A method for manufacturing a solar cell and a solar cell

Abstract

The application relates to a solar cell manufacturing method and a solar cell. The solar cell has a cell piece, the cell piece has a light-receiving side and a back light side opposite to each other along the thickness, and the solar cell manufacturing method comprises the following steps: forming a tunneling medium layer and a doped conductive layer on the back light side of the cell piece; opening grooves on the light-receiving surface or the back light surface of the cell piece by a first laser, the grooves are located at two ends of the cell piece along a cutting direction; cutting the cell piece by a second laser, the first laser and the second laser act on the same side of the cell piece; etching the cutting surface of the cell piece to form a first pyramid structure on the cutting surface of the cell piece; polishing the cutting surface of the cell piece to etch the tip of the first pyramid structure; and passivating the cell piece. In the application, the damage layer on the cutting surface is removed by etching, and the flatness of the cutting surface is improved by polishing, so that the recombination of 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 the entire 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 subsequent processes, 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 comprises a cell, wherein the cell has a light-receiving side and a light-receiving side facing each other along the thickness. The method for manufacturing the solar cell comprises:

[0006] forming a tunneling dielectric layer and a doped conductive layer on the backlight side of the cell;

[0007] Using a first laser, a groove is formed on the light-receiving surface or the backlight surface of the cell, wherein the groove is located at both ends of the cell along the cutting direction;

[0008] Cutting the cell by a second laser, wherein the first laser and the second laser act on the same side of the cell;

[0009] Texturing the cut surface of the battery cell to form a first pyramid structure on the cut surface of the battery cell;

[0010] polishing the cut surface of the cell and etching the tip of the first pyramid structure;

[0011] The battery cell is passivated.

[0012] In one 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, 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 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 cell.

[0013] In a possible design, in step: a groove is opened in the light-receiving surface or the backlight surface of the cell by using a first laser, and the power of the laser emitted by the first laser satisfies: 30W~100W.

[0014] In one 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.

[0015] In one 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 meets the following requirements: 0.5 μm~2 μm, and / or the height of the first base meets the following requirements: 0.5 μm~1.5 μm.

[0016] In one possible design, the step of texturing the cut surface of the cell includes:

[0017] Putting the battery cell into a texturing tank, wherein the texturing tank contains at least an alkaline solvent and a texturing additive;

[0018] Transferring the cell from the texturing tank to a first cleaning tank;

[0019] Wherein, the volume ratio of the alkaline solvent to the texturing additive in the texturing tank satisfies: 1:1-15:1.

[0020] In one possible design, the step of polishing the cut surface of the cell includes:

[0021] Placing the battery cell into a polishing tank, wherein the polishing tank contains at least an alkaline solvent and a polishing additive;

[0022] Transferring the cell from the texturing tank to a second cleaning tank;

[0023] Wherein, the volume ratio of the alkaline solvent to the polishing additive in the polishing tank satisfies: 1.25:1~15:1.

[0024] 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.

[0025] In a possible design, the steps include: texturing the cell to form a first pyramid structure on a cut surface of the cell, wherein the reaction temperature is 60° C. to 80° C., and the reaction time is 300 s to 800 s;

[0026] 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.

[0027] 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:

[0028] a substrate having a second pyramid structure on the light-receiving side and a third pyramid structure on the backlight side;

[0029] an emitter, the emitter being disposed on the light-receiving side of the substrate;

[0030] a tunneling dielectric layer, the tunneling dielectric layer being disposed on the backlight side of the substrate;

[0031] a doped conductive layer, the doped conductive layer being disposed on a side of the tunnel dielectric layer away from the substrate;

[0032] A passivation layer is provided 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.

[0033] In a possible design, an angle between the cut surface of the cell and the thickness direction of the cell satisfies: 30° to 60°.

[0034] In the present application, the second laser first irradiates the laser at the position of one of the grooves, and then moves along the cutting path to the position of the other groove. During this process, heat is generated at the laser action position of the second laser. As the laser action position changes and the cooling means are superimposed (for example, spraying coolant at the position where the laser has acted), a temperature gradient is generated on the cell. The temperature gradient generates tensile stress, and the tensile stress causes a crack to form on the cell that extends 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, while preheating 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 in the fracture of the end of the cell. 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 the subsequent solar cell to have a high recombination and 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 carrier recombination, and thus improves the photoelectric conversion efficiency of the solar cell.

[0035] It should be understood that the foregoing general description and the following detailed description are merely illustrative and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic structural diagram of a solar cell provided in this application in a specific embodiment;

[0037] Figure 2 A flow chart of the method for manufacturing a solar cell provided in this application;

[0038] Figure 3 A schematic diagram of the structure of a cell after the step of: using a first laser to create a groove on the light-receiving surface or the backlight surface of the cell;

[0039] Figure 4 This is a schematic diagram of the structure of the battery cell before and after texturing the substrate;

[0040] Figure 5 The schematic diagram of the structure of the cell before and after boron diffusion is performed on the cell.

[0041] Figure 6 The schematic diagram of the structure of the cell before and after the light-receiving side of the cell is oxidized is shown in the following steps:

[0042] Figure 7Schematic diagram of the structure of the cell before and after the step of removing the borosilicate glass layer on the backlight side and side of the cell;

[0043] 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 following steps:

[0044] Figure 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.

[0045] Figure 10 A flow chart of the method for manufacturing a solar cell provided in this application;

[0046] Figure 11 A schematic diagram of the structure of cutting a battery cell in a direction perpendicular to the thickness of the battery cell;

[0047] Figure 12 The schematic diagram of the battery cell before and after chain cleaning is shown in the following steps:

[0048] Figure 13 The schematic diagram of the structure of the cell before and after texturing the cut surface of the cell is shown in the following steps:

[0049] Figure 14 The schematic diagram of the structure of the cell before and after polishing the cut surface of the cell is shown in the following steps:

[0050] Figure 15 Schematic diagram of the structure of the cell before and after the step of removing the borosilicate glass layer on the light-receiving side and the phosphosilicate glass layer on the backlight side;

[0051] Figure 16 The schematic diagram of the structure of the battery cell before and after passivation is performed.

[0052] Figure 17 A flow chart of the method for manufacturing a solar cell provided in this application;

[0053] Figure 18 A schematic diagram of the structure of cutting a battery cell along the thickness direction of the inclined battery cell;

[0054] Figure 19 This is a schematic structural diagram of another specific embodiment of the solar cell provided in this application.

[0055] Reference numerals:

[0056] 1-base;

[0057] 2-Emitter;

[0058] 3- tunneling dielectric layer;

[0059] 4- doped conductive layer;

[0060] 5-passivation layer;

[0061] 6- borosilicate glass layer;

[0062] 7-phosphosilicate glass layer;

[0063] 8-Grooves.

[0064] 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

[0065] 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.

[0066] It should be clear that the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0067] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "an", "the" 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 otherwise.

[0068] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0069] 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 based on 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 should be understood that when it is mentioned that an element is connected to another element "on" or "under", it can not only be directly connected to the other element "on" or "under", but also be indirectly connected to the other element "on" or "under" through an intermediate element.

[0070] An embodiment of the present application provides a solar cell, which has a cell. The cell has a light-receiving side and a backlight side facing each other along the thickness. The light-receiving side is the side for receiving sunlight, and the backlight side is the side away from sunlight.

[0071] like Figure 1 As shown, the cell includes: a substrate 1, an emitter 2, a tunneling dielectric layer 3, a doped conductive layer 4, and a passivation layer 5. 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.

[0072] Specifically, the emitter 2 and substrate 1 can jointly form a PN junction structure. The tunneling dielectric layer 3 can serve as a tunneling layer for majority carriers while chemically passivating the substrate 1 to reduce interface states. The doped conductive layer 4 can form band bending, enabling selective carrier transport and reducing carrier recombination losses. 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 velocity of carriers between the emitter 2, the doped conductive layer 4, and the cut surface, thereby improving the photoelectric conversion efficiency of the solar cell.

[0073] More specifically, the cut surface has a first pyramid structure, which is composed of a large number of first tower bases with etched tips. Therefore, the first pyramid structure can reduce the reflectivity of sunlight irradiated on the cut surface and increase the solar cell's absorptivity of sunlight. At the same time, the first tower bases without tips facilitate the formation of the passivation layer 5, improving the uniformity of passivation on the cut 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. Therefore, 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 absorptivity of sunlight. The third pyramid structure is composed of a large number of third tower bases with etched tips. The size of the third tower base is larger than that of the first tower base. That is, the flatness of the backlight side of the cell is higher than that of the light-receiving side and the flatness of the cut surface, resulting in a higher internal reflectivity of sunlight on the backlight side, further increasing the solar cell's absorptivity of sunlight. 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 solar cell.

[0074] The present invention provides a method for manufacturing a solar cell. Figure 1 The solar cell shown. Figure 2 As shown, the method for manufacturing a solar cell includes:

[0075] S1: forming a tunnel dielectric layer 3 and a doped conductive layer 4 on the backlight side of the cell.

[0076] In this step, the tunneling dielectric layer 3 and the doped conductive layer 4 are formed on the third pyramid structure, so that the surfaces of the tunneling dielectric layer 3 and the doped conductive layer 4 facing away from the substrate 2 also have a pyramid structure. Optionally, the tunneling dielectric layer 13 and the doped conductive layer 14 are formed using low-pressure chemical vapor deposition (LPCVD) or plasma-enhanced chemical vapor deposition (PECVD).

[0077] S2: using a first laser to create 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.

[0078] In this step, if Figure 3 As shown, the two grooves 8 opened by the first laser are located on the same side of the cell. The first laser can be a nano laser capable of emitting infrared light.

[0079] S3: Cutting the cell by the second laser, the first laser and the second laser act on the same side of the cell.

[0080] In this step, the second laser first irradiates the laser at the position of one of the grooves 8, and then moves along the cutting path to the position of the other groove 8. During this process, heat is generated at the laser action position of the second laser. As the laser action position changes and the cooling means are superimposed (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 form on the battery cell that extends 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. Therefore, the opening of the second groove 8 can assist in the fracture of the end of the battery cell. Figure 11 and Figure 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.

[0081] S4: Texturing the cut surface of the battery cell to form a first pyramid structure on the cut surface of the battery cell.

[0082] In this step, if Figure 13As 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.

[0083] S5: Polish the cut surface of the cell and etch the tip of the first pyramid structure.

[0084] In this step, the heights of different tower bases of the first pyramid structure formed by texturing are different, 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.

[0085] S6: Passivate the battery cells.

[0086] In this step, if Figure 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).

[0087] In this application, if Figure 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.

[0088] Specifically, in step S2: a groove 8 is opened on the light-receiving surface or the backlight surface of the cell by using a first laser, and the power of the laser emitted by the first laser satisfies: 30W~100W.

[0089] For example, the power of the laser light emitted by the first laser can be 30W, 40W, 50W, 60W, 70W, 80W, 90W, 100W, etc. The power of the laser light emitted by the first laser should be neither too high nor too low. If the power of the laser light emitted by the first laser is too high (for example, greater than 100W), the power consumption of the first laser will be high, and the cost will increase. If the power of the laser light emitted by the first laser is too low (for example, less than 30W), it may be impossible to form the groove 8 on the solar cell. Therefore, the power of the laser light emitted by the first laser should be selected within an appropriate range.

[0090] Specifically, in the step of cutting the battery cell by the second laser, the power of the laser emitted by the second laser meets the following requirements: 300W~600W, the spot size of the laser emitted by the second laser meets the following requirements: 1mm~2mm, and the moving speed of the spot meets the following requirements: 500mm / s~800mm / s.

[0091] For example, the power of the laser light emitted by the second laser can be 300W, 350W, 400W, 450W, 500W, 550W, 600W, etc. The power of the laser light emitted by the second laser should be neither too high nor too low. If the power of the laser light emitted by the second laser is too high (for example, greater than 600W), the power consumption of the second laser will be high, and the cost will increase. If the power of the laser light emitted by the second laser is too low (for example, less than 300W), it may make it difficult to cut the solar cells. Therefore, the power of the laser light emitted by the second laser should be selected within an appropriate range.

[0092] For example, the spot size of the laser light 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 light emitted by the second laser should be neither too large nor too small. If the spot size of the laser light emitted by the second laser is too large (for example, larger than 2mm), it is easy to damage areas outside the cutting position on the cell. If the spot size of the laser light emitted by the second laser is too small (for example, smaller than 1mm), the spot light irradiated on the cell is easy to deviate from the cutting position, requiring higher precision from the second laser. At the same time, the larger the spot size, the higher the corresponding laser energy. A smaller laser spot size makes it difficult to achieve a sufficient cutting temperature. Therefore, the spot size of the laser light emitted by the second laser should be selected within an appropriate range.

[0093] For example, the specific moving speed of the light spot can be: 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 be neither too fast nor too slow. If the moving speed of the light spot is too fast (for example, greater than 800 mm / s), the light spot's action time 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 cell cutting efficiency is low. Therefore, the moving speed of the light spot should be selected within an appropriate range.

[0094] Further, such as Figure 10 As shown, before step S1: forming the tunnel dielectric layer 3 and the doped conductive layer 4 on the backlight side of the cell, the method for manufacturing a solar cell further includes:

[0095] S7: texturing the substrate 1 .

[0096] In this step, if Figure 4As shown, texturing the substrate 1 forms an undulating, uneven velvet structure on the light-receiving and backlight-receiving sides of the cell, namely, a second pyramid structure on the light-receiving side and a third pyramid structure on the backlight side of the substrate 1. This reduces the reflection of sunlight from the solar cell, increases the absorption rate of sunlight from the solar cell, and thereby improves the photoelectric conversion efficiency of the solar cell. The height of the second base of the second pyramid structure satisfies the following requirements: 1μm to 2μm, and the size of the bottom of the second base satisfies the following requirements: 1μm to 2μm.

[0097] S8: Diffusion of boron into the cell.

[0098] 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 forming a borosilicate glass layer 6 on the surface of the cell.

[0099] S9: Oxidize the light-receiving side of the cell.

[0100] In this step, if Figure 6 As shown, the thickness of the borosilicate glass layer 6 on the light-receiving side of the cell is increased 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-200nm thicker than the borosilicate glass layer 6 on the backlight side.

[0101] S10: Remove the borosilicate glass layer 6 on the backlight side and side surfaces of the cell.

[0102] In this step, if Figure 7 As shown, the borosilicate glass layer 6 on the backlight side of the cell is removed by chain cleaning.

[0103] S11: Polishing the backlight side of the cell to etch the tip of the third pyramid structure.

[0104] 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 higher flatness, thereby improving the internal reflection of sunlight by the solar cell, increasing the utilization rate of sunlight by the solar cell, and further improving the photoelectric conversion efficiency of the solar cell.

[0105] Specifically, after polishing the backlight side of the cell, the size of the top surface of the third base of the third pyramid structure satisfies the following requirements: 5 μm to 20 μm. For example, the size of the top surface of the third base can be 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, etc.

[0106] The dimensions of the top surface of the third tower base should be neither too large nor too small. If the top surface of the third tower base is too large (for example, greater than 20 μm), a large portion of the cell will be etched away during polishing the backlight side of the cell in step S11, resulting in significant cell loss and increased solar cell production costs. If the top 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, reducing internal reflection of sunlight and affecting the photovoltaic conversion efficiency of the solar cell. Therefore, the dimensions of the top surface of the third tower base should be controlled within an appropriate range.

[0107] Furthermore, in step S1: forming the tunnel dielectric layer 3 and the doped conductive layer 4 on the backlight side of the cell, as shown in FIG. Figure 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.

[0108] like Figure 17 As shown, after step S4: texturing the cut surface of the cell, the method for manufacturing a solar cell further includes:

[0109] S12: Chain cleaning is performed on the cell to remove the phosphorus-silicate glass layer 7 on the light-receiving side of the cell.

[0110] In this step, if Figure 12 and Figure 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, while 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.

[0111] 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 can be etched to a depth of 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc.

[0112] The depth of the cell etching should be neither too deep nor too shallow. If the cell etching depth is too deep (for example, greater than 10μm), the cell will be damaged. If the cell etching depth is too shallow (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.

[0113] Specifically, step S4: texturing the cut surface of the cell includes:

[0114] The battery cell is placed in a texturing tank, which contains at least an alkaline solvent and a texturing additive.

[0115] The battery cells are transferred from the texturing tank to the first cleaning tank, which can clean the residual alkaline solvent and texturing additives on the battery cells.

[0116] 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.

[0117] The volume ratio of the alkaline solvent to the texturing additive in the texturing tank should be neither too large nor too small. If the volume ratio is too large (for example, greater than 15:1), the content of the texturing additive in the tank is too low, making it difficult to form the first pyramid structure. If the volume ratio is too small (for example, greater than 1:1), the content of the alkaline solvent in the tank is too low, making it difficult to completely remove the damaged layer formed by cutting the solar cell. Therefore, the volume ratio of the alkaline solvent to the texturing additive in the texturing tank should be selected within an appropriate range.

[0118] More specifically, step S5: polishing the cut surface of the cell includes:

[0119] placing the cell into a polishing tank containing at least an alkaline solvent and a polishing additive;

[0120] The battery cells are transferred from the texturing tank to the second cleaning tank, which can clean the residual alkaline solvent and polishing additives on the battery cells.

[0121] 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.

[0122] The volume ratio of the alkaline solvent to the polishing additive in the polishing tank should be neither too large nor too small. If the volume ratio of the alkaline solvent to the polishing additive in the polishing tank is too large (for example, greater than 15:1), the polishing additive content in the polishing tank is low, making it difficult to etch the tip of the first pyramid structure. If the volume ratio of the alkaline solvent to the polishing additive in the polishing tank is too small (for example, less than 1.25:1), the polishing additive content in the polishing tank is high, and the first pyramid structure is etched to an excessive extent. Therefore, the volume ratio of the alkaline solvent to the polishing additive in the polishing tank should be selected within an appropriate range.

[0123] Furthermore, 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.

[0124] The reaction temperature for texturing and polishing the cut surfaces of the cell should be neither too high nor too low. If the reaction temperature is too high (for example, above 60°C), the energy consumption required to heat the texturing and polishing tanks will be high, increasing costs. If the reaction temperature is too low (for example, below 60°C), the texturing and polishing speeds will be affected. It is understood that the reaction time for texturing and polishing the cut surfaces of the cell can be adjusted according to actual conditions, and the reaction time for polishing the cut surfaces of the cell can be adjusted according to actual conditions.

[0125] Furthermore, in step S5: 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. For example, the size of the upper surface of the first 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 base can be 0.5μm, 0.8μm, 0.9μm, 1.0μm, 1.2μm, 1.4μm, 1.5μm, etc.

[0126] 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.

[0127] The height of the first tower base should be neither too large nor 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 damaged by etching and cannot reduce the reflectivity of sunlight irradiated on the cut surface.

[0128] In addition, if Figure 15 and Figure 17 As shown, after step S5: 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, after step S5: polishing the cut surface of the cell, the solar cell manufacturing method further includes:

[0129] 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.

[0130] 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 .

[0131] 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 cutting surface.

[0132] In the above embodiment, in step S2: a groove 8 is opened on the light-receiving surface or the backlight surface of the 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 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 cell to crack in a direction inclined relative to the thickness direction of the cell.

[0133] In step S3 , when the cell is cut 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 along a direction inclined relative to the thickness direction of the cell.

[0134] 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.

[0135] like Figure 18 and Figure 19As shown, the cut surface of the cell forms an angle with the thickness direction of the cell. The substrate 1 is generally made of monocrystalline or polycrystalline silicon. Silicon crystals have three distinct crystal orientations. Cutting perpendicular to the thickness of the cell exposes dangling bonds in three directions. The angle between the cut surface and the thickness direction of the cell reduces the exposure of dangling bonds, thereby reducing carrier recombination at the cut surface of the produced solar cell and improving the photovoltaic conversion efficiency of the solar cell.

[0136] Specifically, the angle between the cut surface of the cell and the thickness direction of the cell satisfies the following conditions: 30° to 60°. For example, the angle may be 30°, 35°, 40°, 45°, 50°, 55°, 60°, etc. An angle between the cut surface of the cell and the thickness direction that is too large or too small (e.g., greater than 60°, less than 30°) will increase the number of exposed dangling bonds and increase carrier recombination at the cut surface of the produced solar cell.

[0137] 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.

[0138] The anti-reflection film is located on the side of the emitter 2 facing away from the substrate 1. It 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.

[0139] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for manufacturing a solar cell, characterized in that: The solar cell comprises a cell, wherein the cell has a light-receiving side and a backlight side facing each other along the thickness. The manufacturing method of the solar cell comprises: Texturing the substrate of the cell so that a second pyramid structure is formed on the light-receiving side and a third pyramid structure is formed on the backlight side; Diffusion of boron on the cell to form a borosilicate glass layer (6) on the surface of the cell; Oxidizing the light-receiving side of the cell so that the borosilicate glass layer (6) on the light-receiving side is thicker than the borosilicate glass layer (6) on the backlight side; Removing the borosilicate glass layer (6) on the backlight side; polishing the backlight side and etching the tip of the third pyramid structure; forming a tunneling dielectric layer (3) and a doped conductive layer (4) on the backlight side of the cell; A groove (8) is formed on the light-receiving surface or the backlight surface of the cell by using a first laser, wherein the groove (8) is located at both ends of the cell along the cutting direction; Cutting the cell by a second laser, wherein the first laser and the second laser act on the same side of the cell; Texturing the cut surface of the battery cell 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; passivating the battery cell; The first pyramid structure has a first tower base, the second pyramid structure has a second tower base, and the third pyramid structure has a third tower base. The size of the third tower base is larger than that of the first tower base, and the size of the first tower base is larger than that of the second tower base.

2. The method for manufacturing a solar cell according to claim 1, wherein: 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 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 cell.

3. The method for manufacturing a solar cell according to claim 1, wherein: 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, and 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, wherein: 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, wherein: 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 meets: 0.5μm~2μm, and / or the height of the first base meets: 0.5μm~1.5μm.

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

1.

7. The method for manufacturing a solar cell according to claim 1, wherein: Step: 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; Transferring the cell from the polishing tank to a second cleaning tank; Wherein, the volume ratio of the alkaline solvent to 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, wherein: Step: texturing the cut surface of the cell to form a first pyramid structure on the cut surface of the cell, with a reaction temperature of 60° C. to 80° C. and a reaction time of 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 includes: 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 included angle between the cut surface of the cell and the thickness direction of the cell satisfies: 30°~60°.

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