Effect of ZnO decoration on the photovoltaic performance of TiO₂ based dye sensitized solar cells

Highlights: • Various ZnO morphologies coated TiO₂ photoanodes are formed and applied to DSSCs. • The effect of photoanode morphology on performance of DSSCs was studied. • ZnO NRs@TiO₂ electrode provides more dye absorption and fast transfer pathway. • The η of DSSC with ZnO NRs@TiO₂ is increased over fourfold than other DSSCs. - Abstract: ZnO nanoparticles and one-dimensional vertically aligned ZnO nanorods were grown on the TiO₂ layers in the photoanodes via the hydrothermal method at 60 and 90 °C, respectively. The effect of ZnO decoration on the photovoltaic performance of TiO₂ based dye sensitized solar cells (DSSCs) was investigated. The morphologies, crystalline structures and optical properties of the synthesized ZnO nanoparticles and ZnO nanorods were characterized by field-emission scanning electron microscope, X-ray diffractometer and photoluminescence spectroscopy, respectively. The photocurrent–voltage curves of the fabricated DSSCs showed that the ZnO nanorods decorated DSSCs exhibited better photovoltaic performance than the ZnO nanoparticles decorated DSSCs. The improved performance of the ZnO nanorods decorated DSSCs can be ascribed to the fact that the vertically aligned ZnO nanorods provide high specific surface area for dye adsorption and the efficient pathway for electron transportation