Simple, efficient and low-cost back contact solar cell preparation process
By using technical means such as double-sided fleece making, laminated film deposition, laser patterning and low-temperature sintering in the preparation process of solar cells, the problems of traditional solar cells in high-temperature diffusion and passivation of dielectric films are solved, and efficient and low-cost back-contact solar cell preparation is achieved.
Patent Information
- Application Number
- CN202510375127.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-27
- Publication Date
- 2025-06-27
AI Technical Summary
Traditional solar cells will cause damage to silicon wafers during high temperature diffusion, passivation of dielectric films hinder carrier transmission, and silver materials limit the cost reduction and large-scale application of solar cells.
A P-type silicon wafer with a resistivity of 0.3 to 100Ω.cm was used for double-sided fleece production, and a laminated film of alumina and silicon nitride was deposited on the back of the silicon wafer. The interdigital interlaced pattern of P and N regions was formed by laser patterning and low-concentration hydrofluoric acid dip-washing, and the sintering treatment was performed using aluminum and base metal pastes at low temperatures.
It avoids silicon wafer damage caused by high temperature diffusion, ensures effective carrier transmission, reduces production costs, and improves the production efficiency and stability of solar cells.
Smart Images
Figure CN120224827A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of solar cell preparation, and specifically provides a simple, efficient and low-cost back-contact solar cell preparation process. Background Art
[0002] Back-contact cells are an innovative solar cell technology. Their main feature is that both the positive and negative metal contacts of the cell are placed on the back of the cell, while the front is completely exposed without metal grid lines blocking. This design significantly improves the light utilization efficiency, increases the effective power generation area, and enhances the photoelectric conversion efficiency of the cell.
[0003] In traditional solar cells, high-temperature diffusion is a key step in forming the P-N junction. However, high-temperature diffusion leads to high energy consumption, silicon wafer damage, and impurity introduction, affecting the performance and lifespan of the cell. Secondly, in traditional back-contact solar cells, the N region usually needs to be covered with a passivation dielectric film to protect the cell surface and reduce recombination losses. However, this dielectric film also becomes an obstacle to carrier transport, affecting the cell's performance. Finally, in traditional solar cell production, silver is a crucial material. Due to its high price and limited reserves, it restricts the cost reduction and large-scale application of solar cells, presenting limitations. Therefore, we propose a simple, efficient and low-cost back-contact solar cell preparation process to solve the above problems. Summary of the Invention
[0004] In view of the deficiencies of the prior art, the present invention provides a simple, efficient and low-cost back-contact solar cell preparation process, which solves the problems that high-temperature diffusion in traditional solar cells causes silicon wafer damage, the passivation dielectric film hinders carrier transport, and silver restricts the cost reduction and large-scale application of solar cells, presenting limitations.
[0005] To achieve the above objectives, the present invention is realized through the following technical solutions: A simple, efficient and low-cost back-contact solar cell preparation process, including the following steps;
[0006] Step 1: Use a P-type silicon wafer with a resistivity of 0.3 - 100 Ω·cm and perform double-sided texturing treatment;
[0007] Step 2: Deposit a stacked film of aluminum oxide and silicon nitride on both sides of the textured silicon wafer;
[0008] Step 3: Perform laser patterning treatment on the back of the silicon wafer, and the laser-treated area is the N-type region;
[0009] Step 4: In a chain equipment, perform single-sided low-concentration hydrofluoric acid dipping on the back of the silicon wafer, and use a water film to protect the front;
[0010] Step Five: In the N-type region on the back side, use a laser to remove most of the phosphosilicate glass on the polysilicon surface, but leave the polysilicon in the N-region with a width of 30 to 200 microns untreated by the laser, forming an interdigitated pattern of the P-region and the N-region, and etch away the polysilicon region treated by the laser in an alkaline solution;
[0011] Step Six: In the P-type region on the back side, use a laser to open the previously deposited stacked film;
[0012] Step Seven: Print aluminum paste in the P-region on the back side, and print base metal paste in the N-region, and perform sintering treatment at a temperature below 200 degrees to cure the paste and form good electrical contact with the silicon surface.
[0013] Preferably, the process of performing double-sided texturing treatment on the P-type silicon wafer in Step One is as follows;
[0014] I. Preliminary treatment: Remove impurities and oil stains on the silicon wafer surface through deionized water and chemical cleaning agents;
[0015] II. Primary texturing: Place the silicon wafer in an alkaline solution and perform etching treatment on it under the action of the alkaline solution;
[0016] III. Textured surface modification: Repeatedly clean the silicon wafer with hydrogen peroxide with a mass percentage concentration of 5%;
[0017] IV. Secondary texturing: Adjust parameters such as the concentration, temperature, or etching time of the alkaline solution according to the effect of the primary texturing, and the remaining process is the same as that of the primary texturing.
[0018] Preferably, the alkaline solution is sodium hydroxide.
[0019] Preferably, the alkaline solution is potassium hydroxide.
[0020] Preferably, for the deposition of the stacked film in Step Two, plasma-enhanced chemical vapor deposition is used to deposit an aluminum oxide film and a silicon nitride film on the silicon wafer in sequence.
[0021] Preferably, the specific implementation process of performing single-sided low-concentration hydrofluoric acid dip cleaning on the back side of the silicon wafer in Step Four is as follows;
[0022] I. Cover the front side with a water film: Uniformly spray a water film solution on the front side of the silicon wafer to form a thin and uniform water film;
[0023] II. Dip clean the back side: Spray low-concentration hydrofluoric acid on the back side of the silicon wafer to etch the back side of the silicon wafer;
[0024] III. Rinse and dry: Rinse the silicon wafer after dip cleaning with deionized water and dry it after completion.
[0025] Preferably, in step six, the silicon wafer is irradiated with a laser. By precisely controlling the laser energy, the previously deposited stacked film is opened to expose the silicon surface of the P region.
[0026] Preferably, the specific process of printing and sintering the silicon wafer in step seven is as follows:
[0027] First, print aluminum paste on the P region of the silicon wafer and perform low-temperature drying treatment on it;
[0028] Second, print base metal paste on the N region of the silicon wafer and perform low-temperature drying treatment on it;
[0029] Third, perform formal sintering. Send the dried silicon wafer into a sintering furnace and perform sintering treatment at a temperature below 200 degrees.
[0030] The present invention discloses a preparation process for a simple, efficient and low-cost back-contact solar cell, and its beneficial effects are as follows:
[0031] 1. The device uses a P-type silicon wafer substrate, abandons the traditional high-temperature diffusion process, and through innovative technical means, successfully avoids this high-energy-consuming link, greatly simplifying the manufacturing process. This simplification not only improves production efficiency but also reduces energy consumption, making the production of solar cells more environmentally friendly and economical.
[0032] 2. The device uses heavily doped n+-poly as the N-region material. This material property ensures the effective transmission of carriers even without a passivation dielectric film. At the same time, by using a base metal low-temperature paste with a specific work function for metallization, the smooth transmission of carriers is further ensured, without affecting the performance of the battery.
[0033] 3. The device uses low-temperature aluminum paste for metallization. This paste not only has a low cost but also can achieve good metallization effects at low temperatures. In addition, laser-assisted sintering technology can be selected to further improve the bonding force between the metallization and the silicon wafer, ensuring the stability and reliability of the battery. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0035] Figure 1 It is a schematic diagram of the overall structure flow of the present invention;
[0036] Figure 2Schematic diagram of the principle of the present invention;
[0037] Figure 3 Schematic diagram of the double-sided texturing process of the P-type silicon wafer of the present invention;
[0038] Figure 4 Schematic diagram of the hydrofluoric acid dip cleaning process of the present invention;
[0039] Figure 5 Schematic diagram of the silicon wafer printing and sintering process of the present invention. Detailed implementation manners
[0040] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.
[0041] By providing a simple, efficient and low-cost back-contact solar cell preparation process in the embodiments of the present application, the problems that high-temperature diffusion of traditional solar cells will cause damage to silicon wafers, the passivation dielectric film will hinder the transmission of carriers, and silver will limit the cost reduction and large-scale application of solar cells, and there are limitations are solved.
[0042] To better understand the above technical solutions, the above technical solutions will be described in detail below in conjunction with the accompanying drawings of the specification and specific implementation manners.
[0043] The embodiments of the present invention disclose a simple, efficient and low-cost back-contact solar cell preparation process.
[0044] Example 1:
[0045] The embodiments of the present invention disclose a simple, efficient and low-cost back-contact solar cell preparation process. According to the Figure 1-2 shown, Step 1: Use a P-type silicon wafer with a resistivity of 0.3 to 100 Ω·cm for double-sided texturing treatment;
[0046] Step 2: Deposit a stacked film of aluminum oxide and silicon nitride on both sides of the textured silicon wafer;
[0047] Step 3: Perform laser patterning on the back of the silicon wafer, and the laser treatment area is the N-type area;
[0048] Step 4: In a chain-type device, perform single-sided low-concentration hydrofluoric acid dip cleaning on the back of the silicon wafer, and use a water film to protect the front side;
[0049] Step Five: In the N-type region on the back, use a laser to remove most of the phosphosilicate glass on the polysilicon surface, but leave the polysilicon in the N-region with a width of 30 to 200 microns untreated by the laser, forming an interdigital staggered pattern between the P-region and the N-region, and etch away the polysilicon region treated by the laser in an alkaline solution;
[0050] Step Six: In the P-type region on the back, use a laser to open the previously deposited stacked film;
[0051] Step Seven: Print aluminum paste in the P-region on the back, and print base metal paste in the N-region, and perform sintering treatment at a temperature below 200 degrees to cure the paste and form good electrical contact with the silicon surface.
[0052] The alkaline solution is sodium hydroxide, the alkaline solution is potassium hydroxide, for the deposition of the stacked film in Step Two, plasma-enhanced chemical vapor deposition is used to sequentially deposit an aluminum oxide film and a silicon nitride film on the silicon wafer. In Step Six, the silicon wafer is irradiated with a laser, and by precisely controlling the laser energy, the previously deposited stacked film is opened to expose the silicon surface in the P-region.
[0053] In this embodiment, when the device produces a battery, a P-type silicon wafer with a resistivity in the range of 0.3 to 100 Ω·cm is selected as the substrate. Then, the silicon wafer is subjected to double-sided texturing. The texturing process increases the surface roughness of the silicon wafer by chemical or mechanical methods to improve its light absorption capacity. Double-sided texturing can ensure that both sides of the silicon wafer can effectively absorb light and improve the conversion efficiency of the solar cell. Immediately after that, on the textured silicon wafer, a stacked film of aluminum oxide and silicon nitride is deposited. The stacked film effectively reduces the recombination loss on the silicon wafer surface, increases the carrier lifetime, and at the same time reduces the reflection of light, enabling more light to enter the silicon wafer and be absorbed. The structure and thickness of the stacked film can be optimized according to specific application requirements to achieve the best passivation and antireflection effects. Next, specific patterns are formed on the back N-type region of the silicon wafer by laser. These patterns are used for subsequent process steps such as metallization or etching to form the required circuit structure. Then, in a chain-type device, the back of the silicon wafer is subjected to single-sided low-concentration hydrofluoric acid dipping. Hydrofluoric acid can remove the oxide layer or contaminants on the silicon wafer surface and prepare for subsequent process steps. At the same time, in order to protect the front of the silicon wafer from being eroded by hydrofluoric acid, a water film can be coated on the front as a protective layer. Immediately after that, on the N-type region of the back of the silicon wafer, most of the phosphosilicate glass on the polysilicon surface is removed by laser. However, the N-region polysilicon with a width of 30 to 200 microns is not laser-treated, forming a finger-like interleaved pattern between the P region and the N region. This patterning process helps the subsequent metallization step, enabling the metal electrodes to contact the P region and the N region more accurately. Subsequently, the polysilicon region treated by laser is etched off in an alkaline solution to further form the required circuit structure. In the P-type region on the back, the previously deposited stacked film is opened by laser. This step is to expose the silicon surface of the P region so that the subsequent metallization step can proceed smoothly. Precise control of the laser can ensure that only the required area is opened without affecting the passivation and antireflection effects of other parts. Finally, aluminum paste is printed on the P region on the back, and base metal pastes such as nickel paste or tin bismuth are printed on the N region. The aluminum paste and the base metal pastes are used to form the metal electrodes of the P region and the N region respectively. These pastes are selected because they have good sintering performance and electrical conductivity at low temperatures. Subsequently, a sintering treatment is carried out at a temperature below 200 °C to cure the paste and form good electrical contact with the silicon surface. In this way, the metallization step of the solar cell is completed, preparing for subsequent encapsulation and testing.
[0054] Example 2:
[0055] An embodiment of the present invention discloses a simple, efficient, and low-cost back-contact solar cell preparation process. According to the attached Figure 1 , 3 shown, Step 1: Use a P-type silicon wafer with a resistivity of 0.3 to 100 Ω·cm and perform double-sided texturing treatment.
[0056] Step 2: Deposit a stacked film of aluminum oxide and silicon nitride on both sides of the textured silicon wafer.
[0057] Step 3: Perform laser patterning on the back side of the silicon wafer, and the laser-treated area is the N-type region.
[0058] Step 4: In a chain-type device, dip the back side of the silicon wafer in low-concentration hydrofluoric acid for single-sided cleaning, and protect the front side with a water film.
[0059] Step 5: In the N-type region on the back side, use a laser to remove most of the phosphosilicate glass on the surface of the polysilicon, but keep the polysilicon in the N-region with a width of 30 to 200 microns from being laser-treated, forming an interdigitated pattern of P-region and N-region, and etch away the laser-treated polysilicon region in an alkaline solution.
[0060] Step 6: In the P-type region on the back side, use a laser to open the previously deposited stacked film.
[0061] Step 7: Print aluminum paste on the P-region on the back side, and print base metal paste on the N-region, and perform sintering treatment at a temperature below 200 °C to cure the paste and form good electrical contact with the silicon surface.
[0062] The process of double-sided texturing treatment for the P-type silicon wafer in Step 1 is as follows: First, preliminary treatment, remove impurities and oil stains on the surface of the silicon wafer through deionized water and chemical cleaning agents; Second, primary texturing, put the silicon wafer into an alkaline solution and perform etching treatment under the action of the alkaline solution; Third, surface modification of the texture, repeatedly clean the silicon wafer with hydrogen peroxide with a mass percentage concentration of 5%; Fourth, secondary texturing, adjust parameters such as the concentration, temperature or etching time of the alkaline solution according to the effect of the primary texturing, and the remaining processes are the same as those of the primary texturing.
[0063] In this embodiment, first, deionized water and chemical cleaning agents are used to thoroughly clean the silicon wafers to remove impurities and oil stains on the surface of the silicon wafers. The cleaned silicon wafers need to be kept dry to avoid secondary contamination. Immediately afterwards, according to the process requirements, an alkaline solution with a certain concentration is prepared. During the preparation process, the concentration and temperature of the solution need to be strictly controlled. Then, the cleaned silicon wafers are placed in the alkaline solution for etching treatment. During the etching process, a reaction occurs between the surface of the silicon wafer and the alkaline solution, forming a pyramid-like structure. By controlling parameters such as the etching time, temperature, and concentration of the alkaline solution, the size and density of the pyramids can be controlled. The etched silicon wafers are taken out and cleaned with deionized water to remove the residues on the surface of the silicon wafers. Then, a drying device is used to dry the silicon wafers. The silicon wafers are cleaned with hydrogen peroxide with a mass percentage concentration of 5% to modify the surface texture structure and improve the uniformity of the deposition of the silicon nitride film. To ensure the surface texture effect of the wire arrangement, this step needs to be repeated multiple times. After the cleaning is completed, the silicon wafers are cleaned again with deionized water to ensure that the surface of the silicon wafers is clean and free of impurities. The secondary texturing is the same as the first texturing step, but the parameters such as the concentration, temperature, or etching time of the alkaline solution need to be adjusted according to the effect of the first texturing. After the texturing is completed, the silicon wafers are finally cleaned with deionized water to remove all the residues on the surface of the silicon wafers. A drying device is used to dry the silicon wafers, and preparations are made for the subsequent battery preparation process. The textured silicon wafers are subjected to quality inspection, including indicators such as surface morphology, light reflectivity, and photoelectric conversion efficiency. Unqualified silicon wafers need to be reworked or scrapped. It should be noted that the concentration and temperature of the alkaline solution are the key factors affecting the texturing effect. Excessive concentration and temperature will cause excessive etching on the surface of the silicon wafer, forming too large pyramid structures and reducing the light trapping effect; while too low concentration and temperature will result in insufficient etching and unable to form effective pyramid structures.
[0064] Example 3:
[0065] An embodiment of the present invention discloses a simple, efficient, and low-cost back-contact solar cell preparation process. According to the attached Figure 1 、 4 shown, Step 1: Use a P-type silicon wafer with a resistivity of 0.3 to 100 Ω·cm for double-sided texturing treatment;
[0066] Step 2: Deposit a stacked film of aluminum oxide and silicon nitride on both sides of the textured silicon wafer;
[0067] Step 3: Perform laser patterning treatment on the back of the silicon wafer, and the laser treatment area is the N-type area;
[0068] Step 4: In a chain equipment, perform single-sided low-concentration hydrofluoric acid dipping on the back of the silicon wafer, and use a water film to protect the front side;
[0069] Step 5: On the N-type region of the back side, use a laser to remove most of the phosphosilicate glass on the surface of the polysilicon, but leave the polysilicon in the N region with a width of 30 to 200 microns untreated by the laser, forming an interdigitated pattern of P and N regions, and etch away the polysilicon region treated by the laser in an alkaline solution;
[0070] Step 6: On the P-type region of the back side, use a laser to open the previously deposited stacked film;
[0071] Step 7: Print aluminum paste on the P region of the back side, and print base metal paste on the N region, and perform sintering treatment at a temperature below 200 °C to cure the paste and form good electrical contact with the silicon surface.
[0072] The specific implementation process of the single-sided low-concentration hydrofluoric acid dip cleaning of the back side of the silicon wafer in Step 4 is as follows: First, cover the front side with a water film, evenly spray the water film solution on the front side of the silicon wafer to form a thin and uniform water film; Second, dip clean the back side, spray low-concentration hydrofluoric acid on the back side of the silicon wafer to corrode the back side of the silicon wafer; Third, rinse and dry, rinse the silicon wafer after dip cleaning with deionized water and dry it after completion.
[0073] In this implementation, when the device is in use, place the silicon wafer on the conveyor belt of the chain equipment to ensure that the silicon wafer is stable and not tilted, and evenly spray the water film solution on the front side of the silicon wafer to form a thin and uniform water film. The function of this water film is to protect the front side of the silicon wafer from being corroded by hydrofluoric acid during the subsequent hydrofluoric acid dip cleaning process. After the water film coating is completed, check the water film to ensure that the water film is completely covered without any missed coating or accumulation. Then, when the silicon wafer is conveyed to the hydrofluoric acid dip cleaning area, evenly spray the low-concentration hydrofluoric acid solution on the back side of the silicon wafer through the nozzle, control the spraying amount, spraying speed and spraying time of the hydrofluoric acid solution to ensure that the back side of the silicon wafer is fully corroded while avoiding corrosion of the front side. The main purpose of the hydrofluoric acid solution dip cleaning is to remove the phosphosilicate glass or other impurities on the back side of the silicon wafer while maintaining the integrity and performance of the front side. After the hydrofluoric acid dip cleaning is completed, immediately rinse the silicon wafer with deionized water to remove the residual hydrofluoric acid solution and reaction products, and then send the silicon wafer into the drying equipment for drying treatment to remove the moisture on the surface of the silicon wafer and prepare for the next processing step.
[0074] The embodiment of the present invention discloses a simple, efficient and low-cost back-contact solar cell preparation process. According to the attached Figure 1 、 5 shown, Step 1: Use a P-type silicon wafer with a resistivity of 0.3 to 100 Ω·cm and perform double-sided texturing treatment;
[0075] Step 2: Deposit a stacked film of aluminum oxide and silicon nitride on both sides of the textured silicon wafer;
[0076] Step 3: Perform laser patterning on the backside of the silicon wafer, and the laser processing area is the N-type region;
[0077] Step 4: In a chain equipment, perform single-sided low-concentration hydrofluoric acid dip cleaning on the backside of the silicon wafer, and use a water film to protect the front side;
[0078] Step 5: In the N-type region on the backside, use a laser to remove most of the phosphosilicate glass on the polysilicon surface, but keep the polysilicon in the N region with a width of 30 to 200 microns not being laser processed, forming an interdigitated staggered pattern between the P region and the N region, and etch away the laser-processed polysilicon region in an alkaline solution;
[0079] Step 6: In the P-type region on the backside, use a laser to open the previously deposited stacked film;
[0080] Step 7: Print aluminum paste on the P region on the backside, and print base metal paste on the N region, and perform sintering treatment at a temperature below 200 °C to cure the paste and form good electrical contact with the silicon surface.
[0081] The specific process of printing and sintering the silicon wafer in Step 7 is as follows: First, print aluminum paste, print the aluminum paste on the P region of the silicon wafer, and perform low-temperature drying treatment on it; Second, print base metal paste, print the base metal paste on the N region of the silicon wafer, and perform low-temperature drying treatment on it; Third, perform formal sintering, send the dried silicon wafer into a sintering furnace, and perform sintering treatment at a temperature below 200 °C.
[0082] In this embodiment, it should be noted that the base metal paste is nickel paste or tin bismuth. During formal processing, place the silicon wafer that has undergone pre-treatment steps such as double-sided texturing, stacked film deposition, and backside laser patterning on the printing platform of the printing machine. For P region printing, ensure the alignment of the silicon wafer with the printing stencil, use a squeegee to evenly coat the aluminum paste on the pattern of the printing stencil, and then transfer the aluminum paste to the P region of the silicon wafer through the mesh holes of the stencil. During the printing process, control the pressure, speed, and angle of the squeegee to ensure the uniformity and accuracy of printing. After printing, send the silicon wafer into a drying device and perform drying treatment at a low temperature to remove the organic solvent in the aluminum paste and prevent foaming during sintering. The N region printing is the same as the P region printing. Ensure the alignment of the silicon wafer with the printing stencil, use a squeegee to evenly coat the nickel paste or tin bismuth paste on the pattern of the printing stencil, and then transfer the paste to the N region of the silicon wafer. Also, pay attention to the pressure, speed, and angle of the squeegee, and then send it into a drying device for drying. Send the dried silicon wafer into a sintering furnace and perform sintering treatment at a temperature below 200 °C. During the sintering process, the organic carrier in the paste is burned out, the metal powder forms an ohmic contact with the silicon wafer surface, and at the same time, the glass powder melts to form a protective layer, improving the adhesion and stability of the electrode. The sintering temperature and time need to be adjusted according to the composition and performance of the paste to ensure the sintering quality and efficiency.
[0083] The foregoing has shown and described 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 by the above embodiments, and what is described in the above embodiments and the specification is only to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.
Claims
1. A simple, efficient and low-cost back-contact solar cell preparation process, characterized in that: The steps include: Step 1: Use a P-type silicon wafer with a resistivity of 0.3 to 100 Ω.cm and perform double-sided texturing; Step 2: Depositing a laminated film of aluminum oxide and silicon nitride on both sides of the silicon wafer after the texturing treatment; Step 3: Perform laser patterning on the back of the silicon wafer, where the laser processed area is the N-type area; Step 4: In the chain equipment, the back side of the silicon wafer is cleaned with low-concentration hydrofluoric acid, and the front side is protected with a water film; Step 5: In the N-type region on the back side, a laser is used to remove the phosphosilicate glass on the surface of most of the polysilicon, but the N-region polysilicon with a width of 30 to 200 microns is retained without being laser-processed, forming a cross-finger-shaped staggered pattern of the P region and the N region, and the laser-processed polysilicon region is etched away in an alkaline solution; Step 6: Use laser to open the previously deposited stacked film in the P-type region on the back side; Step seven: print aluminum paste on the P area on the back, and print base metal paste on the N area (multiple metals such as nickel and its alloys, tin and its alloys, tin-clad copper, indium-containing alloys, etc.), and sinter at a temperature below 200 degrees to solidify the paste and form good electrical contact with the silicon surface.
2. A simple, efficient and low-cost back-contact solar cell preparation process according to claim 1, characterized in that: The process of double-sided texturing of the P-type silicon wafer in step 1 is as follows:
1. Preliminary treatment: remove impurities and oil stains on the surface of the silicon wafer using deionized water and chemical cleaning agents; Second, primary texturing, placing the silicon wafer in an alkaline solution and subjecting it to corrosion treatment under the action of the alkaline solution; 3. Suede modification: repeatedly use 5% hydrogen peroxide to clean the silicon wafer; Fourth, the second texturing process: adjust the concentration, temperature and corrosion time parameters of the alkaline solution according to the effect of the first texturing process. The rest of the process is the same as the first texturing process.
3. A simple, efficient and low-cost back-contact solar cell preparation process according to claim 2, characterized in that: The alkaline solution is sodium hydroxide.
4. A simple, efficient and low-cost back-contact solar cell preparation process according to claim 2, characterized in that: The alkaline solution is potassium hydroxide.
5. A simple, efficient and low-cost back-contact solar cell preparation process according to claim 1, characterized in that: The stacked film deposition in step 2 adopts plasma enhanced chemical vapor deposition to sequentially deposit an aluminum oxide film and a silicon nitride film on the silicon wafer.
6. A simple, efficient and low-cost back-contact solar cell preparation process according to claim 1, characterized in that: The specific implementation process of performing single-sided low-concentration hydrofluoric acid cleaning on the back side of the silicon wafer in step 4 is as follows:
1. Cover the front side with water film. Spray the water film solution evenly on the front side of the silicon wafer to form a thin and uniform water film. Second, back cleaning: spray low-concentration hydrofluoric acid on the back of the silicon wafer to corrode the back of the silicon wafer; 3. Rinse and dry. After the cleaning, the silicon wafer is rinsed with ionized water and then dried.
7. A simple, efficient and low-cost back-contact solar cell preparation process according to claim 1, characterized in that: In the step six, a laser is used to irradiate the silicon wafer, and the previously deposited stacked film is opened by precisely controlling the laser energy to expose the silicon surface of the P region.
8. The simple, efficient and low-cost back-contact solar cell preparation process according to claim 1, characterized in that: The specific process of printing and sintering the silicon wafer in step seven is as follows:
1. Printing aluminum paste: Printing aluminum paste on the P area of the silicon wafer and subjecting it to low-temperature drying; 2. Printing base metal slurry: Printing the base metal slurry on the N region of the silicon wafer and performing low temperature drying treatment on the base metal slurry; 3. Formal sintering: The dried silicon wafer is sent into the sintering furnace and sintered at a temperature below 200 degrees.