Fluorinated Perylene Diimide Dimer for Organic Solar Cells as Non‐fullerene Acceptor

Fluorination has been widely applied in modification of photovoltaic materials, especially fused ring electron acceptors and polymer donors, but rarely in perylene diimides (PDIs)‐based acceptors. The di‐PDI‐2F is facilely obtained by a one‐step synthesis via stannylation/Stille cross‐coupling reaction. Furtherly, we conducted a comparison study between the newly designed fluorinated PDI dimer di‐PDI‐2F and its non‐fluorinated analogue di‐PDI. After fluorination, the energy levels are downshifted, and the absorption spectrum is greatly blue shifted. When paired with a medium band‐gap donor PM6, di‐PDI‐2F based organic solar cells show reduced trap‐assisted and bimolecular recombination as well as better exciton dissociation and charge collection efficiency than that of di‐PDI based ones, thus a greatly enhanced fill factor (FF), together with improved open circuit voltage (Voc) and short circuit current density (Jsc), leading to a superior power conversion efficiency. This fact suggests the potential of fluorination strategy on PDI based acceptors.