Organic field-effect transistors as new paradigm for large-area molecular junctions

Self-Assembly Monolayers (SAMs) are considered a promising route for solving technolog-ical hindrances (such as bias-stress, contact resistance, charge trapping) affecting the elec-trical performances of the Organic Field-Effect Transistors (OFETs). Here we use an OFETbased on pentacene thin film to investigate the charge transport across conjugated SAMsat the Au/pentacene interface. We synthesized a homolog series of p -conjugated mole-cules, termed Tn-C8-SH, consisting of a n-unit oligothienyl Tn (n =1...4) bound to anoctane-1-thiol (C8-SH) chain that self-assembles on the Au electrodes. The multi-paramet-ric response of such devices yields an exponential behavior of the field-effect mobility ( l ),current density (J), and total resistivity (R), due to the SAM at the charge injection interface(i.e. Au-SAM-pentacene). The surface treatment of the OFETs induces a clear stabilization ofdifferent parameters, like sub-threshold slope and threshold voltage, thanks to standard-ized steps in the fabrication process. 2012 Elsevier B.V. All rights reserved.