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/cm ²) 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 cm ² 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 0.3V with TiO ₂ hybrid dielectrics. Organic thin-film transistors (OTFTs) fabricated with ZrO ₂ hybrid insulators exhibit a carrier mobility of 0.21 cm ² V ^-1 s ^-1 with an I _on=I _off ratio of ∼104, a threshold voltage of ∼0:83 V, and a subthreshold swing of 0.39 V/decade.