Properties of Er3+/Yb3+-Doped Novel Na5lu(Moo4)4 Phosphors and Green Led Device Applications

Abstract

Currently, multi-purpose phosphors have yet to be studied. Na5Lu0.8-x(MoO4)4: xEr3+/0.2Yb3+ phosphors which have scheelite structure were synthesized by a conventional solid-phase method. It was demonstrated that the Na5Lu0.8-x(MoO4)4: xEr3+/0.2Yb3+ composite was in a position to emit the eigenfunctional green and red peaks of the exclusive Er3+ ions under the NIR (near-infrared) excitation at 980 nm by characterization. Moreover, the green light emission was far stronger than the red light emission, so the sample was able to emit intense green light which was visible to the naked eye, and the above process was a two-photon absorption process. The upper conversion efficiency was maximized when the content of Er3+ ions was 10 mol %. Through the fluorescence intensity ratio(FIR)，further exploration of the optical calorimetric features of the phosphors demonstrated that the UC (upconversion) emission intensity of the Na5Lu0.8-x(MoO4)4: xEr3+/0.2Yb3+ phosphors was temperature-dependent. The maximum sensor absolute sensitivity of the studied particles was approximately 0.67% K-1 (@508 K) and the relative sensitivity was 1.11% K-1 (@298 K) at x = 0.10. The excellent thermo-stability of the phosphors was confirmed via six temperature cycling tests. Next, the compound that had been synthesized previously was combined with a near-infrared 980 nm chip and encapsulated to create a green-emitting diode device. At a voltage of 1.76 V and a current of 700 mA, the phosphor generates a bright green light, demonstrating its usability in solid-state lighting. These properties promote the utility of the phosphor not only for non-contact optical temperature measurement but also for solid-state lighting.

Keywords: Upconversion, molybdate, FIR, green-emitting diode devices