Solar cell and manufacturing method thereof

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a solar cell piece and a manufacturing method thereof, the solar cell piece comprises a substrate, the substrate is provided with a front surface and a back surface which are opposite, the front surface is provided with a suede structure, the edge of the suede structure is arc-shaped, the suede structure is provided with n side surfaces, and n is a positive integer greater than or equal to 4; the emitting electrode covers the front surface of the substrate; the light absorption layer covers the surface of the emitting electrode; the passivation layer covers the surface of the light absorption layer; and the front electrode is in electric contact with the emitter. And the performance of the solar cell can be improved.

Description

Technical Field

[0001] The present disclosure relates to the field of photovoltaics, and in particular to a solar cell and a method for manufacturing the same. Background Art

[0002] Photovoltaic power generation refers to the conversion of solar energy into electrical energy through the photovoltaic effect of semiconductors. For example, TOPCON (Tunnel Oxide Passivated Contact) cells have attracted increasing attention due to their excellent photoelectric conversion performance.

[0003] TOPCON cells are a type of solar cell technology based on the principle of selective carrier transport using a tunneling oxide passivation contact. In TOPCON solar cells, selective carrier transport is achieved by forming a passivation contact structure on the substrate surface.

[0004] There is a need to improve the performance of solar cells. Summary of the Invention

[0005] The embodiments of the present disclosure provide a solar cell, which can at least improve the performance of the solar cell.

[0006] According to some embodiments of the present disclosure, on the one hand, the embodiments of the present disclosure provide a solar cell, comprising: a substrate, the substrate having a front side and a back side relative to each other, the front side having a velvet structure, the edges of the velvet structure being arc-shaped, and the velvet structure having n side faces, where n is a positive integer greater than or equal to 4; an emitter, the emitter covering the front side of the substrate; a light absorbing layer, the light absorbing layer covering the surface of the emitter; a passivation layer, the passivation layer covering the surface of the light absorbing layer; and a front electrode, the front electrode being in electrical contact with the emitter.

[0007] In some embodiments, the material of the light absorbing layer includes reduced graphene material, or a composite material of titanium dioxide and reduced graphene.

[0008] In some embodiments, the thickness of the light absorbing layer is 20 nm to 50 nm, and the particle size of the reduced graphene is 5 nm to 20 nm.

[0009] In some embodiments, the specific surface area of the suede structure is 1.4 to 1.6.

[0010] In some embodiments, the light absorbing layer contains hydrogen ions, and the content of the hydrogen ions is e18Atoms / cm3 to e19Atoms / cm 3 .

[0011] In some embodiments, the top of the suede structure is a rounded spherical crown structure.

[0012] According to some embodiments of the present disclosure, on the other hand, the embodiments of the present disclosure further provide a method for manufacturing a solar cell, forming a substrate, the substrate having a relative front and back, the front having a velvet structure, the edges of the velvet structure being arc-shaped, and the velvet structure having n side faces, where n is a positive integer greater than or equal to 4; forming an emitter, the emitter covering the front side of the substrate; forming a light absorbing layer, the light absorbing layer covering the surface of the emitter; forming a passivation layer, the passivation layer covering the surface of the light absorbing layer; forming a front electrode, the front electrode being in electrical contact with the emitter.

[0013] In some embodiments, the method of forming the substrate includes: providing an initial substrate, the initial substrate having a relative front and back side; performing a texturing process, the texturing process forming the velvet structure at least on the front side; performing a diffusion process, the diffusion process converting part of the initial substrate into an emitter, and the remaining initial substrate serves as the substrate.

[0014] In some embodiments, the method for forming the light absorbing layer includes: synthesizing a reduced graphene material; and depositing the reduced graphene material onto the surface of the emitter using a deposition process to form the light absorbing layer.

[0015] In some embodiments, the process parameters of the deposition process include: ultrasonic deposition, the frequency of the ultrasonic wave is 20KHz to 50KHz, and the temperature of the deposition process is 60°C to 80°C.

[0016] The technical solution provided by the embodiments of the present disclosure has at least the following advantages: first, the edges of the velvet structure are arc-shaped, that is, the velvet structure is rounded, and the arc-shaped edges will reduce the tip potential energy of the velvet structure. At the same time, the velvet structure has greater than or equal to 4 side surfaces, so that the roughness of the surface of the velvet structure is improved. In this way, the velvet structure on the surface of the substrate has the characteristics of roundness and increased roughness, which is convenient for the formation of the emitter and the light-absorbing layer, increases the density of the light-absorbing layer, increases the light-absorbing capacity of the light-absorbing layer, and improves the photoelectric conversion efficiency of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the traditional technology, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A cross-sectional view of a solar cell provided in accordance with an embodiment of the present disclosure;

[0019] Figure 2 This is an enlarged schematic diagram of a suede structure on a substrate surface provided by one embodiment of the present disclosure;

[0020] Figure 3 A flow chart of a method for manufacturing a solar cell provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0021] At present, the tip surface potential energy of the velvet structure on the surface of solar cells is large, and there are many defects at the grain boundary edges. Therefore, diffusion uniformity and contact resistivity are facing huge challenges, thereby reducing the photoelectric conversion efficiency and stability of solar cells.

[0022] The edges of the velvet structure in the embodiment of the present invention are arc-shaped, that is, the velvet structure is rounded. The arc-shaped edges will reduce the tip potential energy of the velvet structure. At the same time, the velvet structure has greater than or equal to 4 side faces, which increases the roughness of the surface of the velvet structure. In this way, the velvet structure on the surface of the substrate has the characteristics of roundness and increased roughness, which is convenient for the formation of the emitter and the light-absorbing layer, increases the density of the light-absorbing layer, increases the light-absorbing capacity of the light-absorbing layer, and improves the photoelectric conversion efficiency of the solar cell.

[0023] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are used solely to distinguish between different objects and should not be understood to indicate or imply relative importance or to implicitly specify the quantity, specific order, or primary and secondary relationship of the technical features indicated. In the description of the embodiments of the present disclosure, "plurality" means more than two, unless otherwise specifically defined.

[0024] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present disclosure. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0025] In the description of the embodiments of the present disclosure, the term "and / or" is merely a description of an association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B can represent the following three situations: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0026] In the description of the embodiments of the present disclosure, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0027] In the description of the embodiments of the present disclosure, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the embodiments of the present disclosure.

[0028] In the description of the embodiments of the present disclosure, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and they can refer to internal connectivity between two components or interaction between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present disclosure based on specific circumstances.

[0029] In the accompanying drawings corresponding to the embodiments of the present disclosure, the thickness and area of the layers are exaggerated for better understanding and ease of description. When describing a component (such as a layer, film, region or substrate) on another component or on the surface of another component, the component can be "directly" located on the surface of the other component, or a third component can be present between the two components. Conversely, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component as being "substantially" 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 partial edge of the entire surface.

[0030] In the description of the embodiments of the present disclosure, when a component is referred to as "including" another component, unless otherwise specified, other components are not excluded, and other components may be further included. In addition, when a component such as a layer, film, region, or plate is referred to as being "on / located on" another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component can be present between them. In addition, when a component such as a layer, film, region, or plate is "directly on" another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it means that no other components are located between them.

[0031] The terms used herein in the description of the various embodiments are intended only to describe the specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is intended to include the plural form unless the context clearly indicates otherwise. A component includes a layer, film, region, or plate.

[0032] The following describes various embodiments of the present disclosure in detail with reference to the accompanying drawings. However, those skilled in the art will appreciate that many technical details are provided in the various embodiments of the present disclosure to facilitate a better understanding of the present disclosure. However, even without these technical details and the various variations and modifications based on the following embodiments, the technical solutions claimed in the present disclosure can still be implemented.

[0033] refer to Figure 1 and Figure 2 , Figure 1 A cross-sectional view of a solar cell provided in one embodiment of the present disclosure is shown. Figure 2 This is an enlarged schematic diagram of a suede structure on a substrate surface provided by an embodiment of the present disclosure, wherein: Figure 2 The left side view in the middle is the appearance of the velvet structure without additional processing in the related art, and the right side view is an enlarged schematic diagram of the velvet structure in the embodiment of the present disclosure.

[0034] In some embodiments, a solar cell may include: a substrate 100, the substrate 100 having a front side 110 and a back side 120 relative to each other, the front side 110 having a velvet structure 130, the edges of the velvet structure 130 being arc-shaped, and the velvet structure 130 having n side surfaces, where n is a positive integer greater than or equal to 4.

[0035] The solar cell may further include an emitter 101 , where the emitter 101 covers the front surface 110 of the substrate 100 .

[0036] The solar cell may further include a light absorbing layer 102 , which covers the surface of the emitter 101 .

[0037] The solar cell may further include a passivation layer 103 , which covers the surface of the light absorbing layer 102 .

[0038] The solar cell may further include a front electrode 104 , which is in electrical contact with the emitter 101 .

[0039] The edges of the velvet structure 130 in the embodiment of the present disclosure are arc-shaped, that is, the velvet structure 130 is rounded. The arc-shaped edges will reduce the tip potential energy of the velvet structure 130. At the same time, the velvet structure 130 has greater than or equal to 4 side faces, so that the roughness of the surface of the velvet structure 130 is improved. In this way, the velvet structure 130 on the surface of the substrate 100 has the characteristics of roundness and increased roughness, which is convenient for the formation of the emitter 101 and the light absorbing layer 102, and will increase the density of the light absorbing layer 102, increase the light absorbing capacity of the light absorbing layer 102, and improve the photoelectric conversion efficiency of the solar cell.

[0040] In some embodiments, the material of the substrate 100 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. The elemental semiconductor material may be in a single crystalline state, a polycrystalline state, an amorphous state, or a microcrystalline state (a state having both single crystalline and amorphous states is referred to as a microcrystalline state). For example, silicon may be at least one of single crystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0041] In some embodiments, the substrate 100 may be made of a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanium, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, copper indium selenide, and the like.

[0042] The substrate 100 may be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type dopant element, which may be any Group V element such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate is doped with a P-type dopant element, which may be any Group III element such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0043] The substrate 100 has a front side 110 and a back side 120 relative to each other. In some embodiments, the battery cell is a single-sided battery cell, and the front side 110 of the substrate 100 can be used as a light-receiving surface for receiving incident light, and the back side 120 can be used as a backlight surface. In some embodiments, the battery cell is a double-sided battery cell, and both the front side 110 and the back side 120 of the substrate 100 can be used as light-receiving surfaces, and can be used to receive incident light. It can be understood that the backlight surface referred to in the embodiments of the present disclosure can also receive incident light, but the degree of reception of the incident light is weaker than that of the light-receiving surface, and therefore it is defined as a backlight surface.

[0044] In some embodiments, a texturing process can be performed on at least one surface of the front side 110 or the back side 120 of the substrate 100 to form a texturing structure 130 on at least one surface of the front side 110 or the back side 120 of the substrate 100. In this way, the absorption and utilization rate of the incident light by the front side 110 and the back side 120 of the substrate 100 can be enhanced.

[0045] In some embodiments, the velvet structure 130 can be further adjusted on the basis of the pyramid velvet. On the one hand, the pyramid velvet is further etched to form a velvet structure 130 having greater than or equal to 4 sides. On the other hand, the edges of the pyramid velvet are also etched to round the edges of the velvet structure 130, thereby completing the rounding treatment of the pyramid velvet and forming a controllable velvet structure 130.

[0046] In some embodiments, the specific surface area of the velvet structure 130 is 1.4 to 1.6, for example, 1.4, 1.5, or 1.6. It is understood that the specific surface area here refers to the ratio of the surface area of the velvet structure 130 to the area of the orthographic projection of the velvet structure 130 on the surface of the substrate 100. The larger the specific surface area of the velvet structure 130, the greater the roughness of the substrate 100. The greater the roughness, the easier it is to form the light absorbing layer 102, which can facilitate the adhesion of the material of the light absorbing layer 102, thereby improving the density of the light absorbing layer 102 and thus improving the light absorbing ability of the light absorbing layer 102.

[0047] If the specific surface area of the velvet structure 130 is less than 1.4, the improvement ability of the velvet structure 130 is not strong, resulting in poor ability to improve the density of the light-absorbing layer 102. If the specific surface area of the velvet structure 130 is greater than 1.6, the roughness of the surface of the substrate 100 will be too large, resulting in excessive damage to the substrate 100 during the etching process, which in turn affects the arc-shaped edges of the velvet structure 130. Therefore, by setting the specific surface area of the velvet structure 130 to 1.4-1.6, the surface roughness of the substrate 100 can be improved while avoiding excessive damage to the substrate 100, thereby improving the reliability of the solar cell while improving the performance of the solar cell.

[0048] In some embodiments, the surface area of the velvet structure 130 can be scanned by a scanning electron microscope, and the surface area of the velvet structure 130 can be calculated by integration. The projection area of the velvet structure 130 can be obtained by obtaining the projection image of the velvet structure 130 through a scanning microscope, and directly calculating the projection area of the velvet structure 130.

[0049] The density of the light absorbing layer 102 can be indirectly determined through experiments. For example, the density of the light absorbing layer 102 can be determined based on the time required to completely etch the light absorbing layer 102 by etching the light absorbing layer 102 under the same conditions. Alternatively, the density of the light absorbing layer 102 can be determined based on the thickness of the light absorbing layer 102 etched within the same time.

[0050] In some embodiments, the top of the velvet structure 130 is a rounded spherical cap structure. In other words, during the rounding process of the velvet structure 130, not only the edges of the velvet structure 130 are processed, but also the tip of the velvet structure 130 is processed, thereby completing the processing of the velvet structure 130. The rounded velvet structure 130 further reduces the surface potential energy of the velvet structure 130, thereby increasing the open circuit voltage of the solar cell and improving the photoelectric conversion efficiency of the solar cell.

[0051] In some embodiments, the emitter 101 may be directly doped on the substrate 100 to convert part of the substrate 100 into a doped emitter 101 . The doping element type of the emitter 101 is opposite to that of the substrate 100 , forming a PN junction with the substrate 100 .

[0052] In some embodiments, the material of the light absorbing layer 102 includes a reduced graphene material, or a composite material of titanium dioxide and reduced graphene. Reduced graphene materials, or composite materials of titanium dioxide and reduced graphene, inherently have high light absorbance and high mechanical strength. High light absorbance can improve the light absorption capacity of solar cells. Reduced graphene materials, or composite materials of titanium dioxide and reduced graphene, can also enhance the long- and short-wavelength absorption capabilities of solar cells.

[0053] In some embodiments, the thickness of the light absorbing layer 102 is 20 nm to 50 nm, such as 23 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, or 48 nm. Regarding the thickness of the light absorbing layer 102, the greater the thickness of the light absorbing layer 102, the stronger the light absorption capability provided by the light absorbing layer 102. However, if the thickness of the light absorbing layer 102 is too large, parasitic light absorption may occur in the light absorbing layer 102, which may in turn affect the photoelectric conversion efficiency of the solar cell. Therefore, setting the thickness of the light absorbing layer 102 to 20 nm to 50 nm can enable the light absorbing layer 102 to improve the light absorption capability of the solar cell while avoiding a negative impact on the photoelectric conversion efficiency of the solar cell.

[0054] In some embodiments, the reduced graphene has a particle size of 5 nm to 20 nm, for example, 8 nm, 10 nm, 13 nm, 15 nm, 17 nm, 18 nm, or 19 nm. Regarding the particle size of the reduced graphene, the smaller the particle size of the reduced graphene, the higher the density of the light absorbing layer 102. However, the smaller the particle size of the reduced graphene, the more difficult it is to form the light absorbing layer 102. Therefore, setting the particle size of the reduced graphene to 5 nm to 20 nm can further increase the density of the light absorbing layer 102 while taking into account the difficulty of forming the light absorbing layer 102, thereby improving the light absorption capacity of the light absorbing layer 102.

[0055] In some embodiments, the light absorbing layer 102 contains hydrogen ions, and the content of hydrogen ions is e18Atoms / cm3 to e19Atoms / cm 3 After the light absorbing layer 102 is formed, the hydrogen ions in the light absorbing layer 102 will be liberated to the surface of the substrate 100. The hydrogen ions bond with the dangling bonds on the surface of the substrate 100, which can repair the substrate 100 and improve the passivation ability of the light absorbing layer 102.

[0056] It is understood that, through experimental tests, the embodiments of the present disclosure can improve the photoelectric conversion efficiency of solar cells by 0.04% to 0.08%, the open circuit voltage by 1 mV to 2 mV, and the fill factor by 0.03% to 0.10%.

[0057] In some embodiments, the solar cell may further include: a tunneling layer 105, the tunneling layer 105 being located on the back side 120 of the substrate 100, and the tunneling layer 105 having a chemical passivation effect on the back side 120, specifically by saturating the dangling bonds on the back side 120, reducing the defect state density on the back side 120, and reducing the recombination centers on the surface of the substrate 100 to reduce the carrier recombination rate.

[0058] The material of the tunneling layer 105 may include at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride.

[0059] The solar cell may also include a doped conductive layer 106, which is located on the surface of the tunneling layer 105 away from the substrate 100. The concentration of the doping element in the doped conductive layer 106 is greater than that of the substrate 100, thereby forming a sufficiently high potential barrier on the back surface 120 of the substrate 100. This barrier can induce energy band bending on the back surface 120, thereby achieving the aggregation of majority carriers and the depletion of minority carriers on the back surface 120, thereby reducing carrier recombination on the back surface 120. The tunneling layer 105 can cause an asymmetric shift in the energy band on the back surface 120, making the barrier for majority carriers lower than that for minority carriers. As a result, majority carriers can more easily undergo quantum tunneling through the tunneling layer 105 and be transported into the doped conductive layer 106, while minority carriers have difficulty passing through the tunneling layer 105, thereby achieving selective carrier transport. Furthermore, the tunneling layer 105 also provides a chemical passivation effect. Specifically, due to the presence of interface state defects at the interface between the substrate 100 and the tunneling layer 105, the interface state density on the back side 120 is relatively large. The increase in the interface state density promotes the recombination of photogenerated carriers, reduces the fill factor, short-circuit current and open-circuit voltage of the solar cell, and thus makes the photoelectric conversion efficiency of the solar cell lower.

[0060] The doped conductive layer 106 also has a field passivation effect. Specifically, the doped conductive layer 106 forms an electrostatic field on the back surface 120 of the substrate 100 that points into the interior of the substrate 100, causing minority carriers to escape from the interface, thereby reducing the minority carrier concentration and the carrier recombination rate at the interface of the substrate 100. This increases the open-circuit voltage, short-circuit current, and fill factor of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell.

[0061] The material of the doped conductive layer 106 may include at least one of amorphous silicon, polysilicon, or silicon carbide.

[0062] The solar cell may further include: a back passivation layer 107, the back passivation layer 107 covering the surface of the doped conductive layer 106 away from the substrate 100, and the back passivation layer 107 can play a good passivation role on the back side 120 of the substrate 100, for example, it can better chemically passivate the dangling bonds on the back side 120, saturate the dangling bonds on the back side 120, reduce the defect state density on the back side 120, and inhibit carrier recombination on the back side 120.

[0063] The material of the back passivation layer 107 can be one of silicon oxide, aluminum oxide, silicon nitride or silicon oxynitride.

[0064] The back passivation layer 107 can be a single-layer structure or a multi-layer structure. For a multi-layer structure, the materials of different layers can be different from each other, or the materials of some layers can be the same and different from the materials of other layers. For example, the back passivation layer 107 can be a multi-layer structure of a silicon nitride layer and an aluminum oxide layer.

[0065] The solar cell may further include: a back electrode 108, which is electrically connected to the doped conductive layer 106. The majority carriers in the substrate 100 tunnel into the doped conductive layer 106 through the tunneling layer 105. The majority carriers transmitted to the doped conductive layer 106 are then transmitted to the back electrode 108 that is in electrical contact with the doped conductive layer 106 and are collected by the back electrode 108.

[0066] The edges of the velvet structure 130 in the embodiment of the present disclosure are arc-shaped, that is, the velvet structure 130 is rounded. The arc-shaped edges will reduce the tip potential energy of the velvet structure 130. At the same time, the velvet structure 130 has a side surface greater than or equal to 4, so that the roughness of the surface of the velvet structure 130 is improved. In this way, the velvet structure 130 on the surface of the substrate 100 has the characteristics of roundness and increased roughness, which is convenient for the formation of the emitter and the light absorbing layer 102, increases the density of the light absorbing layer 102, increases the light absorbing capacity of the light absorbing layer 102, and improves the photoelectric conversion efficiency of the solar cell.

[0067] An embodiment of the present disclosure further provides a method for manufacturing a solar cell, which can be used to form the above-mentioned solar cell. The method for manufacturing a solar cell provided by another embodiment of the present disclosure will be described below in conjunction with the accompanying drawings. It should be noted that the parts that are the same or corresponding to the above-mentioned embodiments can refer to the above-mentioned embodiments and will not be repeated below.

[0068] refer to Figure 3 , Figure 3 A flow chart of a method for manufacturing a solar cell provided in an embodiment of the present disclosure.

[0069] In some embodiments, a method for manufacturing a solar cell may include: forming a substrate, the substrate having a front side and a back side relative to each other, the front side having a velvet structure, the edges of the velvet structure being arc-shaped, and the velvet structure having n side surfaces, where n is a positive integer greater than or equal to 4.

[0070] The method for manufacturing a solar cell may further include: forming an emitter, wherein the emitter covers the front surface of the substrate.

[0071] The method for manufacturing a solar cell may further include: forming a light absorbing layer, wherein the light absorbing layer covers the surface of the emitter.

[0072] The method for manufacturing a solar cell may further include: forming a passivation layer, wherein the passivation layer covers the surface of the light absorbing layer.

[0073] The method for manufacturing a solar cell may further include: forming a front electrode, wherein the front electrode is in electrical contact with the emitter.

[0074] In some embodiments, a method for forming a substrate includes: providing an initial substrate having opposite front and back surfaces; performing a texturing process to form a velvet structure on at least the front surface; and performing a diffusion process to convert a portion of the initial substrate into an emitter, with the remaining initial substrate serving as the substrate. In other words, when forming the substrate and emitter, a portion of the initial substrate is converted into the emitter. Thus, when subsequently forming the light absorbing layer, the velvet structure on the substrate surface remains unchanged. When forming the light absorbing layer, the roughness of the substrate surface facilitates the formation of the light absorbing layer. Furthermore, because the velvet structure is additionally treated when forming the substrate, the material of the light absorbing layer is more easily attached to the substrate surface, thereby increasing the density of the formed light absorbing layer.

[0075] In some embodiments, the texturing process may include: a first texturing step, the first texturing step is used to form the morphology of a pyramid structure on the front side of the initial substrate; a second texturing step, the second texturing step is used to modify the pyramid structure, and during the modification process, the edges of the pyramid structure will be modified, and during the modification process, at least part of the pyramid structure with 4 sides will be converted into a velvet structure with more than 4 sides. On the one hand, the rounding of the edges of the velvet structure can reduce the potential energy of the substrate surface, and on the other hand, the specific surface area of the velvet structure is increased, further improving the roughness of the substrate.

[0076] In some embodiments, the first texturing step can be to corrode the initial substrate by using an alkaline etching agent to form the morphology of a pyramid structure, and the second texturing step can be to modify the pyramid structure by adding an auxiliary agent in combination with an alkaline etching agent. After adding the auxiliary agent, the etching process will preferentially etch the edges and corners of the pyramid structure, thereby completing the etching of the pyramid structure.

[0077] In some embodiments, a method for forming a light-absorbing layer may include synthesizing a reduced graphene material; and depositing the reduced graphene material onto the surface of the emitter using a deposition process to form the light-absorbing layer. Reduced graphene materials have high light absorption and high mechanical strength, and high light absorption can improve the light absorption capacity of solar cells.

[0078] In some embodiments, methods for synthesizing reduced graphene materials include: using a chemical reduction method, which includes mixing graphene oxide with a reducing agent such as hydrazine hydrate or L-ascorbic acid to form the reduced graphene material; or using a photocatalytic reduction method, which includes mixing graphene oxide with a photocatalyst under light conditions to form the reduced graphene material. The chemical reduction method involves treating graphene oxide with hydroxyl, carboxyl, carbonyl, or other groups on its flakes or edges in an aqueous solution or organic solvent to obtain a uniformly dispersed monolayer of graphene oxide, which is then treated with a reducing agent to obtain reduced graphene. The photocatalytic reduction method involves mixing graphene oxide with a photocatalyst, dispersing the mixture in an appropriate solvent, and then irradiating the mixture with visible light or ultraviolet light, where the photocatalyst promotes the reduction reaction of the graphene oxide.

[0079] The high hydrogen content and high light absorbance in reduced graphene can improve the light absorption and passivation capabilities of the light-absorbing layer. Combined with the low surface potential energy suede structure, it can further increase the open circuit voltage of the battery, thereby improving the photoelectric conversion efficiency of the battery.

[0080] In some embodiments, the deposition process parameters include ultrasonic deposition, an ultrasonic frequency of 20 kHz to 50 kHz, and a deposition temperature of 60° C. to 80° C. Ultrasonic deposition can control the particle size and distribution of the formed light absorbing layer, thereby improving the uniformity of the formed light absorbing layer.

[0081] Those skilled in the art will appreciate that the above-described embodiments are specific examples for implementing the present disclosure, and in actual applications, various changes may be made to them in form and detail without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, the scope of protection of the embodiments of the present disclosure shall be based on the scope defined in the claims.

Claims

1. A solar cell, characterized in that: include: A substrate, the substrate having a front side and a back side opposite to each other, the front side having a suede structure, the edges of the suede structure being arc-shaped, and the suede structure having n side surfaces, where n is a positive integer greater than or equal to 4; an emitter, the emitter covering the front surface of the substrate; a light absorbing layer, the light absorbing layer covering the surface of the emitter; a passivation layer, the passivation layer covering the surface of the light absorbing layer; A front electrode is in electrical contact with the emitter.

2. The solar cell according to claim 1, wherein: The material of the light absorbing layer includes reduced graphene material, or a composite material of titanium dioxide and reduced graphene.

3. The solar cell according to claim 2, wherein: The thickness of the light-absorbing layer is 20nm to 50nm, and the particle size of the reduced graphene is 5nm to 20nm.

4. The solar cell according to claim 1, wherein: The specific surface area of the velvet structure is 1.4 to 1.

6.

5. The solar cell according to claim 1, wherein: The light absorbing layer contains hydrogen ions, and the content of the hydrogen ions is e18Atoms / cm3 to e19Atoms / cm 3 .

6. The solar cell according to claim 1, wherein: The top of the velvet structure is a rounded spherical crown structure.

7. A method for manufacturing a solar cell, characterized in that: include: forming a substrate, wherein the substrate has a front surface and a back surface opposite to each other, the front surface having a suede structure, the edges of the suede structure being arc-shaped, and the suede structure having n side surfaces, where n is a positive integer greater than or equal to 4; forming an emitter electrode, wherein the emitter electrode covers the front surface of the substrate; forming a light absorbing layer, wherein the light absorbing layer covers the surface of the emitter; forming a passivation layer, wherein the passivation layer covers the surface of the light absorbing layer; A front electrode is formed, the front electrode being in electrical contact with the emitter.

8. The method for manufacturing a solar cell according to claim 7, wherein: The method of forming the substrate comprises: providing an initial substrate having opposing front and back surfaces; Performing a texturing process, wherein the texturing process forms the velvet structure at least on the front surface; A diffusion process is performed to convert a portion of the initial substrate into an emitter, with the remaining initial substrate serving as the substrate.

9. The method for manufacturing a solar cell according to claim 7, wherein: The method of forming the light absorbing layer includes: Synthesize reduced graphene materials; A deposition process is adopted to deposit the reduced graphene material onto the surface of the emitter to form the light absorbing layer.

10. The method for manufacturing a solar cell according to claim 9, wherein: The process parameters of the deposition process include: ultrasonic deposition, the frequency of the ultrasonic wave is 20KHz to 50KHz, and the temperature of the deposition process is 60°C to 80°C.

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