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.