▎ 摘　　要

The intermolecular interaction determines the photo-physical properties of the organic aggregates, which are critical to the performance of organic photovoltaics. Here, excitonic coupling, an important inter-molecular interaction in organic aggregates, between the pi-stacking graphene quantum dots is studied by using transient absorption spectroscopy. We find that the spectral evolution of the ground state bleach arises from the dynamic variation of the excitonic coupling in the excited pi-stacks. According to the spectral simulations, we demonstrate that the kinetics of the vibronic peak can be exploited as a probe to measure the dynamics of excitonic coupling in the excited pi-stacks.