Nickel Selenide Nanoparticles as a Cheap Alternative for Pt-Counter Electrode in Dye-Sensitized Solar Cells

Colloidal nickel selenide nanocrystals (NCs) of two different compositions i.e., Ni₃Se₂ and Ni₃Se₄, where one is Ni-rich while another is Se-rich are synthesized using the hot injection method by merely changing the injection and growth temperature while keeping the rest of the reaction conditions like solvent, ligands, amount of precursors and reaction time identical. These nanocrystals exhibit electrocatalytic activity in the reduction of triiodide (I^-₃) to iodide (3I^-), therefore employed as counter electrodes (CE) in dye-sensitized solar cells (DSCs). The DSC based on nickel selenides displays an efficiency of 6.4%, comparable to the Pt-based cells prepared by us.