Structural characterization and luminescence characteristics of Dy3+ doped Sr9Y2W4O24 phosphor for application in white-LEDs

Abstract

In this research, a series of Dy3+ ions doped Sr9Y2W4O24 (SYWO) phosphors was prepared for the application in white-LEDs and display devices. The structure, surface, and photo-luminescent (PL) behaviour of the samples were studied. X-ray diffraction (XRD) and Fourier Transform Infra-Red (FT-IR) spectroscopy indicated the formation of single phase particles with no contaminants with various vibrational bands present in the host lattice. The synthesised powders showed agglomeration with the average crystallite size to be in the range of 22–27 nm. The optical band gaps were estimated using diffuse reflectance spectral (DRS) data. The emission spectra of SYWO: xDy3+ (1.0, 2.0, 3.0, 4.0, & 5.0 mol%) have been obtained at different excitation wavelengths of 354, 367, and 391 nm. The SYWO phosphors emit intense blue and yellow colors at 491 nm (4F9/2 → 6H15/2), 576 nm (4F9/2 → 6H13/2) & 679 nm (4F9/2 → 6H11/2), respectively. Furthermore, from the CIE 1931 diagram, it is evident that the emission from these Dy3+ doped phosphors lies in the white region. The lifetime of excited Dy3+ ions decreased with increasing Dy3+ concentration as seen in the luminescence decay graphs. Finally, to determine the phosphor's luminescence thermal stability, temperature dependent photoluminescence (TD-PL) was recorded and the activation energy calculated from this study was found to be 0.231 eV. In the light of aforementioned results, we can conclude that Dy3+ doped Sr9Y2W4O24 phosphors could be used in construction of w-LEDs or as white-emitting luminescent materials in various photonic devices and other photonic applications.