Low-voltage organic field-effect transistors based on novel high-κ organometallic lanthanide complex for gate insulating materials

A novel high-κ organometallic lanthanide complex, Eu(tta)3L (tta=2-thenoyltrifluoroacetonate, L = 4,5-pinene bipyridine), is used as gate insulating material to fabricate low-voltage pentacene field-effect transistors (FETs). The optimized gate insulator exhibits the excellent properties such as low leakage current density, low surface roughness, and high dielectric constant. When operated under a low voltage of −5 V, the pentacene FET devices show the attractive electrical performance, e.g. carrier mobility (μFET) of 0.17 cm2 V−1 s−1, threshold voltage (Vth) of −0.9 V, on/off current ratio of 5 × 103, and subthreshold slope (SS) of 1.0 V dec−1, which is much better than that of devices obtained on conventional 300 nm SiO2 substrate (0.13 cm2 V−1 s−1, −7.3 V and 3.1 V dec−1 for μFET, Vth and SS value when operated at −30 V). These results indicate that this kind of high-κ organometallic lanthanide complex becomes a promising candidate as gate insulator for low-voltage organic FETs.