Design High-Performance Stretchable Light-Harvesting Polymers for Organic Solar Cells via Synergistic Effect of Flexible Alkyl Segment and Hydrogen Bond.

Stretchable organic solar cells (SOSCs) have great application prospects to serve as energy supply systems, which can be fully incorporated with wearable electronic devices to achieve truly integrated systems that are fully stretchable and wearable. However, the stretchable polymer light-harvesting active layer has not been successfully developed, which limits the development of stretchable organic solar cells. In this regard, a series of stretchable light-harvesting donor and acceptor polymers are designed and synthesized by introducing amide units with flexible alkyl segments and hydrogen bonds as the third component into the PM6 and PY-IT based conjugated polymer backbones. Hydrogen bonds and flexible alkyl segments can dissipate tensile stress for high stretchability. In addition, hydrogen bonds can reduce the impact of flexible alkyl segments on intermolecular stacking, thus maintaining good photovoltaic performance. The obtained results suggest that the incorporation of amide units (5 mol% content) into the donor polymer can efficiently improve the stretchability without compromising the photovoltaic performance. This study provides an understanding of the impact of amide units on properties, offering another entry to the molecular design guidelines for high-performance stretchable light-harvesting polymers, developing high-performance stretchable organic solar cells, and further promoting the development of wearable electronic devices.