Surfactant additives for improved photovoltaic effect of polymer solar cells

We herein report on the photovoltaic (PV) effect of a polymer bulk-heterojunction (BHJ) layer consisting of poly(3-hexylthiophene) : methanofullerene mixed with a surfactant additive. The mixed surfactant is poly(oxyethylene tridecyl ether) (PTE). Excellent performance was achieved by using the surfactant as an additive in the PV layer, thereby increasing the short-circuit current density and fill factor. These increases led to a power conversion efficiency of 4.51 ± 0.16%, which was higher than that (3.89 ± 0.08%) of the reference device without the surfactant. This improvement can be attributed to the increased dissociation efficiency of the bound e–h pairs, which may be due to the oriented PTE surfactant molecules at interfaces between the phase-separated BHJ domains. These results suggest that a PV layer mixed with a PTE surfactant additive is a promising functional composite material for use in polymer PV cells.