The Preparation And Surface Passivation Of Black Silicon Solar Cells

Solar cells were widely used in our daily life today. There have many kinds of solar cells. It is a prime target to improve the conversion efficiency of solar cells. In this paper, the black silicon and surface passivation to were employed improve the conversion efficiency of solar cells. Black silicon can reduce the reflectance of incident light, which has the advantages of low cost. Meanwhile, surface passivation is induced to reduce the surface recombination, and increase the conversion efficiency of solar cells.Preparation of black silicon nanowires is very important for silicon solar cells, because it can reduce the reflectance of the incident light so that the absorption rate of incident light is greatly improved. Black silicon was prepared by silver-nanoparticle-assisted etching on pyramidal silicon wafer. At the wavelength range of350nm to1100nm range, the reflectance of black silicon nanostructure is significantly lower than pyramid textured silicon. The structure of black silicon nano wires were modulated by KOH. Experimental results show that the reflectance of black silicon solar cells that have been etched by KOH solution is higher than that of the black silicon solar cells without etching.However, the final conversion efficiency is higher than black silicon without etching, which is due to the reduce of surface recombination velocity. The conversion efficiency of black silicon solar cells that have been etched by KOH solution we obtained reached to16.8%, while the conversion efficiency of black silicon solar cell without etching is16.5%.Although black silicon can reduce the reflectivity of incident light, the conversion efficiency is not improved as expected, which is due to the increase of surface defect density with the increase of the surface area. Therefore, we used various passivation to reduce the surface recombination velocity. The conversion efficiency of black silicon solar cell without passivation is12.9%. For the SiO2and SiNx:H passivation, the conversion efficiency of black silicon solar cells increase to16.0%and16.4%, respectively. Compare to the single film of surface passivation of black silicon solar cells, the SiO2/SiNx:H stacks exhibits the highest efficiency of16.8%. The investigation of IQE suggests that the SiO2/SiNx:H stacks suppress Auger recombination through reducing the surface doping concentration, and SiNx:H layer suppresses the Shockley-Read-Hall (SRH)recombination in the black silicon solar cell.