Organic thin film transistors with soluble processing hybrid dielectrics

In this study, organic thin-film transistors (OTFTs) using pentacene as an organic semiconductor have been made by hybrid dielectrics of crossed linked poly-4-vinylphenol (PVP) / methyl siloxane-based spin-on-glass (SOG) into gate dielectrics by a spin coating method. Atomic force microscope (AFM) has been used to characterize the surface morphology of spin-coated dielectric films, because a very smooth surface (Root Mean Square, Roughness = 0.44 nm) of hybrid film effectively affects the growth of organic pentacene molecules. To calibrate the surface of dielectric film, we measured contact angles using deionized water and ethylene glycol so that the surface energies of the dielectric films were calculated. We obtained devices with electrical characteristics, including field-effect mobility as large as 1.50 cm²/Vs at the maximum saturation current of -99.07 × 10^-6 A, threshold voltage as low as -2V.