Improved photoelectric conversion efficiency from titanium oxide-coupled tin oxide nanoparticles formed in flame

The charge losses as a result of recombination to redox electrolyte and dye cation make tin oxide (SnO₂)-based dye-sensitized solar cells (DSSCs) particularly inferior when compared with its titanium oxide (TiO ₂) counterpart. In this article, TiO₂ nanocrystal is sealed in SnO₂ by a modified flame spray pyrolysis (FSP) approach and the recombination losses to dye cation of SnO₂ photoanode are effectively suppressed due to the negatively shifted Fermi level with the formation of bandedge-engineered core/shell structure. The fabricated TiO ₂@SnO₂ (TSN)-device shows an open circuit voltage of 0.59 V and an efficiency of 3.82%, significantly better than those of the TiO ₂-, and SnO₂-DSSCs devices. After surface modification, the conversion efficiency could be further improved to 7.87% while the open circuit voltage reaches 0.70 V. The higher efficiency of the TSN-based device is attributed to the enhanced electron injection arising from decreased interfacial charge recombination losses and improved electron transport. This strategy renders a new concept for further improvement of photovoltaic performance by engineering the dynamics of electron transport and recombination in DSSCs.