Reducing Trap States in Printed Indium Zinc Oxide Transistors by Doping with Benzyl Viologen

Abstract An air‐stable, strongly reducing molecule benzyl viologen (BV) is used to induce charge‐transfer doping of the indium zinc oxide semiconductor in inkjet‐printed thin‐film transistors. The device mobility is improved from 5.8 ± 1.4 cm 2 V −1 s −1 in the undoped devices and reached up to 8.7 ± 1.0 cm 2 V −1 s −1 after BV treatment. Through measurement of frequency‐dependent admittance and capacitance, this work quantifies the density of interface states and shows that interfacial trap density is four times lower in the BV‐doped transistors compared to undoped devices.