Substrate Screening Effect on Quasiparticle Energies and Optical Properties of Lattice-mismatched Two-dimensional Interfaces

Two-dimensional (2D) materials and their interfaces have recently emerged as promising platforms for exotic physical phenomena. Previous methods of including substrate screening for quasiparticle energies can be only applicable to interfaces of two systems' lattice constants with certain integer proportion, which often requires a few percentage of strain. We developed an efficient and accurate reciprocal-space interpolation technique for dielectric matrices that made quasiparticle energy calculations possible for arbitrarily mismatched interfaces free of strain [1]. We applied this method to obtain quasiparticle corrections at GW approximation for arbitrary mismatched 2D interfaces, by interfacing hBN with SnS₂ and phosphorene at their natural lattice constants. We then employed this method to study the effect of substrates on optical properties of 2D materials, by solving the Bethe-Salpeter equation. We obtained perfect agreement with experimental non-rigid 1s and 2s excitonic shift with increasing layer thickness of WS₂. At the end, we predicted optical spectra and radiative lifetime of hBN with different substrates and explained their microscopic mechanism. [1] C. Guo et al, arXiv:2007.07982