Efficient and stable all-small-molecule solar cells enabled by incorporating a designed giant molecule acceptor

All-small-molecule organic solar cells (all-SMOSCs) exhibit tremendous potential for commercialization thanks to their unique advantages, including a well-defined molecular structure, ease of synthesis, and batch-to-batch reproducibility. However, both high power conversion efficiencies (PCEs) and long-term stability indexes are still lagging behind those of polymer based solar cells. Herein, we designed a giant molecule acceptor Se-Giant and incorporated it into the MPhS-C2:BTP-eC9 binary system. The addition of the Se-Giant complemented the absorption spectra, modified blend micromorphology, and improved charge transport and extraction properties, leading to a promising PCE of 18.16% with excellent film thickness tolerance and high operational stability in all-SMOSCs. Moreover, we successfully demonstrated the feasibility of recycling active layer materials, including Se-Giant, MPhS-C2, and BTP-eC9, which indicates the favorable sustainability. The presented findings are of great significance for highlighting the advantages of all-small molecule systems for commercial applications. A highly efficient and stable all-small-molecule system with excellent thickness tolerance and recycling capability has been developed, by integrating a new giant molecule acceptor (Se-Giant) into the MPhS-C2:BTP-eC9 binary system.