bilayer from first-principles GW calculations*

Two-dimensional (2D) transition metal dichalcogenide (TMD) semiconductor crystals are highly sensitive to their environments, and molecular adsorbates decorating the 2D material surfaces constitute a route to tuning their electronic and optical properties. Here, we use a first-principles GW approach to compute the quasiparticle (QP) energies and energy level alignment at an interface formed by an atomically-flat molecular PTCDA monolayer and a MoS₂ monolayer. To reduce the computational cost, we use the substrate screening GW approach which reduces the expense associated with computing the interface polarizability by using smaller supercells. We show that the respective band gaps of the molecular PTCDA and MoS₂ substrate are both modified upon interface formation and we explore the QP energy level alignment at the interface. We also discuss how a molecular monolayer may controllably alter the photophysics of a TMD monolayer.