Polyethylene Glycol‐ <scp>MXene</scp> Blend as an Interfacial Modification Layer for <i>n‐i‐p</i> Perovskite Solar Cells

Comprehensive Summary The application of two‐dimensional (2D) MXenes for interface modification has been demonstrated as an effective strategy to improve the performance of perovskite solar cells (PSCs). However, the strong van der Waals interactions among MXene nanosheets lead to aggregation and poor film uniformity during spin‐coating. To address this, we blend Ti 3 C 2 T x MXene with polyethylene glycol (PEG) as a dispersant and film‐forming agent, enabling uniform and continuous film coverage. The resulting PEG‐MXene composite forms a uniform buried interlayer between the SnO 2 ETL and the perovskite absorber, which effectively passivates interfacial defects, optimizes energy level alignment, and guides perovskite crystallization. Benefiting from this synergistic modification, the corresponding devices achieve a champion power conversion efficiency (PCE) of 24.76% along with enhanced operational stability under continuous illumination and thermal stress at 70 °C. Notably, the incorporation of PEG significantly improves the reproducibility of device fabrication, enabling a PCE of 20.06% in large‐area devices (1.0 cm 2 ), thereby affirming its potential for scalable manufacturing of PSCs.