Noise-induced quantum coherence drives photocarrier generation dynamics at polymeric semiconductor heterojunctions

We present a fully quantum-mechanical model of the electronic dynamics of primary photoexcitations in a polymeric semiconductor heterojunction, which includes both polymer stacking and phonon relaxation. By examining the phonon-induced fluctuations in the state-to-state energy gaps and the exact golden-rule rate constants, we conclude that resonant tunnelling between the primary exciton to delocalized interchain charge-transfer states may be the initial step in the formation of charge-carriers in polymer-based bulk-heterojunction photovoltaic diodes.