Conventional and Emerging Counter Electrode Materials for Dye-Sensitized Solar Cells: A Comprehensive Review

Dye-sensitized solar cells (DSSCs) are attractive photovoltaic devices due to their low manufacturing costs, simple processing steps, transparency and compatibility with flexible substrates. The counter electrode (CE) is vital for catalyzing redox reactions, thereby affecting charge-transfer efficiency and overall device performance. While platinum (Pt) remains the standard material for CEs, its high cost, limited availability and long-term chemical stability issues have driven research into more affordable alternatives. This review covers recent developments in both traditional and novel CE materials, including Pt-based compounds, carbon materials, conductive macromolecules, transition metal elements and subsequent composites. It compares their synthesis methods, structural and electrochemical properties, catalytic efficacy and photovoltaic performance. This paper concludes with an overview of recent encounters and future pathways, aiming to foster the progress of effective, durable and cost-saving CEs for next-generation DSSCs.