Counterfeiting has caused great concern all over the world. What's more, the fluorescent materials play an important role in technological research and development for high-security. In this work, lead-metal-organic framework (Pb-MOF) and perovskite (MAPbBr 3 ) were used in papers to achieving fluorescence counterfeiting. Pb-MOF, as the template or precursor of MAPbBr 3 , were in-situ generated on the surface of cellulose fibers (CFs) to preparing into hand sheets (Pb-MOF@CFs). Through the analysis of experimental results, it was found that ligands, reaction systems, addition sequences of drugs, time, etc. would affect the deposition of Pb-MOF on the surface of CFs. Using CH 3 NH 3 Br (MABr) as the anti-counterfeiting ink to write on Pb-MOF@CFs, the orange writing leaped across the paper, which caused by Pb in Pb-MOF chemically reacting with MABr forming MAPbBr 3 . The orange writing displayed green fluorescence under 365 nm ultraviolet lamp excitation. The orange writing with green fluorescence could be extinguished and reconstructed, which had promise for reuse. In addition, fluorescent security papers (MAPbBr 3 @Pb-MOFs@CFs) were prepared by immersing Pb-MOF@CFs in MABr solution. The fluorescence of MAPbBr 3 @Pb-MOFs@CFs opened when the surface of it was scraped under 365 nm ultraviolet lamp. This unique fluorescence property was very important in improving the security of products. Consequently, the ongoing research on perovskite and MOFs materials is of great significance.
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 (H 4 BTC), which served as template to in situ anchoring of CH 3 NH 3 PbBr 3 (MAPbBr 3 ) to achieve the controllable synthesis of MAPbBr 3 and reduce aggregate fluorescence quenching. The CH 3 NH 3 Br (MABr) as the anti-counterfeiting ink was applied on Pb-BTC@PFs to achieve security writing. MAPbBr 3 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 MAPbBr 3 . The Pb-BTC@PFs was as the precursor to product fluorescent anti-counterfeiting paper (MAPbBr 3 @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, MAPbBr 3 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.
Zhenhua Yang,Shiyan Chen,Weili Hu,Na Yin,Wen Zhang,Cao Xiang,Huaping Wang
Flexible luminescent membranes based on bacterial cellulose (BC) were successfully fabricated by the in situ synthesis of the CdSe nanoparticles on the BC nanofibers. X-ray diffraction (XRD) patterns and field emission scanning electron microscopy (FE-SEM) revealed that CdSe nanoparticles were homogeneously dispersed on the BC nanofibers. The thermal stability of BC was greatly increased with the inclusion of CdSe nanoparticles. The CdSe/BC nanocomposite exhibited good photoluminescence properties and excellent mechanical properties. This work provides an effective method for the construction of flexible BC membranes with photoluminescence properties, which are promising for applications in the fields of security papers, sensors and flexible luminescent membranes.
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