ABSTRACT
Organic field-effect transistors (OFETs)1,2 and other “plastic” electronic devices3 are currently scrutinized for use in printed, flexible, integrated electronics and displays. Ideally, these systems are fast, operate at low voltage, and are robust enough to be manufactured using standard printing techniques.1,4,5 Current printing technology allows for a separation between the source and drain electrodes in OFETs of less than 1 µm.6 In traditional OFETs, the organic semiconductor film is separated from the gate electrode by a thin insulating dielectric film. The gate-insulator-semiconductor sandwich can be seen as a capacitor, where the charge density in the semiconductor, and thus the conductance of the semiconductor channel, is tuned by the applied voltage. Tremendous efforts have been devoted to reach high capacitance (per area) Ci between the gate and the channel to allow transistors to operate at low voltage.7,8 Since the dielectric constant k of organic materials usually is quite low, very thin gate insulator
10.1 Introduction .................................................................................................. 193 10.2 Polyelectrolyte-Based Capacitors ................................................................. 194 10.3 Polyelectrolyte-Gated Field-Effect Transistors ............................................ 195 10.4 Physical Mechanisms .................................................................................... 198
10.4.1 Electrochemical Doping vs. Field-Effect ......................................... 198 10.4.2 Hole versus Ion Motions ...................................................................200 10.4.3 Insulator Polarization Mechanisms ..................................................202
