Low-voltage organic field-effect transistors by using solution-processable high-κ inorganic-polymer hybrid dielectrics

Abstract Organic field-effect transistors (OFETs) incorporating hybrid high- κ inorganic Al 2 O 3 and polymer dielectrics, including polyvinyl alcohol (PVA), polystyrene (PS), or polymethyl methacrylate (PMMA), through solution-processing techniques were fabricated. The analyses revealed that the high surface energy and hydrophilicity property of Al 2 O 3 and PVA, and the relatively hydrophobic property of PS surface, hindered the performance of corresponding OFETs. The Al 2 O 3 /PMMA-based OFET achieved the optimized performance, with a threshold voltage of −2.7 V, a hole carrier mobility of 0.056 cm 2 /Vs, and a current on/off ratio of 1.0 × 10 4 at a low operating voltage of −5 V. Through analyzing the characteristics of leakage current, capacitance, contact resistance, and trap density of OFETs, we found that the PMMA-engaged films possessed the optimized electrical properties. The introduction of PMMA eliminated the interfacial trapping, thereby lowering the threshold voltage and enhancing the performance of the device. The COMSOL Multiphysics simulation was conducted to confirm the physical mechanism. The strategy of utilizing Al 2 O 3 /PMMA hybrid dielectric could simultaneously ensure the low operating voltage and good performance of OFET, while guaranteeing the low leakage current by the thick PMMA.