Strong near-infrared upconversion luminescence of the Er/Y co-doped YbVO phosphor for multimode optical temperature measurement.

This study explored the enhancement of near-infrared emissions in YbVO: Er through Y ion doping under a 980 nm laser excitation. The phosphor exhibits weak green emissions at 527 nm (H → I) and 553 nm (S → I), red emissions at 654 nm (F → I), and a strong near-infrared emission at 803 nm (I → I). Optimal doping concentration of Y ion in YbVO: 0.02 Er was determined to be 0.1, resulting in a 7.6-fold enhancement of near-infrared luminescence. This enhancement is attributed to defect bands facilitating energy transfer from green and red levels to the near-infrared levels. Furthermore, a multi-mode temperature sensor based on YbVO: Er/Y was developed, offering four distinct temperature sensing modes: TCEL of H/S, NTCEL of H/F and S/F, and single luminescence emission intensity of I energy level. The sensor demonstrates maximum relative sensitivities of 1.17 % K at 298 K, 0.66 % K at 298 K, 0.41 % K at 298 K and 1.29 % K at 673 K. YbVO: Er/Y phosphor exhibits high temperature sensitivity, showcasing significant potential for optical temperature sensing applications.