3D TiO2/ZnO composite nanospheres as an excellent electron transport anode for efficient dye-sensitized solar cells

Abstract

The present study aimed to develop a high electron lifetime (τ_r) and low transit time (τ_d) photoanode material for dye sensitized solar cells (DSSCs). An innovative material structure, a TiO₂/ZnO composite oxide hierarchical nanosphere, was synthesized by a two-step facile hydrothermal method. This composite oxide comprised 3D urchin-like TiO₂ nanospheres and 1D ZnO nanospindles (ULTZ). The ZnO nanospindles were assembled onto the surface of the 3D urchin-like TiO₂ in the hydrothermal process second step. A series of ULTZs made with different growth times were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The DSSCs based on the ULTZs exhibited much higher photoelectric properties and the energy conversion efficiency was 8.78%, which indicated a 30% increase in the conversion efficiency compared to those of the P25 electrode (6.79%); the great improvements of photoelectric properties and energy conversion efficiency for ULTZs based DSSCs were mainly attributed to the superior electronic transmission characteristics.