Cube-like mixed-phases TiO2 mesocrystalline hollow boxes from in situ topotactic transformation for highly efficient dye-sensitized solar cells

The cube-like TiO₂ mesocrystalline hollow boxes (TiO₂-MHBs) are fabricated by a topotactic transformation method. TiO₂-MHBs consist of one-dimensional nanorod-like rutile TiO₂ combined with anatase TiO₂. The ordering of TiO₂-MHBs is in favor of efficient electron transport. TiO₂-MHBs with mesoporous structure show excellent light scattering performance. Dye-sensitized solar cell with TiO₂-MHBs light scattering overlayer exhibits an 18.3% increment of cell efficiency (9.51%) compared with the TiO₂ nanoparticles film cell (8.04%). The improved photovoltaic performance is attributed to its unique crystallographic property and highly porous structure, which can enhance light scattering capability, quicken electron transport and electrolyte diffusion, and reduce charge recombination.