Excitation-dependent luminescent and optical thermometric properties of Er3+ and Yb3+ Co-doped K5Y(P2O7)2

Abstract

We investigated the luminescent and optical thermometric properties of Er3+ and Yb3+ co-doped K5Y(P2O7)2 (KYP) with dependence on the excitation wavelength. To examine the role of Yb3+ ions in excitation-dependent luminescence, we synthesized three series of samples: an Er3+ singly doped KYP sample, and two Er3+ and Yb3+ co-doped KYP samples with varying concentrations of Er3+ or Yb3+. Although our samples exhibited visible and near-infrared (∼1550 nm) emissions under ultraviolet excitation, the doping with Yb3+ disturbed the luminescence of Er3+. In the case of 980 nm excitation, we identified upconversion luminescence (UCL) and 1550 nm luminescence; they were enhanced significantly via doping with Yb3+, which served as a sensitizer via energy transfer to Er3+. Our samples demonstrated excellent optical thermometric properties under 980 nm excitation compared with under ultraviolet excitation. In particular, the relative sensitivity of the UCL spectra was 1.01 %/K at 293 K. These results suggest the promising potential of using our Er3+ and Yb3+ co-doped KYP as an optical thermometer under 980 nm excitation.