Visible‐Light‐Activated Organic Room‐Temperature Phosphorescence via Supramolecular Self‐Assembly in Single‐Component Crystal

Abstract Visible‐light‐excited room‐temperature phosphorescence (RTP) materials possess significant potential for various practical applications, especially for biological and life related fields. However, developing highly simplified and easily accessible RTP materials that can be activated by visible light remains a significant challenge. Herein, a facile one‐step oxidative strategy is reported to directly convert unsubstituted phenothiazine molecule into a self‐assembled supramolecular architecture, which exhibits highly efficient RTP with an impressively long lifetime of 305 ms and a phosphorescence quantum yield of 2.0%. The resulting supramolecular framework based on single‐component molecular crystal can be formed via abundant hydrogen bonds and π ··· π interactions. These intermolecular forces construct a rigid 3D network that effectively confine molecular motion, which not only promotes intermolecular electronic coupling and increases the concentration of triplet excitons but also suppresses nonradiative decay pathways of triplet excitons. These factors collectively induce the redshifted absorption and enable visible‐light‐excited RTP in the extremely simple supermolecules. Given these features, it is successfully applied in multi‐level data encryption and decryption. This work provides a promising strategy for the development of single‐component RTP materials under visible excitation.