title: Coherent ultrafast charge transfer in an organic photovoltaic blend.
abstract: Blends of conjugated polymers and fullerene derivatives are prototype systems for organic photovoltaic devices. The primary charge-generation mechanism involves a light-induced ultrafast electron transfer from the light-absorbing and electron-donating polymer to the fullerene electron acceptor. Here, we elucidate the initial quantum dynamics of this process. Experimentally, we observed coherent vibrational motion of the fullerene moiety after impulsive optical excitation of the polymer donor. Comparison with first-principle theoretical simulations evidences coherent electron transfer between donor and acceptor and oscillations of the transferred charge with a 25-femtosecond period matching that of the observed vibrational modes. Our results show that coherent vibronic coupling between electronic and nuclear degrees of freedom is of key importance in triggering charge delocalization and transfer in a noncovalently bound reference system.
authors.affiliation: Institut für Physik, Carl von Ossietzky Universität, 26129 Oldenburg, Germany. Center of Interface Science, Carl von Ossietzky Universität, 26129 Oldenburg, Germany.
authors.forename: Sarah Maria
authors.initials: SM
authors.lastname: Falke
authors.affiliation: Istituto Nanoscienze-Consiglio Nazionale delle Ricerche (CNR), Centro S3, via Campi 213a, 41125 Modena, Italy.
authors.forename: Carlo Andrea
authors.initials: CA
authors.lastname: Rozzi
authors.affiliation: Istituto di Fotonica e Nanotecnologie-CNR, Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy. Department of Physics and Center for Applied Photonics, University of Konstanz, 78457 Konstanz, Germany.
authors.forename: Daniele
authors.initials: D
authors.lastname: Brida
authors.affiliation: Istituto di Fotonica e Nanotecnologie-CNR, Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy.
authors.forename: Margherita
authors.initials: M
authors.lastname: Maiuri
authors.affiliation: Institut d'Électronique Fondamentale, UMR8622, CNRS, Universitè Paris-Sud, 91405 Orsay, France.
authors.forename: Michele
authors.initials: M
authors.lastname: Amato
authors.affiliation: Institut für Physik, Carl von Ossietzky Universität, 26129 Oldenburg, Germany. Center of Interface Science, Carl von Ossietzky Universität, 26129 Oldenburg, Germany.
authors.forename: Ephraim
authors.initials: E
authors.lastname: Sommer
authors.affiliation: Institut für Physik, Carl von Ossietzky Universität, 26129 Oldenburg, Germany. Center of Interface Science, Carl von Ossietzky Universität, 26129 Oldenburg, Germany.
authors.forename: Antonietta
authors.initials: A
authors.lastname: De Sio
authors.affiliation: Nano-Bio Spectroscopy Group and European Theoretical Spectroscopy Facility Scientific Development Centre, Departamento Física de Materiales, Universidad del País Vasco (UPV), Centro de Física de Materiales Consejo Superior de Investigaciones Científicas-UPV/Euskal Herriko Unibertsitatea-Materials Physics Center and Donostia International Physics Center, Avenida Tolosa 72, 20018 San Sebastián, Spain. Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany.
authors.forename: Angel
authors.initials: A
authors.lastname: Rubio
authors.affiliation: Istituto di Fotonica e Nanotecnologie-CNR, Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy.
authors.forename: Giulio
authors.initials: G
authors.lastname: Cerullo
authors.affiliation: Istituto Nanoscienze-Consiglio Nazionale delle Ricerche (CNR), Centro S3, via Campi 213a, 41125 Modena, Italy. Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università di Modena e Reggio Emilia, via Campi 213a, 41125 Modena, Italy. elisa.molinari@unimore.it christoph.lienau@uni-oldenburg.de.
authors.forename: Elisa
authors.initials: E
authors.lastname: Molinari
authors.affiliation: Institut für Physik, Carl von Ossietzky Universität, 26129 Oldenburg, Germany. Center of Interface Science, Carl von Ossietzky Universität, 26129 Oldenburg, Germany. elisa.molinari@unimore.it christoph.lienau@uni-oldenburg.de.
authors.forename: Christoph
authors.initials: C
authors.lastname: Lienau