Preparation And Characterization Of Porous Silicon/Monocrystalline Silicon Solar Cells

Nowadays,the society needs to seek new strategies for sustainable development because of the energy crisis and environmental pollution.Solar energy has received much attention due to its advantages of clean,pollution-free and abundant reserves.Silicon-based solar cells whose efficiency reach 20%are the mainstream type of development in the photovoltaic industry.At present,the development of crystalline silicon solar cells is relatively mature.It is extremely difficult to reduce the cost of the battery and improve the efficiency.Therefore,we prepare the porous silicon layer to replace the original inverted pyramid structure and anti-reflection film,aiming to reduce the anti-reflection rate.The original diffusion process is replaced by the rapid thermal diffusion process replaces,which simplifies the preparation process and greatly reduces the cost of the battery.Porous silicon/mono-crystalline silicon solar cells were selected as the research object.Difffusion of phosphorus was performed using a rapid thermal processing(RTP)method.The porous silicon properties,including difffusion resistance,reflectance,J-V characteristics,were characterized,and the following conclusions are maintained:(1)The thickness growth rate of porous silicon is 1.77?m/min and oblique pores preferentially grow along(100)and(113)directions.The pore size range is 10-30 nm.(2)The sheet resistance decreases as the thickness of porous silicon increases,which reaches to 100 ?/sq,proving that porous silicon layer promotes phosphorus diffusion.In addition,the thicker the porous silicon layer,the higher the diffusion temperature,the longer the diffusion time,and the better the diffusion effect.(3)The spectra measured by ultraviolet-visible spectrophotometer demonstrates that the reflectivity of the porous silicon layer is slightly lower than 12%within the spectral range of 400-1100 nm.However,with the increasing of the thickness of the porous silicon layer,although the reflectivity is better,the charge recombination phenomenon is frequent and the battery efficiency is reduced.(4)The result is better under the situation of 850? diffusion temperature for 40s diffusion time and 4 min etching at 30 mA/cm2.In this case,the porous silicon solar cell was achieved with an efficiency of 12.32%,a short-circuit current density of 27.99 mA/cm2,an open-circuit voltage of 0.49 V and a filling factor of 71%.