Dye-sensitized solar cells based on hollow anatase TiO2 spheres prepared by self-transformation method

Dye-sensitized solar cells (DSSCs) are fabricated based on hollow anatase TiO2 (HA-TiO2) spheres synthesized by a chemically induced self-transformation (CIST) strategy using urea as a base catalyst, whose walls are composed of anatase nanocrystals and exhibit hierarchical porosity. TiO2 hollow structured materials not only have low density, high specific surface areas, and hierarchically porous structures, but also exhibit high light-collection efficiency and fast motion of charge carriers. Effects of calcination temperatures on the performance of HA-TiO2 solar cells are investigated and discussed. With increasing calcination temperatures, the light–electricity conversion efficiencies (η) increase. At 600 °C, HA-TiO2 cells reach the highest efficiency. The performances of HA-TiO2 cells are also compared with Degussa P-25 (P25) TiO2 nanoparticle cells at the same film thickness, and their optimal efficiencies at 600 °C are 4.82 and 4.35%, respectively. The enhanced performance of HA-TiO2 cells is due to their high surface area and hierarchically nanoporous structures when compared with the nonporous TiO2 nanoparticles (P25).