Stacking-tailoring quasiparticle energies and interlayer excitons in bilayer Janus MoSSe

Stacking sequence of bilayer van der Waals transition metal dichalcogenides determines their electronic and related optical excitations. When the Janus monolayer structure has been taken to construct bilayer TMDs, it would introduce another degree of freedom, the out-of-plane intrinsic dipole moment, to tune the electronic and optical properties. Here we reveal that the electronic band structures and interlayer excitons can be dramatically tuned via the stacking sequence of the bilayer MoSSe with the different intrinsic dipole orientations. Moreover, the lowest energy interlayer excitons exhibit diverse spatial extensions, and the corresponding radiative lifetimes can be tailored within the range of ∼10⁻⁸ to ∼10⁻² seconds at room temperature, by means of optimizing the dipole orientation and stacking sequence, and when the dipole moment keeps the same orientation for the constituent layer, it will slower the radiative recombination. Our findings shed a light on the applications of the interlayer excitons in Janus MoSSe on optoelectronics. (paper)