Effects of contact treatments on solution-processed n-type dicyano-ovalenediimide and its complementary circuits

Abstract

The device performance of bottom-contact organic field-effect transistors (OFETs) was limited by contact resistance which originates from a non-optimal semiconductor growth morphology and limited charge injection area. Self-assembled monolayer (SAM) treatment has proved to be an effective approach to optimize thin film growth and align the energy levels. This SAM-induced work-function modification has different effects on the charge injection barrier as well as on the device performance in terms of threshold voltage. These results were analysed in detail from the perspectives of surface morphology and energy alignment at the Au–semiconductor interface in n-type ovalenediimide (ODI-CN)-based OFETs. Finally, complementary inverters were built using pentacene (p-type) and ODI-CN (n-type) OFETs, and these showed a voltage gain of 13.