High performance low-voltage organic field-effect transistors enabled by solution processed alumina and polymer bilayer dielectrics

• Low-voltage operation of pentacene based p-type OFETs.
• The effect of these Al2O3 dielectric capacitance on performance in OFETs were systematically studied.
• Combing PMMA and Al2O3 to form PMMA/Al2O3 bilayer dielectrics can further boost mobility up to 0.84 cm2/Vs.

High performance low-voltage pentacene-based organic field-effect transistors (OFETs) are fabricated utilizing solution-processed alumina (Al2O3) as high-k gate dielectric, and the effects of gate dielectric capacitance on the device performance were investigated. The results show that Al2O3 gate dielectric with optimized thickness can afford OFETs performance with field-effect mobility of 0.65 cm2/Vs, threshold voltage of −0.6 V, Ion/Ioff ratio of 4 × 103 and sub-threshold swing of 0.45 V/dec, at operating voltage as low as −4 V. After employing a very thin PMMA film onto Al2O3, the mobility of these OFETs with bilayer dielectric can be further boost up to 0.84 cm2/Vs. According to electrical and microscope characterizations, the performance improvement of OFETs can be contributed to low surface trap density and high capacitance density of Al2O3/PMMA bilayer dielectrics.