Comparative analysis of the effect of annealing temperature on the structural and optical properties of chemically deposited CeO2/ZnO and CeO2/NiO core-shell thin films for photovoltaic and optoelectronic applications

This paper describes the deposition and characterization of CeO2/ZnO and CeO2/NiO coreshell thin films with emphasis on the effect of post deposition temperature on the optical properties and structural patterns. The structural temperature-dependent analysis indicated different XRD patterns for both films. However, both films are polycrystalline as depicted by the various peaks in the XRD diffractograms. The SEM images for both films differ in terms of their particle aggregation and distribution. The dependence of the transmittance, absorption coefficient, band gap, refractive index, extinction coefficient, imaginary dielectric constant on annealing temperature were investigated. The results showed that the transmittances of the films were significantly reduced by the heat treatments. The transmittance reduced from 92% to 65% for CeO2/ZnO film samples and 63% to 30% for CeO2/NiO film samples. The band gap showed considerable variation with annealing temperatures. The band gaps of all samples were in ranges of 1.75–3.85 eV and 3.50- 3.88eV for CeO2/ZnO and CeO2/NiO core-shell thin films respectively. The values of the energy band gap strongly indicate that the films can be used in different optoelectronic applications including solar photovoltaic.