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

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.