Different rare earth ions activated NaBiF4 microcrystals for adjustable multicolor luminescence and white light-emitting diodes

The Er3+, Tm3+, Ho3+ activated, and Tm3+, Ho3+ co-doped NaBiF4: Yb3+ microcrystals are achieved by a hydrothermal method, and the optimum synthesis condition is explored. The phase purity, crystal structure, morphology, upconversion luminescence (UCL) performance and thermal stability of the target products are investigated. By doping different rare earth ions and changing the doping concentration, the UCL color can be adjusted, and the color purity is high under the 980 nm irradiation. Meanwhile, The NaBiF4:20%Yb3+, 0.5%Tm3+, 1.5%Ho3+ microcrystals synthesized under the optimal conditions realize the upconversion white emission. Furthermore, the light-emitting diode (LED) devices are fabricated by integrating a near-infrared LED chip with different microcrystals, displaying bright white and other colors emitted light. These achieved features implied that the NaBiF4 microcrystals doped with rare earth ions are promising functional materials for lighting and display devices.