Modulating molecular aggregation of luminogens: Bridging the gap between solutions and solids

In the past two decades, the advancement of aggregation-induced emission (AIE) has greatly advanced our understanding of organic luminescence and facilitated the application of organic luminescent materials. AIE luminogens (AIEgens) emit weakly in solutions but strongly in aggregated states. This significant difference in luminescence between solutions and aggregated states of AIEgens has shown that there is much to explore in the mesoscopic world (the intermediary phase). Accordingly, the research paradigm of aggregate science is proposed. The path to new aggregate materials relies not only on molecule syntheses but also on the control of molecular aggregation, which bridges the gap between solutions and solids. In this Perspective, we outline three general strategies for managing molecular aggregation to stimulate new ideas and provide guidance on controllable molecular aggregation.