Single‐Luminophore Molecular Engineering for Rapidly Phototunable Solid‐State Luminescence

Smart materials enabling emission intensity or wavelength tuning by light stimulus attract attention in numerous cutting‐edge fields. However, due to the generally dense molecular stacking against photoresponsivity in solid states, especially in crystals, developing rapidly phototunable solid‐state luminescent systems remains challenging. Herein, we propose a new luminophore that serves as both a photoresponsive unit and a luminescent group, while possessing enhanced conformational freedom to provide a solution. Namely, photoexcitation‐induced molecular conformational change of an ionized persulfurated arene based on weak intermolecular aliphatic C–H···π interaction was employed. On these basis, rapidly enhanced phosphorescence upon irradiation can be observed in a series of phase states, like solution state, crystal, and amorphous state, especially with a high photoresponsive rate of 0.033 s‐1 in crystal state that is superior to the relevant reported cases. Moreover, a rapidly phototunable afterglow effect is achieved by extending this molecule into some polymer‐based doping systems, endowing the system with unique dynamic imaging and fast photopatterning capabilities. Such a single‐luminophore molecular engineering and the underlying mechanism have implications for building different condensed functional materials, principally for those with stimuli responses in solid states.