Synthesis and photoluminescence properties of novel Ca2LaSbO6:Mn4+ double perovskite phosphor for plant growth LEDs

A novel Mn4+ activated Ca2LaSbO6 (CLS) 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, ultraviolet-visible spectra, luminescence decay times, emission-temperature relationship and internal quantum efficiency (IQE). It is found that CLS:Mn4+ phosphor has a strong broad excitation band in the range of 200–550 nm. The samples can be excited by ultraviolet and blue light. There is a wide emission band centered at 685 nm between 600 nm and 760 nm. The optimum doping concentration of Mn4+ is approximately 0.5 mol%. In addition, all the CIE chromaticity coordinates of CLS:0.005Mn4+ located at far-red region. The concentration quenching mechanism is the dipole-dipole interaction of Mn4+ activator. Importantly, the CLS:0.005 Mn4+ sample has an IQE of up to 52.2%. Finally, a 365 nm ultraviolet light emitting diode (LED) chip combined with 0.5 mol% Mn4+ far-red phosphor was used to fabricate the LED device. All the results indicated that CLS:Mn4+ phosphors have potential applications in indoor plant cultivation.