Cleaning method and device for solar cell

Abstract

The embodiment of the invention provides a cleaning method and device for a solar cell, and the method comprises the steps: a polycrystalline silicon removal step: removing a polycrystalline silicon layer wound and plated on the surface of the solar cell through a first alkaline solution; a first washing step: removing the residual first alkaline solution on the surface of the solar cell through pure water; a post-cleaning step: removing impurities on the surface of the solar cell through a second alkaline solution; a second washing step: removing the residual second alkaline solution on the surface of the solar cell through pure water; a first pickling step: removing the borosilicate glass layer on the front surface of the solar cell and the phosphorosilicate glass layer on the back surface of the solar cell through a first acid solution; a third washing step: removing the residual first acid solution on the surface of the solar cell through pure water; a slow pulling step, wherein the solar cell is slowly pulled for pre-dehydration; and a drying step: drying residual water on the surface of the solar cell. According to the technical scheme, the cleaning efficiency of the solar cell can be improved, and the consumption of the cleaning reagent can be reduced.

Description

Technical Field

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

[0002] The photovoltaic industry has ushered in a period of vigorous development, and it is also an era of large-scale production capacity with the update and iteration of battery technology. As the market requirements for component power in photovoltaic terminals are getting higher and higher, the battery cell technology has been innovated. The efficiency of single-crystal PERC (Passivated Emitter and Rear Contact) batteries is close to reaching the limit due to the battery structure. What follows is the comprehensive promotion of more efficient N-type TOPCon (Tunnel Oxide Passivated Contact) batteries. In the production of N-type TOPCon batteries, the front etching RCA cleaning process is a crucial process; the traditional RCA cleaning method has the problem of long cleaning time and low efficiency due to the cumbersome process; in addition, the traditional RCA cleaning method also requires the use of a large amount of chemical reagents and pure water for cleaning operations, which not only increases the cleaning cost, but also has a greater harm to the environment.

[0003] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of patent protection of this application. Summary of the invention

[0004] The embodiments of the present application provide a method and device for cleaning solar cells, which can improve the cleaning efficiency of solar cells and reduce the consumption of cleaning agents while ensuring the yield of solar cells.

[0005] As a first aspect of an embodiment of the present application, an embodiment of the present application provides a cleaning method for a solar cell, comprising:

[0006] The polysilicon removal step is to remove the polysilicon layer on the surface of the solar cell by using a first alkaline solution;

[0007] A first water washing step, removing the first alkaline solution remaining on the surface of the solar cell by pure water;

[0008] a post-cleaning step of removing impurities on the surface of the solar cell by a second alkaline solution;

[0009] A second water washing step, removing the second alkaline solution remaining on the surface of the solar cell by pure water;

[0010] A first pickling step, removing the borosilicate glass layer on the front side and the phosphosilicate glass layer on the back side of the solar cell by using a first acidic solution;

[0011] A third water washing step, removing the first acidic solution remaining on the surface of the solar cell by pure water;

[0012] A slow pulling step, slowly pulling the solar cell to perform pre-dehydration;

[0013] The drying step is to dry the residual water on the surface of the solar cell.

[0014] Optionally, after the first pickling step, the method further comprises:

[0015] Determine whether the borosilicate glass layer on the front side and the phosphosilicate glass layer on the back side of the solar cell are completely removed;

[0016] If yes, then perform the third water washing step;

[0017] If not, the second acid washing step is first performed to remove the borosilicate glass layer on the front side and the phosphosilicate glass layer on the back side of the solar cell by a second acid solution, and then the third water washing step is performed.

[0018] Optionally, the first alkaline solution is an aqueous solution of potassium hydroxide and an additive.

[0019] Optionally, the volume concentration of potassium hydroxide in the first alkaline solution is 3% to 8%, and the volume concentration of the additive is 0.7% to 1.2%;

[0020] The temperature of the first alkaline solution is 67° C. to 73° C., and the process duration of the polysilicon removal step is 450 s to 600 s.

[0021] Optionally, the second alkaline solution is an aqueous solution of potassium hydroxide and hydrogen peroxide.

[0022] Optionally, the volume concentration of potassium hydroxide in the second alkaline solution is 0.7% to 1.1%, and the volume concentration of hydrogen peroxide is 3% to 8%;

[0023] The temperature of the second alkaline solution is 57° C. to 63° C., and the process duration of the post-cleaning step is 150 s to 300 s.

[0024] Optionally, the first acidic solution is an aqueous solution of hydrofluoric acid.

[0025] Optionally, the volume concentration of hydrofluoric acid in the first acidic solution is 18% to 23%;

[0026] The temperature of the first acidic solution is room temperature, and the process duration of the first pickling step is 130s to 300s.

[0027] Optionally, the second acidic solution is: an aqueous solution of hydrofluoric acid;

[0028] Wherein, the volume concentration of hydrofluoric acid in the first acidic solution is greater than the volume concentration of hydrofluoric acid in the second acidic solution.

[0029] Optionally, the volume concentration of hydrofluoric acid in the second acidic solution is 15% to 20%;

[0030] The temperature of the second acidic solution is room temperature, and the process duration of the second pickling step is 90s to 130s.

[0031] As a second aspect of the embodiment of the present application, the embodiment of the present application provides a cleaning device for solar cells, comprising: a polysilicon removal tank group, a first water washing tank, a post-cleaning tank group, a second water washing tank, a first pickling tank group, a third water washing tank, a slow pulling tank, and a drying tank group are arranged in series in the order in which the solar cells pass;

[0032] The polysilicon removal tank group is used to remove the polysilicon layer coated on the surface of the solar cell through the built-in first alkaline solution;

[0033] The first water washing tank is used to remove the first alkaline solution remaining on the surface of the solar cell through built-in pure water;

[0034] The post-cleaning tank group is used to remove impurities on the surface of the solar cell through a built-in second alkaline solution;

[0035] The second water washing tank is used to remove the second alkaline solution remaining on the surface of the solar cell through the built-in pure water;

[0036] The first pickling tank group is used to remove the borosilicate glass layer on the front side and the phosphosilicate glass layer on the back side of the solar cell through the built-in first acid solution;

[0037] The third water washing tank is used to remove the first acidic solution remaining on the surface of the solar cell through built-in pure water;

[0038] The slow pulling tank is used to slowly pull the solar cell through built-in hot water to perform pre-dehydration;

[0039] The drying tank group is used to dry the residual water on the surface of the solar cell.

[0040] Optionally, a second pickling tank is connected in series between the first pickling tank group and the third water washing tank;

[0041] The second pickling tank is used to remove the borosilicate glass layer on the front side and the phosphosilicate glass layer on the back side of the solar cell through a built-in second acid solution.

[0042] Optionally, the polysilicon removal tank group includes: four polysilicon removal tanks connected in parallel;

[0043] The post-cleaning tank group comprises: two post-cleaning tanks connected in parallel;

[0044] The first pickling tank group comprises: two first pickling tanks connected in parallel;

[0045] The drying tank body group comprises six drying tank bodies connected in parallel.

[0046] Optionally, the first alkaline solution in the polysilicon removal tank is an aqueous solution of potassium hydroxide with a volume concentration of 3% to 8% and an additive with a volume solubility of 0.7% to 1.2%;

[0047] The second alkaline solution in the post-cleaning tank is an aqueous solution of potassium hydroxide with a volume concentration of 0.7% to 1.1% and hydrogen peroxide with a volume solubility of 3% to 8%;

[0048] The first acid solution in the first pickling tank is: an aqueous solution of hydrofluoric acid with a volume concentration of 18% to 23%;

[0049] The second acid solution contained in the second pickling tank is an aqueous solution of hydrofluoric acid with a volume concentration of 15% to 20%.

[0050] The above technical solution adopted in the embodiment of the present application may have the following advantages:

[0051] While ensuring that the cleaning effect is not affected, the cleaning time is shortened and the cleaning efficiency is improved by optimizing the RCA cleaning process. In addition, it not only reduces the consumption of chemical reagents, but also reduces the consumption of pure water, thereby reducing pollution to the environment and reducing the cost of external wastewater treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0053] Figure 1 This is an optional flow chart of a solar cell cleaning method provided in an embodiment of the present application;

[0054] Figure 2 This is an optional structural schematic diagram of a solar cell cleaning device provided in an embodiment of the present application;

[0055] Figure 3This is another optional structural schematic diagram of a solar cell cleaning device provided in an embodiment of the present application;

[0056] Figure 4 It is another optional flow chart of the cleaning method for solar cells provided in the embodiment of the present application. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other in the absence of conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0058] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0059] Herein, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers in the numerical interval, including the two endpoint integers of the numerical range, and each integer between the two endpoints, is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows broadly including numerical interval types such as percentage intervals, ratio intervals, and ratio intervals.

[0060] In this article, when it comes to percentage concentration, unless otherwise specified, it refers to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of the component.

[0061] In this article, when it comes to temperature parameters, unless otherwise specified, both constant temperature treatment and treatment within a certain temperature range are allowed. The constant temperature treatment allows the temperature to fluctuate within the accuracy range of instrument control.

[0062] Herein, the term "room temperature" or "normal temperature" generally refers to 4°C to 35°C, for example, 20°C ± 5°C. In some embodiments herein, "room temperature" or "normal temperature" refers to 10°C to 30°C. In some embodiments herein, "room temperature" or "normal temperature" refers to 20°C to 30°C.

[0063] To facilitate those skilled in the art to understand the technical solutions provided in the embodiments of the present application, the relevant technologies are described below:

[0064] The manufacturing process of TOPCon solar cells generally includes: texturing, boron diffusion, BSG (Boro Silicate Glass) + alkali polishing, LPCVD (Low-Pressure Chemical Vapor Deposition), phosphorus diffusion, PSG (Phospho Silicate Glass) + front etching RCA cleaning, ALD (Atomic Layer Deposition), front plating, back plating, screen printing, and finished product inspection.

[0065] In the manufacturing process of TOPCon solar cells, the front and back of the silicon wafer need to be doped during the diffusion stage. At the same time, a certain amount of impurities will inevitably be added to the side of the silicon wafer. When the positive and negative poles of the impurities are turned on, the solar cell will leak electricity. The impurities will also reduce the reflectivity of the TOPCon solar cell, thereby reducing the yield and efficiency of the TOPCon solar cell. In addition, during the manufacturing process of TOPCon solar cells, chemical reagents, metal ion impurities and oxides will remain on their surface, which will also affect the electrical performance parameters of the TOPCon solar cell. Therefore, an RCA cleaning process needs to be added after the diffusion stage; among them, RCA cleaning is also called front etching, that is, the cleaning of the surface of the solar cell after the phosphorus diffusion process.

[0066] At present, the main RCA cleaning method in the industry is: removing polysilicon Poly-water washing-alkali washing-water washing-acid washing-water washing-alkali washing-water washing-acid washing-water washing-slow pulling-drying; however, the whole process has many steps, which can easily lead to an increase in chemical consumption, thereby causing an increase in the manufacturing cost of TOPCon solar cells.

[0067] To this end, the embodiment of the present application provides a cleaning method for solar cells. Based on this, the cleaning efficiency of solar cells can be improved and the consumption of cleaning reagents can be reduced while ensuring the yield of solar cells. See below for details.

[0068] Hereinafter, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. It should be noted that these exemplary embodiments can be implemented in many different forms and should not be construed as being limited to the embodiments described herein.

[0069] In a first aspect, some embodiments of the present application provide a cleaning method for solar cells, which is applied to the process of manufacturing TOPCon solar cells, and the cleaning method is performed after phosphorus diffusion treatment, such as Figure 1 As shown, the cleaning method specifically includes the following steps S101 to S108:

[0070] S101, polysilicon removal step: removing the polysilicon layer coated on the surface of the solar cell by a first alkaline solution.

[0071] In the process of preparing TOPCon solar cells, the polysilicon layer will form a wrap-around coating on the surface of the solar cell, resulting in a decrease in the passivation effect on the front of the solar cell and affecting the conversion efficiency of the cell; in the embodiment of the present application, a wet cleaning method is used to remove the Poly wrap-around coating.

[0072] For example, an alkaline cleaning tank may be used to perform a de-Poly treatment on the solar cell after the phosphorus diffusion treatment, so as to remove the polysilicon layer plated on the surface of the solar cell; the first alkaline solution may be contained in the alkaline cleaning tank.

[0073] The solar cell is placed in a first alkaline solution, which combines with the BSG layer on the front of the solar cell and the PSG layer on the back to form a protective layer. The polysilicon layer on the front and sides of the solar cell reacts with the first alkaline solution to remove part of the polysilicon layer, thereby avoiding conduction of impurities on the side positive and negative electrodes, and further preventing leakage of the TOPCon solar cell.

[0074] S102, first water washing step: removing the first alkaline solution remaining on the surface of the solar cell by pure water.

[0075] For example, a water washing tank may be used to rinse the solar cells after the de-Poly step; the water washing tank may contain pure water (eg, deionized water at room temperature).

[0076] S103, post-cleaning step: removing impurities on the surface of the solar cell by a second alkaline solution.

[0077] In order to improve the cleanliness and conductivity of the solar cell surface, it is also necessary to remove the pollutants and metal impurities remaining on the surface of the solar cell.

[0078] For example, an alkaline cleaning tank can be used to perform post-cleaning treatment on the solar cell after the first water washing step to remove solid particle impurities on the surface of the solar cell produced by the reaction of the first alkaline solution with the polysilicon layer; the second alkaline solution can be contained in the alkaline cleaning tank.

[0079] S104, second water washing step: removing the second alkaline solution remaining on the surface of the solar cell by pure water.

[0080] For example, a water washing tank may be used to rinse the solar cells after the post-cleaning step; the water washing tank may contain pure water (eg, deionized water at room temperature).

[0081] S105, first pickling step: removing the borosilicate glass (BSG) layer on the front side of the solar cell and the phosphosilicate glass (PSG) layer on the back side by using a first acidic solution.

[0082] For example, an acid cleaning tank can be used to clean the solar cell after the second water cleaning step to remove the BSG layer on the front side of the solar cell and the PSG layer on the back side; the first acid solution can be placed in the acid cleaning tank. In addition, the first acid cleaning solution can also neutralize the alkaline solution remaining on the surface of the solar cell, and the hydrofluoric acid in the first acid solution can remove the silicon dioxide layer generated on the surface of the solar cell due to the previous alkaline cleaning.

[0083] S106, third water washing step: removing the first acidic solution remaining on the surface of the solar cell by pure water.

[0084] For example, a water washing tank may be used to rinse the solar cells after the first pickling step; the water washing tank may contain pure water (eg, deionized water at room temperature).

[0085] S107, slow pulling step: slowly pulling the solar cell to perform pre-dehydration.

[0086] For example, a slow pull tank can be used to pre-dehydrate the solar cells after the third water washing step; hot water (for example, 50 degrees Celsius deionized water) can be placed in the slow pull tank; compared with cold water, hot water can better improve the water droplet desorption effect during washing.

[0087] S108, drying step: drying the residual moisture on the surface of the solar cell.

[0088] In the embodiment of the present application, organic matter and other impurities on the surface of the solar cell can be better removed by two alkaline washes, and metal pollution and residual alkaline solution can be removed by acid wash. Compared with the existing RCA cleaning process, the process flow is simplified, the consumption of cleaning reagents is reduced, the cleaning cost is reduced, and the electrical performance of the solar cell can be better improved.

[0089] In addition, a front passivation layer and a back passivation layer are prepared on the solar cell obtained after cleaning in the above steps S101 to S108, and positive and negative metal electrodes are prepared by screen printing and sintering, thereby preparing a TOPCon solar cell.

[0090] In some embodiments, after the first pickling step in S105, the method further includes:

[0091] Determine whether the borosilicate glass (BSG) layer on the front side of the solar cell and the phosphosilicate glass (PSG) layer on the back side are completely removed;

[0092] If yes, then execute the S106, the third water washing step;

[0093] If not, the second acid washing step is first performed to remove the borosilicate glass BSG layer on the front side of the solar cell and the phosphosilicate glass PSG layer on the back side by a second acid solution, and then the S106, third water washing step is performed.

[0094] In practical applications, since one acid wash may not completely remove the BSG layer on the front of the solar cell and the PSG layer on the back, a second acid wash step is required after the first acid wash step to completely remove the BSG layer on the front of the solar cell and the PSG layer on the back. For example, the first acid solution and the second acid solution may both be aqueous solutions containing an inorganic acid, but the volume solubility of the inorganic acid in the first acid solution is greater than the volume concentration of the inorganic acid in the second acid solution.

[0095] In some embodiments, the first alkaline solution is an aqueous solution of potassium hydroxide and an additive.

[0096] Optionally, the volume concentration of potassium hydroxide in the first alkaline solution is 3% to 8%, and the volume concentration of the additive is 0.7% to 1.2%; the temperature of the first alkaline solution is 67°C to 73°C, and the process time of the polysilicon removal step is 450s to 600s; preferably, the volume concentration of potassium hydroxide in the first alkaline solution is 5.2%, and the volume concentration of the additive is 1%; the temperature of the first alkaline solution is 70°C, and the process time of the polysilicon removal step is 450s.

[0097] In these embodiments, since the additive contains a large amount of organic matter, which is easily decomposed at high temperatures, the temperature of the first alkaline solution can be optionally around 70°C to improve the utilization rate of the additive; of course, if the temperature of the first alkaline solution is too low, it is easy to cause the additive to react for too long.

[0098] It should be noted that the concentration of potassium hydroxide in the first alkaline solution, the concentration of the additive, the temperature of the first alkaline solution and the process duration of the de-Poly step can be flexibly adjusted according to actual needs, and the embodiments of the present application do not specifically limit this.

[0099] In some embodiments, the second alkaline solution is an aqueous solution of potassium hydroxide and hydrogen peroxide.

[0100] Optionally, the volume concentration of potassium hydroxide in the second alkaline solution is 0.7% to 1.1%, and the volume concentration of hydrogen peroxide is 3% to 8%; the temperature of the second alkaline solution is 57°C to 63°C, and the process time of the post-cleaning step is 150s to 300s; preferably, the volume concentration of potassium hydroxide in the second alkaline solution is 0.96%, and the volume concentration of hydrogen peroxide is 5.2%; the temperature of the second alkaline solution is 60°C, and the process time of the post-cleaning step is 200s.

[0101] In the embodiment of the present application, the impurities on the surface of the solar cell can be better cleaned through the two alkaline washing processes of step S101 and step S103. The hydrogen peroxide in step S103 has strong oxidizing properties and can oxidize the organic matter on the surface of the solar cell, and the potassium hydroxide in step S103 dissolves the oxidation product.

[0102] It should be noted that the concentration of potassium hydroxide in the second alkaline solution, the concentration of hydrogen peroxide, the temperature of the second alkaline solution and the process duration of the post-cleaning step can be flexibly adjusted according to actual needs, and the embodiments of the present application do not specifically limit this.

[0103] In some optional embodiments, the first acidic solution is an aqueous solution of hydrofluoric acid, and the second acidic solution is also an aqueous solution of hydrofluoric acid, but the volume concentration of hydrofluoric acid in the first acidic solution is greater than the volume concentration of hydrofluoric acid in the second acidic solution.

[0104] Optionally, the volume concentration of hydrofluoric acid in the first acidic solution is 18% to 23%; the temperature of the first acidic solution is room temperature, and the process time of the first pickling step is 130s to 300s; in addition, the volume concentration of hydrofluoric acid in the second acidic solution is 15% to 20%; the temperature of the second acidic solution is room temperature, and the process time of the second pickling step is 90s to 130s.

[0105] Preferably, the volume concentration of hydrofluoric acid in the first acidic solution is 20%; the temperature of the first acidic solution is room temperature, and the process time of the first pickling step is 220s; in addition, the volume concentration of hydrofluoric acid in the second acidic solution is 17%; the temperature of the second acidic solution is room temperature, and the process time of the second pickling step is 110s.

[0106] It should be noted that the concentration of hydrofluoric acid in the first acidic solution, the temperature of the first acidic solution, the process time of the first pickling step, the concentration of hydrofluoric acid in the second acidic solution, the temperature of the second acidic solution, and the process time of the second pickling step can all be flexibly adjusted according to actual needs, and the embodiments of the present application do not specifically limit this.

[0107] In the embodiments of the present application, while ensuring that the cleaning effect is not affected, the cleaning time is shortened and the cleaning efficiency is improved by optimizing the RCA cleaning process; in addition, not only the consumption of chemical reagents is reduced, but also the consumption of pure water is reduced, thereby reducing pollution to the environment and reducing the cost of treating peripheral wastewater.

[0108] In a second aspect, some embodiments of the present application provide a cleaning device for solar cells, such as Figure 2 As shown, the device specifically includes the following components:

[0109] In the order in which the solar cells pass, there are arranged in series a polysilicon removal Poly tank group 201, a first water washing tank 202, a post-cleaning tank group 203, a second water washing tank 204, a first pickling tank group 205, a third water washing tank 206, a slow pulling tank 207, and a drying tank group 208;

[0110] The polysilicon removal Poly tank group 201 is used to remove the polysilicon layer coated on the surface of the solar cell through the built-in first alkaline solution;

[0111] The first water washing tank 202 is used to remove the first alkaline solution remaining on the surface of the solar cell through the built-in pure water;

[0112] The post-cleaning tank group 203 is used to remove impurities on the surface of the solar cell through a built-in second alkaline solution;

[0113] The second water washing tank 204 is used to remove the second alkaline solution remaining on the surface of the solar cell through the built-in pure water;

[0114] The first pickling tank group 205 is used to remove the BSG layer on the front side and the PSG layer on the back side of the solar cell through a built-in first acid solution;

[0115] The third water washing tank 206 is used to remove the first acidic solution remaining on the surface of the solar cell through the built-in pure water;

[0116] The slow pulling tank 207 is used to slowly pull the solar cell through the built-in hot water to perform pre-dehydration;

[0117] The drying tank group 208 is used to dry the residual water on the surface of the solar cell.

[0118] In some optional embodiments, such as Figure 3 As shown, a second pickling tank 205' is connected in series between the first pickling tank group 205 and the third water washing tank 206;

[0119] The second pickling tank 205' is used to completely remove the BSG layer on the front side and the PSG layer on the back side of the solar cell through a built-in second acid solution.

[0120] In some optional embodiments, the polysilicon removal Poly tank group 201 includes: four polysilicon removal Poly tanks connected in parallel;

[0121] The post-cleaning tank group 203 includes: two post-cleaning tanks connected in parallel;

[0122] The first pickling tank group 205 includes: two first pickling tanks connected in parallel;

[0123] The drying tank group 208 includes six drying tanks connected in parallel.

[0124] In some optional embodiments, the first alkaline solution in the polysilicon removal Poly tank is: an aqueous solution of potassium hydroxide with a volume concentration of 3% to 8% and an additive with a volume solubility of 0.7% to 1.2%;

[0125] The second alkaline solution in the post-cleaning tank is an aqueous solution of potassium hydroxide with a volume concentration of 0.7% to 1.1% and hydrogen peroxide with a volume solubility of 3% to 8%;

[0126] The first acid solution in the first pickling tank is: an aqueous solution of hydrofluoric acid with a volume concentration of 18% to 23%;

[0127] The second acid solution contained in the second pickling tank is an aqueous solution of hydrofluoric acid with a volume concentration of 15% to 20%.

[0128] Compared with the existing cleaning devices, the cleaning device of the embodiment of the present application reduces the use of the tank body and reduces the manufacturing cost of the cleaning device. Cleaning the solar cell with the cleaning device provided by the embodiment of the present application not only reduces the cleaning time, but also reduces the investment in cleaning reagents, thereby achieving the purpose of reducing consumption and cost.

[0129] In order to objectively evaluate the technical effects of the embodiments of the present application, the present application will be described in detail and exemplarily through the following embodiments and comparative examples.

[0130] In the following examples and comparative examples, all raw materials can be purchased commercially, and in order to maintain the reliability of the experiment, the raw materials used in the following examples and comparative examples have the same physical and chemical parameters or are prepared by the same processing method.

[0131] Example 1

[0132] like Figure 4 As shown, the solar cell provided in Example 1 is cleaned according to the following RCA cleaning process:

[0133] S401, Poly removal step: the solar cell after phosphorus diffusion treatment is cleaned with a first aqueous solution containing potassium hydroxide and an additive to remove the polysilicon layer plated on the front and side surfaces of the solar cell; in the first aqueous solution, the volume concentration of potassium hydroxide is 5.2%, and the volume concentration of the additive is 1%; the temperature of the first aqueous solution is controlled at 70°C, and the process duration of Poly removal is controlled at 450s.

[0134] S402, first water washing step: using deionized water to rinse the solar cell after the de-Poly step to remove the residue on the surface of the solar cell.

[0135] S403, post-cleaning step: the solar cell treated in the first water washing step is cleaned with a second aqueous solution containing potassium hydroxide and hydrogen peroxide to remove impurities on the surface of the solar cell; in the second aqueous solution, the volume concentration of potassium hydroxide is 0.96%, and the volume concentration of hydrogen peroxide is 5.2%; the temperature of the second aqueous solution is controlled at 60°C, and the process duration of the post-cleaning is controlled at 200s.

[0136] S404, second water washing step: rinsing the solar cell after the post-washing step with deionized water to remove residues on the surface of the solar cell.

[0137] S405, first pickling step: the solar cell treated in the second water washing step is cleaned with a third aqueous solution containing hydrofluoric acid to preliminarily remove the BSG layer on the front side and the PSG layer on the back side of the solar cell; in the third aqueous solution, the volume concentration of hydrofluoric acid is 20%; the temperature of the third aqueous solution is room temperature, and the cleaning process duration is controlled at 220s.

[0138] S406, second pickling step: the solar cell treated in the first pickling step is cleaned with a fourth aqueous solution containing hydrofluoric acid to completely remove the BSG layer on the front side and the PSG layer on the back side of the solar cell; in the fourth aqueous solution, the volume concentration of hydrofluoric acid is 17%; the temperature of the fourth aqueous solution is room temperature, and the cleaning process duration is controlled at 110s.

[0139] S407, third water washing step: rinsing the solar cell after the second acid washing step with deionized water to remove residues on the surface of the solar cell.

[0140] S408, slow pulling step: slowly pulling the solar cell treated in the third water washing step out of the deionized water at a temperature of 50° C. for pre-dehydration.

[0141] S409, drying step: drying the solar cells after the slow pulling step to remove the residual moisture on the surface of the solar cells.

[0142] A front passivation layer and a back passivation layer are prepared on the solar cell obtained after cleaning in the above steps S401 to S409, and positive and negative metal electrodes are prepared by screen printing and sintering, so as to prepare a TOPCon solar cell.

[0143] Comparative Example 1

[0144] The difference from Example 1 is that the solar cells are cleaned according to the following RCA process flow: 1) Poly removal step, 2) first water washing step, 3) first alkali washing step, 4) second water washing step, 5) first acid washing step, 6) third water washing step, 7) second alkali washing step, 8) fourth water washing step, 9) second acid washing step, 10) fifth water washing step, 11) slow pulling step, and 12) drying step.

[0145] Test Case

[0146] The electrical performance parameters of the solar cells prepared in Example 1 and Comparative Example 1 were tested by a testing machine. Example 1 and Comparative Example 1 were tested three times respectively, and the test results obtained by taking the average values ​​are shown in Table 1 below.

[0147] Table 1

[0148] project Photoelectric conversion efficiency Open circuit voltage Short circuit voltage Fill Factor Electroluminescence yield Example 1 25.82 0.7192 15.87 86.38 99.14％ Comparative Example 1 25.81 0.7191 15.87 86.35 98.76％ Difference 0.01 0.0001 0.00 0.03 0.38％

[0149] Referring to Table 1, it can be seen that the yield of TOPCon solar cells produced based on the RCA cleaning method disclosed in the present application has higher photoelectric conversion efficiency, open circuit voltage, fill factor and electroluminescence yield than that of TOPCon solar cells produced by the cleaning method in the prior art, indicating that the cleaning method provided in the embodiment of the present application can improve the electrical performance parameters of solar cells.

[0150] From the data results in Table 1 above, it can be seen that the cleaning effect of the present invention is better than that of traditional RCA cleaning as a whole. In addition, since the method of the present invention reduces many cleaning steps compared to RCA cleaning, including a cleaning step using a cleaning agent, the amount of chemical reagents and pure water used is significantly reduced, which greatly reduces the production cost.

[0151] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0152] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for cleaning solar cells, characterized in that: include: The polysilicon removal step is to remove the polysilicon layer on the surface of the solar cell by using a first alkaline solution; A first water washing step, removing the first alkaline solution remaining on the surface of the solar cell by pure water; a post-cleaning step of removing impurities on the surface of the solar cell by a second alkaline solution; A second water washing step, removing the second alkaline solution remaining on the surface of the solar cell by pure water; A first pickling step, removing the borosilicate glass layer on the front side and the phosphosilicate glass layer on the back side of the solar cell by using a first acidic solution; A third water washing step, removing the first acidic solution remaining on the surface of the solar cell by pure water; A slow pulling step, slowly pulling the solar cell to perform pre-dehydration; The drying step is to dry the residual water on the surface of the solar cell.

2. The cleaning method for solar cells according to claim 1, characterized in that: After the first pickling step, the method further comprises: Determine whether the borosilicate glass layer on the front side and the phosphosilicate glass layer on the back side of the solar cell are completely removed; If yes, perform the third water washing step; If not, the second acid washing step is first performed to remove the borosilicate glass layer on the front side and the phosphosilicate glass layer on the back side of the solar cell by a second acid solution, and then the third water washing step is performed.

3. The cleaning method for solar cells according to claim 1, characterized in that: The first alkaline solution is an aqueous solution of potassium hydroxide and additives.

4. The cleaning method for solar cells according to claim 3, characterized in that: The volume concentration of potassium hydroxide in the first alkaline solution is 3% to 8%, and the volume concentration of the additive is 0.7% to 1.2%; The temperature of the first alkaline solution is 67° C. to 73° C., and the process duration of the polysilicon removal step is 450 s to 600 s.

5. The method for cleaning solar cells according to claim 1, characterized in that: The second alkaline solution is an aqueous solution of potassium hydroxide and hydrogen peroxide.

6. The cleaning method for solar cells according to claim 5, characterized in that: The volume concentration of potassium hydroxide in the second alkaline solution is 0.7% to 1.1%, and the volume concentration of hydrogen peroxide is 3% to 8%; The temperature of the second alkaline solution is 57° C. to 63° C., and the process duration of the post-cleaning step is 150 s to 300 s.

7. The cleaning method for solar cells according to claim 2, characterized in that: The first acidic solution is an aqueous solution of hydrofluoric acid.

8. The cleaning method for solar cells according to claim 7, characterized in that: The volume concentration of hydrofluoric acid in the first acidic solution is 18% to 23%; The temperature of the first acidic solution is room temperature, and the process duration of the first pickling step is 130s to 300s.

9. The cleaning method for solar cells according to claim 7, characterized in that: The second acidic solution is: an aqueous solution of hydrofluoric acid; Wherein, the volume concentration of hydrofluoric acid in the first acidic solution is greater than the volume concentration of hydrofluoric acid in the second acidic solution.

10. The cleaning method for solar cells according to claim 9, characterized in that: The volume concentration of hydrofluoric acid in the second acidic solution is 15% to 20%; The temperature of the second acidic solution is room temperature, and the process duration of the second pickling step is 90s to 130s.

11. A cleaning device for solar cells, characterized in that: include: In the order in which the solar cells pass, a polysilicon removal tank group, a first water washing tank group, a post-cleaning tank group, a second water washing tank group, a first pickling tank group, a third water washing tank group, a slow pulling tank group, and a drying tank group are arranged in series; The polysilicon removal tank group is used to remove the polysilicon layer coated on the surface of the solar cell through the built-in first alkaline solution; The first water washing tank is used to remove the first alkaline solution remaining on the surface of the solar cell through built-in pure water; The post-cleaning tank group is used to remove impurities on the surface of the solar cell through a built-in second alkaline solution; The second water washing tank is used to remove the second alkaline solution remaining on the surface of the solar cell through the built-in pure water; The first pickling tank group is used to remove the borosilicate glass layer on the front side and the phosphosilicate glass layer on the back side of the solar cell through the built-in first acid solution; The third water washing tank is used to remove the first acidic solution remaining on the surface of the solar cell through built-in pure water; The slow pulling tank is used to slowly pull the solar cell through built-in hot water to perform pre-dehydration; The drying tank group is used to dry the residual water on the surface of the solar cell.

12. The cleaning device for solar cells according to claim 11, characterized in that: A second pickling tank body is connected in series between the first pickling tank body group and the third water washing tank body; The second pickling tank is used to remove the borosilicate glass layer on the front side and the phosphosilicate glass layer on the back side of the solar cell through a built-in second acid solution.

13. The solar cell cleaning device according to claim 12, characterized in that: The polysilicon removal tank group comprises: four polysilicon removal tanks connected in parallel; The post-cleaning tank group comprises: two post-cleaning tanks connected in parallel; The first pickling tank group comprises: two first pickling tanks connected in parallel; The drying tank body group comprises six drying tank bodies connected in parallel.

14. The cleaning device for solar cells according to claim 13, characterized in that: The first alkaline solution in the polysilicon removal tank is an aqueous solution of potassium hydroxide with a volume concentration of 3% to 8% and an additive with a volume solubility of 0.7% to 1.2%. The second alkaline solution in the post-cleaning tank is an aqueous solution of potassium hydroxide with a volume concentration of 0.7% to 1.1% and hydrogen peroxide with a volume solubility of 3% to 8%; The first acid solution in the first pickling tank is: an aqueous solution of hydrofluoric acid with a volume concentration of 18% to 23%; The second acid solution contained in the second pickling tank is an aqueous solution of hydrofluoric acid with a volume concentration of 15% to 20%.

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