Manipulating Excitons in van der Waals Materials with Strain and Dielectric Nanobubbles

The optoelectronic and transport properties of two-dimensional (2D) semiconductors such as transition metal dichalcogenides (TMDs) are highly sensitive to minute atomic displacements and to their local environments. This sensitivity offers unique opportunities for post-synthesis reconfiguration of material function. In this talk, I will show that the motion of excitons (electron-hole pairs) in TMDs can be manipulated with nanoscale precision by creating nanoscale strain and dielectric inhomogeneities known as nanobubbles. Using ultrafast optical scattering microscopy, we directly monitor exciton funneling into these nanoscale regions with femtosecond resolution and nanometer precision. Our imaging approach reveals that interactions between bright and dark excitons in TMDs depend strongly on the dielectric properties of their local environment, providing new opportunities for sensing as well as a highly effective and non-invasive strategy to manipulate exciton transport at the nanoscale in 2D materials.