Preparetion Of SiO₂ Films On The Crystalline Silicon Surface By Liquid Phase Deposition And Their Photovoltaic Properties

At present,due to the relatively high photoelectric conversion efficiency and relatively mature manufacturing technology,crystalline silicon solar cells occupy the dominant position in the PV market.However,the silicon refractive index is more than40%so that most of the light irradiated to the silicon surface is reflected.This resulted in a decrease in the photoelectric conversion efficiency of the solar cell due to the poor absorption of sunlight.Thus,reducing the light reflection on the silicon wafer surface is important to improving the photoelectric conversion efficiency of the crystalline silicon solar cells.In this paper,the SiO₂ anti-reflective film was prepared on the surface of muti-crystalline silicon by the method of liquid phase deposition to reduce the reflection of sunlight on the surface,and to improve the photoelectric conversion efficiency of multi-crystalline solar cells by increasing the luminous flux into the solar cell.The way to improve the efficiency of the multi-crystalline solar cell has been created.The main achievements are as follows:（1）The fluorosilicic acid has been optimized as deposition system.The effect of fluorosilicic acid concentration on the film deposition rate,film surface structure uniformity,film thickness and antireflectivity has been investigated,and a quantitatively controlling their liquid deposition SiO₂ film process has been created.（2）The antireflective properties of liquid phase deposition SiO₂ films on the surface of multi-crystalline silicon wafers were investigated.The investigation clearly showed that,such LPD SiO₂ thin flim had high reducing reflection behavior in visible light range.（3）The boric acid as accelerator,and its critical acceleration behaviors have been investigated.The accelerator and its acceleration of fluorosilicic acid hydrolysis behaviors on silicon wafer were optimized to enhance and control SiO₂ thin film deposition rate.Thus,less than 30 nm SiO₂ thin film on multi-crystalline silicon wafer was successfully created.On the fluorosilicic acid critical concentration performance,the boric acid concentration and silic thin film depositon quantitative relationship have been established.The boric acid concentration tunes thin film deposition rate.（4）The liquid phase deposition SiO₂ film structure and property characterization methods of on multi-crystalline surface have been created.X-ray diffraction,X-ray photoelectron spectroscopy（XPS）,electron dispersive energy spectrum（EDS）,Raman spetectroscopy,and Furiet Transmission Infrared Spectroscopy（FTIR）techniques,etc.have been adopted to study the properties of the film,their characterizations showed that such deposition film have high chemical tolerance,and stability in 800^?C high temperature conditions.The characterizations of the refractive index,reflective index,and minority carrier life showed that,the multi-crystalline deposition film have good anti-reflective properties reducing and effective surface passivation properties.（5）The multi-crystalline solar cell anti-reflective film system had been created by liquid phase deposited SiO₂ film and SiN/SiO₂ dual layer film.The multi-crysalline solar cell used the liquid phase deposited SiO₂ film and SiN/SiO₂ dual layer film as the anti-reflective film and passivation film have been prepared,respectively.It was found that,the multi-crystalline solar cell which used the SiN/SiO₂ dual layer film as the anti-reflective film has maximum optical-electric efficiency up to 16.67%,and the average solar cell efficiency is more than 15%.In a word,the SiO₂ LPD films have not only good antireflective but also good passivation properties.The multi-crystalline solar cells which used the SiN/SiO₂ double layer film as the anti-reflective film have high stability and practicity,and are suitable for the practical applications.