Blue luminescence of Bi3+ in the double perovskite CaLaMgTaO6 matrix for n-UV pumped white light-emitting diodes

Abstract

A novel Bi3+ activated double perovskite CaLaMgTaO6 phosphor was synthesized and its photoluminescence properties were investigated. CaLaMgTaO6: Bi3+ could be efficiently excited in the wavelength range of 270–400 nm, and exhibit a blue emission band ascribing to the 3P1–1S0 transition of Bi3+. The maximum intensity of the excitation moves from 332 to 351 nm, and the emission band moves from 443 to 434 nm as the concentration of Bi3+ increases from 0.5 to 20 mol %, corresponding to the overlapped luminescence of Bi3+ substituting for La3+ and Ca2+ with substitution preference. Due to the energy transfer between Bi3+ ions, the concentration quenching of Bi3+ in the CaLaMgTaO6 host occurred when the concentration of Bi3+ exceeded 7.5 mol %. The energy transfer mechanism of CaLaMgTaO6: Bi3+ was estimated to be dipole-dipole interaction. Furthermore, the thermal stability of the phosphor was investigated and the corresponding activation energy ΔE was determined to be 0.26 eV. Due to the efficient excitation in near ultraviolet (n-UV) region and the strong blue emission, CaLaMgTaO6: Bi3+ would be a potential blue phosphor for n-UV pumped light-emitting diodes.