Characteristic of organic thin film transistor with a high-k insulator of nano-TiO₂ and polyimide blend

The preparation of nanocomposite as gate dielectric film was carried out by blending polyimide and nano-TiO₂ particle to enhance the capacitance of gate dielectric. When the concentration of the nano-TiO₂ particle was less than 2 vol % and was well dispersed in polyimide slurry, a nanocomposite film with a homogeneous distribution of nano-TiO₂ particles in polyimide and low roughness was obtained after curing at 200 °C, resulting in low leakage current density of the nanocomposite film and high on/off ratio of the organic thin film transistor (OTFT) device. A strong correlation between the morphology and electrical properties of the nanocomposite gate dielectric film is reflected in the OTFT device performance. Because capacitance of the gate dielectric film and proportion of thin film phase of the pentacene both increased when the pentacene was deposited on a nanocomposite gate dielectric film, the mobility and the threshold voltage of OTFT noticeably improved.