Plasmon-Enhanced Photoluminescence of Interlayer Excitons Induced on WSe ₂ /MoS ₂ Heterobilayers

Excitonic light emission from transition-metal dichalcogenides (TMDs) heterobilayers has attracted considerable attention as a promising platform for atomically thin light sources. However, their emission efficiency is limited by the momentum mismatch between the valleys of the constituent TMD monolayers, and hence improving the emission quantum yield is highly desirable for their practical implementation in light-emitting devices. Here, we achieve a 10-fold enhancement of momentum-indirect emission by resonantly coupling plasmonic nanostructures with the WSe₂/MoS₂ heterobilayer. We observe a pronounced acceleration of the radiative recombination process of interlayer excitons in the plasmon-heterobilayer coupled system, demonstrating that the emission enhancement originates from the plasmonic Purcell effect. Our findings provide valuable insight into the influence of the plasmonic Purcell effect on momentum-indirect radiative transitions in TMD heterobilayers and offer compelling evidence that plasmonic nanostructures can effectively promote such transitions, paving the way for the development of highly efficient light-emitting devices based on TMD heterobilayers.