Abstract: I present evidence that electron-transfer in model organic photovoltaic blends can be modeled as a competition between short and long-range electron transfer events, each described by a Marcus parabola having different reorganization energies for the most localized charge-transfer (CT) state and the mobile free charge (CT) state. Time-resolved Microwave Conductivity (TRMC) combined with photoluminescence excitation (PLE), photoinduced-absorption detected magnetic resonance (PADMR), and femtosecond transient absorption (fsTA) spectroscopy show that when electron transfer is confined to the immediate interfacial region between the donor and the acceptor very little free charge is produced. Instead, excitons split into a highly localized charge transfer state that do not produce photoconductivity. These results provide an alternative way of thinking about charge separation in organic photovoltaic materials, unify solid-state and solution phase models of charge separation, and provide unique design rules for functional donor/acceptor interfaces.
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