GaAsP nanowire-on-Si tandem solar cell

GaAsP self-assisted core–shell p-i-n nanowires were grown on Si solar cells. The resulting tandem cell exhibited an enhanced Voc of 1.16 V, increasing from 0.54 V for the Si cell alone. Nevertheless, the efficiency of the tandem cell was only 3.51% as compared with 9.33% for the Si cell due to a current-limiting short-circuit current density from the nanowires. Further improvement in device performance can be realized by improving the nanowire open-circuit voltage and short-circuit current, related to doping of the nanowires.