Cesium-Doped Ti 3 C 2 T x MXene for Efficient and Thermally Stable Perovskite Solar Cells

Ti3C2Tx MXenes have been shown to be a promising candidate for use in various applications. Herein, we prepared functionalized Ti3C2Tx MXene nanosheets doped with cesium (Cs) and introduced them into lead iodide (PbI2) precursor solution for perovskite solar cells (PSCs) through a two-step deposition method. Our theoretical and experimental analysis revealed that Cs plays an important role in improving the perovskite crystallization and thus leading to enlarged crystal grains, long-lived carrier lifetimes, and reduced charge recombination as compared to the devices fabricated without and with undoped Ti3C2Tx MXene. PSCs integrated with Cs doped Ti3C2Tx MXene delivered a high photovoltaic efficiency of up to 21.57% with excellent thermal stability. The incorporation of Cs-Ti3C2Tx paves the way to further improve the photovoltaic performance and thermal stability of PSCs.