Ultralow Voltage Driving Circuits Based on Coplanar a-InGaZnO TFTs with Photopatternable Ionic Polymer Gate Dielectric

Abstract

Coplanar amorphous indium gallium zinc oxide (a-InGaZnO) thin film transistors (TFTs) with photopatternable ionic polymer gate dielectrics are fabricated and their inverter/shift register circuits are demonstrated. As a gate dielectric, ionic-polyurethane acrylate (i-PUA) can be patterned as small as 20 µm through conventional photolithography to achieve superior electrical properties at low operating voltages by the electric double layer formation, inducing ultrahigh channel capacitance. The fabricated solution-processed a-InGaZnO TFT with the i-PUA gate dielectric shows excellent electrical characteristics such as a field-effect mobility of 11.6 cm2 V−1 s−1, on–off ratio exceeding 107, and low threshold voltage of 0.3 V. It is also confirmed that the inverter and shift register can be fabricated based on the proposed coplanar a-InGaZnO TFTs and are successfully functional even at 60 Hz operating frequency with driving voltage levels below 3 V. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim