Probing Multilevel Chiroptical Activity in Organic Supramolecular Microcrystals for High‐Performance Circularly Polarized Lasing

Abstract Chiral organic materials are rapidly emerging as a promising platform for circularly polarized lasing. However, the lag in mechanistic research has severely hindered the development of organic circularly polarized lasers. Here, we attempt to probe multilevel chiroptical activity in organic supramolecular microcrystals for exploring high‐performance circularly polarized lasing. The evolution of chiroptical activity is tracked spanning from chiral molecular monomers to dimers to supramolecular helices. The crucial roles of excimers and supramolecular helices in achieving high optical gain and large chiroptical activity are revealed. Accordingly, circularly polarized lasing with low thresholds and large dissymmetry factors is realized in the organic supramolecular microcrystals. Our work marks the beginning of mechanistic research on chirality induced circularly polarized lasing, which will initiate the rational design of chiral organic materials for circularly polarized lasing.