Manufacturing method of solar cell and solar cell

Abstract

The invention relates to a manufacturing method of a solar cell and the solar cell, the solar cell is provided with a cell piece, the cell piece is provided with a light receiving side and a backlight side which are opposite to each other along the thickness, and the manufacturing method of the solar cell comprises the following steps: forming a tunneling dielectric layer and a doped conductive layer on the backlight side of the cell piece; grooves are formed in the light receiving surface or the backlight surface of the battery piece through a first laser, and the grooves are located in the two ends of the battery piece in the cutting direction; cutting the battery piece through a second laser, wherein the first laser and the second laser act on the same side of the battery piece; texturing is carried out on the cutting surface of the battery piece, so that a first pyramid structure is formed on the cutting surface of the battery piece; polishing the cutting surface of the battery piece, and etching the tip of the first pyramid structure; and passivating the battery piece. According to the invention, the damaged layer on the cutting surface is removed through texturing, and the flatness of the cutting surface is improved through polishing, so that the recombination of current carriers is reduced, and the photoelectric conversion efficiency of the solar cell is improved.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic cells, and in particular to a method for manufacturing a solar cell and a solar cell. Background Art

[0002] Solar cells can directly convert solar radiation energy into electrical energy, mainly based on the photovoltaic effect of crystalline silicon, that is, when the photons of sunlight are absorbed by semiconductor crystalline silicon, electron-hole pairs are generated. When these electron-hole pairs reach the pn junction composed of p-type crystalline silicon and n-type crystalline silicon, they are separated to both sides of the pn junction by the junction electric field. When an external load is connected, photocurrent is formed and electrical energy is output.

[0003] The manufacturing process of solar cells involves cutting a whole cell into two halves. There is a damaged layer on the cut surface of the cell. The damaged layer that is not removed will form a recombination center in the subsequent process, affecting the photoelectric conversion efficiency of the solar cell. Summary of the invention

[0004] The present application provides a method for manufacturing a solar cell and a solar cell, so as to solve the problem that a damaged layer generated during the cutting of a cell sheet affects the photoelectric conversion efficiency of the solar cell.

[0005] An embodiment of the present application provides a method for manufacturing a solar cell, wherein the solar cell has a cell sheet, and the cell sheet has a light-receiving side and a backlight side facing each other along the thickness. The method for manufacturing the solar cell includes: forming a tunnel dielectric layer and a doped conductive layer on the backlight side of the cell; Using a first laser to open a groove on the light-receiving surface or the backlight surface of the cell, the groove is located at two ends of the cell along the cutting direction; Cutting the battery sheet by a second laser, wherein the first laser and the second laser act on the same side of the battery sheet; Performing texturing on the cut surface of the battery cell so as to form a first pyramid structure on the cut surface of the battery cell; Polishing the cut surface of the cell and etching the tip of the first pyramid structure; The battery cell is passivated.

[0006] In one possible design, in the step of: opening a groove in the light-receiving surface or the backlight surface of the battery cell by using a first laser, an angle is formed between the laser light emitted by the first laser and the light-receiving surface or the backlight surface of the battery cell; and / or, in the step of: cutting the battery cell by using a second laser, an angle is formed between the laser light emitted by the second laser and the light-receiving surface or the backlight surface of the battery cell.

[0007] In a possible design, in the step of opening a groove in the light-receiving surface or the backlight surface of the cell by using a first laser, the power of the laser emitted by the first laser satisfies: 30W~100W.

[0008] In a possible design, in the step of cutting the battery cell by a second laser, the power of the laser emitted by the second laser satisfies: 300W~600W, the spot size of the laser emitted by the second laser satisfies: 1mm~2mm, and the moving speed of the spot satisfies: 500mm / s~800mm / s.

[0009] In a possible design, in step: after polishing the cut surface of the battery cell, the first pyramid structure has a first base, and the size of the upper surface of the first base satisfies: 0.5μm~2μm, and / or the height of the first base satisfies: 0.5μm~1.5μm.

[0010] In a possible design, the step of texturing the cut surface of the cell comprises: Putting the battery cell into a texturing tank, wherein the texturing tank contains at least an alkaline solvent and a texturing additive; Transferring the battery cell from the texturing tank to a first cleaning tank; Wherein, the volume ratio of the alkaline solvent and the texturing additive in the texturing tank satisfies: 1:1-15:1.

[0011] In a possible design, the step of polishing the cut surface of the cell comprises: Placing the battery cell into a polishing tank, wherein the polishing tank contains at least an alkaline solvent and a polishing additive; Transferring the battery cell from the texturing tank to a second cleaning tank; Wherein, the volume ratio of the alkaline solvent and the polishing additive in the polishing tank satisfies: 1.25:1~15:1.

[0012] In a possible design, in the step of texturing the cut surface of the cell, the cell is etched to a depth of 5 μm to 10 μm.

[0013] In a possible design, the step is: texturing the battery cell to form a first pyramid structure on the cut surface of the battery cell, the reaction temperature is: 60° C. to 80° C., and the reaction time is: 300s to 800s; And / or, step: polishing the cut surface of the battery cell, etching the tip of the first pyramid structure, the reaction temperature is: 60° C.~80° C., and the reaction time is: 100s~200s.

[0014] A solar cell provided in an embodiment of the present application is manufactured by the above-mentioned method for manufacturing a solar cell; the cell comprises: A substrate, wherein the substrate has a second pyramid structure on the light-receiving side and a third pyramid structure on the backlight side; An emitter, the emitter being disposed on the light-receiving side of the substrate; A tunneling dielectric layer, the tunneling dielectric layer being disposed on the backlight side of the substrate; A doped conductive layer, wherein the doped conductive layer is disposed on a side of the tunnel dielectric layer away from the substrate; A passivation layer is arranged on a side of the emitter away from the substrate, a side of the doped conductive layer away from the substrate, and the cut surface.

[0015] In a possible design, an angle between a cutting surface of the battery cell and a thickness direction of the battery cell satisfies: 30°~60°.

[0016] In the present application, the second laser first irradiates the laser at the position of one of the grooves, and then moves to the position of the other groove along the cutting path. In this process, heat is generated at the laser action position of the second laser. With the change of the laser action position and the superposition of cooling means (for example, spraying coolant to the position where the laser has acted), a temperature gradient is generated on the cell, and the temperature gradient generates tensile stress. The tensile stress causes a crack to be formed on the cell extending along a predetermined path, thereby achieving the cutting of the cell. Among them, the first groove can guide the crack so that the crack extends along the predetermined path, and at the same time preheat the area where the laser spot is about to act, thereby increasing the temperature that can be reached at the laser action position. Since the second laser stops emitting laser at the end of cutting the cell, the source of the temperature gradient required for crack expansion disappears, so the second groove can assist the fracture of the end of the cell. Texturing will etch the damaged layer on the cutting surface, remove the damaged layer on the cutting surface, thereby preventing the existence of the damaged layer from causing the subsequent solar cell to have a high recombination and a low photoelectric conversion efficiency. By etching the tip of the first pyramid structure, the flatness of the cut surface can be improved, which facilitates the growth of the passivation layer on the cut surface, improves the passivation effect of the passivation layer on the cut surface, reduces the recombination of carriers, and thus improves the photoelectric conversion efficiency of the solar cell.

[0017] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the structure of a solar cell provided in the present application in a specific embodiment; Figure 2 A flow chart of a method for manufacturing a solar cell provided in the present application; Figure 3 It is a schematic diagram of the structure of the battery cell after the step of: using a first laser to open a groove on the light-receiving surface or the backlight surface of the battery cell; Figure 4 It is a schematic diagram of the structure of the battery cell before and after the substrate is texturized; Figure 5 The schematic diagram of the structure of the battery cell before and after boron diffusion is performed on the battery cell; Figure 6 It is a schematic diagram of the structure of the cell before and after the light-receiving side of the cell is oxidized; Figure 7 It is a schematic diagram of the structure of the cell before and after the step of removing the borosilicate glass layer on the backlight side and the side of the cell; Figure 8 The schematic diagram of the structure of the cell before and after polishing the backlight side of the cell is shown in the step: Fig. 9 The schematic diagram of the structure of the cell before and after the tunnel dielectric layer and the doped conductive layer are formed on the backlight side of the cell; Fig.10 A flow chart of a method for manufacturing a solar cell provided in the present application; Fig.11 A schematic diagram of the structure of cutting a battery cell along a direction perpendicular to the thickness of the battery cell; Fig.12 The battery cell is in the process of: a schematic diagram of the structure before and after chain cleaning of the battery cell; Fig.13 The schematic diagram of the structure of the cell before and after texturing the cut surface of the cell; Fig.14 The schematic diagram of the structure of the cell before and after polishing the cut surface of the cell is shown in step 1. Fig.15 It is a schematic diagram of the structure of the cell before and after the step of removing the borosilicate glass layer on the light-receiving side of the cell and the phosphosilicate glass layer on the backlight side; Fig.16 The schematic diagram of the structure of the battery cell before and after passivation is performed; Fig.17 A flow chart of a method for manufacturing a solar cell provided in the present application; Fig.18 A schematic diagram of the structure of cutting a battery cell along the thickness direction of the inclined battery cell; Fig.19 This is a schematic structural diagram of a solar cell provided in the present application in another specific embodiment.

[0019] Reference numerals: 1- substrate; 2-Emitter; 3- tunnel dielectric layer; 4- doped conductive layer; 5- passivation layer; 6- borosilicate glass layer; 7-phosphosilicate glass layer; 8- Grooves.

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application. DETAILED DESCRIPTION

[0021] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0022] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0023] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0024] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0025] It should be noted that the directional words such as "upper", "lower", "left", and "right" described in the embodiments of the present application are described at the angles shown in the accompanying drawings and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element.

[0026] An embodiment of the present application provides a solar cell, which has a cell sheet. The cell sheet has a light-receiving side and a backlight side that are opposite to each other along the thickness. The light-receiving side is a side for receiving sunlight, and the backlight side is a side away from sunlight.

[0027] like Figure 1 As shown, the cell comprises: a substrate 1, an emitter 2, a tunneling dielectric layer 3, a doped conductive layer 4 and a passivation layer 5, wherein the emitter 2 is arranged on the light-receiving side of the substrate 1, the tunneling dielectric layer 3 is arranged on the backlight side of the substrate 1, the doped conductive layer 4 is arranged on the side of the tunneling dielectric layer 3 away from the substrate 1, and the passivation layer 5 is arranged on the side of the emitter 2 away from the substrate 1, the side of the doped conductive layer 4 away from the substrate 1 and the cutting surface. The cutting surface refers to the surface generated when the cell is cut.

[0028] Specifically, the emitter 2 and the substrate 1 can form a PN junction structure together. The tunneling dielectric layer 3 can serve as a tunneling layer for the majority carriers, and at the same time chemically passivate the substrate 1 to reduce the interface state. The doped conductive layer 4 can form a band bending, realize the selective transmission of carriers, and reduce the recombination loss of carriers. The passivation layer 5 can passivate the surface of the emitter 2 away from the substrate 1, the surface of the doped conductive layer 4 away from the substrate 1, and the cut surface, thereby reducing the recombination speed of the carriers of the emitter 2, the doped conductive layer 4 and the cut surface, and improving the photoelectric conversion efficiency of the solar cell.

[0029] More specifically, the cutting surface has a first pyramid structure, which is composed of a large number of first tower bases with etched tips, so the first pyramid structure can reduce the reflectivity of sunlight irradiated on the cutting surface and increase the solar cell's absorption rate of sunlight. At the same time, the first tower base without a tip is convenient for the formation of the passivation layer 5, and improves the uniformity of passivation of the cutting surface. The substrate 1 has a second pyramid structure on the light-receiving side and a third pyramid structure on the backlight side. The second pyramid structure is composed of a large number of second tower bases with tips, so the second pyramid structure can greatly reduce the reflectivity of sunlight irradiated on the light-receiving side of the cell and increase the solar cell's absorption rate of sunlight; the third pyramid structure is composed of a large number of third tower bases with etched tips, and the size of the third tower base is larger than the size of the first tower base, that is, the flatness of the backlight side of the cell is higher than the flatness of the light-receiving side and the flatness of the cutting surface, so that the internal reflectivity of the backlight side to sunlight is higher, and the solar cell's absorption rate of sunlight is increased again. It can be understood that the size of the second tower base is smaller than the size of the first tower base and the size of the third tower base, so as to ensure that the second pyramid structure can better reduce the reflectivity of sunlight irradiating the light-receiving side of the battery cell.

[0030] The present invention provides a method for manufacturing a solar cell. Figure 1 The solar cell shown. Figure 2As shown, the method for manufacturing a solar cell includes: S1: forming a tunnel dielectric layer 3 and a doped conductive layer 4 on the backlight side of the cell.

[0031] In this step, the tunnel dielectric layer 3 and the doped conductive layer 4 are formed on the third pyramid structure, so the surfaces of the tunnel dielectric layer 3 and the doped conductive layer 4 facing away from the substrate 2 also present a pyramid structure. Optionally, the tunnel dielectric layer 13 and the doped conductive layer 14 are prepared by low pressure chemical vapor deposition (LPCVD) or plasma enhanced chemical vapor deposition (PECVD).

[0032] S2: using a first laser to open a groove 8 on the light-receiving surface or the backlight surface of the cell, the groove 8 is located at both ends of the cell along the cutting direction.

[0033] In this step, if Figure 3 As shown, the two grooves 8 opened by the first laser are located on the same surface of the battery sheet. The first laser can be a nano laser capable of emitting infrared light.

[0034] S3: Cutting the battery cell by the second laser, the first laser and the second laser act on the same side of the battery cell.

[0035] In this step, the second laser first irradiates the laser at the position of one of the grooves 8, and then moves to the position of the other groove 8 along the cutting path. In this process, heat is generated at the laser action position of the second laser. With the change of the laser action position and the superposition of cooling means (for example, spraying coolant to the position where the laser has acted), a temperature gradient is generated on the battery cell. The temperature gradient generates tensile stress, and the tensile stress causes a crack to be formed on the battery cell extending along a predetermined path, thereby achieving the cutting of the battery cell. Among them, the first groove 8 can guide the crack so that the crack extends along the predetermined path, and at the same time preheat the area where the laser spot is about to act, thereby increasing the temperature that can be reached at the laser action position. Since the second laser stops emitting laser at the end of cutting the battery cell, the source of the temperature gradient required for crack expansion disappears, so the second groove 8 can assist the fracture of the end of the battery cell. Fig.11 and Fig.18 A schematic diagram of the structure of a whole battery cell being cut into two half-cells is shown, wherein the dotted line indicates the cutting position.

[0036] S4: Texturing the cut surface of the battery cell to form a first pyramid structure on the cut surface of the battery cell.

[0037] In this step, if Fig.13 As shown, texturing will etch the damaged layer on the cut surface and remove the damaged layer on the cut surface, thereby preventing the presence of the damaged layer from causing higher recombination and lower photoelectric conversion efficiency of the subsequently manufactured solar cells.

[0038] S5: Polishing the cut surface of the battery cell and etching the tip of the first pyramid structure.

[0039] In this step, different tower bases of the first pyramid structure formed by texturing have different heights, which will result in poor flatness of the cut surface. Therefore, the heights of the different tower bases are made close by etching the tip of the first pyramid structure, thereby improving the flatness of the cut surface.

[0040] S6: Passivate the battery cells.

[0041] In this step, if Fig.16 As shown, the passivation layer 5 can be formed on the light-receiving side, the backlight side and the cutting surface of the cell by atomic layer deposition (ALD).

[0042] In this application, if Fig.14 As shown, by etching the tip of the first pyramid structure, the flatness of the cut surface can be improved, which facilitates the growth of the passivation layer 5 on the cut surface, improves the passivation effect of the passivation layer 5 on the cut surface, reduces the recombination of carriers, and thus improves the photoelectric conversion efficiency of the solar cell.

[0043] Specifically, in step S2: a groove 8 is opened on the light-receiving surface or the backlight surface of the battery cell by a first laser, and the power of the laser emitted by the first laser satisfies: 30W~100W.

[0044] For example, the power of the laser emitted by the first laser can be specifically: 30W, 40W, 50W, 60W, 70W, 80W, 90W, 100W, etc. The power of the laser emitted by the first laser should not be too large or too small. If the power of the laser emitted by the first laser is too large (for example, greater than 100W), the power consumption of the first laser is high and the cost increases; if the power of the laser emitted by the first laser is too small (for example, less than 30W), it may not be possible to form the groove 8 on the battery cell. Therefore, the power of the laser emitted by the first laser should be selected within an appropriate range.

[0045] Specifically, in the step of cutting the battery cell by the second laser, the power of the laser emitted by the second laser satisfies: 300W~600W, the spot size of the laser emitted by the second laser satisfies: 1mm~2mm, and the moving speed of the spot satisfies: 500mm / s~800mm / s.

[0046] For example, the power of the laser emitted by the second laser can be specifically: 300W, 350W, 400W, 450W, 500W, 550W, 600W, etc. The power of the laser emitted by the second laser should not be too large or too small. If the power of the laser emitted by the second laser is too large (for example, greater than 600W), the power consumption of the second laser is high and the cost increases; if the power of the laser emitted by the second laser is too small (for example, less than 300W), it may make it difficult to cut the battery cell. Therefore, the power of the laser emitted by the second laser should be selected within an appropriate range.

[0047] For example, the spot size of the laser emitted by the second laser can be 1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.8mm, 1.9mm, 2mm, etc. The spot size of the laser emitted by the second laser should not be too large or too small. If the spot size of the laser emitted by the second laser is too large (for example, greater than 2mm), it is easy to cause damage to the area outside the cutting position on the battery cell; if the spot size of the laser emitted by the second laser is too small (for example, less than 1mm), the spot irradiated on the battery cell is easy to deviate from the cutting position, and the precision requirements of the second laser are relatively high. At the same time, the larger the spot size, the higher the corresponding laser energy. It is difficult for a laser spot of a smaller size to reach a sufficient cutting temperature. Therefore, the spot size of the laser emitted by the second laser should be selected within an appropriate range.

[0048] For example, the moving speed of the light spot can be specifically: 500 mm / s, 550 mm / s, 600 mm / s, 650 mm / s, 700 mm / s, 750 mm / s, 800 mm / s, etc. The moving speed of the light spot should not be too fast or too slow. If the moving speed of the light spot is too fast (for example, greater than 800 mm / s), the action time of the light spot at each position is short, the temperature rise at the cell cutting position is small, and it is difficult to cut the cell; if the moving speed of the light spot is too slow (for example, less than 500 mm / s), it takes a long time to cut a cell, and the cutting efficiency of the cell is low. Therefore, the moving speed of the light spot should be selected within an appropriate range.

[0049] Further, such as Fig.10 As shown, before step S1: forming a tunnel dielectric layer 3 and a doped conductive layer 4 on the backlight side of the cell, the method for manufacturing a solar cell further includes: S7: texturing the substrate 1.

[0050] In this step, if Figure 4As shown, the texturing of the substrate 1 is to form an undulating, uneven velvet structure on the light-receiving side and the backlight side of the cell, that is, the second pyramid structure of the substrate 1 on the light-receiving side and the third pyramid structure on the backlight side, so as to reduce the reflection of sunlight by the manufactured solar cell, improve the absorption rate of sunlight by the manufactured solar cell, and further improve the photoelectric conversion efficiency of the solar cell. Among them, the height of the second tower base of the second pyramid structure meets the requirements of: 1μm ~ 2μm, and the size of the bottom of the second tower base meets the requirements of: 1μm ~ 2μm.

[0051] S8: Diffusion of boron into the battery cell.

[0052] In this step, if Figure 5 As shown, the cell is placed in a diffusion furnace to allow boron atoms to enter the cell, forming a PN junction structure on the cell, and at the same time forming a borosilicate glass layer 6 on the surface of the cell.

[0053] S9: Oxidizing the light-receiving side of the cell.

[0054] In this step, if Figure 6 As shown, the thickness of the borosilicate glass layer 6 on the light-receiving side of the cell increases to improve the protection effect of the borosilicate glass layer 6 on the pyramid structure on the light-receiving side. Preferably, the borosilicate glass layer 6 on the light-receiving side of the cell is 100nm to 200nm thicker than the borosilicate glass layer 6 on the backlight side.

[0055] S10: removing the borosilicate glass layer 6 on the backlight side and the side surfaces of the cell.

[0056] In this step, if Figure 7 As shown, the removal of the borosilicate glass layer 6 on the backlight side of the cell is achieved by chain cleaning.

[0057] S11: polishing the backlight side of the cell to etch the tip of the third pyramid structure.

[0058] In this step, if Figure 8 As shown, the flatness of the polished third pyramid structure is improved, which can make the tunnel dielectric layer 3 and the doped conductive layer 4 formed thereon have a higher flatness, thereby improving the internal reflection of the solar cell to the sunlight, increasing the utilization rate of the solar cell to the sunlight, and further improving the photoelectric conversion efficiency of the solar cell.

[0059] Specifically, after polishing the backlight side of the cell, the size of the upper surface of the third tower base of the third pyramid structure satisfies: 5μm~20μm. For example, the size of the upper surface of the third tower base can be 5μm, 8μm, 10μm, 12μm, 15μm, 18μm, 20μm, etc.

[0060] The size of the upper surface of the third tower base should not be too large or too small. If the size of the upper surface of the third tower base is too large (for example, greater than 20 μm), in step S11: polishing the backlight side of the cell, a large part of the cell is etched away, and the loss of the cell is large, which increases the cost of producing solar cells; if the size of the upper surface of the third tower base is too small (for example, greater than 5 μm), the flatness of the backlight side of the cell will be reduced, the internal reflection of sunlight will be reduced, and the photoelectric conversion efficiency of the solar cell will be affected. Therefore, the size of the upper surface of the third tower base should be controlled within an appropriate range.

[0061] Furthermore, in step S1: when forming the tunnel dielectric layer 3 and the doped conductive layer 4 on the backlight side of the cell, as Fig. 9 As shown, a tunnel dielectric layer 3 and a doped conductive layer 4 are also formed on the light-receiving side of the cell, and a phosphosilicate glass layer 7 is formed on the side of the doped conductive layer 4 facing away from the substrate on both the light-receiving side and the backlight side.

[0062] like Fig.17 As shown, in step S4: after texturing the cut surface of the cell, the method for manufacturing a solar cell further includes: S12: Chain cleaning is performed on the cell to remove the phosphorus-silicate glass layer 7 on the light-receiving side of the cell.

[0063] In this step, if Fig.12 and Fig.13 As shown, the phosphosilicate glass layer 7 on the backlight side of the cell is retained, so that when step S4: texturing the cut surface of the cell is performed, the phosphosilicate glass layer 7 on the backlight side of the cell protects the tunneling dielectric layer 3 and the doped conductive layer 4 on the backlight side, and the tunneling dielectric layer 3 and the doped conductive layer 4 on the light-receiving side of the cell are etched. Therefore, after step S4: texturing the cut surface of the cell, the light-receiving side of the cell only has the emitter 2 and the borosilicate glass layer 6, and the backlight side has the tunneling dielectric layer 3, the doped conductive layer 4 and the phosphosilicate glass layer 7.

[0064] Specifically, in step S4: texturing the cut surface of the cell, the cell is etched to a depth of 5 μm to 10 μm. For example, the cell may be etched to a depth of 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc.

[0065] The depth of the cell etching should not be too large or too small. If the cell etching depth is too large (for example, greater than 10μm), the cell will be damaged; if the cell etching depth is too small (for example, less than 5μm), the damaged layer formed by cutting the cell may not be completely removed. Therefore, the cell etching depth should be selected within an appropriate range.

[0066] Specifically, step S4: texturing the cut surface of the battery cell includes: The battery cell is placed in a texturing tank, which contains at least an alkaline solvent and a texturing additive.

[0067] The battery cell is transferred from the texturing tank to the first cleaning tank, and the first cleaning tank can clean the alkaline solvent and texturing additives remaining on the battery cell.

[0068] The volume ratio of the alkaline solvent to the texturing additive in the texturing tank satisfies 1:1 to 15:1. For example, the volume ratio of the alkaline solvent to the texturing additive in the texturing tank can be 1:1, 2:1, 5:1, 8:1, 10:1, 12:1, 14:1, 15:1, etc.

[0069] The volume ratio of the alkaline solvent and the texturing additive in the texturing tank should not be too large or too small. If the volume ratio of the alkaline solvent and the texturing additive in the texturing tank is too large (for example, greater than 15:1), the content of the texturing additive in the texturing tank is small, and it is difficult to form the first pyramid structure; if the volume ratio of the alkaline solvent and the texturing additive in the texturing tank is too small (for example, greater than 1:1), the content of the alkaline solvent in the texturing tank is small, and it is difficult to completely remove the damaged layer formed by cutting the battery cell. Therefore, the volume ratio of the alkaline solvent and the texturing additive in the texturing tank should be selected within an appropriate range.

[0070] More specifically, step S5: polishing the cut surface of the cell includes: placing the battery cell into a polishing tank, wherein the polishing tank contains at least an alkaline solvent and a polishing additive; The battery cell is transferred from the texturing tank to the second cleaning tank, and the second cleaning tank can clean the alkaline solvent and polishing additives remaining on the battery cell.

[0071] The volume ratio of the alkaline solvent to the polishing additive in the polishing tank satisfies: 1.25: 1 to 15: 1. For example, the volume ratio of the alkaline solvent to the polishing additive in the polishing tank can be 1.25: 1, 2: 1, 5: 1, 8: 1, 10: 1, 12: 1, 14: 1, 15: 1, etc.

[0072] The volume ratio of the alkaline solvent and the polishing additive in the polishing tank should not be too large or too small. If the volume ratio of the alkaline solvent and the polishing additive in the polishing tank is too large (for example, greater than 15:1), the content of the polishing additive in the polishing tank is small, and it is difficult to etch the tip of the first pyramid structure; if the volume ratio of the alkaline solvent and the polishing additive in the polishing tank is too small (for example, less than 1.25:1), the content of the polishing additive in the polishing tank is large, and the first pyramid structure is etched too much. Therefore, the volume ratio of the alkaline solvent and the polishing additive in the polishing tank should be selected within an appropriate range.

[0073] Further, step S4: texturing the cut surface of the battery cell to form a first pyramid structure on the cut surface of the battery cell, the reaction temperature is: 60℃~80℃, and the reaction time is: 300s~800s; step S5: polishing the cut surface of the battery cell and etching the tip of the first pyramid structure, the reaction temperature is: 60℃~80℃, and the reaction time is: 100s~200s.

[0074] When texturing and polishing the cut surface of the cell, the reaction temperature should not be too high or too low. If the reaction temperature is too high (for example, higher than 60°C), the energy consumption required to heat the texturing tank and the polishing tank is high, and the cost increases; if the reaction temperature is too low (for example, lower than 60°C), the speed of texturing and polishing will be affected. It is understandable that the reaction time for texturing the cut surface of the cell can be adjusted according to the actual situation, and the reaction time for polishing the cut surface of the cell can be adjusted according to the actual situation.

[0075] Furthermore, in step S5: after polishing the cut surface of the battery cell, the first pyramid structure has a first tower base, and the size of the upper surface of the first tower base satisfies: 0.5μm~2μm, and / or, the height of the first tower base satisfies: 0.5μm~1.5μm. For example, the size of the upper surface of the first tower base can be 0.5μm, 0.6μm, 0.8μm, 1.0μm, 1.2μm, 1.5μm, 1.8μm, 1.9μm, 2.0μm, etc., and the height of the first tower base can be 0.5μm, 0.8μm, 0.9μm, 1.0μm, 1.2μm, 1.4μm, 1.5μm, etc.

[0076] The size of the upper surface of the first tower base should not be too large or too small. If the size of the upper surface of the first tower base is too small (for example, less than 0.5 μm), the tip of the first tower base is etched too little, and the flatness of the cut surface is poor, which is not conducive to the growth of the passivation layer 5 on the cut surface and affects the passivation effect on the cut surface. If the size of the upper surface of the first tower base is too large (for example, greater than 2 μm), the first tower base is etched too much, and the first pyramid structure is basically damaged by etching, and the reflectivity of sunlight irradiated on the cut surface cannot be reduced.

[0077] The height of the first tower base should not be too large or too small. If the height of the first tower base is too large (for example, greater than 1.5 μm), the flatness of the cut surface will be poor, which is not conducive to the growth of the passivation layer 5 on the cut surface and affects the passivation effect on the cut surface. If the height of the first tower base is too small (for example, greater than 1.5 μm), the first pyramid structure is basically etched and damaged, and the reflectivity of sunlight irradiated on the cut surface cannot be reduced.

[0078] In addition, if Fig.15 and Fig.17As shown, in step S5: after polishing the cut surface of the cell, the light-receiving side of the cell still has the phosphorus-silicate glass layer 7, and the backlight side still has the phosphorus-silicate glass layer 7. Therefore, in step S5: after polishing the cut surface of the cell, the method for manufacturing a solar cell further includes: S13: removing the borosilicate glass layer 6 on the light-receiving side of the cell and the phosphosilicate glass layer 7 on the backlight side.

[0079] Specifically, the cell may be cleaned with a cleaning solution containing hydrofluoric acid to remove the borosilicate glass layer 6 and the phosphosilicate glass layer 7 .

[0080] Through this step, when the cell is passivated in step S6 , the passivation layer 5 can be formed on the side of the emitter 2 away from the substrate 1 , the side of the doped conductive layer 4 away from the substrate 1 , and the cut surface.

[0081] In the above embodiment, in step S2: a groove 8 is opened on the light-receiving surface or the backlight surface of the battery cell by a first laser, and an angle is formed between the laser light emitted by the first laser and the light-receiving surface or the backlight surface of the battery cell, so that an angle is formed between the extension direction of the groove 8 and the light-receiving surface or the backlight surface, thereby guiding the battery cell to crack in a direction inclined relative to the thickness direction of the battery cell.

[0082] In step S3 : in cutting the cell by the second laser, an angle is formed between the laser light emitted by the second laser and the light receiving surface or the backlight surface of the cell, so that the cell is cut in a direction inclined relative to the thickness direction of the cell.

[0083] It can be understood that the angle between the laser emitted by the second laser and the light-receiving surface or backlight surface of the cell is the same as or close to the angle between the laser emitted by the first laser and the light-receiving surface or backlight surface of the cell, so as to ensure that the cell is cut along the preset tilt angle.

[0084] like Fig.18 and Fig.19 As shown, there is an angle between the cutting surface of the cell and the thickness direction of the cell. The material of the substrate 1 is generally single crystal silicon or polycrystalline silicon. The structural characteristics of silicon crystal are: there are three different crystal directions. Cutting along the vertical thickness direction of the cell will expose dangling bonds in three directions. The angle between the cutting surface and the thickness direction of the cell can reduce the exposed dangling bonds, thereby reducing the carrier recombination of the produced solar cell at the cutting surface, and improving the photoelectric conversion efficiency of the solar cell.

[0085] Specifically, the angle between the cut surface of the cell and the thickness direction of the cell satisfies: 30°~60°. For example, the angle may be: 30°, 35°, 40°, 45°, 50°, 55°, 60°, etc. If the angle between the cut surface of the cell and the thickness direction of the cell is too large or too small (for example, greater than 60°, less than 30°), the exposed dangling bonds will increase, and the carrier recombination of the produced solar cell at the cut surface will increase.

[0086] Furthermore, after the cell is passivated in step S6, the method for manufacturing a solar cell further includes: forming an anti-reflection film on the backlight side of the cell, printing electrodes, sintering, electrical injection and sorting.

[0087] The anti-reflection film is located on the side of the emitter 2 away from the substrate 1, which can reduce the reflection of sunlight, improve the utilization rate of sunlight by the solar cell, and thus improve the photoelectric conversion efficiency of the cell. Specifically, the anti-reflection film mainly includes: one or more film layers of silicon nitride, silicon oxynitride, and silicon oxide.

[0088] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for manufacturing a solar cell, characterized in that: The solar cell has a cell sheet, and the cell sheet has a light-receiving side and a backlight side facing each other along the thickness. The manufacturing method of the solar cell includes: Forming a tunneling dielectric layer (3) and a doped conductive layer (4) on the backlight side of the cell; Using a first laser to open a groove (8) on the light-receiving surface or the backlight surface of the cell, the groove (8) being located at two ends of the cell along the cutting direction; Cutting the battery sheet by a second laser, wherein the first laser and the second laser act on the same side of the battery sheet; Performing texturing on the cut surface of the battery cell so as to form a first pyramid structure on the cut surface of the battery cell; Polishing the cut surface of the cell and etching the tip of the first pyramid structure; The battery cell is passivated.

2. The method for manufacturing a solar cell according to claim 1, characterized in that: In the step: a groove (8) is opened in the light-receiving surface or the backlight surface of the cell by using a first laser, wherein an angle is formed between the laser light emitted by the first laser and the light-receiving surface or the backlight surface of the cell; And / or, in the step of cutting the battery cell by using a second laser, an angle is formed between the laser light emitted by the second laser and the light-receiving surface or the backlight surface of the battery cell.

3. The method for manufacturing a solar cell according to claim 1, characterized in that: In the step: a groove (8) is opened in the light-receiving surface or the backlight surface of the cell by using a first laser, wherein the power of the laser emitted by the first laser satisfies: 30W-100W.

4. The method for manufacturing a solar cell according to claim 1, characterized in that: In the step of cutting the battery cell by a second laser, the power of the laser emitted by the second laser satisfies: 300W~600W, the spot size of the laser emitted by the second laser satisfies: 1mm~2mm, and the moving speed of the spot satisfies: 500mm / s~800mm / s.

5. The method for manufacturing a solar cell according to claim 1, characterized in that: In step: after polishing the cut surface of the battery cell, the first pyramid structure has a first tower base, and the size of the upper surface of the first tower base satisfies: 0.5μm~2μm, and / or the height of the first tower base satisfies: 0.5μm~1.5μm.

6. The method for manufacturing a solar cell according to claim 1, characterized in that: Step: Texturing the cut surface of the cell comprises: Putting the battery cell into a texturing tank, wherein the texturing tank contains at least an alkaline solvent and a texturing additive; Transferring the battery cell from the texturing tank to a first cleaning tank; Wherein, the volume ratio of the alkaline solvent and the texturing additive in the texturing tank satisfies: 1:1-15:

1.

7. The method for manufacturing a solar cell according to claim 1, characterized in that: Step: Polishing the cut surface of the cell comprises: Placing the battery cell into a polishing tank, wherein the polishing tank contains at least an alkaline solvent and a polishing additive; Transferring the battery cell from the texturing tank to a second cleaning tank; Wherein, the volume ratio of the alkaline solvent and the polishing additive in the polishing tank satisfies: 1.25:1~15:

1.

8. The method for manufacturing a solar cell according to claim 1, characterized in that: Step: texturing the cut surface of the battery cell to form a first pyramid structure on the cut surface of the battery cell, the reaction temperature is 60° C. to 80° C., and the reaction time is 300 s to 800 s; And / or, step: polishing the cut surface of the battery cell, etching the tip of the first pyramid structure, the reaction temperature is: 60° C.~80° C., and the reaction time is: 100s~200s.

9. A solar cell, characterized in that: The solar cell is manufactured by the method for manufacturing a solar cell according to any one of claims 1 to 8; The battery cell comprises: A substrate (1), wherein the substrate (1) has a second pyramid structure on the light-receiving side and a third pyramid structure on the backlight side; An emitter (2), the emitter (2) being arranged on the light receiving side of the substrate (1); A tunneling dielectric layer (3), the tunneling dielectric layer (3) being arranged on the backlight side of the substrate (1); A doped conductive layer (4), the doped conductive layer (4) being arranged on a side of the tunnel dielectric layer (3) away from the substrate (1); A passivation layer (5), the passivation layer (5) being arranged on a side of the emitter (2) away from the substrate (1), a side of the doped conductive layer (4) away from the substrate (1), and the cut surface.

10. The solar cell according to claim 9, characterized in that: An angle between the cutting surface of the battery cell and the thickness direction of the battery cell satisfies: 30°~60°.

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