▎ 摘　　要

Janus transition metal dichalcogenides with a built-in structural cross-plane asymmetry have recently emerged as a new class of two-dimensional materials with a large cross-plane dipole. By using the density functional theory calculation, we report the formation of different Schottky barriers for Janus PtSSe and graphene based van der Waals heterostructures, where the Schottky barrier height (SBH) and type of contact can be controlled by adjusting the interlayer distance, by applying an external electric field, and by having multiple layers of Janus PtSSe. It is found that the effects of tuning are more prominent for SPtSe/graphene as compared to SePtS/graphene. Besides, a transition from n-type Schottky contact to p-type Schottky contact and to Ohmic contact is also observed in the SPtSe/Gr heterostructure for different SPtSe stackings from 1 layer, to 2- and 3-layers, respectively. Our findings indicate that the SPtSe/graphene heterostructure is a suitable candidate for applications that require a tunable SBH.