Photovoltaic cell

Abstract

The application relates to the photovoltaic technology field and provides a photovoltaic cell which is at least beneficial to improving the efficiency of the photovoltaic cell. The photovoltaic cell comprises a substrate, the substrate comprises a first surface and a second surface which are oppositely arranged; and a ladder structure, the ladder structure is located on the first surface, the ladder structure comprises a plurality of stacked tower bases which are stackedly arranged, the included angle between the slope surface of the ladder structure and the first surface is 30-60 degrees, and the slope surface is the plane where the most number of edges of the stacked tower bases are located.

Description

Technical Field

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

[0002] With the continuous development of photovoltaic technology, the requirements for photovoltaic cell performance are also increasing. Among the many performance indicators of photovoltaic cells, light absorption and reflection characteristics and electron transport efficiency play a crucial role in the overall performance of photovoltaic cells. Polishing the back of a photovoltaic cell makes the back surface smoother, reduces the specific surface area, reduces the recombination of charge carriers in the emitter surface region of the photovoltaic cell, and is beneficial for back passivation.

[0003] However, the internal reflection of light is not fully utilized after the back is polished, which means that some light cannot be effectively absorbed by the photovoltaic cell and converted into electrical energy, thus reducing the photoelectric conversion efficiency of the photovoltaic cell. Summary of the Invention

[0004] This application provides a photovoltaic cell that at least helps to improve the efficiency of photovoltaic cells.

[0005] According to some embodiments of this application, one aspect of this application provides a photovoltaic cell, including: a substrate, the substrate including a first surface and a second surface disposed opposite to each other; a stepped structure, the stepped structure being located on the first surface, the stepped structure including a plurality of stacked tower bases, the angle between the slope surface of the stepped structure and the first surface being 30° to 60°, and the slope surface being the plane where the most numerous edges of the stacked tower bases are located.

[0006] In some embodiments, the first surface further includes a base tower base, which is composed of a single tower base structure, wherein the side length of the stacked tower base is a first dimension; the side length of the base tower base is a second dimension, and the ratio of the first dimension to the second dimension is (1.5 to 2):1.

[0007] In some embodiments, the first dimension is 5 μm to 10 μm.

[0008] In some embodiments, the second dimension is 15 μm to 20 μm.

[0009] In some embodiments, the height of the base tower is greater than the height of the stacked tower bases.

[0010] In some embodiments, the top edge of the stacked tower base has an arc-shaped positive angle, and the radius of curvature of the arc-shaped positive angle is 0.5μm to 1μm.

[0011] In some embodiments, the bottom edge of the stacked base at the bottom of the stepped structure forms an arc-shaped concave angle with the first surface, and the radius of curvature of the arc-shaped concave angle is 0.5μm to 1μm.

[0012] In some embodiments, the number of stacked tower bases in the stepped structure is 2 to 8.

[0013] In some embodiments, the substrate has an N-type dopant element, which includes phosphorus, arsenic, or antimony.

[0014] In some embodiments, the first side is a backlight side and the second side is a light-receiving side.

[0015] The technical solution provided in this application has at least the following advantages:

[0016] In the photovoltaic cell provided in this application embodiment, a stepped structure composed of multiple stacked tower bases is provided on the first surface of the substrate. The three-dimensional, overlapping block structure can reduce the height difference between different areas of the first surface, and at the same time, it allows more light to be reflected back into the photovoltaic cell for absorption, enhancing the internal reflection effect of the photovoltaic cell, improving the light absorption utilization rate, and thus improving the efficiency of the photovoltaic cell. Compared with a conventional polished surface, the planar structure results in a single reflection path for long-wavelength photons (700nm~1100nm), and insufficient light absorption utilization rate (especially under weak light), which has problems with light absorption and reflection as well as electron transmission efficiency. Although the stacked tower bases reduce the flatness of the first surface, the top surface of the stacked tower bases is relatively flat, and the stepped structure has little impact on carrier recombination on the first surface, which can still improve the passivation effect and short-circuit current, thereby improving the light conversion efficiency of the photovoltaic cell. In addition, the slope S of the stepped structure forms an angle of 30° to 60° with the first surface. The directional and intersecting block structure makes the light reflection path present a "Z"-shaped detour, which increases the chance of internal reflection by 2 to 3 times compared with the disordered tower base structure, and improves the light absorption utilization rate by 8% to 12%. Attached Figure Description

[0017] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the structure of a substrate provided in an embodiment of this application;

[0019] Figure 2 A top-view SEM image of a substrate provided for an embodiment of this application.

[0020] Explanation of reference numerals in the attached figures:

[0021] 100. Base; 101. First face; 102. Second face; 110. Step structure; 111. Stacked base; 120. Basic base; 130. Pyramid structure. Detailed Implementation

[0022] As can be seen from the background technology, the internal reflection of light is not fully utilized after the back of the photovoltaic cell is polished, resulting in some light not being effectively absorbed by the photovoltaic cell and converted into electrical energy, thus reducing the photoelectric conversion efficiency of the photovoltaic cell.

[0023] This application provides a photovoltaic cell that at least helps to improve the efficiency of photovoltaic cells.

[0024] In the description of the embodiments of this application, the technical terms "first", "second", etc. are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0025] In the description of the embodiments in this application, "multiple" means two or more, unless otherwise explicitly specified.

[0026] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0027] In the description of the embodiments of this application, technical terms such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" 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 the embodiments of this application and simplifying the description, and are not intended to 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 the embodiments of this application.

[0028] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. When describing a component on another component or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0029] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included.

[0030] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments, the term "component" is also intended to include the plural form unless the context clearly indicates otherwise.

[0031] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0032] Figure 1 A schematic diagram of the structure of a substrate provided in an embodiment of this application; Figure 2 A top-view SEM image of a substrate provided in an embodiment of this application. Figure 2 The AA1 direction shown is... Figure 1 The cross-sectional direction of the stepped structure 110 shown corresponds to that of the other structures.

[0033] refer to Figure 1 The photovoltaic cell provided in this application embodiment includes: a substrate 100 and a stepped structure 110. The substrate 100 includes a first surface 101 and a second surface 102 disposed opposite to each other. The stepped structure 110 is located on the first surface 101. The stepped structure 110 includes a plurality of stacked tower bases 111. The angle α between the slope surface of the stepped structure 110 (the surface shown by the dashed line S in the figure) and the first surface 101 is 30° to 60°. The slope surface S is the plane where the most edges of the stacked tower bases 111 are located.

[0034] In the photovoltaic cell provided in this application embodiment, a stepped structure 110 formed by stacked tower bases 111 is provided on the first surface 101 of the substrate 100. The three-dimensional, overlapping block structure can reduce the height difference between different areas of the first surface 101, and at the same time, it allows more light to be reflected back into the photovoltaic cell for absorption, enhancing the internal reflection effect of the photovoltaic cell, improving the light absorption utilization rate, and thus improving the efficiency of the photovoltaic cell. Compared with conventional polished surfaces, planar structures result in a single reflection path for long-wavelength photons (700nm~1100nm), leading to insufficient light absorption utilization (especially under weak light), and problems with light absorption, reflection, and electron transport efficiency. Although the stacked tower bases 111 reduce the flatness of the first surface 101, the top surface of the stacked tower bases 111 is relatively flat, and the stepped structure 110 has a small impact on carrier recombination on the first surface 101, which can still improve the passivation effect and short-circuit current, thereby improving the light conversion efficiency of the photovoltaic cell. In addition, the slope surface S of the stepped structure 110 forms an angle of 30° to 60° with the first surface 101. The directional and intersecting block structure makes the light reflection path present a "Z"-shaped detour, which increases the chance of internal reflection by 2 to 3 times compared with the disordered tower base structure, and improves the light absorption utilization rate by 8% to 12%.

[0035] It is understandable that the stacking directions of multiple stacked tower bases 111 can be staggered in the horizontal direction, so that the slope surface of the stepped structure 110 is the plane where the extension lines of the most numerous edges in the stacked tower bases 111 are located.

[0036] In some embodiments, the number of stacked tower bases 111 in the stepped structure 110 is 2 to 8, for example, specifically 2, 3, 4, 5, 6, 7 or 8.

[0037] In this embodiment, the first surface 101 is the backlight surface, and the second surface 102 is the light-receiving surface. The second surface 102 of the substrate 100 may have a textured structure, which is composed of multiple pyramid structures 130. The textured structure can enhance the absorption and utilization rate of incident light by the substrate 100, thereby improving the light conversion efficiency of the photovoltaic cell.

[0038] In some embodiments, the photovoltaic cell can be any one of the following: PERC cell (Passivated Emitter and Rear Cell), PERT cell (Passivated Emitter and Rear Totally-diffused cell), TOPCon cell (Tunnel Oxide Passivated Contact cell), HIT / HJT cell (Heterojunction Technology), or BC cell (Back Contact cell). The BC cell can be an IBC cell (Interdigitated Back Contact cell), an HPBC cell (Hybrid Passivated Back Contact cell), a TBC cell combining TOPCon (Tunnel Oxide Passivated Contact) and IBC technologies, or an HBC cell combining HIT / HJT (Heterojunction Technology) and IBC technologies. It can also be other types of back contact cells.

[0039] In some embodiments, the photovoltaic cell can be a monocrystalline silicon solar cell, a polycrystalline silicon solar cell, an amorphous silicon solar cell, or a multi-component compound solar cell. Specifically, the multi-component compound solar cell can be a cadmium sulfide solar cell, a gallium arsenide solar cell, a copper indium selenide solar cell, or a perovskite solar cell.

[0040] In this embodiment, the photovoltaic cell is a TOPCon cell. A tunneling layer and a doped conductive layer are formed on the first surface 101. The tunneling layer is located on one side of the substrate 100, and the doped conductive layer is located on the surface of the tunneling layer away from the substrate 100. The tunneling layer and the doped conductive layer are used to form a passivation contact structure. The tunneling layer can achieve a chemical passivation effect. Due to the presence of interface state defects on the substrate surface, the tunneling layer can saturate the dangling bonds on the substrate surface, reduce the defect state density on the substrate 100 surface, reduce the recombination centers on the substrate surface, and reduce the carrier recombination rate, resulting in a larger interface state density on the substrate 100 surface. The increased interface state density promotes the recombination of photogenerated carriers, increases the fill factor, short-circuit current, and open-circuit voltage of the solar cell, and improves the photoelectric conversion efficiency of the solar cell.

[0041] The first surface 101 is flatter than the second surface 102. On the flat first surface 101, it is more conducive to the growth of the tunneling layer into a perfect, pinhole-free, and uniformly thick ultrathin oxide layer, thereby ensuring the selective and efficient tunneling of charge carriers (electrons) and achieving ultimate passivation.

[0042] The material of the tunneling layer may include at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride.

[0043] The material of the doped conductive layer may include at least one of amorphous silicon, polycrystalline silicon, or silicon carbide. The doped conductive layer has the same doping elements as the substrate 100. If the doping element type of the substrate 100 is P-type, then the doping element type of the doped conductive layer is also P-type; if the doping element type of the substrate 100 is N-type, then the doping element type of the doped conductive layer is also N-type.

[0044] In this embodiment, the substrate 100 contains an N-type dopant element, and any one of the group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). That is, the photovoltaic cell is an N-type TOPCon cell. N-type TOPCon has higher requirements for back-side passivation quality (minority carrier lifetime must be >100μs). The slope surface S formed by the three-dimensional interlacing of the stacked tower base 111 forms an angle of 30° to 60° with the crystal orientation (100) plane of the substrate 100. It is not a traditional parallel or perpendicular stacking, which is adapted to the anisotropic etching characteristics of the N-type substrate.

[0045] In other embodiments, the substrate 100 has a P-type dopant element, which can be any one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0046] In some embodiments, the material of the substrate 100 may be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0047] In some embodiments, the substrate 100 may have an emitter located on the side of the substrate 100 closest to the second surface 102. The doping type of the emitter is opposite to that of the doping type in the substrate 100. For example, if the doping element in the substrate 100 is a P-type doping element, then the doping element in the emitter is an N-type doping element; if the doping element in the substrate 100 is an N-type doping element, then the doping element in the emitter is a P-type doping element, thus forming a PN junction with the substrate 100. The PN junction can receive incident light illuminating the surface of the substrate 100 and generate electron-hole pairs. For example, when the substrate 100 is an N-type substrate, the separated electrons move into the substrate 100, and the separated holes move into the emitter, thus forming a current.

[0048] refer to Figure 1 and Figure 2 The first surface 101 may also include a base tower 120, which is composed of a single tower base structure. The side length of the stacked tower base 111 is a first dimension; the side length of the base tower base 120 is a second dimension. The ratio of the first dimension to the second dimension is (1.5 to 2):1, for example, it can be 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1.

[0049] It should be noted that the top surface of the stacked tower base 111 is approximately rectangular, and the side length of the stacked tower base 111 refers to the length of the longest edge among the edges of the top surface of the stacked tower base 111. Similarly, the top surface of the base tower base 120 is approximately rectangular, and the side length of the base tower base 120 refers to the length of the longest edge among the edges of the top surface of the base tower base 120.

[0050] In some embodiments, the first size is 5μm to 10μm, for example, it can be 5μm, 5.6μm, 6μm, 6.4μm, 7μm, 7.5μm, 8μm, 8.3μm, 9μm, 9.7μm or 10μm.

[0051] In some embodiments, the second dimension is 15μm to 20μm, for example, it can be 15μm, 15.5μm, 16μm, 16.5μm, 17μm, 17.6μm, 18μm, 18.4μm, 19μm, 19.5μm or 20μm.

[0052] In some embodiments, the height of the base tower base 120 is higher than the height of the stacked tower base 111. The height of the base tower base 120 refers to the height difference between the bottom and top surfaces of the base tower base 120; the height of the stacked tower base 111 refers to the height difference between the bottom and top surfaces of the stacked tower base 111.

[0053] In some embodiments, the top edge of the stacked tower base 111 may have an arc-shaped positive angle, and the radius of curvature of the arc-shaped positive angle is 0.5μm to 1μm, for example, it may be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm or 1μm.

[0054] In some embodiments, the bottom edge of the stacking base 111 at the bottom of the stepped structure 110 forms an arc-shaped concave angle with the first surface 101, and the radius of curvature of the arc-shaped concave angle is 0.5μm to 1μm, for example, it can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm or 1μm.

[0055] The top or bottom of the stacked tower base 111 is transitioned by a slight arc with an external arc and an internal arc, which can reduce surface hanging keys.

[0056] In some embodiments, the top edge of the base tower base 120 may also have an arc-shaped positive angle, the radius of curvature of which is 0.5μm to 1μm, specifically 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, or 1μm. The bottom edge of the base tower base 120 may also form an arc-shaped negative angle with the first surface 101, the radius of curvature of which is 0.5μm to 1μm, specifically 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, or 1μm.

[0057] The top or bottom of the base tower 120 is transitioned by a slight arc with an external arc and an internal arc, which can reduce the surface hanging key.

[0058] In the photovoltaic cell provided in this application embodiment, a stepped structure 110 formed by stacked tower bases 111 is provided on the first surface 101 of the substrate 100. The three-dimensional, overlapping block structure can reduce the height difference between different areas of the first surface 101, and at the same time, it allows more light to be reflected back into the photovoltaic cell for absorption, enhancing the internal reflection effect of the photovoltaic cell, improving the light absorption utilization rate, and thus improving the efficiency of the photovoltaic cell. Compared with conventional polished surfaces, planar structures result in a single reflection path for long-wavelength photons (700nm~1100nm), leading to insufficient light absorption utilization (especially under weak light), and problems with light absorption, reflection, and electron transport efficiency. Although the stacked tower bases 111 reduce the flatness of the first surface 101, the top surface of the stacked tower bases 111 is relatively flat, and the stepped structure 110 has a small impact on carrier recombination on the first surface 101, which can still improve the passivation effect and short-circuit current, thereby improving the light conversion efficiency of the photovoltaic cell. In addition, the slope surface S of the stepped structure 110 forms an angle of 30° to 60° with the first surface 101. The directional and intersecting block structure makes the light reflection path present a "Z"-shaped detour, which increases the chance of internal reflection by 2 to 3 times compared with the disordered tower base structure, and improves the light absorption utilization rate by 8% to 12%.

[0059] Accordingly, another embodiment of this application also provides a method for manufacturing a photovoltaic cell, which can be used to manufacture the photovoltaic cell provided in the above embodiments. For parts that are the same as or corresponding to the previous embodiment, please refer to the corresponding descriptions of the foregoing embodiments; detailed descriptions will not be repeated below.

[0060] The method for manufacturing photovoltaic cells provided in this application includes the following steps:

[0061] (1) Provide a substrate, the first and second surfaces of which are both planes, and the substrate is an N-type substrate.

[0062] (2) The substrate is velvetted to form a pyramidal velvet surface on both the first and second surfaces.

[0063] (3) The substrate is subjected to boron diffusion treatment to form an emitter in the substrate. The first surface and the side borosilicate glass layer are removed by hydrofluoric acid. The concentration of hydrofluoric acid can be 50wt% to 80wt%, preferably 60wt% to 70wt%.

[0064] (4) The substrate is pre-cleaned using a tank cleaning machine to remove impurities and prepare for polishing. The solution consists of sodium hydroxide / potassium hydroxide, hydrogen peroxide and pure water. The process temperature is 50℃~90℃, preferably 60℃~80℃, and the time is 50s~500s, preferably 100s~300s. Ultrasonic assisted cleaning (frequency 40kHz~60kHz, power 100W~150W) is added. Combined with NaOH / KOH and hydrogen peroxide system, micron-level impurities (such as metal particles and oxide layer fragments) on the substrate surface are removed, making the surface cleaner and preparing for polishing.

[0065] (5) Alkali etching is performed using a tank etching machine to form multiple overlapping stepped structures on the first surface. Sodium hydroxide / potassium hydroxide solution is used as the base alkaline etching solution, and isopropanol (IPA) and surfactant (sodium dodecylbenzenesulfonate) are added. IPA can reduce the surface tension of the solution and promote uniform corrosion; surfactant can inhibit bubble adhesion and improve the uniformity of the tower base morphology. By adjusting the concentration and temperature of the alkaline etching solution, the corrosion rate ratio of the (100) crystal plane to the (111) crystal plane is controlled between 3:1 and 5:1. Then, composite additives (such as 0.1wt% to 0.5wt% of silane coupling agent and 0.05wt% to 0.2wt% of nano-SiO2 particles) are added to the above alkaline solution (NaOH / KOH).

[0066] Silane coupling agents can regulate the anisotropy of etching rates (increasing the etching rate ratio of the (100) crystal plane to the (111) crystal plane to 6:1 to 8:1), and nano-SiO2 particles are adsorbed at the corners of the tower base, inhibiting over-etching. Segmented alkaline etching is employed.

[0067] (Instead of isothermal etching): First stage (0s~100s): Temperature 65℃~70℃, rapidly forming the basic tower base (size 5μm~10μm); Second stage (100s~300s): Temperature drops to 55℃~60℃, slowly etching to form a stepped structure composed of stacked tower bases (size of stacked tower bases 15μm~20μm).

[0068] (6) After cleaning the substrate, the additive residue on the substrate surface is cleaned. The solution consists of sodium hydroxide / potassium hydroxide, hydrogen peroxide and pure water. The process temperature is 50℃~90℃, preferably 60℃~80℃, and the time is 50s~500s, preferably 100s~300s.

[0069] (7) Use hydrochloric acid to remove metal ions from the substrate surface.

[0070] In the photovoltaic cell manufactured by the method provided in this application, a stepped structure 110 is formed on the first surface 101 of the substrate 100. The stepped structure 110 includes a plurality of stacked tower bases 111. The angle α between the slope surface of the stepped structure 110 (the surface shown by the dashed line S in the figure) and the first surface 101 is 30° to 60°. The slope surface S is the plane where the most edges of the stacked tower bases 111 are located. The three-dimensional interlaced overlapping block structure can reduce the height difference between different areas of the first surface 101, and at the same time, it allows more light to be reflected back into the photovoltaic cell for absorption, enhancing the internal reflection effect of the photovoltaic cell, improving the light absorption utilization rate, and thus helping to improve the efficiency of the photovoltaic cell. The slope surface S of the stepped structure 110 forms an angle of 30° to 60° with the first surface 101. The directional and intersecting block structure makes the light reflection path present a "Z"-shaped detour, which increases the chance of internal reflection by 2 to 3 times compared with the disordered tower base structure, and improves the light absorption utilization rate by 8% to 12%.

[0071] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A photovoltaic cell, characterized in that, include: A substrate, the substrate comprising a first surface and a second surface disposed opposite to each other; A stepped structure is located on the first surface. The stepped structure includes multiple stacked tower bases. The angle between the slope surface of the stepped structure and the first surface is 30° to 60°. The slope surface is the plane where the most edges of the stacked tower bases are located.

2. The photovoltaic cell according to claim 1, characterized in that, The first surface also includes a base tower base, which is composed of a single tower base structure. The side length of the stacked tower base is a first dimension; the side length of the base tower base is a second dimension, and the ratio of the first dimension to the second dimension is (1.5~2):

1.

3. The photovoltaic cell according to claim 2, characterized in that, The first size is 5μm to 10μm.

4. The photovoltaic cell according to claim 2, characterized in that, The second dimension is 15μm to 20μm.

5. The photovoltaic cell according to claim 2, characterized in that, The height of the base tower is higher than the height of the stacked tower.

6. The photovoltaic cell according to claim 1, characterized in that, The top edge of the stacked tower base has an arc-shaped positive angle, and the radius of curvature of the arc-shaped positive angle is 0.5μm to 1μm.

7. The photovoltaic cell according to claim 1, characterized in that, The bottom edge of the stacked tower base at the bottom of the stepped structure forms an arc-shaped concave angle with the first surface, and the radius of curvature of the arc-shaped concave angle is 0.5μm to 1μm.

8. The photovoltaic cell according to claim 1, characterized in that, In the stepped structure, the number of stacked tower bases is 2 to 8.

9. The photovoltaic cell according to claim 1, characterized in that, The substrate contains an N-type dopant element, which includes phosphorus, arsenic, or antimony.

10. The photovoltaic cell according to claim 1, characterized in that, The first side is the backlight side, and the second side is the light-receiving side.

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