A Facile Direct C‐H Arylation Approach Enables Low‐Band Gap Completely Non‐Fused Ring Acceptors for High Efficiency Organic Solar Cells

ABSTRACT Developing environmentally benign and efficient non‐fused ring electron acceptors (NFREAs) with simplified molecular structures and reduced synthetic complexities is a key objective for advancing OSC technology. In conventional NFREA synthesis, typically relies on Stille/Suzuki coupling, which suffers from poor atom economy, multiple steps, high cost, and environmental concerns. Herein, we report a series of A‐D‐A type fully NFREAs, namely SN‐4, SN‐5, and SN‐6 were designed and synthesized in three steps via a direct C‐H arylation strategy that avoids fused‐ring construction and hazardous organotin reagents. These acceptors exhibit narrow optical bandgaps (∼1.44 eV) with strong near‐infrared light absorption, enabling superior light‐harvesting. Molecular dynamics simulations reveal pronounced terminal‐terminal interactions, highlighting the pivotal role of end‐group interactions in governing molecular packing. Among the series, the binary device based on PM6:SN‐6 achieves a remarkable power conversion efficiency (PCE) of 15.86% under green‐solvent processing, surpassing SN‐4 (7.85%) and SN‐5 (12.88%) owing to enhanced charge transport, low radiative energy losses, and reduced trap‐assisted recombination. This work demonstrates a sustainable, efficient, and scalable pathway for developing low‐cost, narrow‐bandgap, high‐performance NFREAs, and advancing their potential for future organic photovoltaic applications.