Fluorine Functionalized MXene QDs for Near-Record-Efficiency CsPbI3 Solar Cell with High Open-Circuit Voltage

Abstract

CsPbI₃ inorganic perovskites have attracted significant attention due to their desirable bandgap for tandem solar cells and excellent thermal stability. However, CsPbI₃ perovskite solar cells (PSCs) still exhibit low efficiency and high energy loss due to nonradiative recombination. Herein, functionalized Ti₃C₂F_x quantum dots (QDs) are prepared and selected as interface passivators to enhance the performance of CsPbI₃ PSCs. The systematic experimental results reveal that Ti₃C₂F_x QDs serve as effective passivators mainly in three aspects: 1) p-type Ti₃C₂F_x QDs can tune the energy level of perovskite films and provide an efficient pathway for hole transfer; 2) Ti₃C₂F_x QDs can effectively passivate defects and reduce interfacial nonradiative recombination, and 3) Ti₃C₂F_x QDs form a barrier layer to prevent water invasion and improve the stability of CsPbI₃ PSCs. Consequently, the champion CsPbI₃ PSC with Ti₃C₂F_x QDs treatment exhibits an excellent efficiency of 20.44% with a high open-circuit voltage of 1.22 V. Meanwhile, the corresponding device without encapsulation retained 93% of its initial efficiency after 600 h of storage in ambient air.