Dynamic Control of Two‐Component Aggregation and Color‐Tunable Emission via Charge‐Transfer Coassembly

ABSTRACT Aggregation‐induced emission luminogens (AIEgens) have become a vital class of functional materials for optoelectronic and biomedical applications. Extending AIE behavior from single‐component to two‐component systems opens a new avenue for modulating emission through intermolecular interactions, yet it also introduces substantial complexity in understanding and controlling the aggregation process. In particular, elucidating how multicomponent molecular packing governs macroscopic photophysical behavior remains a central challenge. Herein, we constructed four distinct charge‐transfer (CT) cocrystals through the coassembly of electron‐rich dibenzo‐heterocyclic donors and electron‐deficient 1,2,4,5‐tetracyanobenzene (TCNB) acceptors. The cocrystallization process allows precise manipulation of the dynamic aggregation pathway by tuning the DMSO/H 2 O ratio. Intriguingly, the morphology evolves from amorphous aggregates to rod‐like and finally to needle‐like microcrystals, showing a nonmonotonic size variation with increasing water content, accompanied by a gradual enhancement of fluorescence intensity. The four CT complexes exhibit wide emission tunability from green to orange‐red, and notably, the AIE‐active DBT/TCNB pair enables a practical demonstration in water‐jet rewritable encryption paper. Overall, this work establishes a simple yet effective paradigm for designing high‐performance solid‐state emitters, while unveiling fundamental principles that govern the controllable molecular assembly in multicomponent luminescent systems.