Anatase TiO2 hollow spheres with small dimension fabricated via a simple preparation method for dye-sensitized solar cells with an ionic liquid electrolyte

The anatase TiO2 hollow spheres with a diameter of approximately 250 nm were synthesized by a chemical template method. Compared to conventional P25 nanocrystalline particles, the TiO2 hollow structured materials not only have a low density, high specific surface areas, and hierarchically porous structures but also exhibit high light-scattering efficiency and fast motion of the charge carriers. A photoelectrode consisting of TiO2 hollow spheres for use in dye-sensitized solar cells (DSSCs) is prepared, and the nanostructure and the performance of DSSCs with an ionic liquid electrolyte are investigated. Improved performance of the DSSCs (Jsc = 8.0 mA cm−2, Voc = 0.732 V, FF = 65%, and η = 3.79%) is obtained compared with the P25 TiO2 nanocrystalline DSSCs (Jsc = 7.25 mA cm−2, Voc = 0.702 V, FF = 59%, η = 2.96%, and measured at 100 mW cm−2, AM 1.5 G). The improved performance is primarily due to the enhanced light scattering by the TiO2 hollow spheres and the highly porous structure of the hollow sphere electrode, allowing the highly viscous non-volatile electrolytes to thoroughly penetrate the electrode. The results show that the structure of the TiO2 hollow sphere photoelectrode can greatly improve the performance of the DSSCs with non-volatile electrolytes.

► Small TiO2 hollow spheres prepared by the template MMA-BA.
► Hollow sphere electrode exhibits high porosity and light scattering property.
► Comparison of the performance of the TiO2 hollow spheres and the P25.
► Better performance with ionic electrolytes due to the special hollow structure.