Tunable NIR Lasing in MOF for Multi‐Level Complex Photonic Barcodes

Abstract Developing functional photonic tags is of great importance to meet the globally increasing demand for information security and anti‐counterfeiting. However, it still suffers from the restricted encoding capacity, low complexity, and unsatisfactory confidentiality. Herein, a strategy is demonstrated to construct multi‐level complex photonic barcodes in near‐infrared (NIR) region based on a composition‐graded metal‐organic framework (MOF) heterostructure with the hierarchical encapsulation of different dye molecules. Such MOF microstructure exhibits switchable dual‐wavelength NIR lasing by adjusting the excited position, polarization direction, and pump energy. Thus, through converting the laser spectra with dynamic and regular changes to solid bars, the multi‐block photonic barcodes with three‐level encoding system are constructed, dramatically increasing the complexity and capacity. It makes the MOF‐based heterostructure with switchable lasing properties become a hard‐to‐counterfeit potential material for advanced anticounterfeiting of high‐level security.