LAUSR

Via simultaneous grafting and crystallization of regioregular poly(3-hexylthiophene) (P3HT) chains onto the reduced graphene oxide nanosheets, the cake-like P3HT crystalline layers sandwiched the nanosheets and sandG-cakeP3HT nano-hybrids were designed. The P3HT grafts directed the P3HT free-chains to vertically assemble onto the rGO-graft-P3HT and reach a flat-on orientation. Further red-shifting and peak intensification were also detected in respective ultraviolet–visible spectra (A0−2 = 491, A0−1 = 552, and A0−0 = 602 nm) and the conductivities of sandG-cakeP3HT nanostructures ranged in 10.13–10.29 S/cm. The bandgap of sandG-cakeP3HT supramolecules [the highest occupied molecular orbital (HOMO) =−5.37 eV, the lowest unoccupied molecular orbital (LUMO) = −3.48 eV] was 1.89 eV. A huge jump in the improvement of photovoltaic characteristics was achieved by newly developed sandG-cakeP3HT nano-hybrids. The P3HT:sandG-cakeP3HT photovoltaic devices led to the characteristics of 9.81 mA/cm2 (short circuit current density), 55% (fill factor), 0.66 V (open circuit voltage) and 3.56% (efficiency). The addition of phenyl-C71-butyric acid methyl ester (PC71BM) also improved the properties to 11.48 mA/cm2, 60%, 0.67 V and 4.61%. The external quantum efficiency measurements verified the influence of developed donor–acceptor nano-hybrids on the photovoltaic characteristics. The maximum peak values of 72–74% were detected at 560 nm for P3HT:sandG-cakeP3HT:PC71BM devices.