Solution growth of highly crystalline and dense-packed ZnO nanorods on a TiO2 seed layer with enhanced absorbance properties

Titanium dioxide:zinc oxide (TiO2:ZnO) nanorod thin films were deposited on glass substrates via a sol-gel spin-coating technique for deposition of a TiO2 seed layer and solution-immersion method for growth of ZnO nanorods. ZnO nanorods were grown at different molar concentrations (0.002-0.060 M) on a TiO2 seed layer annealed at 450 °C for 1 h. The surface topography of the TiO2 seed layer and structural properties of the TiO2:ZnO nanorods were characterized using atomic force microscopy, field emission scanning electron microscopy and X-ray diffraction (XRD). The absorbance performance has been observed by a UV-vis spectrophotometer. The seed layer improved the structures of ZnO nanorods by reducing the diameter size of the nanorods. The denser distribution of nanorods with improved crystallinity was observed at higher concentrations. At 0.060 M, the XRD peak was slightly shifted to a higher angle, attributed to decrease in tensile stress between the TiO2 seed layer and nanorods. Meanwhile, UV-vis spectra of the films displayed high absorption in the UV region and high transparency in the visible region.