Enhancing downshift luminescence of Sm3+ ions in Cs2NaBiCl6 double perovskites through alloy Sb3+ ions for thermometry and anti-counterfeiting

Here, a new type of Sb 3+ /Sm 3+ ions heavy concentration doped Cs 2 NaBiCl 6 double perovskites was successfully synthesized by solvothermal route. The downshifting photoluminescence properties of all samples are analyzed in detail, and the luminescence mechanism is further elucidated by fluorescence decay lifetime. Upon excitation at 354 nm, a strong blue emission band(400–500 nm) is observed for Cs 2 NaBiCl 6 :Sb 3+ , which comes from self-trapping exciton(STE) recombination of distorted [SbCl 6 ] 3– . Benefiting from Sb 3+ -induced local structural modification and narrow optical band gap, both STE broadband and Sm 3+ ions visible luminescence emissions are significantly boosted through free exciton(FE) sensitization in Cs 2 NaBiCl 6 :Sb 3+ /Sm 3+ sample. In addition, the luminescence thermal performances of Cs 2 NaBiCl 6 :Sb 3+ /Sm 3+ sample are investigated from 93 to 293 K. The luminescence thermal enhancement phenomenon is obtained at lower temperature range. The optical temperature sensing performance is discussed with luminescence intensity ratio technique, with maximum relative sensitivity of 5.676 % K −1 at 213 K. Finally, the anti-counterfeiting application of Cs 2 NaBiCl 6 :Sb 3+ /Sm 3+ sample is elaborated due to their bright multi-color emission under different excitation and temperature.