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 (TiO2) 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 TiO2@SnO2 (TSN)-device shows an open circuit voltage of 0.59 V and an efficiency of 3.82%, significantly better than those of the TiO2-, 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. (C) 2014 Elsevier B.V. All rights reserved.