Solar cell, cell assembly and photovoltaic system

Abstract

The invention discloses a solar cell, a cell module and a photovoltaic system, and the solar cell comprises a substrate; the first doped layers and the second doped layers are alternately arranged on the first surface, and the first doped layers and the adjacent second doped layers are separated by isolation regions; the conduction type of the first doping layer is different from that of the substrate; the first doping layer comprises a first doping part; the two side walls of the isolation area are inclined side walls, a light trapping structure is arranged in a first partial area of the inclined side walls, and the light trapping structure comprises a plurality of zigzag structures which are arranged in a laminated mode; the first doping layer further comprises a second doping part; the solar cell further comprises an extension part which extends from the first doping layer to the isolation region. The extension part comprises a second doping part; tooth crests of the sawtooth-shaped structures on the inclined side walls close to the first doping layer make contact with the extending parts. The light utilization rate of the solar cell is effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a solar cell, a battery assembly and a photovoltaic system. Background Art

[0002] A back contact solar cell is a cell in which both the emitter and base contact electrodes are placed on the back side (non-light-receiving side) of the cell. The light-receiving side of the cell is not blocked by any metal electrode, thereby effectively increasing the effective illumination area of ​​the cell.

[0003] However, the current light utilization rate of BC solar cells is low. How to effectively increase the light utilization rate of BC solar cells is a technical problem that the industry urgently needs to solve. Summary of the invention

[0004] The present invention provides a solar cell, a battery assembly and a photovoltaic system to solve the problem of low light utilization rate of BC solar cells.

[0005] In a first aspect, the present invention provides a solar cell, wherein the solar cell comprises: A substrate, the substrate comprising a first surface and a second surface disposed opposite to each other; A first doping layer and a second doping layer are alternately arranged on the first surface, the first doping layer and the adjacent second doping layer are separated by an isolation region, the conductivity type of the first doping layer is different from the conductivity type of the second doping layer; the conductivity type of the first doping layer is different from the conductivity type of the substrate; The first doping layer includes a first doping portion, and the first doping portion is located on the first surface; The two side walls of the isolation region are inclined side walls, and a light trapping structure is disposed in a first portion of the inclined side walls, and the light trapping structure includes a plurality of sawtooth structures; The first doping layer further includes: a second doping portion; The solar cell further includes an extension portion, which extends from the first doped layer toward the isolation region; a vertical projection of the extension portion on the first surface covers a portion of a vertical projection of the inclined sidewall on the first surface; The extension portion includes a second doping portion; the tooth top of the sawtooth structure on the inclined side wall close to the first doping layer contacts the extension portion.

[0006] Optionally, the first polishing structure includes a plurality of stacked sawtooth structures.

[0007] Optionally, the tooth top of the sawtooth structure includes a first side surface and a second side surface, and an included angle between the first side surface and the second side surface is greater than or equal to 70° and less than or equal to 110°.

[0008] Optionally, there is a spacing between the tooth tops of two adjacent sawtooth structures.

[0009] Optionally, the spacing between the tooth tops of two adjacent sawtooth structures is 0.1um-3um.

[0010] Optionally, along the extension direction of the extension portion, the tooth tops of the plurality of sawtooth structures are distributed between a starting position and an ending position of the extension portion.

[0011] Optionally, along the extension direction of the extension portion, there is a spacing between a starting position of the extension portion and a tooth top of the sawtooth structure.

[0012] Optionally, the second doping portion and the first doping portion are integrally provided.

[0013] Optionally, the second doping portion and the first doping portion are arranged at intervals.

[0014] Optionally, a hole is provided at a portion where the second doping portion and the first doping portion are connected.

[0015] Optionally, the solar cell further includes a passivation layer, the passivation layer surrounds the second doped portion, and the extension portion includes the second doped portion and the passivation layer.

[0016] Optionally, a portion of the substrate close to the first surface extends to the isolation region along a direction from the first doping layer to the isolation region to form a reflective portion; The solar cell further includes a passivation layer, which surrounds the reflective portion and the second doped portion; The extension portion includes a second doped portion, a reflective portion and a passivation layer.

[0017] Optionally, the solar cell further includes a first tunneling layer located between the reflective portion and the second doped portion; The extension portion includes a second doped portion, a first tunneling layer, a reflective portion, and a passivation layer.

[0018] Optionally, the tooth top of the sawtooth structure on the inclined sidewall close to the first doping layer is in contact with the passivation layer; Alternatively, the tooth top of the sawtooth structure on the inclined sidewall close to the first doping layer is in contact with the passivation layer and the second doping portion; Alternatively, the tooth top of the sawtooth structure on the inclined sidewall close to the first doping layer is in contact with the passivation layer, the first tunneling layer, and the second doping portion; Alternatively, the tooth top of the sawtooth structure on the inclined sidewall close to the first doping layer is in contact with the passivation layer and the first tunneling layer.

[0019] Optionally, the sawtooth structure includes a plurality of protrusions with different protrusion heights in a direction from the first surface to the second surface; the protrusions in contact with the extension portion are tooth tops of the sawtooth structure; The adjacent protrusions are stacked.

[0020] Optionally, the reflective portion is located on the second partial region of the inclined side wall close to a portion where the first doped portion and the second doped portion are connected; A vertical projection of the reflective portion on the first surface is located within a vertical projection of the second doped portion on the first surface.

[0021] Optionally, an angle between a surface of the reflective portion close to the isolation region and the inclined side wall ranges from 90° to 120°.

[0022] Optionally, an angle between the inclined sidewall close to the first doping layer and a surface of the first doping portion close to the substrate is an obtuse angle.

[0023] Optionally, the isolation region is provided with an isolation groove, and the isolation groove includes a first sub-groove and a second sub-groove connected to each other; The first sub-groove extends from a surface of the first doped layer away from the substrate to the first surface; The second sub-groove extends from the first surface to the inside of the substrate; The inclined side wall is a side wall of the second sub-groove.

[0024] In a second aspect, the present invention provides a battery assembly, wherein the battery assembly includes the solar cell provided in the first aspect.

[0025] In a third aspect, the present invention provides a photovoltaic system, wherein the photovoltaic system includes the battery assembly provided in the second aspect.

[0026] According to the technical solution of the embodiment of the present invention, the two side walls of the isolation region are inclined side walls, and the first part of the first inclined side wall is provided with a light trapping structure composed of a plurality of sawtooth structures. The two side walls of the isolation region are the first surface of the substrate, that is, the light trapping structure can increase the surface area of ​​the first inclined side wall in the first surface, increase the contact area between the first surface and the light irradiated to the first surface, and make the first inclined side wall of the first surface have a higher light trapping effect. When the incident light irradiates the first inclined side wall of the isolation region, the light trapping structure can effectively increase the light trapping and reduce the reflection of the incident light, thereby improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell. According to the technical solution of the embodiment of the present invention, the current and carrier transmission efficiency of the battery are effectively improved, and finally a solar cell with high conversion efficiency is obtained. At the same time, by providing the second doping part, the reflection of the incident light can be effectively increased, so that the incident light is reflected to the light trapping structure composed of a plurality of sawtooth structures, thereby further improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell. The tooth top of the sawtooth structure on the first inclined side wall close to the first doped layer contacts the extension portion, and the sawtooth structure can support the extension portion to prevent the second doped portion from falling, thereby preventing the solar cell from having a short circuit.

[0027] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 It is a structural schematic diagram of a back contact solar cell provided by the related technology; Figure 2 is a schematic structural diagram of a solar cell provided by an embodiment of the present invention; Figure 3 is a scanning electron microscope (SEM) image of an inclined side wall of an isolation region provided by an embodiment of the present invention; Figure 4 is a schematic structural diagram of another solar cell provided by an embodiment of the present invention; Figure 5 is a top view of a first doping layer provided by an embodiment of the present invention; Figure 6 is a schematic structural diagram of another solar cell provided by an embodiment of the present invention; Figure 7 is a schematic structural diagram of another solar cell provided by an embodiment of the present invention; Figure 8 is a schematic structural diagram of another solar cell provided by an embodiment of the present invention; Fig. 9 is a schematic structural diagram of another solar cell provided by an embodiment of the present invention; Fig.10 is a schematic structural diagram of another solar cell provided by an embodiment of the present invention; Fig.11 is a schematic structural diagram of another solar cell provided by an embodiment of the present invention; Fig.12 Yes Figure 3 Enlarged view of the middle AA area; Fig.13 Yes Fig.12 Enlarged view of the middle BB region; Fig.14 It is a schematic diagram of the structure of another solar cell provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0031] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0032] Figure 1 It is a schematic diagram of the structure of a back contact solar cell provided by the related technology, such as Figure 1 As shown, the back-contact solar cell includes a first substrate 1, a third doping layer 2 and a fourth doping layer 3, the first substrate 1 includes a front side 103 and a back side 104, and the third doping layer 2 and the fourth doping layer 3 are alternately arranged on the back side 104 of the first substrate 1. An insulating isolation region 4 is provided between the third doping layer 2 and the fourth doping layer 3, and the two side walls of the insulating isolation region 4 are vertical side walls. The above morphology cannot make good use of sunlight, resulting in a low photoelectric conversion efficiency of the solar cell.

[0033] In order to solve the above problems, the technical solutions of the embodiments of the present invention are as follows: Figure 2 is a schematic structural diagram of a solar cell provided by an embodiment of the present invention, Figure 3 is a scanning electron microscope (SEM) image of a slanted side wall of an isolation region provided by an embodiment of the present invention, such as Figure 2 and Figure 3As shown, the solar cell includes: a substrate 10, the substrate 10 includes a first surface 101 and a second surface 102 arranged opposite to each other. A first doping layer 11 and a second doping layer 12 are alternately arranged on the first surface 101, and the first doping layer 11 and the adjacent second doping layer 12 are separated by an isolation region 13, and the conductivity type of the first doping layer 11 is different from the conductivity type of the second doping layer 12; the conductivity type of the first doping layer 11 is different from the conductivity type of the substrate 10. The first doping layer 11 includes a first doping portion 111, and the first doping portion 111 is located on the first surface 101. The two side walls of the isolation region 13 are inclined side walls, and the first part of the inclined side wall is provided with a light trapping structure, and the light trapping structure includes a plurality of sawtooth structures 1311. The first doping layer 11 also includes: a second doping portion 112. The solar cell also includes an extension portion 15, and the extension portion 15 extends from the first doping layer 11 to the isolation region 13; the vertical projection of the extension portion 15 on the first surface 101 covers a part of the vertical projection of the inclined side wall on the first surface 101. The extension portion 15 includes a second doping portion 112 ; the top of the sawtooth structure 1311 on the inclined sidewall close to the first doping layer 11 contacts the extension portion 15 .

[0034] Specifically, the substrate 10 includes a first surface 101 and a second surface 102 . Exemplarily, the first surface 101 may be a back surface (non-light-receiving surface), and the second surface 102 may be a front surface (light-receiving surface).

[0035] The first doping layers 11 and the second doping layers 12 are alternately arranged on the first surface 101 along a first direction X. The first doping layers 11 and the second doping layers 12 have different doping types. The first direction X is the direction from the first doping layer 11 to the isolation region 13 .

[0036] The first doping layer 11 and the substrate 10 have different doping types, the second doping layer 12 and the substrate 10 have the same doping type, and the doping concentration of the second doping layer 12 is greater than the doping concentration of the substrate 10. Exemplarily, the substrate 10 may be an N-type substrate, the first doping layer 11 may be a P-type doping layer, and the second doping layer 12 may be an N-type doping layer. Alternatively, the substrate 10 may be a P-type substrate, the first doping layer 11 may be an N-type doping layer, and the second doping layer 12 may be a P-type doping layer.

[0037] In some embodiments of the present invention, the second doping layer 12 and the substrate 10 may have different doping types, the first doping layer 11 and the substrate 10 may have the same doping type, and the doping concentration of the first doping layer 11 is greater than the doping concentration of the substrate 10. Exemplarily, the substrate 10 may be an N-type substrate, the first doping layer 11 may be an N-type doping layer, and the second doping layer 12 may be a P-type doping layer. Alternatively, the substrate 10 may be a P-type substrate, the first doping layer 11 may be a P-type doping layer, and the second doping layer 12 may be an N-type doping layer.

[0038] The first doping layer 11 includes a first doping portion 111 and a second doping portion 112. The second doping portion 112 extends from the first doping portion 111 to the isolation region 13. The extension portion 15 may include the second doping portion 112. In some embodiments of the present invention, the extension portion 15 may also include other film layers ( Figure 2 ). The isolation region 13 may extend to the inside of the substrate 10, and the isolation region 13 includes a first inclined sidewall 131 and a second inclined sidewall 132. A light trapping structure consisting of a plurality of sawtooth structures 1311 is disposed in a first portion of the first inclined sidewall 131, and the tooth tops of the sawtooth structures 1311 on the first inclined sidewall 131 close to the first doping layer 11 are in contact with the extension 15, and the sawtooth structures 1311 may support the extension 15. In some embodiments of the present invention, a light trapping structure consisting of a plurality of sawtooth structures 1311 may also be disposed in a first portion of the second inclined sidewall 132.

[0039] Figure 2 The black straight line with a one-way arrow in the middle represents the light path irradiated to the side of the extension portion 15 including the second doped portion 112 close to the first inclined sidewall 131. When the incident light irradiates the side of the extension portion 15 including the second doped portion 112 close to the first inclined sidewall 131, according to the light path, the extension portion 15 including the second doped portion 112 can be called a "brim structure", which can directly reflect the light to the light trapping structure of the first inclined sidewall 131.

[0040] According to the technical solution of the embodiment of the present invention, the two side walls of the isolation region 13 are inclined side walls, and the first part of the first inclined side wall 131 is provided with a light trapping structure composed of a plurality of sawtooth structures 1311. The two side walls of the isolation region 13 are the first surface 101 of the substrate 10, that is, the light trapping structure can increase the surface area of ​​the first inclined side wall 131 in the first surface 101, increase the contact area between the first surface 101 and the light irradiated to the first surface 101, and make the first inclined side wall 131 of the first surface 101 have a higher light trapping effect. When the incident light irradiates the first inclined side wall 131 of the isolation region 13, the light trapping structure can effectively increase the light trapping and reduce the reflection of the incident light, thereby improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell. According to the technical solution of the embodiment of the present invention, the current and carrier transmission efficiency of the battery are effectively improved, and finally a solar cell with high conversion efficiency is obtained. At the same time, by setting the second doped portion 112, the reflection of the incident light can be effectively increased, so that the incident light is reflected to the light trapping structure composed of multiple sawtooth structures 1311, thereby further improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell. And the top of the sawtooth structure 1311 on the first inclined side wall 131 close to the first doped layer 11 is in contact with the extension part 15, and the sawtooth structure 1311 can support the extension part 15 to prevent the second doped portion 112 from falling, thereby preventing the solar cell from having a short circuit problem.

[0041] Optionally, based on the above embodiments, continue to refer to Figure 2 and Figure 3 The light trapping structure includes a plurality of stacked sawtooth structures 1311 .

[0042] It should be noted that the stacking direction of the zigzag structures 1311 arranged in multiple layers is not limited to one direction. For example, the stacking direction may be the S1 direction, the S2 direction, or the S3 direction. Two adjacent zigzag structures 1311 overlap in a certain direction, which may be referred to as the stacking direction. The S1 direction refers to the direction from the second surface 102 to the first surface 101, the S2 direction refers to the direction parallel to the surface where the first inclined sidewall 131 is located, and the S3 direction refers to the direction from the first inclined sidewall 131 to the isolation region 13.

[0043] Specifically, the first part of the first inclined sidewall 131 may be provided with a light trapping structure composed of a plurality of stacked sawtooth structures 1311. The light trapping structure can increase the surface area of ​​the first inclined sidewall 131 in the first surface 101, increase the contact area between the first surface 101 and the light irradiated to the first surface 101, and make the first inclined sidewall 131 of the first surface 101 have a higher light trapping effect. When the incident light irradiates the first inclined sidewall 131 of the isolation region 13, the light trapping structure can effectively increase the light trapping and reduce the reflection of the incident light, thereby improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell. The tops of the plurality of stacked sawtooth structures 1311 on the first inclined sidewall 131 are in contact with the extension 15, and the sawtooth structure 1311 can support the extension 15 to prevent the second doped portion 112 from falling, thereby preventing the solar cell from having a short circuit problem.

[0044] Optionally, based on the above embodiments, continue to refer to Figure 2 and Figure 3 The tooth top of the sawtooth structure 1311 includes a first side surface F1 and a second side surface F2, and an included angle θ between the first side surface F1 and the second side surface F2 is greater than or equal to 70° and less than or equal to 110°.

[0045] Specifically, the tooth top of the sawtooth structure 1311 may include a first side surface F1 and a second side surface F2, and the angle θ between the first side surface F1 and the second side surface F2 may be set to 70°-110°. A plurality of sawtooth structures 1311 constitute a light-trapping structure, which can increase the surface area of ​​the first inclined side wall 131 in the first surface 101 of the substrate 10, increase the contact area between the first surface 101 and the light irradiated to the first surface 101, and make the first surface 101 have a higher light-trapping effect. When the incident light irradiates the first inclined side wall 131 of the isolation region 13, the light-trapping structure can effectively increase the light trapping and reduce the reflection of the incident light, thereby improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell.

[0046] If the angle θ between the first side surface F1 and the second side surface F2 is too large, the area of ​​the second doped portion 112 that plays a reflective role will be too small, resulting in poor effect of the second doped portion 112 in reflecting light to the first inclined sidewall 131. If the angle θ between the first side surface F1 and the second side surface F2 is too small, the contact area between the tooth top of the sawtooth structure 1311 and the extension portion 15 is too small, resulting in poor support effect of the sawtooth structure 1311 on the extension portion 15.

[0047] Optionally, based on the above embodiments, continue to refer to Figure 2 and Figure 3The tooth top of the sawtooth structure 1311 includes a first side surface F1 and a second side surface F2, the first side surface F1 may extend to the bottom of the isolation region 13, the second side surface F2 may extend to the middle of the inclined side wall, and the middle of the inclined side wall is located between the extension 15 and the bottom of the isolation region 13. Alternatively, the first side surface F1 may extend to the bottom of the isolation region 13, and the second side surface F2 may extend to the bottom of the isolation region 13. Alternatively, the first side surface F1 may extend to the middle of the inclined side wall, the second side surface F2 may extend to the middle of the inclined side wall, and the middle of the inclined side wall is located between the extension 15 and the bottom of the isolation region 13.

[0048] Specifically, one side of the tooth top of the sawtooth structure 1311 can extend to the bottom of the isolation region 13 or the middle of the first inclined sidewall 131, and the other side can also extend to the bottom of the isolation region 13 or the middle of the first inclined sidewall 131. The first inclined sidewall 131 and / or the bottom of the isolation region 13 support the sawtooth structure 1311, so that multiple sawtooth structures 1311 form a light-trapping structure. The light-trapping structure can increase the surface area of ​​the first inclined sidewall 131 in the first surface 101 of the substrate 10, increase the contact area between the first surface 101 and the light irradiated to the first surface 101, and make the first surface 101 have a higher light-trapping effect. When the incident light irradiates the first inclined sidewall 131 of the isolation region 13, the light-trapping structure can effectively increase the light trapping and reduce the reflection of the incident light, thereby improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell.

[0049] Optionally, based on the above embodiments, continue to refer to Figure 2 and Figure 3 There is a spacing between the tooth tops of two adjacent sawtooth structures 1311.

[0050] Specifically, there is a spacing D1 between the tooth tops of two adjacent sawtooth structures 1311, and the tooth tops of multiple sawtooth structures 1311 are in contact with different areas of the extension portion 15. The sawtooth structures 1311 can support the extension portion 15 to prevent the second doped portion 112 from falling, thereby preventing the solar cell from having a short circuit problem. Multiple sawtooth structures 1311 constitute a light trapping structure, which can increase the surface area of ​​the first inclined side wall 131 in the first surface 101 of the substrate 10, increase the contact area between the first surface 101 and the light irradiated to the first surface 101, and make the first surface 101 have a higher light trapping effect. When the incident light irradiates the first inclined side wall 131 of the isolation region 13, the light trapping structure can effectively increase the light trapping and reduce the reflection of the incident light, thereby improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell.

[0051] Optionally, based on the above embodiments, continue to refer to Figure 2 and Figure 3 The spacing between the tooth tops of two adjacent sawtooth structures 1311 is 0.1um-3um.

[0052] Specifically, there is a spacing D1 between the tooth tops of two adjacent sawtooth structures 1311, and the spacing D1 can be set to 0.1um-3um. The tooth tops of multiple sawtooth structures 1311 are in contact with different areas of the extension part 15. The sawtooth structures 1311 can support the extension part 15 to prevent the second doped part 112 from falling, thereby preventing the solar cell from having a short circuit problem. There is a spacing D1 between two adjacent sawtooth structures 1311, and the spacing D1 is 0.1um-3um, which can ensure that most areas of the extension part 15 are in contact with the tooth tops of multiple sawtooth structures 1311, and the sawtooth structures 1311 can support the extension part 15 well.

[0053] The distance D1 between the tooth tops of two adjacent sawtooth structures 1311 cannot be set too large. If the distance D1 between two adjacent stacked sawtooth structures 1311 is set too large, the extension portion 15 cannot be well supported.

[0054] Optionally, based on the above embodiments, continue to refer to Figure 2 and Figure 3 , along the extension direction of the extension portion 15, the tooth tops of the plurality of sawtooth structures 1311 are distributed between the starting position A1 and the ending position A2 of the extension portion 15. Preferably, based on the above embodiments, continue to refer to Figure 2 and Figure 3 Along the extension direction of the extension portion 15 , there is a gap between the starting position A1 of the extension portion 15 and the tooth top of the sawtooth structure 1311 .

[0055] Specifically, the intersection of the first inclined sidewall 131 and the first surface 101 may be referred to as the starting position A1 of the extension portion 15 . The edge of the extension portion 15 close to the isolation region 13 may be referred to as the ending position A2 of the extension portion 15 .

[0056] The above scheme ensures that the tooth tops of the multiple sawtooth structures 1311 do not contact the intersection of the first inclined side wall 131 and the first surface 101, and the tooth tops of the multiple sawtooth structures 1311 are completely used to support the extension portion 15, so that the tooth tops of the multiple sawtooth structures 1311 have a good supporting effect on the edge of the extension portion 15 away from the first doped portion 111, which can prevent the second doped portion 112 from falling off, thereby preventing the solar cell from having a short circuit problem.

[0057] The positional relationship between the second doping portion 112 and the first doping portion 111 includes the following three types: Optionally, based on the above embodiments, continue to refer to Figure 2 The second doping portion 112 and the first doping portion 111 are integrally arranged.

[0058] Optionally, based on the above embodiments, Figure 4 is a schematic diagram of the structure of another solar cell provided by an embodiment of the present invention, such as Figure 4 As shown, the second doping portion 112 and the first doping portion 111 are arranged at intervals.

[0059] Optionally, based on the above embodiments, Figure 5 is a top view of a first doping layer provided by an embodiment of the present invention, such as Figure 5 As shown, a hole is provided at a portion where the second doping portion 112 and the first doping portion 111 are connected.

[0060] Specifically, the first doping part 111 and the second doping part 112 can be connected, and the tooth tops of the multiple stacked sawtooth structures 1311 can support the extension part 15 including the second doping part 112, thereby preventing the second doping part 112 from being disconnected from the first doping part 111, preventing the second doping part 112 from falling, and further preventing the solar cell from having a short circuit. Alternatively, even if the first doping part 111 and the second doping part 112 are not connected, the existence of the tooth tops of the multiple stacked sawtooth structures 1311 can support the extension part 15 including the second doping part 112, thereby preventing the second doping part 112 from falling, and further preventing the solar cell from having a short circuit.

[0061] Optionally, based on the above embodiments, Figure 6 is a schematic diagram of the structure of another solar cell provided by an embodiment of the present invention, such as Figure 6 As shown, the solar cell further includes a passivation layer 14 , the passivation layer 14 surrounds the second doped portion 112 , and the extension portion 15 includes the second doped portion 112 and the passivation layer 14 .

[0062] Specifically, the solar cell may further include a passivation layer 14, which is used to protect the substrate 10, the first doping layer 11 and the second doping layer 12 to prevent the external environment from affecting the performance of the solar cell. Optionally, the passivation layer 14 includes a film layer of aluminum oxide and / or silicon nitride. The extension portion 15 may include a second doping portion 112 and a passivation layer 14, and the top of the sawtooth structure 1311 of the first inclined sidewall 131 may be in contact with the second doping portion 112 and the passivation layer 14. In some embodiments of the present invention, the passivation layer 14 may also cover the entire surface of the second doping portion 112 close to the first surface 101, and at this time, the top of the sawtooth structure 1311 may only be in contact with the passivation layer 14. The sawtooth structure 1311 of the first inclined sidewall 131 may support the extension portion 15.

[0063] The second doped portion 112 and the passivation layer 14 can be collectively referred to as a "brim structure", which can directly reflect light to the light trapping structure of the first inclined sidewall 131. The reflection of the incident light can be effectively increased, and the incident light is reflected to the light trapping structure formed by the multiple sawtooth structures 1311, thereby further improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell.

[0064] Optionally, based on the above embodiments, Figure 7 is a schematic diagram of the structure of another solar cell provided by an embodiment of the present invention, such as Figure 7 As shown, the portion of the substrate 10 close to the first surface 101 extends to the isolation region 13 along the direction from the first doping layer 11 to the isolation region 13 to form a reflective portion 105. The solar cell further includes a passivation layer 14, which surrounds the reflective portion 105 and the second doping portion 112. The extension portion 15 includes the second doping portion 112, the reflective portion 105 and the passivation layer 14.

[0065] Specifically, the reflective portion 105 is located at the portion of the first inclined sidewall 131 close to the connection between the first doped portion 111 and the second doped portion 112. The passivation layer 14, the second doped portion 112 and the reflective portion 105 can be collectively referred to as a "brim structure", which can directly reflect light to the light trapping structure of the first inclined sidewall 131. The reflection of the incident light can be effectively increased, and the incident light is reflected to the light trapping structure composed of multiple sawtooth structures 1311, thereby further improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell.

[0066] The tooth tops of the sawtooth structure 1311 of the first inclined sidewall 131 are in contact with the passivation layer 14 and the second doped portion 112, and the sawtooth structure 1311 can support the extension portion 15. In some embodiments of the present invention, the passivation layer 14 can cover a side of the second doped portion 112 close to the first inclined sidewall 131, and the tooth tops of the sawtooth structure 1311 are in contact with the passivation layer 14, and the sawtooth structure 1311 can support the extension portion 15.

[0067] Further, the tooth tops of the sawtooth structure 1311 of the first inclined sidewall 131 may be distributed between the terminating positions of the reflecting portion 105 and the extending portion 15 .

[0068] Optionally, based on the above embodiments, Figure 8 is a schematic diagram of the structure of another solar cell provided by an embodiment of the present invention, such as Figure 8 As shown, the solar cell further includes a first tunneling layer 16 located between the reflective portion 105 and the second doped portion 112. The extension portion 15 includes the second doped portion 112, the first tunneling layer 16, the reflective portion 105 and the passivation layer 14.

[0069] Specifically, the solar cell may further include a first tunneling layer 16 located on the side of the first doped layer 11 close to the first surface 101. The first tunneling layer 16 may be a combination of one or more of a tunneling oxide layer (e.g., a tunneling silicon oxide layer), an intrinsic silicon carbide layer, and an intrinsic amorphous silicon layer, and is not specifically limited here.

[0070] The second doped portion 112, the first tunneling layer 16, the reflective portion 105 and the passivation layer 14 together constitute the extension portion 15, the tooth tops of the sawtooth structure 1311 may contact the passivation layer 14 and the first tunneling layer 16, and the sawtooth structure 1311 may support the extension portion 15. In some embodiments of the present invention, the passivation layer 14 may cover a surface of the first tunneling layer 16 close to the first inclined sidewall 131, at which time the tooth tops of the sawtooth structure 1311 contact the passivation layer 14, and the sawtooth structure 1311 may support the extension portion 15.

[0071] The second doped portion 112, the first tunneling layer 16, the reflective portion 105 and the passivation layer 14 can be collectively referred to as a "brim structure", which can directly reflect light to the light trapping structure of the first inclined sidewall 131. The reflection of the incident light can be effectively increased, and the incident light is reflected to the light trapping structure composed of the multiple stacked sawtooth structures 1311, thereby further improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell.

[0072] Optionally, based on the above embodiments, Fig. 9is a schematic diagram of the structure of another solar cell provided by an embodiment of the present invention, Fig.10 is a schematic diagram of the structure of another solar cell provided by an embodiment of the present invention, such as Fig. 9 As shown in FIG. 1 , the tooth top of the sawtooth structure 1311 on the inclined sidewall close to the first doping layer 11 is in contact with the passivation layer 14. Figure 6 As shown, the tooth tops of the sawtooth structure 1311 on the inclined sidewall close to the first doping layer 11 are in contact with the passivation layer 14 and the second doping portion 112. Fig.10 As shown, the tooth tops of the sawtooth structure 1311 on the inclined sidewall close to the first doping layer 11 are in contact with the passivation layer 14, the first tunneling layer 16, and the second doping portion 112. Figure 8 As shown, the tooth tops of the sawtooth structure 1311 on the inclined sidewall close to the first doping layer 11 are in contact with the passivation layer 14 and the first tunneling layer 16 .

[0073] Specifically, Fig. 9 As shown, the solar cell may include a passivation layer 14, a reflective portion 105, a first tunneling layer 16 and an extension portion 15 consisting of a second doped portion 112, and the passivation layer 14 covers a side of the first tunneling layer 16 close to the first inclined side wall 131, and at this time, the tooth tops of the sawtooth structure 1311 are in contact with the passivation layer 14.

[0074] like Figure 6 As shown, the solar cell may include an extension portion 15 formed by a passivation layer 14 and a second doping portion 112, and the passivation layer 14 only covers a partial area of ​​a side of the second doping portion 112 close to the first inclined sidewall 131, and at this time, the tooth top of the sawtooth structure 1311 is in contact with the passivation layer 14 and the second doping portion 112. The passivation layer 14 and the second doping portion 112 can be collectively referred to as a "brim structure", and the passivation layer 14 and the second doping portion 112 can both directly reflect light to the light trapping structure of the first inclined sidewall 131. The reflection of the incident light can be effectively increased, and the incident light is reflected to the light trapping structure formed by the multiple stacked sawtooth structures 1311, thereby further improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell.

[0075] It should be noted that the solar cell may include a passivation layer 14, a second doped portion 112 and an extension portion 15 consisting of a first tunneling layer, the first tunneling layer is located on a side of the first doped layer 11 close to the first surface 101, and the first tunneling layer only covers a partial area of ​​the second doped portion 112 close to the first inclined side wall 131, and other areas of the second doped portion 112 not covered by the first tunneling layer may be covered by the passivation layer 14, and the tooth tops of the sawtooth structure 1311 may pass through the passivation layer 14 to contact the second doped portion 112.

[0076] like Fig.10 As shown, the solar cell may include an extension portion 15 composed of a passivation layer 14, a first tunneling layer 16, a second doping portion 112 and a reflective portion 105, and the passivation layer 14 and the first tunneling layer 16 only cover a partial area of ​​a side of the second doping portion 112 close to the first inclined sidewall 131, and at this time, the tooth top of the sawtooth structure 1311 is in contact with the passivation layer 14, the first tunneling layer 16 and the second doping portion 112. The passivation layer 14, the first tunneling layer 16, the second doping portion 112 and the reflective portion 105 can be collectively referred to as a "cap brim structure", and the passivation layer 14 and the second doping portion 112 can both directly reflect light to the light trapping structure of the first inclined sidewall 131. The reflection of the incident light can be effectively increased, and the incident light is reflected to the light trapping structure composed of a plurality of stacked sawtooth structures 1311, thereby further improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell.

[0077] like Figure 8 As shown, the solar cell may include a passivation layer 14, a first tunneling layer 16, an extension portion 15 composed of a second doping portion 112 and a reflective portion 105, and the first tunneling layer 16 is arranged on a side of the second doping portion 112 close to the first inclined sidewall 131, and the passivation layer 14 only covers a partial area of ​​a side of the first tunneling layer 16 close to the first inclined sidewall 131, and at this time, the tooth top of the sawtooth structure 1311 contacts the passivation layer 14 and the first tunneling layer 16. The passivation layer 14, the first tunneling layer 16, the second doping portion 112 and the reflective portion 105 can be collectively referred to as a "cap brim structure", and the passivation layer 14 and the first tunneling layer 16 can both directly reflect light to the light trapping structure of the first inclined sidewall 131. The reflection of the incident light can be effectively increased, and the incident light is reflected to the light trapping structure composed of a plurality of stacked sawtooth structures 1311, thereby further improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell.

[0078] Optionally, based on the above embodiments, continue to refer to Figure 2-Figure 10 The sawtooth structure 1311 includes a plurality of protrusions with different protrusion heights in the second direction Y, the second direction Y being the direction from the first surface 101 to the second surface 102; the protrusions contacting the extension portion 15 are the tooth tops of the sawtooth structure 1311. Adjacent protrusions are stacked.

[0079] Specifically, the sawtooth structure 1311 includes a plurality of protrusions with different protrusion heights in the second direction Y, and the protrusions in contact with the extension portion 15 are the tooth tops of the sawtooth structure 1311 , and the protrusions can support the extension portion 15 .

[0080] Optionally, based on the above embodiments, Fig.11is a schematic diagram of the structure of another solar cell provided by an embodiment of the present invention, Fig.12 Yes Figure 3 A magnified image of the AA area in the middle. Fig.13 Yes Fig.12 Enlarged view of the middle BB area, Fig.11 The schematic diagram of the solar cell structure shown in FIG. 1 does not show the first light-emitting structure of the first inclined side wall 131 due to the problem of the cross-sectional angle. Figure 3 , Figure 11-13 As shown, the reflective portion 105 is located on the second partial area of ​​the inclined side wall near the portion where the first doped portion 111 and the second doped portion 112 are connected; the vertical projection of the reflective portion 105 on the first surface 101 is located within the vertical projection of the second doped portion 112 on the first surface 101 .

[0081] Specifically, the reflective portion 105 may be disposed at a portion of the first inclined sidewall 131 close to the connection between the first doping portion 111 and the second doping portion 112. The reflective portion 105 may be disposed at a second portion of the first inclined sidewall 131, and Figure 2-Figure 10 The light trapping structure composed of the plurality of sawtooth structures 1311 shown may be disposed in a first partial region of the first inclined sidewall 131 , and the first partial region and the second partial region may be different regions.

[0082] Fig.11 and Fig.13 The black straight line with an arrow in the middle represents the light path that is irradiated to the extension portion 15 including the second doping portion 112 and is reflected to the first inclined side wall 131 via the reflection portion 105, or directly reflects the incident light to the interior of the solar cell. The extension portion 15 including the second doping portion 112 can be called a "brim structure", which can allow the light to enter the interior of the solar cell through the reflection portion 105, and the reflection portion 105 reflects the light to the first inclined side wall 131, thereby preventing the light from entering the gap between the connection between the second doping portion 112 and the first doping portion 111 and the first inclined side wall 131, and preventing the light from entering the interior of the solar cell. It should be noted that the light entering the gap between the connection between the second doping portion 112 and the first doping portion 111 and the first inclined side wall 131 is equivalent to the light propagating parallel to the first surface 101, and thus cannot enter the interior of the solar cell.

[0083] In summary, the side of the reflective portion 105 close to the isolation region 13 can reflect part of the incident light to the inside of the solar cell, thereby improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell.

[0084] Optionally, based on the above embodiments, continue to refer to Figure 11-13The angle α between a surface of the reflecting portion 105 close to the isolation region 13 and the inclined side wall is in the range of 90°-120°.

[0085] Specifically, when the contact area between the reflecting portion 105 and the extending portion 15 remains unchanged, if the angle α between the side of the reflecting portion 105 close to the isolation region 13 and the first inclined side wall 131 is too small, the volume of the reflecting portion 105 located on the first inclined side wall 131 will be too small, and the incident light irradiated to the reflecting portion 105 will not be effectively reflected to the interior of the solar cell, thereby failing to effectively improve the absorption of light by the solar cell, improve the utilization rate of light by the solar cell, and increase the current density of the solar cell.

[0086] When the contact area between the reflecting portion 105 and the extending portion 15 remains unchanged, if the angle α between the side of the reflecting portion 105 close to the isolation region 13 and the first inclined side wall 131 is too large, the volume of the reflecting portion 105 located on the first inclined side wall 131 will be too large, and the area of ​​the first inclined side wall 131 occupied will be too large, which will correspondingly reduce the area of ​​the first inclined side wall 131 that can be contacted by the sawtooth structure 1311, which is not conducive to the light trapping structure formed by the sawtooth structure 1311 to effectively increase the surface area of ​​the first inclined side wall 131.

[0087] Optionally, based on the above embodiments, continue to refer to Figure 2 , Figure 4-Figure 11 The angle between the inclined side wall close to the first doping layer 11 and the surface of the first doping portion 111 close to the substrate 10 is an obtuse angle.

[0088] Specifically, the angle between the first inclined sidewall 131 close to the first doping layer 11 and the side of the first doping portion 111 close to the substrate 10 is an obtuse angle, and the first inclined sidewall 131 close to the first doping layer 11 protrudes toward the isolation region 13. The first inclined sidewall 131 close to the first doping layer 11 is provided with a light trapping structure composed of a plurality of sawtooth structures 1311, and the light trapping structure can increase the surface area of ​​the first surface 101 of the substrate 10, increase the contact area between the first surface 101 and the light irradiated to the first surface 101, and make the first surface 101 have a higher light trapping effect. When the incident light irradiates the first inclined sidewall 131 of the isolation region 13, the light trapping structure can effectively increase the light trapping and reduce the reflection of the incident light, thereby improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell.

[0089] Optionally, based on the above embodiments, continue to refer to Figure 2 and Figure 4The isolation region 13 is provided with an isolation groove, and the isolation groove includes a first sub-groove 134 and a second sub-groove 135 connected to each other. The first sub-groove 134 extends from the surface of the first doping layer 11 away from the substrate 10 to the first surface 101. The second sub-groove 135 extends from the first surface 101 to the inside of the substrate 10. The inclined sidewall is the sidewall of the second sub-groove 135.

[0090] Specifically, the sidewall of the second sub-groove 135 includes a first inclined sidewall 131 and a second inclined sidewall 132. The first partial area of ​​the first inclined sidewall 131 is provided with a light trapping structure composed of a plurality of sawtooth structures 1311. The light trapping structure can increase the surface area of ​​the first surface 101 of the substrate 10, increase the contact area between the first surface 101 and the light irradiated to the first surface 101, and make the first surface 101 have a higher light trapping effect. When the incident light irradiates the first inclined sidewall 131 of the isolation region 13, the light trapping structure can effectively increase the light trapping and reduce the reflection of the incident light, thereby improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell.

[0091] Optionally, based on the above embodiments, Fig.14 is a schematic diagram of the structure of another solar cell provided by an embodiment of the present invention, such as Fig.14 As shown, the second doping layer 12 includes a third doping portion 121, and the third doping portion 121 is located on the first surface 101; a first part of the second inclined sidewall 132 of the isolation region 13 is provided with a light trapping structure, and the light trapping structure includes a plurality of stacked sawtooth structures 1311. The second doping layer 12 also includes: a fourth doping portion 122; the solar cell also includes an extension portion 15 close to the second inclined sidewall 132, and the extension portion 15 extends along the second doping layer 12 toward the isolation region 13; the vertical projection of the extension portion 15 close to the second inclined sidewall 132 on the first surface 101 covers a part of the vertical projection of the second inclined sidewall 132 on the first surface 101. The extension portion 15 close to the second inclined sidewall 132 includes the fourth doping portion 122; the tooth top of the sawtooth structure 1311 on the second inclined sidewall 132 close to the second doping layer 12 contacts the extension portion 15 close to the second inclined sidewall 132.

[0092] The extension portion 15 including the fourth doped portion 122 may be referred to as a “brim structure”, which may directly reflect light to the light trapping structure of the second inclined sidewall 132 .

[0093] According to the technical solution of the embodiment of the present invention, a light-trapping structure composed of a plurality of stacked sawtooth structures 1311 is arranged in the first part of the second inclined side wall 132. The second inclined side wall 132 of the isolation region 13 is the first surface 101 of the substrate 10, that is, the light-trapping structure can increase the surface area of ​​the second inclined side wall 132 in the first surface 101, increase the contact area between the first surface 101 and the light irradiated to the first surface 101, and make the second inclined side wall 132 of the first surface 101 have a higher light-trapping effect. When the incident light irradiates the second inclined side wall 132 of the isolation region 13, the light-trapping structure can effectively increase the light trapping and reduce the reflection of the incident light, thereby improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell. According to the technical solution of the embodiment of the present invention, the current and carrier transmission efficiency of the battery are effectively improved, and a solar cell with high conversion efficiency is finally obtained. At the same time, by setting the fourth doped portion 122, the reflection of the incident light can be effectively increased, so that the incident light is reflected to the light trapping structure formed by the multiple stacked sawtooth structures 1311, thereby further improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell. The top of the sawtooth structure 1311 on the second inclined side wall 132 close to the second doped layer 12 is in contact with the extension 15 close to the second inclined side wall 132. The sawtooth structure 1311 can support the extension 15 close to the second inclined side wall 132, preventing the fourth doped portion 122 from falling, thereby preventing the solar cell from having a short circuit problem.

[0094] Optionally, based on the above embodiments, continue to refer to Fig.14 The tooth top of the sawtooth structure 1311 of the second inclined side wall 132 includes a third side surface F3 and a fourth side surface F4, and an angle β between the third side surface F3 and the fourth side surface F4 is greater than or equal to 70° and less than or equal to 110°.

[0095] If the angle β between the third side surface F3 and the fourth side surface F4 of the tooth top of the sawtooth structure 1311 of the second inclined sidewall 132 is too large, the area of ​​the fourth doped portion 122 that plays a reflective role will be too small, resulting in poor effect of the fourth doped portion 122 in reflecting light to the second inclined sidewall 132. If the angle β between the third side surface F3 and the fourth side surface F4 of the tooth top of the sawtooth structure 1311 of the second inclined sidewall 132 is too small, the contact area between the tooth top of the sawtooth structure 1311 of the second inclined sidewall 132 and the extension portion 15 close to the second inclined sidewall 132 is too small, resulting in poor support effect of the sawtooth structure 1311 of the second inclined sidewall 132 on the extension portion 15 close to the second inclined sidewall 132.

[0096] Optionally, based on the above embodiments, continue to refer to Fig.14 , the tooth top of the sawtooth structure 1311 of the second inclined sidewall 132 includes a third side surface F3 and a fourth side surface F4, the third side surface F3 extends to the bottom of the isolation region 13, the fourth side surface F4 extends to the middle of the second inclined sidewall 132, and the middle of the second inclined sidewall 132 is located between the extension portion 15 close to the second inclined sidewall 132 and the bottom of the isolation region 13. Alternatively, the third side surface F3 may extend to the bottom of the isolation region 13, and the fourth side surface F4 may also extend to the bottom of the isolation region 13. Alternatively, the third side surface F3 may extend to the middle of the second inclined sidewall 132, the fourth side surface F4 may extend to the middle of the second inclined sidewall 132, and the middle of the second inclined sidewall 132 is located between the extension portion 15 and the bottom of the isolation region 13.

[0097] Specifically, one side of the tooth top of the sawtooth structure 1311 of the second inclined sidewall 132 can extend to the bottom of the isolation region 13 or the middle of the second inclined sidewall 132, and the other side can also extend to the bottom of the isolation region 13 or the middle of the second inclined sidewall 132. The second inclined sidewall 132 and / or the bottom of the isolation region 13 support the sawtooth structure 1311 of the second inclined sidewall 132, so as to realize that the multiple sawtooth structures 1311 of the second inclined sidewall 132 constitute a light trapping structure.

[0098] Optionally, based on the above embodiments, continue to refer to Fig.14 There is a spacing between the tooth tops of two adjacent sawtooth structures 1311 of the second inclined side wall 132 .

[0099] Specifically, there is a spacing between the tooth tops of two adjacent sawtooth structures 1311 of the second inclined sidewall 132, and the tooth tops of the multiple sawtooth structures 1311 of the second inclined sidewall 132 are in contact with different areas of the extension portion 15 close to the second inclined sidewall 132. The sawtooth structure 1311 of the second inclined sidewall 132 can support the extension portion 15 close to the second inclined sidewall 132, thereby preventing the fourth doped portion 122 from falling, thereby preventing the solar cell from having a short circuit problem. Optionally, based on the above embodiments, continue to refer to Fig.14 The spacing between the tooth tops of two adjacent stacked sawtooth structures 1311 of the second inclined side wall 132 is 0.1um-3um.

[0100] Specifically, there is a spacing between the tooth tops of two adjacent sawtooth structures 1311 of the second inclined sidewall 132, and the spacing can be set to 0.1um-3um. The tooth tops of the multiple sawtooth structures 1311 of the second inclined sidewall 132 are in contact with different areas of the extension 15 close to the second inclined sidewall 132. The sawtooth structures 1311 of the second inclined sidewall 132 can support the extension 15 close to the second inclined sidewall 132, prevent the fourth doped part 122 from falling, and further prevent the solar cell from having a short circuit problem. There is a spacing between the two adjacent sawtooth structures 1311 of the second inclined sidewall 132, and the spacing is 0.1um-3um, which can ensure that most areas of the extension 15 close to the second inclined sidewall 132 are in contact with the tooth tops of the multiple sawtooth structures 1311 of the second inclined sidewall 132, and the sawtooth structures 1311 of the second inclined sidewall 132 can well support the extension 15 close to the second inclined sidewall 132.

[0101] The spacing between the tooth tops of the sawtooth structures 1311 of two adjacent stacked second inclined side walls 132 cannot be set too large. If the spacing between the sawtooth structures 1311 of two adjacent stacked second inclined side walls 132 is set too large, it will make it impossible to provide good support for the extension part 15 close to the second inclined side wall 132.

[0102] Optionally, based on the above embodiments, continue to refer to Fig.14 , along the extension direction of the extension portion 15 close to the second inclined side wall 132, the tooth tops of the plurality of stacked sawtooth structures 1311 of the second inclined side wall 132 are distributed between the starting position B1 and the ending position B2 of the extension portion 15 close to the second inclined side wall 132. Preferably, based on the above embodiments, continue to refer to Fig.14 Along the extension direction of the extension portion 15 close to the second inclined side wall 132 , there is a gap between the starting position B1 of the extension portion 15 close to the second inclined side wall 132 and the tooth top of the sawtooth structure 1311 of the second inclined side wall 132 .

[0103] Specifically, the intersection of the second inclined sidewall 132 and the first surface 101 can be referred to as the starting position B1 of the extension portion 15 close to the second inclined sidewall 132. The edge of the extension portion 15 close to the second inclined sidewall 132 close to the isolation region 13 can be referred to as the ending position B2 of the extension portion 15 close to the second inclined sidewall 132.

[0104] The above scheme ensures that the tooth tops of the sawtooth structures 1311 of the multiple stacked second inclined side walls 132 do not contact the intersection of the second inclined side wall 132 and the first surface 101, and the tooth tops of the sawtooth structures 1311 of the multiple stacked second inclined side walls 132 are completely used to support the extension portion 15 close to the second inclined side wall 132, so that the tooth tops of the multiple stacked sawtooth structures 1311 have a good supporting effect on the edge of the extension portion 15 close to the second inclined side wall 132 away from the third doped portion 121, which can prevent the fourth doped portion 122 from falling off, thereby preventing the short circuit problem of the solar cell.

[0105] The positional relationship between the fourth doping portion 122 and the third doping portion 121 includes the following three types: Optionally, based on the above embodiments, continue to refer to Fig.14 , the fourth doping part 122 and the third doping part 121 are integrally arranged. Optionally, on the basis of the above embodiments, the fourth doping part 122 and the third doping part 121 are arranged at intervals. Optionally, on the basis of the above embodiments, a hole is arranged at a portion where the fourth doping part 122 and the third doping part 121 are connected.

[0106] Specifically, the fourth doping part 122 and the third doping part 121 can be connected, and the tooth tops of the sawtooth structures 1311 arranged in multiple layers can support the extension part 15 including the fourth doping part 122, thereby preventing the fourth doping part 122 from being disconnected from the third doping part 121, preventing the fourth doping part 122 from falling, and further preventing the solar cell from having a short circuit problem. Alternatively, even if the third doping part 121 and the fourth doping part 122 are not connected, the existence of the tooth tops of the sawtooth structures 1311 of the second inclined sidewalls 132 arranged in multiple layers can support the extension part 15 including the fourth doping part 122, thereby preventing the fourth doping part 122 from falling, and further preventing the solar cell from having a short circuit problem.

[0107] Optionally, based on the above embodiments, continue to refer to Fig.14 The solar cell further includes a passivation layer 14 , which may surround the fourth doped portion 122 , and the extension portion 15 close to the second inclined sidewall 132 includes the fourth doped portion 122 and the passivation layer 14 .

[0108] Specifically, the sawtooth structure 1311 of the second inclined sidewall 132 may support the extension portion 15 including the fourth doping portion 122 and the passivation layer 14 close to the second inclined sidewall 132 .

[0109] The fourth doped portion 122 and the passivation layer 14 can be collectively referred to as a "brim structure", which can directly reflect light to the light trapping structure of the second inclined sidewall 132. The reflection of the incident light can be effectively increased, and the incident light is reflected to the light trapping structure formed by the sawtooth structure 1311 of the second inclined sidewall 132 arranged in multiple layers, thereby further improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell.

[0110] Optionally, based on the above embodiments, continue to refer to Fig.14 The portion of the substrate 10 close to the first surface 101 extends to the isolation region 13 in the opposite direction of the first direction X to form a reflective portion 105; the solar cell also includes a passivation layer 14, which surrounds the reflective portion 105 and the fourth doped portion 122; the extension portion 15 close to the second inclined sidewall 132 includes the fourth doped portion 122, the reflective portion 105 and the passivation layer 14.

[0111] The fourth doped portion 122, the reflective portion 105 and the passivation layer 14 may be collectively referred to as a "brim structure", which can directly reflect light to the light trapping structure of the second inclined sidewall 132. The reflection of the incident light can be effectively increased, so that the incident light is reflected to the light trapping structure formed by the sawtooth structure 1311 of the second inclined sidewall 132 arranged in multiple layers, thereby further improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell. The sawtooth structure 1311 of the second inclined sidewall 132 can support the extension portion 15 including the fourth doped portion 122, the reflective portion 105 and the passivation layer 14.

[0112] Further, the tooth tops of the sawtooth structure 1311 of the second inclined sidewall 132 may be distributed between the reflecting portion 105 and the end position B2.

[0113] Optionally, based on the above embodiments, continue to refer to Fig.14 The solar cell further includes a second tunneling layer 17 located between the reflective portion 105 and the fourth doped portion 122 near the second inclined sidewall 132 ; the extension portion 15 near the second inclined sidewall 132 includes the fourth doped portion 122 , the second tunneling layer 17 , the reflective portion 105 and the passivation layer 14 .

[0114] Specifically, the solar cell may further include a second tunneling layer 17 located on the side of the second doping layer 12 close to the first surface 101. The second tunneling layer 17 may be a tunneling oxide layer (e.g., a tunneling silicon oxide layer), an intrinsic silicon carbide layer, and an intrinsic amorphous silicon layer, and the like, and is not specifically limited here.

[0115] The sawtooth structure 1311 of the second inclined sidewall 132 can support the extension portion 15 including the fourth doped portion 122, the second tunneling layer 17, the reflective portion 105 and the passivation layer 14. The fourth doped portion 122, the second tunneling layer 17, the reflective portion 105 and the passivation layer 14 can be collectively referred to as a "brim structure", which can directly reflect light to the light trapping structure of the second inclined sidewall 132. It can effectively increase the reflection of the incident light, so that the incident light is reflected to the light trapping structure composed of multiple stacked sawtooth structures 1311, thereby further improving the absorption of light by the solar cell, improving the utilization rate of light by the solar cell, and improving the current density of the solar cell.

[0116] Optionally, based on the above embodiments, the top of the sawtooth structure 1311 on the second inclined sidewall 132 close to the second doping layer 12 is in contact with the passivation layer 14. Alternatively, the top of the sawtooth structure 1311 on the second inclined sidewall 132 close to the second doping layer 12 is in contact with the passivation layer 14 and the fourth doping portion 122. Alternatively, the top of the sawtooth structure 1311 on the second inclined sidewall 132 close to the second doping layer 12 is in contact with the passivation layer 14, the second tunneling layer 17, and the fourth doping portion 122. Alternatively, the top of the sawtooth structure 1311 on the second inclined sidewall 132 close to the second doping layer 12 is in contact with the passivation layer 14 and the second tunneling layer 17.

[0117] Optionally, based on the above embodiments, continue to refer to Fig.14 The sawtooth structure 1311 of the second inclined side wall 132 includes a plurality of protrusions with different protrusion heights in the second direction Y; the protrusion contacting the extension portion 15 close to the second inclined side wall 132 is the tooth top of the sawtooth structure 1311 of the second inclined side wall 132. Adjacent protrusions are stacked.

[0118] Optionally, based on the above embodiments, continue to refer to Fig.14 The reflective portion 105 close to the second inclined sidewall 132 is located on the second partial region of the second inclined sidewall 132, close to the portion where the third doping portion 121 and the fourth doping portion 122 are connected. The vertical projection of the reflective portion 105 on the first surface 101 is located within the vertical projection of the fourth doping portion 122 on the first surface 101.

[0119] Specifically, the reflective portion 105 close to the second inclined sidewall 132 may be disposed at a portion of the second inclined sidewall 132 close to the connection between the third doping portion 121 and the fourth doping portion 122. The reflective portion 105 may be disposed in a second portion of the second inclined sidewall 132, and Fig.14The light trapping structure formed by the sawtooth structures 1311 of the second inclined sidewalls 132 arranged in multiple layers as shown can be arranged in a first partial region of the second inclined sidewall 132, and the first partial region and the second partial region can be different regions.

[0120] The extension portion 15 including the fourth doping portion 122 can be referred to as a "brim structure", which can reflect the light to the second inclined side wall 132 through the reflection portion 105 near the second inclined side wall 132, or directly reflect the incident light to the interior of the solar cell, thereby preventing the light from entering the gap between the connection between the fourth doping portion 122 and the third doping portion 121 and the second inclined side wall 132 and from entering the interior of the solar cell. It should be noted that the light entering the gap between the connection between the fourth doping portion 122 and the third doping portion 121 and the second inclined side wall 132 is equivalent to the light propagating parallel to the first surface 101, and thus cannot enter the interior of the solar cell.

[0121] In summary, the side of the reflective portion 105 close to the second inclined sidewall 132 close to the isolation region 13 can reflect part of the incident light to the inside of the solar cell, thereby improving the solar cell's absorption of light, improving the solar cell's utilization of light, and increasing the current density of the solar cell.

[0122] Optionally, based on the above embodiments, continue to refer to Fig.14 The angle between a surface of the reflection portion 105 close to the second inclined side wall 132 and the isolation region 13 is in the range of 90°-120°.

[0123] Specifically, when the contact area between the reflecting portion 105 and the extending portion 15 remains unchanged, if the angle between the side of the reflecting portion 105 close to the second inclined side wall 132 close to the isolation region 13 and the second inclined side wall 132 is too small, the volume of the reflecting portion 105 located at the second inclined side wall 132 is too small, and the incident light irradiated at the angle between the side of the reflecting portion 105 close to the isolation region 13 and the second inclined side wall 132 will not be effectively reflected to the interior of the solar cell, thereby failing to effectively improve the absorption of light by the solar cell, thereby improving the utilization rate of light by the solar cell, and increasing the current density of the solar cell.

[0124] When the contact area between the reflecting portion 105 and the extending portion 15 remains unchanged, if the angle between the side of the reflecting portion 105 close to the isolation region 13 and the second inclined sidewall 132 is too large, the volume of the reflecting portion 105 located at the second inclined sidewall 132 is too large and occupies too large an area of ​​the second inclined sidewall 132, which correspondingly reduces the area of ​​the second inclined sidewall 132 that can be contacted by the sawtooth structure 1311, which is not conducive to the light trapping structure formed by the sawtooth structure 1311 to effectively increase the surface area of ​​the second inclined sidewall 132.

[0125] Optionally, based on the above embodiments, continue to refer to Fig.14 The included angle between the second inclined side wall 132 close to the second doping layer 12 and the surface of the third doping portion 121 close to the substrate 10 is an obtuse angle.

[0126] An embodiment of the present invention provides a battery assembly, wherein the battery assembly includes any solar cell provided by any of the above embodiments of the present invention, and has the beneficial effects of any solar cell provided by any of the above embodiments of the present invention.

[0127] The embodiment of the present invention provides a photovoltaic system, wherein the photovoltaic system includes the battery assembly provided by the above embodiment of the present invention, and has the beneficial effects of the battery assembly provided by the above embodiment of the present invention. Since the battery assembly provided by the embodiment of the present invention has the beneficial effects of any solar cell provided by any of the above embodiments of the present invention, the photovoltaic system provided by the embodiment of the present invention has the beneficial effects of any solar cell provided by any of the above embodiments of the present invention.

[0128] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0129] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A solar cell, characterized in that: include: A substrate, the substrate comprising a first surface and a second surface disposed opposite to each other; A first doping layer and a second doping layer are alternately arranged on the first surface, the first doping layer and the adjacent second doping layer are separated by an isolation region, the conductivity type of the first doping layer is different from the conductivity type of the second doping layer; the conductivity type of the first doping layer is different from the conductivity type of the substrate; The first doping layer includes a first doping portion, and the first doping portion is located on the first surface; The two side walls of the isolation region are inclined side walls, and a light trapping structure is disposed in a first portion of the inclined side walls, wherein the light trapping structure includes a plurality of sawtooth structures; The first doping layer further includes: a second doping portion; The solar cell further includes an extension portion, the extension portion extending from the first doping layer toward the isolation region; a vertical projection of the extension portion on the first surface covers a portion of a vertical projection of the inclined sidewall on the first surface; The extension portion includes the second doping portion; the tooth top of the sawtooth structure on the inclined side wall close to the first doping layer contacts the extension portion.

2. The solar cell according to claim 1, characterized in that The light trapping structure includes a plurality of stacked sawtooth structures.

3. The solar cell according to claim 1, characterized in that The tooth top of the sawtooth structure includes a first side surface and a second side surface, and the included angle between the first side surface and the second side surface is greater than or equal to 70° and less than or equal to 110°.

4. The solar cell according to claim 1, characterized in that There is a spacing between the tooth tops of two adjacent sawtooth structures.

5. The solar cell according to claim 4, characterized in that: The spacing between the tooth tops of two adjacent sawtooth structures is 0.1um-3um.

6. The solar cell according to claim 1, characterized in that Along the extending direction of the extending portion, the tooth tops of the plurality of sawtooth structures are distributed between the starting position and the ending position of the extending portion.

7. The solar cell according to claim 6, characterized in that: Along the extending direction of the extending portion, there is a distance between the starting position of the extending portion and the tooth top of the sawtooth structure.

8. The solar cell according to claim 1, characterized in that The second doping portion and the first doping portion are integrally provided.

9. The solar cell according to claim 1, characterized in that: The second doping portion and the first doping portion are arranged at an interval.

10. The solar cell according to claim 1, characterized in that: A hole is provided at a portion where the second doping portion and the first doping portion are connected.

11. The solar cell according to claim 1, characterized in that: The solar cell further includes a passivation layer surrounding the second doped portion, and the extension portion includes the second doped portion and the passivation layer.

12. The solar cell according to claim 1, characterized in that A portion of the substrate close to the first surface extends to the isolation region along a direction in which the first doping layer points to the isolation region to form a reflection portion; The solar cell further includes a passivation layer, wherein the passivation layer surrounds the reflective portion and the second doped portion; The extending portion includes the second doped portion, the reflective portion, and the passivation layer.

13. The solar cell according to claim 12, characterized in that: It also includes a first tunneling layer located between the reflective portion and the second doped portion; The extension portion includes the second doped portion, the first tunneling layer, the reflective portion, and the passivation layer.

14. The solar cell according to claim 13, characterized in that: The tooth top of the sawtooth structure on the inclined side wall close to the first doping layer is in contact with the passivation layer; Alternatively, the tooth top of the sawtooth structure on the inclined side wall close to the first doping layer is in contact with the passivation layer and the second doping portion; Alternatively, the tooth top of the sawtooth structure on the inclined side wall close to the first doping layer is in contact with the passivation layer, the first tunneling layer and the second doping portion; Alternatively, the tooth tops of the sawtooth structure on the inclined sidewall close to the first doping layer are in contact with the passivation layer and the first tunneling layer.

15. The solar cell according to claim 1, characterized in that The sawtooth structure includes a plurality of protrusions with different protrusion heights in the direction from the first surface to the second surface; the protrusions in contact with the extension portion are the tooth tops of the sawtooth structure; The adjacent protrusions are stacked.

16. The solar cell according to claim 12, characterized in that: The reflective portion is located on a second partial region of the inclined sidewall close to a portion where the first doped portion and the second doped portion are connected; A vertical projection of the reflective portion on the first surface is located within a vertical projection of the second doped portion on the first surface.

17. The solar cell according to claim 16, characterized in that: The angle between a surface of the reflective portion close to the isolation region and the inclined side wall is in the range of 90°-120°.

18. The solar cell according to claim 1, characterized in that An angle between the inclined side wall close to the first doping layer and a surface of the first doping portion close to the substrate is an obtuse angle.

19. The solar cell according to claim 1, characterized in that The isolation area is provided with an isolation groove, and the isolation groove includes a first sub-groove and a second sub-groove connected to each other; The first sub-groove extends from a surface of the first doped layer away from the substrate to the first surface; The second sub-groove extends from the first surface to the inside of the substrate; The inclined side wall is a side wall of the second sub-groove.

20. A battery assembly, characterized in that: A solar cell comprising the solar cell according to any one of claims 1 to 19.

21. A photovoltaic system, characterized in that: A battery assembly comprising the battery assembly of claim 20.

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