Composite electrode of TiO2 particles with different crystal phases and morphology to significantly improve the performance of dye-sensitized solar cells

Abstract

A novel composite electrode containing brookite TiO₂ quasi nanocubes and anatase TiO₂ sea urchin-like microspheres is fabricated for improving the dye-sensitized solar cell's performance. The brookite nanocubes have a mean size of ∼50 nm, and the anatase microspheres with ∼3 μm diameter display hierarchical structures composed of secondary TiO₂ nanoribbons and nanoparticles. An optimal efficiency of 7.09% is obtained from the solar cell fabricated with a composite TiO₂ electrode containing 30 wt% nanocubes and 70 wt% microspheres, with 81% or 30% improvement in the efficiency as compared to the single nanocube or microsphere film-based cell. Those brookite nanocubes in the microsphere film can fill the interspaces of the hierarchical microspheres, which can not only enhance the dye-loading, but also reduce the charge recombination. All these lead to a higher voltage and current, leading to the improved performance of the anatase TiO₂ film-based solar cell.