A Facile Approach to Construct Multiple Structured ZnO Crystals by Trisodium Citrate-Assisted Hydrothermal Growth Toward Performance Enhancement of Dye-Sensitized Solar Cells

ZnO crystals with different morphologies including microrods, hierarchical microspheres, and hollow microspheres were fabricated via a simple and low-cost trisodium citrate-assisted hydrothermal method. The related morphologies and structures of the as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results showed that trisodium citrate played a crucial role as a capping agent in the formation of ZnO nanostructures, and accordingly, the rational growth mechanism was proposed. The obtained ZnO nanostructures were used as a photoanode in dye-sensitized solar cells (DSSC), and the photovoltaic results demonstrated that the short circuit current density and the overall conversion efficiency of the hierarchical rnicrospheres based DSSC were 6.05 mA cm(-2) and 1.42%, respectively, which were largely improved compared with those of the microrods based DSSC (1.92 mA cm(-2) and 0.41%) and hollow microspheres based DSSC (3.37 mA cm(-2) and 0.79%). The significant improvement for the former was attributed to the sufficient dye loading and efficient light scattering.