Enhanced temperature sensing in lead-free Cs3Bi2Cl9 perovskite co-doping Yb3+/Er3+ for optical thermometry application

Abstract

A simple and rapid grinding method for preparing Er3+-doped and Er3+/Yb3+co-doped Cs3Bi2Cl9 upconversion phosphors was developed. We avoid to employ strong acids as reaction solvents, aligning with the principles of green chemistry. By controlling the thermal treatment temperature and adding BiCl3, a reversible phase transformation process between Cs3Bi2Cl9 and Cs3BiCl6 perovskite phosphors was achieved. The Er3+/Yb3+ co-doped Cs3Bi2Cl9 phosphors emit green light under 980 nm excitation, whereas Cs3BiCl6 phosphors emit red light. Their temperature sensing performance was tested through variable-temperature processes. Compared to Er3+-doped Cs3Bi2Cl9 phosphors, the co-doped Er3+/Yb3+ phosphors have a higher relative sensitivity of 1.60 % K−1. Compared to previously reported materials, Cs3Bi2Cl9 phosphors show enhanced sensitivity in temperature sensing. The study demonstrates that lead-free halide perovskites’ unique color-tunability not only underscores the innovativeness of this synthetic strategy but also provides a significant technological foundation for temperature sensing applications. Given their environmental friendliness and facile preparation process, these phosphors possess notable advantages for industrial production and hold promise as potential candidates for next-generation high-performance phosphor materials.