Large-Scale Fabrication of Room-Temperature Phosphorescence Cellulose Filaments with Color-Tunable Afterglows

The large-scale fabrication of long-lived and sustainable room-temperature phosphorescence (RTP) materials with color-tunable afterglow is of considerable practical importance in diverse optoelectronic applications but remains challenging. Herein, based on a process for the mass production of cellulose acetoacetate filaments, large-scale RTP filaments are synthesized by introducing amino-bearing luminophores via a mild enamine reaction. Attributed to efficient intersystem crossing facilitated by acetoacetyl and benzoyloxy groups alongside a rigid environment provided by multiple hydrogen bonding, the resulting filaments exhibit impressive RTP with a lifetime of 772 ms and a phosphorescence quantum yield of 45.06%. Furthermore, the afterglow color of RTP filaments is rationally modulated from blue to greenish-yellow to rosy-red through triplet-to-singlet Förster resonance energy transfer. Meanwhile, the formation of diverse clusters with comparable but different lifetimes leads to interesting excitation-dependent afterglows. This work not only provides an effective strategy to construct long-lived, color-tunable, sustainable afterglows but also establishes large-scale and continuous preparation routes for functional cellulose filaments.