Exciton Dynamics in Edge-on ZnPc–F₈ZnPc System: Insights from Quantum Simulations^†

Focusing on the mechanism of interfacial exciton dissociation in edge-on stacked ZnPc–F₈ZnPc aggregate, we employ the fragment particle-hole densities (FPHD) method to construct the Hamiltonian of diabatic states and use the non-Markovian stochastic Schrödinger equation (NMSSE) to simulate the photo-induced dynamics processes. The results show that aggregation effects have a significant impact on the interfacial exciton dissociation process. After photo-excitation, the excitons first preferentially delocalize and perform the charge transfer (CT) states in the pure ZnPc or F₈ZnPc aggregates within 100 fs. These ‘intramolecular’ CT states can easily evolve into interfacial CT states by hopping electrons and holes in the intramolecular CT states across the interface. Compared with these exciton dissociation processes, the direct exciton dissociation into interfacial CT state is relatively slow due to the small electronic coupling and vibrational coherence between the locally excited state and the interfacial CT state. As the temperature rises and the vibronic coherence weakens, the direct dissociation rates are significantly enhanced. This investigation provides valuable insights for the design and optimization of high-performance organic photovoltaic devices.