Surface passivation by multifunctional carbon dots toward highly efficient and stable inverted perovskite solar cells

Interfacial imperfections between the perovskite layer and the electron transport layer (ETL) in perovskite solar cells (PSCs) can lead to performance loss and negatively influence long-term operational stability. Here, we introduce an interface engineering method to modify the interface between perovskite and ETL by using multifunctional carbon dots (CDs). C = O in the CDs can chelate with the uncoordinated Pb2+ in the perovskite material, inhibit interfacial recombination, and enhance the performance and stability of device. In addition, –OH in CDs forms hydrogen bonds with I− and organic cation in perovskite, inhibiting light-induced I2 release and organic cation volatilization, causing irreversible degradation of perovskite films, thereby enhancing the long-term operational stability of PSCs. Consequently, we achieve the champion inverted device with an efficiency of 24.02%. The CDs-treated PSCs exhibit high operational stability, and the maximum power point tracking only attenuates by 12.5% after 1000 h. Interfacial modification engineering supported by multifunctional quantum dots can accelerate the road to stable PSCs.