Improving the performance of radial n-i-p junction Si nanowire solar cells by catalyst residue removal

It is hoped that silicon nanowire (SiNW)-based solar cells will provide the basis for a new generation of photovoltaics. However, metal-catalyzed SiNWs contain metal residues (such as indium) which may degrade the performance of solar cells. In this study, we prepared SiNW solar cells by plasma-enhanced chemical vapor deposition using indium as the catalyst to grow the SiNWs. The SiNWs were treated with hydrochloric acid to reduce the indium contamination at different concentrations, CHCl (1–5%). We found the decreasing the indium contamination improved the performance of the solar cells at optimum CopHCl. However, the performance of the solar cells decreased when CHCl exceeded CopHCl. This was attributed to the variation in the conduction-band offset ΔEc between the n type amorphous silicon layer (Ec n-a-Si) and the n type crystalline silicon nanowires (Ec n-c-SiNWs). Finally, a conversion efficiency (Eff) improvement from 2.11% to 6.18% was obtained with the optimized CHCl.