Easily Available High‐Performance Organic Solar Cells by Regulating Phenylalkyl Side Groups of Non‐Fused Ring Electron Acceptors

Abstract Although non‐fused ring electron acceptors (NFREAs) have received increasing attention due to their relatively low synthetic costs, the achievement of high efficiencies strongly depends on tedious pre‐ or/and post‐treatments to refine the active layers, which in turn greatly increase fabrication complexity and expense of organic solar cells (OSCs). Nowadays most of the available as‐cast devices based on NFREAs are below 12% efficiencies. Herein, phenylalkyl category side groups (CnPh) are employed to construct new NFREAs named BOR‐CnPh (n = 3, 4, and 6), which exhibit inherently decent molecular aggregation and thus exclude additional treatments from device fabrication. The modified alkyl spacers of CnPh side groups not only trigger different aggregation of the acceptors, but also regulate the interaction conformations of donor (D) and acceptor (A), and thus D/A interactions. Encouragingly, the pristine PBDB‐T:BOR‐C4Ph blend delivers intrinsic fibrous networks with dominating face‐on orientation, which yields an optimal efficiency up to 13.12%, and ranks as the highest value among as‐cast OSCs based on NFREAs. This research provides a practical strategy to control molecular aggregations, interactions, and pristine heterojunction morphologies for easily available and high‐performance organic photovoltaics.