High-Performance Cobalt Selenide and Nickel Selenide Nanocomposite Counter Electrode for Both Iodide/Triiodide and Cobalt(II/III)Redox Couples in Dye-Sensitized Solar Cells

The nanocomposites of cobalt selenide and nickel selenide(Co_(0.85)Se/Ni_(0.85)Se)were successfully fabricated on FTO glass by a facile co-electrodeposition method at ambient temperature.Nanocomposite films were used as elec-trocatalysts in dye-sensitized solar cell counter electrodes for regeneration of both iodide/triiodide and cobalt(II/III)redox couples.Co_(0.85)Se/Ni_(0.85)Se were mainly composed of nanoflakes and nanoparticles.It is noted that such nanostructure generated by nanoparticles embedded with 2D nanoflakes led to high active sites and was accessible to cobalt(II/III)electrolyte,delivering better catalytic activity for the reduction of larger volume cobalt(II/III).As a result,for cobalt(II/III)electrolyte,the Co_(0.85)Se/Ni_(0.85)Se based dye-sensitized solar cell performed significantly im-proved efficiency than that of Pt and Co_(0.85)Se.Meanwhile,the Co_(0.85)Se/Ni_(0.85)Se based dye-sensitized solar cell held comparable energy conversion efficiency to that of Pt and Co_(0.85)Se for iodide/triiodide electrolyte.