Solar cell, photovoltaic module and preparation method of solar cell

Abstract

The invention relates to the technical field of photovoltaics, in particular to a solar cell, a photovoltaic module and a preparation method of the solar cell. The solar cell comprises a substrate, the substrate is provided with an electrode surface, a doped region is formed on the electrode surface, and a doped semiconductor layer, a surface passivation layer and a metal electrode are arranged on the inner layer of the doped region; the metal electrode at least partially penetrates through the surface passivation layer and is in contact with the doped semiconductor layer, and an interface connection structure is arranged on the surface, in contact with the metal electrode, of the doped semiconductor layer. According to the arrangement, the bonding strength of the metal electrode and the doped semiconductor layer is improved, and the phenomenon that the metal electrode falls off when the welding strip is subjected to a pulling force is prevented.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and in particular to a solar cell, a photovoltaic module, and a method for preparing a solar cell. Background Technology

[0002] In existing technologies, solar cells with tunneling oxide passivation contact structures typically have the tunneling oxide layer and doped semiconductor layer formed on a polished surface. For example, the back side of the silicon substrate in a back-contact cell is usually prepared as a polished surface to improve back-side passivation, reduce back-side recombination, and improve the cell's open-circuit voltage. However, the polished silicon substrate surface is too flat, leading to a reduction in the contact area between the formed metal electrode and the silicon substrate surface, and a decrease in electrode adhesion. When the solder ribbons bonded to the metal electrodes are subjected to tensile force, the solder ribbons can pull the metal electrodes off the cell surface, thus affecting cell performance and module reliability. Summary of the Invention

[0003] The first objective of this invention is to provide a solar cell that solves the technical problem in the prior art where metal electrodes easily detach from the cell surface, thereby affecting cell performance and module reliability.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A solar cell includes a substrate having an electrode surface. A doped region is formed on the electrode surface. A doped semiconductor layer, a surface passivation layer, and a metal electrode are sequentially disposed within the doped region. The metal electrode at least partially penetrates the surface passivation layer and contacts the doped semiconductor layer. An interface connection structure is disposed on the surface of the doped semiconductor layer that contacts the metal electrode. The interface connection structure is used to connect the doped semiconductor layer and the metal electrode. The material of the interface connection structure includes at least one of the material elements contained in the surface passivation layer.

[0005] The beneficial effects of setting an interface connection structure between the doped semiconductor layer and the metal electrode are as follows: on the one hand, it reduces the exposed area of ​​the doped semiconductor layer, thereby reducing surface recombination of the battery and improving the open circuit voltage of the battery; on the other hand, it increases the bonding strength between the metal electrode and the doped semiconductor layer, preventing the metal electrode from falling off when the solder ribbon is subjected to tensile force, and improving the performance and reliability of the battery.

[0006] In some embodiments, the first interface connection structure and the second interface connection structure each include a plurality of protrusions.

[0007] By creating protrusions on the surface of the contact metal electrode of the doped semiconductor layer, an uneven structure is formed on the surface, thereby increasing the bonding strength between the metal electrode and the doped semiconductor layer.

[0008] In some embodiments, the plurality of protrusions includes a plurality of granular protrusions and / or a plurality of strip-shaped protrusions.

[0009] Both granular and strip-shaped bumps protrude from the surface of the contact metal electrode of the doped semiconductor layer, creating an uneven structure on that surface. This surface can have one or a combination of granular and strip-shaped bumps. In some embodiments: the plurality of granular protrusions of the first interface connection structure are randomly discrete or lattice-shaped distributed; and / or, The plurality of strip-shaped protrusions in the first interface connection structure are distributed in a striped, grid-like, intersecting, or discrete pattern; and / or, The plurality of granular protrusions in the second interface connection structure are randomly discrete or lattice-shaped distributed; and / or, The plurality of strip-shaped protrusions in the second interface connection structure are distributed in a striped, grid-like, intersecting, or discrete pattern; and / or, The surfaces of the granular protrusions and / or the strip-shaped protrusions are serrated.

[0010] Granular protrusions can be uniformly arrayed or unevenly dispersed on the metal contact surface, while strip-shaped protrusions can be either interlocked or dispersed. In short, the distribution of protrusions only needs to create an uneven structure on the metal contact surface. Among these, protrusions with a serrated surface can increase the contact area with the metal electrode, thereby improving the connection strength between the protrusion and the metal electrode.

[0011] In some embodiments: the protrusion height of the interface connection structure relative to the surface of the doped semiconductor layer is 10 nm to 300 nm; and / or, The lateral dimension of the granular protrusions is 50~3500nm; and / or, The width of the strip-shaped protrusion is 50~3500nm; and / or, The ratio of the contact area between the interface connection structure and the doped semiconductor layer to the contact area between the metal electrode and the doped semiconductor layer is 0.1% to 5%.

[0012] The material, thickness, and contact area between the interface connection structure and the doped semiconductor layer can be selected within the aforementioned preferred range. Within this parameter range, the battery can ensure good ohmic contact between the doped semiconductor layer and the metal electrode while preventing metal electrode detachment and reducing surface recombination.

[0013] In some embodiments (e.g., TBC batteries): the substrate is a monocrystalline silicon wafer; and / or, The material of the doped semiconductor layer includes at least one of doped polycrystalline silicon, doped polycrystalline silicon oxide, and doped polycrystalline silicon carbide; and / or, The thickness of the doped semiconductor layer is 50~500 nm; and / or, The metal electrode material includes at least one element selected from Ag, Al, Cu, Ni, Ti, W, and Sn; and / or, The thickness of the metal electrode is 3~30 μm.

[0014] The materials and thicknesses of the doped semiconductor layer and the metal electrode can be selected within the aforementioned preferred range.

[0015] In some embodiments, an interface passivation layer disposed between the electrode surface and the doped semiconductor layer is further provided in the doped region; The material of the interface passivation layer includes at least one of silicon oxide, aluminum oxide, silicon oxynitride, and silicon nitride, and / or the thickness of the interface passivation layer is 1~3nm.

[0016] The main function of the interface passivation layer is to protect the substrate and enhance the stability and lifespan of the battery. The thickness of the interface passivation layer should not be too thin, as this will result in poor protection. At the same time, the thickness of the interface passivation layer should not be too thick, as this will affect the carrier transport efficiency. Setting the thickness of the interface passivation layer in the range of 1~3nm can effectively protect the substrate without affecting the carrier transport efficiency.

[0017] In some embodiments, the electrode surface is the backlight surface of the substrate, and a first doped region and a second doped region are formed on the electrode surface, which are alternately arranged along the X direction. The first doped region and the second doped region have opposite conductivity types. A first doped semiconductor layer and a first metal electrode are sequentially disposed in the first doped region, and a second doped semiconductor layer and a second metal electrode are sequentially disposed in the second doped region. A first interface connection structure is provided on the surface of the first doped semiconductor layer that contacts the first metal electrode, and a second interface connection structure is provided on the surface of the second doped semiconductor layer that contacts the second metal electrode.

[0018] The above embodiments provide a back-contact solar cell in which all metal electrodes are integrated on the back surface of the substrate, leaving the front side unobstructed by grid lines. This allows for the absorption of more sunlight and results in higher short-circuit current and photoelectric conversion efficiency. Because the doped semiconductor layer of this back-contact solar cell has an interface connection structure, the electrode adhesion is more than 1.5 times stronger than that of existing back-contact solar cells. This makes the metal electrodes less prone to detachment under tension, resulting in higher performance and reliability compared to existing technologies.

[0019] In some embodiments, the electrode surface is the light-receiving surface and the back-light-receiving surface of the substrate. The back-light-receiving surface has a first doped region, and the light-receiving surface has a plurality of second doped regions spaced apart along the X-direction. The first and second doped regions have opposite conductivity types. A first doped semiconductor layer and a first metal electrode are sequentially layered within the first doped region, and a second doped semiconductor layer and a second metal electrode are sequentially layered within the second doped region. A first interface connection structure is provided on the surface of the first doped semiconductor layer that contacts the first metal electrode. Further, a second interface connection structure may also be provided on the surface of the second doped semiconductor layer that contacts the second metal electrode; and / or, the back-light-receiving surface has a plurality of the first doped regions spaced apart along the X-direction.

[0020] The above embodiment provides a bifacial solar cell, wherein both the light-receiving surface and the back-lighting surface of the cell substrate are electrode surfaces. A first interface connection structure is provided at least on the surface where the first doped semiconductor layer contacts the first metal electrode. This first interface connection structure strengthens the bonding strength between the first doped semiconductor layer and the first metal electrode, thereby preventing the first metal electrode from detaching. Alternatively, a second interface connection structure can be provided on the surface where the second doped semiconductor layer contacts the second metal electrode, thereby strengthening the bonding strength between the second doped semiconductor layer and the second metal electrode.

[0021] Taking TOPCon cells as an example: the substrate is an N-type monocrystalline silicon wafer; the material of the first doped semiconductor layer includes at least one of N-type doped polycrystalline silicon, N-type doped polycrystalline silicon oxide, and N-type doped polycrystalline silicon carbide; the first doped semiconductor layer can be disposed on the entire back surface, or it can be formed on the back surface with a back poly-finger structure having multiple first doped regions spaced apart along the X direction; the second doped semiconductor layer can also be formed on the light-receiving surface with a front poly-finger structure having multiple second doped regions spaced apart along the X direction. As mentioned above, a partial doping layer can be formed on the front side of a bifacial solar cell, which can reduce parasitic absorption and have higher short-circuit current and photoelectric conversion efficiency; a partial doping layer can also be formed on the back side of a bifacial solar cell to reduce parasitic absorption and have higher short-circuit current and photoelectric conversion efficiency; of course, a full-surface doped layer can also be formed on the back side of a bifacial solar cell. Because the doped semiconductor layer of this bifacial solar cell has an interface connection structure, the electrode adhesion of this bifacial solar cell is more than 1.5 times higher than that of back-contact solar cells in the prior art. This makes the metal electrodes of this bifacial solar cell less likely to fall off under tension, and its performance and reliability are higher than those of the prior art.

[0022] A second objective of this invention is to provide a photovoltaic module comprising the solar cell described in any of the preceding claims. The photovoltaic module possesses at least all the technical features and effects of the aforementioned solar cell, which will not be elaborated further here.

[0023] A third objective of the present invention is to provide a method for preparing a solar cell, comprising: forming a plurality of protrusions on the surface of a doped semiconductor layer in contact with the metal electrode before forming a metal electrode on a substrate of the solar cell.

[0024] By forming several protrusions on the surface of the metal electrode contacting the doped semiconductor layer, an uneven structure is created on the surface, thereby increasing the bonding strength between the metal electrode and the doped semiconductor layer. This prevents the metal electrode from detaching under tensile stress, improving battery performance and reliability. Furthermore, the protrusions reduce the exposed area of ​​the doped semiconductor layer, thereby reducing surface recombination and improving the battery's open-circuit voltage. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the back structure of a solar cell provided in Embodiment 1 of the present invention; Figure 2 for Figure 1 The diagram shows the structure after the metal electrode has been removed. Figure 3 for Figure 1 Cross-sectional view at point AA; Figure 4 This is a schematic diagram of the back structure of a solar cell after the metal electrodes have been removed, according to an embodiment of the present invention. Figure 5 This is a schematic diagram of the back structure of a solar cell after the metal electrodes have been removed, provided in another embodiment of the present invention (Embodiment 2). Figure 6 This is a schematic diagram of the back structure of a solar cell after the metal electrodes have been removed, according to an embodiment of the present invention (Embodiment 3). Figure 7 This is a schematic diagram of the back structure of a solar cell after the metal electrodes have been removed, provided in another embodiment of the present invention (Embodiment 3). Figure 8 for Figure 6 Cross-sectional view at point BB; Figure 9 This is a schematic diagram of the back structure of the solar cell after the metal electrode has been removed, as provided in Embodiment 4 of the present invention. Figure 10 The flowcharts are for the methods of preparing solar cells provided in Embodiments 5 and 6 of the present invention.

[0027] icon: 1-Substrate; 11-Electrode surface; 12-First doped region; 13-Second doped region; 14-Isolation region; 21 - First doped semiconductor layer; 22 - Second doped semiconductor layer; 31-First metal electrode; 32-Second metal electrode; 41 - First interface connection structure; 42 - Second interface connection structure; 51 - First interface passivation layer; 52 - Second interface passivation layer; 61-First surface passivation layer; 611-Metal contact area; 62-Second surface passivation layer; 7-Isolation material layer. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] It should be noted that in the description of this invention, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] It should be noted that in the description of this invention, the terms "connection" and "installation" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or a connection through an intermediate medium; they can refer to a mechanical connection or an electrical connection. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] Addressing the technical problem in existing technologies where metal electrodes easily detach from the battery surface, thus affecting battery performance and component reliability, the first aspect of this application provides a solar cell, referring to... Figures 1 to 9 The solar cell includes a substrate 1, at least one of the light-receiving surface and the back-lighting surface of the substrate 1 is an electrode surface 11, a doped region is formed on the electrode surface 11, and a doped semiconductor layer, a surface passivation layer and a metal electrode are sequentially disposed in the doped region. The metal electrode at least partially penetrates the surface passivation layer and contacts the doped semiconductor layer. An interface connection structure is disposed on the surface of the doped semiconductor layer that contacts the metal electrode. The interface connection structure is used to connect the doped semiconductor layer and the metal electrode. The material of the interface connection structure includes at least one of the material elements contained in the surface passivation layer.

[0032] The beneficial effects of setting protrusions between the doped semiconductor layer and the metal electrode are as follows: on the one hand, it reduces the exposed area of ​​the doped semiconductor layer, thereby reducing surface recombination of the battery and improving the open-circuit voltage of the battery; on the other hand, it increases the bonding strength between the metal electrode and the doped semiconductor layer, preventing the metal electrode from falling off when the solder ribbon is subjected to tensile force, thus improving the performance and reliability of the battery.

[0033] When only the backlight surface of substrate 1 is an electrode surface 11, the solar cell is a back-contact solar cell. When both the light-receiving surface and the backlight surface of substrate 1 are electrode surfaces 11, the solar cell is a bifacial solar cell. The solar cell provided in this application can be a bifacial solar cell or a back-contact solar cell. Furthermore, the solar cell can be a multi-busbar solar cell or an OBB solar cell. This application does not limit the type of solar cell.

[0034] In an embodiment where the solar cell is a back-contact solar cell: Refer to Figure 3 The electrode surface 11 serves as the backlight surface of the substrate 1. A first doped region 12 and a second doped region 13, arranged alternately along the X-direction, are formed on the electrode surface 11. The first doped region 12 and the second doped region 13 have opposite conductivity types. A first doped semiconductor layer 21 and a first metal electrode 31 are sequentially layered within the first doped region 12, and a second doped semiconductor layer 22 and a second metal electrode 32 are sequentially layered within the second doped region 13. A first interface connection structure 41 is provided on the surface of the first doped semiconductor layer 21 that contacts the first metal electrode 31, and a second interface connection structure 42 is provided on the surface of the second doped semiconductor layer 22 that contacts the second metal electrode 32. All the metal electrodes of this solar cell are integrated on the backlight surface of the substrate, leaving the front side unobstructed by grid lines. This allows for the absorption of more sunlight, resulting in higher short-circuit current and photoelectric conversion efficiency. Because the doped semiconductor layer of this back-contact solar cell has an interface connection structure, the electrode adhesion of this back-contact solar cell is more than 1.5 times higher than that of back-contact solar cells in the prior art. This makes the metal electrode of this back-contact solar cell less likely to fall off under tensile force, and its performance and reliability are higher than those of the prior art.

[0035] In an embodiment where the solar cell is a bifacial solar cell: the electrode surface 11 serves as the light-receiving surface and the back-lighting surface of the substrate 1. A first doped region 12 is formed on the back-lighting surface, and a plurality of second doped regions 13 are spaced apart along the X-direction on the light-receiving surface. The first doped region 12 and the second doped region 13 have opposite conductivity types. A first doped semiconductor layer 21 and a first metal electrode 31 are sequentially layered within the first doped region 12, and a second doped semiconductor layer 22 and a second metal electrode 32 are sequentially layered within the second doped region 13. A first interface connection structure 41 is provided on the surface of the first doped semiconductor layer 21 that contacts the first metal electrode 31. Based on the above structure, as an optional embodiment: a second interface connection structure 42 may also be provided on the surface of the second doped semiconductor layer 22 that contacts the second metal electrode 32; and / or, the back-lighting surface forms a plurality of first doped regions 12 spaced apart along the X-direction.

[0036] Taking TOPCon battery as an example: the substrate 1 is preferably an N-type monocrystalline silicon wafer; the material of the first doped semiconductor layer 21 includes at least one of N-type doped polycrystalline silicon, N-type doped polycrystalline silicon oxide, and N-type doped polycrystalline silicon carbide; the first doped semiconductor layer 21 can be disposed on the entire backlight surface, or it can be a back poly-finger structure with multiple first doped regions 12 spaced apart along the X direction on the backlight surface; the second doped semiconductor layer 22 can also be a front poly-finger structure with multiple second doped regions 13 spaced apart along the X direction on the light-receiving surface.

[0037] As described above, the bifacial solar cell provided in this application can have a locally doped layer formed on its front side. This configuration reduces parasitic absorption and results in higher short-circuit current and photoelectric conversion efficiency. Similarly, a locally doped layer can also be formed on its back side to reduce parasitic absorption and achieve higher short-circuit current and photoelectric conversion efficiency. Alternatively, the entire back side of the bifacial solar cell can be doped. Because the doped semiconductor layer of this bifacial solar cell has an interface connection structure, the electrode adhesion of this bifacial solar cell is more than 1.5 times stronger than that of back-contact solar cells in the prior art. This makes the metal electrodes of this bifacial solar cell less prone to detachment under tensile force, resulting in higher performance and reliability compared to existing technologies.

[0038] Furthermore, the interface connection structure includes several protrusions. Specifically, the first interface connection structure 41 and the second interface connection structure 42 each include several protrusions. These protrusions include several granular protrusions and / or several strip-shaped protrusions. As optional embodiments: the granular protrusions of the first interface connection structure 41 are randomly discrete or lattice-shaped; and / or, the strip-shaped protrusions of the first interface connection structure 41 are striped, grid-shaped, intersecting, or randomly discrete; and / or, the granular protrusions of the second interface connection structure 42 are randomly discrete or lattice-shaped; and / or, the strip-shaped protrusions of the second interface connection structure 42 are striped, grid-shaped, intersecting, or discrete.

[0039] The surface of the doped semiconductor layer that contacts the metal electrode is called the metal contact surface. Specifically, the first doped semiconductor layer 21 has a first metal contact surface, and the second doped semiconductor layer 22 has a second metal contact surface. Whether granular or strip-shaped protrusions, they all protrude from the metal contact surface of the doped semiconductor layer, creating an uneven structure on the metal contact surface, thereby increasing the bonding strength between the metal electrode and the doped semiconductor layer. Each metal contact surface can have one or a combination of granular and strip-shaped protrusions. Granular protrusions can be uniformly arrayed or unevenly dispersed on the metal contact surface, while strip-shaped protrusions can be interlocked or dispersed on the metal contact surface. In short, the distribution of the protrusions only needs to create an uneven structure on the metal contact surface.

[0040] In some embodiments, the surfaces of the granular protrusions and / or strip protrusions are serrated, which can increase the contact area between the protrusions and the metal electrode and improve the connection strength between the protrusions and the metal electrode.

[0041] In some embodiments, in a corresponding set of doped semiconductor layers, metal electrodes, and interface connection structures, the ratio of the contact area between the interface connection structure and the doped semiconductor layer to the contact area between the metal electrode and the doped semiconductor layer is 0.1% to 5%. If this ratio exceeds the above range, the contact area between the interface connection structure and the doped semiconductor layer is too large, resulting in an insufficient contact area between the metal electrode and the doped semiconductor layer, which in turn leads to excessive current collection resistance. Conversely, if this ratio is below the above range, the improvement in the adhesion of the metal electrode to the doped semiconductor layer is too small, resulting in poor improvement in the problem of easy detachment of the metal electrode.

[0042] Furthermore, the interface connection structure can be as follows: Figure 4 The adhesion shown can be applied to the entire metal contact surface or to a localized area of ​​the metal contact surface. For example, when the passivation layer opening is small, the contact area between the doped semiconductor layer and the metal electrode is small. To avoid excessive current collection resistance caused by the increased interface connection structure, interface connection structures can be set only at both ends of the doped semiconductor layer. This ensures good ohmic contact between the doped semiconductor layer and the metal electrode while increasing adhesion at the location where the metal electrode is most prone to loosening. As another example, when the passivation layer opening is large, the contact area between the doped semiconductor layer and the metal electrode is large. The overall size and coverage area of ​​the interface connection structure can be appropriately increased to prevent metal electrode detachment and reduce surface recombination.

[0043] In some embodiments, the material of the interface connection structure includes Si, and at least two elements selected from O, N, Al, C, P, and B. For example, the material of the interface connection structure is at least one selected from silicon oxide, aluminum oxide, silicon oxynitride, silicon nitride, and silicon carbide. As another example, the material of the interface connection structure is at least one selected from silicon-rich silicon oxide, silicon-rich aluminum oxide, silicon-rich silicon nitride, silicon-rich silicon oxynitride, and silicon-rich silicon carbide. The "at least one" includes one material, a combination of several materials, and a combination of all materials.

[0044] In some embodiments, the protrusion height of the interface connection structure relative to the surface of the doped semiconductor layer is 10 nm to 300 nm; and / or, the lateral dimension of the particle-type protrusion is 50 to 3500 nm; and / or, the width of the strip-type protrusion is 50 to 3500 nm. Setting the size of the protrusion within the above range can ensure the bonding strength between the metal electrode and the doped semiconductor layer and good ohmic contact between them.

[0045] In some embodiments, substrate 1 is an N-type silicon substrate, specifically an N-type single-crystal silicon wafer. In other embodiments, substrate 1 may also be a P-type silicon substrate.

[0046] In some embodiments, the first doped semiconductor layer 21 is made of at least one of N-type doped polycrystalline silicon, N-type doped polycrystalline silicon oxide, and N-type doped polycrystalline silicon carbide. The second doped semiconductor layer 22 is made of at least one of P-type doped polycrystalline silicon, P-type doped polycrystalline silicon oxide, and P-type doped polycrystalline silicon carbide.

[0047] In some embodiments, the peak doping concentrations of the first doped semiconductor layer 21 and the second doped semiconductor layer 22 are 1e19~1e21cm, respectively. -3 .

[0048] In some embodiments, the thicknesses of the first doped semiconductor layer 21 and the second doped semiconductor layer 22 are 50~500nm, respectively.

[0049] In some embodiments, the first metal electrode 31 and the second metal electrode 32 are made of at least one element selected from Ag, Al, Cu, Ni, Ti, W, and Sn. The metal electrodes can be elemental metals or alloys composed of multiple elements.

[0050] In some embodiments, the thicknesses of the first metal electrode 31 and the second metal electrode 32 are 3~30 μm, respectively.

[0051] In some embodiments, an interface passivation layer is further disposed within the doped region, positioned between the electrode surface 11 and the doped semiconductor layer. Specifically, a first interface passivation layer 51 is disposed within each first doped region 12, the first interface passivation layer 51 being located between the electrode surface 11 and the first doped semiconductor layer 21; a second interface passivation layer 52 is disposed within each second doped region 13, the second interface passivation layer 52 being located between the electrode surface 11 and the second doped semiconductor layer 22. The main function of the interface passivation layer is to protect the substrate 1 and enhance the stability and lifespan of the battery.

[0052] In some embodiments, the material of the interface passivation layer (including the first interface passivation layer 51 and the second interface passivation layer 52) includes at least one of silicon oxide, aluminum oxide, silicon oxynitride, silicon nitride, and silicon carbide.

[0053] In some embodiments, the thickness of the interface passivation layer (including the first interface passivation layer 51 and the second interface passivation layer 52) is 1~3nm.

[0054] In an embodiment where the solar cell is a back-contact solar cell: the solar cell further includes a first surface passivation layer 61 covering the electrode surface 11 (i.e., the backlight surface of the substrate 1) and a second surface passivation layer 62 covering the light-receiving surface of the substrate 1; the first surface passivation layer 61 covers each of the first doped semiconductor layers 21 and each of the second doped semiconductor layers 22, the first metal electrode 31 at least partially penetrates the first surface passivation layer 61 and contacts the first doped semiconductor layer 21, and the second metal electrode 32 at least partially penetrates the first surface passivation layer 61 and contacts the second doped semiconductor layer 22. Further, the light-receiving surface of the substrate 1 is one of a positive pyramid textured surface, an inverted pyramid textured surface, or a black silicon textured surface; setting the light-receiving surface of the substrate 1 as a textured surface can reduce surface reflection loss of light and improve light absorption efficiency.

[0055] In some embodiments, the surface passivation layer (including the first surface passivation layer 61 and the second surface passivation layer 62) is made of at least one of silicon nitride, silicon oxynitride, silicon oxide, and aluminum oxide.

[0056] In some embodiments, the refractive indices of the first surface passivation layer 61 and the second surface passivation layer 62 are 1.8 to 2.3, respectively; and / or, the thicknesses of the first surface passivation layer 61 and the second surface passivation layer 62 are 50-250 nm, respectively.

[0057] It is understood that the "coverage" described in this application can be either directly attached to the surface or indirectly covered. For example, the first surface passivation layer 61 and the doped semiconductor layer are in contact with each other, or other films are provided between the first surface passivation layer 61 and the doped semiconductor layer.

[0058] A second aspect of this application provides a photovoltaic module, which includes the solar cell provided in the first aspect embodiment. Further, the photovoltaic module includes multiple strings of cells arranged in a flat arrangement and an encapsulation layer covering each string of cells, each string of cells including several solar cells connected in series. This photovoltaic module includes all the technical features and effects of the solar cell, which will not be repeated here.

[0059] A third aspect of this application provides a method for fabricating a solar cell. The method includes forming a plurality of protrusions on the surface of a contact metal electrode of a doped semiconductor layer before forming a metal electrode on a substrate 1. Because the surface of the contact metal electrode of the doped semiconductor layer has protrusions, it forms an uneven structure, thereby increasing the bonding strength between the surface and the metal electrode and preventing the metal electrode from detaching. Furthermore, the protrusions reduce the exposed area of ​​the doped semiconductor layer, thereby reducing surface recombination of the cell and improving the open-circuit voltage of the cell.

[0060] The following examples further illustrate the solar cell structure and its fabrication method provided in this application.

[0061] Example 1 Reference Figures 1 to 3 , Figure 1 This is a schematic diagram of the back structure of the solar cell provided in this embodiment. Figure 2 for Figure 1 The diagram shows the structure after the metal electrode has been removed. Figure 3 for Figure 1 The cross-sectional view at point AA shows that in the solar cell provided in this embodiment, the solar cell uses an N-type monocrystalline silicon wafer as the substrate 1. The backlight surface of the substrate 1 is the electrode surface 11, on which a first doped region 12, a second doped region 13, and an isolation region 14 are formed. The first doped region 12 and the second doped region 13 are alternately spaced along the X-direction, and the gap between any adjacent first doped region 12 and second doped region 13 forms the isolation region 14. The electrode surface 11 has a groove and / or an isolation material layer 7 within each isolation region 14. Figure 3 As shown, both the groove and the isolation material layer 7 serve to isolate the first doped region 12 and the second doped region 13. They can be used individually or in combination.

[0062] Furthermore, the substrate 1 has a thickness of 130 μm and a resistivity of 10 Ωcm. The width of the first doped region 12 is 400 μm, the width of the second doped region 13 is 95 μm, and the width of the isolation region 14 is 5 μm.

[0063] Within each first doped region 12, a first interface passivation layer 51, a first doped semiconductor layer 21, and a first metal electrode 31 are sequentially stacked on the electrode surface 11. Specifically: the first interface passivation layer 51 is made of silicon oxide and has a thickness of 1.5 nm; the first doped semiconductor layer 21 is made of N-type doped polysilicon and has a peak doping concentration of 4e20cm⁻¹. -3 The thickness of the first metal electrode 31 is 150 nm; the material of the first metal electrode 31 is a composite film containing AlSi alloy and Cu, and the thickness of the first metal electrode 31 is 10 μm.

[0064] Within each second doped region 13, a second interface passivation layer 52, a second doped semiconductor layer 22, and a second metal electrode 32 are sequentially stacked on the electrode surface 11. Specifically: the second interface passivation layer 52 is made of silicon oxide and has a thickness of 1.8 nm; the second doped semiconductor layer 22 is made of p-type doped polysilicon and has a peak doping concentration of 3e19 cm⁻¹. -3 The thickness of the first metal electrode is 200 nm; the second metal electrode 32 is a composite film containing AlSi alloy and Cu, with a thickness of 10 μm.

[0065] The solar cell also includes a first surface passivation layer 61, which covers each doped semiconductor layer and covers each isolation region 14 on the electrode surface 11. The first surface passivation layer 61 is a composite film made of aluminum oxide and silicon nitride, wherein the aluminum oxide film has a thickness of 6 nm, and the silicon nitride film has a refractive index of 2.05 and a thickness of 80 nm.

[0066] In this embodiment, refer to Figure 2 The first surface passivation layer 61 is subjected to a molding process at positions corresponding to each doped semiconductor layer, thereby forming multiple sets of holes on the first surface passivation layer 61. These multiple sets of holes correspond one-to-one with multiple doped semiconductor layers. Each set of holes includes multiple through-holes arrayed along the length or both length and width directions of the corresponding doped semiconductor layer. Each doped semiconductor layer is exposed through its corresponding multiple through-holes to achieve contact between the doped semiconductor layer and the metal electrode. Specifically, the first metal electrode 31 partially passes through the corresponding through-hole and contacts the first doped semiconductor layer 21, and the second metal electrode 32 partially passes through the corresponding through-hole and contacts the second doped semiconductor layer 22. Several or all of the through-holes in each set of holes contain several granular protrusions.

[0067] In other words, granular protrusions can be provided in each through hole individually, or in only some of the through holes. For example, granular protrusions can be provided only in several through holes located at both ends of each group of holes.

[0068] The height of the granular protrusion is 10 nm to 300 nm, and its lateral dimension is 50 to 3500 nm. Its material is composed of Si, O, N, Al, and P elements. Furthermore, the cross-section of the granular protrusion can be polygonal, circular, elliptical, or irregular, and its overall shape can be conical, cylindrical, hemispherical, etc. There are no restrictions on the shape of the granular protrusion. When the cross-section of the granular protrusion is circular, the diameter of the granular protrusion is preferably 1 to 2 μm.

[0069] Furthermore, the first interface connection structure 41 and the second interface connection structure 42 are made of composite films of aluminum oxide and silicon nitride, respectively, and their heights are 86nm.

[0070] Furthermore, in the corresponding set of doped semiconductor layers, metal electrodes, and interface connection structures, the ratio of the contact area between the interface connection structure and the doped semiconductor layer to the contact area between the metal electrode and the doped semiconductor layer is 0.1% to 1%.

[0071] Furthermore, the light-receiving surface of the solar cell is textured, specifically one of a regular pyramid textured surface, an inverted pyramid textured surface, or a black silicon textured surface. A second surface passivation layer 62 is covered on the light-receiving surface of the solar cell. The second surface passivation layer 62 is a composite film layer of aluminum oxide, silicon nitride, silicon oxynitride, and silicon oxide, with a refractive index of 2.0 and a thickness of 90 nm.

[0072] Example 2 Reference Figure 4 , Figure 4 This is a schematic diagram of the back structure of the solar cell after the metal electrodes have been removed, as provided in this embodiment. The difference between this embodiment and Embodiment 1 is that in this embodiment, an elongated hole is formed on the first surface passivation layer 61 at a position corresponding to each doped semiconductor layer. The width of each elongated hole is less than or equal to the width of the corresponding doped semiconductor layer, and the length of each elongated hole is less than or equal to the length of the corresponding doped semiconductor layer. Multiple discretely distributed granular protrusions are provided within each elongated hole. The two ends of the elongated hole along its length direction may or may not penetrate the first surface passivation layer 61.

[0073] Continue to refer to Figure 4 In one embodiment, the multiple granular protrusions within each elongated hole can be uniformly arrayed.

[0074] Reference Figure 5In another embodiment, the multiple granular protrusions within each elongated hole can also be unevenly distributed. Specifically, the number of granular protrusions within each elongated hole increases from the center towards both ends; that is, the granular protrusions are sparsely distributed in the center of the doped semiconductor layer, while they are densely distributed at both ends. This arrangement ensures good ohmic contact between the doped semiconductor layer and the metal electrode while increasing adhesion at the locations where the metal electrode is most prone to loosening.

[0075] The remaining structure of this embodiment is largely the same as that of Embodiment 1.

[0076] Example 3 The difference between this embodiment and the previous embodiments is as follows: Reference Figure 6 and Figure 7 In this embodiment, the first interface connection structure 41 and the second interface connection structure 42 each include a plurality of strip-shaped protrusions distributed in a stripe pattern. Specifically, an elongated hole is formed on the first surface passivation layer 61 at a position corresponding to each doped semiconductor layer. The width of each elongated hole is less than or equal to the width of the corresponding doped semiconductor layer, and the length of each elongated hole is less than or equal to the length of the corresponding doped semiconductor layer. A plurality of strip-shaped protrusions distributed in a stripe pattern are provided in each elongated hole.

[0077] Optionally, multiple strip protrusions can be Figure 6 The linear striped distribution shown can also be... Figure 7 The wavy stripe pattern shown is a characteristic of this distribution.

[0078] Reference Figure 8 In one embodiment, the surface of the strip-shaped protrusion is serrated. The protrusions on the surface of the strip-shaped protrusion can be triangular, hook-shaped, trapezoidal, rectangular, or other shapes, used to improve the connection strength between the protrusion and the metal electrode.

[0079] Furthermore, the materials of the first interface connection structure 41 and the second interface connection structure 42 are composed of five elements: Si, O, N, Al, and P. Specifically, the Si content is 55-65%; the N content is 35-45%; the oxygen content is 0.1-1%; the Al content is 0.1-1%; and the P content is 0-0.01%. The height of the materials of the first interface connection structure 41 and the second interface connection structure 42 is 50-200 nm, and their lateral width is 0.5-1.5 μm.

[0080] Furthermore, in the corresponding set of first doped semiconductor layer 21, first metal electrode 31 and first interface connection structure 41, the ratio of the contact area of ​​the first interface connection structure 41 and the first doped semiconductor layer 21 to the contact area of ​​the first metal electrode 31 and the first doped semiconductor layer 21 is 1% to 3%.

[0081] In this embodiment, the first metal electrode 31 and the second metal electrode 32 are made of Ti / W / Cu metal composite film with a thickness of 6 μm.

[0082] Example 4 The difference between this embodiment and Embodiment 3 is as follows: Reference Figure 9 In this embodiment, the first interface connection structure 41 and the second interface connection structure 42 respectively include a plurality of strip protrusions distributed in a grid pattern.

[0083] Furthermore, in the corresponding set of doped semiconductor layers, metal electrodes, and interface connection structures, the ratio of the contact area between the interface connection structure and the doped semiconductor layer to the contact area between the metal electrode and the doped semiconductor layer is 3% to 5%.

[0084] Furthermore, the first metal electrode 31 is made of an AlSi alloy and Cu metal composite film with a thickness of 10 μm. The second metal electrode 32 is made of a Ti / W / Cu metal composite film with a thickness of 8 μm.

[0085] In one optional embodiment, the materials of the first interface connection structure 41 and the second interface connection structure 42 are respectively composed of five elements: Si, O, N, Al, and P; wherein: the Si content is 55-65%, the N content is 35-45%, the oxygen content is 0.1-1%, the Al content is 0.1-1%, and the P content is 0-0.01%. The height of the materials of the first interface connection structure 41 and the second interface connection structure 42 is 50-200 nm, and their lateral width is 0.5-1.5 μm.

[0086] In another optional embodiment, the materials of the first interface connection structure 41 and the second interface connection structure 42 respectively include at least two elements selected from Si, O, N, and Al, wherein: the Si content is 30%~70%, the N content is 10~40%, the oxygen content is 0~30%, and the Al content is 0~5%. The height of the materials of the first interface connection structure 41 and the second interface connection structure 42 is 10~300nm, and their lateral width is 0.5~1.5um.

[0087] Example 5 This embodiment provides a method for preparing a solar cell, referring to... Figure 10 The method specifically includes: S1: A substrate 1 is provided, and multiple doped regions are divided on the back surface of the substrate 1 by spacing along the X direction. The multiple doped regions are respectively a first doped region 12 and a second doped region 13, and the first doped region 12 and the second doped region 13 are alternately spaced along the X direction.

[0088] S2: Multiple doped semiconductor layers are formed, each corresponding to a different doped region. These multiple doped semiconductor layers are divided into a first doped semiconductor layer 21 and a second doped semiconductor layer 22. The first doped semiconductor layer 21 covers the first doped region 12, while the second doped semiconductor layer 22 covers the second doped region 13. The first doped semiconductor layer 21 and the second doped semiconductor layer 22 have different polarities.

[0089] S3: A first surface passivation layer 61 is formed, which covers multiple doped semiconductor layers. Multiple metal contact regions 611 are sequentially spaced along the X-direction on the first surface passivation layer 61. Each metal contact region 611 corresponds one-to-one with a doped semiconductor layer. Within each metal contact region 611, several stripping sub-regions and several retention sub-regions are divided. The retention sub-regions are in the form of one or more of the following shapes: polygonal (e.g., triangle, rectangle, pentagon), circular, elliptical, striped, or irregular shapes.

[0090] When this preparation method is used to prepare the solar cell provided in Example 1, refer to... Figure 2 The metal contact region 611 is further divided into multiple metal contact sub-regions, and each or several of these sub-regions is further divided into several stripping sub-regions and several retention sub-regions. When this preparation method is used to prepare the solar cells provided in Examples 2 to 4, refer to... Figure 2 The metal contact area 611 is rectangular, and the two ends of the metal contact area 611 along the length direction can penetrate the first surface passivation layer 61.

[0091] S4: The first surface passivation layer 61 is subjected to a film-opening process. The first surface passivation layer 61 in the lift-off sub-region is removed by laser etching, and the first surface passivation layer 61 that was not removed in the retained sub-region forms a protrusion on the doped semiconductor layer. Specifically, the portion of the first surface passivation layer 61 located in the lift-off sub-region is etched by laser, while the portion of the first surface passivation layer 61 located in the retained sub-region naturally protrudes from the doped semiconductor layer.

[0092] In some implementations, the first surface passivation layer 61 located within the reserved sub-region may be partially peeled off to control the height and shape of the protrusion.

[0093] S5: Multiple metal electrodes are formed, and the multiple metal electrodes are correspondingly covered on multiple doped semiconductor layers. Specifically, the multiple metal electrodes are divided into a first metal electrode 31 and a second metal electrode 32, wherein the first metal electrode 31 covers the first doped semiconductor layer 21, the second metal electrode 32 covers the second doped semiconductor layer 22, and each metal electrode contacts the corresponding doped semiconductor layer through an opening on the first surface passivation layer 61.

[0094] In one embodiment, the fabrication method further includes: in step S4, laser etching is performed on the protrusions formed on the doped semiconductor layer to create a serrated structure on the surface of the protrusions. During laser etching of the protrusions formed on the doped semiconductor layer, the tooth shape of the protrusion surface is controlled by controlling the laser etching depth and the angle between the laser and the solar cell. For example, when the laser is slightly tilted towards the solar cell during etching, the protrusions on the surface become hook-shaped. The hook-shaped protrusions can penetrate into the metal electrode, making the metal electrode less likely to detach.

[0095] Example 6 This embodiment provides a method for preparing a solar cell. The only difference between this embodiment and Embodiment 5 is that the first surface passivation layer 61 in the stripper region is removed by a chemical masking process in this embodiment.

[0096] In this embodiment, the step of performing a film-opening process on the first surface passivation layer 61 specifically includes: S41: screen printing photoresist on the portion of the first surface passivation layer 61 located in the retention sub-region, and then curing the photoresist with ultraviolet light or heat to form a mask; S42: selectively etching away the portion of the first surface passivation layer 61 located in the stripping sub-region using an HF solution; S43: removing the photoresist using an alkaline solution and cleaning the battery surface.

[0097] Furthermore, the method provided in this embodiment may also include a step of laser etching the bumps formed on the doped semiconductor layer.

[0098] As described above, the solar cell fabrication methods provided in Examples 5 and 6 effectively utilize the first surface passivation layer 61 to form protrusions on the doped semiconductor layer. This creates an uneven structure on the surface of the doped semiconductor layer contacting the metal electrode, thereby improving the bonding strength between the doped semiconductor layer and the metal electrode and avoiding the technical problem of metal electrode detachment. Furthermore, a serrated structure can be fabricated on the surface of the protrusion using laser etching, allowing the protrusion to penetrate the metal electrode and significantly increasing the pull force of the protrusion on the metal electrode.

[0099] Example 7 This embodiment provides a method for preparing a solar cell. The difference between this embodiment and embodiments five and six is ​​that in this embodiment, several protrusions are formed on the surface of the metal electrode in contact with the doped semiconductor layer by screen printing or deposition.

[0100] In Examples 5 and 6, the interface connections are formed using the first surface passivation layer 61, while in this example, the interface connections are independent of the first surface passivation layer 61. In this example, the interface connections can be formed on the exposed surface of the doped semiconductor layer after the step of opening the first surface passivation layer 61. Compared to Examples 5 and 6, the preparation steps in this example are more complex and do not offer any significant advantages; therefore, this example is not considered preferred.

[0101] Performance testing Seven battery samples were selected for electrode bonding strength and electrical performance testing. Sample 1 had randomly distributed granular protrusions on its doped semiconductor layer, Sample 2 had arrayed granular protrusions on its doped semiconductor layer, Sample 3 had linear stripe protrusions on its doped semiconductor layer, Sample 4 had wavy stripe protrusions on its doped semiconductor layer, Sample 5 had linear stripe protrusions on its doped semiconductor layer, Sample 6 had grid-like stripe protrusions on its doped semiconductor layer, and Sample 7 (as a comparative example) had no protrusions on its doped semiconductor layer (i.e., no interface connection structure). All other parameters and dimensions of the battery samples were the same.

[0102] 1. Test methods for electrode bonding strength include: 1.1 Testing the adhesion between the electrode and the silicon substrate: First, fix the silicon substrate. Then, use 3M tape to stick and cover one of the electrodes of the battery sample. After that, tear the tape until the tape is completely detached from the electrode. Finally, measure and calculate the detachment ratio of the electrode. Detachment ratio = total area of ​​the detached area of ​​the electrode / total area of ​​the electrode (for ease of measurement and calculation, the area can also be replaced by the length). 1.2 Testing the welding pull force of electrodes under low temperature conditions (180~200℃): First, fix the silicon substrate. Then, use a pull gauge to hook one end of the solder strip on a certain electrode (or the middle of the solder strip). After that, lift the pull gauge upward until the electrode begins to fall off the silicon substrate. Record the pull force used when the electrode begins to fall off.

[0103] 2. The electrical performance testing methods include: using IV testing (test conditions 25℃, AM1.5G) to test the electrical performance of battery samples. IV testing is a basic electrical test used to evaluate the electrical performance (battery efficiency, open circuit voltage, fill factor, contact resistance, etc.) of a battery by applying an adjustable voltage / current excitation to the battery, simultaneously measuring the current / voltage, and plotting the IV curve.

[0104] The test results are shown in Table 1: Table 1

[0105] As shown in Table 1, compared to solar cells without protrusions, the welding pull force of the electrodes in the solar cell provided by this application is increased by at least 1.5 times, and the pull-off rate under the same pull force is reduced by at least 10 times. Therefore, the solar cell provided by this application can increase the bonding strength between the metal electrode and the doped semiconductor layer while ensuring its electrical performance, thereby preventing the metal electrode from detaching under tensile stress.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A solar cell, comprising a substrate having an electrode surface, a doped region formed on the electrode surface, a doped semiconductor layer, a surface passivation layer, and a metal electrode sequentially disposed within the doped region, the metal electrode at least partially penetrating the surface passivation layer and contacting the doped semiconductor layer, characterized in that, An interface connection structure is provided on the surface of the doped semiconductor layer that contacts the metal electrode. The interface connection structure is used to connect the doped semiconductor layer and the metal electrode. The material of the interface connection structure includes at least one of the material elements contained in the surface passivation layer.

2. The solar cell according to claim 1, characterized in that, The interface connection structure includes several protrusions.

3. The solar cell according to claim 2, characterized in that, The plurality of protrusions includes a plurality of granular protrusions and / or a plurality of strip-shaped protrusions.

4. The solar cell according to claim 3, characterized in that, The plurality of granular protrusions in the interface connection structure are randomly discrete or lattice-shaped distributed. And / or, the plurality of strip-shaped protrusions of the interface connection structure are distributed in a striped, grid-like, intersecting, or discrete manner; And / or, the surfaces of the granular protrusions and / or the strip-shaped protrusions are serrated.

5. The solar cell according to claim 1, characterized in that, The protrusion height of the interface connection structure relative to the surface of the doped semiconductor layer is 10nm~300nm, and / or, The lateral dimension of the granular protrusions is 50~3500nm; and / or, The width of the strip-shaped protrusion is 50~3500nm.

6. The solar cell according to claim 1, characterized in that, The ratio of the contact area between the interface connection structure and the doped semiconductor layer to the contact area between the metal electrode and the doped semiconductor layer is 0.1% to 5%.

7. The solar cell according to claim 1, characterized in that, The substrate is a monocrystalline silicon wafer; and / or, The material of the doped semiconductor layer includes at least one of doped polycrystalline silicon, doped polycrystalline silicon oxide, and doped polycrystalline silicon carbide; and / or, The thickness of the doped semiconductor layer is 50~500 nm; and / or, The metal electrode is made of at least one element selected from Ag, Al, Cu, Ni, Ti, W, and Sn; and / or, The thickness of the metal electrode is 3~30 μm.

8. The solar cell according to claim 1, characterized in that, An interface passivation layer is also provided in the doped region, which is placed between the electrode surface and the doped semiconductor layer. The material of the interface passivation layer includes at least one of silicon oxide, aluminum oxide, silicon oxynitride, and silicon nitride, and / or... The thickness of the interface passivation layer is 1~3nm.

9. The solar cell according to claim 1, characterized in that, The surface passivation layer is made of at least one of aluminum oxide, silicon oxide, silicon nitride, silicon oxynitride, and silicon carbide.

10. The solar cell according to claim 1, characterized in that, The electrode surface is the backlight surface of the substrate. The electrode surface has a first doped region and a second doped region arranged alternately along the X direction. The first doped region and the second doped region have opposite conductivity types. A first doped semiconductor layer and a first metal electrode are sequentially disposed in the first doped region. A second doped semiconductor layer and a second metal electrode are sequentially disposed in the second doped region. A first interface connection structure is provided on the surface of the first doped semiconductor layer that contacts the first metal electrode, and a second interface connection structure is provided on the surface of the second doped semiconductor layer that contacts the second metal electrode.

11. The solar cell according to claim 1, characterized in that, The electrode surface is the light-receiving surface and the back-light-receiving surface of the substrate. The backlight surface has a first doped region, and the light-receiving surface has a plurality of second doped regions spaced apart along the X direction. The first doped region and the second doped region have opposite conductivity types. A first doped semiconductor layer and a first metal electrode are sequentially disposed in the first doped region, and a second doped semiconductor layer and a second metal electrode are sequentially disposed in the second doped region. A first interface connection structure is provided on the surface of the first doped semiconductor layer that contacts the first metal electrode.

12. The solar cell according to claim 11, characterized in that, A second interface connection structure is provided on the surface of the second doped semiconductor layer that contacts the second metal electrode; and / or, The backlight surface is formed with a plurality of first doped regions spaced apart along the X direction.

13. A photovoltaic module, characterized in that, Includes the solar cell according to any one of claims 1 to 12.

14. A method for preparing a solar cell, characterized in that, include: Before forming a metal electrode on the substrate of a solar cell, several protrusions are formed on the surface of the doped semiconductor layer that contacts the metal electrode.

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