Highly Polar Molecules in Electron Transport Layers Achieve >20% Efficiency and Excellent Scalability in Binary Organic Solar Cells via Enhanced Charge Extraction

Abstract In high‐efficiency organic solar cells (OSCs), the electron transport layer (ETL) serves as the core component for effective carrier extraction, playing a pivotal role in device performance. In this study, a novel perylene diimide (PDI) derivative named PDINON as ETL is developed for OSCs by introducing polar C═O groups into the side chains. PDINON exhibits strong intra‐/inter‐molecular interactions and electrostatic potential. When employing PDINON as guest into the traditional interfacial layers, the new hybrid ETLs significantly improve charge transfer, accelerates carrier mobility, and minimizes trap‐assisted recombination in the device with various active layer. Particularly, using hybrid PNDIT‐F3N:PDINON, the power conversion efficiency (PCE) of the PM6:L8‐BO device reaches 19.75%, setting a new benchmark for interface modulation efficiency and consistently enhancing performance across various systems. Notably, the D18:L8‐BO system achieves the best performance of 20.17%, ranking among the best performance of binary devices. Additionally, the hybrid ETL suppresses interfacial defects, facilitates large‐scale fabrication, and achieves a PCE of 18.64% in 1 cm 2 devices, showing the top performance with reduced efficiency loss. This findings not only offer a straightforward, effective strategy for cathode interface enhancement but also propel forward the commercial viability of OSCs, underlining the transformative potential of interfacial engineering in solar technology.