Patterned Lead‐Free Double Perovskite/Polymer Fluorescent Piezoelectric Composite Films for Advanced Anti‐Counterfeiting

The limitations of single fluorescent anti-counterfeiting technologies necessitate the development of more sophisticated encryption methods to protect information and data. Traditional optical anti-counterfeiting encryption techniques, which rely on light sources with varying wavelengths to identify information, are now insufficient to meet contemporary security demands due to their restricted response to a narrow range of wavelengths. In this study, the fabrication of patterned, lead-free double perovskite (DP)/poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) fluorescent piezoelectric composite films (CFs) is reported. These CFs integrate the up-conversion and down-conversion photoluminescent properties of Cs