(201af) Photovoltaic and Spectral Response of WS2/Silicon Heterojunctions
Transition metal dichalcogenides (TMDs) such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2) are attractive because of their ultrathin structure and inimitable electronic band structures with unique functionalities including: indirect-to-direct bandgap transition, semiconductor-to-metal phase engineering, and the large excitonic effect. Further, the TMDs with thickness-dependent tunable optical bandgaps in the near-infrared to visible spectral range can exhibit extremely strong lightâmatter interactions suitable for energy harvesting devices such as solar cells. Currently, the WS2-based solar cells are realized via micromechanical exfoliation or transfer of two-dimensional (2D) WS2 layers onto conventional 3D bulk semiconductors. Here, we report the photovoltaic response of WS2/Si heterojunction solar cells developed via chemical vapor deposition (CVD). The photoresponse and quantum efficiency of the WS2/Si-based solar cell devices are also investigated in order to further understand the junction characteristics (trap states and recombination mechanisms). The present study opens avenues for the direct integration of CVD-grown monolayer WS2 with Si-based heterojunctions for efficient optoelectronic devices.