The Importance of Contact Resistance in High-Mobility Organic Field-Effect Transistors Studied by Scanning Kelvin Probe Microscopy

Abstract

Contact resistance effect is a major issue in organic field-effect transistors (OFETs) because it can severely limit or even dominate the overall performance of OFETs. This is especially true for recently developed high-mobility OFETs. Here, we present a systematic study of the contact resistance and its effect on mobility in high-mobility 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) OFETs by scanning Kelvin probe microscopy. We find that the contact resistance effect can lower the mobility by a factor of four at some temperatures. More interestingly, it is seen that the contact resistance has significant influence on the temperature dependent mobility behavior. The contact resistance-corrected mobility demonstrates stronger band-like transport than the uncorrected mobility in the same temperature range, which has not been reported before.