Silicon nanowires covered with on-site fabricated nanowire-shape graphene for Schottky junction solar cells

Schottky junction photovoltaic devices were successfully assembled by using nanowire shaped graphene sheets grown on-site onto nano-imprint lithography silicon nanowires (SiNWs). Graphene formation was accomplished by rapid CVD synthesis on nickel catalysts deposited on SiNWs. The graphene remains on the SiNWs after the underlying metal catalyst is wet etched, forming a graphene-Si 3D-junction. The SiNWs substrate contributes light trapping qualities while the NW-shaped graphene increases the carrier collecting area compared to flat graphene resting on SiNWs. Complicated graphene transfer procedures could be avoided, and the process is capable of being scaled up. Simple SiNW-based devices improved the power conversion efficiency (PCE) and ease of fabrication compared to equivalent planar-type controls and could reach a PCE up to 2.19% without doping, or 3.83% after p-type doping with AuCl3. High recombination losses likely limited device performance in this simple system, necessitating future improvements in graphene quality and interface engineering.