Effect of Inserting Teflon as a Surface Modification Layer on Bottom-Contact Pentacene-Based Organic Thin-Film Transistors

Abstract

This study reports the effect of poly(tetrafluoroethylene) (Teflon) as a surface modification layer, which was deposited on the surface of gate insulator and source/drain (S/D) electrodes, on bottom-contact pentacene-based organic thin-film transistors (OTFTs). The inserted 1.5-nm-thick Teflon layer can enhance the device performance because of the improved molecular orientation in pentacene film and reduced contact resistance (RC) between the pentacene film and the S/D electrodes. The improved molecular orientation of pentacene film is caused by the hydrophobic and smooth Teflon layer surface. The reduced RC is a result of the tunneling process at the Au/pentacene interface. This study also found that the device performance decreased as the Teflon layer increased in thickness. This is because of the increased RC and decreased carrier injection efficiency between the pentacene film and the S/D electrodes. Compared to devices without a Teflon layer, the drain current and field-effect mobility of devices with a 1.5-nm-thick Teflon layer increased by 93 and 105%, respectively.