High-efficiency and thermally stable far-red-emitting NaLaMgWO6:Mn4+ phosphorsfor indoor plant growth light-emitting diodes.

In this Letter, we report a novel NaLaMgWO6:Mn4+ double-perovskite phosphor. Under the excitation at 342 nm, this phosphor showed a high-efficiency far-red emission at approximately 700 nm with internal quantum efficiency of up to 60%. Moreover, it exhibited a high thermal stability; the emission intensity at 423 k was approximately 57% of that at room temperature. Finally, a prototype light-emitting diode (LED) device was fabricated using the combination of a NaLaMgWO6:Mn4+ far-red-emitting phosphor and 365-nm LED chip.