Spatially-controlled exciton localization in mixed-dimensional van der Waals heterostructures

초록

The optical porperties of two-dimensional (2D) transition metal dichalcogenides (TMDs), characterized by excitonic emissions stemming from quantum confinement with large binding energies, have stimulated considerable research interest in exploration of their emission modes. Furthremore, controlling excitonic emission in 2D TMDs by assembling van der Waals (vdW) heterostructures offers numerous opportunities for engineering their photonic and optoelectronic properties. Here, we demonstrate a new class of mixed-dimensional vdW heterostructure, integrating 2D semiconductors with onedimensional (1D) semiconductor nanowires composed of vdW layered crystals. This configuration fosters spatially-unique excitonic emissions via a customized arrangement of atoms at the interface. By fine-tuning the axial and sidewall facets of PbI2 vdW nanowires grown from the bottom up and aligning them with single-layer WSe2 flakes, we have engineered vdW heterointerfaces with both vertical and horizontal orientations. Specifically, heterojunctions with vertically oriented PbI2 promote enhanced charge transfer and localized states along their edges, resulting in a noticeable redshift about 50 meV in excitonic