Interface Modification for Tuning the Contact Resistance of Metal/ Organic Semiconductor Junctions

As the performance of organic field-effect transistors improves, the limitation due to charge carrier injection at source and drain electrodes becomes crucial. This review describes the various solutions that have been developed to work around this issue. The most widespread method consists of interposing between the electrodes and the organic semiconductor film a self-assembled monolayer made of an appropriate reactive molecule. In that case, the reduction of the contact resistance may come either from an improved morphology of the semiconductor film, or to a better energy level alignment at the interface with the electrode. The respective inference of both aspects is discussed. Alternative ways to reduce the contact resistance by an appropriate surface treatment of the electrodes prior to the deposition of the semiconductor are also presented.