Achieving 20.1% Efficiency in Organic Solar Cells via Cost‐Reduced Nonfullerene Acceptors with Locally Unsymmetrical Substituents

ABSTRACT Non‐fullerene acceptors (NFAs) are critical for advancing organic solar cells (OSCs). Modulating NFA symmetry via molecular engineering effectively boosts power conversion efficiency (PCE), a key metric for OSC practicality. We designed/synthesized two new NFAs ( A‐βClδF , A‐βFδCl ) with local unsymmetrical substituents, which reduce molecular symmetry and generate a ∼1.5 Debye dipole moment, optimizing intermolecular interactions and film formation. P M6:A‐βFδCl binary OSCs achieved a 16.64% PCE, outperforming PM6:A‐βClδF (16.26%). This gain comes from better morphology, reduced charge recombination, and faster transport. Incorporating A‐βFδCl into PM6:BTP‐eC9 elevated PCE from 18.23% to 20.10%, with concurrently enhanced open circuit voltage (V OC ), short‐circuit current ( J SC ), and fill factor (FF). Notably, 19.3 cm 2 modules using A‐βFδCl retained a 16.10% PCE, bridging lab and industry. Our work confirms local unsymmetry engineering as a promising strategy for high‐efficiency, scalable NFAs.