Photovoltaic cell and method of forming the same, photovoltaic module

Abstract

The embodiment of the present application relates to the photovoltaic technical field, and particularly relates to a photovoltaic cell and a forming method thereof, and a photovoltaic module, the photovoltaic cell comprising: a substrate, a surface of the substrate comprising a mark area, the mark area being used for setting a mark code for marking product information of the photovoltaic cell; a first texture structure, the first texture structure being located on the mark area, the first texture structure comprising a first protruding structure, a side surface of the first protruding structure having a recess structure, and the recess structure constituting the mark code; and a second texture structure, the second texture structure being located on the surface of the substrate outside the mark area, and the second texture structure comprising a second protruding structure.The embodiment of the present application is at least beneficial to reducing the influence of the mark code on the efficiency of the photovoltaic cell and the appearance of the photovoltaic cell.

Description

Technical Field

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

[0002] A photovoltaic (PV) cell is a semiconductor device that converts solar energy into electrical energy, providing a clean, safe, and renewable energy source. Because PV cells are crucial for reducing environmental pollution, their manufacturing has attracted widespread attention.

[0003] In the current photovoltaic (PV) cell manufacturing process, marking codes are typically formed on the substrate surface to track processing information. By identifying these marking codes, process information and monitoring parameters can be obtained. However, the marking dots formed on the substrate surface not only affect the cell's appearance but also damage the substrate surface, impacting the PV cell's photoelectric conversion efficiency. Summary of the Invention

[0004] This application provides a photovoltaic cell and a method for forming the same, as well as a photovoltaic module, which at least helps to reduce the impact of marking codes on the efficiency and appearance of the photovoltaic cell.

[0005] This application provides a photovoltaic cell, including: a substrate, the surface of which includes a marking area for setting a marking code for marking product information of the photovoltaic cell; a first texture structure located in the marking area, the first texture structure including a first raised structure, the side of which has a recessed structure, the recessed structure constituting the marking code; and a second texture structure located on the substrate surface outside the marking area, the second texture structure including a second raised structure.

[0006] In some embodiments, the first protrusion structure has multiple sides, the recessed structure on the first protrusion structure is located on one side of the first protrusion structure, and in different first protrusion structures, the sides of the first protrusion structure with the recessed structure are parallel to each other.

[0007] In some embodiments, the first protrusion structure has multiple sides, and one side of the first protrusion structure has multiple independent recessed structures.

[0008] In some embodiments, the areas of the orthographic projections of different recessed structures onto the sides of the first protruding structure are different.

[0009] In some embodiments, the area of ​​the recessed structure projected onto the side of the first protruding structure is 0.1 μm. 2 ~0.5μm 2 .

[0010] In some embodiments, the maximum depth of the recessed structure is 2 μm to 4 μm along the direction perpendicular to the side of the first protruding structure.

[0011] Accordingly, embodiments of this application also provide a method for forming a photovoltaic cell, comprising: providing a substrate, the surface of which includes a marking area for setting a marking code for marking product information of the photovoltaic cell; forming a first texture structure in the marking area, the first texture structure including a first protrusion structure, the side of the first protrusion structure having a recessed structure, the recessed structure constituting the marking code; and forming a second texture structure on the substrate surface outside the marking area, the second texture structure including a second protrusion structure.

[0012] In some embodiments, the step of forming a first texture structure including a first protrusion structure includes: forming an initial texture structure in a marking area, the initial texture structure including a plurality of initial protrusion structures; forming a recessed structure on the side of the initial protrusion structure located in the marking area, wherein the initial protrusion structure having the recessed structure is the first protrusion structure.

[0013] In some embodiments, the step of forming a second texture structure including a second protrusion structure includes: while forming an initial texture structure in the marking area, forming an initial texture structure including a plurality of initial protrusion structures on the substrate surface outside the marking area, wherein the initial protrusion structure on the substrate surface outside the marking area is the second protrusion structure.

[0014] In some embodiments, forming a recessed structure on the side of the initial protrusion structure includes: laser processing the side of the initial protrusion structure to form a recessed structure.

[0015] In some embodiments, the ratio of the focal length of the laser processing to the beam diameter of the laser used in the laser processing is 0.9 to 1.1.

[0016] In some embodiments, the wavelength of the laser is 240nm to 280nm, and the beam quality factor of the laser is 1 to 1.2.

[0017] In some embodiments, forming an initial texture structure includes: texturing a substrate surface to form an initial texture structure including an initial raised structure.

[0018] Accordingly, this application also provides a photovoltaic module, including: a battery string, the battery string including the photovoltaic cells described in any of the above embodiments; an encapsulating film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulating film away from the battery string.

[0019] The technical solution provided in this application has at least the following advantages:

[0020] In the technical solution provided in this application embodiment, the substrate surface of the photovoltaic cell has a marking code for marking product information of the photovoltaic cell. The marking code is set in a marking area on the substrate surface, and the substrate surface has a textured structure. Specifically, the textured structure in the marking area is a first textured structure, and the textured structure on the substrate surface outside the marking area is a second textured structure. The first textured structure includes multiple first protrusions, and the second textured structure includes multiple second protrusions. The sides of the first protrusions in the marking area have recessed structures. The multiple recessed structures on the sides of the multiple first protrusions form the marking code for marking product information of the photovoltaic cell. That is, the recessed structures constitute the marking code. The method of placing the recessed structure of the marking dot on the side of the first raised structure forming the textured surface has the following advantages: First, compared with the larger marking dots of the prior art with diameters of 100μm to 130μm, the recessed structure provided in this embodiment is smaller and can be placed on the side of the first raised structure forming the textured surface. Therefore, the recessed structure forming the marking code has strong concealment, which is beneficial to making the appearance of the photovoltaic cell more aesthetically pleasing. Second, since the larger marking dots in the prior art occupy a larger space on the cell surface, the grid lines formed on the cell surface during the subsequent manufacturing process of the photovoltaic cell may be obstructed by the larger marking dots. The first point concerns the impact of code dot occlusion on code recognition. By designing the code dots as smaller, recessed structures, the area where subsequent grid lines are applied can be better avoided during the marking code setup, preventing grid lines from obstructing the recessed structure and improving its recognition accuracy, thus increasing the decoding rate of the marking code. The second point concerns the issue of larger code dots in existing technologies. In the subsequent manufacturing process of photovoltaic cells, larger code dots are easily detected as having poor luminescence or low yield during photoluminescence detection or appearance inspection. This means that some larger code dots can affect the photoelectric conversion performance of photovoltaic cells, reducing their yield. Designing the code dots as smaller, recessed structures addresses this issue. This can reduce the damage of the code dots to the battery surface, thereby improving the photoelectric conversion performance of the photovoltaic cell. Fourthly, in the existing technology, when forming large code dots on the substrate surface, the laser thermal effect will generate a ring of raised molten silicon at the edge of the code dots. The raised molten silicon cannot be completely removed in the subsequent texturing process, resulting in the edge of the code dots still having raised molten silicon higher than the remaining texturing structure. In the subsequent screen printing process, the raised molten silicon will cause abnormal wear to the screen used in the screen printing process, affecting the service life of the screen. By setting the recessed structure on the side of the first raised structure, the raised molten silicon higher than the texturing structure can be avoided, thus improving the service life of the screen. Attached Figure Description

[0021] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0022] Figure 1 A schematic diagram of a portion of the substrate surface of a photovoltaic cell provided in an embodiment of this application;

[0023] Figure 2 A schematic diagram of a portion of the substrate surface of a photovoltaic cell, including a marking code, provided for an embodiment of this application;

[0024] Figure 3 This is a schematic diagram of a textured surface structure on a portion of the substrate surface of a photovoltaic cell, provided in an embodiment of this application.

[0025] Figure 4 A schematic diagram of a textured surface structure on a portion of the substrate surface of another photovoltaic cell provided in an embodiment of this application;

[0026] Figure 5 A schematic diagram of a textured surface structure on a portion of the substrate surface of another photovoltaic cell provided in an embodiment of this application;

[0027] Figure 6 A schematic diagram of a textured surface structure on a portion of the substrate surface of a photovoltaic cell, provided as an embodiment of this application.

[0028] Figure 7 A schematic diagram of the orthographic projection of a recessed structure of a photovoltaic cell provided in an embodiment of this application on the side of a first protruding structure;

[0029] Figure 8 A schematic diagram of the orthographic projection of a recessed structure of a photovoltaic cell provided in an embodiment of this application on the side of the first protruding structure.

[0030] Figure 9 A schematic cross-sectional view of the first protrusion structure of a photovoltaic cell provided in this application embodiment along a direction perpendicular to the substrate surface;

[0031] Figure 10 This is a schematic diagram of the structure of a first protrusion structure of a photovoltaic cell provided in an embodiment of this application;

[0032] Figure 11 A schematic cross-sectional view of the textured surface structure of a portion of the substrate surface of a photovoltaic cell provided in this application embodiment, along a direction perpendicular to the substrate surface;

[0033] Figure 12 A cross-sectional structural diagram of a photovoltaic cell provided in an embodiment of this application;

[0034] Figures 13 to 15 A schematic diagram illustrating the steps of a method for forming a photovoltaic cell according to an embodiment of this application;

[0035] Figure 16 This is a structural schematic diagram of a photovoltaic module provided in an embodiment of this application. Detailed Implementation

[0036] As is known from the background technology, the code points of the constituent marking codes formed on the substrate surface not only affect the appearance of photovoltaic cells, but also damage the surface of the substrate, thus affecting the photoelectric conversion efficiency of photovoltaic cells.

[0037] Analysis revealed the following drawbacks in existing photovoltaic (PV) cell marking technologies: the diameter of the marking dots is approximately 100μm to 130μm, while the size of the raised structures forming the textured surface of the cell is typically less than 15μm. For example, the pyramid structure constituting the textured surface typically has a dimension less than 10μm perpendicular to the substrate surface, and the maximum dimension at the base of the pyramid is also typically less than 15μm. Compared to the raised structures forming the textured surface, the marking dots in existing technologies are larger. Larger marking dots not only have poor concealment but also occupy more space on the cell surface. During subsequent PV cell manufacturing, the grid lines formed on the cell surface may obscure these larger marking dots, affecting their identification. Furthermore, during PV cell manufacturing, some larger marking dots are easily detected as having poor luminescence or low yield during photoluminescence detection or visual inspection. In other words, some larger marking dots can affect the photoelectric conversion performance of PV cells, reducing their yield. Furthermore, when forming large code dots on the substrate surface, the laser thermal effect will generate a ring of raised molten silicon at the edge of the code dots. The raised molten silicon cannot be completely removed in the subsequent texturing process, resulting in raised molten silicon at the edge of the code dots that is higher than the remaining texturing structure. In the subsequent screen printing process, the raised molten silicon will cause abnormal wear to the screen used in the screen printing process, affecting the service life of the screen.

[0038] To address the aforementioned issues, this application provides a photovoltaic cell and its formation method, as well as a photovoltaic module. The photovoltaic cell includes a marking code located on the surface of a substrate for marking product information. The marking code is disposed in a marking area on the substrate surface, and the substrate surface has a textured structure. Specifically, the textured structure in the marking area is a first textured structure, and the textured structure on the substrate surface outside the marking area is a second textured structure. The first textured structure includes multiple first protrusions, and the sides of the first protrusions in the marking area have recessed structures. Multiple recessed structures on the sides of the multiple first protrusions form the marking code; that is, the recessed structures are the code dots that make up the marking code. By reducing the size of the recessed structures and placing them on the sides of the first protrusions, the concealment of the recessed structures is improved, which helps to make the photovoltaic cell more aesthetically pleasing. Furthermore, when setting the marking code, smaller recessed structures can better avoid areas where grid lines are subsequently set, thereby preventing grid lines from obstructing the recessed structures and thus improving the decoding rate of the marking code. In addition, setting the code dots as smaller recessed structures can reduce damage to the cell surface, thereby improving the photovoltaic photoelectric conversion performance. Furthermore, by placing the recessed structure on the side of the first raised structure, it is possible to avoid the formation of raised molten silicon that is higher than the textured surface when the recessed structure is formed. This helps to prevent the raised molten silicon from causing wear on the screen printing plate used in the screen printing process, thereby improving the service life of the screen.

[0039] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the embodiments. However, the technical solutions claimed in the embodiments of this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0040] Figure 1 A schematic diagram of a portion of the substrate surface of a photovoltaic cell provided in an embodiment of this application; Figure 2 A schematic diagram of a portion of the substrate surface of a photovoltaic cell, including a marking code, provided for an embodiment of this application; Figure 3 This is a schematic diagram of a textured surface structure on a portion of the substrate surface of a photovoltaic cell, provided in an embodiment of this application. Figure 4 A schematic diagram of a textured surface structure on a portion of the substrate surface of another photovoltaic cell provided in an embodiment of this application; Figure 5 A schematic diagram of a textured surface structure on a portion of the substrate surface of another photovoltaic cell provided in an embodiment of this application; Figure 6 This is a schematic diagram of a textured surface structure on a portion of the substrate surface of a photovoltaic cell, as provided in an embodiment of this application.

[0041] refer to Figures 1 to 6The photovoltaic cell includes: a substrate 10, the surface of which includes a marking area 11 for setting a marking code 13 for marking product information of the photovoltaic cell; a first texture structure 100 located in the marking area 11, the first texture structure 100 including a first protrusion structure 110, the side of the first protrusion structure 110 having a recessed structure 111, the recessed structure 111 constituting the marking code 13; and a second texture structure 200 located on the surface of the substrate 10 outside the marking area 11, the second texture structure 200 including a second protrusion structure 210.

[0042] In this design, the first texture structure 100 is the velvety surface structure of the marking area 11, and the second texture structure 200 is the velvety surface structure of the substrate 10 surface outside the marking area 11. The sides of the first protruding structure 110 in the marking area 11 have recessed structures 111. Multiple recessed structures 111 on the sides of the first protruding structures 110 form the marking code 13; that is, the recessed structures 111 are the code points that make up the marking code 13. Thus, by reducing the size of the recessed structures 111 and placing them on the sides of the first protruding structures 110 that form the velvety surface structure, the concealment of the recessed structures 111 that make up the marking code 13 is improved, which helps to make the photovoltaic cell more aesthetically pleasing. Furthermore, when setting the marking code 13, the smaller size of the recessed structures 111 can better avoid areas where subsequent grid lines are set, thereby preventing the grid lines from obstructing the recessed structures 111, which helps to improve the recognizability of the recessed structures 111, and thus helps to improve the decoding rate of the marking code 13. Furthermore, by setting the code dots as small recessed structures 111, damage to the cell surface caused by the code dots can be reduced, thereby improving the photovoltaic conversion performance. By placing the recessed structure 111 on the side of the first raised structure 110, it is possible to avoid the formation of raised molten silicon that is higher than the textured surface during the formation of the recessed structure 111. This helps to prevent the raised molten silicon from causing wear on the screen printing plate used in the screen printing process, thus improving the lifespan of the screen printing plate.

[0043] A photovoltaic cell is a solar cell. The substrate 10 is a substrate used to manufacture photovoltaic cells. In some embodiments, the substrate 10 is a silicon substrate. The material of the silicon substrate may include monocrystalline silicon, polycrystalline silicon, amorphous silicon, and microcrystalline silicon. In other embodiments, the material of the substrate 10 may also be carbon, organic materials, and multi-component compounds, including gallium arsenide, cadmium telluride, or copper indium selenide, etc.

[0044] The surface of substrate 10 is the light-receiving surface of the photovoltaic cell, as shown in the reference. Figure 1 , Figure 2 and Figure 3The light-receiving surface of the substrate 10 other than the marked area 11 is defined as the unmarked area 12. The first texture structure 100 constitutes the velvet structure of the marked area 11, and the second texture structure 200 constitutes the velvet structure of the unmarked area 12.

[0045] The textured surface increases the number of times light refracts on the surface of a photovoltaic cell, which helps improve the absorption and utilization rate of light by the photovoltaic cell, and thus improves the photoelectric conversion efficiency of the photovoltaic cell.

[0046] The marking area 11 is used to set the marking code 13, which is used to mark the product information of the photovoltaic cell. The product information of the photovoltaic cell may include: the processing steps of the photovoltaic cell, the product model of the photovoltaic cell, the batch number of the photovoltaic cell, and the monitoring parameter information during the processing. By scanning the marking code 13 with light, the product information of the photovoltaic cell can be identified, which is conducive to the traceability of the photovoltaic cell processing process and the management of the photovoltaic cell processing.

[0047] In some embodiments, the marker code 13 can be a QR code (Quick Response Code). QR codes have advantages such as large information capacity, high reliability, ability to represent Chinese characters and various image and text information, and strong security and anti-counterfeiting features. Using a QR code as the marker code 13 is beneficial for improving the decoding rate of the marker code 13 and for storing more photovoltaic cell product information. In one example, the marker code 13 can be a 29×29 arranged QR code. In other examples, the marker code 13 can also be a 35×35 arranged QR code or other arranged QR codes. Specifically, the arrangement of the QR code can be reasonably set according to the size of the photovoltaic cell and the storage requirements of the photovoltaic cell product information.

[0048] In some embodiments, the marker code 13 may also be other forms of two-dimensional graphic codes, one-dimensional graphic codes, or three-dimensional graphic codes. In other embodiments, the marker code 13 may also be a marker code 13 in the form of characters, data matrices, or barcodes.

[0049] refer to Figures 1 to 3 The recessed structure 111 located on the side of the first protruding structure 110 is the code point that makes up the mark code 13. Specifically, the recessed structure 111 can be a laser pit made by laser on the surface of the substrate 10, and multiple laser pits connected into a line or forming a pattern are the mark code 13.

[0050] In some embodiments, the photovoltaic cell is a single-sided cell, in which case the front side of the substrate 10 can be the light-receiving surface and the back side of the substrate 10 can be the back-light-receiving surface. Correspondingly, the marking code 13 is located on the front side of the substrate 10, and the textured structure including the first textured structure 100 and the second textured structure 200 is located on the front side of the substrate 10. In other embodiments, the photovoltaic cell can be a bi-sided cell, in which case both opposite surfaces of the substrate 10 can be light-receiving surfaces. Correspondingly, in one example, the marking code 13 can be located on at least one of the two opposite surfaces of the substrate 10. In another example, the marking code 13 can also be located on both opposite surfaces of the substrate 10, i.e., both the first textured structure 100 and the second textured structure 200 are located on both opposite surfaces of the substrate 10. This application describes an embodiment where the photovoltaic cell is a single-sided cell and the front side of the substrate 10 is the light-receiving surface.

[0051] refer to Figures 1 to 6 The first protrusion structure 110 is a microstructure constituting the first texture structure 100, which is composed of a plurality of first protrusion structures 110. In some embodiments, the first texture structure 100 includes a plurality of non-connected parts. In one example, the first texture structure 100 includes a first part and a second part, wherein the first part of the first texture structure 100 may be composed of a plurality of interconnected first protrusion structures 110, and the second part of the first texture structure 100 may be composed of a plurality of interconnected first protrusion structures 110. The distribution of the first protrusion structures 110 constituting the first texture structure 100 on the surface of the substrate 10 mainly depends on the position of the marking code 13 on the surface of the substrate 10.

[0052] Similarly, the second protrusion structure 210 is a microstructure constituting the second texture structure 200. The second texture structure 200 can be composed of a single second protrusion structure 210, or it can be composed of multiple interconnected second protrusion structures 210. In some embodiments, the second texture structure 200 can be composed of multiple non-connected parts. The distribution of the second protrusion structures 210 constituting the second texture structure 200 on the surface of the substrate 10 mainly depends on the position of the unmarked area 12 on the surface of the substrate 10.

[0053] In some embodiments, the first protruding structure 110 is a pyramid-like structure with recessed structures 111 on its sides, and the second protruding structure 210 is also a pyramid-like structure. The velvet structure composed of pyramid-like structures is a common velvet structure, which helps reduce the manufacturing difficulty of the second protruding structure 210. Furthermore, the pyramid-like structure has smooth sides, and forming recessed structures 111 on the sides of the pyramid-like structure helps reduce the difficulty of setting the recessed structures 111, thereby reducing the difficulty of forming the first protruding structure 110. It is understood that in other embodiments, the first protruding structure 110 may also be a protruding structure of other shapes with smooth sides and recessed structures 111, and the second protruding structure 210 may also be a protruding structure of other shapes. This application uses the example of the first protruding structure 110 being a pyramid-like structure with recessed structures 111 on its sides and the second protruding structure 210 being a pyramid-like structure to illustrate the first protruding structure 110 and the second protruding structure 210.

[0054] In some embodiments, reference Figure 2 and Figure 3 The first protruding structure 110 has multiple sides, and recessed structures 111 can be provided on different sides of the first protruding structure 110. That is, a first protruding structure 110 has multiple recessed structures 111, and the recessed structures 111 can be located on different sides of the first protruding structure 110. Specifically, since two adjacent sides can directly receive light emitted from the same direction, the recessed structures 111 can be provided on two adjacent sides of the first protruding structure 110. This facilitates the identification of the recessed structures 111 located on two adjacent sides by light emitted from the same direction, improving the recognition accuracy of the recessed structures 111, and thus improving the decoding rate of the tag code 13.

[0055] In some embodiments, reference Figure 2 and Figure 4 The first protruding structure 110 has multiple sides, and the recessed structure 111 is located on one side of the first protruding structure 110. Furthermore, among the different first protruding structures 110, the sides of the first protruding structure 110 with the recessed structure 111 are parallel to each other. These parallel sides can directly receive light emitted from the same direction. Therefore, it is advantageous to identify the recessed structures 111 on multiple first protruding structures 110 using light emitted from the same direction, thereby improving the recognition accuracy of the recessed structures 111 and ultimately increasing the decoding rate of the tag code 13.

[0056] In some embodiments, reference Figure 2 , Figure 3 and Figure 4The first protruding structure 110 has multiple sides, while the side of the first protruding structure 110 with the recessed structure 111 has only one recess. Thus, based on the area of ​​the side of the first protruding structure 110, a relatively large recessed structure 111 can be set. Since forming a small recessed structure 111 is difficult, setting only one recessed structure 111 on one side of the first protruding structure 110 helps to increase the size of the recessed structure 111 within a limited space, thereby reducing the difficulty of forming the recessed structure 111. Furthermore, a larger recessed structure 111 has higher recognizability, which helps to improve the decoding rate of the marker code 13.

[0057] In some embodiments, reference Figure 2 and Figure 5 The first protruding structure 110 has multiple sides, and one side of the first protruding structure 110 has multiple independent recessed structures 111. This allows the recessed structures 111 constituting the tag code 13 to have a higher density. The higher the density of the recessed structures 111 forming the tag code 13, the easier the tag code 13 is to be identified. Increasing the density of the recessed structures 111 on the surface of the substrate 10 is beneficial to improving the decoding rate of the tag code 13.

[0058] Continue to refer to Figure 5 In some embodiments, the areas of the orthographic projections of different recessed structures 111 onto the side of the first protruding structure 110 are different. It should be noted that the orthographic projection of a recessed structure 111 onto the side of the first protruding structure 110 is the orthographic projection of the recessed structure 111 onto the side of the first protruding structure 110. The different areas of the orthographic projections of different recessed structures 111 onto the side of the first protruding structure 110 indicate that the sizes of the different recessed structures 111 are different. Specifically, the different recessed structures 111 can be different recessed structures 111 located on one side of the same first protruding structure 110. By setting multiple recessed structures 111 located on the same side as recessed structures 111 of different sizes, the smaller recessed structures 111 can occupy the remaining side of the larger recessed structures 111, thereby increasing the area occupied by the recessed structures 111 on the limited side of the first protruding structure 110. This is beneficial for achieving a higher density of the recessed structures 111 constituting the tag code 13 on the surface of the substrate 10, thereby improving the decoding rate of the tag code 13. In other embodiments, the different recessed structures 111 may be recessed structures 111 located on different first protruding structures 110, or the different recessed structures 111 may be recessed structures 111 located on different sides of the same first protruding structure 110. The dimensions of the different recessed structures 111 can be adjusted according to specific needs.

[0059] In some embodiments, reference Figure 2and Figure 5 The number of recessed structures 111 located on different sides can be the same. In other embodiments, refer to Figure 2 and Figure 6 The number of recessed structures 111 located on different sides can also be different.

[0060] Figure 7 A schematic diagram of the orthographic projection of a recessed structure of a photovoltaic cell provided in an embodiment of this application on the side of a first protruding structure; Figure 8 A schematic diagram of the orthographic projection of a recessed structure of a photovoltaic cell provided in an embodiment of this application on the side of the first protruding structure. Figure 9 A schematic cross-sectional view of the first protrusion structure of a photovoltaic cell provided in this application embodiment along a direction perpendicular to the substrate surface; Figure 10 This is a schematic diagram of the structure of a first protrusion structure of a photovoltaic cell provided in an embodiment of this application; Figure 11 This is a schematic cross-sectional view of the textured surface of a portion of the substrate surface of a photovoltaic cell, provided in an embodiment of this application, along a direction perpendicular to the substrate surface.

[0061] In some embodiments, reference Figure 7 The recessed structure 111 can be a hemispherical recess, and the orthographic projection of the recessed structure 111 onto the side of the first protruding structure 110 is circular. It is understood that in other embodiments, the recessed structure 111 can also be a recess of other shapes, for example, referring to... Figure 8 The recessed structure 111 is an irregularly shaped recess. As long as the recessed structure 111 satisfies the condition of constituting a marking code, the specific shape of the recessed structure 111 is not restricted.

[0062] In some embodiments, the area of ​​the recessed structure 111 projected onto the side of the first protruding structure 110 is 0.1 μm. 2～ 0.5μm 2 For example, it can be 0.2μm. 2 0.25μm 2 0.3μm 2 0.4μm 2 Or 0.43μm 2Forming a recessed structure 111 that is too small is difficult, and such a small recessed structure 111 is not easily identifiable. Therefore, if the area of ​​the orthographic projection of the recessed structure 111 onto the side of the first protruding structure 110 is too small, the size of the recessed structure 111 will be too small. This will not only increase the difficulty of forming the recessed structure 111, but also reduce its identifiability. In addition, the space on the side of the first protruding structure 110 is limited. A recessed structure 111 that is too large cannot be placed on the side of the first protruding structure 110, and may also cause the recessed structure 111 to be too close to the prismatic structure of the edge of the side of the first protruding structure 110, reducing the stability of the prismatic structure of the first protruding structure 110, and thus affecting the stability of the first protruding structure 110. Therefore, the area of ​​the orthographic projection of the recessed structure 111 onto the side of the first protruding structure 110 is set to 0.1 μm. 2 ~0.5μm 2 This not only helps reduce the difficulty of forming the recessed structure 111, but also helps ensure that the recessed structure 111 has high recognizability, and helps avoid the recessed structure 111 affecting the stability of the first protruding structure 110.

[0063] In some embodiments, reference Figure 9 Along the direction perpendicular to the side of the first protruding structure 110, the maximum depth L1 of the recessed structure 111 is 2μm to 4μm. For example, it can be 2.1μm, 2.5μm, 2.8μm, 3μm, or 3.5μm. If the maximum depth L1 of the recessed structure 111 is too small, the recessed structure 111 may have poor recognition or even be unrecognizable. If the maximum depth L1 of the recessed structure 111 is too large, it may affect the stability of the first protruding structure 110 and increase the difficulty of forming the recessed structure 111. Therefore, setting the maximum depth L1 of the recessed structure 111 to 2μm to 4μm not only helps to ensure that the recessed structure 111 can be accurately identified, but also helps to avoid the recessed structure 111 affecting the stability of the first protruding structure 110, and helps to reduce the difficulty of forming the recessed structure 111.

[0064] In some embodiments, reference Figure 9 Along the direction from the first texture structure to the substrate, the maximum height L2 of the first protrusion structure 110 can be 3μm to 5μm. For example, it can be 3.1μm, 3.5μm, 3.8μm, 4μm, or 5μm. (Reference) Figure 10 Along the direction perpendicular to the first texture structure pointing towards the substrate, the maximum width L3 of the first protrusion structure 110 can be 6μm to 12μm. For example, it can be 6.1μm, 6.5μm, 8μm, 9μm, or 10μm.

[0065] It should be noted that the dimensions of different first protrusion structures 110 can be the same or different, and the dimensions of different second protrusion structures 210 can be the same or different.

[0066] refer to Figure 11 In some embodiments, a smaller second protrusion structure 210 may also be present between adjacent first protrusion structures 110.

[0067] It should be noted that, compared with the larger code dots in the prior art, the recessed structure 111 provided in this application embodiment has a smaller size. Therefore, when identifying the mark code composed of the recessed structure 111, low-angle illumination can be used to identify the mark code, thereby improving the recognition accuracy of the mark code.

[0068] Figure 12 This is a schematic cross-sectional view of a photovoltaic cell provided in an embodiment of this application. (Reference) Figure 12 The photovoltaic cell also includes: an emitter 16, a first passivation layer 17, a second passivation layer 18, a first electrode 19, and a second electrode 20. Specifically, the substrate 10 has a front side 14 and a back side 15. The front side 14 of the substrate 10 is the light-receiving surface and has a textured surface. The emitter 16 is located on the front side 14 of the substrate 10. Both the emitter 16 and the substrate 10 contain doped elements. The doped elements can be P-type doped elements (such as boron, aluminum, gallium, indium, or thallium) or N-type doped elements (such as phosphorus, arsenic, antimony, or bismuth). The doped element type of the emitter 16 is different from that of the substrate 10, so that a PN junction is formed between the substrate 10 and the emitter 16. The first passivation layer 17 is located on the back side of the substrate 10, and the second passivation layer 18 is located on the front side of the substrate 10. The first passivation layer 17 and the second passivation layer 18 serve a passivation protection function. The first electrode 19 is located on the first passivation layer 17 away from the surface of the substrate 10, and the first electrode 19 penetrates the first passivation layer 17 and contacts the substrate 10. The second electrode 20 is located on the second passivation layer 18 away from the surface of the substrate 10, and the second electrode 20 penetrates the second passivation layer 18 and contacts the emitter 16. The first electrode 19 and the second electrode 20 are used to collect charge carriers.

[0069] In some embodiments, the marker code can be disposed between the second electrodes 19 on the front side 14 of the substrate 10, that is, the marker code is located between the grid lines on the front side 14 of the substrate 10, and the marker code does not overlap or intersect with the grid lines. This helps to avoid the grid lines obstructing the marker code.

[0070] The photovoltaic cell provided in the above embodiment includes a marking code 13 located on the surface of a substrate 10 for marking product information of the photovoltaic cell. The marking code 13 is disposed in a marking area 11 on the surface of the substrate 10. The surface of the substrate 10 has a textured structure. The textured structure located in the marking area 11 is a first textured structure 100, and the textured structure located on the surface of the substrate 10 outside the marking area 11 is a second textured structure 200. The first textured structure 100 includes a plurality of first protruding structures 110, and the second textured structure 200 includes a plurality of second protruding structures 210. The side of the first protruding structure 110 located in the marking area 11 has a recessed structure 111. The plurality of recessed structures 111 on the side of the plurality of first protruding structures 110 form the marking code 13 for marking product information of the photovoltaic cell. That is, the recessed structure 111 is the code point that makes up the marking code 13. By reducing the size of the recessed structure 111 and placing the recessed structure 111 on the side of the first protruding structure 110 that makes up the textured structure, the concealment of the recessed structure 111 is improved, making the appearance of the photovoltaic cell more aesthetically pleasing. Furthermore, when setting the marker code 13, the smaller recessed structure 111 can better avoid areas where subsequent grid lines are set, thus preventing the grid lines from obstructing the recessed structure 111 and improving the decoding rate of the marker code 13. Additionally, setting the code point to a smaller recessed structure 111 reduces damage to the battery surface, thereby improving the photovoltaic photoelectric conversion performance. Placing the recessed structure 111 on the side of the first protruding structure 110 also avoids the formation of raised molten silicon above the textured surface during the formation of the recessed structure 111, thus preventing wear on the screen printing plate and extending its lifespan.

[0071] Accordingly, another aspect of this application provides a method for forming a photovoltaic cell, which can be used to form the photovoltaic cell provided in the above embodiments. It should be noted that the parts that are the same as or corresponding to those in the foregoing embodiments can be found in the detailed descriptions of the foregoing embodiments, and will not be repeated hereafter.

[0072] Figures 13 to 15 This is a schematic diagram illustrating the steps of a method for forming a photovoltaic cell according to an embodiment of this application. It should be noted that, for the sake of simplicity, the accompanying drawings... Figures 13 to 15 Only a partial cross-section of the photovoltaic cell is shown; the complete cell with full marking code 13 is not shown.

[0073] Methods for forming photovoltaic cells include: (Reference) Figure 1 as well as Figure 13 A substrate 10 is provided, the surface of which includes a marking area 11 for setting a marking code that marks product information of the photovoltaic cell. The substrate 10 is a substrate for manufacturing photovoltaic cells, and in some embodiments, the substrate 10 may be a silicon substrate 10.

[0074] In some embodiments, the photovoltaic cell can be a single-sided cell, in which case the front surface 14 of the substrate 10 can be the light-receiving surface, the marking area 11 is located on the front surface 14 of the substrate 10, and the front surface 14 of the substrate 10 other than the marking area 11 is the non-marking area 12.

[0075] refer to Figures 14 to 15 A first texture structure 100 is formed in the marking area 11. The first texture structure 100 includes a first protrusion structure 110, and the side of the first protrusion structure 110 has a recessed structure 111, which constitutes a marking code. A second texture structure 200 is formed on the surface of the substrate 10 outside the marking area 11. The second texture structure 200 includes a second protrusion structure 210. The recessed structure 111 is located on the side of the first protrusion structure 110, which improves the concealment of the recessed structure 111 that constitutes the marking code, makes the photovoltaic cell more aesthetically pleasing, and avoids the grid lines from obstructing the small recessed structure 111, thereby improving the decoding rate of the marking code 1. Furthermore, setting the code point as a small recessed structure 111 reduces damage to the cell surface caused by the code point, thus improving the photovoltaic photoelectric conversion performance. Setting the recessed structure 111 on the side of the first protruding structure 110 also helps to avoid the formation of molten silicon that is higher than the textured surface when the recessed structure 111 is formed. This helps to avoid the molten silicon from the protruding surface from causing wear on the screen printing plate used in the screen printing process, and helps to improve the service life of the screen.

[0076] In some embodiments, the step of forming a first texture structure 100 including a first protrusion structure 110 may include: referring to Figure 14 An initial texture structure 300 is formed in the marked area 11, the initial texture structure 300 including multiple initial bump structures 310; Reference Figure 15 A recessed structure 111 is formed on the side of the initial protrusion structure located in the marking area 11, and the initial protrusion structure with the recessed structure 111 is the first protrusion structure 110. Compared with directly forming the first protrusion structure 110 with the recessed structure 111, the method of forming the initial protrusion structure 310 and forming the recessed structure 111 on the side of the initial protrusion structure 310 to prepare the first protrusion structure 110 is easier to implement and helps to reduce the difficulty of forming the first protrusion structure 110.

[0077] In some embodiments, reference Figure 14 and Figure 15The step of forming a second texture structure 200 including a second protrusion structure 210 includes: simultaneously forming an initial texture structure 300 in the marking area 11, and also forming an initial texture structure 300 including multiple initial protrusion structures 310 on the surface of the substrate 10 outside the marking area 11. The initial protrusion structures 310 on the surface of the substrate 10 outside the marking area 11 are the second protrusion structures 210. That is, an initial texture structure 300 including an initial protrusion structure 310 is formed simultaneously in the marking area 11 and the non-marking area 12, and then a recessed structure 111 is formed only on the side of the initial protrusion structure 310 in the marking area 11 to form a first protrusion structure 110. The remaining initial protrusion structures 310 without a recessed structure 111 are the second protrusion structures 210. Forming the second protrusion structure 210 simultaneously with the first protrusion structure 110 helps to reduce the difficulty of forming the first protrusion structure 110 and the second protrusion structure 210 on the surface of the substrate 10.

[0078] In some embodiments, reference Figure 14 Forming the initial texture structure 300 may include texturing the surface of the substrate 10 to form the initial texture structure 300 including the initial protrusion structure 310. Specifically, solution texturing can be used to texturize the surface of the substrate 10. In one example, the substrate 10 is monocrystalline silicon, and a mixture of alkaline and alcohol solutions can be used to texturize the surface of the substrate 10 to form the initial texture structure 300 including the initial protrusion structure 310. In another example, the substrate 10 is polycrystalline silicon, and an acid solution can be used to texturize the surface of the substrate 10 to form the initial texture structure 300 including the initial protrusion structure 310. It is understood that in other embodiments, laser texturing or reactive ion etching (RIE) texturing processes can also be used to prepare the initial texture structure 300 including the initial protrusion structure 310.

[0079] In some embodiments, reference Figure 14 and Figure 15 Forming a recessed structure 111 on the side of the initial protrusion structure 310 includes: laser processing the side of the initial protrusion structure 310 to form the recessed structure 111. When forming the recessed structure 111 using a laser, the position, shape, and depth of the recessed structure 111 are easier to control. Using a laser not only helps to form a highly recognizable recessed structure 111, but also helps to avoid damage to the surface of the substrate 10 where the recessed structure 111 has not been formed.

[0080] The size of the recessed structure 111 formed by the laser depends on the size of the laser spot on the surface of the substrate 10. Since diffraction is inevitable during laser propagation, for aspherical lenses, considering only the effect of diffraction on the laser spot, the size of the laser spot on the surface of the substrate 10 is usually determined by the following parameters: laser beam diameter D, focal length f, laser wavelength λ, and laser divergence M. 2 The relationship between the diameter d of the light spot and the above parameters can be satisfied by the following formula:

[0081]

[0082] Formula (1) shows that the diameter d of the light spot is directly proportional to the focal length f of the focusing lens and the laser wavelength λ, and inversely proportional to the diameter D of the laser beam.

[0083] Based on the above analysis, in some embodiments, ultraviolet lasers can be used as the lasers used for laser processing. Ultraviolet lasers have advantages such as short wavelength, high photon energy, small diffraction effect, strong resolution and small thermal effect. Using ultraviolet lasers is beneficial to reducing the diameter d of the light spot, which in turn is beneficial to forming a smaller recessed structure 111 located on the side of the first protrusion structure 110.

[0084] In some embodiments, the ratio of the focal length f to the beam diameter D of the laser used in the laser processing can be set to 0.9 to 1.1. For example, it can be 0.95, 0.97, 0.98, 1, or 1.05. Setting the ratio of the focal length f to the laser beam diameter D close to 1 reduces the influence of the focal length f and the laser beam diameter D on the spot diameter d, allowing the laser wavelength λ and the laser divergence M to be used more effectively. 2 Controlling the effect of diffraction on the diameter d of the light spot helps reduce the difficulty of controlling the size of the light spot, which in turn helps reduce the manufacturing difficulty of the recessed structure 111.

[0085] Furthermore, if the ratio of focal length f to laser beam diameter D is set to be close to 1, and the laser divergence M is... 2 Set to meet 2M 2 When the wavelength is close to π, the diameter of the light spot is d = 2λ. Therefore, reducing the wavelength λ of the laser will reduce the diameter d of the light spot.

[0086] Based on the above analysis, in some embodiments, the laser wavelength can be set to 240nm–280nm, for example, 240nm, 250nm, 260nm, or 265nm. The laser beam quality factor can be set to 1–1.2, for example, 1, 1.02, 1.05, or 1.12. Thus, assuming the ratio of focal length f to laser beam diameter D is 1, when the laser wavelength and laser beam quality factor satisfy the above values, the laser divergence M can be reduced. 2 Set to meet 2M 2 In cases close to π, a smaller spot size can be formed by reducing the laser wavelength λ. In some examples, a laser wavelength of 261 nm is used, and the laser divergence M... 2 A short-wavelength continuous ultraviolet laser with a wavelength of 1.12 can produce a spot with a diameter d of 0.402 μm, which translates to a spot area of ​​0.127 μm. 2 In this way, the area of ​​the formed concave structure 111 projected onto the side of the first protruding structure 110 is within 0.1 μm. 2 ~0.5μm 2 In between, the size of the recessed structure 111 was effectively reduced.

[0087] In addition, the size of the light spot is also affected by spherical aberration. The larger the spherical aberration, the larger the size of the light spot. Therefore, in some embodiments, a lens with a smaller spherical aberration can be selected for laser processing, such as a concave-convex lens, to reduce the influence of spherical aberration on the size of the light spot, which is conducive to more precise control of the size of the concave structure 111.

[0088] In some embodiments, a beam expander can be used to change the laser beam diameter D, thereby controlling the size of the laser spot using the beam diameter D.

[0089] In some embodiments, referring to 12, the method of forming a photovoltaic cell may further include: forming an emitter 16, a first passivation layer 17, a second passivation layer 18, a first electrode 19, and a second electrode 20.

[0090] In the photovoltaic cell formation method provided in the above embodiments, a recessed structure 111 is formed on the side of the initial protrusion structure 310 by laser processing. Furthermore, by controlling the laser parameters to control the size of the laser spot, the size of the recessed structure 111 formed by the laser is controlled. This is beneficial for forming a smaller recessed structure 111 on the side of the initial protrusion structure 310 and for reducing the difficulty of forming a smaller recessed structure 111.

[0091] Figure 16 This is a structural schematic diagram of a photovoltaic module provided in an embodiment of this application.

[0092] Accordingly, embodiments of this application also provide a photovoltaic module, with reference to... Figure 16 The photovoltaic module includes: a battery string, the battery string including the photovoltaic cell 30 as described in any of the above embodiments; an encapsulating film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulating film away from the battery string.

[0093] In this structure, multiple photovoltaic cells 30 are connected in series or parallel to form a battery string. The encapsulating film can be an organic encapsulating film such as EVA or POE, which covers the surface of the battery string to seal and protect it. The encapsulating film includes a first encapsulating film 31 and a second encapsulating film 32, which are respectively covered on both sides of the surface of the battery string. The cover plate can include a first cover plate 33 and a second cover plate 34. The first cover plate 33 is used to cover the surface of the first encapsulating film 31 away from the battery string, and the second cover plate 34 is used to cover the surface of the second encapsulating film 32 away from the battery string. The cover plate can be a glass cover plate or a plastic cover plate, etc., used to protect the battery string.

[0094] Those skilled in the art will understand that the above-described embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of this application. Any person skilled in the art can make their own variations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A photovoltaic cell, characterized in that, include: A substrate, the surface of which includes a marking area for setting a marking code that marks product information of the photovoltaic cell; A first texture structure is located in the mark area, the first texture structure comprises a first convex structure, the side surface of the first convex structure has a concave structure, and the concave structure constitutes the mark code. 2 0.5 μm 2 ; The second texture structure is located on the substrate surface outside the marked area. The second texture structure includes a second raised structure and is a velvety structure.

2. The photovoltaic cell as described in claim 1, characterized in that, The first protruding structure has multiple sides, and the recessed structure on the first protruding structure is located on one side of the first protruding structure. In different first protruding structures, the sides of the first protruding structures having the recessed structure are parallel to each other.

3. The photovoltaic cell as described in claim 1, characterized in that, The first protrusion structure has multiple sides, and one side of the first protrusion structure has multiple independent recessed structures.

4. The photovoltaic cell as described in claim 1 or 3, characterized in that, The areas of the orthographic projections of the different recessed structures onto the side of the first protruding structure are different.

5. The photovoltaic cell as described in claim 1, characterized in that, Along the direction perpendicular to the side of the first protruding structure, the maximum depth of the recessed structure is 2μm~4μm.

6. A method for forming a photovoltaic cell, characterized in that, include: A substrate is provided, the surface of which includes a marking area for setting a marking code that marks product information of the photovoltaic cell; A first texture structure is formed in the marking area. The first texture structure includes a first raised structure, and the sides of the first raised structure have recessed structures. The recessed structures constitute the marking code. The first texture structure is a velvety texture. Multiple recessed structures on the sides of the first raised structures form the marking code for marking photovoltaic cell product information. The recessed structures are code dots that make up the marking code. The area of ​​the recessed structure projected onto the sides of the first raised structure is 0.1 μm. 2 ~0.5μm 2 ; A second texture structure is formed on the substrate surface outside the marked area. The second texture structure includes a second raised structure and is a velvety structure.

7. The method for forming a photovoltaic cell as described in claim 6, characterized in that, The steps of forming the first texture structure including the first protrusion structure include: An initial texture structure is formed in the marked area, the initial texture structure including a plurality of initial raised structures; The recessed structure is formed on the side of the initial protrusion structure located in the marked area, and the initial protrusion structure having the recessed structure is the first protrusion structure.

8. The method for forming a photovoltaic cell as described in claim 7, characterized in that, The step of forming the second texture structure including the second protrusion structure includes: While the initial texture structure is formed in the marking area, an initial texture structure including multiple initial protrusion structures is also formed on the substrate surface outside the marking area. The initial protrusion structure located on the substrate surface outside the marking area is the second protrusion structure.

9. The method for forming a photovoltaic cell as described in claim 7, characterized in that, Forming the recessed structure on the side of the initial protrusion structure includes: The side surface of the initial protrusion structure is laser-processed to form the recessed structure.

10. The method for forming a photovoltaic cell as described in claim 9, characterized in that, The ratio of the focal length of the laser processing to the beam diameter of the laser used in the laser processing is 0.9 to 1.

1.

11. The method for forming a photovoltaic cell as described in claim 10, characterized in that, The wavelength of the laser is 240nm~280nm, and the beam quality factor of the laser is 1~1.

2.

12. The method for forming a photovoltaic cell as described in claim 7 or 8, characterized in that, Forming the initial texture structure includes: performing a texturing process on the substrate surface to form the initial texture structure including the initial raised structure.

13. A photovoltaic module, characterized in that, include: A battery string, the battery string comprising a photovoltaic cell as described in any one of claims 1 to 5, or a photovoltaic cell formed by the method of forming a photovoltaic cell as described in any one of claims 6 to 12; An encapsulating film, the encapsulating film being used to cover the surface of the battery string; A cover plate for covering the surface of the encapsulating film away from the battery string.

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