Comparative performance of single and binary metal selenides in dye-sensitized solar cells

Iron selenide (FeSe₂), cobalt selenide (Co₃Se₄), and iron cobalt selenide (FeCo₂Se₄) have been synthesized via a two-step hydrothermal process. The formation of FeSe₂, Co₃Se₄, and FeCo₂Se₄ has been proven by sample characterization to support their catalytic activity as the counter electrodes for dye-sensitized solar cells (DSSCs). The poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)/propylene carbonate (PC)/1,2-dimethoxyethane (DME)/1-methyl-3-propyl imidazolium iodide (MPII)/sodium iodide (NaI)/iodine (I₂) gel electrolytes were assembled into DSSCs with FeCo₂Se₄, FeSe₂, Co₃Se₄, or platinum (Pt) as the counter electrode. The DSSC with FeCo₂Se₄ counter electrode shows an efficiency of 8.55%, whereas Pt counter electrode shows an efficiency of 7.06%. The highest performance of DSSC achieved with FeCo₂Se₄ can be attributed to its highest surface area and pore volume. Hence, FeCo₂Se₄ can be used as a Pt-free counter electrode for high-performance DSSCs.