Fabrication of Deformed TiO2 Aggregate as Photoanode in Dye-Sensitized Solar Cells

The special structure of deformed TiO
₂
aggregate composed of connected nanoparticles was synthesized by the sol-gel method and hydrothermal processes with triblock copolymer as a template. The preliminary experiment of dye-sensitized solar cells (DSSCs) with deformed TiO
₂
aggregate as a photoanode was investigated. Field emission scanning electron microscopy reveals that the deformed TiO
₂
aggregate has a mesoporous structure, and its particle diameters are approximately 300-600 nm. Due to these structure characteristics, the deformed TiO
₂
aggregate processes enhanced light harvesting and a larger amount of dye loading. An overall conversion efficiency of DSSCs with deformed TiO
₂
aggregate as a photoanode is 3.82% under illumination of simulated AM 1.5G solar light (100 mW·cm
^-2
), which is higher than that the DSSCs fabricated from commercial P25 (2.58%) as a photoanode with the same thickness and processing procedures. In addition, electrochemical impedance spectroscopy (EIS) was performed to investigate electronic processes in DSSCs, and the results showed that deformed TiO
₂
aggregate possesses higher electron lifetime than that of P25. The results implied that the deformed TiO
₂
aggregate was composed of partially oriented attachment of primary particles and the deformed TiO
₂
aggregate connected with each other to avoid existing large voids between the aggregates.