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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 76: Organic semiconductors II (joint session HL/CPP)
CPP 76.4: Vortrag
Mittwoch, 18. März 2020, 16:30–16:45, POT 112
Coherent Real-Space Charge Transport Across a Donor-Acceptor Interface Mediated by Vibronic Couplings — Ziyao Xu1, Yi Zhou1, Lynn Groß2, Antonietta De Sio3, ChiYung Yam4, Thomas Frauenheim2, GuanHua Chen1, and •Christoph Lienau3 — 1Department of Chemistry, University of Hong Kong — 2BCCMS, University of Bremen — 3Institut für Physik, Universität Oldenburg — 4Beijing Computational Science Research Center
Growing experimental and theoretical evidence suggests that vibronic couplings (VCs), couplings between electronic and nuclear degrees of freedom, play a fundamental role for the ultrafast excited-state dynamics in organic donor-acceptor materials. While VC has been shown to support charge separation at donor-acceptor interfaces, so far, little is known about its role for the real-space transport of charges in these systems. Here we theoretically study charge transport in thiophene-fullerene stacks using time-dependent density functional tight-binding theory combined with Ehrenfest molecular dynamics for open systems. Our results reveal coherent oscillations of the charge density between neighboring donor sites, persisting for ~200 fs and promoting charge transport within the polymer. At the donor-acceptor interface, vibronic wave packets are launched, propagating coherently over distances of >3 nm into the acceptor region. This supports previous experimental observations of long-range ballistic charge motion in organic photovoltaic systems and highlights the possibility of VC engineering as a concept for tailoring the functionality of organic devices