Investigation Of The Conducting Mechanism Of The Al-si Interface By Kpfm

PERC(passivated emitter and rear cell)is taking a huge amount of the photovoltaic market due to its excellent performance,it has the advantage of higher open circuit voltage and short circuit current over traditional back surface field(BSF)silicon solar cell,which are generally claimed to be related to the reduction of rear side recombination and the increase of rear surface reflection.However,few works have focused on exploring the internal conducting mechanism behind this.Herein,the influence of PERC technique on improving the short circuit current is investigated by comparing a PERC with a BSF cell.The surface potential results measured by Kelvin probe force microscopy show a higher surface potential step at the Al-Si interface of PERC than that of BSF cell,indicating a severer energy band variation and a better carrier collecting ability of PERC.Moreover,by using advanced microstructure characterization techniques,the relationship among the surface potential step,morphology and element distribution is fully studied which provides a new viewpoint to understand the enhanced performance of PERC.Additionally,potential routes to optimize the rear side of PERC are proposed by considering the sintering process of the solar cell,and that might be beneficial to the development of the photovoltaic market in our country.