Covalent–supramolecular multivalent synergy coupling enables ultralong and robust sustainable organic phosphorescence

Achieving ultralong room-temperature phosphorescence (RTP) in organic systems that simultaneously combine environmental robustness and dynamic responsiveness remains a challenge, particularly for sustainable polymer platforms. Herein, we combine covalent bonding and supramolecular interactions to construct thermal-resistant and multi-stimulus responsive phosphorescent materials. Specifically, the triphenylen-2-ylboronic acid (TPB) chromophores are firmly immobilized within a supramolecular network composed of cellulose and γ-cyclodextrin (CD) through covalent bonds and multivalent non-covalent interactions. The supramolecular network can achieve high rigidity and dynamic adaptability, effectively suppressing the non-radiative decay of the TPB molecules and stabilizing triplet excitons. The resulting film exhibits an RTP lifetime of up to 4.34 s, with a persistent afterglow exceeding 1 min and excellent high-temperature ultralong phosphorescence, even at 423 K. The system further shows reversible responses to pH and humidity, allowing dynamic modulation of phosphorescence emission. By coupling long-lived triplet excitons with a triplet-to-singlet Förster resonance energy transfer (TS-FRET) platform, multi-color and time-resolved afterglow emission is realized. Benefiting from processability of cellulose, the RTP materials can be processed into diverse 1D/2D/3D architectures, enabling applications in crack detection, multi-level information encryption and wearable photonics. This work has advanced the development of sustainable phosphorescent materials with excellent environmental tolerance, confirming their significant potential for use in advanced optical applications.