Recent Progress in Dimerized Small-Molecular Acceptors for Organic Solar Cells.

Organic solar cells (OSCs) have witnessed significant advancements in recent years, largely propelled by innovations in material design and device engineering. Among the emerging materials, dimerized small-molecule acceptors (DSMAs) have garnered considerable attention due to their unique advantages. For instance, DSMAs can directly inherit the excellent optoelectronic properties of corresponding small-molecule monomers. Moreover, their relatively larger molecular weight can effectively suppress molecular diffusion in the active layer, thereby enhancing the stability of OSCs. Compared to polymer acceptors, DSMAs have a well-defined structure, which is free from batch-to-batch variability, greatly enhancing the reproducibility of devices. This review comprehensively summarizes recent progress in DSMAs for OSCs, with a focus on their two primary linkage configurations: conjugative and non-conjugative connections. Additionally, the impact of various connection positions (including core-unit, end-group, and side-chain connection sites) on molecular packing, optoelectronic properties, and device performance is systematically reviewed. The review highlights the critical role of DSMAs in addressing key challenges in OSCs, such as photodegradation and morphological instability, while balancing power conversion efficiency and long-term stability. By consolidating recent breakthroughs and identifying future research directions, this work aims to provide valuable insights into the rational design of DSMAs, paving the way for the development of high-performance and commercially viable OSCs.