High-efficiency dual-mode luminescence of metal halide perovskite Cs3Bi2Cl9:Er3+ and its use in optical temperature measurement with high sensitivity

Metal halide perovskites have attracted much attention due to their excellent optical properties and structural tunability. In this work, we synthesized the metal halide perovskite Cs3Bi2Cl9:Er3+ as the activator by solid-phase method using deionized water as the solvent. The phosphor doped with self-sensitizating of Er3+ ions emitted bright green light under the excitation of triple near-infrared laser (808 nm, 980 nm and 1550 nm). Interestingly, the upconversion emission exhibited a strong temperature dependence due to the thermally coupled energy levels 2H11/2 and 4S3/2 of Er3+, therefore is useful for optical temperature measurement. The maximum relative sensitivity in the range of 303–573 K is 1.40%K−1 (303 K, 808 nm), 1.38%K−1 (303 K, 980 nm), 1.50%K−1 (303 K, 1550 nm), respectively. By using fluorescence intensity ratiometry (FIR) methods, Cs3Bi2Cl9:Er3+ phosphor showed excellent accuracy and sensitivity and was compared very favorably with the reported temperature measurement materials. We anticipate that this new phosphor may have a range of applications in multi-mode luminescence and multi-excited light source temperature measurement.