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

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.

Novel C3N4-Assisted Bilateral Interface Engineering for Efficient and Stable Perovskite Solar Cells

“…Moreover, the y-CN-modified perovskite film exhibits an enlarged grain size with an average size of 765 nm, much larger than those of control (622 nm) and w-CN-modified (678 nm) perovskite films, which can be demonstrated by the size distribution in Figure S7 of the Supporting Information. The enlarged grain size means the enhanced crystallinity of the y-CN-treated CsPbIBr 2 film, , consistent with the XRD analysis, which contributes to the enhancement of light absorption of the perovskite layer. As shown in Figure g, the y-CN-modified perovskite film displays a higher absorbance than the other two films, contributing to the increase of the J sc value.…”

Recent progress in use of MXene in perovskite solar cells: for interfacial modification, work-function tuning and additive engineering

“…Recently, in June 2022, Dongfang and his colleagues 126 reported the use of fluorine-functionalized MXene QDs as a surface passivator to increase the efficiency of a CsPbI 3 perovskite. They concluded that fluorine-doped MXene sheets provide a barrier against moisture sensitivity, improve charge transfer, and further reduce nano-radiative recombination, resulting in a 20.44 percent enhancement in efficiency.…”

“…With a substantial modification of the J SC , Voc, and FF, a considerable hysteresis-free PCE enhancement from 18.31% to 21.64% of PSCs was accomplished. 126…”

“…This surface tuning not only provided a protection against moisture for the perovskite layer, but also improved the charge separation at the perovskite/ ETL interface due to a strong electric field, achieving an efficiency of 19.69 percent for 0.096 cm 2 minimodules. 125 Recently, in June 2022, Dongfang and his colleagues 126 reported the use of fluorine-functionalized MXene QDs as a surface passivator to increase the efficiency of a CsPbI 3 perovskite. They concluded that fluorine-doped MXene sheets provide a barrier against moisture sensitivity, improve charge transfer, and further reduce nano-radiative recombination, resulting in a 20.44 percent enhancement in efficiency.…”

“…With a substantial modification of the J SC , Voc, and FF, a considerable hysteresis-free PCE enhancement from 18.31% to 21.64% of PSCs was accomplished. 126 Wang et al demonstrated the potential use of Ti 3 C 2 T x as an ETL for PSC by a process method at room temperature. Oxygen plasma treatment was done to modify the surface of the Ti 3 C 2 T x .…”