Exciton dissociation pathways in donor/acceptor blends studied by the wave packet dynamics approach

Abstract

Understanding the relationship between the energy levels and the charge photogeneration in donor/acceptor blends is crucial to improving the power conversion efficiency of organic solar cells. Here, we investigate the exciton dissociation dynamics in poly(3-hexylthiophene) (P3HT)/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blends by employing the ensemble-averaged wave packet dynamics and the Marcus–Levich–Jortner rate equation. To improve the accuracy of the wave packet dynamics method, we introduced the reorganization and temperature corrections and validated these methods against the hierarchy equation of motion method. Our analyses reveal that higher-energy charge-transfer (CT) states, often overlooked in conventional models, play a significant role in facilitating exciton dissociation. These results highlight the importance of considering the entire CT-state manifold in understanding the charge photogeneration dynamics in donor/acceptor blends.