Excited State Dynamics of Aggregation-Induced Emission Molecules

Abstract

Many organic molecules exhibit weak luminescence in the solid state due to aggregation-caused quenching, while exhibiting strong luminescence in solution. In contrast, aggregation-induced emission (AIE) is a phenomenon that enables strong luminescence in the solid state and has attracted much attention from the viewpoint of application in the solid-state emissive materials. Thus, it is essential to understand the AIE mechanism including the excited-state dynamics. In the early stages of advocating the AIE phenomenon, the quantum mechanical studies proposed the restriction of the intramolecular motion (RIM) model for the AIE mechanism. Recently, both quantum chemical calculations and time-resolved spectroscopies have suggested the contribution of the conical intersection (CI) and deduced the importance of restricted access to a conical intersection (RACI) model in the potential energy surface (PES). In this review, we introduce recent studies on the excited-state dynamics of AIE compounds and molecular design strategies guided by this understanding.