Plasmonic enhanced multifunctional composite photoanode for highly efficient dye-sensitized solar cells

Dye-sensitized solar cells (DSSCS) were fabricated using different photoanode compositions of P25 TiO2 and hierarchically structured TiO2 microspheres and optimized their performance. DSSCs fabricated with 10% TiO2 microspheres in the composite photoanode exhibited the highest efficiency of 7.17%, while the devices with pristine P25 TiO2 photoanode showed an efficiency of 6.34% under the same illumination conditions of 100 mW cm(-2). Device performance was further optimized by using the plasmonic effect of Ag nanoparticles (AgNPs) with different particle sizes. SEM imaging revealed that the average diameter of the TiO2 microspheres was about 700 nm and consisted of aggregates of smaller TiO2 nanoparticles of diameters 5-15 nm. This unique morphology appears to enhance the light absorption by scattering effect as well as by increasing the specific surface area of the TiO2 photoanode for improved dye adsorption. The average particle size of the Ag nanoparticles confirmed by the Transmittance Electron Microscopy (TEM) measurements was found to be 20 nm (red colour) and 80 nm (blue colour). Optimized DSSCs made with 10 wt% of AgNPs (in TiO2) with red colour and blue colour showed efficiencies of 7.88% and 8.15% respectively under the same illumination conditions. An impressive similar to 29% increase in the overall device efficiency due to the combined effect of hierarchically TiO2 microspheres as well as the plasmonic Ag NPs of blue colour (cluster size 80 nm) in the photoanodes, whereas the overall efficiency enhancement with red-coloured AgNPs of size similar to 20 nm was similar to 24%.