Nanostructured TiO₂ films for dye-sensitized solar cells

A new strategy was attempted to fabricate photoelectrode of dye-sensitized solar cells through a reassembly technique (exfoliation and restacking) to increase solar activity. A random hybridization between exfoliated layered titanate and TiO₂ (anatase) nanoparticles resulted in a 'house-of-cards' structure, which might increase the mesoporosity and surface area of TiO₂ film. In the XRD patterns of the present nanocomposite, no (00 l) peaks could be seen due to the random hybridization between layered titanate and TiO₂ nanosol particles. According to the N₂ adsorption-desorption isotherms, the resulting nanohybrids are fairly porous with a high specific surface area (S_BET=∼190 m²/g, mean pore size=6 nm), which leads to an efficient dye adsorption. A solar energy to electricity conversion efficiency (η) of the present nanocomposite film is about 100 times higher than that of TiO₂ nanoparticle one under the standard AM 1.0 irradiation condition, suggesting that the mesoporous nature of TiO₂ film would play an important role for efficient photovoltaic cell performance.