(Invited) Thin-Film Transistors Based on Donor-Acceptor Polymers

In this presentation we will describe device designs, modeling, and experimental results with several new diketopyrrolopyrrole DPP-based polymers and specifically discuss techniques to keep the operating voltage low (< 10 V) in small channel length (< 5 mm) devices.  We have been able to obtain mobility values of ~4 cm²/V-s with some of the materials in such devices at low operating voltages for channel lengths of 4 mm in air.  These devices possess very high temperature field-induced conductivity of any polymer FET and which exceeds that of most organic single crystal FETs reported so far.  Our best devices designs possess a bilayer gate insulator which includes a thin interfacial low- dielectric constant insulator.  We will demonstrate that the mobility improvement arises due to the suppression of the formation of Fröhlich polarons, which tend to reduce mobility when polar media such as high-k dielectrics are used with polymer semiconductors.  We will also discuss charge transport in such polymers transistors both above and below the threshold voltage.