Enhanced Functional Properties of Sol-gel Derived ZnO-based Nanocomposite Thin Films Incorporating Ag, TiO<sub>2</sub>, and Graphene Nanoparticles

This study reports the synthesis and characterization of ZnO-based nanocomposite thin films prepared by the sol-gel method associated with spin coating technique, with incorporation of silver (Ag), titanuim oxide (TiO<sub>2</sub>), and graphene nanoparticles as functional additive. The aim of this work is to investigate the influence of these nanoinclusions on the structural, optical, and electrical properties of ZnO thin films. X-ray diffraction (XRD) results confirm the retention of the hexagonal wurtzite structure of ZnO, with additional reflections at 38,1°, 44,3°, and 64,4° attributed to Ag, 25,3° and 48 ° to anatase TiO<sub>2</sub>, and a broad peak near 26° to GO. Scanning Electron Microscopy (SEM) analyse reveals enhanced grain connectivity and surface uniformity in composite films. UV-Vis spectroscopy indicates a tunable optical bandgap and improved transmittance in the visible range, especially for TiO<sub>2</sub> and graphene-loaded films. Electrical measurements show a significant decrease in resistivity from 4,5*10<sup>3</sup> Ω.cm (ZnO) to 3,2*10<sup>2</sup> Ω.cm (ZnO-Ag), 1,7*10<sup>2</sup> Ω.cm in the ternary composite, with corresponding conductivity up to 5,9*10<sup>-3</sup> S/cm and carrier mobility of 7,6 cm<sup>2</sup>/V.s in Ag and graphene-containing films, attributed to improved charge carrier mobility and percolation pathways. The multifunctional enhancement observed in these ZnO nanocomposites positions them as promising materials for transparent electrodes, photocatalytic devices, and UV photodetectors.