  Plasmonic core-shell nanoparticles (PCSNPs) can function as nanoantennas and
improve the efficiency of dye-sensitized solar cells (DSSCs). To achieve
maximum enhancement, the morphology of PCSNPs need to be optimized. Here we
precisely control the morphology of Au@TiO2 PCSNPs and systematically study its
influence on the plasmonic enhancement effect. Enhancement mechanism was found
to vary with the thickness of TiO2 shell. PCSNPs with thinner shell enhance the
current due to plasmonic effect, whereas particles with thicker shell improve
the voltage due to increasing semiconducting character. Wavelength-independent
enhancement in the visible range was observed and attributed to plasmonic
heating effect. PCSNPs with 5-nm shell give highest efficiency enhancement of
23%. Our work provides a new synthesis route for well-controlled Au@TiO2
core-shell nanoparticles and gains insight into the plasmonic enhancement in
DSSCs.
