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.