Two-dimensional layered semiconductor/graphene heterostructures for solar photovoltaic applications

Abstract

Schottky barriers formed by graphene (monolayer, bilayer, and multilayer) on 2D layered semiconductor tungsten disulfide (WS₂) nanosheets are explored for solar energy harvesting. The characteristics of the graphene–WS₂ Schottky junction vary significantly with the number of graphene layers on WS₂, resulting in differences in solar cell performance. Compared with monolayer or stacked bilayer graphene, multilayer graphene helps in achieving improved solar cell performance due to superior electrical conductivity. The all-layered-material Schottky barrier solar cell employing WS₂ as a photoactive semiconductor exhibits efficient photon absorption in the visible spectral range, yielding 3.3% photoelectric conversion efficiency with multilayer graphene as the Schottky contact. Carrier transport at the graphene/WS₂ interface and the interfacial recombination process in the Schottky barrier solar cells are examined.