Ultra‐Stable, Long‐Lived, and Multicolor Circularly Polarized Room‐Temperature Phosphorescence Enabled by Shrimp‐Derived Chitosan Nanocomposite Chemistry

Abstract Developing circularly polarized room‐temperature phosphorescent (CPRTP) materials from biomass holds great promise for chiral science and biophotonics. However, current luminescent materials face significant challenges, including color monotony in CPRTP emission and poor luminescence stability under humid and aqueous conditions. Here, a facile and versatile molecular engineering strategy to anchor arylboronic acid chromophores onto shrimp shell‐derived nanostructured chitosan films via B─O covalent bonds is presented. Synergistic B─O/H‐bond rigidification stabilizes triplet excitons and suppresses non‐radiative decay, while the intrinsic chiral nematic structure preserves circular polarization. The resulting films exhibit tunable right‐handed CPRTP emissions ranging from green to yellow to red under ambient conditions, ultralong phosphorescence lifetimes (419–805 ms), and high dissymmetry factor values (up to −0.29). Notably, these CPRTP films demonstrate exceptional photostability (stable for over six months) even after exposure to harsh hydrophilic conditions (soaking in acid, base, and salt solutions) and diverse organic solvents. Furthermore, the films possess mechanical flexibility, enabling their fabrication into various label products. Proof‐of‐concept demonstrations utilizing their fluorescence, ultralong phosphorescence, circular polarization, and time‐dependent afterglow confirm their potential in multilevel anti‐counterfeiting and optical information storage. This sustainable, scalable, shrimp‐derived CPRTP platform provides new insights for designing high‐performance biomass‐based chiroptical phosphorescent materials.