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 ns2 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 Te4+-doped Cs2InCl5·H2O single crystals (SCs) were prepared through the hydrothermal method and showed a strong temperature dependence of photoluminescence lifetime. Upon Te4+ doping, the nonemissive Cs2InCl5·H2O 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 Te4+-doped Cs2InCl5·H2O SC. The Te4+ ions with the 5s2 electronic configuration endow the Te4+-doped Cs2InCl5·H2O 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.