Microsphere assembly of TiO2 mesoporous nanosheets with highly exposed (101) facets and application in a light-trapping quasi-solid-state dye-sensitized solar cell

Abstract

The morphology of nano-titania has a significant effect on the photoelectric properties of dye-sensitized solar cells. In this study, microsphere assembly of a TiO₂ mesoporous nanosheet constructed by nanocuboids was conducted via a simple hydrothermal process. The XRD pattern indicated that the hierarchical mesoporous microspheres are anatase phase with decreased (004) peaks. Raman spectrum shows enhanced E_g peaks at 143 and 638 cm⁻¹ caused by the symmetric stretching vibration of O–Ti–O of the (101) crystalline facet in anatase TiO₂. FESEM and TEM images show that well monodispersed TiO₂ microspheres with a diameter of 2 μm are assembled by TiO₂ mesoporous nanosheets with exposed (101) facets. The oriented attachment of TiO₂ nanocuboids along the (101) direction leads to the formation of mesoporous titania nanosheets. The UV-Vis spectrum shows that the mesoporous TiO₂ nanosheets have high scattering ability and light absorption by dye. Quasi-solid-state dye-sensitized solar cells that incorporate these microspheres into the top scattering layers exhibit a prominent improvement in the power conversion efficiency of 7.51%, which shows a 45.8% increase in the overall conversion efficiency when compared with the spine hierarchical TiO₂ microspheres (5.15%). There is the potential application for microsphere assembly of mesoporous TiO₂ nanosheets in quasi-solid-state dye-sensitized solar cells with excellent stability.