Recent advances of Imide-functionalized polymer Donors for Non-fullerene Solar Cells

In recent years, there has been a shift towards using nonfullerene electron acceptors in organic solar cells (OSCs) as a replacement for fullerene derivatives. This change requires polymer donors that possess compatible physical properties, such as absorption range, HOMO energy level, miscibility, and crystallinity. Moreover, the high cost and poor batch-to-batch reproducibility of polymer donors also hinder future large-scale manufacturing. These emphasize the need to explore alternative types of polymer donors. The imide-functionalized building units possess several key attributes that make their polymers highly promising for non-fullerene OSCs. These attributes include ease of synthesis, strong electron-withdrawing ability, rigid and co-planar structure, and the ability to easily tune solubility through imide side chains. In this review, we summarized the synthetic routes of imide building units, and the struc-tural evolution of imide-functionalized polymer donors by focusing on the effects of polymer structure on their physical, optoelec-tronic, and photovoltaic properties. We hope that this mini-review will serve as a catalyst for future research on imide-functionalized polymers toward high-performance, cost-effective, and durable organic solar cells (OSCs).