a first component, or on the surface of a first component, or on one side of a first component, may include embodiments where the first and second components are in direct contact, and may also include embodiments where an additional component may be present between the first and second components, thereby preventing direct contact between the first and second components. For simplicity and clarity, various components may be drawn at different scales. In the drawings, some layers / components may be omitted for simplicity. Unless otherwise specified, the formation or provision of a second component on the surface of a first component refers to direct contact between the first and second components. The term "component" can refer to a layer, film, region, portion, structure, etc.

[0032] 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 "component" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0033] The embodiments of this disclosure 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 disclosure to facilitate a better understanding of the disclosure. However, the technical solutions claimed in this disclosure can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0034] One embodiment of this application relates to a battery fabrication method, the specific fabrication process of which is described in [reference]. Figures 1 to 5 .

[0035] refer to Figure 1 This is a schematic diagram of the initial battery cell structure.

[0036] This embodiment first provides an initial solar cell; the initial solar cell is a solar cell after laser-enhanced contact optimization, and the initial solar cell is in an inert gas environment; the initial solar cell includes a substrate 10, a doped layer 20, and a passivation layer 30; wherein, the doped layer 20 covers the surface of the substrate 10, and the passivation layer 30 covers the surface of the doped layer 20 away from the substrate 10.

[0037] Existing battery fabrication processes include the following steps: texturing, boron diffusion, alkaline polishing, polypolymerization, phosphorus diffusion, alkaline polishing, ALD, positive film, back film, screen printing, light injection, LECO, UV lamp irradiation, and testing and sorting. However, the current "UV lamp irradiation" process suffers from technical problems such as a lack of dynamic control capabilities, failure to consider the synergistic effect of temperature on hydrogen atom behavior, and hydrogen atom loss due to the lack of a protective atmosphere. Therefore, the battery fabrication method in this embodiment is performed between the LECO and testing / sorting steps. The initial battery cell in this embodiment is a cell optimized by laser-enhanced contact, thereby replacing the "UV lamp irradiation" process in the original battery fabrication method to improve battery performance, thereby increasing battery conversion efficiency and yield.

[0038] In this embodiment, the doped layer 20 can be an N-type doped layer or a P-type doped layer, and the passivation layer 30 is a passivation layer 30 covering the N-type doped layer or the P-type doped layer.

[0039] During the fabrication of doped layers 20, such as N-type or P-type doped layers, hydrogen-containing byproducts are generated, which may leave residual free hydrogen ions 51 and form hydrogen-silicon bonds 52 in the doped layer 20. Therefore, the doped layer 20 will contain free hydrogen ions 51 and hydrogen-silicon bonds 52. The passivation layer 30 is fabricated using ALD (Atomic Layer Deposition) or PECVD (Plasma Enhanced Chemical Vapor Deposition). During the fabrication process, -OH groups are introduced, which may form hydrogen-silicon bonds 52 and free hydrogen ions 51. Therefore, the passivation layer 30 contains free hydrogen ions 51 and hydrogen-silicon bonds 52. The presence of these free hydrogen ions 51 and the formation of hydrogen-silicon bonds 52 will affect the performance of the doped layer 20 and the passivation layer 30. Therefore, the free hydrogen ions 51 and the formation of hydrogen-silicon bonds 52 will be used to repair the defects of the initial solar cell in subsequent processing. On the one hand, it can reduce the free hydrogen ions 51 and the formation of hydrogen-silicon bonds 52 in the doped layer 20 and the passivation layer 30, thereby improving the performance of the doped layer 20 and the passivation layer 30. On the other hand, it can serve as a source of hydrogen ions to repair the defects of the initial solar cell, thereby improving the performance of the initial solar cell.

[0040] refer to Figure 1 The initial solar cell in this embodiment also includes an electrode 40; the electrode 40 penetrates the passivation layer 30 and connects to the doped layer 20. By contacting the doped layer 20, the electrode 40 collects photogenerated carriers and transmits them to an external circuit, thereby forming a current. If the doped layer 20 is a P-type doped layer, located on the front side of the solar cell, the electrode 40 can exist as a fine grid line, mainly used to collect holes; if the doped layer 20 is an N-type doped layer, located on the back side of the solar cell, the electrode 40 can be a large-area back electrode, mainly used to collect photogenerated electrons.

[0041] refer to Figure 2 This is a schematic diagram of the structure of the initial battery cell after preheating treatment.

[0042] In this embodiment, after providing the initial battery cell, the initial battery cell is preheated to allow free hydrogen ions 51 in the doped layer 20 and passivation layer 30 to diffuse into the substrate 10.

[0043] Because bulk defects may exist in the substrate 10 during its fabrication process, there may be some oxygen vacancies within the substrate 10, which may affect the performance of the fabricated solar cell. In this embodiment, it is necessary to repair both the surface and internal defects of the substrate 10. Therefore, this embodiment first uses a preheating treatment to allow free hydrogen ions 51 in the doped layer 20 and passivation layer 30 to diffuse to the substrate 10, providing a hydrogen ion basis for subsequent modification of the surface and internal defects of the substrate 10. At the same time, the free hydrogen ions 51 in the doped layer 20 and passivation layer 30 can reach the substrate 10 first, improving the efficiency of subsequent repair of the surface and internal defects of the substrate 10.

[0044] The preheating treatment in this embodiment includes a stepped heating treatment and a constant temperature diffusion treatment; wherein, the preheating treatment of the initial solar cell includes: performing a stepped heating treatment on the initial solar cell to activate the free hydrogen ions 51 in the doped layer 20 and the passivation layer 30; and performing a constant temperature diffusion treatment on the initial solar cell to allow the activated free hydrogen ions 51 to diffuse to the substrate 10.

[0045] This embodiment divides the preheating process into a stepped heating process and an isothermal diffusion process, allowing the initial solar cell to gradually heat up according to the stepped heating process, thereby improving the stability of the initial solar cell. Because the temperature rise in the stepped heating process is relatively stable, the temperature of the initial solar cell is more uniform, which can effectively activate the free hydrogen ions 51 in the doped layer 20 and passivation layer 30, providing a hydrogen ion source for subsequent repair of defects in the substrate 10 and improving the repair effect of the substrate 10. Simultaneously, this embodiment uses an isothermal diffusion process to ensure a uniform temperature of the initial solar cell, which allows the activated free hydrogen ions 51 to diffuse effectively into the substrate 10, improving the subsequent repair effect of defects in the substrate 10.

[0046] refer to Figure 3 The diagram illustrates the temperature changes during stepped heating and isothermal diffusion processes. The stepped heating process includes multiple heating stages, each consisting of a uniform heating stage L1 and a temperature maintenance stage L2. The isothermal diffusion process is represented by L3 in the diagram. Specifically, in some embodiments, the heating rate of the uniform heating stage L1 is 5°C / s, and the total time for each heating stage is 20s. For example, if the temperature increases by 50°C in each heating stage, the duration of the uniform heating stage L1 is 10s due to the heating rate of 5°C / s, and the duration of the temperature maintenance stage L2 is also 10s.

[0047] The stepped heating process in this embodiment uses gradual thermal excitation to gradually transform the free hydrogen ions 51 from the bound state of the doped layer 20 and the passivation layer 30 into a free state, avoiding the aggregation and dissipation of hydrogen atoms caused by sudden heating, and improving the effect of subsequent repair of defects in the substrate 10.

[0048] In some embodiments, the temperature of the isothermal diffusion treatment L3 is 250°C to 400°C, for example, 250°C, 280°C, 300°C, 330°C, 350°C, 380°C, or 400°C; and the duration of the isothermal diffusion treatment is 60s to 360s, for example, 60s, 100s, 120s, 150s, 200s, 250s, 300s, 350s, or 400s.

[0049] Since each heating stage in this embodiment includes a uniform heating stage L1 and a temperature maintenance stage L2, after each heating stage is heated uniformly and then maintained for a period of time before proceeding to the next heating stage, the multiple heating stages present a gradient heating, which further improves the uniformity of the initial cell temperature, enhances the effect of activating free hydrogen ions 51 in the doped layer 20 and passivation layer 30, and improves the subsequent repair effect of the substrate 10.

[0050] In this embodiment, the isothermal diffusion process utilizes thermal drive to cause free hydrogen atoms 51 to break through the interface barrier between the doped layer 20 and the substrate 10 and diffuse into the bulk region of the substrate 10. The orderly activation of the stepped heating and the deep migration of the isothermal diffusion create a hydrogen concentration gradient reserve from the surface layer to the bulk region of the substrate 10, providing a continuous hydrogen source for defect repair in the subsequent photothermal stage.

[0051] refer to Figure 1 The initial battery cell in this embodiment also includes an electrode 40. Since some surface defects may exist on the surface of the electrode 40 during its fabrication process, this embodiment can also repair these surface defects. During the preheating process of the initial battery cell, free hydrogen ions 51 in the doped layer 20 and passivation layer 30 diffuse to the electrode 40, providing a hydrogen ion source for subsequent repair of electrode 40 defects. In the stepped heating process, the free hydrogen ions 51 in the doped layer 20 and passivation layer 30 are activated. In the isothermal diffusion process, the activated free hydrogen ions 51 diffuse to the electrode 40, improving the effectiveness of subsequent repair of electrode 40 defects.

[0052] Since each heating stage in this embodiment includes a uniform heating stage and a temperature maintenance stage, after each heating stage, the temperature is maintained for a period of time before proceeding to the next heating stage. This results in a gradient heating effect across multiple heating stages, further improving the uniformity of the initial cell temperature and enhancing the effect of activating free hydrogen ions 51 in the doped layer 20 and passivation layer 30. This not only improves the repair effect of the substrate 10 but also the repair effect of the electrode 40, thereby improving the conversion efficiency and yield of the cell.

[0053] In this embodiment, the stepped heating process and the isothermal diffusion process are performed in a nitrogen atmosphere. The nitrogen concentration for the stepped heating process is lower than that for the isothermal diffusion process. Since the stepped heating process operates at a lower temperature than the isothermal diffusion process, the nitrogen requirement is lower. Therefore, this embodiment uses a lower nitrogen concentration for the stepped heating process compared to the isothermal diffusion process. This approach reduces the cost of the nitrogen environment for the stepped heating process while still meeting the nitrogen requirements of both processes. Furthermore, it ensures that the initial solar cells are not oxidized during both processes, improving their stability, conversion efficiency, and yield.

[0054] Specifically, the nitrogen concentration corresponding to the stepped heating treatment is 4000 sccm to 6000 sccm, such as 4000 sccm, 4500 sccm, 5000 sccm, 5500 sccm, and 6000 sccm; the nitrogen concentration corresponding to the isothermal diffusion treatment is 8000 sccm to 10000 sccm, such as 8000 sccm, 8500 sccm, 9000 sccm, 9500 sccm, and 10000 sccm.

[0055] In this embodiment, after preheating the initial solar cell, dynamic photothermal treatment is performed on the preheated initial solar cell to break the hydrogen-silicon bonds 52 in the doped layer 20 and the passivation layer 30 to form active hydrogen ions. The free hydrogen ions 51 and the active hydrogen ions repair the defects of the initial solar cell, resulting in a repaired solar cell.

[0056] Because of the preheating treatment, the free hydrogen ions 51 in the doped layer 20 and passivation layer 30 have diffused to the substrate 10 and the electrode 40. During the photothermal treatment, the free hydrogen ions 51 that have diffused to the substrate 10 and the electrode 40 can directly repair the defects of the substrate 10 and the electrode 40, thereby improving the conversion efficiency and yield of the solar cell.

[0057] Since the doped layer 20 may be introduced into the process of preparation, including inactive states and metal impurities, it may also have surface and metal defects. Therefore, in this embodiment, the surface and metal defects of the doped layer 20 are repaired during the photothermal treatment process, thereby improving the repair effect of the doped layer 20, improving the conversion efficiency of the solar cell and the yield of the solar cell.

[0058] The dynamic photothermal processing in this embodiment includes a first photothermal processing and a second photothermal processing. (See reference...) Figure 4 This is a schematic diagram of the structure of the initial solar cell after the first photothermal treatment. (Reference) Figure 5This is a schematic diagram of the structure of the initial solar cell after undergoing the second photothermal treatment.

[0059] This embodiment establishes a two-stage collaborative mode of low photothermal pre-aggregation (first photothermal treatment) + high photothermal deep repair (second photothermal treatment) to achieve layered treatment of surface and deep defects.

[0060] This embodiment performs dynamic photothermal treatment on the preheated initial solar cell, including: performing a first photothermal treatment on the initial solar cell to cause free hydrogen ions 51 to accumulate on the surface defects of the substrate 10 and the doped layer 20, thereby repairing the surface defects of the substrate 10 and the doped layer 20; and performing a second photothermal treatment on the initial solar cell to cause the hydrogen-silicon bonds 52 in the doped layer 20 and the passivation layer 30 to break and form active hydrogen ions, which are used to repair deep defects in the substrate 10 and the doped layer 20. During the first photothermal treatment of the initial solar cell in this embodiment, free hydrogen ions 51 also accumulate on the surface defects of the electrode 40, repairing the surface defects of the electrode 40. The surface defects of the electrode 40 are the contact areas between the metal electrode and the substrate 10, which are electronic state defects of the silicon material in the substrate 10.

[0061] Specifically, during the diffusion of free hydrogen ions 51 from the doped layer 20 and passivation layer 30 to the substrate 10 and electrode 40, some of the free hydrogen ions 51 from the passivation layer 30 diffuse to the doped layer 20, and some of the free hydrogen ions 51 from the doped layer 20 remain. Therefore, during the first photothermal treatment, the free hydrogen ions 51 gathered on the substrate 10 repair the surface defects of the substrate 10, the free hydrogen ions 51 gathered on the electrode 40 repair the surface defects of the electrode 40, and the free hydrogen ions 51 inside the doped layer 20 also repair the surface defects of the doped layer 20. This allows the surface defects of the substrate 10, electrode 40, and doped layer 20 to be repaired, thereby improving the conversion efficiency and yield of the solar cell.

[0062] Specifically, in this embodiment, after the first photothermal treatment is performed and the surface defects of the substrate 10, electrode 40, and doped layer 20 are repaired, a second photothermal treatment is performed. During the second photothermal treatment, the hydrogen-silicon bonds 52 in the doped layer 20 and passivation layer 30 will break to form active hydrogen ions. The active hydrogen ions will further repair the deep defects of the substrate 10 and the deep defects of the doped layer 20 under the action of the second photothermal treatment, thereby improving the conversion efficiency of the solar cell and the yield of the solar cell.

[0063] The low-intensity photogenerated carriers (electron-hole pairs) generated by the first photothermal treatment form an electric field on the surface, guiding free hydrogen ions 51 to aggregate towards surface defects (such as dangling bonds and oxide layer defects) to repair these defects. The high-intensity photothermal treatment enhances the breaking of hydrogen-silicon bonds 52 (selectively breaking only weak bonds with low binding energy to defects, i.e., hydrogen-silicon bonds 52), and the high temperature promotes the chemical bonding of hydrogen atoms with deep defects (such as dislocations and metallic impurities). This embodiment avoids local overheating caused by traditional constant parameters (temperature fluctuations are controlled within ±3℃) by gradually increasing the light intensity and temperature, significantly reducing the new defect generation rate.

[0064] In this process, the light intensity of the first photothermal treatment is lower than that of the second photothermal treatment, and the temperature of the first photothermal treatment is lower than that of the second photothermal treatment. Under higher light intensity, the hydrogen-silicon bonds 52 in the doped layer 20 and passivation layer 30 will break, forming active hydrogen ions. If both free hydrogen ions 51 and active hydrogen ions are present simultaneously, a large number of hydrogen ions will be activated, resulting in uneven repair effects on the substrate 10, electrode 40, and doped layer 20, leading to poor repair results. Therefore, in this embodiment, a first photothermal treatment with lower light intensity is first performed to prevent the hydrogen-silicon bonds 52 in the doped layer 20 and passivation layer 30 from breaking and forming active hydrogen ions. Only free hydrogen ions 51 are used to repair the surface defects of the substrate 10, electrode 40, and doped layer 20, ensuring the effectiveness of surface defect repair. Then, a second photothermal treatment with higher light intensity is performed, which causes the hydrogen-silicon bonds 52 in the doped layer 20 and passivation layer 30 to break and form active hydrogen ions to repair the deep defects of the substrate 10 and doped layer 20, ensuring the repair effect of deep defects of the substrate 10 and doped layer 20, improving the conversion efficiency and yield of the solar cell.

[0065] Specifically, the light intensity of the first photothermal treatment is 10 to 15 suns, for example, 10 suns, 11 suns, 12 suns, 13 suns, 14 suns, or 15 suns; the temperature of the first photothermal treatment is 300°C to 350°C, for example, 300°C, 310°C, 320°C, 330°C, 340°C, or 350°C; and the duration of the first photothermal treatment is 10 to 300 seconds, for example, 10 seconds, 50 seconds, 100 seconds, 150 seconds, 200 seconds, or 250 seconds. The light intensity of the second photothermal treatment is 30s to 50s, for example, 30s, 35s, 40s, 45s, 50s; the temperature of the second photothermal treatment is 350℃ to 400℃, for example, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃; the duration of the second photothermal treatment is 10s to 300s, for example, 10s, 50s, 100s, 150s, 200s, 250s, 300s.

[0066] In some embodiments, the inert gas is argon, and the first and second photothermal treatments are performed in an argon atmosphere. This embodiment avoids the problem of cell oxidation during photothermal treatment by performing the first and second photothermal treatments in an argon atmosphere, thereby improving the repair efficiency of initial cell defects, and ultimately increasing the cell conversion efficiency and yield.

[0067] Specifically, the argon concentration corresponding to the first photothermal treatment is the same as the argon concentration corresponding to the second photothermal treatment; the argon concentration corresponding to the first photothermal treatment and the argon concentration corresponding to the second photothermal treatment are both between 8000 sccm and 10000 sccm, for example, 8000 sccm, 9000 sccm, and 10000 sccm.

[0068] Based on the differences in physical properties between nitrogen and argon, this embodiment designs a segmented atmosphere protection strategy: A nitrogen environment with a purity ≥99.999% is used in the preheating stage. Nitrogen's low thermal conductivity reduces heat loss, and a dynamic flow rate (e.g., 5000 sccm for the heating stage → 10000 sccm for the isothermal stage) forms an "air curtain barrier" to isolate oxygen and reduce hydrogen atom oxidation. An argon environment with a purity ≥99.999% is used in the photothermal treatment stage. Argon's large atomic mass and low diffusion coefficient suppress thermal convection disturbances (e.g., a flow rate of 10000 sccm), while its high inertness protects the active hydrogen generated by the breaking of hydrogen-silicon bonds from contamination.

[0069] In current passivation processes for crystalline silicon solar cells, the synergy between low-temperature thermal treatment and photothermal excitation is insufficient, resulting in limited passivation effects. Specifically, this manifests as: low hydrogen atom migration efficiency: In traditional isothermal thermal treatment (150-400℃), hydrogen atoms are only enriched on the surface, resulting in low passivation rates for bulk defects (such as oxygen vacancies and metal impurities in the substrate) and poor passivation effects; imbalance between photothermal and photothermal matching: The combination of constant light intensity (20-40 sun) and high temperature (300-600℃) easily triggers an "overactivation" phenomenon, where the hydrogen-silicon bond 52 breaking rate exceeds the rate at which hydrogen atoms combine with defects, leading to the generation of new defects; lack of atmosphere control: Without inert gas protection, hydrogen atoms combine with oxygen in the air to generate H2O at high temperatures, resulting in a high hydrogen loss rate and causing the passivation effect to decay over time.

[0070] This invention achieves precise control of the entire process of hydrogen atoms from activation and migration to defect bonding through an integrated process combining thermal treatment temperature gradient, photoexcitation dynamic light intensity, and inert gas field. The initial solar cell is preheated to diffuse free hydrogen ions to the substrate, and then subjected to dynamic photothermal treatment to allow free hydrogen ions to repair defects in the initial solar cell, thereby improving the battery's performance, conversion efficiency, and yield.

[0071] Another embodiment of this application relates to a battery fabrication method, the specific fabrication process of which is described in [reference]. Figures 6 to 9 .

[0072] refer to Figure 6 This is another structural schematic diagram of the initial battery cell.

[0073] This embodiment first provides an initial solar cell; the initial solar cell is a solar cell after laser-enhanced contact optimization, and the initial solar cell is in an inert gas environment; the initial solar cell in this embodiment can be a Topcon solar cell, which has a first doped layer 21 and a second doped layer 22 on the front and back sides, respectively. Correspondingly, the passivation layer includes a first passivation layer 31 and a second passivation layer 32; wherein, the first doped layer 21 covers the front side of the substrate 10, the first passivation layer 31 covers the surface of the first doped layer 21 away from the substrate 10, the second doped layer 22 covers the back side of the substrate 10, and the second passivation layer 32 covers the surface of the second doped layer 22 away from the substrate 10. The first doped layer 21 is a P-type doped layer, and the second doped layer 22 is an N-type doped layer.

[0074] refer to Figure 6The initial solar cell in this embodiment also includes a first electrode 41 and a second electrode 42. The first electrode 41 penetrates the first passivation layer 31 and is connected to the first doped layer 21. The second electrode 42 penetrates the second passivation layer 32 and is connected to the second doped layer 22. The first doped layer 21 is a P-type doped layer, which is located on the front side of the solar cell. The first electrode 41 exists in the form of fine grid lines and is mainly used to collect holes. The second doped layer 22 is an N-type doped layer, which is located on the back side of the solar cell. The second electrode 42 is mainly used to collect photogenerated electrons.

[0075] refer to Figure 6 An aluminum oxide layer 60 is disposed between the first passivation layer 31 and the first doped layer 21. The aluminum oxide layer 60 can effectively passivate the dangling bonds and defect states (surface traps) of the first passivation layer 31 and the first doped layer 21, significantly reducing the surface recombination rate, thereby improving minority carrier lifetime and cell efficiency. A tunneling layer 70, such as the ultrathin silicon oxide layer in TOPCon cells, is also disposed between the substrate 10 and the second doped layer 22. The tunneling layer 70 can selectively tunnel through, allowing majority carriers to tunnel through, but blocking minority carriers, thereby reducing recombination and lowering the recombination current. The ultrathin silicon oxide layer can saturate the dangling bonds on the silicon surface, reduce the interface defect state density, and improve minority carrier lifetime. The tunneling layer 70 can saturate the dangling bonds on the silicon surface, reduce the interface defect state density, improve minority carrier lifetime, and improve open-circuit voltage and cell efficiency.

[0076] refer to Figure 7 This is a schematic diagram of another structure after the initial solar cell has undergone preheating treatment.

[0077] In this embodiment, after providing the initial battery cell, the initial battery cell is preheated to allow free hydrogen ions 51 in the first doped layer 21, the second doped layer 22, the first passivation layer 31, and the second passivation layer 32 to diffuse into the substrate 10.

[0078] Specifically, in addition to the substrate 10, the first doped layer 21 and the second doped layer 22 also have defects. Therefore, after preheating the initial cell, the free hydrogen ions 51 in the first passivation layer 31 and the second passivation layer 32 diffuse to the first passivation layer 31 and the second passivation layer 32. Some free hydrogen ions 51 will also remain inside the first passivation layer 31 and the second passivation layer 32, providing a hydrogen ion basis for subsequent repair of the defects in the substrate 10, the first doped layer 21 and the second doped layer 22, thereby improving the conversion efficiency and yield of the cell.

[0079] The preheating treatment in this embodiment includes a stepped heating treatment and a constant-temperature diffusion treatment. The preheating treatment of the initial solar cell includes a stepped heating treatment to activate free hydrogen ions 51 in the first doped layer 21, the second doped layer 22, the first passivation layer 31, and the second passivation layer 32. If the first doped layer 21 is boron doped, there are no hydrogen ions in the first doped layer 21; only the second doped layer 22 will produce hydrogen ions as a byproduct during phosphorus doping. This embodiment also performs a constant-temperature diffusion treatment on the initial solar cell to allow the activated free hydrogen ions 51 to diffuse to the substrate 10. The activated free hydrogen ions 51 also diffuse to the interface defects between the first electrode 41, the second electrode 42, and the substrate 10.

[0080] This embodiment divides the preheating process into a stepped heating process and an isothermal diffusion process, allowing the initial solar cell to gradually heat up according to the stepped heating process, thereby improving the stability of the initial solar cell. Because the temperature rise in the stepped heating process is relatively stable, the temperature of the initial solar cell is more uniform, which can effectively activate the free hydrogen ions 51 in the first doped layer 21, the second doped layer 22, the first passivation layer 31, and the second passivation layer 32. This provides a source of hydrogen ions for subsequent repair of defects in the substrate 10, the first doped layer 21, and the second doped layer 22, improving the repair effect of the initial solar cell. Simultaneously, this embodiment uses an isothermal diffusion process to ensure a uniform temperature of the initial solar cell, allowing the activated free hydrogen ions 51 to diffuse effectively into the substrate 10, the first doped layer 21, and the second doped layer 22, further improving the effectiveness of subsequent repair of defects in the initial solar cell.

[0081] In this embodiment, after preheating the initial battery cell, dynamic photothermal treatment is performed on the preheated initial battery cell to break the hydrogen-silicon bonds 52 in the first doped layer 21, the second doped layer 22, the first passivation layer 31, and the second passivation layer 32 to form active hydrogen ions. The free hydrogen ions 51 and the active hydrogen ions repair the defects of the initial battery cell, resulting in a repaired battery cell.

[0082] Because of the preheating treatment, the substrate 10, the first electrode 41, the second electrode 42, the first doped layer 21, and the second doped layer 22 all contain free hydrogen ions 51. During the dynamic photothermal treatment process, the free hydrogen ions 51 in the substrate 10, the first electrode 41, the second electrode 42, the first doped layer 21, and the second doped layer 22 can directly repair the surface defects of the first electrode 41 and the second electrode 42, that is, the interface defects between the first electrode 41 and the substrate 10 and the interface defects between the second electrode 42 and the substrate 10. They can also repair the surface defects of the first doped layer 21 and the second doped layer 22, thereby improving the conversion efficiency and yield of the solar cell.

[0083] The dynamic photothermal treatment in this embodiment includes a first photothermal treatment and a second photothermal treatment; Reference Figure 8 This is another structural diagram of the initial solar cell after undergoing the first photothermal treatment. (Refer to...) Figure 9 This is another structural diagram of the initial solar cell after undergoing a second photothermal treatment.

[0084] This embodiment performs dynamic photothermal treatment on the preheated initial solar cell, including: performing a first photothermal treatment on the initial solar cell to cause free hydrogen ions 51 to accumulate on the surface defects of the substrate 10, the first doped layer 21, the second doped layer 22, the first electrode 41, and the second electrode 42, thereby repairing the surface defects of the substrate 10, the first doped layer 21, and the second doped layer 22; and performing a second photothermal treatment on the initial solar cell to cause the hydrogen-silicon bonds 52 in the first doped layer 21, the second doped layer 22, the first passivation layer 31, and the second passivation layer 32 to break and form active hydrogen ions, which are used to repair deep defects in the substrate 10, the first doped layer 21, and the second doped layer 22. During the first photothermal treatment of the initial solar cell in this embodiment, free hydrogen ions 51 also accumulate on the surface defects of the first electrode 41 and the second electrode 42, repairing the surface defects of the first electrode 41 and the second electrode 42.

[0085] Compared with TOPCon batteries prepared by existing processes, the TOPCon batteries prepared by the process in this embodiment have improved conversion efficiency, UOC (open circuit voltage), ISC (short circuit current), and FF (fill factor). As shown in Table 1, this table compares the parameters of the TOPCon batteries prepared by the process in this embodiment with those prepared by existing processes.

[0086] Table 1

[0087] Another embodiment of this application relates to a battery fabrication method, the specific fabrication process of which is described in [reference]. Figures 10 to 13 .

[0088] refer to Figure 10 This is another structural schematic diagram of the initial battery cell.

[0089] This embodiment first provides an initial solar cell, which is a solar cell optimized by laser-enhanced contact, and the initial solar cell is placed in an inert gas environment. The initial solar cell in this embodiment can be a back-contact solar cell, having a first doped layer 21 and a second doped layer 22 on the back side. Correspondingly, the passivation layer 30 includes a first passivation layer 31 and a second passivation layer 32. The first doped layer 21 covers the back side of the substrate 10, the first passivation layer 31 covers the surface of the first doped layer 21 away from the substrate 10, the second doped layer 22 covers the back side of the substrate 10, and the second passivation layer 32 covers the surface of the second doped layer 22 away from the substrate 10. The first doped layer 21 is a P-type doped layer, and the second doped layer 22 is an N-type doped layer.

[0090] refer to Figure 10 The initial solar cell in this embodiment also includes a first electrode 41 and a second electrode 42. The first electrode 41 penetrates the first passivation layer 31 and is connected to the first doped layer 21. The second electrode 42 penetrates the second passivation layer 32 and is connected to the second doped layer 22. The first doped layer 21 is a P-type doped layer, which is located on the front side of the solar cell. The first electrode 41 exists in the form of fine grid lines and is mainly used to collect holes. The second doped layer 22 is an N-type doped layer, which is located on the back side of the solar cell. The second electrode 42 is mainly used to collect photogenerated electrons.

[0091] refer to Figure 10 A first aluminum oxide layer 61 is disposed between the first passivation layer 31 and the first doped layer 21, and a second aluminum oxide layer 62 is disposed between the second passivation layer 32 and the second doped layer 22. The first aluminum oxide layer 61 can effectively passivate the dangling bonds and defect states (surface traps) of the first passivation layer 31 and the first doped layer 21, and the second aluminum oxide layer 62 can effectively passivate the dangling bonds and defect states (surface traps) of the second passivation layer 32 and the second doped layer 22, significantly reducing the surface recombination rate, thereby improving minority carrier lifetime and battery efficiency.

[0092] In this embodiment, a first tunneling layer 71 is further disposed between the substrate 10 and the first doped layer 21, and a second tunneling layer 72 is further disposed between the substrate 10 and the second doped layer 22. The first tunneling layer 71 and the second tunneling layer 72 are ultrathin silicon oxide layers. The first tunneling layer 71 and the second tunneling layer 72 can selectively tunnel through, allowing majority carriers to tunnel through, but blocking minority carriers, thereby reducing recombination and lowering the recombination current. The ultrathin silicon oxide layer can saturate the dangling bonds on the silicon surface, reduce the interface defect state density, and improve the minority carrier lifetime. The first tunneling layer 71 and the second tunneling layer 72 can saturate the dangling bonds on the silicon surface, reduce the interface defect state density, improve the minority carrier lifetime, and improve the open-circuit voltage and cell efficiency.

[0093] refer to Figure 10The back side of the substrate 10 has a spacer region separating the first doped layer 21 and the second doped layer 22, and an aluminum oxide layer 60 and a passivation layer 30 are sequentially disposed in the spacer region.

[0094] refer to Figure 11 This is a schematic diagram of another structure after the initial solar cell has undergone preheating treatment.

[0095] In this embodiment, after providing the initial battery cell, the initial battery cell is preheated to allow free hydrogen ions 51 in the first doped layer 21, the second doped layer 22, the first passivation layer 31, and the second passivation layer 32 to diffuse into the substrate 10.

[0096] Specifically, in addition to the substrate 10, the first doped layer 21 and the second doped layer 22 also have defects. Therefore, after preheating the initial cell, the free hydrogen ions 51 in the first passivation layer 31 and the second passivation layer 32 diffuse to the first passivation layer 31 and the second passivation layer 32. Some free hydrogen ions 51 will also remain inside the first passivation layer 31 and the second passivation layer 32, providing a hydrogen ion basis for subsequent repair of the defects in the substrate 10, the first doped layer 21 and the second doped layer 22, thereby improving the conversion efficiency and yield of the cell.

[0097] The preheating treatment in this embodiment includes a stepped heating treatment and a constant-temperature diffusion treatment; wherein, the preheating treatment of the initial battery cell includes: performing a stepped heating treatment on the initial battery cell to activate the free hydrogen ions 51 in the first doped layer 21, the second doped layer 22, the first passivation layer 31, and the second passivation layer 32; and performing a constant-temperature diffusion treatment on the initial battery cell to allow the activated free hydrogen ions 51 to diffuse to the substrate 10, and the activated free hydrogen ions 51 will also diffuse to the interface between the first electrode 41, the second electrode 42 and the substrate 10.

[0098] This embodiment divides the preheating process into a stepped heating process and an isothermal diffusion process, allowing the initial solar cell to gradually heat up according to the stepped heating process, thereby improving the stability of the initial solar cell. Because the temperature rise in the stepped heating process is relatively stable, the temperature of the initial solar cell is more uniform, which can effectively activate the free hydrogen ions 51 in the first doped layer 21, the second doped layer 22, the first passivation layer 31, and the second passivation layer 32. This provides a source of hydrogen ions for subsequent repair of defects in the substrate 10, the first doped layer 21, and the second doped layer 22, improving the repair effect of the initial solar cell. Simultaneously, this embodiment uses an isothermal diffusion process to ensure a uniform temperature of the initial solar cell, allowing the activated free hydrogen ions 51 to diffuse effectively into the substrate 10, the first doped layer 21, and the second doped layer 22, further improving the effectiveness of subsequent repair of defects in the initial solar cell.

[0099] In this embodiment, after preheating the initial battery cell, dynamic photothermal treatment is performed on the preheated initial battery cell to break the hydrogen-silicon bonds 52 in the first doped layer 21, the second doped layer 22, the first passivation layer 31, and the second passivation layer 32 to form active hydrogen ions. The free hydrogen ions 51 and the active hydrogen ions repair the defects of the initial battery cell, resulting in a repaired battery cell.

[0100] Because of the preheating treatment, the substrate 10, the first doped layer 21, and the second doped layer 22 all contain free hydrogen ions 51. During the dynamic photothermal treatment process, the free hydrogen ions 51 of the substrate 10, the first doped layer 21, and the second doped layer 22 can directly repair the surface defects of the first doped layer 21 and the second doped layer 22, thereby improving the conversion efficiency and yield of the solar cell.

[0101] The dynamic photothermal treatment in this embodiment includes a first photothermal treatment and a second photothermal treatment; Reference Figure 12 This is a schematic diagram of the structure of the initial solar cell after the first photothermal treatment. (Refer to...) Figure 13 This is a schematic diagram of the structure of the initial solar cell after undergoing a second photothermal treatment.

[0102] This embodiment performs dynamic photothermal treatment on the preheated initial solar cell, including: performing a first photothermal treatment on the initial solar cell to cause free hydrogen ions 51 to accumulate on the surface defects of the substrate 10, the first doped layer 21, the second doped layer 22, the first electrode 41, and the second electrode 42, thereby repairing the surface defects of the substrate 10, the first doped layer 21, and the second doped layer 22; and performing a second photothermal treatment on the initial solar cell to cause the hydrogen-silicon bonds 52 in the first doped layer 21, the second doped layer 22, the first passivation layer 31, and the second passivation layer 32 to break and form active hydrogen ions, which are used to repair deep defects in the substrate 10, the first doped layer 21, and the second doped layer 22. During the first photothermal treatment of the initial solar cell in this embodiment, free hydrogen ions 51 also accumulate on the surface defects of the first electrode 41 and the second electrode 42.

[0103] Compared with back contact batteries prepared by existing processes, the back contact battery prepared by the process in this embodiment has improved conversion efficiency, UOC (open circuit voltage), ISC (short circuit current), and FF (fill factor). As shown in Table 2, it is a parameter comparison table between the back contact battery prepared by the process in this embodiment and the back contact battery prepared by existing processes.

[0104] Table 2

[0105] One embodiment of this application relates to a solar cell, which is prepared by the above-described cell preparation method.

[0106] In this embodiment, internal defects in the solar cell are repaired during the fabrication process using the above-described fabrication method, thereby improving the performance of the solar cell, and thus increasing the conversion efficiency and yield of the solar cell.

[0107] One embodiment of this application also relates to a photovoltaic module, including the solar cell described in the above embodiment.

[0108] The photovoltaic module of this embodiment includes the solar cell of the above embodiment, thereby improving the conversion efficiency and yield of the photovoltaic module.

[0109] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing this application, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of this application.

Claims

1. A method for manufacturing a battery, characterized in that, include: Provide initial battery cells; The initial solar cell is a solar cell that has undergone laser-enhanced contact optimization; the initial solar cell includes a substrate, a doped layer, and a passivation layer; the initial solar cell is in an inert gas environment; The initial solar cell is preheated to allow free hydrogen ions in the doped layer and the passivation layer to diffuse into the substrate; The preheated initial solar cell is subjected to dynamic photothermal treatment to break the hydrogen-silicon bonds in the doped layer and the passivation layer to form active hydrogen ions. The free hydrogen ions and the active hydrogen ions repair the defects of the initial solar cell to obtain a repaired solar cell. The repaired battery cells were then tested and sorted.

2. The battery preparation method according to claim 1, characterized in that, The preheating treatment includes a stepped heating process and a constant-temperature diffusion process; the preheating treatment of the initial solar cell includes: The initial battery cell is subjected to a stepped heating process to activate free hydrogen ions in the doped layer and the passivation layer; The initial battery cell is subjected to isothermal diffusion treatment to allow the activated free hydrogen ions to diffuse into the substrate.

3. The battery preparation method according to claim 2, characterized in that, The stepped heating process includes multiple heating stages, each with a heating rate of 5°C / s and a duration of 20s. The temperature of the isothermal diffusion treatment is 250°C to 400°C, and the duration of the isothermal diffusion treatment is 60s to 360s.

4. The battery preparation method according to claim 2, characterized in that, The stepped heating process and the isothermal diffusion process are carried out in a nitrogen atmosphere. The nitrogen concentration corresponding to the stepped heating treatment is less than the nitrogen concentration corresponding to the isothermal diffusion treatment; The nitrogen concentration corresponding to the stepped heating treatment is 4000 sccm to 6000 sccm; the nitrogen concentration corresponding to the isothermal diffusion treatment is 8000 sccm to 10000 sccm.

5. The battery preparation method according to claim 1, characterized in that, The dynamic photothermal treatment includes a first photothermal treatment and a second photothermal treatment; the dynamic photothermal treatment of the preheated initial solar cell includes: The initial solar cell is subjected to a first photothermal treatment to cause the free hydrogen ions to aggregate to the surface defects of the substrate and the surface defects of the doped layer, so as to repair the surface defects of the substrate and the surface defects of the doped layer. The initial solar cell is subjected to a second photothermal treatment to break the hydrogen-silicon bonds in the doped layer and the passivation layer to form active hydrogen ions, which are used to repair deep defects in the substrate and deep defects in the doped layer. Wherein, the light intensity of the first photothermal treatment is less than the light intensity of the second photothermal treatment, and the temperature of the first photothermal treatment is less than the temperature of the second photothermal treatment.

6. The battery manufacturing method according to claim 5, characterized in that, The initial battery cell also includes electrodes; During the preheating process of the initial battery cell, free hydrogen ions in the doped layer and the passivation layer diffuse to the electrode; During the first photothermal treatment of the initial battery cell, the free hydrogen ions also aggregate to the surface defects of the electrode, repairing the surface defects of the electrode.

7. The battery manufacturing method according to claim 5 or 6, characterized in that, The light intensity of the first photothermal treatment is 10 to 15 suns, the temperature of the first photothermal treatment is 300°C to 350°C, and the duration of the first photothermal treatment is 10 to 300 seconds. The light intensity of the second photothermal treatment is 30 to 50 suns, the temperature of the second photothermal treatment is 350°C to 400°C, and the duration of the second photothermal treatment is 10 to 300 seconds.

8. The battery manufacturing method according to claim 5 or 6, characterized in that, The inert gas is argon; The argon concentration corresponding to the first photothermal treatment is the same as the argon concentration corresponding to the second photothermal treatment; the argon concentration corresponding to the first photothermal treatment and the argon concentration corresponding to the second photothermal treatment are both 8000 sccm to 10000 sccm.

9. A solar cell, characterized in that, The solar cell is prepared by the cell preparation method according to any one of claims 1 to 8.

10. A photovoltaic module, characterized in that, include: The solar cell as described in claim 9.

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