Studies on luminescence properties of double perovskite deep red phosphor La2ZnTiO6:Mn4+ for indoor plant growth LED applications

A non-rare-earth doped double perovskite La2ZnTiO6:Mn4+ phosphor with the single-phase was prepared by solid-state reaction. The composition and the distribution of La2ZnTiO6:0.5%Mn4+ phosphor was confirmed by the scanning electron microscope and energy-dispersive spectroscopy. The optical band gap of La2ZnTiO6 was analyzed by density functional theory using the CASTEP code, which matched well with the result of diffuse the reflectance spectra (DRS). The excitation spectra of La2ZnTiO6:Mn4+ show two broad bands with peaks at about 342 nm and 504 nm. Emissions characteristic of Mn4+ ions from 650 nm to 750 nm were observed, with the E-4(g) -> (4)A(2g) transition near 708 nm. The result of the temperature-dependent photoluminescence shows good thermal stability and the luminous mechanism is explained by schematic energy level diagram of Mn4+ ion. Above all, a significant overlap was found between the far-red emission band of La2ZnTiO6:0.5%Mn4+ and the absorption spectrum of the phytochrome PFR, indicating that La2ZnTiO6:Mn4+ phosphor has great potentiality to be used as indoor plant artificial light. (C) 2019 Published by Elsevier B.V.