Te4+-doped Cs2InCl5·H2O single crystals for remote optical thermometry

Zero-dimensional metal halide perovskites have captured intense research interest owing to their unique optoelectronic properties. Particularly, metal halides with the n s 2 electronic configuration are of great interest owing to the high-temperature sensitivity of their photoluminescence, which could be applied to remote optical thermometry (ROT). Herein, all-inorganic and lead-free halide perovskite Te 4+ -doped Cs 2 InCl 5 ·H 2 O single crystals (SCs) were prepared through the hydrothermal method and showed a strong temperature dependence of photoluminescence lifetime. Upon Te 4+ doping, the nonemissive Cs 2 InCl 5 ·H 2 O SC exhibits a bright orange emission at 660 nm with a wide full width at half maximum of 180 nm. The strong phonon-exciton coupling promotes the formation of self-trapped excitons in the soft lattice of the zero-dimensional Te 4+ -doped Cs 2 InCl 5 ·H 2 O SC. The Te 4+ ions with the 5s 2 electronic configuration endow the Te 4+ -doped Cs 2 InCl 5 ·H 2 O SC with a strong temperature-dependent photoluminescence lifetime. This SC reaches a maximum specific sensitivity of 0.062K −1 at 320 K, thereby showing the potential advantages of indium-based metal halide perovskites in ROT applications.