Exploring Many-body Effects on the Dynamics of Optical Excitations in Low-Dimensional Materials
Diana Qiu, Mechanical Engineering & Materials Science, Yale University
In low-dimensional and nanostructured materials, the optical response is dominated by correlated electron-hole pairs—or excitons—bound together by the Coulomb interaction. Understanding the energetics and dynamics of these excitons is essential for diverse applications across optoelectronics, quantum information and sensing, as well as energy harvesting and conversion. By now, it is well-established that these large excitonic effects in low dimensional materials are a combined consequence of quantum confinement and inhomogeneous screening. However, many challenges remain in understanding their dynamical processes, especially when it comes to correlating complex experimental signatures with underlying physical phenomena through the use of quantitatively predictive theories. In this talk, I will discuss how excitons in low-dimensional and nanostructured materials, such as monolayer transition metal dichalcogenides, few-layer black phosphorus, carbon nanotubes, and molecular crystals, differ from typical bulk materials. In particular, we will look at how symmetry and dimensionality manifest in the exciton bandstructure and how those features of exciton dynamics and transport. I will also discuss new methods we have developed to simulate exciton dynamics, including exciton-phonon interactions, and core-level excitations associated with x-ray absorption spectra.
Host: Walter Lambrecht