Low-voltage organic thin film transistors and circuits with molecular gate dielectrics

Abstract

To reduce the operating voltage of organic thin film transistors (TFTs) to a few volts (similar to state of the art silicon integrated circuits), a molecular thin film transistor concept based on an ultra thin molecular self assembled monolayer (SAM) gate dielectric in combination with a high mobility organic semiconductor is presented. Having a gate dielectric thickness of 2.5 nm, these TFTs can be operated with supply voltages of less than 2 V. The TFTs have a carrier mobility up to 1 cm²/Vs, an on/off current ratio of 10⁶, and a subthreshold swing of 100 mV/decade. Owing to the excellent insulation properties of the SAM dielectric, the TFTs have lower gate leakage than silicon MOSFETs with a thermally grown SiO₂ dielectric of similar thickness. Results on the first integrated circuits (inverters and ring oscillators) with molecular gate dielectrics, manufactured on glass and on flexible polymeric substrates, demonstrate the practicability of the molecular dielectric approach for applications.