Vibronic coupling in organic semiconductors for photovoltaics

Light-induced charge transfer from the photoexcited donor to the acceptor is the fundamental step towards current generation in organic solar cells. Experimental evidence for efficient charge separation on ultrafast time scales has been available for quite some time. Yet even today, the elementary mechanisms underlying this process in organic semiconductors and in particular the role of the coherent wave-like motion of electrons and nuclei for the charge separation are still a matter of considerable debate. In this perspective, we present a survey of the current understanding on the role of quantum coherences in organic semiconductors. Specifically, we discuss the role of vibronic couplings for ultrafast charge separation dynamics with particular attention on the potential implications for the light-to-current conversion process in photovoltaic devices.