There is provided herein a performance-enhancing composition comprising inorganic nanoparticles dispersed in a polymer selected from the group consisting of polysiloxane, polysilsesquioxane, and mixtures thereof. This composition, when applied to a thin-film transistor, such as a bottom-gate thin-film transistor, as an overcoat or top layer, improves the carrier mobility and current on/off ratio of the thin film transistor. Also provided is the thin-film transistor produced utilizing this process and/or composition.