Quasi-1D Exciton Channels in Strain-Engineered 2D Materials

Strain engineering is a powerful tool in the design of high temperature excitonic devices. Two-dimensional transition metal dichalcogenides (2D TMDCs) harbor enormous potential in this regard because they unify excellent elasticity with robust and highly mobile exciton quasiparticles. However, steering these neutral quasiparticles along predesigned pathways has proven to be exceptionally difficult.

Here, we demonstrate guiding of excitons along strain-engineered quasi-one-dimensional (1D) potential channels by combining mechanically flexible van der Waals heterostructures with single-crystal nanowires in hybrid 1D/2D systems [1]. Using ultrafast, all-optical injection and time-resolved readout, we realize highly directional exciton flow with up to 100% anisotropy both at cryogenic and room temperatures. The vanishing diffusion of excitons perpendicular to the channels highlights their efficient localization by confinement potentials and locally suppressed exciton-phonon scattering. Artificially inducing anisotropy in a pristine, otherwise fully 2D semiconductor is a promising, non-invasive approach to steering optical excitations along pre-determined pathways and opens a path towards rich quasiparticle transport phenomena in 1D.