Boosting Red Room-Temperature Phosphorescence by Host-Guest Confinement: Acrylonitrile Derivatives in PMMA Toward Long-Lived Afterglow and Anti-Counterfeiting.

Organic room-temperature phosphorescence (RTP) materials have attracted extensive interest in optoelectronics, information encryption, and biosensing due to their unique long-lived luminescence. However, most state-of-the-art organic RTP systems suffer from short lifetimes, low quantum efficiency, and severe nonradiative quenching under ambient conditions, greatly limiting practical applications. Herein, we develop a robust host-guest confinement strategy to achieve efficient ultra-long-lived red RTP by incorporating three newly designed acrylonitrile-based luminophores (Cz-Cz, Cz-Py, and Cz-DiPy) into a rigid PMMA matrix. All doped films show intense and stable red RTP emission; the Cz-DiPy@PMMA composite affords a remarkable lifetime of 260.32 ms, nearly three orders of magnitude higher than pristine powder. Mechanistic studies combined with theoretical calculations reveal that the rigid PMMA framework restricts intramolecular motions, suppresses nonradiative relaxation, and shields triplet excitons from oxygen and collisional quenching, synergistically improving RTP performance. Enabled by excellent long-afterglow properties, these films are successfully applied to time-resolved multi-level information encryption and advanced anti-counterfeiting. This work provides a universal route to high-performance red-emissive organic RTP materials and offers valuable mechanistic insights to advance their deployment in next-generation information security and optoelectronic technologies.