Conversion of Face‐On Orientation to Edge‐On/Flat‐On in Induced‐Crystallization of Poly(3‐hexylthiophene) via Functionalization/Grafting of Reduced Graphene Oxide with Thiophene Adducts

Reduced graphene oxide (rGO) is functionalized with 2‐thiophene acetic acid (rGO‐f‐TAA) and grafted with poly(3‐dodecylthiophene) (rGO‐g‐PDDT) and poly(3‐thiophene ethanol) (rGO‐g‐PTEt) to manipulate the orientation and patterning of crystallized poly(3‐hexylthiophene) (P3HT). P3HT chains prefer to interact with their thiophene rings with bared rGO surface, resulting in a conventional face‐on orientation. In these hybrids, beyond critical length of P3HT nanofibers developed onto rGO (>100 nm), an inclination occurs after solvent evaporation, thereby face‐on noninclined fibers change to edge‐on inclined ones. In P3HT/rGO‐f‐TAA supramolecular structures patterned with P3HT short nanofibrils (42–95 nm in length), the orientation of P3HT chains changes from face‐on to edge‐on, originating from strong interactions between hexyl side chains of P3HTs and 2‐thiophene acetic acid functional groups of rGO. Supramolecular structures based on grafted rGO demonstrate a patched‐like morphology composed of flat‐on P3HTs with main backbones perpendicular to substrate. Grafted polythiophenic oligomers onto rGO (rGO‐g‐PDDT and rGO‐g‐PTEt) provoke P3HT backbones to vertically attach to surface and remain perpendicular even after solvent evaporation. Flat‐on orientation acquired for rGO‐g‐PDDT and rGO‐g‐PTEt systems is the best for P3HT chains assembled onto rGO. Face‐on P3HT/rGO hybrids and, subsequently, edge‐on P3HT/rGO‐f‐TAA hybrids also reflect optical and supramolecular donor–acceptor properties based on ultraviolet–visible and photoluminescence analyses. Novel donor–acceptor supramolecules are designed based on regioregular poly(3‐hexylthiophene) (P3HT) and reduced graphene oxide (rGO) functionalized with 2‐thiophene acetic acid and grafted with poly(3‐dodecylthiophene) and poly(3‐thiophene ethanol). Supramolecular structures based on grafted rGO demonstrate a patched‐like morphology composed of flat‐on P3HTs. By grafting rGO with polythiophenic oligomers, the surface patterning, chain orientation, and optical characteristics are improved.