Researchers achieved a 20.92% power conversion efficiency in organic solar cells by altering the molecular packing of fused-ring electron acceptors, according to a study published in Nature Communications. The ternary device, which combined the donor polymer D18 with acceptors L8-BO and Y6-2Cl, also recorded a fill factor of 82.93%.
The team synthesized two acceptor materials, named Y6-2Cl and Y6-4Cl, by attaching bulky chlorobenzene moieties to the ends of inner side chains to reduce non-radiative energy loss. This modification enhanced solubility, raised the photoluminescence quantum yield, and altered molecular arrangement. Instead of adopting the conventional three-dimensional network structure typical of Y-series acceptors, the compounds formed an ordered, array-like packing while maintaining crystalline properties. The structural change preserved charge-transport characteristics and optimized active layer morphology, allowing a binary D18:Y6-2Cl cell to achieve a 20.0% efficiency rating.
Nan Wei and Tong Sun contributed equally to the work, collaborating across Qingdao University, Beijing Normal University, and Donghua University. Jieni Chen and Professor Wenkai Zhang from the Department of Physics at Beijing Normal University conducted transient spectral measurements for the project.
The National Natural Science Foundation of China financed the research under grants 22579096 and 52433007, with additional backing from the Natural Science Foundation of Shandong Province under grant ZR2022YQ45 and the Taishan Scholars Program under grant tstp20221121. The peer-reviewed study appeared on August 15, 2026, after receiving acceptance on July 31, 2026.
