Water-Unquenchable Ultralong Room-Temperature Phosphorescent CDs@SiO2 Composites for Information Encryption and Anticounterfeiting Applications
Room-temperature phosphorescence (RTP) materials are critical for anticounterfeiting, yet their practical deployment in aqueous media is severely constrained by average lifetimes below 1 s due to moisture- and oxygen-induced quenching. This study introduces an ex-situ covalent coupling strategy to fabricate liquid-phase ultralong RTP composites by covalently anchoring feather-derived carbon dots (CDs) onto SiO2 microspheres. The resulting CDs@SiO2 microspheres exhibit an aqueous dispersion lifetime of 2.38 s and an absolute quantum yield of 22%, while the solid-state composite achieves an average lifetime of 3.04 s—surpassing existing carbon-based RTP materials. The enhanced phosphorescence originates from Si–O–C covalent bond immobilization and Si–O–Si rigid networks that suppress nonradiative decay. The composites display reversible water-responsive structural colors, blue fluorescence, and cyan RTP, enabling multilevel information encryption and high-level anticounterfeiting. These findings establish a scalable route for water-resistant, long-lived RTP materials with dual-mode optical security features.