Thermally stable La(2)LiSbO(6):Mn(4+),Mg(2+) far-red emitting phosphors with over 90% internal quantum efficiency for plant growth LEDs

In this paper, we reported on the high-efficiency and thermally-stable La(2)LiSbO(6):Mn(4+),Mg(2+) (LLS:Mn(4+),Mg(2+)) far-red emitting phosphors. Under 338 nm excitation, the composition-optimized LLS:0.3%Mn(4+),1.6%Mg(2+) phosphors which were made up of [SbO(6)], [LiO(6)], and [LaO(8)] polyhedrons, showed intense far-red emissions peaking at 712 nm ((2)E(g) → (4)A(2g) transition) with internal quantum efficiency as high as 92%. The LLS:0.3%Mn(4+),1.6%Mg(2+) phosphors also exhibited high thermal stability, and the emission intensity at 423 K only reduced by 42% compared with its initial value at 303 K. The far-red light-emitting device has also been made by using the LLS:0.3%Mn(4+),1.6%Mg(2+) phosphors and a 365 nm emitting InGaN chip, which can emit far-red light that is visible to the naked eye. Importantly, the emission spectrum of the LLS:0.3%Mn(4+),1.6%Mg(2+) phosphors can match well with the absorption spectrum of phytochrome P(FR), indicating the potential of these phosphors to be used in plant growth light-emitting diodes.