Thin Dielectric Layer Enabled Low Voltage Operation of Fully Printed Flexible Carbon Nanotube Thin Film Transistors

摘要： Quality of printable dielectric layer has become one of the major obstacles to achieve high performance fully printed transistors. A thick dielectric layer will require high gate voltage to switch on and off the transistors, which will cause high power dissipation in printed devices. In response to this challenge, fully printed carbon nanotube (CNT) based thin film transistors (TFTs) have been fabricated on flexible membranes such as polyimide and liquid crystal polymer using aerosol jet printing (AJP). These devices can be operated at bias voltages below ±10 V (drain/gate voltages around ±6 V). It is much smaller than the previously reported values for fully printed CNT-TFTs using xdi-dcs (mixture of poly(vinylphenol)/poly (methylsilsesquioxane)) as dielectric and using a single printing method. This is enabled because of thin dielectric layer (~300 nm) and good uniformity in printed CNT network. The printed CNT-TFTs show on/off ratio > 105, and mobility > 5 cm2V-1s-1. Layer-by-layer deposition of CNT allows highly uniform and dense network formation, and the optimization of the xdi-dcs concentration using natural butyl alcohol provides a high-yield printing of a thin dielectric layer. Collectively, this work shows a potential of using fully printed CNT-TFTs in various flexible electronic applications such as wearable sensors, actuators, artificial skins, displays and wireless tags and antennas.