Surface relief gratings on poly(3-hexylthiophene) and fullerene blends for efficient organic solar cells

The use of periodic submicrometer structures as an efficient light-trapping scheme was investigated for high performance organic solar cells (OSCs) based on poly (3-hexylthiophene) and 1-(3-methoxycarbonyl)-propyl-1-phenyl- (6,6)C-61. The gratings on an active layer are achieved by a soft lithographic approach using photoinduced surface- relief gratings (SRGs) on azo polymer films and poly (dimethylsiloxane) as a master and stamp, respectively. Incident photon to current conversion efficiency and the power conversion efficiency of OSC with gratings increased primarily due to enhanced short circuit current density, indicating that SRGs induce further photon absorption in active layers by increasing the optical path length and light trapping. (C) 2007 American Institute of Physics.