MXene-Driven Augmentation of Hole-Selective Self-Assembled Monolayer Interfaces for Efficient and Stable p-i-n Perovskite Solar Cells

Abstract

The hole-selective interface in planar p-i-n architecture devices serves a multifaceted role, functioning as a robust substrate for the growth of perovskite absorber layers, facilitating efficient hole-carrier extraction, and suppressing electron transport-related recombination. However, as a buried interface, it remains non-exposed, characterized by ambiguous electronic states and a significant presence of defective antisites at the perovskite absorber and indium tin oxide anode junctions. Although self-assembled monolayers (SAMs) have been proposed as standalone hole-selective interfaces, their limited electrical properties fail to fully meet the demands of high-performance p-i-n perovskite solar cells (PSCs). In this study, we functionalize the SAM-based hole-selective interface with MXene (Ti3C2Tx) nanosheets, thereby enhancing electrical conductivity, anode work function, and surface properties to mitigate the challenges associated with the buried interface. The integration of MXene nanosheets promotes efficient carrier transport, reduces interfacial trap density at the perovskite interfaces, and improves film quality while suppressing non-radiative recombination. As a result, the inclusion of MXene in the SAM-based hole-selective interface significantly enhances the power conversion efficiency (PCE) from 20.86% to 23.25% in CsFAPbI3-based p-i-n perovskite solar cells. Moreover, the MXene nanosheets contribute to increased hydrophobicity of the SAM/ITO surface, enabling the device to retain over 91% of its initial PCE under ambient conditions for 800 hours. These findings underscore the potential of MXene as a novel component in the design of hole-selective buried interfaces, paving the way for substantial improvements in both photovoltaic performance and long-term stability of p-i-n PSCs.