Solar cell, preparation method thereof and photovoltaic module

Abstract

The invention provides a solar cell, relates to the field of photovoltaic technology, and aims to improve color quality. The solar cell includes a substrate, a first stack structure, and a second stack structure. The substrate comprises a first surface and a second surface which are opposite, and the first surface is provided with a plurality of tower-shaped structures. The first stack structure is stacked on the first surface, the first stack structure comprises at least one first antireflection film, and the material of the first antireflection film comprises silicon nitride. The second stack structure is arranged on the side, away from the substrate, of the first stack structure in a stacked mode, the second stack structure comprises at least one second antireflection film, and the second antireflection film is made of silicon oxynitride. Wherein the reflectivity of the solar cell to light with the wavelength of 400-460 nm is smaller than 10%, the L value of the solar cell in a Lab color model meets the condition that L is larger than or equal to 8 and smaller than or equal to 10.5, the a value of the solar cell in the Lab color model meets the condition that a is larger than or equal to 2.5 and smaller than or equal to 4.5, and b is larger than or equal to-14 and smaller than or equal to-3.

Description

Technical Field

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

[0002] Currently, when tunnel oxide passivated contact (TOPCon) cells are used in aesthetic components, color differences are prone to occur, resulting in a decrease in the color quality of the cells and failing to meet aesthetic requirements. Summary of the Invention

[0003] This application proposes a solar cell and its preparation method, as well as a photovoltaic module, with the aim of improving the color quality of solar cells.

[0004] On one hand, a solar cell is provided, comprising a substrate, a first stacked structure, and a second stacked structure. The substrate includes opposing first and second surfaces, with a plurality of tower-like structures disposed on the first surface. The first stacked structure is stacked on the first surface and includes at least one first antireflective film made of silicon nitride. The second stacked structure is stacked on the side of the first stacked structure away from the substrate and includes at least one second antireflective film made of silicon oxynitride. The solar cell exhibits a reflectivity of less than 10% for light with wavelengths between 400 nm and 460 nm, and in the Lab color model, the L value of the solar cell satisfies 8 ≤ L ≤ 10.5, the a value satisfies 2.5 ≤ a ≤ 4.5, and the b value satisfies -14 ≤ b ≤ -3.

[0005] In some embodiments, along a direction parallel to the second surface, the number of tower-like structures per square centimeter on the first surface is greater than or equal to 190,000. Along a direction perpendicular to the second surface, the thickness ratio of the first stack structure to the second stack structure is greater than or equal to 1.5, the refractive index of the first stack structure is greater than or equal to 2.15, and the refractive index of the second stack structure is less than or equal to 2.0.

[0006] In some embodiments, the first stack structure includes a plurality of stacked first antireflective films along a direction perpendicular to the second surface. The refractive indices of the plurality of first antireflective films decrease sequentially along a direction away from the substrate.

[0007] In some embodiments, the plurality of first antireflective films include a first bottom antireflective film closest to the substrate and a first top antireflective film located on the side of the first bottom antireflective film away from the substrate. The silicon-to-nitrogen ratio in the first bottom antireflective film is 1:5 to 1:2, and the silicon-to-nitrogen ratio in the first top antireflective film is 1:15 to 1:6.

[0008] In some embodiments, the plurality of first antireflective films include a first bottom antireflective film closest to the substrate, and a first top antireflective film located on the side of the first bottom antireflective film away from the substrate. The thickness ratio of the first bottom antireflective film to the first top antireflective film is 0.16 to 1.

[0009] In some embodiments, the second stack structure includes a plurality of stacked second antireflective films along a direction perpendicular to the second surface. The refractive indices of the plurality of second antireflective films decrease sequentially along a direction away from the substrate.

[0010] In some embodiments, the plurality of second antireflective films include a second bottom antireflective film closest to the substrate, and a second top antireflective film located on the side of the second bottom antireflective film away from the substrate. The silicon-to-nitrogen ratio in the second bottom antireflective film is 1:10 to 1:4, and the silicon-to-oxygen ratio is 1:6 to 1:4. The silicon-to-nitrogen ratio in the second top antireflective film is 1:8 to 1:4, and the silicon-to-oxygen ratio is 1:10 to 1:6.

[0011] In some embodiments, the thickness of the overall structure formed by the first stack structure and the second stack structure ranges from 65 nm to 85 nm, and the refractive index is 2.08 to 2.15.

[0012] In some embodiments, the width of the base of the tower-like structure is 1.4 μm to 1.8 μm, and the height of the tower-like structure is 0.8 μm to 1.2 μm. The reflectivity of the first surface is 8% to 10%.

[0013] In some embodiments, the solar cell further includes a passivation layer disposed between the substrate and the first stack structure, the material of the passivation layer including aluminum oxide, and the thickness variation rate of the passivation layer being less than or equal to 3%.

[0014] On the other hand, a method for fabricating a solar cell is also provided, the method comprising: providing a substrate, the substrate including opposing first and second surfaces; texturing the substrate to form a plurality of tower-like structures on the first surface; forming a first stack structure on the first surface, the first stack structure including at least one first antireflective film, the material of the first antireflective film including silicon nitride; forming a second stack structure on the side of the first stack structure away from the substrate, the second stack structure including at least one second antireflective film, the material of the second antireflective film including silicon oxynitride; Among them, the reflectivity of the solar cell to light with wavelengths of 400nm~460nm is less than 10%, and the L value of the solar cell in the Lab color model satisfies 8≤L≤10.5, the a value satisfies 2.5≤a≤4.5, and the b value satisfies -14≤b≤-3.

[0015] In some embodiments, along a direction parallel to the second surface, the number of tower-like structures per square centimeter on the first surface is greater than or equal to 190,000. Along a direction perpendicular to the second surface, the thickness ratio of the first stack structure to the second stack structure is greater than or equal to 1.5, the refractive index of the first stack structure is greater than or equal to 2.15, and the refractive index of the second stack structure is less than or equal to 2.0.

[0016] In some embodiments, the alkali content in the texturing bath solution is 0.5% to 1%, and the additive content is 0.2% to 0.6%. The texturing time is 300s to 400s.

[0017] In some embodiments, a plasma-enhanced chemical vapor deposition process is used to form a first stack structure and a second stack structure.

[0018] In some embodiments, after texturing the substrate and before forming the first stack structure, the above preparation method further includes: forming a passivation layer on the first surface using an atomic layer deposition process. The material of the passivation layer includes aluminum oxide, and the thickness variation rate of the passivation layer is less than or equal to 3%.

[0019] On the other hand, a photovoltaic module is also provided, which includes a plurality of solar cells as described in the above embodiments, and the plurality of solar cells are electrically connected.

[0020] In this embodiment, the solar cell includes a substrate, a first stacked structure, and a second stacked structure. The substrate includes a first surface and a second surface facing each other, with the first surface serving as the light-receiving surface. Along a direction parallel to the second surface, the number of tower-like structures per square centimeter on the first surface is greater than or equal to 190,000. Compared to related technologies, the first surface in this application has a higher texturing density and better light-trapping effect, reducing the probability of light escape and decreasing the reflectivity of the first surface, thereby reducing the overall brightness of the solar cell and lowering the risk of graying.

[0021] Based on increasing the texturing density of the first surface, a first stacked structure is stacked on the first surface, the first stacked structure including at least one first antireflective film. A second stacked structure, including at least one second antireflective film, is then stacked on the side of the first stacked structure away from the substrate. The first and second stacked structures cooperate to form an antireflective film. The first surface is uneven due to the tower-like structure, and the first and second stacked structures are formed on the first surface, making their surfaces also uneven. This improves the light-trapping effect of the first and second stacked structures and reduces the reflectivity of the antireflective film.

[0022] It is understandable that the refractive index of the first stack structure is greater than that of the second stack structure. By setting the thickness ratio of the first stack structure to the second stack structure to be greater than or equal to 1.5, the thickness of the first stack structure with a higher refractive index accounts for a larger proportion in the anti-reflection film layer, avoiding the appearance of cells with excessively low refractive indices, which is beneficial to reducing the overall reflectivity of the solar cell.

[0023] Furthermore, the refractive index of the first stacked structure is greater than or equal to 2.15, and the refractive index of the second stacked structure is less than or equal to 2.0, so that the refractive indices of the first stacked structure and the second stacked structure have a difference of at least 0.15, ensuring that the overall reflectivity of the solar cell is low, especially reducing the reflectivity of light (blue light) in the wavelength range of 400nm~460nm. The reflectivity can be reduced to below 10%, thereby reducing the risk of the solar cell turning blue and thus improving the color quality of the solar cell.

[0024] In related technologies, the L value (brightness) of solar cells in the Lab color model satisfies 9 ≤ L ≤ 15. In the embodiments of this application, the L value of solar cells in the Lab color model satisfies 8 ≤ L ≤ 10.5. The L value of the solar cells in this application is even lower, making the color closer to black. Furthermore, in related technologies, the a value of solar cells in the Lab color model satisfies 2.5 ≤ a ≤ 7. In the embodiments of this application, the a value of solar cells in the Lab color model satisfies 2.5 ≤ a ≤ 4.5. The a value of the solar cells in this application is smaller and closer to 0, resulting in less red and a color closer to black. Additionally, in related technologies, the b value of solar cells in the Lab color model satisfies -18 ≤ b ≤ -12. In the embodiments of this application, the b value of solar cells in the Lab color model satisfies -14 ≤ b ≤ -3. The b value of the solar cells in this application is larger and closer to 0, resulting in less blue and a color closer to black. Therefore, the appearance color of the solar cells in this application is closer to black, which better meets aesthetic requirements. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in this application, the accompanying drawings used in some embodiments of this application will be briefly described below. Obviously, the drawings described below are only drawings of some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams and are not actual dimensions of the products or actual processes of the methods involved in the embodiments of this application.

[0026] Figure 1 This is a schematic diagram of the structure of a solar cell in related technologies; Figure 2This is a measured diagram of the textured surface structure of solar cells in related technologies; Figure 3 This is a schematic diagram of the structure of the solar cell provided in this application; Figure 4 The above is a measured diagram of the textured surface structure of the solar cell provided in this application. Figures 5-7 Box plot comparing the textured surface data of the solar cell provided in this application with that of solar cells in related technologies; Figure 8 A comparison of reflectance test results of multiple antireflection coatings provided in this application and antireflection coatings in related technologies under illumination of different wavelengths of light; Figure 9 A comparison of the transmittance test results of the multiple antireflection coatings provided in this application and antireflection coatings in related technologies under illumination of different wavelengths of light; Figure 10 A comparison of the absorption rate test results of the multiple antireflection coatings provided in this application and the antireflection coatings in related technologies under illumination of different wavelengths of light; Figure 11 A comparison chart showing the reflectivity test results of the solar cell provided in this application and solar cells in related technologies under illumination of different wavelengths of light; Figure 12 A comparison chart showing the transmittance test results of the solar cell provided in this application and solar cells in related technologies under different wavelengths of light. Figure 13 The comparison chart of the absorption rate test results of the solar cells provided in this application and the solar cells in related technologies under different wavelengths of light; Figures 14-16 Lab box plot comparing the solar cell provided in this application with solar cells in related technologies; Figure 17 A schematic diagram of the Lab color model; Figure 18 A flowchart illustrating the fabrication process of the solar cell provided in this application; Figures 19-24 A diagram illustrating the fabrication steps of the solar cell provided in this application; Figure 25 This is a schematic diagram of the structure of the photovoltaic module provided in this application. Detailed Implementation

[0027] The technical solutions in some embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application are within the scope of protection of this application.

[0028] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as open and encompassing, that is, "including, but not limited to".

[0029] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this application, unless otherwise stated, "a plurality of" means two or more.

[0030] In describing some embodiments, the term "connection" and its derivative expressions may be used. The term "connection" should be interpreted broadly; for example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium. For example, in describing some embodiments, the term "connection" may be used to indicate that two or more components have direct physical or electrical contact with each other.

[0031] In addition, the use of “based on” implies openness and inclusivity, because processes, steps, calculations or other actions “based on” one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0032] This document describes exemplary embodiments with reference to cross-sectional views, which are intended as idealized exemplary drawings. In the drawings, the thickness of the layers and the area of ​​the regions are enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to, for example, manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but rather include shape deviations caused, for example, by manufacturing processes. For example, etched areas shown as rectangular would typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of the areas of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0033] Figure 1 This is a schematic diagram of the structure of a solar cell in related technologies.

[0034] See Figure 1In related technologies, the solar cell 100' is a tunnel oxide passivated contact (TOPCon) cell. The substrate 1' of the solar cell 100' includes a first surface 101' and a second surface 102', with the first surface 101' serving as the light-receiving surface. Multiple tower-like structures 10' are disposed on the first surface 101', and these tower-like structures 10' are textured structures on the first surface 101'. The reflectivity of the first surface 101' is 9%~11%.

[0035] Figure 2 This is a measured diagram of the textured surface structure of solar cells in related technologies.

[0036] See Figure 1 and Figure 2 Each tower-like structure 10' has a width ranging from 1.6 μm to 2.2 μm and a height ranging from 1.0 μm to 2.0 μm. The flocking density on the first surface 101' is greater than 120,000 / cm³. 2 That is, on the first surface 101', there are at least 120,000 tower-like structures 10' per square centimeter. Because the texturing density on the first surface 101' is low, the reflectivity and refractive index of light shining on the first surface 101' are high, that is, the probability of light escaping is high, which increases the overall brightness of the solar cell 100', thereby leading to the risk of the solar cell 100' turning gray.

[0037] This process typically employs an alkaline solution for etching to form multiple tower-like structures 10'. The alkaline solution contains 0.5%–1% alkali and 0.2%–0.6% additives. The substrate 1' reacts with this alkaline solution for 300–400 seconds to complete the texturing of the first surface 101'.

[0038] See also Figure 1 An antireflective coating is disposed on the first surface 101', the antireflective coating comprising a silicon nitride layer 2', a silicon oxynitride layer 3', and a silicon oxide layer 300 stacked sequentially. The silicon nitride layer 2' comprises three stacked silicon nitride layers.

[0039] Because the silicon oxynitride layer 3' and silicon oxide layer 300 have low refractive indices and high reflectivities, and because they constitute a large proportion of the overall structure, the antireflective coating has an overall low refractive index and high reflectivity, which is detrimental to the light absorption of the solar cell 100'. Furthermore, along the Z-direction, the total thickness of the antireflective coating ranges from 75nm to 90nm, which is relatively thick and makes it difficult to capture blue light in the wavelength range of 400nm to 460nm, thus increasing the risk of blue emission from the solar cell 100'.

[0040] Based on this, this application proposes a solar cell and its preparation method and electronic device, aiming to reduce the risk of graying and blueing of solar cells.

[0041] On the one hand, a solar cell is provided. Figure 3 This is a schematic diagram of the structure of the solar cell provided in this application.

[0042] See Figure 3 The solar cell 100 is a TOPCon cell. The solar cell 100 includes a substrate 1, a first stacked structure 2, and a second stacked structure 3. Both the first stacked structure 2 and the second stacked structure 3 are used for anti-reflection.

[0043] The substrate 1 includes a first surface 101 and a second surface 102 opposite to each other. The first surface 101 is provided with a plurality of tower-like structures 10. The first surface 101 is a light-receiving surface, the second surface 102 is a backlighting surface, and the plurality of tower-like structures 10 are textured structures on the first surface 101. For example, the substrate 1 can be an n-type silicon substrate.

[0044] Figure 4 This is a measured diagram of the textured surface structure of the solar cell provided in this application.

[0045] Among them, see Figure 3 and Figure 4 Along a direction X parallel to the second surface 102, the number of tower-like structures 10 per square centimeter on the first surface 101 is greater than or equal to 190,000. Exemplarily, the base width of the tower-like structure 10 is 1.4 μm to 1.8 μm, for example, it can be 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, or 1.8 μm. The height of the tower-like structure 10 is 0.8 μm to 1.2 μm, for example, it can be 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, or 1.2 μm.

[0046] Compared to Figure 1 The tower-like structure shown in this application has a reduced base width and height, resulting in a greater number of tower-like structures 10 per unit area. The number of tower-like structures 10 per square centimeter is greater than or equal to 190,000, meaning the flocking density of the first surface 101 is greater than or equal to 190,000 / cm². 2 .

[0047] Figures 5-7 Box plot comparing the textured surface data of the solar cell provided in this application with that of solar cells in related technologies.

[0048] See Figure 5In related technologies, the median width of multiple tower-like structures 10' is 1.767. In the embodiments of this application, the median width of multiple tower-like structures 10 is 1.663. The tower base width of the tower-like structure 10 provided in this application is smaller.

[0049] See Figure 6 In related technologies, the median height of multiple tower-like structures 10' is 1.419. In the embodiments of this application, the median height of multiple tower-like structures 10 is 1.0955. The tower base height of the tower-like structure 10 provided in this application is smaller.

[0050] See Figure 7 In related technologies, the median texturing density of the first surface 101' is 188,658 / cm². 2 In the embodiments of this application, the median down density of the first surface 101 is 211356, and the down density of the tower-shaped structure 10 of this application is even greater.

[0051] As can be seen, the multiple tower-shaped structures 10 provided in this application have smaller tower base width and height, and more towers, which increases the texturing density of the first surface 101, thereby increasing the reflectivity of the first surface 101, thereby reducing the brightness of the solar cell 100, and thus reducing the risk of the solar cell 100 turning gray.

[0052] See also Figure 3 A first stacked structure 2 is stacked on the first surface 101. The first stacked structure 2 includes at least one first antireflective film 20, and the material of the first antireflective film 20 includes silicon nitride. A second stacked structure 3 is stacked on the side of the first stacked structure 2 away from the substrate 1. The second stacked structure 3 includes at least one second antireflective film 30, and the material of the second antireflective film 30 includes silicon oxynitride.

[0053] Along the direction Z perpendicular to the second surface 102, the first stack structure 2 is thicker than the second stack structure 3, the thickness ratio of the first stack structure 2 to the second stack structure 3 is greater than or equal to 1.5, the refractive index of the first stack structure 2 is greater than or equal to 2.15, and the refractive index of the second stack structure 3 is less than or equal to 2.0.

[0054] The solar cell 100 in this embodiment includes a substrate 1, a first stacked structure 2, and a second stacked structure 3. The substrate 1 includes a first surface 101 and a second surface 102 facing each other, with the first surface 101 being the light-receiving surface. Along a direction X parallel to the second surface 102, the number of tower-like structures 10 on the first surface 101 is greater than or equal to 190,000 per square centimeter. Compared to related technologies, the first surface 101 in this application has a higher texturing density and better light-trapping effect, reducing the probability of light escape and decreasing the reflectivity of the first surface 101 to light, thereby reducing the overall brightness of the solar cell 100 and lowering the risk of the solar cell 100 turning gray.

[0055] In this application, the reflectivity of the first surface 101 to light is reduced to 8%~10%. For example, the reflectivity of the first surface 101 can be 8%, 8.5%, 9%, 9.5% or 10%, which is beneficial to reduce the overall brightness of the solar cell 100 and reduce the risk of the solar cell 100 turning gray.

[0056] Based on increasing the texturing density of the first surface 101, a first stack structure 2 is stacked on the first surface 101. The first stack structure 2 includes at least one first antireflective film 20 made of silicon oxide. A second stack structure 3 is stacked on the side of the first stack structure 2 away from the substrate 1. The second stack structure 3 includes at least one second antireflective film 30 made of silicon oxynitride. The first stack structure 2 and the second stack structure 3 cooperate to form an antireflective film. The first surface 101 is uneven due to the presence of the tower-shaped structure 10. The first stack structure 2 and the second stack structure 3 are formed on the first surface 101, making their surfaces also uneven. This improves the light-trapping effect of the first stack structure 2 and the second stack structure 3 and reduces the reflectivity of the antireflective film.

[0057] It is understandable that the refractive index of silicon nitride is greater than that of silicon oxynitride, and the refractive index of the first stacked structure 2 of silicon nitride material is greater than that of the second stacked structure 3 of silicon oxynitride material. By setting the thickness ratio of the first stacked structure 2 to the second stacked structure 3 to be greater than or equal to 1.5, the thickness of the first stacked structure 2 with a higher refractive index is larger in the antireflection film layer, which avoids the appearance of cells with too low a refractive index and helps to reduce the overall reflectivity of the solar cell 100.

[0058] Furthermore, the refractive index of the first stack structure 2 is greater than or equal to 2.15, and the refractive index of the second stack structure 3 is less than or equal to 2.0, so that the refractive index of the first stack structure 2 and the second stack structure 3 has a difference of at least 0.15, ensuring that the overall reflectivity of the solar cell 100 is low, especially reducing the reflectivity of light (blue light) in the wavelength range of 400nm~460nm. The reflectivity can be reduced to below 10%, thereby reducing the risk of the solar cell 100 turning blue and thus improving the color quality of the solar cell 100.

[0059] In some embodiments, see Figure 3 The solar cell 100 also includes a passivation layer 4 disposed between the substrate 1 and the first stack structure 2. The material of the passivation layer 4 includes aluminum oxide. For example, the thickness of the passivation layer 4 ranges from 4 nm to 12 nm.

[0060] The thickness variation rate α of the passivation layer 4 is less than or equal to 3%. The thickness of the passivation layer 4 is measured at multiple locations to obtain n thickness values ​​d1, d2, d3, ..., dn. n Among the n thickness values, the maximum value d is included. max and minimum value d min , α = (d max -d min The range of α can be calculated by using () / 2n.

[0061] It is understandable that α≤3%, meaning the passivation layer 4 has high thickness uniformity. Since the passivation layer 4 is closest to the substrate 1, and the alumina material of the passivation layer 4 has a low refractive index, the uniform thickness of the passivation layer 4 is beneficial to improving the uniformity of light reflection in different parts of the substrate 1, thereby reducing the risk of color difference in the solar cell 100.

[0062] In some embodiments, the solar cell 100 further includes a tunneling layer 5, a first conductivity type layer 6, an emitter layer 7, an electrode 8, and an antireflection layer 9. The tunneling layer 5, the first conductivity type layer 6, and the antireflection layer 9 are sequentially stacked on the second surface 102, and the emitter layer 7 is disposed on the first surface 101. The electrode 8 is disposed on the side of the passivation layer 4 away from the substrate 1 and on the side of the first conductivity type layer 6 away from the substrate 1.

[0063] For example, the tunneling layer 5 can be made of silicon oxide. The first conductivity type layer 6 is doped with phosphorus, and its conductivity type is n-type. The emitter layer 7 is doped with boron, and its conductivity type is p-type. The electrode 8 is used for electrical connection between the solar cell 100 and an external structure.

[0064] In some embodiments, see Figure 3Along the direction Z perpendicular to the second surface 102, the first stack structure 2 includes a plurality of stacked first antireflective films 20. Exemplarily, the first stack structure 2 may include two, three, or four stacked first antireflective films 20. This embodiment illustrates the first stack structure 2 with three stacked first antireflective films 20 as an example. Along the direction away from the substrate 1 (direction Z), the refractive index of the plurality of first antireflective films 20 decreases sequentially, creating a difference in refractive index between adjacent first antireflective films 20, which is beneficial for reducing the reflectivity of the first stack structure 2.

[0065] In some embodiments, see Figure 3 The plurality of first antireflective films 20 include a first bottom antireflective film 21 closest to the substrate 1, and a first top antireflective film 22 located on the side of the first bottom antireflective film 21 away from the substrate 1. For example, the first top antireflective film 22 includes a first silicon nitride layer 221 and a second silicon nitride layer 222 stacked together.

[0066] Since the material of the multiple first antireflective films 20 is silicon nitride, the refractive index of the multiple first antireflective films 20 can be adjusted by adjusting the silicon-nitrogen ratio of the material. The silicon-nitrogen ratio is the ratio of SiH4 to NH3. The more silane and the less ammonia in silicon nitride, the higher its refractive index. That is, the higher the silicon-nitrogen ratio in the first antireflective film 20, the higher its refractive index.

[0067] The silicon-to-nitrogen ratio in the first bottom antireflective film 21 is 1:5 to 1:2. For example, the silicon-to-nitrogen ratio in the first bottom antireflective film 21 can be 1:5, 3:10, 7:20, 2:5, or 1:2. The silicon-to-nitrogen ratio in the first top antireflective film 22 is 1:15 to 1:6. For example, the silicon-to-nitrogen ratio in the first top antireflective film 22 can be 1:15, 1:10, 7:60, 2:15, or 1:6.

[0068] Understandably, in the first stack structure 2, the first bottom antireflective film 21, which is closest to the substrate 1, has the highest silicon-to-nitrogen ratio and the highest refractive index. Along the direction Z away from the substrate 1, the silicon-to-nitrogen ratio in the first silicon nitride layer 221 and the second silicon nitride layer 222 gradually decreases in the range of 1:15 to 1:6, that is, the refractive index of the first silicon nitride layer 221 is greater than the refractive index of the second silicon nitride layer 222.

[0069] In some embodiments, see Figure 3 The thickness ratio of the first bottom antireflective film 21 to the first top antireflective film 22 is 0.16 to 1. For example, the thickness ratio can be 0.16, 0.3, 0.5, 0.8 or 1. For example, the thickness of the first bottom antireflective film 21 is in the range of 8nm to 20nm, and the thickness of the first top antireflective film 22 is in the range of 20nm to 50nm.

[0070] It is understandable that the thickness of the first bottom antireflective film 21 is less than or equal to the thickness of the first top antireflective film 22. Since the refractive index of the first bottom antireflective film 21 is higher than that of the first top antireflective film 22, the extinction coefficient of the high-refractive-index first bottom antireflective film 21 is higher. By setting the thickness of the first bottom antireflective film 21 to be smaller, the loss of 100% efficiency of the solar cell can be avoided.

[0071] In some embodiments, see Figure 3 Along direction Z, the second stack structure 3 includes a plurality of stacked second antireflective films 30. Exemplarily, the second stack structure 3 may include two, three, or four stacked second antireflective films 30. This embodiment illustrates the second stack structure 3 as having three stacked second antireflective films 30. Along the direction away from the substrate 1 (direction Z), the refractive index of the plurality of second antireflective films 30 decreases sequentially, creating a difference in refractive index between adjacent second antireflective films 30, which is beneficial for reducing the reflectivity of the second stack structure 3.

[0072] In some embodiments, see Figure 3 The plurality of second antireflective films 30 include a second bottom antireflective film 31 closest to the substrate 1, and a second top antireflective film 32 located on the side of the second bottom antireflective film 31 away from the substrate 1. For example, the second top antireflective film 32 includes a first silicon oxynitride layer 321 and a second silicon oxynitride layer 322 stacked together.

[0073] Since the material of the multiple second antireflective films 30 is silicon oxynitride, the refractive index of the multiple second antireflective films 30 can be adjusted by changing the silicon-to-nitrogen ratio and the silicon-to-oxygen ratio of the material. The silicon-to-nitrogen ratio is the ratio of SiH4 to NH3, and the silicon-to-oxygen ratio is the ratio of SiH4 to N2O. The higher the proportion of N2O in the silicon oxynitride, the higher its refractive index. The content of SiH4 and NH3 must be adjusted according to the content of N2O. In other words, the higher the proportion of "oxygen" in the second antireflective film 30, the higher its refractive index.

[0074] The silicon-to-nitrogen ratio in the second bottom antireflective film 31 is 1:10 to 1:4. For example, the silicon-to-nitrogen ratio in the second bottom antireflective film 31 can be 1:10, 3:20, 7:40, 1:5, or 1:4. The silicon-to-oxygen ratio in the second bottom antireflective film 31 is 1:6 to 1:4. For example, the silicon-to-oxygen ratio in the second bottom antireflective film 31 can be 1:6, 3:16, 5:24, 11:48, or 1:4.

[0075] The silicon-to-nitrogen ratio in the second upper antireflective film 32 is 1:8 to 1:4. For example, the silicon-to-nitrogen ratio in the second upper antireflective film 32 can be 1:8, 5:32, 3:16, 7:32, or 1:4. The silicon-to-oxygen ratio in the second upper antireflective film 32 is 1:10 to 1:6. For example, the silicon-to-oxygen ratio in the second upper antireflective film 32 can be 1:10, 7:60, 2:15, 3:20, or 1:6.

[0076] It is understandable that in the second stack structure 3, the second bottom antireflective film 31, which is closest to the substrate 1, has the highest refractive index, and the refractive index of the first silicon oxynitride layer 321 is greater than that of the second silicon oxynitride layer 322.

[0077] In some embodiments, see Figure 3 The thickness of the overall structure formed by the first stack structure 2 and the second stack structure 3 ranges from 65nm to 85nm. For example, the thickness of the overall structure can be 65nm, 70nm, 75nm, 80nm, or 85nm. The refractive index of the overall structure is 2.08 to 2.15. For example, the refractive index of the overall structure can be 2.08, 2.10, 2.12, 2.14, or 2.15. Compared to the total thickness range of 75nm to 90nm for antireflective films in related technologies, the overall structure in the embodiment of this application has a smaller thickness and a higher refractive index, which is more conducive to light capture.

[0078] Figure 8 A comparison of reflectance test results of multiple antireflection coatings provided in this application and antireflection coatings in related technologies under illumination of different wavelengths of light; Figure 9 A comparison of the transmittance test results of the multiple antireflection coatings provided in this application and antireflection coatings in related technologies under illumination of different wavelengths of light; Figure 10 A comparison of the absorption rate test results of the multiple antireflection coatings provided in this application and antireflection coatings in related technologies under illumination of different wavelengths of light.

[0079] See Figure 8 Curve A1 represents the reflectance variation curve of the overall structure formed by the first stack structure 2 and the second stack structure 3, while curve A2 represents the reflectance variation curve of the antireflective coating layer in the related technology. Within the wavelength range of 380nm to 600nm, the reflectance corresponding to curve A1 is consistently lower than that of curve A2, meaning the reflectance of the aforementioned overall structure is lower than that of the antireflective coating layer in the related technology. Particularly in the wavelength range of 400nm to 460nm, the reflectance of curve A1 is significantly lower than that of curve A2. Since light with wavelengths of 400nm to 460nm is blue light, the reflectance of the aforementioned overall structure is significantly reduced in the blue light region, thereby reducing the risk of blue emission from the solar cell 100.

[0080] See Figure 9 Curve B1 represents the transmittance variation curve of the overall structure formed by the first stacked structure 2 and the second stacked structure 3, while curve B2 represents the transmittance variation curve of the antireflective coating layer in the related technology. Within the wavelength range of 380nm to 600nm, curves B1 and B2 essentially overlap, indicating that the multiple stacked layers in the first stacked structure 2 and the second stacked structure 3 do not affect the light transmittance, thus ensuring good light transmittance of the solar cell 100.

[0081] See Figure 10 Curve C1 represents the absorptivity variation curve of the overall structure formed by the first stacked structure 2 and the second stacked structure 3, while curve C2 represents the absorptivity variation curve of the antireflective coating layer in the related technology. Within the wavelength range of 380nm to 520nm, the absorptivity corresponding to curve C1 is consistently higher than that of curve C2, indicating that the overall structure's light absorption rate has increased, particularly in the blue light region, where the increase is more significant, thereby reducing the risk of blue emission from solar cell 100.

[0082] It should be noted that the sum of the above-mentioned reflectivity, transmittance and absorptivity is equal to 100%.

[0083] Figure 11 A comparison chart showing the reflectivity test results of the solar cell provided in this application and solar cells in related technologies under illumination of different wavelengths of light; Figure 12 A comparison chart showing the transmittance test results of the solar cell provided in this application and solar cells in related technologies under different wavelengths of light. Figure 13 The graph shows a comparison of the absorption rate test results of the solar cells provided in this application and those in related technologies under illumination of different wavelengths of light.

[0084] In some embodiments, see Figure 11 Curve A3 represents the reflectance variation curve of solar cell 100, specifically the reflectance variation curves of the first stack structure 2, the second stack structure 3, and the textured structure. Curve A4 represents the reflectance variation curve of solar cell 100' in related technologies. Within the wavelength range of 380nm to 600nm, the reflectance corresponding to curve A3 is consistently lower than that of curve A4, indicating that the reflectance of solar cell 100 in this application is even lower. Particularly in the wavelength range of 400nm to 460nm, the reflectance of curve A3 is significantly lower than that of curve A4. Light with wavelengths of 400nm to 460nm is blue light, meaning that the reflectance of solar cell 100 is significantly reduced in the blue light region, thereby reducing the risk of blue emission from solar cell 100. Furthermore, the reflectance of solar cell 100 for light with wavelengths of 400nm to 460nm (blue light) is less than 10%.

[0085] See Figure 12 Curve B3 represents the transmittance variation curve of solar cell 100, and curve B4 represents the transmittance variation curve of solar cell 100' in related technologies. Within the wavelength range of 380nm to 600nm, curves B3 and B4 basically overlap, meaning that the transmittance of light in solar cell 100 is basically unaffected, ensuring good light transmittance of solar cell 100.

[0086] See Figure 13 Curve C3 represents the absorptivity variation curve of solar cell 100, and curve C4 represents the absorptivity variation curve of solar cell 100' in related technologies. Within the wavelength range of 380nm to 520nm, the absorptivity corresponding to curve C3 is always higher than that of curve C4, indicating that the overall structure has increased light absorption, especially in the blue light region, where the increase is more significant, thereby reducing the risk of blue emission from solar cell 100.

[0087] It should be noted that the sum of the above-mentioned reflectivity, transmittance and absorptivity is equal to 100%.

[0088] A Lab color model of the solar cell was established using a color difference meter. Figures 14-16 Lab box plot comparing the solar cell provided in this application with solar cells in related technologies; Figure 17 This is a schematic diagram of the Lab color model.

[0089] See Figure 14 In related technologies, the L value (brightness) of solar cells in the Lab color model satisfies 9 ≤ L ≤ 15, and the median L value is 12.3. In the embodiments of this application, the L value of solar cells in the Lab color model satisfies 8 ≤ L ≤ 10.5, and the median L value is 9.035. The L value of the solar cells in this application is lower and closer to 0. (Refer to...) Figure 17 The larger the L value, the brighter the color; the smaller the L value, the darker the color. Compared with related technologies, the L value of the solar cell in this application is closer to 0. Therefore, the color of the solar cell is darker and closer to black.

[0090] See Figure 15 In related technologies, the a value of solar cells in the Lab color model satisfies 2.5 ≤ a ≤ 7, and the median a value is 4.94. In the embodiments of this application, the a value of solar cells in the Lab color model satisfies 2.5 ≤ a ≤ 4.5, and the median a value is 3.475. The a value of the solar cells in this application is smaller and closer to 0. (Refer to...) Figure 17 The larger the a value, the redder the color; the smaller the a value, the greener the color. Compared with related technologies, the a value of the solar cell in this application is closer to 0. Therefore, the solar cell has less red and is closer to black.

[0091] See Figure 16 In related technologies, the b-values ​​of solar cells in the Lab color model satisfy -18 ≤ b ≤ -12, and the median b-value is -16.09. In the embodiments of this application, the b-values ​​of solar cells in the Lab color model satisfy -14 ≤ b ≤ -3, and the median b-value is -8.66. The b-values ​​of the solar cells in this application are larger and closer to 0. Figure 17 The larger the b value, the yellower the color; the smaller the b value, the bluer the color. Compared with related technologies, the b value of the solar cell in this application is closer to 0. Therefore, the solar cell has less blue and is closer to black.

[0092] On the other hand, embodiments of this application also provide a method for preparing a solar cell. Figure 18 A flowchart illustrating the fabrication process of the solar cell provided in this application; Figures 19-24 This is a diagram illustrating the fabrication steps of the solar cell provided in this application.

[0093] See Figure 18 The preparation method includes the following steps S1 to S4: Step S1: See Figure 19 A substrate 1 is provided, which includes a first surface 101 and a second surface 102 opposite to each other. The first surface 101 is a light-receiving surface, and the second surface 102 is a backlighting surface. For example, the substrate 1 can be an n-type silicon substrate.

[0094] Step S2: See Figure 20 The substrate 1 is texturized to form a plurality of tower-like structures 10 on the first surface 101. Along a direction X parallel to the second surface 102, the number of tower-like structures 10 per square centimeter on the first surface 101 is greater than or equal to 190,000. Compared to... Figure 1 In the related technology shown, the fiber density on the first surface 101' is greater than 120,000 / cm². 2 The first surface 101 in this application has a higher texturing density, which means that the reflectivity and refractive index of light shining on the first surface 101 are smaller, thereby reducing the probability of light escaping, which reduces the overall brightness of the solar cell 100 and thus reduces the risk of the solar cell 100 turning gray.

[0095] In some embodiments, see Figure 20The alkali content in the texturing bath solution is 0.5% to 1%, and for example, the alkali content can be 0.5%, 0.6%, 0.75%, 0.9%, or 1%. The additive content is 0.2% to 0.6%, and for example, the additive content can be 0.2%, 0.3%, 0.4%, 0.5%, or 0.6%. For example, the additive can be isopropanol. The texturing time is 300s to 400s, and for example, the texturing time can be 300s, 330s, 350s, 580s, or 400s.

[0096] Step S3: See Figure 23 A first stack structure 2 is formed on the first surface 101. The first stack structure 2 includes at least one first antireflective film 20, and the material of the first antireflective film 20 includes silicon nitride. Exemplarily, the first stack structure 2 may include one, two, three or four first antireflective films 20. The embodiments of this application illustrate the example of the first stack structure 2 including three stacked first antireflective films 20.

[0097] For example, the plurality of first antireflective films 20 include a first bottom antireflective film 21 closest to the substrate 1, and a first top antireflective film 22 located on the side of the first bottom antireflective film 21 away from the substrate 1. The first top antireflective film 22 includes a first silicon nitride layer 221 and a second silicon nitride layer 222 stacked together. Along the direction away from the substrate 1 (direction Z), the refractive index of the plurality of first antireflective films 20 decreases sequentially, and the thickness of the first bottom antireflective film 21 is less than or equal to the thickness of the first top antireflective film 22.

[0098] For example, see Figure 21 Before forming the first stack structure 2 on the first surface 101, elemental doping is performed on the first surface 101 to form the emitter layer 7. For example, the doping element can be boron; boron doping on the silicon substrate surface will produce a byproduct, borosilicate glass (BSG). Since elemental doping is a diffusion process, doped regions and the byproduct BSG will also be formed on the second surface 102. Then, alkaline polishing is used to remove the doped regions and the byproduct BSG on the second surface 102 to obtain a flat second surface 102.

[0099] Next, low-pressure chemical vapor deposition (LPCVD) is used to sequentially form a tunneling layer 5 and a conductive layer on the second surface 102. Elemental doping is performed within the conductive layer to form a first conductivity type layer 6, followed by annealing. For example, phosphorus can be the dopant element; boron doping within the conductive layer will produce a byproduct, phosphosilicate glass (PSG). Since elemental doping is a diffusion process, PSG will also form on the first surface 102.

[0100] The BSG and PSG on the first surface 101 are removed, and the substrate 1, tunneling layer 5, and first conductive type layer 6 are cleaned using a standardized wet cleaning process to obtain the desired result. Figure 17 The structure shown.

[0101] In some embodiments, see Figure 22 After texturing the substrate 101 and before forming the first stack structure 2, the above-mentioned preparation method further includes forming a passivation layer 4 on the first surface 101 using an atomic layer deposition (ALD) process. The material of the passivation layer 4 includes aluminum oxide, and the thickness variation rate α of the passivation layer 4 is less than or equal to 3%, that is, the thickness uniformity of the passivation layer 4 is high. Since the passivation layer 4 is closest to the substrate 1, and the refractive index of the aluminum oxide passivation layer 4 is low, the uniform thickness of the passivation layer 4 is beneficial to improving the uniformity of light reflection in various parts of the substrate 1.

[0102] Specifically, n thickness values ​​d1, d2, d3, ..., d can be obtained by measuring the thickness of the passivation layer 4 at multiple locations. n Among the n thickness values, the maximum value d is included. max and minimum value d min , α = (d max -d min The range of α can be calculated by using () / 2n.

[0103] Step S4: See Figure 24 A second stack structure 3 is formed on the side of the first stack structure 2 away from the substrate 1. The second stack structure 3 includes at least one second antireflective film 30, and the material of the second antireflective film 30 includes silicon oxynitride. Exemplarily, the second stack structure 3 may include one, two, three, or four second antireflective films 30. The embodiments of this application illustrate the second stack structure 3 as having three stacked second antireflective films 30.

[0104] For example, the plurality of second antireflective films 30 include a second bottom antireflective film 31 closest to the substrate 1, and a second top antireflective film 32 located on the side of the second bottom antireflective film 31 away from the substrate 1. The second top antireflective film 32 includes a first silicon oxynitride layer 321 and a second silicon oxynitride layer 322 stacked together. Along the direction away from the substrate 1 (direction Z), the refractive index of the plurality of first antireflective films 20 decreases sequentially.

[0105] Among them, see Figure 24Along direction Z, the thickness ratio of the first stack structure 2 to the second stack structure 3 is greater than or equal to 1.5. The refractive index of the first stack structure 2 is greater than or equal to 2.15, and the refractive index of the second stack structure 3 is less than or equal to 2.0. It is understandable that the first antireflective film 20 made of silicon nitride material has a higher refractive index, which is beneficial for light absorption, while the second antireflective film 30 made of silicon oxynitride material has a lower refractive index. In the antireflective film layers, the first stack structure 2, with its higher refractive index, accounts for a larger proportion, thereby increasing the overall refractive index of the solar cell 100 and reducing the risk of blue emission from the solar cell 100.

[0106] For example, see Figure 3 After forming the second stack structure 3, the above-described fabrication method further includes forming an antireflection layer 9 on the side of the first conductivity type layer 6 away from the second surface 102, and then forming electrodes 8 on the first surface 101 and the second surface 102 respectively to form a solar cell 100. The solar cell 100 is a TOPCon cell.

[0107] For example, electrode materials are printed on the second silicon oxynitride layer 322 and the antireflection layer 9, respectively, and electrode 8 is obtained by sintering and photo-injection or electro-injection of the electrode materials.

[0108] In some embodiments, see Figure 23 and Figure 24 Plasma-enhanced chemical vapor deposition (PECVD) is used to form a first stack structure 2 and a second stack structure 3.

[0109] On the other hand, embodiments of this application also provide a photovoltaic module. Figure 25 This is a schematic diagram of the structure of the photovoltaic module provided in this application.

[0110] See Figure 25 The photovoltaic module 400 includes multiple solar cells 100 as described in the above embodiments, and the multiple solar cells 100 are electrically connected. Exemplarily, the multiple solar cells 100 can be connected in series or in parallel; the embodiments of this application illustrate this by using two solar cells 100 connected in series as an example. Because the risk of graying or bluish tint in the solar cells 100 is reduced, the color quality of the solar cells 100 is improved, thereby improving the color quality of the photovoltaic module 400.

[0111] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A solar cell, characterized in that, include: The substrate includes opposing first and second surfaces, wherein the first surface is provided with a plurality of tower-like structures; A first stack structure is stacked on the first surface; the first stack structure includes at least one first anti-reflective film, the material of the first anti-reflective film being silicon nitride. A second stacked structure is stacked on the side of the first stacked structure away from the substrate. The second stacked structure includes at least one second antireflective film, and the material of the second antireflective film includes silicon oxynitride. The solar cell has a reflectivity of less than 10% for light with wavelengths of 400nm to 460nm; the L value of the solar cell in the Lab color model satisfies 8≤L≤10.5, the a value satisfies 2.5≤a≤4.5, and the b value satisfies -14≤b≤-3.

2. The solar cell according to claim 1, characterized in that, Along a direction parallel to the second surface, the number of tower-like structures per square centimeter on the first surface is greater than or equal to 190,000; Along a direction perpendicular to the second surface, the thickness ratio of the first stack structure to the second stack structure is greater than or equal to 1.5; the refractive index of the first stack structure is greater than or equal to 2.15, and the refractive index of the second stack structure is less than or equal to 2.

0.

3. The solar cell according to claim 1, characterized in that, Along a direction perpendicular to the second surface, the first stack structure includes a plurality of stacked first antireflective films; Along the direction away from the substrate, the refractive index of the plurality of first antireflective films decreases sequentially.

4. The solar cell according to claim 3, characterized in that, The plurality of first antireflective films include a first bottom antireflective film closest to the substrate, and a first top antireflective film located on the side of the first bottom antireflective film away from the substrate; The silicon-to-nitrogen ratio in the first bottom antireflective film is 1:5 to 1:2; the silicon-to-nitrogen ratio in the first top antireflective film is 1:15 to 1:

6.

5. The solar cell according to claim 3, characterized in that, The plurality of first antireflective films include a first bottom antireflective film closest to the substrate, and a first top antireflective film located on the side of the first bottom antireflective film away from the substrate; The thickness ratio of the first bottom antireflective film to the first top antireflective film is 0.16~1.

6. The solar cell according to claim 1, characterized in that, Along a direction perpendicular to the second surface, the second stack structure includes a plurality of stacked second antireflective films; Along the direction away from the substrate, the refractive index of the plurality of second antireflective films decreases sequentially.

7. The solar cell according to claim 6, characterized in that, The plurality of second antireflective films include a second bottom antireflective film closest to the substrate, and a second top antireflective film located on the side of the second bottom antireflective film away from the substrate; The silicon-to-nitrogen ratio in the second bottom antireflective film is 1:10 to 1:4, and the silicon-to-oxygen ratio is 1:6 to 1:4; the silicon-to-nitrogen ratio in the second top antireflective film is 1:8 to 1:4, and the silicon-to-oxygen ratio is 1:10 to 1:

6.

8. The solar cell according to claim 1, characterized in that, The thickness of the overall structure formed by the first stack structure and the second stack structure ranges from 65nm to 85nm, and the refractive index is 2.08 to 2.

15.

9. The solar cell according to claim 1, characterized in that, The width of the base of the tower-like structure is 1.4μm to 1.8μm, and the height of the tower-like structure is 0.8μm to 1.2μm. The reflectivity of the first surface is 8%~10%.

10. The solar cell according to claim 1, characterized in that, The solar cell further includes a passivation layer disposed between the substrate and the first stack structure; The passivation layer is made of aluminum oxide, and the thickness variation rate of the passivation layer is less than or equal to 3%.

11. A method for preparing a solar cell, characterized in that, include: A substrate is provided, the substrate including opposing first and second surfaces; The substrate is texturing to form a plurality of tower-like structures on the first surface; A first stack structure is formed on the first surface, the first stack structure including at least one first antireflective film, the material of the first antireflective film including silicon nitride; A second stack structure is formed on the side of the first stack structure away from the substrate, the second stack structure including at least one second antireflective film, the material of the second antireflective film including silicon oxynitride; The solar cell has a reflectivity of less than 10% for light with wavelengths of 400nm to 460nm; the L value of the solar cell in the Lab color model satisfies 8≤L≤10.5, the a value satisfies 2.5≤a≤4.5, and the b value satisfies -14≤b≤-3.

12. The preparation method according to claim 11, characterized in that, Along a direction parallel to the second surface, the number of tower-like structures per square centimeter on the first surface is greater than or equal to 190,000; Along a direction perpendicular to the second surface, the thickness ratio of the first stack structure to the second stack structure is greater than or equal to 1.5; the refractive index of the first stack structure is greater than or equal to 2.15, and the refractive index of the second stack structure is less than or equal to 2.

0.

13. The preparation method according to claim 11, characterized in that, The alkali content in the texturing bath solution of the texturing process is 0.5%~1%, and the additive content is 0.2%~0.6%. The flocking time for the flocking process is 300s~400s.

14. The preparation method according to claim 11, characterized in that, The first stack structure and the second stack structure are formed using a plasma-enhanced chemical vapor deposition process.

15. The preparation method according to claim 11, characterized in that, After texturing the substrate and before forming the first stack structure, the preparation method further includes: An atomic layer deposition process is used to form a passivation layer on the first surface; the material of the passivation layer includes aluminum oxide, and the thickness variation rate of the passivation layer is less than or equal to 3%.

16. A photovoltaic module, characterized in that, It includes a plurality of solar cells as described in any one of claims 1 to 10, and the plurality of solar cells are electrically connected.

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