“…For these D–A systems, many works have been carried out to capture the CT intermediates and obtained some information about the dynamic processes by means of time-resolved transient absorption, , emission, , Raman, − and other techniques, so as to further understand the nature of CT state. The intermolecular CT between the electron donor and electron acceptor in solution has been studied and reported a lot. , However, the electronic interactions between the donor and acceptor in the cocrystals are not deeply explored because of the technical limitations. − However, it is a big challenge to characterize and explore the excited states of solid state because there are multiple influence factors to the properties of excited state of solid state, such as intermolecular CT, hydrogen bond, π–π stacking, van der Waals force, and so forth. The motivation here is that we want to explore the excited states and its dynamics in the solid state by ultrafast time-resolved spectroscopy.…”