One Stimulus In Situ Induces Two Sequential Luminescence Switchings in the Same Solvent‐Fuming Process: Anthracene Excimer as the Intermediate

Abstract Commonly, one stimulus only induces one luminescence switching in stimuli‐responsive experiment. Herein, it is reported that one stimulus in situ induces two luminescent switches, resulting from two phase transitions in a solvent‐fuming process. Two phase transitions are in situ composed of a first fast and a subsequent slow process, corresponding to the change of molecular packing from the amorphous state to the π–π dimer crystalline state to the cocrystalline state with the inclusion of solvents, accompanied with luminescent transformation from pure blue to green to deep blue. Theoretical and experimental results reveal that the staggered π–π dimer stacking of anthracenes serves as the intermediate state to bridge the two phase transitions. This finding expands a new horizon in the stimuli‐responsive field and inspires novel applications in information storage and security fields.