Aggregation-Induced Anti-Kasha Emission: Unraveling Multimodal Luminescence Mechanisms in a Single Molecule With Five Morphologies

Abstract

In recent years, the exploration of emission pathways from high-excited states in organic luminogens has received extensive attention owing to the anti-Kasha's rule emission with the potential of improving the exciton utilization. However, it is extremely difficult to predict the anti-Kasha effect and estimate the luminescent mechanism of high-energy excited states. We here present a rational design on the basis of the intermolecular noncovalent interactions to achieve the purpose of altering the molecular optoelectronic properties and regulating the distribution of high-energy excited state. The emitter, p-Py-SO₂-DMAC, with π–π dimer stacking is designed and synthesized, which not only exceptionally shows five aggregation morphologies and presents the infrequent aggregation-induced anti-Kasha's rule emission, room-temperature phosphorescence (RTP), and mechanoluminescence (ML) behaviors simultaneously, but also possesses the features of thermally activated delayed fluorescence (TADF) and aggregation-induced emission (AIE). The multiple luminescent mechanisms have been scientifically verified by experimental and theoretical investigations.