High-Efficiency and Low-Energy- Loss Organic Solar Cells Enabled by Tuning Conformations of Dimeric Electron Acceptors

Dimeric fused-ring electron acceptors (DFREAs) have attracted much attention due to the combined advantages of their monomeric and polymeric acceptors, including a well-defined molecular structure, excellent repeatability, and stable morphology. However, the additionally introduced single-bonds during dimerization may result in a twisted backbone of DFREAs, which is detrimental to intermolecular packing and charge transport. Herein, three DFREAs are designed and synthesized, in which DFREA conformations were systematically tuned via adjusting the intensities of intramolecular noncovalent interactions (INIs) to achieve high-performance organic solar cells (OSCs). Theoretical and experimental results show that the gradual introduction of SF INIs can continuously improve molecular planarity and rigidity, resulting in reduced reorganization energies, ordered packing mode, and enhanced crystallization of DFREAs. Benefiting from the incorporation of fourfold SF INIs, DYF-TF-based binary OSCs show a record high efficiency of 18.26% with an extremely low energy loss (0.493 eV) for DFREA-based OSCs. In addition, DYF-TF-based OSCs exhibited good long-term stability with a T-80% lifetime of 2681 h, and the power conversion efficiency of the DYF-TF-based ternary device is further enhanced to 18.73%. This contribution demonstrates the great potential of the INIs strategy in achieving excellent DFREAs materials.