High pressure processing of hydrogenated amorphous silicon solar cells: Relation between nanostructure and high open-circuit voltage

This study gives a guideline on developing high bandgap, high quality hydrogenated amorphous silicon (a-Si:H) through a carefully engineered nanostructure. Single-junction a-Si:H solar cells with open-circuit voltages (V-oc) above 950 mV and conversion efficiencies above 9% are realized by processing the absorber layers at high pressures of 7-10 mbar. The high V-oc is a result of an increased bandgap, which is attributed to an increase in the average size of the open volume deficiencies in the absorber layer without a significant increase in the nanosized void density. (C) 2015 AIP Publishing LLC.