Blending CoS and Pt for amelioration of electrodeposited transparent counterelectrodes and the efficiency of back-illuminated dye solar cells

Highly efficient and transparent multicomponent catalysts for Dye Solar Cells (DSCs) were obtained by simultaneous electrodeposition of platinum and cobalt-sulfide (Pt:CoS) on conducting glass substrates from a mixture solution of both precursors. At equal charge transfer resistances (R-CT), the superior transparency of electrodeposited (ED) Pt:CoS compared to ED Pt-only and ED CoS-only was attributed to the synergic combination of a very thin CoS layer and a fine dispersion of Pt nanoparticles. The highly catalytic properties of Pt:CoS with less electrodeposited material consumption, carried out at room temperature, can represent a fast and energy saving fabrication process, also compatible with flexible plastic substrates. In fact, DSCs with the ED Pt:CoS counterelectrodes showed the highest power conversion efficiency in back illumination, which is the configuration used for flexible metallic and bifacial DSCs during operation, gaining on average almost 14% and 7% in device efficiency with respect to ED CoS-only and ED Pt-only based cells. These results are important for all applications where transparency represents a key factor (e.g. BIPV, metal based devices) and may also point at blending different precursor solutions as a more general route for electrodeposition of layers with added functionality.