A Unified Ab-Initio Framework for Studying Phonon Mediated and Limited Exciton Diffusion in Molecular Crystals

A Unified Ab-Initio Framework for Studying Phonon Mediated and LImited Exciton Diffusion
January 27, 2022
Monday, February 7, 2022

Join us for the Physics Condensed Matter Seminar at 3:00-3:30 pm
Title: A unified ab-initio framework for studying phonon mediated and limited exciton diffusion in molecular crystals

Developing a predictive first principles framework to accurately describe exciton transport in complex materials remains an open challenge. In organic semiconductors - optoelectronic materials with strong light-matter interactions and chemical tunability - understanding exciton transport is further complicated by the fact that exciton bandwidths and exciton-phonon coupling strengths are similar in magnitude. For these systems, it is unclear a priori whether exciton diffusion is best described by phonon-limited Boltzmann-like or phonon-mediated thermally activated hopping theories. Several computational approaches have been put forward to understand exciton dynamics in the hopping or band-like regime separately; however to date, few approaches exist which are general enough to be applied to both regimes in solids. In this talk, using state-of-the-art density functional perturbation theory and the ab initio GW plus Bethe-Salpeter equation approach, we develop a self-contained framework for computing exciton diffusion coefficients for solids in both the band-like and hopping exciton-polaron regimes. We apply our method to a select set of acene crystals, comparing our results in the two limits with experiments and elucidating microscopic origins of exciton diffusion in these and related materials.

Join Zoom Meeting https://berkeley.zoom.us/j/99982021890?pwd=OTMyd3cwMGp5Tk9QTW1vNk9EMDJNZz09
Meeting ID: 999 8202 1890 Passcode: 954439

Location: 3 Physics North

Speaker: Jonah B. Haber

Affiliation: UC Berkeley