Performance of organic field-effect transistors with poly(3-hexylthiophene) as the semiconductor layer and poly(4-vinylphenol) thin film untreated and treated by hexamethyldisilazane as the gate insulator

The relationship between the carrier mobility and the structure/morphology of polymer semiconductor molecules on a substrate remains a very important issue in organic electronics. In this paper, the relationship between the crystallinity of drop-cast regioregular poly(3-hexylthiophene-2,5-diyl) (RR-P3HT) thin films and polymer substrates was discussed by using heat-crosslinkable poly(4-vinylphenol) (PVP) as the gate insulator in organic field-effect transistors (OFETs). The effect of a self-assembled monolayer (SAM) of 1,1,1,3,3,3-hexamethyldisilazane (HMDS) on crosslinked PVP was also examined and the performance of the OFET was investigated. Results show that not only the orientation and crystallinity of the polymer semiconductor are very important in determining the OFET performance, but also the gate properties, surface roughness, and the interface properties between the gate and semiconductor layers are important factors.