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

Abstract

Hierarchical TiO₂ nanocrystallite aggregates, composed of ∼10 nm nanocrystallites, with a size of ∼500 nm have been synthesized by a microwave assisted method at 150 °C in a short time (∼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.