Solar cell, assembly and system

Abstract

The invention belongs to the technical field of solar cells, and relates to a solar cell, an assembly and a system. The pyramid structure is arranged on the surface of the silicon substrate, protrusions are formed on the surface of the pyramid structure, and the average height of the protrusions ranges from 1 nm to 50 nm. According to the invention, the nano-sized bulges are arranged on the pyramid suede, so that the reflectivity of the silicon substrate bare chip is effectively reduced, and the reliability is high.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology and relates to a solar cell, module and system. Background Technology

[0002] Against the backdrop of the photovoltaic industry's pursuit of high efficiency, monocrystalline silicon solar cells dominate due to their advantages in raw materials and manufacturing. Surface texturing of silicon wafers, as a core process, aims to create micro-nano morphologies to reduce light reflection and surface recombination, thereby directly improving the cell's photoelectric conversion efficiency. Industry data shows that for every 1% reduction in silicon wafer surface reflectivity, efficiency increases by approximately 0.2%-0.3%.

[0003] Current texturing technology is based on alkaline etching, with conventional pyramid texturing being the mainstream. It utilizes the anisotropic etching of silicon in an alkaline solution to form a 3μm~5μm pyramid structure. The reflectivity of the bare wafer is reduced from more than 35% of polished silicon wafers to about 10%, and can be further reduced to 2%-3% with the addition of coating. The process is simple, low-cost, and compatible with mass production equipment. However, smooth pyramids are not good at capturing medium and high angle incident light, and the size and density are difficult to optimize. The reflectivity of the bare wafer is difficult to break through the 10% threshold, which restricts the further improvement of short-circuit current.

[0004] To achieve better anti-reflection effects, inverted pyramid and black silicon texturing technologies have emerged. Inverted pyramid technology uses precious metals to catalyze etching to create pit-like structures, effectively reducing the reflectivity of the bare wafer. However, the catalysts are expensive and difficult to recycle. Black silicon texturing utilizes metal particles to catalyze the formation of nanoneedle-like structures, effectively reducing the reflectivity of the bare wafer. However, it suffers from high surface recombination rates, complex passivation, and the nanostructures are easily damaged during coating, resulting in poor reliability and hindering industrialization. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a solar cell, module and system that effectively reduces the reflectivity of the silicon substrate by setting nanoscale protrusions on the pyramid textured surface, and has high reliability.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a solar cell, comprising: silicon substrate; A pyramid structure is disposed on the surface of the silicon substrate, the surface of the pyramid structure having protrusions, the average height of the protrusions being 1nm~50nm.

[0007] In some embodiments, the protrusions are island-shaped protrusions, and the distribution density of the protrusions is 100 per μm. 2 ~180 cells / μm 2 .

[0008] In some embodiments, the protrusions are formed on the surface of the pyramid structure by etching, preferably by alkaline etching.

[0009] In some embodiments, the reflectivity of the pyramid structure surface is 1.5% to 8.5%.

[0010] In some embodiments, the protrusion includes a first protrusion formed on the top of the pyramid structure, the average height h1 of the first protrusion being 1 nm to 30 nm.

[0011] In some embodiments, the first protrusion includes a first sidewall and a first bottom surface, the bottom edge of the first bottom surface has a side length of W1, the height of the first protrusion is H1, and the aspect ratio H1 / W1 of a single first protrusion is 0.1 to 0.2.

[0012] In some embodiments, the radius of curvature of the top of the first protrusion is 80 nm to 200 nm.

[0013] In some embodiments, the protrusion includes a second protrusion formed on the sidewall of the pyramid structure, the average height of the second protrusion being h2, which is 10 nm to 50 nm.

[0014] In some embodiments, the average height of the first protrusion is h1, the average height of the second protrusion is h2, and h1 ≤ h2.

[0015] In some embodiments, the second protrusion includes a second sidewall and a second bottom surface, the bottom edge of the second bottom surface has a side length of W2, the height of the second protrusion is H2, and the aspect ratio H2 / W2 of a single second protrusion is 0.2 to 0.4.

[0016] In some embodiments, the radius of curvature of the top of the second protrusion is 40 nm to 100 nm.

[0017] In some embodiments, the first protrusion and / or the second protrusion is a polyhedral structure, a frustum structure, or a conical structure.

[0018] In some embodiments, the surface of the pyramid structure is further formed with pits, the average depth of which is 1 nm to 50 nm.

[0019] In some embodiments, the pits and the protrusions form a continuously varying curved surface.

[0020] In some embodiments, the pit includes a first pit formed on the top of the pyramid structure, the first pit having an average depth of 1 nm to 30 nm.

[0021] In some embodiments, the first recess includes a first sidewall, a first bottom surface, and a first opening. The side length of the projected outline of the first opening on the first bottom surface is W11, the side length of the first bottom surface is W12, the depth of the first recess is D1, and the aspect ratio of a single first recess is D1 / W11 = 0.25~0.3, where W11 ≥ W12.

[0022] In some embodiments, the pit includes a second pit formed on the sidewall of the pyramid structure, the second pit having an average depth of 10 nm to 50 nm.

[0023] In some embodiments, the second recess includes a second sidewall, a second bottom surface, and a second opening. The side length of the projected outline of the second opening on the second bottom surface is W21, the side length of the second bottom surface is W22, the depth of the second recess is D2, and the depth-to-width ratio of a single second recess is D2 / W21 = 0.3~0.45, where W21 ≥ W22.

[0024] In some embodiments, the first recess and / or the second recess is a polygonal recess, an inverted truncated cone recess, or an inverted conical recess.

[0025] In some embodiments, a passivation layer is further included that grows conformally to the pyramid structure and the protrusions and / or pits, the passivation layer having an average thickness of 130 nm to 155 nm.

[0026] In some embodiments, the passivation layer includes a first passivation layer disposed on the protrusions and / or pits, and a second passivation layer disposed on the pyramid structure; Along the thickness direction, the thickness variation rate of the first passivation layer is ≤5%, and the thickness variation rate of the second passivation layer is ≥3%.

[0027] In some embodiments, the angle of the pyramid apex is 20°~40°, and the height is 2.5μm~4μm; The base side length of the pyramid structure is 2.5μm~5μm; The top of the pyramid structure has rounded corners; The sidewalls of the pyramid structure have edges that are rounded off. The radius of curvature of the smooth apex and / or smooth edge is 50nm~1000nm.

[0028] In some embodiments, the angle between the sidewall of the pyramid structure and the plane of the silicon substrate is the angle between the line connecting the top vertex and the bottom endpoint of the pyramid structure and the plane of the silicon substrate, and the angle between the sidewall of the pyramid structure and the plane of the silicon substrate is 35° to 80°.

[0029] In some embodiments, a transition region is formed between the sidewall of the pyramid structure and the plane of the silicon substrate, and a third protrusion is formed on the transition region. The average height difference h3 of the third protrusion is 1 nm to 20 nm, and h3 ≤ h1 ≤ h2.

[0030] In some embodiments, the third protrusion includes a third sidewall and a third bottom surface, the bottom edge of the third bottom surface has a side length of W3, the height of the third protrusion is H3, and the aspect ratio H3 / W3 of a single third protrusion is 0.2~0.3.

[0031] In some embodiments, the radius of curvature of the top of the third protrusion is 80~150nm.

[0032] In some embodiments, the third protrusion is a polyhedral structure, a frustum-shaped structure, or a conical structure.

[0033] In some embodiments, a third pit is formed on the transition region, and the average depth of the third pit is 1 nm to 20 nm.

[0034] In some embodiments, the third recess includes a third sidewall, a third bottom surface, and a third opening. The side length of the projection profile of the third opening onto the third bottom surface is W31, the side length of the third bottom surface is W32, the depth of the third recess is D3, and the depth-to-width ratio of a single third recess is D3 / W31 = 0.3~0.4, where W31 ≥ W32.

[0035] In some embodiments, the third recess is a polygonal recess, an inverted truncated cone recess, or an inverted conical recess.

[0036] In a second aspect, the present invention provides a solar cell module, including the solar cell as described in the first aspect.

[0037] Thirdly, the present invention provides a solar cell system comprising a solar cell as described in the first aspect or containing a solar cell module as described in the second aspect.

[0038] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention constructs a secondary rough surface of "micron-level pyramid structure + nano-level protrusions" by directly forming nano-sized protrusions on the pyramid textured surface, which breaks through the single pyramid structure, increases the diffuse reflection path of light, reduces reflectivity, and improves light absorption efficiency and battery conversion performance. Moreover, the protrusions are formed directly on the pyramid structure, rather than by spraying or depositing nanoparticles on the surface of the pyramid structure, which improves the stability of the structure and increases the reliability of the solar cell.

[0039] (2) This invention forms island-shaped protrusions directly on the pyramid structure through etching, which can precisely control the anisotropic etching of silicon. It forms nanoscale protrusions while avoiding uncontrolled pyramid size, thus solving the "size-emissivity" contradiction of traditional etching. Moreover, the process has good stability and is easy to control in mass production. In addition, this invention only improves the textured surface structure of the solar cell, without requiring large-scale adjustments to the cell process. It has strong compatibility and can be quickly applied to existing monocrystalline silicon solar cell production lines, possessing high industrialization potential.

[0040] (3) The present invention forms protrusions of different shapes in different regions of the pyramid structure, specifically including a first protrusion formed at the top of the pyramid structure, a second protrusion formed on the sidewall of the pyramid structure, and a third protrusion formed in the transition region between the sidewall of the pyramid structure and the plane where the silicon substrate is located. Under the synergistic effect of the first protrusion, the second protrusion and the third protrusion can increase the number of scattering and reflection of light incident on different regions, increase the diffuse reflection path of light, and further reduce the reflectivity.

[0041] (4) The present invention directly forms protrusions and pits in the pyramid structure. The pits and protrusions form a continuously changing curved surface, which increases the diffuse reflection path of light, further reduces the reflectivity, and improves the battery conversion efficiency. Attached Figure Description

[0042] Figure 1 This is a cross-sectional micrograph of an embodiment of a pyramid structure on a silicon substrate; Figure 2 This is a planar micrograph of an embodiment of a pyramid structure on a silicon substrate; Figure 3 This is a cross-sectional micrograph of another embodiment of the pyramid structure on a silicon substrate; Figure 4 This is a planar micrograph of another embodiment of the pyramid structure on a silicon substrate; Figure 5 This is a magnified view of a portion of the pyramid structure on a silicon substrate. Figure 6 This is another enlarged view of a portion of the pyramid structure on a silicon substrate. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the invention, and should not be construed as limiting the invention. Furthermore, it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0044] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0045] Furthermore, 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0046] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0047] In this invention, "preferred" and "more preferred" are merely descriptions of better implementation methods or embodiments, and should be understood as not constituting a limitation on the scope of protection of this invention. In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features. In this invention, numerical ranges are involved; unless otherwise specified, they include the two endpoints of the numerical range.

[0048] In the description of this specification, the references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0049] like Figures 1-4As shown, the present invention provides a solar cell, comprising: a silicon substrate 1 and a pyramid structure 2 disposed on the surface of the silicon substrate 1, wherein the surface of the pyramid structure 2 is formed with protrusions 3, and the average height of the protrusions 3 is 1 nm to 50 nm.

[0050] The average height of the protrusion 3 is 1nm to 50nm, for example, it can be 1nm, 2nm, 4nm, 5nm, 6nm, 8nm, 10nm, 20nm, 30nm, 40nm, or 50nm, but it is not limited to the listed values; other unlisted values ​​within this range are also applicable. Preferably, the average height of the protrusion 3 is 5nm to 45nm. More preferably, the average height of the protrusion 3 is 10nm to 40nm.

[0051] It should be noted that, in this invention, the height of the protrusion 3 is the vertical distance between the highest point of the protrusion and the surface of the pyramid structure, and the average height of the protrusion 3 is the average of the vertical distances between the highest points of multiple protrusions and the surface of the pyramid structure.

[0052] This invention constructs a secondary rough surface of "micron-level pyramid structure + nano-level protrusions" by directly forming nanoscale protrusions 3 on a pyramid-shaped textured surface. This breaks through the limitations of a single pyramid structure, increases the diffuse reflection path of light, reduces reflectivity, and improves light absorption efficiency and battery conversion performance. The average height of the protrusions 3 is 1nm~50nm. Combined with the micron-level pyramid structure, the pyramid height is generally 2.5μm~4μm. The average height of the protrusions accounts for 1:50~1:4000 of the pyramid height, which allows light reflected to the pyramid surface to be reflected multiple times, significantly increasing the diffuse reflection path and reducing reflectivity. When the height of the protrusions is <1nm, there is a technical problem of excessively high frontal reflectivity leading to low photoelectric efficiency; when the height of the protrusions is >50nm, there is a technical problem of poor Al2O3 and SiNx coverage, passivation failure, and reduced power-off efficiency. Preferably, the average height of the protrusions accounts for 1:50~1:1000 of the pyramid height. More preferably, the average height of the protrusions accounts for 1:50~1:500 of the pyramid height.

[0053] The protrusion 3 is formed directly on the pyramid structure 2, rather than by spraying or depositing nanoparticles onto the surface of the pyramid structure, thus improving the stability of the structure. Compared with existing technologies that spray silica nanoparticles onto the pyramid structure or deposit metal nanoparticles onto the dielectric layer of a silicon wafer and then form a light-trapping textured surface through plasma etching, this invention can simultaneously achieve high stability and low reflectivity, resolving the "size-emissivity" contradiction of traditional etching.

[0054] In some embodiments, the solar cell includes a passivation layer disposed on the pyramid structure and the raised surface. The passivation layer may be an Al₂O₃ layer or a SiN layer. x One or a combination of layers, but not limited to this.

[0055] This invention constructs a secondary rough surface of "micron-level pyramid structure + nano-level protrusions" by directly forming nanoscale protrusions on a pyramid-shaped surface, thereby achieving a reflectivity of 1.5%-8.5% on the surface of the pyramid structure 2. For example, it can be 1.5%, 2.5%, 3.5%, 4.5%, 5.5%, 6.5%, 7.5%, or 8.5%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. Preferably, the reflectivity of the surface of the pyramid structure 2 is 2.0%-7.5%. More preferably, the reflectivity of the surface of the pyramid structure 2 is 2.5%-5.5%.

[0056] It should be noted that the reflectivity of the surface of the pyramid structure 2, i.e. the reflectivity of the pyramid velvet surface, refers to its average surface reflectivity in the wavelength range of 400 nm to 1050 nm.

[0057] In some embodiments, the present invention can form different protrusions 3 on the pyramid structure 2 in different regions, which can lengthen the diffuse reflection path of light in different regions and reduce reflectivity. Preferably, multiple protrusions are distributed in at least one of the following regions of the pyramid structure 2: (1) The top of pyramid structure 2; (2) The side walls of pyramid structure 2; and (3) The transition area between the sidewall of the pyramid structure 2 and the plane where the silicon substrate is located.

[0058] It should be noted that the boundary lines between the top, side walls, and transition areas of the pyramid structure can be defined according to the actual situation. As an optional embodiment, the area located at the top of the pyramid structure and accounting for 5% to 10% of the pyramid's height is defined as the top of pyramid structure 2; The area located at the bottom of the pyramid structure and accounting for 5% to 10% of the pyramid height is defined as the bottom of the side wall of the pyramid structure 2. The transition area between the side wall of the pyramid structure 2 and the plane where the silicon substrate is located can be understood as the transition area between the bottom of the side wall of the pyramid structure 2 and the plane where the silicon substrate is located.

[0059] In some embodiments, the protrusion 3 includes at least one of the following protrusions: A first protrusion 31 is formed on the top 21 of the pyramid structure, and the average height h1 of the first protrusion 31 is 1nm~30nm; The second protrusion 32 is formed on the side wall 22 of the pyramid structure, and the average height of the second protrusion 32 is h2, which is 10nm~50nm. A third protrusion 33 is formed in the transition region 23 between the sidewall of the pyramid structure and the plane of the silicon substrate, and the average height difference h3 of the third protrusion 33 is 1nm~20nm.

[0060] In this embodiment, at least one nano-sized protrusion is formed in the sidewall, top, and transition region of the pyramid structure to construct a secondary rough surface of "micron-level pyramid structure + nano-level protrusion". This can make full use of the characteristics of different light paths irradiating the sidewall, top, and transition region of the pyramid structure. By setting different protrusions in the sidewall, top, and transition region of the pyramid structure, the diffuse reflection path of light is further increased, the reflectivity is reduced, and the light absorption efficiency and battery conversion performance are improved.

[0061] In some embodiments, such as Figure 5 As shown, the protrusion 3 includes a sidewall and a bottom surface. The bottom edge of the bottom surface has a side length of W, the height of the protrusion is H, and the aspect ratio H / W of the protrusion is 0.1-0.4. By forming a protrusion with a specific aspect ratio on the basis of a pyramid, this textured structure increases the probability of multiple reflections of light hitting the solar cell, significantly improving the anti-reflection effect, thereby increasing the short-circuit current of the solar cell and improving its light conversion efficiency.

[0062] In some embodiments, the protrusion 3 is an island-shaped protrusion, which is independent of each other and dispersed on the surface of the pyramid structure 2. The present invention forms a plurality of three-dimensional, scattered island-shaped protrusions on the surface of the pyramid structure 2, which can not only increase the diffuse reflection path of light, but also relieve the compressive stress of the silicon substrate.

[0063] Preferably, the distribution density of the protrusions is 100 per μm. 2 -180 cells / μm 2 .

[0064] This invention directly forms island-shaped protrusions on a pyramid structure through etching, enabling precise control of anisotropic etching of silicon. This results in nanoscale protrusions while avoiding uncontrolled pyramid size, resolving the "size-emissivity" contradiction inherent in traditional etching. Furthermore, the process exhibits good stability and facilitates process control in mass production. Moreover, this invention only improves the textured surface structure of the solar cell, requiring no large-scale adjustments to the cell manufacturing process. It boasts strong compatibility and can be quickly applied to existing monocrystalline silicon solar cell production lines, demonstrating significant industrialization potential. Compared to strip-shaped or ribbed protrusions, the island-shaped protrusions of this invention are independent of each other, effectively increasing the diffuse reflection path of light and reducing reflectivity. The reflectivity of the pyramid structure surface can be as low as 1.5%-7.5%.

[0065] In some embodiments, the surface of the pyramid structure 2 is further formed with pits 4, the average depth of which is 1 nm to 50 nm. The pits 4 and the protrusions 3 form a continuously varying curved surface, increasing the diffuse reflection path of light, further reducing reflectivity, and improving the cell conversion efficiency. Moreover, pits and protrusions of different sizes and shapes can form curved surfaces with different trends, meeting the requirements of solar cells for the reflectivity of the pyramid textured surface under different conditions.

[0066] In some embodiments, the average depth of the pit 4 is 1 nm to 50 nm, for example, it can be 1 nm, 2 nm, 4 nm, 5 nm, 6 nm, 8 nm, 10 nm, 20 nm, 30 nm, 40 nm, or 50 nm, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. Preferably, the average depth of the pit 4 is 5 nm to 40 nm. More preferably, the average depth of the pit 4 is 10 nm to 30 nm.

[0067] It should be noted that, in this invention, the depth of the pit 4 is specifically the vertical distance between the lowest point of the pit and the surface of the pyramid structure, and the average depth of the pit 4 is specifically the average value of the vertical distances between the lowest points of multiple pits and the surface of the pyramid structure.

[0068] In some embodiments, such as Figure 6 As shown, the recess 4 includes sidewalls, a bottom surface, and an opening. The side length of the projection of the opening onto the bottom surface is W1, the side length of the bottom surface is W2, and the depth of the recess is D. The aspect ratio of a single recess is D / W1 = 0.25-0.45, and W1 ≥ W2. The side length of the opening of the recess is greater than the side length of the bottom surface, forming an inclined sidewall. This bowl-shaped recess allows more light to be reflected into its interior. Simultaneously, the bowl-shaped recess has a suitable aspect ratio, increasing the number of scattering and reflections of light incident into the recess, further reducing reflectivity and improving battery conversion efficiency.

[0069] In some embodiments, the pit 4 includes at least one of the following pits: A first recess 41 is formed at the top 21 of the pyramid structure, and the average depth of the first recess 41 is 1nm~30nm; A second recess 42 is formed on the sidewall 22 of the pyramid structure, and the average depth of the second recess 42 is 10nm~50nm; A third pit 43 is formed in the transition region 23 between the sidewall of the pyramid structure and the plane of the silicon substrate, and the average depth of the third pit 43 is 1nm~20nm.

[0070] In some embodiments, the angle of the apex of the pyramid structure 2 is 20° to 40°, for example, it can be 20°, 22°, 25°, 26°, 28°, 30°, 32°, 35°, 38°, or 40°, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. Preferably, the angle of the apex of the pyramid structure is 20° to 30°. More preferably, the angle of the apex of the pyramid structure is 20° to 26°.

[0071] The height of the pyramid structure 2 is 2.5μm to 4μm, for example, it can be 2.5μm, 3μm, 3.2μm, 3.4μm, 3.6μm, 3.8μm, or 4μm, but it is not limited to the listed values; other unlisted values ​​within this range are also applicable. Preferably, the height of the pyramid structure is 2.8μm to 3.8μm. More preferably, the height of the pyramid structure is 3μm to 3.5μm.

[0072] The base side length of the pyramid structure 2 is 2.5μm to 5μm, for example, it can be 2.5μm, 3μm, 3.2μm, 3.4μm, 3.6μm, 3.8μm, 4μm, 4.2μm, 4.4μm, 4.6μm, 4.8μm, or 5μm, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. Preferably, the base side length of the pyramid structure 2 is 3μm to 4.5μm. More preferably, the base side length of the pyramid structure 2 is 3.5μm to 4.5μm.

[0073] This invention coordinates the angle of the pyramid apex, the length of the base, and the height of the pyramid structure 2 to give the pyramid structure 2 a steeper velvety surface structure. This velvety surface structure increases the probability of multiple reflections of light hitting the solar cell, significantly improving the anti-reflection effect, thereby increasing the short-circuit current of the solar cell and improving the light conversion efficiency of the solar cell.

[0074] In some embodiments, the top of the pyramid structure 2 is a rounded apex; the sidewalls of the pyramid structure have edges, which are rounded corners. Preferably, the radius of curvature of the rounded apex and / or the rounded corners is 50nm~1000nm, which ensures low reflectivity while avoiding problems such as exposed pyramid tops and uneven film layers on the pyramid textured surface during later coating.

[0075] In some embodiments, the angle α between the sidewall 22 of the pyramid structure 2 and the plane where the silicon substrate 10 is located is the angle between the line connecting the top vertex and the bottom endpoint of the pyramid structure and the plane where the silicon substrate is located, and the angle between the sidewall of the pyramid structure and the plane where the silicon substrate is located is 35°~80°.

[0076] In some embodiments, the protrusions and / or pits on the surface of the pyramid structure are formed by etching, preferably by alkaline etching.

[0077] Optionally, the present invention may employ a secondary alkaline etching process with tiered alkaline concentrations, comprising: performing preliminary alkaline texturing on a silicon substrate to form a pyramid structure on the surface of the silicon substrate; performing a primary cleaning on the silicon substrate after preliminary alkaline texturing; and performing secondary alkaline etching on the silicon substrate after the primary cleaning to form protrusions and / or pits on the surface of the pyramid structure, wherein the alkaline concentration used in the secondary alkaline etching is lower than that used in the preliminary alkaline texturing.

[0078] Optionally, the preliminary alkaline texturing process uses a texturing alkaline solution to form a pyramid structure on the surface of the silicon substrate. The solute in the texturing alkaline solution includes at least one of NaOH, KOH, NH4OH, or TMAH, and the volume concentration of the solute in the texturing alkaline solution is 1%-5%. The texturing treatment is carried out at a temperature of 50-90°C for 300-1200 seconds.

[0079] Optionally, in the secondary alkaline etching, an etching alkaline solution is used for etching treatment to form protrusions and / or pits on the surface of the pyramid structure. The solute in the etching alkaline solution includes at least one of NaOH, KOH, NH4OH, or TMAH. The volume concentration of the solute in the etching alkaline solution is 0.1%-4%. The etching treatment temperature is 25-60℃, and the time is 20-300s.

[0080] The present invention will be further described below with reference to various embodiments. Example 1 A solar cell, comprising: A silicon substrate 1 and a pyramid structure 2 disposed on the surface of the silicon substrate 1. The surface of the pyramid structure 2 is formed with protrusions 3. The protrusions 3 include a second protrusion 32 formed on the sidewall 22 of the pyramid structure 2. The average height of the second protrusion 32 is h2, which is 10nm~50nm.

[0081] The sidewalls of the pyramid structure are concentrated areas of diffuse light reflection. This invention constructs a secondary rough surface of "micron-level pyramid structure + nano-level protrusions" by directly forming nano-sized protrusions 3 on the sidewalls of the pyramid structure. This breaks through the single pyramid structure, increases the diffuse light reflection path, reduces reflectivity, and improves light absorption efficiency and battery conversion performance.

[0082] In some embodiments, the second protrusion 32 includes a second sidewall and a second bottom surface. The bottom edge of the second bottom surface has a side length of W2, and the height of the second protrusion is H2. The aspect ratio H2 / W2 of a single second protrusion is 0.2 to 0.4. The sidewall of the pyramid structure is provided with a second protrusion having a large aspect ratio and a steeper textured surface. This textured surface increases the probability of multiple reflections of light hitting the solar cell, significantly improving the anti-reflection effect, thereby increasing the short-circuit current of the solar cell and improving its light conversion efficiency.

[0083] In some embodiments, the radius of curvature of the top of the second protrusion 32 is 40nm~100nm, which ensures low reflectivity while avoiding problems such as exposed pyramid tops and uneven film layers on the pyramid textured surface during later coating.

[0084] In some embodiments, the second protrusion 32 is a polyhedral structure, a frustum structure, or a conical structure, but is not limited thereto.

[0085] Example 2 A solar cell, comprising: A silicon substrate 1 and a pyramid structure 2 disposed on the surface of the silicon substrate 1, wherein a protrusion 3 is formed on the surface of the pyramid structure 2, the protrusion 3 comprising: The first protrusion 31 formed on the top 21 of the pyramid structure 2 has an average height h1 of 1nm~30nm; The second protrusion 32 is formed on the side wall 22 of the pyramid structure 2, and the average height of the second protrusion 32 is h2, which is 10nm~50nm.

[0086] Compared with Example 1, this example forms a first protrusion 31 and a second protrusion 32 with nanoscale dimensions on the top and sidewalls of the pyramid structure, constructing a secondary rough surface of "micron-scale pyramid structure + nanoscale protrusion". This can make full use of the characteristics of different light paths irradiating the sidewalls and top of the pyramid structure. By setting different protrusions on the sidewalls and top of the pyramid structure, the diffuse reflection path of light is further increased, the reflectivity is reduced, and the light absorption efficiency and battery conversion performance are improved.

[0087] In some embodiments, the average height of the first protrusion 31 is h1, and the average height of the second protrusion 32 is h2, where h1 ≤ h2. This balances the requirements for increasing diffuse reflection paths in different regions and structural stability. The first protrusion 31 located at the top 21 has a smaller height, which satisfies the diffuse reflection requirement of incident light from the top while avoiding the formation of an overly steep protrusion at the top, which would affect the stability of the structure and the uniformity of the subsequent passivation film deposition.

[0088] In some embodiments, the first protrusion 31 includes a first sidewall and a first bottom surface, the bottom edge of the first bottom surface has a side length of W1, the height of the first protrusion is H1, and the aspect ratio H1 / W1 of a single first protrusion is 0.1 to 0.2. The second protrusion 32 includes a second sidewall and a second bottom surface, the bottom edge of the second bottom surface has a side length of W2, the height of the second protrusion is H2, and the aspect ratio H2 / W2 of a single second protrusion is 0.2 to 0.4.

[0089] The pyramid structure has a second protrusion 32 with a larger aspect ratio on its sidewalls and a first protrusion 31 with a smaller aspect ratio on its top. The second protrusion 32 has a steeper textured surface, while the first protrusion 31 has a gentler textured surface. This textured surface further increases the probability of multiple reflections of light hitting the solar cell, thus significantly improving the anti-reflection effect.

[0090] In some embodiments, the radius of curvature of the top of the first protrusion 31 is 80nm~200nm, and the radius of curvature of the top of the second protrusion 32 is 50nm~100nm. This can meet the light diffuse reflection requirements of different areas, and while ensuring low reflectivity, avoid the problems of exposed top of the protrusion and uneven film layer on the pyramid textured surface in the later coating.

[0091] In some embodiments, the first protrusion 31 and / or the second protrusion 32 are polyhedral structures, frustum structures, or conical structures, but are not limited thereto.

[0092] Example 3 A solar cell, comprising: A silicon substrate 1 and a pyramid structure 2 disposed on the surface of the silicon substrate 1. The surface of the pyramid structure 2 is formed with protrusions 3 and pits 4. The protrusions 3 include a second protrusion 32 formed on the sidewall 22 of the pyramid structure 2. The pits 4 include a second pit 42 formed on the sidewall 22 of the pyramid structure 2. The average height h2 of the second protrusions 32 is 10nm~50nm, and the average depth of the second pits 42 is 10nm~50nm.

[0093] Compared to Example 1, this example not only forms nanoscale protrusions directly on the sidewalls of the pyramid structure, but also forms nanoscale pits. This example constructs a three-level rough surface of "micrometer-scale pyramid structure + nanoscale protrusions + nanoscale pits", which further increases the diffuse reflection path of light, reduces reflectivity, and improves light absorption efficiency and battery conversion performance.

[0094] In some embodiments, the second protrusion 32 includes a second sidewall and a second bottom surface. The bottom edge of the second bottom surface has a side length of W2, and the height of the second protrusion is H2. The aspect ratio H2 / W2 of a single second protrusion is 0.2 to 0.4. The sidewall of the pyramid structure is provided with a second protrusion having a large aspect ratio and a steeper textured surface. This textured surface increases the probability of multiple reflections of light hitting the solar cell, significantly improving the anti-reflection effect, thereby increasing the short-circuit current of the solar cell and improving its light conversion efficiency.

[0095] In some embodiments, the radius of curvature of the top of the second protrusion 32 is 40nm~100nm, which ensures low reflectivity while avoiding problems such as exposed pyramid tops and uneven film layers on the pyramid textured surface during later coating.

[0096] In some embodiments, the second protrusion 32 is a polyhedral structure, a frustum structure, or a conical structure, but is not limited thereto.

[0097] In some embodiments, the second recess 42 includes a second sidewall, a second bottom surface, and a second opening. The side length of the projected outline of the second opening on the second bottom surface is W21, the side length of the second bottom surface is W22, the depth of the second recess is D2, and the aspect ratio of a single second recess is D2 / W21 = 0.3~0.45, where W21 ≥ W22. The side length of the second opening of the second recess 42 is greater than the side length of the second bottom surface, forming an inclined second sidewall. This bowl-shaped recess allows more light to be reflected into the recess. Simultaneously, the bowl-shaped recess has a large aspect ratio, increasing the number of scattering and reflections of light incident into the recess, further reducing reflectivity and improving battery conversion efficiency.

[0098] In some embodiments, the second recess 42 is a polygonal recess, an inverted truncated cone recess, or an inverted conical recess, but is not limited thereto.

[0099] Example 4 A solar cell, comprising: A silicon substrate 1 and a pyramid structure 2 disposed on the surface of the silicon substrate 1, wherein the surface of the pyramid structure 2 has protrusions 3 and pits 4, wherein... The protrusion 3 includes a first protrusion 31 formed on the top 21 of the pyramid structure 2 and a second protrusion 32 formed on the side wall 22 of the pyramid structure 2. The average height h1 of the first protrusion 31 is 1nm~30nm; the average height h2 of the second protrusion 32 is 10nm~50nm.

[0100] The pit 4 includes a first pit 41 formed on the top of the pyramid structure and a second pit 42 formed on the side wall 22 of the pyramid structure 2. The average depth of the first pit 41 is 1nm~30nm and the average depth of the second pit 42 is 10nm~50nm.

[0101] Compared with Embodiment 2, this embodiment adds a first pit 41 and a second pit 42, that is, protrusions 3 and pits 4 with nanoscale dimensions are formed on the side wall and top of the pyramid structure, constructing a three-level rough surface of "micron-scale pyramid structure + nanoscale protrusions + nanoscale pits". By setting different protrusions and pits on the side wall and top of the pyramid structure, the diffuse reflection path of light is further increased, the reflectivity is reduced, and the light absorption efficiency and battery conversion performance are improved.

[0102] It should be noted that the technical details of the first protrusion 31 and the second protrusion 32 in this embodiment are the same as those in Embodiment 2, and will not be repeated here. The first recess 41 and the second recess 42 will be described in detail below.

[0103] In some embodiments, the second recess 42 includes a second sidewall, a second bottom surface, and a second opening. The side length of the projected outline of the second opening on the second bottom surface is W21, the side length of the second bottom surface is W22, the depth of the second recess is D2, and the aspect ratio of a single second recess is D2 / W21 = 0.3~0.45, where W21 ≥ W22. The side length of the second opening of the second recess 42 is greater than the side length of the second bottom surface, forming an inclined second sidewall. This bowl-shaped structure of the second recess 42 allows more light to be reflected into the recess. Simultaneously, the bowl-shaped structure of the second recess 42 has a large aspect ratio, increasing the number of scattering and reflections of light incident into the recess, further reducing reflectivity and improving battery conversion efficiency.

[0104] The first recess 41 includes a first sidewall, a first bottom surface, and a first opening. The side length of the projected outline of the first opening on the first bottom surface is W11, the side length of the first bottom surface is W12, and the depth of the first recess is D1. The aspect ratio of a single first recess is D1 / W11 = 0.25~0.3, and W11 ≥ W12. The side length of the first opening of the first recess 41 is greater than the side length of the first bottom surface, forming an inclined first sidewall. This bowl-shaped structure of the first recess 41 allows more light to be reflected into the recess. At the same time, the bowl-shaped structure of the first recess 41 has a small aspect ratio, which can meet the requirements of scattering and reflection of light incident from the top of the pyramid into the recess, and also ensure the uniformity of the subsequent deposition of the passivation film.

[0105] In some embodiments, the first recess 41 and / or the second recess 42 are polygonal recesses, inverted truncated cone recesses, or inverted conical recesses, but are not limited thereto.

[0106] Example 5 A solar cell, comprising: A silicon substrate 1 and a pyramid structure 2 disposed on the surface of the silicon substrate 1, wherein a protrusion 3 is formed on the surface of the pyramid structure 2, the protrusion 3 comprising: The first protrusion 31 formed on the top 21 of the pyramid structure 2 has an average height h1 of 1nm~30nm; The second protrusion 32 is formed on the side wall 22 of the pyramid structure 2, and the average height of the second protrusion 32 is h2, which is 10nm~50nm; A third protrusion 33 is formed in the transition region 23 between the sidewall of the pyramid structure and the plane of the silicon substrate, and the average height difference h3 of the third protrusion 33 is 1nm~20nm.

[0107] Compared with Example 2, this example forms a first protrusion 31, a second protrusion 32, and a third protrusion 33 with nanoscale dimensions on the sidewalls, top, and transition region of the pyramid structure, constructing a secondary rough surface of "micron-scale pyramid structure + nanoscale protrusion". This can make full use of the characteristics of different light paths irradiating the sidewalls, top, and transition region of the pyramid structure. By setting different protrusions on the sidewalls, top, and transition region of the pyramid structure, the diffuse reflection path of light is further increased, the reflectivity is reduced, and the light absorption efficiency and battery conversion performance are improved.

[0108] In some embodiments, the average height of the first protrusion 31 is h1, the average height of the second protrusion 32 is h2, and the average height difference h3 of the third protrusion 33 is 1nm~20nm, where h3≤h1≤h2. This balances the requirements for increasing diffuse reflection paths and structural stability in different regions. The third protrusion 33 located in the transition region 23 has a smaller height, the first protrusion 31 at the top has a higher height than the third protrusion 33, and the second protrusion 32 on the sidewall has a higher height than the first protrusion 31. This satisfies the diffuse reflection requirement of light incident from the top and effectively utilizes the light incident on the transition region, further increasing the diffuse reflection path and reducing reflectivity.

[0109] In some embodiments, the first protrusion 31 includes a first sidewall and a first bottom surface. The bottom edge of the first bottom surface has a side length of W1, the height of the first protrusion is H1, and the aspect ratio H1 / W1 of a single first protrusion is 0.1~0.2. The second protrusion 32 includes a second sidewall and a second bottom surface. The bottom edge of the second bottom surface has a side length of W2, the height of the second protrusion is H2, and the aspect ratio H2 / W2 of a single second protrusion is 0.2~0.4. By providing second protrusions 32 with a larger aspect ratio on the sidewalls of the pyramid structure and first protrusions 31 with a smaller aspect ratio on the top, the second protrusion 32 has a steeper textured surface, while the first protrusion 31 has a gentler textured surface. This textured surface further increases the probability of multiple reflections of light hitting the solar cell, significantly improving the anti-reflection effect.

[0110] Generally, light incident on the transition region 23 between the sidewall of the pyramid structure and the plane of the silicon substrate is not easily reused. In this embodiment, a third protrusion 33 is formed in the transition region 23. The third protrusion 33 includes a third sidewall and a third bottom surface. The side length of the bottom edge of the third bottom surface is W3, and the height of the third protrusion is H3. The aspect ratio H3 / W3 of a single third protrusion is 0.2~0.3. By setting a third protrusion 33 with a small aspect ratio in the transition region 23 of the pyramid structure, and utilizing a smooth textured surface, the third protrusion 33 and the surface of the pyramid form a larger incident angle range, which can receive more light and further reflect it, increasing the diffuse reflection path of light.

[0111] In some embodiments, the radius of curvature of the top of the first protrusion 31 is 80nm~200nm, the radius of curvature of the top of the second protrusion 32 is 40nm~100nm, and the radius of curvature of the top of the third protrusion 33 is 80~150nm. This can meet the light diffuse reflection requirements of different areas, and while ensuring low reflectivity, avoid the problems of exposed protrusion tops and uneven film layers on the pyramid textured surface during later coating.

[0112] In some embodiments, the first protrusion 31, the second protrusion 32 and / or the third protrusion 33 are polyhedral structures, frustum structures or conical structures, but are not limited thereto.

[0113] Example 6 A solar cell, comprising: A silicon substrate 1 and a pyramid structure 2 disposed on the surface of the silicon substrate 1, wherein the surface of the pyramid structure 2 has protrusions 3 and pits 4, wherein... The protrusion 3 includes: a first protrusion 31 formed on the top 21 of the pyramid structure 2, a second protrusion 32 formed on the sidewall 22 of the pyramid structure 2, and a third protrusion 33 formed in the transition region 23 between the sidewall of the pyramid structure and the plane where the silicon substrate is located. The average height h1 of the first protrusion 31 is 1nm~30nm; the average height h2 of the second protrusion 32 is 10nm~50nm; and the average height difference h3 of the third protrusion 33 is 1nm~20nm.

[0114] The pit 4 includes a first pit 41 formed at the top of the pyramid structure, a second pit 42 formed on the sidewall 22 of the pyramid structure 2, and a third pit 43 formed in the transition region 23 between the sidewall of the pyramid structure and the plane where the silicon substrate is located. The average depth of the first pit 41 is 1nm~30nm, the average depth of the second pit 42 is 10nm~50nm, and the average depth of the third pit 43 is 1nm~20nm.

[0115] Compared with Example 5, this example adds a first pit 41, a second pit 42, and a third pit 43 to the first protrusion 31, the second protrusion 32, and the third protrusion 33. That is, protrusions and pits with nanoscale dimensions are formed on the sidewalls, top, and transition areas of the pyramid structure, constructing a three-level rough surface of "micron-scale pyramid structure + nanoscale protrusions + nanoscale pits". This can make full use of the characteristics of different light paths irradiating the sidewalls, top, and transition areas of the pyramid structure. By setting different protrusions and pits on the sidewalls, top, and transition areas of the pyramid structure, the diffuse reflection path of light is further increased, the reflectivity is reduced, and the light absorption efficiency and battery conversion performance are improved.

[0116] It should be noted that the technical details of the first protrusion 31, the second protrusion 32, and the third protrusion 33 in this embodiment are the same as those in Embodiment 5, and will not be repeated here. The first recess 41, the second recess 42, and the third recess 43 will be described in detail below.

[0117] In some embodiments, the second recess 42 includes a second sidewall, a second bottom surface, and a second opening. The side length of the projected outline of the second opening on the second bottom surface is W21, the side length of the second bottom surface is W22, the depth of the second recess is D2, and the aspect ratio of a single second recess is D2 / W21 = 0.3~0.45, where W21 ≥ W22. The side length of the second opening of the second recess 42 is greater than the side length of the second bottom surface, forming an inclined second sidewall. This bowl-shaped structure of the second recess 42 allows more light to be reflected into the recess. Simultaneously, the bowl-shaped structure of the second recess 42 has a large aspect ratio, increasing the number of scattering and reflections of light incident into the recess, further reducing reflectivity and improving battery conversion efficiency.

[0118] The first recess 41 includes a first sidewall, a first bottom surface, and a first opening. The side length of the projected outline of the first opening on the first bottom surface is W11, the side length of the first bottom surface is W12, and the depth of the first recess is D1. The aspect ratio of a single first recess is D1 / W11 = 0.25~0.3, and W11 ≥ W12. The side length of the first opening of the first recess 41 is greater than the side length of the first bottom surface, forming an inclined first sidewall. This bowl-shaped structure of the first recess 41 allows more light to be reflected into the recess. At the same time, the bowl-shaped structure of the first recess 41 has a small aspect ratio, which can meet the requirements of scattering and reflection of light incident from the top of the pyramid into the recess, and also ensure the uniformity of the subsequent deposition of the passivation film.

[0119] The third recess 43 includes a third sidewall, a third bottom surface, and a third opening. The side length of the projected outline of the third opening on the third bottom surface is W31, the side length of the third bottom surface is W32, and the depth of the third recess is D3. The aspect ratio of a single third recess is D3 / W31 = 0.3~0.4, and W31 ≥ W32. The side length of the third opening of the third recess 43 is greater than the side length of the third bottom surface, forming an inclined third sidewall. This bowl-shaped structure of the third recess 43 allows more light to be reflected into the recess. At the same time, the bowl-shaped structure of the third recess 43 has a small aspect ratio, which can meet the requirements of scattering and reflection of light incident into the recess in the pyramid transition area, and also ensure the uniformity of the subsequent deposition of the passivation film.

[0120] In some embodiments, the first recess 41, the second recess 42, and / or the third recess 43 are polygonal recesses, inverted truncated cone recesses, or inverted conical recesses, but are not limited thereto.

[0121] Example 7 Based on the solar cell described in any one of Embodiments 1 to 6, a passivation layer is further included that grows conformally to the pyramid structure and the protrusions and / or pits, the passivation layer having an average thickness of 130~150 nm.

[0122] In some embodiments, the thickness variation rate of the passivation layer along the thickness direction is ≤5%, that is, the thickness of the passivation layer at its thickest point differs from that at its thinnest point by no more than 5%.

[0123] In this embodiment, the passivation layer grows conformally to the protrusions and / or pits, and its thickness is relatively uniform. This maximizes the utilization of the diffuse reflection effect formed between the protrusions and pits, thereby reducing the reflectivity.

[0124] Example 8 Based on the solar cell described in any one of Embodiments 1 to 6, a passivation layer is further provided on the pyramid structure and the protrusions and / or pits, the passivation layer having an average thickness of 145 nm to 155 nm.

[0125] In some embodiments, the passivation layer includes a first passivation layer disposed on the protrusions and / or pits, and a second passivation layer disposed on the pyramid structure.

[0126] Along the thickness direction, the thickness variation rate of the first passivation layer is ≤5%, meaning that the thickness of the first passivation layer at its thickest point differs from that at its thinnest point by no more than 5%. This passivation layer grows conformally to the protrusions and / or pits, resulting in a relatively uniform thickness. This maximizes the utilization of the diffuse reflection effect formed between the protrusions and pits, thereby reducing reflectivity.

[0127] Along the thickness direction, the thickness variation rate of the second passivation layer is ≥3%, that is, the thickness of the second passivation layer in the pyramid structure is not uniform, and protrusions can be formed on the second passivation layer, which can further increase the diffuse reflection path of light and reduce the reflectivity.

[0128] Example 9 A method for fabricating a solar cell, comprising: (1) The silicon substrate is initially texturized with alkali to form a pyramid structure on the surface of the silicon substrate; (2) The silicon substrate that has undergone preliminary alkaline texturing is cleaned once; (3) The silicon substrate after the first cleaning is subjected to a second alkaline etching to form protrusions and / or pits on the surface of the pyramid structure. (4) The silicon substrate that has undergone secondary alkaline etching is cleaned a second time; The alkaline solution concentration used in the secondary alkaline etching is lower than that used in the initial alkaline texturing.

[0129] Specifically, in the preliminary alkaline texturing process, a texturing alkaline solution is used for texturing treatment to form a pyramid structure on the surface of the silicon substrate. The solute in the texturing alkaline solution includes at least one of NaOH, KOH, NH4OH, or TMAH, and the volume concentration of the solute in the texturing alkaline solution is 1%-5%. The texturing treatment temperature is 50-90℃, and the time is 300-1200s.

[0130] In the secondary alkaline etching process, an etching alkaline solution is used for etching treatment to form protrusions and / or pits on the surface of the pyramid structure. The solute in the etching alkaline solution includes at least one of NaOH, KOH, NH4OH or TMAH, and the volume concentration of the solute in the etching alkaline solution is 0.1%-4%. The etching treatment temperature is 25-60℃ and the time is 20-300s.

[0131] Optionally, the texturing alkaline solution may also contain additive A, and additive A includes at least one of surfactant, dispersant or emulsifier, wherein the volume concentration of additive A in the texturing alkaline solution is 0.1%-2%.

[0132] Optionally, the etching alkaline solution may also contain additive B, and additive B includes at least one of carboxymethyl cellulose, sodium lignosulfonate, dipropylene glycol ethyl ether, tannic acid, defoamer or preservative, and the volume concentration of additive B in the etching alkaline solution is 0.1%-2%.

[0133] Optionally, the primary cleaning includes, but is not limited to, deionized water cleaning, hydrogen peroxide cleaning, ozone cleaning, and hydrogen fluoride cleaning; the secondary cleaning includes, but is not limited to, deionized water cleaning, cleaning with a mixture of alkali and hydrogen peroxide, ozone cleaning, and hydrogen fluoride cleaning.

[0134] Example 10 The present invention provides a solar cell module, comprising the solar cell described in any one of Embodiments 1 to 8.

[0135] Understandably, the solar cell module may also include a metal frame, front panel, back panel, and encapsulant film, or other necessary components.

[0136] Example 11 The present invention provides a solar cell system, including a solar cell module as described in Example 9.

[0137] In this embodiment, the solar cell system can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. It can also be applied to equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the solar cell system are not limited to these; that is, the solar cell system can be applied in all fields that require solar energy for power generation. Taking a photovoltaic power generation system grid as an example, the photovoltaic system may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.

[0138] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A solar cell, characterized in that, include: silicon substrate; A pyramid structure is disposed on the surface of the silicon substrate, the surface of the pyramid structure having protrusions, the average height of the protrusions being 1 nm to 50 nm.

2. The solar cell according to claim 1, characterized in that, The protrusions are island-shaped protrusions, and the distribution density of the protrusions is 100 per μm. 2 ~180 cells / μm 2 .

3. The solar cell according to claim 1, characterized in that, The reflectivity of the pyramid structure surface is 1.5% to 8.5%.

4. The solar cell according to claim 1, characterized in that, The protrusion includes a first protrusion formed on the top of the pyramid structure, the average height h1 of the first protrusion being 1nm~30nm.

5. The solar cell according to claim 4, characterized in that, The first protrusion includes a first sidewall and a first bottom surface. The bottom edge of the first bottom surface has a side length of W1, and the height of the first protrusion is H1. The aspect ratio of a single first protrusion, H1 / W1, is 0.1 to 0.

2.

6. The solar cell according to claim 4, characterized in that, The radius of curvature of the top of the first protrusion is 80 nm to 200 nm.

7. The solar cell according to claim 4, characterized in that, The protrusion includes a second protrusion formed on the sidewall of the pyramid structure, the average height of the second protrusion being h2, which is 10nm~50nm.

8. The solar cell according to claim 7, characterized in that, The average height of the first protrusion is h1, and the average height of the second protrusion is h2, where h1 ≤ h2.

9. The solar cell according to claim 7, characterized in that, The second protrusion includes a second sidewall and a second bottom surface. The bottom edge of the second bottom surface has a side length of W2, and the height of the second protrusion is H2. The aspect ratio of a single second protrusion, H2 / W2, is 0.2 to 0.

4.

10. The solar cell according to claim 7, characterized in that, The radius of curvature of the top of the second protrusion is 40nm~100nm.

11. The solar cell according to any one of claims 7 to 10, characterized in that, The first protrusion and / or the second protrusion are polyhedral structures, frustum structures, or conical structures.

12. The solar cell according to claim 1, characterized in that, The surface of the pyramid structure is also formed with pits, the average depth of which is 1nm~50nm.

13. The solar cell according to claim 12, characterized in that, The pits and the protrusions form a continuously changing curved surface.

14. The solar cell according to claim 12, characterized in that, The pit includes a first pit formed at the top of the pyramid structure, the average depth of which is 1 nm to 30 nm.

15. The solar cell according to claim 14, characterized in that, The first recess includes a first sidewall, a first bottom surface, and a first opening. The side length of the projection outline of the first opening on the first bottom surface is W11, the side length of the first bottom surface is W12, the depth of the first recess is D1, the depth-to-width ratio of a single first recess is D1 / W11 = 0.25~0.3, and W11 ≥ W12.

16. The solar cell according to claim 14, characterized in that, The pit includes a second pit formed on the sidewall of the pyramid structure, the average depth of which is 10nm~50nm.

17. The solar cell according to claim 16, characterized in that, The second recess includes a second sidewall, a second bottom surface, and a second opening. The side length of the projection outline of the second opening on the second bottom surface is W21, the side length of the second bottom surface is W22, the depth of the second recess is D2, and the depth-to-width ratio of a single second recess is D2 / W21 = 0.3~0.45, where W21 ≥ W22.

18. The solar cell according to claim 16 or 17, characterized in that, The first and / or second recess is a polygonal recess, an inverted truncated cone recess, or an inverted conical recess.

19. The solar cell according to claim 12, characterized in that, It also includes a passivation layer that grows conformally to the pyramid structure and the protrusions and / or pits, the passivation layer having an average thickness of 130nm~155nm.

20. The solar cell according to claim 19, characterized in that, The passivation layer includes a first passivation layer disposed on the protrusions and / or pits, and a second passivation layer disposed on the pyramid structure; Along the thickness direction, the thickness variation rate of the first passivation layer is ≤5%, and the thickness variation rate of the second passivation layer is ≥3%.

21. The solar cell according to any one of claims 1 to 3, characterized in that, The pyramid structure has an angle of 20° to 40° at its apex and a height of 2.5μm to 4μm. The base side length of the pyramid structure is 2.5μm~5μm; The top of the pyramid structure has rounded corners; The sidewalls of the pyramid structure have edges that are rounded off. The radius of curvature of the smooth apex and / or smooth edge is 50nm~1000nm.

22. The solar cell according to any one of claims 1 to 3, characterized in that, The angle between the sidewall of the pyramid structure and the plane of the silicon substrate is the angle between the line connecting the top vertex and the bottom endpoint of the pyramid structure and the plane of the silicon substrate, and the angle between the sidewall of the pyramid structure and the plane of the silicon substrate is 35°~80°.

23. The solar cell according to claim 8, characterized in that, A transition region is formed between the sidewall of the pyramid structure and the plane of the silicon substrate. A third protrusion is formed on the transition region. The average height difference h3 of the third protrusion is 1nm~20nm, and h3≤h1≤h2.

24. The solar cell according to claim 23, characterized in that, The third protrusion includes a third sidewall and a third bottom surface. The bottom edge of the third bottom surface has a side length of W3, and the height of the third protrusion is H3. The aspect ratio of a single third protrusion, H3 / W3, is 0.2 to 0.

3.

25. The solar cell according to claim 23, characterized in that, The radius of curvature of the top of the third protrusion is 80nm~150nm.

26. The solar cell according to claim 23, characterized in that, The third protrusion is a polyhedral structure, a frustum-shaped structure, or a conical structure.

27. The solar cell according to claim 23, characterized in that, A third recess is formed in the transition area. The third recess includes a third sidewall, a third bottom surface, and a third opening. The side length of the projection outline of the third opening onto the third bottom surface is W31, the side length of the third bottom surface is W32, the depth of the third recess is D3, and the depth-to-width ratio of a single third recess is D3 / W31 = 0.3~0.4, where W31 ≥ W32.

28. The solar cell according to claim 27, characterized in that, The third recess is a polygonal recess, an inverted truncated cone recess, or an inverted conical recess.

29. A solar cell module, characterized in that, Including the solar cell as described in any one of claims 1-28.

30. A solar cell system, characterized in that, Includes the solar cell module as described in claim 29.

Images