Method for realizing graded laminated passivation film on back surface of solar cell

Abstract

The invention relates to the field of solar cell production method, especially to a method for realizing a laminated passivation film on the back surface of a solar cell. A film is deposited on the backlight surface of a processed solar cell silicon chip according to chemical vapor deposition technology, the mixed gas of SiH4 and N2O is adopted as the gas at the beginning of the deposition, NH3 is gradually added in the process of deposition so that the component of the film is changed from silicon dioxide on the surface of the silicon chip to nitrogen oxide of silicon in the outward direction and then to silicon nitride in the outward direction, and the thickness of the film ranges from 50nm to 300nm. The method has the characteristics of fast deposition speed, high output, being capable of achieving the deposition of a plurality of films at a time, and high tightness of the deposited film. High temperature process is not needed in the technology, the heat budget required is less, and high temperature influence resulted from thermal oxidization is avoided, in addition, such a graded laminated film can effectively reduce interface state caused by the combination of different films, improve thermal stability compared with silicon nitride only, and lessen film stress.

Description

technical field [0001] The invention relates to the field of solar cell production methods, in particular to a method for realizing a slowly-varying lamination passivation film on the back surface of the solar cell. Background technique [0002] Photovoltaic power generation is a very important field in the utilization of solar energy. It is an urgent task to seek new technologies, new materials, and new processes to improve battery conversion efficiency and reduce costs. [0003] The conversion efficiency of solar cells is directly related to the generated photovoltaic electron-hole pairs. More electron-hole pairs mean high conversion efficiency, but only when these minority electrons are actually collected can they be converted into electrical energy. Various defects and interface states of the silicon wafer will greatly recombine these minority carriers, reducing the final effective conversion efficiency. By improving the pulling technology of crystalline silicon, the de...

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Problems solved by technology

At present, the existing back surface passivation methods are: 1. Aluminum back field passivation. At present, most crystalline silicon solar cells use the method of screen printing aluminum back field, but the passivation effect is limited; 2. Thermal growth oxidation Silicon passivation, the passivation effect of thermally grown silicon dioxide passivation is good, but it has a disadvantage. The cell has to go through the process of thermally growing silicon oxide at high temperature. The high temperature is usually greater than 800 degrees. There are side effects, and it will reduce the life of the polycrystal, and the process time will be longer; 3. SiNx passivation has a good passivation, but this inversion layer will introduce a field, which will form a bypass to greatly reduce the output current and voltage

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