Preparation of hierarchical TiO2 microspheres for enhancing photocurrent of dye sensitized solar cells

Hierarchically structured TiO2 microspheres were prepared at a low temperature by combining a sol-gel process with a solvothermal route and characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. Results indicate that the phase structure of the as-prepared TiO2 products undergoes a transformation, which changes from amorphous microspheres with a smooth surface in the sol-gel process to hierarchical anatase ones consisting of nanocrystallines after the solvothermal treatment. The hierarchical anatase TiO2 microsphere shows large surface areas and good light scattering effects as the photoelectrodes for dye sensitized solar cells (DSSCs). DSSCs based on TiO2 microspheres exhibit an improvement power conversion efficiency of 6.58% and a high short current density of 13.83 mA/cm2 as compared to the commercial P25 based DSSCs with a power conversion efficiency of 4.94% and a high short current density of 10.28 mA/cm2.