SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 70: Poster Session V: Poster to Mini-Symposium: Frontiers of electronic-structure theory II
O 70.2: Poster
Mittwoch, 3. März 2021, 10:30–12:30, P
Non-perturbative modelling of exciton-phonon interactions in organic semiconductors — •Antonios M. Alvertis1, Timothy J.H. Hele2, and Bartomeu Monserrat3 — 1Cavendish Laboratory, University of Cambridge, J.,J.,Thomson Avenue, Cambridge CB3 0HE, United Kingdom — 2Department of Chemistry, University College London, 20, Gordon Street, London WC1H 0AJ, United Kingdom — 3Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
The optoelectronic response of organic semiconductors is dominated by excitons, which often strongly interact with phonons. This makes perturbation theory insufficient for describing exciton-phonon interactions in these materials. Here we present a non-perturbative methodology for accurately capturing exciton-phonon interactions to all orders, combining finite differences methods for phonons with GW-BSE or TD-DFT calculations for crystalline or isolated systems respectively. We show that exciton spatial delocalisation is the main parameter controlling the magnitude of its coupling to phonons and reveal the microscopic mechanism of exciton temperature- and pressure-dependence in molecular crystals. Furthermore, accounting for nuclear quantum motion is found to be critical for achieving quantitative accuracy in the prediction of exciton energies, both for single molecules and periodic systems. Overall, we provide a unified picture of exciton-vibration interactions in organic semiconductors, reconciling the complementary views of finite molecular clusters and periodic molecular solids.