Post-treatment of porous titanium dioxide film with plasmonic compact layer as a photoanode for enhanced dye-sensitized solar cells

Abstract

Mesoporous TiO2 photoanode before dye adsorption was modified with a thin compact layer of plasmonic silver-doped anatase TiO2 (cTiO2-Ag) by a simple dip-coating method followed by thermal decomposition. Post-treatment process significantly enhanced the open-circuit photovoltage and short-circuit photocurrent density, resulting in an increase in the photoelectric conversion efficiency (η) of dye-sensitized solar cell (DSSC). Ag modification increased the optical absorption of dye through the localized surface plasmons and improved the interfacial connection between TiO2 particles for expediting the electron transport, but at the expense of decreasing dye adsorption. There was no appreciable change in the adsorption amount of dye after the formation of cTiO2-Ag on photoanode. The cTiO2-Ag layer could provide an effective approach to enhancing light harvesting due to the plasmonic effect, bridging the pathways for electron transport, and decreasing the charge recombination at fluorinated tin oxide/electrolyte and/or TiO2/electrolyte interfaces, all of which could result in superior photovoltaic performance of DSSC. The η value of DSSC using photoanode with cTiO2-Ag layer could reach as high as 9.45%, far better than that of DSSC using bare photoanode (6.27%).