Abstract

Current Si-based photovoltaic devices are expensive due primarily to high-quality raw materials and elaborate fabrication, drastic performance improvement and cost reduction are necessary for extensive applications. Two-dimensional layered materials such as graphene, metal dichalcogenides, and topological insulators have attracted much attention due to their extraordinary properties. Here, we report a systematic investigation on graphene/Si heterojunction solar cells. Si nanowire (SiNW) and nanohole (SiNH) arrays are both used for device construction, taking advantage of their large junction area and enhanced light absorption. Surface charge recombination and graphene conductivity play important roles in determining solar cell performance. By suppressing surface recombination and optimizing graphene layers and doping level, we demonstrate power conversion efficiencies (PCEs) over 10% for SiNW and SiNH arrays-based devices. A new type of solar cells based on the graphene quantum dots (GQDs)/Si heterojunctions was also developed. Owing to the extraordinary optical and electrical properties of GQDs, the GQDs/Si heterojunctions show much enhanced photovoltaic performance with efficiency over 12%. Further, MoS₂/Si and Bi₂SeTe₂/Si heterojunctions were constructed, which exhibited ultra-fast response to pulsed light and could serve as self-powered photodetectors. Our work reveals the great potential of two-dimensional layered materials/silicon heterojunctions for high-performance photovoltaic and optoelectronic devices.

© 2014 Optical Society of America