Preparation of smooth surface TiO₂ photoanode for high energy conversion efficiency in dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) based on a TiO₂ photoanode have been considered as an alternative source in the field of renewable energy resources. In DSSCs, photoanode plays a key role to achieve excellent photo-to-electric conversion efficiency. The surface morphology, surface area, TiO₂ crystal phase, and the dispersion of TiO₂ nanoparticles are the most important factors influencing the properties of a photoanode. The smooth TiO₂ surface morphology of the photoanode indicates closely packed arrangement of TiO₂ particles which enhance the light harvesting efficiency of the cell. In this paper, a smooth TiO ₂ photoanode has been successfully prepared using a well-dispersed anatase TiO₂ nanosol via a simple hydrothermal process. The above TiO₂ photoanode was then compared with the photoanode made from commercial TiO₂ nanoparticle pastes. The morphological and structural analyses of both the aforementioned photoanodes were comprehensively characterized by scanning electron microscopy and X-ray diffraction analysis. The DSSC fabricated by using a-TiO₂ nanosol-based photoelectrode exhibited an overall light conversion efficiency of 7.20% and a short-circuit current density of 13.34 mA cm^-2, which was significantly higher than those of the DSSCs with the TiO₂ nanoparticles-based electrodes.