Low-voltage pentacene field-effect transistors with ultrathin polymer gate dielectrics

Organic field-effect transistors (OFETs) for low-voltage operation have been realized with conventional polymer gate dielectrics such as polyimides and cross-linked poly-4-vinyl phenols (PVPs) by fabricating ultrathin films. These ultrathin polymers (thickness ∼10 nm) have shown good insulating properties, including high breakdown fields (≫2.5 MV/cm). With ultrathin dielectrics, high capacitances (≫250 nF/cm²) have been achieved, allowing operation of OFETs within -3 V. Pentacene OFETs with ultrathin PVP dielectrics exhibit a mobility of 0.5 cm²/V s, an on-off ratio of 10⁵, and a small subthreshold swing of 174 mV/decade when devices are operated at -3 V.