Photovoltaic cell and manufacturing method therefor, and photovoltaic module

Abstract

The present disclosure provides a photovoltaic cell and a manufacturing method therefor, and a photovoltaic module. The manufacturing method for the photovoltaic cell comprises: providing a first substrate, the first substrate having a pyramid textured structure formed by first texturing treatment; stacking a plurality of first substrates, or stacking the first substrates and then performing position transfer; and performing second texturing treatment on the first substrates to form second substrates.

Description

Photovoltaic cells and their manufacturing methods, photovoltaic modules

[0001] Cross-reference to related applications

[0002] This disclosure claims priority to Chinese Patent Application No. 202510189282.2, filed with the China National Intellectual Property Administration on February 20, 2025, entitled "A Texturing Method for a Silicon Substrate, a Solar Cell, and a Method for Preparing a Solar Cell"; this disclosure claims priority to Chinese Patent Application No. 202610187711.7, filed with the China National Intellectual Property Administration on February 9, 2026, entitled "Photovoltaic Cell and Manufacturing Method Thereof, Photovoltaic Module"; and this disclosure claims priority to Chinese Patent Application No. 202610194868.2, filed with the China National Intellectual Property Administration on February 9, 2026, entitled "Photovoltaic Cell and Manufacturing Method Thereof, Photovoltaic Module", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the photovoltaic field, and in particular to a photovoltaic cell and its manufacturing method, and a photovoltaic module. Background Technology

[0004] With the rapid development of solar photovoltaic technology, photovoltaic cells are becoming increasingly widely used as a sustainable and clean energy source. A photovoltaic cell is a device that uses the photovoltaic principle to generate charge carriers to convert sunlight into electrical energy. During the manufacturing process of photovoltaic cells, a texturing process is typically required to treat at least part of the substrate surface to form a pyramidal textured structure suitable for light trapping.

[0005] However, the pyramid textured surface structure formed by different texturing processes varies greatly, and the manufacturing process of photovoltaic cells includes other production processes besides texturing. The pyramid textured surface structure will also be affected by subsequent related production processes, which will ultimately affect the complexity of the photovoltaic cell manufacturing process or the photovoltaic cell photoelectric conversion efficiency.

[0006] Public content

[0007] This disclosure provides a photovoltaic cell and its manufacturing method, as well as a photovoltaic module, which at least helps to simplify the manufacturing process of photovoltaic cells, while upgrading from traditional single-area centralized manufacturing, such as from a single long-chain standardized process, to a multi-scenario industrialization technology system, thereby improving manufacturing efficiency and improving the method to enhance the photoelectric conversion efficiency of photovoltaic cells.

[0008] This disclosure provides a method for manufacturing a photovoltaic cell, comprising: providing a first substrate having a pyramidal textured surface structure formed by a first texturing process; stacking a plurality of the first substrates or transferring the positions of the stacked first substrates; and performing a second texturing process on the first substrates to form a second substrate.

[0009] Optionally, the first texturing process is performed at a first production site, and the second texturing process is performed at a second production site; wherein the first production site and the second production site are located in different factories, or the first production site and the second production site are located in different areas of the same factory.

[0010] Optionally, the step of providing the first substrate includes: providing a substrate, performing at least a first wet cleaning process and a first wet texturing process on the substrate; and / or, the step of performing the second texturing process includes at least performing a second wet cleaning process and a second wet texturing process on the first substrate.

[0011] Optionally, after performing the second wet texturing process, the step of performing the second texturing treatment may further include: performing a water washing process; and / or, performing an oxidation cleaning process; and / or, performing a wet acid washing process.

[0012] Optionally, the cleaning solution used in the oxidative cleaning process is a mixed solution comprising hydrochloric acid and ozone, wherein the hydrochloric acid has a weight percentage of 0.01 wt% to 3 wt%, and the concentration of ozone dissolved in the mixed solution is 10 ppm to 60 ppm; or, the cleaning solution used in the oxidative cleaning process is a mixed solution comprising hydrofluoric acid and hydrogen peroxide, wherein the hydrofluoric acid has a weight percentage of 0.5 wt% to 10 wt%, and the hydrogen peroxide has a weight percentage of 0.5 wt% to 10 wt%.

[0013] Optionally, the cleaning solution used in the wet pickling process is a mixed solution comprising hydrofluoric acid and pickling additives, wherein the weight percentage of the hydrofluoric acid is 0.5wt% to 8wt% and the weight percentage of the pickling additives is 0.5wt% to 5wt%.

[0014] Optionally, at least one of the first wet cleaning process and the second wet cleaning process uses a cleaning solution comprising a mixed solution of alkali and hydrogen peroxide, wherein the alkali is sodium hydroxide or potassium hydroxide; wherein the weight percentage of the alkali is 0.1 wt% to 10 wt%, and the weight percentage of the hydrogen peroxide is 0.5 wt% to 10 wt%.

[0015] Optionally, the cleaning solution used in at least one of the first wet texturing process and the second wet texturing process is a mixed solution comprising an alkali and a texturing additive, wherein the alkali is sodium hydroxide or potassium hydroxide; wherein the weight percentage of the alkali is 0.1 wt% to 10 wt%, and the weight percentage of the texturing additive is 0.1 wt% to 10 wt%.

[0016] Optionally, the process temperature of at least one of the first wet texturing process and the second wet texturing process is 55°C to 85°C; and / or, the process duration of at least one of the first wet texturing process and the second wet texturing process is 100s to 800s.

[0017] Optionally, the first substrate has two first surfaces opposite each other along a first direction, at least one of the first surfaces including a first pyramid structure; after the second texturing process, the second substrate has two second surfaces opposite each other along the first direction, at least one of the second surfaces including a second pyramid structure and a first protrusion structure, the first protrusion structure being located on the side and / or side edge of the second pyramid structure, and along the first direction, the height of the first protrusion structure being less than the height of the second pyramid structure, the first direction being the thickness direction of the second substrate.

[0018] Optionally, the base size of the second pyramid structure is greater than or equal to the base size of the first pyramid structure; and / or, the height of the second pyramid structure is greater than or equal to the height of the first pyramid structure.

[0019] Optionally, the base size of the first pyramid structure is 1μm to 4.5μm, and the base size of the second pyramid structure is 1μm to 5μm; and / or, along the first direction, the height of the first pyramid structure is 0.5μm to 2μm, and the height of the second pyramid structure is 0.5μm to 2.5μm.

[0020] Optionally, the first base further has a first side surface connecting the two first surfaces, the first side surface including a third pyramid structure, the base size of the third pyramid structure being smaller than the base size of the first pyramid structure; and / or, the second base further has a second side surface connecting the two second surfaces, the second side surface including a fourth pyramid structure and a second protrusion structure, the second protrusion structure being located on the side surface and / or side edge of the fourth pyramid structure, and along a direction away from the second side surface, the height of the second protrusion structure being smaller than the height of the fourth pyramid structure; the base size of the fourth pyramid structure being smaller than the base size of the second pyramid structure.

[0021] Optionally, in the step of stacking or transferring the positions of multiple first substrates, the first substrate is transformed into an initial second substrate, the initial second substrate having two initial second surfaces opposite each other along the first direction, and an initial second side surface connecting the two initial second surfaces, the initial second side surface including a fifth pyramid structure, at least a portion of the fifth pyramid structure having a defect at the top; in the step of performing the second texturing process, the defect is removed.

[0022] Optionally, the base size of the fifth pyramid structure is 1μm to 3μm, and the height of the fifth pyramid structure in the direction perpendicular to the initial second side is 0.2μm to 1.5μm; and / or, the base size of the fourth pyramid structure is 1μm to 4.5μm, and the height of the fourth pyramid structure in the direction perpendicular to the second side is 0.5μm to 2.5μm.

[0023] Optionally, the step of providing the first substrate includes: providing a substrate; and performing a first texturing process on the substrate to form a first substrate, the first substrate having two first surfaces opposite each other along the first direction, at least one of the first surfaces including the first pyramid structure.

[0024] Optionally, the base size of the third pyramid structure is 1μm to 3μm, and the height of the third pyramid structure in the direction perpendicular to the first side is 0.2μm to 1.5μm; and / or, the base size of the fourth pyramid structure is 1μm to 4.5μm, and the height of the fourth pyramid structure in the direction perpendicular to the second side is 0.5μm to 2.5μm.

[0025] Optionally, in the step of stacking or transferring the positions of multiple first substrates, the first substrates are transformed into initial second substrates, the initial second substrates having two initial second surfaces opposite each other along the first direction, at least one of the initial second surfaces including a sixth pyramid structure, at least a portion of the sixth pyramid structure having a defect at the top; in the step of performing the second texturing process, the defect is removed, wherein the second pyramid structure and the first protrusion structure are formed on the basis of the sixth pyramid structure.

[0026] Optionally, the base size of the second pyramid structure is greater than or equal to the base size of the sixth pyramid structure; and / or, the height of the second pyramid structure is greater than or equal to the height of the sixth pyramid structure.

[0027] Optionally, the base size of the sixth pyramid structure is 1μm to 4.5μm; and / or, the height of the sixth pyramid structure along the first direction is 0.5μm to 2μm.

[0028] Optionally, the method for manufacturing the photovoltaic cell further includes: performing a gettering and impurity removal process before performing the first texturing process; or performing a gettering and impurity removal process after performing the first texturing process and before performing the second texturing process.

[0029] This disclosure also provides a method for manufacturing a photovoltaic cell, comprising: providing an initial second substrate having two initial second surfaces opposite each other along a first direction, the first direction being the thickness direction of the initial second substrate; wherein at least one of the initial second surfaces includes a sixth pyramid structure, and at least a portion of the sixth pyramid structure has a defect at its top; performing a second texturing process on the initial second substrate to remove the defect, and forming a second pyramid structure and a first protrusion structure on the basis of the sixth pyramid structure to form a second substrate; wherein the first protrusion structure is located on the side and / or side edge of the second pyramid structure, and along the first direction, the height of the first protrusion structure is less than the height of the second pyramid structure. Thus, the first protrusion structure located on the side and / or side edge of the second pyramid structure and the second pyramid structure can be considered to jointly constitute a clustered pyramid group, which is beneficial for forming more light-trapping areas to improve the light-trapping effect of the second surface of the second substrate. Moreover, the clustered pyramid group makes the second surface of the second substrate rougher, which is more conducive to the formation of better ohmic contact between the subsequent electrode and the second substrate, thereby improving the photoelectric conversion efficiency of the photovoltaic cell in terms of both light utilization and conductivity. In other words, compared to conventional textured surfaces, such as the pyramid textured structure of the first substrate, the height difference between the first protrusion on the side and / or side edge of the second pyramid structure and the cluster pyramid group formed by the second pyramid structure is smaller, or the unevenness per unit area is lower. This is more conducive to the formation of subsequent passivation contact structures and electrode printing. Furthermore, the cluster pyramid group makes more effective use of the gaps between adjacent second pyramid structures, increasing the density and compactness of the textured surface, reducing the reflectivity of the second substrate, and is more conducive to the passivation and current enhancement of photovoltaic cells, thereby improving the photoelectric performance of photovoltaic cells.

[0030] Optionally, the initial second base also has an initial second side surface connecting the two initial second surfaces, the initial second side surface including a fifth pyramid structure, and at least a portion of the fifth pyramid structure having the defect portion at its top; in the step of performing the second texturing process, the defect portion is removed, and a fourth pyramid structure and a second protrusion structure are formed on the basis of the fifth pyramid structure; wherein, the second protrusion structure is located on the side surface and / or side edge of the fourth pyramid structure, and along a direction away from the initial second side surface, the height of the second protrusion structure is less than the tower height of the fourth pyramid structure.

[0031] Optionally, the base size of the fifth pyramid structure is smaller than the base size of the sixth pyramid structure; and / or, the base size of the fourth pyramid structure is smaller than the base size of the second pyramid structure.

[0032] Optionally, the base size of the fifth pyramid structure is 1μm to 3μm, and the height of the fifth pyramid structure in the direction perpendicular to the initial second side is 0.2μm to 1.5μm; and / or, the base size of the fourth pyramid structure is 1μm to 4.5μm, and the height of the fourth pyramid structure in the direction perpendicular to the second side is 0.5μm to 2.5μm.

[0033] Optionally, the step of providing the initial second substrate includes: providing a substrate; performing a first texturing process on the substrate to form a first substrate, the first substrate having two first surfaces opposite each other along the first direction, at least one of the first surfaces including a first pyramid structure; stacking a plurality of the first substrates or stacking the initial second substrates and then performing a position transfer, such that the first substrates are transformed into the initial second substrate.

[0034] Optionally, the step of providing the initial second substrate includes: providing a substrate; performing a first texturing process on the substrate to form a first substrate, the first substrate having two first surfaces opposite each other along the first direction and a first side surface connecting the two first surfaces, the first side surface including a third pyramid structure; and stacking a plurality of the first substrates such that the first substrates are transformed into the initial second substrate.

[0035] This disclosure also provides a photovoltaic cell, which is formed by the manufacturing method of the photovoltaic cell described in any of the preceding claims.

[0036] This disclosure also provides a photovoltaic module, comprising: a battery string, which is formed by connecting a plurality of photovoltaic cells manufactured by any of the above methods, or by connecting a plurality of photovoltaic 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 opposite to the battery string.

[0037] The technical solutions provided in this disclosure have at least the following advantages:

[0038] By interleaving the stacking or post-stack relocation steps between the first and second texturing processes, several advantages are achieved. First, even if impurities or debris are generated on the surface of the first substrate during the stacking or relocation steps, the second texturing process can remove them and refine the details of the pyramidal textured surface, ensuring the final second substrate also possesses a good textured morphology. Second, the stacking or relocation steps remove the apex of the pyramidal textured surface on the first substrate, further aided by the second texturing process to achieve rounding of the pyramidal textured surface. This eliminates the need for a separate rounding process, achieving both cleaning and apex rounding of the pyramidal textured surface, thereby improving the uniformity of the film thickness formed on the second substrate and enhancing the ohmic contact between the subsequent electrodes and the second substrate. This approach simplifies the photovoltaic cell manufacturing process while simultaneously improving the photoelectric conversion efficiency of the photovoltaic cells. Attached Figure Description

[0039] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures 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 disclosure or the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 is a process flow diagram of a method for manufacturing photovoltaic cells according to an embodiment of the present disclosure;

[0041] Figure 2 is a schematic cross-sectional view of a first substrate in a photovoltaic cell manufacturing method according to an embodiment of the present disclosure;

[0042] Figure 3 is a schematic cross-sectional view of a photovoltaic cell manufacturing method provided in an embodiment of the present disclosure after multiple first substrates are stacked.

[0043] Figure 4 is a scanning electron microscope image of the initial second surface of the initial second substrate in a photovoltaic cell manufacturing method provided in an embodiment of the present disclosure;

[0044] Figure 5 is a scanning electron microscope image of the initial second side of the initial second substrate in a photovoltaic cell manufacturing method provided in an embodiment of the present disclosure;

[0045] Figure 6 is a schematic cross-sectional view of an initial second substrate in a photovoltaic cell manufacturing method according to an embodiment of the present disclosure;

[0046] Figure 7 is a scanning electron microscope image of a second substrate in a photovoltaic cell manufacturing method provided in an embodiment of this disclosure;

[0047] Figure 8 is a schematic cross-sectional view of a second substrate in a photovoltaic cell manufacturing method according to an embodiment of the present disclosure;

[0048] Figure 9 is a schematic cross-sectional view of a substrate in a photovoltaic cell manufacturing method according to an embodiment of the present disclosure;

[0049] Figure 10 is a schematic cross-sectional view of a photovoltaic cell in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure.

[0050] Figure 11 is a schematic cross-sectional view of another photovoltaic cell in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure;

[0051] Figure 12 is a partial three-dimensional schematic diagram of a battery string in a photovoltaic module provided in another embodiment of the present disclosure;

[0052] Figure 13 is a partial cross-sectional schematic diagram of a photovoltaic module provided in another embodiment of this disclosure.

[0053] Figure 14 is a top-view SEM image of the silicon substrate obtained in Embodiment 1 of this disclosure on an 8μm scale.

[0054] Figure 15 is a side-view SEM image of the silicon substrate obtained in Embodiment 1 of this disclosure on an 8μm scale.

[0055] Figure 16 is a top-view SEM image of the silicon substrate obtained in Comparative Example 1 of this disclosure on an 8 μm scale.

[0056] Figure 17 is a side-view SEM image of the silicon substrate obtained in Comparative Example 1 of this disclosure on an 8 μm scale.

[0057] Figure 18 is a top-view SEM image of the silicon substrate obtained in Comparative Example 2 of this disclosure on an 8 μm scale.

[0058] Figure 19 is a side-view SEM image of the silicon substrate obtained in Comparative Example 2 of this disclosure on an 8 μm scale.

[0059] Figure 20 is a top-view SEM image of the silicon substrate obtained in Comparative Example 3 of this disclosure on an 8 μm scale.

[0060] Figure 21 is a side-view SEM image of the silicon substrate obtained in Comparative Example 3 of this disclosure on an 8 μm scale.

[0061] Figure 22 is a schematic diagram of the clustered pyramid velvet structure disclosed herein.

[0062] Figure 23 is a cross-sectional schematic diagram of the clustered pyramid velvet structure described in this disclosure.

[0063] Figure 24 is a schematic diagram of the structure of the silicon substrate surface pyramid obtained by the conventional method in Comparative Example 3 of this disclosure.

[0064] Figure 25 is a schematic cross-sectional view of the pyramid structure on the surface of a silicon substrate obtained by the conventional method of Comparative Example 3 of this disclosure.

[0065] Figure 26 is a flowchart of the flocking method described in this disclosure.

[0066] Explanation of reference numerals in the attached drawings: 100, First base; 110, First surface; 120, First pyramid structure; 130, First side surface; 140, Third pyramid structure; 101, Second base; 111, Second surface; 121, Second pyramid structure; 131, First protrusion structure; 141, Second side surface; 151, Fourth pyramid structure; 161, Second protrusion structure; 102, Substrate; 103, Initial second base; 113, Initial second surface; 123, Initial second side surface; 133, Fifth pyramid structure Structure; 143, Defect section; 153, Sixth pyramid structure; 104, Passivated contact structure; 1041, First passivated contact structure; 1042, Second passivated contact structure; 114, Dielectric layer; 1141, First dielectric layer; 1142, Second dielectric layer; 124, Doped layer; 1241, First doped layer; 1242, Second doped layer; 105, Electrode; 115, First electrode; 125, Second electrode; 40, Photovoltaic cell; 41, Encapsulating film; 42, Cover plate; 43, Solder ribbon. 1. Main pyramid; 2. Dependent pyramid; 3. Large pyramid with primary texturing; 4. Small pyramid with secondary texturing. Detailed Implementation

[0067] As can be seen from the background technology, the complexity of photovoltaic cell manufacturing processes needs to be reduced and the photoelectric conversion efficiency of photovoltaic cells needs to be improved.

[0068] This disclosure provides a photovoltaic cell and its manufacturing method, as well as a photovoltaic module. In the manufacturing method, the steps of stacking or transferring the stacked components are interspersed between a first texturing process and a second texturing process. On one hand, even if impurities or debris are generated on the surface of the first substrate during the stacking or transfer process, these impurities or debris can be removed by the second texturing process. Furthermore, the second texturing process can refine the details of the pyramidal textured surface, ensuring that the final second substrate also has a good textured surface morphology. On the other hand, the stacking or transfer process can remove the apex of the pyramidal textured surface of the first substrate. Further assistance with the second texturing process can achieve rounding of the pyramidal textured surface, thus eliminating the need for a separate rounding process. This achieves both cleaning and apex rounding of the pyramidal textured surface, thereby improving the uniformity of the film thickness formed on the second substrate and enhancing the ohmic contact between the subsequent electrodes and the second substrate. This simplifies the photovoltaic cell manufacturing process while improving the photoelectric conversion efficiency of the photovoltaic cell.

[0069] In the description of the embodiments of this disclosure, 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 or secondary relationship of the indicated technical features. In the description of the embodiments of this disclosure, "a plurality of" means two or more, unless otherwise explicitly defined.

[0070] 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 disclosure. 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.

[0071] In the description of the embodiments of this disclosure, 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. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0072] In the description of the embodiments of this disclosure, the term "multiple" refers to two or more (including two), similarly, "multiple groups" refers to two or more (including two groups), and "multiple pieces" refers to two or more (including two pieces).

[0073] In the description of the embodiments of this disclosure, 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 disclosure 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 disclosure.

[0074] In the description of the embodiments of this disclosure, 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. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0075] In the accompanying drawings corresponding to the embodiments of this disclosure, 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.

[0076] In the description of embodiments of this disclosure, when a component "includes" another component, other components are not excluded unless otherwise stated, and 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 in between), 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 component is located therein.

[0077] 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.

[0078] 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 embodiments. However, the technical solutions claimed in the embodiments of this disclosure can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0079] This disclosure provides a method for manufacturing a photovoltaic cell according to an embodiment. The method for manufacturing a photovoltaic cell according to an embodiment of this disclosure will be described in detail below with reference to the accompanying drawings.

[0080] Figure 1 is a process flow diagram of a photovoltaic cell manufacturing method according to an embodiment of this disclosure. Referring to Figures 1 to 8, the photovoltaic cell manufacturing method includes at least the following steps:

[0081] S1: A first substrate 100 is provided, the first substrate 100 having a pyramidal textured surface structure formed by a first texturing process. Referring to FIG2, FIG2 is a schematic cross-sectional view of the first substrate 100 in a photovoltaic cell manufacturing method provided in an embodiment of the present disclosure.

[0082] S2: Referring to Figures 2 to 6, multiple first substrates 100 are stacked or their positions are transferred after being stacked.

[0083] It should be noted that Figure 3 is a cross-sectional structural diagram of a photovoltaic cell manufacturing method provided in an embodiment of this disclosure after multiple first substrates are stacked. Figures 4 to 6 will be described in detail later with reference to specific embodiments. In addition, to illustrate the positional relationship of the multiple first substrates 100, the textured surface features of the first substrates 100 are not shown in Figure 3.

[0084] S3: Referring to Figures 2 to 8, the first substrate 100 is subjected to a second texturing process to form a second substrate 101. Figure 7 is a scanning electron microscope image of the second substrate in a photovoltaic cell manufacturing method according to an embodiment of this disclosure; Figure 8 is a cross-sectional structural diagram of the second substrate in a photovoltaic cell manufacturing method according to an embodiment of this disclosure.

[0085] Generally, in the manufacturing process of photovoltaic cells, the substrate needs to be transferred between multiple production processes. To facilitate storage and transfer, multiple substrates are usually stacked. During the stacking and transfer processes, there is a risk that the surface morphology of the substrate will change, and impurities may be introduced, resulting in the final photovoltaic cell failing to achieve the expected electrical performance. In addition, for pyramidal textured structures, if the apex of the pyramid is relatively sharp, it is not conducive to the formation of a uniform thickness film layer on the pyramidal textured structure, nor is it conducive to the contact between the subsequent electrodes and the pyramidal textured structure. Furthermore, the apex is prone to becoming a severe carrier recombination center.

[0086] Based on this, the stacking or post-stack transfer steps are interspersed between the first and second texturing processes. On the one hand, even if impurities or debris are generated on the surface of the first substrate 100 during the stacking or post-stack transfer steps, such as the defect 143 shown in Figures 4 to 6, the second texturing process can remove these impurities or debris and refine the details of the pyramid textured surface, ensuring that the final second substrate 101 also has a good textured surface morphology. On the other hand, the stacking or post-stack transfer steps can remove the apex of the pyramid textured surface of the first substrate 100, and further assist the second texturing process to achieve rounding of the pyramid textured surface. Therefore, the cleaning and apex rounding of the pyramid textured surface can be achieved without additional separate rounding treatment, thereby improving the thickness uniformity of the film layer subsequently formed on the second substrate 101 and improving the ohmic contact between the subsequent electrodes and the second substrate 101. In this way, it is beneficial to improve the photoelectric conversion efficiency of photovoltaic cells while simplifying the manufacturing process of photovoltaic cells.

[0087] The following will describe in more detail a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure, with reference to the accompanying drawings.

[0088] In some embodiments, referring to FIG1, a first texturing process is performed at a first place of origin, and a second texturing process is performed at a second place of origin. It is understood that the first substrate 100 (referring to FIG2) that has undergone the first texturing process can be regarded as a semi-finished substrate, the place of origin of the first substrate 100 can be regarded as the first place of origin, and the place of origin of the second substrate 101 (referring to FIG8) that has finally undergone the second texturing process is the second place of origin.

[0089] The following describes in detail the origin of the first and second texturing processes through two scenarios.

[0090] In some cases, the primary and secondary production sites can be located in different factories. It is worth noting that forming photovoltaic cells requires multiple processes, and the execution of these processes relies on various production equipment. The technical control of the texturing process has a significant impact on the formation of semiconductor or conductive layers in the subsequent cells, as well as the optical and electrical efficiency of the finished cells. Cell texturing is a wet process, affected by temperature, water quality, solution, and subsequent cell connection processes. The traditional single-region centralized manufacturing model has long been hampered by planned production bottlenecks. Furthermore, the equipment linkage and process connection between the substrate or base texturing process and the cell conductive layer process are complex, with a narrow scope of coordination, failing to simultaneously improve manufacturing capacity, efficiency, and cost. On the one hand, given the limited mass production scale, the implementation method provided in this disclosure breaks through the limitations of a single-region standardized production line model to a regional manufacturing system. This can drive the matching of equipment, raw materials, and auxiliary materials resources in multiple regions to adapt to the core processes, promoting technological upgrades. On the other hand, for local application scenarios in each production area, the short-chain manufacturing system allows for customized optimization of processes, significantly improving mass production capabilities through technology scenario-based expansion.

[0091] Moreover, the regional manufacturing method of wet texturing process can form a positive technology closed loop in which the core process drives the supporting technology and the supporting technology in turn supports the core process. This effect cannot be achieved by traditional single-region manufacturing, and ultimately improves the technical level of the entire photovoltaic cell industry chain, rather than the progress of a single link.

[0092] Furthermore, considering factors such as the construction costs of various production equipment (e.g., the construction costs of the same production line vary in different cities or countries, and the differences in construction costs in some regions are significant), the site requirements of various production equipment, the environmental impact of various production equipment (e.g., the standards for judging the environmental impact of a production line differ in different cities or countries, thus the handling methods of raw materials will also differ when constructing a production line), and the continuous innovation of technology, the first and second texturing processes can be designed to be carried out in different factories. In this way, while simplifying the manufacturing process of photovoltaic cells and improving the photoelectric conversion efficiency of photovoltaic cells, on the one hand, it helps to solve the problem of insufficient production lines in a single factory, enabling factories that can only perform the first texturing process to also start production; on the other hand, it facilitates the coordination between the stacking or post-stack transfer steps and the second texturing process, allowing different factories to collaborate to improve technology and increase production capacity. This represents a breakthrough from the limited mass production scale of a single region to regional manufacturing, ensuring the production efficiency of each region or factory, and the cross-regional connection and deep matching of various processes. This also reduces the construction cost of a single factory, thereby helping to reduce the manufacturing cost of photovoltaic cells.

[0093] In other cases, the first and second production sites may also be located in different areas of the same factory. It is worth noting that, based on the overall layout planning of a single factory, there may be a distance between different production lines that requires material handling. Based on this, referring to Figures 3 to 8, multiple first substrates 100 are first stacked or stacked and then moved to transform the first substrates 100 into initial second substrates 103. Then, the initial second substrates 103 are subjected to a second texturing process, which also helps to simplify the manufacturing process of photovoltaic cells while improving the photoelectric conversion efficiency of photovoltaic cells.

[0094] In both of the above scenarios, referring to Figure 2, multiple first substrates 100 are stacked in the same support structure (not shown in the figure). Before the second texturing process, the support structure carrying multiple first substrates 100 is transported from the first production site to the second production site.

[0095] In some examples, the support structure carrying multiple first substrates 100 can be a quartz boat, a graphite boat, or a basket. Quartz boats are mainly used in high-temperature oxidation or high-temperature annealing processes, or as external containers for graphite boats; specifically, the first substrates 100 are inserted into slots in the quartz boat. Graphite boats are mainly used in diffusion or chemical vapor deposition processes; specifically, the first substrates 100 are inserted into slots in the graphite boat. Baskets are mainly used in wet processes such as texturing, cleaning, and etching that require acid or alkali baths; specifically, the first substrates 100 are inserted into slots in a specially designed basket, with the entire basket immersed in or passing through the acid or alkali bath.

[0096] In some embodiments, since the second substrate 101 is formed by performing a second texturing process on the first substrate 100 after stacking or after repositioning, the weight of the second substrate 101 is reduced by about 0.05g to 0.35g compared with the weight of the first substrate 100. For example, it can be 0.05g, 0.1g, 0.15g, 0.2g, 0.25g, 0.3g or 0.35g, etc.

[0097] In some cases, the reflectivity of the first surface 110 (or pyramidal textured structure) of the first substrate 100 can be 7% to 12%, for example, 7%, 8%, 9%, 10%, 11%, or 12%; the reflectivity of the surface formed in the second substrate 101 based on the pyramidal textured structure of the first substrate 100 (or the second surface 111 formed based on the first surface 110) can be 8% to 15%, for example, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%.

[0098] In some embodiments, referring to Figures 9 and 2, Figure 9 is a schematic cross-sectional view of a substrate in a photovoltaic cell manufacturing method according to an embodiment of the present disclosure. The step of providing a first substrate 100 may include: providing a substrate 102, and performing at least a first wet cleaning process and a first wet texturing process on the substrate 102. In other words, the step of performing the first texturing process includes at least a first wet cleaning process and a first wet texturing process. The first wet cleaning process can remove dirt from the surface of the substrate 102; the first wet texturing process can form a pyramidal textured structure on at least one surface of the substrate 102 to form the first substrate 100 and lay the foundation for the surface morphology of the subsequently formed second substrate 101.

[0099] Alternatively, the step of providing the initial second substrate 103 may at least include performing a first texturing process. The first texturing process may include performing a first wet cleaning process and a first wet texturing process. In other words, the first texturing process includes at least performing a first wet cleaning process and a first wet texturing process on the substrate 102. The second wet cleaning process can remove contaminants from the surface of the substrate 102; the second wet texturing process can form a pyramidal textured structure on at least one surface of the substrate 102 to form the first substrate 100 and lay the foundation for the surface morphology of the subsequently formed second substrate 101.

[0100] In some cases, the substrate 102 undergoes a first texturing process to form a first substrate 100. The weight of the first substrate 100 is reduced by about 0.2g to 0.8g compared to the weight of the substrate 102. For example, it can be 0.2g, 0.3g, 0.4g, 0.5g, 0.6g, 0.7g, or 0.8g.

[0101] In some embodiments, referring to Figures 2 to 8, the second texturing process includes at least a second wet cleaning process and a second wet texturing process on the first substrate 100 (or the initial second substrate 103). In other words, the second texturing process includes at least a second wet cleaning process and a second wet texturing process. The second wet cleaning process cleans the first substrate 100 (or the initial second substrate 103) after the first texturing process, for example, removing newly added dirt (i.e., newly added dirt on the surface of the initial second substrate 103) from the first substrate 100 during the stacking or post-stack relocation process. The second wet texturing process removes impurities or debris generated during the stacking or post-stack relocation process (i.e., impurities or debris generated on the surface of the initial second substrate 103), and can modify the pyramidal textured surface of the initial second substrate 103, for example, by rounding the apex of the pyramidal textured surface.

[0102] It should be noted that when designing the first texturing process, which includes the first wet cleaning process and the first wet texturing process, the second texturing process, which includes the second wet cleaning process and the second wet texturing process, is also designed simultaneously.

[0103] The following details the process steps involved in the first and second texturing processes.

[0104] In some cases, the cleaning solution used in at least one of the first wet cleaning process and the second wet cleaning process may be a mixed solution including alkali and hydrogen peroxide, wherein the alkali may be sodium hydroxide or potassium hydroxide.

[0105] In some examples, in at least one of the first wet cleaning process and the second wet cleaning process, the weight percentage of alkali can be from 0.1 wt% to 10 wt%, for example, it can be 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%. The weight percentage of hydrogen peroxide can be 0.5wt% to 10wt%, for example, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt%, or 10wt%.

[0106] It should be noted that both the first and second wet cleaning processes can use a mixed solution comprising alkali and hydrogen peroxide as the cleaning solution. In practical applications, the weight percentage of alkali in both processes can be selected from 0.1 wt% to 10 wt% according to specific requirements, and the weight percentage of hydrogen peroxide in both processes can be selected from 0.5 wt% to 10 wt% according to specific requirements. Furthermore, the relative weight percentages of alkali and hydrogen peroxide in both processes can be flexibly designed according to specific needs.

[0107] In some cases, the cleaning solution used in at least one of the first wet texturing process and the second wet texturing process may be a mixed solution comprising an alkali and a texturing additive, wherein the alkali may be sodium hydroxide or potassium hydroxide.

[0108] In some examples, in at least one of the first wet texturing process and the second wet texturing process, the weight percentage of alkali can be from 0.1 wt% to 10 wt%, for example, it can be 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%. 9.5wt% or 10wt%, etc.; the weight percentage of the flocking additive can be from 0.1wt% to 10wt%, for example, it can be 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt%, or 10wt%, etc.

[0109] It should be noted that both the first and second wet texturing processes can use a mixed solution comprising alkali and texturing additives as the cleaning solution. In practical applications, the weight percentage of alkali in both the first and second wet texturing processes can be selected from 0.1 wt% to 10 wt% according to specific requirements, as can the weight percentage of texturing additives in both processes.

[0110] Furthermore, the relationship between the weight percentage of alkali in the first wet texturing process and the second wet texturing process can include the following two examples:

[0111] In some examples, the weight percentage of alkali in the first wet texturing process can be designed to be lower than that in the second wet texturing process. Thus, based on the pyramidal textured surface structure or the first substrate 100 formed by the first texturing process, the second texturing process can utilize a cleaning solution with a higher weight percentage of alkali to remove impurities or debris and round the apex of the pyramidal textured surface structure of the first substrate 100, while simultaneously forming additional protruding structures around the pyramidal structure included in the second substrate 101 (refer to Figure 8) to enhance the light-trapping ability of the second substrate 101. It should be noted that the surface morphology of the second substrate 101 will be described in detail later.

[0112] In other examples, the weight percentage of alkali in the first wet texturing process may also be greater than or equal to the weight percentage of alkali in the second wet texturing process.

[0113] Furthermore, the weight percentage relationship between the texturing additives in the first and second wet texturing processes can be flexibly designed according to specific requirements.

[0114] In some examples, the process temperature of at least one of the first and second wet texturing processes can be between 55℃ and 85℃, for example, it can be 55℃, 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, or 85℃, etc. It should be noted that in practical applications, the process temperature of both the first and second wet texturing processes can be selected within the range of 55℃ to 85℃ according to specific requirements.

[0115] In some examples, the process time of at least one of the first and second wet texturing processes can be between 100s and 800s, for example, 100s, 150s, 200s, 250s, 300s, 350s, 400s, 450s, 500s, 550s, 600s, 650s, 700s, 750s, or 800s. It should be noted that in practical applications, the process time of both the first and second wet texturing processes can be selected within the range of 100s to 800s according to specific requirements.

[0116] The following details the other process steps that may be included in the first texturing process.

[0117] In some cases, in addition to the first texturing process including the first wet cleaning process and the first wet texturing process, the first texturing process may also include: performing a first lifting process and a first drying process on the substrate 102 (refer to FIG. 9) that has undergone the first wet texturing process.

[0118] In some examples, the first lifting process can use a pure water overflow method to slowly, uniformly, and vertically lift the substrate 102 that has undergone the first wet texturing process out of the water tank, so as to clean the residual cleaning liquid on its surface and improve the hydrophobicity of its surface, thereby minimizing the risk of water stains or trace impurities remaining on the surface of the substrate 102 that has undergone the first wet texturing process, so as to achieve the purpose of cleaning the surface of the substrate 102 that has undergone the first wet texturing process.

[0119] In some examples, the first drying process may use hot air at a temperature of 65°C to 90°C, such as 65°C, 70°C, 75°C, 80°C, 85°C, or 90°C, to dry the surface of the substrate 102 that has undergone the first pulling process. In one example, the hot air may be ozone-filtered air to reduce the risk of oxidation of the substrate 102 that has undergone the first pulling process.

[0120] The following details the other process steps that may be included in the second texturing process.

[0121] In some cases, after the second wet texturing process, the second texturing step may also include a water washing process. For example, a pure water circulation bubbling and overflow method can be used to create a continuous upward flow of pure water to wash the first substrate 100 (refer to Figure 2) or the initial second substrate 103 that has undergone the second wet texturing process, in order to rinse off contaminants attached to its surface and continuously dilute and remove residual cleaning solution.

[0122] In some cases, after the second wet texturing process, the second texturing process may further include: performing an oxidation cleaning process to clean the residual cleaning solution used in the second wet texturing process, and removing the surface damage layer of the first substrate 100 (refer to FIG. 2) or the initial second substrate 103 that has undergone the second wet texturing process.

[0123] In some cases, after the second wet texturing process, the second texturing treatment step may also include: performing a wet acid washing process to dilute the residual cleaning solution used in the second wet texturing process with acid, thereby achieving the purpose of cleaning the surface of the first substrate 100 (refer to FIG. 2) or the initial second substrate 103 that has undergone the second wet texturing process.

[0124] In one example, after the second wet texturing process, the washing process, oxidation cleaning process, and wet acid washing process can be performed sequentially.

[0125] In one example, after the wet pickling process, the second texturing process may further include: performing a second lifting process and a second drying process on the first substrate 100 (or the initial second substrate 103) that has undergone the wet pickling process.

[0126] In the second lifting process, a pure water overflow method can be used to slowly, uniformly, and vertically lift the first substrate 100 (or the initial second substrate 103) that has undergone the wet pickling process from the water tank. This is to clean the residual cleaning liquid on its surface and improve its hydrophobicity, thereby minimizing the risk of water stains or trace impurities remaining on its surface and achieving the purpose of cleaning its surface. In the second drying process, hot air at a temperature of 65℃ to 90℃, such as 65℃, 70℃, 75℃, 80℃, 85℃, or 90℃, can be used to dry the surface of the first substrate 100 (or the initial second substrate 103) that has undergone the wet pickling process. The hot air can be ozone-filtered air to reduce the risk of oxidation of the first substrate 100 (or the initial second substrate 103) that has undergone the second lifting process.

[0127] The following two examples illustrate the oxidation cleaning process in detail.

[0128] In some examples, the cleaning solution used in the oxidative cleaning process can be a mixed solution comprising hydrochloric acid and ozone. The hydrochloric acid can be present in a weight percentage ranging from 0.01 wt% to 3 wt%, for example, 0.01 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2... The concentrations of ozone dissolved in the mixed solution can range from 10 ppm to 60 ppm, for example, 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, 35 ppm, 40 ppm, 45 ppm, 50 ppm, 55 ppm, or 60 ppm.

[0129] In other examples, the cleaning solution used in the oxidation cleaning process can be a mixed solution including hydrofluoric acid and hydrogen peroxide. The hydrofluoric acid can be present in a weight percentage of 0.5 wt% to 10 wt%, for example, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, or 10 wt%, etc.; the hydrogen peroxide can be present in a weight percentage of 0.5 wt% to 10 wt%, for example, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, or 10 wt%, etc.

[0130] The following is a detailed explanation of the wet pickling process.

[0131] In some examples, the cleaning solution used in the wet pickling process can be a mixed solution comprising hydrofluoric acid and pickling additives. The hydrofluoric acid comprises 0.5 wt% to 8 wt% by weight, for example, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, or 8 wt% by weight; the pickling additives comprise 0.5 wt% to 5 wt% by weight, for example, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, or 5 wt%.

[0132] The surface morphology of the first substrate 100 (refer to FIG. 2) and the second substrate 101 (refer to FIG. 8) will be described in detail below.

[0133] In some embodiments, referring to FIG2, the first substrate 100 has two first surfaces 110 opposite each other along a first direction X, and at least one first surface 110 includes a first pyramid structure 120. It should be noted that FIG2 uses the example of both first surfaces 110 of the first substrate 100 including the first pyramid structure 120. In actual applications, only one first surface may include the first pyramid structure as required, and the other first surface may be formed as a polished surface or other surface morphology.

[0134] Referring to Figure 8, after the second texturing process, the second substrate 101 has two second surfaces 111 opposite each other along the first direction X. At least one second surface 111 includes a second pyramid structure 121 and a first protrusion structure 131. The first protrusion structure 131 is located on the side and / or side edge of the second pyramid structure 121 and along the first direction X. The height of the first protrusion structure 131 is less than the height of the second pyramid structure 121. The first direction X is the thickness direction of the second substrate 101. It should be noted that Figure 8 uses the example where both second surfaces 111 of the second substrate 101 include the second pyramid structure 121 and the first protrusion structure 131. In practical applications, only one second surface may include the second pyramid structure and the first protrusion structure, and the other second surface may be formed as a polished surface or other surface morphology, depending on the requirements. In existing technologies, different texturing processes produce pyramidal textured surfaces with significant differences. Further research is needed to determine which pyramidal textured surface morphology is most conducive to light trapping. Furthermore, the manufacturing process of photovoltaic cells may involve multiple texturing processes, or other production processes besides texturing, which can easily affect the morphology of the initially formed pyramidal textured surface. The first and second texturing processes described in this application at least facilitate the formation of a second substrate with a unique surface morphology while simultaneously removing defects.

[0135] It is worth noting that, referring to Figures 2 to 8, the first surface 110 undergoes a second texturing process after being stacked or repositioned, and then transforms into the second surface 111. In other words, the first pyramid structure 120 is formed after the first texturing process; the second pyramid structure 121 and the first protrusion structure 131 are formed after the second texturing process, and the second pyramid structure 121 is formed on the basis of a portion of the first pyramid structures 120. Compared to the morphology of the first surface 110 of the first substrate 100, the morphology of the second surface 111 of the second substrate 101 includes not only the second pyramid structure 121 but also the first protrusion structure 131. The first protrusion structure 131 surrounds the second pyramid structure 121. Thus, the first protrusion structure 131 located on the side and / or side edge of the second pyramid structure 121 and the second pyramid structure 121 can be regarded as jointly forming a clustered pyramid group, which is conducive to forming more light-trapping areas to improve the light-trapping effect of the second surface 111 of the second substrate 101. Moreover, the clustered pyramid group makes the second surface 111 of the second substrate 101 rougher, which is more conducive to the formation of better ohmic contact between the subsequent electrode and the second substrate 101, thereby improving the photoelectric conversion efficiency of the photovoltaic cell in terms of both light utilization and conductivity. In other words, compared to conventional textured surfaces, such as the pyramid textured structure of the first substrate 100, the height difference within the clustered pyramid group formed by the first protrusion 131 on the side and / or side edge of the second pyramid structure 121 and the second pyramid structure 121 is smaller, or the unevenness per unit area is lower. This is more conducive to the formation of subsequent passivation contact structures and electrode printing. Furthermore, the clustered pyramid group makes more effective use of the gaps between adjacent second pyramid structures 121, increasing the density and compactness of the textured surface, reducing the reflectivity of the second substrate 101, and is more conducive to the passivation and current enhancement of photovoltaic cells, thereby improving the photoelectric performance of photovoltaic cells.

[0136] It should be noted that, referring to Figures 7 and 8, at least a portion of the first protruding structures 131 can be considered as incomplete pyramid structures. For example, the first protruding structure 131 can be considered as a sheet-like pyramid structure. Along the direction from the apex to the base, the portion of the first protruding structure 131 near the base is blocked by the side and / or side edges of the second pyramid structure 121 during its extension. This results in a smaller extension area on the side of the first protruding structure 131 that contacts the second pyramid structure 121, thus presenting a first protruding structure 131 with a apex but not a complete pyramid structure overall. Furthermore, in addition to contacting the second pyramid structure 121, a portion of the first protruding structures 131 may also contact another first protruding structure 131 on the other side. In other words, at least two first protruding structures 131 can be stacked on the surface of the same second pyramid structure 121, making the first protruding structure 131 more closely resemble a sheet-like structure.

[0137] Based on this, the base size of the first protrusion structure 131 can be understood as the base size when the first protrusion structure 131 extends into a complete pyramid structure without being blocked by the second pyramid structure 121, and the base size of the first protrusion structure 131 can be smaller than the base size of the second pyramid structure 121.

[0138] In some cases, referring to Figures 2, 6, and 8, the base size of the second pyramid structure 121 can be greater than or equal to the base size of the first pyramid structure 120. It is worth noting that the second pyramid structure 121 is formed after the first pyramid structure 120 undergoes stacking or repositioning after stacking, followed by a second texturing process. Based on this, in the second texturing step, in addition to modifying the top of the first pyramid structure 120 along the first direction X, the base of the first pyramid structure 120 can be further etched to form a second pyramid structure 121 with a larger base size. Thus, the larger base size of the second pyramid structure 121 facilitates the attachment of more first protrusions 131, resulting in a more uneven cluster of pyramids, which is more conducive to improving the light-trapping effect of the second substrate 101 and facilitating better ohmic contact between the subsequent electrodes and the second substrate 101. Furthermore, it is worth noting that the stacking process or the subsequent position transfer step has little impact on the base of the first pyramid structure 120, so the base size of the first pyramid structure 120 is similar to that of the sixth pyramid structure 153. Further, in the second texturing process, along the first direction X, in addition to modifying the top of the sixth pyramid structure 153, the base of the sixth pyramid structure 153 can be further etched to form a second pyramid structure 121 with a larger base size. Thus, the base size of the second pyramid structure 121 can be greater than or equal to the base size of the sixth pyramid structure 153.

[0139] In some embodiments, referring to Figures 6 and 8, the base size of the second pyramid structure 121 is greater than or equal to the base size of the sixth pyramid structure 153. Thus, the larger base size of the second pyramid structure 121 facilitates the attachment of more first protrusion structures 131, resulting in a cluster of pyramids with a more uneven surface morphology. This is more conducive to improving the light-trapping effect of the second substrate 101 and to forming better ohmic contact between the subsequent electrodes and the second substrate 101.

[0140] In some cases, referring to Figures 2 and 8, the height of the second pyramid structure 121 can be greater than or equal to the height of the first pyramid structure 120. It is worth noting that the second pyramid structure 121 is formed by re-texturing the first pyramid structure 120. Therefore, along the first direction X, the first substrate 100 is etched along its thickness, resulting in a greater height for the second pyramid structure 121. Thus, the greater height of the second pyramid structure 121 facilitates the stacking of multiple first protrusions 131 on their sides and / or side edges, forming a cluster of pyramids with a more uneven surface morphology. This is more conducive to improving the light-trapping effect of the second substrate 101 and to forming better ohmic contact between the subsequent electrodes and the second substrate 101.

[0141] Furthermore, it is noteworthy that in the second texturing process, along the first direction X, the initial second substrate 103 is etched in its thickness, thereby increasing the height of the formed second pyramid structure 121. Thus, the height of the second pyramid structure 121 is greater than or equal to the height of the sixth pyramid structure 153.

[0142] In some embodiments, referring to Figures 6 and 8, the height of the second pyramid structure 121 is greater than or equal to the height of the sixth pyramid structure 153. Thus, the greater height of the second pyramid structure 121 facilitates the stacking of multiple first protrusions 131 on its sides and / or side edges, thereby forming a cluster of pyramids with a more uneven surface topography. This is more conducive to improving the light-trapping effect of the second substrate 101 and to forming better ohmic contact between the subsequent electrodes and the second substrate 101.

[0143] In some cases, referring to Figure 2, the base size of the first pyramid structure 120 can be from 1μm to 4.5μm, for example, it can be 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, 3.1μm, 3.2μm, 3.3μm, 3.4μm, or 3.5μm. The base dimensions of the sixth pyramid structure 153 can be 1μm to 4.5μm, for example, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, etc. Referring to Figures 2 and 6, the base dimensions of the sixth pyramid structure 153 can be 1μm to 4.5μm, for example, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, etc. The base dimensions of the second pyramid structure 121 can be 1μm to 5μm, for example, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.5μm, 1.6μm, 1.7μm, 2.8μm, 2.9μm, 3μm, 3.1μm, 3.2μm, 3.3μm, 3.4μm, 3.5μm, 3.6μm, 3.7μm, 3.8μm, 3.9μm, 4μm, 4.1μm, 4.2μm, 4.3μm, 4.4μm, or 4.5μm, etc.; referring to Figure 8, the base dimensions of the second pyramid structure 121 can be 1μm to 5μm, for example, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6 ... 7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, 3.1μm, 3.2μm, 3.3μm, 3 .4μm, 3.5μm, 3.6μm, 3.7μm, 3.8μm, 3.9μm, 4μm, 4.1μm, 4.2μm, 4.3μm, 4.4μm, 4.5μm, 4.6μm, 4.7μm, 4.8μm, 4.9μm or 5μm, etc.

[0144] In some cases, referring to Figure 2, along the first direction X, the height of the first pyramid structure 120 can be 0.5μm to 2μm, for example, it can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, or 2μm, etc.; referring to Figures 2 and 6, along the first direction X, the height of the sixth pyramid structure 153 can be 0.5μm to 2μm, for example, it can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1 ... μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm or 2μm, etc.; Referring to Figure 8, the height of the second pyramid structure 121 can be 0.5μm to 2.5μm, for example, it can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm or 2.5μm, etc.

[0145] In some cases, referring to Figure 2, the first substrate 100 may also have a first side surface 130 connecting the two first surfaces 110. The first side surface 130 includes a third pyramid structure 140, the base size of which is smaller than the base size of the first pyramid structure 120. It is worth noting that the first texturing process not only gives at least one first surface 110 of the first substrate 100 a pyramidal texturing structure, but also simultaneously gives the first side surface 130 of the first substrate 100 a similar pyramidal texturing structure. Thus, in the subsequent second texturing process, it is also beneficial to form a second substrate 101 that is more conducive to light trapping based on the third pyramid structure 140.

[0146] It should be noted that, as shown in Figure 2, the first base 100 has two first side surfaces 130 that both include the third pyramid structure 140. In actual applications, the first base has multiple first side surfaces surrounding the first surface, such as four first side surfaces. Depending on the requirements, only at least one first side surface of the first base may include the third pyramid structure. Other first side surfaces may also be formed as polished surfaces or other surface morphologies.

[0147] In some cases, referring to Figure 8, the second base 101 also has a second side surface 141 connecting the two second surfaces 111. The second side surface 141 includes a fourth pyramid structure 151 and a second protrusion structure 161. The second protrusion structure 161 is located on the side and / or side edge of the fourth pyramid structure 151, and along the direction away from the second side surface 141, the height of the second protrusion structure 161 is less than the height of the fourth pyramid structure 151; the base size of the fourth pyramid structure 151 is less than the base size of the second pyramid structure 121. It can be seen that the fourth pyramid structure 151 and the second protrusion structure 161 are formed on the basis of the fifth pyramid structure 133, that is, the initial second side surface 123 is transformed into the second side surface 141 after undergoing the second texturing process.

[0148] It should be noted that, as shown in Figure 8, the second base 101 has two second sides 141 that both include the fourth pyramid structure 151 and the second protrusion structure 161 as an example. In actual applications, the second base has multiple second sides surrounding the second surface, such as four second sides. Depending on the requirements, only at least one second side of the second base may include the fourth pyramid structure and the second protrusion structure. Other second sides may also be formed as polished surfaces or other surface morphologies.

[0149] It is worth noting that the initial second substrate 103, which is an intermediate product in the process of manufacturing photovoltaic cells, may have defects 143 not only on its initial second surface 113, but also on its initial second side surface 123. This results in at least a portion of the tops of the fifth pyramid structures 133 on the initial second substrate 103 having defects 143. The reasons for the formation of defects 143 will not be elaborated here, but will be described in detail in conjunction with the embodiments later.

[0150] Based on this, in order to improve the yield of the final photovoltaic cell and form a second substrate 101 with a special morphology that has a better light-trapping effect, a second texturing process is designed to be performed on the initial second substrate 103 to remove the defect portion 143 and form a second side surface 141 including a fourth pyramid structure 151 and a second protrusion structure 161. Thus, compared with the morphology of the initial second side surface 123 of the initial second substrate 103, the morphology of the second side surface 141 of the second substrate 101 includes not only the fourth pyramid structure 151 but also the second protrusion structure 161. The second protrusion structure 161 surrounds the fourth pyramid structure 151. Thus, the second protrusion structure 161 located on the side surface and / or side edge of the fourth pyramid structure 151 and the fourth pyramid structure 151 can be regarded as jointly forming a cluster of pyramids, which is conducive to forming more light-trapping areas to improve the light-trapping effect of the second side surface 141 of the second substrate 101.

[0151] Alternatively, the first side 130 undergoes stacking or repositioning after stacking, followed by a second texturing process, and is then transformed into the second side 141. In other words, the third pyramid structure 140 is formed after the first texturing process; the fourth pyramid structure 151 and the second protruding structure 161 are formed after the second texturing process, and the fourth pyramid structure 151 is formed based on a portion of the third pyramid structures 140. Compared to the morphology of the first side 130 of the first base 100, the morphology of the second side 141 of the second base 101 includes not only the fourth pyramid structure 151 but also the second protruding structure 161. The second protruding structure 161 surrounds the fourth pyramid structure 151. Thus, the second protruding structure 161 located on the side and / or side edge of the fourth pyramid structure 151 and the fourth pyramid structure 151 can be considered to jointly constitute a cluster of pyramids, which is beneficial for forming more light-trapping areas to improve the light-trapping effect of the second side 141 of the second base 101.

[0152] It should be noted that, referring to Figure 8, at least a portion of the second protruding structures 161 can be considered as incomplete pyramid structures. For example, the second protruding structure 161 can be considered as a sheet-like pyramid structure. Along the direction from the apex to the base, the portion of the second protruding structure 161 near the base is blocked by the side and / or side edge of the fourth pyramid structure 151 during its extension. This results in a smaller extension area on the side of the second protruding structure 161 that contacts the fourth pyramid structure 151, thus presenting a second protruding structure 161 with a apex but not a complete pyramid structure overall. Furthermore, in addition to contacting the fourth pyramid structure 151, a portion of the second protruding structures 161 may also contact another second protruding structure 161 on the other side. In other words, at least two second protruding structures 161 can be stacked on the surface of the same fourth pyramid structure 151, making the second protruding structures 161 more closely resemble sheet-like structures.

[0153] Based on this, the base size of the second protrusion structure 161 can be understood as the base size when the second protrusion structure 161 extends into a complete pyramid structure without being blocked by the fourth pyramid structure 151, and the base size of the second protrusion structure 161 can be smaller than the base size of the fourth pyramid structure 151.

[0154] In some cases, referring to Figure 6, the base size of the fifth pyramid structure 133 can be smaller than the base size of the sixth pyramid structure 153.

[0155] In some cases, referring to Figure 8, the base size of the fourth pyramid structure 151 can be smaller than the base size of the second pyramid structure 121.

[0156] In some cases, referring to Figure 6, the base size of the fifth pyramid structure 133 is 1μm to 3μm, for example, it can be 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, 2 The height of the fifth pyramid structure 133 in the direction perpendicular to the initial second side 123 is 0.2μm to 1.5μm, for example, it can be 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm or 1.5μm, etc.

[0157] The steps for providing the initial second substrate 103 are described in detail below through two embodiments.

[0158] In some embodiments, the step of providing an initial second substrate 103 may include: referring to FIG9, providing a substrate 102; referring to FIG2 and FIG9, performing a first texturing process on the substrate 102 to form a first substrate 100, the first substrate 100 having two first surfaces 110 opposite each other along a first direction X, at least one first surface 110 including a first pyramid structure 120; referring to FIG3 and FIG4 to FIG6, stacking or transferring the positions of a plurality of first substrates 100 after stacking, such that the first substrate 100 is transformed into an initial second substrate 103.

[0159] It is understandable that the first surface 110, formed after the first texturing process, transforms into the initial second surface 113 after being stacked or repositioned after stacking. The initial second surface 113 then transforms into the second surface 111 after undergoing the second texturing process. In other words, the first pyramid structure 120 is formed after the first texturing process, the sixth pyramid structure 153 is formed after being stacked or repositioned based on the first pyramid structure 120, and the second pyramid structure 121 and the first protrusion structure 131 are formed after the second texturing process. Furthermore, the second pyramid structure 121 is formed based on a portion of the sixth pyramid structures 153.

[0160] In other embodiments, referring to Figures 4 to 8, the initial second base 103 further has an initial second side 123 including a fifth pyramid structure 133, at least a portion of the fifth pyramid structures 133 having a defect 143 at the top, and in the step of performing the second texturing process, the defect 143 is removed, and the step of providing the initial second base 103 based on the fifth pyramid structure 133 to form the fourth pyramid structure 151 and the second protrusion structure 161 may further include the following steps:

[0161] Referring to FIG. 9, a substrate 102 is provided. Referring to FIGS. 2 and 9, the substrate 102 undergoes a first texturing process to form a first substrate 100. The first substrate 100 has two first surfaces 110 opposite each other along a first direction X, and a first side surface 130 connecting the two first surfaces 110. The first side surface 130 includes a third pyramid structure 140. Referring to FIG. 3, multiple first substrates 100 are stacked to transform the first substrate 100 into an initial second substrate 103. Thus, the first texturing process not only enables at least one first surface 110 of the first substrate 100 to have a first pyramid structure 120, but also simultaneously enables the first side surface 130 of the first substrate 100 to have a third pyramid structure 140. Therefore, in the subsequent second texturing process, it is also beneficial to form a second substrate 101 that is more conducive to light trapping based on the third pyramid structure 140.

[0162] In some examples, referring to Figures 2 to 6, in the step of stacking or transferring the positions of multiple first substrates 100, the first substrates 100 are transformed into an initial second substrate 103. The initial second substrate 103 has two initial second surfaces 113 opposite each other along a first direction X, and an initial second side surface 123 connecting the two initial second surfaces 113. The initial second side surface 123 includes a fifth pyramid structure 133, and at least a portion of the fifth pyramid structure 133 has a defect portion 143 at its top. Referring to Figures 4 to 8, in the step of performing a second texturing process, the defect portion 143 is removed.

[0163] It should be noted that Figure 4 is a scanning electron microscope (SEM) image of the initial second surface of the initial second substrate in a photovoltaic cell manufacturing method according to an embodiment of the present disclosure; Figure 5 is a scanning electron microscope (SEM) image of the initial second side surface of the initial second substrate in a photovoltaic cell manufacturing method according to an embodiment of the present disclosure; and Figure 6 is a cross-sectional structural diagram of the initial second substrate in a photovoltaic cell manufacturing method according to an embodiment of the present disclosure. Furthermore, Figure 6 uses the example where both initial second side surfaces 123 of the initial second substrate 103 include a fifth pyramid structure 133. In practical applications, the initial second substrate may have multiple, such as four, initial second side surfaces surrounding the initial second surface. Depending on the requirements, only at least one initial second side surface of the initial second substrate may include the fifth pyramid structure; other initial second side surfaces may also be formed as polished surfaces or other surface morphologies.

[0164] It is worth noting that after the first texturing process, a third pyramid structure 140 with an intact apex is formed on the first side surface 130. During the stacking or post-stack relocation steps, some of the taller third pyramid structures 140 may experience wear at their apex due to compression or contact friction, generating looser debris, thus transforming the third pyramid structure 140 into a fifth pyramid structure 133. Alternatively, during the stacking or post-stack relocation steps, fine impurities may be introduced, remaining on the initial second side surface 123 of the initial second substrate 103. Based on this, the defect portion 143 includes the aforementioned debris and / or impurities. In the subsequent second texturing process, the defect portion 143 is removed, thereby transforming the initial second side surface 123 into a second side surface 141. This helps to prevent the presence of the defect portion 143 from affecting the light trapping of the second side surface 141 or affecting the thickness uniformity of the film layer subsequently formed on the second side surface 141, thereby avoiding a decrease in the yield of the photovoltaic cell.

[0165] Furthermore, in the stacking or post-stack transfer step, since the tips of a portion of the third pyramid structure 140 are worn to form the fifth pyramid structure 133, in the subsequent second texturing process, in addition to removing the defective part 143, the top of the fifth pyramid structure 133 can be further modified so that the top of the final fourth pyramid structure 151 is an arc surface, thereby reducing the composite center of the second side 141 of the second base 101.

[0166] Understandably, the first side 130, formed after the first texturing process, transforms into the initial second side 123 after being stacked or repositioned after stacking. The initial second side 123 then transforms into the second side 141 after undergoing the second texturing process. In other words, the third pyramid structure 140 is formed after the first texturing process, the fifth pyramid structure 133 is formed after being stacked or repositioned based on the third pyramid structure 140, the fourth pyramid structure 151 and the second protruding structure 161 are formed after the second texturing process, and the fourth pyramid structure 151 is formed based on a portion of the fifth pyramid structures 133.

[0167] In some examples, referring to Figures 2 and 6, during the stacking or post-stack relocation steps, a portion of the apex of the third pyramid structure 140 is struck, resulting in debris around the apex of the third pyramid structure 140. The accumulation of this debris forms a defect 143. Based on this, the thickness of the defect 143 on the first side surface 130 can be 5 nm to 500 nm along the direction perpendicular to the first side surface 130, or conversely, the thickness of the defect 143 on the initial second side surface 123 can be 5 nm to 500 nm along the direction perpendicular to the initial second side surface 123.

[0168] It should be noted that the defect 143 on the first side 130 (or the initial second side 123) may be formed by the collision of the apex of the third pyramid structure 140. Based on this, the missing portion of the fifth pyramid structure 133 compared to the third pyramid structure 140 is the defect 143. Therefore, taking the horizontal plane where the apex of the third pyramid structure 140 is located as the reference plane, the distance between the top of a portion of the fifth pyramid structures 133 and the reference plane is similar to the thickness of the defect 143. In other words, the depth of influence or friction depth of the stacking or post-stacking placement steps on the top of the third pyramid structure 140 is 5 nm to 500 nm.

[0169] In one example, the thickness of the defect portion 143 located on the first side 130 along the direction perpendicular to the first side 130 (or the initial second side 123) can be 5nm, 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm or 500nm, etc.

[0170] In one example, during the stacking or subsequent position transfer step, relative compression or friction is applied to the top of the third pyramid structure 140 with a base size greater than or equal to 2 μm to form a defect 143, which then transforms into the fifth pyramid structure 133.

[0171] In some examples, referring to Figure 2, the base size of the third pyramid structure 140 can be 1μm to 3μm, for example, it can be 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, etc. The height of the third pyramid structure 140 in the direction perpendicular to the first side 130 can be 0.2μm to 1.5μm, for example, it can be 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm or 1.5μm, etc.

[0172] In some examples, referring to Figure 8, along the first direction X, the base size of the fourth pyramid structure 151 can be from 1μm to 4.5μm, for example, it can be 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, 3.1μm, 3.2μm, 3.3μm, 3.4μm, 3.5μm, 3.6μm, 3.7μm, 3 The height of the fourth pyramid structure 151 in the direction perpendicular to the second side 141 can be 0.5μm to 2.5μm, for example, it can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm or 2.5μm, etc.

[0173] In some cases, referring to Figures 2 and 6, during the step of stacking or transferring the positions of multiple first substrates 100, the first substrates 100 are transformed into an initial second substrate 103. The initial second substrate 103 has two initial second surfaces 113 opposite each other along a first direction X, where the first direction X is the thickness direction of the initial second substrate 103. At least one initial second surface 113 includes a sixth pyramid structure 153, and at least a portion of the sixth pyramid structures 153 has a defect 143 at its top. Referring to Figures 4 to 8, during the step of performing a second texturing process, the defect 143 is removed.

[0174] It is worth noting that the initial second substrate 103 can be considered an intermediate product in the manufacturing process of photovoltaic cells, and can be called a semi-finished substrate. Due to the numerous manufacturing steps involved in photovoltaic cells, there are many reasons why at least a portion of the sixth pyramid structures 153 on the initial second substrate 103 have defects 143 at their tops. For example, damage to the surface of the initial second substrate 103 resulting in debris is one cause of the defects 143. The accumulation of fine impurities on the surface of the initial second substrate 103 during the production process is also one cause of the defects 143. The defects 143 will be described in detail later with reference to embodiments. Therefore, if the defects 143 are not treated, their presence will adversely affect the quality of the film layer subsequently formed on the sixth pyramid structure 153, and will also adversely affect the ohmic contact between the subsequent electrodes and the initial second substrate 103, thereby affecting the yield of the photovoltaic cell.

[0175] Further, the initial second base 103 is subjected to a second texturing process to remove the defective portion 143, and a second pyramid structure 121 and a first protrusion structure 131 are formed on the basis of the sixth pyramid structure 153 to form the second base 101; wherein, the first protrusion structure 131 is located on the side and / or side edge of the second pyramid structure 121 and along the first direction X, and the height of the first protrusion structure 131 is less than the tower height of the second pyramid structure 121.

[0176] The second substrate 101 has two second surfaces 111 opposite each other along the first direction X. The second pyramid structure 121 and the first protrusion structure 131 are formed on the basis of the sixth pyramid structure 153, that is, the initial second surface 113 is transformed into the second surface 111 after undergoing a second texturing process. In addition, Figure 6 shows an example in which both second surfaces 111 of the second substrate 101 include the second pyramid structure 121 and the first protrusion structure 131. In practical applications, only one second surface can include the second pyramid structure and the first protrusion structure, and the other second surface can be formed as a polished surface or other surface morphology, depending on the requirements.

[0177] Based on this, in order to improve the yield of the final photovoltaic cell and form a second substrate 101 with a special morphology that has a better light trapping effect, a second texturing process is designed to be performed on the initial second substrate 103 to remove the defect portion 143 and form a second surface 111 including a second pyramid structure 121 and a first protrusion structure 131. Thus, compared to the morphology of the initial second surface 113 of the initial second substrate 103, the morphology of the second surface 111 of the second substrate 101 includes not only the second pyramid structure 121 but also the first protrusion structure 131. The first protrusion structure 131 surrounds the second pyramid structure 121. Thus, the first protrusion structure 131 located on the side and / or side edge of the second pyramid structure 121 and the second pyramid structure 121 can be regarded as jointly forming a clustered pyramid group, which is conducive to forming more light-trapping areas to improve the light-trapping effect of the second surface 111 of the second substrate 101. Moreover, the clustered pyramid group makes the second surface 111 of the second substrate 101 rougher, which is more conducive to the formation of better ohmic contact between the subsequent electrode and the second substrate 101, thereby improving the photoelectric conversion efficiency of the photovoltaic cell in terms of both light utilization and conductivity. In other words, compared to conventional textured surfaces, such as the sixth pyramid structure 153 in the initial second substrate 103, the height difference within the clustered pyramid group formed by the first protrusion structure 131 on the side and / or side edge of the second pyramid structure 121 and the second pyramid structure 121 is smaller, or the unevenness per unit area is lower. This is more conducive to the formation of subsequent passivation contact structures and electrode printing. Furthermore, the clustered pyramid group makes more effective use of the gaps between adjacent second pyramid structures 121, increasing the density and compactness of the textured surface, reducing the reflectivity of the second substrate 101, and is more conducive to the passivation and current enhancement of photovoltaic cells, thereby achieving the effect of improving the photoelectric performance of photovoltaic cells.

[0178] It should be noted that, as shown in Figure 6, both initial second surfaces 113 of the initial second substrate 103 include the sixth pyramid structure 153 as an example. In actual applications, only one initial second surface of the initial second substrate may include the sixth pyramid structure, depending on the requirements. Other initial second surfaces may also be formed as polished surfaces or other surface morphologies.

[0179] It is worth noting that after the first texturing process, a first pyramid structure 120 with an intact apex is formed on the first surface 110. During the stacking or post-stack transfer steps, some of the taller first pyramid structures 120 may experience wear at their apex due to compression or contact friction, resulting in looser debris. This can transform the first pyramid structure 120 into a sixth pyramid structure 153. Alternatively, during the stacking or post-stack transfer steps, fine impurities may be introduced, remaining on the pyramid textured structure of the first substrate 100 or the first surface 110. Based on this, the defect portion 143 includes the aforementioned debris and / or impurities. In the subsequent second texturing process, the defect portion 143 is removed, thereby transforming the initial second surface 113 into the second surface 111. This helps to prevent the presence of the defect portion 143 from affecting light trapping on the second surface 111, affecting the thickness uniformity of the film layer subsequently formed on the second surface 111, or affecting the ohmic contact between the subsequent electrode and the second surface 111, thereby preventing a decrease in the yield of the photovoltaic cell.

[0180] Furthermore, in the stacking or post-stack transfer step, since the tips of a portion of the first pyramid structures 120 are worn to form the sixth pyramid structure 153, in the subsequent second texturing process, in addition to removing the defective portion 143, the top of the sixth pyramid structure 153 can be further modified so that the top of the final formed second pyramid structure 121 is an arc surface, thereby reducing the composite center of the second surface 111 of the second base 101.

[0181] In some examples, referring to Figures 2 and 6, during the stacking or post-stack transfer steps, a portion of the tips of the first pyramid structures 120 are collided, resulting in debris around the tips of the first pyramid structures 120. The accumulation of this debris forms a defect portion 143. Based on this, the thickness of the defect portion 143 located on the initial second surface 113 along the first direction X can be 10 nm to 500 nm.

[0182] It should be noted that the defect 143 on the initial second surface 113 may be formed by the collision of the apex of the first pyramid structure 120. Based on this, the missing portion of the sixth pyramid structure 153 compared to the first pyramid structure 120 is the defect 143. Therefore, taking the horizontal plane where the apex of the first pyramid structure 120 is located as the reference plane, the distance between the top of a portion of the sixth pyramid structures 153 and the reference plane is similar to the thickness of the defect 143. In other words, the depth of influence or friction depth of the stacking or post-stacking placement step on the top of the first pyramid structure 120 is 10 nm to 500 nm.

[0183] In some examples, the thickness of the defect portion 143 located on the initial second surface 113 along the first direction X can be 10nm to 500nm, for example, it can be 10nm, 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm or 500nm, etc.

[0184] In some examples, during the stacking or subsequent position transfer steps, relative compression or friction occurs on the top of the first pyramid structure 120 with a base size greater than or equal to 3 μm to form a defect portion 143, which then transforms into a sixth pyramid structure 153.

[0185] The following details other steps that may be included in the manufacturing process of photovoltaic cells.

[0186] In some embodiments, the method for manufacturing a photovoltaic cell may further include performing a gettering process and a cleaning process before performing a first texturing process. In other words, the substrate 102 (refer to FIG. 9) is a semiconductor structure that has undergone a gettering process and a cleaning process.

[0187] In other embodiments, a gettering and impurity removal process is performed after the first texturing process and before the second texturing process. In other words, the first substrate 100 (refer to FIG. 2) is subjected to gettering and impurity removal, or the first substrate 100 or the initial second substrate 103 (refer to FIG. 6) after being stacked or repositioned after stacking is subjected to gettering and impurity removal, and then the second texturing process is performed to form the second substrate 101.

[0188] In both embodiments described above, the semiconductor structure requiring gettering is used as the gettering structure. The gettering process can include the following steps: doping the gettering structure to form a getter layer, for example, by diffusing dopant elements into the gettering structure using a high-temperature diffusion furnace. Thus, at high temperatures, the getter layer can generate an electric field or recombination centers of a certain strength, attracting and capturing impurities within the gettering structure, thereby improving the internal performance of the gettering structure. Furthermore, the impurity removal process can include the following steps: removing the getter layer using an acidic or alkaline etching solution.

[0189] In some cases, the material to be gettered can be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. The elemental semiconductor material can be monocrystalline, polycrystalline, amorphous, or microcrystalline (a state simultaneously possessing both monocrystalline and amorphous states is called microcrystalline). For example, silicon can be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. In other embodiments, the material to be gettered can also be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanide, silicon carbide, gallium arsenide, indium gallium dihydrogen phosphate, perovskite, cadmium telluride, and copper indium selenide.

[0190] In some cases, the doping element can be either a p-type or an n-type doping element. Specifically, the p-type doping element can be at least one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or gallium (In); the n-type doping element can be at least one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As).

[0191] In some embodiments, referring to FIG10 or FIG11, after performing the second texturing process, the method for manufacturing a photovoltaic cell may further include: forming a passivation contact structure 104 on at least one second surface 111 of the second substrate 101; and forming an electrode 105 on the side of the passivation contact structure 104 away from the second substrate 101.

[0192] A passivation contact structure 104 is formed on at least one second surface 111 of the second substrate 101; an electrode 105 is formed on the side of the passivation contact structure 104 away from the second substrate 101.

[0193] It should be noted that Figure 10 is a cross-sectional structural diagram of a photovoltaic cell in a photovoltaic cell manufacturing method according to an embodiment of the present disclosure; Figure 11 is a cross-sectional structural diagram of a photovoltaic cell in a photovoltaic cell manufacturing method according to an embodiment of the present disclosure. Furthermore, to clearly illustrate the positional relationship between the passivation contact structure 104, the electrode 105, and the second substrate 101, the textured surface morphology of any region of the second substrate 101 is not shown in Figures 10 and 11. Moreover, in practical applications, the surface with the passivation contact structure can be designed as the second surface 111 shown in Figure 8, or it can be designed as a polished surface or other surface morphology, while the other surface without the passivation contact structure is the second surface 111 shown in Figure 8.

[0194] In some cases, referring to Figure 10, photovoltaic cells are cells with electrodes on both sides, such as TOPCON cells (Tunnel Oxide Passivated Contact), PERC cells (Passivated emitter and real cell), and heterojunction cells (Heterojunction with Intrinsic Thin-film, abbreviated as HIT or HJT).

[0195] In some examples, the step of forming the passivated contact structure 104 includes forming a dielectric layer 114 on a second surface 111 of the second substrate 101 and forming a doped layer 124 on the side of the dielectric layer 114 away from the second substrate 101.

[0196] In one example, the photovoltaic cell is an HJT cell, the material of the dielectric layer 114 may include one or more of amorphous silicon, microcrystalline silicon or nanocrystalline silicon, the material of the doped layer 124 may include a single crystal, polycrystalline, amorphous or microcrystalline silicon material layer, and the doped layer 124 has a P-type dopant element or an N-type dopant element.

[0197] In another example, the photovoltaic cell is a TOPCON cell, the material of the dielectric layer 114 may include one or more of silicon oxide, silicon carbide, silicon nitride or silicon oxynitride, and the material of the doped layer 124 may include a single crystal, polycrystalline, amorphous or microcrystalline silicon material layer, and the doped layer 124 has a P-type dopant element or an N-type dopant element.

[0198] In both of the above examples, the step of forming electrode 105 includes: forming a first electrode 115 on the side of the doped layer 124 away from the dielectric layer 114, and forming a second electrode 125 on another second surface 111 of the second substrate 101. Furthermore, before forming the first electrode 115, a transparent conductive film may also be formed on the side of the doped layer 124 away from the dielectric layer 114.

[0199] In other cases, referring to Figure 11, the photovoltaic cell is a cell with an electrode on one side only, such as a BC cell (Back Contact). BC cells include, but are not limited to, IBC cells (Interdigitated Back Contact), HBC cells (Heterojunction Back Contact), TBC cells (TOPCon Back Contact), or HTBC cells (Hybrid Passivated Back Contact). HTBC cells are hybrid back contact solar cells combining heterojunction and tunnel oxide passivated contacts (abbreviated as HTBC).

[0200] In some examples, a second surface 111 of the second substrate 101 includes a first region 1111 and a second region 1112 arranged alternately along a second direction Y. The step of forming the passivation contact structure 104 includes: forming a first passivation contact structure 1041 at least on the first region 1111, the first passivation contact structure 1041 including a first dielectric layer 1141 and a first doped layer 1241 located on the side of the first dielectric layer 1141 away from the second substrate 101; and forming a second passivation contact structure 1042 at least on the second region 1112, the second passivation contact structure 1042 including a second dielectric layer 1142 and a second doped layer 1242 located on the side of the second dielectric layer 1142 away from the second substrate 101.

[0201] Furthermore, the step of forming electrode 105 includes: forming a first electrode 115 on the side of the first doped layer 1241 away from the second substrate 101; and forming a second electrode 125 on the side of the second doped layer 1242 away from the second substrate 101.

[0202] In one example, the material of at least one of the first dielectric layer 1141 and the second dielectric layer 1142 may include one or more of silicon oxide, silicon carbide, silicon nitride, and silicon oxynitride; in another example, the material of at least one of the first dielectric layer 1141 and the second dielectric layer 1142 may include one or more of amorphous silicon, microcrystalline silicon, and nanocrystalline silicon.

[0203] In summary, by interleaving the stacking or post-stack transfer steps between the first and second texturing processes, on the one hand, even if impurities or debris are generated on the surface of the first substrate 100 during the stacking or post-stack transfer steps, the second texturing process can remove these impurities or debris and refine the details of the pyramid textured surface, ensuring that the final second substrate 101 also has a good textured surface morphology. On the other hand, the stacking or post-stack transfer steps can remove the apex of the pyramid textured surface of the first substrate 100, and further assist the second texturing process to achieve rounding of the pyramid textured surface. This eliminates the need for a separate rounding process, achieving both cleaning and apex rounding of the pyramid textured surface, thereby improving the thickness uniformity of the film layer subsequently formed on the second substrate 101 and enhancing the ohmic contact between the subsequent electrodes and the second substrate 101. This approach simplifies the photovoltaic cell manufacturing process while improving the photoelectric conversion efficiency of the photovoltaic cell.

[0204] Another embodiment of this disclosure provides a photovoltaic cell, formed by the manufacturing method of the photovoltaic cell provided in the foregoing embodiments. The photovoltaic cell provided in another embodiment of this disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that parts that are the same as or corresponding to those in the foregoing embodiments will not be repeated here.

[0205] Referring to Figures 8, 10, and 11, the photovoltaic cell is formed by the photovoltaic cell manufacturing method provided in the foregoing embodiments.

[0206] Another embodiment of this disclosure provides a photovoltaic module, which will be described in detail below with reference to the accompanying drawings. It should be noted that parts that are the same as or corresponding to those in the foregoing embodiments will not be repeated here.

[0207] Referring to Figures 8, 10 to 13, the photovoltaic module includes: a battery string, which is formed by connecting multiple photovoltaic cells 40 provided in the foregoing embodiments, or by connecting photovoltaic cells 40 formed by the manufacturing method of multiple photovoltaic cells provided in the foregoing embodiments; an encapsulating film 41 for covering the surface of the battery string; and a cover plate 42 for covering the surface of the encapsulating film 41 facing away from the battery string.

[0208] It should be noted that Figure 12 is a partial three-dimensional schematic diagram of a cell string in a photovoltaic module provided in another embodiment of the present disclosure; Figure 13 is a partial cross-sectional schematic diagram of a photovoltaic module provided in another embodiment of the present disclosure. Furthermore, Figures 12 and 13 only use BC cells as an example for the photovoltaic cell 40.

[0209] In some embodiments, the photovoltaic cell 40 includes, but is not limited to, one or any combination of PERC cells, BC cells, TOPCON cells, HIT / HJT cells, thin-film solar cells, and tandem cells. Among them, BC cells include, but are not limited to, IBC cells, HBC cells, TBC cells, or HTBC cells.

[0210] It should be noted that multiple photovoltaic cells 40 can be electrically connected via solder strips 43. Figures 12 and 13 illustrate a BC cell configuration for the photovoltaic cells 40, and only show one possible positional relationship between the photovoltaic cells 40, where the electrode side of each photovoltaic cell 40 faces the same side, and the conductive strips 43 connect the same side of two adjacent photovoltaic cells 40 respectively. In other embodiments, the photovoltaic cells can also be arranged such that the electrodes of two adjacent photovoltaic cells are located on different sides, in which case the conductive strips connect the different sides of the two adjacent photovoltaic cells.

[0211] In some embodiments, the photovoltaic cells 40 are electrically connected in the form of a single cell or multiple segments to form multiple cell strings, and the multiple cell strings are electrically connected in series and / or parallel. The photovoltaic cells 40 can be a single cell or a sliced ​​cell, where a sliced ​​cell refers to a cell formed by cutting a complete single cell.

[0212] In some embodiments, the encapsulating film 41 includes a first encapsulating layer and a second encapsulating layer. The first encapsulating layer covers one of the front or back sides of the photovoltaic cell 40, and the second encapsulating layer covers the other of the front or back sides of the photovoltaic cell 40. Specifically, at least one of the first and second encapsulating layers can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene coelastomer (POE) film, or polyethylene terephthalate (PET) film. Alternatively, at least one of the first and second encapsulating layers can also be an EP film, an EPE film, or a PVP film. Here, EP film refers to a co-extruded film composed of stacked EVA film and POE film; EPE film refers to a co-extruded film formed by sequentially stacking EVA film + POE film + EVA film; and PVP film refers to a co-extruded film formed by stacking POE film + EVA film + POE film. Co-extruded films can be prepared by sequentially extruding one or more raw materials onto another pre-made film during the film processing, or by bonding different types of pre-made films together.

[0213] In some cases, the first encapsulation layer and the second encapsulation layer still have a boundary line before lamination. After lamination, the photovoltaic module will no longer have the concept of a first encapsulation layer and a second encapsulation layer. That is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 41.

[0214] In some embodiments, the cover plate 42 can be a glass cover plate, a plastic cover plate, or other cover plate with light-transmitting function. Specifically, the surface of the cover plate 42 facing the encapsulating film 41 can be an uneven surface or a textured surface containing multiple raised structures, thereby increasing the utilization rate of incident light. The cover plate 42 includes a first cover plate and a second cover plate, the first cover plate being opposite to the first encapsulation layer, and the second cover plate being opposite to the second encapsulation layer.

[0215] In another aspect, this disclosure provides a texturing method for a silicon substrate, the flowchart of which is shown in Figure 14, and includes the following steps:

[0216] S10: Provides a silicon substrate;

[0217] S20: Forms the velvety surface structure of the main pyramid;

[0218] S30: Cleaning, performed using a cleaning solution containing a texturing additive; and

[0219] S40: A velvety pyramidal surface structure is formed on the facets and / or corners of the main pyramid.

[0220] S50: Post-processing to obtain a silicon substrate with a clustered pyramidal textured surface.

[0221] This disclosure describes a process where a silicon substrate is texturized in one step to form a main pyramid. The main pyramid is then cleaned and protected using a cleaning solution containing texturing additives. A second texturing process is then performed, during which the pyramid continues to grow on the edges or corners of the main pyramid, resulting in a clustered pyramid textured surface structure with a rectangular or irregular quadrilateral base. Compared to conventional textured surfaces, the clustered pyramid textured surface has a smaller height difference, which is more conducive to film contact and electrode printing. Furthermore, the clustered pyramids more effectively utilize the gaps between the pyramids, increasing the density and compactness of the textured surface, reducing the reflectivity of the silicon substrate, and further facilitating cell passivation and current enhancement, thereby improving the photoelectric performance of the battery.

[0222] As shown in Figure 22, the attached pyramid 2 (similar to the first protrusion structure 131 in Figure 8) of this disclosure is attached to the main pyramid 1 (similar to the second pyramid structure 121 in Figure 8). It grows on the edges and / or corners of part of the periphery of the main pyramid 1. After part of the attached pyramid 2 grows on the periphery of the main pyramid 1, the attached pyramid that continues to grow can also be attached to the periphery of the attached pyramid that has already grown. As can be seen from Figure 23, the height difference between the attached pyramid 2 and the main pyramid 1 of this disclosure is small.

[0223] Furthermore, the base of the main pyramid 1 described in this disclosure is a regular square, while the base of the attached pyramid 2 is incomplete compared to the square base of the main pyramid. Therefore, the attached pyramid 2 is incomplete compared to the main pyramid 1, and its base is rectangular or an irregular quadrilateral. That is, the sides of the attached pyramid 2 described in this disclosure are attached to or adhered to at least one edge of the main pyramid 1, forming a dependent relationship, and it does not exist independently. As shown in Figures 24 and 25, the pyramid texture structure obtained by conventional secondary texture processing shows that the small pyramid 4 of secondary texture processing grows independently between the gaps of the large pyramid 3 of primary texture processing, exists independently, and has a small base size, which is different from the attached pyramid of this disclosure.

[0224] The principle behind this disclosure for obtaining clustered pyramidal surfaces by cleaning with a cleaning solution containing texturing additives after a primary texturing process is as follows: After a primary texturing process, a main pyramidal textured surface is formed on the silicon substrate. Subsequently, the substrate is cleaned with a cleaning solution containing texturing additives. The texturing additives (such as high-molecular-weight ethers) have a strong adsorption capacity on the textured silicon substrate surface, enhancing its hydrophobicity and reducing contact between the substrate surface and reactants in the solution. This protects the already formed pyramidal textured surface during the secondary texturing process. Simultaneously, new pyramids continue to etch around the already formed main pyramid. Since these new pyramids are newly etched interfaces, they have less adsorption of protective substances and will quickly etch out new interfaces. In summary, due to the protection of the original main pyramid surface by the additives, combined with the newly etched interfaces near the main pyramid, a clustered pyramidal textured surface is achieved overall.

[0225] After the post-processing described in this disclosure, the apex of the pyramid is corroded; specifically, the rounding step in the post-processing will corrode the apex of the pyramid. If the rounding process is not performed, the passivation effect will be weakened, so the rounding process is performed.

[0226] In one specific embodiment, the surface tension of the flocking additive is 45mN / m-65mN / m, for example, it can be 45mN / m, 50mN / m, 55mN / m, 60mN / m or 65mN / m, and it is a hydrophobic flocking additive.

[0227] The texturing additives used in this disclosure include any one or a combination of at least two of the following: Xiaochen H13C hydrophobic additive, H16 hydrophilic additive, or Shichuang HJ21v02 hydrophobic additive. The texturing additive used for cleaning is preferably a texturing additive with a surface tension within a specific range. As a hydrophobic texturing additive, its components contain polymeric components that can be adsorbed on the surface of the first-step texturing to form a protective layer.

[0228] In one specific embodiment, the mass concentration ratio of the alkali solution in the texturing solution that forms the attached pyramidal textured surface is W1, and the mass concentration ratio of the alkali solution in the texturing solution that forms the main pyramidal textured surface is W2. <W2。

[0229] This disclosure preferably uses a lower proportion of alkali concentration in the secondary texturing solution than in the primary texturing solution, which can protect the main pyramid while facilitating the formation of the attached pyramid.

[0230] In one specific embodiment, the cleaning includes the following steps: first cleaning with a cleaning solution containing a texturing additive, and then cleaning with a cleaning solution containing an oxidant; or, first cleaning with a cleaning solution containing an oxidant, and then cleaning with a cleaning solution containing a texturing additive.

[0231] This disclosure allows for the use of a cleaning solution containing an oxidizing agent before or after cleaning with a cleaning solution containing a texturing additive, which can increase the size of the clustered pyramids, thereby increasing the coverage of the clustered pyramids and reducing the gaps between the pyramids.

[0232] Furthermore, this disclosure prioritizes the use of a cleaning solution containing an oxidant for the first cleaning, followed by a cleaning solution containing a texturing additive for the second cleaning. The first cleaning with the oxidant results in a higher surface cleanliness, and the second cleaning with the cleaning solution containing the texturing additive provides stronger protection for the already formed texturized surface. The second texturing process can fully utilize the gaps between the texturized surfaces to grow clustered pyramids, thereby reducing reflectivity and improving battery efficiency.

[0233] In one specific embodiment, the cleaning temperature is 55℃-70℃, for example, it can be 55℃, 60℃, 65℃ or 70℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0234] The cleaning temperature described in this disclosure will have a certain impact on the clustered pyramid structure. If the cleaning temperature is too low, the surface cleaning may not be thorough, and the residual reaction solution will continue to corrode the silicon substrate surface, weakening the protection of the silicon substrate textured surface by the cleaning solution. If the temperature of the secondary cleaning is too high, it may oxidize the silicon substrate surface, making the additive adsorption capacity insufficient, weakening the protective effect of the additive, and increasing the reflectivity of the silicon substrate.

[0235] In one specific embodiment, the cleaning time is 100s-150s, for example, it can be 100s, 110s, 120s, 130s, 140s or 150s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0236] In one specific embodiment, the steps of cleaning and forming the attached pyramid velvet structure are repeated more than once, for example, once, twice, three times or four times, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0237] This disclosure allows for multiple texturing processes after a secondary texturing process has resulted in an attached pyramidal texturing structure.

[0238] In one specific embodiment, the flocking method includes the following steps:

[0239] Provides silicon substrate.

[0240] The silicon substrate is texturized in one step to form the main pyramid textured surface structure.

[0241] The cleaning process involves using a cleaning solution containing a texturing additive.

[0242] Secondary pile processing creates an attached pyramid pile structure on the facets and / or corners of the main pyramid.

[0243] The cleaning process involves using a cleaning solution containing a texturing additive.

[0244] The process involves three rounds of fabrication, during which the dependent pyramids continue to grow on the faces and / or corners of the main pyramid and the dependent pyramids.

[0245] Post-processing yields a silicon substrate with a clustered pyramidal textured surface.

[0246] This disclosure allows for multiple texturing steps, such as the texturing method described above. After secondary texturing, washing and texturing can be performed again to continue growing the pyramids, thereby effectively utilizing the gaps between the main pyramids and reducing reflectivity.

[0247] In one specific embodiment, the primary texturing solution for forming the main pyramidal texturing structure includes texturing additives, alkali, and water.

[0248] In one specific embodiment, the cleaning solution used for cleaning includes a texturing additive and water, wherein the content of the texturing additive is 0.1wt%-1wt%, for example, it can be 0.1wt%, 0.3wt%, 0.5wt%, 0.7wt%, 0.9wt% or 1wt%, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0249] In one specific embodiment, the secondary texturing solution for forming the attached pyramidal texturing structure includes texturing additives, alkali, and water.

[0250] In one specific embodiment, the silicon substrate is pre-cleaned, coarsely polished, and then cleaned once before forming the main pyramid textured structure.

[0251] In one specific embodiment, the pre-cleaning cleaning solution includes an oxidant, an alkali, and water.

[0252] The silicon substrate described in this disclosure has been pre-cleaned, for example, by using hydrogen peroxide and sodium hydroxide solution to remove surface oil.

[0253] In one specific embodiment, the cleaning solution used in the first cleaning includes an oxidant and water.

[0254] The rough polishing described in this disclosure removes the oxide layer and mechanical damage layer from the silicon substrate. After rough polishing, the silicon substrate is cleaned once to obtain a clean surface.

[0255] The oxidant used in this disclosure is hydrogen peroxide, and the alkali used includes sodium hydroxide.

[0256] In one specific embodiment, the post-processing includes pure water washing, rounding, acid washing, slow lifting and drying steps.

[0257] The rounding process described in this disclosure can etch the apex of the pyramid in the clustered pyramid textured structure. If the rounding process is not performed, the passivation effect of the silicon substrate will be weakened. Therefore, the rounding process needs to be performed in the post-processing stage.

[0258] In one specific embodiment, the sphericification liquid used for sphericification includes ozone, HF, and water.

[0259] In one specific embodiment, the rounding process involves washing with pure water followed by acid washing.

[0260] Secondly, this disclosure provides a method for preparing a solar cell, the method comprising the following steps:

[0261] Provides silicon substrate.

[0262] This forms the velvety surface structure of the main pyramid.

[0263] The cleaning process involves using a cleaning solution containing a texturing additive.

[0264] A textured pyramidal surface is formed on the facets and / or corners of the main pyramid.

[0265] Post-processing yields a silicon substrate with a clustered pyramidal textured surface.

[0266] Prepare amorphous or microcrystalline films.

[0267] Prepare conductive film.

[0268] Electrodes are prepared to obtain the solar cell.

[0269] In one specific embodiment, amorphous / microcrystalline silicon films are deposited on the front and back sides of a silicon substrate that has undergone texturing.

[0270] Subsequently, a PN junction is formed on one side, and a high-low junction is formed on the other side.

[0271] PVD coating: A conductive film is deposited on both sides of the coated silicon substrate.

[0272] Screen printing: The grid electrodes are prepared by screen printing and curing to obtain the solar cell.

[0273] Thirdly, this disclosure provides a solar cell comprising a silicon substrate having a clustered pyramidal textured surface structure, the clustered pyramidal textured surface structure comprising a main pyramid and attached pyramids, the attached pyramids being located on the facets and / or corners of the main pyramid.

[0274] In one specific embodiment, the apex of the dependent pyramid is lower than the apex of the main pyramid.

[0275] The main pyramid of this invention has a high apex, and the attached pyramids are formed by attaching to the gaps between the main pyramids. Therefore, the main pyramid has a higher reflectivity.

[0276] In one specific embodiment, the proportion of the main pyramid within the unit area of ​​the silicon substrate is ≥50%, for example, it can be 50%, 55%, 60%, 65%, 70%, 75% or 80%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0277] Due to the high reflectivity of the main pyramid, in order to reduce reflectivity, it is preferable that the main pyramid accounts for ≥50% of the area per unit area of ​​the silicon substrate (either in number or in base area).

[0278] In one specific embodiment, the main pyramid grows from the surface of the silicon substrate in a direction away from the silicon substrate, and the attached pyramid grows along the facets and / or ridges of the main pyramid.

[0279] The pyramids disclosed herein are attached to the main pyramid and grow along the direction of the facets and / or ridges of the main pyramid, and do not exist independently, while pyramids prepared by conventional methods exist independently.

[0280] In one specific embodiment, the height of the main pyramid is 1.3-1.6 μm, for example, it can be 1.3 μm, 1.4 μm, 1.5 μm or 1.6 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0281] The technical solutions of this disclosure will be further illustrated below through specific embodiments.

[0282] Example 1

[0283] This embodiment provides a texturing method for a silicon substrate, the texturing method comprising the following steps:

[0284] (1) Take a single crystal silicon substrate that has been cleaned, impurity removed and PSG removed as a texturing silicon substrate for later use.

[0285] (2) Pre-cleaning: Immerse the monocrystalline silicon substrate in a pre-cleaning mixed solution at 65°C for 240 seconds.

[0286] The initial cleaning solution consists of 280L of pure water, 4L of 45wt% sodium hydroxide solution, and 20L of 45wt% hydrogen peroxide solution; the replenishment solution for each batch consists of 5L of pure water, 100mL of 45wt% sodium hydroxide solution, and 1L of 45wt% hydrogen peroxide solution.

[0287] (3) Water washing: Immerse the monocrystalline silicon substrate from step (2) in pure water for 120 seconds.

[0288] (4) Rough polishing: Immerse the single crystal silicon substrate from step (3) in an alkaline solution at 80°C for 60 seconds for alkaline polishing.

[0289] The initial solution for coarse polishing is: 280L of pure water and 30L of 45wt% sodium hydroxide solution; the replenishment solution for each batch is 8L of pure water and 500mL of 45wt% sodium hydroxide solution.

[0290] (5) First cleaning: Immerse the single crystal silicon substrate from step (4) in a cleaning solution at 65°C for 400 seconds.

[0291] The cleaning solution was a 5wt% solution of hydrogen peroxide and pure water. After cleaning, the monocrystalline silicon substrate was immersed in pure water for 120 seconds.

[0292] (6) First texturing: The monocrystalline silicon substrate is immersed in the first texturing solution at 80°C for 350 seconds.

[0293] The first texturing solution formula is as follows: the initial solution is prepared by 280L of pure water, 3L of 45wt% sodium hydroxide and 1L of H13C texturing additive; each batch of replenishment solution consists of 10L of pure water, 350mL of 45wt% sodium hydroxide solution and 280mL of H13C texturing additive.

[0294] (7) Second cleaning: At 60°C, the texturized silicon substrate from step (6) is immersed in H13C texturizing additive for 120 seconds.

[0295] The secondary cleaning solution is formulated with 2L of H13C texturing additive and 280L of pure water. Each batch of replenishment solution consists of 1L of pure water and 100mL of H13C texturing additive.

[0296] (8) Second texturing: Immerse the monocrystalline silicon substrate from step (7) in a second texturing solution at 80°C for 350 seconds.

[0297] The second texturing solution formula is the same as the first texturing solution formula in step (6). After texturing is completed, it is immersed in pure water for 120 seconds.

[0298] (9) Rounding: Immerse the textured monocrystalline silicon substrate from step (8) in rounding cleaning solution for 350s.

[0299] The formulation of the round cleaning solution is: 45ppm ozone and 2% HF solution; the replenishment solution for each batch is 30mL HF solution and 4L pure water.

[0300] After rounding, the silicon substrate is immersed in pure water for 120 seconds.

[0301] (10) Pickling: Immerse the single crystal silicon substrate from step (9) in a 5 wt% hydrofluoric acid solution for 300 s and then immerse the silicon substrate in pure water for 120 s.

[0302] (11) Slow lifting and drying: The single crystal silicon substrate from step (10) is washed in pure water and slowly lifted at a speed of 3 mm / s. After lifting, it is dried in clean air at 80°C for 15 min to obtain the silicon substrate. The silicon substrate has a clustered pyramid textured surface structure. The clustered pyramid textured surface structure includes a main pyramid and a dependent pyramid. The dependent pyramid is located on the facets and corners of the main pyramid. The apex of the dependent pyramid is lower than the apex of the main pyramid. The main pyramid accounts for 55% of the clustered pyramid textured surface structure. The height of the main pyramid is 1.5 μm.

[0303] The top-view SEM image of the silicon substrate obtained in this embodiment is shown in Figure 14 (the dimensions of the pyramid base are marked in Figure 14). The side-view SEM image is shown in Figure 15. The schematic diagram of the clustered pyramid structure on the surface of the silicon substrate is shown in Figure 22, and the schematic diagram of the cross-sectional structure is shown in Figure 23.

[0304] Example 2

[0305] This embodiment provides a texturing method for a silicon substrate. Except for step (7), the texturing method is the same as that in Embodiment 1. Step (7) is as follows:

[0306] (7) Secondary cleaning: At 60°C, the texturized silicon substrate from step (6) is immersed in H13C texturizing additive solution for 120s. The secondary cleaning solution is formulated with 2L H13C texturizing additive and 280L pure water. Each batch of replenishment solution consists of 1L pure water and 100mL H13C texturizing additive.

[0307] After cleaning with the texturing additive solution, the sample was immersed in hydrogen peroxide at 60°C for 120 seconds. The cleaning solution formula was the same as that used in the first cleaning.

[0308] In this embodiment, the texturized silicon substrate has a clustered pyramid textured surface structure, which includes a main pyramid and attached pyramids. The attached pyramids are located on the facets and corners of the main pyramid, and the apex of the attached pyramid is lower than the apex of the main pyramid. The main pyramid accounts for 50% of the clustered pyramid textured surface structure, and the height of the main pyramid is 1.5 μm.

[0309] Example 3

[0310] This embodiment provides a texturing method for a silicon substrate. Except for step (7), the texturing method is the same as that in Embodiment 1. Step (7) is as follows:

[0311] (7) Second cleaning: At 60°C, the texturized silicon substrate from step (6) is immersed in hydrogen peroxide for 120 seconds. The cleaning solution formula is the same as that of the first cleaning solution.

[0312] After cleaning with hydrogen peroxide, the sample is immersed in an H13C texturing additive solution at 60°C for 120 seconds. The cleaning solution consists of 2L of H13C texturing additive and 280L of pure water. Each batch is replenished with 1L of pure water and 100mL of H13C texturing additive.

[0313] In this embodiment, the texturized silicon substrate has a clustered pyramid textured surface structure, which includes a main pyramid and attached pyramids. The attached pyramids are located on the facets and corners of the main pyramid, and the apex of the attached pyramid is lower than the apex of the main pyramid. The main pyramid accounts for 60% of the clustered pyramid textured surface structure, and the height of the main pyramid is 1.5 μm.

[0314] Example 4

[0315] This embodiment provides a texturing method for a silicon substrate. Except for step (7) of secondary cleaning in H16 hydrophilic texturing additive solution, the texturing method is the same as in Example 1.

[0316] Example 5

[0317] This embodiment provides a texturing method for a silicon substrate. In addition to the second texturing step (8), the texturing method also performs three cleaning steps and three texturing steps in sequence. The third cleaning step is the same as the second cleaning step, and the third texturing step is the same as the second texturing step. The rest are the same as in Embodiment 1.

[0318] Example 6

[0319] This embodiment provides a texturing method for a silicon substrate. Except for the temperature of the secondary cleaning in step (7) being 55°C, the texturing method is the same as in embodiment 1.

[0320] Example 7

[0321] This embodiment provides a texturing method for a silicon substrate. Except for the temperature of the secondary cleaning in step (7) being 70°C, the texturing method is the same as that in Embodiment 1.

[0322] Example 8

[0323] This embodiment provides a texturing method for a silicon substrate. Except for the temperature of the secondary cleaning in step (7) being 40°C, the texturing method is the same as in embodiment 1.

[0324] Example 9

[0325] This embodiment provides a texturing method for a silicon substrate. Except for the temperature of the secondary cleaning in step (7) being 80°C, the texturing method is the same as in embodiment 1.

[0326] Comparative Example 1

[0327] This comparative example provides a texturing method for a silicon substrate, which is the same as that in Example 1 except for step (7) of secondary washing in pure water.

[0328] The top-view SEM image of the silicon substrate obtained in this comparative example is shown in Figure 16 (the tower base dimensions are marked in Figure 16), and the side-view SEM image is shown in Figure 17.

[0329] Comparative Example 2

[0330] This comparative example provides a texturing method for a silicon substrate. Except for step (7), in which a second cleaning with hydrogen peroxide is performed, and the cleaning solution formulation is the same as that used in the first cleaning, the texturing method is the same as that in Example 1.

[0331] The top-view SEM image of the silicon substrate obtained in this embodiment is shown in Figure 18 (the tower base dimensions are marked in Figure 18), and the side-view SEM image is shown in Figure 19.

[0332] Comparative Example 3

[0333] This comparative example provides a texturing method for a silicon substrate, the texturing method comprising the following steps:

[0334] (1) Take a single crystal silicon substrate that has been cleaned, impurity removed and PSG removed as a texturing silicon substrate for later use.

[0335] (2) Pre-cleaning: Immerse the monocrystalline silicon substrate in a pre-cleaning mixed solution at 65°C for 240 seconds.

[0336] The initial cleaning solution consists of 280L of pure water, 4L of 45wt% sodium hydroxide solution, and 20L of 45wt% hydrogen peroxide solution; the replenishment solution for each batch consists of 5L of pure water, 100mL of 45wt% sodium hydroxide solution, and 1L of 45wt% hydrogen peroxide solution.

[0337] (3) Water washing: Immerse the monocrystalline silicon substrate from step (2) in pure water for 120 seconds.

[0338] (4) Rough polishing: Immerse the single crystal silicon substrate from step (3) in an alkaline solution at 80°C for 60 seconds for alkaline polishing.

[0339] The initial solution for coarse polishing is: 280L of pure water and 30L of 45wt% sodium hydroxide solution; the replenishment solution for each batch is 8L of pure water and 500mL of 45wt% sodium hydroxide solution.

[0340] (5) Cleaning: Immerse the monocrystalline silicon substrate in a cleaning solution at 65°C for 400 seconds.

[0341] The cleaning solution was a 5wt% solution of hydrogen peroxide and pure water. After cleaning, the monocrystalline silicon substrate was immersed in pure water for 120 seconds.

[0342] (6) Texturing: Immerse the monocrystalline silicon substrate from step (5) in the first texturing solution at 80°C for 700s, and after texturing, rinse with pure water for 120s.

[0343] The first texturing solution formula is: initially prepared with 280L of pure water, 3L of 45wt% sodium hydroxide and 1L of H13C texturing additive; each batch of replenishment solution consists of 10L of pure water, 350mL of 45wt% sodium hydroxide solution and 280mL of texturing additive.

[0344] The top-view SEM image of the silicon substrate obtained in this comparative example is shown in Figure 20 (the dimensions of the pyramid base are marked in Figure 20), the side-view SEM image is shown in Figure 21, the schematic diagram of the pyramid structure on the surface of the silicon substrate is shown in Figure 24, and the schematic diagram of the cross-sectional structure is shown in Figure 25.

[0345] After each batch of monocrystalline silicon substrates in the above embodiments and comparative examples is completed, liquid replenishment is performed accordingly, and then texturing of the next batch of silicon substrates is carried out to complete the silicon substrate texturing.

[0346] The silicon substrates obtained in the above embodiments and comparative examples were used to fabricate cells. The cell fabrication process included the following steps:

[0347] Microcrystalline silicon layers were deposited on the front and back sides of the silicon substrates obtained in the above embodiments and comparative examples, and then a PN junction was formed on one side and a high-low junction was formed on the other side.

[0348] PVD coating: A conductive film is deposited on both sides of the coated silicon substrate.

[0349] Screen printing: The grid electrodes are fabricated through screen printing and curing to obtain the solar cell. The performance of the solar cell is then tested, and the test results are shown in Table 1.

[0350] Table 1

[0351] As can be seen from Figures 14-25 and Table 1:

[0352] (1) As shown in Figures 14-21, this disclosure uses a texturing additive solution for cleaning after the first texturing process and before the second texturing process, which can obtain a high proportion of clustered pyramidal texturing surface. Figure 14 shows that the base size of the main pyramid obtained in Example 1 is approximately 2.8 μm. Figure 16 shows that the base size of the texturing main pyramid obtained in Comparative Example 1 is approximately 2.5 μm. Figure 18 shows that the base size of the texturing main pyramid obtained in Comparative Example 2 is approximately 4 μm. Figure 20 shows that the texturing main pyramid obtained in Comparative Example 3... The base size is approximately 3.2 μm, and the proportion of clustered pyramidal textured surface obtained in Example 1 is higher, with a smaller height difference between the clustered textured surfaces. As shown in Figures 22-25, compared with the ordinary textured surface in Figures 24-25, the clustered pyramidal textured surface in Figures 22-23 of this disclosure is attached to the periphery or corners of the main pyramid, and the height difference between the attached pyramid and the main pyramid is smaller. The clustered pyramidal textured surface makes full use of the gaps between the pyramids to grow more attached pyramids, effectively enhancing the light absorption effect of the textured surface.

[0353] (2) As can be seen from Example 1 and Comparative Examples 1-3, the battery performance of Example 1 is better, with lower reflectivity, higher short-circuit current Isc and fill factor FF, indicating that the clustered pyramids are beneficial to the absorption of light waves by the battery cells and the passivation contact of the film layer. The higher reflectivity of Comparative Example 2 compared to Comparative Example 3 indicates that after surface oxidation and hydrophilic texturing, the textured surface is enlarged but the reflectivity is somewhat lost, although the fill factor is improved. As can be seen from Example 1 and Examples 2-3, this disclosure can also use an oxidant solution for cleaning before or after cleaning with the texturing additive solution, which can increase the size of the clustered pyramids, thereby increasing the coverage of the clustered pyramids, reducing the gaps between the pyramids, and improving the battery performance. As can be seen from Example 1 and Example 4, this disclosure preferably uses a hydrophobic texturing additive solution for secondary cleaning, which can further improve the battery performance. As can be seen from Example 1 and Example 5, this disclosure can perform secondary texturing or multiple texturing, with texturing additive cleaning between the two texturing processes. As can be seen from Example 1 and Examples 6-9, the temperature of the secondary cleaning in this disclosure will affect the cleaning effect, thereby affecting the battery performance.

[0354] In summary, this disclosure provides a method for texturing a silicon substrate, a solar cell, and a method for fabricating a solar cell. The texturing method involves cleaning the silicon substrate after a single texturing process with a cleaning solution containing texturing additives to obtain a clustered pyramidal textured surface structure. This effectively utilizes the gaps between the pyramids, increases the density and compactness of the pyramidal textured surface, reduces the reflectivity of the silicon substrate, and is more conducive to passivation and current enhancement of the cell, thereby improving the photoelectric performance of the cell.

[0355] Those skilled in the art will understand that the above embodiments are specific examples of implementing this disclosure, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the embodiments of this disclosure. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the embodiments of this disclosure; therefore, the scope of protection of the embodiments of this disclosure should be determined by the scope defined in the claims.

Claims

1. A method for manufacturing a photovoltaic cell, characterized in that, include: A first substrate is provided, the first substrate having a pyramidal pile structure formed by a first pile forming process; Stack multiple first substrates or stack the first substrates and then move their positions; The first substrate is subjected to a second texturing process to form a second substrate.

2. The method for manufacturing a photovoltaic cell according to claim 1, characterized in that, The first texturing process is carried out at a first production site, and the second texturing process is carried out at a second production site; wherein the first production site and the second production site are located in different factories, or the first production site and the second production site are located in different areas of the same factory.

3. The method for manufacturing a photovoltaic cell according to claim 1 or 2, characterized in that, The step of providing the first substrate includes: providing a substrate, performing at least a first wet cleaning process and a first wet texturing process on the substrate; and / or, The second texturing process includes at least a second wet cleaning process and a second wet texturing process on the first substrate.

4. The method for manufacturing a photovoltaic cell according to claim 3, characterized in that, After the second wet texturing process, the second texturing treatment step also includes: Perform a water washing process; and / or, perform an oxidation cleaning process; and / or, perform a wet pickling process.

5. The method for manufacturing a photovoltaic cell according to claim 4, characterized in that, The oxidative cleaning process uses a cleaning solution comprising a mixture of hydrochloric acid and ozone, wherein the hydrochloric acid comprises 0.01 wt% to 3 wt% by weight, and the concentration of ozone dissolved in the mixture is 10 ppm to 60 ppm; or, the oxidative cleaning process uses a cleaning solution comprising a mixture of hydrofluoric acid and hydrogen peroxide, wherein the hydrofluoric acid comprises 0.5 wt% to 10 wt% by weight, and the hydrogen peroxide comprises 0.5 wt% to 10 wt% by weight.

6. The method for manufacturing a photovoltaic cell according to claim 4 or 5, characterized in that, The wet pickling process uses a cleaning solution comprising hydrofluoric acid and pickling additives, wherein the hydrofluoric acid comprises 0.5wt% to 8wt% by weight and the pickling additives comprise 0.5wt% to 5wt% by weight.

7. The method for manufacturing a photovoltaic cell according to any one of claims 3-6, characterized in that, The cleaning solution used in at least one of the first wet cleaning process and the second wet cleaning process is a mixed solution comprising an alkali and hydrogen peroxide, wherein the alkali is sodium hydroxide or potassium hydroxide; wherein the weight percentage of the alkali is 0.1 wt% to 10 wt%, and the weight percentage of the hydrogen peroxide is 0.5 wt% to 10 wt%.

8. The method for manufacturing a photovoltaic cell according to any one of claims 3-6, characterized in that, The cleaning solution used in at least one of the first wet texturing process and the second wet texturing process is a mixed solution comprising an alkali and a texturing additive, wherein the alkali is sodium hydroxide or potassium hydroxide; wherein the weight percentage of the alkali is 0.1 wt% to 10 wt%, and the weight percentage of the texturing additive is 0.1 wt% to 10 wt%.

9. The method for manufacturing a photovoltaic cell according to any one of claims 3-8, characterized in that, The process temperature of at least one of the first wet texturing process and the second wet texturing process is 55℃~85℃; and / or, the process duration of at least one of the first wet texturing process and the second wet texturing process is 100s~800s.

10. A method for manufacturing a photovoltaic cell according to any one of claims 1-9, characterized in that, The first base has two first surfaces opposite each other along a first direction, and at least one of the first surfaces includes a first pyramid structure; After the second texturing process, the second substrate has two second surfaces opposite each other along the first direction. At least one of the second surfaces includes a second pyramid structure and a first protrusion structure. The first protrusion structure is located on the side and / or side edge of the second pyramid structure, and along the first direction, the height of the first protrusion structure is less than the height of the second pyramid structure. The first direction is the thickness direction of the second substrate.

11. The method for manufacturing a photovoltaic cell according to claim 10, characterized in that, The base size of the second pyramid structure is greater than or equal to the base size of the first pyramid structure; and / or, the height of the second pyramid structure is greater than or equal to the height of the first pyramid structure.

12. The method for manufacturing a photovoltaic cell according to claim 10 or 11, characterized in that, The base size of the first pyramid structure is 1μm to 4.5μm, and the base size of the second pyramid structure is 1μm to 5μm; and / or, along the first direction, the height of the first pyramid structure is 0.5μm to 2μm, and the height of the second pyramid structure is 0.5μm to 2.5μm.

13. The method for manufacturing a photovoltaic cell according to any one of claims 10-12, characterized in that, The first base also has a first side surface connecting the two first surfaces, the first side surface including a third pyramid structure, the base size of the third pyramid structure being smaller than the base size of the first pyramid structure; and / or, The second base also has a second side surface connecting the two second surfaces. The second side surface includes a fourth pyramid structure and a second protrusion structure. The second protrusion structure is located on the side surface and / or side edge of the fourth pyramid structure and in a direction away from the second side surface, the height of the second protrusion structure is less than the height of the fourth pyramid structure; the base size of the fourth pyramid structure is less than the base size of the second pyramid structure.

14. The method for manufacturing a photovoltaic cell according to claim 13, characterized in that, In the step of stacking or transferring the position of multiple first bases, the first bases are transformed into initial second bases, the initial second bases having two initial second surfaces opposite each other along the first direction, and initial second side surfaces connecting the two initial second surfaces, the initial second side surfaces including fifth pyramid structures, at least a portion of the top of the fifth pyramid structures having defects; In the second texturing process, the defective portion is removed.

15. The method for manufacturing a photovoltaic cell according to claim 14, characterized in that, The base size of the fifth pyramid structure is 1μm to 3μm, and the height of the fifth pyramid structure in the direction perpendicular to the initial second side is 0.2μm to 1.5μm; and / or, the base size of the fourth pyramid structure is 1μm to 4.5μm, and the height of the fourth pyramid structure in the direction perpendicular to the second side is 0.5μm to 2.5μm.

16. The method for manufacturing a photovoltaic cell according to any one of claims 10-15, characterized in that, The step of providing the first substrate includes: Provide substrate; and The substrate is subjected to a first texturing process to form a first substrate, the first substrate having two first surfaces opposite each other along the first direction, at least one of the first surfaces including the first pyramid structure.

17. The method for manufacturing a photovoltaic cell according to any one of claims 13-15, characterized in that, The base size of the third pyramid structure is 1μm to 3μm, and the height of the third pyramid structure in the direction perpendicular to the first side is 0.2μm to 1.5μm; and / or the base size of the fourth pyramid structure is 1μm to 4.5μm, and the height of the fourth pyramid structure in the direction perpendicular to the second side is 0.5μm to 2.5μm.

18. The method for manufacturing a photovoltaic cell according to any one of claims 10-15, characterized in that, In the step of stacking or transferring the position of multiple first bases, the first bases are transformed into initial second bases, the initial second bases having two initial second surfaces opposite each other along the first direction, at least one of the initial second surfaces including a sixth pyramid structure, and at least a portion of the sixth pyramid structure having a defect at the top. In the second texturing process, the defective portion is removed, wherein the second pyramid structure and the first protrusion structure are formed on the basis of the sixth pyramid structure.

19. The method for manufacturing a photovoltaic cell according to claim 18, characterized in that, The base size of the second pyramid structure is greater than or equal to the base size of the sixth pyramid structure; and / or, the height of the second pyramid structure is greater than or equal to the height of the sixth pyramid structure.

20. The method for manufacturing a photovoltaic cell according to claim 18 or 19, characterized in that, The base dimensions of the sixth pyramid structure are 1μm to 4.5μm; and / or, along the first direction, the height of the sixth pyramid structure is 0.5μm to 2μm.

21. The method for manufacturing a photovoltaic cell according to any one of claims 1-20, characterized in that, Also includes: Impurity removal and cleaning processes are performed before the first texturing process; or, impurity removal and cleaning processes are performed after the first texturing process and before the second texturing process.

22. A photovoltaic cell, characterized in that, The photovoltaic cell is formed by the manufacturing method of a photovoltaic cell as described in any one of claims 1 to 21.

23. A photovoltaic module, characterized in that, include: A battery string is formed by connecting multiple photovoltaic cells manufactured by any one of the photovoltaic cells as described in any one of claims 1 to 21, or by connecting multiple photovoltaic cells as described in claim 22; An encapsulating film is used to cover the surface of the battery string; and A cover plate is used to cover the surface of the encapsulating film that faces away from the battery string.

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