Reduced Intrinsic Non?Radiative Losses Allow Room?Temperature Triplet Emission from Purely Organic Emitters

Persistent luminescence from triplet excitons in organic molecules is rare, as fast non-radiative deactivation typically dominates over radiative transitions. This work demonstrates that the substitution of a hydrogen atom derivative phenanthroimidazole with an N-phenyl ring can substantially stabilize excited state. stabilization converts material without phosphorescence emission into molecular system exhibiting efficient and ultralong afterglow at room temperature. Results systematic photophysical investigations, kinetic modeling, excited-state dynamic single-crystal structure analysis identify long-lived triplets originate reduction intrinsic relaxations. Further modification halogen atoms affects lifetime quantum yield. As proof-of-concept, anticounterfeiting device demonstrated time-dependent Morse code feature for data encryption based on these emitters. A fundamental design principle outlined to achieve emissive states by suppressing relaxations form vibrations or rotations.