Reduced contact resistance in organic field-effect transistors fabricated using floating film transfer method

Abstract

This paper presents an in-depth performance-based comparison of organic field-effect transistors (OFETs) prepared using the conventional spin coating (SC) technique and a recently developed floating film transfer method (FTM). A remarkable improvement in the performance of transistors fabricated using FTM was achieved in comparison to their SC counterparts. The estimated value of width-normalized contact resistance in FTM-based OFETs was an order lower in comparison to that of transistors prepared using SC technique. The observed results were credited to a significant enhancement in the length of π-conjugation due to the presence of edge-on oriented polymer chains of active layer deposited using FTM, leading to the lowering of carrier injection barrier at the Au/P3HT interface. These results were well supported through absorption, photoluminescence and Raman measurements as well as the anisotropy measurements using polarized absorption spectra, which also pointed towards the improvement in the polymer chain alignment of thin films prepared by FTM over that prepared by the conventional SC technique. The results indicate thin film morphology as a key towards reducing the contact resistance in OFETs.