MoOx and WOx based hole-selective contacts for wafer-based Si solar cells

Highly-transparent carrier-selective front contacts open a pathway towards entirely dopant free Si solar cells. Holeselective a-Si:H/MoO_x/ITO front contact stacks were already successfully applied in such novel devices. However, for optimum device performance, further improvements are required: We evaluate the use of the high-work-function material WO_x as a replacement for MoO_x in an attempt to reduce optical absorption losses. In addition, we investigate the use of thin hydrogenated SiO_X instead of a-Si:H, and the impact of the residual pressure for MoO_x evaporation.