Dresden 2017 – wissenschaftliches Programm
HL 36.5: Vortrag
Dienstag, 21. März 2017, 10:30–10:45, POT 251
Vibronic coherence in a reference organic photovoltaic blend — •Antonietta De Sio1, Ephraim Sommer1, James Lim2, Susana F. Huelga2, Martin B. Plenio2, Giulio Cerullo3, and Christoph Lienau1 — 1Institut für Physik, Universität Oldenburg, Germany — 2Institut für Theoretische Physik, Universität Ulm, Germany — 3Department of Physics, Politecnico di Milano, Italy
The microscopic mechanisms underlying charge separation in organic solar cells are still highly debated. Although recent theoretical work  suggests that vibronic couplings may lie at the origin of efficient charge generation in such systems, clear experimental evidence on the role of vibronic coherence for charge separation is still lacking. Here we use ultrafast two-dimensional electronic spectroscopy with 10-fs time resolution to investigate the initial dynamics of excitons and polaronic species in P3HT and P3HT:PCBM thin films with different acceptor concentration. Our experimental results, supported by theoretical simulations, show that strong vibronic coupling favors exciton delocalization and accelerates charge separation even in presence of disorder, resulting in long-lived coherent oscillatory dynamics of strongly correlated excitons and polaron pair states, mutually coupled to a dominant vibrational mode. These results allow us to gain fundamental new insights into the initial dynamics of charge separation and may open up new perspectives for optimizing devices [2,3].
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