Performance of poly(3-hexylthiophene) field effect transistor with high dielectric constant gate insulator

Organic field effect transistors (OFETs) were fabricated with high-kappa titanium dioxide (TiO₂) as gate insulator and regioregular poly(3-hexylthiophene-2,5-diyl) (RR-P3HT) as electronically active semiconductor. The dielectric material was prepared by sol-gel method and the gate insulator layer was fabricated by spin-coating method. The thickness of the thin films was measured using surface profile measuring system. The fabricated thin films structure was analyzed by atomic force microscopy (AFM), X-ray diffraction (XRD) and UV-visible absorption spectra. The X-ray result shows that the drop-cast RR-P3HT thin film has high crystallinity on the TiO₂ surface and leads to high field effect mobility of the OFET. Good characteristics performances were obtained with low threshold voltage (+3 V) and the field effect mobility is 3.73 times 10^-3 cm²/Vs.