Multifunctional AIE Molecules Possessing Long-lasting Room Temperature Phosphorescence, Thermally Activated Delayed Fluorescence and Dual-mode Mechanochromism

Two simple donor-acceptor multifunctional pure organic light-emitting molecules[(9H-carbazol-9-yl)(4-hydroxyphenyl)-methanone(CzMP) and (4-hydroxyphenyl)(10H-phenothiazin-10-yl)methanone(PTZMP)] with distinct aggregation-induced emission(AIE) properties were synthesized. Surprisingly, CzMP showed a long room temperature phosphorescence lifetime (>900 ms), and PTZMP exhibited triple emission of prompt fluorescence(PF), room temperature phosphorescence(RTP) and thermally activated delayed fluorescence(TADF). Furthermore, CzMP effectively responded to mechanical external forces and solvent fumigation, exhibiting dual-mode mechanochromic luminescence(MCL) including multiple fluorescence color shifts and phosphorescence switching. Time-dependent density functional theory(TDDFT) calculations were investigated to explain different luminescence properties of the two molecules, and the single crystal of CzMP was obtained and analyzed to demonstrate the unique molecular stacking pattern and strong intermolecular interactions in close association with phosphorescence emission. The multifunctional luminescent properties of the emitters explored in this work could be more effectively applied to a wide range of applications, such as information encryption and anti-counterfeiting.