Carbon Counter Electrodes in Dye-Sensitized and Perovskite Solar Cells

Developing highly effective and stable counter electrode (CE) materials to replace rare and expensive noble metals for dye-sensitized and perovskite solar cells (DSC and PSC) is a research hotspot. Carbon materials are identified as the most qualified noble metal-free CEs for the commercialization of the two photovoltaic devices due to their merits of low cost, excellent activity, and superior stability. Herein, carbonaceous CE materials are reviewed extensively with respect to the two devices. For DSC, a classified discussion according to the morphology is presented because electrode properties are closely related to the specific porosity or nanostructure of carbon materials. The pivotal factors influencing the catalytic behavior of carbon CEs are also discussed. For PSC, an overview of the new carbon CE materials is addressed comprehensively. Moreover, the modification techniques to improve the interfacial contact between the perovskite and carbon layers, aiming to enhance the photovoltaic performance, are also demonstrated. Finally, the development directions, main challenges, and coping approaches with respect to the carbon CE in DSC and PSC are stated.