Preparation method of photovoltaic cell
By simplifying the front etching process of photovoltaic cells, the second alkali washing step was cancelled, and only one alkali washing and two acid washing were performed, the problem of high chemical consumption in the prior art was solved and the photoelectric conversion efficiency was improved.
Patent Information
- Application Number
- CN202311855598.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-29
- Publication Date
- 2025-07-08
AI Technical Summary
In the front etching process of existing TOPCon batteries, chemical consumption is high, process cost is high, and photoelectric conversion efficiency is limited.
In the preparation method of photovoltaic cell cells, the second alkali washing step in the front etching process is omitted, and only one alkali washing and two acid washing are performed, and the process flow is optimized to reduce the use of chemicals and improve the photoelectric conversion efficiency.
By simplifying the process steps, the chemical consumption is significantly reduced, the process time is shortened, and the photoelectric conversion efficiency of photovoltaic cells is improved.
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Figure CN120282564A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of photovoltaic cells, and in particular relates to a method for preparing a photovoltaic cell sheet. Background Art
[0002] With the urgent need for energy replacement, the new energy industry has developed rapidly, and photovoltaics has also ushered in a greater trend. Opportunities and challenges often coexist, and higher photoelectric conversion efficiency has become the focus of the industry. The further improvement of battery efficiency requires more advanced technologies to support it. These technologies are reflected in all aspects of photovoltaic cell manufacturing, requiring each technical point to be better than the others.
[0003] TOPCon (Tunnel Oxide Passivated Contact) cell is a tunnel oxide passivated contact cell based on the principle of selective carriers. It includes a silicon wafer and an ultra-thin tunnel oxide layer and a doped crystalline silicon layer prepared on the back of the silicon wafer. The tunnel oxide layer and the doped crystalline silicon layer together form a passivated contact structure, which can effectively reduce surface recombination and metal contact recombination. Compared with the existing PERC cell, the photoelectric conversion efficiency of the TOP Con cell has greater room for improvement.
[0004] The TOPCon cell of the prior art generally includes processes such as texturing, front boron diffusion, back etching, LPC VD (tunneling oxide layer and polysilicon layer deposition), polysilicon phosphorus diffusion, front etching, double-sided passivation, double-sided metallization, etc. The front etching is the positive etching process, which specifically includes the following steps:
[0005] 1. Remove the polysilicon on the front and edge of the silicon wafer;
[0006] 2. The first alkaline washing is to clean the residual additives on the surface of the silicon wafer;
[0007] 3. The first pickling is to remove the residual alkali solution, front BSG (borosilicate glass) and back PSG (phosphorus silicon glass) on the surface of the silicon wafer;
[0008] 4. The second alkaline wash removes the porous silicon produced on the surface of the silicon wafer;
[0009] 5. The second pickling removes the oxide layer on the surface of the silicon wafer and forms a hydrophobic surface;
[0010] 6. Slowly pull to dehydrate the moisture on the surface of the silicon wafer;
[0011] 7. Dry to remove moisture from the surface of the silicon wafer.
[0012] The conventional etching process requires two acid wash steps and two alkaline wash steps, resulting in high chemical consumption and process costs.
[0013] Therefore, in view of the above technical problems, it is necessary to provide a method for preparing a photovoltaic cell. Summary of the Invention
[0014] In view of this, an object of the present invention is to provide a method for preparing a photovoltaic cell to reduce the process cost of the photovoltaic cell and improve the photoelectric conversion efficiency.
[0015] To achieve the above object, the technical solution provided by an embodiment of the present invention is as follows:
[0016] A method for preparing a photovoltaic cell, the preparation method comprising:
[0017] Preparing a tunneling oxide layer and a doped polycrystalline layer on the back surface of the silicon wafer;
[0018] Performing a de-bypass plating treatment on the silicon wafer to remove the polysilicon layer on the front and side surfaces of the silicon wafer;
[0019] Performing a post-cleaning treatment and a drying treatment on the silicon wafer, and the silicon wafer only undergoes one alkali wash in the post-cleaning treatment.
[0020] In one embodiment, the post-cleaning treatment includes one alkali wash and two acid washes after the alkali wash.
[0021] In one embodiment, the de-bypass plating treatment includes:
[0022] Treating the silicon wafer with a first alkali solution and an additive to remove the polysilicon plated on the front and edges.
[0023] In one embodiment, the post-cleaning treatment includes:
[0024] Alkali wash, washing the de-bypass plated silicon wafer with a second alkali solution to remove the residual additive on the surface of the silicon wafer;
[0025] First acid wash, washing the alkali-washed silicon wafer with a first acid solution to remove the residual second alkali solution, front BSG and back PSG on the surface of the silicon wafer;
[0026] Second acid wash, washing the silicon wafer after the first acid wash with a second acid solution to remove the oxide layer on the surface of the silicon wafer;
[0027] Dehydration, removing the residual moisture on the silicon wafer.
[0028] In one embodiment, the first alkali solution in the de-bypass plating treatment is a NaOH solution, the additive is an additive that promotes the reaction between the alkali and polysilicon, the treatment temperature is 63°C to 73°C, and the treatment time is 240 s to 480 s.
[0029] In one embodiment, the first alkali solution is a NaOH solution with a mass fraction of 40% to 50%; and / or,
[0030] The volume ratio of the first alkali solution to the additive is (20-30):(4-5).
[0031] In one embodiment, the second alkali solution in the alkali washing is a mixed solution of a NaOH solution and a hydrogen peroxide solution. The temperature of the alkali washing is 60°C to 70°C, and the time is 60 s to 180 s.
[0032] In one embodiment, the second alkali solution includes a NaOH solution with a mass fraction of 40%-50%, and the second alkali solution further includes a hydrogen peroxide solution with a mass fraction of 25%-35%; and / or,
[0033] The volume ratio of the NaOH solution to the hydrogen peroxide solution in the second alkali solution is (1-3):(15-25).
[0034] In one embodiment, the first acid solution in the first acid washing is an HF solution. The temperature of the first acid washing is room temperature, and the time is 100 s to 220 s;
[0035] The second acid solution in the second acid washing is an HF solution. The temperature of the second acid washing is room temperature, and the time is 60 s to 180 s.
[0036] In one embodiment, the first acid solution and / or the second acid solution is an HF solution with a mass fraction of 44%-54%; and / or,
[0037] The volume ratio of the first acid solution to the second acid solution is (5-9):(3-7).
[0038] In one embodiment, after the unwinding plating treatment, alkali washing, first acid washing, and second acid washing, it further includes:
[0039] Water washing, cleaning the silicon wafer with pure water.
[0040] In one embodiment, the dehydration includes:
[0041] Slowly and uniformly lifting the silicon wafer out of the pure water by a robotic arm. The lifting speed of the robotic arm is 1 mm / s to 10 mm / s, the temperature is 20°C to 30°C, and the water washing time before dehydration is 10 s to 30 s.
[0042] In one embodiment, the heating temperature in the drying treatment is 90°C to 100°C, and the heating time is 700 s to 900 s.
[0043] The present invention has the following beneficial effects:
[0044] By optimizing the preparation method of photovoltaic cell wafers, the second alkali wash between the first pickling and the second pickling is omitted in the positive etching process, greatly reducing the consumption of chemicals, optimizing the process steps, shortening the process time, and simultaneously improving the photoelectric conversion efficiency of the cells. BRIEF DESCRIPTION OF THE DRAWINGS
[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0046] Figure 1 It is a specific flowchart of the preparation method of photovoltaic cell wafers in the present invention;
[0047] Figure 2 It is a process flowchart of the positive etching process of photovoltaic cell wafers in a comparative example of the present invention;
[0048] Figure 3 It is a process flowchart of the positive etching process of photovoltaic cell wafers in a specific embodiment of the present invention;
[0049] Figure 4a 、 4b They are respectively the front and back morphology diagrams of the silicon wafer after the positive etching process in the comparative example;
[0050] Figure 5a 、 5b They are respectively the front and back morphology diagrams of the silicon wafer after the positive etching process in a specific embodiment of the present invention;
[0051] Figure 6a 、 6b They are respectively the front and back morphology diagrams of the silicon wafer after the anti - plating treatment in a specific embodiment of the present invention;
[0052] Figure 7a 、 7b They are respectively the front and back morphology diagrams of the silicon wafer after the alkali wash in a specific embodiment of the present invention;
[0053] Figure 8a 、 8b They are respectively the front and back morphology diagrams of the silicon wafer after the first pickling in a specific embodiment of the present invention;
[0054] Figure 9a 、 9b They are respectively the front and back morphology diagrams of the silicon wafer after the second pickling in a specific embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0055] To enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.
[0056] As shown Figure 1 the present invention discloses a method for preparing a photovoltaic cell, including:
[0057] Preparing a tunneling oxide layer and a doped polycrystalline layer on the back surface of the silicon wafer;
[0058] Performing a de-bypass plating treatment on the silicon wafer to remove the polysilicon layer on the front and side surfaces of the silicon wafer;
[0059] Performing a post-cleaning treatment and a drying treatment on the silicon wafer, and the silicon wafer only undergoes an alkali wash during the post-cleaning treatment.
[0060] In the present invention, the positive etching process of the photovoltaic cell includes a de-bypass plating treatment, a post-cleaning treatment, and a drying treatment. Among them, the post-cleaning treatment after the de-bypass plating treatment includes an alkali wash and two acid washes after the alkali wash.
[0061] The following will elaborate on each process step of the present invention in detail.
[0062] The preparation of the tunneling oxide layer and the doped polycrystalline layer on the back surface of the silicon wafer belongs to the prior art in the preparation process of TOPCon cells and will not be elaborated here.
[0063] De-bypass plating treatment:
[0064] Treating the silicon wafer with a first alkali solution and an additive to remove the polysilicon bypass-plated on the front and edges.
[0065] The first alkali solution in the de-bypass plating treatment is a NaOH solution, the additive is an additive that promotes the reaction between the alkali and polysilicon, the treatment temperature is 63°C to 73°C, and the treatment time is 240s to 480s; the first alkali solution is a NaOH solution with a mass fraction of 40% to 50%; the volume ratio of the first alkali solution to the additive is (20 to 30):(4 to 5).
[0066] Alkali wash:
[0067] Cleaning the de-bypass plated silicon wafer with a second alkali solution to remove the residual additive on the surface of the silicon wafer.
[0068] The second alkaline solution in the alkaline cleaning is a mixed solution of NaOH solution and hydrogen peroxide solution. The temperature of the alkaline cleaning is 60°C to 70°C, and the time is 60s to 180s. The second alkaline solution includes a NaOH solution with a mass fraction of 40% to 50% and a hydrogen peroxide solution with a mass fraction of 25% to 35%. The volume ratio of the NaOH solution to the hydrogen peroxide solution is (1 to 3):(15 to 25).
[0069] The first acid cleaning:
[0070] The silicon wafers after alkaline cleaning are cleaned with a first acid solution to remove the residual second alkaline solution, front BSG and back PSG on the surface of the silicon wafers.
[0071] The first acid solution in the first acid cleaning is an HF solution. The temperature of the first acid cleaning is room temperature, and the time is 100s to 220s. The first acid solution is an HF solution with a mass fraction of 44% to 54%, and the volume is 50L to 90L.
[0072] The second acid cleaning:
[0073] The second acid solution in the second acid cleaning is an HF solution. The temperature of the second acid cleaning is room temperature, and the time is 60s to 180s. The second acid solution is an HF solution with a mass fraction of 44% to 54%, and the volume is 30L to 70L.
[0074] Furthermore, after the de-wiring plating treatment, alkaline cleaning, first acid cleaning, and second acid cleaning, water washing is performed in sequence, and the silicon wafers are cleaned with pure water.
[0075] Dehydration:
[0076] Remove the residual moisture on the silicon wafers.
[0077] The silicon wafers are slowly and uniformly lifted out of the pure water by a robotic arm. The lifting speed of the robotic arm is 1mm / s to 10mm / s, the temperature is 20°C to 30°C, and the water washing time before dehydration is 10s to 30s.
[0078] Drying treatment:
[0079] The silicon wafers are heated and dried. The heating temperature is 90°C to 100°C, and the heating time is 700s to 900s.
[0080] The present invention will be further described below with specific examples.
[0081] Combined with Figure 2 As shown, the preparation method of a pair of photovoltaic cell wafers in the comparative example of the present invention includes the following steps:
[0082] 1. Prepare a tunneling oxide layer and a doped polycrystalline layer on the back of the silicon wafer.
[0083] 2. Dewiring plating treatment: The silicon wafer is treated with a first alkaline solution and additives to remove the polysilicon plated around the front and edges.
[0084] In the dewiring plating treatment of this comparative example, the first alkaline solution is a NaOH solution with a mass fraction of 45%; the main function of the additive (ADD) is to promote the reaction between the alkali and polysilicon, protect the oxide layer under the polysilicon, and improve the desorption of hydrogen bubbles. The additive can include various components, and mainly the EST-10 additive of Shangneng Photovoltaic Materials Technology Co., Ltd. is used, with a pH value of 7 - 8; the volumes of the first alkaline solution and the additive are 24 L and 4.4 L respectively; the treatment temperature is 68 °C, and the treatment time is 360 s.
[0085] Further, after the dewiring plating treatment, water washing is carried out to clean the silicon wafer with pure water.
[0086] 3. First alkali washing: The silicon wafer after the dewiring plating treatment is washed with a second alkaline solution to remove the residual additives on the surface of the silicon wafer.
[0087] In the first alkali washing of this comparative example, the second alkaline solution is a mixed solution of a NaOH solution with a mass fraction of 45% and a hydrogen peroxide solution with a mass fraction of 30%. The volumes of the NaOH solution and the hydrogen peroxide solution are 2 L and 20 L respectively; the temperature of the first alkali washing is 65 °C, and the time is 120 s.
[0088] Further, after the first alkali washing, water washing is carried out to clean the silicon wafer with pure water.
[0089] 4. First acid washing: The silicon wafer after the first alkali washing is washed with a first acid solution to remove the residual second alkaline solution, front BSG, and back PSG on the surface of the silicon wafer.
[0090] In the first acid washing of this comparative example, the first acid solution is a HF solution with a mass fraction of 49%, and the volume is 70 L; the temperature of the first acid washing is room temperature, and the time is 160 s.
[0091] Further, after the first acid washing, water washing is carried out to clean the silicon wafer with pure water.
[0092] 5. Second alkali washing: The silicon wafer after the first acid washing is washed with a third alkaline solution to remove the porous silicon generated on the surface of the silicon wafer.
[0093] In the second alkali washing of this comparative example, the third alkaline solution is a mixed solution of a NaOH solution with a mass fraction of 45% and a hydrogen peroxide solution with a mass fraction of 30%. The volumes of the NaOH solution and the hydrogen peroxide solution are 2 L and 10 L respectively; the temperature of the second alkali washing is 50 °C, and the time is 100 s.
[0094] Further, after the second alkali wash, a water wash is performed to clean the silicon wafer with pure water.
[0095] 6. Second pickling: The silicon wafer after the second alkali wash is cleaned with a second acid solution to remove the oxide layer on the surface of the silicon wafer and form a hydrophobic surface.
[0096] In the second pickling of this comparative example, the first acid solution is a HF solution with a mass fraction of 49%, and the volume is 50 L; the temperature of the first pickling is room temperature, and the time is 120 s.
[0097] Further, after the second pickling, a water wash is performed to clean the silicon wafer with pure water.
[0098] 7. Dehydration: Remove the residual water on the silicon wafer.
[0099] The silicon wafer is slowly and uniformly lifted out of the pure water by a robotic arm. The lifting speed of the robotic arm is 5 mm / s, the temperature is 25 °C, and the water wash time before dehydration is 20 s;
[0100] 8. Drying treatment: Heat and dry the silicon wafer. The heating temperature is 95 °C, and the heating time is 800 s.
[0101] So far, the positive etching process is completed, and the subsequent preparation process of the photovoltaic cell is continued until printing, testing, sorting, and warehousing.
[0102] The following table shows the chemical composition ratio table of each functional tank in this comparative example.
[0103]
[0104] Refer Figure 1 And in combination with Figure 3 As shown, the method for preparing a photovoltaic cell in an embodiment of the present invention includes the following steps:
[0105] 1. Prepare a tunneling oxide layer and a doped polycrystalline layer on the back of the silicon wafer.
[0106] 2. Dewiring treatment: The silicon wafer is treated with a first alkali solution and an additive to remove the polysilicon wirewound on the front and edges.
[0107] In the dewiring treatment of this comparative example, the first alkali solution is a NaOH solution with a mass fraction of 45%; the main function of the additive (ADD) is to promote the reaction between the alkali and polysilicon, protect the oxide layer under the polysilicon, and improve the desorption of hydrogen bubbles. The additive can include multiple components, and mainly uses the EST-10 additive of Solar Energy Materials Technology Co., Ltd., with a pH value of 7-8; the volumes of the first alkali solution and the additive are 24 L and 4.4 L respectively; the treatment temperature is 68 °C, and the treatment time is 360 s.
[0108] Further, after the stripping plating treatment, water washing is carried out to clean the silicon wafer with pure water.
[0109] The front and back morphology diagrams of the silicon wafer after the stripping plating treatment are respectively as Figure 6a , 6b shown.
[0110] 3. Alkaline washing: The silicon wafer after the stripping plating treatment is cleaned with a second alkaline solution to remove the additives remaining on the surface of the silicon wafer.
[0111] In the alkaline washing of this embodiment, the second alkaline solution is a mixed solution of a NaOH solution with a mass fraction of 45% and a hydrogen peroxide solution with a mass fraction of 30%. The volumes of the NaOH solution and the hydrogen peroxide solution are 2 L and 20 L respectively; the temperature of the alkaline washing is 65 °C and the time is 120 s.
[0112] Further, after the alkaline washing, water washing is carried out to clean the silicon wafer with pure water.
[0113] The front and back morphology diagrams of the silicon wafer after the alkaline washing are respectively as Figure 7a , 7b shown.
[0114] 4. First pickling: The silicon wafer after the alkaline washing is cleaned with a first acid solution to remove the second alkaline solution remaining on the surface of the silicon wafer, the front BSG, and the back PSG.
[0115] In the first pickling of this embodiment, the first acid solution is an HF solution with a mass fraction of 49% and the volume is 70 L; the temperature of the first pickling is room temperature and the time is 160 s.
[0116] Further, after the first pickling, water washing is carried out to clean the silicon wafer with pure water.
[0117] The front and back morphology diagrams of the silicon wafer after the first pickling are respectively as Figure 8a , 8b shown.
[0118] 5. Second pickling: The silicon wafer after the first pickling is cleaned with a second acid solution to remove the oxide layer on the surface of the silicon wafer.
[0119] In the second pickling of this embodiment, the first acid solution is an HF solution with a mass fraction of 49% and the volume is 50 L; the temperature of the first pickling is room temperature and the time is 120 s.
[0120] Further, after the second pickling, water washing is carried out to clean the silicon wafer with pure water.
[0121] The front and back morphology diagrams of the silicon wafer after the second pickling are respectively as Figure 9a , 9b shown.
[0122] 6. Dehydration to remove the residual moisture on the silicon wafer.
[0123] Slowly and uniformly lift the silicon wafer out of pure water by the robotic arm. The lifting speed of the robotic arm is 5 mm / s, the temperature is 25 °C, and the water washing time before dehydration is 20 s.
[0124] 7. Drying treatment: Heat and dry the silicon wafer. The heating temperature is 95 °C, and the heating time is 800 s.
[0125] Thus, the positive etching process ends, and continue to complete the subsequent preparation process of photovoltaic cells until printing, testing, sorting, and warehousing.
[0126] See Figure 4a , 4b Shown are the front and back morphology diagrams of the silicon wafer after the positive etching process in the comparative example. See Figure 5a , 5b Shown are the front and back morphology diagrams of the silicon wafer after the positive etching process in the specific embodiment of the present invention. In the (first) alkali wash, the pyramid texture structure on the back of the silicon wafer is polished to form a pedestal. The pedestal is the base left after the pyramid-shaped texture is polished. The size of the pedestal in this embodiment is about 10 μm - 12 μm. Alkali washing can flatten the surface, reduce the back surface area, greatly improve the back surface reflectivity, enhance the light utilization rate. The flatter the back surface, the better the passivation effect and the higher the open voltage. There is no obvious difference in the appearance of the silicon wafers between the comparative example and the embodiment, and the weight loss difference can be ignored.
[0127] The following table shows the chemical mixture ratio table of each functional tank in this embodiment.
[0128]
[0129] In the first alkali wash in the comparative example, it is mainly to remove the residual additives on the silicon wafer surface. The second alkali wash is mainly to remove the porous silicon generated on the silicon wafer surface. Substantially, the second alkali wash is still to remove the residual additives or other chemicals in the porous silicon. However, the concentration of the chemicals (NaOH and H2O2) in this process has a great influence. If the concentration is too small, it may lead to incomplete cleaning. If the concentration is too large, it will wash away the polysilicon on the back surface, and it is impossible to ensure that the process ends just after removing the porous silicon in the actual process.
[0130] In this embodiment, the second alkali wash in the comparative example is cancelled, and the second acid wash is directly carried out after the first acid wash. In this way, the chemical consumption in the second alkali wash in the comparative example can be saved. In this embodiment, a reduction of H2O2 by 9.33 L / 10,000 wafers and NaOH by 1.03 L / 10,000 wafers can be achieved, greatly reducing the process cost. And in this embodiment, one process is omitted, shortening the process time.
[0131] In addition, by testing the efficiency of the photovoltaic cells prepared in the comparative examples and the examples, it was found that the efficiency of the photovoltaic cells increased rather than decreased after removing the second alkaline wash, and the average efficiency could be increased by about 0.02%.
[0132] It can be seen that the additives remaining in the comparative examples were basically removed by the first alkaline wash. While removing the porous silicon during the second alkaline wash, some polysilicon was also washed away, affecting the performance of the passivated contact structure on the back of the photovoltaic cells, and the loss of performance exceeded the influence of the additives remaining in the porous silicon on the performance.
[0133] It should be understood that in the above embodiments, each step is described with specific chemical ratios, chemical volumes, temperatures, and times. In other embodiments, the chemical ratios, chemical volumes, temperatures, and times are not limited to the specific values in the embodiments. Any solution that omits the second alkaline wash in the comparative examples falls within the scope protected by the present invention. As for different chemical ratios and volumes, they only affect the specific consumption of the chemicals.
[0134] From the above technical solutions, it can be seen that the present invention has the following beneficial effects:
[0135] By optimizing the preparation method of the photovoltaic cells, the present invention omits the second alkaline wash between the first pickling and the second pickling in the positive etching process, greatly reducing the chemical consumption, optimizing the process steps, shortening the process time, and at the same time improving the photoelectric conversion efficiency of the battery.
[0136] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.
[0137] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A method for preparing a photovoltaic cell, characterized in that, The preparation method includes: Preparing a tunneling oxide layer and a doped polycrystalline layer on the back surface of the silicon wafer; Performing a stripping treatment on the silicon wafer to remove the polysilicon layers on the front and side surfaces of the silicon wafer; Performing a post-cleaning treatment and a drying treatment on the silicon wafer, and the silicon wafer only undergoes one alkali wash during the post-cleaning treatment.
2. The preparation method of the photovoltaic cell according to claim 1, wherein The post-cleaning treatment includes one alkali wash and two acid washes after the alkali wash.
3. The preparation method of the photovoltaic cell according to claim 1, characterized in that, The stripping treatment includes: Treating the silicon wafer with a first alkali solution and an additive to remove the polysilicon deposited on the front and edge.
4. The manufacturing method of the photovoltaic cell according to claim 2, characterized in that, The post-cleaning treatment includes: Alkali wash, washing the stripped silicon wafer with a second alkali solution to remove the residual additive on the surface of the silicon wafer; First acid wash, washing the alkali-washed silicon wafer with a first acid solution to remove the residual second alkali solution, the front BSG, and the back PSG on the surface of the silicon wafer; Second acid wash, washing the silicon wafer after the first acid wash with a second acid solution to remove the oxide layer on the surface of the silicon wafer; Dehydration, removing the residual moisture on the silicon wafer.
5. The preparation method of the photovoltaic cell according to claim 3, characterized in that, The first alkali solution in the stripping treatment is a NaOH solution, the additive is an additive that promotes the reaction between the alkali and polysilicon, the treatment temperature is 63°C to 73°C, and the treatment time is 240 s to 480 s.
6. The preparation method of the photovoltaic cell according to claim 5, wherein, The first alkali solution is a NaOH solution with a mass fraction of 40% to 50%; and / or, The volume ratio of the first alkali solution to the additive is (20 to 30):(4 to 5).
7. The manufacturing method of the photovoltaic cell according to claim 4, characterized in that, The second alkali solution in the alkali wash is a mixed solution of a NaOH solution and a hydrogen peroxide solution, the temperature of the alkali wash is 60°C to 70°C, and the time is 60 s to 180 s.
8. The preparation method of the photovoltaic cell according to claim 7, characterized in that, The second alkali solution includes a NaOH solution with a mass fraction of 40% to 50%, and the second alkali solution further includes a hydrogen peroxide solution with a mass fraction of 25% to 35%; and / or, The volume ratio of the NaOH solution to the hydrogen peroxide solution in the second alkali solution is (1 to 3):(15 to 25).
9. The manufacturing method of the photovoltaic cell according to claim 4, wherein, The first acid solution in the first acid wash is an HF solution, the temperature of the first acid wash is room temperature, and the time is 100 s to 220 s; The second acid solution in the second acid wash is an HF solution, the temperature of the second acid wash is room temperature, and the time is 60 s to 180 s.
10. The preparation method of the photovoltaic cell according to claim 9, characterized in that, The first acid solution and / or the second acid solution is an HF solution with a mass fraction of 44% to 54%; and / or, The volume ratio of the first acid solution to the second acid solution is (5 to 9):(3 to 7).
11. The manufacturing method of the photovoltaic cell according to claim 4, characterized in that, After the stripping treatment, the alkali wash, the first acid wash, and the second acid wash, it further includes: Water wash, washing the silicon wafer with pure water.
12. The method for preparing a photovoltaic cell according to claim 11, characterized in that dehydration It includes: Slowly and uniformly lifting the silicon wafer out of the pure water by a robotic arm, the lifting speed of the robotic arm is 1 mm / s to 10 mm / s, the temperature is 20°C to 30°C, and the water wash time before dehydration is 10 s to 30 s.
13. The preparation method of the photovoltaic cell according to claim 1, characterized in that, The heating temperature in the drying treatment is 90°C to 100°C, and the heating time is 700 s to 900 s.