Materials integration for printed zinc oxide thin-film transistors: Engineering of a fully-printed semiconductor/contact scheme

We report for the first time on the impact of a printed indium tin oxide (ITO) layer inserted between a printed silver conductor and solution processed zinc oxide (ZnO) leading to an optimized semiconductor/contact scheme for full print integration. Introducing the ITO interlayer, the contact resistance is reduced by two orders of magnitude. Nanoparticle thin-film transistors (TFTs) in this Ag/ITO contact configuration show improved saturation mobility of 0.53 cm(2) . V-1 . s(-1) with respect to 0.08 cm(2) . V-1 . s(-1) without ITO interlayer. The contact improvement can be attributed to either an increased charge carrier concentration or a reduction of band offsets at the ZnO/electrode interface.