Color‐Tunable Dual Persistent Emission Via a Triplet Exciton Reservoir for Temperature Sensing and Anti‐Counterfeiting

Organic persistent luminescent materials attract great attention, but most of them exhibit single luminescence color with one emission band, which limits their applications in optoelectronic, sensing, and bioimaging fields. Herein, an effective strategy to achieve dual persistent emission is proposed by utilizing the triplet excited state in the single‐molecule 6,12‐diphenyl‐5,6,11,12‐tetrahydroindolo[3,2‐b]carbazole derivatives. Experimental data and theoretical calculations suggest that the triplet excited state operates as a triplet exciton reservoir to stockpile and provide long‐lived excitons for room temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF) in aggregate state. Moreover, tunable emission color is achieved through the regulation of RTP and TADF emission by introducing aromatic and aliphatic bromine atoms. Finally, dual persistent emission with a long lifetime of 0.26 s and a persistent luminescence quantum yield of 10% is obtained in single‐component materials, and these luminophores are used for visual temperature detection and anti‐counterfeiting. Persistent thermally activated delayed fluorescence and phosphorescence emission is achieved in single‐component systems via utilizing the triplet exciton in the single compound. The dual persistent emission characteristics are tunable through the bromine atoms in different chemical environments and the organic luminophores are used for visual temperature detection and anti‐counterfeiting.