A single crystal texturing process in HJT cell production

Abstract

The application discloses a single crystal texturing process in HJT cell production, and the method comprises the following steps: washing a silicon wafer with pure water to remove surface dirt; pre-cleaning the silicon wafer; texturing the silicon wafer after pre-treatment to form a uniform surface; once cleaning the silicon wafer after texturing with a mixed solution of potassium hydroxide and hydrogen peroxide; twice cleaning the silicon wafer after texturing with a mixed solution of hydrochloric acid and hydrogen peroxide; cleaning the silicon wafer with a hydrofluoric acid solution after pure water washing; slow lifting the silicon wafer with pure water for pre-drying; and drying the obtained silicon wafer. Compared with the traditional single crystal texturing process, the texturing cleaning process used in the application has a reduced process flow, the cleaning liquid does not contain nitrogen substances, an ozone generator is not needed, and the pollution of the environment caused by the modified substances is eliminated, the types of chemicals used are less, and the cost of raw materials used is reduced.

Description

Technical Field

[0001] This invention relates to the field of HJT battery technology, and more particularly to a single-crystal texturing process in HJT battery production. Background Technology

[0002] Heterojunction (HJT) solar cells, characterized by high efficiency, high on-state voltage, and simple manufacturing process, have gained popularity and traction in recent years. Also known as HIT, HJT, or SHJ cells, their current manufacturing process mainly involves texturing and cleaning, amorphous silicon, total silicon co-processing (TCO), printing, and testing, requiring fewer steps compared to traditional solar cells. Among these, texturing and cleaning is a crucial step in solar cell production. To form a suitable pyramidal textured surface and improve silicon wafer cleanliness, existing texturing and cleaning processes involve numerous steps and often use large amounts of nitrogen-containing chemicals, which negatively impacts the uniformity of the textured surface and raises significant environmental concerns regarding the disposal of these nitrogen-containing chemicals. Therefore, this invention provides a novel texturing and cleaning process that does not use nitrogen-containing chemicals, achieving a final conversion efficiency comparable to traditional texturing and cleaning processes, while offering advantages such as fewer process steps, less environmental pollution, and lower cost. Summary of the Invention

[0003] To address the aforementioned issues, this invention provides a monocrystalline texturing process for HJT battery production that is more environmentally friendly, involves fewer process steps, and eliminates the need for an ozone generator.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a single-crystal texturing process in HJT battery production, the method comprising the following steps:

[0005] The silicon wafers are washed with pure water to remove surface dirt;

[0006] Pre-clean the silicon wafers;

[0007] After rinsing with pure water, the pre-treated silicon wafers are texturized to form a uniform textured surface.

[0008] After rinsing with pure water, the texturized silicon wafer is cleaned once with a mixed solution of potassium hydroxide and hydrogen peroxide.

[0009] After rinsing with pure water, the texturized silicon wafers are cleaned a second time with a mixture of hydrochloric acid and hydrogen peroxide.

[0010] After rinsing with pure water, the silicon wafer is cleaned with hydrofluoric acid solution to achieve dehydration, and then rinsed with pure water again.

[0011] The silicon wafers are slowly pulled up using pure water and pre-dried.

[0012] The resulting silicon wafers are then dried.

[0013] Furthermore, the pre-cleaning involves cleaning the silicon wafer with a mixed solution of potassium hydroxide and hydrogen peroxide, wherein the mass fraction of potassium hydroxide is not less than 60% and the mass fraction of hydrogen peroxide is not less than 20%, and the cleaning time is 4-6 minutes.

[0014] Furthermore, the texturing time for the silicon wafer is 600-900 seconds, and the texturing temperature is 65-85°C.

[0015] Furthermore, in the first cleaning, the mass fraction of potassium hydroxide in the mixed solution of potassium hydroxide and hydrogen peroxide is not less than 60%, the mass fraction of hydrogen peroxide is not less than 20%, the cleaning temperature is 40-85℃, and the cleaning time is 4min-6min.

[0016] Furthermore, in the secondary cleaning, the hydrochloric acid and hydrogen peroxide mixture has a hydrochloric acid mass fraction of not less than 30% and a hydrogen peroxide mass fraction of not less than 20%, the cleaning temperature is 40-85℃, and the cleaning time is 4min-6min.

[0017] Furthermore, when cleaning silicon wafers with hydrofluoric acid solution, the mass fraction of hydrofluoric acid solution is not less than 50%, and the cleaning time at room temperature is 50-200 seconds.

[0018] Furthermore, the silicon wafer is slowly pulled up using pure water at a temperature of 30-60°C for a cleaning time of >30 seconds.

[0019] Furthermore, the drying temperature of the silicon wafer is 30-90℃, and the drying time is 400-720s.

[0020] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following advantages:

[0021] Compared with the traditional single-crystal texturing process, the texturing and cleaning process used in this invention has several advantages. First, it reduces the number of process steps and the types of tanks required, thereby lowering equipment development costs. Second, the cleaning solutions used in this invention are all potassium hydroxide and hydrogen peroxide, which do not contain nitrogenous substances and eliminate the need for ozone generators, thus preventing the pollution of such substances to the environment. Finally, this invention uses fewer types of chemicals, reducing the cost of raw materials. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0023] Figure 1 This is a flowchart of a single-crystal texturing process in the production of HJT batteries according to the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] Example

[0026] A single-crystal texturing process for HJT battery production, the method comprising the following steps:

[0027] S01. The silicon wafer is washed with pure water to remove particulate dirt and other contaminants from the surface of the silicon wafer during slicing, packaging, disassembly, and manual operation. The washing time is 90-240 seconds.

[0028] S02. Pre-clean the silicon wafer using a mixed solution of potassium hydroxide and hydrogen peroxide. The potassium hydroxide mass fraction should be no less than 60%, and the hydrogen peroxide mass fraction should be no less than 20%. The cleaning time should be 4-6 minutes. The mixed solution of potassium hydroxide and hydrogen peroxide is used to oxidize the surface of the silicon wafer. On the one hand, the strong alkali will remove some of the chemical substances trapped on the surface, thus cleaning the surface. On the other hand, this cleaning method increases the cleanliness of the silicon wafer surface and provides oxidation points for pyramid etching in the subsequent texturing process, thus better forming the textured surface.

[0029] S03. Wash with pure water to remove the surface solution. The washing time is 90-240 seconds. Then, texture the pre-treated silicon wafer for 600-800 seconds at a temperature of 70-80℃ to form a uniform textured surface.

[0030] S04. Rinse the silicon wafer once or twice with pure water to remove the surface solution. The rinsing time is 90-240 seconds. Then, clean the texturized silicon wafer once with a mixed solution of potassium hydroxide and hydrogen peroxide. The mass fraction of potassium hydroxide should not be less than 60%, and the mass fraction of hydrogen peroxide should not be less than 20%. The cleaning temperature should be 40-85℃, and the cleaning time should be 4-6 minutes.

[0031] S05. Wash with pure water to remove the surface solution. The washing time is 90-240 seconds. Then, clean the texturized silicon wafer a second time with a mixture of hydrochloric acid and hydrogen peroxide. The mass fraction of hydrochloric acid is not less than 30%, and the mass fraction of hydrogen peroxide is not less than 20%. The cleaning temperature is 40-85℃, and the cleaning time is 4-6 minutes.

[0032] S06. Wash with pure water to remove the surface solution. The washing time is 90-240 seconds. Clean the silicon wafer with hydrofluoric acid solution. The mass fraction of the hydrofluoric acid solution should not be less than 50%. The washing time is 50-200 seconds at room temperature. After achieving the purpose of dehydration, wash with pure water to remove the surface acid solution. The washing time is 90-240 seconds.

[0033] S07. The silicon wafer is slowly lifted with pure water at a temperature of 30-60℃ for a cleaning time of more than 30 seconds, and then pre-dried.

[0034] S08. Dry the obtained silicon wafer at a temperature of 30-90℃ for 400-720 seconds.

[0035] Compared with the traditional single-crystal texturing process, the texturing and cleaning process used in this invention has several advantages. First, it reduces the number of process steps and the types of tanks required, thereby lowering equipment development costs. Second, the cleaning solutions used in this invention are all potassium hydroxide and hydrogen peroxide, which do not contain nitrogenous substances and eliminate the need for ozone generators, thus preventing the pollution of such substances to the environment. Finally, this invention uses fewer types of chemicals, reducing the cost of raw materials.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A single crystal texturing process in HJT cell production, characterized by: The single crystal texturing process comprises the following steps: The silicon wafer is washed with pure water to remove surface dirt; The silicon wafer is pre-cleaned; the pre-cleaning is cleaning the silicon wafer with a mixed solution of potassium hydroxide and hydrogen peroxide, the mass fraction of potassium hydroxide is not less than 60%, the mass fraction of hydrogen peroxide is not less than 20%, and the cleaning time is 4-6 min; After the pure water washing, the silicon wafer is texturized to form a uniform surface; After the pure water washing, the silicon wafer is cleaned with a mixed solution of potassium hydroxide and hydrogen peroxide; the mass fraction of potassium hydroxide in the mixed solution is not less than 60%, the mass fraction of hydrogen peroxide is not less than 20%, the cleaning temperature is 40-85°C, and the cleaning time is 4-6 min; After the pure water washing, the silicon wafer is cleaned with a mixed solution of hydrochloric acid and hydrogen peroxide; the mass fraction of hydrochloric acid in the mixed solution is not less than 30%, the mass fraction of hydrogen peroxide is not less than 20%, the cleaning temperature is 40-85°C, and the cleaning time is 4-6 min; After the pure water washing, the silicon wafer is cleaned with a hydrofluoric acid solution, and then washed with pure water again; The silicon wafer is slowly pulled up with pure water and pre-dried; The obtained silicon wafer is dried.

2. The mono-crystalline texturing process in HJT cell production according to claim 1, characterized in that: The texturing time of the silicon wafer is 600-900 s, and the texturing temperature is 65-85°C.

3. The mono-crystalline texturing process in HJT cell production according to claim 1, characterized in that: The silicon wafer is cleaned with a hydrofluoric acid solution, the mass fraction of the hydrofluoric acid solution is not less than 50%, and the cleaning time at room temperature is 50-200 s.

4. The mono-crystalline texturing process in HJT cell production according to claim 1, wherein: The silicon wafer is slowly pulled up with pure water, the pure water temperature is 30-60°C, and the cleaning time is more than 30 s.

5. The mono-crystalline texturing process in HJT cell production according to claim 1, wherein: The drying temperature of the silicon wafer is 30-90°C, and the drying time is 400-720 s.

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