In-Place Printing of Flexible Electrolyte-Gated Carbon Nanotube Transistors With Enhanced Stability
Jorge A. Cardenas, Shiheng Lu, Nicholas X. Williams, James L. Doherty, Aaron D. Franklin
Abstract
Ion gel-based dielectrics have long been considered for enabling low-voltage operation in printed thin-film transistors (TFTs), but their compatibility with in-place printing (a streamlined, direct-write printing approach where devices never leave the printer mid- or post-process) remains unexplored. Here, we demonstrate a simple and rapid 4-step in-place printing procedure for producing low-voltage electrolyte-gated carbon nanotube (CNT) thin-film transistors at low temperature (80 °C). This process consists of the use of polymer-wrapped CNT inks for printed channels, silver nanowire inks for printed electrodes, and imidazolium-based ion gel inks for printed gate dielectrics. We find that the efficacy of rinsing CNT films and printing an ion gel in-place is optimized using an elevated platen temperature (as opposed to external rinsing or post-process annealing), where resultant devices exhibited on/off-current ratios exceeding 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , mobilities exceeding 10 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , and gate hysteresis of only 0.1 V. Additionally, devices were tested under mechanical strain and long-term bias, showing exceptional flexibility and electrochemical stability over the course of 14-hour bias tests. The findings presented here widen the potential scope of print-in-place (PIP) devices and reveal new avenues of investigation for the improvement of bias stress stability in electrolyte-gated transistors.