A solar cell and assemblies and systems thereof
By designing multi-morphological pyramid unit structures on the surface of solar cells, the reflective area is increased and the light path is extended, which solves the problem of insufficient capture of incident light at medium and high angles and improves the short-circuit current.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG AIKO SOLAR ENERGY TECH CO LTD
- Filing Date
- 2025-12-31
- Publication Date
- 2026-05-29
Smart Images
Figure CN122121349A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of solar cell technology, and relates to a solar cell, its components, and a 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. Texturing the silicon wafer surface is a core process, aiming 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% to 0.3%, making pyramid texturing optimization crucial.
[0003] In fabricating pyramidal textured surfaces for back-contact solar cells, existing texturing techniques rely on alkaline etching to form 3μm-5μm pyramidal structures with a square pyramid shape, utilizing the anisotropic etching of silicon in an alkaline solution. However, the 3μm-5μm pyramidal structure is insufficient for capturing mid-to-high angle incident light, its size and density are difficult to optimize, and the wafer reflectivity is hard to exceed the 10% threshold, thus limiting further improvements in short-circuit current. Summary of the Invention
[0004] To address the shortcomings of existing technologies, the present invention aims to provide a solar cell, its components, and a system that solves the problem of insufficient capture of incident light at medium and high angles, reduces the reflectivity of the pyramidal textured surface, and improves battery performance.
[0005] 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 first pyramid unit is disposed on the surface of the silicon substrate. The first pyramid unit is composed of at least two first pyramid structures. The tops of adjacent first pyramid structures are connected to form a convex ridge, and the bottoms of adjacent first pyramid structures partially overlap. The second pyramid unit is disposed on the surface of the silicon substrate. The second pyramid unit is composed of at least two second pyramid structures, with a recess formed between the tops of adjacent second pyramid structures and a partial overlap between the bottoms of adjacent second pyramid structures. The ratio of the total area of the first pyramid unit to the area of the silicon substrate is 30% to 90%, the ratio of the total area of the second pyramid unit to the area of the silicon substrate is 10% to 70%, the length of the longest diagonal of the base of the first pyramid unit is ≥6μm, and the length of the longest diagonal of the convex ridge is ≥1μm.
[0006] In some embodiments, the ratio of the total area of the first pyramid unit to the area of the silicon substrate is 50% to 80%; the ratio of the total area of the second pyramid unit to the area of the silicon substrate is 20% to 50%. The length of the longest diagonal at the base of the first pyramid unit is ≥6μm, and the length of the longest diagonal of the convex ridge is ≥1μm; The length of the longest diagonal of the base of the second pyramid unit is ≥6μm; the length of the longest diagonal of the recess is ≥0.5μm, and the depth of the recess is ≥0.5μm.
[0007] In some embodiments, the first pyramid unit consists of 2 to 6 first pyramid structures, with the tops of adjacent 2 to 6 first pyramid structures connected to form a convex ridge, and the bases of adjacent 2 to 6 first pyramid structures partially overlapping.
[0008] In some embodiments, the length of the longest diagonal of the base of the first pyramid unit is 6μm to 40μm, and the length of the longest diagonal of the convex ridge is 1μm to 6μm.
[0009] In some embodiments, the ridge is a protrusion extending along the connecting line between the tops of adjacent first pyramid structures, and the angle between the extension line of the ridge and the silicon substrate is 0~60°.
[0010] In some embodiments, the top of the protruding ridge is a smooth corner transition, and the radius of curvature of the smooth corner is 50nm~1000nm.
[0011] In some embodiments, the distance between the highest point of the protrusion and the silicon substrate along the thickness direction of the silicon substrate is 200 nm to 2 μm.
[0012] In some embodiments, the height of a single first pyramid structure is 200 nm to 2 μm, and the side length of the base of a single first pyramid structure is 1 to 10 μm.
[0013] In some embodiments, the intersecting edges between the bases of adjacent first pyramid structures are overlapping edges, and the length of the overlapping edges is 1~10μm.
[0014] In some embodiments, the second pyramid unit consists of 2 to 6 second pyramid structures, with a recess formed between the tops of adjacent 2 to 6 second pyramid structures, and the bases of adjacent 2 to 6 second pyramid structures partially overlapping.
[0015] In some embodiments, the length of the longest diagonal of the base of the second pyramid unit is 6μm to 40μm; the length of the longest diagonal of the recess is 2μm to 20μm; and the depth of the recess is 20nm to 2μm.
[0016] In some embodiments, the recess includes at least two sidewalls connected at their bottoms, and the included angle between the sidewalls is 0 to 79°.
[0017] In some embodiments, the height of a single second pyramid structure is 200 nm to 2 μm, and the side length of the base of a single second pyramid structure is 1 to 10 μm.
[0018] In some embodiments, the intersecting edges between the bases of adjacent second pyramid structures are overlapping edges, and the length of the overlapping edges is 1~10μm.
[0019] In some embodiments, the first pyramid structure and / or the second pyramid structure includes at least one curved side edge.
[0020] In some embodiments, a third pyramid unit disposed on the surface of the silicon substrate is further included, the third pyramid unit being composed of third pyramid structures, wherein the bases of adjacent third pyramid structures do not overlap.
[0021] In some embodiments, the ratio of the total area of the third pyramid unit to the area of the silicon substrate is 0 to 10%.
[0022] In some embodiments, the height of a single third pyramid structure is 0.3 μm to 5 μm, and the side length of the base of a single third pyramid structure is 0.3 μm to 5 μm.
[0023] Secondly, the present invention also provides a solar cell module, including the aforementioned solar cell.
[0024] Thirdly, the present invention provides a solar cell system including the aforementioned solar cell module.
[0025] Implementing this invention has the following beneficial effects: This invention provides an embodiment of a silicon substrate for solar cells, which has multiple pyramidal units of different shapes, including a first pyramidal unit and a second pyramidal unit. The first pyramidal unit consists of at least two first pyramidal structures, with the apexes of adjacent first pyramidal structures connected to form a convex ridge, and the bases of adjacent first pyramidal structures partially overlapping. Compared to existing 3μm~5μm pyramidal structures, the first pyramidal unit is composed of multiple first pyramidal structures, with the longest diagonal of the base of each first pyramidal unit being ≥6μm, and the apexes interconnected to form a convex ridge with a longest diagonal length ≥1μm. The first pyramidal unit forms a pyramidal textured surface resembling a ridge, increasing the lateral reflective area of the textured surface. The convex ridge effectively captures incident light at medium to high angles, increasing the number of scattering and reflections of light reaching the top region, reducing the reflectivity of the textured surface, and thus improving the short-circuit current of the solar cell.
[0026] The second pyramid unit consists of at least two second pyramid structures, with a recess formed between the apexes of adjacent second pyramid structures and partial overlap between the bases of adjacent second pyramid structures. The recess between the apexes of adjacent second pyramid structures allows sunlight incident on the inner wall of the pyramid structure to be reflected by the inner wall into the recess adjacent to that pyramid structure, and then continuously reflected between the apexes of adjacent pyramid structures, thus lengthening the light path and improving the effective absorption rate of sunlight. This recess can also reflect incident light reflected by the first pyramid unit again, and further reflect incident light that has not yet been reflected by the first pyramid unit, reducing the surface reflectivity and thereby increasing the short-circuit current of the solar cell.
[0027] The ratio of the total area of the first pyramid unit to the area of the silicon substrate is 30% to 90%, and the ratio of the total area of the second pyramid unit to the area of the silicon substrate is 10% to 70%. The first and second pyramid units are reasonably distributed and complement each other, which can effectively increase the number of scattering and reflection of light hitting the top and middle-high regions, reduce the reflectivity of the textured surface, and thus improve the short-circuit current of the solar cell. Attached Figure Description
[0028] Figure 1 This is a planar micrograph of an embodiment of a pyramid structure on a silicon substrate; Figure 2 This is a structural schematic diagram of an embodiment of the first pyramid unit; Figure 3 This is a top view of an embodiment of the first pyramid unit; Figure 4 This is a structural schematic diagram of another embodiment of the first pyramid unit; Figure 5This is a structural schematic diagram of an embodiment of the second pyramid unit; Figure 6 This is a top view of an embodiment of the second pyramid unit. Detailed Implementation
[0029] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.
[0030] like Figure 1 As shown, the present invention provides a solar cell, including a silicon substrate 1, a first pyramid unit 2 disposed on the surface of the silicon substrate, and a second pyramid unit 3 disposed on the surface of the silicon substrate. To better distinguish the structures of the top and bottom of the first pyramid unit 2 and the second pyramid unit 3, in this embodiment, the first pyramid unit 2 includes a first top 21 and a first bottom 23, with adjacent first tops 21 of the first pyramid structure connected to form a convex ridge 22. The second pyramid unit 3 includes a second top 31 and a second bottom 33, with adjacent second tops 31 of the second pyramid structure forming a recess 32.
[0031] Specifically, such as Figure 2-4 As shown, the first pyramid unit 2 is composed of at least two first pyramid structures, with the first tops 21 of adjacent first pyramid structures connected to form a convex ridge 22, and the first bottoms 23 of adjacent first pyramid structures partially overlapping. like Figure 5-6 As shown, the second pyramid unit 3 is composed of at least two second pyramid structures, with a recess 32 formed between the second tops 31 of adjacent second pyramid structures, and the second bottoms 33 of adjacent second pyramid structures partially overlapping.
[0032] The ratio of the total area of the first pyramid unit 2 to the area of the silicon substrate 1 is 30% to 90%, the ratio of the total area of the second pyramid unit 3 to the area of the silicon substrate 1 is 10% to 70%, the length of the longest diagonal of the first pyramid base 23 of the first pyramid unit is ≥6μm, and the length of the longest diagonal of the convex ridge 22 is ≥1μm.
[0033] The first pyramid unit 2 is composed of multiple first pyramid structures. The first apex 21 of adjacent first pyramid structures are connected to form a convex ridge 22, and the first base 23 of adjacent first pyramid structures partially overlap. The first pyramid unit 2 forms a pyramid-shaped velvet surface, which increases the lateral reflective area of the velvet structure. The convex ridge effectively captures incident light at medium and high angles, increases the number of scattering and reflections of light hitting the top area, reduces the reflectivity of the velvet surface, and thus improves the short-circuit current of the solar cell.
[0034] Compared to the existing 3μm~5μm pyramid structure, the longest diagonal of the first pyramid base 23 of the first pyramid unit is ≥6μm and can reach 40μm, increasing the size and decreasing the density of the first pyramid unit on the silicon substrate. Meanwhile, the longest diagonal of the convex ridge 22 is ≥1μm and can reach 6μm, significantly increasing the side reflection area of the pyramid textured structure and also increasing the reflection area of the top region. The convex ridge 22 effectively captures incident light at medium to high angles, increasing the number of scattering and reflections of light reaching the top region, reducing the surface reflectivity, and thus improving the short-circuit current of the solar cell.
[0035] The second pyramid unit 3 consists of at least two second pyramid structures. A recess 32 is formed between the second pyramid tops 31 of adjacent second pyramid structures, and the second pyramid bottoms 33 of adjacent second pyramid structures partially overlap. The recess 32 can reflect the incident light reflected by the first pyramid unit 2 again, and can also further reflect the incident light that has not yet been reflected by the first pyramid unit 2, thereby reducing the reflectivity of the textured surface and thus increasing the short-circuit current of the solar cell.
[0036] Compared to existing 3μm~5μm pyramid structures, the longest diagonal of the second pyramid unit's second base 33 is ≥6μm and can reach 40μm. The longest diagonal of the recess 32 is ≥0.5μm and can reach 20μm, increasing the size and decreasing the density of the second pyramid unit 3 on the silicon substrate. The second pyramid unit 3 has a recess 32 formed in the middle-high region near the top, increasing the reflective area of the middle-high region of the pyramid textured surface. The recess formed between the second apexes of adjacent second pyramid structures allows sunlight incident on the inner wall of the pyramid structure to be reflected by the inner wall and then reflected into the recess adjacent to the pyramid structure, and continuously reflected between the apexes of adjacent pyramid structures, extending the light path and improving the effective absorption rate of sunlight. The recessed portion 32 can reflect the incident light reflected by the first pyramid unit again, and can also reflect the incident light that has not yet been reflected by the first pyramid unit, increasing the number of scattering and reflection of light hitting the top and middle-high regions, reducing the reflectivity of the textured surface, and thus increasing the short-circuit current of the solar cell.
[0037] The ratio of the total area of the first pyramid unit 2 to the area of the silicon substrate 1 is 30% to 90%, and the ratio of the total area of the second pyramid unit 3 to the area of the silicon substrate 1 is 10% to 70%. The first pyramid unit 2 and the second pyramid unit 3 are reasonably distributed and complement each other, which can effectively increase the number of scattering and reflection of light hitting the top and middle-high regions, reduce the reflectivity of the textured surface, and thus improve the short-circuit current of the solar cell.
[0038] In some embodiments, the ratio of the total area of the first pyramid unit 2 to the area of the silicon substrate 1 is preferably 50% to 80%, and the ratio of the total area of the second pyramid unit 3 to the area of the silicon substrate 1 is preferably 20% to 50%. By setting a larger area first pyramid unit 2 and a smaller area second pyramid unit 3, the distribution of the first pyramid unit 2 and the second pyramid unit 3 is more reasonable. The two complement each other, which can effectively increase the number of scattering and reflection of light hitting the top area and the middle and high areas, reduce the reflectivity of the textured surface, and thus improve the short-circuit current of the solar cell.
[0039] In some embodiments, the longest diagonal of the first base 23 of the first pyramid unit is ≥6μm, and the longest diagonal of the convex ridge 22 is ≥1μm; the longest diagonal of the second base 33 of the second pyramid unit 3 is ≥6μm; the longest diagonal of the recess 32 is ≥0.5μm, and the depth of the recess 32 is ≥0.5μm. This embodiment, by limiting the length of the longest diagonal of the first base of the first pyramid unit, the length of the longest diagonal of the convex ridge, the length of the longest diagonal of the second base of the second pyramid unit, the length of the longest diagonal of the recess, and the depth of the recess (≥0.5μm), further ensures the reflective area of the recess while maintaining the side and top reflective areas of the pyramid-patterned structure. A recess is formed between the second apex of adjacent second pyramid structures, which allows sunlight incident on the inner wall of the pyramid structure to be reflected by the inner wall and into the recess adjacent to the pyramid structure. The light is then continuously reflected between the apex of adjacent pyramid structures, extending the light path and improving the effective absorption rate of sunlight.
[0040] It should be noted that the length of the longest diagonal of the first base 23 of the first pyramid unit refers to the longest diagonal line connecting any two points of the first base of the first pyramid unit, as shown by L1 in the figure. The length of the longest diagonal of the convex ridge 22 refers to the longest diagonal line connecting any two points of the end of the convex ridge, as shown by L2 in the figure. The length of the longest diagonal of the second base 33 of the second pyramid unit refers to the longest diagonal line connecting any two points of the second base 33 of the second pyramid unit, as shown by L3 in the figure; the length of the longest diagonal of the recess 32 refers to the longest diagonal line connecting any two points of the recess, as shown by L4 in the figure; the depth of the recess 32 refers to the longest vertical distance between the lowest point of the recess and the top of the pyramid structure, as shown by H in the figure.
[0041] In some embodiments, the first pyramid unit 2 is composed of 2 to 6 first pyramid structures, with the first apexes of adjacent 2 to 6 first pyramid structures 2 connected to form a convex ridge, and the first bases of adjacent 2 to 6 first pyramid structures 2 partially overlapping. Preferably, the first pyramid unit 2 is composed of 3 to 6 first pyramid structures, with the first apexes of adjacent 3 to 6 first pyramid structures 2 connected to form a convex ridge, and the first bases of adjacent 3 to 6 first pyramid structures 2 partially overlapping.
[0042] It is understood that the present invention can provide first pyramid units of various different forms, which may include one or more of the following: (1) A first pyramid unit A is composed of two first pyramid structures, wherein the length of the longest diagonal of the first base of the first pyramid unit A is ≥6μm, and the length of the longest diagonal of the convex edge is ≥1μm; (2) The first pyramid unit B is composed of three first pyramid structures, the length of the longest diagonal of the first base of the first pyramid unit B is ≥8μm, and the length of the longest diagonal of the convex edge is ≥1.5μm; (3) The first pyramid unit C is composed of four first pyramid structures, the length of the longest diagonal of the first base of the first pyramid unit C is ≥9μm, and the length of the longest diagonal of the convex edge is ≥2μm; (4) The first pyramid unit D is composed of 5 first pyramid structures, the length of the longest diagonal of the first base of the first pyramid unit D is ≥10μm, and the length of the longest diagonal of the convex edge is ≥2.5μm; (5) The first pyramid unit E is composed of 6 first pyramid structures, the length of the longest diagonal of the first base of the first pyramid unit E is ≥12μm, and the length of the longest diagonal of the convex edge is ≥3μm.
[0043] It is understandable that the proportion of the number of the first pyramid unit A, first pyramid unit B, first pyramid unit C, first pyramid unit D, and first pyramid unit E to the total number of the first pyramid units can be determined according to the actual situation, and no specific limitation is made here. For example Figure 2 , 3 As shown, Figure 2 and 3 This illustrates one implementation of the first pyramid unit, which consists of four pyramid structures with progressively increasing ridge heights (shown from left to right). Figure 4 As shown, Figure 4 Another implementation of the first pyramid unit is shown, which consists of 5 pyramid structures, with the height of the convex ridges gradually increasing and then gradually decreasing (the direction shown in the illustration is from left to right).
[0044] It should be noted that, since the protrusion is formed by connecting the first apexes 21 of adjacent first pyramid structures, and the heights of the first pyramid structures are not entirely equal, the height of the protrusion is not constant. Therefore, the height of the protrusion is the vertical distance between any point on the protrusion and the silicon substrate.
[0045] In some embodiments, the length of the longest diagonal of the first base 23 of the first pyramid unit is preferably 6μm to 40μm, specifically 6μm, 8μm, 10μm, 12μm, 15μm, 18μm, 20μm, 22μm, 25μm, 30μm, 32μm, 35μm, 38μm, or 40μm, and is not limited thereto. When the length of the longest diagonal of the first base of the first pyramid unit is less than 6μm, the side reflective area of the first pyramid structure cannot be effectively increased, the number of scattering and reflections of light incident on the side area cannot be increased, and the reflectivity of the velvet surface is reduced; when the length of the longest diagonal of the first base of the first pyramid unit is greater than 40μm, it will affect the distribution density of the first pyramid structure, thereby affecting the density of the subsequent passivation film layer and the passivation effect.
[0046] The longest diagonal of the convex ridge has a length of 1μm to 6μm, specifically 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, and 6μm, and is not limited to this. When the longest diagonal of the convex ridge is less than 1μm, it cannot effectively increase the number of scattering and reflections of light hitting the top area, thus reducing the reflectivity of the velvet surface; when the longest diagonal of the convex ridge is greater than 6μm, the size distribution of the convex ridge and the first pyramid structure is unreasonable, and it cannot balance the reflective area of the side and top areas of the velvet structure, thus reducing the reflectivity of the velvet surface.
[0047] In some embodiments, the ridge is a protrusion extending along the connecting line between the first apexes of adjacent first pyramid structures, and the angle between the extension line of the ridge and the silicon substrate is 0~60°.
[0048] Understandably, the extension line of the protruding ridge can be parallel to the silicon substrate or form an angle with the silicon substrate, with the angle being less than or equal to 60°. The protruding ridge set at an angle to the silicon substrate can form a larger reflective surface at different heights, which can effectively increase the number of scattering and reflections of light hitting the top and middle-high regions, reduce the reflectivity of the textured surface, and thus increase the short-circuit current of the solar cell.
[0049] In some embodiments, along the thickness direction of the silicon substrate, the distance between the highest point of the protrusion and the silicon substrate is 200 nm to 2 μm, preferably 500 nm to 2 μm. Generally, the height of a conventional pyramid is 2.5 μm to 4 μm. In this embodiment, the distance between the highest point of the protrusion and the silicon substrate is 200 nm to 2 μm, which can fully utilize the characteristics of different light paths irradiating the sidewalls and top of the pyramid structure. The protrusion further increases the diffuse reflection path of light, reduces reflectivity, and improves light absorption efficiency and battery conversion performance. When the distance between the highest point of the protrusion and the silicon substrate is <200 nm, the reflective area of the pyramid structure is small and cannot effectively reduce the reflectivity of the textured surface. When the distance between the highest point of the protrusion and the silicon substrate is >2 μm, there will be technical problems such as poor coverage of passivation films such as Al2O3 and SiNx, passivation failure, and reduced power-off efficiency.
[0050] It is understood that the distance between the highest point of the protrusion and the silicon substrate refers to the vertical distance between the highest point of the protrusion and the silicon substrate.
[0051] In some embodiments, the height of a single first pyramid structure is 200nm to 2μm, specifically 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1μm, 1.5μm, or 2μm, and is not limited thereto. The base length of a single first pyramid structure is 1μm to 10μm, specifically 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, or 10μm, and is not limited thereto. Different numbers of first pyramid structures overlap each other, and the tops and / or bases are connected to each other to form first pyramid units of different shapes.
[0052] The intersecting edges between the first bases 23 of adjacent first pyramid structures are overlapping edges. The length of the overlapping edges is 1μm to 10μm, specifically 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, and 10μm, and is not limited to these values. The intersection of the first bases 23 of adjacent first pyramid structures forms a groove, which allows sunlight incident on the inner wall of the pyramid structure to be reflected by the inner wall and reflected into the groove adjacent to the pyramid structure and partially overlapping at its base. This continuous reflection between adjacent pyramid structures lengthens the light path and improves the effective absorption rate of sunlight.
[0053] In some embodiments, the top of the protruding ridge 22 is a smooth corner transition, and the radius of curvature of the smooth corner is 50nm~1000nm. While ensuring low reflectivity, this avoids the problem of exposed pyramid top and uneven film layer on the pyramid textured surface during later coating.
[0054] In some embodiments, the second pyramid unit consists of 2 to 6 second pyramid structures, with a recessed portion formed between the second pyramid tops 31 of adjacent 2 to 6 second pyramid structures, and the second pyramid bases 33 of adjacent 2 to 6 second pyramid structures partially overlapping. Preferably, the second pyramid unit consists of 2 to 5 second pyramid structures, with a recessed portion 32 formed between the second pyramid tops 31 of adjacent 2 to 6 second pyramid structures, and the second pyramid bases 33 of adjacent 2 to 5 second pyramid structures partially overlapping.
[0055] It is understood that the present invention can provide second pyramid units in various different forms, which may include one or more of the following: (1) The second pyramid unit A is composed of two second pyramid structures, the length of the longest diagonal of the second base of the second pyramid unit A is ≥6μm; the length of the longest diagonal of the recess is ≥0.5μm, and the depth of the recess is ≥0.5μm; (2) The second pyramid unit B is composed of three second pyramid structures. The length of the longest diagonal of the second base of the second pyramid unit B is ≥8μm; the length of the longest diagonal of the recess is ≥1μm; and the depth of the recess is ≥0.7μm. (3) The second pyramid unit C is composed of four second pyramid structures. The length of the longest diagonal of the second base of the second pyramid unit C is ≥9μm; the length of the longest diagonal of the recess is ≥1.5μm; and the depth of the recess is ≥0.8μm. (4) The second pyramid unit D is composed of 5 second pyramid structures, the length of the longest diagonal of the second base of the second pyramid unit D is ≥10μm; the length of the longest diagonal of the recess is ≥2μm, and the depth of the recess is ≥0.9μm; (5) The second pyramid unit E is composed of 6 second pyramid structures, the length of the longest diagonal of the second base of the second pyramid unit E is ≥12μm; the length of the longest diagonal of the recess is ≥2.5μm, and the depth of the recess is ≥1.0μm; It is understandable that the proportion of the number of second pyramid units A, B, C, D, and E to the total number of second pyramid units can be determined based on the actual situation, and no specific limit is made here. For example... Figure 5 , 6 As shown, Figure 5 and 6 An embodiment of the second pyramid unit is shown, which consists of two pyramid structures with a recess formed between them.
[0056] In some embodiments, the length of the longest diagonal of the second base 33 of the second pyramid unit is 6μm to 40μm, specifically 6μm, 8μm, 10μm, 12μm, 15μm, 18μm, 20μm, 22μm, 25μm, 30μm, 32μm, 35μm, 38μm, and 40μm, and is not limited thereto. When the length of the longest diagonal of the second base 33 of the second pyramid unit is less than 6μm, the side reflective area of the second pyramid structure cannot be effectively increased, the number of scattering and reflections of light incident on the side area cannot be increased, and the reflectivity of the textured surface is reduced; when the length of the longest diagonal of the second base 33 of the second pyramid unit is greater than 40μm, it will affect the distribution density of the second pyramid structure, thereby affecting the density of the subsequent passivation film layer and the passivation effect.
[0057] The longest diagonal of the recessed portion 32 has a length of 2μm to 20μm, specifically 2μm, 3μm, 5μm, 8μm, 10μm, 12μm, 15μm, 17μm, 18μm, and 20μm, and is not limited to this. When the length of the longest diagonal of the recessed portion is less than 2μm, it cannot effectively increase the number of scattering and reflections of light hitting the top and middle-high regions, thus reducing the reflectivity of the velvet surface. When the length of the longest diagonal of the recessed portion is greater than 20μm, the size distribution of the recessed portion and the second pyramid structure is unreasonable, and it cannot balance the reflective area of the side, top, and middle-high regions of the velvet surface structure, thus reducing the reflectivity of the velvet surface.
[0058] The depth of the recessed portion 32 is 20nm~2μm, specifically 20nm, 50nm, 100nm, 200nm, 30nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1μm, 1.5μm, 2μm, and is not limited thereto. When the depth of the recessed portion is less than 20nm, the reflective area of the recessed portion is small, and the reflectivity cannot be effectively reduced; when the depth of the recessed portion is greater than 2μm, there will be poor coverage of passivation films such as Al2O3 and SiNx, passivation failure, and technical problems leading to reduced power-off efficiency.
[0059] In some embodiments, the recess 32 includes at least two sidewalls connected at their bottoms, and the included angle between the sidewalls is 0° to 79°, preferably 10° to 60°, and more preferably 30° to 60°.
[0060] It is understood that the recess 32 is formed by two or more sidewalls, which are arranged at an angle to the silicon substrate. The bottoms of the sidewalls are connected to form the recess, and the upper end of the recess forms an opening. Along the thickness direction of the silicon substrate, the cross-section of the recess in this embodiment is preferably triangular, which can increase the number of times sunlight is reflected repeatedly in the recess between the tops of adjacent pyramid structures, lengthen the light path, and improve the effective absorption rate of sunlight.
[0061] In some embodiments, the height of a single second pyramid structure is 200 nm to 2 μm, specifically 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 1.5 μm, or 2 μm, and is not limited thereto. The base length of a single second pyramid structure is 1 to 10 μm, specifically 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm, and is not limited thereto. Different numbers of second pyramid structures overlap each other, and the tops and / or bases are connected to each other to form second pyramid units of different shapes.
[0062] In some embodiments, the intersecting edges between the second bases 33 of adjacent second pyramid structures are overlapping edges, the length of which is 1~10μm, specifically 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, and is not limited thereto. The intersecting second apexes 31 of adjacent second pyramid structures form a recess 32, and the intersecting second bases 33 of adjacent second pyramid structures form a groove. This allows sunlight incident on the inner wall of the pyramid structure to be reflected by the inner wall and into the recess and groove, and continuously reflected between adjacent pyramid structures, thus lengthening the light path and improving the effective absorption rate of sunlight.
[0063] In some embodiments, the first pyramid structure 2 and / or the second pyramid structure 3 include at least one curved side ridge. The curved side ridge can increase the reflection path of sunlight incident on the sidewall of the pyramid structure. After being reflected by the curved side ridge, the sunlight can be reflected onto the convex ridge, recess, groove, or sidewall, enriching the reflection path, increasing the number of reflections, lengthening the light path, and improving the effective absorption rate of sunlight.
[0064] In some embodiments, the solar cell further includes a third pyramid unit disposed on the surface of the silicon substrate, the third pyramid unit being composed of third pyramid structures, wherein the bases of adjacent third pyramid structures do not overlap.
[0065] It is understandable that the third pyramid unit is a conventional independent pyramid structure, and the bases of adjacent third pyramid structures do not overlap, nor do the apexes overlap.
[0066] In some embodiments, the ratio of the total area of the third pyramid unit to the area of the silicon substrate is 0-10%, preferably 1-8%. The ratio of the total area of the first pyramid unit to the area of the silicon substrate is 30%-90%, the ratio of the total area of the second pyramid unit to the area of the silicon substrate is 10%-70%, and the ratio of the total area of the third pyramid unit to the area of the silicon substrate is 0-10%. By setting a larger area first pyramid unit, a smaller area second pyramid unit, and a very small area third pyramid unit, the distribution of the first, second, and third pyramid units is more reasonable, which can effectively increase the number of scattering and reflection of light hitting the top, middle and high, and bottom regions, reduce the surface reflectivity, and thus improve the short-circuit current of the solar cell.
[0067] In some embodiments, the height of a single third pyramid structure is 0.3 μm to 5 μm, and the side length of the base of a single third pyramid structure is 0.3 μm to 5 μm. Preferably, the height of a single third pyramid structure is 0.3 μm to 2 μm, and the side length of the base of a single third pyramid structure is 0.3 μm to 2 μm.
[0068] In some embodiments, the third pyramid structure includes at least one curved side ridge. The curved side ridge can increase the reflection path of sunlight incident on the sidewall of the pyramid structure. After being reflected by the curved side ridge, the sunlight can be reflected onto the convex ridge, recess, groove, or sidewall, enriching the reflection path, increasing the number of reflections, lengthening the light path, and improving the effective absorption rate of sunlight.
[0069] Secondly, the present invention also provides a solar cell module, including the aforementioned solar cell. It will be understood that the solar cell module may further include a metal frame, a front panel, a back panel, and an encapsulating film, or other necessary components.
[0070] Thirdly, the present invention provides a solar cell system including the aforementioned solar cell module.
[0071] 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.
[0072] The present invention will be further illustrated below with specific embodiments. Example 1 The present invention provides a solar cell, comprising a silicon substrate 1, a first pyramidal unit 2 disposed on the surface of the silicon substrate, and a second pyramidal unit 3 disposed on the surface of the silicon substrate. The first pyramid unit 2 is composed of 2 to 6 first pyramid structures. The first tops 21 of adjacent first pyramid structures are connected to form a convex ridge 22, and the first bases 23 of adjacent first pyramid structures partially overlap. The length of the longest diagonal of the first base 23 of the first pyramid unit is 6μm to 40μm, the length of the longest diagonal of the convex ridge 22 is 1μm to 6μm, the height of a single first pyramid structure is 200μm to 2μm, and the side length of the base of a single first pyramid structure is 1μm to 10μm.
[0073] The second pyramid unit 3 consists of 2 to 6 second pyramid structures. A recess 32 is formed between the second apex 31 of adjacent second pyramid structures, and the second bases 33 of adjacent second pyramid structures partially overlap. The longest diagonal of the second base 33 of the second pyramid unit is 6 μm to 40 μm, the longest diagonal of the recess 32 is 2 μm to 20 μm, and the depth of the recess 32 is 20 nm to 2 μm. The height of a single second pyramid structure is 200 nm to 2 μm, and the side length of the base of a single second pyramid structure is 1 to 10 μm.
[0074] The ratio of the total area of the first pyramid unit 2 to the area of the silicon substrate 1 is 80-90%, and the ratio of the total area of the second pyramid unit 3 to the area of the silicon substrate 1 is 10-20%.
[0075] Example 2 The present invention provides a solar cell, comprising a silicon substrate 1, a first pyramidal unit 2 disposed on the surface of the silicon substrate, and a second pyramidal unit 3 disposed on the surface of the silicon substrate. The first pyramid unit 2 is composed of 2 to 6 first pyramid structures. The first tops 21 of adjacent first pyramid structures are connected to form a convex ridge 22, and the first bases 23 of adjacent first pyramid structures partially overlap. The length of the longest diagonal of the first base 23 of the first pyramid unit is 10μm to 40μm, the length of the longest diagonal of the convex ridge 22 is 2μm to 6μm, the height of a single first pyramid structure is 1μm to 2μm, and the side length of the base of a single first pyramid structure is 1μm to 10μm.
[0076] The second pyramid unit 3 consists of 2 to 6 second pyramid structures. A recess 32 is formed between the second apex 31 of adjacent second pyramid structures, and the second bases 33 of adjacent second pyramid structures partially overlap. The longest diagonal of the second base 33 of the second pyramid unit is 10 μm to 40 μm, the longest diagonal of the recess 32 is 5 μm to 20 μm, and the depth of the recess 32 is 100 μm to 2 μm. The height of a single second pyramid structure is 1 μm to 2 μm, and the side length of the base of a single second pyramid structure is 1 to 10 μm.
[0077] The ratio of the total area of the first pyramid unit 2 to the area of the silicon substrate 1 is 60-70%, and the ratio of the total area of the second pyramid unit 3 to the area of the silicon substrate 1 is 30-40%.
[0078] Example 3 The present invention provides a solar cell, comprising a silicon substrate 1, a first pyramidal unit 2 disposed on the surface of the silicon substrate, and a second pyramidal unit 3 disposed on the surface of the silicon substrate. The first pyramid unit 2 is composed of 2 to 6 first pyramid structures. The first tops 21 of adjacent first pyramid structures are connected to form a convex ridge 22, and the first bases 23 of adjacent first pyramid structures partially overlap. The length of the longest diagonal of the first base 23 of the first pyramid unit is 12μm to 35μm, the length of the longest diagonal of the convex ridge 22 is 1.5μm to 6μm, the height of a single first pyramid structure is 500μm to 2μm, and the side length of the base of a single first pyramid structure is 1μm to 10μm.
[0079] The second pyramid unit 3 consists of 2 to 6 second pyramid structures. A recess 32 is formed between the second apex 31 of adjacent second pyramid structures, and the second bases 33 of adjacent second pyramid structures partially overlap. The longest diagonal of the second base 33 of the second pyramid unit is 12 μm to 35 μm, the longest diagonal of the recess 32 is 3.5 μm to 18 μm, and the depth of the recess 32 is 200 nm to 1.8 μm. The height of a single second pyramid structure is 500 nm to 2 μm, and the side length of the base of a single second pyramid structure is 1 to 10 μm.
[0080] The ratio of the total area of the first pyramid unit 2 to the area of the silicon substrate 1 is 50-60%, and the ratio of the total area of the second pyramid unit 3 to the area of the silicon substrate 1 is 40-50%.
[0081] Example 4 The present invention provides a solar cell, comprising a silicon substrate 1, a first pyramidal unit 2 disposed on the surface of the silicon substrate, a second pyramidal unit 3 disposed on the surface of the silicon substrate, and a third pyramidal unit disposed on the surface of the silicon substrate. The first pyramid unit 2 is composed of 2 to 6 first pyramid structures. The first tops 21 of adjacent first pyramid structures are connected to form a convex ridge 22, and the first bases 23 of adjacent first pyramid structures partially overlap. The length of the longest diagonal of the first base 23 of the first pyramid unit is 10μm to 40μm, the length of the longest diagonal of the convex ridge 22 is 2μm to 6μm, the height of a single first pyramid structure is 1μm to 2μm, and the side length of the base of a single first pyramid structure is 1μm to 10μm.
[0082] The second pyramid unit 3 consists of 2 to 6 second pyramid structures. A recess 32 is formed between the second apex 31 of adjacent second pyramid structures, and the second bases 33 of adjacent second pyramid structures partially overlap. The longest diagonal of the second base 33 of the second pyramid unit is 10 μm to 40 μm, the longest diagonal of the recess 32 is 5 μm to 20 μm, and the depth of the recess 32 is 100 μm to 2 μm. The height of a single second pyramid structure is 1 μm to 2 μm, and the side length of the base of a single second pyramid structure is 1 to 10 μm.
[0083] The third pyramid structures do not overlap with each other. The height of a single third pyramid structure is 0.3μm to 2μm, and the side length of the base of a single third pyramid structure is 0.3μm to 2μm.
[0084] The ratio of the total area of the first pyramid unit 2 to the area of the silicon substrate 1 is 60-70%, the ratio of the total area of the second pyramid unit 3 to the area of the silicon substrate 1 is 20-30%, and the ratio of the total area of the third pyramid unit to the area of the silicon substrate is 0-10%.
[0085] Example 5 Unlike Example 1, the first pyramid structure in Example 5 includes 1 to 4 curved side edges.
[0086] Example 6 Unlike Example 2, the second pyramid structure in Example 6 includes 1 to 4 curved side edges.
[0087] Example 7 Unlike Example 3, the first and second pyramid structures in Example 7 both include 1 to 4 curved side edges.
[0088] Example 8 Unlike Embodiment 4, the first and second pyramid structures in Embodiment 8 each include 1 to 4 curved side edges, and the third pyramid structure includes 1 to 4 curved side edges.
[0089] 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 first pyramid unit is disposed on the surface of the silicon substrate. The first pyramid unit is composed of at least two first pyramid structures. The tops of adjacent first pyramid structures are connected to form a convex ridge, and the bottoms of adjacent first pyramid structures partially overlap. The second pyramid unit is disposed on the surface of the silicon substrate. The second pyramid unit is composed of at least two second pyramid structures, with a recess formed between the tops of adjacent second pyramid structures and a partial overlap between the bottoms of adjacent second pyramid structures. The ratio of the total area of the first pyramid unit to the area of the silicon substrate is 30% to 90%, the ratio of the total area of the second pyramid unit to the area of the silicon substrate is 10% to 70%, the length of the longest diagonal of the base of the first pyramid unit is ≥6μm, and the length of the longest diagonal of the convex ridge is ≥1μm.
2. The solar cell according to claim 1, characterized in that, The ratio of the total area of the first pyramid unit to the area of the silicon substrate is 50% to 80%; the ratio of the total area of the second pyramid unit to the area of the silicon substrate is 20% to 50%. The length of the longest diagonal at the base of the first pyramid unit is ≥6μm, and the length of the longest diagonal of the convex ridge is ≥1μm; The length of the longest diagonal of the base of the second pyramid unit is ≥6μm; the length of the longest diagonal of the recess is ≥0.5μm, and the depth of the recess is ≥0.5μm.
3. The solar cell according to claim 1, characterized in that, The first pyramid unit consists of 2 to 6 first pyramid structures. The tops of adjacent 2 to 6 first pyramid structures are connected to form convex ridges, and the bases of adjacent 2 to 6 first pyramid structures partially overlap.
4. The solar cell according to claim 3, characterized in that, The longest diagonal of the base of the first pyramid unit has a length of 6μm to 40μm, and the longest diagonal of the convex ridge has a length of 1μm to 6μm.
5. The solar cell according to claim 3, characterized in that, The protrusion is a protrusion extending along the connecting line between the tops of adjacent first pyramid structures, and the angle between the extension line of the protrusion and the silicon substrate is 0~60°.
6. The solar cell according to claim 3, characterized in that, The top of the protruding ridge has a smooth, rounded corner transition, with a radius of curvature of 50nm to 1000nm.
7. The solar cell according to claim 3, characterized in that, Along the thickness direction of the silicon substrate, the distance between the highest point of the protrusion and the silicon substrate is 200 nm to 2 μm.
8. The solar cell according to claim 3, characterized in that, The height of a single first pyramid structure is 200 nm to 2 μm, and the side length of the base of a single first pyramid structure is 1 μm to 10 μm.
9. The solar cell according to claim 3, characterized in that, The intersecting edges between the bases of adjacent first pyramid structures are called overlapping edges, and the length of the overlapping edges is 1μm to 10μm.
10. The solar cell according to claim 1, characterized in that, The second pyramid unit consists of 2 to 6 second pyramid structures, with a recessed area formed between the tops of adjacent 2 to 6 second pyramid structures, and the bases of adjacent 2 to 6 second pyramid structures partially overlapping.
11. The solar cell according to claim 10, characterized in that, The longest diagonal of the base of the second pyramid unit is 6μm to 40μm; the longest diagonal of the recess is 2μm to 20μm, and the depth of the recess is 20nm to 2μm.
12. The solar cell according to claim 10, characterized in that, The recess includes at least two sidewalls, the bottoms of which are connected, and the included angle between the sidewalls is 0° to 79°.
13. The solar cell according to claim 10, characterized in that, The height of a single second pyramid structure is 200 nm to 2 μm, and the side length of the base of a single second pyramid structure is 1 μm to 10 μm.
14. The solar cell according to claim 10, characterized in that, The intersecting edges between the bases of adjacent second pyramid structures are overlapping edges, and the length of the overlapping edges is 1μm to 10μm.
15. The solar cell according to claim 1, characterized in that, The first pyramid structure and / or the second pyramid structure include at least one curved side edge.
16. The solar cell according to claim 1, characterized in that, It also includes a third pyramid unit disposed on the surface of the silicon substrate, the third pyramid unit being composed of a third pyramid structure, wherein the bases of adjacent third pyramid structures do not overlap.
17. The solar cell according to claim 18, characterized in that, The ratio of the total area of the third pyramid unit to the area of the silicon substrate is 0% to 10%.
18. The solar cell according to claim 18, characterized in that, The height of a single third pyramid structure is 0.3μm to 5μm, and the side length of the base of a single third pyramid structure is 0.3μm to 5μm.
19. A solar cell module, characterized in that, Including the solar cell as described in any one of claims 1 to 18.
20. A solar cell system, characterized in that, Includes the solar cell module as described in claim 19.