Solar cell and photovoltaic module

Abstract

The invention provides a solar cell and a photovoltaic module, the solar cell comprises a silicon substrate, the back surface of the silicon substrate comprises P-type doped regions and N-type doped regions which are alternately arranged, the P-type doped regions correspond to P-type doped layers, the N-type doped regions correspond to N-type doped layers, isolation channels are arranged between the adjacent P-type doped regions and N-type doped regions, and the isolation channels are communicated with the P-type doped regions and the N-type doped regions. The surface of the isolation channel is provided with a first suede structure, the height difference between the P-type doped layer and the first suede structure is H1, the height difference between the N-type doped layer and the first suede structure is H2, and H1 is greater than H2; the side wall, adjacent to the P-type doped region, of the isolation channel is provided with at least two light reflection supporting arms, the electric leakage of the BC solar cell can be reduced, meanwhile, the light utilization rate of the BC solar cell can be improved, and higher photoelectric conversion efficiency is achieved.

Description

Technical Field

[0001] This application relates to the field of solar cells, and in particular, to a solar cell and a photovoltaic module. Background Art

[0002] A solar cell is a device that converts solar energy into electrical energy, and has the advantages of being clean and pollution-free, and has been widely used in the power generation industry.

[0003] Among them, a BC solar cell is a solar cell with no metal grid lines on the front side and the metal grid lines of the P / N regions are distributed in a finger-like cross pattern on the back side of the cell. How to improve the BC solar cell to reduce its leakage current and improve its light utilization rate, so as to improve the photoelectric conversion efficiency of the BC solar cell, has become a technical problem to be solved urgently. Summary of the Invention

[0004] To solve the above technical problems, this application discloses a solar cell and a photovoltaic module, which can reduce the leakage current of the BC solar cell while improving its light utilization rate, thereby improving the photoelectric conversion efficiency of the BC solar cell.

[0005] In a first aspect, this application provides a solar cell, including a silicon substrate. The back side of the silicon substrate includes alternately arranged P-type doped regions and N-type doped regions. The P-type doped regions correspond to P-type doped layers, and the N-type doped regions correspond to N-type doped layers. An isolation channel is provided between adjacent P-type doped regions and N-type doped regions. The surface of the isolation channel has a first textured structure, wherein: The height difference between the P-type doped layer and the first textured structure is H 1 , and the height difference between the N-type doped layer and the first textured structure is H 2 , H 1 > H 2 ; The side wall of the isolation channel adjacent to the P-type doped region has at least two reflective arms.

[0006] In some embodiments of this application, 1.5 μm ≤ H 2 ≤ 5 μm, and 1.5 ≤ H 1 / H 2 ≤ 3.5.

[0007] In some embodiments of this application, the reflective arms include a first reflective arm and a second reflective arm, and both the first reflective arm and the second reflective arm are located on the side wall of the isolation channel adjacent to the P-type doped region.

[0008] In some embodiments of this application, the height difference between the second reflective arm and the first reflective arm is H 3 , 1.5 μm ≤ H3 ≤ 3 μm.

[0009] In some embodiments of the present application, the length of the first reflective arm is L 1 , and the length of the second reflective arm is L 2 , L 1 < L 2 .

[0010] In some embodiments of the present application, 0.5 μm ≤ L 1 ≤ 1 μm, 1 μm ≤ L 2 ≤ 2 μm.

[0011] In some embodiments of the present application, the inclination angle of the sidewall of the isolation channel adjacent to the P-type doped region is 40° - 60°.

[0012] In a second aspect, the present application provides a photovoltaic module, which includes the solar cell as described in the first aspect.

[0013] Compared with the prior art, the present application has at least the following beneficial effects: The present application provides a solar cell and a photovoltaic module. The solar cell includes a silicon substrate. The back surface of the silicon substrate includes alternately arranged P-type doped regions and N-type doped regions. The P-type doped regions correspond to P-type doped layers, and the N-type doped regions correspond to N-type doped layers. An isolation channel is provided between adjacent P-type doped regions and N-type doped regions. The surface of the isolation channel has a first textured structure; the height difference between the P-type doped layer and the first textured structure is H 1 , and the height difference between the N-type doped layer and the first textured structure is H 2 , H 1 > H 2 , which can reduce adverse phenomena such as leakage; at least two reflective arms are provided on the adjacent side of the P-type doped region and the isolation channel. The reflective arms are used to reflect the light emitted from the isolation channel back into the silicon substrate, thereby improving the utilization rate of light on the back surface of the battery. The solar cell with the structure of the present application can reduce the leakage of the BC solar cell while improving its light utilization rate, and has a higher photoelectric conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0015] Figure 1 It is a schematic structural diagram of a solar cell according to an embodiment of the present application; Figure 2 This is the morphology diagram of the solar cell in one embodiment of the present application; Figure 3 This is the morphology diagram of the solar cell in another embodiment of the present application; Figure 4 This is a partial schematic diagram of the solar cell in one embodiment of the present application; Figure 5 This is a schematic structural diagram of the solar cell in another embodiment of the present application; Figure 6 This is a schematic structural diagram of the semi-finished solar cell after the first coating treatment of the present application; Figure 7 This is a schematic structural diagram of the semi-finished solar cell after the first patterning treatment of the present application; Figure 8 This is a schematic structural diagram of the semi-finished solar cell after the second polishing treatment of the present application; Figure 9 This is a schematic structural diagram of the semi-finished solar cell after the second coating treatment of the present application; Figure 10 This is a schematic structural diagram of the semi-finished solar cell after the second patterning treatment of the present application; Figure 11 This is a schematic structural diagram of the solar cell in yet another embodiment of the present application.

[0016] Explanation of reference numerals: silicon substrate - 1, P-type doped layer - 2, N-type doped layer - 3, isolation channel - 4, first textured structure - 5, first dielectric layer - 6, second dielectric layer - 7, reflective arm - 8, sidewall - 9, first passivation layer - 10, first antireflection layer - 11, second passivation layer - 12, second antireflection layer - 13, electrode grid line - 14, first silicon oxide mask layer - 21, patterned area - 22, second silicon oxide mask layer - 31, micro-unit structure - 51, first reflective arm - 81, second reflective arm - 82. Detailed implementation manners

[0017] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0018] In this application, the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal", etc. is based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe this application and its embodiments, and are not used to limit that the indicated device, element or component must have a specific orientation, or be constructed and operated in a specific orientation.

[0019] Moreover, in addition to being able to represent the orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0020] In addition, the terms "mounted", "arranged", "provided with", "connected", "linked" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there is an internal connection between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0021] In addition, terms such as "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, the meaning of "a plurality" is two or more.

[0022] The technical solution of this application will be further described below in conjunction with embodiments and drawings.

[0023] This application provides a solar cell. Figure 1 As shown in the structural schematic diagram of the solar cell of an embodiment of this application, as Figure 1 shown, the solar cell includes a silicon substrate 1. The back surface of the silicon substrate 1 includes alternately arranged P-type doped regions and N-type doped regions. The P-type doped regions correspond to P-type doped layers 2, and the N-type doped regions correspond to N-type doped layers 3. An isolation channel 4 is provided between adjacent P-type doped regions and N-type doped regions. The surface of the isolation channel 4 has a first textured structure 5, where: the height difference between the P-type doped layer 2 and the first textured structure 5 is H 1 , and the height difference between the N-type doped layer 3 and the first textured structure 5 is H 2 , H 1 > H 2;The side wall 9 adjacent to the P-type doped region of the isolation channel 4 has at least two reflective arms 8. In addition, a first dielectric layer 6 is provided on the back surface of the silicon substrate 1 in the P-type doped region, and the P-type doped layer 2 is provided on the surface of the first dielectric layer 6; a second dielectric layer 7 is sequentially provided on the back surface of the silicon substrate 1 in the N-type doped region, and the N-type doped layer 3 is provided on the surface of the second dielectric layer 7.

[0024] In this application, referring to Figure 1 , the first textured structure 5 may be formed by a plurality of pyramid-shaped micro-unit structures 51, and the pyramid-shaped micro-unit structures 51 may be formed during the process of texturing the front surface of the solar cell. In this application, the height difference H 1 between the P-type doped layer and the first textured structure refers to: the distance between the top of the P-type doped layer and the bottom of the first textured structure; the height difference H 2 between the N-type doped layer and the first textured structure refers to: the distance between the top of the N-type doped layer and the bottom of the first textured structure.

[0025] In this application, by controlling H 1 > H 2 , it is possible to reduce adverse phenomena such as leakage. This is because in the existing BC solar cell structure process, the P-type doped layer is grown first, and then the N-type doped region is obtained through the first patterning process and alkaline solution polishing. To achieve effective isolation of the back surface P-type doped region and N-type doped region, the N-type doped region is etched downward by the alkaline solution to the silicon substrate. And, the adjacent side of the P-type doped region and the isolation channel has at least two reflective arms, and the reflective arms are used to reflect the light emitted from the isolation channel back into the silicon substrate, thereby improving the light utilization rate of the back surface of the battery. The solar cell with the structure of this application can reduce the leakage of the BC solar cell while improving its light utilization rate, and has a higher photoelectric conversion efficiency.

[0026] The materials of the first dielectric layer and / or the second dielectric layer in the present application may include a variety of dielectric materials, such as at least one of silicon oxide, magnesium fluoride, amorphous silicon, polycrystalline silicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide, or titanium oxide. Specifically, the dielectric layer may be composed of a silicon oxide layer containing silicon oxide. This is because the silicon oxide layer has excellent passivation performance, can minimize the recombination loss of minority carriers on the surface of the semiconductor substrate, and is a film with excellent durability for subsequent high-temperature processes. To better provide interface passivation for the substrate, the thickness of the dielectric layer may be 0.1 nm to 5 nm. For example, the thickness of the dielectric layer may be 0.1 nm, 0.5 nm, 1 nm, 1.5 nm, 2 nm, 3 nm, 4 nm, 5 nm, etc. However, the present application is not limited thereto, and the thickness of the dielectric layer may have various values. The dielectric layer, as a kind of barrier for electrons and holes, can combine with the polycrystalline silicon layer to prevent minority carriers from passing through. The dielectric layer can also have the function of pinhole channels, enabling the carriers in the solar cell to move freely, generating selective passage for majority carriers through heavily doped polycrystalline silicon, which is beneficial to reducing the recombination loss of minority carriers. In addition, the dielectric layer can be used as a diffusion barrier to prevent the dopant in the doped polycrystalline silicon layer from diffusing into the semiconductor substrate.

[0027] The thickness of the silicon substrate in the present application is 100 μm to 200 μm, and the present application does not make specific limitations.

[0028] In some embodiments of the present application, 1.5 μm ≤ H 2 ≤ 5 μm, and 1.5 ≤ H 1 / H 2 ≤ 3.5. For example, H 2 is 1.5 μm, 2 μm, 3 μm, 4 μm, or 5 μm, and H 1 / H 2 is 1.5, 2, 2.5, 3, or 3.5. The inventors have found through research that when H 2 is too small (e.g., less than 1.5 μm), there are polishing residues in the N-type doping region and the isolation channel, which are likely to be conductive with the P-type doping region, resulting in a relatively large leakage current in the solar cell; when H 2 is too large (e.g., greater than 5 μm), the depth of the N-type doping region and the isolation channel is too large, and it is necessary to increase the etching with alkaline solution, resulting in the corrosion and damage of the film layer structure of the N-type doping region; when H 1 / H 2 is too small (e.g., less than 1.5), the silicon oxide layer, doped polycrystalline silicon layer, and the generated inner diffusion layer generated by doping cannot be completely removed, and a better isolation effect cannot be guaranteed, and it is also likely to result in a relatively large leakage current; when H 1 / H 2 is too large (e.g., greater than 3.5), it will increase the difficulty of subsequent electrode paste printing and affect the printing quality of the electrode grid lines. By controlling H2 and H 1 / H 2 Within the scope of the present application, it is beneficial to improve the printing quality of the electrode gate line while reducing leakage current.

[0029] In some embodiments of the present application, referring to Figure 1 , the reflective support arm 8 includes a first reflective support arm 81 and a second reflective support arm 82. Both the first reflective support arm 81 and the second reflective support arm 82 are located at the side wall 9 adjacent to the isolation channel 4 and the P-type doped region. The first reflective support arm and the second reflective support arm can make part of the light refracted from the back side of the silicon substrate return to the silicon substrate and be absorbed and utilized by the silicon substrate under the combined reflection of the first reflective support arm and the second reflective support arm, increasing the utilization rate of light on the back side of the solar cell, thereby improving the photoelectric conversion efficiency.

[0030] Figure 2 is the morphology diagram of the solar cell in one embodiment of the present application, Figure 3 is the morphology diagram of the solar cell in another embodiment of the present application. As shown by the black dashed boxes in Figure 2 and Figure 3 , the reflective support arm of the present application includes a first reflective support arm 81 and a second reflective support arm 82. It can also be seen from Figure 2 and Figure 3 that the back side of the silicon substrate of the present application has a first velvet surface structure formed by a plurality of pyramid-shaped micro-unit structures.

[0031] In some embodiments of the present application, referring to Figure 1 , the height of the second reflective support arm 82 is higher than the height of the first reflective support arm 81. In the present application, the reference basis for the height of the second reflective support arm and the height of the first reflective support arm is the bottom of the first velvet surface structure 5. By controlling the height of the second reflective support arm to be higher than the height of the first reflective support arm, an effective spacing distance can be maintained between the first reflective support arm and the second reflective support arm, so as to better meet the multiple reflection and utilization of incident light.

[0032] In some embodiments of the present application, referring to Figure 1 , the height difference between the second reflective support arm and the first reflective support arm is H 3 , 1.5μm ≤ H 3 ≤ 3μm. For example, H 3 is 1.5μm, 1.8μm, 2.0μm, 2.5μm or 3μm. By controlling H 3 within the above range, part of the light refracted from the back side of the silicon substrate can return to the silicon substrate and be absorbed and utilized by the silicon substrate under the reflection of the first reflective support arm 81 and the second reflective support arm 82, thereby realizing the multiple utilization of light.

[0033] In some embodiments of the present application, reference is made to Figure 4 , Figure 4 which is a partial schematic view of a solar cell in an embodiment of the present application. The length of the first reflective arm 81 is L 1 , and the length of the second reflective arm 82 is L 2 , L 1 <L 2 . In the present application, the length L 1 of the first reflective arm 81 refers to the length that the part of the silicon substrate 1 located in the P-type doping region extends outward from the sidewall 9 of the P-type doping region. The length L 2 of the second reflective arm 82 refers to the length that the P-type doping layer 2 extends outward from the sidewall 9 of the P-type doping region. By controlling L 1 <L 2 , it is possible to avoid the reflection light of the first reflective arm 81 from blocking the second reflective arm 82, and increase the multiple utilization of light between the first reflective arm 81 and the second reflective arm 82.

[0034] In some embodiments of the present application, 0.5μm ≤ L 1 ≤ 1μm, 1μm ≤ L 2 ≤ 2μm. For example, L 1 is 0.5μm, 0.6μm, 0.8μm or 1μm, and L 2 is 1μm, 1.2μm, 1.5μm, 1.8μm or 2μm.

[0035] In some embodiments of the present application, reference is made to Figure 4 , the inclination angle α of the sidewall 9 adjacent to the isolation channel and the P-type doping region is 40° - 60°. For example, α is 40°, 45°, 50°, 55° or 60°. In this way, it is possible to make the light experience multiple reflections and refractions between the inclined surface of this sidewall, the first reflective arm, the second reflective arm and the first texture structure, increase the optical path of the light on the back of the solar cell, and is beneficial to the increase of the light absorption of the silicon substrate, thereby increasing the utilization rate of the light on the back of the solar cell.

[0036] In some embodiments of the present application, reference is made to Figure 5 , Figure 5 which is a schematic structural view of a solar cell in another embodiment of the present application. A first passivation layer 10 and a first antireflection layer 11 are sequentially provided on the back of the silicon substrate 1. The front of the silicon substrate 1 has a second texture structure, and a second passivation layer 12 and a second antireflection layer 13 are sequentially provided on the front of the silicon substrate 1. In addition, electrode grid lines 14 are respectively provided in the P-type doping region and the N-type doping region.

[0037] In the present application, the preparation process of the solar cell can be: First polishing treatment: The silicon substrate is etched and polished using a mixed solution of an alkaline solution and a pre-polishing additive to achieve the purpose of removing line marks and oil stains. The alkaline solution can be a NaOH solution or a KOH solution, the concentration of the alkaline solution is 0.5 wt% - 5 wt%, the process temperature is 60°C - 80°C, and the polishing time is 200 s - 800 s. After polishing, it is washed with a mixed solution containing hydrofluoric acid (concentration 1 wt% - 6 wt%) and hydrochloric acid (concentration 1.5 wt% - 5 wt%), and then washed and dried with deionized water. The pre-polishing additive can be a commercially available pre-polishing additive, and there is no special limitation in this application as long as it can achieve the purpose of this application.

[0038] First coating treatment: Using low-pressure chemical vapor deposition (LPCVD), a first dielectric layer and an intrinsic amorphous silicon layer are sequentially deposited on the back of the silicon substrate. The thickness of the first dielectric layer is 0.5 nm - 3 nm, and the thickness of the intrinsic amorphous silicon layer is 100 nm - 300 nm. The deposition temperature of LPCVD is 550°C - 650°C; then the solar cell semi-finished product is doped with the intrinsic amorphous silicon layer by thermal diffusion. For example, using BCl 3 as the doping source, a P-type doped layer with a thickness of 200 nm - 400 nm is obtained, and a first silicon oxide mask layer with a thickness of 20 nm - 60 nm is formed on the surface of the P-type doped layer. The structure of the solar cell semi-finished product obtained after the first coating treatment is as Figure 6 shown. On the back of the silicon substrate 1 are sequentially the first dielectric layer 6, the P-type doped layer 2, and the first silicon oxide mask layer 21.

[0039] First patterning treatment: The solar cell semi-finished product is subjected to the first patterning treatment by laser scanning to form a patterned area, and the action depth of the patterning treatment is ≥ the thickness of the first silicon oxide mask layer. The laser-related parameters in this application can be: the laser type is at least one of nanosecond laser, picosecond laser, and femtosecond laser, the light type is any one of infrared laser, visible light laser, and ultraviolet laser, the energy density of the laser is 30 mJ / cm 2 ~3000 mJ / cm 2 , the wavelength is 700 nm - 1000 nm, and the spot shape of the laser can be circular or square. The structure of the solar cell semi-finished product obtained after the first patterning treatment is as Figure 7 shown, and a patterned area 22 is formed.

[0040] Second polishing treatment: The patterned area 22 is etched by alkali washing using a mixed solution of an alkali solution and a post-polishing additive until reaching the silicon substrate 1. The non-patterned area is not etched because it is protected by the first silicon oxide mask layer 21. The alkali solution can be an NaOH solution or a KOH solution, with the alkali solution concentration being 0.5 wt% - 5 wt%, the process temperature being 60°C - 80°C, and the polishing time being 200 s - 600 s. The main components of the post-polishing additive are sodium gluconate, a protective agent, a brightening agent, etc., and it can be a commercially available post-polishing additive. Exemplarily, it can be the post-polishing additive of model BPL719. After polishing, alkali washing and water washing are carried out using an alkali-containing solution, pickling is carried out using an acid-containing solution, and processes such as water washing and drying are carried out for standby. The structure of the solar cell semi-finished product after the second polishing treatment is as Figure 8 shown.

[0041] Second coating treatment: Using the method of enhanced plasma chemical vapor deposition (PECVD), a second dielectric layer and a second doped amorphous silicon layer are sequentially grown on the patterned area, non-patterned area, and side of the back surface of the solar cell semi-finished product after the second polishing treatment, and a second silicon oxide mask layer with a thickness of 20 nm - 60 nm is formed on the surface of the second doped crystalline silicon layer. Among them, the doping type of the second doped amorphous silicon layer is opposite to that of the first doped layer; at the same time, crystallization is achieved in a high-temperature environment (temperature 700°C - 900°C), and the doped amorphous silicon in the second doped amorphous silicon layer is transformed into doped polycrystalline silicon to form a second doped layer. The structure of the solar cell semi-finished product obtained after the second coating treatment is as Figure 9 shown, and a second dielectric layer 7, an N-type doped layer 3, and a second silicon oxide mask layer 31 are sequentially formed on the back surface of the silicon substrate.

[0042] Second patterning treatment: The solar cell semi-finished product after the second coating treatment is subjected to second patterning treatment by laser scanning: The second silicon oxide mask layer in the patterned area is removed by laser to form a patterned second doped layer. The laser-related parameters of the present application can be: The laser type is at least one of nanosecond laser, picosecond laser, and femtosecond laser, the light type is any one of infrared laser, visible light laser, and ultraviolet laser, the energy density of the laser is 30 mJ / cm 2 ~3000 mJ / cm 2 , the wavelength is 700 nm - 1000 nm, and the laser spot size is a quadrilateral spot of (20 - 400) μm × (20 - 400) μm. The structure of the solar cell semi-finished product obtained after the second patterning treatment is as Figure 10 shown, and a patterned P-type doped layer 2, an N-type doped layer 3, and an isolation channel 4 are formed on the back surface of the silicon substrate, and the corresponding silicon oxide mask layers are retained on the surfaces of the P-type doped layer 2 and the N-type doped layer 3.

[0043] Texturing: After removing the bypass plating on the semi-finished solar cell by single-sided acid polishing, a mixed solution of texturing additive and NaOH is used for texturing. On the back of the semi-finished solar cell, a first textured surface structure is formed on the silicon substrate surface in the isolation trench 4; on the front of the semi-finished solar cell, a second textured surface structure is formed on the silicon substrate surface. The reaction time is 300s - 800s, and the process temperature is 60°C - 85°C. Among them, the model of the texturing additive is ZRY00B. In the mixed solution, the mass concentration of the texturing additive is 1% - 3%, and the mass concentration of NaOH is 0.5% - 2%. The texturing additive includes carboxymethyl cellulose, defoaming agent, and sodium lignosulfonate. Among them, the mass concentration of carboxymethyl cellulose is 1% - 2%, the mass concentration of the defoaming agent is 1% - 2%, and the mass concentration of sodium lignosulfonate is 0.5% - 2%. Then, the semi-finished solar cell is successively alkali-washed and water-washed with an alkali-containing solution, pickled with an HF acid-containing solution, and undergoes processes such as water-washing and drying.

[0044] Preparation of the functional layer: After removing the silicon oxide mask layer on the surfaces of the P-type doping region and the N-type doping region, by means of PECVD, an aluminum oxide layer is deposited on the front and back of the textured semi-finished solar cell as a passivation layer, and then a silicon nitride layer is respectively deposited on the surface of the aluminum oxide passivation layer as an antireflection layer; among them, referring to Figure 11 , the thickness of the first passivation layer 10 is 3nm - 8nm, and the thickness of the first antireflection layer 11 is 60nm - 90nm; the thickness of the second passivation layer 12 is 3nm - 8nm, and the thickness of the second antireflection layer 13 is 80nm - 110nm.

[0045] Preparation of the electrode grid lines: On the back of the semi-finished solar cell with the functional layer, the electrode paste is applied to the P-type doping region and the N-type doping region by screen printing, and then sintered, as Figure 5 shown, to form the electrode grid lines 14.

[0046] The present application does not particularly limit the method of forming the first light-reflecting arm and the second light-reflecting arm, as long as the purpose of the present application can be achieved. Exemplarily, in the above-mentioned second patterning process, by controlling the laser energy density at 30mJ / cm 2 ~3000mJ / cm 2 , the wavelength is 700nm - 1000nm, the laser spot size is a quadrilateral spot of (20 - 400)μm × (20 - 400)μm, synchronously matching the texturing process, the reaction time is 300s - 800s, and the process temperature is 60°C - 85°C, so as to form the second light-reflecting arm; in the above-mentioned first patterning process, by controlling the laser energy density to be 30mJ / cm 2 ~3000mJ / cm 2, with a wavelength of 700 nm to 1000 nm, synchronously matching the above-mentioned texturing process to form the first reflective arm. In the texturing process, a mixed solution of an additive composed of carboxymethyl cellulose with a mass concentration of 1% to 2%, a defoaming agent with a mass concentration of 1% to 2%, sodium lignosulfonate with a mass concentration of 0.5% to 2%, sodium gluconate with a mass concentration of 1% to 2%, and a brightening agent with a mass concentration of 0.5% to 1% and NaOH is used for the reaction. In the mixed solution, the mass concentration of the texturing additive is 1% to 3%, and the mass concentration of NaOH is 0.5% to 2%. The reaction time is 300 s to 800 s, and the process temperature is 60 °C to 85 °C.

[0047] The present application provides a photovoltaic module, and the photovoltaic module includes the solar cell described in any one of the above embodiments.

[0048] The present application further provides a photovoltaic module, which is used to convert the received light energy into electrical energy and transmit it to an external load. The photovoltaic module includes: at least one battery string, which is formed by connecting a plurality of the above-mentioned solar cells; an encapsulation film, which is used to cover the surface of the battery string; and a cover plate, which is used to cover the surface of the encapsulation film facing away from the battery string.

[0049] The above has introduced in detail a solar cell and a photovoltaic module disclosed in the present application. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the technical solution and the core inventive point of the embodiments of the present application: At the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A solar cell, characterized in that: A silicon substrate is included, wherein the back side of the silicon substrate includes alternately arranged P-type doping regions and N-type doping regions, the P-type doping regions correspond to the P-type doping layers, the N-type doping regions correspond to the N-type doping layers, an isolation channel is provided between the adjacent P-type doping regions and the N-type doping regions, and the surface of the isolation channel has a first velvet structure, wherein: The height difference between the P-type doped layer and the first velvet structure is H1, and the height difference between the N-type doped layer and the first velvet structure is H2, H1>H2; The side wall of the isolation channel adjacent to the P-type doping region has at least two light-reflecting arms.

2. The solar cell according to claim 1, characterized in that: 1.5μm≤H2≤5μm, and 1.5≤H1 / H2≤3.

5.

3. The solar cell according to claim 1, characterized in that: The reflective support arm includes a first reflective support arm and a second reflective support arm, and the first reflective support arm and the second reflective support arm are both located on a side wall of the isolation channel adjacent to the P-type doping region.

4. The solar cell according to claim 3, characterized in that: A height difference between the second reflective support arm and the first reflective support arm is H3, and 1.5 μm≤H3≤3 μm.

5. The solar cell according to claim 3, characterized in that: The length of the first reflective support arm is L1, the length of the second reflective support arm is L2, and L1<L2.

6. The solar cell according to claim 5, characterized in that: 0.5μm≤L1≤1μm, 1μm≤L2≤2μm.

7. The solar cell according to claim 1, characterized in that: The inclination angle of the side wall of the isolation channel adjacent to the P-type doping region is 40° to 60°.

8. A photovoltaic module, characterized in that: The photovoltaic module comprises the solar cell according to any one of claims 1 to 7.

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