The impact of carbon sp2 fraction of reduced graphene oxide on the performance of reduced graphene oxide contacted organic transistors

Abstract

One of the major bottlenecks in fabricating high performance organic field effect transistors (OFETs) is a large interfacial contact barrier between metal electrodes and organic semiconductors (OSCs) which makes the charge injection inefficient. Recently, reduced graphene oxide (RGO) has been suggested as an alternative electrode material for OFETs. RGO has tunable electronic properties and its conductivity can be varied by several orders of magnitude by varying the carbon sp2 fraction. However, whether the sp2 fraction of RGO in the electrode affects the performance of the fabricated OFETs is yet to be investigated. In this study, we demonstrate that the performance of OFETs with pentacene as OSC and RGO as electrode can be continuously improved by increasing the carbon sp2 fraction of RGO. When compared to control palladium electrodes, the mobility of the OFETs shows an improvement of ∼200% for 61% sp2 fraction RGO, which further improves to ∼500% for 80% RGO electrode. Similar improvements were also observed in current on-off ratio, on-current, and transconductance. Our study suggests that, in addition to π-π interaction at RGO/pentacene interface, the tunable electronic properties of RGO electrode have a significant role in OFETs performance.