Enhanced charge transport of conjugated polymer/reduced graphene oxide composite films by solvent vapor pre-treatment

In this study, a facile approach that could provide a significant enhancement of the charge transport properties of the conjugated polymer/reduced graphene oxide (rGO) composite films using a non-solvent vapor treatment is reported. As the methanol vapors were exposed to the poly(3-hexylthiophene) (P3HT)/rGO composite solution, P3HT chains self-assembled to create nanofibrillar structures via favorable π–π interactions. The π–π staking in P3HT occurred by the non-solvent vapor exposure to minimize unfavorable interactions of P3HT chains with the non-solvent vapor molecules. The self-assembly of P3HT chains was chiefly facilitated by the presence of rGO. This is because the surface of rGO can serve as nucleation sites for the growth of P3HT nanowires. Consequently, P3HT/rGO composite films obtained from the methanol vapor treated corresponding solutions exhibited a high charge carrier mobility (1.3 × 10−1 cm2 V−1 s−1), which is approximately 11-times and 6.5-times higher than those of pristine P3HT (1.2 × 10−2 cm2 V−1 s−1) and P3HT/rGO (2.0 × 10−2 cm2 V−1 s−1) composite films, respectively.