Giant amplification of interlayer exciton flux enabled by extreme exciton localization

The complex, but extraordinary transport properties of interlayer excitons (IXs) in van der Waals (vdW) heterostructures drive the development of advanced excitonic circuits, yet their transport mechanisms at the nanoscale remain largely unknown. Here, we demonstrate an anomalous IX transport regime arising from nanoscale bandgap modifications in vdW heterostructures. To manipulate and simultaneously probe such IX behaviors, we present a controllable electro-plasmonic nanocavity with sub-nanometer positional precision. The nanoscale bandgap gradient confines IXs to narrow potential well, creating a highly localized density profile whose outward diffusion current exceeds the electric-field-induced drift. By analyzing nonlinear energy shifts from repulsive dipolar interactions and applying a drift-diffusion model, we quantify 8,300% amplification of the diffusion current compared to that achieved with conventional microscale gating. Importantly, we find that this anomalous regime is governed not by total IX population, but by sharp nanoscale gradient in IX density. Our work reveals a decoupling of IX transport efficiency from density constraints and establishes a robust platform for reconfigurable exciton flux in vdW heterostructure devices.