A topotactic tailored synthesis of waxberry-like mixed-phase TiO2hollow spheres for dye-sensitized solar cells

The waxberry-like mixed-phase TiO2hollow microstructures (WMTHMs) are controllably prepared viaa topotactic synthetic method, involving the synthesis of monodispersed CaTiO3precursors by a solvothermal method and subsequently transforming them into TiO2through a Na2EDTA-assisted ion-exchange process. The ratio of anatase-rutile is adjustable, and the two phases are connected well with each other. WMTHMs are composed of radially aligned nanorods, speeding up the electron transport. The optimum WMTHMs sample shows a specific surface area of 68.05 m2/g and exhibits an excellent light scattering capacity. The cell based on WMTHMs light scattering layer obtained an optimal efficiency of 9.12%. The improvement of cell efficiency is mainly attributed to the high specific surface area, the efficient light scattering, the appropriate ratio of anatase-rutile, the staggered bandgap structure, and the convenient one-dimensional electron transport channel.