Polymerization Based on Modified β‐Cyclodextrin Achieves Efficient Phosphorescence Energy Transfer for Anti‐Counterfeiting

Abstract Supramolecular polymerization can not only activate guest phosphorescence, but also promote phosphorescence Förster resonance energy transfer and induce effective delayed fluorescence. Herein, the solid supramolecular assemblies of ternary copolymers based on acrylamide, modified β‐cyclodextrin (CD), and carbazole (CZ) are reported. After doping with polyvinyl alcohol (PVA) and dyes, a NIR luminescence supramolecular composite with a lifetime of 1.07 s, an energy transfer efficiency of up to 97.4% is achieved through tandem phosphorescence energy transfer. The ternary copolymers can realize macrocyclic enrichment of dyes in comparison to CZ and acrylamide copolymers without CD, which can facilitate energy transfer between triplet and singlet with a high donor–acceptor ratio. Additionally, the flexible polymeric films exhibit regulable lifetime, tunable luminescence color, and repeatable switchable afterglow by adjusting the excitation wavelength, donor–acceptor ratio, and wet/dry stimuli. The luminescence materials are successfully applied to information encryption and anti‐counterfeiting.