Regulating Multicolor Luminescence in Single‐Component Systems: From Molecular Conformation to Photoactive Aggregates

ABSTRACT

Single‐component multicolor luminescent materials provide a well‐defined platform to understand how molecular structure, excited‐state dynamics, and packing govern emission. Compositionally, such systems avoid phase separation, uncontrolled energy transfer, compositional instability, and the need for precise mixing ratios. This mini review highlights recent advances in this field, focusing on three interrelated themes: competitive excited‐state relaxation pathway modulation, molecular conformation engineering, and intermolecular packing regulation. In some cases, emission arises from competition among relaxation pathways associated with different excited states. These pathways can lead to conventional emission from the lowest excited state or anti‐Kasha emission from higher lying excited states. Among these excited states, charge‐transfer states are particularly sensitive to intra‐ and intermolecular electronic coupling, enabling tunable emission colors. In addition, molecular conformation can be regulated through intramolecular rotation, structural deformation, and bending‐to‐planarization, thereby influencing electronic structure and excited‐state relaxation. In aggregates, intermolecular interactions and packing motifs further modify conformation and luminescence. These strategies enable diverse single‐component multicolor systems for sensing, information encryption, anti‐counterfeiting, and light‐emitting devices. Remaining challenges and future directions for rational design are also discussed.