Fabrication and photoluminescence characteristics of novel red-emitting Ba₂LuNbO₆:Eu³⁺ double-perovskite phosphors on near UV WLEDs

Red emitting phosphors play a significant role in accelerating the improvement of illumination quality for white light emitting diodes (WLEDs). In this work, by using solid-state reaction method, an efficient novel Ba₂LuNbO₆:Eu³⁺ phosphor with double-perovskite structure was successfully prepared. Here, a series of Ba₂LuNbO₆:Eu³⁺ red phosphors can be efficiently pumped by the near-ultraviolet (UV) light and then present high-brightness at orange emission (598 nm, ⁵D₀→⁷F₁) and red emission (610 nm, ⁵D₀→⁷F₂). The ratio values of 610 to 598 nm in Ba₂LuNbO₆:Eu³⁺ phosphors exceed 1 when the content of Eu³⁺ is larger than 0.4 mol, because the occupation of Eu³⁺ ions is changed from Lu³⁺ ions with symmetric sites to Ba²⁺ ions with asymmetric sites. Besides, the optimized concentration of Eu³⁺ at the ⁵D₀→⁷F₂ transitions is obtained when x = 1, indicating that there is non-concentration quenching in Ba₂LuNbO₆:Eu³⁺ phosphors. Moreover, the CIE chromaticity coordinates of Ba₂LuNbO₆:Eu³⁺ was calculated to be (0.587, 0.361), the color purity was calculated to be 72.26% and internal quenching efficiency (IQE) was measured to be 67%. Finally, the thermal stability of Ba₂LuNbO₆:Eu³⁺ phosphors was also studied. Our work demonstrates that the novel double-perovskite red-emitting Ba₂LuNbO₆:Eu³⁺ phosphors are prospective red emitting elements for WLEDs applications.