Huge enhancement in upconversion luminescence near-infrared emission of KYb (MoO4)2: Er3+ phosphor by doping Y3+ ions

The KYb(MoO 4 ) 2 : Er 3+ , Y 3+ phosphors were synthesized by high temperature solid state reaction method. By further doping Y 3+ ions, the near-infrared (NIR, 804 nm, 4 I 9/2  →  4 I 15/2 ) luminescence of KYb(MoO 4 ) 2 : 0.1 % Er 3+ phosphor is greatly enhanced. Based on the upconversion luminescence (UCL) spectra, the optimal doping concentration of Y 3+ ions were 7.5 %. Its near-infrared UCL intensity is about 26.9 times that of undoped Y 3+ ions. Through a series of characterization methods, we find that the enhancement of NIR upconversion emission is due to the generation of defect bands. It plays a crucial role in facilitating the transfer of energy from green light level ( 2 H 11/2 , 4 S 3/2 ) to red light level ( 4 F 9/2 ) and near-infrared level. To explain the luminescence mechanism, the power dependence, UV-VI-NIR absorption spectra , excitation spectra at 804 nm and emission spectra at 380 nm were studied. In addition, the 804 nm single near-infrared UCL intensity of KYb (MoO 4 ) 2 : Er 3+ , Y 3+ shows a linear variation with temperature in the temperature range of 298 K–673 K. The maximum sensitivity is 0.13 % K −1 . This study provides a new method and theoretical support for the application of near-infrared UCL in optical temperature measurement.