Boosting charge transfer with MoS2-grafted MXene interlayers for high-efficiency all-inorganic CsPbBr3 perovskite solar cells with an ultrahigh voltage of 1.701 V

Controlling the interface energy level and simultaneously passivating the surface defects of perovskite films are crucial for improving the efficiency and stability of perovskite solar cells (PSCs). In this study, two-dimensional MXene nanoflakes grafted with MoS2 quantum dots (QD) are utilized as multifunctional interlayers at the interface of perovskite/carbon in all-inorganic CsPbBr3 PSCs, aiming to enhance their performance and stability. MoS2 QDs are grafted onto the surface of MXene to use the unsaturated S atoms at the edge of MoS2 to passivate the under-coordinated Pb2+ in perovskite films and reduce the interface charge recombination. The MoS2-grafted MXene interlayer can also tune the energy level of perovskite films and provide an efficient pathway for hole transfer, thereby reducing open-circuit voltage (Voc) deficit and improving device performance. Moreover, the ion diffusion from the perovsikte layer to the carbon electrode is significantly suppressed due to the passivation of perovskite interface defects and the formation of isolation layers by the MoS2-grafted MXene interlayers. As a result, the optimized device exhibits a champion efficiency of 10.70% with an ultrahigh Voc of 1.701 V and significantly improved stability under persistent light irradiation and humidity (80%) for a remarkable 50 day period.