Photocurrent Generation in Polymer-Fullerene Bulk Heterojunctions

The photocurrent in conjugated polymer-fullerene blends is dominated by the dissociation efficiency of bound electron-hole pairs at the donor-acceptor interface. A model based on Onsager's theory of geminate charge recombination explains the observed field and temperature dependence of the photocurrent in $\mathrm{P}\mathrm{P}\mathrm{V}\ensuremath{\mathbin:}\mathrm{P}\mathrm{C}\mathrm{B}\mathrm{M}$ blends. At room temperature only 60% of the generated bound electron-hole pairs are dissociated and contribute to the short-circuit current, which is a major loss mechanism in photovoltaic devices based on this material system.