Highly Efficient and ITO-Free Flexible Counter Electrodes Employing Novel Copper Based Redox Shuttles in Dye-Sensitized Solar Cells

We present results on highly efficient and indium tin oxide (ITO) free counter electrodes. These were fabricated via low-temperature based highly conductive single walled carbon nanotubes (SWCNTs), which are printed over a flexible polymer substrate. The printed nanotubes served as an alternative to both the traditional conducting (ITO) and catalyst (Pt) layers of the counter electrode. The SWCNT or Pt based flexible counter electrodes were assembled with the photoelectrodes to produce dye-sensitized solar cells (DSSCs) employing electrolytes based on novel copper redox shuttles. The performance of the fabricated solar cells were investigated through J-V curves and electrochemical impedance spectroscopy (EIS). The SWCNT-based flexible counter electrodes exhibited excellent compatibility and superior catalytic activity with copper electrolytes compared to flexible Pt catalyst based counter electrodes fabricated on flexible ITO-PEN substrates. Our results suggest that SWCNT can be a potential alternative for realizing efficient flexible dye-sensitized solar cells when fabricated with electrolytes based on copper redox shuttles.