Tunable single-phase white light emission from double perovskite Ca2LuTaO6:Dy3+/Sm3+ phosphors

The advancement of double perovskite oxide phosphors has expanded their applications, encompassing white light-emitting diodes (LEDs) to optical thermometry and scintillation detection. We have synthesized novel Ca 2 LuTaO 6 phosphors characterized by double perovskite structures by employing the high-temperature solid-state reaction technique. Upon excitation with 312 nm UV light, these undoped phosphors emit a broad blue light centered at 424 nm. We thoroughly investigated the origin of this blue emission using computational and experimental methods. The Ca 2 LuTaO 6 phosphors were further doped with Dy 3+ or Dy 3+ and Sm 3+ ions, which results in a broadband tunable-color emission covering the entire visible region (400–700 nm). Under 354 nm excitation, the single doped Ca 2 LuTaO 6 :Dy 3+ exhibits two emission bands due to the 4 F 9/2  →  6 H 15/2 (blue) and 4 F 9/2  →  6 H 13/2 (yellow) transitions of Dy 3+ . The single doped Ca 2 LuTaO 6 :Sm 3+ generates a red emission (603 nm) when excited at 407 nm from 4 G 5/2 to 6 H 7/2 transition. The optimized Ca 2 LuTaO 6 :0.05Dy 3+ and Ca 2 LuTaO 6 : 0.05Dy 3+ /0.04Sm 3+ phosphors show excellent thermal stability. Even at a temperature of 150 °C, i.e. typical temperature of the working LED electronics, the luminescence intensity for the single-doped sample with Dy 3+ maintains 82 % of its initial value. On the other hand, at the same temperature conditions, for the phosphors co-doped with Dy 3+ and Sm 3+ , the intensity remains at 90 % of Dy 3+ peaks with a slight chromaticity shift. A study of the electroluminescent performance of the Ca 2 LuTaO 6 :0.05Sm 3+ and Ca 2 LuTaO 6 :0.05Dy 3+ /0.04Sm 3+ phosphors were conducted using 365 nm LED chips to investigate their applications in white light-emitting diodes (WLEDs). The results confirm that Ca 2 LuTaO 6 :Dy 3+ /Sm 3+ phosphors have great potential for general illumination purposes, as the single-phase light sources.