Colloquium: Antoinetta De Sio
M143, W&N-gebouw, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam
Coherent vibronic coupling in organic photovoltaic materials
Antoinetta De Sio, Institute of Physics, Carl von Ossietzky Universität Oldenburg, Germany
Faculty of Sciences
Light-induced charge transfer from the donor to the acceptor is the primary step towards light-to-current conversion in organic photovoltaic (OPV) devices. It is known and accepted that this charge separation process occurs on an ultrafast, sub-ps time scale . However, still very little is known about the initial quantum dynamics of this photoinduced process in technologically relevant material systems. Charge photogeneration in organic materials, like conjugated polymers, is a complex process that has been described for a long time in the frame of an incoherent model, i.e. the jump of electrons from the excited donor to the acceptor. The microscopic mechanisms underlying this charge separation are still highly debated. In recent years, experimental evidence of quantum coherence in biological [2-4] and artificial light harvesting systems  is challenging this classical model. By combining coherent femtosecond spectroscopy and advanced theoretical simulations, we show evidence for the dominant role of vibronic coupling in driving charge separation in the initial stages of the dynamics in a reference material of technological relevance for OPV devices [6, 7].
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