Effect of the rutile content on the photovoltaic performance of the dye-sensitized solar cells composed of mixed-phase TiO2 photoelectrodes

Abstract

The effect of the rutile content on the photovoltaic performance of dye-sensitized solar cells (DSSCs) composed of mixed-phase TiO₂ photoelectrode has been investigated. The mixed-phase TiO₂ particles with varied amounts of rutile, relative to anatase phase, are synthesized by an in situ method where the concentration of sulfate ion is used as a phase-controlling parameter in the formation of TiO₂ using TiCl₄ hydrolysis. The surface area (S_BET) varies from 33 (pure rutile) to 165 (pure anatase) m² g⁻¹. Generally, both the current density (J_sc) and photo-conversion efficiency (η) decrease as the rutile content increases. The incorporation of rod-shaped rutile particles causes low uptake of dye due to the reduced surface area, as well as slow electron transport in less efficiently-stacked structure. However, maximum J_sc (14.63 mA cm⁻²) and η (8.69%) appear when relatively low rutile content (16%) is employed. The reported synergistic effect by the efficient interparticle electron transport from rutile to anatase seems to overbalance the decrease of surface area when small amount of rutile particles is incorporated.