Pt-free, cost-effective and efficient counter electrode with carbon nanotube yarn for solid-state fiber dye-sensitized solar cells

Fiber-shaped solar cells have attracted significant attention for their potential applications in portable and wearable electronics. Developing highly efficient and stable counter electrodes (CEs) to replace rare and expensive noble metals in dye-sensitized solar cells (DSSCs) is a research challenge. The low cost, excellent activity, and stability of carbon materials make them the most qualified noble-metal-free CEs for the commercialization of photovoltaic devices. In this study, we incorporated a carbon nanotube yarn (CNTY) as a CE for efficient and stable solid-state fiber-shaped DSSCs. After device optimization, the power conversion efficiency with the CNTY fiber-shaped DSSCs was approximately 4.00%, which is comparable to that of devices with platinum electrodes (2.64%). The superior mechanical property and performance stability after repeated bending, cleaning, and high output voltage for in-series connection suggest that the proposed CNTY fiber-shaped DSSCs may find applications as flexible power sources in next-generation flexible/wearable fiber electronics and energy textiles.