Spectroscopic properties of Dy3+ doped ZnO for white luminescence applications

Undoped and Dy3+ (0.25, 0.5, 0.8 and 1.5 at.%) doped ZnO were elaborated by solid-state reaction method. The ZnO:Dy3+ samples were characterized using X-ray diffraction (XRD), Raman spectroscopy, UV vis diffuse reflectance spectroscopy and photoluminescence (PL). The XRD analysis confirms the wurtzite structure of ZnO. A slight shift to lower angles, of the (101) peak, is seen with Dy3+ content, indicating the substitution of these ions into the ZnO lattice. Raman study indicates the good crystallinity of all ZnO:Dy3+ samples and confirms the substitution of Zn2+ by Dy3+. The band gap energy was found to increase then decrease with Dy content. The PL excitation spectra (PLE) of Dy3+ showed six excitation bands with hypersensitive at 346 nm (H-6(15/2) -> P-6(7/2)). PL spectra show principally three emission bands relatives to F-4(9/2) -> H-6(15/2) (476 nm), F-4(9/2) -> H-6(13/2) (567 nm) and F-4(9/2) -> H-6(11/2) (658 nm) transitions. The concentration dependency of PL intensity indicates a quenching for Dy3+ concentration above 0.5 at.%. The PL lifetime of F-4(9/2) metastable state was measured and discussed for all Dy content in ZnO. The temperature dependency of PL intensity is investigated for ZnO:Dy (0.5%) sample and the activation energy is determined. The CIE chromaticity color coordinate shows that ZnO:Dy3+ can be useful for white luminescence applications. (C) 2017 Elsevier B.V. All rights reserved.