Dynamic Reversible Full‐Color Phosphorescence Afterglows from Stimuli‐Responsive Carboxymethyl Chitosan Based Materials

Pure organic stimuli-responsive persistent room-temperature phosphorescence (p-RTP) materials hold significant promise for encryption, bioimaging, sensing, and wearable optoelectronics. However, developing highly efficient smart p-RTP systems featuring full-color tunability and multi-dimensional reversible responsiveness remains a long-standing challenge, especially for nonconventional luminophores lacking significant conjugation. Herein, it is found that marine-derived carboxymethyl chitosan (CMCS) exhibits intrinsic excitation-tunable panchromatic (400-610 nm) photoluminescence (PL) and a record-high p-RTP quantum yield of 10.1% amongst nonconventional polymeric luminophores. Leveraging its outstanding PL, rigid conformation, and, moreover, inherent amino/carboxyl groups, we further construct a pyrenedicarboxylic acid salt-doped phosphorescence system that demonstrates efficient (8.8%), prolonged (515.1 ms), and dynamically tunable (495-710 nm) p-RTP with cyclable control via pH, delay time (t_d), and excitation wavelength (λ_ex). Moving beyond conventional aromatic structural modification strategies, this work achieves multimode stimuli-responsive and efficient p-RTP through the synergy between nonaromatic CMCS and aromatic chromophores, and the effective control of their intra/intermolecular interactions, chain conformation, and consequent dye aggregation, enabling versatile applications across anti-counterfeiting, encryption, information storage, and phosphorescent textiles.