Color tunable ZnO nanorods by Eu^{3+} and Tb^{3+} co-doping for optoelectronic applications

Eu (^{3+}) /Tb (^{3+}) co-doped ZnO nanorods were prepared by co-precipitation method and the effect of Eu–Tb co-doping was studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy, Fourier transform infrared spectroscopy (FTIR), UV-Vis-NIR diffuse reflectance (DR) and photoluminescence (PL) spectroscopy. The XRD pattern shows typical peak pattern for pure hexagonal wurtzite structure to match with the JCPDS data. The samples are found to be consisting of nanorods of diameter 20–30 nm as revealed by the TEM image. The FTIR pattern confirms the formation of the compounds. The DR study was carried to show the variation of absorption edge and the variation in band gap values, which showed the crystal size effect in the co-doped sample of different rare-earth ratios. The room temperature PL study shows bright emission spectra for the samples with different rare-earth ratios. It shows a very good energy transfer from Tb (^{3+}) to Eu (^{3+}) ions. The energy transfer mechanism and color tunability were discussed thoroughly.