Spectral regulation in Cs2PtCl6 double perovskite via low-temperature and high-pressure engineering for advanced optical thermometry and manometry

To build bifunctional luminescent platform for optical thermometry and manometry, Cs2PtCl6 double perovskite was synthesized. Upon 468 nm excitation, the designed compound emitted bright red light centered at ≈675 nm, originating from self-trapped exciton (STE) emission, whose fluorescence intensity and band width are highly temperature-dependent. Moreover, the temperature-dependent decay curves of the developed Cs2PtCl6 double perovskite were measured to explore its application in optical thermometry, of which its maximum relative sensor sensitivity is 1.34% K-1, with the operation range of 100-310 K. Furthermore, the impact of pressure on the phase structure and luminescence behaviors of the Cs2PtCl6 double perovskite was also discussed. The pressure-dependent Raman spectra clarified that the synthesized compound possesses stable phase structure at high-pressure. Furthermore, Cs2PtCl6 double perovskite exhibits distinct spectral blue-shift at high-pressure. Importantly, as pressure increases (i.e., 0-5.67 GPa), the STE emission band centroid and full width at half maximum (FWHM) are both linearly dependent on pressure, resulting in high pressure sensitivities of dλ/dp = 7.19 nm/GPa and dFWHM/dp = 4.95 nm/GPa. Our finding manifests that the luminescence characteristics of the Cs2PtCl6 double perovskite can be efficiently regulated via low-temperature and high-pressure, enabling its applications in optical thermometry and manometry.