Plasmonic Organic Photovoltaic Devices on Transparent Carbon Nanotube Films

We have explored the effect of Au-nanoparticle (NP)-induced surface plasmons on the performance of polymer-fullerene photovoltaic devices utilizing single-walled carbon-nanotube (SWNT) films as the transparent electrode for hole collection. The Au NPs were produced by ultrafast laser ablation in liquids and were incorporated on the devices in a SWNT/poly(3,4-ethylene-dioxythiophene):poly(4-styrenesulfonate)/NP/poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester/Al configuration. The NP incorporation leads to a power conversion efficiency improvement of 70%. This increase can be attributed to the improved photocurrent and fill factor due to an enhanced exciton generation rate of the photoactive layer caused by localized surface-plasmon resonances of the conduction electrons within the NPs. This argument was supported by the combinatorial study of the optical properties of the NPs and the photon-to-electron conversion efficiency of the devices.