2D Janus MoSSe/MoGeSiN4 vdW heterostructures for photovoltaic and photocatalysis applications

Photoelectric catalytic and solar cells are two effective ways to solve the global energy shortage and environmental pollution problems. However, low carrier separation efficiency has been becoming a common problem of current photocatalytic water decomposition and solar cells. In this work, both the electronic structures and optical properties of Janus MoSSe/MoGeSiN4 vdW heterostructures were systematically studied by density functional theory. The results show that the Janus MoSSe/MoGeSiN4 vdW heterostructure with Se/Ge interfacial contact (Se/Ge heterostructure) is a direct band gap semiconductor. Interestingly, for the Se/Ge heterostructure, spatial separation of the photo-generated electrons and holes is expected, due to the conduction band minimum (CBM) and the valence band maximum (VBM) separately locating on the MoGeSiN4 and MoSSe layer. Besides, the Se/Ge heterostructure not only exhibits considerable absorption index in the visible light range but also maximum theoretical photoelectric conversion efficiency approaches 26.4 %, which can be furthermore enhanced by varying the layer distance and biaxial strain. The Se/Ge heterostructure shows high carrier mobility, obvious carrier separation, notably visible light absorption and tunable photoelectric properties, making it promising candidates for novel two dimensional photocatalysis devices and solar cells.