For verifying the influence of donor-acceptor supramolecules on photovoltaic properties, different hybrids were designed and used in organic solar cells. In this respect, reduced graphene oxide (rGO) was functionalization 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 orientation of poly(3-hexylthiophene) (P3HT) assemblies. Face-on, edge-on, and flat-on orientations were detected for assembled P3HTs on rGO and its functionalized and grafted derivatives, respectively. Alteration of P3HT orientation from face-on to flat-on enhanced current density (J(sc)), fill factor (FF), and power conversion efficiency (PCE) and thus J(sc)=7.11 mAcm(-2), FF=47%, and PCE=2.14% were acquired. By adding phenyl-C71-butyric acid methyl ester (PC71BM) to active layers composed of pre-designed P3HT/rGO, P3HT/rGO-f-TAA, P3HT/rGO-g-PDDT, and P3HT/rGO-g-PTEt hybrids, photovoltaic characteristics further improved, demonstrating that supramolecules appropriately mediated in P3HT:PC71BM solar cells. Phase separation was more intensified in best-performing photovoltaic systems. Larger P3HT crystals assembled onto grafted rGOs (95-143 nm) may have acted as convenient templates for the larger and more intensified phase separation in P3HT:PCBM films. The best performances were reached for P3HT:P3HT/rGO-g-PDDT:PCBM (J(sc)=9.45 mAcm(-2), FF=54%, and PCE=3.16%) and P3HT:P3HT/rGO-g-PTEt:PCBM (J(sc)=9.32 mAcm(-2), FF=53%, and PCE=3.11%) photovoltaic systems. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 1877-1889