Method for solving problem of EL (electroluminescent) black spots of PERC (passivated emitter and rear cells)

Abstract

The invention belongs to the field of solar cell manufacture, and particularly relates to a method for solving the problem of EL (electroluminescent) black spots of PERC (passivated emitter and rear cells). The method has the advantages that the aperture sizes of spray pins of water films are 0.8 mm, water film devices can slowly cover silicon wafers, the silicon wafer covering water spray pressures of the water films can be relieved, the silicon wafer laying pressures can be reduced, undesirable conditions that existing water films are splashed all around to contaminate existing surrounding silicon wafers can be effectively reduced on the premise that consistent water flow is guaranteed, and the problem of the EL black spots of the PERC can be effectively solved by the aid of the method;the pressures of the water film devices can be relieved, the problem of falling of existing spray pins of the existing water films can be effectively solved, the problem of long-time pinhole blockingcan be solved, over-etching due to insufficient water volumes can be prevented, equipment staffs only need to carry out irregular replacement and maintenance, and accordingly the time and labor can besaved; the problems of water film splashing, belt and silicon wafer contamination and etching contamination due to excessively high power and high pressures of the existing water films can be solved,the yield of efficient single crystals can be increased, the efficiency of the efficient single crystals can be improved, and the method has a broad application prospect.

Description

technical field [0001] The invention belongs to the field of solar cell manufacturing, and in particular relates to a method for solving EL black spots of PERC cells. Background technique [0002] In 2017, high-efficiency monocrystalline cells scrambled to occupy the mainstream market of photovoltaic cells and became a new generation of conventional technology for solar cells. PERC cells implemented passivation technology on the back of the cell to enhance the internal back reflection of light on the silicon base and reduce the backside recombination. In this way, the efficiency of PERC cells can be effectively improved. Low-cost and high-efficiency PERC cells have significant advantages in mass production. Like all technologies, the advent of new products is accompanied by some challenges and problems to be solved. High-efficiency monocrystalline cells The EL problem of the finished film is more prominent. EL is the abbreviation of electroluminescence (English electrolumin...

AI Technical Summary

Problems solved by technology

The dark spots and spots under the EL of the battery sheet are more obvious under the back passivation process. The black spot defect area of ​​the battery sheet contains a high concentration of harmful impurities, among which S element, metal Ca, Zn, Sr, and Co The content exceeds the table. These impurities generate recombination centers in crystalline silicon cells, reduce the diffusion length and minority carrier lifetime, and form black spots under the EL. Therefore, improving the cleanliness and corrosion cleaning quality in the production process is the key to reducing black spots. Wet method is the main process that leads to the formation of black spots. The splash of water film falls on the feeding conveyor belt of the upper equipment, causing the belt to be wet. During the transfer of silicon wafers, silicon wafers are polluted to form internal defects in silicon wafers, and finally EL black spots are formed. Because the acid polishing process of high-efficiency monocrystalline solar cells is a crucial step in the manufacturing process of high-efficiency solar cells, it has a significant impact on the EL yield and electrical performance of finished cells, and high-efficiency monocrystalline cells occupy the mainstream market of photovoltaic cells Under the premise, EL black spot is a problem that often occurs in etching acid polishing. Acid polishing requires high reflectivity and high weight loss. The backside reacts violently under concentrated acid conditions, which can easily cause etching over-etching, and the water film is in the process of etching. The coverage before the etching tank is very important, which requires high water film. To ensure sufficient water flow, the equipment needs to have sufficient pressure. After the finished battery is made, the EL black spot is serious, which reduces the qualification of the finished product. Rate

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