Transparent pentacene organic thin film transistors with polyimide dielectrics

Transparent pentacene organic thin film transistors (OTFTs) were prepared on ITO substrate with the spin-coated polyimide (PI) film as the gate dielectric. The PI film showed a good surface flatness and enabled a well crystallized pentacene film deposited on it. The electrical performances of the pentacene OTFTs on PI/ITO substrate were investigated and compared with those on SiO₂/Si substrate. The devices with PI dielectric showed lower carrier mobility due to a smaller crystalline size of the pentacene on PI substrate. However, comparable I_on/I_off ratio and the smaller subthreshold swing S were obtained. Our results demonstrate that the PI film presents a great potential as the dielectric in transparent OTFT devices.