Design of opposite thermal behaviors in Tm³⁺/Eu³⁺ co-doped YVO₄ for high-sensitivity optical thermometry

Temperature-induced redshift of the V-O charge transfer band edge and the temperature quenching effect were combined for designing ratiometric optical thermometry. Following this approach, opposite thermal behaviors of Tm³⁺ and Eu³⁺ emissions were realized in the range of 300 to 380 K in Tm³⁺/Eu³⁺ co-doped YVO₄. Applying the temperature dependent fluorescence intensity ratio of Eu³⁺ to Tm³⁺ as temperature readout, the maximal relative sensitivity reaches up to 4.6%K^-1 around 330 K. This result makes our proposed strategy an excellent candidate for developing high-sensitivity optical thermometry.