<i>Aequorea Victoria</i> ‐Inspired Covalent Anchoring Enables Water‐Resistant and Scalable Room‐Temperature Phosphorescence in Cellulose

Developing organic room-temperature phosphorescence (RTP) materials stable in aqueous environments remains highly challenging due to the facile quenching of triplet excitons. Inspired by the protective β-barrel architecture of the green fluorescent protein (Aequorea victoria), the study presented a covalent anchoring strategy based on an amphiphilic cellulose derivative (cellulose acetate) to construct water-resistant and scalable RTP materials. Covalent immobilization of chromophores within the rigid framework yields dynamic photoactivated afterglow, extending the lifetime from 2.1 to 946.4 ms. The resulting films retain bright RTP even under water while exhibiting water-mediated tunable mechanical properties. Furthermore, Förster resonance energy transfer with Rhodamine B enables full-color RTP spanning blue to orange. Benefiting from the inherent thermoplasticity and hydroplasticity of cellulose acetate, the RTP cellulose derivatives are readily processed into diverse 1D/2D/3D architectures and applied in multilevel information encryption. This covalent anchoring strategy offers a sustainable and commercially viable pathway to robust polysaccharide-based RTP, opening new opportunities for optoelectronics, security, and eco-friendly photonic technologies.