Cyclization-enhanced photoactivatable reversible room-temperature phosphorescence for efficient real-time light printing

Abstract

The construction of polymer-based photoactivated room-temperature phosphorescence systems remains a prominent research focus, yet the development of ultrafast activated systems under ambient conditions continues to pose a challenge. In this study, cyclized phenothiazine derivatives bearing diverse substituents are synthesized and incorporated into an amorphous polyvinyl alcohol (PVA) matrix, resulting in significantly enhanced dynamic photoactivation characteristics compared with those of their pristine monomeric counterparts. Under ambient conditions and 2 s irradiation, the lifetime and quantum yield of C[4]PTZ-OH@PVA increase by factors of 1.96 (from 11.8 to 23.1 ms) and 3.43 (from 8.62% to 29.53%), respectively, relative to those of PTZ-OH@PVA. Theoretical calculations and experimental data reveal the mechanism of ultrafast photoactivation: (1) the rigid cyclic architecture suppresses non-radiative decay and enhances the probability of intersystem crossing pathways; (2) the hydroxyl-substituted phenothiazine derivatives form an extensive hydrogen-bonding network with PVA, providing isolation from oxygen and moisture invasion while suppressing molecular vibrations. This synergistic effect enables rapid depletion of residual ³O₂ under irradiation, thereby accelerating the photoactivation of C[4]PTZ-OH@PVA. Notably, various patterns are printed on the films within 2 s, and then quickly erased after annealing. This study proposes a novel cyclization-enhanced strategy for photoactivated room-temperature phosphorescence, offering valuable guidance for the development of high-performance light-responsive materials.