Surface-Mediated Solidification of a Semiconducting Polymer during Time-Controlled Spin-Coating

Spin-casting a polymer semiconductor solution over a short period of only a few seconds dramatically improved the molecular ordering and charge transport properties of the resulting semiconductor thin films. In this process, it was quite important to halt spinning before the drying line propagation had begun. Here, we elucidated the effects of the substrate surface characteristics on the drying kinetics during spin-coating, systematically investigated the microstructural evolution during semiconducting polymer solidification, and evaluated the performances of the resulting polymer field-effect transistors. We demonstrated that the spin time required to enhance the molecular ordering and electrical properties of the polythiophene thin films was strongly correlated with the solidification onset time, which was altered by surface treatments introduced onto the substrate surfaces.