Controlled ambipolar charge transport of polymer semiconductors by viologen-doping for complementary-like electronic circuits

Abstract

We report on controllable ambipolar charge transport in polymeric semiconductors by the incorporation of viologen-based molecular additives. The viologen dopants selectively contribute to an increase in the charge carrier density of the electrons while enhancing the fibril-like crystalline thin-film morphology of the polymers to provide favourable charge transport in staggered-structure organic field-effect transistors. A well-balanced ambipolar behaviour is obtained at the optimised viologen concentration in donor-acceptor conjugated polymers by conversely modulating the p- and n-channel carrier mobilities within a given active layer. Complementary-like inverter circuits are demonstrated through the application of a simple blanket coating of a viologen-doped ambipolar semiconductor, which exhibits high ideal voltage switching at around half of the applied bias, a high gain of more than 50, and sufficient noise immunity to enable various applications for printed electronics and optoelectronics.