Tailoring exciton transport in strained two-dimensional semiconductors

SungWoo Nam
University of Illinois at Urbana-Champaign
Friday, August 28, 2020
4:00 pm
Zoom Meeting
Tightly bound electron-hole pairs (excitons) in two-dimensional semiconductors have emerged as prospective elements for quantum optoelectronic devices such as single photon emitters, valleytronic transistors, and solar energy harvesters. For controlled exciton transport in excitonic circuits, it is crucial to manipulate the potential energy gradient of charge-neutral excitons. In this talk, I will present strain-induced exciton funneling in monolayer tungsten diselenide (WSe2) across microns via steady-state pump-probe measurement at room temperature. Conformally deformed wrinkle architecture enabled optically-resolvable local strain to WSe2, which led to photoluminescence shift and prolonged exciton lifetime. Furthermore, strain gradient induced flux of high-energy excitons to the nearest energy minima up to few μm-away from pump point with high transport efficiency. Our results provide strong evidence for strain-driven manipulation of exciton funneling in two-dimensional semiconductors, opening up future opportunities for quantum straintronics and excitonic phase transitions.

Wilson Ho