Effects of Plasmonic Nanoparticle Incorporation on Electrodynamics and Photovoltaic Performance of Dye Sensitized Solar Cells

Incorporation of plasmonic nanoparticles (NPs) has been considered recently to increase the absorption efficiency and/or the photocurrent of dye sensitized solar cells (DSSCs). However, metal NPs introduced in DSSCs make direct contact with iodide/triiodide-based liquid electrolyte, creating several problems such as recombination of charge-carriers, back reaction of photogenerated carriers, and corrosion of introduced metal NPs. For freshly prepared cells, charge-carrier recombination has been assumed as the principal process affecting the overall efficiency on DSSs. In this paper, through detailed optical and electrical characterization of gold nano-particle-incorporated DSSCs and utilization of total electron density model, we demonstrate that the common perception that bare Au nanoparticles (NPs) act as recombination or back reactions centers cannot explain the photovoltaic behaviors of plasmonic DSSCs fully. Introduced plasmonic nanoparticles reduce electron injection efficiency in DSSCs, keeping the electron collection efficiency unchanged. Reduction of electron injection efficiency in plasmonic DSSCs is associated with an upward shift of the conduction band due to Au nanoparticle incorporation.