Understanding The Influence Of Contact Resistances On Short-Channel High-Mobility Organic Transistors In Linear And Saturation Regimes

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 (mu(FET)) of 10 cm(2) V(-1 )s(-1), while effective mu(FET) significantly decreases with reducing channel length. Here, we investigate the influence of contact resistances on the effective mu(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 mu(FET) in short-channel OFETs. An anomalous trend in the channel-length dependence of linear and saturation mu(FET) in C-12-BTBT FETs is also discussed.