Unravelling the catalytic activity of copper cobalt oxide - nickel cobalt oxide composites for efficient counter electrode performance in DSSCs

Undoubtedly, the counter electrode (CE) plays a dominant role on the power conversion efficiency (PCE) of Dye Sensitized Solar Cells (DSSCs), as it regenerates the redox couple and responsible for the continuous activity of the device. Yet, the conventional platinum CE is highly expensive and needs to be replaced with equivalent material to achieve low-cost devices. Aiming this we have fabricated DSSCs with Cubic - Copper Cobalt Oxide (C-CCO), Cubic - Nickel Cobalt Oxide (C-NCO) and the composite of C-CCO and C-NCO [i.e C-(CCO/NCO)] as CEs. The Cyclic Voltammetry analysis shows that the minimum peak to peak separation (Epp) value of 0.34V was obtained for C-(CCO/NCO), indicating that the composite shows excellent catalytic activity. Further the charge diffusion coefficient and charge transfer resistance of C-(CCO/NCO) composites significantly favour the DSSCs performance. As our main result, we obtained a maximum PCE of 4.56% for C-(CCO/NCO), whereas the efficiency of C-CCO and C-NCO are 3.66% and 3.71% respectively. The fabricated DSSCs show relatively better performance than contemporary spinel-oxide based DSSCs. The synergetic effect of the composite materials is analysed extensively to understand the improved performance.