High-resolution remote thermometry based on Bi³⁺-doped 0D zinc halide hybrids

Developing highly sensitive optical thermometers is of great significance due to their capability to enable remote and non-contact temperature measurements, rendering them highly applicable in diverse and harsh environments. Herein we report a temperature-dependent phosphor of 0D metal halide hybrid by incorporating Bi³⁺ into the (MePPh₃)₂ZnCl₄ matrix. Through Bi³⁺ doping, the initially non-luminescent (MePPh₃)₂ZnCl₄ matrix exhibits a deep-blue emission centered at 453 nm, with a photoluminescence quantum yield (PLQY) of 5.71% and a Stokes shift of 75 nm at room temperature. Experimental characterization demonstrates that exciton-like luminescence of Bi³⁺ is mainly responsible for the blue emission. Single crystals of Bi³⁺-doped (MePPh₃)₂ZnCl₄ show an unusual correlation between photoluminescence (PL) lifetime and temperature. Particularly, the dependence of luminescence lifetime on temperature is most remarkable in the temperature range of 80 to 100 K with an exceptional sensitivity up to 0.09 K⁻¹, representing one of the best levels for thermometry based on PL decay lifetime. Our work not only provides a viable strategy for designing a novel, environmentally friendly, and stable blue emitter, but also paves the way for precise thermometric application at low temperature.