Low temperature growth of hybrid ZnO/TiO2 nano-sculptured foxtail-structures for dye-sensitized solar cells

Abstract

ZnO/TiO₂ nano-sculptured foxtail-structures were fabricated using two sequential low-temperature processes combining hydrothermal growth of ZnO nanorods (NRs) and plasma ion assisted evaporation of crystalline TiO₂ nanostructures. The ZnO NRs were homogeneously covered with a thin layer of anatase TiO₂ nanostructure to form nano-sculptured foxtail-like patterns. Power conversion efficiency of dye-sensitized solar cells made from these hybrid ZnO/TiO₂ structures was improved from 0.3% to 1.8% after using the ZnO/TiO₂ hybrid structure. Measurement using electrochemical impedance spectroscopy and photocurrent decay proved that the hybrid structures have good electron transport capability, because the ZnO NRs can provide a direct pathway for charge transport; the TiO₂ layer can improve charge injection and prevent the formation of Zn²⁺/dye complex (thus reducing the recombination); the hybrid structures can further increase surface area (thus higher dye loading).