Te4+-Doping Rubidium Scandium Halide Perovskite Single Crystals Enabling Optical Thermometry

Zero-dimensional (0D) metal halides have attracted extensive attention due to their excellent optoelectronic properties. Doping is one of the effective strategies to enhance the optical properties of metal halides. Here, we prepared 0D Te4+-doped Rb2ScCl5·H2O single crystals by a facile hydrothermal method. Te4+ doping changes the original Rb2ScCl5·H2O emission band, resulting in a broadband orange emission with a full width at half-maximum of 146 nm. Detailed spectroscopy and fast femtosecond transient absorption measurements indicate that the orange light emission comes from triplet self-trapped excitons. In addition, the fluorescence lifetime of the Rb2ScCl5·H2O:Te4+ single crystal has a strong temperature dependence because Te4+ with the 5s2 electron configuration is more sensitive to temperature. The maximum relative sensitivity (SR) of 3.53% K–1 for this single crystal occurs at 310 K, and the average absolute sensitivity (SA) in the sensitive temperature range 240–320 K is 48.06 ns K–1, indicating potential applications in optical thermometry.