Novel multi-wavelength excitable single-component phosphor system for application in white-LEDs

Abstract

A novel color-tunable phosphor of BaZnO2:xEu3+ (x = 0–20 mol%) has been successfully prepared via high-temperature calcination method using alkaline earth metal as the charge compensator. Uncommonly, BaZnO2:Eu3+ is a multi-wavelength excitable phosphor due to its wide absorption spectrum ranging 250–550 nm. It shows broad white (400–700 nm), orange (∼580 nm) and red (∼611 nm) photoluminescence (PL) under 370 nm, 395 nm and 467 nm excitations, respectively and were assigned to one or more 5D0→7FJ (J = 1 to 4) transitions of Eu3+ ion. An efficient energy transfer between Zn2+ and Eu3+ has been observed upon systematically increasing the concentration of Eu3+ ion. Scanning Electron Microscopy images indicated elongated rod-like structures with an average diameter of ∼20 nm. The chromaticity coordinates (x, y) were found to be positioned at white (0.33, 0.42), orange (0.51, 0.42) and red (0.65, 0.34) regions correspond to 370 nm, 395 nm and 467 nm excitations, respectively. The temperature-dependent luminescence spectrum of BaZnO2:Eu3+ under the excitation of 467 nm was also studied. It exhibited good thermal stability and a marginal drop in photoluminescence intensity by 4.29% at 150 °C was observed. The mathematical calculation of the activation energy was approximately 0.20 eV. The results indicate the suitability of the phosphor for LEDs applications, which is otherwise difficult to obtain in single-component system.