Fully Additive Low-Cost Printed Electronics With Very Low Process Variations

Abstract

Low-cost printed electronics (PE) on flexible substrates necessitates that its printing process embodies only additive steps (vis-a-vis subtractive steps), and processing at low temperature (e.g., $\mu $ ; and in some cases, the primary parameter is threshold voltage $V_{\mathrm{ th}}$ . We present a novel screen-printing low-cost fully additive all-air-processed low-temperature PE printing process featuring very low process variations. In particular, the process variations are ±4.9% $\mu $ and ±0.43 V $V_{\mathrm{ th}}$ . To the best of our knowledge, this is the smallest $\mu $ variations amongst all reported fully additive printing processes, and comparable to the best of subtractive processes. These very low variations are achieved by blade coating the semiconductor layer comprising a polymer-small molecular blend in a dual-solvent system, yielding a precise control of the semiconductor film formation. Further by means of careful layout, the matching between our two printed organic thin-film transistors is markedly improved from 7.2% (arising from ±4.9% $\mu $ and ±0.43 V $V_{\mathrm{ th}}$ variations) to 2.1%—to date, the best reported matching.