Abstract

The interaction of light with matter is fundamental to the operation of a range of devices such as solar cells, LEDs, photocatalytic, plasmonic and many QI systems. For over 30 years, ultrafast spectroscopy has served as the key tool to understand the dynamics of the quasiparticles mediating light-matter interaction such as excitons, polarons and polaritons. However, to date, ultrafast spectroscopies were designed and largely applied to species dissolved in liquids or homogeneous bulk solids. The advent of nanoscience and thin films materials with nanoscale inhomogeneity and disorder has rendered these ensemble-based methods inadequate and they continue to be used largely because of a lack of alternatives, rather than being particularly suited to address the questions of interest. In this talk I will present first results from a new experimental platform combining unprecedented spatial, temporal, spectral and vibronic sensitivity. This allows us to follow the dynamics and motion of charges, excitons, polaritons and other quasiparticles down to 10nm length scales with 10fs time resolution, while providing few nm spectral resolution as well as information about the coupling between electronic and nuclear degrees of freedom in the system. I will highlight unexpected results including ultrafast long-range motion of photoexcitations in 2D semiconductors, organic molecules and hybrid organic-inorganic systems and how these may be harnessed in novel devices.