Enhancement of field effect mobility of poly(3-hexylthiophene) thin film transistors by soft-lithographical nanopatterning on the gate-dielectric surface

The submicroscaled octadecyltrichlorosilane (OTS) line patterns on gate-dielectric surfaces were introduced into the fabrication of organic field effect transistors (OFETs). These spin-cast regioregular poly(3-hexylthiophene) films on soft-lithographically patterned SiO2 surfaces yielded a higher hole mobility (similar to 0.072 cm(2)/V s) than those of unpatterned (similar to 0.015 cm(2)/V s) and untreated (similar to 5x10(-3) cm(2)/V s) OFETs. The effect of mobility enhancement as a function of the patterned line pitch was investigated in structural and geometric characteristics. The resulting improved mobility is likely attributed to the formation of efficient pi-pi stacking as a result of guide-assisted, local self-organization-involved molecular interactions between the poly(3-hexylthiophene) polymer and the geometrical OTS patterns. (C) 2007 American Institute of Physics.