Multimodal Fluorescence Switching Materials: One Dye to Have Them All

Abstract Off/on, on/off, and on 1 /on 2 fluorescence switching systems find application in a variety of areas, for each of which a particular dye or dye‐switch tether must be specifically designed and synthesized. Herein it is demonstrated that such tight requirement can be avoided by using easily prepared mixtures of readily available emitters and phase change materials (PCMs). By proper selection of the PCM and, if needed, additives, thermo‐ and photothermoresponsive materials showing all classes of emission switching modes can be prepared from a single dye and without chemical modifications. This strategy can be generalized to distinct emitters and, thanks to the facile and versatile printability of dye–PCM mixtures, it can be used for the fabrication of fluorescent patterns showing complex (photo)thermal responses with direct applicability in sensing and anti‐counterfeiting.