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

ABSTRACT 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.