Single-band red up-conversion emission of Er3+doped Yb0.2Zr0.8O1.9 phosphors and multi-mode optical temperature sensing

This work used a solid-state technique to produce a variety of Er3+-doped Yb0.2Zr0.8O1.9 (Yb0.2Zr0.8O1.9: Er3+) phosphors. The temperature sensing characteristics and up-conversion luminescence (UCL) properties of Er3+ in Yb0.2Zr0.8O1.9: Er3+ phosphors under 980 and 1550 nm excitations were investigated. A virtually pure red UC emission was obtained with a spectral color purity of 95.65 % and 99.92 % when excited at 980 and 1550 nm, respectively. Based upon the fluorescence intensity ratios of temperature-dependent distinct emissions, the temperature sensing capabilities of the materials were investigated. The relative sensitivity (SR) generated from the red emission reaches 0.74 % K- 1 at 298 K, whereas the one derived from the green emission attains its highest value of 1.51 % K-1 at 688 K utilizing the thermally coupled energy levels (TCELs). At 495 K, the SR for non-thermally coupled energy levels (NTCELs) reaches its highest value of 0.46 % K-1. This study reveals that Yb0.2Zr0.8O1.9: Er3+ is an excellent red UC phosphor and has potential applications in three-dimensional display and temperature sensing.