Interfacial Interactions between Poly(3-hexylthiophene) and Substrates

Abstract

Interfacial interactions between poly(3-hexylthiophene) (P3HT) and substrate surface have been investigated. P3HT nanowhiskers of single molecule thickness were prepared from chloroform solution, and their adsorption on substrates of various surface chemistries was investigated using atomic force microscopy (AFM) and Raman spectroscopy. P3HT monolayer nanowhiskers with edge-on molecular orientation were found to adsorb readily onto a SiO2 substrate, and the amount of adsorption was significantly higher on a SiO2 surface modified with a perfluorohexyl monolayer; no P3HT adsorption was observed on a hexyl monolayer. These results suggest that electron-withdrawing groups rather than surface energy govern the interfacial interactions. On a highly oriented pyrolytic graphite (HOPG) surface, P3HT molecules adsorbed in face-on orientation, and edge-on monolayer nanowhiskers were absent on the surface. Raman spectroscopy data revealed strong charge-transfer interactions between face-on P3HT molecules and the HOPG...