A method of manufacturing a topcon and bc photovoltaic cell

Abstract

The application discloses a method for preparing a TOPCon and BC photovoltaic cell, a hot-melt wax functional mask is prepared on the surface of a crystalline silicon wafer through an industrial inkjet printing mode, directional etching windowing of a silicon wafer silicon nitride passivation layer is first completed relying on the mask, then the hot-melt wax mask is directly used as an insulating barrier layer to perform cell metal electrode plating processing, and finally all the hot-melt wax masks are quickly stripped and dissolved by means of an alkaline solution. The application realizes single mask material adaptation etching and plating dual photovoltaic core processes, simplifies the production process, reduces equipment investment and consumable cost, simultaneously replaces the traditional screen printing silver paste process with the electrode plating process, effectively reduces silver consumption, optimizes the electrode structure, significantly improves the photoelectric conversion efficiency and mass production yield of the TOPCon cell and the BC back contact cell, has strong process adaptability and low landing difficulty, can be applied to large-scale industrial production of high-efficiency crystalline silicon photovoltaic cells, and promotes the development of the photovoltaic industry in the aspects of silver-free, low cost and high efficiency.

Description

Technical Field

[0001] This invention relates to the field of solar photovoltaic cell manufacturing technology, and in particular to a method for preparing TOPCon and BC photovoltaic cells. Background Technology

[0002] Currently, in the global crystalline silicon photovoltaic market, TOPCon cells and BC back-contact cells have become the mainstream development direction for high-efficiency cells. These two types of cells, with their excellent photoelectric conversion efficiency and mass production potential, are gradually dominating the mid-to-high-end photovoltaic market. At present, the mainstream electrode preparation method for these two types of cells in the industry is still mainly screen-printed silver paste. Although this process is mature and easy to implement, it has many industry pain points, severely restricting cost reduction, efficiency improvement, and performance upgrades of cells.

[0003] 1. High cost of silver paste consumables: As a precious metal, silver prices fluctuate frequently, and the silver paste consumption of screen printing process is huge. The average silver consumption per cell accounts for 15%-20% of the total cost of the battery, which greatly increases the manufacturing cost of a single cell and goes against the industry's trend of silver-free and low-cost development.

[0004] 2. Bottlenecks in electrode performance: There are obvious process limits in the thickness and aspect ratio of screen-printed grid lines. The width of conventional grid lines is difficult to exceed 20μm, and the aspect ratio is less than 2:1, which limits the conductivity of the electrodes, resulting in high series resistance inside the battery and making it difficult to further improve the photoelectric conversion efficiency of the battery.

[0005] 3. Difficulty in controlling production yield: Printing paste is easily affected by factors such as environmental humidity and screen wear, resulting in defects such as broken grids, incomplete printing, grid line misalignment, and ink overflow, making it difficult to stabilize the yield of finished battery products above 98%, increasing mass production losses.

[0006] 4. Poor adaptability of traditional masking processes: To overcome the bottleneck of screen printing, the industry is gradually promoting silver-free / low-silver electroplating electrode processes. However, low-cost, easy-to-prepare, and easy-to-remove masking materials suitable for electroplating processes are currently scarce. Traditional photoresist masking processes are cumbersome, raw materials are expensive, and the removal conditions are stringent (requiring high temperature or organic solvents). They have high energy consumption and are prone to damaging the silicon wafer passivation layer, making them unsuitable for the large-scale, low-cost mass production needs of photovoltaics. Conventional masking materials cannot simultaneously meet the dual process requirements of silicon nitride passivation layer etching protection and electroplating insulation barrier, which seriously restricts the widespread application of electroplating electrode processes in TOPCon and BC cell fields.

[0007] Based on the above industry status quo, there is an urgent need for a mask preparation process that can achieve integrated "etching protection-electroplation insulation", low cost, easy mass production, and high adaptability, to solve the pain points of existing technologies, promote the large-scale implementation of TOPCon and BC battery electroplating processes, and achieve the dual goals of reducing battery costs and improving efficiency. This invention was developed for this purpose. Summary of the Invention

[0008] The purpose of this invention is to provide a method for preparing TOPCon and BC photovoltaic cells, aiming to overcome the inherent defects in the electrode preparation processes of existing TOPCon and BC photovoltaic cells, and to provide a photovoltaic cell preparation process that is simple, low-cost, has high pattern precision, and strong adaptability. The core of this invention is to utilize inkjet-printed hot-melt wax as an integrated functional mask, sequentially completing two core processes: silicon nitride etching and metal electrode electroplating. This eliminates the need for secondary mask replacement and coating, and finally removes the mask through rapid peeling with conventional alkaline solution. This completely replaces the traditional screen-printed silver paste electrode preparation method, achieving the R&D and mass production goals of reducing costs and increasing efficiency in photovoltaic cell production, simplifying the process, improving photoelectric conversion efficiency and mass production yield. Simultaneously, it reduces the difficulty of production line modification, adapts to the rapid upgrade of existing mass production lines, and promotes the widespread adoption of silver-free electroplating processes in the field of high-efficiency photovoltaic cells.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A method for preparing TOPCon and BC photovoltaic cells includes the following steps:

[0011] Step 1: Pre-processing of silicon wafers;

[0012] Select qualified TOPCon or BC back-contact silicon wafers that have completed texturing, diffusion, oxide layer preparation, and passivation layer (silicon nitride passivation layer) deposition. The silicon wafer surface should be free of damage, scratches, and impurities. Perform fine dust and oil removal treatment on the silicon wafer surface using plasma cleaning + pure water rinsing to remove residual trace contaminants and water stains. Then, send it to a hot air drying oven for low-temperature drying (drying temperature 60-80℃, drying time 2-3min) to ensure that the silicon wafer surface is clean, flat, and free of watermarks. This improves the adhesion stability of hot melt wax inkjet printing and avoids subsequent printing defects such as peeling, misalignment, defects, and bubbles.

[0013] Step 2: High-precision inkjet printing of hot melt wax molding mask;

[0014] Using professional photovoltaic industrial inkjet printing equipment (positioning accuracy ±12μm, printing resolution above 300dpi), the prepared hot melt wax functional ink is precisely sprayed onto designated areas of the silicon wafer according to the pre-imported cell grid pattern, electrode pattern, and BC structure window trajectory (TOPCon cells focus on the front fine grid and main grid areas, while BC cells focus on the back electrode window area). After printing, the hot melt wax pattern is cured and shaped at low temperature using a temperature-controlled curing device (curing temperature 15-25℃, curing time 1-5s), so that the hot melt wax adheres tightly to the silicon wafer surface, forming a stable, clear-edged, and uniformly thick (thickness controlled between 5-40μm) solid hot melt wax mask. The unprinted areas completely expose the silicon wafer substrate, reserving precise process channels for subsequent etching and electroplating, ensuring that the etching and electroplating processes are precise and controllable.

[0015] Step 3: Use a hot-melt wax mask to etch and open windows in the silicon nitride layer;

[0016] The silicon wafer with the printed hot melt wax mask is fed into a wet etching machine. The appropriate etching process is selected according to the battery type (wet etching is preferred for TOPCon and BC batteries). The silicon nitride passivation film on the exposed part of the silicon wafer surface is removed by directional etching. During the etching process, the hot melt wax mask area has extremely strong etching resistance, which can completely protect the underlying silicon nitride layer and silicon wafer substrate from etching damage. The windowing operation is accurately completed in the specified positions such as the electrode area required for TOPCon and BC batteries. The etching parameters are strictly controlled (hydrofluoric acid solution is used for wet etching, etching temperature is 20-25℃, and etching time is 600-700s) to ensure accurate window size (window width is controlled within 20-300μm), smooth edges, and no over-etching or under-etching.

[0017] Step 4: Conduct metal electroplating using hot melt wax as an insulating mask;

[0018] After the silicon nitride etching and windowing process is completed, there is no need to remove the hot melt wax mask. The silicon wafer is directly transferred to the photovoltaic cell electroplating production line. Metal electrode deposition is carried out using either copper electroplating (suitable for silver-free requirements) or nickel-copper electroplating (suitable for low-silver requirements). Utilizing the excellent insulating properties of the hot melt wax itself, it serves as an electroplating isolation and protective mask, effectively preventing contact between the electroplating solution and non-target areas. Metal layer deposition and electroplating are performed only on the etched exposed areas of the silicon wafer, precisely shaping the positive and negative electrodes, fine grid electrodes, and back contact electrodes of the cell. Strict control of electroplating parameters (electroplating temperature below 35℃, current density 1-3A / dm², electroplating time 5-20min) ensures that the electrode pattern is regular and the conductive layer thickness is uniform (metal layer thickness controlled at 5-15μm). This perfectly adapts to the electroplating shaping requirements of various structures such as TOPCon fine grid electrodes, BC back electrodes, and front SE electrodes, avoiding defects such as incomplete plating, over-plating, and electrode detachment.

[0019] Step 5: Use alkaline solution to peel off and dissolve the hot melt wax mask at a constant temperature;

[0020] After the electroplating deposition of the battery metal electrodes is completed, the silicon wafer is placed in an alkaline cleaning tank and immersed in a prepared weakly alkaline solution (sodium hydroxide solution, mass concentration 3%-5%) at a constant temperature (immersion temperature 40-50℃, immersion time 90-120s). Utilizing the physicochemical properties of hot-melt wax material, which easily swells and decomposes in the presence of alkali, all hot-melt wax mask layers on the silicon wafer surface are quickly and completely peeled off and fully dissolved in the alkaline solution, leaving no residual wax. Subsequently, a three-stage pure water overflow rinsing (each rinsing time 10-15s) and hot air drying (drying temperature 70-80℃, drying time 10-15min) are performed to thoroughly remove any trace amounts of residual wax and alkali from the silicon wafer surface. The entire process does not corrode the silicon wafer substrate, passivation layer, or formed metal electrodes, ensuring the stable performance of the battery in the future.

[0021] Step 6: Subsequent finished product manufacturing process;

[0022] After the silicon wafers are removed and cleaned, they undergo a series of conventional processes, including annealing (annealing temperature 300-350℃, annealing time 30-40min to improve the adhesion between the metal electrodes and the silicon wafers), electrode inspection (using EL detection and electrical testing to screen out defective products), appearance sorting (removing silicon wafers with surface scratches, damage, and defective electrodes), and encapsulation, to finally manufacture high-performance TOPCon photovoltaic cells and BC back contact photovoltaic cell products.

[0023] Compared with existing technologies, this invention has the following advantages: 1. Significantly reduces battery production costs: This invention fully adopts electroplating metal electrode technology to replace the traditional high-cost screen printing silver paste technology, greatly reducing the amount of precious metal silver used (silver-free electroplating can achieve zero silver consumption, and low-silver electroplating can reduce silver consumption by more than 80%), significantly compressing the production cost of a single photovoltaic cell from the raw material end; at the same time, hot melt wax material is inexpensive and has no VOC emissions, making it environmentally friendly, and the process steps are simplified, further reducing production time and energy consumption costs, which is in line with the industry's trend of silver-free and low-cost development.

[0024] 2. Significantly improves battery photoelectric conversion efficiency: Inkjet printing combined with electroplating can produce fine grid line electrodes with better aspect ratios (up to 1:1 or higher) and stronger conductivity, effectively reducing the internal series resistance of the battery, reducing the light-blocking area of ​​the grid lines, and improving the light absorption utilization rate of the silicon wafer; at the same time, the high precision of hot melt wax mask etching can optimize the contact performance between the electrode and the silicon wafer, reduce contact resistance, and comprehensively improve the photoelectric conversion efficiency and output power of TOPCon and BC batteries. Compared with traditional screen printing processes, battery efficiency can be improved by 0.3%-0.8%.

[0025] 3. High production yield and strong process stability: The hot melt wax mask has uniform molding and stable protective performance. It is not easy to have defects such as breakage, peeling, or displacement during etching and electroplating. It effectively reduces the occurrence of defects such as grid breakage, false printing, and missed plating. The yield of finished battery products can be stabilized at over 98.5%, improving the stability of mass production and reducing production losses.

[0026] 4. Low difficulty in production line transformation and strong feasibility: The overall process can be seamlessly connected to the existing mainstream TOPCon and BC battery mass production lines without large-scale reconstruction of the production line. The process upgrade can be completed by simply adding high-precision inkjet printing equipment, electroplating equipment and alkaline stripping equipment. The technical transformation investment is small, the cycle is short, the production speed is fast, and the commercialization and promotion value is extremely high.

[0027] 5. Green and environmentally friendly with high production safety: The hot melt wax ink formula is environmentally friendly and non-toxic, contains no harmful organic solvents, and there is no volatilization of high-risk organic solvents during the production process; the alkaline peeling process is mature and pollution-free, and the alkaline solution after peeling can be recycled after treatment, which meets the green and low-carbon production standards of the photovoltaic industry, while ensuring a safe and clean production environment and reducing environmental treatment costs.

[0028] 6. Strong process compatibility and adaptability to future upgrades: This process is compatible with the trend of silver-free and low-silver electroplating, and can adapt to the production needs of new generation high-efficiency batteries such as ultra-fine grids and thin sheets. At the same time, the printing pattern, etching parameters and electroplating parameters can be flexibly adjusted to adapt to the production of TOPCon and BC batteries with different specifications and performance requirements, leaving room for future upgrades of the production line. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to specific embodiments.

[0030] Example 1

[0031] TOPCon battery mass production operation case study;

[0032] Project Overview: This case study was applied to the mass production line of a photovoltaic company's 182mm TOPCon cells. The original process involved screen printing silver paste electrodes. This project replaced the original screen printing process with the process of this invention, while keeping the other front-end and back-end processes unchanged. The study verified the adaptability, cost reduction effect, and efficiency gain of this process in TOPCon cell mass production. This batch production involved 10,000 silicon wafers, with a control group of 10,000 wafers (using traditional screen printing). The construction environment was a Class 10,000 cleanroom with a temperature of 25°C and humidity of 55%, perfectly conforming to the standard operating conditions for photovoltaic mass production.

[0033] Construction parameters and procedures:

[0034] (1) Pre-treatment of silicon wafers: 182mm N-type TOPCon silicon wafers (thickness 130μm) were selected. After texturing, diffusion, tunneling oxide layer (thickness 1.3nm), polycrystalline silicon layer (thickness 140nm), and silicon nitride passivation layer (thickness 80nm) were deposited, plasma cleaning + pure water rinsing was carried out, and hot air drying at 65℃ for 20min was performed. The surface of the silicon wafer was clean and free of impurities.

[0035] (2) Inkjet printing hot melt wax mask: High-precision inkjet printing equipment (positioning accuracy ±10μm) is used, the printing opening is 25μm, the wax film thickness is 25μm, and the printing pattern is the fine grid and main grid trajectory of the front / back of the TOPCon battery; the curing temperature is 20℃, the curing time is 0.7s, and the wax film edge is clear, without ink overflow or peeling.

[0036] (3) Silicon nitride etching window: Hydrofluoric acid (49% concentration): Nitric acid (68% concentration): Deionized water = 1:2:10~1:3:12 (volume ratio); Nitric acid can adjust the etching rate and inhibit the corrosion of silicon substrate by HF, improve etching selectivity, and avoid damage to silicon wafers. Etching temperature: 25~30℃ (constant temperature control in mass production workshop). Compared with room temperature etching, this temperature range can ensure etching efficiency and avoid uncontrolled etching rate caused by excessive temperature. Etching time: 120~180s (2~3min); The etching rate of the mixed solution on 80nm silicon nitride is about 0.4~0.7nm / s. Combined with the mass production efficiency requirements, controlling it within this time range can achieve thorough etching without affecting subsequent processes.

[0037] (4) Metal electroplating: The process of electroplating nickel and copper is adopted. The electroplating temperature is 40℃, the current density is 2A / dm², the electroplating time is 45min, the nickel thickness is 1 micrometer as the seed layer, the copper electrode thickness is 8μm, the electrode pattern is regular and there is no plating omission.

[0038] (5) Alkaline dewaxing: Use 4% sodium hydroxide solution, soak at 45℃ for 100s and operate with auxiliary equipment such as circulation bubbling, the hot melt wax is completely dissolved and peeled off; rinse with three-stage pure water, dry with hot air at 75℃ for 22min, and there is no wax or alkaline residue on the surface of the silicon wafer.

[0039] (6) Post-processing: Annealing at 320℃ for 35 minutes, EL testing, electrical testing, appearance sorting and packaging to obtain TOPCon battery finished products.

[0040] Construction test results:

[0041] Compared with the traditional screen-printed control group, the TOPCon battery prepared in this embodiment shows the following improvements: the average silver consumption per cell decreased from 90mg to 0mg (no silver plating), reducing the cost per cell by 1.8 yuan; the photoelectric conversion efficiency increased from 25.2% to 25.65%, an efficiency gain of 0.45%; the series resistance decreased from 1.2mΩ to 0.8mΩ; the yield rate increased from 95.8% to 98.7%; the average energy consumption per cell decreased by 13%; there were no defects such as silicon wafer damage or electrode detachment, fully meeting the requirements for mass production; and the equipment investment cost can be recovered within 3 months after the technical upgrade.

[0042] Example 2

[0043] Case study of refined construction of BC back contact batteries;

[0044] Project Overview: This case study is applied to a high-efficiency photovoltaic cell R&D production line. For 166mm BC back-contact cells, the process of this invention is used to prepare the back electrode window and electroplating electrode, adapting to the refined back contact structure requirements of BC cells and verifying the adaptability and performance advantages of this process in BC cells. This project involves the batch production of 3000 silicon wafers in a Class 1000 cleanroom at 23℃ and 52% humidity. The focus is on verifying the windowing accuracy of the hot-melt wax mask and the electroplating insulation effect.

[0045] Construction parameters and procedures:

[0046] (1) Pre-treatment of silicon wafers: 166mm N-type BC cell silicon wafers (110μm thick) are selected. After texturing, diffusion and passivation layer deposition are completed, the wafers are cleaned and dried to ensure that there are no impurities or scratches on the back of the silicon wafers.

[0047] (2) Inkjet printing hot melt wax mask: High-precision inkjet printing equipment is used to print the window area of ​​the back electrode of BC battery. The printing line width is 50μm and the wax film thickness is 20μm. The positioning is accurate and there is no offset. The curing temperature is 18℃ and the curing time is 0.7s. The wax film is tightly attached to the back of the silicon wafer.

[0048] (3) Silicon nitride etching window opening: Wet etching process is adopted, the etching solution is a mixture of hydrofluoric acid and nitric acid (mass concentrations of 8% and 3% respectively), the etching temperature is 22℃, the etching time is 180s, the back electrode window opening is accurately completed, the window size is uniform, the edge is flat, and there is no over-etching.

[0049] (4) Metal electroplating: The nickel-copper electroplating process (with less silver) is adopted. The electroplating temperature is 42℃, the current density is 1.5A / dm², the electroplating time is 15min, the nickel layer thickness is 2μm, the silver layer thickness is 5μm, and the metal electrode is deposited only in the window area. There is no overflow plating in the non-target area.

[0050] (5) Alkaline dewaxing: Use 3.5% sodium hydroxide solution, soak at 42℃ for 95s, and the hot melt wax is completely dissolved and peeled off; rinse with four-stage pure water, dry with hot air at 70℃ for 20min, and there is no residue on the back of the silicon wafer.

[0051] (6) Back-end process: Annealing at 310℃ for 30 minutes to complete back contact preparation, testing and packaging to obtain BC back contact battery finished product.

[0052] Construction test results:

[0053] The BC battery prepared in this embodiment has a back electrode windowing accuracy of ±3μm, which fully meets the requirements of fine back contact for BC batteries; the contact resistance between the electrode and the silicon wafer is reduced by 0.3mΩ, and the minority carrier recombination rate is reduced by 15%; the photoelectric conversion efficiency of the battery reaches 26.1%, which is 0.6% higher than that of the traditional screen printing process; the average silver consumption per cell is reduced by 100%, and the cost per cell is reduced by 2.2 yuan; the yield of finished products reaches 98.9%, with no defects such as incomplete plating, over-plating, or wax residue, and the process stability is excellent, which can be directly adapted to the mass production of BC batteries.

[0054] Comparative Example: Application Case of Traditional Screen Printing Silver Paste Process

[0055] 1. Process conditions: 182mm TOPCon silicon wafers of the same specifications were used. Electrodes were prepared using traditional screen printing silver paste process with a silver paste thickness of 13μm and a gate line width of 25μm. The remaining front-end and back-end processes were the same as in Example 1.

[0056] 2. Existing problems: The average silver loss per cell is 90mg, which is very high, and the series resistance is too high; there are defects such as broken grids and false printing, and the yield rate is only 95.8%; the battery efficiency is only 25.2%; the screen printing plate wears out quickly, the operation and maintenance costs are high, and it is difficult to adapt to the needs of refined production.

[0057] Construction Summary:

[0058] The two construction examples above fully demonstrate that the process of the present invention is superior to the traditional screen printing silver paste process, whether in the conventional mass production of TOPCon cells or in the refined production of BC cells. The process has high stability, significant cost reduction effect, and obvious efficiency gain. At the same time, the production line transformation is easy and the implementation speed is fast. It can be widely used in the large-scale production of TOPCon and BC high-efficiency photovoltaic cells, and has extremely high commercial promotion value.

[0059] The above description represents a preferred embodiment of the present invention. For those skilled in the art, any changes, modifications, substitutions, and variations made to the implementation methods without departing from the principles and spirit of the present invention, based on the teachings of the present invention, still fall within the protection scope of the present invention.

Claims

1. A method for preparing TOPCon and BC photovoltaic cells, characterized in that, Includes the following steps: Step 1: Pre-processing of silicon wafers; Select qualified TOPCon or BC back-contact silicon wafers that have completed texturing, diffusion, oxide layer preparation, and passivation layer deposition. The silicon wafer surface should be free of damage, scratches, and impurities. The silicon wafer surface should be finely cleaned and degreased using plasma cleaning and pure water rinsing to remove residual trace contaminants and water stains. Then, it should be sent to a hot air drying oven for low-temperature drying to ensure that the silicon wafer surface is clean, flat, and free of watermarks. Step 2: High-precision inkjet printing of hot melt wax molding mask; Using professional photovoltaic industrial inkjet printing equipment, the prepared hot melt wax functional ink is precisely sprayed onto the designated area of ​​the silicon wafer according to the pre-introduced battery grid pattern, electrode pattern, and BC structure windowing trajectory. After printing, the hot melt wax pattern is cured and shaped at low temperature using a temperature-controlled curing device, so that the hot melt wax adheres tightly to the silicon wafer surface, forming a solid hot melt wax mask with a stable structure, clear edges, and uniform thickness; the unprinted areas are completely exposed to the silicon wafer substrate. Step 3: Use a hot-melt wax mask to etch and open windows in the silicon nitride layer; The silicon wafer with the hot melt wax mask printed is fed into a wet etching equipment. The appropriate etching process is selected according to the battery type to remove the silicon nitride passivation film on the exposed part of the silicon wafer surface by directional etching. During the etching process, the hot melt wax mask area has extremely strong etching resistance, which perfectly protects the underlying silicon nitride layer and silicon wafer substrate from etching damage, and accurately completes the windowing operation at the specified positions of the electrode areas required for the topcon and BC battery. Control the etching parameters to ensure accurate window size, smooth edges, and no over-etching or under-etching. Step 4: Conduct metal electroplating using hot melt wax as an insulating mask; After the silicon nitride etching and windowing process is completed, there is no need to remove the hot melt wax mask. The silicon wafer is directly transferred to the photovoltaic cell electroplating production line, where metal electrode deposition is carried out using either copper electroplating or nickel-copper electroplating. Utilizing the excellent insulating properties of the hot melt wax itself, it serves as an electroplating isolation and protective mask, preventing the electroplating solution from contacting non-target areas. Metal layer deposition and electroplating are performed only on the etched bare areas of the silicon wafer, precisely shaping the positive and negative electrodes, fine grid electrodes, and back contact electrodes of the cell. Electroplating parameters are controlled to ensure that the electrode patterns are regular and the conductive layer thickness is uniform, adapting to the electroplating shaping requirements of various structures such as TOPCon fine grid electrodes, BC back electrodes, and front SE electrodes. Step 5: Use alkaline solution to peel off and dissolve the hot melt wax mask at a constant temperature; After the electroplating and deposition of the battery metal electrodes are completed, the silicon wafer is placed in an alkaline cleaning tank and immersed at a constant temperature using a prepared weak alkaline solution. Utilizing the physicochemical properties of hot melt wax, which easily swells and decomposes in the presence of alkali, all hot melt wax mask layers on the silicon wafer surface are quickly and completely peeled off and fully dissolved in the alkaline solution, leaving no residual wax. Subsequent steps include three-stage pure water overflow rinsing and hot air drying to remove any trace amounts of residual wax and alkali from the silicon wafer surface. The entire process does not corrode the silicon wafer substrate, passivation layer, or the formed metal electrodes, ensuring the stable performance of the battery in the future. Step 6: Subsequent finished product manufacturing process; After the silicon wafers are stripped and cleaned, they undergo annealing and reinforcement, electrode inspection, appearance sorting, and encapsulation, and are then packaged into high-performance TOPCon photovoltaic cells and BC back contact photovoltaic cells.

2. The method for preparing TOPCon and BC photovoltaic cells as described in claim 1, characterized in that, In step 1, the drying temperature is 60-80℃ and the drying time is 2-3 minutes.

3. The method for preparing TOPCon and BC photovoltaic cells as described in claim 1, characterized in that, In step 2, precise jet printing is performed on the designated area of ​​the silicon wafer. For TOPCon cells, the focus is on the front fine grid and main grid area, while for BC cells, the focus is on the back electrode window area. The curing temperature for low-temperature curing and shaping is 15-25℃, the curing time is 1-5s, and the thickness of the solid hot melt wax mask is controlled at 5-40μm.

4. The method for preparing TOPCon and BC photovoltaic cells as described in claim 1, characterized in that, In step 3, the appropriate etching process is selected according to the battery type. TOPCon BC batteries use wet etching. The wet etching solution used in controlling the etching parameters is hydrofluoric acid solution, the etching temperature is 20-25℃, and the etching time is 600-700s to ensure accurate window size and window width control of 20-300μm.

5. The method for preparing TOPCon and BC photovoltaic cells as described in claim 1, characterized in that, In step 4, the electroplating parameters are controlled as follows: electroplating temperature below 35℃, current density 1-3A / dm², electroplating time 5-20min, and metal layer thickness controlled at 5-15μm.

6. The method for preparing TOPCon and BC photovoltaic cells as described in claim 1, characterized in that, In step 6, the annealing temperature is 300-350℃ and the annealing time is 30-40 minutes.