Charge-Transfer Dynamics in the Lowest Excited State of a Pentacene-Fullerene Complex: Implications for Organic Solar Cells

We characterize the dynamic nature of the lowest excited state in a pentacene/C₆₀ complex on the femtosecond time scale, via a combination of ab initio molecular dynamics and time-dependent density functional theory. We analyze the correlations between the molecular vibrations of the complex and the oscillations in the electron-transfer character of its lowest excited state, which point to vibration-induced coherences between the (pentacene-based) local-excitation (LE) state and the complex charge-transfer (CT) state. We discuss the implications of our results on this model system for the exciton-dissociation process in organic solar cells.