X-ray photoelectron spectroscopy and optical analysis of pure white light emitting Dy3+ and Mn2+ codoped Na3Y(PO4)2 phosphors for solid-state lighting

Abstract

A single-phase and optimized pure white light emitting Dy3+-doped and Dy3+/Mn2+ codoped Na3Y(PO4)2 phosphors (NYPO) were synthesized by traditional solid state reaction process. The as-synthesized phosphors were characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectra and photoluminescence studies. The results suggested that the NYPO: Dy, Mn phosphors were crystallized in orthorhombic structures. The presence of dopants Dy and Mn was quantified by XPS analysis. All of the phosphors were effectively excited using a light of wavelength 351 nm and emissions in two regions, blue (~482 nm, 4F9/2→6H15/2) and yellow (~573 nm, 4F9/2→6H13/2), were obtained due to the f-f transitions of Dy3+ ions. The maximum intensities of Dy and Mn obtained were 0.07 and 0.05 for NYPO:Dy and NYPO:0.07Dy, Mn, respectively. The chromaticity coordinates, color temperatures, and color rendering indices of NYPO: 0.07Dy ((0.32, 0.33), 6194 K, and 48) and NYPO:0.07Dy, 0.05Mn phosphors ((0.33, 0.33), 5688 K, and 62) were determined. The energy transfer mechanism and oxygen vacancies that arise due to the introduction of Mn2+ ions in the NYPO:Dy phosphors, are responsible for the tuning of cool white light to pure day white light. The introduction of Mn in the Dy doped NYPO phosphor enhances the emission intensity in the phosphor.