Carbon Dots in Perovskite Solar Cells: Properties, Applications, and Perspectives

Perovskite solar cells (PSCs) have attracted substantial research interest owing to their flexible fabrication, high efficiency, and low cost. Currently, the power conversion efficiency (PCE) of PSCs has reached 25.7%, meeting the requirements for commercialization. In recent years, as a novel type of carbon nanomaterial, carbon dots (CDs) with abundant and tunable surface functional groups have shown great potential in regulating the efficiency and stability of PSCs because of their tunable photovoltaic properties, high photochemical stability, and energy down-shift properties. These CDs not only modify the interface of PSCs to control their energy level structure but also induce the growth of perovskite crystals to improve crystal quality, ultimately improving the efficiency and stability of PSCs. This review systematically summarizes the photoelectric properties of CDs and their application progress in PSCs as an active layer dopant, electron transport layer, hole transport layer, interface modification layer, and energy down-shift material after briefly introducing the structures and types of PSCs. Finally, the existing problems and challenges of CDs applied in PSCs are pointed out; specific solutions are proposed; and the future development prospects are presented.