Using a thermally-crosslinkable organosiloxane-based organic-inorganic hybrid material, solution-processable gate dielectric layer for organic thin-film transistors (OTFTs) have been fabricated. The hybrid dielectric was synthesized by the sol-gel process. The surface of the prepared dielectric was modified by self-assembled monolayers (SAMs) treatment using wet chemical method. Prior to surface modification, the chemical inertness of prepared dielectric was investigated by immersing into various solvents such as toluene, acetone, isopropyl alcohol, and DI-water. The existence of SAMs on the surface of dielectric was confirmed by measuring current density-electric field characteristics and it was observed that surface morphology of SAMs-treated hybrid dielectric was very smooth.