Additive for solving LPCVD (Low Pressure Chemical Vapor Deposition) double-plug front surface winding and enlarging printing of TOPCon battery and cleaning process

Abstract

The invention discloses an additive for solving LPCVD double-plug front surface winding and enlarging printing of a TOPCon cell and a cleaning process, and relates to the technical field of solar cell production and manufacturing. Comprising the following components: an alkali corrosion catalyst, a multi-carboxyl polymer, organic acid, a chelating agent, a surfactant, lactobionic acid, tetrahydroxymethyl glycoluril, hydroxypropyl beta-cyclodextrin, hyperbranched polytriazole hb-PTA-OEG and water. According to the additive and the cleaning process, polycrystalline silicon can be selectively etched and adsorbed on the surface of BPSG, the polycrystalline silicon is protected from being corroded by alkali in the winding plating removing process, meanwhile, the corrosion rate of winding plating in an alkali solution can be increased, front polycrystalline silicon can be removed more rapidly and thoroughly, and the gain effect on battery efficiency is obvious.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell production and manufacturing, and in particular to an additive and a cleaning process for solving the problem of LPCVD double-insertion front-side winding and expansion printing of TOPCon cells. Background Art

[0002] Solar cells are devices that directly convert light energy into electrical energy through the photoelectric effect or photochemical effect. As a type of solar cell, TOPCON (Thin Oxide Passivated Contact) cells are widely used due to their high photovoltaic conversion rate, relatively mature equipment and processes, and high cost-effectiveness in mass production.

[0003] In the TOPCon cell production process, LPCVD is required to grow polysilicon on one side of the silicon wafer. When coating the target growth surface with the current polysilicon growth method, polysilicon will inevitably grow on the edge of the other side, which we call wrap-around plating. If this part of the wrap-around polysilicon is not removed, it will significantly reduce the efficiency of the solar cell and cause serious poor appearance. Therefore, it is usually necessary to add a step to remove the wrap-around plating. After the TOPCon cell process, a layer of borosilicate glass, namely BSG, will form on the front of the silicon wafer. At the same time, the PSG and polysilicon layers wrapped around the front are also covered on it, and the junction is BPSG. Polysilicon is easily removed in a hot alkaline solution, so you only need to immerse the silicon wafer in a hot alkaline solution for a period of time to remove the polysilicon in the wrap-around part. However, the reaction rate of alkaline solution to different substances is different. In the process of de-coating, if no protective measures are taken, BPSG reacts fastest, so the pyramid in this part is very easy to be corroded, and after removing the oxide layer, it will form poor appearance such as coil expansion; when cleaning the coil, it may lead to incomplete removal or etching of the doped polysilicon layer, affecting the efficiency of the battery. It is in this situation that the additives and cleaning process for solving the LPCVD double-insertion front coil expansion of TOPCon batteries came into being, and its appearance has attracted great attention in the industry.

[0004] The existing additives and cleaning processes for solving the problem of LPCVD double-insertion front winding expansion of TOPCon cells have more or less technical defects such as slow and incomplete winding removal, etching of the doped polysilicon layer, and limited gain effect on cell efficiency. In order to solve the above problems, the Chinese invention patent with application publication number CN116808881A discloses an alkali polishing additive for TOPCON cell LPCVD double-insertion process, the content of each component of which is: 0.01-0.1 parts by mass of nanomaterial catalyst treated by nano homogenizer, 3-8 parts by mass of complexing dispersant, 1-5 parts by mass of inorganic salt, 5-8 parts by mass of surfactant, and 78.9-90.99 parts by mass of deionized water. The TOPCON battery polished with the above additives can clean the polySi and a small amount of BPSG that are plated, selectively protect BSG, control the alkali corrosion rate, evenly clean the corroded plating, and avoid problems such as color difference and poor appearance. The efficiency of the double-insertion process and the single-insertion process battery is the same, while the production capacity is doubled and the cost is reduced. The invention focuses on the effect of selectively protecting BSG, thereby solving the problems of the double-insertion process and appearance. However, its gain effect on battery efficiency needs to be further improved, and it depends on specific processing equipment, which requires a large capital investment.

[0005] Therefore, a method is developed that can selectively etch polysilicon and adsorb on the surface of BPSG to protect it from alkali corrosion during the de-wrap process, while increasing the corrosion rate of the wrap-around in alkaline solution, making the removal of the front polysilicon faster and more thorough, with a significant effect on cell efficiency gain. The additive and cleaning process for solving the LPCVD double-insertion front wrap-around of TOPCon cells meets market demand, has broad market value and application prospects, and is of great significance for promoting the further development of the TOPCon cell field. Summary of the invention

[0006] The main purpose of the present invention is to provide an additive and cleaning process for solving the problem of LPCVD dual-insertion front wrap-around printing of TOPCon cells, which can selectively etch polysilicon and adsorb on the surface of BPSG to protect it from alkali corrosion during the de-wrapping process, while increasing the corrosion rate of the wrap-around in the alkaline solution, making the removal of the front polysilicon faster and more thorough, and significantly increasing the efficiency of the cell.

[0007] To achieve the above purpose, the present invention provides an additive for solving the problem of LPCVD dual-insertion front-side expansion printing of TOPCon batteries, comprising the following components calculated by mass percentage: alkali corrosion catalyst 0.8wt%-1.5wt%, polycarboxyl polymer 0.5wt%-1wt%, organic acid 0.1wt%-0.6wt%, chelating agent 0.3wt%-0.8wt%, surfactant 0.8wt%-2wt%, lactobionic acid 0.3wt%-1wt%, tetrahydroxymethyl glycoluril 0.05wt%-0.12wt%, hydroxypropyl β-cyclodextrin 0.03wt%-0.1wt%, hyperbranched polytriazole hb-PTA-OEG 0.03wt%-0.08wt%, and the balance is water.

[0008] Preferably, the alkaline corrosion catalyst is one or a combination of two or more of ammonium persulfate, meta-chloroperbenzoic acid, and urea peroxide.

[0009] Preferably, the polycarboxyl polymer is one or a combination of two or more of polyaspartic acid, sodium polyacrylate, and polycarboxylate dispersant 5040.

[0010] Preferably, the organic acid is one or a combination of formic acid, acetic acid, citraconic acid, aminosulfonic acid, and methanesulfonic acid.

[0011] Preferably, the chelating agent is one or a combination of two or more of citric acid, tartaric acid, malic acid, EDTA and sodium gluconate.

[0012] Preferably, the surfactant is one or a combination of two or more of Span 80, Tween 20, sodium dodecylbenzene sulfonate, and lauroylamidopropyl betaine.

[0013] Preferably, the source of the hyperbranched polytriazole hb-PTA-OEG has special requirements. In one embodiment of the present invention, the hyperbranched polytriazole hb-PTA-OEG is prepared according to the method of Example 1 of the Chinese invention patent with authorization announcement number CN104403103B.

[0014] Another object of the present invention is to provide a cleaning process for removing the winding degree and cleaning using the additive for solving the problem of LPCVD double-insertion front winding expansion of TOPCon cells, comprising the following steps: Step S1, after uniformly mixing the components of the additive for solving the problem of LPCVD double-insertion front-side winding and expansion of TOPCon batteries, the additive for solving the problem of LPCVD double-insertion front-side winding and expansion of TOPCon batteries is obtained; Step S2, etching the silicon wafer with hydrofluoric acid to remove the phosphosilicate glass on the front side; Step S3, add the additive for solving the TOPCon battery LPCVD dual-insertion front-side expansion printing prepared in step S1 into the alkaline solution and stir evenly, alkali-etch the silicon wafer treated in step S2, and then sequentially perform deionized water washing, post-washing, deionized water washing, acid washing, deionized water washing, slow pulling and drying.

[0015] Preferably, the mass percentage concentration of the hydrofluoric acid in step S2 is 45-55wt%; during the acid etching, the silicon wafer is etched in the PSG removal groove with the front side facing downward to protect the PSG on the back side, and the acid etching time is ≥10s.

[0016] Preferably, the alkali solution in step S3 is a sodium hydroxide solution or a potassium hydroxide solution; the mass percentage concentration of the alkali solution is 1-2wt%.

[0017] Preferably, the volume ratio of the additive and the alkaline solution used to solve the LPCVD double-insertion front-side expansion printing of the TOPCon battery described in step S3 is (0.5-1.5):100.

[0018] Preferably, the temperature of the alkaline etching in step S3 is 60-75° C. and the time is 300-500 s.

[0019] Due to the application of the above technical solution, the present invention has the following beneficial effects: (1) The cleaning process disclosed in the present invention for removing the winding and cleaning of the additives for solving the problem of LPCVD double-insertion front winding and expansion printing of TOPCon batteries is simple and easy to operate, convenient to operate and control, has low dependence on equipment, low energy consumption, and little impact on the environment. It has a good appearance after cleaning, high alkaline etching efficiency and good effect, is suitable for industrial production, and has a high value for promotion and application.

[0020] (2) The additive disclosed in the present invention for solving the LPCVD dual-insertion front-side expansion printing of TOPCon batteries includes the following components calculated by mass percentage: alkaline corrosion catalyst 0.8wt%-1.5wt%, polycarboxyl polymer 0.5wt%-1wt%, organic acid 0.1wt%-0.6wt%, chelating agent 0.3wt%-0.8wt%, surfactant 0.8wt%-2wt%, lactobionic acid 0.3wt%-1wt%, tetrahydroxymethyl glycoluril 0.05wt%-0.12wt%, hydroxypropyl β-cyclodextrin 0.03wt%-0.1wt%, hyperbranched polytriazole hb-PTA-OEG 0.03wt%-0.08wt%, and the balance is water. Through the mutual coordination and joint action of various components, the prepared additive can selectively etch polysilicon and adsorb on the surface of BPSG, protecting it from alkali corrosion during the de-plating process. At the same time, it can increase the corrosion rate of the de-plating in the alkaline solution, making the removal of the front polysilicon faster and more thorough. At the same time, it can protect the front PN junction of the silicon wafer from being damaged, and the effect of increasing the battery efficiency is obvious.

[0021] (3) The additive disclosed in the present invention is used to solve the problem of LPCVD double-insertion front-side winding and expansion printing of TOPCon cells. The alkaline corrosion catalyst can accelerate the oxidation step to a certain extent, thereby enhancing the decomposition effect of polysilicon; the polycarboxyl polymer has a hydrophilic carboxyl group, and has a dipole-dipole interaction, a hydrophilic-hydrophobic interaction and a hydrogen bond interaction with the BPSG on the front side of the cell, and is easily adsorbed on the BPSG position to form a film, thereby preventing the contact between hydroxyl and BPSG, thereby achieving selective corrosion of BPSG and polysilicon, so that the pyramid on the front side of the cell is not destroyed during the de-winding plating process; the organic acid substance can further protect the BPSG from corrosion. The selected organic acid substance selectively corrodes polysilicon but does not react with single crystal silicon and silicon oxide, and this type of substance has electrostatic interaction. It can be adsorbed on the surface of the oxide layer well, temporarily preventing corrosion and damage at the adsorption points, thereby further protecting BPSG; the chelating agent can effectively chelate metal ions, further enhance the cleaning effect, and prevent the silicon wafer from adsorbing metal ions and causing a decrease in conversion efficiency; the surfactant, lactobionic acid, tetrahydroxymethyl glycoluril, hydroxypropyl β-cyclodextrin and hyperbranched polytriazole hb-PTA-OEG, cooperate with other components to further improve the effect and efficiency of selective etching, so that the product can adapt to the selective etching of polysilicon while protecting the front oxide layer and pyramid from being damaged. During the alkaline etching process, the additive product can completely protect the oxide layer and pyramid while promoting the cleaning of polysilicon, thereby improving the cleaning effect of the silicon wafer and protecting the front PN junction of the silicon wafer from being damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a surface morphology of a silicon wafer before de-coating in Example 1 of the present invention; Figure 2 This is a surface morphology image after de-coating in Example 1 of the present invention; Figure 3 This is a scanning electron microscope image of the pyramid of the BPSG part in Example 1 of the present invention; Figure 4 This is a scanning electron microscope image of the pyramid of the BPSG part in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0023] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0024] Example 1, an additive for solving the LPCVD dual-insertion front-side expansion printing of TOPCon batteries, including the following components calculated by mass percentage: 0.8wt% alkaline corrosion catalyst, 0.5wt% polycarboxyl polymer, 0.1wt% organic acid, 0.3wt% chelating agent, 0.8wt% surfactant, 0.3wt% lactobionic acid, 0.05wt% tetrakishydroxymethyl glycoluril, 0.03wt% hydroxypropyl β-cyclodextrin, 0.03wt% hyperbranched polytriazole hb-PTA-OEG, and the balance is water.

[0025] The alkaline corrosion catalyst is ammonium persulfate; the polycarboxyl polymer is polyaspartic acid; the organic acid is formic acid; the chelating agent is citric acid; the surfactant is Span 80; the hyperbranched polytriazole hb-PTA-OEG is prepared according to the method of Example 1 of the Chinese invention patent with authorization announcement number CN104403103B.

[0026] A cleaning process for removing the winding degree and cleaning using the additive for solving the problem of LPCVD double-insertion front winding and expansion printing of TOPCon cells comprises the following steps: Step S1, after uniformly mixing the components of the additive for solving the problem of LPCVD double-insertion front-side winding and expansion of TOPCon batteries, the additive for solving the problem of LPCVD double-insertion front-side winding and expansion of TOPCon batteries is obtained; Step S2, etching the silicon wafer with hydrofluoric acid to remove the phosphosilicate glass on the front side; Step S3, add the additive for solving the TOPCon battery LPCVD dual-insertion front-side expansion printing prepared in step S1 into the alkaline solution and stir evenly, alkali-etch the silicon wafer treated in step S2, and then sequentially perform deionized water washing, post-washing, deionized water washing, acid washing, deionized water washing, slow pulling and drying.

[0027] The mass percentage concentration of the hydrofluoric acid in step S2 is 45wt%; during the acid etching, the silicon wafer is etched in the PSG removal groove with the front side facing downward to protect the PSG on the back side, and the acid etching time is ≥10s.

[0028] The alkali solution described in step S3 is sodium hydroxide solution; the mass percentage concentration of the alkali solution is 1wt%; the volume ratio of the additive used to solve the LPCVD double-insertion front-side expansion printing of the TOPCon battery described in step S3 and the alkali solution is 0.5:100; the temperature of the alkaline etching in step S3 is 60°C and the time is 300s.

[0029] Example 2, an additive for solving the LPCVD dual-insertion front-side expansion printing of TOPCon batteries, including the following components calculated by mass percentage: 1wt% alkaline corrosion catalyst, 0.6wt% polycarboxyl polymer, 0.2wt% organic acid, 0.4wt% chelating agent, 1wt% surfactant, 0.5wt% lactobionic acid, 0.07wt% tetrakishydroxymethyl glycoluril, 0.05wt% hydroxypropyl β-cyclodextrin, 0.04wt% hyperbranched polytriazole hb-PTA-OEG, and the balance is water.

[0030] The alkaline corrosion catalyst is m-chloroperbenzoic acid; the polycarboxyl polymer is sodium polyacrylate; the organic acid is acetic acid; the chelating agent is tartaric acid; the surfactant is Tween 20; the hyperbranched polytriazole hb-PTA-OEG is prepared according to the method of Example 1 of the Chinese invention patent with authorization announcement number CN104403103B.

[0031] A cleaning process for removing the winding degree and cleaning using the additive for solving the problem of LPCVD double-insertion front winding and expansion printing of TOPCon cells comprises the following steps: Step S1, after uniformly mixing the components of the additive for solving the problem of LPCVD double-insertion front-side winding and expansion of TOPCon batteries, the additive for solving the problem of LPCVD double-insertion front-side winding and expansion of TOPCon batteries is obtained; Step S2, etching the silicon wafer with hydrofluoric acid to remove the phosphosilicate glass on the front side; Step S3, add the additive for solving the TOPCon battery LPCVD dual-insertion front-side expansion printing prepared in step S1 into the alkaline solution and stir evenly, alkali-etch the silicon wafer treated in step S2, and then sequentially perform deionized water washing, post-washing, deionized water washing, acid washing, deionized water washing, slow pulling and drying.

[0032] The mass percentage concentration of the hydrofluoric acid in step S2 is 48wt%; during the acid etching, the silicon wafer is etched in the PSG removal groove with the front side facing down to protect the PSG on the back side, and the acid etching time is ≥10s; the alkali solution in step S3 is a potassium hydroxide solution; the mass percentage concentration of the alkali solution is 1.2wt%.

[0033] The volume ratio of the additive and the alkaline solution used to solve the LPCVD double-insertion front-side expansion printing of the TOPCon battery described in step S3 is 0.8:100; the temperature of the alkaline etching described in step S3 is 65°C and the time is 350s.

[0034] Example 3, an additive for solving the LPCVD dual-insertion front-side expansion printing of TOPCon batteries, including the following components calculated by mass percentage: 1.2wt% alkaline corrosion catalyst, 0.7wt% polycarboxyl polymer, 0.35wt% organic acid, 0.5wt% chelating agent, 1.3wt% surfactant, 0.6wt% lactobionic acid, 0.09wt% tetrakishydroxymethyl glycoluril, 0.07wt% hydroxypropyl β-cyclodextrin, 0.06wt% hyperbranched polytriazole hb-PTA-OEG, and the balance is water.

[0035] The alkaline corrosion catalyst is urea peroxide; the polycarboxyl polymer is polycarboxylate dispersant 5040; the organic acid is citraconic acid; the chelating agent is malic acid; the surfactant is sodium dodecylbenzene sulfonate; the hyperbranched polytriazole hb-PTA-OEG is prepared according to the method of Example 1 of the Chinese invention patent with authorization announcement number CN104403103B.

[0036] A cleaning process for removing the winding degree and cleaning using the additive for solving the problem of LPCVD double-insertion front winding and expansion printing of TOPCon cells comprises the following steps: Step S1, after uniformly mixing the components of the additive for solving the problem of LPCVD double-insertion front-side winding and expansion of TOPCon batteries, the additive for solving the problem of LPCVD double-insertion front-side winding and expansion of TOPCon batteries is obtained; Step S2, etching the silicon wafer with hydrofluoric acid to remove the phosphosilicate glass on the front side; Step S3, add the additive for solving the TOPCon battery LPCVD dual-insertion front-side expansion printing prepared in step S1 into the alkaline solution and stir evenly, alkali-etch the silicon wafer treated in step S2, and then sequentially perform deionized water washing, post-washing, deionized water washing, acid washing, deionized water washing, slow pulling and drying.

[0037] The mass percentage concentration of the hydrofluoric acid in step S2 is 50wt%; during the acid etching, the silicon wafer is etched in the PSG removal groove with the front side facing down to protect the PSG on the back side, and the acid etching time is ≥10s; the alkali solution in step S3 is a sodium hydroxide solution; the mass percentage concentration of the alkali solution is 1.5wt%.

[0038] The volume ratio of the additive and the alkaline solution used to solve the LPCVD double-insertion front-side expansion printing of the TOPCon battery described in step S3 is 1:100; the temperature of the alkaline etching described in step S3 is 68°C and the time is 400s.

[0039] Example 4, an additive for solving the LPCVD dual-insertion front-side expansion printing of TOPCon batteries, comprising the following components calculated by mass percentage: 1.4wt% alkaline corrosion catalyst, 0.9wt% polycarboxyl polymer, 0.5wt% organic acid, 0.7wt% chelating agent, 1.8wt% surfactant, 0.9wt% lactobionic acid, 0.11wt% tetrakishydroxymethyl glycoluril, 0.09wt% hydroxypropyl β-cyclodextrin, 0.07wt% hyperbranched polytriazole hb-PTA-OEG, and the balance is water.

[0040] The alkaline corrosion catalyst is ammonium persulfate, meta-chloroperbenzoic acid, and urea peroxide mixed in a mass ratio of 1:2:3; the polycarboxyl polymer is polyaspartic acid, sodium polyacrylate, and polycarboxylate dispersant 5040 mixed in a mass ratio of 1:3:5; the organic acid is formic acid, acetic acid, citraconic acid, aminosulfonic acid, and methylsulfonic acid mixed in a mass ratio of 1:1:2:1:3; the chelating agent is citric acid, tartaric acid, malic acid, EDTA, and sodium gluconate mixed in a mass ratio of 2:1:3:2:5; the surfactant is Span 80, Tween 20, sodium dodecylbenzene sulfonate, and lauroamidopropyl betaine mixed in a mass ratio of 1:3:4:2; the hyperbranched polytriazole hb-PTA-OEG is prepared according to the method of Example 1 of the Chinese invention patent with authorization announcement number CN104403103B.

[0041] A cleaning process for removing the winding degree and cleaning using the additive for solving the problem of LPCVD double-insertion front winding and expansion printing of TOPCon cells comprises the following steps: Step S1, after uniformly mixing the components of the additive for solving the problem of LPCVD double-insertion front-side winding and expansion of TOPCon batteries, the additive for solving the problem of LPCVD double-insertion front-side winding and expansion of TOPCon batteries is obtained; Step S2, etching the silicon wafer with hydrofluoric acid to remove the phosphosilicate glass on the front side; Step S3, add the additive for solving the TOPCon battery LPCVD dual-insertion front-side expansion printing prepared in step S1 into the alkaline solution and stir evenly, alkali-etch the silicon wafer treated in step S2, and then sequentially perform deionized water washing, post-washing, deionized water washing, acid washing, deionized water washing, slow pulling and drying.

[0042] The mass percentage concentration of the hydrofluoric acid in step S2 is 53wt%; during the acid etching, the silicon wafer is etched face down in the PSG removal groove to protect the PSG on the back, and the acid etching time is ≥10s; the alkali solution in step S3 is a sodium hydroxide solution; the mass percentage concentration of the alkali solution is 1.8wt%.

[0043] The volume ratio of the additive and the alkaline solution used to solve the LPCVD double-insertion front-side expansion printing of the TOPCon battery described in step S3 is 1.3:100; the temperature of the alkaline etching described in step S3 is 73°C and the time is 450s.

[0044] Example 5, an additive for solving the LPCVD dual-insertion front-side expansion printing of TOPCon batteries, including the following components calculated by mass percentage: 1.5wt% alkaline corrosion catalyst, 1wt% polycarboxyl polymer, 0.6wt% organic acid, 0.8wt% chelating agent, 2wt% surfactant, 1wt% lactobionic acid, 0.12wt% tetrakishydroxymethyl glycoluril, 0.1wt% hydroxypropyl β-cyclodextrin, 0.08wt% hyperbranched polytriazole hb-PTA-OEG, and the balance is water.

[0045] The alkaline corrosion catalyst is m-chloroperbenzoic acid; the polycarboxyl polymer is polycarboxylate dispersant 5040; the organic acid is aminosulfonic acid; the chelating agent is sodium gluconate; the surfactant is Span 80; the hyperbranched polytriazole hb-PTA-OEG is prepared according to the method of Example 1 of the Chinese invention patent with authorization announcement number CN104403103B.

[0046] A cleaning process for removing the winding degree and cleaning using the additive for solving the problem of LPCVD double-insertion front winding and expansion printing of TOPCon cells comprises the following steps: Step S1, after uniformly mixing the components of the additive for solving the problem of LPCVD double-insertion front-side winding and expansion of TOPCon batteries, the additive for solving the problem of LPCVD double-insertion front-side winding and expansion of TOPCon batteries is obtained; Step S2, etching the silicon wafer with hydrofluoric acid to remove the phosphosilicate glass on the front side; Step S3, add the additive for solving the TOPCon battery LPCVD dual-insertion front-side expansion printing prepared in step S1 into the alkaline solution and stir evenly, alkali-etch the silicon wafer treated in step S2, and then sequentially perform deionized water washing, post-washing, deionized water washing, acid washing, deionized water washing, slow pulling and drying.

[0047] The mass percentage concentration of the hydrofluoric acid in step S2 is 55wt%; during the acid etching, the silicon wafer is etched in the PSG removal groove with the front side facing downward to protect the PSG on the back side, and the acid etching time is ≥10s.

[0048] The alkali solution described in step S3 is sodium hydroxide solution or potassium hydroxide solution; the mass percentage concentration of the alkali solution is 2wt%; the volume ratio of the additive used to solve the LPCVD double-insertion front-side expansion printing of the TOPCon battery in step S3 and the alkali solution is 1.5:100; the temperature of the alkaline etching in step S3 is 75°C and the time is 500s.

[0049] Comparative Example 1 The present invention provides an additive and a cleaning process for solving the problem of LPCVD double-insertion front-side expansion printing of TOPCon cells, which is similar to Example 1, except that hyperbranched polytriazole hb-PTA-OEG and lactobionic acid are not added.

[0050] Comparative Example 2 The present invention provides an additive and a cleaning process for solving the problem of LPCVD double-insertion front-side expansion printing of TOPCon batteries, which is similar to Example 1, except that tetrahydroxymethyl glycoluril and hydroxypropyl β-cyclodextrin are not added.

[0051] The additives for solving the problem of LPCVD double-insertion front-side expansion printing of TOPCon cells involved in the above Examples 1-5 and Comparative Examples 1-2 were subjected to relevant performance tests. The test results are shown in Table 1. The test method is as follows: (1) Appearance: Observe the appearance changes of the silicon wafer after alkaline etching and cleaning. If the side is etched clean and the tower base is of normal size, there is no residue after plating cleaning on the front side, the pyramid on the front surface of the silicon wafer is well protected, and the polysilicon layer on the back side is well protected, then the appearance passes. If the velvet surface of the pyramid on the front side is damaged, there is obvious expansion on the appearance, the polysilicon layer on the back side is corroded, and any of the above conditions destroys the tunneling structure of the TOPCon battery, then the appearance fails.

[0052] (2) Electrical properties: The silicon wafers after alkaline etching and cleaning in each case were put into the subsequent solar cell preparation process to be made into finished solar cells. The finished solar cells made in each case were tested using a special test instrument for solar cells, such as a single flash simulator. The test conditions were standard test conditions (STC): light intensity 1000W / m 2 ; Spectrum AM1.5; Temperature 25℃; Test method is in accordance with IEC904-1, main electrical performance parameters of the cell: photoelectric conversion efficiency (Eta, unit: %), fill factor (FF, unit: %).

[0053] Table 1

[0054] As can be seen from Table 1, the additives and cleaning process for solving the LPCVD double-insertion front-side expansion printing of TOPCon cells disclosed in the embodiments of the present invention have a more excellent alkaline etching cleaning effect than the comparative product, and the photoelectric conversion efficiency gain effect of the solar cell is more obvious; the addition of hyperbranched polytriazole hb-PTA-OEG, lactobionic acid, tetrahydroxymethyl glycoluril and hydroxypropyl β-cyclodextrin is beneficial to improving the above performance.

[0055] At the same time, taking Example 1 as an example, the surface morphology of the silicon wafer before de-winding cleaning using the additives and cleaning methods of each example is shown in FIG. Figure 1 , the surface morphology after de-plating is shown in Figure 2 , BPSG part pyramid scanning electron microscope image see Figure 3 ;from Figure 1-Figure 3 It can be seen that the side is etched cleanly and the tower base is normal in size, the front side is cleaned by plating and there is no residue, and the pyramid on the front surface of the silicon wafer is well protected.

[0056] At the same time, the BPSG part of the comparative example 1 is shown in the scanning electron microscope image. Figure 4 ,from Figure 4 It can be seen that after alkaline etching and cleaning, the pyramid velvet surface on the front side of the silicon wafer is damaged, and there is an obvious expansion mark on the appearance.

[0057] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. An additive for solving the problem of LPCVD double-insertion front-side expansion printing of TOPCon cells, characterized in that: The invention comprises the following components calculated by mass percentage: 0.8wt%-1.5wt% of alkaline corrosion catalyst, 0.5wt%-1wt% of polycarboxyl polymer, 0.1wt%-0.6wt% of organic acid, 0.3wt%-0.8wt% of chelating agent, 0.8wt%-2wt% of surfactant, 0.3wt%-1wt% of lactobionic acid, 0.05wt%-0.12wt% of tetrakishydroxymethyl glycoluril, 0.03wt%-0.1wt% of hydroxypropyl beta-cyclodextrin, 0.03wt%-0.1wt% of hyperbranched polytriazole hb-PTA-OEG, and the balance is water.

2. The additive for solving the problem of LPCVD double-insertion front-side winding and expansion printing of TOPCon cells according to claim 1, characterized in that: The alkaline corrosion catalyst is one or a combination of two or more of ammonium persulfate, meta-chloroperbenzoic acid, and urea peroxide.

3. The additive for solving the problem of LPCVD double-insertion front-side expansion printing of TOPCon cells according to claim 1, characterized in that: The polycarboxyl polymer is one or a combination of two or more of polyaspartic acid, sodium polyacrylate, and polycarboxylate dispersant 5040.

4. The additive for solving the problem of LPCVD double-insertion front-side winding and expansion printing of TOPCon cells according to claim 1, characterized in that: The organic acid is one or a combination of formic acid, acetic acid, citraconic acid, aminosulfonic acid and methanesulfonic acid.

5. The additive for solving the problem of LPCVD double insertion front-side winding and expansion printing of TOPCon cells according to claim 1, characterized in that: The chelating agent is one or a combination of two or more of citric acid, tartaric acid, malic acid, EDTA and sodium gluconate.

6. The additive for solving the problem of LPCVD double-insertion front-side expansion printing of TOPCon cells according to claim 1, characterized in that: The surfactant is one or a combination of two or more of Span 80, Tween 20, sodium dodecylbenzene sulfonate, and lauroylamidopropyl betaine.

7. A cleaning process for removing winding and cleaning using the additive for solving the problem of LPCVD double-insertion front winding and expansion printing of TOPCon cells as described in any one of claims 1 to 6, characterized in that: The steps include: Step S1, after uniformly mixing the components of the additive for solving the problem of LPCVD double-insertion front-side winding and expansion of TOPCon batteries, the additive for solving the problem of LPCVD double-insertion front-side winding and expansion of TOPCon batteries is obtained; Step S2, etching the silicon wafer with hydrofluoric acid to remove the phosphosilicate glass on the front side; Step S3, add the additive for solving the TOPCon battery LPCVD dual-insertion front-side expansion printing prepared in step S1 into the alkaline solution and stir evenly, alkali-etch the silicon wafer treated in step S2, and then sequentially perform deionized water washing, post-washing, deionized water washing, acid washing, deionized water washing, slow pulling and drying.

8. The cleaning process according to claim 7, characterized in that: The mass percentage concentration of the hydrofluoric acid in step S2 is 45-55wt%; during the acid etching, the silicon wafer is etched in the PSG removal groove with the front side facing downward to protect the PSG on the back side, and the acid etching time is ≥10s.

9. The cleaning process according to claim 7, characterized in that: The alkali solution described in step S3 is sodium hydroxide solution or potassium hydroxide solution; the mass percentage concentration of the alkali solution is 1-2wt%; the volume ratio of the additive used to solve the LPCVD double-insertion front winding and expansion printing of the TOPCon battery described in step S3 and the alkali solution is (0.5-1.5):

100.

10. The cleaning process according to claim 7, characterized in that: The alkaline etching in step S3 is carried out at a temperature of 60-75° C. and for a time of 300-500 seconds.

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