Enhanced performance for dye-sensitized solar cells based on spherical TiO2 nanorod-aggregate light-scattering layer

A new bilayer-structured photoelectrode film with spherical TiO2 nanorod aggregates as a light-scattering overlayer and nanocrystalline TiO2 as an underlayer is fabricated and studied with the aim of improving energy conversion efficiency in dye-sensitized solar cells (DSSCs). An overall energy conversion efficiency of 6.10% and a short-circuit photocurrent density of 18.47 mA cm(-2) are achieved by introducing a spherical TiO2 nanorod-aggregate light-scattering layer. These are respectively 37.1% and 42.6% higher than those of a DSSC using a conventional 200 nm-diameter solid TiO2 particle light-scattering layer. These improvements are attributed to the spherical TiO2 nanorod-aggregate overlayer, which has a large surface area for sufficient dye adsorption, sub-micrometer size for efficient light scattering, and lower surface state traps, allowing a longer exciton lifetime. (C) 2012 Elsevier B.V. All rights reserved.