Building a hybrid nanocomposite assembly of gold nanowires and thienyl-derivative fullerenes to enhance electron transfer in photovoltaics

Abstract

We report the preparation and characterization of a novel nanocomposite assembly comprising metallic gold nanowires (Au NWs) and thienyl-C₆₁-butyric acid methyl ester (ThCBM) fabricated by adsorbing ThCBM groups, via coordinate bonds involving sulfur functionalities, onto the Au(111) surfaces of Au NWs. The ThCBM-adsorbed Au NW nanocomposites displayed clear shifts in the plasmonic absorption band and in the binding energy of the gold relative to the pure gold NWs. A bulk heterojunction solar cell using the ThCBM-adsorbed Au NW nanocomposites displayed a good power conversion efficiency (PCE) of 3.12%, and a short circuit current density and fill factor that were significantly better than those of a reference cell prepared using ThCBM without Au NWs (with a PCE of 2.67%). The electron mobility in an electron-only device prepared using the ThCBM-adsorbed Au NW nanocomposites was significantly higher (by 35% or more) than the electron mobility in a device prepared with pure ThCBM. In conclusion, the hybrid composites proposed here, i.e., ThCBM-adsorbed Au NW nanocomposites, provide a promising approach to improving the performance of bulk heterojunction photovoltaic cells via improved electron transfer through the metallic nanowires as well as by enhanced ordering among the fullerenes assembled along the longitudinal axes of the gold nanowires.