Low-temperature self-curable polyacrylate copolymer gate insulator for hysteresis-free organic field-effect transistors

We report on the fabrication of hysteresis-free organic field-effect transistors (OFETs) and metal–insulator–semiconductor (MIS) capacitors that utilize self-curable polyacrylate type copolymer (L-PA) as a gate insulator. Superior to previously reported polymer gate insulators, L-PA for the first time enables hysteresis-free OFETs and MIS capacitors through a low temperature (110–140 °C) curing process, which is compatible with the conventional plastic substrates (Tg < 150 °C) for flexible electronics. The dielectric film showed high dielectric strength >4.5 MV/cm and low leakage current density of 5 × 10−9–10−8 A/cm2 at 1 MV/cm, while the transistors displayed a decent field-effect mobility (μ) of 0.91 cm2/V s, on/off current ratio (Ion/Ioff) of 106 and inverse subthreshold slope (SS) as low as 1.13 V/dec. Chemical changes were verified by FT-IR, DSC (differential scanning calorimetry) and TGA (thermo-gravimetric analysis) experiments and the surface properties of dielectrics and morphology of pentacene layers were also examined and correlated with OFET device performance.

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► We report a low-temperature (110–140 °C) self-curable copolymer gate insulator (L-PA).
► It shows high dielectric strength and low electrical leakage.
► Negligible hysteresis in C-V characteristics, transfer and output curves for MIS capacitors and OFETs, respectively.
► Decent field-effect mobility, on/off current ratio, and subthreshold slope are achievable with the transistors.
► This polymer dielectric is suitable for fabricating low temperature-processed, reliable electronic devices.