Exciton transport in strained monolayer WSe2

We experimentally demonstrate the visualization of exciton energy transport in a non-uniformly strained WSe2 monolayer by monitoring the propagation of exciton densities via spectrally, temporally, and spatially resolved photoluminescence measurements at room temperature. Our measurements indicate that excitons in the WSe2 monolayer exhibit anomalous diffusion due to disorder in the system, which leads to a time-varying diffusion coefficient. In addition, we show that the sensitivity of monolayer WSe2's bandgap to strain gives rise to a built-in excitonic potential that results in the funneling of excitons towards high tensile strain points. The observed drift and diffusion agree reasonably with our proposed model that takes into account the strain field on the monolayer to describe the exciton dynamics.