Fabrication of Organic Thin-Film Transistors Based on Cross-Linked Hybrid Dielectric Materials

We report here the synthesis and dielectric properties of cross-linked hybrid dielectrics for organic field-effect transistor application. Hybrid thin films were first fabricated by hydrolysis of methacrylate-modified titanium and zirconium alkoxides and were further cross-linked via polymerization under UV. The dielectrics exhibit high dielectric constants (5.2–9) and good insulating properties with low leakage current densities (10-6–10-7 A/cm2) even though the dielectric film thickness was about 25–150 nm. Furthermore, the hybrid thin films had smooth and hydrophobic surfaces. The fabricated pentacene field-effect transistors using these dielectrics show good electric performance, including a carrier mobility as large as 0.29 cm2 V-1 s-1, a subthreshold swing as low as 0.13 V/decade, an on/off current ratio of ~105, and a low threshold voltage of 0.3 V with TiO2 hybrid dielectrics. Organic thin-film transistors (OTFTs) fabricated with ZrO2 hybrid insulators exhibit a carrier mobility of 0.21 cm2 V-1 s-1 with an Ion/Ioff ratio of ~104, a threshold voltage of -0.83 V, and a subthreshold swing of 0.39 V/decade.