Wide‐Range Tunable Fluorescence Lifetime and Ultrabright Luminescence of Eu‐Grafted Plasmonic Core–Shell Nanoparticles for Multiplexing

Wide‐range, well‐separated, and tunable lifetime nanocomposites with ultrabright fluorescence are highly desirable for applications in optical multiplexing such as multiplexed biological detection, data storage, and security printing. Here, a synthesis of tunable fluorescence lifetime nanocomposites is reported featuring europium chelate grafted onto the surface of plasmonic core–shell nanoparticles, and systematically investigated their optical performance. In a single red color emission channel, more than 12 distinct fluorescence lifetime populations with high fluorescence efficiency (up to 73%) are reported. The fluorescence lifetime of Eu‐grafted core–shell nanoparticles exhibits a wider tunable range, possesses larger lifetime interval and is more sensitive to separation distance than that of ordinary Eu‐doping core–shell type. These superior performances are attributed to the unique nanostructure of Eu‐grafed type. In addition, these as‐prepared nanocomposites are used for security printing to demonstrate optical multiplexing applications. The optical multiplexing experiments show an interesting pseudo‐information “a rabbit in a well” and conceal the real message “NKU.”