Structural, morphological and optical properties of sol gel processed CdZnO nanostructured films: effect of precursor solvents

Cadmium-doped zinc oxide (CZO) has been the potential candidate for the fabrication of low-cost transparent conductors having applications in energy conversion devices such as thin-film solar cells and light-emitting diodes. In this work, the effect of different precursor solvents on the structural, morphological, and optical properties of sol–gel spin-coated CZO films was investigated. The X-ray diffraction study has revealed the hexagonal wurtzite crystal structure with crystallite size ranging from 45 to 49 nm for these films. The surface morphology of these films was analyzed by the atomic force microscopy. The precursor solvent effect was also analyzed using the UV–vis spectroscopy and fluorescence spectroscopic techniques. All the prepared films show the larger values of optical transparency (>80%) along with the shift in the fundamental absorption edge and the direct optical gap was found to be between 3.14 and 3.19 eV. The highly intense band edge emission for the sample was synthesized using the 2-ethoxyethanol while the presence of other defect-related bands in the other samples has been observed. The change in the precursor solvent volatility influences the crystal structure to favor the change in the density/type of defect states in the bandgap is used to discuss the present results. The formation of highly porous films will be suitable for gas sensor applications while the larger value of optical transparency and lower surface roughness have their probable application as the transparent electrodes in optoelectronics.