Novel far-red emitting phosphor Mn4+-activated BaLaLiWO6 with excellent performance for indoor plant cultivation of light-emitting diodes

Abstract

The far-red oxide phosphors doped with Mn4+ ions are constantly investigated for plant cultivation of light-emitting diodes (LEDs) due to their emission bands matching well the absorption region of phytochromes in plants. Herein, a novel far-red emitting phosphor of BaLaLiWO6 (BLLW) doped with Mn4+ ions was successfully prepared for plant cultivation. The Rietveld-refined lattice parameters and surface micromorphology of the samples were investigated. The theoretical values of the energy gap for the perfect BLLW matrix were calculated by density functional theory and the experimental values obtained based on the absorption spectra were compared. In addition, the samples can be efficiently excited by ultraviolet and blue light, and emit intense far-red light with a central wavelength of 708 nm. Furthermore, the crystalline field effect and concentration quenching mechanism of Mn4+ ions in the BLLW matrix were explored. Satisfactorily, the internal quantum efficiency, color purity, and activation energy of the phosphor were as high as 48.38%, 99.6%, and 0.53 eV, respectively. Meanwhile, the effects of synthesis temperature and Ca2+ ions co-doping on the luminescence intensity of the samples were studied. Finally, the far-red LEDs devices were prepared for plant cultivation by combining the phosphor with 460 nm LEDs chips.