The novel Sr3LiSbO6:Mn4+, Ca2+ far-red-emitting phosphors with over 95% internal quantum efficiency for indoor plant growth LEDs

Abstract Sr3LiSbO6:x%Mn4+, y%Ca2+ (x = 0.1, 0.2, 0.3, 0.4, 0.5, x: y = 1: 1.5) phosphors have been successfully synthesized via conventional high-temperature solid-state reaction method. The phosphor samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence spectra, ultraviolet–visible (UV–vis) absorption spectra, Raman spectra and decay curves as well as internal quantum efficiency (IQE). The quantum efficiency of Sr3LiSbO6:Mn4+ phosphor can be as high as 96% by co-doping small amount of Ca2+ ions. The excitation and emission intensities of Sr3LiSbO6:Mn4+, Ca2+ phosphors can be enhanced 1.3–1.6 times. Furthermore, the Sr3LiSbO6:0.3%Mn4+, 0.45%Ca2+ phosphor exhibited good thermal stability and the emission intensity at 423 K maintained 87% compared with its initial value at 298 K. Under the excitation of 365 nm, the phosphor exhibits an intense far-red emission band centered at 693 nm which can match well with the absorption band of phytochrome PFR. Finally, a LED device was fabricated with the Sr3LiSbO6:0.3%Mn4+, 0.45%Ca2+ phosphor, which showed an effective promotion of growth in red beans and pakchoi cabbages. All the results show that the synthesized phosphors may have promising applications for use in plant growth LEDs.