Temperature-controlled tunable emission of Bi-doped RbSnCl all-inorganic vacancy ordered lead-free perovskite for advanced anticounterfeiting.

At present, tuning the luminescence characteristics of phosphors by external physical stimuli such as temperature and pressure has attracted the interest of researchers. However, the emission-tunable luminescence processes by temperature or pressure in lead-free perovskite with ordered vacancy materials have not been systematically studied. In this study, Bi-doped RbSnCl crystals were successfully synthesized using a simple precipitation method, and these crystals demonstrated a remarkable enhancement of luminescence intensity compared with the unannealed ones at 140-200 °C, and with a red-shift in the emission peak from 450 to 500 nm. It was found that the annealing treatment increased the Bi-Cl bond length leading to emission red-shift and achieved the change in the emission intensity due to the band gap modulation of the material. Furthermore, a candidate material for the color-changing optical security strategies was obtained by combining the Bi-doped RbSnCl phosphor and printing ink. This work is a valuable reference for the rational design of luminescent perovskites with promising new functionalities and stimulates the great potential of luminescent perovskites in developing promising phosphors for advanced anticounterfeiting.