Abstract
The effect of using an anodic layer with low density (~ 6x10
cm
) of gold nanorods (GNR) in organic bulk
heterojunction poly(3-hexylthiophene) (P3HT) and phenyl-C
-butyric acid methyl ester (PCBM) solar cells was studied.
GNRs were deposited using several techniques, which produced various densities of GNRs on the anode layer. The
anodic layers were characterized microscopically and spectroscopically. The power conversion efficiency and the short-circuit
current for experimental devices incorporating GNR anodic layer showed an enhancement of up to 18% as
compared to the control device. The results suggest that the electric field in the P3HT:PCBM active layer was increased
by the localized surface plasmon resonances in GNRs. The increase in the electric field enhanced the photo-generation of
excitons in the active layer near the plasmon peak, which improved the short-circuit current and the overall power
conversion efficiency. Interestingly, photovoltaic devices with a low density of GNRs in the anodic layer showed an
increase in the power conversion efficiency that was superior to that of devices with a higher density of GNRs in the
anodic layer. This suggests that although the anodic layer with a higher density of GNRs absorbed more light, part of this
light was confined in the anodic layer itself, and prevented from reaching the active layer of the bulk heterojunction
device. In such cases, the power conversion efficiency was even found to be decreased with respect to the value for the
control device.