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Stable Ultrathin Perovskite/Polyvinylidene Fluoride Composite Films for Imperceptible Multi‐Color Fluorescent Anti‐Counterfeiting Labels

As an essential part of information security in the Internet of Things (IoT), fluorescent labels possess a principal portion of anti‐counterfeiting due to its easy fabrication, low cost, and high yield. Here an ultrathin, stable, and patterned multi‐color fluorescent label with perovskite/polyvinylidene fluoride composite film is presented, which registers a resolution of 56.4 dpi and almost maintains its original fluorescent intensity after being immersed in water for 120 h. The variable color of fluorescent labels will improve the anti‐counterfeiting dimensions for the information security due to precise halogen constitutions. The imperceptible fluorescent labels are typically with a thickness of 1.2 um and a weight of 1.2 mg. They can be conformally adhered on the arbitrary curved substrate as the intelligent multi‐color fluorescent anti‐counterfeiting labels for IoT applications.