Metal organic framework@pulp fibers modified by CH3NH3PbBr3 for fluorescent anticounterfeiting and writing encryption

Perovskites nanocrystals and luminescent metal–organic frameworks (MOF) were investigated for anticounterfeiting materials because of their exciting optoelectronic and optical properties. MOFs have always served as an excellent host for encapsulating perovskite leveraging their inherent porosity. In this paper, we prepared fluorescent anticounterfeiting paper with two luminescence modes by different fluorescence properties of Tb-metal–organic framework (Tb-MOF) and perovskite (MAPbBr 3 ). In order to obtain the appropriate loading capacity of Tb-MOF on the surface of pulp fibers (PFs), the reaction conditions containing temperature, time and amount were optimized. The selection of pyromellitic acid (H 4 BTC) as a ligand not only improved the luminescence efficiency of Tb 3+ , it also increased the deposition rate of Tb-MOF due to the uncoordinated carboxyl group forming hydrogen bond with hydroxyl group of PFs. For the sake of controlling the formation rate and reducing agglomeration of MAPbBr 3 , Pb 2+ was doped in Tb-MOF. Fluorescent anticounterfeiting writing of Pb/Tb-MOF@PFs was realized by CH 3 NH 3 Br (MABr) ink. Then, Pb/Tb-MOF was used as porous templates and lead sources to prepare MAPbBr 3 @Pb/Tb-MOF with two luminescence modes at 254 nm and 365 nm UV excitation wavelength to achieve multilevel anticounterfeiting. Under excitation wavelengths of 254 nm and 365 nm, MAPbBr 3 @Pb/Tb-MOF@CFs exhibited quantum yields of 6.48% and 2.62%, respectively, while decay times of 0.77 ms and 4.96 ns were detected at an emission wavelength of 545 nm and 512 nm. Consequently, the current study not only provides a new idea for the synthesis of MAPbBr 3 and their controllable anchoring on support materials but also offers an effective method for fluorescent anticounterfeiting. Graphical abstract