Submicron-scale manipulation of phase separation in organic solar cells

This paper describes a method for controlling the submicron-scale phase separation of poly(3-hexylthiophene) and (6,6)-phenyl-C-61-butyric acid methyl ester in organic solar cells. Using microcontact printing of self-assembled monolayers on the device buffer layer to divide the surface into two regimes having different surface energies, an interdigitated structure aligned vertical to the substrate surface is achieved after spontaneous surface-directed phase separation. The power conversion efficiency increases upon decreasing the grating spacing, reaching 2.47%. The hole mobility increased as a consequence of improved polymer chain ordering, resulting in higher device efficiency, while smaller pattern sizes were used. (c) 2008 American Institute of Physics.