UV luminescence enhancement of Cu-doped ZnO nanorods grown by hydrothermal treatment

Herein, we studied the effect of Cu doping on the ultraviolet (UV) emission enhancement of ZnO nanorods. ZnO nanorods with different Cu doping concentrations were prepared by hydrothermal method and the Cu doping behavior was investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), ultraviolet visible (UV–Vis) absorption spectroscopy and photoluminescence (PL). XRD patterns confirmed the incorporation of Cu. Compared with pure ZnO, no other phase appears, the intensity of diffraction peaks and the calculated parameters such as lattice constants increase, all of which proved that the doping of Cu is substitutional doping. Doping induces a red-shift in the absorption maximum wavelength of the absorption spectrum, indicating that doping causes attenuation of UV absorption properties. In the PL spectra, the increase of Cu doping concentration makes the UV emission peak enhanced and there is almost no emission peak in the visible region. The UV emission at room temperature can be attributed to the superposition of free and bound excitons, where free excitons dominate and bound excitons are related to the substitution of Cu for Zn. The enhanced UV emission of Cu-doped ZnO materials could lead to the wide application in the field of UV optoelectronic devices. •Cu doping has a certain effect on light absorption properties of ZnO nanorods.•The crystal structure of ZnO nanorods is not significantly affected by Cu doping.•A certain concentration of Cu can enhance the UV emission of ZnO nanorods.•The UV emission at room temperature can be attributed to the superposition of free and bound excitons.