Ordered Mesoporous SnO₂−Based Photoanodes for High-Performance Dye-Sensitized Solar Cells

Ordered mesoporous SnO₂ with three-dimensional bicontinuous cubic mesostructure, high surface area, and crystalline frameworks was synthesized by the solvent-free infiltration of tin precursor in KIT-6 silica template and employed as a photoanode in dye-sensitized solar cells (DSSCs). It is shown that coating an ultrathin TiO₂ or Al₂O₃ layer on mesoporous SnO₂ photoanode greatly improves the open-circuit voltage, short-circuit current, and fill factor, leading to more than a 3-fold improvement in the energy conversion efficiency. The superior photovoltaic performance of surface modified mesoporous SnO₂ photoanode is mainly the result of inhibited electron recombination caused by passivation of reactive surface states and increased dye loading. Control cells fabricated with conventional nanoparticle SnO₂/TiO₂ photoanode exhibit a similar trend but with about 30% lower energy conversion efficiency, which is mainly because of limitations due to low dye loading and poor light scattering.