Conjugated Polymer Semiconductors Enabled Multifunctional Interfacial Engineering for High‐Performance Inverted Perovskite Solar Cells

The interfacial defect challenge between perovskite and electron transport layer (ETL) in inverted perovskite solar cells have become a critical bottleneck for achieving concurrent high efficiency and stability in the process of industrialization. We developed a novel multifunctional integrated polymer semiconductor material P4N‐Cl as an interface interlayer between perovskite and [6,6]‐phenyl‐C 61 ‐butyric acid methyl ester. Various functional groups including carbonyl group, Cl atom and sp 2 ‐N atom in the polymer backbone effectively passivate defects at the perovskite interface through a synergistic coordination mechanism and significantly suppress non‐radiative recombination losses. Simultaneously, the robust interfacial binding at the heterointerface further optimizes the energy level alignment at the perovskite/ETL interface and enhances charge carrier dynamics. The inverted PSCs based on the P4N‐Cl multifunctional layer achieved a champion efficiency of 26.20% and a high open‐circuit voltage of 1.21 V. The target devices retained 96.2% and 90.2% of their initial power conversion efficiency after 2016 h aging in ambient air (40%–60% relative humidity) and 1500 h maximum power point tracking at 65°C under 1‐sun illumination in nitrogen, respectively. This “one‐stop” design provides exciting research prospects for constructing a new generation of commercially viable perovskite solar cells with high efficiency and long‐term operation stability of devices.