Highly efficient overlayer derived from peroxotitanium for dye-sensitized solar cells

Abstract

Low-cost and high-efficiency dye-sensitized solar cells (DSSCs) have attracted intense research attention recently, especially the key component of sensitized titanium dioxide (TiO₂) photoanode. Owing to the short electron diffusion length of sintered TiO₂ nanoparticles and the charge recombination near the FTO substrate, crucial structures of overlayers on the FTO substrate and the whole TiO₂ film have been applied. However, the generally accepted TiCl₄ overlayer cannot work effectively due to its loose structure and the presence of chloride ions. Therefore, researchers are still faced with the challenge of developing new efficient overlayers on TiO₂ photoanodes. In this study, by employing super-pure peroxotitanium solution (PTS), we have succeeded in significantly improving DSSC performance with simple dip coating. The uniform and compact structure of PTS overlayers can be ascribed to a polymerization mechanism. Overlayers derived from TiCl₄, PTS and other materials such as Nb₂O₅, Al₂O₃, SiO₂ or ZrO₂ are probed. Among these coatings, an energy conversion efficiency as high as 7.33% has been achieved by applying PTS overlayers on the FTO substrate and the whole TiO₂ film.