Carrier transport mechanisms of nickel oxide-based carrier selective contact silicon heterojunction solar cells: Role of wet chemical silicon oxide passivation interlayer

Abstract

We have investigated the carrier transport mechanisms of Ag/ITO/NixO/n-Si/LiFx/Al carrier-selective contact (CSC) silicon solar cells without and with chemically grown SiOx passivation interlayer. The carrier transport is dominated by thermionic (Schottky) emission and tunnelling at the high- (>0.4 V) and low-forward (<0.4 V) bias voltage regions, respectively, in the cell with SiOx interlayer. Without intentionally grown SiOx layer, the carrier transport is dominated by the recombination through interface/surface defect states, which is inferred from the smaller activation energy and strong temperature-dependent ideality factors in >0.4 V forward voltage bias region. The C–V analysis is also confirmed the inability to hold the excess photo-generated charge carriers because of poor interface quality of the cell without SiOx than the cell with SiOx. The NixO/c-Si junction with the SiOx is resulted in higher built-in voltage and better open-circuit voltage representing better interface passivation quality with fewer interface/surface defect states.