Tailoring the Luminescence Properties of Cs_<b>2</b>TeCl_<b>6</b> Nanocrystals <i>via</i> High-Pressure and Low-Temperature Stimuli for Multiparameter Optical Manometry and Thermometry

To search for a bifunctional luminescent platform for optical manometry and thermometry, Cs₂TeCl₆ nanocrystals were prepared. Excited at 456 nm, the designed nanocrystals emitted dazzling orange emission, whose fluorescence intensity, full width at half-maximum (fwhm), and decay time were sensitive to temperature. Through analyzing the temperature-dependent lifetime, the thermometric properties of the resulting nanocrystals were evaluated, resulting in a high relative sensitivity of 3.76% K^-1. The pressure-related Raman spectra demonstrated the splendid structural stability and reversibility of the studied samples. By studying the pressure-dependent Raman modes, one knows that the maximum pressure sensitivity of the Cs₂TeCl₆ nanocrystals was 9.62 cm^-1 GPa^-1. Furthermore, as the pressure increases, a distinct spectral blue-shift was observed in the synthesized nanocrystals, contributing to the controllable luminescence at high-pressure. Through analyzing the pressure-dependent emission band centroid and fwhm, one knows that the maximum pressure sensitivities of the resultant nanocrystals were 3.54 and 4.82 nm GPa^-1, respectively. Additionally, based on the pressure-dependent color coordinate, it was found that the maximum relative sensitivity of the designed nanocrystals was 4.62% GPa^-1. Our findings imply that the utilization of high-pressure and low-temperature stimuli is an efficient route to regulate the luminescence properties of the Cs₂TeCl₆ nanocrystals.