Dependence of structural and optical properties of sol-gel derived ZnO thin films on sol concentration

► ZnO thin films have been prepared by sol-gel method using various sol concentrations. ► The ZnO thin films deposited in this study had approximately equal thickness, excluding the influence of film thickness on the physical properties. ► The results showed that low sol concentration was favorable for obtaining high c-axis oriented ZnO thin films with good crystalline quality. ► Photoluminescence spectra indicated that the defect-related blue emission was increased with the enhancement of sol concentration.