Hole selective MoOx contact for silicon heterojunction solar cells

Efficient carrier selective contacts and excellent surface passivation are essential for solar cells to reach high power conversion efficiencies. Exploring MoO_x as a dopant-free, hole-selective contact in combination with an intrinsic hydrogenated amorphous silicon passivation layer between the oxide and the crystalline silicon absorber, we demonstrate a silicon hetero-junction solar cell with a high open-circuit voltage of 711 mV and a power conversion efficiency of 18.8%. Compared to the traditional p-type hydrogenated amorphous silicon emitter of a traditional silicon heterojunction solar cell, we observe a substantial gain in photocurrent of 1.9 mA/cm² for MoO_x due to its wide band gap of 3.3 eV. Our results on MoO_x have important implications for other combinations of transition metal oxides and photovoltaic absorber materials.