Contact Resistance of Inkjet-Printed Silver Source–Drain Electrodes in Bottom-Contact OTFTs

In this paper, we report contact resistance analysis between inkjet-printed silver source-drain (S/D) electrodes and organic semiconductor layer in bottom-contact organic thin-film transistors (OTFTs) using transmission line method (TLM). Inkjet-printed silver electrodes, spin-coated PVP and evaporated pentacene were used as gate and S/D electrodes, gate dielectric layer and semiconductor layer, respectively. On a common gate electrode, S/D electrodes with various channel length from 15 to 111 μm were printed for TLM analysis. The same bottom-contact OTFT with evaporated silver S/D electrodes was also fabricated for reference. We extracted contact resistances of 1.79 MΩ·cm and 0.55 MΩ·cm for inkjet-printed and evaporated silver electrodes, respectively. Higher contact resistance for inkjet-printed silver electrodes can be explained in terms of their relatively poor surface properties at electrode edge that can cause small pentacene molecule grain or slight oxidation of surface during the printed silver sintering process.