Nanosheet-based hierarchical ZnO structure decorated with TiO sub(2) particles for enhanced performance in dye-sensitized solar cell

A hierarchical ZnO structure assembled by nanosheets was prepared through a low temperature chemical bath deposition and a growing-melting mechanism was proposed to elucidate the shape evolution. Afterwards, a poly (vinylpyrrolidone) (PVP) assisted hydrothermal method was adopted to decorate TiO sub(2) particles onto the ZnO structure. When used in dye-sensitized solar cells, the device employing the hybrid ZnO/TiO sub(2) photoanode exhibited improved short-circuit current density (J sub(sc)), open-circuit voltage (V sub(oc)) and filling factor (FF), which resulted in a higher power conversion efficiency (PCE) of 3.60% in comparison to 1.96% from the pure ZnO cell. Based on the investigation of UV-vis absorption and diffuse-reflection spectra, Mott-Schottky analysis, electronic impedance spectra (EIS) and incident monochromatic photo-to-electron conversion efficiency (IPCE), the effect of TiO sub(2) modification on the photovoltage performances of the ZnO sheet-based hierarchical structures was studied in detail.