Fabrication of Polymer-Based Transistors with Carbon Nanotube Source Drain Electrodes Using Softlithography Techniques

Abstract

In this study, we have developed the multilayer deposition and patterning processes with a resolution of 1 µm for fabricating polymer-based organic field effect transistors (p-OFETs) based on vacuum-free, solution processable softlithography techniques. We have used regioregular poly(3-hexylthiophene) (P3HT) as the soluble polymer semiconductor, and poly(methyl methacrylate) (PMMA) and polyimide as the soluble and insoluble polymer gate insulators, respectively. We have used multiwalled carbon nanotubes (MWNTs) as the printed source–drain (S–D) electrodes in order to fabricate vacuum-free, all printed OFETs. The p-OFETs with MWNT S–D electrodes exhibit higher hole mobility and on/off ratio than the devices with vacuum-evaporated Au electrodes, probably owing to the better contact of the electrode interface and damage-free transfer of electrodes onto the gate insulator. The mobility was further improved by the crystallization of the P3HT film after heat treatment prior to the pattern transfer of P3HT.