The breakup of excitons into free charges in organic photovoltaics occurs at nearly a 100% efficiency for many materials.  The binding energy of the charge transfer state in these materials is much larger than kT and would indicate that the formation of free charges should not be efficient.  We use a combined quantum mechanical/molecular mechanical scheme to model the different charged states at the organic-organic interface.  The local environment at the organic-organic interface is found to play a significant role in the efficiency of forming free charges.  Effects such as poor packing, polarizability differences, and electrostatic dipoles at the interface create an unfavorable local environment for charged species.  The competition between the increase in energy from the local environment and the binding energy controls the efficiency of charge separation.

Charge dissociation at an organic-organic interface: The role of the environment

243rd National Meeting (2012)

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