Cobalt-based electrolytes for dye-sensitized solar cells: Recent advances towards stable devices

Abstract

Redox mediators based on cobalt complexes allowed dye-sensitized solar cells (DSCs)to achieve efficiencies exceeding 14%, thus challenging the emerging class of perovskite solarcells. Unfortunately, cobalt-based electrolytes demonstrate much lower long-term stabilitytrends if compared to the traditional iodide/triiodide redox couple. In view of the large-scalecommercialization of cobalt-based DSCs, the scientific community has recently proposed variousapproaches and materials to increase the stability of these devices, which comprise gelling agents,crosslinked polymeric matrices and mixtures of solvents (including water). This review summarizesthe most significant advances recently focused towards this direction, also suggesting some intriguingway to fabricate third-generation cobalt-based photoelectrochemical devices stable over time.