Stacking-Dependent Interlayer Excitons in BP/CrSe ₂ van der Waals Heterostructure

The emergence of two-dimensional van der Waals (vdW) heterostructures has revolutionized exciton-based research due to their tunable electronic and optical properties. Here, we present a systematic many-body study of a BP/CrSe₂ vdW heterostructure composed of experimentally realized boron phosphide (BP) and chromium diselenide (CrSe₂) monolayers. We find a robust type-II band alignment across all stacking configurations; however, interlayer excitons emerge selectively depending on the stacking order. The vdW heterostructure exhibits strong exciton binding energy (0.34-0.44 eV, depending on stacking) and nanosecond-scale room-temperature radiative lifetimes, indicating long-lived excitonic states. Additionally, its optical absorption extends from the visible to the near-infrared regime, underscoring its potential for optoelectronic and excitonic applications. Our findings highlight the critical role of stacking-dependent interlayer coupling in controlling the excitonic properties of vdW heterostructures, paving the way for tailored design strategies in next-generation light-harvesting and quantum technologies.