Employing Fully Asymmetric Building Block Toward High‐Performance Stretchable Active Layer for Organic Solar Cells

Stretchable organic solar cells (SOSCs) show remarkable promise to provide energy to wearable electronic devices. Despite the rigid organic solar cells (OSCs) have made power conversion efficiencies (PCEs) of over 20%, tensile properties of these high‐performance active layers are often compromised and thus do not make them suitable for stretchable wearable electronic devices. In this regard, we designed a novel donor polymer, PBDTT‐Fully‐asy, with the fully asymmetric structure of the backbone and side chains, and incorporated it in PM6:Y6 blend to construct a stretchable light‐harvesting active layer. Compared with a symmetric structure, the center of the fully asymmetric fused‐ring is shifted, which can weaken self‐aggregation. In addition, strong twisting and disruption of the aggregation can occur due to the side chain of the rigid benzene ring. Furthermore, the improved backbone coplanarity and increased π‐conjugation are advantageous for improving the charge transfer ability and photovoltaic performance. Our obtained results suggest that incorporation of PBDTT‐Fully‐asy (10 wt%) can efficiently improve the stretchability and photovoltaic performance. Our proposed molecular design approach will contribute to the acceleration of high‐performance stretchable.