Application of perovskite crystal on lead-metal–organic frameworks @pulp fibers for fluorescent anti-counterfeiting

Fluorescent anti-counterfeiting paper was a very important kind of special paper, which played an important role in people’s life, such as paper money. In this work, fluorescent anti-counterfeiting paper was prepared by using lead-metal–organic framework (Pb-BTC) that was in situ formed on the surface of pulp fibers (PFs) with lead ions and pyromellitic acid (H₄BTC), which served as template to in situ anchoring of CH₃NH₃PbBr₃ (MAPbBr₃) to achieve the controllable synthesis of MAPbBr₃ and reduce aggregate fluorescence quenching. The CH₃NH₃Br (MABr) as the anti-counterfeiting ink was applied on Pb-BTC@PFs to achieve security writing. MAPbBr₃ forming writing was invisible under sunlight but displayed green fluorescence under 365 nm ultraviolet lamp excitation. The writing with green fluorescence could be extinguished by water and reconstructed by forming new MAPbBr₃. The Pb-BTC@PFs was as the precursor to product fluorescent anti-counterfeiting paper (MAPbBr₃@Pb-BTC@PFs) reacted with MABr in ethanol solution, so that the green fluorescence of it was opened under 365 nm ultraviolet lamp. When it was exposed to polar solution, MAPbBr₃ structure collapsed. Since Pb-BTC was stably in paper and was not easy to lose in polar solution, it could be reused several times on the premise that the paper structure was not damaged, which demonstrated an advantage over using perovskite alone in paper. Consequently, the current study not only provided a new idea for controllable anchoring perovskite on support materials, but also offered a new method for producing fluorescent anti-counterfeiting paper.