Graphenic nanosheets sandwiched between crystalline cakes of poly(3-hexylthiophene) via simultaneous grafting/crystallization and their applications in active photovoltaic layers

摘要

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 (A(0-2) = 491, A(0-1) = 552, and A(0-0) = 602nm) and the conductivities of sandG-cakeP3HT nanostructures ranged in 10.13-10.29S/cm. The bandgap of sandG-cakeP3HT supramolecules [the highest occupied molecular orbital (HOMO) =-5.37eV, the lowest unoccupied molecular orbital (LUMO) = -3.48eV] was 1.89eV. 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 9.81mA/cm(2) (short circuit current density), 55% (fill factor), 0.66V (open circuit voltage) and 3.56% (efficiency). The addition of phenyl-C71-butyric acid methyl ester (PC71BM) also improved the properties to 11.48mA/cm(2), 60%, 0.67V 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 560nm for P3HT:sandG-cakeP3HT:PC71BM devices.