Nano-TiO2 for Solar Cells and Photocatalytic Water Splitting: Scientific and Technological Challenges for Commercialization

ABSTRACT

Nanosized titanium dioxide (nano-TiO₂) particles are used in diverse products and devices, including photocatalytic water splitting and solar cells whose successful commercialization is still facing scientific and technological challenges.

Particularly, dye-sensitized solar cells (DSSCs) have recently attracted a lot of attention. The number of papers and patents published in this area has grown exponentially over the last ten years. However, at the present, commercial devices are of small sizes and produced in limited quantities, thus addressing niche markets. Research efforts have largely focused on the optimization of the dye, but the TiO₂ nanocrystalline electrode itself also needs to be optimized. It has been shown that particle size and shape, crystallinity, surface morphology and chemistry of the TiO₂ material are key parameters to be controlled for enhanced performance of the cell. This article gives an overview of the state-of-the-art on nano-TiO₂ for applications in photocatalytic water splitting and, more specifically, in DSSCs. After a brief analysis of the commercial perspectives of DSSCs and of the remaining challenges for their successful commercialization, our approach to the control of the nano-TiO₂ surface chemistry for improvement of the DSSC performance is briefly introduced.