The triboelectric nanogenerator is a state-of-the-art device for addressing the growing problem of meeting the world's ever-increasing energy needs by converting mechanical energy into electrical energy. Using the popular semiconductor SnO2 nanostructured thin films as a triboelectric layer over contact regions, as opposed to polymers with lesser performance, increases the output power and life time of nanogenerators. In order to design a triboelectric nanogenerator, deposited thin film SnO2 is used as a friction layer with Ag electrode after heat-treatment at 623 K with a contrary layer of PMMA poly (methyl-methacrylate) with ITO electrode. The structural and electrical properties were analyzed by using scanning electron microscopy (SEM), electro-impedance spectroscopy (EIS) and atomic force microscopy (AFM) measurements. The increased output power of the triboelectric nanogenerator is attributed to the nanoscale PMMA contact charge created by tunneling electrons in the SnO2/Ag nanocomposite thin film layer. Due to its proximity to the PMMA/ITO surface, the SnO2/Ag layer causes electron field emission, and tapping the SnO2/Ag layer may result in electron cloud overlap. Similar to a semiconductor/insulator interface, the Fermi level of SnO2 plays a crucial role in electron transport. The system efficiency stated as a touch detector in a conventional keyboard that generates its own power is revealed in part by an analysis of its operating state up to the 4V.