Precise Molecular Design for High‐Performance Luminogens with Aggregation‐Induced Emission

Precise design of fluorescent molecules with desired properties has enabled the rapid development of many research fields. Among the different types of optically active materials, luminogens with aggregation‐induced emission (AIEgens) have attracted significant interest over the past two decades. The negligible luminescence of AIEgens as a molecular species and high brightness in aggregate states distinguish them from conventional fluorescent dyes, which has galvanized efforts to bring AIEgens to a wide array of multidisciplinary applications. Herein, the useful principles and emerging structure–property relationships for precise molecular design toward AIEgens with desirable properties using concrete examples are revealed. The cutting‐edge applications of AIEgens and their excellent performance in enabling new research directions in biomedical theranostics, optoelectronic devices, stimuli‐responsive smart materials, and visualization of physical processes are also highlighted.