First-principles study of tunable exciton lifetime in ZrSSe/SnSSe heterostructures

The excitonic effect is of great significance for the application of 2D materials in light-emitting devices, excitonic devices, and other light-matter interaction-related fields. In this work, based on first-principles calculations using the GW approximation and solving the Bethe-Salpeter equation (BSE), the quasiparticle band structures and exciton-related optical properties of monolayer ZrSSe and ZrSSe/SnSSe heterostructures were investigated. The results show that monolayer ZrSSe has a large exciton binding energy (0.53 eV) and an exciton lifetime at the ps level. Furthermore, the four stable stacking configurations of the ZrSSe/SnSSe heterostructures, exhibit type-II band structures, which are favorable for the generation of interlayer excitons. The real-space distributions of exciton wave functions in ZrSSe/SnSSe heterostructure indicate that the lowest energy excitons are interlayer excitons, and the first strong absorption peak exciton are intralayer excitons. More importantly, all four stackings have large exciton binding energies (0.314–0.351 eV) as well as long exciton lifetimes (0.42–36.89 ns). The bandgap and exciton lifetime could be regulated by the intrinsic interfacial electric field arising from different stackings. These findings provide new insights into the potential applications of monolayer ZrSSe and ZrSSe/SnSSe heterostructures as optoelectronic devices materials.