Back contact solar cell and cell module

Abstract

The invention relates to the technical field of solar cells, and discloses a back contact solar cell and a cell module. The backlight surface of the substrate layer in the battery comprises first areas and second areas which are alternated; the first passivation contact structure is arranged in the first region; the second passivation contact structure is arranged in the second area, covers part of the first passivation contact structure and is provided with a first opening exposing part of the first passivation contact structure, and a plurality of first microstructures are formed in the first opening; comprising a part of the second passivation contact film layer remaining on the surface of the first passivation contact structure and / or a plurality of protruding structures formed by a part of the first passivation contact structure exposed by the first opening. The plurality of first microstructures in the first opening form light trapping difference for incident light with different wavelengths, the residual second passivation contact film layer plays a role in preventing hot spots, and when the first microstructures are formed in the first passivation contact structure, the thinned first passivation contact structure is beneficial to reducing parasitic absorption.

Description

Technical Field

[0001] This disclosure relates to the field of solar cell technology, specifically to back-contact solar cells and cell modules. Background Technology

[0002] Tunneling oxide passivated contact back contact cells (TBC cells) are considered the next generation of cells with the greatest potential for mass production after mainstream TOPCon cells, and have therefore attracted widespread attention. The back side of a TBC cell includes alternating p-regions and n-regions. The passivation contact film layer in the p-regions consists of a p-type doped polycrystalline silicon layer (p-poly), while the passivation contact film layer in the n-regions consists of an n-type doped polycrystalline silicon layer (n-poly). Compared to n-poly, p-poly films are weaker in both passivation and contact performance, and are difficult to significantly optimize from the manufacturing process perspective. Therefore, the performance of p-poly directly determines the cell efficiency.

[0003] Therefore, the industry has begun to explore using p-type doped amorphous silicon passivation contact films to replace p-poly films, thereby forming hybrid passivated back-contact solar cells. However, the specific structures and processes for hybrid passivated back-contact solar cells are not yet mature, the fabrication process is difficult, the economic benefits are low, and the cell performance and power generation efficiency need further improvement. Summary of the Invention

[0004] This disclosure provides a back-contact solar cell and a cell module to solve the problems of high difficulty in the fabrication process of existing back-contact solar cells, low economic efficiency, and difficulty in guaranteeing cell performance and power generation efficiency.

[0005] In a first aspect, this disclosure provides a back-contact solar cell, comprising: a substrate layer, a first passivation contact structure, a second passivation contact structure, a plurality of first microstructures, a first electrode, and a second electrode. The substrate layer includes a light-receiving surface and a back-lighting surface disposed opposite to each other, and the back-lighting surface includes alternating first regions and second regions. The first passivation contact structure is disposed in the first region. The second passivation contact structure is disposed in the second region and extends to cover the first passivation contact structure. The second passivation contact structure further has a first opening, the first opening exposing a portion of the first passivation contact structure. A plurality of first microstructures are formed within the first opening, the first microstructures including a portion of the second passivation contact film layer remaining on the surface of the first passivation contact structure and / or a plurality of protrusion structures formed by the portion of the first passivation contact structure exposed by the first opening. The first electrode is located within the first opening and is adapted to be connected to the first passivation contact structure, and the second electrode is located in the second region and is adapted to be connected to the second passivation contact structure.

[0006] Beneficial effects: In this disclosure, the first passivation contact structure covers the surface of a first region of the substrate layer, and the second passivation contact structure covers the surface of a second region of the substrate layer while also extending to both sides to cover a portion of the surface of the first passivation contact structure. Adjacent second passivation contact structures have a first opening on the first passivation contact structure, and a plurality of first microstructures are formed within the first opening. The first microstructure can be a residual portion of the second passivation contact film layer that has not been completely removed, or it can be a protrusion structure formed in the first passivation contact structure exposed in the first opening after the second passivation contact film layer has been completely removed. Alternatively, the first microstructure can include both of the above structures, and multiple first microstructures can be formed, each with a different size.

[0007] The first microstructure forms an uneven surface morphology within the first opening. Firstly, this helps to create differences in light-trapping performance for incident light of different wavelengths in the region where the first opening is located, improving the absorption and utilization of incident light of different wavelengths. Secondly, the first microstructure formed by the small amount of second passivation contact film layer remaining on the surface of the first passivation contact structure in the first opening region also helps to work synergistically with the first passivation contact structure to prevent hot spots, improving the reliability and lifespan of the battery. While the first microstructure formed after deeper removal from the first passivation contact structure does not involve hot spot prevention, the thinner first passivation contact structure helps to reduce parasitic absorption.

[0008] In one alternative implementation, a plurality of first microstructures are arranged periodically within a first opening.

[0009] Beneficial effects: The first microstructures are not randomly arranged, but periodically arranged in a defined direction at a certain interval. This periodic arrangement of the first microstructures has greater controllability during the fabrication process, avoiding the accumulation of first microstructures of different sizes in individual areas, which could cause an imbalance in the optical and electrical performance of that area or even the entire battery.

[0010] In one alternative implementation, the edge profile of the second passivated contact structure near the first opening is shaped into a first concave-convex structure.

[0011] Beneficial effects: The edge contour of the second passivation contact structure forms a tortuous and uneven morphological structure. The edge region is partially convex towards the first opening and partially concave towards the second passivation contact structure. On the one hand, it can increase the reflection and refraction of incident light, further improve the light trapping performance, and thus improve the bifaciality of the battery. On the other hand, the uneven contour structure can also increase the coverage area of ​​subsequent deposited films, such as transparent conductive films, and improve the overall performance of the battery.

[0012] In one alternative embodiment, the system further includes: a plurality of second microstructures formed in the second region, the second microstructures including protrusions formed by a portion of the base layer of the second region, the size of the second microstructures being larger than the size of the first microstructure.

[0013] Beneficial effects: In this disclosure, the first passivation contact film layer in the second region is completely removed to expose the surface of the substrate layer. Several second microstructures are formed in the exposed substrate layer of the second region. The second microstructures are usually pyramidal in shape and can be formed in multiple locations with varying sizes, but their size is larger than that of the first microstructure. This large-sized second microstructure is different from the small-sized microstructures formed by subsequent processes, thereby creating differences in light-trapping performance for incident light of different wavelengths in the second region, improving the absorption and utilization of incident light of different wavelengths, and effectively improving photoelectric conversion efficiency and power generation performance.

[0014] In one alternative implementation, several second microstructures are arranged periodically within the second region.

[0015] Beneficial effects: The multiple second microstructures are not randomly arranged, but periodically arranged at certain intervals in a defined direction. This periodic arrangement provides greater controllability during fabrication, preventing the accumulation of second microstructures of different sizes in individual areas, which could lead to imbalances in the optical and electrical performance of that area or even the entire battery. The multiple second microstructures can be divided into multiple groups, each group comprising several closely spaced second microstructures. Therefore, the periodic arrangement of these second microstructures can be achieved by periodically arranging multiple groups, which helps to create superior light-trapping performance in larger second regions.

[0016] In one alternative implementation, the size of the second microstructure ranges from 5 to 50 μm.

[0017] Beneficial effects: The size range of microstructures formed on the substrate layer of conventional batteries through processes such as wet cleaning is typically 1~2 μm. However, the size range of the second microstructure in this disclosure is much larger than that of the microstructures on the conventional substrate layer. Therefore, this disclosure combines the second microstructure with the conventional small-sized microstructure. First, it can achieve multi-scale light trapping, with the small-sized microstructure absorbing short-wavelength light and the large-sized second microstructure absorbing long-wavelength light, effectively broadening the absorption spectrum. Second, it can enhance light scattering, as the large-sized periodic second microstructure can more effectively scatter long-wavelength (red light, near-infrared) light, significantly extending the effective optical path length of light inside the battery. Third, it can improve passivation and contact performance, as the large-sized second microstructure provides a relatively gentle slope region to a certain extent, which is conducive to the uniform deposition of a high-quality passivation layer. Finally, the optimized total surface area and morphology of the second region can reduce the surface recombination rate, which is beneficial to improving the open-circuit voltage and fill factor.

[0018] In one alternative implementation, the edge contour of the first passivated contact structure near the second region is shaped into a second concave-convex structure.

[0019] Beneficial effects: The edge contour of the first passivation contact structure also forms a tortuous and uneven morphological structure. The edge area protrudes towards the isolation groove and is concave towards the first passivation contact structure. On the one hand, it can increase the reflection and refraction of incident light, further improve the light trapping performance, and thus improve the bifaciality of the battery. On the other hand, the uneven contour structure can also increase the coverage area of ​​subsequent deposited films, such as the second passivation contact film, and improve the overall performance of the battery.

[0020] In one alternative implementation, it further includes: A first transparent conductive layer and a second transparent conductive layer, wherein the first transparent conductive layer at least covers the first opening and the second transparent conductive layer at least covers the second region of the second passivation contact structure; a second opening is formed between the first transparent conductive layer and the second transparent conductive layer, and the second passivation contact structure is exposed in the second opening. Several third microstructures are located in the second opening. The third microstructures include a transparent conductive film layer remaining on the surface of the second passivated contact structure exposed in the second opening and / or a protrusion structure formed by a portion of the second passivated contact structure exposed in the second opening.

[0021] Beneficial effects: The first transparent conductive layer is connected to the first passivated contact structure, and the second transparent conductive layer is connected to the second passivated contact structure. They are electrically isolated from each other through the second opening. The first electrode is disposed on the first transparent conductive layer, enabling efficient output of electron carriers from the substrate layer to the first passivated contact structure, then to the first transparent conductive layer, and finally from the first electrode. The second electrode is disposed on the second transparent conductive layer, enabling efficient output of hole carriers from the substrate layer to the second passivated contact structure, then to the second transparent conductive layer, and finally from the second electrode. A third microstructure with an uneven morphology is formed on the surface exposed by the second opening. This can be a partially removed portion of the transparent conductive film layer, or a protrusion structure formed in the second passivated contact structure exposed by the second opening after complete removal of the transparent conductive film layer, or both. Multiple third microstructures of varying sizes can be formed, creating differences in light-trapping performance for incident light of different wavelengths in the second opening region. This improves the absorption and utilization of incident light of different wavelengths, thereby increasing photoelectric conversion efficiency and power generation efficiency.

[0022] In one alternative embodiment, the edge contour of the first transparent conductive layer and / or the second transparent conductive layer near the second opening is shaped into a third concave-convex structure.

[0023] Beneficial effects: The edges of the first and second transparent conductive layers form a tortuous and uneven morphological structure. Some of the edge regions protrude towards the second opening, while others are concave towards the first or second transparent conductive layer. This can increase the reflection and refraction of incident light, further improve the light trapping performance, thereby increasing the bifaciality of the battery and improving the overall performance of the battery.

[0024] Secondly, this disclosure also provides a back-contact solar cell module, including a plurality of the aforementioned back-contact solar cells.

[0025] Beneficial effects: The back-contact solar module has several of the aforementioned back-contact solar cells, and therefore has the aforementioned beneficial effects of the back-contact solar cells, exhibiting superior performance at the module end. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the specific embodiments of this disclosure or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of a back-contact solar cell according to an embodiment of the present disclosure; Figure 2 This is a partial structural diagram of a back-contact solar cell after the formation of a second passivated contact structure, according to an embodiment of the present disclosure. Figure 3 for Figure 2 A top view of the structure shown; Figure 4 This is a partial structural diagram of a back-contact solar cell after forming a second passivated contact structure, according to another embodiment of the present disclosure. Figure 5 for Figure 4 A top view of the structure shown; Figure 6 This is a top view of the back contact solar cell after the formation of the first passivated contact structure according to an embodiment of the present disclosure. Figure 7 This is a top-view scanning electron microscope diagram of a back-contact solar cell after the first passivated contact structure has been formed in an embodiment of the present disclosure. Figure 8 for Figure 7 An enlarged schematic diagram of the structure shown; Figure 9 for Figure 8 A further enlarged schematic diagram of the structure shown; Figure 10This is a partial structural diagram of a back-contact solar cell after the formation of a first transparent conductive layer and a second transparent conductive layer, according to an embodiment of the present disclosure. Figure 11 for Figure 10 A top view of the structure shown; Figure 12 This is a partial structural diagram of a back-contact solar cell according to an embodiment of the present disclosure after forming the first transparent conductive layer and the second transparent conductive layer. Figure 13 for Figure 12 A top view of the structure shown.

[0028] Explanation of reference numerals in the attached figures: 1. Base layer; 101. Light-receiving surface; 102. Backlight-receiving surface; A. First region; B. Second region; 2. First passivation contact structure; 201. Tunneling oxide layer; 202. Doped polysilicon layer; 203. Isolation groove; 204. Second concave-convex structure; 3. Second passivated contact structure; 301. Intrinsic amorphous silicon layer; 302. Doped amorphous silicon layer; 303. First opening; 304. First uneven structure; 401. First microstructure; 402. Second microstructure; 403. Third microstructure; 501, First electrode; 502, Second electrode; 601. First transparent conductive layer; 602. Second transparent conductive layer; 603. Second opening; 604. Third uneven structure; 7. Passivation anti-reflection layer. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0030] like Figures 1 to 13As shown, this disclosure provides a back-contact solar cell, including: a substrate layer 1, a first passivation contact structure 2, a second passivation contact structure 3, a plurality of first microstructures 401, a first electrode 501, and a second electrode 502. The substrate layer 1 includes a light-receiving surface 101 and a back-lighting surface 102 disposed opposite to each other. The back-lighting surface 102 includes an alternately disposed first region A and a second region B. The first passivation contact structure 2 is disposed in the first region A. The second passivation contact structure 3 is disposed in the second region B and extends to cover the first passivation contact structure 2. The second passivation contact structure 3 also has... There is a first opening 303, and the first passivation contact structure 2 is exposed in the first opening 303; a plurality of first microstructures 401 are formed in the first opening 303, the first microstructures 401 include a portion of the second passivation contact film layer remaining on the surface of the first passivation contact structure 2 and / or a plurality of protrusion structures formed by the portion of the first passivation contact structure 2 exposed in the first opening 303; a first electrode 501 is located in the first opening 303 and is adapted to be connected to the first passivation contact structure 2, and a second electrode 502 is located in the second region B and is adapted to be connected to the second passivation contact structure 3.

[0031] Specifically, the substrate 1 is a silicon substrate, and the first region A and the second region B on one side of the backlight surface 102 are along... Figure 1 The horizontal arrangement is shown as alternating. A first passivation contact structure 2 is formed on the first region A, and an isolation groove 203 exposing the second region B is provided between adjacent first passivation contact structures 2. For example, the first passivation contact structure 2 includes a stacked tunneling oxide layer 201 and a doped polycrystalline silicon layer 202, and the second passivation contact structure 3 includes a stacked intrinsic amorphous silicon layer 301 and a doped amorphous silicon layer 302. That is, the back contact solar cell of this disclosure can be a hybrid passivation back contact solar cell including a first passivation contact structure 2 of the TOPCon cell type and a second passivation contact structure 3 of the heterojunction cell type. In the first passivation contact structure 2 and the second passivation contact structure 3, one of them is p-type doped and the other is n-type doped. In this disclosure, the first passivation contact structure 2 is n-type doped and the second passivation contact structure 3 is p-type doped as an example. The first electrode 501 and the second electrode 502 are metal grid lines that collect and export carriers in different doped regions. For example, the first electrode 501 is connected to the n-type first passivation contact structure 2 to realize the collection and export of electron carriers, and the second electrode 502 is connected to the p-type second passivation contact structure 3 to realize the collection and export of hole carriers.

[0032] The first passivation contact structure 2 covers the surface of the first region A, and the second passivation contact structure 3 covers the surface of the second region B. At the same time, it extends to both sides to cover part of the surface of the first passivation contact structure 2. The adjacent second passivation contact structure 3 has a first opening 303 on the first passivation contact structure 2 to avoid short circuit conduction. Specifically, the forming of the second passivation contact structure 3 typically includes: firstly, forming a second passivation contact film layer on one side of the backlight surface 102, the second passivation contact film layer covering the surface of the second region B and the first passivation contact structure 2; then removing a portion of the second passivation contact film layer located on the first passivation contact structure 2, thereby forming a first opening 303 and a second passivation contact structure 3, the first opening 303 exposing a portion of the first passivation contact structure 2, the second passivation contact structure 3 covering the second region B and extending to cover a portion of the first passivation contact structure 2, and forming a first microstructure 401 within the first opening 303, so that the surface exposed by the first opening 303 presents an uneven morphology. The first microstructure 401 disclosed herein is non-pyramid shaped, such as hemispherical, columnar, etc., with no obvious sharp parts, which helps in the uniform deposition of subsequent transparent conductive film layers and improves carrier transport and collection performance.

[0033] More importantly, the first microstructure 401 of this disclosure can be as follows: Figure 2 and Figure 3 The residual portion of the second passivation contact film layer shown is due to the presence of a phosphosilicate glass (PSG) layer as a surface protective layer on the surface of the first passivation contact structure 2. Therefore, residual film layers may remain in areas with lower laser spot energy. Alternatively, it could be as follows: Figure 4 and Figure 5After the second passivation contact film layer is completely removed, the protruding structure formed in the first passivation contact structure 2 exposed by the first opening 303 can be achieved by removing a deeper film layer through continuous multi-round laser cyclic marking or repeated marking with a single spot; or the first microstructure 401 can also include the above two structures. Of course, regardless of whether the first microstructure 401 is a residual part of the second passivation contact film layer or a protruding structure formed by the first passivation contact structure 2 itself, multiple protrusions can be formed, and their sizes can vary. First, the uneven morphology formed in this way helps to create differences in the light-trapping performance of incident light of different wavelengths in the region where the first opening 303 is located, thereby improving the absorption and utilization of incident light of different wavelengths. Secondly, the first microstructure 401 formed by the small amount of second passivation contact film layer remaining on the surface of the first passivation contact structure 2 in the first opening 303 region also helps to work synergistically with the first passivation contact structure 2 to prevent hot spots, thereby improving the reliability and service life of the battery. Although the first microstructure 401 formed in the first passivation contact structure 2 after being removed to a greater depth does not involve the effect of preventing hot spots, the thinner first passivation contact structure 2 helps to reduce parasitic absorption. Moreover, since the second passivation contact structure 3 of the back contact solar cell of this disclosure uses an amorphous silicon thin film, and based on the high temperature resistance of the amorphous silicon thin film, the subsequent electrode paste is usually a low temperature paste, so there is no need to worry too much about the risk of the thinner first passivation contact structure 2 being burned through by the paste.

[0034] In one embodiment, the aforementioned plurality of first microstructures 401 are arranged periodically within the first opening 303. That is, the plurality of first microstructures 401 are not randomly arranged, but are arranged periodically in a defined direction at a certain interval, such as being evenly spaced along the length or width of the first opening 303 at a first interval. This periodic arrangement provides greater controllability during the fabrication process, avoiding the accumulation of first microstructures 401 of different sizes in individual areas, which could cause an imbalance in the optical and electrical performance of that area or even the entire battery.

[0035] For example, a portion of the second passivation contact film layer located on the first passivation contact structure 2 can be removed by a first laser process to form the first opening 303. Since lasers are easily affected by factors such as dust, temperature, external vibration, and device aging during operation, resulting in uneven energy distribution of the laser spot, conventional laser processes require periodic reshaping of the laser's diffraction optical element (DOE) and strict control of the overlap rate between laser spots. For example, the overlap rate is generally required to be greater than or equal to 50% to obtain a laser spot with more uniform energy distribution, ensuring the effectiveness of film removal and surface smoothness. However, such a laser process has the advantage of greater energy loss for the same area, and such a large laser spot overlap rate can easily damage the relevant film layers of the battery, making the process quite difficult. However, the formation of the first microstructure 401 in this disclosure can take advantage of the uneven energy distribution of the laser spot. On the one hand, such a first laser process helps to leave a certain residue in the removed second passivation contact film layer, or to form an uneven surface morphology in the deeper first passivation contact structure 2, thereby forming the first microstructure 401 in the first opening 303. The limitations of the first laser process are turned into advantages, and the overlap rate of the laser spot can be reduced to less than 10%, reducing energy loss and damage to the film layer. On the other hand, since laser marking is usually periodic, it helps to form the periodically arranged first microstructure 401 in this disclosure without the need to introduce other processing steps, and the process is compatible.

[0036] In one embodiment, such as Figure 3 and Figure 5 As shown, the edge contour of the second passivated contact structure 3 near the first opening 303 is formed into a first concave-convex structure 304. Based on the above-mentioned first laser process for forming the first opening 303, in this process, the edge contour of the second passivated contact structure 3 is also partially etched by the laser spot, thereby forming a tortuous and concave-convex morphological structure. That is, the edge region partially protrudes towards the first opening 303 and partially concave towards the second passivated contact structure 3. On the one hand, this can increase the reflection and refraction of incident light, further improving the light trapping performance, thereby increasing the bifaciality of the battery; on the other hand, the uneven contour structure can also increase the coverage area of ​​subsequent deposited films, such as transparent conductive films, improving the overall performance of the battery.

[0037] In one embodiment, such as Figure 1 , Figures 6 to 9 As shown, the aforementioned back-contact solar cell further includes: a plurality of second microstructures 402 formed in the second region B. The second microstructures 402 include protrusions formed by a portion of the substrate layer 1 of the second region B. The size of the second microstructures 402 is larger than the size of the first microstructures 401.

[0038] It is understood that the forming steps of the first passivated contact structure 2 may include: firstly, covering at least the entire backlight surface 102 with a first passivated contact film layer, that is, covering the first region A and the second region B of the backlight surface 102. Of course, the first passivated contact film layer may also cover all surfaces of the entire substrate layer 1, including the light-receiving surface 101, the backlight surface 102, and the side surfaces; then, using a process such as a second laser, directly removing the first passivated contact film layer located in the second region B, forming the first passivated contact structure 2 on the first region A, and forming an isolation groove 203 exposing the second region B between adjacent first passivated contact structures 2, such as... Figure 1 As shown.

[0039] The second laser process disclosed herein completely removes the first passivation contact film layer of the second region B. This is because there is no surface protective layer on the surface of the substrate layer 1, thus the first passivation contact film layer of the second region B can be completely removed, exposing the surface of the substrate layer 1. During this process, the non-uniform energy distribution of the laser spot is also utilized to form several second microstructures 402 in the substrate layer 1 of the second region B exposed by the isolation groove 203. The second microstructures 402 are typically pyramidal in shape, and multiple structures can be formed of varying sizes, but their dimensions are larger than the dimensions of the first microstructure 401. This large-sized second microstructure 402 distinguishes it from the small-sized microstructures formed by subsequent processes. The small-sized microstructures are... Figure 6 Other microstructures in the second region shown in the figure create differences in light-trapping performance for incident light of different wavelengths in the second region B, thereby improving the absorption and utilization of incident light of different wavelengths and effectively enhancing photoelectric conversion efficiency and power generation performance.

[0040] In one embodiment, such as Figures 6 to 9 As shown, several second microstructures 402 are arranged periodically within the second region B.

[0041] Similarly, the second microstructures 402 can be arranged not randomly, but periodically in a defined direction at a certain interval, such as uniformly spaced along the length or width of the isolation groove 203 at a second interval. This periodic arrangement provides greater controllability during fabrication, preventing the accumulation of second microstructures 402 of different sizes in individual areas, which could lead to imbalances in the optical and electrical performance of that area or even the entire battery. Furthermore, as... Figures 7 to 9 As shown, the number of second microstructures 402 can be divided into multiple groups of second microstructures. Each group of second microstructures includes multiple second microstructures 402 that are close to each other. Therefore, the periodic arrangement of the number of second microstructures 402 can be arranged in multiple groups of second microstructures, which helps to form better light-trapping performance in the second region B with a larger area.

[0042] In one embodiment, the size of the second microstructure 402 described above ranges from 5 to 50 μm.

[0043] It is known that the size range of microstructures formed on the substrate 1 in conventional batteries through processes such as wet cleaning is typically 1~2 μm, while the size range of the second microstructure 402 in this disclosure is much larger than the size range of microstructures on the conventional substrate 1, such as... Figures 6 to 9 As shown. Therefore, the second region B surface in this disclosure has both a second microstructure 402 and conventional small-sized microstructures. First, it can achieve multi-scale light trapping, with the small-sized microstructure absorbing short-wavelength light and the large-sized second microstructure 402 absorbing long-wavelength light, effectively broadening the absorption spectrum. Second, it can enhance light scattering, as the large-sized periodic second microstructure 402 can more effectively scatter long-wavelength (red light, near-infrared) light, significantly extending the effective optical path of light inside the battery. Third, it can improve passivation and contact performance, as the large-sized second microstructure 402 provides a relatively gentle slope region to a certain extent, which is conducive to the uniform deposition of a high-quality passivation layer. Finally, the optimized total surface area and morphology of the second region B can reduce the surface recombination rate, which is beneficial to improving the open-circuit voltage and fill factor.

[0044] In one embodiment, such as Figure 6 As shown, the edge contour of the first passivated contact structure 2 near the second region B is shaped into a second concave-convex structure 204.

[0045] Similarly, based on the process of forming the isolation groove 203 using the second laser process, during this process, the edge contour of the first passivation contact structure 2 is also partially etched by the laser spot, thus forming a tortuous and uneven morphological structure. That is, the edge area partially protrudes towards the isolation groove 203 and partially concave towards the first passivation contact structure 2. On the one hand, this can increase the reflection and refraction of incident light, further improve the light trapping performance, and thus improve the bifaciality of the battery. On the other hand, the uneven contour structure can also increase the coverage area of ​​subsequent deposited films, such as the second passivation contact film, and improve the overall performance of the battery.

[0046] In one embodiment, such as Figure 1 , Figures 10 to 13As shown, the back-contact solar cell further includes: a first transparent conductive layer 601, a second transparent conductive layer 602, and a plurality of third microstructures 403. The first transparent conductive layer 601 at least covers the first opening 303, and the second transparent conductive layer 602 at least covers the second passivated contact structure 3 in the second region B. A second opening 603 is formed between the first transparent conductive layer 601 and the second transparent conductive layer 602, and the second passivated contact structure 3 is exposed in the second opening 603. A plurality of third microstructures 403 are located in the second opening 603. The third microstructures 403 include a transparent conductive film layer remaining on the surface of the second passivated contact structure 3 exposed in the second opening 603 and / or a protrusion structure formed by the portion of the second passivated contact structure 3 exposed in the second opening 603.

[0047] Similarly, the forming steps of the first transparent conductive layer 601 and the second transparent conductive layer 602 may include: firstly, covering the entire backlight surface 102 with a transparent conductive film layer, which covers the second passivation contact structure 3 and the first opening 303; then removing a portion of the transparent conductive film layer located on the second passivation contact structure 3 to form the second opening 603, the first transparent conductive layer 601, and the second transparent conductive layer 602. The second opening 603 exposes a portion of the second passivation contact structure 3 extending and covering the first passivation contact structure 2. The first transparent conductive layer 601 and the second transparent conductive layer 602 are located on both sides of the second opening 603, such as... Figure 1 As shown, the first transparent conductive layer 601 covers the surface of the first passivated contact structure 2 exposed by the first opening 303, the sidewall of the second passivated contact structure 3 exposed by the first opening 303, and part of the surface of the second passivated contact structure 3 located in the first region A; the second transparent conductive layer 602 covers the second passivated contact structure 3 in the second region B, and may also cover part of the second passivated contact structure 3 in the first region A depending on the opening position of the second opening 603.

[0048] For example, the initially deposited transparent conductive film layer covers at least one side of the entire backlight surface 102, that is, the first passivation contact structure 2 and the second passivation contact structure 3 cover one side of the backlight surface 102. The transparent conductive film layer can be selected from TCO-based materials, such as indium tin oxide (ITO) material, or fluorine-doped tin oxide (FTO) material, or aluminum-doped zinc oxide (AZO) material, etc. The initially deposited transparent conductive film layer is truncated on the second passivation contact structure 3, forming a second opening 603 that electrically isolates the first transparent conductive layer 601 (connected to the first passivation contact structure 2) and the second transparent conductive layer 602 (connected to the second passivation contact structure 3). A first electrode 501 is disposed on the first transparent conductive layer 601, enabling efficient output of electron carriers from the substrate 1 to the first passivation contact structure 2, then to the first transparent conductive layer 601, and finally from the first electrode 501. A second electrode 502 is disposed on the second transparent conductive layer 602, enabling efficient output of hole carriers from the substrate 1 to the second passivation contact structure 3, then to the second transparent conductive layer 602, and finally from the second electrode 502. Simultaneously, a third microstructure 403 with an uneven morphology is formed on the surface exposed by the second opening 603. The third microstructure 403 can be, for example,... Figure 10 and Figure 11 The partially removed transparent conductive film layer shown can also be as follows: Figure 12 and Figure 13 The diagram shows a raised structure formed in the second passivated contact structure 3 exposed after the transparent conductive film layer is completely removed, or both structures may be included. Furthermore, the raised structure in this region may also include a portion of the borosilicate glass layer (BSG layer) located on the surface of the second passivated contact structure 3. Of course, both the residual transparent conductive film layer and the raised structure formed in the second passivated contact structure 3 can be multiple and vary in size, thereby creating differences in light-trapping performance for incident light of different wavelengths in the second opening 603 region. This improves the absorption and utilization of incident light of different wavelengths, thereby increasing photoelectric conversion efficiency and power generation efficiency.

[0049] Furthermore, the dimensions of the third microstructure 403 and the first microstructure 401 are similar, and both are smaller than the dimensions of the second microstructure 402.

[0050] In one embodiment, the removal of the portion of the transparent conductive film layer on the second passivation contact structure 3 may be performed using a third laser process or a wet etching process.

[0051] That is, there are two ways to partially remove the transparent conductive film layer to form the first transparent conductive layer 601 and the second transparent conductive layer 602 with spacing. One is the third laser process, and the other is the wet process using etching paste. The third microstructure 403 is formed by retaining part of the residual transparent conductive film layer. This can be obtained by the above two methods. However, the protrusion structure formed in the second passivated contact structure 3 exposed by the second opening 603 after the transparent conductive film layer is completely removed can only be obtained by the third laser process.

[0052] The aforementioned etching paste includes: acidic etchant, conductive filler, solvent, rheology modifier, and other additives. The acidic etchant can be phosphoric acid, which provides hydrogen ions to react with TCO-based materials, dissolving them and achieving selective etching of the TCO-based materials while avoiding damage to the underlying materials. The conductive filler can be graphite, carbon black, or other materials that provide conductivity, assist in electrochemical etching, and provide rheological properties. The solvent can be water or an organic solvent, used to dissolve other components to form a paste-like material while ensuring the stability of the cap and suitable printability. The rheology modifier can be a thixotropic agent or a thickener formed from a specific polymer, adjusting the viscosity and thixotropy of the paste to facilitate printing and maintain pattern stability, preventing pattern diffusion after printing and ensuring the accuracy of the etched lines. Other additives include defoamers, adhesion promoters, degassing agents, etc., used to improve process performance and enhance stability and yield during manufacturing.

[0053] In one embodiment, such as Figure 11 and Figure 13 As shown, the edge contours of the first transparent conductive layer 601 and / or the second transparent conductive layer 602 near the second opening 603 are formed into a third concave-convex structure 604.

[0054] Similarly, based on the third laser process or wet etching process, the edge contours of the first transparent conductive layer 601 and the second transparent conductive layer 602 are also partially etched by the laser spot or wet solution, thus forming a tortuous and uneven morphological structure. That is, the edge area partially protrudes towards the second opening 603 and partially concave towards the first transparent conductive layer 601 or the second transparent conductive layer 602. On the one hand, this can increase the reflection and refraction of incident light, further improve the light trapping performance, thereby increasing the bifaciality of the battery and improving the overall performance of the battery.

[0055] The first, second, and third laser processes described above can use different parameters to ensure the accuracy and specificity of removing different film layers; alternatively, the same parameters can be used to simplify the fabrication process. By using the same parameters to act on the differences in different film layers to form microstructures of different sizes, it is possible to obtain multiple microstructures of different sizes in different regions on one side of the backlight surface 102, which greatly enhances the utilization rate of light of different wavelengths and thus significantly improves the photoelectric conversion efficiency.

[0056] like Figure 1 As shown, the back-contact solar cell of this disclosure also has a passivation and antireflection layer 7 on the textured surface of the light-receiving surface 101 of the substrate layer 1. The passivation and antireflection layer 7 can be aluminum oxide, silicon nitride, or a stacked structure of the two, to enhance the light absorption and passivation performance on the light-receiving surface 101.

[0057] This disclosure also provides a back-contact solar cell module, including a plurality of the aforementioned back-contact solar cells, having all the beneficial effects of the aforementioned back-contact solar cells.

[0058] Further functional descriptions of the above structures are the same as those of the corresponding embodiments described above, and will not be repeated here.

[0059] Although embodiments of the present disclosure have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present disclosure, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A back-contact solar cell, characterized in that, include: The substrate (1) includes a light-receiving surface (101) and a backlight surface (102) disposed opposite to each other. The backlight surface (102) includes a first region (A) and a second region (B) disposed alternately. A first passivated contact structure (2) is disposed in the first region (A); The second passivation contact structure (3) is disposed in the second region (B) and extends to cover the first passivation contact structure (2). The second passivation contact structure (3) also has a first opening (303), which exposes a portion of the first passivation contact structure (2). A plurality of first microstructures (401) are formed in the first opening (303). The first microstructures (401) include a portion of the second passivation contact film layer remaining on the surface of the first passivation contact structure (2) and / or a plurality of protrusions formed by the portion of the first passivation contact structure (2) exposed by the first opening (303). A first electrode (501) and a second electrode (502), wherein the first electrode (501) is located within the first opening (303) and is adapted to be connected to the first passivation contact structure (2), and the second electrode (502) is located in the second region (B) and is adapted to be connected to the second passivation contact structure (3).

2. The back-contact solar cell according to claim 1, characterized in that, Several of the first microstructures (401) are arranged periodically within the first opening (303).

3. The back-contact solar cell according to claim 1, characterized in that, The second passivated contact structure (3) is shaped into a first concave-convex structure (304) near the edge contour of the first opening (303).

4. The back-contact solar cell according to claim 1, characterized in that, Also includes: A plurality of second microstructures (402) are formed within the second region (B), the second microstructures (402) including protrusions formed by a portion of the base layer (1) of the second region (B), the size of the second microstructures (402) being larger than the size of the first microstructures (401).

5. The back-contact solar cell according to claim 4, characterized in that, Several of the second microstructures (402) are arranged periodically within the second region (B).

6. The back-contact solar cell according to claim 4, characterized in that, The size range of the second microstructure (402) is 5~50 μm.

7. The back-contact solar cell according to claim 4, characterized in that, The first passivated contact structure (2) is shaped into a second concave-convex structure (204) near the edge contour of the second region (B).

8. The back-contact solar cell according to any one of claims 1-7, characterized in that, Also includes: A first transparent conductive layer (601) and a second transparent conductive layer (602), wherein the first transparent conductive layer (601) at least covers the first opening (303), and the second transparent conductive layer (602) at least covers the second passivation contact structure (3) of the second region (B); a second opening (603) is formed between the first transparent conductive layer (601) and the second transparent conductive layer (602), and the second opening (603) exposes a portion of the second passivation contact structure (3); A plurality of third microstructures (403) are located in the second opening (603), the third microstructures (403) including a transparent conductive film layer remaining on the surface of the second passivation contact structure (3) exposed by the second opening (603) and / or a protrusion structure formed by the portion of the second passivation contact structure (3) exposed by the second opening (603).

9. The back-contact solar cell according to claim 8, characterized in that, The first transparent conductive layer (601) and / or the second transparent conductive layer (602) are shaped into a third concave-convex structure (604) near the edge contour of the second opening (603).

10. A back-contact solar cell module, characterized in that, Includes the back-contact solar cell according to any one of claims 1-9.

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