Effect of Gold Nanoparticle Distribution in TiO on the Optical and Electrical Characteristics of Dye-Sensitized Solar Cells.

Photoanodes comprising Au nanoparticles (GNPs) and thin TiO layers with a stacked structure were fabricated by repeating the application of TiO paste and GNP solutions on conductive glass to vary the distribution of GNPs in the TiO layer. The plasmon-enhanced characteristics of dye-sensitized solar cells (DSSCs) with such photoanodes were investigated. Both the absorption of the TiO layer and the performance of the DSSC are found to be most increased by plasmonic enhancement when GNPs are concentrated near the position in the TiO layer, which is the penetration depth of the incident light of wavelength corresponding to the maximum absorption of the N719 dye (~ 520 nm). When a GNP layer with a relatively high density of 1.3 μg/cm density was formed at its position, and two GNP layers with a relatively low density of 0.65 μg/cm were formed near the front side of the incident light, the short-circuit current density (Jsc) and energy conversion efficiency (η) of the DSSC were found to be 10.8 mA/cm and 5.0%, increases of 15 and 11%, respectively, compared with those of the DSSC without GNPs. Our work suggests that optimization of the distribution of GNPs in the TiO layer is very important for improving the performance of DSSCs fabricated by utilizing GNPs.