¹ Department of Graphic Arts and Photophysics, Faculty of Chemical Technology, University of Pardubice, Pardubice-532 10, Czech Republic

² Department of Physics, Chemistry and Biology (IFM), Linköping University-581 83, Sweden

³ School of Mechanical Engineering, KIIT Deemed to be University, Bhubaneswar-751024, India

* Correspondence: sudesna.roy@gmail.com

In this manuscript, we have comprehensively investigated the structural, optical, photoluminescence (PL), and Raman spectra of sol-gel-synthesized ZnO thin films using a combination of experimental and theoretical approaches. The deposited ZnO thin film was further characterized using scanning electron microscopy (SEM) with elemental dispersive spectroscopy (EDS), atomic force microscopy (AFM), X-ray diffraction (XRD), UV-visible spectroscopy, photoluminescence (PL), and Raman spectroscopy. XRD and UV-Vis. Results suggested that the as-synthesized ZnO film is a uniform thin film with an average surface roughness of 5.5 ± 0.5, and that it has a wurtzite structure, as confirmed by XRD analysis. Moreover, the optical bandgap (E_g) was determined to be 3.39 eV. In contrast, EDS analysis confirms the presence of Zn and O atoms in the thin film. PL and Raman measurements reveal thin-film defect levels, possibly due to Zn interstitials, oxygen vacancies, and nonradiative recombination. A first-principles DFT study has been conducted to validate the experimental finding. The electronic band structure (3.37 eV) and absorption edge (393 nm) obtained from the DFT calculation were well-matched with the experimental findings. Also, theoretical Raman spectra confirm the wurtzite structure of ZnO and support our experimental Raman data. The synergy between experimental studies and theoretical insights into the material's properties is necessary to highlight its potential for future solar cell applications.