Low-conjugation amino chromophore-stabilized oxidized cellulose for efficient room-temperature phosphorescence

Organic room-temperature phosphorescence (RTP) is typically achieved by tailoring the electronic structures of chromophore, for example, through extended π-conjugation, or by restricting nonradiative decay within the rigid microstructure. Most reported RTP systems therefore involve highly conjugated chromophores or rigid matrices, while the use of low-conjugation chromophores in bio-based frameworks remains relatively underexplored. Herein, we report an amino-chromophore-grafted design with low conjugation for stabilizing ultralong RTP in oxidized cellulose. In which, microcrystalline cellulose is selectively oxidized to dialdehyde cellulose, providing abundant aldehyde groups for the covalent grafting of amino chromophores. The resulting imine linkages and multivalent hydrogen-bonding interactions immobilize the chromophores and reconstruct a rigid local environment, thereby suppressing non-radiative decay, and stabilizing triplet excitons. These results demonstrate that coupling low-conjugation chromophores with local framework stabilization enables efficient cellulose RTP without extended π-conjugation, yielding a phosphorescence lifetime of 843.8 ms and a photoluminescence quantum yield of 12.8% and thereby placing the resultant material among the better-performing cellulose-based RTP systems reported to date. The superior phosphorescence is further demonstrated in time-gated optical encoding, phosphorescent hydrogels, and transparent afterglow wood. The design presented here enables low-conjugation amino chromophores to regulate the local microenvironment, offering a promising avenue for realizing cellulose-based RTP materials with prolonged afterglow.