Plasmon enhancement of bulk heterojunction organic photovoltaic devices by electrode modification

The efficiency of photovoltaic devices fabricated from blends of regioregular poly (3-hexylthiophene) and {6,6}-phenyl C-61-butyric acid methylester was improved by introducing a thin Au layer and LiF spacer prior to evaporation of Al contacts onto the polymer blend. Using an optimized Au/LiF/Al electrode gave a 20%-30% improved power efficiency over devices with only LiF/Al for AM1.5 irradiation. The increased efficiency is primarily due to the increased photocurrent, and we present spectroscopic data suggesting that this can be ascribed to plasmon enhancement of the polymer absorption by nanotextured Au. (C) 2008 American Institute of Physics.