Long-term Stability of Conducting Polymers in Iodine/iodide Electrolytes: Beyond Conventional Platinum Catalysts

One of the primary obstacles to the commercialization of dye-sensitized solar cells (DSSCs) is the improvement of their long-term stability. Here, we report greatly improved long-term stability of DSSCs, which have PEDOT:FTS polymer as a counter electrode. DSSCs with this PEDOT:FTS film demonstrate slightly lower power conversion efficiency of 8.1% under standard conditions (AM 1.5 G, 100 mWcm⁻²) compared to the ∼9.1% efficiency of Pt, using an electrolyte with iodine/iodide, which is the most popular redox shuttle. However, we demonstrate that this conducting polymer counter electrode facilitates the fabrication of solar cells with greatly improved long-term stability compared to Pt-based ones after exposure to electrolyte soaking conditions. Various electrochemical analyses were performed to evaluate the enhanced durability of PEDOT:FTS polymer in the highly corrosive iodine/iodide electrolyte under a continuous redox reaction condition.