Advanced Anti‐Counterfeiting: Integrating Humidity‐Responsive Room‐Temperature Phosphorescence and Chromism in Biomass Supramolecular Frameworks

Abstract Organic room‐temperature phosphorescent (RTP) materials are gaining prominence for their potential in anti‐counterfeiting and information security, yet challenges remain in achieving robust performance under ambient light and developing sustainable alternatives to petroleum‐based systems. This study presents a dual photo/humidity‐responsive RTP material based on biomass‐derived supramolecular networks, designed through covalent crosslinking and metal coordination strategies to enable high‐security anti‐counterfeiting under ambient light. By replacing conventional petroleum‐based matrices, renewable cellulose and α‐cyclodextrin (α‐CD) frameworks integrated with siloxane networks form rigid architectures that suppress non‐radiative transitions. The dual‐mode response mechanism integrates closed‐shell Sn ² ⁺ (d ¹⁰ ) complexes and open‐shell Co ² ⁺ (d ⁷ ) systems within α‐CD cavities, achieving humidity‐triggered chromatic switching (purple→pink) and prolonged phosphorescence lifetime (up to 676.16 ms) with a quantum yield of 0.70%. Polyvinyl alcohol (PVA)‐enhanced hydrogen‐bond networks improve durability, with the material maintaining a 6 s afterglow duration through 50 consecutive cycles. For scalable commercialization, a chameleon‐inspired hierarchical encryption system is developed, combining time‐resolved dynamic responses with Vigenère cipher algorithms to operate under daylight (chromatic transition) and UV illumination (RTP emission). Programmable film fabrication techniques further demonstrate efficient large‐area patterning capabilities. This work not only provides a sustainable paradigm for biomass‐derived smart materials in high‐security applications but also elucidates critical structure–property relationships between metal coordination geometry and RTP performance.