Dual-Function Scattering Layer of Submicrometer-Sized Mesoporous TiO2 Beads for High-Efficiency Dye-Sensitized Solar Cells

Submicrometer-sized (830 +/- 40 nm) mesoporous TiO2 beads are used to form a scattering layer on top of a transparent, 6-mu m-thick, nanocrystalline TiO2 film. According to the Mie theory, the large beads scatter light in the region of 600-800 nm. In addition, the mesoporous structure offers a high surface area, 89.1 m(2) g-(1), which allows high dye loading. The dual functions of light scattering and electrode participation make the mesoporous TiO2 beads superior candidates for the scattering layer in dye-sensitized solar cells. A high efficiency of 8.84% was achieved with the mesoporous beads as a scattering layer, compared with an efficiency of 7.87% for the electrode with the scattering layer of 400-nm TiO2 of similar thickness.