Spatial Control of the Threshold Voltage of Low-Voltage Organic Transistors by Microcontact Printing of Alkyl- and Fluoroalkyl-phosphonic Acids

Abstract

Low-voltage-driven organic thin-film transistors (organic TFTs) with spatially controlled threshold voltages (-1.2 and -0.36 V) were fabricated for the first time. Using the microcontact printing method, tetradecylphosphonic acid (HC14-PA)and pentadecylfluoro-octadecylpho-sphonic acid (FC18-PA) were transferred to form ultrathin layers in different regions on a substrate. Together with plasma-grown aluminum oxide (AIOx) layer, the stamped layers were shown to have equal insulating ability as the dipped method monolayer. The feasibility of the area-selective stamping method was displayed using locally controlled inverter circuits. The shift of turn-on voltage for those transistors was consistent with the threshold voltage shift of the transistors.