Highly radiative emission of room temperature-localized excitons enabled by charge-neutralized 0D quantum wells in 2D...

Nondiffusing localized excitons (X_L) in two-dimensional semiconductors present a robust platform for mediating light-matter interactions, with potential applications in both photovoltaics and light-emitting devices. However, at room temperature, high thermal energy hinders X_L formation, while excess charges diminish the quantum yield (QY) through nonradiative decay. Here, we present high-QY X_L emission in ambient conditions by removing excess charges and inducing efficient exciton funneling into a Au nanohole. Specifically, by evaporating an H₂O barrier between the n-type MoS₂ and the Au substrate, we induce a grounding effect on electrons. Dominantly populating excitons are then funneled and bound to the nanohole through the strain-induced zero-dimensional quantum well effect. We confirm the exciton confinement efficiency of ~98% using a drift-diffusion model, enabling bright X_L emission at the nanoscale. Using tip-induced gigapascal-scale pressure, we control X_L dynamics and QY in a reversible manner. Our approach provides an innovative strategy for X_L-based nanophotonic devices.