Sculpting Excitonic Landscape in Mixed-Dimensional van der Waals Heterostructures

초록

Van der Waals (vdW) heterostructures, which utilize 2-dimensional (2D) semiconducting materials like transition metal dichalcogenides (TMDs), offer superior physical and electrical properties compared to traditional silicon-based semiconductors. A critical aspect of these heterostructures is the modulation of their optical transitions via the atomic configurations at their interfaces; however, the design space for such interfaces has been largely confined to planar 2D geometries. Expanding this design space is pivotal for exploring novel excitonic phenomena. Here, we demonstrate the engineering of atomic interfaces in mixed-dimensional vdW heterostructures composed of one-dimensional (1D) nanowires and 2D TMD monolayers. Unlike conventional nanowires formed from 3D crystalline materials, our nanowires?composed of stacked 2D materials with growth-controlled orientations?exhibit sidewall facets with distinct atomic configurations. Interfacing these nanowires with 2D TMD monolayers creates atomic arrangements at the junction that are inaccessible in conventional planar vdW heterostructures. Using PbI2 nanowires on MoSe2 and WSe2, we first establish that distinct atomic registries result in localized, geometry-dependent excitonic emission, a finding supported by first-principles calculations. Building on this, we demonstrate how stack-engineered MoS2 nanowire junction can be used to sculpt the entire excitonic landscape of a WSe2 monolayer over several microns. Spatially-resolved photoluminescence mapping reveals that the junction remotely activates and suppresses distinct recombination pathways, leading to a spatial redistribution of free and bound excitonic species across the monolayer. Our findings demonstrate a powerful new strategy for the non-local control of excitonic recombination channels, providing essential insights for designing innovative ultrathin optoelectronic devices.