Silicon heterojunction solar cell with passivated hole selective MoO _x contact

We explore substoichiometric molybdenum trioxide (MoO_x, x < 3) as a dopant-free, hole-selective contact for silicon solar cells. Using an intrinsic hydrogenated amorphous silicon passivation layer between the oxide and the silicon absorber, we demonstrate a high open-circuit voltage of 711 mV and power conversion efficiency of 18.8%. Due to the wide band gap of MoO _x, we observe a substantial gain in photocurrent of 1.9 mA/cm ² in the ultraviolet and visible part of the solar spectrum, when compared to a p-type amorphous silicon emitter of a traditional silicon heterojunction cell. Our results emphasize the strong potential for oxides as carrier selective heterojunction partners to inorganic semiconductors.