Low-resistance contacts of electroless-plated metals with high-mobility organic semiconductors: Novel organic field-effect transistors with solution-processed electrodes

Abstract

The establishment of a reliable vacuum-free method for the formation of electrical contacts on high-performance organic semiconductors has become an urgent task due to rapid progress made in the development of solution-processable high-mobility organic field-effect transistors (OFETs). We have recently proposed that electroless plating, a standard technology to mass produce wirings in currently commercialized electronic devices, is suited for high-performance solution-crystallized OFETs. A low contact resistance at the source and drain electrodes is necessary with organic semiconductors for high-speed device operation; therefore, we have evaluated the contact resistance using the transfer line method. A top-contact geometry with sufficient contact area is employed to achieve stable carrier injection, which has enabled contact resistances as low as 1.4 kΩ cm on a polyethylene naphthalate substrate at a gate voltage of −10 V. This marks outstanding performance among the solution-processed metal electrodes reported for OFETs, particularly on plastic substrates. The result indicates that high-quality boundaries with minimized trap densities are realized due to the mild conditions of the electroless plating process at room temperature.