Streamlined One‐Step Dimerization of Small‐Molecule Acceptors for High‐Performance Organic Solar Cells

ABSTRACT

Achieving both high power conversion efficiency (PCE) and long‐term operational stability remains a formidable challenge for organic solar cells (OSCs). Dimeric small‐molecule acceptors (DSMAs), constructed by linking small‐molecule acceptor (SMA) subunits, have recently emerged as promising candidates. However, their conventional synthesis via Stille coupling necessitates multistep reactions, rendering large‐scale, low‐cost preparation impractical. Herein, we report a streamlined direct dimerization strategy that efficiently constructs core‐linked DSMAs through the condensation of bromoacetyl groups with diamine subunits, obviating the need for expensive palladium catalysts and toxic organotin reagents. By systematically varying the linking units, we synthesized a series of DSMAs with precisely tunable optical and electronic properties, demonstrating the generality of the approach. Such a direct dimerization approach effectively resolves the long‐standing trade‐off between cost‐effective synthesis and high photovoltaic performance. Consequently, the best‐performing device delivers a record‐high PCE of 20.15%, while maintaining outstanding photostability. Collectively, this work provides a versatile blueprint for the cost‐effective synthesis of stable, high‐performance DSMAs, effectively bridging the gap between molecular design and practical OSC scalability.