The Effect of TiO₂ Nanoparticle Doping on the Structural and Optical Properties of Coal Fly Ash Thin Films

This study has investigated the impact of TiO₂ doping on the structural and optical characteristics of fly ash thin films. The thin films were produced using the spin-coating technique, and the structural investigation was conducted using XRD and SEM techniques to evaluate the crystallinity of the samples and to calculate related structural parameters, including crystallite size, which was found to be influenced by the TiO₂ content. Additionally, SEM images of the thin film surfaces indicated a denser structure characterized by a reduced quantity of pores in the thin films containing TiO₂. Furthermore, the introduction of TiO₂ as a dopant resulted in a reduction of the optical band gap energy of the films from 3.956 eV to 3.900 eV. Also, the doping led to an increased refractive index and extinction coefficient. Moreover, it notably enhanced the optical conductivity, which reached \(4.61\times {10}^{13 }{S}^{-1}\) $4.61\times {10}^{13}{S}^{-1}$ . The enhanced optical characteristics of the thin films render them to be appropriate for a wide range of photovoltaic applications.