Mechanically Robust Transparent Conducting Electrodes for Flexible Perovskite Solar Cells

Perovskite solar cells (PSCs) offer unique advantage of enabling lightweight and flexible power sources compared to the commercially available rigid wafer-based silicon solar cells, while their power conversion efficiencies are now nearly comparable. To ensure high performance, flexibility and lightweight characteristics in flexible perovskite solar cells and modules, it is essential to develop electrodes that are highly conductive, highly transparent, flexible and thin. In this review, we first highlight important technical metric, figure of merits (FoM), that reflects not only the optical and electrical properties of the transparent electrodes but also their mechanical flexibility. Then, we review recent advancements in transparent conductive electrodes for flexible perovskite solar cells, focusing on various materials and designs including conducting polymers, metal nanowires and meshes, carbon-based nanomaterials, transparent conducting oxides and other novel materials. Lastly, we discuss the challenges and future prospects toward commercialization of flexible perovskite solar modules.