An insight into the structure, luminescent characteristics and Judd-Ofelt analysis of (1-x) ZnS-(x) Dy2O3 phosphors

Abstract

We report a white light emitting of (1- x) ZnS - (x) Dy2O3 with x = 0, 0.1, 0.2 and 0.3 phosphor synthesized via conventional solid state reaction method. The crystal structure, modes of vibrations, morphology, NIR-UV absorption and luminescence characteristics were discussed. The X-ray diffraction study confirmed the single phase of hexagonal ZnS and cubic Dy2O3 structure. The intensity parameters Ω2, Ω4 and Ω6 were estimated for x = 0.1, from the optical absorption spectra using Judd-Ofelt theory, since the optimal doping concentration is about 10mol%. The optical band gap energy of the samples varied from 3.41 to 3.49 eV. The photoluminescence spectra has an intense strong emission at 582 nm corresponding to 4F9/2 → 6H13/2 transition due to a forced electric dipole (ED) allowed transition with selection rule ΔL = 2 and ΔJ = 2. The transition radiative parameter (AR) and the stimulated emission cross section, σe values suggested that (1- x) ZnS - (x) Dy2O3 with x = 0.1 phosphor material is suitable for white LED applications. The nephelauxetic ratio and the bonding parameter of concentration x = 0.1 were calculated. The negative value of bonding parameter indicated that Dy3+ ion and ZnS material is bonded ionically. The CIE chromaticity coordinates, Yellow to Blue intensity ratio, Color Purity and Correlated Color Temperature were also estimated. The CIE coordinates of the samples lie in the white light region and this type of white light luminescence phosphors could be promising phosphors for w-LEDs and optoelectronic devices applications.