Fluorine Functionalized MXene QDs for Near‐Record‐Efficiency CsPbI<sub>3</sub> Solar Cell with High Open‐Circuit Voltage
Dongfang Xu, Tong Li, Yu Han, Xuexia He, Shaomin Yang, Yuhang Che, Jie Xu, Hong Zou, Xi Guo, Jungang Wang, Xuruo Lei, Zhike Liu
Abstract
Abstract CsPbI 3 inorganic perovskites have attracted significant attention due to their desirable bandgap for tandem solar cells and excellent thermal stability. However, CsPbI 3 perovskite solar cells (PSCs) still exhibit low efficiency and high energy loss due to nonradiative recombination. Herein, functionalized Ti 3 C 2 F x quantum dots (QDs) are prepared and selected as interface passivators to enhance the performance of CsPbI 3 PSCs. The systematic experimental results reveal that Ti 3 C 2 F x QDs serve as effective passivators mainly in three aspects: 1) p ‐type Ti 3 C 2 F x QDs can tune the energy level of perovskite films and provide an efficient pathway for hole transfer; 2) Ti 3 C 2 F x QDs can effectively passivate defects and reduce interfacial nonradiative recombination, and 3) Ti 3 C 2 F x QDs form a barrier layer to prevent water invasion and improve the stability of CsPbI 3 PSCs. Consequently, the champion CsPbI 3 PSC with Ti 3 C 2 F 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.