Efficient carrier selective contacts are key to electronic devices based on silicon including sensors, microelectromechanical systems, field effect transistors and photovoltaics. We explore substoichiometric molybdenum trioxide (MoOx, x<3) as a dopant-free, hole-selective contact for silicon. As a proof of principle, we demonstrate a silicon solar cell with a MoOx hole contact delivering a high open-circuit voltage of 711 mV and a power conversion efficiency of 18.8%. Due to the wide band gap of MoOx, we observe a substantial gain in photocurrent of 1.9 mA/cm2 in the ultraviolet and visible part of the solar spectrum, when compared to a p-type hydrogenated amorphous silicon emitter of a traditional silicon heterojunction cell. With a high workfunction exceeding those of elemental metals, MoOx presents an important opportunity to contact holes in inorganic semiconductor materials beyond silicon including III-V semiconductors, carbon-based nanomaterials and layered transition metal dichalcogenide semiconductors.
Project end date: 08/13/14