Currently, organic photovoltaics are not a viable renewable source of energy in comparison to silicon solar panels because of its low efficiencies, due to its disorganized morphology which leads to charge recombination and an overall loss of energy production. It was hypothesized that simultaneously organizing the morphology and increasing the area of the active sites for exciton dissociation would improve overall efficiency.
Our synthesized gold-graphene (AuRGO) was dispersed in sulfonated polystyrene (PSS) and added to the active layer. We also blended polymethylmethacrylate (PMMA) with graphene, which was then incorporated into the active layer. AFM imaging demonstrated that the polymers self-assembled into column structures. Additionally, the AuRGO showed an affinity for both P3HT and the PSS, migrating to the interfaces. Solar simulation results show that both polymer-graphene blends demonstrated enhanced current and efficiency.
The self-organization helped increase the efficiency of both samples, but the AuRGO/PSS had a greater efficiency improvement over the cG/PMMA by 170%. This increase is attributed to the fact that since the AuRGO migrated to the interfaces, the sheet acts as a bridge that improved the electron flow through a connection between the electron donating and accepting materials, improving exciton dissociation and charge transport, and therefore efficiency.