Synergistic Photophysical Modulation via Molecular Engineering: Carbazole-Based Copolymers Enabling High-Efficiency Ultralong Room-Temperature Phosphorescence

Room-temperature phosphorescence (RTP) polymers represent promising candidates for advanced optical materials and devices. However, it remains challenging to realize efficient RTP with a long lifetime through the multidimensional structural engineering of polymers. Herein, based on the synergistic photophysical mechanism of excited-state energy transfer, rigid microenvironment, and strong intermolecular hydrogen-bonding interactions, a novel amorphous carbazole-based copolymer with room-temperature long afterglow is constructed. Flexible alkyl-chain spacers act as conformation regulators to facilitate carbazole moieties rearrangement, while polar acrylamide comonomer units synergistically construct robust intra- and intermolecular hydrogen-bonding interactions that form a rigid microenvironment, effectively suppressing nonradiative decay, triplet exciton annihilation, and emission quenching to achieve ultralong RTP in the copolymers. In particular, the carbazole-based copolymer (1-400) exhibits long-lived phosphorescence emission with a lifetime of up to 1.45 s and a remarkable afterglow duration exceeding 20 s under ambient conditions. Meanwhile, the RTP emission color of the carbazole-based copolymer can be tuned from blue to bright yellow by incorporating commercial fluorescent dyes via the triplet-to-singlet Förster-resonance energy transfer strategy. As a proof-of-concept demonstration, the organic carbazole-based RTP materials exhibit great potential for information storage and encryption. This work achieves high-performance RTP through multidimensional polymer regulation, establishing new design principles for carbazole-based materials and boosting their applications in optoelectronics.