Understanding the influence of contact resistances on short-channel high-mobility organic transistors in linear and saturation regimes

Abstract Solution-processed organic field-effect transistors (OFETs) based on 2,7-didodecyl[1]benzothieno[3,2-b][1]benzothiophene (C 12 -BTBT) exhibit a high channel field-effect mobilities ( μ FET ) of 10 cm 2 V −1 s −1 , while effective μ FET significantly decreases with reducing channel length. Here, we investigate the influence of contact resistances on the effective μ FET of short-channel C 12 -BTBT FETs operated in the linear and saturation regimes. The numerical calculations using an equivalent circuit involving source and drain contact resistances reveal a large influence of the effective gate-source voltage on the reduction of saturation μ FET in short-channel OFETs. An anomalous trend in the channel-length dependence of linear and saturation μ FET in C 12 -BTBT FETs is also discussed.