Producing long afterglow by cellulose confinement effect: A wood-inspired design for sustainable phosphorescent materials

Embedding luminogens into a well-selected rigid matrix has been a particularly attractive way of preparing long afterglow materials. On this basis, seeking green, low-cost and sustainable materials or strategies, remains challenging but desirable. Prompted by the generation of wood fluorescence, a general strategy for preparing long afterglow materials successfully developed by embedding biomass-derived carbon dots into cellulose fibrils. Internal hydrogen bonding interactions between cellulose fibrils and carbon dots strongly erected a confinement effect for protecting the triplet exciton from quenching, leading to an increase of phosphorescence lifetime by seven orders of magnitude. These properties, which originated from such a green and convenient approach, were able to match most of reported long afterglow examples. Moreover, thanks to the humidity sensitivity of cellulose, the materials can behave a unique humidity-dependent phosphorescence property, showing superior potential application in advanced anti-counterfeiting and encryption.