Simultaneous tunable fluorescence lifetime and upconversion luminescence enhancement of NaLuF4:Er3+/Yb3+ microcrystals through heavily doped KF for multiplexing

Abstract A strategy is demonstrated for enhanced upconversion luminescence and significantly realized tunable fluorescence lifetime of NaLuF4 by simply doping KF. The upconversion luminescence intensities of the green and red are remarkably enhanced for molar ratio KF/Ln(Lu/Yb/Er) 80% doped NaLuF4 microcrystals compared to that without KF. Moreover, the fluorescence lifetime of NaLuF4 is tunable in a wide range depending on the doping molar ratio of KF. In a single 541 nm emission channel, 7 different fluorescence lifetimes ranging from 87.44μs to 285.47μs can be obtained. These superior performances are attributed to the tailored local environment. In addition, we use three of the materials to demonstrate multiplexing. Under 980 nm excitation, it displays the fake information “8”. However, scanning the security pattern in the time domain shows the real messages “1” and “9”.