Influence of dopant concentration on powder morphology and photoluminescence characteristics of red-emitting Eu3+-doped ZnO

Abstract

A well-defined morphology is highly required to obtain richness in red colour with improved photoluminescence characteristics of phosphor materials. In this work, different concentrations of Eu3+-doped ZnO red-emitting materials with well-established morphologies were prepared through precipitation using sodium borohydride. The morphology of pure phase of Eu3+-doped ZnO samples varied from agglomerated spherical particles to elliptical/elongated rod-like structures with the incorporation of Eu3+ ions. The Raman spectra exhibited the defects such as oxygen vacancy with zinc interstitial in all the samples. The emission spectra revealed the dominance of 5D0→7F2 electric dipole transition at 613 nm. The elongated rods with flower-like morphology of 1 mol% Eu3+-doped ZnO sample exhibited the highest emission intensity. It was mainly due to the less defects introduced in the larger particle size i.e. elongated rods with flower-like morphology. This led to decrease the nonradiative rate and eventually increases the emission intensity. The R/O ratio revealed the higher asymmetry in nature around the Eu3+ ions in the ZnO for all the samples. The CIE coordinates of Eu3+-doped ZnO samples were lie in the reddish-orange and red region. The elongated rods with flower-like nanostructures show a higher colour purity among the other nanostructures. Further, the Judd-Ofelt intensity parameters were determined with the help of emission spectra. The obtained results suggested that the Eu3+-doped ZnO samples may be used as a red-emitting light source in the solid-state lighting application.