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 (∼0.072cm2∕Vs) than those of unpatterned (∼0.015cm2∕Vs) and untreated (∼5×10−3cm2∕Vs) 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 π-π stacking as a result of guide-assisted, local self-organization-involved molecular interactions between the poly(3-hexylthiophene) polymer and the geometrical OTS patterns.