Insights on interfacial charge transfer across P3HT/fullerene photovoltaic heterojunction from ab initio calculations

The interfacial charge-transfer mechanism of the P3HT/fullerene photovoltaic heterojunction is elucidated using density functional theory calculations. Our findings indicate that an efficient adiabatic electron transfer is highly probable due to the presence of an extended electronic state that has a significant probability distribution across the interface in the lowest excited state. Furthermore, efficient exciton dissociation is possible because this bridging state has significant overlap with near-degenerate unoccupied states that are localized on the fullerene.