Dual emission and energy transfer of Bi 3+ and Mn 4+ in double perovskite CaLaMgTaO 6 phosphors for white light-emitting diodes

Serial Bi3+/Mn4+ codoped double perovskite CaLaMgTaO6 phosphors were synthesized via a solid-state reaction method. When excited under 350 nm, CaLaMgTaO6: Bi3+, Mn4+ provided a blue emission band peaking at 440 nm due to the 3P1–1S0 transition of Bi3+ and a typical deep red emission band peaking at 699 nm owing to the 2Eg → 4A2 transition of Mn4+, which appropriately met the requirement of the growing plants for lighting. The ratio of the blue and deep red spectral component, as well as the emission color could be controlled by tuning the Bi3+/Mn4+ ratio. The energy transfer from Bi3+ to Mn4+ was investigated based on the photoluminescence spectra and fluorescence decay curves. The mechanism of energy transfer was demonstrated to be a dipole–dipole interaction. The quantum efficiency of Bi3+/Mn4+ codoped CaLaMgTaO6 phosphors are higher than that of Bi3+ or Mn4+ single-doped CaLaMgTaO6 phosphors thanks to the energy transfer process.