Flexible Printed Top-Contact Organic Thin-Film Transistors

A staggered organic thin-film transistors (TFTs) have considerable benefits of charge injection. The contact resistance of a OTFT with top-contact structure is typically lower, compared to that of a bottom-contact device. However, the staggered bottomgate organic TFTs fabricated by printing are very rare due to the difficulties of printing contact electrodes on solution-processed organic semiconductors (OSCs). In this study, we demonstrate the fabrication of flexible bottom-gate top-contact organic TFTs by optimizing the inkjet printing process of Ag nanoparticles on an OSC surface. All the layers of the printed TFTs, including organic semiconductors and silver nanoparticles, were formed by printing methods except for Parylene dielectric layer that was deposited by chemical vapor deposition. The printed staggered TFTs exhibited remarkably high carrier mobility and low threshold voltage, compared with coplanar counterparts, due to reduced contact resistance. Our approach to printing staggered TFTs can lead to flexible functional circuit with high electrical characteristics.