Competing role of quantum localization and interfacial disorder in determining triplet exciton fission and recombination dynamics in polymer/fullerene photovoltaics

摘要

Non-geminate charge recombination is a significant source of carrier loss in organic photovoltaic systems. Recent experiments by Rao, et al. (Nature, 2013 500, 435-439) suggest that the recombination of triplet charge-transfer (~3CT) states can be suppressed by careful control of the molecular order in the vicinity of the phase boundary between donor and acceptor materials polymer/fullerene bulk-heterojunction devices. In short, recombination of ~3CT states is effectively suppressed when the fullerene phase exhibits a high degree of local order near the interface. Here we report upon our theoretical model that connects energetic disorder, dimensionality, and wave function localization to show that inhomogeneous broadening introduces strong coupling between the interfacial ~3CT and nearby fullerene triplet excitons and can enhance the decay of these states in systems with higher degrees of energetic disorder.