Bilayer films using broadband nanoparticles and mesoporous TiO2 for high efficient dye sensitized solar cells

The improvement of the power-conversion efficiency of dye-sensitized solar cells (DSCs) has slowed down in recent years due to limited light absorption of the dyes in the near-infrared region. In this study, we present a novel strategy that uses ultra-broadband core–shell Ag@TiO 2 nanoparticles and mesoporous TiO 2 particles to improve light absorption and reduce charge recombination in DSCs. The effect of the concentration of nanoparticles on both photovoltaic performance and charge recombination is studied. The results show that Ag@TiO 2 nanoparticles can significantly improve the short-circuit current of DSCs and reduce the charge-transfer resistance at the TiO 2 -dye/electrolyte interface. These are key factors to achieve high power-conversion efficiency. A power-conversion efficiency of 8.34% is achieved by integrating core–shell NPs (0.6 wt%) with pure P25 TiO 2 particles. This efficiency can be improved further (to 10.02%) by depositing a layer of mesoporous TiO 2 particles, which increases the propagation distance of incoming light. The good interconnection between the TiO 2 crystals of mesoporous particles and the faceted nanocrystal surface enhance electron transport . This work shows a new route to speed-up the transfer of photo-generated carriers, and to split electron-hole pairs more efficiently.