Fabrication Of Porous Silicon By Silver Catalytic Method And Its Application On Silicon Solar Cells

As today’s energy crisis becomes more and more severe, solar energy as a kind of clean renewable energy has broad application prospects. Photovoltaic technology could convert solar energy into electricity directly. For this reason, researchers pay a lot of attention to it. Currently,80%of the photovoltaic market share is occupied by silicon solar cells. Reducing the production cost and improving the cell efficiency is the final goal of the crystalline silicon solar cell research.In order to reduce the production cost, the thickness of the silicon wafer should be thinner. The absorption of light is the key problem when the wafers become thinner. Minimization of surface reflection losses is a most effective way to solve the light absorption problem. In this work, noble metal catalytic method is used to make nonporous silicon on crystalline and multicrystalline silicon solar cells. The main innovation results are summarized as followed:The evolution of the surface reflectance with the reaction time and temperature is studied. With the reaction temperature increasing, the average reflectance of the crystalline silicon surface gradually decreases. With the prolongation of the reaction time, the reflectance of the wafer becomes lower. In the reaction time range of2-5min, the reflectance of the wafer could be reduced to5%.The porous silicon structure is applied on the deep emitter of crystalline silicon wafer. The most suitable sheet resistance to fibricate silicon solar cell is50Q/sq. And the highest efficiency of the porous silicon solar cell device is14.2%corresponding to this sheet resistance. When the SiNx coating is applied on the silicon surface, the cell efficiency increases to15.3%.After the porous silicon applied on muticrystalline silicon wafer surface, the porous silicon solar cell efficiency could reach13.1%when the sheet resistance is50Ω/sq. In another work, the nanoporous silicon is applied on P type multicrystalline silicon. The reflectance could be reduced to15%in the visible wavelength range. The conversion efficiency of porous silicon solar cell device is11.9%. And the conversion efficiency increases to12.2%and12.4%severally by SiNx and oxidation passivation.