Twisted aggregation-induced emission luminogens (AIEgens) contribute to mechanochromism materials: a review

Abstract

Mechanochromic luminescence (MCL) materials, which are stimulated by mechanical force, have several promising advantages, such as controllable stimulus response, reversible change in fluorescence emission, high sensing ability and recyclable utilization, and thus can be widely used as memory chips, file security and encryption materials, security inks, stress sensors, organic light-emitting diodes (OLEDs), etc. During the last few decades, MCL materials have aroused great interest and become a research hotspot in the field of advanced optical materials. Aggregation-induced emission (AIE) compounds usually adopt a highly twisted chemical structure, resulting in their relatively loose molecular packing in the solid state, and thus the conformation and packing modes of AIE luminogens (AIEgens) can be altered and tuned artificially under external stimuli. Thus, considering this very interesting behavior, this review focuses on the latest advances in AIE MCL-active materials according to their structural features, ranging from organic-small molecules to complexes and polymers. Furthermore, the application and future challenges in this field are prospected.