Rapid construction of TiO2 aggregates using microwave assisted synthesis and its application for dye-sensitized solar cells

Hierarchical TiO2 nanocrystallite aggregates, composed of similar to 10 nm nanocrystallites, with a size of similar to 500 nm have been synthesized by a microwave assisted method at 150 degrees C in a short time (similar to 10 minutes) as the photoanode of dye-sensitized solar cells (DSCs). Ethanol and TiCl4 are selected as the solvent and titanium precursor, respectively. The rapid heating rate and superheating/hot spots of the reaction system under microwave irradiation result in a large amount of nuclei instantly, which leads to the formation of a great deal of clusters. Moreover, the clusters that grow up rapidly are assembled into TiO2 nanocrystallite aggregates. The TiO2 aggregates show better light scattering property, larger specific surface area and higher dye-loading compared to the commercial P25 TiO2 nanoparticles. In comparison with DSC based P25 photoanode, the short current density (J(sc)) and dye-loading of DSC based the as-synthesized TiO2 aggregates photoanode increase by 33% and 62%, respectively. As a result, the PCE of the DSC is up to 7.64%, and the TiO2 aggregates obtained by microwave assisted synthesis are a promising and potential candidate for DSCs.