Realize intelligent anti-counterfeiting and efficient near-infrared emission of indium-based perovskite through crystal phase and energy band engineering.

The crystal phase and energy band adjustment of halide perovskites have become the focus of research. Sb3+ doped lead-free indium-based perovskites A 2 InX 5 ·H 2 O:Sb3+ (A=Cs+, Rb+; X = Cl-, Br-) are synthesized at room temperature. Through changing the crystal phase structure, an intelligent anti-counterfeiting material is used to monitor water vapor and high temperature. Moreover, the Rb 2 InBr 5 ·H 2 O:Sb3+ achieves broadband near-infrared (NIR) emission with a high photoluminescence quantum efficiency (PLQY) of 54.3%. The NIR light-emitting diode shows that the device can effectively achieve NIR imaging. Theoretical calculations further clarified that the regular changes in luminescence originate from energy band modulation. This work provides a broader sight for the synthesis, luminescence mechanism and application of indium-based perovskite. • Indium-based perovskite with controllable luminescence properties was synthesized at room temperature. • The reversible change of crystal phase is used for smart anti-counterfeiting. • High-efficiency quantum yield of Rb 2 InBr 5 ·H 2 O:Sb3+ is used in near-infrared light-emitting diodes. • Theoretical calculation combined with experiments prove that broadband emission originate from band gap adjustment. [ABSTRACT FROM AUTHOR]