Gold Nanorods Incorporated Cathode for Better Performance of Polymer Solar Cells

The effect of inserting low density of gold nanorods in the metallic rear electrode of polymer solar cells on their performance was studied. Gold nanorods were introduced by spin-coating their aqueous solution directly on top of the poly(3-hexylthiophene-2,5diyl):[6,6]-phenyl-C-61-butyric-acid-methyl-ester layer. The resulting devices showed a 5% increase in the short circuit current that leads to a 14% enhancement in the power conversion efficiency. Investigation on the photocurrent spectral response of devices with/without gold nanorods revealed that incorporating the rods helped in enhancing the devices photogenerated current near the plasmonic absorption modes of the rods. The enhancement in the devices efficiency is related to the increase in their absorptivity due to the far-field and near-field effect of localized surface plasmon resonance induced by the presence of the rods in the interface between the photoactive layer and the metallic rear electrode.