High-efficiency and thermally stable far-red emission of Mn4+ in double cubic perovskite Sr9Y2W4O24 for plant cultivation

Abstract

A new Mn4+ activated Sr9Y2W4O24 far-red phosphor was synthesized by high temperature solid state reaction. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence spectra, temperature-dependent emission spectra (298–548 K) and electroluminescence spectra. Finally, a 365 nm ultraviolet (UV) light-emitting diode (LED) chip combined with Sr9Y2W4O24:0.005 Mn4+ far-red phosphor was used to fabricate the LED device. It is found that Sr9Y2W4O24:Mn4+ phosphor has a strong broad excitation band in the range of 300–550 nm. There is a wide emission band centered at 680 nm between 650 nm and 800 nm. The optimum doping concentration of Mn4+ is about 0.5 mol%. Importantly, Sr9Y2W4O24:0.005 Mn4+ has an IQE of up to 49.8%. The thermal activation energy Ea = 0.448 eV. In short, the emission spectra of Sr9Y2W4O24:0.005 Mn4+ phosphors are well matched with the absorption bands of PFR in plants excited by near ultraviolet light, so Sr9Y2W4O24:Mn4+ phosphors have potential applications in indoor plant cultivation.