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Monocrystalline silicon photovoltaic cells are a photovoltaic cell with earlier development, the highest conversion rate and large output. At present, the conversion efficiency of monocrystalline silicon photovoltaic cells in China has reached an average of 16.5%, while the highest conversion efficiency recorded by the laboratory has exceeded 24.7%. This kind of photovoltaic cell is generally based on high-purity monocrystalline silicon rods as raw materials, and the purity requirements are 99.9999%. In order to reduce production costs, photovoltaic cells for ground applications now use solar-grade monocrystalline silicon rods, and the material performance indicators have been relaxed. Some can also use the head and tail materials and waste monocrystalline silicon materials processed by semiconductor devices to be compounded to make monocrystalline silicon rods for photovoltaic cells. The monocrystalline silicon rod is cut into silicon wafers, and the thickness of the wafers is generally about 180-220um. After the silicon wafer has been tested, cleaned, velveted and other processes, it is then doped and diffused on the surface layer with trace elements such as boron, phosphorus, antimony, etc., forming a PN junction, that is, it has the basic characteristics of the battery. In order to prevent a large number of photons from being reflected off the smooth surface of the silicon wafer, it is necessary to use the Pevcd method to coat the surface of the silicon wafer with a layer of silicon nitride anti-reflection film, which also plays a protective role. Then, after dephosphorization silicon glass and plasma etching, the screen printing method is adopted, and the prepared silver paste is printed on the silicon wafer to make a grid line, and the back electrode is made, and then after the sintering process, the monocrystalline silicon photovoltaic cell is made.

 

Second, polycrystalline silicon photovoltaic cells