Who: Sivan Refaely-Abarmson, University of California, Berkeley; Lawrence Berkeley National Laboratory
Place: Donostia International Physics Center
Date: Thursday, 30 August 2018, 12:00
New developments in the theory of excited-state phenomena can lead to better understanding of nanoscale mechanisms of processes in photophysics and predictions of new materials hosting such phenomena. In this talk, I will discuss recent studies using ab initio many-body perturbation theory to uncover and understand such mechanisms in extended materials. I will present a new approach to calculate multi-exciton generation in solids from first principles and describe an application of this approach to singlet fission in organic crystals. Focusing on crystalline pentacene, I will discuss a newly discovered exciton?bi-exciton coupling channel and a new selection rule for singlet fission, associated with the crystal symmetry and structure. Additionally, I will describe a recent study of excited state properties in monolayer transition metal dichalcogenides with structural defects; these impurities can give rise to localized states, introduce strongly-bound excitons below the absorption edge, and reduce the valley-selective circular dichroism. These findings suggest a novel pathway to tune spin-valley polarization and other optical properties through defect engineering.
Host: Sara Barja