Synergistic plasmonic effects of metal nanoparticle-decorated PEGylated graphene oxides in polymer solar cells.

Metal nanostructures that trigger plasmonic near-field effects are often incorporated in organic photovoltaic devices (OPVs) to improve their light-harvesting ability. These nanostructures usually can be positioned in two different locations in a device: (i) within the photon absorption layers and (ii) at the interfaces between the active layer and the metal electrodes. In this study, we developed amphiphilic gold nanoparticles (Au NPs) for use in dual plasmonic nanostructures within OPVs. We employed graphene oxide as the template to anchor the Au NPs, thereby avoiding their aggregation. Furthermore, we added poly(ethylene glycol) (PEG) bis(amine) to the synthesis medium to improve the solubility of the nanocomposites, such that they could be dispersed well in water and in several organic solvents. Accordingly, we could incorporate the PEGylated Au NP/graphene oxides readily into both the buffer layer and photoactive layer of OPVs, which, as a result, exhibited obvious enhancements in their photocurrents and overall device efficiencies. Moreover, we observed different spectral enhancement regions when we positioned the nanocomposites at different locations, reflecting the different dielectric environments surrounding the NPs; this unexpected behavior should assist in enhancing the broadband absorption of solar irradiation.