Aggregation-induced emission: phenomenon, mechanism and applications

TLDR

Chromophore aggregation typically quenches light emission. The article reports the observation of aggregation‑induced emission (AIE) and attributes it mainly to restriction of intramolecular rotation. AIE luminogens arise from restriction of intramolecular rotation and are applied in diverse high‑tech areas such as sensing, bio‑probes, immunoassays, imaging, polarized light emission, and OLED fabrication. The authors created new AIE systems spanning the visible spectrum with quantum yields up to 100 %.

Abstract

It is textbook knowledge that chromophore aggregation generally quenches light emission. In this feature article, we give an account on how we observed an opposite phenomenon termed aggregation-induced emission (AIE) and identified the restriction of intramolecular rotation as a main cause for the AIE effect. Based on the mechanistic understanding, we developed a series of new fluorescent and phosphorescent AIE systems with emission colours covering the entire visible spectral region and luminescence quantum yields up to unity. We explored high-tech applications of the AIE luminogens as, for example, fluorescence sensors (for explosive, ion, pH, temperature, viscosity, pressure, etc.), biological probes (for protein, DNA, RNA, sugar, phospholipid, etc.), immunoassay markers, PAGE visualization agents, polarized light emitters, monitors for layer-by-layer assembly, reporters for micelle formation, multistimuli-responsive nanomaterials, and active layers in the fabrication of organic light-emitting diodes.