Mn4+-activated BaLaMgSbO6 double-perovskite phosphor: a novel high-efficiency far-red-emitting luminescent material for indoor plant growth lighting

In the present work, novel high-efficiency Mn4+-activated BaLaMgSbO6 (BLMS) far-red-emitting phosphors used for plant growth LEDs were successfully synthesized via a solid-state reaction method. X-ray diffraction (XRD), photoluminescence (PL), temperature-dependent PL, CIE color coordinates, and lifetimes as well as internal quantum efficiency (IQE) were used to characterize the phosphor samples. The excitation spectrum of the as-obtained BLMS: Mn4+ phosphors presented two wide bands covering 250-550 nm and the emission spectrum exhibited a far-red emission band in the range of 650-800 nm peaked at 700 nm. Concentration-dependent PL properties of BLMS: Mn4+ phosphors were studied. The optimal doping concentration of Mn4+ ions was 0.6 mol%, and the concentration quenching mechanism was determined to be the nonradiative energy transfer among the nearest-neighbor Mn4+ activators. Impressively, the BLMS: 0.6% Mn4+ sample showed an outstanding IQE of 83%. In addition, luminescence thermal quenching characteristics were also analyzed. Furthermore, the PL spectrum of BLMS: 0.6% Mn4+ sample was compared with the absorption spectrum of phytochrome PFR. Finally, after combining BLMS: 0.6% Mn4+ phosphors with a 365 nm near-UV LED chip, a far-red light-emitting diode (LED) device was successfully achieved to demonstrate its possible applications in plant growth LEDs.