Morphology evolution of Eu3+-activated NaTbF4 nanorods: A highly-efficient near-ultraviolet light-triggered red-emitting platform towards application in white light-emitting diode
A series of NaTbF4 and Eu3+-activated NaTbF4 nanorods with high luminescent efficiency were designed by using an ingenious reaction technique at room temperature. The effect of synthetic time on the evolution of NaTbF4 nanorods was investigated. Moreover, the influences of Eu3+ doping concentration on the crystal structure, morphology, electronic structure and photoluminescence properties of NaTbF4 nanorods were systematically studied. The near-ultraviolet (NUV) light was the proper excitation lighting source for the final products and the optimum Eu3+ doping concentration was 30 mol%. The critical distance of Eu3+ ions in the NaTbF4 host lattices was 11.42 Å and the concentration quenching mechanism was prevailed by electric dipole-dipole interaction. The local symmetry properties of Eu3+ ions in the NaTbF4 host were explored by analyzing the optical transition parameters based on the Judd-Ofelt theory. The resultant nanorods not only exhibited splendid thermal stability but also had a high internal quantum efficiency of 50.2%. Additionally, the fabricated light-emitting diode (LED) device can emit glaring white light emission with admirable colorific properties (i.e., good color coordinate, high color rendering and low color correlated temperature) which slightly changed at high injection current. These achievements suggested that the Eu3+-activated NaTbF4 nanorods were promising red-emitting candidates for high-powered NUV-pumped white-LED.