Black phosphorus-based van der Waals heterostructures for mid-infrared light-emission applications

Mid-infrared(MIR)light-emitting devices play a key role in optical communications,thermal imaging,and material analysis applications.Two-dimensional(2D)materials offer a promising direction for next-generation MIR devices owing to their exotic optical properties,as well as the ultimate thickness limit.More importantly,van der Waals heterostructures-combining the best of various 2D materials at an artificial atomic level-provide many new possibilities for constructing MIR light-emitting devices of large tuneability and high integration.Here,we introduce a simple but novel van der Waals heterostructure for MIR light-emission applications built from thin-film BP and transition metal dichalcogenides(TMDCs),in which BP acts as an MIR light-emission layer.For BP–WSe_(2) heterostructures,an enhancement of~200% in the photoluminescence intensities in the MIR region is observed,demonstrating highly efficient energy transfer in this heterostructure with type-Ⅰ band alignment.For BP-MoS_(2) heterostructures,a room temperature MIR light-emitting diode(LED)is enabled through the formation of a vertical PN heterojunction at the interface.Our work reveals that the BP-TMDC heterostructure with efficient light emission in the MIR range,either optically or electrically activated,provides a promising platform for infrared light property studies and applications.