A method of manufacturing a solar cell and a solar cell

Abstract

The application relates to a manufacturing method of a solar cell and the solar cell, the back surface of the solar cell has a first area and a second area, and a second electrode of the solar cell is arranged in the second area; the manufacturing method of the solar cell comprises the following steps: etching the cell piece; diffusing boron to the cell piece; laser etching the first area; groove cleaning the first area; and chain cleaning the second area. In the application, the back surface of the cell piece is selectively etched by laser, so that the borosilicon glass layer of the first area is removed, the borosilicon glass layer of the second area is reserved, the first area of the cell piece is cleaned and polished in subsequent preparation steps, the borosilicon glass layer of the second area protects the texture structure of the second area in subsequent preparation steps, the tunneling medium layer and the doped conductive layer in the second area also have the texture structure, and therefore the contact area of the second electrode and the doped conductive layer is increased, 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 particularly relates to a manufacturing method of a solar cell and the solar cell. BACKGROUND

[0002] The solar cell can directly convert solar radiation energy into electric energy, and is mainly based on the photovoltaic effect of crystalline silicon, that is, when the light quantum of sunlight is absorbed by the semiconductor crystalline silicon, an electron-hole pair is generated, and when the electron-hole pair reaches the p-n junction composed of p-type crystalline silicon and n-type crystalline silicon, the electron-hole pair is separated by the junction electric field to the two sides of the p-n junction, and when an external load is connected, a photoelectric current is formed, and electric energy is output.

[0003] In order to improve the passivation effect and internal reflection effect of the back of the existing solar cell, the texture structure of the back of the cell is removed, so that the contact resistance between the electrode on the back of the cell and the cell body is large, which affects the photoelectric conversion efficiency of the solar cell. SUMMARY

[0004] The present application provides a manufacturing method of a solar cell and the solar cell, and aims to solve the technical problem that the contact resistance between the electrode on the back of the cell and the cell body is large, which affects the photoelectric conversion efficiency of the solar cell.

[0005] The manufacturing method of the solar cell provided by the present application is provided, and the back of the solar cell has a first region and a second region, and the electrode of the solar cell is arranged on the second region.

[0006] The manufacturing method of the solar cell comprises the following steps.

[0007] Texturing is performed on the cell piece.

[0008] Boron diffusion is performed on the cell piece.

[0009] The first region is laser etched.

[0010] Groove cleaning is performed on the first region.

[0011] Chain cleaning is performed on the second region.

[0012] In a possible design, in the step of laser etching the first region, the power of laser etching is 40W-60W.

[0013] In a possible design, in the step of laser etching the first region, the speed of laser etching is 40m / s-70m / s.

[0014] In a possible design, after the step of performing chain etching on the second region, the manufacturing method of the solar cell further comprises the following steps.

[0015] forming a tunneling dielectric layer and a doped conductive layer on the back surface of the cell.

[0016] In a possible design, in the step of forming a tunneling dielectric layer and a doped conductive layer on the back surface of the cell, a deposition time t of the doped conductive layer satisfies: 1500s≤t≤1800s.

[0017] The solar cell is prepared by the manufacturing method of the solar cell.

[0018] The solar cell includes a substrate, an emitter, a tunneling dielectric layer and a doped conductive layer, the emitter is arranged on the front surface of the substrate, and the tunneling dielectric layer and the doped conductive layer are sequentially arranged on the back surface of the substrate.

[0019] In a possible design, the flatness of the doped conductive layer in the second region is less than the flatness in the first region.

[0020] In a possible design, the flatness of the tunneling dielectric layer in the second region is less than the flatness in the first region.

[0021] In a possible design, the flatness of the back surface of the substrate in the second region is less than the flatness in the first region.

[0022] In a possible design, a thickness d of the doped conductive layer satisfies: 110nm≤d≤130nm.

[0023] In the present application, the back surface of the cell is selectively etched by laser to remove the borosilicate glass layer in the first region and retain the borosilicate glass layer in the second region, so that the first region of the cell is cleaned and polished in subsequent preparation steps, thereby making the passivation effect of the back surface of the cell better, the recombination of the back surface of the cell less, and the internal reflection of the back surface of the cell enhanced, the utilization rate of sunlight increased, and meanwhile, the borosilicate glass layer in the second region of the cell can protect the textured structure of the second region in subsequent preparation steps, so that the tunneling dielectric layer and the doped conductive layer in the second region also have the textured structure, thereby increasing the contact area of the second electrode and the doped conductive layer and reducing the resistance at the contact between the second electrode and the doped conductive layer, and further improving the photoelectric conversion efficiency of the solar cell.

[0024] It should be understood that the general description above and the detailed description below are only exemplary and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Flow chart of the manufacturing method of the solar cell provided in the present application;

[0026] Figure 2 Structure diagram of the solar cell provided in the present application in a specific embodiment;

[0027] Figure 3 Structure diagram of the cell piece not processed in the flow chart of Figure 1

[0028] Figure 4 Structure diagram of the cell piece after texturing in the flow chart of Figure 3

[0029] Structure diagram of the cell piece after boron diffusion in the flow chart of Figure 5 Figure 4 Structure diagram of the cell piece after laser etching in the flow chart of

[0030] Figure 6 Figure 5 Structure diagram of the cell piece after chain cleaning in the flow chart of

[0031] Figure 7 Structure diagram of the cell piece after forming the tunneling medium layer and the doped conductive layer on the back surface in the flow chart of Figure 6

[0032] Structure diagram of the cell piece after etching the glass produced on the front surface in the flow chart of Figure 8 Figure 7 Structure diagram of the cell piece after forming the passivation layer on the front surface and the back surface in the flow chart of

[0033] Figure 9 Figure 8

[0034] Figure 10 Figure 9 Reference signs:

[0035] 1 - solar cell;

[0036] 1a - second region;

[0037] 11 - substrate;

[0038] 12 - emitter;

[0039] 13 - tunneling medium layer;

[0040] 14 - doped conductive layer;

[0041] 15 - first passivation layer;

[0042] ​​​​​​​​

[0043] 16 - second passivation layer.

[0044] 17 - first electrode;

[0045] 18 - second electrode.

[0046] The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate embodiments consistent with the application and serve to explain the principles of the application. DETAILED DESCRIPTION

[0047] For a better understanding of the technical solutions of the present application, the embodiments of the present application are described in detail below with reference to the drawings.

[0048] It should be clear that the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0049] The terms used in the embodiments of the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0050] It should be understood that the term "and / or" used herein is only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0051] It should be noted that the "up", "down", "left", "right" and other directional words described in the embodiments of the present application are described from the angle shown in the drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it should also be understood that when referring to an element connected to another element "on" or "under", it can not only be directly connected to another element "on" or "under", but also indirectly connected to another element "on" or "under" through an intermediate element.

[0052] The embodiments of the present application provide a solar cell, such as Figure 1As shown, the solar cell 1 includes a substrate 11, an emitter 12, a tunneling dielectric layer 13, and a doped conductive layer 14. The emitter 12 is disposed on the front side of the substrate 11, and the tunneling dielectric layer 13 and the doped conductive layer 14 are disposed sequentially on the back side of the substrate 11. The front side of the substrate 11 refers to the surface of the substrate 11 facing the light-receiving side of the solar cell 1, and the back side of the substrate 11 refers to the surface of the substrate 11 facing the back-lighting side of the solar cell 1.

[0053] The substrate 11 and the emitter 12 can together form a PN junction structure. The tunneling dielectric layer 13 can serve as a tunneling layer for majority carriers, while simultaneously chemically passivating the substrate 11 to reduce interface states. The doped conductive layer 14 can form band bending, enabling selective carrier transport and reducing carrier recombination losses.

[0054] A first passivation layer 15 is disposed on the side of the emitter 12 facing away from the substrate 11, passivating the surface of the emitter 12 facing away from the substrate 11. A second passivation layer 16 is disposed on the side of the doped conductive layer 14 facing away from the substrate 11, passivating the surface of the doped conductive layer 14 facing away from the substrate 11. This reduces the recombination velocity of charge carriers in the emitter 12 and the doped conductive layer 14, thereby improving the photoelectric conversion efficiency of the solar cell 1. Furthermore, the solar cell 1 also includes a first electrode 17 connected to the emitter 12 and a second electrode 18 connected to the doped conductive layer 14.

[0055] like Figure 1 As shown, the back side of the solar cell 1 has a first region and a second region 1a. The second region 1a is provided with a second electrode 18. The width of the second region 1a is greater than the width of the second electrode 18, so that the second electrode 18 can be located within the second region 1a. The first region is the area on the back side of the solar cell 1 other than the second region 1a.

[0056] Furthermore, the flatness of the doped conductive layer 14 in the second region 1a is less than that in the first region; that is, the doped conductive layer 14 is less flat in the second region 1a and more flat in the first region. The less flatness of the doped conductive layer 14 in the second region 1a increases the contact area between the second electrode 18 and the doped conductive layer 14, reducing the resistance at the contact point. The more flatness of the doped conductive layer 14 in the first region increases its internal reflection of sunlight, increasing the utilization rate of solar energy and thus improving the photoelectric conversion efficiency of the solar cell 1.

[0057] The flatness of the tunneling dielectric layer 13 in the second region 1a is less than that in the first region, that is, the part of the tunneling dielectric layer 13 in the second region 1a is relatively uneven, and the part of the tunneling dielectric layer 13 in the first region is relatively flat. The uneven degree of the tunneling dielectric layer 13 in the second region 1a is close to the uneven degree of the doped conductive layer 14 in the second region 1a, so that the thickness of the part of the tunneling dielectric layer 13 and the doped conductive layer 14 in the second region 1a is relatively uniform. The part of the tunneling dielectric layer 13 in the first region is relatively flat, so that the passivation effect of the tunneling dielectric layer 13 on the substrate 11 is better, and the internal reflection of the tunneling dielectric layer 13 to sunlight is increased, which is beneficial to improve the photoelectric conversion efficiency of the solar cell 1.

[0058] The flatness of the second passivation layer 16 in the second region 1a is less than that in the first region, that is, the part of the second passivation layer 16 in the second region 1a is relatively uneven, and the part of the second passivation layer 16 in the first region is relatively flat, so that the thickness of the second passivation layer 16 as a whole is relatively uniform, and the passivation effect on the doped conductive layer 14 is better.

[0059] Further, the flatness of the substrate 11 in the second region 1a is less than that in the first region, that is, the part of the substrate 11 in the second region 1a is relatively uneven, and the part of the substrate 11 in the first region is relatively flat. The part of the substrate 11 in the second region 1a is relatively uneven, which can facilitate the deposition of the relatively uneven tunneling dielectric layer 13, doped conductive layer 14 and second passivation layer 16 in the second region 1a in turn; the part of the substrate 11 in the first region is relatively flat, which can facilitate the deposition of the relatively flat tunneling dielectric layer 13, doped conductive layer 14 and second passivation layer 16 in the first region in turn.

[0060] Specifically, the substrate 11 can be an N-type substrate or a P-type substrate. The N-type substrate mainly includes a silicon substrate, and the N-type substrate is further doped with an N-type element, which can be a pentavalent element such as phosphorus element, arsenic element or antimony element. The P-type substrate mainly includes a silicon substrate, and the P-type substrate is further doped with a P-type element, which can be a trivalent element such as boron element, indium element or gallium element.

[0061] The embodiment of the present application also provides a manufacturing method of a solar cell, as shown in Figure 2 Taking the TopCon cell of the N-type substrate as an example, the manufacturing method of the solar cell 1 includes the following steps:

[0062] S1: Texturing the cell piece.

[0063] In this step, as shown in Figure 3 and Figure 4As shown, texturing is the process of creating an undulating, uneven textured surface on the light-receiving and back-light-receiving surfaces of the solar cell to reduce the reflection of sunlight by the manufactured solar cell 1, increase the absorption rate of sunlight by the manufactured solar cell 1, and thus improve the photoelectric conversion efficiency of the solar cell 1.

[0064] S2: Boron diffusion is performed on the solar cells.

[0065] In this step, such as Figure 5 As shown, the solar cell is placed in a diffusion furnace to allow boron atoms to enter the solar cell, forming a PN junction structure on the solar cell, while a borosilicate glass layer is formed on the surface of the solar cell.

[0066] S3: Laser etching of the first region.

[0067] In this step, such as Figure 6 As shown, a high-power laser can be used to etch and remove the borosilicate glass layer in the first region, while selectively retaining the borosilicate glass layer in the second region 1a. Laser etching has the advantages of high precision, good etching uniformity, and high surface flatness after etching.

[0068] S4: Perform tank cleaning on the first area.

[0069] In this step, the tank cleaning process removes surface contaminants such as oxide layers from the solar cell in the first region, removes damage caused by laser etching in the first region, and partially polishes the solar cell in the first region. The borosilicate glass layer in the second region 1a protects the textured surface of the second region 1a from damage during the tank cleaning process.

[0070] S5: Perform chain cleaning on the second region 1a.

[0071] In this step, such as Figure 7 As shown, chain cleaning can remove the borosilicate glass layer in the second region 1a.

[0072] S6: A tunneling dielectric layer 13 and a doped conductive layer 14 are formed on the back side of the solar cell.

[0073] In this step, such as Figure 8As shown, the tunneling dielectric layer 13 and the doped conductive layer 14 can be prepared by a Low Pressure Chemical Vapor Deposition (LPCVD) method or a Plasma Enhanced Chemical Vapor Deposition (PECVD) method. Since the first region is relatively flat, the tunneling dielectric layer 13 and the doped conductive layer 14 formed on the first region are also relatively flat; since the second region la has a textured structure, the tunneling dielectric layer 13 and the doped conductive layer 14 formed on the second region la also have a textured structure. In addition, as shown, during the process of forming the tunneling dielectric layer 13 and the doped conductive layer 14 on the back surface of the cell sheet, the front surface of the cell sheet will also form a sputtered polysilicon and a phosphosilicate glass layer. In order to prevent the sputtered polysilicon and the phosphosilicate glass layer from affecting the performance of the solar cell 1, it is necessary to remove them. Figure 9

[0074] S7: Forming a passivation layer on the front surface and the back surface of the cell sheet.

[0075] In this step, as shown, the passivation layer can be formed on the front surface and the back surface of the cell sheet by an Atomic Layer Deposition (ALD) method. The passivation layer deposited on the front surface of the cell sheet is a first passivation layer 15, and the passivation layer deposited on the back surface of the cell sheet is a second passivation layer 16. Since the first region of the back surface of the cell sheet is relatively flat, the second passivation layer 16 formed on the first region is also relatively flat; since the second region la of the back surface of the cell sheet has a textured structure, the second passivation layer 16 formed on the second region la also has a textured structure. Specifically, the passivation layer is generally an aluminum oxide layer. Figure 10

[0076] S8: Screen printing electrodes on the cell sheet and performing sintering.

[0077] In this step, the electrode printed on the front surface of the cell sheet is a first electrode 17, and the electrode printed on the back surface of the cell sheet is a second electrode 18. The electrode includes a fine grid and a main grid, the fine grid is used to collect the current generated on the cell sheet, and the main grid is used to collect the current in the fine grid. High-temperature sintering of the electrode can form a good ohmic contact between the electrode and the cell.

[0078] ​​In the embodiment, the back surface of the cell sheet is selectively etched by laser to remove the borosilicate glass layer of the first region and retain the borosilicate glass layer of the second region 1a, so that the first region of the cell sheet is cleaned and polished in subsequent preparation steps, and the passivation effect of the back surface of the cell sheet is better, the recombination of the back surface of the cell sheet is less, and the internal reflection of the back surface of the cell sheet is enhanced, the utilization rate of sunlight is increased, and the borosilicate glass layer of the second region 1a of the cell sheet can protect the textured structure of the second region 1a in subsequent preparation steps, so that the tunneling medium layer 13 and the doped conductive layer 14 in the second region 1a also have a textured structure, thereby increasing the contact area of the second electrode 18 and the doped conductive layer 14, reducing the resistance at the contact between the second electrode 18 and the doped conductive layer 14, and further improving the photoelectric conversion efficiency of the solar cell 1.

[0079] Specifically, the tank cleaning equipment at least includes: a first cleaning tank, a first water washing tank, a polishing tank, a second water washing tank, a second cleaning tank, a third water washing tank, a third cleaning tank, a fourth water washing tank, and a first drying tank.

[0080] The first cleaning tank contains an alkaline solution which can react with the surface oxide layer of the cell sheet but cannot react with borosilicate glass, so the first cleaning tank will not etch the second region 1a. Optionally, the alkaline solution can be a potassium hydroxide solution. The first water washing tank is used to remove the residual alkaline solution in the first cleaning tank on the cell sheet. The polishing tank can chemically polish the cell sheet. The second water washing tank is used to remove the residual solution in the polishing tank on the cell sheet. The second cleaning tank also contains an alkaline solution which can remove the oxides, grease and impurities attached to the cell sheet, and also remove the solution in the polishing tank that cannot be washed off the cell sheet by the second water washing tank. The third water washing tank is used to remove the residual alkaline solution in the second cleaning tank on the cell sheet. The third cleaning tank contains an acidic solution which can further remove the grease and impurities attached to the cell sheet, and also remove the solution in the second cleaning tank that cannot be washed off the cell sheet by the third water washing tank. The fourth water washing tank is used to remove the residual acidic solution in the third cleaning tank on the cell sheet. The first drying tank is used to dry the moisture on the cell sheet.

[0081] Specifically, the equipment for chain cleaning at least includes a fourth cleaning tank, a fifth water washing tank and a second drying tank. The fourth cleaning tank contains a hydrofluoric acid solution which can react with borosilicate glass to remove the borosilicate glass layer of the second region 1a on the cell sheet. The fifth cleaning tank is used to remove the residual hydrofluoric acid solution in the fourth cleaning tank on the cell sheet. The second drying tank is used to dry the moisture on the cell sheet.

[0082] Further, in the step S3: laser etching the first region, the power of laser etching is: 40W-60W. For example, the power of laser etching can be specifically 40W, 43W, 45W, 48W, 50W, 52W, 55W, 57W, 60W, etc.

[0083] The power of laser etching should not be too large or too small. If the power of laser etching is too small (for example, less than 40W), it will result in slower laser etching speed and lower efficiency, and even cause etching failure. If the power of laser etching is too large (for example, greater than 40W), it will result in larger etching thickness and greater damage to the battery piece. Therefore, the power of laser etching should be selected within an appropriate range.

[0084] Further, in the step S3: laser etching the first region, the speed of laser etching is: 40m / s-70m / s. For example, the speed of laser etching can be specifically: 40m / s, 45m / s, 48m / s, 50m / s, 53m / s, 58m / s, 60m / s, 64m / s, 67m / s, 70m / s, etc.

[0085] The speed of laser etching should not be too fast or too slow. If the speed of laser etching is too fast (for example, greater than 70m / s), it will reduce the etching uniformity and the surface flatness after etching. If the speed of laser etching is too slow (for example, less than 40m / s), it will increase the time required for laser etching and reduce the efficiency of laser etching. Therefore, the speed of laser etching should be selected within an appropriate range.

[0086] In addition, in the step S3: laser etching the first region, the spot size of laser etching is: 200μm-400μm. For example, the spot size can be specifically: 200μm, 220μm, 245μm, 278μm, 300μm, 329μm, 358μm, 384μm, 400μm, etc.

[0087] The spot size of laser etching should be selected within an appropriate range to make the efficiency of laser etching higher, and the uniformity and flatness of the etched surface better.

[0088] In a specific embodiment, in the step S6: forming a tunneling medium layer 13 and a doped conductive layer 14 on the back surface of the battery piece, the deposition time t of depositing the doped conductive layer 14 satisfies: 1500s≤t≤1800s. For example, the deposition time t can be specifically 1500s, 1530s, 1550s, 1580s, 1600s, 1630s, 1680s, 1700s, 1750s, 1800s, etc.

[0089] The thickness of the doped conductive layer 14 formed can be controlled by controlling the deposition time. The deposition time t for depositing the doped conductive layer 14 should not be too long or too short. If the deposition time t is too long (for example, longer than 1800s), the doped conductive layer 14 obtained by deposition will be too thick, which will increase the parasitic absorption of the doped conductive layer 14 to sunlight, and reduce the photoelectric conversion efficiency of the solar cell 1. If the deposition time t is too short (for example, shorter than 1500s), the doped conductive layer 14 obtained by deposition will be too thin, which will increase the recombination in the doped conductive layer 14 and increase the resistance, and reduce the photoelectric conversion efficiency of the solar cell 1. Therefore, the deposition time t for depositing the doped conductive layer 14 should be selected within an appropriate range.

[0090] Specifically, the thickness d of the doped conductive layer 14 satisfies: 110nm≤d≤130nm. For example, the thickness d of the doped conductive layer can be specifically 110nm, 112nm, 115nm, 118nm, 120nm, 124nm, 128nm, 130nm, etc.

[0091] The thickness d of the doped conductive layer 14 should not be too thick or too thin. If the thickness d of the doped conductive layer 14 is too thick (for example, thicker than 130nm), the parasitic absorption of the doped conductive layer 14 to sunlight will increase, and the photoelectric conversion efficiency of the solar cell 1 will decrease. If the thickness d of the doped conductive layer 14 is too thin (for example, thinner than 110nm), the recombination in the doped conductive layer 14 will increase, and the resistance will increase, and the photoelectric conversion efficiency of the solar cell 1 will decrease. Therefore, the thickness d of the doped conductive layer 14 should be controlled within an appropriate range.

[0092] In addition, since the surface flatness of the first region after laser etching on the cell sheet is high, the film color difference of the solar cell 1 caused by the non-uniform deposition thickness of the tunneling medium layer 13 and the doped conductive layer 14 can be improved.

[0093] In a specific embodiment, the ratio of the width of the second region 1a to the width of the second electrode 18 satisfies: 5~15. For example, the ratio of the width of the second region 1a to the width of the second electrode 18 can be 5, 6.5, 8, 9, 10.5, 12, 13, 14.5, 15, etc.

[0094] The ratio of the width of the second region 1a to the width of the second electrode 18 should be selected within an appropriate range, so that the contact area of the second electrode 18 and the doped conductive layer 14 is larger, the resistance at the contact between the two is smaller, and at the same time, the size of the first region is as large as possible, so that the passivation effect of the back surface of the cell sheet is better, the recombination on the back surface of the cell sheet is less, the internal reflection effect of the back surface of the cell sheet is stronger, the utilization rate of sunlight is increased, and the photoelectric conversion efficiency of the solar cell 1 is higher.

[0095] Preferably, the width of the second electrode 18 satisfies 15 μm to 35 μm, and the width of the second region la satisfies 150 μm to 350 μm.

[0096] The preferred embodiments of the present application only and are not intended to limit the present application. The present application can have various changes and modifications, which should be included in the scope of the present application for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the present application.

Claims

1. A method for manufacturing a solar cell, characterized by, The back surface of the solar cell (1) has a first region and a second region (1a), and a second electrode (18) of the solar cell (1) is arranged in the second region (1a); The manufacturing method of the solar cell (1) comprises: Texturing the cell sheet, and forming a textured structure on the back surface of the cell sheet; Boron diffusion is performed on the cell sheet, and a borosilicate glass layer is formed on the surface of the cell sheet; Laser etching the first region to remove the borosilicate glass layer of the first region, and retaining the borosilicate glass layer of the second region; Groove cleaning is performed on the first region to polish the first region, and the borosilicate glass layer of the second region protects the textured structure of the second region; Chain cleaning is performed on the second region (1a) to remove the borosilicate glass layer of the second region.

2. The method for manufacturing a solar cell according to claim 1, wherein In the step of laser etching the first region, the power of laser etching is 40W-60W.

3. The method for manufacturing a solar cell according to claim 1, wherein In the step of laser etching the first region, the speed of laser etching is 40m / s-70m / s.

4. The method for manufacturing a solar cell according to claim 1, wherein After the step of chain etching the second region (1a), the manufacturing method of the solar cell (1) further comprises: forming a tunneling medium layer (13) and a doped conductive layer (14) on the back surface of the cell sheet.

5. The method of manufacturing a solar cell according to claim 4, wherein In the step of forming a tunneling medium layer (13) and a doped conductive layer (14) on the back surface of the cell sheet, the deposition time t of the doped conductive layer (14) satisfies: 1500s≤t≤1800s.

6. A solar cell, characterized by The solar cell (1) is prepared by the manufacturing method of the solar cell according to any one of claims 1-5; the back surface of the solar cell (1) has a first region and a second region (1a), and the second region (1a) is provided with a second electrode (18); The solar cell (1) comprises a substrate (11), an emitter (12), a tunneling medium layer (13), and a doped conductive layer (14), wherein the emitter (12) is arranged on the front surface of the substrate (11), and the tunneling medium layer (13) and the doped conductive layer (14) are sequentially arranged on the back surface of the substrate (11).

7. The solar cell according to claim 6, characterized in that, The flatness of the doped conductive layer (14) in the second region (1a) is less than that in the first region.

8. The solar cell of claim 6, wherein, The flatness of the tunneling medium layer (13) in the second region (1a) is less than that in the first region.

9. The solar cell of claim 6, wherein, The flatness of the back surface of the substrate (11) in the second region (1a) is less than that in the first region.

10. The solar cell of claim 6, wherein, The thickness d of the doped conductive layer (14) satisfies: 110nm≤d≤130nm.

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