Regensburg 2022 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 1: Organic Electronics and Photovoltaics 1
CPP 1.5: Vortrag
Montag, 5. September 2022, 10:45–11:00, H38
Ultrafast charge carriers separation at organic donor-acceptor interfaces - Influence of molecular vibrations — •Maximilian F. X. Dorfner1, Sebastian Hutsch1, Raffaele Borrelli2, Maxim F. Gelin3, and Frank Ortmann1 — 1Department of Chemistry, Technische Universität München, 85748 Garching b. München (Germany) — 2DISAFA, University of Torino, Largo Paolo Braccini 2, I-10095 Grugliasco (TO), Italy — 3School of Sciences, Hangzhou Dianzi University, Hangzhou 310018, China
In this work the charge transfer dynamics of photogenerated excitons at a donor-acceptor interface of an organic solar cell blend is examined. This is done by means of a fully quantum mechanical treatment of an effective Holstein model including the relevant electronic orbitals coupled to over one hundred vibrational modes, parametrized by density functional theory calculations. To solve this coupled electron-phonon system we make use of the numerically quasi-exact matrix-product-state ansatz. We find that, depending on the driving energy, different mechanisms are predominantly responsible for the charge separation at the interface. For near zero driving the ultrafast electron transfer is prevalently due to kinetic processes, while at larger driving the separation of carriers can be traced back to dissipative phonon emission connected with the dominant molecular vibrations. This charge transfer picture is consistent with a novel semi-classical hopping approach, with which we compare. These results show that dissipation of energy to the phonon is essential for charge separation for systems with a moderate driving force.