Bi3+/Sb3+-doped Cs2Na (Yb/Er) Cl6 double perovskite nanocrystals: Fabrication, optical properties and temperature sensing

Rare-earth-based double perovskites exhibit excellent thermal, water, and oxygen stability, making them promising environmentally friendly materials for various applications such as anti-counterfeiting, LED technology, infrared imaging, and photodetectors. In this study, we utilized the hot injection method to prepare Cs2NaYbCl6:Er3+/Bi3+/Sb3+ double perovskite nanocrystals, realizing upconversion visible and downshifting NIR emission under 980 nm and 1550 nm excitation, and their luminescence and dynamics as a function of temperature were further investigated. The luminescence intensity of Er3+ in Cs2NaYb0.85Er0.15Cl6 can be improved by Sb3+ or Bi3+ doping, and they exhibited the temperature dependent visible and NIR emission with an optimum temperature around 100–130 K. Furthermore, the intensity ratios of RH/S and Rr/g increase consistently with temperature in the range of 80–310 K. The temperature sensing sensitivity of Cs2NaYb0.845Er0.15Sb0.005Cl6 at 310 K increases from 2.39 % K−1 to the relative sensitivity (SR) of 2.90 % K−1 for Cs2NaYb0.85Er0.15Cl6. Our work providing a detailed understanding on the luminescent performance of perovskites through transition metal doping, expanding their temperature sensing application.